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Sample records for 6-4 pyrimidone photoproducts

  1. Electronic structure of (6-4) DNA photoproduct repair involving a non-oxetane pathway.

    PubMed

    Domratcheva, Tatiana; Schlichting, Ilme

    2009-12-16

    Mutagenic pyrimidine-pyrimidone (6-4) photoproducts are one of the main DNA lesions induced by solar UV radiation. These lesions can be photoreversed by (6-4) photolyases. The originally published repair mechanism involves rearrangement of the lesion into an oxetane intermediate upon binding to the (6-4) photolyase, followed by light-induced electron transfer from the reduced flavin cofactor. In a recent crystallographic study on a (6-4) photoproduct complexed with (6-4) photolyase from Drosophila melanogaster no oxetane was observed, raising the possibility of a non-oxetane repair mechanism. Using quantum-chemical calculations we find that in addition to repair via an oxetane, a direct transfer of the hydroxyl group results in reversal of the radical anion (6-4) photoproduct. In both mechanisms, the transition states have high energies and correspond to avoided crossings of the ground and excited electronic states. To study whether the repair can proceed via these state crossings, the excited-state potential energy curves were computed. The radical excitation energies and accessibility of the nonadiabatic repair path were found to depend on hydrogen bonds and the protonation state of the lesion. On the basis of the energy calculations, a nonadiabatic repair of the excited (6-4) lesion radical anion via hydroxyl transfer is probable. This repair mechanism is in line with the recent structural data on the (6-4) photolyase from D. melanogaster . PMID:19921821

  2. Removal of UV light-induced pyrimidine-pyrimidone(6-4) products from Escherichia coli DNA requires the uvrA, uvrB, and urvC gene products.

    PubMed Central

    Franklin, W A; Haseltine, W A

    1984-01-01

    Ultraviolet light induces the formation of cyclobutane pyrimidine dimers and pyrimidine- pyrimidone (6-4) photoproducts in cellular DNA. In Escherichia coli, the uvrA, uvrB, and uvrC genes are necessary for excision of cyclobutane dimers. To determine whether the uvrABC gene products are required for (6-4) product removal from DNA, a sensitive HPLC assay was developed that allows the separation and quantitation of both types of photoproducts. Both the T T cyclobutane dimer and the T-C(6-4) product were completely removed from the DNA after 2 hr of repair in a wild-type strain. Both products were also removed in the wild-type strain in the presence of chloramphenicol, an inhibitor of protein synthesis. No decrease in the amount of either T T cyclobutane dimer or of T-C(6-4) products was observed in strains that were deficient in any one of the three uvr gene products under similar conditions. We conclude the uvrABC enzyme complex is required for excision of (6-4) photoproducts from E. coli DNA. PMID:6374666

  3. Detection, purification and characterization of a protein that binds the (6-4) photoproduct-containing DNA in HeLa cells.

    PubMed

    Fujiwara, Y; Masutani, C; Hanaoka, F; Iwai, S

    1997-01-01

    HeLa cell proteins that bind DNA containing the pyrimidine(6-4)pyrimidone photoproduct were detected by the electrophoretic mobility shift assay using synthetic oligonucleotide duplexes as probes. The major species was purified to near homogeneity, and the amino acid sequences of the proteolytic peptides revealed that it was the human damage-specific DNA-binding protein, which was reported previously. The substrate specificity of this protein was determined using damaged or modified DNA duplexes. PMID:9586107

  4. Cloning and characterization of a gene (UVR3) required for photorepair of 6-4 photoproducts in Arabidopsis thaliana.

    PubMed Central

    Nakajima, S; Sugiyama, M; Iwai, S; Hitomi, K; Otoshi, E; Kim, S T; Jiang, C Z; Todo, T; Britt, A B; Yamamoto, K

    1998-01-01

    UV radiation induces two major classes of pyrimidine dimers: the pyrimidine [6-4] pyrimidone photoproduct (6-4 product) and the cyclobutane pyrimidine dimer (CPD). Many organisms produce enzymes, termed photolyases, that specifically bind to these damage products and split them via a UV-A/blue light-dependent mechanism, thereby reversing the damage. These photolyases are specific for either CPDs or 6-4 products. A gene that expresses a protein with 6-4 photolyase activity in vitro was recently cloned from Drosophila melanogaster and Xenopus laevis. We report here the isolation of a homolog of this gene, cloned on the basis of sequence similarity, from the higher plant Arabidopsis thaliana. This cloned gene produces a protein with 6-4 photolyase activity when expressed in Escherichia coli. We also find that a previously described mutant of Arabidopsis (uvr3) that is defective in photoreactivation of 6-4 products carries a nonsense mutation in this 6-4 photolyase homolog. We have therefore termed this gene UVR3. Although homologs of this gene have previously been shown to produce a functional 6-4 photolyase when expressed in heterologous systems, this is the first demonstration of a requirement for this gene for photoreactivation of 6-4 products in vivo. PMID:9421527

  5. Purification of a novel UV-damaged-DNA binding protein highly specific for (6-4) photoproduct.

    PubMed

    Wakasugi, M; Abe, Y; Yoshida, Y; Matsunaga, T; Nikaido, O

    1996-03-15

    UV damage-specific binding proteins are considered to play important roles in early responses of cells irradiated with UV, including damage recognition in the DNA repair process. We have surveyed nuclear and cytoplasmic proteins which bind selectively to UV-irradiated DNA using an electrophoretic mobility shift assay. We detected four distinct binding activities with different mobilities in fractions separated from HeLa cells by heparin chromatography. Three of them were found in nuclear extracts and one in cytoplasmic extracts. We purified one of the binding factors from nuclear extracts to homogeneity, which was designated NF-10 (the 10th fraction of nuclear extract on heparin chromatography). It migrated as a 40 kDa polypeptide in SDS-PAGE, and bound to UV-irradiated double- stranded DNA but not to unirradiated DNA. The binding pattern of the NF-10 protein to DNA irradiated with UV corresponded to the induction kinetics of (6-4) photoproduct. Removal of (6-4) photoproducts from UV- irradiated DNA by (6-4) photoproduct-specific photolyase diminished the binding of NF-10 protein. These results suggest that the NF-10 protein binds to UV-damaged DNA through (6-4) photoproduct. Immunoblot analysis using a monoclonal antibody revealed that the NF-10 protein was expressed in cell lines from all complementation groups of xeroderma pigmentosum, indicating that the NF-10 protein is a novel UV-damaged-DNA binding protein. PMID:8604344

  6. Repair of a Dimeric Azetidine Related to the Thymine-Cytosine (6-4) Photoproduct by Electron Transfer Photoreduction.

    PubMed

    Fraga-Timiraos, Ana B; Lhiaubet-Vallet, Virginie; Miranda, Miguel A

    2016-05-10

    Photolyases are intriguing enzymes that take advantage of sunlight to restore lesions like cyclobutane pyrimidine dimers or (6-4) photoproducts. This work focused on the photoreductive process responsible for splitting of the azetidine ring proposed to occur during (6-4) photoproduct repair at a thymine-cytosine sequence. A model compound formed by photocycloaddition between thymine and 6-azauracil has been designed to mimic the elusive azetidine intermediate. The photoinduced electron transfer process has been investigated by means of steady-state and time-resolved fluorescence using photosensitizers with oxidation potentials in the singlet excited state ranging from -3.3 to -2.1 V vs. SCE. Azetidine ring splitting and recovery of "repaired" bases were proven by HPLC analysis. PMID:27061458

  7. The in situ repair kinetics of epidermal thymine dimers and 6-4 photoproducts in human skin types I and II.

    PubMed

    Young, A R; Chadwick, C A; Harrison, G I; Hawk, J L; Nikaido, O; Potten, C S

    1996-06-01

    We assessed the in situ time-dependent loss of epidermal thymine dimers and 6-4 photoproducts in skin types I and II after exposure to two minimal erythema doses of solar-simulating radiation on previously unexposed buttock skin. Using quantitative image analysis, we evaluated biopsy sections stained with monoclonal antibodies. We then made comparisons, in the same volunteers, with unscheduled DNA synthesis, which is a direct marker of overall excision repair. Removal of thymine dimers was slow (half-life = 33.3 h), with high levels of lesions still present 24 h post-irradiation; some lesions were still present at 7 d. In contrast, removal of 6-4 photoproducts was rapid (half-life = 2.3 h), the decay kinetics of which correlated better with the decline in epidermal unscheduled DNA synthesis (half-life = 7.1 h). These data show that as in mouse, monkey, and in vitro models, the 6-4 photolesion is repaired preferentially in human epidermis in situ. They also raise the possibility that poor thymine dimer repair may be a feature of skin types I and II, who are more prone to skin cancer than are types III and IV. There was an inverse relationship between the onset of erythema and 6-4 photoproduct repair, suggesting that this repair process initiates erythema. PMID:8752675

  8. The (6-4) Dimeric Lesion as a DNA Photosensitizer.

    PubMed

    Vendrell-Criado, Victoria; Rodríguez-Muñiz, Gemma M; Lhiaubet-Vallet, Virginie; Cuquerella, M Consuelo; Miranda, Miguel A

    2016-07-01

    Based on our previous investigations into the photophysical properties of the 5-methyl-2-pyrimidone (Pyo) chromophore, we now extend our studies to the photobehavior of the dimeric (6-4) thymine photoproducts (6-4 PP) to evaluate their capability to act as instrinsic DNA photosensitizers. The lesion presents significant absorption in the UVB/UVA region, weak fluorescence emission, a singlet-excited-state energy of approximately 351 kJ mol(-1) , and a triplet-excited-state energy of 297 kJ mol(-1) . Its triplet transient absorption has a maximum at 420-440 nm, a lifetime of around 7 μs, and a high formation quantum yield, ΦISC =0.86. This species is efficiently quenched by thymidine. Its DNA photosensitizing properties are demonstrated by a series of experiments run on a pBR322 plasmid. The lesion photoinduces both single-strand breaks and the formation of cyclobutane thymine dimers. Altogether, these results show that, the substitution of the pyrimidone ring at C4 by a 5-hydroxy-5,6-dihydrothymine does not cancel out the photosensitization properties of the chromophore. PMID:26990589

  9. Fully functional global genome repair of (6-4) photoproducts and compromised transcription-coupled repair of cyclobutane pyrimidine dimers in condensed mitotic chromatin

    SciTech Connect

    Komura, Jun-ichiro; Ikehata, Hironobu; Mori, Toshio; Ono, Tetsuya

    2012-03-10

    During mitosis, chromatin is highly condensed, and activities such as transcription and semiconservative replication do not occur. Consequently, the condensed condition of mitotic chromatin is assumed to inhibit DNA metabolism by impeding the access of DNA-transacting proteins. However, about 40 years ago, several researchers observed unscheduled DNA synthesis in UV-irradiated mitotic chromosomes, suggesting the presence of excision repair. We re-examined this subject by directly measuring the removal of UV-induced DNA lesions by an ELISA and by a Southern-based technique in HeLa cells arrested at mitosis. We observed that the removal of (6-4) photoproducts from the overall genome in mitotic cells was as efficient as in interphase cells. This suggests that global genome repair of (6-4) photoproducts is fully functional during mitosis, and that the DNA in mitotic chromatin is accessible to proteins involved in this mode of DNA repair. Nevertheless, not all modes of DNA repair seem fully functional during mitosis. We also observed that the removal of cyclobutane pyrimidine dimers from the dihydrofolate reductase and c-MYC genes in mitotic cells was very slow. This suggests that transcription-coupled repair of cyclobutane pyrimidine dimers is compromised or non-functional during mitosis, which is probably the consequence of mitotic transcriptional repression. -- Highlights: Black-Right-Pointing-Pointer Global genome repair of (6-4) photoproducts is fully active in mitotic cells. Black-Right-Pointing-Pointer DNA in condensed mitotic chromatin does not seem inaccessible or inert. Black-Right-Pointing-Pointer Mitotic transcriptional repression may impair transcription-coupled repair.

  10. A Light-Dependent Pathway for the Elimination of UV-Induced Pyrimidine (6-4) Pyrimidinone Photoproducts in Arabidopsis.

    PubMed Central

    Chen, J. J.; Mitchell, D. L.; Britt, A. B.

    1994-01-01

    Light-dependent repair of UV-induced cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6-4) pyrimidinone dimers (6-4 products) was investigated in an excision repair-deficient Arabidopsis mutant. As previously described, exposure to broad-spectrum lighting was found to greatly enhance the rate of repair of CPDs. We demonstrate that 6-4 products are also efficiently eliminated in a light-dependent manner and that this photoreactivation of 6-4 products occurs independently of the previously described 6-4 product dark repair pathway. The light-dependent repair of both 6-4 products and CPDs occurs in the presence of blue light (435 nm) but not upon exposure to light of longer wavelengths. We also found that high-level expression of the CPD-specific photoreactivating activity in the Arabidopsis seedling requires induction by exposure to light prior to as well as during the period of repair while the 6-4 photoreactivating activity is constitutively expressed. This differential regulation of the photoreactivating activities suggests that the Arabidopsis seedling produces at least two distinct photolyases: one specific for CPDs and the other specific for 6-4 products. PMID:12244273

  11. The Reactivity of Thymine and Thymidine 5,6-Epoxides with Organometallic Reagents - A Route to Thymidine (6-4) Photoproduct Analogues.

    PubMed

    Wrigstedt, Pauli; Kavakka, Jari; Heikkinen, Sami; Nieger, Martin; Räisänen, Minna; Repo, Timo

    2016-05-01

    This report describes an efficient procedure for the generation and isolation of various thymine and thymidine 5,6-epoxides from the corresponding trans-5,6-bromohydrins by reaction with triethylamine. The quantitative isolation of the epoxides, accomplished by solvent precipitation of triethylamine hydrobromide, enabled their regiospecific ring-opening at C6 position by organometallic nucleophiles. The reaction was amenable to a broad range of alkyl, aryl, alkenyl, and alkynyl organomagnesium, -zinc, -aluminum, or -boron reagents, although the reactivity was strongly affected by the electronic effects of N3 protecting group. Additionally, the reaction featured excellent cis-diastereoselectivity providing access to C6-carbon-functionalized dihydrothymidine cis-alcohols, which are synthetic derivatives of UV-induced DNA lesions, namely, thymidine (6-4) photoproducts. PMID:27080560

  12. Functional Conversion of CPD and (6-4) Photolyases by Mutation.

    PubMed

    Yamada, Daichi; Dokainish, Hisham M; Iwata, Tatsuya; Yamamoto, Junpei; Ishikawa, Tomoko; Todo, Takeshi; Iwai, Shigenori; Getzoff, Elizabeth D; Kitao, Akio; Kandori, Hideki

    2016-08-01

    Ultraviolet (UV) light from the sun damages DNA by forming a cyclobutane pyrimidine dimer (CPD) and pyrimidine(6-4)pyrimidone photoproducts [(6-4) PP]. Photolyase (PHR) enzymes utilize near-UV/blue light for DNA repair, which is initiated by light-induced electron transfer from the fully reduced flavin adenine dinucleotide chromophore. Despite similar structures and repair mechanisms, the functions of PHR are highly selective; CPD PHR repairs CPD, but not (6-4) PP, and vice versa. In this study, we attempted functional conversion between CPD and (6-4) PHRs. We found that a triple mutant of (6-4) PHR is able to repair the CPD photoproduct, though the repair efficiency is 1 order of magnitude lower than that of wild-type CPD PHR. Difference Fourier transform infrared spectra for repair demonstrate the lack of secondary structural alteration in the mutant, suggesting that the triple mutant gains substrate binding ability while it does not gain the optimized conformational changes from light-induced electron transfer to the release of the repaired DNA. Interestingly, the (6-4) photoproduct is not repaired by the reverse mutation of CPD PHR, and eight additional mutations (total of 11 mutations) introduced into CPD PHR are not sufficient. The observed asymmetric functional conversion is interpreted in terms of a more complex repair mechanism for (6-4) repair, which was supported by quantum chemical/molecular mechanical calculation. These results suggest that CPD PHR may represent an evolutionary origin for photolyase family proteins. PMID:27431478

  13. Structural Changes of the Active Center during the Photoactivation of Xenopus (6-4) Photolyase.

    PubMed

    Yamada, Daichi; Yamamoto, Junpei; Zhang, Yu; Iwata, Tatsuya; Hitomi, Kenichi; Getzoff, Elizabeth D; Iwai, Shigenori; Kandori, Hideki

    2016-02-01

    Photolyases (PHRs) repair the UV-induced photoproducts, cyclobutane pyrimidine dimer (CPD) or pyrimidine-pyrimidone (6-4) photoproduct [(6-4) PP], restoring normal bases to maintain genetic integrity. CPD and (6-4) PP are repaired by substrate-specific PHRs, CPD PHR and (6-4) PHR, respectively. Flavin adenine dinucleotide (FAD) is the chromophore of both PHRs, and the resting oxidized form (FAD(ox)), at least under in vitro purified conditions, is first photoconverted to the neutral semiquinoid radical (FADH(•)) form, followed by photoconversion into the enzymatically active fully reduced (FADH(-)) form. Previously, we reported light-induced difference Fourier transform infrared (FTIR) spectra corresponding to the photoactivation process of Xenopus (6-4) PHR. Spectral differences between the absence and presence of (6-4) PP were observed in the photoactivation process. To identify the FTIR signals where these differences appeared, we compared the FTIR spectra of photoactivation (i) in the presence and absence of (6-4) PP, (ii) of (13)C labeling, (15)N labeling, and [(14)N]His/(15)N labeling, and (iii) of H354A and H358A mutants. We successfully assigned the vibrational bands for (6-4) PP, the α-helix and neutral His residue(s). In particular, we assigned three bands to the C ═ O groups of (6-4) PP in the three different redox states of FAD. Furthermore, the changed hydrogen bonding environments of C ═ O groups of (6-4) PP suggested restructuring of the binding pocket of the DNA lesion in the process of photoactivation. PMID:26719910

  14. Resistance of the genome of Escherichia coli and Listeria monocytogenes to irradiation evaluated by the induction of cyclobutane pyrimidine dimers and 6-4 photoproducts using gamma and UV-C radiations

    NASA Astrophysics Data System (ADS)

    Beauchamp, S.; Lacroix, M.

    2012-08-01

    The effect of gamma and UV-C irradiation on the production of cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts (6-4 PPs) in DNA was investigated to compare the natural resistance of the genome of a Gram-positive bacterium and a Gram-negative bacterium against irradiation. Solution of pure DNA and bacterial strains Listeria monocytogenes and Escherichia coli were irradiated using gamma and UV-C rays. Extracted DNA from bacteria and pure DNA samples were then analysed by ELISA using anti-CPDs and anti-6-4 PPs monoclonal antibodies. The results show that gamma rays, as well as UV-C rays, induce the formation of CPDs and 6-4 PPs in DNA. During UV-C irradiation, the three samples showed a difference in their sensitivity against formation of CPDs (P≤0.05). Pure DNA was the most sensitive while the genome of L. monocytogenes was the most resistant. Also during UV-C irradiation, the genome of L. monocytogenes was the only one to show a significant resistance against formation of 6-4 PPs (P≤0.05). During gamma irradiation, for both types of lesion, pure DNA and the genome of E. coli did not show significant difference in their sensitivity (P>0.05) while the genome of L. monocytogenes showed a resistance against formation of CPDs and 6-4 PPs.

  15. The significance of the Dewar valence photoisomer as a UV radiation-induced DNA photoproduct in marine microbial communities.

    PubMed

    Meador, Jarah A; Baldwin, Amy J; Pakulski, J Dean; Jeffrey, Wade H; Mitchell, David L; Douki, Thierry

    2014-06-01

    Induction of pyrimidine dimers in DNA by solar UV radiation has drastic effects on microorganisms. To better define the nature of these DNA photoproducts in marine bacterioplankton and eukaryotes, a study was performed during a cruise along a latitudinal transect in the Pacific Ocean. The frequency of all possible cyclobutane pyrimidine dimers, pyrimidine (6-4) pyrimidone photoproducts (64PPs) and their related Dewar valence isomers (DEWs) was determined by high-performance liquid chromatography-mass spectrometry. Studied samples were bacterioplankton and eukaryotic fractions isolated from sea water either collected before sunrise or exposed to ambient sunlight from sunrise to sunset. Isolated DNA dosimeters were also exposed to daily sunlight for comparison purposes. A first major result was the observation in all samples of large amounts of DEWs, a class of photoproducts rarely considered outside photochemical studies. Evidence was obtained for a major role of UVA in the formation of these photoisomerization products of 64PPs. Considerations on the ratio between the different classes of photoproducts in basal and induced DNA damage suggests that photoenzymatic repair (PER) is an important DNA repair mechanism used by marine microorganisms occupying surface seawater in the open ocean. This result emphasizes the biological role of DEWs which are very poor substrate for PER. PMID:24517516

  16. Combined QM/MM investigation on the light-driven electron-induced repair of the (6-4) thymine dimer catalyzed by DNA photolyase.

    PubMed

    Faraji, Shirin; Groenhof, Gerrit; Dreuw, Andreas

    2013-09-01

    The (6-4) photolyases are blue-light-activated enzymes that selectively bind to DNA and initiate splitting of mutagenic thymine (6-4) thymine photoproducts (T(6-4)T-PP) via photoinduced electron transfer from flavin adenine dinucleotide anion (FADH(-)) to the lesion triggering repair. In the present work, the repair mechanism after the initial electron transfer and the effect of the protein/DNA environment are investigated theoretically by means of hybrid quantum mechanical/molecular mechanical (QM/MM) simulations using X-ray structure of the enzyme-DNA complex. By comparison of three previously proposed repair mechanisms, we found that the lowest activation free energy is required for the pathway in which the key step governing the repair photocycle is electron transfer coupled with the proton transfer from the protonated histidine, His365, to the N3' nitrogen of the pyrimidone thymine. The transfer simultaneously occurs with concerted intramolecular OH transfer without formation of an oxetane or isolated water molecule intermediate. In contrast to previously suggested mechanisms, this newly identified pathway requires neither a subsequent two-photon process nor electronic excitation of the photolesion. PMID:23915283

  17. Synthesis and acetylcholinesterase inhibitory activity of several pyrimidone analogues of huperzine A

    SciTech Connect

    Kozlkowski, A.P.; Campiani, G.; Saxena, A.; Doctor, S.P.

    1995-12-31

    Synthesis of four new pyrimidone analogues of the acetyicholinesterase (AChE) inhibitor huperzine A are reported together with the inhibitory potendes of these compounds for foetal bovine calf serum AChE; t3-lactone formation followed by a thermal cycloreversion reaction serves as the key step for introduction of the ethylidene appendage of analogue 12 in the stereochemically correct form.

  18. Role of the carbonyl group of the (6–4) photoproduct in the (6–4) photolyase reaction†

    PubMed Central

    Yamamoto, Junpei; Hitomi, Kenichi; Hayashi, Ryosuke; Getzoff, Elizabeth D.; Iwai, Shigenori

    2009-01-01

    The (6–4) photoproduct, which is one of the major UV-induced DNA lesions, causes carcinogenesis with high frequency. The (6–4) photolyase is a flavoprotein that can restore this lesion to the original bases, but its repair mechanism has not been elucidated. In this study, we focused on the interaction between the enzyme and the 3’ pyrimidone component of the (6–4) photoproduct, and prepared a substrate analog in which the carbonyl group, a hydrogen-bond acceptor, was replaced with an imine, a hydrogen-bond donor, to investigate the involvement of this carbonyl group in the (6–4) photolyase reaction. UV irradiation of oligodeoxyribonucleotides containing a single thymine–5-methylisocytosine site yielded products with absorption bands at wavelengths longer than 300 nm, similar to those obtained from the conversion of the TT site to the (6–4) photoproduct. The nuclease digestion, MALDI-TOF mass spectrometry, and the instability of the products indicated the formation of the 2-iminopyrimidine-type photoproduct. Analyses of the reaction and the binding of the (6–4) photolyase using these oligonucleotides revealed that this imine analog of the (6–4) photoproduct was not repaired by the (6–4) photolyase, although the enzyme bound to the oligonucleotide with considerable affinity. These results indicate that the carbonyl group of the 3’ pyrimidone ring plays an important role in the (6–4) photolyase reaction. Based on these results, we discuss the repair mechanism. PMID:19715341

  19. Sketching the historical development of pyrimidones as the inhibitors of the HIV integrase.

    PubMed

    Patel, Rahul V; Keum, Young-Soo; Park, Se Won

    2015-06-01

    Heterocyclic substances perform a very unique role in drug design and discovery. This article provides the primary objectives of the analysis within pyrimidine centered new heterocyclic elements chronologically from their finding focusing on one of the essential enzyme of HIV virus particle that is integrase upon suppressing its strand transfer function. The class of compounds reviewed here includes bicyclic pyrimidines, dihydroxypyrimidines, pyrimidine-2,4-dinones, N-methylpyrimidones, pyranopyrimidine, pyridine-quinoline conjugates, pyrimidine-2-carboxamides, N-3 hydroxylated pyrimidine-2,4-diones as well as their various substituted analogues. Such initiatives released an effective drug Raltegravir as a first FDA approved anti-HIV integrase inhibitor as well as several of its derivatives along with other pyrimidones is under clinical or preclinical growth. Some of the provided scaffolds indicated dual anti-HIV efficacies against HIV reverse transcriptase and integrase enzymes at both cites as 3'-processing and strand transfer, while several scaffolds exhibited potency against Raltegravir resistant HIV mutant strains determining themselves a potent class of compounds having appealing upcoming implementations. Connections of the new compounds' molecular structure and HIV viral target has been overviewed to be able to accomplish further growth of promising anti-HIV agents in future drug discovery process. PMID:25084622

  20. Quantum chemical study of the enzymatic repair of T(6-4)C/C(6-4)T UV-photolesions by DNA photolyases.

    PubMed

    Faraji, Shirin; Wirz, Lukas; Dreuw, Andreas

    2013-08-26

    Several strategies have evolved to repair one of the abundant UV radiation-induced damages caused to DNA, namely the mutagenic pyrimidine (6-4) pyrimidone photolesions. DNA (6-4)-photolyases are enzymes repairing these lesions by a photoinitiated electron transfer. An important aspect of a possible repair mechanism is its generality and transferability to different (6-4) lesions. Therefore, previously suggested mechanisms for the repair of the T(6-4)T lesion are here transferred to the T(6-4)C and C(6-4)T lesions and investigated theoretically using quantum chemical methods. Despite the different functional groups of the pyrimidine bases involved, a general valid molecular mechanism was identified, in which the initial step is an electron transfer coupled to a proton transfer from the protonated HIS365 to the N3(') nitrogen of the 3(') pyrimidine, followed by an intramolecular OH/NH2 transfer in one concerted step, which does not require an oxetane/azetidine or isolated water/ammonia intermediate. PMID:23821498

  1. Etude par spectrometrie infrarouge et Raman de la triméthyl-4,5,6 pyrimidone-2 et de son chlorhydrate. Complexation par les halogenures de potassium

    NASA Astrophysics Data System (ADS)

    Lautié, Alain; Picquenard, Eric; Ratovelomanana, Nicole

    The i.r. Raman spectra of crystalline 4,5,6-trimethyl 2-pyrimidone and seven deuterated derivatives have been investigated between 4000 and 180 cm -1. Aqueous and CHCl 3 solutions were also examined. An assignment for intramolecular fundamentals is given, as well as a distinction between the most characteristic of each methyl group. The methylation and protonation effects are discussed. Furthermore, a 1/1 adduct of this pyrimidone and potassium halides is observed and characterized; it contains a strong NH…X - hydrogen bond.

  2. K*+ Photoproduction at CLAS

    SciTech Connect

    K. Hicks, W. Tang

    2011-10-01

    The study of hyperon resonances has entered a new era of precision with advent of high-statistics photoproduction data from the CLAS detector at Jefferson Lab and elsewhere. These data have multi-particle final states, allowing clean identification of exclusive reactions associated with strange mesons and baryons. In this paper, cross sections for K* photoproduction are presented that will provide a future test of the existence of the purported K0(800) meson via comparison with theoretical models.

  3. Backward pion photoproduction

    SciTech Connect

    Sibirtsev, A; Haidenbauer, J; Huang, F; Krewald, S; Meissner, U -G

    2009-04-01

    We present a systematic analysis of backward pion photoproduction for the reactions $ \\gamma$ p $ \\rightarrow$ $ \\pi^{0}_{}$ p and $ \\gamma$ p $ \\rightarrow$ $ \\pi^{+}_{}$ n . Regge phenomenology is applied at invariant collision energies above 3GeV in order to fix the reaction amplitude. A comparision with older data on $ \\pi^{0}_{}$ - and $ \\pi^{+}_{}$ -photoproduction at $ \\vartheta$ = 180° indicates that the high-energy limit as given by the Regge calculation could be reached possibly at energies of around $ \\sqrt{{s}}$ ≃ 3 GeV. In the energy region of $ \\sqrt{{s}}$ $ \\le$2.5 GeV, covered by the new measurements of $ \\gamma$ p $ \\rightarrow$ $ \\pi^{0}_{}$ p differential cross-sections at large angles at ELSA, JLab, and LEPS, we see no clear signal for a convergence towards the Regge results. The baryon trajectories obtained in our analysis are in good agreement with those given by the spectrum of excited baryons.

  4. Charm photoproduction dynamics

    SciTech Connect

    Garbincius, P.H.

    1995-03-01

    Photoproduction of open charm is reviewed, both as a tool for studying the properties of charm particles such as spectroscopy, decays, and lifetimes, and as a testing ground for theoretical calculations of production dynamics. Many characteristics of charm photoproduction are described in terms of the leading order (LO) {alpha}{sub EM}{alpha}{sub S} Photon-Gluon Fusion (PGF) model. The next-to-leading order (NLO) corrections of strength {alpha}{sub EM}{alpha}{sub S}{sup 2} due to radiation of additional gluons are then added. The sensitivities of the NLO calculations on the mass of the charm quark, m{sub c}, and on the choice of the gluon structure function of the nucleon are illustrated for the energy dependence of the cross section for charm photoproduction. These are compared with fixed target data and new HERA data. The single charm particle inclusive distributions in x{sub f} and p{sub {perpendicular}}{sup 2}, along with {sigma}({gamma}N {yields} c{anti c}X) give good estimates of m{sub c} and n{sub g}, the shape parameter for the gluon distribution within the nucleon. As in hadroproduction, some disagreements between prediction and observation begin to appear in trying to simultaneously match the distributions in both p{sub {perpendicular}}{sup 2} for single charm particles and in the {Delta}{Phi} acoplanarity angle between pairs of charm particles. These can be partially remedied by modifying the fragmentation function for c-quarks into charm particles, and by including extra k{sub {perpendicular}}{sup 2} transverse smearing of the gluon distributions within the target nucleon. Initial studies of the relative production between charm particles and anti-particles indicate disagreement with the predictions of the independent string fragmentation model.

  5. Dijets in Photoproduction

    NASA Astrophysics Data System (ADS)

    Frising, Gilles

    2002-10-01

    Dijet cross sections as functions of several jet observables are measured in photoproduction using the H1 detector at HERA. The data sample comprises ep data with an integrated luminosity of 34.9 pb-1. Jets are selected using the inclusive kt algorithm with a minimum transverse energy of 25 GeV for the leading jet. The phase space covers longitudinal proton momentum fraction xp and photon longitudinal momentum fraction xγ in the ranges 0.05< xp<0.6 and 0.1

  6. Biological hydrogen photoproduction

    SciTech Connect

    Nemoto, Y.

    1995-09-01

    Following are the major accomplishments of the 6th year`s study of biological hydrogen photoproduction which were supported by DOE/NREL. (1) We have been characterizing a biological hydrogen production system using synchronously growing aerobically nitrogen-fixing unicellular cyanobacterium, Synechococcus sp. Miami BG 043511. So far it was necessary to irradiate the cells to produce hydrogen. Under darkness they did not produce hydrogen. However, we found that, if the cells are incubated with oxygen, they produce hydrogen under the dark. Under 80% argon + 20% oxygen condition, the hydrogen production activity under the dark was about one third of that under the light + argon condition. (2) Also it was necessary so far to incubate the cells under argon atmosphere to produce hydrogen in this system. Argon treatment is very expensive and should be avoided in an actual hydrogen production system. We found that, if the cells are incubated at a high cell density and in a container with minimum headspace, it is not necessary to use argon for the hydrogen production. (3) Calcium ion was found to play an important role in the mechanisms of protection of nitrogenase from external oxygen. This will be a clue to understand the reason why the hydrogen production is so resistant to oxygen in this strain. (4) In this strain, sulfide can be used as electron donor for the hydrogen production. This result shows that waste water can be used for the hydrogen production system using this strain.

  7. 27 CFR 6.4 - Jurisdictional limits.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Jurisdictional limits. 6.4 Section 6.4 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS âTIED-HOUSEâ Scope of Regulations § 6.4 Jurisdictional limits. (a) General. The regulations in this part apply where:...

  8. 27 CFR 6.4 - Jurisdictional limits.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Jurisdictional limits. 6.4 Section 6.4 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL âTIED-HOUSEâ Scope of Regulations § 6.4 Jurisdictional limits. (a) General. The regulations in this part apply where:...

  9. 27 CFR 6.4 - Jurisdictional limits.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Jurisdictional limits. 6.4 Section 6.4 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL âTIED-HOUSEâ Scope of Regulations § 6.4 Jurisdictional limits. (a) General. The regulations in this part apply where:...

  10. 27 CFR 6.4 - Jurisdictional limits.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Jurisdictional limits. 6.4 Section 6.4 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS âTIED-HOUSEâ Scope of Regulations § 6.4 Jurisdictional limits. (a) General. The regulations in this part apply where:...

  11. 7 CFR 6.4 - Investigations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 1 2010-01-01 2010-01-01 false Investigations. 6.4 Section 6.4 Agriculture Office of the Secretary of Agriculture IMPORT QUOTAS AND FEES General Provisions § 6.4 Investigations. (a) Section 22. The Administrator shall cause an investigation to be made whenever, based upon a...

  12. Charmed hadron photoproduction at COMPASS

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Yun; Guskov, Alexey

    2016-06-01

    Photoproduction of the charmonium-like state Zc(4200) and the charmed baryon Λ_c^* (2940) is investigated with an effective Lagrangian approach and the Regge trajectories applying to the COMPASS experiment. Combining the experimental data from COMPASS and our theoretical model we estimate the upper limit of ΓZc(4200)→J/ψπ to be of about 37 MeV. Moreover, the possibility to produce Λ_c^* (2940) at COMPASS is discussed. It seems one can try to search for this hadron in the missing mass spectrum since the t-channel is dominating for the Λ_c^* (2940) photoproduction.

  13. Hyperon Resonance Photoproduction at CLAS

    SciTech Connect

    K. Hicks, D. Keller, W. Tang

    2011-02-01

    The study of hyperon resonances has entered a new era of precision with advent of high-statistics photoproduction data from the CLAS detector at Jeffersonnext term Lab. These data have multi-particle final states, allowing clean identification of exclusive reactions associated with strange mesons and baryons. Examples of physics results are: evidence for isospin interference in the decay of the Λ(1405) resonance; a strong suggestion of meson cloud effects in the structure of the Sigma (1385) resonance; data from Klow asterisk photoproduction that will test the existence of the purported K0(800) meson. Properties of other hyperon resonances will also be studied in the near future.

  14. Photoproduction of dissolved inorganic carbon in Swedish lakes

    NASA Astrophysics Data System (ADS)

    Koehler, B.; Landelius, T.; Tranvik, L. J.

    2012-04-01

    A substantial fraction of the dissolved organic carbon (DOC) in inland waters is mineralized to dissolved inorganic carbon (DIC) during passage towards the sea. Both microbial and photochemical mineralization have a share but there is currently no landscape-scale estimate of the contribution of photomineralization to total lake carbon dioxide emissions, restricting our understanding of inland-water C cycling. We use 1) DOC absorbance spectra measured during autumn 2009 in water samples from 1074 lakes distributed across Sweden, 2) light attenuation coefficients estimated based on correlations with absorption coefficients as established from literature data, 3) cloud-corrected, below-water-surface downwelling scalar irradiance spectra derived by modeling radiative transfer in the atmosphere and transmission into the water and 4) an apparent quantum yield spectrum determined in a humic lake, to calculate spectra of DIC photoproduction from 280 to 600 nm and from the water surface down to the mean lake depths. For each lake, we calculate DIC photoproduction rates on a daily base and integrate to obtain yearly flux estimates. Preliminary model results calculated for July 2009 show that, even though water color differed largely (25%- and 75%-quantiles of specific UV absorption coefficients at 254 nm (SUV A254) of 6.4 and 9.6 L mg C-1 m-1, respectively), depth-integrated DIC photoproduction rates showed a relatively small variation with a 25%-quantile of 12.0 and a 75%-quantile of 13.1 mg C m-2 day-1. These rather similar DIC photoproduction rates are explained by their different depth distributions: The brownest lake with a SUV A254 of 12.9 L mg C-1 m-1 had large surface DIC photoproduction rates of 887.9 mg C m-3 day-1 but photons were quickly attenuated with depth, with DIC photoproduction rates falling below 1 mg C m-3 day-1 already at ¯ 0.2 m depth (depth-integrated rate of 14.2 mg C m-2 day-1). The clearest lake with a SUV A254 of 1.4 L mg C-1 m-1 had nearly 100

  15. Structural role of two histidines in the (6-4) photolyase reaction

    PubMed Central

    Yamada, Daichi; Iwata, Tatsuya; Yamamoto, Junpei; Hitomi, Kenichi; Todo, Takeshi; Iwai, Shigenori; Getzoff, Elizabeth D.; Kandori, Hideki

    2015-01-01

    Photolyases (PHRs) are DNA repair enzymes that revert UV-induced photoproducts, either cyclobutane pyrimidine dimers (CPD) or (6-4) photoproducts (PPs), into normal bases to maintain genetic integrity. (6-4) PHR must catalyze not only covalent bond cleavage, but also hydroxyl or amino group transfer, yielding a more complex mechanism than that postulated for CPD PHR. Previous mutation analysis revealed the importance of two histidines in the active center, H354 and H358 for Xenopus (6-4) PHR, whose mutations significantly lowered the enzymatic activity. Based upon highly sensitive FTIR analysis of the repair function, here we report that both H354A and H358A mutants of Xenopus (6-4) PHR still maintain their repair activity, although the efficiency is much lower than that of the wild type. Similar difference FTIR spectra between the wild type and mutant proteins suggest a common mechanism of repair in which (6-4) PP binds to the active center of each mutant, and is released after repair, as occurs in the wild type. Similar FTIR spectra also suggest that a decrease in volume by the H-to-A mutation is possibly compensated by the addition of water molecule( s). Such a modified environment is sufficient for the repair function that is probably controlled by proton-coupled electron transfer between the enzyme and substrate. On the other hand, two histidines must work in a concerted manner in the active center of the wild-type enzyme, which significantly raises the repair efficiency. PMID:27493863

  16. 27 CFR 6.4 - Jurisdictional limits.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Jurisdictional limits. 6.4 Section 6.4 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF... transactions in interstate or foreign commerce in any such products; or (iii) The direct effect of...

  17. Prediction of p38 map kinase inhibitory activity of 3, 4-dihydropyrido [3, 2-d] pyrimidone derivatives using an expert system based on principal component analysis and least square support vector machine

    PubMed Central

    Shahlaei, M.; Saghaie, L.

    2014-01-01

    A quantitative structure–activity relationship (QSAR) study is suggested for the prediction of biological activity (pIC50) of 3, 4-dihydropyrido [3,2-d] pyrimidone derivatives as p38 inhibitors. Modeling of the biological activities of compounds of interest as a function of molecular structures was established by means of principal component analysis (PCA) and least square support vector machine (LS-SVM) methods. The results showed that the pIC50 values calculated by LS-SVM are in good agreement with the experimental data, and the performance of the LS-SVM regression model is superior to the PCA-based model. The developed LS-SVM model was applied for the prediction of the biological activities of pyrimidone derivatives, which were not in the modeling procedure. The resulted model showed high prediction ability with root mean square error of prediction of 0.460 for LS-SVM. The study provided a novel and effective approach for predicting biological activities of 3, 4-dihydropyrido [3,2-d] pyrimidone derivatives as p38 inhibitors and disclosed that LS-SVM can be used as a powerful chemometrics tool for QSAR studies. PMID:26339262

  18. Meson Photoproduction Experiments with CLAS

    SciTech Connect

    Eugene Pasyuk

    2012-12-01

    A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to light baryon spectroscopy. Meson photoprodcution experiments are essential part of this program. CEBAF Large Acceptance Spectrometer (CLAS) and availability of circularly and linearly polarized tagged photon beams and frozen spin polarized targets provide unique conditions for this type of experiments. This combination of experimental tools gives a remarkable opportunity to measure double polarization observables for different pseudo-scalar meson photoproduction processes. For the first time, a complete or nearly complete measurement became possible and will facilitate model independent extraction of the reaction amplitude. An overview of the experimental program and its current status together with recent results on double polarization measurements in π{sup +} photoproduction are presented.

  19. Photoproduction of exotic baryon resonances

    NASA Astrophysics Data System (ADS)

    Karliner, Marek; Rosner, Jonathan L.

    2016-01-01

    We point out that the new exotic resonances recently reported by LHCb in the J / ψ p channel are excellent candidates for photoproduction off a proton target. This test is crucial to confirming the resonant nature of such states, as opposed to their being kinematical effects. We specialize to an interpretation of the heavier narrow state as a molecule composed of Σc and Dbar*, and estimate its production cross section using vector dominance. The relevant photon energies and fluxes are well within the capabilities of the GlueX and CLAS12 detectors at Thomas Jefferson National Accelerator Facility (JLAB). A corresponding calculation is also performed for photoproduction of an analogous resonance which is predicted to exist in the ϒp channel.

  20. Bayesian analysis for kaon photoproduction

    SciTech Connect

    Marsainy, T. Mart, T.

    2014-09-25

    We have investigated contribution of the nucleon resonances in the kaon photoproduction process by using an established statistical decision making method, i.e. the Bayesian method. This method does not only evaluate the model over its entire parameter space, but also takes the prior information and experimental data into account. The result indicates that certain resonances have larger probabilities to contribute to the process.

  1. 43 CFR 3141.6-4 - Qualifications.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LEASING IN SPECIAL TAR SAND AREAS Leasing in Special Tar Sand Areas § 3141.6-4 Qualifications. Each bidder shall submit with the bid a statement over...

  2. 43 CFR 3141.6-4 - Qualifications.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LEASING IN SPECIAL TAR SAND AREAS Leasing in Special Tar Sand Areas § 3141.6-4 Qualifications. Each bidder shall submit with the bid a statement over...

  3. 43 CFR 3141.6-4 - Qualifications.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LEASING IN SPECIAL TAR SAND AREAS Leasing in Special Tar Sand Areas § 3141.6-4 Qualifications. Each bidder shall submit with the bid a statement over...

  4. 43 CFR 3141.6-4 - Qualifications.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., DEPARTMENT OF THE INTERIOR MINERALS MANAGEMENT (3000) LEASING IN SPECIAL TAR SAND AREAS Leasing in Special Tar Sand Areas § 3141.6-4 Qualifications. Each bidder shall submit with the bid a statement over...

  5. Complete Photo-production Experiments

    SciTech Connect

    D'Angelo, A.; Bartalini, O.; Fantini, A.; Schaerf, C.; Vegna, V.; Ardashev, K.; Bade, C.; Hicks, K.; Kizilgul, S.; Lucas, M.; Mahon, J.; Bellini, V.; Blecher, M.; Bocquet, J.-P.; Lleres, A.; Rebreyend, D.; Capogni, M.; Caracappa, A.; Kistner, O. C.; Miceli, L.

    2011-10-24

    The extraction of resonance parameters from meson photo-reaction data is a challenging effort, that would greatly benefit from the availability of several polarization observables, measured for each reaction channel on both proton and neutron targets. In the aim of obtaining such complete experiments, polarized photon beams and targets have been developed at facilities, worldwide. We report on the latest results from the LEGS and GRAAL collaborations, providing single and double polarization measurements on pseudo-scalar meson photo-production from the nucleon.

  6. Meson Photoproduction Experiments at ELPH, Tohoku University

    NASA Astrophysics Data System (ADS)

    Ishikawa, Takatsugu; Fujimura, Hisako; Fukasawa, Hiroshi; Hashimoto, Ryo; He, Qinghua; Honda, Yuki; Iwata, Takahiro; Kaida, Shun; Kasagi, Jirohta; Kawano, Atsushi; Kuwasaki, Shuzo; Maeda, Kazushige; Masumoto, Shin'ichi; Miyabe, Manabu; Miyahara, Fusashi; Mochizuki, Kei'ichi; Muramatsu, Norihito; Nakamura, Akihiko; Nawa, Ken'ichi; Ogushi, Shoei; Okada, Yasuyuki; Onodera, Yoshihito; Ozawa, Kyoichiro; Sakamoto, Yasunobu; Sato, Mamoru; Shimizu, Hajime; Sugai, Hiroyuki; Suzuki, Koutaku; Tajima, Yasuhisa; Takahashi, Shin'ichiro; Taniguchi, Yusuke; Tsuchikawa, Yusuke; Yamazaki, Hirohito; Yamazaki, Ryuji; Yoshida, Hiroshi Y.

    Meson photoproduction experiments have been conducted with an electromagnetic (EM) calorimeter FOREST at Research Center for Electron Photon Science (ELPH), Tohoku University. A narrow resonance observed at W = 1670 MeV in η photoproduction on the neutron is of great interest, which is a candidate of an anti-decuplet pentaquark baryon although its origin is still controversial. The preliminary results of the cross sections for π0 and η photoproduction on the deuteron are presented. The next generation FOREST experiments have been planned to study S11(1535) properties in the nuclear medium by searching for η-mesic nucleus states. The planned experiments are also shown in this contribution.

  7. Photoproduction total cross section and shower development

    NASA Astrophysics Data System (ADS)

    Cornet, F.; García Canal, C. A.; Grau, A.; Pancheri, G.; Sciutto, S. J.

    2015-12-01

    The total photoproduction cross section at ultrahigh energies is obtained using a model based on QCD minijets and soft-gluon resummation and the ansatz that infrared gluons limit the rise of total cross sections. This cross section is introduced into the Monte Carlo system AIRES to simulate extended air showers initiated by cosmic ray photons. The impact of the new photoproduction cross section on common shower observables, especially those related to muon production, is compared with previous results.

  8. K*{sup +} Photoproduction at CLAS

    SciTech Connect

    Hicks, K.; Tang, W.

    2011-10-21

    The study of hyperon resonances has entered a new era of precision with advent of high-statistics photoproduction data from the CLAS detector at Jefferson Lab and elsewhere. These data have multi-particle final states, allowing clean identification of exclusive reactions associated with strange mesons and baryons. In this paper, cross sections for K* photoproduction are presented that will provide a future test of the existence of the purported K{sub 0}(800) meson via comparison with theoretical models.

  9. Exact evaluation of triplet photoproduction

    NASA Astrophysics Data System (ADS)

    Endo, I.; Kobayashi, T.

    1993-05-01

    The differential cross section of the triplet photoproduction (TPP), i.e., the pair production on an electron, has been evaluated by using the computer code HELAS in which all the eight lowest order Feynman graphs can be numerically treated without any approximation. It has been shown that the calculation with only two diagrams, called Borsellino diagrams, agrees very well with the full calculation in a wide kinematical region for photon energies between 50 and 550 MeV. For a possible application of TPP to the polarimetry of high energy linearly polarized photons, we show that the analyzing power can be enhanced by restricting the opening angle of the forward going e +e - pair.

  10. Photoproduction of the kaon(+)kaon(-)(1750)

    NASA Astrophysics Data System (ADS)

    Mitchell, Ryan Edward

    2003-07-01

    While photoproduction has often been advertised as an important environment in which to study light meson spectroscopy, solid experimental results are sparse. In fact, beyond the relatively straightforward photoproduction of the rho, o, and φ mesons, the few results of exclusive photoproduction that do exist are poorly understood, and several, perhaps, have even been misinterpreted. After extensively reviewing the sometimes tenuous history of the exclusive photoproduction of the "rho'(1600)," the "opi0(1250)," the "o(1650)," and the "K+K -(1750)," new results from the E831/FOCUS photoproduction experiment at Fermilab are presented which address the interpretation of the K+K-(1750). This enhancement in low-pT K +K- pairs at a mass near 1750 MeV/c2 has been observed by several previous photoproduction experiments, but, despite several apparent inconsistencies, it has always been interpreted as the JPC = 1-- φ(1680) meson. With nearly two orders of magnitude more events than any previous observation of the K+ K-(1750), and based on precise measurements of its mass and width, and its absence from the K* K final state, the FOCUS data can finally render this interpretation implausible. In addition, several steps have been taken towards establishing a new interpretation. Based on limited angular analyses of its decay and the beam energy dependence of its production, we argue that, in the absence of any wild interference scenarios, the K+ K-(1750) has JPC ≠ 1--, and, in fact, the most likely assignment appears to be 2++. It is hoped that this work can help set the stage for future reevaluations and new insights in photoproduction.

  11. Measurement of elastic Υ photoproduction at HERA

    NASA Astrophysics Data System (ADS)

    ZEUS Collaboration; Breitweg, J.; Derrick, M.; Krakauer, D.; Magill, S.; Mikunas, D.; Musgrave, B.; Repond, J.; Stanek, R.; Talaga, R. L.; Yoshida, R.; Zhang, H.; Mattingly, M. C. K.; Anselmo, F.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Castellini, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Coppola, N.; Corradi, M.; de Pasquale, S.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Polini, A.; Sartorelli, G.; Zamora Garcia, Y.; Zichichi, A.; Amelung, C.; Bornheim, A.; Brock, I.; Coböken, K.; Crittenden, J.; Deffner, R.; Eckert, M.; Grothe, M.; Hartmann, H.; Heinloth, K.; Heinz, L.; Hilger, E.; Jakob, H.-P.; Kappes, A.; Katz, U. F.; Kerger, R.; Paul, E.; Pfeiffer, M.; Schnurbusch, H.; Wieber, H.; Bailey, D. S.; Campbell-Robson, S.; Cottingham, W. N.; Foster, B.; Hall-Wilton, R.; Heath, G. P.; Heath, H. F.; McFall, J. D.; Piccioni, D.; Roff, D. G.; Tapper, R. J.; Capua, M.; Iannotti, L.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Pac, M. Y.; Caldwell, A.; Cartiglia, N.; Jing, Z.; Liu, W.; Mellado, B.; Parsons, J. A.; Ritz, S.; Sampson, S.; Sciulli, F.; Straub, P. B.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Klimek, K.; Przybycień , M. B.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Bukowy, M.; Czermak, A. M.; Jeleń , K.; Kisielewska, D.; Kowalski, T.; Przybycień , M.; Rulikowska-Zarȩ Bska, E.; Suszycki, L.; Zaja C, J.; Duliń Ski, Z.; Kotań Ski, A.; Abbiendi, G.; Bauerdick, L. A. T.; Behrens, U.; Beier, H.; Bienlein, J. K.; Desler, K.; Drews, G.; Fricke, U.; Gialas, I.; Goebel, F.; Göttlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G. F.; Hasell, D.; Hebbel, K.; Johnson, K. F.; Kasemann, M.; Koch, W.; Kötz, U.; Kowalski, H.; Lindemann, L.; Löhr, B.; Martínez, M.; Milewski, J.; Milite, M.; Monteiro, T.; Notz, D.; Pellegrino, A.; Pelucchi, F.; Piotrzkowski, K.; Rohde, M.; Roldán, J.; Ryan, J. J.; Saull, P. R. B.; Savin, A. A.; Schneekloth, U.; Schwarzer, O.; Selonke, F.; Stonjek, S.; Surrow, B.; Tassi, E.; Westphal, D.; Wolf, G.; Wollmer, U.; Youngman, C.; Zeuner, W.; Burow, B. D.; Coldewey, C.; Grabosch, H. J.; Meyer, A.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Pelfer, P.; Maccarrone, G.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Markun, P.; Raach, H.; Trefzger, T.; Wölfle, S.; Bromley, J. T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Lee, S. W.; MacDonald, N.; McCance, G. J.; Saxon, D. H.; Sinclair, L. E.; Skillicorn, I. O.; Strickland, E.; Waugh, R.; Bohnet, I.; Gendner, N.; Holm, U.; Meyer-Larsen, A.; Salehi, H.; Wick, K.; Garfagnini, A.; Gladilin, L. K.; Kçira, D.; Klanner, R.; Lohrmann, E.; Poelz, G.; Zetsche, F.; Bacon, T. C.; Butterworth, I.; Cole, J. E.; Howell, G.; Lamberti, L.; Long, K. R.; Miller, D. B.; Pavel, N.; Prinias, A.; Sedgbeer, J. K.; Sideris, D.; Walker, R.; Mallik, U.; Wang, S. M.; Wu, J. T.; Cloth, P.; Filges, D.; Fleck, J. I.; Ishii, T.; Kuze, M.; Suzuki, I.; Tokushuku, K.; Yamada, S.; Yamauchi, K.; Yamazaki, Y.; Hong, S. J.; Lee, S. B.; Nam, S. W.; Park, S. K.; Lim, H.; Park, I. H.; Son, D.; Barreiro, F.; Fernández, J. P.; García, G.; Glasman, C.; Hernández, J. M.; Hervás, L.; Labarga, L.; del Peso, J.; Puga, J.; Terrón, J.; de Trocóniz, J. F.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Murray, W. N.; Ochs, A.; Riveline, M.; Stairs, D. G.; St-Laurent, M.; Tsurugai, T.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Golubkov, Yu. A.; Khein, L. A.; Korotkova, N. A.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Yu.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Zotkin, S. A.; Bokel, C.; Botje, M.; Brümmer, N.; Engelen, J.; Koffeman, E.; Kooijman, P.; van Sighem, A.; Tiecke, H.; Tuning, N.; Verkerke, W.; Vossebeld, J.; Wiggers, L.; de Wolf, E.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Nylander, P.; Romanowski, T. A.; Blaikley, H. E.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Edmonds, J. K.; Große-Knetter, J.; Harnew, N.; Nath, C.; Noyes, V. A.; Quadt, A.; Ruske, O.; Tickner, J. R.; Walczak, R.; Waters, D. S.; Bertolin, A.; Brugnera, R.; Carlin, R.; dal Corso, F.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Oh, B. Y.; Okrasiń Ski, J. R.; Toothacker, W. S.; Whitmore, J. J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Raso, M.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Epperson, D.; Heusch, C.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Wichmann, R.; Williams, D. C.; Abramowicz, H.; Briskin, G.; Dagan, S.; Kananov, S.; Levy, A.; Abe, T.; Fusayasu, T.; Inuzuka, M.; Nagano, K.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Matsushita, T.; Nishimura, T.; Arneodo, M.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Petrucci, M. C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Fagerstroem, C.-P.; Galea, R.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sabetfakhri, A.; Simmons, D.; Butterworth, J. M.; Catterall, C. D.; Hayes, M. E.; Heaphy, E. A.; Jones, T. W.; Lane, J. B.; Saunders, R. L.; Sutton, M. R.; Wing, M.; Ciborowski, J.; Grzelak, G.; Nowak, R. J.; Pawlak, J. M.; Pawlak, R.; Smalska, B.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Zsolararnecki, A. F.; Adamus, M.; Deppe, O.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Badgett, W. F.; Chapin, D.; Cross, R.; Dasu, S.; Foudas, C.; Loveless, R. J.; Mattingly, S.; Reeder, D. D.; Smith, W. H.; Vaiciulis, A.; Wodarczyk, M.; Deshpande, A.; Dhawan, S.; Hughes, V. W.; Bhadra, S.; Frisken, W. R.; Khakzad, M.; Schmidke, W. B.

    1998-10-01

    The photoproduction reaction γp--> μ+μ-p has been studied in ep interactions using the ZEUS detector at HERA. The data sample corresponds to an integrated luminosity of 43.2 pb-1. The Υ meson has been observed in photoproduction for the first time. The sum of the products of the elastic Υ(1S),Υ(2S),Υ(3S) photoproduction cross sections with their respective branching ratios is determined to be 13.3+/-6.0(stat.)+2.7-2.3(syst.) pb at a mean photon-proton centre of mass energy of 120 GeV. The cross section is above the prediction of a perturbative QCD model.

  12. Biological Systems for Hydrogen Photoproduction (Presentation)

    SciTech Connect

    Ghirardi, M. L.

    2012-05-01

    This presentation summarizes NREL biological systems for hydrogen photoproduction work for the DOE Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting, May 14-18, 2012. General goal is develop photobiological systems for large-scale, low cost and efficient H{sub 2} production from water (barriers AH, AI and AJ). Specific tasks are: (1) Address the O{sub 2} sensitivity of hydrogenases that prevent continuity of H{sub 2} photoproduction under aerobic, high solar-to-hydrogen (STH) light conversion efficiency conditions; and (2) Utilize a limited STH H{sub 2}-producing method (sulfur deprivation) as a platform to address or test other factors limiting commercial algal H{sub 2} photoproduction, including low rates due to biochemical and engineering mechanisms.

  13. Photoproduction of the Lambda*(1520) Hyperon

    SciTech Connect

    Z. W. Zhao, H. Y. Lu, L. Graham, K. Park, R. W. Gothe

    2010-08-01

    The photoproduction of the Lambda*(1520) on both the proton and neutron have been studied by using the CLAS eg3 run data set. The reactions are gammad-->K+Lambda*(n) and gammad-->K0Lambda*(p) with Lambda*-->pK-. Preliminary total and differential cross sections have been extracted in the photon energy region 1.75 GeVphotoproduction of Lambda*(1520) on the neutron is reported, and we will extend the results on the proton to higher energies than in previous studies.

  14. Studies on porphyrin photoproducts in solution, cells, and tumor tissue

    NASA Astrophysics Data System (ADS)

    Koenig, Karsten; Schneckenburger, Herbert; Rueck, Angelika C.; Koenig, Roland

    1994-07-01

    Light excitation of photosensitizing porphyrins leads to cytotoxic reactions. In addition, photobleaching and photoproduct formation occur indicating photosensitizer destruction. Photoproducts from hematoporphyrin (HP) fluoresce in aqueous solution at 642 nm, whereas photoproducts from protoporphyrin (PP) in hydrophobic environment emit around 670 nm and exhibit pronounced absorption at 665 nm. Photoproduct formation depends on singlet oxygen. The photoproducts exhibit faster fluorescence decay kinetics compared with nonirradiated porphyrins, as shown by time-grated spectroscopy and fluorescence decay measurements. Photoproduct fluorescence was observed during light exposure of cells and of tumor-bearing, nude mice, following administration of Hematoporphyrin Derivative (HpD), tetramethyl-HP, and PP. Photoconversion was also detected with naturally-occurring porphyrins (PP-producing bacteria) and ALA-simulated biosynthesis of PP in tumor tissue and in skin lesions of patients (psoriasis, mycosis fungoides). The efficiency of PDT with porphyrin photoproducts was found to be low in spite of the strong electronic transitions in the red spectral region.

  15. Crystal structure of a prokaryotic (6-4) photolyase with an Fe-S cluster and a 6,7-dimethyl-8-ribityllumazine antenna chromophore

    PubMed Central

    Zhang, Fan; Scheerer, Patrick; Oberpichler, Inga; Lamparter, Tilman; Krauß, Norbert

    2013-01-01

    The (6-4) photolyases use blue light to reverse UV-induced (6-4) photoproducts in DNA. This (6-4) photorepair was thought to be restricted to eukaryotes. Here we report a prokaryotic (6-4) photolyase, PhrB from Agrobacterium tumefaciens, and propose that (6-4) photolyases are broadly distributed in prokaryotes. The crystal structure of photolyase related protein B (PhrB) at 1.45 Å resolution suggests a DNA binding mode different from that of the eukaryotic counterparts. A His-His-X-X-Arg motif is located within the proposed DNA lesion contact site of PhrB. This motif is structurally conserved in eukaryotic (6-4) photolyases for which the second His is essential for the (6-4) photolyase function. The PhrB structure contains 6,7-dimethyl-8-ribityllumazine as an antenna chromophore and a [4Fe-4S] cluster bound to the catalytic domain. A significant part of the Fe-S fold strikingly resembles that of the large subunit of eukaryotic and archaeal primases, suggesting that the PhrB-like photolyases branched at the base of the evolution of the cryptochrome/photolyase family. Our study presents a unique prokaryotic (6-4) photolyase and proposes that the prokaryotic (6-4) photolyases are the ancestors of the cryptochrome/photolyase family. PMID:23589886

  16. Factors affecting the efficiency of carbon monoxide photoproduction in the St. Lawrence estuarine system (Canada).

    PubMed

    Zhang, Yong; Xie, Huixiang; Chen, Guohua

    2006-12-15

    This study examined the effects of water temperature and the origin (terrestrial vs marine) and light history of chromophoric dissolved organic matter (CDOM) on the apparent quantum yields of carbon monoxide (CO) photoproduction for water samples collected along a salinity gradient (salinity range: 0-33) in the St. Lawrence estuarine system (Canada). The solar insolation-weighted mean apparent quantum yield of CO (phico) decreased as much as fourfold with increasing salinity and showed a strong positive correlation with the dissolved organic carbon-specific absorption coefficient at 254 nm. This suggests that terrestrial CDOM is more efficient at photochemically producing CO than is marine algae-derived CDOM and that aromatic moieties are likely involved in this photoprocess. CDOM photobleaching, mainly at the very early stage, dramatically decreased phico (by up to 6.4 times) for low-salinity samples, but photobleaching had little effect on the most marine sample. For a 20 degree C increase in temperature, phico increased by approximately 70% for low-salinity samples and 30-40% for saline samples. This study demonstrates that water temperature, as well as the CDOM's origin and light history, strongly affect the efficiency of CO photoproduction. These factors should be taken into account in modeling the photochemical fluxes of CO and other related CDOM photoproducts on varying spatiotemporal scales. PMID:17256526

  17. Photoproduction of charm particles at Fermilab

    SciTech Connect

    Cumalat, John P.

    1997-03-15

    A brief description of the Fermilab Photoproduction Experiment E831 or FOCUS is presented. The experiment concentrates on the reconstruction of charm particles. The FOCUS collaboration has participants from several Central American and Latin American institutions; CINVESTAV and Universidad Autonoma de Puebla from Mexico, University of Puerto Rico from the United States, and Centro Brasileiro de Pesquisas Fisicas in Rio de Janeiro from Brasil.

  18. FTIR Study of the Photoactivation Process of Xenopus (6-4) Photolyase†

    PubMed Central

    Yamada, Daichi; Zhang, Yu; Iwata, Tatsuya; Hitomi, Kenichi; Getzoff, Elizabeth D.; Kandori, Hideki

    2012-01-01

    Photolyases (PHRs) are blue-light activated DNA repair enzymes that maintain genetic integrity by reverting UV-induced photoproducts into normal bases. The FAD chromophore of PHRs has four different redox states: oxidized (FADox), anion radical (FAD•−), neutral radical (FADH•) and fully reduced (FADH−). We combined difference Fourier-transform infrared (FTIR) spectroscopy with UV-visible spectroscopy to study the detailed photoactivation process of Xenopus (6-4) PHR. Two photons produce the enzymatically active, fully reduced PHR from oxidized FAD: FADox is converted to semiquinone via light-induced one-electron and one-proton transfers, and then to FADH− by light-induced one-electron transfer. We successfully trapped FAD•− at 200 K, where electron transfer occurs, but proton transfer does not. UV-visible spectroscopy following 450-nm illumination of FADox at 277 K defined the FADH•/FADH− mixture and allowed calculation of difference FTIR spectra among the four redox states. The absence of a characteristic C=O stretching vibration indicated that the proton donor is not a protonated carboxylic acid. Structural changes in Trp and Tyr are suggested from UV-visible and FTIR analysis of FAD•− at 200 K. Spectral analysis of amide-I vibrations revealed structural perturbation of the protein’s β-sheet during initial electron transfer (FAD•− formation), transient increase in α-helicity during proton transfer (FADH• formation) and reversion to the initial amide-I signal following subsequent electron transfer (FADH− formation). Consequently, in (6-4) PHR, unlike cryptochrome-DASH, formation of enzymatically active FADH− did not perturb α-helicity. Protein structural changes in the photoactivation of (6-4) PHR are discussed on the basis of the present FTIR observations. PMID:22747528

  19. Characterization and Differential Expression of CPD and 6-4 DNA Photolyases in Xiphophorus Species and Interspecies Hybrids★

    PubMed Central

    Walter, Dylan J.; Boswell, Mikki; Volk de García, Sara M.; Walter, Sean M.; Breitenfeldt, Eric W.; Boswell, William; Walter, Ronald B.

    2014-01-01

    Among the many Xiphophorus interspecies hybrid tumor models are those that exhibit ultraviolet light (UVB) induced melanoma. In previous studies, assessment of UVB induced DNA damage and nucleotide excision DNA repair has been performed in parental lines and interspecies hybrids. Species and hybrid specific differences in the levels of DNA damage induced and the dark repair rates for cyclobutane pyrimidine dimers (CPDs) and 6-4 pyrimidine pyrimidine photoproducts (6-4PPs) have been reported. However, UVB induced DNA lesions in Xiphophorus fishes are thought to primarily be repaired via light dependent CPD and 6-4PP specific photolyases. Photolyases are of evolutionary interest since they are ancient and presumably function solely to ameliorate the deleterious effects of UVB exposure. Herein, we report results from detailed studies of CPD and 6-4PP photolyase gene expression within several Xiphophorus tissues. We determined photolyase gene expression patterns before and after exposure to fluorescent light in X. maculatus, X. couchianus, and for F1 interspecies hybrids produced from crossing these two parental lines (×. maculatus Jp 163 B × X. couchianus). We present novel results showing these two photolyase genes exhibit species, tissue, and hybrid-specific differences in basal and light induced gene expression. PMID:24496042

  20. 15 CFR 6.4 - Adjustments to penalties.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 15 Commerce and Foreign Trade 1 2011-01-01 2011-01-01 false Adjustments to penalties. 6.4 Section 6.4 Commerce and Foreign Trade Office of the Secretary of Commerce CIVIL MONETARY PENALTY INFLATION ADJUSTMENTS § 6.4 Adjustments to penalties. The civil monetary penalties provided by law within the jurisdiction of the respective agencies or...

  1. 15 CFR 6.4 - Adjustments to penalties.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Adjustments to penalties. 6.4 Section 6.4 Commerce and Foreign Trade Office of the Secretary of Commerce CIVIL MONETARY PENALTY INFLATION ADJUSTMENTS § 6.4 Adjustments to penalties. The civil monetary penalties provided by law within the jurisdiction of the respective agencies or...

  2. 39 CFR 6.4 - Attendance by conference telephone call.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Attendance by conference telephone call. 6.4 Section 6.4 Postal Service UNITED STATES POSTAL SERVICE THE BOARD OF GOVERNORS OF THE U.S. POSTAL SERVICE MEETINGS (ARTICLE VI) § 6.4 Attendance by conference telephone call. For regularly scheduled meetings...

  3. 43 CFR 6.4 - Action by Solicitor.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 1 2012-10-01 2011-10-01 true Action by Solicitor. 6.4 Section 6.4 Public Lands: Interior Office of the Secretary of the Interior PATENT REGULATIONS Inventions by Employees § 6.4 Action by Solicitor. (a) If an employee inventor requests pursuant to § 6.2(e), that such...

  4. 43 CFR 6.4 - Action by Solicitor.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Action by Solicitor. 6.4 Section 6.4 Public Lands: Interior Office of the Secretary of the Interior PATENT REGULATIONS Inventions by Employees § 6.4 Action by Solicitor. (a) If an employee inventor requests pursuant to § 6.2(e), that...

  5. 43 CFR 6.4 - Action by Solicitor.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 1 2013-10-01 2013-10-01 false Action by Solicitor. 6.4 Section 6.4 Public Lands: Interior Office of the Secretary of the Interior PATENT REGULATIONS Inventions by Employees § 6.4 Action by Solicitor. (a) If an employee inventor requests pursuant to § 6.2(e), that...

  6. 43 CFR 6.4 - Action by Solicitor.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 1 2011-10-01 2011-10-01 false Action by Solicitor. 6.4 Section 6.4 Public Lands: Interior Office of the Secretary of the Interior PATENT REGULATIONS Inventions by Employees § 6.4 Action by Solicitor. (a) If an employee inventor requests pursuant to § 6.2(e), that...

  7. 41 CFR 51-6.4 - Military resale commodities.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... commodities. 51-6.4 Section 51-6.4 Public Contracts and Property Management Other Provisions Relating to... PROCEDURES § 51-6.4 Military resale commodities. (a) Purchase procedures for ordering military resale... overseas, to designated depots at ports of embarkation. Zone pricing is used for delivery to Alaska...

  8. 41 CFR 51-6.4 - Military resale commodities.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... commodities. 51-6.4 Section 51-6.4 Public Contracts and Property Management Other Provisions Relating to... PROCEDURES § 51-6.4 Military resale commodities. (a) Purchase procedures for ordering military resale... overseas, to designated depots at ports of embarkation. Zone pricing is used for delivery to Alaska...

  9. 41 CFR 51-6.4 - Military resale commodities.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... commodities. 51-6.4 Section 51-6.4 Public Contracts and Property Management Other Provisions Relating to... PROCEDURES § 51-6.4 Military resale commodities. (a) Purchase procedures for ordering military resale... overseas, to designated depots at ports of embarkation. Zone pricing is used for delivery to Alaska...

  10. 1 CFR 6.4 - Monthly list of sections affected.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 1 General Provisions 1 2011-01-01 2011-01-01 false Monthly list of sections affected. 6.4 Section 6.4 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER THE FEDERAL REGISTER INDEXES AND ANCILLARIES § 6.4 Monthly list of sections affected. A monthly list of sections of the Code...

  11. 1 CFR 6.4 - Monthly list of sections affected.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 1 General Provisions 1 2010-01-01 2010-01-01 false Monthly list of sections affected. 6.4 Section 6.4 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER THE FEDERAL REGISTER INDEXES AND ANCILLARIES § 6.4 Monthly list of sections affected. A monthly list of sections of the Code...

  12. 1 CFR 6.4 - Monthly list of sections affected.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 1 General Provisions 1 2013-01-01 2012-01-01 true Monthly list of sections affected. 6.4 Section 6.4 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER THE FEDERAL REGISTER INDEXES AND ANCILLARIES § 6.4 Monthly list of sections affected. A monthly list of sections of the Code...

  13. 1 CFR 6.4 - Monthly list of sections affected.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 1 General Provisions 1 2012-01-01 2012-01-01 false Monthly list of sections affected. 6.4 Section 6.4 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER THE FEDERAL REGISTER INDEXES AND ANCILLARIES § 6.4 Monthly list of sections affected. A monthly list of sections of the Code...

  14. 1 CFR 6.4 - Monthly list of sections affected.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 1 General Provisions 1 2014-01-01 2012-01-01 true Monthly list of sections affected. 6.4 Section 6.4 General Provisions ADMINISTRATIVE COMMITTEE OF THE FEDERAL REGISTER THE FEDERAL REGISTER INDEXES AND ANCILLARIES § 6.4 Monthly list of sections affected. A monthly list of sections of the Code...

  15. Activation of hyaluronidase by 8-methoxypsoralen-polyamine photoproducts.

    PubMed

    Shigehara, N; Kakegawa, H; Miyataka, H; Matsumoto, H; Isobe, A; Satoh, T

    1991-12-01

    Ultraviolet radiation of 8-methoxypsoralen (8-MOP) in the presence of various polyamines resulted in stable photoproducts that were very soluble in water and showed hyaluronidase-activating properties. Among them, the photoproducts obtained from the reaction systems of 8-MOP-spermine and 8-MOP-spermidine markedly activated hyaluronidase. The enzyme activity was not affected by 8-MOP alone and the photoproduct of 8-MOP (8-MOP-P). From these facts, it was suggested that the photoproducts with hyaluronidase-activating properties might play an important role in the onset of 8-MOP-induced photosensitivity. PMID:1823146

  16. Measurement of Charged Pion Photoproduction at ELPH

    NASA Astrophysics Data System (ADS)

    Kanda, Hiroki; Beckford, Brian; Fujibayashi, Takeji; Fujii, Takao; Fujii, Yu; Futatsukawa, Kenta; Gogami, Toshiyuki; Han, Yun-Cheng; Hashimoto, Osamu; Hirose, Kentaro; Hosomi, Kenji; Honda, Ryotaro; Iguchi, Alan; Ishikawa, Takatsugu; Kaneta, Masashi; Kaneko, Yusuke; Kasai, Yuma; Kawasaki, Taito; Kimura, Chigusa; Kiyokawa, Shogo; Koike, Takeshi; Maeda, Kazushige; Maruyama, Nayuta; Matsubara, Masao; Miwa, Koji; Miyagi, Yohei; Nagao, Sho; Nakamura, Satoshi N.; Nishizawa, Takashi; Okuyama, Akira; Shimizu, Hajime; Suzuki, Kotaku; Tamae, Tadaaki; Tamura, Hirokazu; Tsukada, Kyo; Terada, Nobu; Ukai, Mifuyu; Wang, Tie-Shan; Yamamoto, Fumiya; Yamazaki, Hirohito

    We investigated the charged pion photoproductions on the deuteron in the photon energy region of 0.65 to 1.1 GeV at Research Center for Electron Photon Science, Tohoku University. The objective is to explore the π+π- photoproduction process which dominates at Eγ > 0.8 GeV. We measured the charged particles from the photoreaction on the deuteron with the Neutral Kaon Spectrometer-2 (NKS2). The analyses both for quasi-free and non-quasi-free processes are underway. As one of the non-quasi-free processes, γd → π+π-d was separated by requiring π+, π- and d. The relative yield and the π+π- invariant mass spectra are presented. We are also proceeding with the development of the new photon tagger to be ready in 2014.

  17. Photoproduction of the {Lambda}*(1520) Hyperon

    SciTech Connect

    Zhao, Z. W.; Lu, H. Y.; Graham, L.; Park, K.; Gothe, R. W.

    2010-08-05

    The photoproduction of the {Lambda}*(1520) on both the proton and neutron have been studied by using the CLAS eg3 run data set. The reactions are {gamma}d{yields}K{sup +{Lambda}}*(n) and {gamma}d{yields}K{sup 0{Lambda}}*(p) with {Lambda}*{yields}pK{sup -}. Preliminary total and differential cross sections have been extracted in the photon energy region 1.75 GeVphotoproduction of {Lambda}*(1520) on the neutron is reported, and we will extend the results on the proton to higher energies than in previous studies.

  18. Exclusive photoproduction of the cascade (Xi) hyperon

    SciTech Connect

    John Price; Bernard Nefkens; Justin Ducote; John Goetz; et. Al.

    2004-09-01

    We report on the first measurement of exclusive {Xi}{sup -}(1321) hyperon photoproduction in {gamma}p {yields} K{sup +}K{sup +}{Xi}{sup -} for 3.2 < E{sub {gamma}} < 3.9 GeV. The final state is identified by the missing mass in p({gamma}, K{sup +}K{sup +})X measured with the CLAS detector at Jefferson Laboratory. We have detected a significant number of the ground-state {Xi}{sup -}(132)1/2{sup +}, and have estimated the total cross section for its production. We have also observed the first excited state {Xi}{sup -}(1530)3/2{sup +}. Photoproduction provides a copious source of {Xi}'s. We discuss the possibilities of a search for the recently proposed {Xi}{sub 5}{sup --} and {Xi}{sub 5}{sup +} pentaquarks.

  19. Hadronic form factors in kaon photoproduction

    SciTech Connect

    Syukurilla, L. Mart, T.

    2014-09-25

    We have revisited the effect of hadronic form factors in kaon photoproduction process by utilizing an isobaric model developed for kaon photoproduction off the proton. The model is able to reproduce the available experimental data nicely as well as to reveal the origin of the second peak in the total cross section, which was the main source of confusion for decades. Different from our previous study, in the present work we explore the possibility of using different hadronic form factors in each of the KΛN vertices. The use of different hadronic form factors, e.g. dipole, Gaussian, and generalized dipole, has been found to produce a more flexible isobar model, which can provide a significant improvement in the model.

  20. K*0Λ photoproduction off a neutron

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Yun; He, Jun

    2016-03-01

    Inspired by the preliminary experimental data by the CLAS Collaboration, the K*0Λ photoproduction off a neutron is studied within an effective Lagrangian approach. The contributions from the Born terms including s , u , and t channels are considered to calculate the amplitude, with which the cross sections are calculated and compared with preliminary CLAS data. The theoretical results indicate that the contribution from the t -channel K exchange plays a dominant role for the K*0Λ photoproduction. The contribution from the κ exchange is found one order of magnitude smaller than that from the K exchange. Both the Regge model and the Feynman model are applied to treat the t -channel contribution. The discrepancy between two models is found small in the energy range of CLAS data and predicted to become obvious at energies higher than 3 GeV. More precise experimental data especially at backward angles will be helpful to further understand the interaction mechanism of the K*0Λ photoproduction.

  1. Measurement of inclusive (Ds+/-) photoproduction at HERA

    NASA Astrophysics Data System (ADS)

    Breitweg, J.; Chekanov, S.; Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Pellegrino, A.; Repond, J.; Stanek, R.; Yoshida, R.; Mattingly, M. C. K.; Abbiendi, G.; Anselmo, F.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Castellini, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Coppola, N.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Polini, A.; Sartorelli, G.; Zamora Garcia, Y.; Zichichi, A.; Amelung, C.; Bornheim, A.; Brock, I.; Coböken, K.; Crittenden, J.; Deffner, R.; Hartmann, H.; Heinloth, K.; Hilger, E.; Irrgang, P.; Jakob, H.-P.; Kappes, A.; Katz, U. F.; Kerger, R.; Paul, E.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K. C.; Weber, A.; Wieber, H.; Bailey, D. S.; Barret, O.; Brook, N. H.; Foster, B.; Heath, G. P.; Heath, H. F.; McFall, J. D.; Piccioni, D.; Rodrigues, E.; Scott, J.; Tapper, R. J.; Capua, M.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Jeoung, H. Y.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Ma, K. J.; Pac, M. Y.; Caldwell, A.; Liu, W.; Liu, X.; Mellado, B.; Paganis, S.; Sampson, S.; Schmidke, W. B.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Klimek, K.; Olkiewicz, K.; Piotrzkowski, K.; Przybycień, M. B.; Stopa, P.; Zawiejski, L.; Bednarek, B.; Jeleń, K.; Kisielewska, D.; Kowal, A. M.; Kowalski, T.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Szuba, D.; Kotański, A.; Bauerdick, L. A. T.; Behrens, U.; Bienlein, J. K.; Burgard, C.; Dannheim, D.; Desler, K.; Drews, G.; Fox-Murphy, A.; Fricke, U.; Goebel, F.; Göttlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G. F.; Hasell, D.; Hebbel, K.; Johnson, K. F.; Kasemann, M.; Koch, W.; Kötz, U.; Kowalski, H.; Lindemann, L.; Löhr, B.; Martínez, M.; Milite, M.; Monteiro, T.; Moritz, M.; Notz, D.; Pelucchi, F.; Petrucci, M. C.; Rohde, M.; Saull, P. R. B.; Savin, A. A.; Schneekloth, U.; Selonke, F.; Sievers, M.; Stonjek, S.; Tassi, E.; Wolf, G.; Wollmer, U.; Youngman, C.; Zeuner, W.; Coldewey, C.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.; Straub, P. B.; Barbagli, G.; Gallo, E.; Pelfer, P.; Maccarrone, G.; Votano, L.; Bamberger, A.; Benen, A.; Eisenhardt, S.; Markun, P.; Raach, H.; Wölfle, S.; Bussey, P. J.; Doyle, A. T.; Lee, S. W.; Macdonald, N.; McCance, G. J.; Saxon, D. H.; Sinclair, L. E.; Skillicorn, I. O.; Waugh, R.; Bohnet, I.; Gendner, N.; Holm, U.; Meyer-Larsen, A.; Salehi, H.; Wick, K.; Garfagnini, A.; Gialas, I.; Gladilin, L. K.; Kçira, D.; Klanner, R.; Lohrmann, E.; Poelz, G.; Zetsche, F.; Goncalo, R.; Long, K. R.; Miller, D. B.; Tapper, A. D.; Walker, R.; Mallik, U.; Cloth, P.; Filges, D.; Ishii, T.; Kuze, M.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Ahn, S. H.; Lee, S. B.; Park, S. K.; Lim, H.; Park, I. H.; Son, D.; Barreiro, F.; García, G.; Glasman, C.; Gonzalez, O.; Labarga, L.; del Peso, J.; Redondo, I.; Terrón, J.; Barbi, M.; Corriveau, F.; Hanna, D. S.; Ochs, A.; Padhi, S.; Riveline, M.; Stairs, D. G.; Wing, M.; Tsurugai, T.; Bashkirov, V.; Dolgoshein, B. A.; Dementiev, R. K.; Ermolov, P. F.; Golubkov, Y. A.; Katkov, I. I.; Khein, L. A.; Korotkova, N. A.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Y.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Vlasov, N. N.; Zotkin, S. A.; Bokel, C.; Botje, M.; Brümmer, N.; Engelen, J.; Grijpink, S.; Koffeman, E.; Kooijman, P.; Schagen, S.; van Sighem, A.; Tiecke, H.; Tuning, N.; Velthuis, J. J.; Vossebeld, J.; Wiggers, L.; de Wolf, E.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Boogert, S.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Große-Knetter, J.; Matsushita, T.; Ruske, O.; Sutton, M. R.; Walczak, R.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; Dosselli, U.; Dusini, S.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Adamczyk, L.; Iannotti, L.; Oh, B. Y.; Okrasiński, J. R.; Toothacker, W. S.; Whitmore, J. J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cormack, C.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Epperson, D.; Heusch, C.; Sadrozinski, H. F.-W.; Seiden, A.; Wichmann, R.; Williams, D. C.; Pavel, N.; Abramowicz, H.; Dagan, S.; Kananov, S.; Kreisel, A.; Levy, A.; Abe, T.; Fusayasu, T.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Inuzuka, M.; Kitamura, S.; Nishimura, T.; Arneodo, M.; Cartiglia, N.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Fagerstroem, C.-P.; Galea, R.; Koop, T.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sabetfakhri, A.; Simmons, D.; Butterworth, J. M.; Catterall, C. D.; Hayes, M. E.; Heaphy, E. A.; Jones, T. W.; Lane, J. B.; West, B. J.; Ciborowski, J.; Ciesielski, R.; Grzelak, G.; Nowak, R. J.; Pawlak, J. M.; Pawlak, R.; Smalska, B.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Z˙arnecki, A. F.; Adamus, M.; Gadaj, T.; Deppe, O.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Badgett, W. F.; Chapin, D.; Cross, R.; Foudas, C.; Mattingly, S.; Reeder, D. D.; Smith, W. H.; Vaiciulis, A.; Wildschek, T.; Wodarczyk, M.; Deshpande, A.; Dhawan, S.; Hughes, V. W.; Bhadra, S.; Catterall, C.; Cole, J. E.; Frisken, W. R.; Hall-Wilton, R.; Khakzad, M.; Menary, S.

    2000-05-01

    The first measurement of inclusive Ds+/- photoproduction at HERA has been performed with the ZEUS detector for photon-proton centre-of-mass energies 130DsX=3.79+/- 0.59(stat.)+0.26-0.46(syst.)+/-0.94(br.)nb, where the last error arises from the uncertainty in the Ds+/- decay branching ratio. The measurements are compared with inclusive D*+/- photoproduction cross sections in the same kinematic region and with QCD calculations. The Ds+/- cross sections lie above a fixed-order next-to-leading order calculation and agree better with a tree-level O(ααs3) calculation that was tuned to describe the ZEUS D*+/- cross sections. The ratio of Ds+/- to D*+/- cross sections is 0.41+/-0.07(stat.)+0.03-0.05(syst.)+/-0.10(br.). From this ratio, the strangeness-suppression factor in charm photoproduction, within the LUND string fragmentation model, has been calculated to be γs=0.27+/-0.05+/-0.07(br.). The cross-section ratio and γs are in good agreement with those obtained in charm production in e+e- annihilation.

  2. 22 CFR 19.6-4 - Date of court orders.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Date of court orders. 19.6-4 Section 19.6-4 Foreign Relations DEPARTMENT OF STATE PERSONNEL BENEFITS FOR SPOUSES AND FORMER SPOUSES OF PARTICIPANTS IN THE FOREIGN SERVICE RETIREMENT AND DISABILITY SYSTEM § 19.6-4 Date of court orders. (a) A court order directing or barring payment of a pension...

  3. 37 CFR 6.4 - Schedule for collective membership marks.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2013-07-01 2013-07-01 false Schedule for collective membership marks. 6.4 Section 6.4 Patents, Trademarks, and Copyrights UNITED STATES PATENT AND TRADEMARK... Schedule for collective membership marks. All collective membership marks in applications based on...

  4. 37 CFR 6.4 - Schedule for collective membership marks.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2011-07-01 2011-07-01 false Schedule for collective membership marks. 6.4 Section 6.4 Patents, Trademarks, and Copyrights UNITED STATES PATENT AND TRADEMARK... Schedule for collective membership marks. All collective membership marks in applications based on...

  5. 37 CFR 6.4 - Schedule for collective membership marks.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2010-07-01 2010-07-01 false Schedule for collective membership marks. 6.4 Section 6.4 Patents, Trademarks, and Copyrights UNITED STATES PATENT AND TRADEMARK... Schedule for collective membership marks. All collective membership marks in applications based on...

  6. 37 CFR 6.4 - Schedule for collective membership marks.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2012-07-01 2012-07-01 false Schedule for collective membership marks. 6.4 Section 6.4 Patents, Trademarks, and Copyrights UNITED STATES PATENT AND TRADEMARK... Schedule for collective membership marks. All collective membership marks in applications based on...

  7. 37 CFR 6.4 - Schedule for collective membership marks.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 37 Patents, Trademarks, and Copyrights 1 2014-07-01 2014-07-01 false Schedule for collective membership marks. 6.4 Section 6.4 Patents, Trademarks, and Copyrights UNITED STATES PATENT AND TRADEMARK... Schedule for collective membership marks. All collective membership marks in applications based on...

  8. 15 CFR 6.4 - Adjustments to penalties.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 15 Commerce and Foreign Trade 1 2012-01-01 2012-01-01 false Adjustments to penalties. 6.4 Section 6.4 Commerce and Foreign Trade Office of the Secretary of Commerce CIVIL MONETARY PENALTY INFLATION..., Collection of Foreign Trade Statistics—Delinquency on Delayed Filing of Export Documentation; maximum...

  9. 15 CFR 6.4 - Adjustments to penalties.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 15 Commerce and Foreign Trade 1 2014-01-01 2014-01-01 false Adjustments to penalties. 6.4 Section 6.4 Commerce and Foreign Trade Office of the Secretary of Commerce CIVIL MONETARY PENALTY INFLATION..., Collection of Foreign Trade Statistics—Delinquency on Delayed Filing of Export Documentation; maximum...

  10. 15 CFR 6.4 - Adjustments to penalties.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 15 Commerce and Foreign Trade 1 2013-01-01 2013-01-01 false Adjustments to penalties. 6.4 Section 6.4 Commerce and Foreign Trade Office of the Secretary of Commerce CIVIL MONETARY PENALTY INFLATION..., Collection of Foreign Trade Statistics—Delinquency on Delayed Filing of Export Documentation; maximum...

  11. Measurements of Heavy Flavour Photoproduction at HERA

    NASA Astrophysics Data System (ADS)

    Mergelmeyer, Sebastian

    2013-12-01

    Recent measurements of open charm and beauty photoproduction with the H1 and ZEUS detectors at the e±p-collider HERA are presented. These measurements reveal valuable details about the inner structure of the proton and the photon, the fragmentation of quarks into jets, and allow tests of perturbative QCD. Various experimental techniques were employed to identify and extract the heavy-quark signal. Their results are discussed, and compared to each other and to NLO QCD calculations. In addition the determination of charm fragmentation fractions is presented.

  12. Status of Meson Photoproduction Experiments with CLAS

    SciTech Connect

    Pasyuk, Eugene A.

    2014-01-01

    A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to baryon spectroscopy. Meson photoproduction experiments are essential part of this program. CEBAF Large Acceptance Spectrometer (CLAS) and availability of circularly and linearly polarized tagged photon beams in combination with longitudinally and transversely polarized frozen spin targets provide unique conditions for this type of experiments. For the first time, a complete or nearly complete measurement became possible and will allow model independent extraction of the reaction amplitude. The measurements were complete with both proton and deuteron targets. An overview of the collected experimental data will be presented.

  13. Higgs boson photoproduction at the LHC

    SciTech Connect

    Ducati, M. B. Gay; Silveira, G. G.

    2011-07-15

    We present the current development of the photoproduction approach for the Higgs boson with its application to pp and pA collisions at the LHC. We perform a different analysis for the Gap Survival Probability, where we consider a probability of 3% and also a more optimistic value of 10% based on the HERA data for dijet production. As a result, the cross section for the exclusive Higgs boson production is about 2 fb and 6 fb in pp collisions and 617 and 2056 fb for pPb collisions, considering the gap survival factor of 3% and 10%, respectively.

  14. Charm and Beauty in Photoproduction at HERA

    NASA Astrophysics Data System (ADS)

    Dobre, Monica

    2014-04-01

    The photoproduction of beauty and charm quarks at the ep collider HERA are presented. The b-quarks production was investigated in the bb → eeX' channel and the differential production cross section was measured as a function of the average transverse momentum of the beauty quarks down to the threshold. The cross section of D* meson decaying in the golden channel was determined both inclusively and in D*-tagged dijet events. Exploiting the characteristics of the heavy-flavoured hadron decays, beauty and charm quark cross sections were also measured in dijet events using secondary vertices or semi-muonic decays.

  15. {Lambda}(1520) photoproduction with Regge contribution

    SciTech Connect

    Nam, Seung-il; Yu, Byung-Geel; Kao, Chung-Wen

    2011-10-21

    In this talk, we report our recent progresses on the {Lambda}(1520) photoproduction using the effective Lagrangian approach. In addition to the tree-level Born diagrams, we take into account the Regge-trajectories for the possible strange-meson exchanges in the t channel. We compute the angular and energy dependences of the production process, including polarization observables, such as the photon-beam asymmetry and the polarization-transfer coefficients, resulting in good qualitative agreement with current experimental data. We also compute the K{sup -} angle distribution function in the Gottfried-Jackson frame, using the polarization-transfer coefficients in the z direction.

  16. Antibaryon photoproduction using CLAS at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Phelps, W.; Guo, L.

    2016-05-01

    There is little known about baryon-antibaryon photoproduction mechanisms. Three reactions, γ p →p p p ¯, γ p →p p n ¯π-, and γ p →p n p ¯π+ have been investigated for the photon energy range of 3.95-5.45 GeV. The data were from the g12 run period taken with the CLAS detector using a liquid hydrogen target in Hall B at Thomas Jefferson National Accelerator Facility. This experiment had high statistics, with an integrated luminosity of 68 pb-1. General features of the data and preliminary cross sections are presented.

  17. Hydrogen photoproduction of A. Variabilis incorporated in a photobioreactor

    NASA Astrophysics Data System (ADS)

    Liu, Jian-Guo; Hall, David O.; Rao, Krishna K.; Tsygankov, Anatoly A.; Sveshnikov, Dmitry A.

    1998-03-01

    H2 photoproduction and nitrogenase activities in two strains of Anabaena variabilis marked wild type ATCC 29413 and mutant PK84 exposed to thermal stress (temperature higher than the normal incubation temperature of 30°C) were studied. Cultures of both strains collected from any interval of logarithmic growth phase exhibited high H2 photoproduction and nitrogenase activities when exposed to limited time heat shock during the assay process. In contrast, the algal H2 photoproduction rate of both strains fluctuated with long term thermal stress caused by increasing the growth temperature from 30°C to 36°C. The changes of nitrogenase (the key H2 photobiosynthetic enzyme) activities in the mutant PK84 showed variation tendency similar to that of H2 photoproduction during exposure to thermal stress, indicating that fluctuation of H2 photoproduction in the mutant was mainly due to the variation of nitrogenase activities. A temporary maximal H2 photoproduction in the mutant PK84 (wild type ATCC29413) was observed when cells grew at 36°C for 14 (6) days. However, the responses of nitrogenase activities in the wild type to thermal stress were not completely similar to those in the mutant in spite of similar variations of H2 photoproduction in both strains. The data obtained in these studies suggested that the activities of other enzymes (in the wild strain) involved in H2 photoproduction were affected by thermal stress since H2 photoproduction maximized or dropped to 0 without variation tendency similar to that of nitrogenase activities. Furthermore, an enhancement of H2 photoproduction speed of the mutant strain cultured in a 4.4 L laboratory photobioreactor was also observed when it was subjected to short time continuous charge of argon, and temperature rise. All these results indicated that high temperature plays an important role in the photo-autotrophic H2 photoproduction, and that long term thermal stress is unfavourable for net H2 photoproduction in both strains

  18. GlueX: Meson Spectroscopy in Photoproduction

    SciTech Connect

    Salgado, Carlos; Smith, Elton S.

    2014-03-01

    The goal of the GlueX experiment \\cite{gluex} is to provide crucial data to help understand the soft gluonic fields responsible for binding quarks in hadrons. Hybrid mesons, and in particular exotic hybrid mesons, provide the ideal laboratory for testing QCD in the confinement regime since these mesons explicitly manifest the gluonic degrees of freedom. Photoproduction is expected to be effective in producing exotic hybrids but there is little data on the photoproduction of light mesons. GlueX will use the new 12-GeV electron beam at Jefferson Lab to produce a 9-GeV beam of linearly polarized photons using the technique of coherent bremsstrahlung. A solenoid-based hermetic detector is under construction, which will be used to collect data on meson production and decays. These data will also be used to study the spectrum of conventional mesons, including the poorly understood excited vector mesons. This talk will give an update on the experiment as well as describe theoretical developments \\cite{Dudek:2011bn} to help understand how these data can provide insights into the fundamental theory of strong interactions.

  19. Photoproduction of the rho meson and its magnetic moments

    SciTech Connect

    Kaneko, Hiromi; Hosaka, Atsushi; Scholten, Olaf

    2011-10-21

    We study photoproduction of {rho} meson in a model of hidden local symmetry. We introduce the {rho} meson on a hidden gauge boson and phenomenological {rho} meson-nucleon Lagrangian is constructed respecting chiral symmetry. It turns out that the {sigma}-exchange interaction plays an important role in neutral {rho} meson photoproduction to reproduce the experimental cross sections. In charged {rho} meson photoproduction, the model takes into account the {rho} meson magnetic moments from the three-point vertex in the kinetic terms. We show that the magnetic moment of the charged {rho} meson has a significant effect on the total cross sections in proportion to the photon energies.

  20. Measurement of dijet cross sections for events with a leading neutron in photoproduction at HERA

    NASA Astrophysics Data System (ADS)

    Breitweg, J.; Chekanov, S.; Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Pellegrino, A.; Repond, J.; Stanek, R.; Yoshida, R.; Mattingly, M. C. K.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Sartorelli, G.; Zichichi, A.; Amelung, C.; Bornheim, A.; Brock, I.; Coböken, K.; Crittenden, J.; Deffner, R.; Hartmann, H.; Heinloth, K.; Hilger, E.; Irrgang, P.; Jakob, H.-P.; Kappes, A.; Katz, U. F.; Kerger, R.; Paul, E.; Rautenberg, J.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K. C.; Weber, A.; Wieber, H.; Bailey, D. S.; Barret, O.; Brook, N. H.; Foster, B.; Heath, G. P.; Heath, H. F.; Rodrigues, E.; Scott, J.; Tapper, R. J.; Capua, M.; Schioppa, M.; Susinno, G.; Jeoung, H. Y.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Ma, K. J.; Pac, M. Y.; Caldwell, A.; Liu, W.; Liu, X.; Mellado, B.; Paganis, S.; Sampson, S.; Schmidke, W. B.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Klimek, K.; Olkiewicz, K.; Piotrzkowski, K.; Przybycień, M. B.; Stopa, P.; Zawiejski, L.; Bednarek, B.; Jeleń, K.; Kisielewska, D.; Kowal, A. M.; Kowalski, T.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Szuba, D.; Kotański, A.; Bauerdick, L. A. T.; Behrens, U.; Bienlein, J. K.; Borras, K.; Chiochia, V.; Dannheim, D.; Desler, K.; Drews, G.; Fox-Murphy, A.; Fricke, U.; Goebel, F.; Goers, S.; Göttlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G. F.; Hebbel, K.; Hillert, S.; Koch, W.; Kötz, U.; Kowalski, H.; Labes, H.; Löhr, B.; Mankel, R.; Martens, J.; Martínez, M.; Milite, M.; Moritz, M.; Notz, D.; Petrucci, M. C.; Polini, A.; Rohde, M.; Savin, A. A.; Schneekloth, U.; Selonke, F.; Sievers, M.; Stonjek, S.; Wolf, G.; Wollmer, U.; Youngman, C.; Zeuner, W.; Coldewey, C.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.; Straub, P. B.; Barbagli, G.; Gallo, E.; Parenti, A.; Pelfer, P. G.; Bamberger, A.; Benen, A.; Coppola, N.; Eisenhardt, S.; Markun, P.; Raach, H.; Wölfle, S.; Bussey, P. J.; Bell, M.; Doyle, A. T.; Glasman, C.; Lee, S. W.; Lupi, A.; Macdonald, N.; McCance, G. J.; Saxon, D. H.; Sinclair, L. E.; Skillicorn, I. O.; Waugh, R.; Bohnet, I.; Gendner, N.; Holm, U.; Meyer-Larsen, A.; Salehi, H.; Wick, K.; Carli, T.; Garfagnini, A.; Gialas, I.; Gladilin, L. K.; Kçira, D.; Klanner, R.; Lohrmann, E.; Gonçalo, R.; Long, K. R.; Miller, D. B.; Tapper, A. D.; Walker, R.; Cloth, P.; Filges, D.; Ishii, T.; Kuze, M.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Ahn, S. H.; Lee, S. B.; Park, S. K.; Lim, H.; Son, D.; Barreiro, F.; García, G.; González, O.; Labarga, L.; del Peso, J.; Redondo, I.; Terrón, J.; Vázquez, M.; Barbi, M.; Corriveau, F.; Hanna, D. S.; Ochs, A.; Padhi, S.; Stairs, D. G.; Wing, M.; Tsurugai, T.; Antonov, A.; Bashkirov, V.; Danilov, M.; Dolgoshein, B. A.; Gladkov, D.; Sosnovtsev, V.; Suchkov, S.; Dementiev, R. K.; Ermolov, P. F.; Golubkov, Yu. A.; Katkov, I. I.; Khein, L. A.; Korotkova, N. A.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Yu.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Vlasov, N. N.; Zotkin, S. A.; Bokel, C.; Botje, M.; Brümmer, N.; Engelen, J.; Grijpink, S.; Koffeman, E.; Kooijman, P.; Schagen, S.; van Sighem, A.; Tassi, E.; Tiecke, H.; Tuning, N.; Velthuis, J. J.; Vossebeld, J.; Wiggers, L.; de Wolf, E.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Boogert, S.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Große-Knetter, J.; Matsushita, T.; Ruske, O.; Sutton, M. R.; Walczak, R.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; Dusini, S.; Limentani, S.; Longhin, A.; Posocco, M.; Stanco, L.; Turcato, M.; Adamczyk, L.; Iannotti, L.; Oh, B. Y.; Okrasiński, J. R.; Saull, P. R. B.; Toothacker, W. S.; Whitmore, J. J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cormack, C.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Epperson, D.; Heusch, C.; Sadrozinski, H. F.-W.; Seiden, A.; Wichmann, R.; Williams, D. C.; Park, I. H.; Pavel, N.; Abramowicz, H.; Dagan, S.; Kananov, S.; Kreisel, A.; Levy, A.; Abe, T.; Fusayasu, T.; Kohno, T.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Inuzuka, M.; Kitamura, S.; Matsuzawa, K.; Nishimura, T.; Arneodo, M.; Cartiglia, N.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Bailey, D. C.; Fagerstroem, C.-P.; Galea, R.; Koop, T.; Levman, G. M.; Martin, J. F.; Mirea, A.; Sabetfakhri, A.; Butterworth, J. M.; Hayes, M. E.; Heaphy, E. A.; Jones, T. W.; Lane, J. B.; West, B. J.; Ciborowski, J.; Ciesielski, R.; Grzelak, G.; Nowak, R. J.; Pawlak, J. M.; Pawlak, R.; Smalska, B.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Gadaj, T.; Deppe, O.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Badgett, W. F.; Chapin, D.; Cross, R.; Foudas, C.; Mattingly, S.; Reeder, D. D.; Smith, W. H.; Vaiciulis, A.; Wildschek, T.; Wodarczyk, M.; Deshpande, A.; Dhawan, S.; Hughes, V. W.; Bhadra, S.; Catterall, C.; Cole, J. E.; Frisken, W. R.; Hall-Wilton, R.; Khakzad, M.; Menary, S.; ZEUS Collaboration

    2001-02-01

    Differential cross sections for dijet photoproduction in association with a leading neutron using the reaction e++ p→ e++ n+jet+jet+ Xr have been measured with the ZEUS detector at HERA using an integrated luminosity of 6.4 pb -1. The fraction of dijet events with a leading neutron in the final state was studied as a function of the jet kinematic variables. The cross sections were measured for jet transverse energies ETjet>6 GeV, neutron energy En>400 GeV, and neutron production angle θn<0.8 mrad. The data are broadly consistent with factorization of the lepton and hadron vertices and with a simple one-pion-exchange model.

  1. Modelling vibrational coherence in the primary rhodopsin photoproduct

    NASA Astrophysics Data System (ADS)

    Weingart, O.; Garavelli, M.

    2012-12-01

    Molecular dynamics simulations of the rhodopsin photoreaction reveal coherent low frequency oscillations in the primary photoproduct (photorhodopsin), with frequencies slightly higher than observed in the experiment. The coherent molecular motions in the batho-precursor can be attributed to the activation of ground state vibrational modes in the hot photo-product, involving out-of-plane deformations of the carbon skeleton. Results are discussed and compared with respect to spectroscopic data and suggested reaction mechanisms.

  2. Chemical syntheses of oligodeoxyribonucleotides containing spore photoproduct

    PubMed Central

    Jian, Yajun; Li, Lei

    2013-01-01

    5-(α-Thyminyl)-5,6-dihydrothymine, also called spore photoproduct or SP, is commonly found in the genomic DNA of UV irradiated bacterial endospores. Despite the fact that SP was discovered nearly 50 years ago, its biochemical impact is still largely unclear due to the difficulty to prepare SP containing oligonucleotide in high purity. Here, we report the first synthesis of the phosphoramidite derivative of dinucleotide SP TpT, which enables successful incorporation of SP TpT into oligodeoxyribonucleotides with high efficiency via standard solid phase synthesis. This result provides the scientific community a reliable means to prepare SP containing oligonucleotides, laying the foundation for future SP biochemical studies. Thermal denaturation studies of the SP containing oligonucleotide found that SP destabilizes the duplex by 10–20 kJ/mole, suggesting that its presence in the spore genomic DNA may alter the DNA local conformation. PMID:23506239

  3. Photoproduction of eta-mesic 3He.

    PubMed

    Pfeiffer, M; Ahrens, J; Annand, J R M; Beck, R; Caselotti, G; Cherepnya, S; Föhl, K; Fog, L S; Hornidge, D; Janssen, S; Kashevarov, V; Kondratiev, R; Kotulla, M; Krusche, B; McGeorge, J C; MacGregor, I J D; Mengel, K; Messchendorp, J G; Metag, V; Novotny, R; Rost, M; Sack, S; Sanderson, R; Schadmand, S; Thomas, A; Watts, D P

    2004-06-25

    The photoproduction of eta-mesic 3He has been investigated using the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI. The total inclusive cross section for the reaction gamma3He-->etaX has been measured for photon energies from threshold to 820 MeV. The total and angular differential coherent eta cross sections have been extracted up to energies of 745 MeV. A resonancelike structure just above the eta production threshold with an isotropic angular distribution suggests the existence of a resonant quasibound state. This is supported by studies of a competing decay channel of such a quasibound eta-mesic nucleus into pi(0)pX. A binding energy of (-4.4+/-4.2) MeV and a width of (25.6+/-6.1) MeV is deduced for the quasibound eta-mesic state in 3He. PMID:15244998

  4. Incoherent neutral pion photoproduction on 12C.

    PubMed

    Tarbert, C M; Watts, D P; Aguar, P; Ahrens, J; Annand, J R M; Arends, H J; Beck, R; Bekrenev, V; Boillat, B; Braghieri, A; Branford, D; Briscoe, W J; Brudvik, J; Cherepnya, S; Codling, R; Downie, E J; Föhl, K; Glazier, D I; Grabmayr, P; Gregor, R; Heid, E; Hornidge, D; Jahn, O; Kashevarov, V L; Knezevic, A; Kondratiev, R; Korolija, M; Kotulla, M; Krambrich, D; Krusche, B; Lang, M; Lisin, V; Livingston, K; Lugert, S; Macgregor, I J D; Manley, D M; Martinez, M; McGeorge, J C; Mekterovic, D; Metag, V; Nefkens, B M K; Nikolaev, A; Novotny, R; Owens, R O; Pedroni, P; Polonski, A; Prakhov, S N; Price, J W; Rosner, G; Rost, M; Rostomyan, T; Schadmand, S; Schumann, S; Sober, D; Starostin, A; Supek, I; Thomas, A; Unverzagt, M; Walcher, Th; Zehr, F

    2008-04-01

    We present the first detailed measurement of incoherent photoproduction of neutral pions to a discrete state of a residual nucleus. The 12C(gamma,pi(0))(12)C*(4.4 MeV) reaction has been studied with the Glasgow photon tagger at MAMI employing a new technique which uses the large solid angle Crystal Ball detector both as a pi(0) spectrometer and to detect decay photons from the excited residual nucleus. The technique has potential applications to a broad range of future nuclear measurements with the Crystal Ball and similar detector systems elsewhere. Such data are sensitive to the propagation of the Delta in the nuclear medium and will give the first information on matter transition form factors from measurements with an electromagnetic probe. The incoherent cross sections are compared to two theoretical predictions including a Delta-hole model. PMID:18517938

  5. Kaon photoproduction and electroproduction near threshold

    SciTech Connect

    Mart, T.

    2011-10-21

    We analyze the electromagnetic production of K{sup +}{Lambda} and K{sup 0}{Lambda} near their production thresholds by using isobar models. In the K{sup +}{Lambda} channel we show that the model can nicely describe the available experimental data. In the K{sup 0}{Lambda} channel we demonstrate that the K{sup 0} charge form factor has sizable effects on the longitudinal cross section. By extending the model up to W = 1730 MeV, we are able to observe the existence of the narrow P{sub 11}(J{sup p} = 1/2{sup +}) resonance in the kaon photoproduction process. It is found that the most convincing mass (width) of this resonance is 1650 MeV(5 MeV).

  6. Photocouplings at the pole from pion photoproduction

    SciTech Connect

    Ronchen, D.; Doring, M.; Huang, F.; Haberzettl, H.; Haidenbauer, J.; Hanhart, C.; Krewald, S.; MeiBner, U. -G.; Nakayama, K.

    2014-06-24

    The reactions γp → π0p and γp → π+n are analyzed in a semi-phenomenological approach up to E ~ 2.3 GeV. Fits to differential cross section and single and double polarization observables are performed. A good overall reproduction of the available photoproduction data is achieved. The Julich2012 dynamical coupled-channel model -which describes elastic πN scattering and the world data base of the reactions πN → ηN, KΛ, and KΣ at the same time– is employed as the hadronic interaction in the final state. Furthermore, the framework guarantees analyticity and, thus, allows for a reliable extraction of resonance parameters in terms of poles and residues. In particular, the photocouplings at the pole can be extracted and are presented.

  7. Photocouplings at the pole from pion photoproduction

    DOE PAGESBeta

    Ronchen, D.; Doring, M.; Huang, F.; Haberzettl, H.; Haidenbauer, J.; Hanhart, C.; Krewald, S.; MeiBner, U. -G.; Nakayama, K.

    2014-06-24

    The reactions γp → π0p and γp → π+n are analyzed in a semi-phenomenological approach up to E ~ 2.3 GeV. Fits to differential cross section and single and double polarization observables are performed. A good overall reproduction of the available photoproduction data is achieved. The Julich2012 dynamical coupled-channel model -which describes elastic πN scattering and the world data base of the reactions πN → ηN, KΛ, and KΣ at the same time– is employed as the hadronic interaction in the final state. Furthermore, the framework guarantees analyticity and, thus, allows for a reliable extraction of resonance parameters in termsmore » of poles and residues. In particular, the photocouplings at the pole can be extracted and are presented.« less

  8. Microbial degradation of thidiazuron and its photoproduct.

    PubMed

    Benezet, H J; Knowles, C O

    1982-01-01

    Degradation of the cotton defoliant thidiazuron and its photoproduct photothidiazuron by soil and thirteen species of microorganisms was examined. Aspergillus versicolor, Torula rosea, and Flavobacter sp. were most active in degrading thidiazuron. Unknown water-soluble metabolites and phenylurea were the major products. A. versicolor and Penicillium cyclopium were most active in degrading photothidiazuron. 4-Hydroxyphenylphotothidiazuron was the major organosoluble product formed by A. versicolor; phenylurea and an unidentified metabolite constituted the major organosoluble products from P. cyclopium. Both microbes also formed appreciable water-soluble metabolites. Radioactive carbon dioxide was formed from thidiazuron-aniline-14C by Oscillatoria sp. but not by Chlorella sp., suggesting that the former algal species utilized the defoliant as an energy source. PMID:7073312

  9. Photoproduction of scalar mesons at medium energies

    SciTech Connect

    Da Silva, M. L.; Machado, M. V.

    2013-03-25

    In this work we will focus on photoproduction of mesons states a{sub 0}(980), f{sub 0}(1500) and f{sub 0}(1710). The f{sub 0}(1500) and f{sub 0}(1710) mesons will be considered in distinct mixing possibilities and assuming that a{sub 0}(980) is member of the ground-state nonet. The theoretical formalism is the Regge approach with reggeized {rho} and {omega} exchange. The differential and integrated total cross section are computed for the cases of the mesons a{sub 0}(980), f{sub 0}(1500) and f{sub 0}(1710) focusing the GlueX energy regime with photon energy E = 9 GeV.

  10. Meson photoproduction from the nucleon at CLAS

    SciTech Connect

    Daniel P. Watts

    2012-01-01

    The excitation spectrum of the nucleon provides a stringent constraint on the dynamics and interactions of its internal constituents and therefore probes the mechanism of confinement in the light quark sector. Our detailed knowlege of this excitation spectrum is poor, with many predicted states not yet observed in experiment and many 'established' states having poorly known properties. To address these shortcomings a worldwide effort is currently underway exploiting the latest generation of electron and photon beams in detailed studies of meson photoproduction from nucleon targets. A major contribution to this effort will come from the experimental programme at Jefferson Lab exploiting the frozen spin target (FROST) with the CLAS spectrometer. The status of this project will be presented along with preliminary results and analyses.

  11. Model discrimination in pseudoscalar-meson photoproduction

    NASA Astrophysics Data System (ADS)

    Nys, J.; Ryckebusch, J.; Ireland, D. G.; Glazier, D. I.

    2016-08-01

    To learn about a physical system of interest, experimental results must be able to discriminate among models. We introduce a geometrical measure to quantify the distance between models for pseudoscalar-meson photoproduction in amplitude space. Experimental observables, with finite precision, map to probability distributions in amplitude space, and the characteristic width scale of such distributions needs to be smaller than the distance between models if the observable data are going to be useful. We therefore also introduce a method for evaluating probability distributions in amplitude space that arise as a result of one or more measurements, and show how one can use this to determine what further measurements are going to be necessary to be able to discriminate among models.

  12. Photoproduction of scalar mesons at CLAS

    NASA Astrophysics Data System (ADS)

    Chandavar, Shloka; Hicks, Kenneth; Weygand, Dennis; CLAS Collaboration

    2013-10-01

    A single gluon, which carries color charge, cannot exist independently outside a hadron. Lattice QCD calculations in pure SU(3), however, predict the existence of glueballs which are bound states of two or more gluons. In the real world, the challenge to identify glueballs experimentally is the fact they mix with meson states. The f0 (1500) is one of several candidates for the lightest glueball, with JPC =0++ . We investigate the presence of this particle in photoproduction by analyzing the reaction γp -->fJ p -->KS0KS0 p --> 2 (π+π-) p . This reaction was studied using data from the g12 experiment performed using the CLAS detector at Jefferson Lab. A preliminary partial wave analysis, performed on the KS0KS0 invariant mass spectrum, will be presented. These results update those presented for this reaction channel at previous conferences. This work is supported by grant from NSF.

  13. 34 CFR 6.4 - Central records; confidentiality.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Education Office of the Secretary, Department of Education INVENTIONS AND PATENTS (GENERAL) § 6.4 Central records; confidentiality. Central files and records shall be maintained of all inventions, patents, and... Department under such patents. Invention reports required from employees or others for the purpose...

  14. 34 CFR 6.4 - Central records; confidentiality.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Education Office of the Secretary, Department of Education INVENTIONS AND PATENTS (GENERAL) § 6.4 Central records; confidentiality. Central files and records shall be maintained of all inventions, patents, and... Department under such patents. Invention reports required from employees or others for the purpose...

  15. 34 CFR 6.4 - Central records; confidentiality.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Education Office of the Secretary, Department of Education INVENTIONS AND PATENTS (GENERAL) § 6.4 Central records; confidentiality. Central files and records shall be maintained of all inventions, patents, and... Department under such patents. Invention reports required from employees or others for the purpose...

  16. 34 CFR 6.4 - Central records; confidentiality.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Education Office of the Secretary, Department of Education INVENTIONS AND PATENTS (GENERAL) § 6.4 Central records; confidentiality. Central files and records shall be maintained of all inventions, patents, and... Department under such patents. Invention reports required from employees or others for the purpose...

  17. 34 CFR 6.4 - Central records; confidentiality.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Education Office of the Secretary, Department of Education INVENTIONS AND PATENTS (GENERAL) § 6.4 Central records; confidentiality. Central files and records shall be maintained of all inventions, patents, and... Department under such patents. Invention reports required from employees or others for the purpose...

  18. 41 CFR 51-6.4 - Military resale commodities.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 1 2010-07-01 2010-07-01 true Military resale... PROCEDURES § 51-6.4 Military resale commodities. (a) Purchase procedures for ordering military resale commodities are available from the central nonprofit agencies. Authorized resale outlets (military...

  19. 41 CFR 51-6.4 - Military resale commodities.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 41 Public Contracts and Property Management 1 2011-07-01 2009-07-01 true Military resale... PROCEDURES § 51-6.4 Military resale commodities. (a) Purchase procedures for ordering military resale commodities are available from the central nonprofit agencies. Authorized resale outlets (military...

  20. DETERMINATION OF APPARENT QUANTUM YIELD SPECTRA FOR THE FORMATION OF BIOLOGICALLY LABILE PHOTOPRODUCTS

    EPA Science Inventory

    Quantum yield spectra for the photochemical formation of biologically labile photoproducts from dissolved organic matter (DOM) have not been available previously, although they would greatly facilitate attempts to model photoproduct formation rates across latitudinal, seasonal, a...

  1. Photoproduction of the K+ K0-(1750)

    SciTech Connect

    Mitchell, Ryan Edward

    2003-01-01

    While photoproduction has often been advertised as an important environment in which to study light meson spectroscopy, solid experimental results are sparse. In fact, beyond the relatively straightforward photoproduction of the {rho}, {omega}, and {phi} mesons, the few results of exclusive photoproduction that do exist are poorly understood, and several, perhaps, have even been misinterpreted. After extensively reviewing the sometimes tenuous history of the exclusive photoproduction of the ''{rho}{sup 1}(1600)'', the ''{omega}{pi}{sup 0}(1250)'', the ''{omega}(1650)'', and the ''K{sup +}K{sup -}(1750)'', new results from the E831/FOCUS photoproduction experiment at Fermilab are presented which address the interpretation of the K{sup +}K{sup -}(1750). This enhancement in low-p{sub T} K{sup +}K{sup -} pairs at a mass near 1750 MeV/c{sup 2} has been observed by several previous photoproduction experiments, but, despite several apparent inconsistencies, it has always been interpreted as the J{sup PC} = 1{sup --} {phi}(1680) meson. With nearly two orders of magnitude more events than any previous observation of the K{sup +}K{sup -}(1750), and based on precise measurements of its mass and width, and its absence from the K*K final state, the FOCUS data can finally render this interpretation implausible. In addition, several steps have been taken towards establishing a new interpretation. Based on limited angular analyses of its decay and the beam energy dependence of its production, they argue that, in the absence of any wild interference scenarios, the K{sup +}K{sup -}(1750) has J{sup PC} {ne} 1{sup --}, and, in fact, the most likely assignment appears to be 2{sup ++}. It is hoped that this work can help set the stage for future reevaluations and new insights in photoproduction.

  2. Photoproduction of K Λ on the proton

    NASA Astrophysics Data System (ADS)

    Skoupil, D.; Bydžovský, P.

    2016-02-01

    Kaon photoproduction on the proton is studied in the resonance region using an isobar model. The higher-spin nucleon (3/2 and 5/2) and hyperon (3/2) resonances were included in the model utilizing the consistent formalism by Pascalutsa, and they were found to play an important role in data description. The spin-1/2 and spin-3/2 hyperon resonances in combination with the Born terms contribute significantly to the background part of the amplitude. Various forms of the hadron form factor were considered in the construction, and the dipole and multidipole forms were selected as those most suitable for the data description. Model parameters were fitted to new experimental data from CLAS, LEPS, and GRAAL collaborations, and two versions of the model, BS1 and BS2, were chosen. Both models provide a good overall description of the data for the center-of-mass energies from the threshold up to 2.4 GeV. Predicted cross sections of the models at very small kaon angles being consistent with results of the Saclay-Lyon model indicate that the models could be also successful in predicting the hypernucleus production cross sections. Although kaon photoproduction takes place in the third-resonance region with many resonant states, the total number of included resonances, 15 and 16, is quite moderate, and it is comparable with numbers of resonances in other models. The set of chosen nucleon resonances overlaps well with the set of the most probable contributing states determined in the Bayesian analysis with the Regge-plus-resonance model. Particularly, we confirm that the missing resonances P13(1900 ) and D13(1875 ) do play an important role in the description of data. However, the spin-1/2 state P11(1880 ) included in the Bayesian analysis was replaced in our analysis with the near-mass spin-5/2 state N*(1860 ) , recently considered by the Particle Data Group.

  3. Neutral histidine and photoinduced electron transfer in DNA photolyases.

    PubMed

    Domratcheva, Tatiana

    2011-11-16

    The two major UV-induced DNA lesions, the cyclobutane pyrimidine dimers (CPD) and (6-4) pyrimidine-pyrimidone photoproducts, can be repaired by the light-activated enzymes CPD and (6-4) photolyases, respectively. It is a long-standing question how the two classes of photolyases with alike molecular structure are capable of reversing the two chemically different DNA photoproducts. In both photolyases the repair reaction is initiated by photoinduced electron transfer from the hydroquinone-anion part of the flavin adenine dinucleotide (FADH(-)) cofactor to the photoproduct. Here, the state-of-the-art XMCQDPT2-CASSCF approach was employed to compute the excitation spectra of the respective active site models. It is found that protonation of His365 in the presence of the hydroquinone-anion electron donor causes spontaneous, as opposed to photoinduced, coupled proton and electron transfer to the (6-4) photoproduct. The resulting neutralized biradical, containing the neutral semiquinone and the N3'-protonated (6-4) photoproduct neutral radical, corresponds to the lowest energy electronic ground-state minimum. The high electron affinity of the N3'-protonated (6-4) photoproduct underlines this finding. Thus, it is anticipated that the (6-4) photoproduct repair is assisted by His365 in its neutral form, which is in contrast to the repair mechanisms proposed in the literature. The repair via hydroxyl group transfer assisted by neutral His365 is considered. The repair involves the 5'base radical anion of the (6-4) photoproduct which in terms of electronic structure is similar to the CPD radical anion. A unified model of the CPD and (6-4) photoproduct repair is proposed. PMID:21970417

  4. Laser shock peening of titanium 6-4 alloy

    NASA Astrophysics Data System (ADS)

    Brar, N. S.; Hopkins, A.; Laber, M. W.

    2000-04-01

    Laser shock peening of titanium 6-4 has been shown to improve its high cycle fatigue life. Residual compressive stresses generated on the surface of titanium 6-4, as a result of laser shocking, have shown dramatic improvement in the performance of aircraft turbine blades. Laser shocking of titanium was carried out with a 20 ns pulse width, 50 joule pulsed laser, operated by LSP Technologies, Columbus, OH. Titanium disks, 20-mm in diameter, and ranging in thicknesses from zero (bare LiF) to 3-mm were subjected to laser shock to monitor amplitude and temporal stress profiles of the pulsed laser. Laser shock stress amplitudes on the back of titanium disks were monitored with VISAR using LiF as the window material. The peak shock stress produced in LiF (titanium thickness zero) was measured to be 16±1 GPa. The laser shock amplitude decays to about 2.7 GPa while propagating through 3-mm thick disk of titanium 6-4.

  5. Laser Shock Peening of Titanium 6-4 Alloy

    NASA Astrophysics Data System (ADS)

    Hopkins, Alan; Laber, Mark; Brar, Nachhatter S.

    1999-06-01

    shock 99 Laser shock peening of titanium 6-4 has been shown to improve its high cycle fatigue life. Residual compressive stresses generated on the surface of titanium 6-4, as a result of laser shocking, have shown dramatic improvement in the performance of aircraft turbine blades. Laser shocking of titanium was carried out with a 20 ns pulse width, 50 joule pulsed laser, operated by LSP Technologies, Columbus, OH. Disks of titanium, 0 to 3-mm thick and 20-mm in diameter, were subjected to the pulsed laser to monitor amplitude and temporal stress profiles of laser shock. Laser shock stress amplitudes on the back of titanium disks were monitored with VISAR using LiF as the window material. The peak shock stress produced in LiF (titanium thickness zero) was measured to be 16±1 GPa. The laser shock amplitude decays to about 2.6 GPa while propagating through 3-mm thick disk of titanium 6-4. *Supported by the U.S. Air Force Research Laboratory

  6. Search for Strangeonia in Photoproduction using CLAS

    SciTech Connect

    Saini, Mukesh

    2010-08-05

    The HyCLAS experiment at Jefferson Lab is a program to search for new and unusual mesons produced via photoproduction. The strangeonia sector is poorly known and a main component of this program is a search for new strangeonium states. The reaction {gamma}p{yields}p{phi}{eta} is an ideal channel to look for strangeonium states due to the strangeness content of both the {phi} and {eta}. The data was acquired at the JLAB CLAS facility using a 4-5.5 GeV tagged photon beam. The {phi} meson is identified via the K{sup +}K- decay. The recoil proton is observed in the CLAS spectrometer and the {eta} meson is identified through the missing mass. Also of interest is the search for strangeonia decaying to {phi}{pi}{sup 0} and {phi}{omega}. These channels are OZI suppressed for qq-bar mesons and an observation of a meson decaying to these channels would provide a strong evidence of mesons beyond qqa-bar. Preliminary results describing the data quality, kinematics and dynamics will be shown.

  7. Coherent ω-Meson Photoproduction off Deuteron

    NASA Astrophysics Data System (ADS)

    Chetry, Taya; Hicks, Kenneth; CLAS Collaboration

    2016-03-01

    Coherent ω photoproduction from the deuteron has been studied using CLAS at Jefferson Lab, Virginia, as a function of the photon energy and the 4-momentum transfer. Tagged photons with beam energies between 0.8 and 3.6 GeV were produced using the bremsstrahlung process incident on a deuterium target, during the run period g10. The final state particles detected are an energetic deuteron and a pair of charged pions. These events were constrained to have neutral pion missing mass, to ensure an exclusive reaction where an ω-meson decays into a π+, a π- and a π0. This study allows to test models of hadronic scattering of ω-mesons from the nucleon, as it is not possible to produce beams of ω-mesons. A preliminary differential cross section of the ω-meson in the coherent process is presented. In addition, this final state is useful to investigate a possible d* dibaryon resonance that has been seen in other reaction channels at CLAS, as well as being seen earlier in partial-wave analysis of pion-deuteron scattering at a mass of about 2145 MeV.

  8. Photoproduction of the Sigma(1385) resonance at LEPS

    NASA Astrophysics Data System (ADS)

    Hicks, Kenneth

    2008-04-01

    The Sigma(1385) hyperon resonance has been measured using the LEPS detector at the SPring-8 facility in Japan. Linearly polarized photons in the range of 1.5-2.4 GeV were incident on a liquid deuterium target, producing a K^+ and a &-circ; in the final state. The negative Sigma(1385) was isolated by its decay to (λ&-circ;) using the missing mass technique. The same final state particles can also used to identify photoproduction of the &-circ; ground state via its decay to (n&-circ;). Using simulations to correct for the detector acceptance, it will be possible to link the cross sections for the Sigma(1385) to the previously measured cross sections for photoproduction of K^+&-circ;. Theoretical calculations for photoproduction of K^+&*-circ; from the neutron are in progress, and will be discussed along with the data analysis of this reaction.

  9. Spore Photoproduct Lyase: The Known, the Controversial, and the Unknown*

    PubMed Central

    Yang, Linlin; Li, Lei

    2015-01-01

    Spore photoproduct lyase (SPL) repairs 5-thyminyl-5,6-dihydrothymine, a thymine dimer that is also called the spore photoproduct (SP), in germinating endospores. SPL is a radical S-adenosylmethionine (SAM) enzyme, utilizing the 5′-deoxyadenosyl radical generated by SAM reductive cleavage reaction to revert SP to two thymine residues. Here we review the current progress in SPL mechanistic studies. Protein radicals are known to be involved in SPL catalysis; however, how these radicals are quenched to close the catalytic cycle is under debate. PMID:25477522

  10. The g-tensor of the flavin cofactor in (6-4) photolyase: a 360 GHz/12.8 T electron paramagnetic resonance study

    NASA Astrophysics Data System (ADS)

    Schnegg, A.; Kay, C. W. M.; Schleicher, E.; Hitomi, K.; Todo, T.; Möbius, K.; Weber, S.

    2006-05-01

    The g-tensor of the neutral radical form of the flavin adenine dinucleotide cofactor FADH• of (6-4) photolyase from Xenopus laevis has been determined by very high-magnetic-field/high-microwave-frequency electron-paramagnetic resonance (EPR) performed at 360 GHz/12.8 T. Due to the high spectral resolution the anisotropy of the g-tensor could be fully resolved in the frozen-solution continuous-wave EPR spectrum. By least square fittings of spectral simulations to experimental data, the principal values of the g-tensor have been established: gX = 2.00433(5), gY = 2.00368(5), gZ = 2.00218(7). A comparison of very high-field EPR data and proton and deuteron electron-nuclear double resonance measurements yielded precise information concerning the orientation of the g-tensor with respect to the molecular frame. This data allowed a comparison to be made between the principal values of the g-tensors of the FADH• cofactors of photolyases involved in the repair of two different DNA lesions: the cyclobutane pyrimidine dimer (CPD) and the (6-4) photoproduct. It was found that gX and gZ are similar in both enzymes, whereas the gY component is slightly larger in (6-4) photolyase. This result clearly shows the sensitivity of the g-tensor to subtle differences in the protein environment experienced by the flavin.

  11. Solar ultraviolet B radiation and photoproduction of vitamin D3 in central and southern areas of Argentina.

    PubMed

    Ladizesky, M; Lu, Z; Oliveri, B; San Roman, N; Diaz, S; Holick, M F; Mautalen, C

    1995-04-01

    The incidence of nutritional rickets in the southern part of Argentina is 8-12 times higher than in the rest of the country. Winter 25(OH)D serum levels in normal population of southern areas are lower than in central and northern areas. To elucidate these differences, we compared the photoconversion of provitamin D3 (7-DHC) to previtamin D3 in two cities: Ushuaia (latitude 55 degrees S) and Buenos Aires (34 degrees S). Ampules containing 7-DHC were exposed to sunlight one day in the middle of each month either from 10:30 a.m. to 2:30 p.m. or from 8:00 a.m. to 5:00 p.m. The percentages of photoproducts formed were determined by high performance liquid chromatography (HPLC). Previous studies have proved that this is a valid model to assess "in vitro" the photoproduction of vitamin D3 in human skin. Previtamin D3 + vitamin D3 formed in Ushuaia were less (p < 0.02) than those found in Buenos Aires during all seasons: summer, (X +/- SEM) 6.4 +/- 0.8% vs. 13.2 +/- 1.8%; autumn, 1.2 +/- 0.7% vs. 6.3 +/- 1.3%; winter, 0.8 +/- 0.7% vs. 3.6 +/- 0.7%; spring, 3.4 +/- 0.5% vs. 9.1 +/- 1.1%. The photoproducts produced from 10:30 a.m. to 2:30 p.m. were similar for each month and latitude to those formed when the ampules were exposed from 8:00 a.m. to 5:00 p.m. We conclude that in Ushuaia there is a prolonged "vitamin D winter" during which cutaneous synthesis of vitamin D is absent, leading to lower serum values of 25(OH)D and contributing to the higher incidence of rickets. PMID:7610924

  12. Note on the photoproduction of the charged A1

    NASA Astrophysics Data System (ADS)

    Condo, G. T.; Handler, T.

    1987-05-01

    Arguments made nearly 15 years ago by Fox and Hey are updated in the light of recent experimental findings. These indicate that the charge-exchange photoproduction of the A1 should dominate that of the A2. Consistency with the experimental data demands an A1 mass of 1335+/-20 MeV and width of 180+/-55 MeV.

  13. Efficiency of hydrogen photoproduction by chloroplast-bacterial hydrogenase systems.

    PubMed

    Krasnovsky, A A; Van Ni, C; Nikandrov, V V; Brin, G P

    1980-11-01

    A comparative study of H(2) photoproduction by chloroplasts and solubilized chlorophyll was performed in the presence of hydrogenase preparations of Clostridium butyricum. The photoproduction of H(2) by chloroplasts in the absence of exogenous electron donors, and with irreversibly oxidized dithiothreitol and cysteine, is thought to be limited by a cyclic transport of electrons wherein methylviologen short-circuits the electron transport in photosystem I. The efficiency of H(2) photoproduction by chloroplasts with ascorbate and NADPH is limited by a back reaction between light-reduced methylviologen and the oxidized electron donors. The use of a combination of electron donors (dithiothreitol and ascorbate), providing anaerobiosis without damage to chloroplasts, makes it possible to avoid consumption of reduced methylviologen for the reduction of oxidized electron donors and to exclude the short-circuiting of electron transfer. Under these conditions, photoproduction of H(2) was observed to occur with a rate of 350 to 400 micromoles H(2) per milligram chlorophyll per hour. In this case, the full electron-transferring capability of photosystem I (measured by irreversible photoreduction of methyl red or O(2)) is used to produce H(2). PMID:16661554

  14. Opportunities in Photoproduction and Spectroscopy at an EIC

    NASA Astrophysics Data System (ADS)

    Stevens, Justin

    2015-04-01

    In recent years, a large number of new states have been observed in the spectrum of heavy quark mesons, both in e+e- collisions and in the decays of B mesons. These states, referred to as XYZ mesons, were not expected in the spectrum of heavy quark-antiquark bound states, and their interpretation remains uncertain. The photoproduction process provides an attractive and complementary production mechanism to study these exotic states and potentially discover new states which are challenging to access through other mechanisms. The proposed Electron-Ion Collider (EIC) is a new high-energy and high-luminosity electron-ion machine with a versatile range of kinematics and beam polarizations, capable of providing new opportunities to study heavy quark meson spectroscopy through photoproduction. In this talk, I will review the recent progress in heavy quark meson spectroscopy and discuss the prospects for hadron spectroscopy at an EIC.

  15. Dijet angular distributions in direct and resolved photoproduction at HERA

    NASA Astrophysics Data System (ADS)

    Derrick, M.; Krakauer, D.; Magill, S.; Mikunas, D.; Musgrave, B.; Okrasinski, J. R.; Repond, J.; Stanek, R.; Talaga, R. L.; Zhang, H.; Mattingly, M. C. K.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Bruni, P.; Cara Romeo, G.; Castellini, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; Gialas, I.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Polini, A.; Sartorelli, G.; Zamora Garcia, Y.; Zichichi, A.; Amelung, C.; Bornheim, A.; Crittenden, J.; Deffner, R.; Doeker, T.; Eckert, M.; Feld, L.; Frey, A.; Geerts, M.; Grothe, M.; Hartmann, H.; Heinloth, K.; Heinz, L.; Hilger, E.; Jakob, H.-P.; Katz, U. F.; Mengel, S.; Paul, E.; Pfeiffer, M.; Rembser, Ch.; Schramm, D.; Stamm, J.; Wedemeyer, R.; Campbell-Robson, S.; Cassidy, A.; Cottingham, W. N.; Dyce, N.; Foster, B.; George, S.; Hayes, M. E.; Heath, G. P.; Heath, H. F.; Piccioni, D.; Roff, D. G.; Tapper, R. J.; Yoshida, R.; Arneodo, M.; Ayad, R.; Capua, M.; Garfagnini, A.; Iannotti, L.; Schioppa, M.; Susinno, G.; Caldwell, A.; Cartiglia, N.; Jing, Z.; Liu, W.; Parsons, J. A.; Ritz, S.; Sciulli, F.; Straub, P. B.; Wai, L.; Yang, S.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Jakubowski, Z.; Przybycień, M. B.; Zachara, M.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Zajaç, J.; Duliński, Z.; Kotański, A.; Abbiendi, G.; Bauerdick, L. A. T.; Behrens, U.; Beier, H.; Bienlein, J. K.; Cases, G.; Deppe, O.; Desler, K.; Drews, G.; Flasiński, M.; Gilkinson, D. J.; Glasman, C.; Göttlicher, P.; Große-Knetter, J.; Haas, T.; Hain, W.; Hasell, D.; Heßling, H.; Iga, Y.; Johnson, K. F.; Joos, P.; Kasemann, M.; Klanner, R.; Koch, W.; Kötz, U.; Kowalski, H.; Labs, J.; Ladage, A.; Löhr, B.; Löwe, M.; Lüke, D.; Mainusch, J.; Mańczak, O.; Milewski, J.; Monteiro, T.; Ng, J. S. T.; Notz, D.; Ohrenberg, K.; Piotrzkowski, K.; Roco, M.; Rohde, M.; Roldán, J.; Schneekloth, U.; Schulz, W.; Selonke, F.; Surrow, B.; Voß, T.; Westphal, D.; Wolf, G.; Wollmer, U.; Youngman, C.; Zeuner, W.; Grabosch, H. J.; Kharchilava, A.; Mari, S. M.; Meyer, A.; Schlenstedt, S.; Wulff, N.; Barbagli, G.; Gallo, E.; Pelfer, P.; Maccarrone, G.; De Pasquale, S.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Trefzger, T.; Wölfle, S.; Bromley, J. T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Saxon, D. H.; Sinclair, L. E.; Utley, M. L.; Wilson, A. S.; Dannemann, A.; Holm, U.; Horstmann, D.; Sinkus, R.; Wick, K.; Burow, B. D.; Hagge, L.; Lohrmann, E.; Poelz, G.; Schott, W.; Zetsche, F.; Bacon, T. C.; Brümmer, N.; Butterworth, I.; Harris, V. L.; Howell, G.; Hung, B. H. Y.; Lamberti, L.; Long, K. R.; Miller, D. B.; Pavel, N.; Prinias, A.; Sedgbeer, J. K.; Sideris, D.; Whitfield, A. F.; Mallik, U.; Wang, M. Z.; Wang, S. M.; Wu, J. T.; Cloth, P.; Filges, D.; An, S. H.; Cho, G. H.; Ko, B. J.; Lee, S. B.; Nam, S. W.; Park, H. S.; Park, S. K.; Kartik, S.; Kim, H.-J.; McNeil, R. R.; Metcalf, W.; Nadendla, V. K.; Barreiro, F.; Fernandez, J. P.; Graciani, R.; Hernández, J. M.; Hervás, L.; Labarga, L.; Martinez, M.; del Peso, J.; Puga, J.; Terron, J.; de Trocóniz, J. F.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Matthews, C. G.; Patel, P. M.; Riveline, M.; Stairs, D. G.; St-Laurent, M.; Ullmann, R.; Zacek, G.; Tsurugai, T.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Gladilin, L. K.; Golubkov, Yu. A.; Kobrin, V. D.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Yu.; Proskuryakov, A. S.; Savin, A. A.; Shcheglova, L. M.; Solomin, A. N.; Zotov, N. P.; Botje, M.; Chlebana, F.; Engelen, J.; de Kamps, M.; Kooijman, P.; Kruse, A.; van Sighem, A.; Tiecke, H.; Verkerke, W.; Vossebeld, J.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; van Woudenberg, R.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Li, C.; Ling, T. Y.; Nylander, P.; Park, I. H.; Romanowski, T. A.; Bailey, D. S.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Harnew, N.; Lancaster, M.; Lindemann, L.; McFall, J. D.; Nath, C.; Noyes, V. A.; Quadt, A.; Tickner, J. R.; Uijterwaal, H.; Walczak, R.; Waters, D. S.; Wilson, F. F.; Yip, T.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; De Giorgi, M.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Zuin, F.; Bulmahn, J.; Feild, R. G.; Oh, B. Y.; Whitmore, J. J.; D'Agostini, G.; Marini, G.; Nigro, A.; Tassi, E.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Barberis, E.; Dubbs, T.; Heusch, C.; Van Hook, M.; Lockman, W.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Williams, D. C.; Biltzinger, J.; Seifert, R. J.; Schwarzer, O.; Walenta, A. H.; Zech, G.; Abramowicz, H.; Briskin, G.; Dagan, S.; Levy, A.; Fleck, J. I.; Inuzuka, M.; ishii, T.; Kuze, M.; Mine, S.; Nakao, M.; Suzuki, I.; Tokushuku, K.; Umemori, K.; Yamada, S.; Yamazaki, Y.; Chiba, M.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Matsushita, T.; Yamauchi, K.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Peroni, C.; Sacchi, R.; Solano, A.; Staino, A.; Dardo, M.; Bailey, D. C.; Benard, F.; Brkic, M.; Fagerstroem, C.-P.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sampson, C. R.; Simmons, D.; Teuscher, R. J.; Butterworth, J. M.; Catterall, C. D.; Jones, T. W.; Kaziewicz, P. B.; Lane, J. B.; Saunders, R. L.; Shulman, J.; Sutton, M. R.; Lu, B.; Mo, L. W.; Bogusz, W.; Ciborowski, J.; Gajewski, J.; Grzelak, G.; Kasprzak, M.; Krzyżanowski, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Coldewey, C.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Revel, D.; Zer-Zion, D.; Badgett, W. F.; Breitweg, J.; Chapin, D.; Cross, R.; Dasu, S.; Foudas, C.; Loveless, R. J.; Mattingly, S.; Reeder, D. D.; Silverstein, S.; Smith, W. H.; Vaiciulis, A.; Wodarczyk, M.; Bhadra, S.; Cardy, M. L.; Frisken, W. R.; Khakzad, M.; Murray, W. N.; Schmidke, W. B.; ZEUS Collaboration

    1996-02-01

    Jet photoproduction, where the two highest transverse energy ( ETjet) jets have ETjet above 6 GeV and a jet-jet invariant mass above 23 GeV, has been studied with the ZEUS detector at the HERA ep collider. Resolved and direct photoproduction samples have been separated. The cross section as a function of the angle between the jet-jet axis and the beam direction in the dijet rest frame has been measured for the two samples. The measured angular distributions differ markedly from each other. They agree with the predictions of QCD calculations, where the different angular distributions reflect the different spins of the quark and gluon exchanged in the hard subprocess.

  16. Photoproduction of Mesons on Quasi-Free Nucleons

    NASA Astrophysics Data System (ADS)

    Keshelashvili, I.

    2014-11-01

    The investigation of excited baryon states is important to understand the underling nature/symmetries of hadronic matter. Historically, the first nucleon excitation experiments have been done using charged pion and kaon secondary beams. Later the antiproton-proton scattering has also been involved. However, since the beginning of the 90's meson photoproduction reactions have been considered as a powerful tool in baryon spectroscopy. In this contribution, we overview our experimental programs conducted at the bremsstrahlung photon beams of the MAMI accelerator in Mainz and the ELSA accelerator in Bonn. The results are differential and total cross sections for photoproduction of light neutral mesons and of meson pairs off quasi-free nucleons bound in the deuteron (and sometimes other light nuclei). The scientific programs of this experiments also include single and double polarization measurements as well.

  17. Near-threshold photoproduction of ϕ mesons from deuterium

    NASA Astrophysics Data System (ADS)

    Clas Collaboration; Qian, X.; Chen, W.; Gao, H.; Hicks, K.; Kramer, K.; Laget, J. M.; Mibe, T.; Qiang, Y.; Stepanyan, S.; Tedeschi, D. J.; Xu, W.; Adhikari, K. P.; Amaryan, M.; Anghinolfi, M.; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Bellis, M.; Biselli, A. S.; Bookwalter, C.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Careccia, S. L.; Carman, D. S.; Cole, P. L.; Collins, P.; Crede, V.; D'Angelo, A.; Daniel, A.; Dashyan, N.; de Vita, R.; de Sanctis, E.; Deur, A.; Dey, B.; Dhamija, S.; Djalali, C.; Doughty, D.; Dupre, R.; Egiyan, H.; El Alaoui, A.; Eugenio, P.; Fegan, S.; Gabrielyan, M. Y.; Gevorgyan, N.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Gothe, R. W.; Graham, L.; Griffioen, K. A.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Hassall, N.; Holtrop, M.; Ilieva, Y.; Ireland, D. G.; Jawalkar, S. S.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Khetarpal, P.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Konczykowski, P.; Kubarovsky, V.; Kuleshov, S. V.; Kuznetsov, V.; Livingston, K.; Martinez, D.; Mayer, M.; McAndrew, J.; McCracken, M. E.; McKinnon, B.; Meyer, C. A.; Mikhailov, K.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Moreno, B.; Moriya, K.; Morrison, B.; Moutarde, H.; Munevar, E.; Nadel-Turonski, P.; Ni, A.; Niccolai, S.; Niculescu, I.; Niroula, M. R.; Osipenko, M.; Ostrovidov, A. I.; Paremuzyan, R.; Park, K.; Park, S.; Pereira, S. Anefalos; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Seraydaryan, H.; Sharabian, Y. G.; Smith, E. S.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Stepanyan, S. S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Taylor, C. E.; Tkachenko, S.; Ungaro, M.; Vernarsky, B.; Vineyard, M. F.; Voutier, E.; Weinstein, L. B.; Weygand, D. P.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, B.; Zhao, Z. W.

    2011-02-01

    We report the first, kinematically-complete measurement of the differential cross section of ϕ-meson photoproduction from deuterium near the production threshold for a proton using the CLAS detector and a tagged-photon beam in Hall B at Jefferson Lab. The measurement was carried out by a triple coincidence detection of a proton, K+ and K- near the theoretical production threshold of 1.57 GeV. The extracted differential cross sections dσdt for the initial photon energy range of 1.65-1.75 GeV are consistent with predictions based on a quasifree mechanism. Our finding is different from recent LEPS results on ϕ-meson photoproduction from deuterium in a similar incident photon energy range, but in a different momentum transfer region.

  18. Nuclear photoproduction of vector mesons within a Monte Carlo approach

    NASA Astrophysics Data System (ADS)

    González, I.; Guzmán, F.; Deppman, A.

    2014-05-01

    We present recent improvements in the crisp code for nuclear reaction simulation. The photoproduction of vector mesons was included in the code, which can evaluate also final state interaction of these mesons with the nucleus. Effects such as shadowing, subthreshold production, and Pauli blocking can be observed. The model is described in detail and some important quantities, such as cross section and nuclear transparency, are calculated as examples of the potential of our code.

  19. Polarization Measurements in Photoproduction with CEBAF Large Acceptance Spectrometer

    SciTech Connect

    E. Pasyuk

    2010-05-01

    A significant part of the experimental program in Hall-B of the Jefferson Lab is dedicated to the studies of the structure of baryons. CEBAF Large Acceptance Spectrometer (CLAS), availability of circularly and linearly polarized photon beams and recent addition of polarized targets provides remarkable opportunity for single, double and in some cases triple polarization measurements in photoproduction. An overview of the experiments will be presented.

  20. Correlations between D and Dbar mesons in high energy photoproduction

    SciTech Connect

    Erik E Gottschalk

    2002-11-13

    Over 7000 events containing a fully reconstructed D{bar D} pair have been extracted from data recorded by the FOCUS photoproduction experiment at Fermilab. Preliminary results from a study of correlations between D and {bar D} mesons are presented. Correlations are used to study perturbative QCD predictions and investigate non-perturbative effects. We also present a preliminary result on the production of {psi}(3770).

  1. Charm and bottom photoproduction at HERA with MC@NLO

    SciTech Connect

    Toll T.; Frixione, S.

    2011-12-01

    We apply the MC@NLO formalism to the production of heavy-quark pairs in pointlike photon-hadron collisions. By combining this result with its analogue relevant to hadron-hadron collisions, we obtain NLO predictions matched to parton showers for the photoproduction of Q{bar Q} pairs. We compare MC{at}NLO results to the measurements of c- and b-flavored hadron observables performed by the H1 and ZEUS Collaborations at HERA.

  2. Phototransformation of amlodipine: degradation kinetics and identification of its photoproducts.

    PubMed

    Jakimska, Anna; Śliwka-Kaszyńska, Magdalena; Nagórski, Piotr; Namieśnik, Jacek; Kot-Wasik, Agata

    2014-01-01

    Nowadays, monitoring focuses on the primary compounds and does not include degradation products formed during various biological and chemical processes. Transformation products may have the same effects to human health and the environment or sometimes they can be more toxic than the parent compound. Unfortunately, knowledge about the formation of degradation products is still limited, however, can be very important for the environmental risk assessment. Firstly, the photodegradation kinetic of amlodipine was investigated in two experimental conditions: during the exposure to solar radiation and during the exposure to the light emitted by the xenon lamp. In all cases degradation of amlodipine followed a pseudo-first-order kinetics. In the next step, identification of transformation products of amlodipine formed during the exposure to xenon lamp irradiation was performed using ultra high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS). As a result sixteen photoproducts were identified, their structures were elucidated and ultimately the transformation pathway was proposed. Fifteen compounds (out of 16 photoproducts) were newly identified and reported here for the first time; some of those compounds were formed from the first photoproduct, amlodipine pyridine derivative. Several analytes were formed only in acidic or basic conditions. Furthermore, the occurrence of amlodipine and its identified degradation products was investigated in environmental waters. Only one out of 16 compounds was found in wastewater effluent. The possibility of the sorption of examined analytes to sewage sludge particles was discussed based on QSAR. PMID:25279815

  3. High-mass dijet cross sections in photoproduction at HERA

    NASA Astrophysics Data System (ADS)

    Chekanov, S.; Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Pellegrino, A.; Repond, J.; Yoshida, R.; Mattingly, M. C. K.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Sartorelli, G.; Zichichi, A.; Aghuzumtsyan, G.; Bartsch, D.; Brock, I.; Crittenden, J.; Goers, S.; Hartmann, H.; Hilger, E.; Irrgang, P.; Jakob, H.-P.; Kappes, A.; Katz, U. F.; Kerger, R.; Kind, O.; Paul, E.; Rautenberg, J.; Renner, R.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K. C.; Weber, A.; Wessoleck, H.; Bailey, D. S.; Brook, N. H.; Cole, J. E.; Foster, B.; Heath, G. P.; Heath, H. F.; Robins, S.; Rodrigues, E.; Scott, J.; Tapper, R. J.; Wing, M.; Capua, M.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Jeoung, H. Y.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Ma, K. J.; Pac, M. Y.; Caldwell, A.; Helbich, M.; Liu, X.; Mellado, B.; Paganis, S.; Schmidke, W. B.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Olkiewicz, K.; Przybycień, M. B.; Stopa, P.; Zawiejski, L.; Bednarek, B.; Grabowska-Bold, I.; Jeleń, K.; Kisielewska, D.; Kowal, A. M.; Kowal, M.; Kowalski, T.; Mindur, B.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Szuba, D.; Szuba, J.; Kotański, A.; Słomiński, W.; Bauerdick, L. A. T.; Behrens, U.; Borras, K.; Chiochia, V.; Dannheim, D.; Desler, K.; Drews, G.; Fourletova, J.; Fox-Murphy, A.; Fricke, U.; Geiser, A.; Goebel, F.; Göttlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G. F.; Hillert, S.; Kötz, U.; Kowalski, H.; Labes, H.; Lelas, D.; Löhr, B.; Mankel, R.; Martens, J.; Martínez, M.; Moritz, M.; Notz, D.; Petrucci, M. C.; Polini, A.; Schneekloth, U.; Selonke, F.; Stonjek, S.; Surrow, B.; Whitmore, J. J.; Wichmann, R.; Wolf, G.; Youngman, C.; Zeuner, W.; Coldewey, C.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Genta, C.; Pelfer, P. G.; Bamberger, A.; Benen, A.; Coppola, N.; Markun, P.; Raach, H.; Wölfle, S.; Bell, M.; Bussey, P. J.; Doyle, A. T.; Glasman, C.; Hanlon, S.; Lee, S. W.; Lupi, A.; McCance, G. J.; Saxon, D. H.; Skillicorn, I. O.; Bodmann, B.; Holm, U.; Salehi, H.; Wick, K.; Ziegler, A.; Ziegler, Ar.; Carli, T.; Gialas, I.; Klimek, K.; Lohrmann, E.; Milite, M.; Collins-Tooth, C.; Foudas, C.; Gonçalo, R.; Long, K. R.; Metlica, F.; Miller, D. B.; Tapper, A. D.; Walker, R.; Cloth, P.; Filges, D.; Kuze, M.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Barakbaev, A. N.; Boos, E. G.; Pokrovskiy, N. S.; Zhautykov, B. O.; Ahn, S. H.; Lee, S. B.; Park, S. K.; Lim, H.; Son, D.; Barreiro, F.; García, G.; González, O.; Labarga, L.; del Peso, J.; Redondo, I.; Terrón, J.; Vázquez, M.; Barbi, M.; Bertolin, A.; Corriveau, F.; Ochs, A.; Padhi, S.; Stairs, D. G.; St-Laurent, M.; Tsurugai, T.; Antonov, A.; Bashkirov, V.; Danilov, P.; Dolgoshein, B. A.; Gladkov, D.; Sosnovtsev, V.; Suchkov, S.; Dementiev, R. K.; Ermolov, P. F.; Golubkov, Yu. A.; Katkov, I. I.; Khein, L. A.; Korotkova, N. A.; Korzhavina, I. A.; Kuzmin, V. A.; Levchenko, B. B.; Lukina, O. Yu.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Vlasov, N. N.; Zotkin, S. A.; Bokel, C.; Engelen, J.; Grijpink, S.; Koffeman, E.; Kooijman, P.; Maddox, E.; Schagen, S.; Tassi, E.; Tiecke, H.; Tuning, N.; Velthuis, J. J.; Wiggers, L.; de Wolf, E.; Brümmer, N.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Boogert, S.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Ferrando, J.; Matsushita, T.; Rigby, M.; Ruske, O.; Sutton, M. R.; Walczak, R.; Brugnera, R.; Carlin, R.; Dal Corso, F.; Dusini, S.; Garfagnini, A.; Limentani, S.; Longhin, A.; Parenti, A.; Posocco, M.; Stanco, L.; Turcato, M.; Adamczyk, L.; Oh, B. Y.; Saull, P. R. B.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cormack, C.; Hart, J. C.; McCubbin, N. A.; Heusch, C.; Park, I. H.; Pavel, N.; Abramowicz, H.; Dagan, S.; Gabareen, A.; Kananov, S.; Kreisel, A.; Levy, A.; Abe, T.; Fusayasu, T.; Kohno, T.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Inuzuka, M.; Kitamura, S.; Matsuzawa, K.; Nishimura, T.; Arneodo, M.; Cartiglia, N.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Galea, R.; Koop, T.; Levman, G. M.; Martin, J. F.; Mirea, A.; Sabetfakhri, A.; Butterworth, J. M.; Gwenlan, C.; Hall-Wilton, R.; Hayes, M. E.; Heaphy, E. A.; Jones, T. W.; Lane, J. B.; Lightwood, M. S.; West, B. J.; Ciborowski, J.; Ciesielski, R.; Grzelak, G.; Nowak, R. J.; Pawlak, J. M.; Smalska, B.; Sztuk, J.; Tymieniecka, T.; Ukleja, A.; Ukleja, J.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Plucinski, P.; Eisenberg, Y.; Gladilin, L. K.; Hochman, D.; Karshon, U.; Breitweg, J.; Chapin, D.; Cross, R.; Kçira, D.; Lammers, S.; Reeder, D. D.; Savin, A. A.; Smith, W. H.; Deshpande, A.; Dhawan, S.; Hughes, V. W.; Straub, P. B.; Bhadra, S.; Catterall, C. D.; Fourletov, S.; Menary, S.; Soares, M.; Standage, J.; ZEUS Collaboration

    2002-04-01

    Dijet differential cross sections for the reaction e+p→e++ jet + jet + X in the photoproduction regime have been measured with the ZEUS detector at HERA using an integrated luminosity of 42.7 pb-1. The cross sections are given for photon-proton centre-of-mass energies in the range 134photoproduction of σe+p→e+Z0X<5.9 pb. Upper limits on the photoproduction of new heavy resonances decaying into two jets are also presented for masses in the range between 60 GeV and 155 GeV.

  4. Phototransformation of Amlodipine: Degradation Kinetics and Identification of Its Photoproducts

    PubMed Central

    Jakimska, Anna; Śliwka-Kaszyńska, Magdalena; Nagórski, Piotr; Namieśnik, Jacek; Kot-Wasik, Agata

    2014-01-01

    Nowadays, monitoring focuses on the primary compounds and does not include degradation products formed during various biological and chemical processes. Transformation products may have the same effects to human health and the environment or sometimes they can be more toxic than the parent compound. Unfortunately, knowledge about the formation of degradation products is still limited, however, can be very important for the environmental risk assessment. Firstly, the photodegradation kinetic of amlodipine was investigated in two experimental conditions: during the exposure to solar radiation and during the exposure to the light emitted by the xenon lamp. In all cases degradation of amlodipine followed a pseudo-first-order kinetics. In the next step, identification of transformation products of amlodipine formed during the exposure to xenon lamp irradiation was performed using ultra high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS). As a result sixteen photoproducts were identified, their structures were elucidated and ultimately the transformation pathway was proposed. Fifteen compounds (out of 16 photoproducts) were newly identified and reported here for the first time; some of those compounds were formed from the first photoproduct, amlodipine pyridine derivative. Several analytes were formed only in acidic or basic conditions. Furthermore, the occurrence of amlodipine and its identified degradation products was investigated in environmental waters. Only one out of 16 compounds was found in wastewater effluent. The possibility of the sorption of examined analytes to sewage sludge particles was discussed based on QSAR. PMID:25279815

  5. Photoproduction at Relativistic Heavy Ion Collider with STAR

    NASA Astrophysics Data System (ADS)

    Madagodahettige Don, Dilan

    2011-11-01

    Relativistic heavy ions carry strong transverse electromagnetic fields which can be treated as sources of quasi-real virtual photons. The ions interact through photon-Pomeron and photon-photon collisions at impact parameter more than twice the nuclear radius, so hadronic interactions are suppressed. We present recent results of the STAR experiment at RHIC on 0̂(770) production in AuAu collisions at various energies. Also we present a new measurement of J/ψ photoproduction in 200 (GeV) AuAu collisions at RHIC. The pT distribution of the J/ψ mesons peaks at very low pT, consistent with expectations for coherent photoproduction. Both the photoproduction cross section and the J/ψ rapidity distribution are expected to show the effects of gluon shadowing. A measurement of the ratio of J/ψ to 0̂ meson cross sections in 200 (GeV) AuAu collisions, as well as a distribution of rapidity within y < 1 for the J/ψ mesons are presented.

  6. Observations of the Scalar Meson f{sub 0} (980) in the photoproduction experiment E687 at Fermilab

    SciTech Connect

    Lebrun, P.; E687 Collaboration

    1997-11-01

    Observation of the scalar meson f{sub 0}(980) is reported in the E687 photoproduction experiment at Fermilab. Evidence is given also for the quasi-exclusive associated {phi}(1020)f{sub 0}(980) photoproduction.

  7. Theoretical estimates of photoproduction cross sections for neutral subthreshold pions in carbon-carbon collisions

    NASA Technical Reports Server (NTRS)

    Norbury, J. W.; Townsend, L. W.

    1986-01-01

    Using the Weizsacher-Williams method of virtual quanta, total cross section estimates for the photoproduction of neutral subthreshold pins in carbon-carbon collisions at incident energies below 300 MeV/nucleon are made. Comparisons with recent experimental data indicate that the photoproduction mechanism makes an insignificant contribution to these measured cross sections.

  8. Recent results on eta and eta-prime photoproduction on the proton

    SciTech Connect

    Barry Ritchie

    2004-06-01

    The experimental situation on eta and eta' photoproduction on the proton is reviewed, emphasizing progress made since 2001. New preliminary results for eta' photoproduction on the proton from Jefferson Lab are presented. Experimental results are compared with several theoretical approaches, with an emphasis on consequences for understanding baryon spectroscopy.

  9. 41 CFR 302-6.4 - Am I eligible for a TQSE allowance?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 41 Public Contracts and Property Management 4 2014-07-01 2014-07-01 false Am I eligible for a TQSE allowance? 302-6.4 Section 302-6.4 Public Contracts and Property Management Federal Travel Regulation System... EXPENSES 6-ALLOWANCE FOR TEMPORARY QUARTERS SUBSISTENCE EXPENSES General Rules § 302-6.4 Am I eligible...

  10. 41 CFR 302-6.4 - Am I eligible for a TQSE allowance?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 41 Public Contracts and Property Management 4 2011-07-01 2011-07-01 false Am I eligible for a TQSE allowance? 302-6.4 Section 302-6.4 Public Contracts and Property Management Federal Travel Regulation System... EXPENSES 6-ALLOWANCE FOR TEMPORARY QUARTERS SUBSISTENCE EXPENSES General Rules § 302-6.4 Am I eligible...

  11. 41 CFR 302-6.4 - Am I eligible for a TQSE allowance?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 4 2010-07-01 2010-07-01 false Am I eligible for a TQSE allowance? 302-6.4 Section 302-6.4 Public Contracts and Property Management Federal Travel Regulation System... EXPENSES 6-ALLOWANCE FOR TEMPORARY QUARTERS SUBSISTENCE EXPENSES General Rules § 302-6.4 Am I eligible...

  12. 41 CFR 302-6.4 - Am I eligible for a TQSE allowance?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 41 Public Contracts and Property Management 4 2012-07-01 2012-07-01 false Am I eligible for a TQSE allowance? 302-6.4 Section 302-6.4 Public Contracts and Property Management Federal Travel Regulation System... EXPENSES 6-ALLOWANCE FOR TEMPORARY QUARTERS SUBSISTENCE EXPENSES General Rules § 302-6.4 Am I eligible...

  13. 41 CFR 302-6.4 - Am I eligible for a TQSE allowance?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 41 Public Contracts and Property Management 4 2013-07-01 2012-07-01 true Am I eligible for a TQSE allowance? 302-6.4 Section 302-6.4 Public Contracts and Property Management Federal Travel Regulation System... EXPENSES 6-ALLOWANCE FOR TEMPORARY QUARTERS SUBSISTENCE EXPENSES General Rules § 302-6.4 Am I eligible...

  14. Photoproduction of a2(1320 ) in a Regge model

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Yun; Guskov, Alexey

    2016-04-01

    In this work, the photoproduction of a2(1320 ) off a proton target is investigated within an effective Lagrangian approach and the Regge model. The theoretical result indicates that the shapes of the total and differential cross sections of the γ p →a2+n reaction within the Feynman (isobar) model are much different from that of the Reggeized treatment. The obtained cross section is compared with the existing experimental results at low energies. The a2(1320 ) production cross section at high energies can be tested by the COMPASS experiment, which can provide important information for clarifying the role of the Reggeized treatment at that energy range.

  15. Measurement of three-jet distributions in photoproduction at HERA

    NASA Astrophysics Data System (ADS)

    ZEUS Collaboration; Breitweg, J.; Chekanov, S.; Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Repond, J.; Stanek, R.; Yoshida, R.; Mattingly, M. C. K.; Abbiendi, G.; Anselmo, F.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Castellini, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Coppola, N.; Corradi, M.; de Pasquale, S.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Polini, A.; Sartorelli, G.; Zamora Garcia, Y.; Zichichi, A.; Amelung, C.; Bornheim, A.; Brock, I.; Coböken, K.; Crittenden, J.; Deffner, R.; Eckert, M.; Grothe, M.; Hartmann, H.; Heinloth, K.; Heinz, L.; Hilger, E.; Jakob, H.-P.; Kappes, A.; Katz, U. F.; Kerger, R.; Paul, E.; Pfeiffer, M.; Schnurbusch, H.; Weber, A.; Wieber, H.; Bailey, D. S.; Barret, O.; Cottingham, W. N.; Foster, B.; Hall-Wilton, R.; Heath, G. P.; Heath, H. F.; McFall, J. D.; Piccioni, D.; Scott, J.; Tapper, R. J.; Capua, M.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Jeoung, H. Y.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Ma, K. J.; Pac, M. Y.; Caldwell, A.; Cartiglia, N.; Jing, Z.; Liu, W.; Mellado, B.; Parsons, J. A.; Ritz, S.; Sacchi, R.; Sampson, S.; Sciulli, F.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Klimek, K.; Przybycień , M. B.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Jeleń , K.; Kisielewska, D.; Kowal, A. M.; Kowalski, T.; Przybycień , M.; Rulikowska-Zarȩ Bska, E.; Suszycki, L.; Zaja C, J.; Duliń Ski, Z.; Kotań Ski, A.; Bauerdick, L. A. T.; Behrens, U.; Beier, H.; Bienlein, J. K.; Burgard, C.; Desler, K.; Drews, G.; Fricke, U.; Goebel, F.; Göttlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G. F.; Hasell, D.; Hebbel, K.; Johnson, K. F.; Kasemann, M.; Koch, W.; Kötz, U.; Kowalski, H.; Lindemann, L.; Löhr, B.; Martínez, M.; Milewski, J.; Milite, M.; Monteiro, T.; Notz, D.; Pellegrino, A.; Pelucchi, F.; Piotrzkowski, K.; Rohde, M.; Roldán, J.; Ryan, J. J.; Saull, P. R. B.; Savin, A. A.; Schneekloth, U.; Schwarzer, O.; Selonke, F.; Sievers, M.; Stonjek, S.; Surrow, B.; Tassi, E.; Westphal, D.; Wolf, G.; Wollmer, U.; Youngman, C.; Zeuner, W.; Burow, B. D.; Coldewey, C.; Grabosch, H. J.; Lopez-Duran Viani, A.; Meyer, A.; Mönig, K.; Schlenstedt, S.; Straub, P. B.; Barbagli, G.; Gallo, E.; Pelfer, P.; Maccarrone, G.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Markun, P.; Raach, H.; Wölfle, S.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Lee, S. W.; MacDonald, N.; McCance, G. J.; Saxon, D. H.; Sinclair, L. E.; Skillicorn, I. O.; Strickland, E.; Waugh, R.; Bohnet, I.; Gendner, N.; Holm, U.; Meyer-Larsen, A.; Salehi, H.; Wick, K.; Garfagnini, A.; Gialas, I.; Gladilin, L. K.; Kçira, D.; Klanner, R.; Lohrmann, E.; Poelz, G.; Zetsche, F.; Bacon, T. C.; Cole, J. E.; Howell, G.; Lamberti, L.; Long, K. R.; Miller, D. B.; Prinias, A.; Sedgbeer, J. K.; Sideris, D.; Tapper, A. D.; Walker, R.; Mallik, U.; Wang, S. M.; Cloth, P.; Filges, D.; Ishii, T.; Kuze, M.; Suzuki, I.; Tokushuku, K.; Yamada, S.; Yamauchi, K.; Yamazaki, Y.; Ahn, S. H.; An, S. H.; Hong, S. J.; Lee, S. B.; Nam, S. W.; Park, S. K.; Lim, H.; Park, I. H.; Son, D.; Barreiro, F.; Fernández, J. P.; García, G.; Glasman, C.; Hernández, J. M.; Labarga, L.; del Peso, J.; Puga, J.; Redondo, I.; Terrón, J.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Murray, W. N.; Ochs, A.; Padhi, S.; Pinciuc, C.; Riveline, M.; Stairs, D. G.; St-Laurent, M.; Tsurugai, T.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Golubkov, Yu. A.; Khein, L. A.; Korotkova, N. A.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Yu.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Zotkin, S. A.; Bokel, C.; Botje, M.; Brümmer, N.; Engelen, J.; Koffeman, E.; Kooijman, P.; van Sighem, A.; Tiecke, H.; Tuning, N.; Verkerke, W.; Vossebeld, J.; Wiggers, L.; de Wolf, E.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Nylander, P.; Blaikley, H. E.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Edmonds, J. K.; Große-Knetter, J.; Harnew, N.; Matsushita, T.; Noyes, V. A.; Quadt, A.; Ruske, O.; Sutton, M. R.; Walczak, R.; Waters, D. S.; Bertolin, A.; Brugnera, R.; Carlin, R.; dal Corso, F.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Iannotti, L.; Oh, B. Y.; Okrasiń Ski, J. R.; Toothacker, W. S.; Whitmore, J. J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Raso, M.; Cormack, C.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Epperson, D.; Heusch, C.; Sadrozinski, H. F.-W.; Seiden, A.; Wichmann, R.; Williams, D. C.; Pavel, N.; Abramowicz, H.; Briskin, G.; Dagan, S.; Kananov, S.; Levy, A.; Abe, T.; Fusayasu, T.; Inuzuka, M.; Nagano, K.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Nishimura, T.; Arneodo, M.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Petrucci, M. C.; Ruspa, M.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Fagerstroem, C.-P.; Galea, R.; Koop, T.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sabetfakhri, A.; Simmons, D.; Butterworth, J. M.; Catterall, C. D.; Hayes, M. E.; Heaphy, E. A.; Jones, T. W.; Lane, J. B.; Wing, M.; Ciborowski, J.; Grzelak, G.; Nowak, R. J.; Pawlak, J. M.; Pawlak, R.; Smalska, B.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Zsolararnecki, A. F.; Adamus, M.; Gadaj, T.; Deppe, O.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Badgett, W. F.; Chapin, D.; Cross, R.; Foudas, C.; Mattingly, S.; Reeder, D. D.; Smith, W. H.; Vaiciulis, A.; Wildschek, T.; Wodarczyk, M.; Deshpande, A.; Dhawan, S.; Hughes, V. W.; Bhadra, S.; Frisken, W. R.; Khakzad, M.; Menary, S.; Schmidke, W. B.

    1998-12-01

    The cross section for the photoproduction of events containing three jets with a three-jet invariant mass of M3J>50 GeV has been measured with the ZEUS detector at HERA. The three-jet angular distributions are inconsistent with a uniform population of the available phase space but are well described by parton shower models and ≀(ααs2) pQCD calculations. Comparisons with the parton shower model indicate a strong contribution from initial state radiation as well as a sensitivity to the effects of colour coherence.

  16. Primakoff effect in η-photoproduction off protons

    DOE PAGESBeta

    A. Sibirtsev; Haidenbauer, J.; Krewald, S.; MeiBner, U. -G.

    2010-03-26

    In this paper, we analyse data on forward η -meson photoproduction off a proton target and extract the η → γγ decay width utilizing the Primakoff effect. The hadronic amplitude that enters into our analysis is strongly constrained because it is fixed from a global fit to available γp → pη data for differential cross-sections and polarizations. Finally, we compare our results with present information on the two-photon η-decay from the literature. We provide predictions for future PrimEx experiments at Jefferson Laboratory in order to motivate further studies.

  17. Beauty photoproduction using decays into electrons at HERA

    SciTech Connect

    Chekanov, S.; Derrick, M.; Magill, S.; Musgrave, B.; Nicholass, D.; Repond, J.; Yoshida, R.; Mattingly, M. C. K.; Antonioli, P.; Bari, G.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cindolo, F.; Corradi, M.; Iacobucci, G.; Margotti, A.; Nania, R.; Polini, A.

    2008-10-01

    Photoproduction of beauty quarks in events with two jets and an electron associated with one of the jets has been studied with the ZEUS detector at HERA using an integrated luminosity of 120 pb{sup -1}. The fractions of events containing b quarks, and also of events containing c quarks, were extracted from a likelihood fit using variables sensitive to electron identification as well as to semileptonic decays. Total and differential cross sections for beauty and charm production were measured and compared with next-to-leading-order QCD calculations and Monte Carlo models.

  18. Photoproduction and Decay of Light Mesons in CLAS

    SciTech Connect

    Amaryan, Moskov Jamalovich

    2013-08-01

    We present preliminary experimental results on photoproduction and decay of light mesons measured with CLAS setup at JLAB . This include Dalitz decay of pseudoscalar and vector mesons, radiative decay of pseudoscalar mesons as well hadronic decays of pseudoscalar and vector mesons. The collected high statistics in some of decay channels exceeds the world data by an order of magnitude and some other decay modes are observed for the first time. It is shown how the CLAS data will improve the world data on transition form factors of light mesons, Dalitz plot analyses, branching ratios of rare decay modes and other fundamental properties potentially accessible through the light meson decays.

  19. Eta(547) and Eta(958) Meson Photoproduction on the Proton

    SciTech Connect

    Michael Dugger

    2001-12-01

    Photoproduction of {eta} and {eta}{prime} mesons has been studied at the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) using a tagged photon beam incident on a hydrogen target with photon energies from the respective production thresholds up to 2.4 GeV. The photoproduced mesons were identified via missing mass reconstruction using recoil proton momentum and time of flight information. Data were obtained in a range of {radical}s from threshold to 2.2 GeV for each meson. In this study, differential cross-section measurements for the {gamma}p {yields} p{eta} and {gamma}p {yields} p{eta}{prime} reactions are presented, and the results compared to recent data. An isobar analysis of the differential cross-sections is performed. The predicted differential cross-sections from the isobar analysis are used to predict behavior in unmeasured regions of phase space, and to infer total cross sections. For the {gamma}p {yields} p{eta} reaction, a value of the S{sub 11}(1535) proton helicity amplitude also was extracted and compared to recent analyses. The data presented greatly extends the energy and angle coverage for differential cross-sections of {eta} photoproduction, and significantly improves the accuracy with which {eta}{prime} cross sections are known.

  20. Diffractive photoproduction of ψ(2 S) mesons at HERA

    NASA Astrophysics Data System (ADS)

    Adloff, C.; Andreev, V.; Andrieu, B.; Anthonis, T.; Astvatsatourov, A.; Babaev, A.; Bähr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Baumgartner, S.; Becker, J.; Beckingham, M.; Beglarian, A.; Behnke, O.; Beier, C.; Belousov, A.; Berger, Ch.; Berndt, T.; Bizot, J. C.; Böhme, J.; Boudry, V.; Braunschweig, W.; Brisson, V.; Bröker, H.-B.; Brown, D. P.; Brückner, W.; Bruncko, D.; Büsser, F. W.; Bunyatyan, A.; Burrage, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A. J.; Caron, S.; Cassol-Brunner, F.; Clarke, D.; Collard, C.; Contreras, J. G.; Coppens, Y. R.; Coughlan, J. A.; Cousinou, M.-C.; Cox, B. E.; Cozzika, G.; Cvach, J.; Dainton, J. B.; Dau, W. D.; Daum, K.; Davidsson, M.; Delcourt, B.; Delerue, N.; Demirchyan, R.; De Roeck, A.; De Wolf, E. A.; Diaconu, C.; Dingfelder, J.; Dixon, P.; Dodonov, V.; Dowell, J. D.; Droutskoi, A.; Dubak, A.; Duprel, C.; Eckerlin, G.; Eckstein, D.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P. J. W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Ferron, S.; Fleischer, M.; Fleischmann, P.; Fleming, Y. H.; Flügge, G.; Fomenko, A.; Foresti, I.; Formánek, J.; Franke, G.; Frising, G.; Gabathuler, E.; Gabathuler, K.; Garvey, J.; Gassner, J.; Gayler, J.; Gerhards, R.; Gerlich, C.; Ghazaryan, S.; Goerlich, L.; Gogitidze, N.; Grab, C.; Grabski, V.; Grässler, H.; Greenshaw, T.; Grindhammer, G.; Hadig, T.; Haidt, D.; Hajduk, L.; Haller, J.; Haynes, W. J.; Heinemann, B.; Heinzelmann, G.; Henderson, R. C. W.; Hengstmann, S.; Henschel, H.; Heremans, R.; Herrera, G.; Herynek, I.; Hildebrandt, M.; Hilgers, M.; Hiller, K. H.; Hladký, J.; Höting, P.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Hurling, S.; Ibbotson, M.; İşsever, Ç.; Jacquet, M.; Jaffre, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jönsson, L.; Johnson, C.; Johnson, D. P.; Jones, M. A. S.; Jung, H.; Kant, D.; Kapichine, M.; Karlsson, M.; Karschnick, O.; Keil, F.; Keller, N.; Kennedy, J.; Kenyon, I. R.; Kermiche, S.; Kiesling, C.; Kjellberg, P.; Klein, M.; Kleinwort, C.; Kluge, T.; Knies, G.; Koblitz, B.; Kolya, S. D.; Korbel, V.; Kostka, P.; Kotelnikov, S. K.; Koutouev, R.; Koutov, A.; Kroseberg, J.; Krüger, K.; Kuhr, T.; Kurča, T.; Lamb, D.; Landon, M. P. J.; Lange, W.; Laštovička, T.; Laycock, P.; Lebailly, E.; Lebedev, A.; Leißner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; Lindstroem, M.; List, B.; Lobodzinska, E.; Lobodzinski, B.; Loginov, A.; Loktionova, N.; Lubimov, V.; Lüders, S.; Lüke, D.; Lytkin, L.; Malden, N.; Malinovski, E.; Malinovski, I.; Mangano, S.; Maraček, R.; Marage, P.; Marks, J.; Marshall, R.; Martyn, H.-U.; Martyniak, J.; Maxfield, S. J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A. B.; Meyer, H.; Meyer, J.; Meyer, P.-O.; Mikocki, S.; Milstead, D.; Mohrdieck, S.; Mondragon, M. N.; Moreau, F.; Morozov, A.; Morris, J. V.; Müller, K.; Murín, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, Th.; Nellen, G.; Newman, P. R.; Niebergall, F.; Niebuhr, C.; Nix, O.; Nowak, G.; Olsson, J. E.; Ozerov, D.; Panassik, V.; Pascaud, C.; Patel, G. D.; Peez, M.; Perez, E.; Petrukhin, A.; Phillips, J. P.; Pitzl, D.; Pöschl, R.; Potachnikova, I.; Povh, B.; Rädel, G.; Rauschenberger, J.; Reimer, P.; Reisert, B.; Risler, C.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rusakov, S.; Rybicki, K.; Sankey, D. P. C.; Schätzel, S.; Scheins, J.; Schilling, F.-P.; Schleper, P.; Schmidt, D.; Schmidt, D.; Schmidt, S.; Schmitt, S.; Schneider, M.; Schoeffel, L.; Schöning, A.; Schörner, T.; Schröder, V.; Schultz-Coulon, H.-C.; Schwanenberger, C.; Sedlák, K.; Sefkow, F.; Shekelyan, V.; Sheviakov, I.; Shtarkov, L. N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, A.; Spitzer, H.; Stamen, R.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Swart, M.; Tchetchelnitski, S.; Thompson, G.; Thompson, P. D.; Tomasz, F.; Traynor, D.; Truöl, P.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Turney, J. E.; Tzamariudaki, E.; Udluft, S.; Uraev, A.; Urban, M.; Usik, A.; Valkár, S.; Valkárová, A.; Vallée, C.; Van Mechelen, P.; Vassiliev, S.; Vazdik, Y.; Vest, A.; Vichnevski, A.; Wacker, K.; Wagner, J.; Wallny, R.; Waugh, B.; Weber, G.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; White, G.; Wiesand, S.; Wilksen, T.; Winde, M.; Winter, G.-G.; Wissing, Ch.; Wobisch, M.; Woehrling, E.-E.; Wünsch, E.; Wyatt, A. C.; Žáček, J.; Zálešák, J.; Zhang, Z.; Zhokin, A.; Zomer, F.; zur Nedden, M.; H1 Collaboration

    2002-08-01

    Results on diffractive photoproduction of ψ(2 S) mesons are presented using data collected between 1996 and 2000 with the H1 detector at the HERA ep collider. The data correspond to an integrated luminosity of 77 pb -1. The energy dependence of the diffractive ψ(2 S) cross section is found to be similar to or possibly somewhat steeper than that for J/ ψ mesons. The dependences of the elastic and proton dissociative ψ(2 S) photoproduction cross sections on the squared momentum transfer t at the proton vertex are measured. The t-dependence of the elastic channel, parametrised as ebt, yields belψ(2 S) =(4.31±0.57±0.46) GeV -2, compatible with that of the J/ ψ. For the proton dissociative channel the result bpdψ(2 S) =(0.59±0.13±0.12) GeV -2 is 2.3 standard deviations smaller than that measured for the J/ ψ. With proper account of the individual wavefunctions theoretical predictions based on perturbative QCD are found to describe the measurements well.

  1. Experimental study of η meson photoproduction reaction at MAMI

    NASA Astrophysics Data System (ADS)

    Kashevarov, V. L.

    2015-06-01

    New data for the differential cross sections, polarization observables T, F, and E in the reaction of η photoproduction on proton from the threshold up to a center-of-mass energy of W=1.9 GeV are presented. The data were obtained with the Crystal-Ball/TAPS detector setup at the Glasgow tagged photon facility of the Mainz Microtron MAMI. The polarization measurements were made using a frozen-spin butanol target and circularly polarized photon beam. The results are compared to existing experimental data and different PWA predictions. The data solve a long-standing problem related the angular dependence of older T data close to threshold. The unexpected relative phase motion between s- and d-wave amplitudes required by the old data is not confirmed. At higher energies, all model predictions fail to reproduce the new polarization data indicating a significant impact on our understanding of the underlying dynamics of η meson photoproduction. Furthermore, we present a fit of the new data and existing data from GRAAL for ∑ asymmetry based on an expansion in terms of associated Legendre polynomials. A Legendre decomposition shows the sensitivity to small partialwave contributions. The sensitivity of the Legendre coefficients to the nucleon resonance parameters is shown using the ηMAID isobar model.

  2. π 0 and η Photoproduction on the Deuteron at ELPH, Tohoku University

    NASA Astrophysics Data System (ADS)

    Ishikawa, T.; Fujimura, H.; Fukasawa, H.; Hashimoto, R.; He, Q.; Honda, Y.; Iwata, T.; Kaida, S.; Kasagi, J.; Kawano, A.; Kuwasaki, S.; Maeda, K.; Masumoto, S.; Miyabe, M.; Miyahara, F.; Mochizuki, K.; Muramatsu, N.; Nakamura, A.; Nawa, K.; Ogushi, S.; Okada, Y.; Onodera, Y.; Ozawa, K.; Sakamoto, Y.; Sato, M.; Shimizu, H.; Sugai, H.; Suzuki, K.; Tajima, Y.; Takahashi, S.; Taniguchi, Y.; Tsuchikawa, Y.; Yamazaki, H.; Yamazaki, R.; Yoshida, H. Y.

    2013-08-01

    Baryon spectroscopy is important to understand Quantum Chromodynamics at low energies. In this purpose, a series of π 0 and η photoproduction experiments was carried out with an electro-magnetic calorimeter FOREST at Research Center for Electron Photon Science, Tohoku University. The incident tagged bremsstrahlung photon energy ranges from 550 to 1,150 MeV. The differential and total cross sections obtained for π 0 and η photoproduction processes on the proton are consistent with the SAID and MAID calculations. The analysis of π 0 and η photoproduction on the neutron is underway.

  3. Coherent {pi}{sup 0}-photoproduction on the deuteron including polarization observables

    SciTech Connect

    Darwish, E. M.; Akopov, N.; El-Zohry, M.

    2011-10-27

    Coherent {pi}{sup 0}-photoproduction on the deuteron including polarization effects in the energy region from {pi}-threshold up to 1 GeV is studied using an enhanced elementary pion photo-production operator on the free nucleon and a realistic NN potential model for the deuteron wave function. Results for double polarization observables are predicted for which the sensitivity to various models for the elementary pion photoproduction amplitude is investigated. We find considerable dependence of the results on the elementary amplitude. In addition, results for differential cross section are predicted and compared with the experimental data from TAPS and a satisfactory agreement was found.

  4. Characterization of the Saccharomyces cerevisiae sec6-4 mutation and tools to create S. cerevisiae strains containing the sec6-4 allele.

    PubMed

    Lamping, Erwin; Tanabe, Koichi; Niimi, Masakazu; Uehara, Yoshimasa; Monk, Brian C; Cannon, Richard D

    2005-11-21

    The highly conserved exocyst complex of eukaryotic cells allows the polarized transport and fusion of late secretory vesicles with the plasma membrane. In Saccharomyces cerevisiae the Sec6p component of the exocyst complex is essential for cell growth. The sec6-4 temperature-sensitive mutation of the S. cerevisiae SEC6 gene leads to the accumulation of large amounts of mature late post-Golgi secretory vesicles in the cytosol of mutant cells at the restrictive temperature of 37 degrees C. These readily isolated, inside-out and tightly sealed vesicles contain mature post-translationally modified plasma membrane and secretory proteins and provide a valuable tool for the study of plasma membrane protein function. This study shows that the single point mutation L633P in the SEC6 coding region defines the sec6-4 phenotype. We followed the localization of the wild type Sec6p and the mutant Sec6-4p proteins (C-terminally tagged with the green fluorescent protein yEGfp3p) in the presence or absence of heterologously over-expressed Candida albicans plasma membrane ATP-binding cassette (ABC) transporter CaCdr1p (C-terminally tagged with the red fluorescent protein mRfp1p). The Sec6-4p protein localized to buds and septa, like wild type Sec6p, at the permissive temperature of 23 degrees C and the sec6-4 mutant cells grew at the same rate as the wild type control cells. Sec6-4p was mislocalized at the restrictive temperature of 37 degrees C and heterogenous vesicles accumulated in cells but sec6-4 cells also accumulated homogenous secretory vesicles at the permissive temperature. PMID:16185821

  5. 36 CFR 6.4 - Solid waste disposal sites not in operation on September 1, 1984.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Solid waste disposal sites not in operation on September 1, 1984. 6.4 Section 6.4 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SOLID WASTE DISPOSAL SITES IN UNITS OF THE NATIONAL PARK SYSTEM § 6.4 Solid waste disposal sites not...

  6. Spectroscopic characterization of titanium 6-4 surfaces after chemical pretreatments

    NASA Technical Reports Server (NTRS)

    Chen, W.; Siriwardane, R.; Wightman, J. P.

    1980-01-01

    Several techniques have been used to study pretreated Ti 6-4 surfaces including scanning electron microscopy (SEM), electron spectroscopy of chemical analysis (ESCA), and, reflectance visibile spectroscopy. Each pretreatment type gives a characteristic surface morphology as seen by SEM. Elemental analysis of the Ti 6-4 surfaces was done using ESCA. Trace residual contaminants from particular chemical pretreatments are identified readily. Reflectance visible spectroscopy using indicator dyes placed on Ti 6-4 surfaces appears to be a feasible approach to establish surface acidity. Differences in surface acidity have been observed using bromthymol blue on Ti 6-4 surfaces pretreated by two different methods.

  7. Photoproduction of ω mesons off nuclei and impact of polarization on the meson-nucleon interaction

    NASA Astrophysics Data System (ADS)

    Chudakov, E.; Gevorkyan, S.; Somov, A.

    2016-01-01

    We use photoproduction of ω mesons off complex nuclei to study interactions of transversely and longitudinally polarized vector mesons with nucleons. Whereas the total cross section for interactions of the transversely polarized vector mesons with nucleons σT=σ (VTN ) can be obtained from coherent photoproduction, measurements of vector meson photoproduction in the incoherent region provide a unique opportunity to extract the yet unmeasured total cross section for longitudinally polarized mesons σL=σ (VLN ) . The predictions for the latter strongly depend on the theoretical approaches. This work is stimulated by the construction of the new experiment GlueX at Jefferson Lab, designed to study the photoproduction of mesons in the beam energy range between 5 and 12 GeV.

  8. Pole positions and residues from pion photoproduction using the Laurent-Pietarinen expansion method

    NASA Astrophysics Data System (ADS)

    Švarc, Alfred; Hadžimehmedović, Mirza; Osmanović, Hedim; Stahov, Jugoslav; Tiator, Lothar; Workman, Ron L.

    2014-06-01

    We applied a new approach to determine the pole positions and residues from pion photoproduction multipoles. The method is based on a Laurent expansion of the partial-wave T matrices, with a Pietarinen series representing the regular part of energy-dependent and single-energy photoproduction solutions. The method is applied to multipole fits generated by the MAID and George Washington University SAID (GWU-SAID) groups. We show that the number and properties of poles extracted from photoproduction data correspond very well to results from πN elastic data and values cited by the Particle Data Group (PDG). The photoproduction residues provide new information for the electromagnetic current at the pole position, which are independent of background parametrizations, which is not the case for the Breit-Wigner representation. Finally, we present the photodecay amplitudes from the current MAID and SAID solutions at the pole for all four-star nucleon resonances below W =2 GeV.

  9. Photoproduction of ω mesons off nuclei and impact of polarization on the meson-nucleon interaction

    DOE PAGESBeta

    Chudakov, Eugene A.; Gevorkyan, Sergey; Somov, Alexander

    2016-01-25

    We consider photoproduction of ω mesons off complex nuclei to study interactions of transversely and longitudinally polarized vector mesons with nucleons. Whereas the total cross section for interactions of the transversely polarized vector mesons with nucleons σT = σ(VTN) can be obtained from coherent photoproduction, measurements of vector meson photoproduction in the incoherent region provide a unique opportunity to extract the not-yet-measured total cross section for longitudinally polarized mesons σL = σ(VLN). The predictions for the latter strongly depend on the theoretical approaches. Furthermore, this work is stimulated by the construction of the new experiment GlueX at Jefferson Lab, designedmore » to study the photoproduction of mesons in a large beam energy range up to 12 GeV.« less

  10. Genetics of human sensitivity to ultraviolet radiation

    NASA Astrophysics Data System (ADS)

    Cleaver, James E.

    1994-07-01

    the major human health effects of solar and artificial UV light occur from the UVB and UVC wavelength ranges and involve a variety of short-term and long-term deleterious changes to the skin and eyes. the more important initial damage to cellular macromolecules involves dimerization of adjacent pyrimidines in DNA to produce cyclobutane pyrimidine dimes, (6-4) pyrimidine- pyrimidone, and (6-4) dewar photoproducts. these photoproducts can be repaired by a genetically regulated enzyme system (nucleotide excision repair) which removes oligonucleotides 29-30 nucleotides long that contain the photoproducts, and synthesizes replacement patches. At least a dozen gene products are involved in the process of recognizing photoproducts in DNA, altering local DNA helicity and cleaving the polynucleotide chain at defined positions either side of a photoproduct. Hereditary mutations in many of these genes are recognized in the human genetic disorders xeroderma pigmentosum (XP), Cockayne syndrome (CS), and trichothiodystrophy (TTD). Several of the gene products have other functions involving the regulation of gene transcription which accounts for the complex clinical presentation of repair deficient diseases that involve sensitivity of the skin and eyes to UV light, increased solar carcinogenesis (in XP), demyelination, and ganglial calcification (in CS), hair abnormalities (in TTD), and developmental and neurological abnormalities

  11. 38 CFR 6.4 - Proof of age, relationship and marriage.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., relationship and marriage. 6.4 Section 6.4 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS....4 Proof of age, relationship and marriage. Whenever it is necessary for a claimant to prove age, relationship or marriage, the provisions of 38 U.S.C. 103(c) and Part 3 this chapter will be followed....

  12. 38 CFR 6.4 - Proof of age, relationship and marriage.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., relationship and marriage. 6.4 Section 6.4 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS....4 Proof of age, relationship and marriage. Whenever it is necessary for a claimant to prove age, relationship or marriage, the provisions of 38 U.S.C. 103(c) and Part 3 this chapter will be followed....

  13. 38 CFR 6.4 - Proof of age, relationship and marriage.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., relationship and marriage. 6.4 Section 6.4 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS....4 Proof of age, relationship and marriage. Whenever it is necessary for a claimant to prove age, relationship or marriage, the provisions of 38 U.S.C. 103(c) and Part 3 this chapter will be followed....

  14. 38 CFR 6.4 - Proof of age, relationship and marriage.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., relationship and marriage. 6.4 Section 6.4 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS....4 Proof of age, relationship and marriage. Whenever it is necessary for a claimant to prove age, relationship or marriage, the provisions of 38 U.S.C. 103(c) and Part 3 this chapter will be followed....

  15. 38 CFR 6.4 - Proof of age, relationship and marriage.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., relationship and marriage. 6.4 Section 6.4 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS....4 Proof of age, relationship and marriage. Whenever it is necessary for a claimant to prove age, relationship or marriage, the provisions of 38 U.S.C. 103(c) and Part 3 this chapter will be followed....

  16. Nonresonant Background in Isobaric Models of Photoproduction of η-Mesons on Nucleons

    NASA Astrophysics Data System (ADS)

    Tryasuchev, V. A.; Alekseev, B. A.; Yakovleva, V. S.; Kondratyeva, A. G.

    2016-07-01

    Within the framework of isobaric models of pseudoscalar meson photoproduction, the nonresonant background of photoproduction of η-mesons on nucleons is investigated as a function of energy. A bound on the magnitude of the pseudoscalar coupling constant of the η-meson with a nucleon is obtained: g {ηNN/ 2}/4π ≤ 0.01, and a bound on vector meson exchange models is also obtained.

  17. Exclusive photoproduction of quarkonium at the LHC energies within the color dipole approach

    SciTech Connect

    Ducati, M. B. Gay; Griep, M. T.; Machado, M. V. T.

    2015-04-10

    The exclusive photoproduction of ψ(2S) meson was investigated and the coherent and the incoherent contributions were evaluated. The light-cone dipole formalism was considered in this analysis and predictions are done for PbPb collisions at the CERN-LHC energy of 2.76 TeV. A comparison is done to the recent ALICE Collaboration data for the ψ(1S) state photoproduction with good agreement.

  18. Nonresonant Background in Isobaric Models of Photoproduction of η-Mesons on Nucleons

    NASA Astrophysics Data System (ADS)

    Tryasuchev, V. A.; Alekseev, B. A.; Yakovleva, V. S.; Kondratyeva, A. G.

    2016-07-01

    Within the framework of isobaric models of pseudoscalar meson photoproduction, the nonresonant background of photoproduction of η-mesons on nucleons is investigated as a function of energy. A bound on the magnitude of the pseudoscalar coupling constant of the η-meson with a nucleon is obtained: g η NN 2 /4π ≤ 0.01, and a bound on vector meson exchange models is also obtained.

  19. Rescattering in meson photoproduction from few body systems

    SciTech Connect

    J-M. Laget

    2006-04-01

    Exclusive reactions induced at high momentum transfer in few body systems provide us with an original way to study the production and propagation of hadrons in cold nuclear matter. In very well-defined parts of the phase space, the reaction amplitude develops a logarithmic singularity. It is on solid ground since it depends on only on-shell elementary amplitudes and on low momentum components of the nuclear wave function. This is the best window for studying the propagation of exotic configurations of hadrons such as the onset of color transparency. It may appear earlier in meson-photoproduction reactions, more particularly in the strange sector, than in the more classical quasi-elastic scattering of electrons. More generally, those reactions provide us with the best tool to determine the cross section of the scattering of various hadrons (strange particles, vector mesons) from the nucleon and to obtain the production of possible exotic states.

  20. Unitary constraints on charged pion photoproduction at large p⊥

    SciTech Connect

    Laget, Jean-Marc

    2010-01-25

    Around $\\theta_{\\pi}=$90$^\\circ$, the coupling to the $\\rho^\\circ N$ channel leads to a good accounting of the charged pion exclusive photoproduction cross section in the energy range 3 < Eγ < 10 GeV, where experimental data exist. Starting from a Regge Pole approach that successfully describes vector meson production, the singular part of the corresponding box diagrams (where the intermediate vector meson-baryon pair propagates on-shell) is evaluated without any further assumptions (unitarity). Such a treatment provides an explanation of the $s^{-7}$ scaling of the cross section. Furthermore, elastic rescattering of the charged pion improves the basic Regge pole model at forward and backward angles.

  1. Photoproduction of the phi (1020) near threshold in CLAS

    SciTech Connect

    Tedeschi, D J

    2002-06-01

    The differential cross section for the photoproduction of the phi(1020) near threshold (E_{gamma} - 1.57GeV ) is predicted to be sensitive to production mechanisms other than diffraction. However, the existing low energy data is of limited statistics and kinematical coverage. Complete measurements of phi meson production on the proton have been performed at the Thomas Jefferson National Accelerator Facility using a liquid hydrogen target and the CEBAF Large Acceptance Spectrometer (CLAS). The phi was identified by missing mass using a proton and positive kaon detected by CLAS in coincidence with an electron in the photon tagger. The energy of the tagged, bremsstrahlung photons ranged from phi-threshold to 2.4 GeV. A description of the data set and the differential cross section far (E_{gamma} = 2.0 GeV ) will be presented and compared with present theoretical calculations.

  2. Search for new and unusual strangeonia in photoproduction using CLAS

    NASA Astrophysics Data System (ADS)

    Saini, Mukesh S.

    We perform a survey of the proton, K+, K - , - 3 charged track data, taken by the CLAS detector for the HyCLAS experiment [1] during the g12 run-period at Jefferson Lab. We aim to study the strong decay amplitudes, partial widths and production channels of strangeonia from the CLAS g12 dataset. HyCLAS was motivated by the experimental results for gluonic hybrid meson candidates, theoretical Lattice QCD, and Flux-tube Model calculations and predictions. The experiment was designed and conducted to search and observe new forms of hadronic matter through photoproduction. Crucial among the various channels explored in HyCLAS are those for strangeonia,resonances such as φ(1680), φ3(1850) and Y(2175) [2] decaying to φ eta. A meson decay via φ eta is the signature that unequivocally identifies a strangeonium (ss¯ ) state and is the main focus of this thesis. A strangeonium decay via φ eta is considered the premier decay mode to cleanly establish the strangeonia spectrum [3]. This is due to negligible interference of the φ eta decay mode with the non-strange nn¯ (n ∈ {u, d}) meson decay modes, on account of the fact that φ(1020) is an almost pure ss¯ vector meson and the eta meson possesses a strong component of ss¯ in it as well. Another analysis explored was the φ pio decay channel, which is an exotic decay mode for a meson. Decay of an initial ss¯ meson via this channel is forbidden on account of the conservation of isotopic spin whereas the decay of a nn¯ via the φ pi o decay mode is also forbidden by the Okubo - Zweig - Iizuka (OZI) rule. Thus, observation of a resonance decaying to φ pi o will provide strong evidence of mesons beyond qq¯, probably of a gluonic excitation - qq¯g or a tetraquark state - qq¯qq¯ [4]. A final state of proton, K + and K - is selected from the g12 dataset. An intermediate φ state is identified by its decay to K+ K-. Using Energy-Momentum conservation, missing mass in an event is calculated. Depending on the analyses

  3. g8b Experiment at JLab: Photoproduction of PHI meson

    SciTech Connect

    Salamanca, Julian; Cole, Philip

    2009-01-01

    The experiments using polarized photos, at threshold energies, have been taken as relevant experiments because the physics behind them is expected to explain a bunch of problems into the hadronic physics. The nature of parity exchange at threshold energies, strangeness content of proton, violation of Okubo-Zweig-Iizuka observation (OZI rule), are examples of them. Photoproduction of vector mesons by using polarized photons gives a very important way to study those issues. Our goal will be measure the $\\vec {\\gamma} p \\rightarrow \\phi p $ reaction, with $\\phi \\rightarrow K^{+}K^{-} $, in the photon energy range of 1.7GeV to 2.1 GeV by using a Coherent Linear Polarized Photon Beam in Hall-B at Thomas Jefferson Laboratory (Newport News, VA). The experiment where data were taken was called "g8b".

  4. Incoherent Neutral Pion Photoproduction on {sup 12}C

    SciTech Connect

    Tarbert, C. M.; Watts, D. P.; Branford, D.; Foehl, K.; Glazier, D. I.; Aguar, P.; Ahrens, J.; Arends, H. J.; Heid, E.; Jahn, O.; Krambrich, D.; Martinez, M.; Rost, M.; Thomas, A.; Walcher, Th.; Annand, J. R. M.; Codling, R.; Downie, E. J.; Livingston, K.; MacGregor, I. J. D.

    2008-04-04

    We present the first detailed measurement of incoherent photoproduction of neutral pions to a discrete state of a residual nucleus. The {sup 12}C({gamma},{pi}{sup 0}){sup 12}C{sub 4.4} {sub MeV}* reaction has been studied with the Glasgow photon tagger at MAMI employing a new technique which uses the large solid angle Crystal Ball detector both as a {pi}{sup 0} spectrometer and to detect decay photons from the excited residual nucleus. The technique has potential applications to a broad range of future nuclear measurements with the Crystal Ball and similar detector systems elsewhere. Such data are sensitive to the propagation of the {delta} in the nuclear medium and will give the first information on matter transition form factors from measurements with an electromagnetic probe. The incoherent cross sections are compared to two theoretical predictions including a {delta}-hole model.

  5. Near-threshold photoproduction of Φ mesons from deuterium

    SciTech Connect

    Qian, X.; Chen, W.; Gao, H.; Hicks, K.; Kramer, K.; Laget, J. M.; Mibe, T.; Qiang, Y.; Stepanyan, S.; Tedeschi, D. J.; Xu, W.; Adhikari, K. P.; Amaryan, M.; Anghinolfi, M.; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Bellis, M.; Biselli, A. S.; Bookwalter, C.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Careccia, S. L.; Carman, D. S.; Cole, P. L.; Collins, P.; Crede, V.; D'Angelo, A.; Daniel, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Dey, B.; Dhamija, S.; Djalali, C.; Doughty, D.; Dupre, R.; Egiyan, H.; El Alaoui, A.; Eugenio, P.; Fegan, S.; Gabrielyan, M. Y.; Gevorgyan, N.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Gothe, R. W.; Graham, L.; Griffioen, K. A.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Hassall, N.; Holtrop, M.; Ilieva, Y.; Ireland, D. G.; Jawalkar, S. S.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Khetarpal, P.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Konczykowski, P.; Kubarovsky, V.; Kuleshov, S. V.; Kuznetsov, V.; Livingston, K.; Martinez, D.; Mayer, M.; McAndrew, J.; McCracken, M. E.; McKinnon, B.; Meyer, C. A.; Mikhailov, K.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Moreno, B.; Moriya, K.; Morrison, B.; Moutarde, H.; Munevar, E.; Nadel-Turonski, P.; Ni, A.; Niccolai, S.; Niculescu, I.; Niroula, M. R.; Osipenko, M.; Ostrovidov, A. I.; Paremuzyan, R.; Park, K.; Park, S.; Pereira, S. Anefalos; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Seraydaryan, H.; Sharabian, Y. G.; Smith, E. S.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Stepanyan, S. S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Taylor, C. E.; Tkachenko, S.; Ungaro, M.; Vernarsky, B.; Vineyard, M. F.; Voutier, E.; Weinstein, L. B.; Weygand, D. P.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, B.; Zhao, Z. W.

    2011-01-05

    In this report, we measure the differential cross section on $\\phi$-meson photoproduction from deuterium near the production threshold for a proton using the CLAS detector and a tagged-photon beam in Hall B at Jefferson Lab. The measurement was carried out by a triple coincidence detection of a proton, $K^+$ and $K^-$ near the theoretical production threshold of 1.57 GeV. Moreover, the extracted differential cross sections $\\frac{d\\sigma}{dt}$ for the initial photon energy from 1.65-1.75 GeV are consistent with predictions based on a quasifree mechanism. Ultimately, this experiment establishes a baseline for a future experimental search for an exotic $\\phi$-N bound state from heavier nuclear targets utilizing subthreshold/near-threshold production of $\\phi$ mesons.

  6. Near-threshold photoproduction of Φ mesons from deuterium

    DOE PAGESBeta

    Qian, X.; Chen, W.; Gao, H.; Hicks, K.; Kramer, K.; Laget, J. M.; Mibe, T.; Qiang, Y.; Stepanyan, S.; Tedeschi, D. J.; et al

    2011-01-05

    In this report, we measure the differential cross section onmore » $$\\phi$$-meson photoproduction from deuterium near the production threshold for a proton using the CLAS detector and a tagged-photon beam in Hall B at Jefferson Lab. The measurement was carried out by a triple coincidence detection of a proton, $K^+$ and $K^-$ near the theoretical production threshold of 1.57 GeV. Moreover, the extracted differential cross sections $$\\frac{d\\sigma}{dt}$$ for the initial photon energy from 1.65-1.75 GeV are consistent with predictions based on a quasifree mechanism. Ultimately, this experiment establishes a baseline for a future experimental search for an exotic $$\\phi$$-N bound state from heavier nuclear targets utilizing subthreshold/near-threshold production of $$\\phi$$ mesons.« less

  7. Measurement of inclusive prompt photon photoproduction at HERA

    NASA Astrophysics Data System (ADS)

    Breitweg, J.; Chekanov, S.; Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Pellegrino, A.; Repond, J.; Stanek, R.; Yoshida, R.; Mattingly, M. C. K.; Abbiendi, G.; Anselmo, F.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Castellini, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Coppola, N.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Polini, A.; Sartorelli, G.; Zamora Garcia, Y.; Zichichi, A.; Amelung, C.; Bornheim, A.; Brock, I.; Coböken, K.; Crittenden, J.; Deffner, R.; Hartmann, H.; Heinloth, K.; Hilger, E.; Jakob, H.-P.; Kappes, A.; Katz, U. F.; Kerger, R.; Paul, E.; Rautenberg, J.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K. C.; Weber, A.; Wieber, H.; Bailey, D. S.; Barret, O.; Brook, N. H.; Foster, B.; Heath, G. P.; Heath, H. F.; McFall, J. D.; Piccioni, D.; Rodrigues, E.; Scott, J.; Tapper, R. J.; Capua, M.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Jeoung, H. Y.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Ma, K. J.; Pac, M. Y.; Caldwell, A.; Liu, W.; Liu, X.; Mellado, B.; Sacchi, R.; Sampson, S.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Klimek, K.; Olkiewicz, K.; Przybycień, M. B.; Stopa, P.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Jeleń, K.; Kisielewska, D.; Kowal, A. M.; Kowalski, T.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Zajac, J.; Kotański, A.; Bauerdick, L. A. T.; Behrens, U.; Bienlein, J. K.; Burgard, C.; Desler, K.; Drews, G.; Fox-Murphy, A.; Fricke, U.; Goebel, F.; Göttlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G. F.; Hasell, D.; Hebbel, K.; Johnson, K. F.; Kasemann, M.; Koch, W.; Kötz, U.; Kowalski, H.; Lindemann, L.; Löhr, B.; Martínez, M.; Milite, M.; Monteiro, T.; Moritz, M.; Notz, D.; Pelucchi, F.; Petrucci, M. C.; Piotrzkowski, K.; Rohde, M.; Saull, P. R. B.; Savin, A. A.; Schneekloth, U.; Selonke, F.; Sievers, M.; Stonjek, S.; Tassi, E.; Wolf, G.; Wollmer, U.; Youngman, C.; Zeuner, W.; Coldewey, C.; Grabosch, H. J.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.; Straub, P. B.; Barbagli, G.; Gallo, E.; Pelfer, P.; Maccarrone, G.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Markun, P.; Raach, H.; Wölfle, S.; Bussey, P. J.; Doyle, A. T.; Lee, S. W.; Macdonald, N.; McCance, G. J.; Saxon, D. H.; Sinclair, L. E.; Skillicorn, I. O.; Waugh, R.; Bohnet, I.; Gendner, N.; Holm, U.; Meyer-Larsen, A.; Salehi, H.; Wick, K.; Garfagnini, A.; Gialas, I.; Gladilin, L. K.; Kçira, D.; Klanner, R.; Lohrmann, E.; Poelz, G.; Zetsche, F.; Goncalo, R.; Long, K. R.; Miller, D. B.; Tapper, A. D.; Walker, R.; Mallik, U.; Wang, S. M.; Cloth, P.; Filges, D.; Ishii, T.; Kuze, M.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Ahn, S. H.; An, S. H.; Hong, S. J.; Lee, S. B.; Nam, S. W.; Park, S. K.; Lim, H.; Park, I. H.; Son, D.; Barreiro, F.; García, G.; Glasman, C.; Gonzalez, O.; Labarga, L.; del Peso, J.; Redondo, I.; Terrón, J.; Barbi, M.; Corriveau, F.; Hanna, D. S.; Ochs, A.; Padhi, S.; Riveline, M.; Stairs, D. G.; Wing, M.; Tsurugai, T.; Bashkirov, V.; Dolgoshein, B. A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Golubkov, Y. A.; Khein, L. A.; Korotkova, N. A.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Y.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Zotkin, S. A.; Bokel, C.; Botje, M.; Brümmer, N.; Engelen, J.; Koffeman, E.; Kooijman, P.; van Sighem, A.; Tiecke, H.; Tuning, N.; Velthuis, J. J.; Verkerke, W.; Vossebeld, J.; Wiggers, L.; de Wolf, E.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Nylander, P.; Boogert, S.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Große-Knetter, J.; Matsushita, T.; Ruske, O.; Sutton, M. R.; Walczak, R.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; Dondana, S.; Dosselli, U.; Dusini, S.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Iannotti, L.; Oh, B. Y.; Okrasiński, J. R.; Toothacker, W. S.; Whitmore, J. J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cormack, C.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Epperson, D.; Heusch, C.; Sadrozinski, H. F.-W.; Seiden, A.; Wichmann, R.; Williams, D. C.; Pavel, N.; Abramowicz, H.; Dagan, S.; Kananov, S.; Kreisel, A.; Levy, A.; Abe, T.; Fusayasu, T.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Inuzuka, M.; Kitamura, S.; Nishimura, T.; Arneodo, M.; Cartiglia, N.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Ruspa, M.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Fagerstroem, C.-P.; Galea, R.; Koop, T.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sabetfakhri, A.; Simmons, D.; Butterworth, J. M.; Catterall, C. D.; Hayes, M. E.; Heaphy, E. A.; Jones, T. W.; Lane, J. B.; West, B. J.; Ciborowski, J.; Ciesielski, R.; Grzelak, G.; Nowak, R. J.; Pawlak, J. M.; Pawlak, R.; Smalska, B.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Zarnecki, A. F.; Adamus, M.; Gadaj, T.; Deppe, O.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Badgett, W. F.; Chapin, D.; Cross, R.; Foudas, C.; Mattingly, S.; Reeder, D. D.; Smith, W. H.; Vaiciulis, A.; Wildschek, T.; Wodarczyk, M.; Deshpande, A.; Dhawan, S.; Hughes, V. W.; Bhadra, S.; Cole, J. E.; Frisken, W. R.; Hall-Wilton, R.; Khakzad, M.; Menary, S.; Schmidke, W. B.

    2000-01-01

    First inclusive measurements of isolated prompt photons in photoproduction at the HERA /ep collider have been made with the ZEUS detector, using an integrated luminosity of 38.4 pb-1. Cross sections are given as a function of the pseudorapidity and the transverse energy (ηγ, ETγ) of the photon, for ETγ5 GeV in the /γp centre-of-mass energy range 134-285 GeV. Comparisons are made with predictions from Monte Carlo models having leading-logarithm parton showers, and with next-to-leading-order QCD calculations, using currently available parameterisations of the photon structure. For forward ηγ (proton direction) good agreement is found, but in the rear direction all predictions fall below the data.

  8. Photoproduction of hydrogen by membranes of green photosynthetic bacteria

    SciTech Connect

    Bernstein, J D; Olson, J M

    1980-01-01

    Photoproduction of H/sub 2/ from ascorbate by unit-membrane vesicles from Chlorobium limicola f. thiosulfatophilum was achieved with a system containing gramicidin D, tetramethyl-p-phenylenediamine, methyl viologen, dithioerythritol, Clostridium hydrogenase, and an oxygen-scavenging mixture of glucose, glucose oxidase, ethanol, and catalase. Maximum quantum yield was less than one percent. Half maximum rate of H/sub 2/ production occurred at a white-light intensity of approximately 0.15 cm/sup -2/. The reaction was inhibited completely by 0.3% sodium dodecylbenzene sulfonate, 1% Triton X-100, or preheating the vesicles at 100/sup 0/C for 5 minutes. Low concentrations (0.01 and 0.05%) of Triton X-100 about doubled the reaction rate.

  9. Measurement of double polarisation asymmetries in ω-photoproduction

    NASA Astrophysics Data System (ADS)

    Eberhardt, H.; Jude, T. C.; Schmieden, H.; Anisovich, A. V.; Bantes, B.; Bayadilov, D.; Beck, R.; Beloglazov, Yu.; Bichow, M.; Böse, S.; Brinkmann, K.-Th.; Challand, Th.; Crede, V.; Diez, F.; Drexler, P.; Dutz, H.; Elsner, D.; Ewald, R.; Fornet-Ponse, K.; Friedrich, St.; Frommberger, F.; Funke, Ch.; Gottschall, M.; Gridnev, A.; Grüner, M.; Gutz, E.; Hammann, Ch.; Hannappel, J.; Hartmann, J.; Hillert, W.; Hoffmeister, Ph.; Honisch, Ch.; Jaegle, I.; Kaiser, D.; Kalinowsky, H.; Kalischewski, F.; Kammer, S.; Keshelashvili, I.; Kleber, V.; Klein, F.; Klempt, E.; Koop, K.; Krusche, B.; Kube, M.; Lang, M.; Lopatin, I.; Maghrbi, Y.; Makonyi, K.; Metag, V.; Meyer, W.; Müller, J.; Nanova, M.; Nikonov, V.; Novotny, R.; Piontek, D.; Reeve, S.; Reicherz, G.; Rostomyan, T.; Runkel, S.; Sarantsev, A.; Schaepe, St.; Schmidt, Ch.; Schmitz, R.; Seifen, T.; Sokhoyan, V.; Sumachev, V.; Thiel, A.; Thoma, U.; Urban, M.; van Pee, H.; Walther, D.; Wendel, Ch.; Wiedner, U.; Wilson, A.; Winnebeck, A.

    2015-11-01

    The first measurements of the beam-target-helicity-asymmetries E and G in the photoproduction of ω-mesons off protons at the CBELSA/TAPS experiment are reported. E (G) was measured using circularly (linearly) polarised photons and a longitudinally polarised target. E was measured over the photon energy range from close to threshold (Eγ = 1108 MeV) to Eγ = 2300 MeV and G at a single energy interval of 1108

  10. Photoproduction of the ω meson on the proton near threshold

    NASA Astrophysics Data System (ADS)

    Strakovsky, I. I.; Prakhov, S.; Azimov, Ya. I.; Aguar-Bartolomé, P.; Annand, J. R. M.; Arends, H. J.; Bantawa, K.; Beck, R.; Bekrenev, V.; Berghäuser, H.; Braghieri, A.; Briscoe, W. J.; Brudvik, J.; Cherepnya, S.; Codling, R. F. B.; Collicott, C.; Costanza, S.; Demissie, B. T.; Downie, E. J.; Drexler, P.; Fil'kov, L. V.; Glazier, D. I.; Gregor, R.; Hamilton, D. J.; Heid, E.; Hornidge, D.; Jaegle, I.; Jahn, O.; Jude, T. C.; Kashevarov, V. L.; Keshelashvili, I.; Kondratiev, R.; Korolija, M.; Kotulla, M.; Koulbardis, A.; Kruglov, S.; Krusche, B.; Lisin, V.; Livingston, K.; MacGregor, I. J. D.; Maghrbi, Y.; Manley, D. M.; Marinides, Z.; McGeorge, J. C.; McNicoll, E. F.; Mekterovic, D.; Metag, V.; Middleton, D. G.; Mushkarenkov, A.; Nefkens, B. M. K.; Nikolaev, A.; Novotny, R.; Ortega, H.; Ostrick, M.; Otte, P. B.; Oussena, B.; Pedroni, P.; Pheron, F.; Polonski, A.; Robinson, J.; Rosner, G.; Rostomyan, T.; Schumann, S.; Sikora, M. H.; Starostin, A.; Supek, I.; Taragin, M. F.; Tarbert, C. M.; Thiel, M.; Thomas, A.; Unverzagt, M.; Watts, D. P.; Werthmüller, D.; Zehr, F.; A2 Collaboration at MAMI

    2015-04-01

    An experimental study of ω photoproduction on the proton was conducted by using the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. The γ p →ω p differential cross sections are measured from threshold to the incident-photon energy Eγ=1.40 GeV (W =1.87 GeV for the center-of-mass energy) with 15-MeV binning in Eγ and full production-angle coverage. The quality of the present data near threshold gives access to a variety of interesting physics aspects. As an example, an estimation of the ω N scattering length αω p is provided.

  11. Baryon Antibaryon Photoproduction using CLAS at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Phelps, William; CLAS Collaboration

    2013-10-01

    There is little known about the baryon antibaryon production mechanism. The following reactions were looked at, γp -->pp p , γp -->ppπ- n , and γp -->p p π+ n. For these reactions the photon energies that were selected were from 4.4-5.45 GeV. The data were from the g12 experiment taken with the CLAS detector using a liquid hydrogen target at Thomas Jefferson National Accelerator Facility. This experiment had high statistics, with a luminosity of 68 pb-1. Features of the data such as invariant mass spectra, missing mass spectra, and angular distributions necessary for the analysis will be shown. In addition, a first observation of antineutrons in photoproduction in the missing mass spectra of γp -->ppπ- n will also be shown.

  12. Baryon Antibaryon Photoproduction using CLAS at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Phelps, William; CLAS Collaboration

    2014-09-01

    There is little known about the baryon antibaryon photoproduction mechanism. Three reactions, γ p --> pp p , γp --> pp π- n , and γp --> p p π+ n have been investigated for the photon energy range of 4.4-5.45 GeV. The data were from the g12 experiment taken with the CLAS detector using a liquid hydrogen target at Thomas Jefferson National Accelerator Facility. This experiment had high statistics, with an integrated luminosity of 68 pb-1. General features of the data for these three reactions will be shown. In particular, the angular and energy dependence of the antibaryons as well as the preliminary normalized yields will be presented. Also, preliminary partial wave analysis results for the p p system will be discussed.

  13. Baryon Antibaryon Photoproduction using CLAS at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Phelps, William

    2015-04-01

    There is little known about the baryon antibaryon photoproduction mechanism. Three reactions, γp --> pp p , γp --> ppπ- n , and γp --> p p π+ n have been investigated for the photon energy range of 4.4-5.45 GeV. The data were from the g12 experiment taken with the CLAS detector using a liquid hydrogen target at Thomas Jefferson National Accelerator Facility. This experiment had high statistics, with an integrated luminosity of 68 pb-1. General features of the data for these three reactions will be shown. In particular, the angular and energy dependence of the antibaryons as well as the preliminary normalized yields will be presented. Also, preliminary partial wave analysis results for the p p system will be discussed.

  14. Unitary constraints on charged pion photoproduction at large p⊥

    DOE PAGESBeta

    Laget, Jean-Marc

    2010-01-25

    Aroundmore » $$\\theta_{\\pi}=$$90$$^\\circ$$, the coupling to the $$\\rho^\\circ N$$ channel leads to a good accounting of the charged pion exclusive photoproduction cross section in the energy range 3 < Eγ < 10 GeV, where experimental data exist. Starting from a Regge Pole approach that successfully describes vector meson production, the singular part of the corresponding box diagrams (where the intermediate vector meson-baryon pair propagates on-shell) is evaluated without any further assumptions (unitarity). Such a treatment provides an explanation of the $$s^{-7}$$ scaling of the cross section. Furthermore, elastic rescattering of the charged pion improves the basic Regge pole model at forward and backward angles.« less

  15. Electro- and Photoproduction of Vector Mesons at Jefferson Lab

    SciTech Connect

    Marco Battaglieri

    2002-09-01

    The total and differential cross section for exclusive electro- and photoproduction of vector mesons in the resonance region and above (1.6 < W < 2.9 GeV) was measured at Jefferson Laboratory in a wide kinematic range (0 < Q2 < 4 GeV2 and 0< -t < 5 GeV2). The measurement of the total and differential cross section down to 100 pb/GeV2 with the full kinematic coverage, was possible for the first time thanks to the combination of the 100% duty cycle of CEBAF and the large acceptance of the CLAS detector. The main results from the CLAS Collaboration activity in this field will be presented and discussed.

  16. Photoproduction at Relativistic Heavy Ion Collider with STAR

    NASA Astrophysics Data System (ADS)

    Gorbunov, Yury

    2010-11-01

    Relativistic heavy ions carry strong transverse electromagnetic fields which can be treated as sources of quasi-real virtual photons. The ions interact through photon-Pomeron and photon-photon collisions at impact parameter more than twice the nuclear radius, so hadronic interactions are suppressed. We present recent results of the STAR experiment at RHIC on 0̂(770) production in AuAu collisions at various energies. STAR is also sensitive to the interference between two production modes: either ion can be the photon emitter or the target. We observed the coherent photoproduction of &+circ;&-circ;π+&-circ;, which maybe attributed to one of the poorly known excited states of 0̂. As well in this talk we will present preliminary results based on data collected during run 10.

  17. The SOS-dependent upregulation of uvrD is not required for efficient nucleotide excision repair of ultraviolet light induced DNA photoproducts in Escherichia coli.

    PubMed

    Crowley, D J; Hanawalt, P C

    2001-05-10

    We have shown previously that induction of the SOS response is required for efficient nucleotide excision repair (NER) of the major ultraviolet light (UV) induced DNA lesion, the cyclobutane pyrimidine dimer (CPD), but not for repair of 6-4 photoproducts (6-4PP) or for transcription-coupled repair of CPDs [1]. We have proposed that the upregulation of cellular NER capacity occurs in the early stages of the SOS response and enhances the rate of repair of the abundant yet poorly recognized genomic CPDs. The expression of three NER genes, uvrA, uvrB, and uvrD, is upregulated as part of the SOS response. UvrD differs from the others in that it is not involved in lesion recognition but rather in promoting the post-incision steps of NER, including turnover of the UvrBC incision complex. Since uvrC is not induced during the SOS response, its turnover would seem to be of great importance in promoting efficient NER. Here we show that the constitutive level of UvrD is adequate for carrying out efficient NER of both CPDs and 6-4PPs. Thus, the upregulation of uvrA and uvrB genes during the SOS response is sufficient for inducible NER of CPDs. We also show that cells with a limited NER capacity, in this case due to deletion of the uvrD gene, repair 6-4PPs but cannot perform transcription-coupled repair of CPDs, indicating that the 6-4PP is a better substrate for NER than is a CPD targeted for transcription-coupled repair. PMID:11585364

  18. 4,2':6',4''-Terpyridines: diverging and diverse building blocks in coordination polymers and metallomacrocycles.

    PubMed

    Housecroft, Catherine E

    2014-05-14

    4,2':6',4''-Terpyridine (4,2':6',4''-tpy) is one of the less well documented isomers of the well-established bis-chelating 2,2':6',2''-terpyridine. The N-donors of the outer rings in 4,2':6',4''-tpy subtend an angle of 120°, leading to a description of 4,2':6',4''-tpy as a divergent ligand. Because it typically binds metal ions through the outer N-donors only, 4,2':6',4''-tpy is an ideal linker for combination with metal nodes (often geometrically flexible d(10) ions) in coordination polymers and metallomacrocyclic complexes. The facile functionalization of terpyridines in the 4'-position allows access to a suite of 4'-X-4,2':6',4''-tpy ligands in which the 4'-substituent, X, can be selected to assist in directing the metal-ligand assembly process. This overview of recent advances in the chemistry of 4,2':6',4''-tpy and its 4'-substituted derivatives looks at relationships within a series of chiral polymers, competition between the formation of metallocyclic complexes versus polymers, and the use of extended aryl systems to encourage the formation of coordination polymers in which π-stacking of arene domains dominates in the assembly process. Use of metal(ii) acetates is key to the formation of paddle-wheel and larger cluster nodes that direct the assembly of both predetermined and unexpected architectures. PMID:24522847

  19. An investigation of adhesive/adherend and fiber matrix interactions. [Ti 6-4 surfaces

    NASA Technical Reports Server (NTRS)

    Beck, B.; Siriwardane, R.; Wightman, J. P.

    1981-01-01

    Research during the report period focused on continued scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) of lap shear samples and flatwise tensile specimens and on the surface characterization of TiO2, Ti 6-4, and Ti powders with particular emphasis on their interaction with primer solutions of both polyphenylquinoxaline and LaRC-13 polyimide. The use of SEM and XPS in the analysis of Ti 6-4 adherend surfaces is described as well as differences in Ti 6-4 surface composition after different chemical pretreatments. Analysis of fractured surfaces is used to established the failure mode. The surface acidity of Ti 6-4 coupons can be established by reflectance visible spectroscopy using indicator dyes.

  20. Determining pseudoscalar meson photoproduction amplitudes from complete experiments

    NASA Astrophysics Data System (ADS)

    Sandorfi, A. M.; Hoblit, S.; Kamano, H.; Lee, T.-S. H.

    2011-05-01

    A new generation of complete experiments is focused on a high precision extraction of pseudoscalar meson photoproduction amplitudes. Here, we review the development of the most general analytic form of the cross section, dependent upon the three polarization vectors of the beam, target and recoil baryon, including all single-, double- and triple-polarization terms involving 16 spin-dependent observables. We examine the different conventions that have been used by different authors, and we present expressions that allow the direct numerical calculation of any pseudoscalar meson photoproduction observables with arbitrary spin projections from the Chew-Goldberger-Low-Nambu amplitudes. We use this numerical tool to clarify apparent sign differences that exist in the literature, in particular with the definitions of six double-polarization observables. We also present analytic expressions that determine the recoil baryon polarization, together with examples of their potential use with quasi-4π detectors to deduce observables. As an illustration of the use of the consistent machinery presented in this review, we carry out a multipole analysis of the γp → K+Λ reaction and examine the impact of recently published polarization measurements. When combining data from different experiments, we utilize the Fierz identities to fit a consistent set of scales. In fitting multipoles, we use a combined Monte Carlo sampling of the amplitude space, with gradient minimization, and find a shallow χ2 valley pitted with a very large number of local minima. This results in broad bands of multipole solutions that are experimentally indistinguishable. While these bands have been noticeably narrowed by the inclusion of new polarization measurements, many of the multipoles remain very poorly determined, even in sign, despite the inclusion of data on eight different observables. We have compared multipoles from recent PWA codes with our model-independent solution bands and found that such

  1. Study of the two pion final state photoproduction on deuterium

    SciTech Connect

    Lewis Graham, Kijun Park, Ralf Gothe, Elton Smith

    2010-08-01

    Understanding the structure of baryons in terms of the fundamental interaction of the constituent quarks and gluons is one of the challenges in strong interaction physics. This interaction is governed by Quantum Chromodynamics (QCD). However, solutions of this theory in the non-perturbative domain of the interaction are extremely difficult to achieve. In inelastic electron scattering, very little is known about exclusive hadron production purely contributed to a lack of knowledge. The gammaN interaction is recognized for being a powerful method for investigating hadrons and the mysteries that still exist within the strong interaction. From reactions with the nucleon, the strong interaction can be tested through the amplitudes of the N and Delta resonances. More specifically, if an electromagnetic interaction is well known then the intermediate resonance states may be evaluated through pion photoproduction. To gain more detailed insight into this interaction, we look to probe the baryon structure of Delta and the meson structure of the pion through photon scattering off a deuteron producing two pions in the final state. The photoproduction processes on the deuteron will be used to investigate known baryon resonances in the proton-pion channel. The two pion final state will be investigated for unraveling new information in to the rho decay at threshold. We want to explore both final states interactions to search for “missing” states that are predicted by quark models but have not yet been found experimentally. Using the CEBAF Large Acceptance Spectrometer (CLAS), the hadronic products are detected in coincidence with the scattered photon. This makes it possible to measure the differential cross section and the decay angular distribution for the production of two and three pion final states. The measured cross sections will contribute significantly and push the knowledge of the strong interaction to the next level. We propose to use the CEBAF Large Acceptance

  2. Study of the two pion final state photoproduction on deuterium

    SciTech Connect

    Graham, Lewis; Gothe, Ralf; Park, Kijun; Smith, Elton

    2010-08-05

    Understanding the structure of baryons in terms of the fundamental interaction of the constituent quarks and gluons is one of the challenges in strong interaction physics. This interaction is governed by Quantum Chromodynamics (QCD). However, solutions of this theory in the non-perturbative domain of the interaction are extremely difficult to achieve. In inelastic electron scattering, very little is known about exclusive hadron production purely contributed to a lack of knowledge. The {gamma}N interaction is recognized for being a powerful method for investigating hadrons and the mysteries that still exist within the strong interaction. From reactions with the nucleon, the strong interaction can be tested through the amplitudes of the N and {Delta} resonances. More specifically, if an electromagnetic interaction is well known then the intermediate resonance states may be evaluated through pion photoproduction. To gain more detailed insight into this interaction, we look to probe the baryon structure of {Delta} and the meson structure of the pion through photon scattering off a deuteron producing two pions in the final state. The photoproduction processes on the deuteron will be used to investigate known baryon resonances in the proton-pion channel. The two pion final state will be investigated for unraveling new information in to the rho decay at threshold. We want to explore both final states interactions to search for ''missing'' states that are predicted by quark models but have not yet been found experimentally. Using the CEBAF Large Acceptance Spectrometer (CLAS), the hadronic products are detected in coincidence with the scattered photon. This makes it possible to measure the differential cross section and the decay angular distribution for the production of two and three pion final states. The measured cross sections will contribute significantly and push the knowledge of the strong interaction to the next level. We propose to use the CEBAF Large Acceptance

  3. The photoyellowing of stilbene-derived fluorescent whitening agents--mass spectrometric characterization of yellow photoproducts.

    PubMed

    Dyer, Jolon M; Cornellison, Charisa D; Bringans, Scott D; Maurdev, George; Millington, Keith R

    2008-01-01

    The application of fluorescent whitening agents (FWAs) significantly accelerates the photoyellowing of wool and silk under exposure to the ultraviolet and visible components of sunlight <500 nm. The photochemistry involved in this process is poorly understood, particularly the role of photoproducts derived directly from the FWA itself. Hydroxylation was identified as the key initial mechanism of photodegradation leading to coloration of the solution in the irradiation of the stilbene-derived FWA 4,4'-bis(2-sulfostyryl)biphenyl (DSBP) in the presence of hydrogen peroxide (H2O2). Polyhydroxylated DSBP derivatives were implicated as critical intermediates in the formation of yellow photoproducts under these conditions. The formation of trace quantities of DSBP quinone derivatives subsequent to hydroxylation was identified as the key cause of DSBP photoyellowing. These results are the first successful characterization of yellow photoproducts resulting directly from irradiation of a stilbene-based FWA. Formation of these yellow stilbene-based FWA-derived photoproducts may occur on the surface of FWA-treated wool exposed to simulated sunlight, as previous work has shown that H2O2 is photogenerated when wet FWA-treated wool is exposed to light. These results therefore suggest that yellow FWA-derived photoproducts contribute to the accelerated photoyellowing of FWA-treated wool. PMID:18173714

  4. Photoproduction of carbonyl sulfide in south Pacific Ocean waters as a function of irradiation wavelength

    NASA Technical Reports Server (NTRS)

    Weiss, Peter S.; Andrews, Steven S.; Johnson, James E.; Zafiriou, Oliver C.

    1995-01-01

    Carbonly sulfide (OCS) photoproduction rates were measured at selected wavelengths of ultraviolet light between 297 and 405 nm in sea water samples from the southern Pacific Ocean. Near-surface and column production rate spectra for natural sunlit waters were calculated using sea-surface sunlight data measured near the austral summer solstice. These plots show that photoproduction rates are at a maximum at 313 nm in tropical waters and at 336 nm in Antarctic waters. Tropical surface and column rates were found to be 68 pM/day and 360 nmol/sq m/day, respectively, and Antarctic surface and column rates were found to be 101 pM/day and 620 nmol/sq m/day, respectively. A high degree of variability was observed between photoproduction rates from different ocean regions, with coastal rates being the highest, suggesting that natural environmental variability is an important factor. Photoproduction rates at 297 nm were found to be constant at individual locations with increasing irradiation time. Relative photoproduction rates from this work are compared to previously measured rates from coastal sea water.

  5. Carbon Monoxide Photoproduction from Particles and Solutes in the Delaware Estuary under Contrasting Hydrological Conditions.

    PubMed

    Song, Guisheng; Richardson, John D; Werner, James P; Xie, Huixiang; Kieber, David J

    2015-12-15

    Full-spectrum, ultraviolet (UV), and visible broadband apparent quantum yields (AQYs) for carbon monoxide (CO) photoproduction from chromophoric dissolved organic matter (CDOM) and particulate organic matter (POM) were determined in the Delaware Estuary in two hydrologically contrasting seasons in 2012: an unusually low flow in August and a storm-driven high flow in November. Average AQYs for CDOM and POM in November were 10 and 16 times the corresponding AQYs in August. Maximum AQYs in November occurred in a midestuary particle absorption maximum zone. Although POM AQYs were generally smaller than CDOM AQYs, the ratio of the former to the latter increased substantially from the UV to the visible. In both seasons, UV solar radiation was the primary driver for CO photoproduction from CDOM whereas visible light was the principal contributor to POM-based CO photoproduction. CDOM dominated CO photoproduction in the uppermost water layer while POM prevailed at deeper depths. On a depth-integrated basis, the Delaware Estuary shifted from a CDOM-dominated system in August to a POM-dominated system in November with respect to CO photoproduction. This study reveals that flood events may enhance photochemical cycling of terrigenous organic matter and switch the primary photochemical driver from CDOM to POM. PMID:26506215

  6. Fluorescence and mass spectrometry studies of meta-tetra(hydroxyphenyl)chlorin photoproducts.

    PubMed

    Kasselouri, A; Bourdon, O; Demore, D; Blais, J C; Prognon, P; Bourg-Heckly, G; Blais, J

    1999-09-01

    The meta-tetra(hydroxyphenyl)chlorin (m-THPC), a second-generation sensitizer used in photodynamic therapy (PDT), is currently under clinical trial. In vivo fluorometry provides direct evidence that photobleaching processes are induced at the tumor site during PDT. Photoproduct formation has thus to be taken into account to fully understand PDT treatment. A preliminary step is to determine the fluorescence characteristics of photoproducts formed in solution. Solutions of m-THPC irradiated at 514 nm have been separated by HPLC using absorption and fluorescence detection. Six main photoproducts have been isolated. According to matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS) results, five fluorescent photoproducts emitting at 652 nm have been attributed to three mono-, one di- and one tri-hydroxy derivatives (m/z 697, 713 and 729, respectively). Fluorescence characteristics of mono-hydroxy forms were found to be similar to those of m-THPC, whereas fluorescence yields in di- and tri-hydroxy derivatives were very low. Another product, corresponding to a MALDI-TOF MS main signal at m/z 542, showed an absorption spectrum maximum at 522 nm while a weak fluorescence was detected at 480 nm. The loss of the Soret band suggests that this photoproduct results from the opening of the reduced pyrrole ring. The part played by each of these products in the photobleaching phenomenon of m-THPC is discussed. PMID:10483355

  7. Role of two-nucleon mechanisms in pion photoproduction on nuclei in the region of high momentum transfers

    SciTech Connect

    Egorov, M. V.; Fix, A. I.

    2013-05-15

    The role of two-nucleon mechanisms in pion photoproduction on nuclei was studied in the region of high momentum transfers to the residual nucleus. The process in which the photoproduction of negative pions on a {sup 12}C nucleus is accompanied by proton emission was considered by way of example. The results of the calculations were compared with available experimental data.

  8. STRUCTURES OF SOME KEPONE PHOTOPRODUCTS AND RELATED CHLORINATED PENTACYCLODECANES BY CARBON-13 AND PROTON NUCLEAR MAGNETIC RESONANCE

    EPA Science Inventory

    The pesticide Kepone, 1,1a,3,3a,4,5,5a,5b,6-decachlorooctahydro-1,3,4-metheno-2H-cyclobuta(cd)pentalen-2-one, the related compounds mirex, kelevan, a monohydro photoproduct of kelevan, kepone alcohol, kepone hydrate, and the mono- and dihydro photoproducts of Kepone hydrate and t...

  9. Measurement of open beauty production in photoproduction at HERA

    NASA Astrophysics Data System (ADS)

    ZEUS Collaboration; Breitweg, J.; et al.

    2001-01-01

    The production and semi-leptonic decay of heavy quarks have been studied in the photoproduction process e+p -> e+ + dijet + e- + X with the ZEUS detector at HERA using an integrated luminosity of 38.5 pb -1. Events with photon-proton centre-of-mass energies, Wγ p, between 134 and 269 GeV and a photon virtuality, Q2, less than 1 GeV 2 were selected requiring at least two jets of transverse energy ET jet1(2) >7(6) GeV and an electron in the final state. The electrons were identified by employing the ionisation energy loss measurement. The contribution of beauty quarks was determined using the transverse momentum of the electron relative to the axis of the closest jet, pT rel. The data, after background subtraction, were fit with a Monte Carlo simulation including beauty and charm decays. The measured beauty cross section was extrapolated to the parton level with the b quark restricted to the region of transverse momentum pT^b > pT^min = 5 GeV and pseudorapidity |η b| < 2. The extrapolated cross section is 1.6 +/- 0.4 (stat.)+0.3-0.5 (syst.) +0.2-0.4 (ext.) nb. The result is compared to a perturbative QCD calculation performed to next-to-leading order.

  10. Photoproduction of $\\pi^+ \\pi^-$ meson pairs on the proton

    SciTech Connect

    Marco A. Battaglieri; DeVita, Raffaella; Szczepaniak, Adam P.

    2009-10-01

    The exclusive reaction $\\gamma p \\to p \\pi^+ \\pi^-$ was studied in the photon energy range 3.0 - 3.8 GeV and momentum transfer range $0.4<-t<1.0$ GeV$^2$. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. In this kinematic range the integrated luminosity was about 20 pb$^{-1}$. The reaction was isolated by detecting the $\\pi^+$ and proton in CLAS, and reconstructing the $\\pi^-$ via the missing-mass technique. Moments of the di-pion decay angular distributions were derived from the experimental data. Differential cross sections for the $S$, $P$, and $D$-waves in the $M_{\\pi^+\\pi^-}$ mass range $0.4-1.4$ GeV were derived performing a partial wave expansion of the extracted moments. Besides the dominant contribution of the $\\rho(770)$ meson in the $P$-wave, evidence for the $f_0(980)$ and the $f_2(1270)$ mesons was found in the $S$ and $D$-waves, respectively. The differential production cross sections $d\\sigma/dt$ for individual waves in the mass range of the above-mentioned mesons were extracted. This is the first time the $f_0(980)$ has been measured in a photoproduction experiment.

  11. Λ(1520) photoproduction off a proton target with Regge contributions

    NASA Astrophysics Data System (ADS)

    Nam, Seung-Il; Kao, Chung-Wen

    2010-05-01

    We investigate the Λ(1520,3/2-)≡Λ* photoproduction off the proton target beyond the resonance region within a model including the Regge contributions, the tree-level diagrams with the nucleon and the certain resonance intermediate states, and one contact term. The Reggeized propagators for the K and K* exchanges in the t channel are employed in a gauge-invariant manner. We compute the angular and energy dependences of the cross section and some polarization observables, such as the photon-beam asymmetry and the polarization-transfer coefficients. Our results qualitatively agree with the current experimental data. We find that the Regge contributions are necessary to explain the high-energy data beyond Eγ≈4 GeV, especially for the angular dependences in the forward region. On the contrary, the polarization observables are insensitive to the Regge contributions due to the contact-term dominance, which is a consequence of gauge invariance. We also calculate the K--angle distribution function in the Gottfried-Jackson frame, using the polarization-transfer coefficients in the z direction. We find that it owns a complicated angle and energy dependences in the forward K+ scattering region.

  12. {Lambda}K*{Lambda}(1116) photoproduction and nucleon resonances

    SciTech Connect

    Kim, Sang-Ho; Kim, Hyun-Chul; Nam, Seung-il; Oh, Yongseok

    2011-10-21

    In this presentation, we report our recent studies on the {Lambda}K*{Lambda}(1116) photoproduction off the proton target, using the tree-level Born approximation, via the effective Lagrangian approach. In addition, we include the nine (three- or four-star confirmed) nucleon resonances below the threshold {radical}(s{sub th}){approx_equal}2008 MeV, to interpret the discrepancy between the experiment and previous theoretical studies, in the vicinity of the threshold region. From the numerical studies, we observe that the S{sub 11}(1535) and S11(1650) play an important role for the cross-section enhancement near the {radical}(s{sub th}). It also turns out that, in order to reproduce the data, we have the vector coupling constants gK*S{sub 11}(1535){Lambda} = (7.0{approx}9.0) and gK*S{sub 11}(1650){Lambda} (5.0{approx}6.0).

  13. Diffractive Higgs boson photoproduction in ultraperipheral collisions at LHC

    SciTech Connect

    Gay Ducati, M. B.; Silveira, G. G.

    2010-10-01

    A new production mechanism for the standard model Higgs boson in ultraperipheral collisions at the LHC, which allows central exclusive diffractive production by double pomeron exchange in photon-proton processes, is presented. The Higgs boson is centrally produced by gluon fusion with two large rapidity gaps emerging in the final state, being the main experimental signature for this process. As already studied for Pomeron-Pomeron and two-photon processes, the Higgs boson photoproduction is studied within this new mechanism in proton-proton (pp) and proton-nucleus (pA) collisions, where each system has a different dynamics to be taken into account. As a result, this mechanism predicts a production cross section for pp collisions of about 1.8 fb, which is similar to that obtained in Pomeron-Pomeron processes. Besides, in pPb collisions the cross sections have increased to about 0.6 pb, being comparable with the results of two-photon processes in pAu collisions. Therefore, as the rapidity gap survival probability is an open question in high-energy physics, an analysis for different values of this probability shows how competitive the mechanisms are in the LHC kinematical regime.

  14. Transverse polarization of {lambda} and {lambda} hyperons in quasireal photoproduction

    SciTech Connect

    Airapetian, A.; Akopov, N.; Akopov, Z.; Avakian, R.; Avetissian, A.; Elbakian, G.; Gharibyan, V.; Marukyan, H.; Rostomyan, A.; Taroian, S.; Zohrabian, H.; Amarian, M.; Ammosov, V. V.; Gapienko, G.; Gapienko, V.; Tchuiko, B.; Andrus, A.; Bailey, P.; Bouwhuis, M.; Chiang, H. C.

    2007-11-01

    The HERMES experiment has measured the transverse polarization of {lambda} and {lambda} hyperons produced inclusively in quasireal photoproduction at a positron beam energy of 27.6 GeV. The transverse polarization P{sub n}{sup {lambda}} of the {lambda} hyperon is found to be positive while the observed {lambda} polarization is compatible with zero. The values averaged over the kinematic acceptance of HERMES are P{sub n}{sup {lambda}}=0.078{+-}0.006(stat){+-}0.012(syst) and P{sub n}{sup {lambda}}=-0.025{+-}0.015(stat){+-}0.018(syst) for {lambda} and {lambda}, respectively. The dependences of P{sub n}{sup {lambda}} and P{sub n}{sup {lambda}} on the fraction {zeta} of the beam's light-cone momentum carried by the hyperon and on the hyperon's transverse momentum p{sub T} were investigated. The measured {lambda} polarization rises linearly with p{sub T} and exhibits a different behavior for low and high values of {zeta}, which approximately correspond to the backward and forward regions in the center-of-mass frame of the {gamma}*N reaction.

  15. High-energy photoproduction of rho and phi vector mesons

    SciTech Connect

    Callahan, P.H.

    1983-01-01

    We have studied the photoproduction of rho and phi vector mesons from hydrogen in the Fermilab broad band neutral beam. Forward going two particle final states were detected in a multiparticle spectrometer consisting of two analyzing magnets, a multiwire-proportional-chamber tracking system and a particle identification system. Recoil protons and target fragments were observed in a recoil detector which surrounded the target. The total elastic cross-sections were measured to be independent of energy at the 10% level from 35 to 225 GeV at 10.6 ..mu..b for the rho and from 35 to 165 GeV at 0.64 ..mu..b for the phi. The elastic differential cross-sections were also measured. Approximately 20% of the diffractive rho and phi events were found to be inelastic from an analysis of the recoil detector. The t-dependence of the fraction of diffractive events which are inelastic for both the phi and the psi are consistent with a universal function determined from the rho data.

  16. Diffractive dijet cross sections in photoproduction at HERA

    NASA Astrophysics Data System (ADS)

    Breitweg, J.; Derrick, M.; Krakauer, D.; Magill, S.; Mikunas, D.; Musgrave, B.; Repond, J.; Stanek, R.; Talaga, R. L.; Yoshida, R.; Zhang, H.; Mattingly, M. C. K.; Anselmo, F.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Romeo, G. Cara; Castellini, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Coppola, N.; Corradi, M.; de Pasquale, S.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Polini, A.; Sartorelli, G.; Garcia, Y. Zamora; Zichichi, A.; Amelung, C.; Bornheim, A.; Brock, I.; Coböken, K.; Crittenden, J.; Deffner, R.; Eckert, M.; Grothe, M.; Hartmann, H.; Heinloth, K.; Heinz, L.; Hilger, E.; Jakob, H.-P.; Kappes, A.; Katz, U. F.; Kerger, R.; Paul, E.; Pfeiffer, M.; Stamm, J.; Wieber, H.; Bailey, D. S.; Campbell-Robson, S.; Cottingham, W. N.; Foster, B.; Hall-Wilton, R.; Heath, G. P.; Heath, H. F.; McFall, J. D.; Piccioni, D.; Roff, D. G.; Tapper, R. J.; Ayad, R.; Capua, M.; Iannotti, L.; Schioppa, M.; Susinno, G.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Pac, M. Y.; Caldwell, A.; Cartiglia, N.; Jing, Z.; Liu, W.; Mellado, B.; Parsons, J. A.; Ritz, S.; Sampson, S.; Sciulli, F.; Straub, P. B.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Klimek, K.; Przybycień, M. B.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Bukowy, M.; Czermak, A. M.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Przybycień, M.; Rulikowska-Zarbska, E.; Suszycki, L.; Zajc, J.; Duliński, Z.; Kotański, A.; Abbiendi, G.; Bauerdick, L. A. T.; Behrens, U.; Beier, H.; Bienlein, J. K.; Desler, K.; Drews, G.; Fricke, U.; Gialas, I.; Goebel, F.; Göttlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hasell, D.; Hebbel, K.; Johnson, K. F.; Kasemann, M.; Koch, W.; Kötz, U.; Kowalski, H.; Lindemann, L.; Löhr, B.; Milewski, J.; Milite, M.; Monteiro, T.; Ng, J. S. T.; Notz, D.; Park, I. H.; Pellegrino, A.; Pelucchi, F.; Piotrzkowski, K.; Rohde, M.; Roldán, J.; Ryan, J. J.; Savin, A. A.; Schneekloth, U.; Schwarzer, O.; Selonke, F.; Stonjek, S.; Surrow, B.; Tassi, E.; Westphal, D.; Wolf, G.; Wollmer, U.; Youngman, C.; Zeuner, W.; Burow, B. D.; Coldewey, C.; Grabosch, H. J.; Meyer, A.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Pelfer, P.; Maccarrone, G.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Markun, P.; Raach, H.; Trefzger, T.; Wölfle, S.; Bromley, J. T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; MacDonald, N.; Saxon, D. H.; Sinclair, L. E.; Skillicorn, I. O.; Strickland, E.; Waugh, R.; Bohnet, I.; Gendner, N.; Holm, U.; Meyer-Larsen, A.; Salehi, H.; Wick, K.; Garfagnini, A.; Gladilin, L. K.; Horstmann, D.; Kçira, D.; Klanner, R.; Lohrmann, E.; Poelz, G.; Schott, W.; Zetsche, F.; Bacon, T. C.; Butterworth, I.; Cole, J. E.; Howell, G.; Lamberti, L.; Long, K. R.; Miller, D. B.; Pavel, N.; Prinias, A.; Sedgbeer, J. K.; Sideris, D.; Walker, R.; Mallik, U.; Wang, S. M.; Wu, J. T.; Cloth, P.; Filges, D.; Fleck, J. I.; Ishii, T.; Kuze, M.; Suzuki, I.; Tokushuku, K.; Yamada, S.; Yamauchi, K.; Yamazaki, Y.; Hong, S. J.; Lee, S. B.; Nam, S. W.; Park, S. K.; Barreiro, F.; Fernández, J. P.; García, G.; Glasman, C.; Hernández, J. M.; Hervás, L.; Labarga, L.; Martínez, M.; Peso, J. Del; Puga, J.; Terrón, J.; Trocóniz, J. F. De; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Murray, W. N.; Ochs, A.; Riveline, M.; Stairs, D. G.; St-Laurent, M.; Ullmann, R.; Tsurugai, T.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Golubkov, Yu. A.; Khein, L. A.; Korotkova, N. A.; Korzhavina, I. A.; Kuzinin, V. A.; Lukina, O. Yu.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Zotkin, S. A.; Bokel, C.; Botje, M.; Brümmer, N.; Engelen, J.; Koffeman, E.; Kooijman, P.; van Sighem, A.; Tiecke, H.; Tuning, N.; Verkerke, W.; Vossebeld, J.; Wiggers, L.; Wolf, E. De; Acosta, D.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Nylander, P.; Romanowski, T. A.; Blaikley, H. E.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Edmonds, J. K.; Große-Knetter, J.; Harnew, N.; Nath, C.; Noyes, V. A.; Quadt, A.; Ruske, O.; Tickner, J. R.; Walczak, R.; Waters, D. S.; Bertolin, A.; Brugnera, R.; Carlin, R.; Corso, F. Dal; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Bulmahn, J.; Oh, B. Y.; Okrasiński, J. R.; Toothacker, W. S.; Whitmore, J. J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Raso, M.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Epperson, D.; Heusch, C.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Wichmann, R.; Williams, D. C.; Abramowicz, H.; Briskin, G.; Dagan, S.; Kananov, S.; Levy, A.; Abe, T.; Fusayasu, T.; Inuzuka, M.; Nagano, K.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Matsushita, T.; Arneodo, M.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Petrucci, M. C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Fagerstroem, C.-P.; Galea, R.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sabetfakhri, A.; Simmons, D.; Teuscher, R. J.; Butterworth, J. M.; Catterall, C. D.; Hayes, M. E.; Jones, T. W.; Lane, J. B.; Saunders, R. L.; Sutton, M. R.; Wing, M.; Ciborowski, J.; Grzelak, G.; Kasprzak, M.; Nowak, R. J.; Pawlak, J. M.; Pawlak, R.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Zarnecki, A. F.; Adamus, M.; Deppe, O.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Badgett, W. F.; Chapin, D.; Cross, R.; Dasu, S.; Foudas, C.; Loveless, R. J.; Mattingly, S.; Reeder, D. D.; Smith, W. H.; Vaiciulis, A.; Wodarczyk, M.; Deshpande, A.; Dhawan, S.; Hughes, V. W.; Bhadra, S.; Frisken, W. R.; Khakzad, M.; Schmidke, W. B.

    1998-08-01

    Differential dijet cross sections have been measured with the ZEUS detector for photoproduction events in which the hadronic final state containing the jets is separated with respect to the outgoing proton direction by a large rapidity gap. The cross section has been measured as a function of the fraction of the photon (ϰγ OBS) and pomeron (β OBS) momentum participating in the production of the dijet system. The observed ϰγ OBS dependence shows evidence for the presence of a resolved- as well as a direct-photon component. The measured cross section da/dβ OBS increases as β OBS increases indicating that there is a sizeable contribution to dijet production from those events in which a large fraction of the pomeron momentum participates in the hard scattering. These cross sections and the ZEUS measurements of the diffractive structure function can be described by calculations based on parton densities in the pomeron which evolve according to the QCD evolution equations and include a substantial hard momentum component of gluons in the pomeron.

  17. Rescattering in Meson Photoproduction off Few Body Systems

    SciTech Connect

    Jean-Marc Laget

    2006-04-01

    Exclusive reactions induced at high momentum transfer in few body systems allow to adjust the formation time of the produced particles to the distance between two nucleons in the target. They are the best windows to study the propagation of exotic configurations of hadrons such as for instance the onset of color transparency. It may appear earlier in meson photo-production reactions, in the strange sector more particularly, than in more classical quasi elastic scattering of electrons. More generally, those reactions provide them with the best tool to determine the cross section of the scattering of various hadrons (strange particles, vector mesons) with nucleon, to better understand the mechanisms of their formation in cold hadronic matter, and to access the production of possible exotic states. At the top of the unitary rescattering peak (triangular logarithmic singularity), the reaction amplitude is on solid ground since it depends only on on-shell elementary amplitudes and on low momentum components of the nuclear wave function.

  18. Neutron Skin of Pb208 from Coherent Pion Photoproduction

    NASA Astrophysics Data System (ADS)

    Tarbert, C. M.; Watts, D. P.; Glazier, D. I.; Aguar, P.; Ahrens, J.; Annand, J. R. M.; Arends, H. J.; Beck, R.; Bekrenev, V.; Boillat, B.; Braghieri, A.; Branford, D.; Briscoe, W. J.; Brudvik, J.; Cherepnya, S.; Codling, R.; Downie, E. J.; Foehl, K.; Grabmayr, P.; Gregor, R.; Heid, E.; Hornidge, D.; Jahn, O.; Kashevarov, V. L.; Knezevic, A.; Kondratiev, R.; Korolija, M.; Kotulla, M.; Krambrich, D.; Krusche, B.; Lang, M.; Lisin, V.; Livingston, K.; Lugert, S.; MacGregor, I. J. D.; Manley, D. M.; Martinez, M.; McGeorge, J. C.; Mekterovic, D.; Metag, V.; Nefkens, B. M. K.; Nikolaev, A.; Novotny, R.; Owens, R. O.; Pedroni, P.; Polonski, A.; Prakhov, S. N.; Price, J. W.; Rosner, G.; Rost, M.; Rostomyan, T.; Schadmand, S.; Schumann, S.; Sober, D.; Starostin, A.; Supek, I.; Thomas, A.; Unverzagt, M.; Walcher, Th.; Zana, L.; Zehr, F.; Crystal Ball at MAMI; A2 Collaboration

    2014-06-01

    Information on the size and shape of the neutron skin on Pb208 is extracted from coherent pion photoproduction cross sections measured using the Crystal Ball detector together with the Glasgow tagger at the MAMI electron beam facility. On exploitation of an interpolated fit of a theoretical model to the measured cross sections, the half-height radius and diffuseness of the neutron distribution are found to be cn=6.70±0.03(stat.) fm and an=0.55±0.01(stat.)-0.03+0.02(sys.) fm, respectively, corresponding to a neutron skin thickness Δrnp=0.15±0.03(stat.)-0.03+0.01(sys.) fm. The results give the first successful extraction of a neutron skin thickness with an electromagnetic probe and indicate that the skin of Pb208 has a halo character. The measurement provides valuable new constraints on both the structure of nuclei and the equation of state for neutron-rich matter.

  19. In vitro residual anti-bacterial activity of difloxacin, sarafloxacin and their photoproducts after photolysis in water.

    PubMed

    Kusari, Souvik; Prabhakaran, Deivasigamani; Lamshöft, Marc; Spiteller, Michael

    2009-10-01

    Fluoroquinolones like difloxacin (DIF) and sarafloxacin (SARA) are adsorbed in soil and enter the aquatic environment wherein they are subjected to photolytic degradation. To evaluate the fate of DIF and SARA, their photolysis was performed in water under stimulated natural sunlight conditions. DIF primarily degrades to SARA. On prolonged photodegradation, seven photoproducts were elucidated by HR-LC-MS/MS, three of which were entirely novel. The residual anti-bacterial activities of DIF, SARA and their photoproducts were studied against a group of pathogenic strains. DIF and SARA revealed potency against both gram-positive and -negative bacteria. The photoproducts also exhibited varying degrees of efficacies against the tested bacteria. Even without isolating the individual photoproducts, their impact on the aquatic environment could be assessed. Therefore, the present results call for prudence in estimating the fate of these compounds in water and in avoiding emergence of resistance in bacteria caused by the photoproducts of DIF and SARA. PMID:19473738

  20. phi-meson photoproduction on Hydrogen in the neutral decay mode

    SciTech Connect

    Seraydaryan, Helena; Amaryan, Moscov J.; Gavalian, Gagik; Baghdasaryan, Hovhannes A.; Weinstein, Larry

    2014-05-01

    We report the first measurement of the photoproduction cross section of the $\\phi$ meson in its neutral decay mode in the reaction $\\gamma p \\to p\\phi(K_SK_L)$. The experiment was performed with a tagged photon beam of energy $1.6 \\le E_\\gamma \\le 3.6$ GeV incident on a liquid hydrogen target of the CLAS spectrometer at the Thomas Jefferson National Accelerator Facility. The $p \\phi$ final state is identified via reconstruction of $K_S$ in the invariant mass of two oppositely charged pions and by requiring the missing particle in the reaction $\\gamma p \\to p K_S X$ to be $K_L$. The presented results significantly enlarge the existing data on $\\phi$-photoproduction. These data, combined with the data from the charged decay mode, will help to constrain different mechanisms of $\\phi$ photoproduction.

  1. Double and single pion photoproduction within a dynamical coupled-channels model

    DOE PAGESBeta

    Hiroyuki Kamano; Julia-Diaz, Bruno; Lee, T. -S. H.; Matsuyama, Akihiko; Sato, Toru

    2009-12-16

    Within a dynamical coupled-channels model which has already been fixed from analyzing the data of the πN → πN and γN → πN reactions, we present the predicted double pion photoproduction cross sections up to the second resonance region, W < 1.7 GeV. The roles played by the different mechanisms within our model in determining both the single and double pion photoproduction reactions are analyzed, focusing on the effects due to the direct γN → ππN mechanism, the interplay between the resonant and non-resonant amplitudes, and the coupled-channels effects. As a result, the model parameters which can be determined mostmore » effectively in the combined studies of both the single and double pion photoproduction data are identified for future studies.« less

  2. ϕ-meson photoproduction on hydrogen in the neutral decay mode

    NASA Astrophysics Data System (ADS)

    Seraydaryan, H.; Amaryan, M. J.; Gavalian, G.; Baghdasaryan, H.; Weinstein, L.; Adhikari, K. P.; Adikaram, D.; Aghasyan, M.; Anderson, M. D.; Pereira, S. Anefalos; Avakian, H.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Bennett, R. P.; Biselli, A. S.; Bono, J.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Bültmann, S.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Collins, P.; Contalbrigo, M.; Cortes, O.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dugger, M.; Dupre, R.; Fassi, L. El; Eugenio, P.; Fedotov, G.; Fegan, S.; Fersch, R.; Fleming, J. A.; Gevorgyan, N.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guler, N.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Heddle, D.; Hicks, K.; Ho, D.; Holtrop, M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Kim, A.; Kim, W.; Klein, F. J.; Koirala, S.; Kubarovsky, A.; Kubarovsky, V.; Kuhn, S. E.; Kuleshov, S. V.; Lewis, S.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Martinez, D.; Mayer, M.; McKinnon, B.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Moutarde, H.; Munevar, E.; Camacho, C. Munoz; Nadel-Turonski, P.; Nasseripour, R.; Niccolai, S.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Pappalardo, L. L.; Paremuzyan, R.; Park, K.; Park, S.; Pasyuk, E.; Phelps, E.; Phillips, J. J.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Protopopescu, D.; Puckett, A. J. R.; Rimal, D.; Ripani, M.; Ritchie, B. G.; Rizzo, A.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Sharabian, Y. G.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Stepanyan, S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Tang, W.; Taylor, C. E.; Tian, Ye; Tkachenko, S.; Ungaro, M.; Vineyard, M. F.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; CLAS Collaboration

    2014-05-01

    We report the first measurement of the photoproduction cross section of the ϕ meson in its neutral decay mode in the reaction γp →pϕ(KSKL). The experiment was performed with a tagged photon beam of energy 1.6≤Eγ≤3.6 GeV incident on a liquid hydrogen target of the CLAS spectrometer at the Thomas Jefferson National Accelerator Facility. The pϕ final state is identified via reconstruction of KS in the invariant mass of two oppositely charged pions and by requiring the missing particle in the reaction γp →pKSX to be KL. The presented results significantly enlarge the existing data on ϕ photoproduction. These data, combined with the data from the charged decay mode, will help to constrain different mechanisms of ϕ photoproduction.

  3. Photoproduction of neutral kaons on a liquid deuterium target in the threshold region

    SciTech Connect

    Tsukada, K.; Takahashi, T.; Watanabe, T.; Fujii, Y.; Futatsukawa, K.; Hashimoto, O.; Hirose, K.; Ito, K.; Kameoka, S.; Kanda, H.; Maeda, K.; Matsumura, A.; Miura, Y.; Miyase, H.; Nakamura, S. N.; Nomura, H.; Nonaka, K.; Osaka, T.; Okayasu, Y.; Tamura, H.

    2008-07-15

    The photoproduction process of neutral kaons on a liquid deuterium target is investigated near the threshold region, E{sub {gamma}}=0.8-1.1 GeV. K{sup 0} events are reconstructed from positive and negative pions, and differential cross sections are derived. Experimental momentum spectra are compared with those calculated in the spectator model using a realistic deuteron wave function. Elementary amplitudes as given by recent isobar models and a simple phenomenological model are used to study the effect of the new data on the angular behavior of the elementary cross section. The data favor a backward-peaked angular distribution of the elementary n({gamma},K{sup 0}){lambda} process, which provides additional constraints on current models of kaon photoproduction. The present study demonstrates that the n({gamma},K{sup 0}){lambda} reaction can provide key information on the mechanism of the photoproduction of strangeness.

  4. Cross-section measurement of charged-pion photoproduction from hydrogen and deuterium.

    PubMed

    Zhu, L Y; Arrington, J; Averett, T; Beise, E; Calarco, J; Chang, T; Chen, J P; Chudakov, E; Coman, M; Clasie, B; Crawford, C; Dieterich, S; Dohrmann, F; Dutta, D; Fissum, K; Frullani, S; Gao, H; Gilman, R; Glashausser, C; Gomez, J; Hafidi, K; Hansen, J-O; Higinbotham, D W; Holt, R J; De Jager, C W; Jiang, X; Kinney, E; Kramer, K; Kumbartzki, G; LeRose, J; Liyanage, N; Mack, D; Markowitz, P; McCormick, K; Meekins, D; Meziani, Z-E; Michaels, R; Mitchell, J; Nanda, S; Potterveld, D; Ransome, R; Reimer, P E; Reitz, B; Saha, A; Schulte, E C; Seely, J; Sirca, S; Strauch, S; Sulkosky, V; Vlahovic, B; Weinstein, L B; Wijesooriya, K; Williamson, C F; Wojtsekhowski, B; Xiang, H; Xiong, F; Xu, W; Zeng, J; Zheng, X

    2003-07-11

    We have measured the differential cross section for the gamman-->pi(-)p and gammap-->pi(+)n reactions at theta(c.m.)=90 degrees in the photon energy range from 1.1 to 5.5 GeV at Jefferson Lab (JLab). The data at E(gamma) greater, similar 3.3 GeV exhibit a global scaling behavior for both pi(-) and pi(+) photoproduction, consistent with the constituent counting rule and the existing pi(+) photoproduction data. Possible oscillations around the scaling value are suggested by these new data. The data show enhancement in the scaled cross section at a center-of-mass energy near 2.2 GeV. The cross section ratio of exclusive pi(-) to pi(+) photoproduction at high energy is consistent with the prediction based on one-hard-gluon-exchange diagrams. PMID:12906473

  5. Photoreactivation, Photoproduct Formation, and Deoxyribonucleic Acid State in Ultraviolet-Irradiated Sporulating Cultures of Bacillus cereus

    PubMed Central

    Baillie, Elizabeth; Germaine, G. R.; Murreli, W. G.; Ohye, D. F.

    1974-01-01

    Photoreactivation of ultraviolet-irradiated Bacillus cereus T declined markedly during the development of stage IV forespores. During ultraviolet irradiation of a culture containing early and late stage IV forespores, both vegetative- and spore-type photoproducts were formed. The formation of vegetative-type photoproducts (mainly thymine dimers) decreased to nearly half during late stage IV, remaining constant until lysis of the mother cells began, when it fell to zero. Spore-type photoproducts were first observed during late stage IV and increased with the increase in numbers of late stage IV forespores. The occurrence of spore-type photoproducts preceded the development of refractile forespores by about 1 h. At stage III the nuclear material occupied a central position, and the ribosomes were at the periphery of the forespore protoplast. During stage IV the deoxyribonucleic acid (DNA) occurred in a peripheral position, and bundles of fibers (“transition” DNA) could be seen. By stage V, all of the DNA appeared to be of the spore type and was peripheral, and the forespore protoplast center was packed with ribosomes. Forespore stages II, III, and IV were classified by light and electron microscopy. The curve for electron microscope classifications preceded that for light microscope classifications by approximately one stage. The formation of spore-type photoproducts preceded differentiation of DNA by about 1 h, the latter coinciding with the development of refractility. Spore-type photoproducts have been associated with DNA in the A state, and the progressive change of the forespore DNA into this state is discussed in relation to the spore differentiation process. Images PMID:4214215

  6. Sustainable Hydrogen Photoproduction by Phosphorus-Deprived Marine Green Microalgae Chlorella sp.

    PubMed Central

    Batyrova, Khorcheska; Gavrisheva, Anastasia; Ivanova, Elena; Liu, Jianguo; Tsygankov, Anatoly

    2015-01-01

    Previously it has been shown that green microalga Chlamydomonas reinhardtii is capable of prolonged H2 photoproduction when deprived of sulfur. In addition to sulfur deprivation (-S), sustained H2 photoproduction in C. reinhardtii cultures can be achieved under phosphorus-deprived (-P) conditions. Similar to sulfur deprivation, phosphorus deprivation limits O2 evolving activity in algal cells and causes other metabolic changes that are favorable for H2 photoproduction. Although significant advances in H2 photoproduction have recently been realized in fresh water microalgae, relatively few studies have focused on H2 production in marine green microalgae. In the present study phosphorus deprivation was applied for hydrogen production in marine green microalgae Chlorella sp., where sulfur deprivation is impossible due to a high concentration of sulfates in the sea water. Since resources of fresh water on earth are limited, the possibility of hydrogen production in seawater is more attractive. In order to achieve H2 photoproduction in P-deprived marine green microalgae Chlorella sp., the dilution approach was applied. Cultures diluted to about 0.5–1.8 mg Chl·L−1 in the beginning of P-deprivation were able to establish anaerobiosis, after the initial growth period, where cells utilize intracellular phosphorus, with subsequent transition to H2 photoproduction stage. It appears that marine microalgae during P-deprivation passed the same stages of adaptation as fresh water microalgae. The presence of inorganic carbon was essential for starch accumulation and subsequent hydrogen production by microalgae. The H2 accumulation was up to 40 mL H2 gas per 1iter of the culture, which is comparable to that obtained in P-deprived C. reinhardtii culture. PMID:25629229

  7. Sustainable hydrogen photoproduction by phosphorus-deprived marine green microalgae Chlorella sp.

    PubMed

    Batyrova, Khorcheska; Gavrisheva, Anastasia; Ivanova, Elena; Liu, Jianguo; Tsygankov, Anatoly

    2015-01-01

    Previously it has been shown that green microalga Chlamydomonas reinhardtii is capable of prolonged H2 photoproduction when deprived of sulfur. In addition to sulfur deprivation (-S), sustained H2 photoproduction in C. reinhardtii cultures can be achieved under phosphorus-deprived (-P) conditions. Similar to sulfur deprivation, phosphorus deprivation limits O2 evolving activity in algal cells and causes other metabolic changes that are favorable for H2 photoproduction. Although significant advances in H2 photoproduction have recently been realized in fresh water microalgae, relatively few studies have focused on H2 production in marine green microalgae. In the present study phosphorus deprivation was applied for hydrogen production in marine green microalgae Chlorella sp., where sulfur deprivation is impossible due to a high concentration of sulfates in the sea water. Since resources of fresh water on earth are limited, the possibility of hydrogen production in seawater is more attractive. In order to achieve H2 photoproduction in P-deprived marine green microalgae Chlorella sp., the dilution approach was applied. Cultures diluted to about 0.5-1.8 mg Chl·L-1 in the beginning of P-deprivation were able to establish anaerobiosis, after the initial growth period, where cells utilize intracellular phosphorus, with subsequent transition to H2 photoproduction stage. It appears that marine microalgae during P-deprivation passed the same stages of adaptation as fresh water microalgae. The presence of inorganic carbon was essential for starch accumulation and subsequent hydrogen production by microalgae. The H2 accumulation was up to 40 mL H2 gas per 1iter of the culture, which is comparable to that obtained in P-deprived C. reinhardtii culture. PMID:25629229

  8. Helicity Amplitudes for Photoproduction of Baryons with J = 1/2 and JP = 3/2+

    NASA Astrophysics Data System (ADS)

    Liu, Lei-Hua

    2015-12-01

    We derive the separate helicity amplitudes using the partial wave analysis in the process of pseudo-scalar meson photoproduction. For JP = 3/2+, we find the amplitude is model independent. According to parity conservation, the general amplitude in the case of JP = 1/2- is obtained. We prove this general amplitude corresponds to the situation of λ = -1 when adopting the circular polarization. Finally, the formulas of scattering amplitudes involving the meson photoproduction with JP = 3/2+ are obtained from the chiral quark model. Supported by the Chinese Scholarship Council (CSC)

  9. Determination of E and G Observables in n Photoproduction on the CLAS Frozen Spin Target (FROST)

    SciTech Connect

    Senderovich, Igor; Morrison, Brian T.; Dugger, Michael R.; Ritchie, Barry G.; Tucker, Ross J.

    2014-01-01

    Polarization observables are vital for disentangling overlapping resonances in the baryon spectrum. Extensive data have been collected at Jefferson Lab in Hall B with circularly and linearly polarized tagged photon beam incident on longitudinally polarized protons provided by the Frozen Spin Target (FROST). The focus of the described work is on η photoproduction, which acts as an "isospin filter", isolating the N*(I = 1/2) resonances. Preliminary results for the double-polarization observables E and G are presented. There are currently no data on these in the world database for η photoproduction.

  10. Studying the Pc(4450 ) resonance in J /ψ photoproduction off protons

    NASA Astrophysics Data System (ADS)

    Blin, A. N. Hiller; Fernández-Ramírez, C.; Jackura, A.; Mathieu, V.; Mokeev, V. I.; Pilloni, A.; Szczepaniak, A. P.; Joint Physics Analysis Center

    2016-08-01

    A resonancelike structure, the Pc(4450 ), has recently been observed in the J /ψ p spectrum by the LHCb Collaboration. We discuss the feasibility of detecting this structure in J /ψ photoproduction in the CLAS12 experiment at JLab. We present a first estimate of the upper limit for the branching ratio of the Pc(4450 ) to J /ψ p . Our estimates, which take into account the experimental resolution effects, predict that it will be possible to observe a sizable cross section close to the J /ψ production threshold and shed light on the Pc(4450 ) resonance in the future photoproduction measurements.

  11. Measurement of Beauty and Charm Photoproduction at H1 using inclusive lifetime tagging

    SciTech Connect

    Finke, L.

    2005-10-06

    A measurement of the charm and beauty photoproduction cross sections at the ep collider HERA is presented. The lifetime signature of c and b-flavoured hadrons is exploited to determine the fractions of events in the sample containing charm or beauty. Differential cross sections as a function of the jet transverse momentum, the rapidity and x{sub {gamma}}{sup obs} are measured in the photoproduction region Q2 < 1 GeV2, with inelasticity 0.15 < y < 0.8. The results are compared with calculations in next-to-leading order perturbative QCD and Monte Carlo models as implemented in PYTHIA and CASCADE.

  12. Preliminary results for the helicity asymmetry E for eta photoproduction on the proton

    SciTech Connect

    B. T. Morrison, M. Dugger, B. G. Ritchie, CLAS Collaboration

    2012-04-01

    Polarization observables are an important tool for clarifying the nucleon resonance spectrum. No previous measurements for double polarization asymmetries have been published for eta photoproduction. Double polarization measurements have been made at Jefferson Lab using a polarized photon beam and protons in a polarized frozen spin target (FROST). Data were taken during the first running period of FROST using the CLAS detector with photon energies from 0.33 to 2.35 GeV. Preliminary results for the E polarization observable for eta meson photoproduction from the proton at threshold and above, along with comparisons to several theoretical predictions are presented.

  13. CLAS+FROST: new generation of photoproduction experiments at Jefferson Lab

    SciTech Connect

    Eugene Pasyuk

    2009-12-01

    A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to baryon spectroscopy. Photoproduction experiments are essential part of this program. CEBAF Large Acceptance Spectrometer (CLAS) and availability of circularly and linearly polarized tagged photon beams provide unique conditions for this type of experiments. Recent addition of the Frozen Spin Target (FROST) gives a remarkable opportunity to measure double and triple polarization observables for different pseudo-scalar meson photoproduction processes. For the first time, a complete or nearly complete experiment becomes possible and will allow model independent extraction of the reaction amplitude. An overview of the experiment and its current status is presented.

  14. Study of the Two-pion Photoproduction on the Deuteron

    SciTech Connect

    Graham, Lewis P.

    2012-12-01

    Understanding the structure of baryons in terms of the fundamental interaction of the constituent quarks and gluons is one of the primary challenges in strong interaction physics. This interaction is governed by Quantum Chromodynamics (QCD), which is a theory for understanding the dynamics of strong. QCD displays the asymptotic freedom of hadrons at very short distances and also the confinement of quarks and gluons inside hadrons. However, solutions of this QCD theory in the non-perturbative domain of the interaction are extremely difficult to achieve, mainly because confinement happens on the hadronic scale on which the coupling constant is large and prevents any perturbative approach. Thus leaving us with strategies such as lattice QCD or formulating QCD sum rules to get around this problem. In exclusive hadron production the yN interaction is recognized for being a powerful method for investigating hadrons and the mysteries that still exist within the strong interaction. From reactions with the nucleon, the strong interaction can be investigated through the transition amplitudes to the N and Delta resonances. More specifically, if an electromagnetic interaction is well known then the intermediate resonance states may be evaluated through meson photoproduction. To gain more detailed insight into this interaction, we look to probe the baryon structure of the nucleon and the photo-excited resonance decays through photon scattering off a deuteron producing two pions in the final state. This photoproduction process off the deuteron will be used to investigate known baryon resonances in the two pion channel. The two pion final state will be investigated for unraveling new information into the photo-coupling strengths. We want to explore final state interactions, search for properties of known resonances, and to explore the possibility of seeing missing states that are predicted by quark models but have not yet been found experimentally. Using the CEBAF Large

  15. Photoproduction of π0-pairs off protons and off neutrons

    NASA Astrophysics Data System (ADS)

    Dieterle, M.; Oberle, M.; Ahrens, J.; Annand, J. R. M.; Arends, H. J.; Bantawa, K.; Bartolome, P. A.; Beck, R.; Bekrenev, V.; Berghäuser, H.; Braghieri, A.; Branford, D.; Briscoe, W. J.; Brudvik, J.; Cherepnya, S.; Costanza, S.; Demissie, B.; Downie, E. J.; Drexler, P.; Fil'kov, L. V.; Fix, A.; Garni, S.; Glazier, D. I.; Hamilton, D.; Heid, E.; Hornidge, D.; Howdle, D.; Huber, G. M.; Jahn, O.; Jude, T. C.; Käser, A.; Kashevarov, V. L.; Keshelashvili, I.; Kondratiev, R.; Korolija, M.; Krusche, B.; Lisin, V.; Livingston, K.; MacGregor, I. J. D.; Maghrbi, Y.; Mancell, J.; Manley, D. M.; Marinides, Z.; McGeorge, J. C.; McNicoll, E.; Mekterovic, D.; Metag, V.; Micanovic, S.; Middleton, D. G.; Mushkarenkov, A.; Nikolaev, A.; Novotny, R.; Ostrick, M.; Otte, P.; Oussena, B.; Pedroni, P.; Pheron, F.; Polonski, A.; Prakhov, S.; Robinson, J.; Rostomyan, T.; Schumann, S.; Sikora, M. H.; Sober, D. I.; Starostin, A.; Strub, Th.; Supek, I.; Thiel, M.; Thomas, A.; Unverzagt, M.; Walford, N. K.; Watts, D. P.; Werthmüller, D.; Witthauer, L.

    2015-11-01

    Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of π0π0 pairs off free protons and off nucleons bound in the deuteron. The experiments were performed at the MAMI accelerator facility in Mainz using the Glasgow photon tagging spectrometer and the Crystal Ball/TAPS detector. The accelerator delivered electron beams of 1508 and 1557MeV, which produced bremsstrahlung in thin radiator foils. The tagged photon beam covered energies up to 1400MeV. The data from the free proton target are in good agreement with previous measurements and were only used to test the analysis procedures. The results for differential cross sections (angular distributions and invariant-mass distributions) for free and quasi-free protons are almost identical in shape, but differ in absolute magnitude up to 15%. Thus, moderate final-state interaction effects are present. The data for quasi-free neutrons are similar to the proton data in the second resonance region (final-state invariant masses up to ≈ 1550 MeV), where both reactions are dominated by the N(1520)3/2- → Δ(1232)3/2+π decay. At higher energies, angular and invariant-mass distributions are different. A simple analysis of the shapes of the invariant-mass distributions in the third resonance region is consistent with strong contributions of an N^{star}→ Nσ decay for the proton, while the reaction is dominated by a sequential decay via a Δπ intermediate state for the neutron. The data are compared to predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled-channel analysis.

  16. Photoproduction of the f1(1285 ) meson

    NASA Astrophysics Data System (ADS)

    Dickson, R.; Schumacher, R. A.; Adhikari, K. P.; Akbar, Z.; Amaryan, M. J.; Anefalos Pereira, S.; Badui, R. A.; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A.; Boiarinov, S.; Briscoe, W. J.; Burkert, V. D.; Cao, T.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Chetry, T.; Ciullo, G.; Colaneri, L.; Cole, P. L.; Compton, N.; Contalbrigo, M.; Cortes, O.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dugger, M.; Dupre, R.; El Alaoui, A.; El Fassi, L.; Eugenio, P.; Fanchini, E.; Fedotov, G.; Filippi, A.; Fleming, J. A.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Gothe, R. W.; Griffioen, K. A.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Holtrop, M.; Hicks, K.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jiang, H.; Jo, H. S.; Joosten, S.; Keller, D.; Khachatryan, G.; Khandaker, M.; Kim, A.; Kim, W.; Klein, F. J.; Kubarovsky, V.; Kuleshov, S. V.; Lanza, L.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Mattione, P.; McKinnon, B.; Meyer, C. A.; Mirazita, M.; Markov, N.; Mokeev, V.; Moriya, K.; Munevar, E.; Murdoch, G.; Nadel-Turonski, P.; Net, L. A.; Ni, A.; Osipenko, M.; Ostrovidov, A. I.; Park, K.; Pasyuk, E.; Phelps, W.; Pisano, S.; Pogorelko, O.; Price, J. W.; Prok, Y.; Puckett, A. J. R.; Raue, B. A.; Ripani, M.; Rizzo, A.; Rosner, G.; Roy, P.; Salgado, C.; Seder, E.; Sharabian, Y. G.; Skorodumina, Iu.; Smith, E. S.; Smith, G. D.; Sober, D.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Strakovsky, I. I.; Stankovic, I.; Strauch, S.; Sytnik, V.; Taiuti, M.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Weygand, D.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zonta, I.; CLAS Collaboration

    2016-06-01

    The f1(1285 ) meson with mass 1281.0 ±0.8 MeV/c2 and width 18.4 ±1.4 MeV (full width at half maximum) was measured for the first time in photoproduction from a proton target using CLAS at Jefferson Lab. Differential cross sections were obtained via the η π+π-,K+K¯0π- , and K-K0π+ decay channels from threshold up to a center-of-mass energy of 2.8 GeV. The mass, width, and an amplitude analysis of the η π+π- final-state Dalitz distribution are consistent with the axial-vector JP=1+ f1(1285 ) identity, rather than the pseudoscalar 0- η (1295 ) . The production mechanism is more consistent with s -channel decay of a high-mass N* state and not with t -channel meson exchange. Decays to η π π go dominantly via the intermediate a0±(980 ) π∓ states, with the branching ratio Γ [a0π (noK ¯K )] /Γ [η π π (all)] =0.74 ±0.09 . The branching ratios Γ (K K ¯π ) /Γ (η π π ) =0.216 ±0.033 and Γ (γ ρ0) /Γ (η π π ) =0.047 ±0.018 were also obtained. The first is in agreement with previous data for the f1(1285 ) , while the latter is lower than the world average.

  17. Survey of selected seaweeds for simultaneous photoproduction of hydrogen and oxygen

    SciTech Connect

    Greenbaum, E.; Ramus, J.

    1983-03-01

    Then seaweed species were surveyed for simultaneous photoevolution of hydrogen and oxygen. In an attempt to induce hydrogenase activity (as measured by hydrogen photoproduction) the seaweeds were maintained under anaerobiosis in CO/sub 2/-free seawater for varying lengths of time. Although oxygen evolution was observed in every alga studied, hydrogen evolution was not observed. One conclusion of this research is that, in contrast to the microscopic algae, there is not a single example of a macroscopic alga for which the photoevolution of hydrogen has been observed, in spite of the fact that there are now at least nine macroscopic algal species known for which hydrogenase activity has been reported (either by dark hydrogen evolution or light-activated hydrogen uptake). These results are in conflict with the conventional view that algal hydrogenase can catalyze a multiplicity of reactions, one of which is the photoproduction of molecular hydrogen. Two possible explanations for the lack of hydrogen photoproduction in macroscopic algae are presented. It is postulated that electron acceptors other than carbon dioxide can take up reducing equivalents from Photosystem I to the measurable exclusion of hydrogen photoproduction. Alternatively, the hydrogenase system in macroscopic algae may be primarily a hydrogen-uptake system with respect to light-activated reactions. A simple kinetic argument based on recent measurements of the photosynthetic turnover times of simultaneous light-activated hydrogen and oxygen production is presented that supports the second explanation. 25 references, 3 figures, 1 table.

  18. Photoproduction of an isovector. rho. pi. state at 1775 MeV

    SciTech Connect

    Condo, G.T.; Handler, T.; Shimony, J.; Abe, K.; Armenteros, R.; Austern, M.; Bacon, T.C.; Ballam, J.; Bingham, H.H.; Brau, J.E.; Braune, K.; Brick, D.; Bugg, W.M.; Butler, J.M.; Cameron, W.; Cohn, H.O.; Colley, D.C.; Dado, S.; Diamond, R.; Dingus, P.; Erickson, R.; Falicov, A.; Field, R.C.; Fortney, L.R.; Franek, B.; Fujiwara, N.; Glanzman, T.; Godfrey, I.M.; Goldberg, J.J.; Goshaw, A.T.; Hall, G.; Hancock, E.R.; Hargis, H.J.; Hart, E.L.; Harwin, M.J.; Hasegawa, K.; Hulsizer, R.I.; Jobes, M.; Kafka, T.; Kalmus, G.E.; Kelsey, D.P.; Kent, J.; Kitagaki, T.; Levy, A.; Lucas, P.W.; Mann, W.A.; McCrory, E.S.; Merenyi, R.; Milburn, R.; Milstene, C.; Moffeit, K.C.; Napier, A.; Noguchi, S.; O'Dell, V.R.; O'Neale, S.; Palounek, A.P.T.; Pless, I.A.; Rankin, P.; Robertson, W.J.; Sagawa, H.; Sato, T.; Schneps, J.; Sewell, S.J.; Shank, J.; Shapiro, A.M.; Sugahara, R.; Takahashi, K.; Tamai, K.; Tanaka, S.; Tether, S.; Waide, D.A.; Walker, W.D.; White, S.L.; Widgoff, M.; Wilkins, C.G.; Wolbers, S.; Wo

    1991-05-01

    Evidence is presented for the charge-exchange photoproduction, in two distinct reactions, of an isovector {rho}{pi} state of mass {similar to}1775 MeV. Results of an analysis of the decay-angular distributions are also presented, from which it is concluded that {ital J}{sup {ital P}}=1{sup {minus}}, 2{sup {minus}}, or 3{sup +}.

  19. Eta photoproduction in a combined analysis of pion- and photon-induced reactions

    SciTech Connect

    Ronchen, D.; Doring, M.; Haberzettl, H.; Haidenbauer, J.; MeiBner, U. -G.; Nakayama, K.

    2015-06-25

    The $\\eta N$ final state is isospin-selective and thus provides access to the spectrum of excited nucleons without being affected by excited $\\Delta$ states. To this end, the world database on eta photoproduction off the proton up to a center-of-mass energy of $E\\sim 2.3$ GeV is analyzed, including data on differential cross sections, and single and double polarization observables. The resonance spectrum and its properties are determined in a combined analysis of eta and pion photoproduction off the proton together with the reactions $\\pi N\\to \\pi N$, $\\eta N$, $K\\Lambda$ and $K\\Sigma$. For the analysis, the so-called J\\"ulich coupled-channel framework is used, incorporating unitarity, analyticity, and effective three-body channels. Parameters tied to photoproduction and hadronic interactions are varied simultaneously. Furthermore, the influence of recent MAMI $T$ and $F$ asymmetry data on the eta photoproduction amplitude is discussed in detail.

  20. Eta photoproduction in a combined analysis of pion- and photon-induced reactions

    DOE PAGESBeta

    Ronchen, D.; Doring, M.; Haberzettl, H.; Haidenbauer, J.; MeiBner, U. -G.; Nakayama, K.

    2015-06-25

    Themore » $$\\eta N$$ final state is isospin-selective and thus provides access to the spectrum of excited nucleons without being affected by excited $$\\Delta$$ states. To this end, the world database on eta photoproduction off the proton up to a center-of-mass energy of $$E\\sim 2.3$$ GeV is analyzed, including data on differential cross sections, and single and double polarization observables. resonance spectrum and its properties are determined in a combined analysis of eta and pion photoproduction off the proton together with the reactions $$\\pi N\\to \\pi N$$, $$\\eta N$$, $$K\\Lambda$$ and $$K\\Sigma$$. For the analysis, the so-called J\\"ulich coupled-channel framework is used, incorporating unitarity, analyticity, and effective three-body channels. Parameters tied to photoproduction and hadronic interactions are varied simultaneously. Furthermore, the influence of recent MAMI $T$ and $F$ asymmetry data on the eta photoproduction amplitude is discussed in detail.« less

  1. Rho0 Photoproduction in Ultra-Peripheral Relativistic Heavy Ion Collisions with STAR

    SciTech Connect

    STAR Coll

    2007-12-20

    Photoproduction reactions occur when the electromagnetic field of a relativistic heavy ion interacts with another heavy ion. The STAR collaboration presents a measurement of {rho}{sup 0} and direct {pi}{sup +}{pi}{sup -} photoproduction in ultra-peripheral relativistic heavy ion collisions at {radical}s{sub NN} = 200 GeV. We observe both exclusive photoproduction and photoproduction accompanied by mutual Coulomb excitation. We find a coherent cross-section of {sigma}(AuAu {yields} Au*Au* {rho}{sup 0}) = 530 {+-} 19 (stat.) {+-} 57 (syst.) mb, in accord with theoretical calculations based on a Glauber approach, but considerably below the predictions of a color dipole model. The {rho}{sup 0} transverse momentum spectrum (p{sub T}{sup 2}) is fit by a double exponential curve including both coherent and incoherent coupling to the target nucleus; we find {sigma}{sub inc}/{sigma}{sub coh} = 0.29 {+-} 0.03 (stat.) {+-} 0.08 (syst.). The ratio of direct {pi}{sup +}{pi}{sup -} production is comparable to that observed in {gamma}p collisions at HERA, and appears to be independent of photon energy. Finally, the measured {rho}{sup 0} spin helicity matrix elements agree within errors with the expected s-channel helicity conservation.

  2. QCD investigation of polarization effects in the inclusive photoproduction of SUSY particles

    SciTech Connect

    Sadykhov, F.S.; Akhmedov, A.I.

    1995-10-01

    Polarization effects in the inclusive photoproduction of SUSY particles is investigated in QCD. Two-spin asymmetries are studied as functions of the transverse momentum, the effective mass of scalar pairs, and the scattering angle. It is shown that information about the masses of scalar quarks can be deduced from the analysis of spin asymmetry. 4 refs., 4 figs.

  3. Abiotic ammonification and gross ammonium photoproduction in the upwelling system off central Chile (36° S)

    NASA Astrophysics Data System (ADS)

    Rain-Franco, A.; Muñoz, C.; Fernandez, C.

    2012-12-01

    We investigated the production of ammonium via photodegradation of dissolved organic matter (DOM) in the coastal upwelling system off central Chile (36° S). Photoammonification experiments were carried out using exudates obtained from representative diatom species (Chaetoceros muelleri and Thalassiosira minuscule) and natural marine DOM under simulated solar radiation conditions. Additionally, we evaluated the use of photoproduced ammonium by natural microbial communities and separated ammonium oxidizing archaea and bacteria by using GC-7 as an inhibitor of the archaeal community. We found photoammonification operating at two levels: via the transformation of DOM by UV radiation (abiotic ammonification) and via the simultaneous occurrence of abiotic phototransformation and biological remineralization of DOM into NH4+ (referred as gross photoproduction of NH4+). The maximum rates of abiotic ammonification reached 0.057 μmol L-1 h-1, whereas maximum rates of gross photoproduction reached 0.746 μmol L-1 h-1. Our results also suggest that ammonium oxidizing archaea could dominate the biotic remineralization induced by photodegradation of organic matter and consequently play an important role in the local N cycle. Abiotic ammonium photoproduction in coastal upwelling systems could support between 7 and 50% of the spring-summer phytoplankton NH4+ demand. Surprisingly, gross ammonium photoproduction (remineralization induced by abiotic ammonification) might support 50 to 180% of spring-summer phytoplankton NH4+ assimilation.

  4. Helicity Asymmetry Measurement for pi0 Photoproduction with FROST

    SciTech Connect

    Iwamoto, Hideko

    2011-08-15

    This thesis reports on the first helicity asymmetry measurement for single neutral pion photoproduction using the CLAS detector in Hall B at the Thomas Jefferson National Accelerator Facility (JLab). This measurement used longitudinally polarized protons and circularly polarized photons at energies between 350 MeV and 2400 MeV. The experimental results are compared to three available model calculations.

  5. Beam asymmetry {Sigma} measurements of {pi}{sup -} photoproduction on neutrons

    SciTech Connect

    Mandaglio, G.; Manganaro, M.; Giardina, G.; Mammoliti, F.; Bellini, V.; Giusa, A.; Randieri, C.; Russo, G.; Sperduto, M. L.; Bocquet, J. P.; Lleres, A.; Rebreyend, D.; D'Angelo, A.; Fantini, A.; Franco, D.; Schaerf, C.; Vegna, V.

    2010-10-15

    The -beam asymmetry {Sigma} in the photoproduction of negative pions on quasi-free neutrons in a deuterium target was measured at the Grenoble Anneau Accelerateur Laser in the energy interval 700-1500 MeV and over a wide angular range, using polarized and tagged photons. Results are compared with recent partial-wave analyses.

  6. The γn -->K0 Λ photoproduction studied with an electromagnetic calorimeter complex FOREST

    NASA Astrophysics Data System (ADS)

    Tsuchikawa, Yusuke; Hashimoto, Ryo; He, Qinghua; Ishikawa, Takatsugu; Masumoto, Shinichi; Miyabe, Manabu; Muramatsu, Norihito; Shimizu, Hajime; Tajima, Yasuhisa; Yamazaki, Hirohito; Yamazaki, Ryuji; Forest Collaboration

    2014-09-01

    Nucleon resonance have been experimentally studied by means of meson production reactions for understanding low-energy scale QCD. Photoproduction is one of the useful tools to reveal properties of excited nucleons. Indeed, the π and η photoproduction reactions have been intensively investigated until now. Kaon photoproduction is the best probe to study highly excited nucleons, which hardly couple to πN and ηN . Simultaneous K0 Λ production is more advantageous than K+ Λ production which is reported by many experimental groups. It is because the kaon exchange is forbidden in the K0 Λ photoproduction, and because Born term contribution is small. The γd --> (K0 Λ) p --> (π0π0 pπ-) p reaction is experimentally investigated with an electromagnetic calorimeter FOREST at Research Center for Electron Photon Science, Tohoku University. The K0 and Λ particles are clearly observed in π0π0 and π- p invariant mass distributions. We will present the current status of the exclusive γn -->K0 Λ reaction.

  7. A quantum chemical perspective on (6-4) photolesion repair by photolyases.

    PubMed

    Dreuw, Andreas; Faraji, Shirin

    2013-12-14

    (6-4)-Photolyases are fascinating enzymes which repair (6-4)-DNA photolesions utilizing light themselves. It is well known that upon initial photo-excitation of an antenna pigment an electron is transferred from an adjacent FADH(-) cofactor to the photolesion initiating repair, i.e. restoration of the original undamaged DNA bases. Concerning the molecular details of this amazing repair mechanism, the early steps of energy transfer and catalytic electron generation are well understood, the terminal repair mechanism, however, is still a matter of ongoing debate. In this perspective article, recent results of quantum chemical investigations are presented, and their meaning for the repair mechanism under natural conditions is outlined. Consequences of natural light conditions, temperature and thermal equilibration are highlighted when issues like the initial protonation state of the relevant histidines and the lesion, or the direction of electron transfer are discussed. PMID:24145385

  8. Dynamically Complex [6+4] and [4+2] Cycloadditions in the Biosynthesis of Spinosyn A.

    PubMed

    Patel, Ashay; Chen, Zhuo; Yang, Zhongyue; Gutiérrez, Osvaldo; Liu, Hung-Wen; Houk, K N; Singleton, Daniel A

    2016-03-23

    SpnF, an enzyme involved in the biosynthesis of spinosyn A, catalyzes a transannular Diels-Alder reaction. Quantum mechanical computations and dynamic simulations now show that this cycloaddition is not well described as either a concerted or stepwise process, and dynamical effects influence the identity and timing of bond formation. The transition state for the reaction is ambimodal and leads directly to both the observed Diels-Alder and an unobserved [6+4] cycloadduct. The potential energy surface bifurcates and the cycloadditions occur by dynamically stepwise modes featuring an "entropic intermediate". A rapid Cope rearrangement converts the [6+4] adduct into the observed [4+2] adduct. Control of nonstatistical dynamical effects may serve as another way by which enzymes control reactions. PMID:26909570

  9. Sustained hydrogen photoproduction by Chlamydomonas reinhardtii: Effects of culture parameters.

    PubMed

    Kosourov, Sergey; Tsygankov, Anatoly; Seibert, Michael; Ghirardi, Maria L

    2002-06-30

    The green alga, Chlamydomonas reinhardtii, is capable of sustained H(2) photoproduction when grown under sulfur-deprived conditions. This phenomenon is a result of the partial deactivation of photosynthetic O(2)-evolution activity in response to sulfur deprivation. At these reduced rates of water-oxidation, oxidative respiration under continuous illumination can establish an anaerobic environment in the culture. After 10-15 hours of anaerobiosis, sulfur-deprived algal cells induce a reversible hydrogenase and start to evolve H(2) gas in the light. Using a computer-monitored photobioreactor system, we investigated the behavior of sulfur-deprived algae and found that: (1) the cultures transition through five consecutive phases: an aerobic phase, an O(2)-consumption phase, an anaerobic phase, a H(2)-production phase and a termination phase; (2) synchronization of cell division during pre-growth with 14:10 h light:dark cycles leads to earlier establishment of anaerobiosis in the cultures and to earlier onset of the H(2)-production phase; (3) re-addition of small quantities of sulfate (12.5-50 microM MgSO(4), final concentration) to either synchronized or unsynchronized cell suspensions results in an initial increase in culture density, a higher initial specific rate of H(2) production, an increase in the length of the H(2)-production phase, and an increase in the total amount of H(2) produced; and (4) increases in the culture optical density in the presence of 50 microM sulfate result in a decrease in the initial specific rates of H(2) production and in an earlier start of the H(2)-production phase with unsynchronized cells. We suggest that the effects of sulfur re-addition on H(2) production, up to an optimal concentration, are due to an increase in the residual water-oxidation activity of the algal cells. We also demonstrate that, in principle, cells synchronized by growth under light:dark cycles can be used in an outdoor H(2)-production system without loss of

  10. Single Chirality (6,4) Single-Walled Carbon Nanotubes for Fluorescence Imaging with Silicon Detectors.

    PubMed

    Antaris, Alexander L; Yaghi, Omar K; Hong, Guosong; Diao, Shuo; Zhang, Bo; Yang, Jiang; Chew, Leila; Dai, Hongjie

    2015-12-16

    Postsynthetic single-walled carbon nanotube (SWCNT) sorting methods such as density gradient ultracentrifugation, gel chromatography, and electrophoresis have all been inspired by established biochemistry separation techniques designed to separate subcellular components. Biochemistry separation techniques have been refined to the degree that parameters such as pH, salt concentration, and temperature are necessary for a successful separation, yet these conditions are only now being applied to SWCNT separation methodologies. Slight changes in pH produce radically different behaviors of SWCNTs inside a density gradient, allowing for the facile separation of ultrahigh purity (6,4) SWCNTs from as-synthesized carbon nanotubes. The (6,4) SWCNTs are novel fluorophores emitting below ≈900 nm and can be easily detected with conventional silicon-based charge-coupled device detectors without the need for specialized InGaAs cameras. The (6,4) SWCNTs are used to demonstrate their potential as a clinically relevant NIR-I fluorescence stain for the immunohistochemical staining of cells and cancer tissue sections displaying high endothelial growth factor receptor levels. PMID:26529611

  11. SKW 6.4 cell differentiation induced by interleukin 6 is stimulated by butyrate.

    PubMed

    Kawamoto, T; Gohda, E; Iji, H; Fujiwara, M; Yamamoto, I

    1998-08-01

    We investigated if sodium butyrate (NaBu), an inhibitor of histone deacetylase, and its analogs modulate cytokine-induced differentiation of the human B cell line SKW 6.4 transformed by the Epstein-Barr virus. NaBu markedly enhanced interleukin (IL)-6-induced IgM production with an accompanying increase in the level of histone H4 acetylation and augmented IgM production induced by IL-4 and phorbol 12-myristate 13-acetate. From both the enhancing effect of cell differentiation and the effect of inducing histone hyperacetylation in SKW 6.4 cells, other histone deacetylase inhibitors and NaBu analogs were divided into three groups: those that increased both IL-6-induced antibody production and histone acetylation, those that caused histone hyperacetylation, but failed to induce the differentiation, and those that were ineffective at inducing either activity. No agent that enhanced IgM production without inducing histone hyperacetylation was found among the inhibitors and analogs we tested. These results suggest that the increase in the histone acetylation is necessary, but it is insufficient to augment differentiation of SKW 6.4 cells. Thus another activity of NaBu in addition to the inhibition of histone deacetylase may be involved in promoting IL-6-induced differentiation. Our results also suggest that fatty acids that have a straight chain of four carbon atoms or are branched with four and five carbon atoms, which contain no hydrophilic substituents, or those with similar structures, show this other activity. PMID:9826026

  12. Energetics of Photoinduced Charge Migration within the Tryptophan Tetrad of an Animal (6-4) Photolyase.

    PubMed

    Cailliez, Fabien; Müller, Pavel; Firmino, Thiago; Pernot, Pascal; de la Lande, Aurélien

    2016-02-17

    Cryptochromes and photolyases are flavoproteins that undergo cascades of electron/hole transfers after excitation of the flavin cofactor. It was recently discovered that animal (6-4) photolyases, as well as animal cryptochromes, feature a chain of four tryptophan residues, while other members of the family contain merely a tryptophan triad. Transient absorption spectroscopy measurements on Xenopus laevis (6-4) photolyase have shown that the fourth residue is effectively involved in photoreduction but at the same time could not unequivocally ascertain the final redox state of this residue. In this article, polarizable molecular dynamics simulations and constrained density functional theory calculations are carried out to reveal the energetics of charge migration along the tryptophan tetrad. Migration toward the fourth tryptophan is found to be thermodynamically favorable. Electron transfer mechanisms are sought either through an incoherent hopping mechanism or through a multiple sites tunneling process. The Jortner-Bixon formulation of electron transfer (ET) theory is employed to characterize the hopping mechanism. The interplay between electron transfer and relaxation of protein and solvent is analyzed in detail. Our simulations confirm that ET in (6-4) photolyase proceeds out of equilibrium. Multiple site tunneling is modeled with the recently proposed flickering resonance mechanism. Given the position of energy levels and the distribution of electronic coupling values, tunneling over three tryptophan residues may become competitive in some cases, although a hopping mechanism is likely to be the dominant channel. For both reactive channels, computed rates are very sensitive to the starting protein configuration, suggesting that both can take place and eventually be mixed, depending on the state of the system when photoexcitation takes place. PMID:26765169

  13. CFL3D Version 6.4-General Usage and Aeroelastic Analysis

    NASA Technical Reports Server (NTRS)

    Bartels, Robert E.; Rumsey, Christopher L.; Biedron, Robert T.

    2006-01-01

    This document contains the course notes on the computational fluid dynamics code CFL3D version 6.4. It is intended to provide from basic to advanced users the information necessary to successfully use the code for a broad range of cases. Much of the course covers capability that has been a part of previous versions of the code, with material compiled from a CFL3D v5.0 manual and from the CFL3D v6 web site prior to the current release. This part of the material is presented to users of the code not familiar with computational fluid dynamics. There is new capability in CFL3D version 6.4 presented here that has not previously been published. There are also outdated features no longer used or recommended in recent releases of the code. The information offered here supersedes earlier manuals and updates outdated usage. Where current usage supersedes older versions, notation of that is made. These course notes also provides hints for usage, code installation and examples not found elsewhere.

  14. Photolytic degradation of benorylate: effects of the photoproducts on cultured hepatocytes

    SciTech Connect

    Castell, J.V.; Gomez, M.J.; Mirabet, V.; Miranda, M.A.; Morera, I.M.

    1987-05-01

    The photodegradation of benorylate (4'-(acetamido)phenyl-2-acetoxybenzoate), a drug frequently used in rheumatoid arthritis therapy, has been examined under different sets of experimental conditions. Several photoproducts have been isolated and identified on the basis of their IR, NMR, and MS spectra. The most significant photochemical process is the photo-Fries rearrangement of benorylate, leading to 5-acetamido-2'-acetoxy-2-hydroxybenzophenone (1). This compound undergoes a rapid transacylation to the isomeric 5'-acetamido-2'-acetoxy-2-hydroxybenzophenone (2). A primary culture of rat hepatocytes has been used to evaluate the possible toxicity of these two benzophenones, keeping in mind the following criteria: leakage of cytosolic enzymes, attachment index to culture plates, gluconeogenesis from lactate and fructose, glycogen balance, and albumin synthesis. At the concentrations assayed, neither of the two major photoproducts of benorylate (benzophenones 1 and 2) had significant toxic effects on liver cells in culture.

  15. Photoaffinity labeling of diphtheria toxin fragment A with NAD: structure of the photoproduct at position 148.

    PubMed

    Carroll, S F; McCloskey, J A; Crain, P F; Oppenheimer, N J; Marschner, T M; Collier, R J

    1985-11-01

    Irradiation of mixtures of diphtheria toxin fragment A and [carbonyl-14C]NAD with UV light (253.7 nm) is known to induce efficient transfer of the radiolabel to position 148, corresponding to glutamic acid in the unmodified protein. Here we report the structure of the photoproduct at position 148, as determined by chemical and photochemical methods, fast-atom-bombardment mass spectrometry, and nuclear magnetic resonance. The photoproduct [an alpha-amino-gamma-(6-nicotin-amidyl)butyric acid residue] contains the entire nicotinamide moiety of NAD linked via its number 6 carbon to the decarboxylated gamma-methylene carbon of Glu-148. No portion of the ADP-ribosyl group of NAD is present. These findings are consistent with the idea that Glu-148 lies at or near the catalytic center of diphtheria toxin. PMID:3864158

  16. Transverse polarization of Σ+(1189) in photoproduction on a hydrogen target in CLAS

    NASA Astrophysics Data System (ADS)

    Nepali, C. S.; Amaryan, M.; Adhikari, K. P.; Aghasyan, M.; Anefalos Pereira, S.; Baghdasaryan, H.; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A. S.; Bono, J.; Boiarinov, S.; Briscoe, W. J.; Bültmann, S.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Cole, P. L.; Collins, P.; Contalbrigo, M.; Crede, V.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; Alaoui, A. El; Fassi, L. El; Fedotov, G.; Fegan, S.; Fersch, R.; Fleming, J. A.; Gabrielyan, M. Y.; Gevorgyan, N.; Giovanetti, K. L.; Girod, F. X.; Glazier, D. I.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guler, N.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Heddle, D.; Hicks, K.; Ho, D.; Holtrop, M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jo, H. S.; Keller, D.; Khandaker, M.; Khetarpal, P.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Koirala, S.; Kubarovsky, V.; Kuhn, S. E.; Kuleshov, S. V.; Kvaltine, N. D.; Lu, H. Y.; MacGregor, I. J. D.; Markov, N.; Mayer, M.; McKinnon, B.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Munevar, E.; Munoz Camacho, C.; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Pappalardo, L. L.; Paremuzyan, R.; Park, K.; Park, S.; Pasyuk, E.; Phelps, E.; Phillips, J. J.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Puckett, A. J. R.; Raue, B. A.; Rimal, D.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Seraydaryan, H.; Sharabian, Y. G.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Stepanyan, S. S.; Stepanyan, S.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Tang, W.; Taylor, C. E.; Tian, Ye; Tkachenko, S.; Torayev, B.; Vernarsky, B.; Vlassov, A. V.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Weinstein, L. B.; Weygand, D. P.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; Zonta, I.

    2013-04-01

    Experimental results on the Σ+(1189) hyperon transverse polarization in photoproduction on a hydrogen target using the CLAS detector at Jefferson Laboratory are presented. The Σ+(1189) was reconstructed in the exclusive reaction γ+p→KS0+Σ+(1189) via the Σ+→pπ0 decay mode. The KS0 was reconstructed in the invariant mass of two oppositely charged pions with the π0 identified in the missing mass of the detected pπ+π- final state. Experimental data were collected in the photon energy range Eγ=1.0-3.5 GeV (s range 1.66-2.73 GeV). We observe a large negative polarization of up to 95%. As the mechanism of transverse polarization of hyperons produced in unpolarized photoproduction experiments is still not well understood, these results will help to distinguish between different theoretical models on hyperon production and provide valuable information for the searches of missing baryon resonances.

  17. A resonance interpretation for the nonmonotonic behavior of the φ photoproduction cross section near threshold

    NASA Astrophysics Data System (ADS)

    Nan Yang, Shin; Kiswandhi, Alvin; Xie, Ju-Jun

    2011-10-01

    We study whether the nonmonotonic behavior found in the differential cross section of the φ-meson photoproduction near threshold can be described by a resonance. The resonant contribution is evaluated by using an effective Lagrangian approach. We find that, with the assumption of a JP = 3/2- resonance with mass of 2.10±0.03 GeV and width of 0.465±0.141 GeV, LEPS data can indeed be well described. The ratio of the helicity amplitudes A1/2/A3/2 calculated from the re-22 sulting coupling constants differs in sign from that of the known D13(2080). We further find that the addition of this postulated resonance can substantially improve the agreement between the existing theoretical predictions and the recent ω photoproduction data if a large value of the OZI evading parameter xOZI = 12 is assumed for the resonance.

  18. Upper limits for the photoproduction cross section for the Phi--(1860) pentaquark state off the deuteron

    SciTech Connect

    Hovanes Egiyan

    2012-01-01

    We searched for the {Phi}{sup --}(1860) pentaquark in the photoproduction process off the deuteron in the {Xi}{sup -} {pi}{sup -} decay channel using CLAS. The invariant mass spectrum of the {Xi}{sup -} {pi}{sup -} system does not indicate any statistically significant enhancement near the reported mass M = 1.860 GeV. The statistical analysis of the sideband-subtracted mass spectrum yields a 90% confidence level upper limit of 0.7 nb for the photoproduction cross section of {Phi}{sup --}(1860) with a consecutive decay into {Xi}{sup -} {pi}{sup -} in the photon energy range 4.5 GeV < E{sub {gamma}} < 5.5 GeV.

  19. Chiral effective-field theory in the Delta(1232) region : II. radiative pion photoproduction

    SciTech Connect

    Vladimir Pascalutsa; Marc Vanderhaeghen

    2007-10-12

    We present a theoretical study of the radiative pion photoproduction on the nucleon ($\\gamma N \\rightarrow \\pi N \\gamma'$) in the $\\De$-resonance region, with the aim to determine the magnetic dipole moment (MDM) of the $\\Delta^+(1232)$. The study is done within the framework of chiral effective-field theory where the expansion is performed (to next-to-leading order) in the $\\delta$ power-counting scheme which is an extension of chiral perturbation theory to the $\\Delta$-resonance energy region. We present in detail the results for the absorptive part of the $\\Delta$ MDM, as well as a sensitivity study for the radiative pion photoproduction observables on the real part of the $\\Delta$ MDM. We find that an asymmetry for circular polarization of the photon beam may provide a model-independent way to measure the $\\Delta$ MDM.

  20. Study of photoproducts of Rhodamine 6G in ethanol upon powerful laser pumping

    SciTech Connect

    Batishche, S.A.; Malevich, N.A.; Mostovnikov, V.A.

    1995-04-01

    Absorption spectra of rhodamine 6G in ethanol solution are measured using, the technique of laser probing upon pumping by a doubled Nd {sup 3+}:YAG laser with pulse length{tau}{sub 01}{approx_equal}16ns. It is shown that, at the pumping energy density {ge}1.5 J/cm{sup 2}, short-lived ({tau} < 25 ns) and long-lived photoproducts formed in the dye solution, which absorbed in a wide spectral range, including the lasing region. The estimates show that the probability of rhodamine 6G transformation to the photoproduct upon three-step excitation at 532 nm achieves {approximately}2.5 X 10{sup -3}. It is noted that, in order to obtain reliable spectroscopic information using this technique, one should take into account the intense scattering of probing radiation by thermal noise gratings, which are formed due to self-diffraction of the pumping radiation into noise components.

  1. Photoproduction of the rho(0) meson on the proton at large momentum transfer.

    PubMed

    Battaglieri, M; Anciant, E; Anghinolfi, M; De Vita, R; Golovach, E; Laget, J M; Mokeev, V; Ripani, M; Adams, G; Amaryan, M J; Armstrong, D S; Asavapibhop, B; Asryan, G; Audit, G; Auger, T; Avakian, H; Barrow, S; Beard, K; Bektasoglu, M; Berman, B L; Bianchi, N; Biselli, A S; Boiarinov, S; Branford, D; Briscoe, W J; Brooks, W K; Burkert, V D; Calarco, J R; Capitani, G P; Carman, D S; Carnahan, B; Cazes, A; Cetina, C; Cole, P L; Coleman, A; Cords, D; Corvisiero, P; Crabb, D; Crannell, H; Cummings, J P; DeSanctis, E; Degtyarenko, P V; Demirchyan, R; Denizli, H; Dennis, L; Dharmawardane, K V; Dhuga, K S; Djalali, C; Dodge, G E; Doughty, D; Dragovitsch, P; Dugger, M; Dytman, S; Eckhause, M; Egiyan, H; Egiyan, K S; Elouadrhiri, L; Farhi, L; Feuerbach, R J; Ficenec, J; Forest, T A; Freyberger, A P; Frolov, V; Funsten, H; Gaff, S J; Gai, M; Gilad, S; Gilfoyle, G P; Giovanetti, K L; Griffioen, K; Guidal, M; Guillo, M; Gyurjyan, V; Hancock, D; Hardie, J; Heddle, D; Hersman, F W; Hicks, K; Hicks, R S; Holtrop, M; Hyde-Wright, C E; Ito, M M; Joo, K; Kelley, J H; Khandaker, M; Kim, W; Klein, A; Klein, F J; Klusman, M; Kossov, M; Kramer, L H; Kuang, Y; Kuhn, S E; Lawrence, D; Lucas, M; Lukashin, K; Major, R W; Manak, J J; Marchand, C; McAleer, S; McCarthy, J; McNabb, J W; Mecking, B A; Mestayer, M D; Meyer, C A; Mikhailov, K; Minehart, R; Mirazita, M; Miskimen, R; Muccifora, V; Mueller, J; Mutchler, G S; Napolitano, J; Nelson, S O; Niczyporuk, B B; Niyazov, R A; O'Brien, J T; Opper, A K; Peterson, G; Philips, S A; Pivnyuk, N; Pocanic, D; Pogorelko, O; Polli, E; Preedom, B M; Price, J W; Protopopescu, D; Qin, L M; Raue, B A; Reolon, A R; Riccardi, G; Ricco, G; Ritchie, B G; Ronchetti, F; Rossi, P; Rowntree, D; Rubin, P D; Sabourov, K; Salgado, C; Sanzone-Arenhovel, M; Sapunenko, V; Schumacher, R A; Serov, V S; Shafi, A; Sharabian, Y G; Shaw, J; Skabelin, A V; Smith, E S; Smith, T; Smith, L C; Sober, D I; Spraker, M; Stavinsky, A; Stepanyan, S; Stoler, P; Taiuti, M; Taylor, S; Tedeschi, D J; Todor, L; Thompson, R; Vineyard, M F; Vlassov, A V; Weinstein, L B; Weisberg, A; Weller, H; Weygand, D P; Whisnant, C S; Wolin, E; Wood, M; Yegneswaran, A; Yun, J; Zhang, B; Zhao, J; Zhou, Z

    2001-10-22

    The differential cross section, d sigma/dt, for rho(0) meson photoproduction on the proton above the resonance region was measured up to a momentum transfer -t = 5 GeV2 using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The rho(0) channel was extracted from the measured two charged-pion cross sections by fitting the pi(+)pi(-) and p pi(+) invariant masses. The low momentum transfer region shows the typical diffractive pattern expected from Reggeon exchange. The flatter behavior at large -t cannot be explained solely in terms of QCD-inspired two-gluon exchange models. The data indicate that other processes, like quark interchange, are important to fully describe rho photoproduction. PMID:11690264

  2. Weak and electromagnetic mechanisms of neutrino-pair photoproduction in a strongly magnetized electron gas

    SciTech Connect

    Borisov, A. V.; Kerimov, B. K.; Sizin, P. E.

    2012-11-15

    Expressions for the power of neutrino radiation from a degenerate electron gas in a strong magnetic field are derived for the case of neutrino-pair photoproduction via the weak and electromagnetic interaction mechanisms (it is assumed that the neutrino possesses electromagnetic form factors). It is shown that the neutrino luminosity of a medium in the electromagnetic reaction channel may exceed substantially the luminosity in the weak channel. Relative upper bounds on the effective neutrino magnetic moment are obtained.

  3. Test of factorization in diffractive deep inelastic scattering and photoproduction at HERA

    SciTech Connect

    Polifka, Richard

    2015-04-10

    The QCD factorization theorem in diffraction is tested by comparing diffractive jet production data to QCD predictions based on fits to inclusive diffractive cross section data. H1 measured dijet production with a leading proton detected in the Very Forward Proton Spectrometer (VFPS), both in deep-inelastic scattering and in photoproduction. The DIS measurements are complemented by measurements of dijet production with an associated rapidity gap and in a data sample selected with a leading proton in the Forward Proton Spectrometer (FPS)

  4. Prolongation of H2 Photoproduction by Immobilized, Sulfur-Limited Chlamydomonas reinhardtii Cultures

    SciTech Connect

    Laurinavichene, T. V.; Kosourov, S. N.; Ghirardi, M. L.; Seibert, M.; Tsygankov, A. A.

    2008-04-30

    Two approaches to prolong the duration of hydrogen production by immobilized, sulfur-limited Chlamydomonas reinhardtii cells are examined. The results demonstrate that continuous H{sub 2} photoproduction can occur for at least 90 days under constant flow of TAP medium containing micromolar sulfate concentrations. Furthermore, it is also possible to prolong the duration of H{sub 2} production by cycling immobilized cells between minus and plus sulfate conditions.

  5. Polarization Observables From The Photoproduction Of Omega-Mesons Using Linearly Polarized Photons

    SciTech Connect

    Martinez, Danny; Cole, Philip L.

    2014-01-01

    We report on the extraction of Polarization Observables Spin Density Matrix Elements (SDMEs), and Beam Asymmetry Sigma for omega meson photoproduction using a beam of linearly polarized photons in the photon energy region of Egamma = 1.3 to 1.7 GeV, by means of the angular distributions of the daughter pions from omega decay. These preliminary results are from the g8b dataset, which were collected with the CLAS detector in Hall B of Jefferson Lab.

  6. Photoproduction of the eta prime meson in the effective Lagrangian approach

    SciTech Connect

    Mukhopadhyay, N.C.; Zhang, J.F.; Benmerrouche, M.

    1994-04-01

    In the framework of the effective Lagrangian approach, the authors study the {eta}{prime} photoproduction off protons, of great interest at CEBAF I and II. They calculate the contributions from the leading nucleon Born terms, vector meson exchanges, and estimate the resonance contributions, using the transition amplitudes from the recent quark model estimates by Capstick and Roberts. They discuss implications for the CEBAF experiments.

  7. Exclusive Photoproduction of K+Σ*-(n) Off Deuteron

    SciTech Connect

    Lu, Haiyun; Graham, Lewis; Zhao, Zhiwen; Park, Kijun; Gothe, Ralf

    2010-08-16

    We are using the CEBAF Large Acceptance Spectrometer (CLAS) to study the exclusive photoproduction of K+Σ*- (1385) off the deuteron. It will be the first published total cross section of this reaction channel. We show the preliminary results of the total cross section, while we present all the key steps of achieving it. In order to study the reaction mechanism, we also study and show the angular distribution in the Gottfried-Jackson frame.

  8. A comparison of hydrogen photoproduction by sulfur-deprived Chlamydomonas reinhardtii under different growth conditions.

    PubMed

    Kosourov, Sergey; Patrusheva, Elena; Ghirardi, Maria L; Seibert, Michael; Tsygankov, Anatoly

    2007-03-10

    Continuous photoproduction of H(2) by the green alga, Chlamydomonas reinhardtii, is observed after incubating the cultures for about a day in the absence of sulfate and in the presence of acetate. Sulfur deprivation causes the partial and reversible inactivation of photosynthetic O(2) evolution in algae, resulting in the light-induced establishment of anaerobic conditions in sealed photobioreactors, expression of two [FeFe]-hydrogenases in the cells, and H(2) photoproduction for several days. We have previously demonstrated that sulfur-deprived algal cultures can produce H(2) gas in the absence of acetate, when appropriate experimental protocols were used (Tsygankov, A.A., Kosourov, S.N., Tolstygina, I.V., Ghirardi, M.L., Seibert, M., 2006. Hydrogen production by sulfur-deprived Chlamydomonas reinhardtii under photoautotrophic conditions. Int. J. Hydrogen Energy 31, 1574-1584). We now report the use of an automated photobioreactor system to compare the effects of photoautotrophic, photoheterotrophic and photomixotrophic growth conditions on the kinetic parameters associated with the adaptation of the algal cells to sulfur deprivation and H(2) photoproduction. This was done under the experimental conditions outlined in the above reference, including controlled pH. From this comparison we show that both acetate and CO(2) are required for the most rapid inactivation of photosystem II and the highest yield of H(2) gas production. Although, the presence of acetate in the system is not critical for the process, H(2) photoproduction under photoautotrophic conditions can be increased by optimizing the conditions for high starch accumulation. These results suggest ways of engineering algae to improve H(2) production, which in turn may have a positive impact on the economics of applied systems for H(2) production. PMID:17275940

  9. Measurement of the G double-polarisation observable in pion photoproduction

    SciTech Connect

    J. McAndrew, D. Watts, E. Pasyuk

    2012-04-01

    The g9a experiment using the CLAS detector in Hall B of Jefferson Lab will measure double-polarization observables using a polarized energy-tagged photon beam in conjunction with the frozen spin target, FROST. This contribution describes the extraction of the G double polarization observable in the single pion photoproduction using a linearly polarized photon beam in the energy range 730-2300 MeV and the longitudinally polarized frozen spin target, FROST.

  10. The structure of an authentic spore photoproduct lesion in DNA suggests a basis for recognition.

    PubMed

    Singh, Isha; Jian, Yajun; Lian, Yajun; Li, Lei; Georgiadis, Millie M

    2014-03-01

    The spore photoproduct lesion (SP; 5-thymine-5,6-dihydrothymine) is the dominant photoproduct found in UV-irradiated spores of some bacteria such as Bacillus subtilis. Upon spore germination, this lesion is repaired in a light-independent manner by a specific repair enzyme: the spore photoproduct lyase (SP lyase). In this work, a host-guest approach in which the N-terminal fragment of Moloney murine leukemia virus reverse transcriptase (MMLV RT) serves as the host and DNA as the guest was used to determine the crystal structures of complexes including 16 bp oligonucleotides with and without the SP lesion at 2.14 and 1.72 Å resolution, respectively. In contrast to other types of thymine-thymine lesions, the SP lesion retains normal Watson-Crick hydrogen bonding to the adenine bases of the complementary strand, with shorter hydrogen bonds than found in the structure of the undamaged DNA. However, the lesion induces structural changes in the local conformation of what is otherwise B-form DNA. The region surrounding the lesion differs significantly in helical form from B-DNA, and the minor groove is widened by almost 3 Å compared with that of the undamaged DNA. Thus, these unusual structural features associated with SP lesions may provide a basis for recognition by the SP lyase. PMID:24598744

  11. A 6.4 kV pulse generator with transformers

    NASA Astrophysics Data System (ADS)

    Bastein, W. L.

    The possibility of producing a 6.4 kV voltage pulse using transformers was investigated. The pulse has to have a rise and fall time of 100 ns, a pulse duration of 2 to 50 microns, a repetition frequency of 2500 Hz, and a ripple of less than 10 V. It is shown that it is in principle possible, using transformers for the low frequency and high frequency parts of the pulse, to produce a pulse which fulfills the slope requirements. However, it is difficult to make and tune the circuits to flatten the pulse sufficiently. The losses are so high that it is recommended to investigate the possibility of producing the pulse with a number of MOSFET's in series.

  12. Biological activity of photoproducts of merocyanine 540 generated by laser-light activation

    NASA Astrophysics Data System (ADS)

    Gulliya, Kirpal S.; Chanh, Tran C.; Pervaiz, Shazib; Harriman, Anthony; Matthews, James Lester

    1992-08-01

    Controlled exposure of photoactive compounds to light prior to their use in biological targets results in the formation of heretofore unknown photoproducts. This process of photoproduct generation, termed "preactivation," renders the photactive compound capable of systemic use without further dependence on light. Preactivation of mercyanin 540 (MC540) and several other photoactive compounds is achievable by exposure to CW and pulse laser radiation. The singlet oxygen generated at excited states attacks the dye molucule itself, resulting in the formation of biologically active photoproducts. For preactivated MC540 (photoproducts of MC540) generated by exposure to argon laser light (514 nm) and light from free-electron laser, we have demonstrated its effectiveness in selective killing of certain types of cultured tumor cells as well as human immunodeficiency virus type 1 (HIV-1) with very low, if any, damage to normal cells and tisues. For example, approximately 90% of the Burkitt's lymphoma Daudi cells and HL-60 leukemic cells are killed by preactivated MC540 at a concentration of 120 μg/ml. A two-hour treatment of cultured cells with buthionine sulfoxamine followed by the treatement with preactivated MC540 reults in 99.99% inhibition of clonogenic tumor stem cell growth. We also have demonstrated that preactivated MC540 is very effective in killing cell-free and cell-associated HIV-1. It also is very effective in killing HIV-1 and simian immunodeficiency virus (SIV) in virus-infected blood in vitro as determined by reverse transcriptase, P24, P17, core antigen expression and synctium formation. Treatment of HIV-1 with preactivated MC540 renders the treated HIV-1 incapable of binding to CD4 target molecules on T cells as determined by immunofluorescence and radioimmunoprecipitation assays. In vivo toxicology studies show that preactivated MC540 is very well tolerated and does not produce any signs of adverse reaction at the therapeutic doses, as determined by

  13. Coherent photoproduction of vector mesons in ultraperipheral heavy ion collisions: Update for run 2 at the CERN Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Guzey, V.; Kryshen, E.; Zhalov, M.

    2016-05-01

    We make predictions for the cross sections of coherent photoproduction of ρ ,ϕ ,J /ψ ,ψ (2 S ) , and Υ (1 S ) mesons in Pb-Pb ultraperipheral collisions (UPCs) at √{sN N}=5.02 TeV in the kinematics of run 2 at the Large Hadron Collider extending the approaches successfully describing the available Pb-Pb UPC data at √{sN N}=2.76 TeV . Our results illustrate the important roles of hadronic fluctuations of the photon and inelastic nuclear shadowing in photoproduction of light vector mesons on nuclei and the large leading twist nuclear gluon shadowing in photoproduction of quarkonia on nuclei. We show that the ratio of ψ (2 S ) and J /ψ photoproduction cross sections in Pb-Pb UPCs is largely determined by the ratio of these cross sections on the proton. We also argue that UPCs with electromagnetic excitations of the colliding ions followed by the forward neutron emission allows one to significantly increase the range of photon energies accessed in vector meson photoproduction on nuclei.

  14. Fatigue Behavior of Ti-6-4 Alloy with Application of Calcium Phosphate

    NASA Astrophysics Data System (ADS)

    Kamboj, Jaspal Singh

    It is key to consider a material's mechanical properties when determining its use for any given application, including biomaterial implantations. One such characteristic includes the fatigue life, which is determined by repeatedly cycling specified amounts of load on any given material. The fatigue life is then measured according to how many cycles of load the material can undergo before fracture. When a material is introduced to the human body it is usually expected that the life of the material will not match that of the patient. It is crucial to understand the fatigue life of the material before implantation to pre-diagnose how often and when the implant will need to be replaced. The purpose of this project is to help determine and compare the fatigue behaviors of a commonly used biocompatible coating on Titanium 6-4 metal alloy. The comparison will help identify how the material properties vary with the addition of calcium phosphate when compared to the bare alloy itself. Multiple, small rectangular samples were cut by electrical discharge machining (EDM) of which half were covered with calcium phosphate coating. Fatigue crack initiations and propagation would then be analyzed using scanning electron microscopy (SEM) to help determine the nature of the damage processes. It was found that the fatigue life of the coated samples varied at different stresses but was greater than the bare samples, and particularly high in the 900 MPa - 1000 MPa stress range.

  15. Asperity break after 12 years: The Mw6.4 2015 Lefkada (Greece) earthquake

    NASA Astrophysics Data System (ADS)

    Sokos, E.; Zahradník, J.; Gallovič, F.; Serpetsidaki, A.; Plicka, V.; Kiratzi, A.

    2016-06-01

    The Mw6.4 earthquake sequence of 2015 in western Greece is analyzed using seismic data. Multiple point source modeling, nonlinear slip patch, and linear slip inversions reveal a coherent rupture image with directivity toward the southwest and several moment release episodes, reflected in the complex aftershock distribution. The key feature is that the 2015 earthquake ruptured a strong asperity, which was left unbroken in between two large subevents of the Mw6.2 Lefkada doublet in 2003. This finding and the well-analyzed Cephalonia earthquake sequence of 2014 provide strong evidence of segmentation of the major dextral Cephalonia-Lefkada Transform Fault (CTF), being related to extensional duplex transform zones. We propose that the duplexes extend farther to the north and that the CTF runs parallel to the western coast of Lefkada and Cephalonia Islands, considerably closer to the inhabited islands than previously thought. Generally, this study demonstrates faulting complexity across short time scales (earthquake doublets) and long time scales (seismic gaps).

  16. High-power MIXSEL: an integrated ultrafast semiconductor laser with 6.4 W average power.

    PubMed

    Rudin, B; Wittwer, V J; Maas, D J H C; Hoffmann, M; Sieber, O D; Barbarin, Y; Golling, M; Südmeyer, T; Keller, U

    2010-12-20

    High-power ultrafast lasers are important for numerous industrial and scientific applications. Current multi-watt systems, however, are based on relatively complex laser concepts, for example using additional intracavity elements for pulse formation. Moving towards a higher level of integration would reduce complexity, packaging, and manufacturing cost, which are important requirements for mass production. Semiconductor lasers are well established for such applications, and optically-pumped vertical external cavity surface emitting lasers (VECSELs) are most promising for higher power applications, generating the highest power in fundamental transverse mode (>20 W) to date. Ultrashort pulses have been demonstrated using passive modelocking with a semiconductor saturable absorber mirror (SESAM), achieving for example 2.1-W average power, sub-100-fs pulse duration, and 50-GHz pulse repetition rate. Previously the integration of both the gain and absorber elements into a single wafer was demonstrated with the MIXSEL (modelocked integrated external-cavity surface emitting laser) but with limited average output power (<200 mW). We have demonstrated the power scaling concept of the MIXSEL using optimized quantum dot saturable absorbers in an antiresonant structure design combined with an improved thermal management by wafer removal and mounting of the 8-µm thick MIXSEL structure directly onto a CVD-diamond heat spreader. The simple straight cavity with only two components has generated 28-ps pulses at 2.5-GHz repetition rate and an average output power of 6.4 W, which is higher than for any other modelocked semiconductor laser. PMID:21197032

  17. Physicochemical Mechanism of Light-Driven DNA Repair by (6-4) Photolyases

    NASA Astrophysics Data System (ADS)

    Faraji, Shirin; Dreuw, Andreas

    2014-04-01

    DNA photolyases are light-activated enzymes that repair DNA damage induced by ultraviolet (UV) radiation. UV radiation causes two of the most abundant mutagenic and cytotoxic DNA lesions: cyclobutane pyrimidine dimers and 6-4 photolesions. Photolyases selectively bind to DNA and initiate the splitting of mutagenic pyrimidine dimers via photoinduced electron transfer from a flavin adenine dinucleotide anion (FADH-) to the lesion triggering its repair. This review discusses the consecutive steps of the repair process, from both experimental and theoretical points of view. It covers the following issues: the process of how photolyases accommodate the lesion into their binding pockets, excitation energy transfer between two involved catalytic cofactors, photoinduced electron transfer to the lesion, the splitting of the pyrimidine dimer radical anion, and the fate of the unstable radical species created after the splitting of the thymine dimer. In particular, mechanisms of the splitting and restoration of the original bases are described in detail, and the most probable repair pathways are outlined.

  18. Physicochemical mechanism of light-driven DNA repair by (6-4) photolyases.

    PubMed

    Faraji, Shirin; Dreuw, Andreas

    2014-01-01

    DNA photolyases are light-activated enzymes that repair DNA damage induced by ultraviolet (UV) radiation. UV radiation causes two of the most abundant mutagenic and cytotoxic DNA lesions: cyclobutane pyrimidine dimers and 6-4 photolesions. Photolyases selectively bind to DNA and initiate the splitting of mutagenic pyrimidine dimers via photoinduced electron transfer from a flavin adenine dinucleotide anion (FADH(-)) to the lesion triggering its repair. This review discusses the consecutive steps of the repair process, from both experimental and theoretical points of view. It covers the following issues: the process of how photolyases accommodate the lesion into their binding pockets, excitation energy transfer between two involved catalytic cofactors, photoinduced electron transfer to the lesion, the splitting of the pyrimidine dimer radical anion, and the fate of the unstable radical species created after the splitting of the thymine dimer. In particular, mechanisms of the splitting and restoration of the original bases are described in detail, and the most probable repair pathways are outlined. PMID:24364918

  19. Exclusive photoproduction of f1(1285) meson off the proton in kinematics available at the Jefferson Laboratory experimental facilities

    SciTech Connect

    N.I. Kochelev, M. Battaglieri, R. De Vita

    2009-08-01

    We calculated the exclusive f1(1285) meson photoproduction cross section at an energy of a few GeV within the Regge approach. The calculation shows that the cross section is sizable, being in the range of 100 nb, and much larger than the expected cross section of the eta(1295) meson photoproduction at the same energy. These two facts make it possible to use this reaction to study the poor known properties of the f1(1285) meson in the JLab kinematics.

  20. Laser mass spectrometric detection of AlH molecules as collision-free excimer laser photoproducts from aluminum alkyls

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Stuke, M.

    1988-08-01

    Aluminum hydride molecules AlH are detected and identified by tunable dye-laser mass spectroscopy as collision-free UV excimer laser photoproducts of the Al alkyls TEA (triethylaluminum (C 2H 5) 3Al) and TIBA (triisobutylaluminum ( i-C 4H 9) 3Al) at 248 and 193 nm. An internal energy distribution analysis of the photoproducts shows only minor vibrational excitation of ν″ = 1 and a Boltzmann-type rotational energy distribution with a temperature of about 0.03 eV, compared to the incoming photon energy of 5.0 or 6.42 eV.

  1. Hydrogen photoproduction is attenuated by disruption of an isoamylase gene in Chlamydomonas reinhardtii.

    PubMed

    Posewitz, Matthew C; Smolinski, Sharon L; Kanakagiri, Saradadevi; Melis, Anastasios; Seibert, Michael; Ghirardi, Maria L

    2004-08-01

    DNA insertional transformants of Chlamydomonas reinhardtii were screened chemochromically for attenuated H(2) production. One mutant, displaying low H(2) gas photoproduction, has a nonfunctional copy of a gene that shows high homology to the family of isoamylase genes found in several photosynthetic organisms. DNA gel blotting and gene complementation were used to link this isoamylase gene to previously characterized nontagged sta7 mutants. This mutant is therefore denoted sta7-10. In C. reinhardtii, the STA7 isoamylase gene is important for the accumulation of crystalline starch, and the sta7-10 mutant reported here contains <3% of the glucose found in insoluble starch when compared with wild-type control cells. Hydrogen photoproduction rates, induced after several hours of dark, anaerobic treatment, are attenuated in sta7 mutants. RNA gel blot analysis indicates that the mRNA transcripts for both the HydA1 and HydA2 [Fe]-hydrogenase genes are expressed in the sta7-10 mutant at greater than wild-type levels 0.5 h after anaerobic induction. However, after 1.5 h, transcript levels of both HydA1 and HydA2 begin to decline rapidly and reach nearly undetectable levels after 7 h. In wild-type cells, the hydrogenase transcripts accumulate more slowly, reach a plateau after 4 h of anaerobic treatment, and maintain the same level of expression for >7 h under anaerobic incubation. Complementation of mutant cells with genomic DNA corresponding to the STA7 gene restores both the starch accumulation and H(2) production phenotypes. The results indicate that STA7 and starch metabolism play an important role in C. reinhardtii H(2) photoproduction. Moreover, the results indicate that mere anaerobiosis is not sufficient to maintain hydrogenase gene expression without the underlying physiology, an important aspect of which is starch metabolism. PMID:15269330

  2. Double neutral pion photoproduction off the proton with FOREST at ELPH

    NASA Astrophysics Data System (ADS)

    He, Q.; Fujimura, H.; Fukasawa, H.; Hashimoto, R.; Honda, Y.; Ishikawa, T.; Iwata, T.; Kaida, S.; Kasagi, J.; Kawano, A.; Kuwasaki, S.; Maeda, K.; Masumoto, S.; Miyabe, M.; Miyahara, F.; Mochizuki, K.; Muramatsu, N.; Nakamura, A.; Nawa, K.; Ogushi, S.; Okada, Y.; Onodera, Y.; Ozawa, K.; Sakamoto, Y.; Sato, M.; Shimizu, H.; Sugai, H.; Suzuki, K.; Tajima, Y.; Takahashi, S.; Taniguchi, Y.; Tsuchikawa, Y.; Yamazaki, H.; Yamazaki, R.; Yoshida, H. Y.

    2016-02-01

    Total cross section for the double neutral pion photoproduction off the proton is presented in the incident photon energy range of 0.58 to 1.15 GeV. The data were accumulated in the years 2009-2010, recorded by a 4π EM calorimeter at ELPH, named FOREST. The number of recorded events obtained during this period is 1.6×109 for a hydrogen target. Two neutral pions are reconstructed via detecting their decay products, four gammas (2π0 → 4γ). Compared to the previous results obtained by other groups, our data are in good agreement with theirs within error bars.

  3. Inclusive Sigma- photoproduction on the neutron via the reaction gamma n (p) ---> K+ Sigma- (p)

    SciTech Connect

    Jorn Langheinrich; Ana Lima; Barry Berman

    2006-06-01

    The analysis described here is part of a comprehensive survey of the elementary strangeness photoproduction cross sections on the nucleon. The six elementary strangeness reactions are {gamma}n {yields} K{sup 0}{Lambda} and {gamma}p {yields} K{sup +}{Lambda} {gamma}n {yields} K{sup 0}{Sigma}{sup 0} and {gamma}p {yields} K{sup +}{Sigma}{sup 0} {gamma}n {yields} K{sup +}{Sigma}{sup -} and {gamma}p {yields} K{sup 0}{Sigma}|{sup +}

  4. Unitary constraints on charged pion photoproduction at large p_perp

    SciTech Connect

    J.M. Laget

    2010-03-01

    Around $\\theta_{\\pi}=$~90$^\\circ$, the coupling to the $\\rho^\\circ N$ channel leads to a good accounting of the charged pion exclusive photoproduction cross section in the energy range 3~$<$~10~GeV, where experimental data exist. Starting from a Regge Pole approach that successfully describes vector meson production, the singular part of the corresponding box diagrams (where the intermediate vector meson-baryon pair propagates on-shell) is evaluated without any further assumptions (unitarity). Such a treatment provides an explanation of the $s^{-7}$ scaling of the cross section. Elastic rescattering of the charged pion improves the basic Regge pole model at forward and backward angles.

  5. Studying the Pc(4450) resonance in J/ψ photoproduction off protons

    DOE PAGESBeta

    Blin, A. N. Hiller; Fernandez-Ramirez, C.; Jackura, A.; Mathieu, V.; Mokeev, V. I.; Pilloni, A.; Szczepaniak, A. P.

    2016-08-01

    In this study, a resonance-like structure, the Pc(4450), has recently been observed in the J/ψ p spectrum by the LHCb collaboration. We discuss the feasibility of detecting this structure in J/ψ photoproduction in the CLAS12 experiment at JLab. We present a first estimate of the upper limit for the branching ratio of the Pc(4450) to J/ψ p. Our estimates, which take into account the experimental resolution effects, lead to a sizable cross section close to the J/ψ production threshold, which makes future experiments covering this region very promising.

  6. Photoproduction of the Charged Top-Pions at the LHeC

    NASA Astrophysics Data System (ADS)

    Guo, Jing; Yue, Chong-Xing; Zhang, Jiao; Zeng, Qing-Guo

    2012-11-01

    The top triangle moose (TTM) model, which can be seen as the deconstructed version of the topcolor-assisted technicolor (TC2) model, predicts the existence of the charged top-pions πt± in low energy spectrum. In the context of this model, we consider photoproduction of πt± via the subprocesses γb → tπt- and at the large hadron-electron collider (LHeC), in which high energy photon beams are generated by using the Compton backscatting method. We find that, as long as the charged top-pions are not too heavy, they can be abundantly produced via 76 collision.

  7. Precise photoproduction of the charged top-pions at the LHC with forward detector acceptances

    NASA Astrophysics Data System (ADS)

    Sun, Hao; Yue, Chong-Xing

    2014-04-01

    We study the photoproduction of the charged top-pion predicted by the top triangle moose (TTM) model (a deconstructed version of the topcolor-assisted technicolor TC2 model) via the processes at the 14 TeV Large Hadron Collider (LHC) including next-to-leading order (NLO) QCD corrections. Our results show that the production cross sections and distributions are sensitive to the free parameters and . A typical QCD correction value is and this does not depend much on as well as the forward detector acceptances.

  8. Study of the Hyperon-Nucleon (YN) Interaction in Exclusive Λ Photoproduction off the Deuteron

    NASA Astrophysics Data System (ADS)

    Cao, Tongtong; Ilieva, Yordanka; Zachariou, Nicholas

    2016-07-01

    This study aims to extract the polarization observables Cx, Cz, ∑, Ox, and Oz for final-state interactions (FSI) in overrightarrow γ d to {K^ + }overrightarrow Λ n. The data were taken with the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility (JLab) during the E06-103 experiment. These are the very first results for FSI observables in hyperon photoproduction and are expected to constrain the free parameters of YN potentials. This work is funded in part by the U.S. NSF under grant PHY-125782.

  9. Evidence for Nucleon-Resonance Excitation in {omega}-Meson Photoproduction

    SciTech Connect

    Ajaka, J.; Assafiri, Y.; Bouchigny, S.; Didelez, J.P.; Fichen, L.; Guidal, M.; Hourany, E.; Kunne, R.; Kouznetsov, V.; Mushkarenkov, A.N.; Nedorezov, V.; Rudnev, N.; Turinge, A.; Zhao, Q.

    2006-04-07

    The photoproduction of the {omega} meson has been studied at GRAAL from threshold up to a photon energy of 1.5 GeV. The differential cross sections and beam asymmetries have been measured precisely at all angles. The total cross section is also obtained. Systematic enhancements of the differential cross section at large angles and nonzero beam asymmetries at intermediate angles provide clear evidence for s- and u-channel resonant processes. The data are compared to the results of hadron and quark models.

  10. Beam asymmetries in near-threshold {omega} photoproduction off the proton

    SciTech Connect

    Klein, Frank; Bantes, B.; Dutz, H.; Elsner, D.; Ewald, R.; Hoeffgen, S.; Kammer, S.; Kleber, V.; Klein, Friedrich; Konrad, M.; Menze, D.; Morales, C.; Ostrick, M.; Schmieden, H.; Suele, A.; Walther, D.; Anisovich, A. V.; Bayadilov, D.; Nikonov, V. A.; Novinski, D.

    2008-12-01

    The photoproduction of {omega} mesons off protons has been studied at the Bonn ELSA accelerator from threshold to E{sub {gamma}}=1700 MeV. Linearly polarized beams were produced via coherent bremsstrahlung. Large photon asymmetries in excess of 50% were obtained. For the first time the pion asymmetries associated with the {omega}{yields}{pi}{sup 0}{gamma} decay were measured and found close to zero. The asymmetries indicate s-channel resonance formation on top of t-channel exchange processes.

  11. Measurement of charm and beauty photoproduction at HERA using D* μ correlations

    NASA Astrophysics Data System (ADS)

    Aktas, A.; Andreev, V.; Anthonis, T.; Aplin, S.; Asmone, A.; Astvatsatourov, A.; Babaev, A.; Backovic, S.; Bähr, J.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Baudrand, S.; Baumgartner, S.; Becker, J.; Beckingham, M.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, Ch.; Berger, N.; Bizot, J. C.; Boenig, M.-O.; Boudry, V.; Bracinik, J.; Brandt, G.; Brisson, V.; Brown, D. P.; Bruncko, D.; Büsser, F. W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A. J.; Caron, S.; Cassol-Brunner, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Contreras, J. G.; Coughlan, J. A.; Cox, B. E.; Cozzika, G.; Cvach, J.; Dainton, J. B.; Dau, W. D.; Daum, K.; Delcourt, B.; Demirchyan, R.; De Roeck, A.; Desch, K.; De Wolf, E. A.; Diaconu, C.; Dodonov, V.; Dubak, A.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Ellerbrock, M.; Elsen, E.; Erdmann, W.; Essenov, S.; Falkewicz, A.; Faulkner, P. J. W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Finke, L.; Fleischer, M.; Fleischmann, P.; Fleming, Y. H.; Flucke, G.; Fomenko, A.; Foresti, I.; Formánek, J.; Franke, G.; Frising, G.; Frisson, T.; Gabathuler, E.; Garutti, E.; Gayler, J.; Gerhards, R.; Gerlich, C.; Ghazaryan, S.; Ginzburgskaya, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gorbounov, S.; Goyon, C.; Grab, C.; Greenshaw, T.; Gregori, M.; Grindhammer, G.; Gwilliam, C.; Haidt, D.; Hajduk, L.; Haller, J.; Hansson, M.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Henshaw, O.; Herrera, G.; Hildebrandt, M.; Hiller, K. H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Ibbotson, M.; Ismail, M.; Jacquet, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jönsson, L.; Johnson, D. P.; Jung, H.; Kapichine, M.; Karlsson, M.; Katzy, J.; Keller, N.; Kenyon, I. R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knies, G.; Knutsson, A.; Korbel, V.; Kostka, P.; Koutouev, R.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Krüger, K.; Kückens, J.; Landon, M. P. J.; Lange, W.; Laštovička, T.; Laycock, P.; Lebedev, A.; Leißner, B.; Lendermann, V.; Levonian, S.; Lindfeld, L.; Lipka, K.; List, B.; Lobodzinska, E.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.-I.; Lueders, H.; Lüke, D.; Lux, T.; Lytkin, L.; Makankine, A.; Malden, N.; Malinovski, E.; Mangano, S.; Marage, P.; Marshall, R.; Martisikova, M.; Martyn, H.-U.; Maxfield, S. J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A. B.; Meyer, H.; Meyer, J.; Mikocki, S.; Milcewicz-Mika, I.; Milstead, D.; Mohamed, A.; Moreau, F.; Morozov, A.; Morris, J. V.; Mozer, M. U.; Müller, K.; Murín, P.; Nankov, K.; Naroska, B.; Naumann, J.; Naumann, Th.; Newman, P. R.; Niebuhr, C.; Nikiforov, A.; Nikitin, D.; Nowak, G.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J. E.; Osman, S.; Ozerov, D.; Palichik, V.; Papadopoulou, T.; Pascaud, C.; Patel, G. D.; Peez, M.; Perez, E.; Perez-Astudillo, D.; Perieanu, A.; Petrukhin, A.; Pitzl, D.; Plačakytė, R.; Portheault, B.; Povh, B.; Prideaux, P.; Raicevic, N.; Reimer, P.; Rimmer, A.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Salvaire, F.; Sankey, D. P. C.; Sauvan, E.; Schätzel, S.; Schilling, F.-P.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schöning, A.; Schröder, V.; Schultz-Coulon, H.-C.; Schwanenberger, C.; Sedlák, K.; Sefkow, F.; Sheviakov, I.; Shtarkov, L. N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, A.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Tchoulakov, V.; Thompson, G.; Thompson, P. D.; Tomasz, F.; Traynor, D.; Truöl, P.; Tsakov, I.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, M.; Usik, A.; Utkin, D.; Valkár, S.; Valkárová, A.; Vallée, C.; Van Mechelen, P.; Van Remortel, N.; Vargas Trevino, A.; Vazdik, Y.; Veelken, C.; Vest, A.; Vinokurova, S.; Volchinski, V.; Vujicic, B.; Wacker, K.; Wagner, J.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; Wessling, B.; Wigmore, C.; Winter, G.-G.; Wissing, Ch.; Wolf, R.; Wünsch, E.; Xella, S.; Yan, W.; Yeganov, V.; Žáček, J.; Zálešák, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zimmermann, J.; Zohrabyan, H.; Zomer, F.; H1 Collaboration

    2005-08-01

    A measurement of charm and beauty photoproduction at the electron proton collider HERA is presented based on the simultaneous detection of a D*± meson and a muon. The correlation between the D* meson and the muon serves to separate the charm and beauty contributions and the analysis provides comparable sensitivity to both. The total and differential experimental cross sections are compared to LO and NLO QCD calculations. The measured charm cross section is in good agreement with QCD predictions including higher order effects while the beauty cross section is higher.

  12. Measurement of charm and beauty photoproduction at HERA using Dμ correlations

    NASA Astrophysics Data System (ADS)

    H1 Collaboration; Aktas, A.; Andreev, V.; Anthonis, T.; Aplin, S.; Asmone, A.; Astvatsatourov, A.; Babaev, A.; Backovic, S.; Bähr, J.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Baudrand, S.; Baumgartner, S.; Becker, J.; Beckingham, M.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, Ch.; Berger, N.; Bizot, J. C.; Boenig, M.-O.; Boudry, V.; Bracinik, J.; Brandt, G.; Brisson, V.; Brown, D. P.; Bruncko, D.; Büsser, F. W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A. J.; Caron, S.; Cassol-Brunner, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Contreras, J. G.; Coughlan, J. A.; Cox, B. E.; Cozzika, G.; Cvach, J.; Dainton, J. B.; Dau, W. D.; Daum, K.; Delcourt, B.; Demirchyan, R.; de Roeck, A.; Desch, K.; de Wolf, E. A.; Diaconu, C.; Dodonov, V.; Dubak, A.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Ellerbrock, M.; Elsen, E.; Erdmann, W.; Essenov, S.; Falkewicz, A.; Faulkner, P. J. W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Finke, L.; Fleischer, M.; Fleischmann, P.; Fleming, Y. H.; Flucke, G.; Fomenko, A.; Foresti, I.; Formánek, J.; Franke, G.; Frising, G.; Frisson, T.; Gabathuler, E.; Garutti, E.; Gayler, J.; Gerhards, R.; Gerlich, C.; Ghazaryan, S.; Ginzburgskaya, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gorbounov, S.; Goyon, C.; Grab, C.; Greenshaw, T.; Gregori, M.; Grindhammer, G.; Gwilliam, C.; Haidt, D.; Hajduk, L.; Haller, J.; Hansson, M.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Henshaw, O.; Herrera, G.; Hildebrandt, M.; Hiller, K. H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Ibbotson, M.; Ismail, M.; Jacquet, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jönsson, L.; Johnson, D. P.; Jung, H.; Kapichine, M.; Karlsson, M.; Katzy, J.; Keller, N.; Kenyon, I. R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knies, G.; Knutsson, A.; Korbel, V.; Kostka, P.; Koutouev, R.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Krüger, K.; Kückens, J.; Landon, M. P. J.; Lange, W.; Laštovička, T.; Laycock, P.; Lebedev, A.; Leißner, B.; Lendermann, V.; Levonian, S.; Lindfeld, L.; Lipka, K.; List, B.; Lobodzinska, E.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.-I.; Lueders, H.; Lüke, D.; Lux, T.; Lytkin, L.; Makankine, A.; Malden, N.; Malinovski, E.; Mangano, S.; Marage, P.; Marshall, R.; Martisikova, M.; Martyn, H.-U.; Maxfield, S. J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A. B.; Meyer, H.; Meyer, J.; Mikocki, S.; Milcewicz-Mika, I.; Milstead, D.; Mohamed, A.; Moreau, F.; Morozov, A.; Morris, J. V.; Mozer, M. U.; Müller, K.; Murín, P.; Nankov, K.; Naroska, B.; Naumann, J.; Naumann, Th.; Newman, P. R.; Niebuhr, C.; Nikiforov, A.; Nikitin, D.; Nowak, G.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J. E.; Osman, S.; Ozerov, D.; Palichik, V.; Papadopoulou, T.; Pascaud, C.; Patel, G. D.; Peez, M.; Perez, E.; Perez-Astudillo, D.; Perieanu, A.; Petrukhin, A.; Pitzl, D.; Plačakytė, R.; Portheault, B.; Povh, B.; Prideaux, P.; Raicevic, N.; Reimer, P.; Rimmer, A.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Salvaire, F.; Sankey, D. P. C.; Sauvan, E.; Schätzel, S.; Schilling, F.-P.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schöning, A.; Schröder, V.; Schultz-Coulon, H.-C.; Schwanenberger, C.; Sedlák, K.; Sefkow, F.; Sheviakov, I.; Shtarkov, L. N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, A.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Tchoulakov, V.; Thompson, G.; Thompson, P. D.; Tomasz, F.; Traynor, D.; Truöl, P.; Tsakov, I.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, M.; Usik, A.; Utkin, D.; Valkár, S.; Valkárová, A.; Vallée, C.; van Mechelen, P.; van Remortel, N.; Vargas Trevino, A.; Vazdik, Y.; Veelken, C.; Vest, A.; Vinokurova, S.; Volchinski, V.; Vujicic, B.; Wacker, K.; Wagner, J.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; Wessling, B.; Wigmore, C.; Winter, G.-G.; Wissing, Ch.; Wolf, R.; Wünsch, E.; Xella, S.; Yan, W.; Yeganov, V.; Žáček, J.; Zálešák, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zimmermann, J.; Zohrabyan, H.; Zomer, F.

    2005-08-01

    A measurement of charm and beauty photoproduction at the electron proton collider HERA is presented based on the simultaneous detection of a D meson and a muon. The correlation between the D meson and the muon serves to separate the charm and beauty contributions and the analysis provides comparable sensitivity to both. The total and differential experimental cross sections are compared to LO and NLO QCD calculations. The measured charm cross section is in good agreement with QCD predictions including higher order effects while the beauty cross section is higher.

  13. Helicity-dependent angular distributions in double-charged-pion photoproduction

    SciTech Connect

    Steffen Strauch

    2003-05-01

    Two-pion photoproduction in the reaction {gamma}p {yields} p{pi}{sup +} {pi}{sup -} has been studied at Jefferson Lab Hall B using a circularly-polarized tagged photon beam in the energy range between 0.6 GeV and 2.3 GeV. Owing to the large angular acceptance of the CLAS detector, complete beam-helicity-dependent angular distributions of the final-state particles were measured. The large cross-section asymmetries exhibit strong sensitivity to the kinematics of the reaction and provide valuable information on the reaction dynamics. Preliminary results are presented.

  14. Photochemistry of polycyclic aromatic hydrocarbons in cosmic water ice. I. Mid-IR spectroscopy and photoproducts

    NASA Astrophysics Data System (ADS)

    Bouwman, J.; Mattioda, A. L.; Linnartz, H.; Allamandola, L. J.

    2011-01-01

    Context. Polycyclic aromatic hydrocarbons (PAHs) are known to be abundantly present in photon-dominated regions (PDRs), as evidenced by their ubiquitous mid-IR emission bands. Towards dense clouds, however, their IR emission bands are strongly suppressed. It is here where molecules are known to reside on very cold grains (T ≤ 30 K) in the form of interstellar ices. Therefore, it is likely that non-volatile species, such as PAHs, also freeze out on grains. Such icy grains act as catalytic sites and, upon vacuum ultraviolet (VUV) irradiation, chemical reactions are initiated. In the study presented here, these reactions and the resulting photoproducts are investigated for PAH containing water ices. Aims: The aim of this work is to monitor vacuum ultraviolet induced chemical reactions of PAHs in cosmic ice through their IR signatures, to characterize the families of species formed in these reactions, and to apply the results to astronomical observations. Methods: Mid-infrared Fourier transform absorption spectroscopic measurements ranging from 6500 to 450 cm-1 are performed on freshly deposited and vacuum ultraviolet processed PAH containing cosmic H2O ices at low temperatures. Results: The mid-IR spectroscopy of anthracene, pyrene and benzo[ghi]perylene containing H2O ice is reported. Band strengths of the neutral PAH modes in H2O ice are derived. Additionally, spectra of vacuum ultraviolet processed PAH containing H2O ices are presented. These spectra are compared to spectra measured in VUV processed PAH:argon matrix isolation studies. It is concluded that the parent PAH species is ionized in H2O ice and that other photoproducts, mainly more complex PAH derivatives, also form. The importance of PAHs and their PAH:H2O photoproducts in astronomical mid-infrared spectroscopic studies, in particular in the 5-8 μm region, is discussed. As a test-case, the VUV photolyzed PAH:H2O laboratory spectra are compared to a high resolution ISO-SWS spectrum of the high

  15. Regge-plus-resonance predictions for neutral-kaon photoproduction from the deuteron

    SciTech Connect

    Vancraeyveld, P.; De Cruz, L.; Ryckebusch, J.

    2011-10-24

    We present a Regge-inspired effective-Lagrangian framework for neutral-kaon photo-production from the deuteron. Quasi-free kaon production is investigated using the Regge-plus-resonance elementary operator within the relativistic plane-wave impulse approximation. The Regge-plus-resonance model was developed to describe photoinduced and electroinduced charged-kaon production off protons. We show how this elementary operator can be transformed to account for the production of neutral kaons from both protons and neutrons. Our results compare favourably to the sole {sup 2}H({gamma},K{sup 0})YN dataset published to date.

  16. The GlueX experiment: Search for gluonic excitations via photoproduction at Jefferson Lab

    SciTech Connect

    Eugenio, Paul

    2013-07-01

    Studies of meson spectra via strong decays provide insight regarding QCD at the confinement scale. These studies have led to phenomenological models for QCD such as the constituent quark model. However, QCD allows for a much richer spectrum of meson states which include extra states such as exotics, hybrids, multi-quarks, and glueballs. First discussion of the status of exotic meson searches is given followed by an overview of the progress at Jefferson Lab to double the energy of the machine to 12 GeV, which will allow us to access photoproduction of mesons in search for gluonic excited states.

  17. A new measurement of Beam Asymmetry in Pion Photoproduction from the Neutron using CLAS

    SciTech Connect

    D. Sokhan, D. Watts, D. Branford, F. Klein

    2010-08-01

    We present a preliminary analysis of the photon beam asymmetry observable (Sigma) from the photoproduction reaction channel gamma+ n -> p + pi-. This new data was obtained using the near-4pi CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Laboratory, USA, employing a linearly polarised photon beam with an energy range 1.1 - 2.3 GeV. The measurement will provide new data to address the poorly established neutron excitation spectrum and will greatly expand the sparse world data-set both in energy and angle.

  18. Genome-wide analysis of human global and transcription-coupled excision repair of UV damage at single-nucleotide resolution

    PubMed Central

    Hu, Jinchuan; Adar, Sheera; Selby, Christopher P.

    2015-01-01

    We developed a method for genome-wide mapping of DNA excision repair named XR-seq (excision repair sequencing). Human nucleotide excision repair generates two incisions surrounding the site of damage, creating an ∼30-mer. In XR-seq, this fragment is isolated and subjected to high-throughput sequencing. We used XR-seq to produce stranded, nucleotide-resolution maps of repair of two UV-induced DNA damages in human cells: cyclobutane pyrimidine dimers (CPDs) and (6-4) pyrimidine–pyrimidone photoproducts [(6-4)PPs]. In wild-type cells, CPD repair was highly associated with transcription, specifically with the template strand. Experiments in cells defective in either transcription-coupled excision repair or general excision repair isolated the contribution of each pathway to the overall repair pattern and showed that transcription-coupled repair of both photoproducts occurs exclusively on the template strand. XR-seq maps capture transcription-coupled repair at sites of divergent gene promoters and bidirectional enhancer RNA (eRNA) production at enhancers. XR-seq data also uncovered the repair characteristics and novel sequence preferences of CPDs and (6-4)PPs. XR-seq and the resulting repair maps will facilitate studies of the effects of genomic location, chromatin context, transcription, and replication on DNA repair in human cells. PMID:25934506

  19. Regge approach to charged-pion photoproduction at invariant energies above 2 GeV

    SciTech Connect

    Sibirtsev, A; Haidenbauer, J; Krewald, S; Lee, T S.H.; Meissner, U -G; Thomas, A W

    2007-10-01

    A Regge model with absorptive corrections is employed in a global analysis of the world data on positive and negative pion photoproduction for photon energies from 3 to 8~GeV. In this region resonance contributions are expected to be negligible so that the available experimental information on differential cross sections and single polarization observables at $-t{\\leq}2$ GeV$^2$ allows us to determine the non-resonant part of the reaction amplitude reliably. The model amplitude is then used to predict observables for photon energies below $3$ GeV. Differences between our predictions and data in this energy region are systematically examined as possible signals for the presence of excited baryons. We find that the data available for the polarized photon asymmetry show promising resonance signatures at invariant energies around 2~GeV. With regard to differential cross sections the analysis of negative pion photoproduction data, obtained recently at JLab, indicates likewise the presence of resonance structures around 2~GeV.

  20. J/psi Photo-production at Large z in Soft Collinear Effective Theory

    SciTech Connect

    Sean Fleming; Adam K. Leibovich; Thomas Mehen

    2005-10-02

    One of the outstanding problems in J/{psi} physics is a systematic understanding of the differential photo-production cross section d{sigma}/dz({gamma} + p {yields} J/{psi} + X), where z = E{sub {psi}}/E{sub {gamma}} in the proton rest frame. The theoretical prediction based on the non-relativistic QCD (NRQCD) factorization formalism has a color-octet contribution which grows rapidly in the endpoint region, z {yields} 1, spoiling perturbation theory. In addition there are subleading operators which are enhanced by powers of 1/(1-z) and they must be resumed to all orders. Here an update of a systematic analysis is presented. The approach used to organize the endpoint behavior of the photo-production cross section is based on a combination of NRQCD and soft collinear effective theory. While a final result is not yet available, an intermediate result indicates that better agreement between theory and data will be achieved in this framework.

  1. Exclusive J/ψ and ϒ photoproduction and the low x gluon

    NASA Astrophysics Data System (ADS)

    Jones, S. P.; Martin, A. D.; Ryskin, M. G.; Teubner, T.

    2016-04-01

    We study exclusive vector meson photoproduction, γ p\\to V+p with V=J/\\psi or ϒ, at next-to-leading order (NLO) in collinear factorisation, in order to examine what may be learnt about the gluon distribution at very low x. We examine the factorisation scale dependence of the predictions. We argue that, using knowledge of the NLO corrections, terms enhanced by a large {ln}(1/ξ ) can be reabsorbed in the LO part by a choice of the factorisation scale. (In these exclusive processes ξ takes the role of Bjorken-x.) Then, the scale dependence coming from the remaining NLO contributions has no {ln}(1/ξ ) enhancements. As a result, we find that predictions for the amplitude of ϒ production are stable to within about ±15%. This will allow data for the exclusive process {pp}\\to p{{\\Upsilon }}p at the Large Hadron Collider (LHC), particularly from LHCb, to be included in global parton analyses to constrain the gluon parton distribution function (PDF) down to x∼ {10}-5. Moreover, the study of exclusive J/\\psi photoproduction indicates that the gluon density found in the recent global PDF analyses is too small at low x and low scales.

  2. A multispecies study to assess the toxic and genotoxic effect of pharmaceuticals: furosemide and its photoproduct.

    PubMed

    Isidori, Marina; Nardelli, Angela; Parrella, Alfredo; Pascarella, Luigia; Previtera, Lucio

    2006-05-01

    Pharmaceutical products for humans and animals, as well as their related metabolites end up in the aquatic environment after use. Recent investigations show that concentrations of pharmaceuticals are detectable in the order of ng/l-mug/l in municipal wastewater, groundwater and also drinking water. Little is known about the effects, and the hazard of long-term exposure to low concentrations of pharmaceuticals for non-target aquatic organisms. This study was designed to assess the ecotoxicity of furosemide, a potent diuretic agent, and its photoproduct in the aquatic environment. Bioassays were performed on bacteria, algae, rotifers and microcrustaceans to assess acute and chronic toxicity, while the SOS Chromotest and the Ames test were utilized to detect the genotoxic potential of the investigated compounds. A first approach to risk characterization was to calculate the environmental impact of furosemide by measured environmental concentration and predicted no effect concentration ratio (MEC/PNEC). To do so we used occurrence data reported in the literature and our toxicity results. The results showed that acute toxicity was in the order of mg/l for the crustaceans and absent for bacteria and rotifers. Chronic exposure to these compounds caused inhibition of growth population on the consumers, while the algae did not seem to be affected. A mutagenic potential was found for the photoproduct compared to the parental compound suggesting that byproducts ought to be considered in the environmental assessment of drugs. The risk calculated for furosemide suggested its harmlessness on the aquatic compartment. PMID:16213548

  3. Toxic and genotoxic impact of fibrates and their photoproducts on non-target organisms.

    PubMed

    Isidori, Marina; Nardelli, Angela; Pascarella, Luigia; Rubino, Maria; Parrella, Alfredo

    2007-07-01

    Lipid regulators have been detected in effluents from sewage treatment plants and surface waters from humans via excretion. This study was designed to assess the ecotoxicity of fibrates, lipid regulating agents. The following compounds were investigated: Bezafibrate, Fenofibrate and Gemfibrozil and their derivatives obtained by solar simulator irradiation. Bioassays were performed on bacteria, algae, rotifers and microcrustaceans to assess acute and chronic toxicity, while SOS Chromotest and Ames test were utilized to detect the genotoxic potential of the investigated compounds. The photoproducts were identified by their physical features and for the first risk evaluation, the environmental impact of parental compounds was calculated by Measured Environmental Concentrations (MEC) using the available data from the literature regarding drug occurrence in the aquatic environment and the Predicted No Effect Concentrations (PNEC) based on our toxicity data. The results showed that acute toxicity was in the order of dozens of mg/L for all the trophic levels utilized in bioassays (bacteria, rotifers, crustaceans). Chronic exposure to these compounds caused inhibition of growth population on rotifers and crustaceans while the algae seemed to be slightly affected by this class of pharmaceuticals. Genotoxic and mutagenic effects were especially found for the Gemfibrozil photoproduct suggesting that also byproducts have to be considered in the environmental risk of drugs. PMID:17320957

  4. Photoproducts formed in the photoyellowing of collagen in the presence of a fluorescent whitening agent.

    PubMed

    Dyer, Jolon M; Clerens, Stefan; Cornellison, Charisa D; Murphy, Chris J; Maurdev, George; Millington, Keith R

    2009-01-01

    Fibrous proteins discolor on exposure to the UV component of sunlight. This effect is exacerbated in the presence of fluorescent whitening agents (FWAs), which are often applied to textiles to improve product brightness. Tryptophan photoproducts have been identified as significant contributors to protein photoyellowing; however, the role of non-tryptophan-derived chromophores is less clear. In this study bovine collagen, containing no tryptophan residues, was irradiated in the presence and absence of the stilbene-derived FWA, 4,4'-bis(2-sulfostyryl)biphenyl (DSBP) and photoproducts were identified using mass spectrometry. Photoyellowing was found to be dependent on the presence of the FWA, attributed to amplified generation of reactive oxygen species (ROS), particularly hydroxyl radicals and peroxynitrite. Four key proteinaceous photomodifications contributing directly to photoyellowing were located in irradiated collagen pretreated with DSBP, namely dopa, nitrophenylalanine, nitrotyrosine and nitrohistidine. This represents the first direct characterization of the three nitrated residues in the photoyellowing of an isolated fibrous protein, and implicates the ROS, peroxynitrite, as a key contributor to protein photoyellowing. Direct oxidative modification of the FWA itself was also observed. This study demonstrates that, even in the absence of tryptophan residues, significant photomodification of protein residues leading to chromophore formation occurs in the presence of an FWA. PMID:19709380

  5. Quasi-free photoproduction of η-mesons off the deuteron

    NASA Astrophysics Data System (ADS)

    Jaegle, I.; Krusche, B.; Anisovich, A. V.; Bacelar, J. C. S.; Bantes, B.; Bartholomy, O.; Bayadilov, D. E.; Beck, R.; Beloglazov, Y. A.; Castelijns, R.; Crede, V.; Dieterle, M.; Dutz, H.; Elsner, D.; Ewald, R.; Frommberger, F.; Funke, C.; Gothe, R.; Gregor, R.; Gridnev, A. B.; Gutz, E.; Hillert, W.; Höffgen, S.; Hoffmeister, P.; Horn, I.; Junkersfeld, J.; Kalinowsky, H.; Kammer, S.; Keshelashvili, I.; Kleber, V.; Klein, Frank; Klein, Friedrich; Klempt, E.; Konrad, M.; Kotulla, M.; Lang, M.; Löhner, H.; Lopatin, I. V.; Lugert, S.; Maghrbi, Y.; Menze, D.; Mertens, T.; Messchendorp, J. G.; Metag, V.; Nikonov, V. A.; Nanova, M.; Novinski, D. V.; Novotny, R.; Oberle, M.; Ostrick, M.; Pant, L. M.; van Pee, H.; Pfeiffer, M.; Pheron, F.; Roy, A.; Sarantsev, A. V.; Schadmand, S.; Schmidt, C.; Schmieden, H.; Schoch, B.; Shende, S. V.; Sokhoyan, V.; Süle, A.; Sumachev, V. V.; Szczepanek, T.; Thoma, U.; Trnka, D.; Varma, R.; Walther, D.; Wendel, C.; Werthmüller, D.; Witthauer, L.

    2011-08-01

    Precise data for quasi-free photoproduction of η-mesons off the deuteron have been measured at the Bonn ELSA accelerator with the combined Crystal Barrel/TAPS detector for incident photon energies up to 2.5GeV. The η-mesons have been detected in coincidence with recoil protons and neutrons. Possible nuclear effects like Fermi motion and re-scattering can be studied via a comparison of the quasi-free reaction off the bound proton to η-production off the free proton. No significant effects beyond the folding of the free cross-section with the momentum distribution of the bound protons have been found. These Fermi motion effects can be removed by an analysis using the invariant mass of the η-nucleon pairs reconstructed from the final-state four-momenta of the particles. The total cross-section for quasi-free η-photoproduction off the neutron reveals even without correction for Fermi motion a pronounced bump-like structure around 1GeV of incident photon energy, which is not observed for the proton. This structure is even narrower in the invariant-mass spectrum of the η-neutron pairs. Position and width of the peak in the invariant-mass spectrum are W ≈ 1665 MeV and FWHM Γ ≈ 25 MeV. The data are compared to the results of different models.

  6. First measurement of direct $f_0(980)$ photoproduction on the proton

    SciTech Connect

    Battaglieri, Marco; De Vita, Raffaella; Szczepaniak, Adam

    2009-03-01

    We report on the results of the first measurement of exclusive $f_0(980)$ meson photoproduction on protons for $E_\\gamma=3.0 - 3.8$ GeV and $-t = 0.4-1.0$ GeV$^2$. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The resonance was detected via its decay in the $\\pi^+ \\pi^-$ channel by performing a partial wave analysis of the reaction $\\gamma p \\to p \\pi^+ \\pi^-$. Clear evidence of the $f_0(980)$ meson was found in the interference between $P$ and $S$ waves at $M_{\\pi^+ \\pi^-}\\sim 1$ GeV. The $S$-wave differential cross section integrated in the mass range of the $f_0(980)$ was found to be a factor of 50 smaller than the cross section for the $\\rho$ meson. This is the first time the $f_0(980)$ meson has been measured in a photoproduction experiment.

  7. Transverse Polarization of {Sigma}{sup +}(1189) in Photoproduction on a Hydrogen Target in CLAS

    SciTech Connect

    Nepali, Chandra S.

    2013-04-01

    Experimental results on the $\\Sigma^+(1189)$ hyperon transverse polarization in photoproduction on a hydrogen target using the CLAS detector at Jefferson laboratory are presented. The $\\Sigma^+(1189)$ was reconstructed in the exclusive reaction $\\gamma+p\\rightarrow K^{0}_{S} + \\Sigma^+(1189)$ via the $\\Sigma^{+} \\to p \\pi^{0}$ decay mode. The $K^{0}_S$ was reconstructed in the invariant mass of two oppositely charged pions with the $\\pi^0$ identified in the missing mass of the detected $p\\pi^+\\pi^-$ final state. Experimental data were collected in the photon energy range $E_{\\gamma}$ = 1.0-3.5 GeV ($\\sqrt{s}$ range 1.66-2.73 GeV). We observe a large negative polarization of up to 95%. As the mechanism of transverse polarization of hyperons produced in unpolarized photoproduction experiments is still not well understood, these results will help to distinguish between different theoretical models on hyperon production and provide valuable information for the searches of missing baryon resonances.

  8. Sunlight-induced degradation of fluoroquinolones in wastewater effluent: Photoproducts identification and toxicity.

    PubMed

    Sturini, Michela; Speltini, Andrea; Maraschi, Federica; Pretali, Luca; Ferri, Elida Nora; Profumo, Antonella

    2015-09-01

    The photodegradation of Ciprofloxacin (CIP), Enrofloxacin (ENR), Danofloxacin (DAN), Marbofloxacin (MAR) and Levofloxacin (LEV), five widely used fluoroquinolones (FQs), was studied in urban WWTP secondary effluent, under solar light. The degradation profiles and the kinetic constants were determined at the micrograms per litre levels (20-50 μg L(-1)). The photo-generated products were identified by high-pressure liquid chromatography coupled to electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The toxicity of the photoproducts was assessed by Vibrio fischeri light emission inhibition assay performed on irradiated and not-irradiated FQs solutions, at environmentally significant concentrations. Attention was focused on the evaluation of the photoproducts contribution to the overall biotoxic effect of these emerging pollutants. Data from chronic exposure experiments (24-48 h) were primarily considered. Results confirmed the major usefulness of chronic toxicity data with respect to the acute assay ones and proved the not negligible biotoxicity of the FQs photodegradation products. PMID:25966937

  9. Measurement of Direct f0(980) Photoproduction on the Proton

    NASA Astrophysics Data System (ADS)

    Battaglieri, M.; de Vita, R.; Szczepaniak, A. P.; Adhikari, K. P.; Aghasyan, M.; Amaryan, M. J.; Ambrozewicz, P.; Anghinolfi, M.; Asryan, G.; Avakian, H.; Bagdasaryan, H.; Baillie, N.; Ball, J. P.; Baltzell, N. A.; Batourine, V.; Bedlinskiy, I.; Bellis, M.; Benmouna, N.; Berman, B. L.; Bibrzycki, L.; Biselli, A. S.; Bookwalter, C.; Bouchigny, S.; Boiarinov, S.; Bradford, R.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Bültmann, S.; Burkert, V. D.; Calarco, J. R.; Careccia, S. L.; Carman, D. S.; Casey, L.; Chen, S.; Cheng, L.; Clinton, E.; Cole, P. L.; Collins, P.; Crabb, D.; Crannell, H.; Crede, V.; Cummings, J. P.; Dale, D.; Daniel, A.; Dashyan, N.; de Masi, R.; de Sanctis, E.; Degtyarenko, P. V.; Deur, A.; Dhamija, S.; Dharmawardane, K. V.; Dickson, R.; Djalali, C.; Dodge, G. E.; Donnelly, J.; Doughty, D.; Dugger, M.; Dzyubak, O. P.; Egiyan, H.; Egiyan, K. S.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fersch, R.; Forest, T. A.; Fradi, A.; Gabrielyan, M. Y.; Gan, L.; Garçon, M.; Gasparian, A.; Gavalian, G.; Gevorgyan, N.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Glamazdin, O.; Goett, J.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Gordon, C. I. O.; Gothe, R. W.; Graham, L.; Griffioen, K. A.; Guidal, M.; Guler, N.; Guo, L.; Gyurjyan, V.; Hadjidakis, C.; Hafidi, K.; Hakobyan, H.; Hakobyan, R. S.; Hanretty, C.; Hardie, J.; Hassall, N.; Heddle, D.; Hersman, F. W.; Hicks, K.; Hleiqawi, I.; Holtrop, M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Ito, M. M.; Jenkins, D.; Jo, H. S.; Johnstone, J. R.; Joo, K.; Juengst, H. G.; Kageya, T.; Kalantarians, N.; Keller, D.; Kellie, J. D.; Khandaker, M.; Khetarpal, P.; Kim, W.; Klein, A.; Klein, F. J.; Klimenko, A. V.; Konczykowski, P.; Kossov, M.; Krahn, Z.; Kramer, L. H.; Kubarovsky, V.; Kuhn, J.; Kuhn, S. E.; Kuleshov, S. V.; Kuznetsov, V.; Lachniet, J.; Laget, J. M.; Langheinrich, J.; Lawrence, D.; Lee, T.; Lesniak, L.; Li, Ji; Livingston, K.; Lowry, M.; Lu, H. Y.; MacCormick, M.; Malace, S.; Markov, N.; Mattione, P.; McCracken, M. E.; McKinnon, B.; Mecking, B. A.; Melone, J. J.; Mestayer, M. D.; Meyer, C. A.; Mibe, T.; Mikhailov, K.; Mineeva, T.; Minehart, R.; Mirazita, M.; Miskimen, R.; Mochalov, V.; Mokeev, V.; Moreno, B.; Moriya, K.; Morrow, S. A.; Moteabbed, M.; Munevar, E.; Mutchler, G. S.; Nadel-Turonski, P.; Nakagawa, I.; Nasseripour, R.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Niczyporuk, B. B.; Niroula, M. R.; Niyazov, R. A.; Nozar, M.; Osipenko, M.; Ostrovidov, A. I.; Park, K.; Park, S.; Pasyuk, E.; Paris, M.; Paterson, C.; Pereira, S. Anefalos; Pierce, J.; Pivnyuk, N.; Pocanic, D.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Prok, Y.; Protopopescu, D.; Raue, B. A.; Riccardi, G.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salamanca, J.; Salgado, C.; Sandorfi, A.; Santoro, J. P.; Sapunenko, V.; Schott, D.; Schumacher, R. A.; Serov, V. S.; Sharabian, Y. G.; Sharov, D.; Shvedunov, N. V.; Smith, E. S.; Smith, L. C.; Sober, D. I.; Sokhan, D.; Starostin, A.; Stavinsky, A.; Stepanyan, S.; Stepanyan, S. S.; Stokes, B. E.; Stoler, P.; Stopani, K. A.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Tedeschi, D. J.; Teymurazyan, A.; Tkabladze, A.; Tkachenko, S.; Todor, L.; Tur, C.; Ungaro, M.; Vineyard, M. F.; Vlassov, A. V.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Weygand, D. P.; Williams, M.; Wolin, E.; Wood, M. H.; Yegneswaran, A.; Yurov, M.; Zana, L.; Zhang, J.; Zhao, B.; Zhao, Z. W.

    2009-03-01

    We report on the results of the first measurement of exclusive f0(980) meson photoproduction on protons for Eγ=3.0-3.8GeV and -t=0.4-1.0GeV2. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The resonance was detected via its decay in the π+π- channel by performing a partial wave analysis of the reaction γp→pπ+π-. Clear evidence of the f0(980) meson was found in the interference between P and S waves at Mπ+π-˜1GeV. The S-wave differential cross section integrated in the mass range of the f0(980) was found to be a factor of about 50 smaller than the cross section for the ρ meson. This is the first time the f0(980) meson has been measured in a photoproduction experiment.

  10. Resummation of large endpoint corrections to color-octet J/{psi} photoproduction

    SciTech Connect

    Fleming, Sean; Leibovich, Adam K.; Mehen, Thomas

    2006-12-01

    An unresolved problem in J/{psi} phenomenology is a systematic understanding of the differential photoproduction cross section, d{sigma}/dz[{gamma}+p{yields}J/{psi}+X], where z=E{sub {psi}}/E{sub {gamma}} in the proton rest frame. In the nonrelativistic QCD (NRQCD) factorization formalism, fixed-order perturbative calculations of color-octet mechanisms suffer from large perturbative and nonperturbative corrections that grow rapidly in the endpoint region, z{yields}1. In this paper, NRQCD and soft collinear effective theory are combined to resum these large corrections to the color-octet photoproduction cross section. We derive a factorization theorem for the endpoint differential cross section involving the parton distribution function and the color-octet J/{psi} shape functions. A one-loop matching calculation explicitly confirms our factorization theorem at next-to-leading order. Large perturbative corrections are resummed using the renormalization group. The calculation of the color-octet contribution to d{sigma}/dz is in qualitative agreement with data. Quantitative tests of the universality of color-octet matrix elements require improved knowledge of shape functions entering these calculations as well as resummation of the color-singlet contribution which accounts for much of the total cross section and also peaks near the endpoint.

  11. Resummation of Large Endpoint Corrections to Color-Octet J/psi Photoproduction

    SciTech Connect

    Sean Fleming; Adam K. Leibovich; Thomas Mehen

    2006-07-27

    An unresolved problem in J/{psi} phenomenology is a systematic understanding of the differential photoproduction cross section, d{sigma}/dz [{gamma} + p {yields} J/{psi} + X], where z = E{sub {psi}}/E{sub {gamma}} in the proton rest frame. In the non-relativistic QCD (NRQCD) factorization formalism, fixed-order perturbative calculations of color-octet mechanisms suffer from large perturbative and nonperturbative corrections that grow rapidly in the endpoint region, z {yields} 1. In this paper, NRQCD and soft collinear effective theory are combined to resum these large corrections to the color-octet photoproduction cross section. We derive a factorization theorem for the endpoint differential cross section involving the parton distribution function and the color-octet J/{psi} shape functions. A one loop matching calculation explicitly confirms our factorization theorem at next-to-leading order. Large perturbative corrections are resummed using the renormalization group. The calculation of the color-octet contribution to d{sigma}/dz is in qualitative agreement with data. Quantitative tests of the universality of color-octet matrix elements require improved knowledge of shape functions entering these calculations as well as resummation of the color-singlet contribution which accounts for much of the total cross section and also peaks near the endpoint.

  12. [UV photolysis of propranolol in aqueous solution: mechanism and toxicity of photoproducts].

    PubMed

    Peng, Na; Wang, Kai-Feng; Liu, Guo-Guang; Zeng, Ling-Ze; Yao, Kun; Lu, Wen-Ying

    2014-10-01

    This paper studied the phtodegradation behavior, mechanism and security of propranolol (PRO) in water under ultraviolet irradiation using the high pressure mercury lamp. The photodegradation mechanism was verified by reactive oxygen species (ROS) quenching method, and the photoproducts security was evaluated by luminescent bacteria toxicity test. The results showed that the rate of photolysis (k) of PRO decreased with increasing initial concentration, and showed a significant negative correlation (r2 > 0.95). The increasing k value was also accompanied with higher pH of the solution, and the k values were 0.0953-0.267 min(-1) under pH 5-9. ROS quenching experiments showed that the PRO UV photolysis process included a triplet PRO (3PRO*) direct photolysis participation, and self-sensitized photolysis participation caused by hydroxyl radical (·OH) and singlet oxygen (1O2). Direct photolysis rate was greater than the rate of self-sensitized photolysis. The result of 1O2 steady concentration measured by FFA as the probe was consistent with the quenching method. The toxicity evaluation illustrated the formation of some intermediate photoproducts, which were more toxic than PRO. PMID:25693385

  13. Development of 4π Electro-Magnetic Calorimeter Complex Forest for Neutral Meson Photo-Production Experiments

    NASA Astrophysics Data System (ADS)

    Suzuki, K.; Fujimura, H.; Fukasawa, H.; Hashimoto, R.; Ishikawa, T.; Kasagi, J.; Kuwasaki, S.; Mochizuki, K.; Nawa, K.; Okada, Y.; Onodera, Y.; Sato, M.; Shimizu, H.; Yamazaki, H.; Kawano, A.; Sakamoto, Y.; Maeda, K.

    2010-10-01

    A large solid angle electro-magnetic calorimeter system, FOREST, has been constructed at LNB-Sendai to study the π0 and η photo-production reactions. FOREST consists of three electro-magnetic calorimeters: pure CsI crystals, Lead/SciFi blocks and Lead Glass Cherenkov counters. It covers about 90% of the total solid angle.

  14. Hydrogen peroxide and superoxide photoproduction in diverse marine waters: A simple proxy for estimating direct CO2 photochemical fluxes

    NASA Astrophysics Data System (ADS)

    Powers, Leanne C.; Miller, William L.

    2015-09-01

    The photoproduction of H2O2 and CO2 exhibits a well-defined relationship with an average CO2:H2O2 molar ratio of 6.6 ± 1.8 as determined in a variety of marine waters ranging from a dark tidal creek to clear offshore stations near the Gulf Stream. Even when corrected for photobleaching, accumulation of both H2O2 and CO2 was not linear beyond 12 h of constant irradiation, with interval rates indicating that production efficiency for both products decreased with increasing photon dose. Direct measurements of O2- photoproduction, together with its dark thermal decay to H2O2, indicate that O2- may be the better proxy for photochemical dissolved organic matter oxidation to CO2. Given the very short irradiation times needed to determine O2- production rates (~2-5 min), determination of O2- photoproduction may provide robust estimates for initial CO2 photoproduction rates even in blue water, allowing greatly improved estimates for the global significance of dissolved organic carbon photooxidation.

  15. ρ0 photoproduction in ultraperipheral relativistic heavy ion collisions at sNN=200 GeV

    NASA Astrophysics Data System (ADS)

    Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Anderson, B. D.; Arkhipkin, D.; Averichev, G. S.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baudot, J.; Baumgart, S.; Beavis, D. R.; Bellwied, R.; Benedosso, F.; Betts, R. R.; Bhardwaj, S.; Bhasin, A.; Bhati, A. K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Blyth, S.-L.; Bombara, M.; Bonner, B. E.; Botje, M.; Bouchet, J.; Braidot, E.; Brandin, A. V.; Bueltmann, S.; Burton, T. P.; Bystersky, M.; Cai, X. Z.; Caines, H.; Sánchez, M. Calderón De La Barca; Callner, J.; Catu, O.; Cebra, D.; Cervantes, M. C.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Choi, K. E.; Christie, W.; Chung, S. U.; Clarke, R. F.; Codrington, M. J. M.; Coffin, J. P.; Cormier, T. M.; Cosentino, M. R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Dash, S.; Daugherity, M.; Moura, M. M. De; Dedovich, T. G.; Dephillips, M.; Derevschikov, A. A.; Souza, R. Derradi De; Didenko, L.; Dietel, T.; Djawotho, P.; Dogra, S. M.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, F.; Dunlop, J. C.; Mazumdar, M. R. Dutta; Edwards, W. R.; Efimov, L. G.; Elhalhuli, E.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Eun, L.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Feng, A.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Fu, J.; Gagliardi, C. A.; Gaillard, L.; Ganti, M. S.; Garcia-Solis, E.; Ghazikhanian, V.; Ghosh, P.; Gorbunov, Y. N.; Gordon, A.; Grebenyuk, O.; Grosnick, D.; Grube, B.; Guertin, S. M.; Guimaraes, K. S. F. F.; Gupta, A.; Gupta, N.; Guryn, W.; Haag, B.; Hallman, T. J.; Hamed, A.; Harris, J. W.; He, W.; Heinz, M.; Henry, T. W.; Hepplemann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffman, A. M.; Hoffmann, G. W.; Hofman, D. J.; Hollis, R. S.; Horner, M. J.; Huang, H. Z.; Hughes, E. W.; Humanic, T. J.; Igo, G.; Iordanova, A.; Jacobs, P.; Jacobs, W. W.; Jakl, P.; Jin, F.; Jones, P. G.; Judd, E. G.; Kabana, S.; Kajimoto, K.; Kang, K.; Kapitan, J.; Kaplan, M.; Keane, D.; Kechechyan, A.; Kettler, D.; Khodyrev, V. Yu.; Kiryluk, J.; Kisiel, A.; Klein, S. R.; Knospe, A. G.; Kocoloski, A.; Koetke, D. D.; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kouchpil, V.; Kowalik, K. L.; Kravtsov, P.; Kravtsov, V. I.; Krueger, K.; Kuhn, C.; Kumar, A.; Kurnadi, P.; Lamont, M. A. C.; Landgraf, J. M.; Lange, S.; Lapointe, S.; Laue, F.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, C.-H.; Levine, M. J.; Li, C.; Li, Q.; Li, Y.; Lin, G.; Lin, X.; Lindenbaum, S. J.; Lisa, M. A.; Liu, F.; Liu, H.; Liu, J.; Liu, L.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Love, W. A.; Lu, Y.; Ludlam, T.; Lynn, D.; Ma, G. L.; Ma, J. G.; Ma, Y. G.; Mahapatra, D. P.; Majka, R.; Mangotra, L. K.; Manweiler, R.; Margetis, S.; Markert, C.; Matis, H. S.; Matulenko, Yu. A.; McShane, T. S.; Meschanin, A.; Millane, J.; Miller, M. L.; Minaev, N. G.; Mioduszewski, S.; Mischke, A.; Mitchell, J.; Mohanty, B.; Morozov, D. A.; Munhoz, M. G.; Nandi, B. K.; Nattrass, C.; Nayak, T. K.; Nelson, J. M.; Nepali, C.; Netrakanti, P. K.; Ng, M. J.; Nogach, L. V.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Okada, H.; Okorokov, V.; Olson, D.; Pachr, M.; Pal, S. K.; Panebratsev, Y.; Pavlinov, A. I.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Phatak, S. C.; Planinic, M.; Pluta, J.; Poljak, N.; Porile, N.; Poskanzer, A. M.; Potekhin, M.; Potukuchi, B. V. K. S.; Prindle, D.; Pruneau, C.; Pruthi, N. K.; Putschke, J.; Qattan, I. A.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Relyea, D.; Ridiger, A.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Rose, A.; Roy, C.; Ruan, L.; Russcher, M. J.; Rykov, V.; Sahoo, R.; Sakrejda, I.; Sakuma, T.; Salur, S.; Sandweiss, J.; Sarsour, M.; Schambach, J.; Scharenberg, R. P.; Schmitz, N.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shabetai, A.; Shahaliev, E.; Shao, M.; Sharma, M.; Shi, X.-H.; Sichtermann, E. P.; Simon, F.; Singaraju, R. N.; Skoby, M. J.; Smirnov, N.; Snellings, R.; Sorensen, P.; Sowinski, J.; Speltz, J.; Spinka, H. M.; Srivastava, B.; Stadnik, A.; Stanislaus, T. D. S.; Staszak, D.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Subba, N. L.; Sumbera, M.; Sun, X. M.; Sun, Z.; Surrow, B.; Symons, T. J. M.; Toledo, A. Szanto De; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thein, D.; Thomas, J. H.; Tian, J.; Timmins, A. R.; Timoshenko, S.; Tokarev, M.; Trainor, T. A.; Tram, V. N.; Trattner, A. L.; Trentalange, S.; Tribble, R. E.; Tsai, O. D.; Ulery, J.; Ullrich, T.; Underwood, D. G.; Buren, G. Van; Kolk, N. Van Der; Leeuwen, M. Van; Molen, A. M. Vander; Varma, R.; Vasconcelos, G. M. S.; Vasilevski, I. M.; Vasiliev, A. N.; Vernet, R.; Videbaek, F.; Vigdor, S. E.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Wada, M.; Waggoner, W. T.; Wang, F.; Wang, G.; Wang, J. S.; Wang, Q.; Wang, X.; Wang, X. L.; Wang, Y.; Webb, J. C.; Westfall, G. D.; , C. Whitten, Jr.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, J.; Wu, Y.; Xu, N.; Xu, Q. H.; Xu, Z.; Yepes, P.; Yoo, I.-K.; Yue, Q.; Zawisza, M.; Zbroszczyk, H.; Zhan, W.; Zhang, H.; Zhang, S.; Zhang, W. M.; Zhang, Y.; Zhang, Z. P.; Zhao, Y.; Zhong, C.; Zhou, J.; Zoulkarneev, R.; Zoulkarneeva, Y.; Zuo, J. X.

    2008-03-01

    Photoproduction reactions occur when the electromagnetic field of a relativistic heavy ion interacts with another heavy ion. The STAR Collaboration presents a measurement of ρ0 and direct π+π- photoproduction in ultraperipheral relativistic heavy ion collisions at sNN=200 GeV. We observe both exclusive photoproduction and photoproduction accompanied by mutual Coulomb excitation. We find a coherent cross section of σ(AuAu→Au*Au*ρ0)=530±19(stat.)±57(syst.) mb, in accord with theoretical calculations based on a Glauber approach, but considerably below the predictions of a color dipole model. The ρ0 transverse momentum spectrum (pT2) is fit by a double exponential curve including both coherent and incoherent coupling to the target nucleus; we find σinc/σcoh=0.29±0.03(stat.)±0.08(syst.). The ratio of direct π+π- to ρ0 production is comparable to that observed in γp collisions at HERA and appears to be independent of photon energy. Finally, the measured ρ0 spin helicity matrix elements agree within errors with the expected s-channel helicity conservation.

  16. Significant Increase in Hydrogen Photoproduction Rates and Yields by Wild-Type Algae is Detected at High Photobioreactor Gas Phase Volume (Fact Sheet)

    SciTech Connect

    Not Available

    2012-07-01

    This NREL Hydrogen and Fuel Cell Technical Highlight describes how hydrogen photoproduction activity in algal cultures can be improved dramatically by increasing the gas-phase to liquid-phase volume ratio of the photobioreactor. NREL, in partnership with subcontractors from the Institute of Basic Biological Problems in Pushchino, Russia, demonstrated that the hydrogen photoproduction rate in algal cultures always decreases exponentially with increasing hydrogen partial pressure above the culture. The inhibitory effect of high hydrogen concentrations in the photobioreactor gas phase on hydrogen photoproduction by algae is significant and comparable to the effect observed with some anaerobic bacteria.

  17. A TeGM6-4r antigen-based immunochromatographic test (ICT) for animal trypanosomosis.

    PubMed

    Nguyen, Thu-Thuy; Ruttayaporn, Ngasaman; Goto, Yasuyuki; Kawazu, Shin-ichiro; Sakurai, Tatsuya; Inoue, Noboru

    2015-11-01

    Animal trypanosomosis is a disease that is distributed worldwide which results in huge economic losses due to reduced animal productivity. Endemic regions are often located in the countryside where laboratory diagnosis is costly or inaccessible. The establishment of simple, effective, and accurate field tests is therefore of great interest to the farming and veterinary sectors. Our study aimed to develop a simple, rapid, and sensitive immunochromatographic test (ICT) for animal trypanosomosis utilizing the recombinant tandem repeat antigen TeGM6-4r, which is conserved amongst salivarian trypanosome species. In the specificity analysis, TeGM6-4r/ICT detected all of Trypanosoma evansi-positive controls from experimentally infected water buffaloes. As expected, uninfected controls tested negative. All sera samples collected from Tanzanian and Ugandan cattle that were Trypanosoma congolense- and/or Trypanosoma vivax-positive by microscopic examination of the buffy coat were found to be positive by the newly developed TeGM6-4r/ICT, which was comparable to results from TeGM6-4r/ELISA (kappa coefficient [κ] = 0.78). TeGM6/ICT also showed substantial agreement with ELISA using Trypanosoma brucei brucei (κ = 0.64) and T. congolense (κ = 0.72) crude antigen, suggesting the high potential of TeGM6-4r/ICT as a field diagnostic test, both for research purposes and on-site diagnosis of animal trypanosomosis. PMID:26290217

  18. Photoproduction of ω mesons off nuclei and impact of polarization on the meson-nucleon interaction

    SciTech Connect

    Chudakov, Eugene A.; Gevorkyan, Sergey; Somov, Alexander

    2016-01-01

    We consider photoproduction of omega mesons off complex nuclei to study interactions of transversely and longitudinally polarized vector mesons with nucleons. Whereas the total cross section for interactions of the transversely polarized vector mesons with nucleons sigma_T = sigma(V_T N) can be obtained from coherent photoproduction, measurements of vector meson photoproduction in the incoherent region provide a unique opportunity to extract the not-yet-measured total cross section for longitudinally polarized mesons sigma_L = sigma(V_L N). The predictions for the latter strongly depend on the theoretical approaches. This work is stimulated by the construction of the new experiment GlueX at Jefferson Lab, designed to study the photoproduction of mesons in a large beam energy range up to 12 GeV.

  19. Study of Strangeness Photoproduction on the Neutron in the Threshold Region

    NASA Astrophysics Data System (ADS)

    Kanda, Hiroki; Beckford, Brian; Fujibayashi, Takeji; Fujii, Takao; Fujii, Yu; Futatsukawa, Kenta; Gogami, Toshiyuki; Han, Yun-Cheng; Hashimoto, Osamu; Hirose, Kentaro; Honda, Ryotaro; Hosomi, Kenji; Iguchi, Alan; Ishikawa, Takatsugu; Kaneko, Yusuke; Kaneta, Masashi; Kasai, Yuma; Kawama, Daisuke; Kawasaki, Taito; Kimura, Chigusa; Kiyokawa, Shogo; Koike, Takeshi; Maeda, Kazushige; Maruta, Tomofumi; Maruyama, Nayuta; Matsubara, Masao; Miwa, Koji; Miyagi, Yohei; Nagao, Sho; Nakamura, Satoshi N.; Okuyama, Akira; Suzuki, Kotaku; Tamae, Tadaaki; Tamura, Hirokazu; Terada, Nobuhiro; Tsukada, Kyo; Wang, Tie-Shang; Yamamoto, Fumiya; Yamamoto, Takeshi O.; Yamazaki, Hirohito

    2013-08-01

    Photoproduction of the neutral kaon on the deuteron has been investigated at the Research Center for Electron Photon Science, Tohoku University. We constructed the Neutral Kaon Spectrometer-2 for the detection of charged particles from the decay of the neutral kaon and the hyperon. We obtained a momentum distribution of K 0 with the inclusive measurement. It was consistent with the previous measurement. The total cross section of γ + d → K 0 + Λ + p was estimated from the measured integral cross section of γ + d → Λ + X. The total cross section with respect to the photon energy was compared with the theoretical calculations. It favored the Saclay-Lyon A model calculation with the ratio of the neutral to charged coupling constants of the axial-vector meson, K 1, as ~ -1.5. The energy dependence and the magnitude of the total cross section were similar to the total cross section of γ + p → K + Λ.

  20. Polarization Transfer in Wide-Angle Compton Scattering and Single-Pion Photoproduction from the Proton

    NASA Astrophysics Data System (ADS)

    Fanelli, C.; Cisbani, E.; Hamilton, D. J.; Salmé, G.; Wojtsekhowski, B.; Ahmidouch, A.; Annand, J. R. M.; Baghdasaryan, H.; Beaufait, J.; Bosted, P.; Brash, E. J.; Butuceanu, C.; Carter, P.; Christy, E.; Chudakov, E.; Danagoulian, S.; Day, D.; Degtyarenko, P.; Ent, R.; Fenker, H.; Fowler, M.; Frlez, E.; Gaskell, D.; Gilman, R.; Horn, T.; Huber, G. M.; de Jager, C. W.; Jensen, E.; Jones, M. K.; Kelleher, A.; Keppel, C.; Khandaker, M.; Kohl, M.; Kumbartzki, G.; Lassiter, S.; Li, Y.; Lindgren, R.; Lovelace, H.; Luo, W.; Mack, D.; Mamyan, V.; Margaziotis, D. J.; Markowitz, P.; Maxwell, J.; Mbianda, G.; Meekins, D.; Meziane, M.; Miller, J.; Mkrtchyan, A.; Mkrtchyan, H.; Mulholland, J.; Nelyubin, V.; Pentchev, L.; Perdrisat, C. F.; Piasetzky, E.; Prok, Y.; Puckett, A. J. R.; Punjabi, V.; Shabestari, M.; Shahinyan, A.; Slifer, K.; Smith, G.; Solvignon, P.; Subedi, R.; Wesselmann, F. R.; Wood, S.; Ye, Z.; Zheng, X.

    2015-10-01

    Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θcmp=70 ° . The longitudinal transfer KLL, measured to be 0.645 ±0.059 ±0.048 , where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ˜3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude.

  1. Φ-Meson Photoproduction with Linearly Polarized Photons at Threshold Energies

    SciTech Connect

    Salamanca, Julian; Cole, Philip L

    2007-10-01

    The observables provided by linearly-polarized photons are of interest in delineating the contributions of the various hadronic processes giving rise to vector meson photoproduction. In particular, we describe how Φ-meson production affords an incisive tool for exploring the nature of the parity exchange at threshold energies, the strangeness content of proton, as well as extracting signatures for the violation of Okubo-Zweig-Iizuka observation (OZI rule). Our goal is to study the γp → Φp reaction, with Φ → K+K-, in the photon energy range of 1.7 to 2.1 GeV by using the Coherent Linear Bremsstrahlung Facility in Hall B of Jefferson Laboratory, Newport News, VA. The data were collected during the g8b run in the summer of 2005.

  2. Helicity asymmetry E measurement for single π0 photoproduction with a frozen spin target

    NASA Astrophysics Data System (ADS)

    Iwamoto, Hideko; CLAS Collaboration

    2012-04-01

    The helicity asymmetry for single neutral pion photoproduction was measured using the CLAS detector in Hall B at the Thomas Jefferson National Accelerator Facility. This measurement used longitudinally polarized protons and circularly polarized photons with photon energis between 0.35 GeV to 2.4 GeV. The target was a frozen-spin butanol (C4H9OH) target, polarized at about 85%. The helicity asymmetry E for the γp→pπ0 was measured with missing-mass technique at the high statistics of about 12×106 events. The experimental results are compared to three available theoretical predictions, SAID, MAID, and EBAC. The preliminary results are in good agreement with the model calculations at low Eγ energy bins. However, a significant deviation is observed at high energy bins. Therefore, the new data will help to constrain the parameters of the theoretical models.

  3. K*0Σ+ Photoproduction from Threshold to 3.0 GeV

    NASA Astrophysics Data System (ADS)

    Hwang, Sanghoon; Ahn, Jung Keun; Hicks, K.

    2013-03-01

    The CLAS collaboration and the CBELSA/TAPS collaboration reported the differential cross section data for K*0 photoproduction, and found that the t-channel K exchange dominates the production amplitudes at small scattering angles. The measurement of forward-angle parity spin asymmetry for the γ p → K*0Σ+ reaction, where the theoretical calculations show an unambiguous signal, would establish the role of the κ(800). The γ p → K*0Σ+ reaction, where the Σ+ was identified through missing mass, on a liquid hydrogen target was measured at the LEPS detector in the energy from threshold to 3.0 GeV by using a linearly polarized photon beam at SPring-8. Decay angular distributions in the rest frame of the K + π - system were fit to extract spin-density matrix elements of the K*0 decay.

  4. Transverse Polarization of Σ+(1189) in Photoproduction on Hydrogen Target with CLAS

    NASA Astrophysics Data System (ADS)

    Nepali, Chandra; Amaryan, Moskov; CLAS Collaboration

    2011-10-01

    Experimental results on the measurement of Σ+(1189) hyperon transverse polarization in photoproduction on a hydrogen target with CLAS are presented for the first time. The Σ+(1189) is reconstructed in the exclusive reaction γ + p -->KSΣ+(1189) via the decay Σ+ --> pπ0 . The KS is reconstructed in the invariant mass of two oppositely charged pions and π0 is identified in the missing mass of detected proton, π+ and π-. We observe significant negative polarization of as much as 60 %. Experimental data are collected in the photon energy range 1-3.5 GeV. As the mechanism of large transverse polarization of hyperons produced in unpolarized hadro-, and photo production experiments is still not well understood, these results will help to distinguish between different theoretical models on hyperon production. Current status of the analysis and future prospects are discussed.

  5. Diffractive dijet photoproduction in ultraperipheral collisions at the LHC in next-to-leading order QCD

    NASA Astrophysics Data System (ADS)

    Guzey, V.; Klasen, M.

    2016-04-01

    We make predictions for the cross sections of diffractive dijet photoproduction in pp, pA and AA ultraperipheral collisions (UPCs) at the LHC during Runs 1 and 2 using next-to-leading perturbative QCD. We find that the resulting cross sections are sufficiently large and, compared to lepton-proton scattering at HERA, have an enhanced sensitivity to small observed momentum fractions in the diffractive exchange, commonly denoted {z}_{P}^{jets} , and an unprecedented reach in the invariant mass of the photon-nucleon system W. We examine two competing schemes of diffractive QCD factorization breaking, which assume either a global suppression factor or a suppression for resolved photons only and demonstrate that the two scenarios can be distinguished by the nuclear dependence of the distributions in the observed parton momentum fraction in the photon x γ jets.

  6. Extraction of electromagnetic properties of the {Delta}(1232) excitation from pion photoproduction

    SciTech Connect

    Wilbois, T.; Wilhelm, P.; Arenhoevel, H.

    1998-01-01

    Several methods for the treatment of pion photoproduction in the region of the {Delta}(1232) resonance are discussed, in particular the effective Lagrangian approach and the speed plot analysis are compared to a dynamical treatment. As a main topic, we discuss the extraction of the genuine resonance parts of the magnetic dipole and electric quadrupole multipoles of the electromagnetic excitation of the resonance. To this end, we try to relate the various values for the ratio R{sub EM} of the E2 to M1 multipole excitation strengths for the {Delta}(1232) resonance as extracted by the different methods to corresponding ratios of a dynamical model. Moreover, it is confirmed that all methods for extracting resonance properties suffer from an unitary ambiguity which is due to some phenomenological contributions entering the models. {copyright} {ital 1998} {ital The American Physical Society}

  7. Exclusive photoproduction of J/ψ and ψ(2S) in pp and AA collisions

    SciTech Connect

    Cisek, Anna; Schäfer, Wolfgang; Szczurek, Antoni

    2015-04-10

    The amplitude for γp → J/ψp(γp → ψ'p) is calculated in a pQCD k{sub ⊥}-factorization approach. The total cross section for this process is calculated for different unintegrated gluon distributions and compared with the HERA data and the data extracted recently by the LHCb collaboration. The amplitude for γp → J/ψp(γp → ψ'p) is used to predict the cross section for exclusive photoproduction of the J/ψ(ψ') meson in proton-proton and nucleus-nucleus collisions. In the pp case, compared to earlier calculations we include both Dirac and Pauli electromagnetic form factors. We also discuss the dependence of nuclear shadowing on the charmonium state.

  8. Appearance of p-odd nuclear forces in photoproduction of pions on /sup 6/Li

    SciTech Connect

    Rekalo, M.P.

    1986-01-01

    This paper studies P-odd effects in the photoproduction of pions on Li-6 nuclei, ..gamma.. + Li-6 ..-->.. ..pi../sup +/ + He-6. Collisions of linearly and circularly polarized photons with a polarized nuclear target are studied, and in addition both vectorial and tensorial polarization are taken into account. It is shown that in the general case P-odd effects in ..gamma.. + Li-6..--> pi../sup +/ + He-6 are characterized by 18 real structure functions, which determine different P-odd asymmetries in the angular distribution of the pions. The structure functions in their turn depend on different products of three p-even and three p-odd amplitudes of the process.

  9. DIFFERENTIAL CROSS SECTION ANALYSIS IN KAON PHOTOPRODUCTION USING ASSOCIATED LEGENDRE POLYNOMIALS

    SciTech Connect

    P. T. P. HUTAURUK, D. G. IRELAND, G. ROSNER

    2009-04-01

    Angular distributions of differential cross sections from the latest CLAS data sets,6 for the reaction γ + p→K+ + Λ have been analyzed using associated Legendre polynomials. This analysis is based upon theoretical calculations in Ref. 1 where all sixteen observables in kaon photoproduction can be classified into four Legendre classes. Each observable can be described by an expansion of associated Legendre polynomial functions. One of the questions to be addressed is how many associated Legendre polynomials are required to describe the data. In this preliminary analysis, we used data models with different numbers of associated Legendre polynomials. We then compared these models by calculating posterior probabilities of the models. We found that the CLAS data set needs no more than four associated Legendre polynomials to describe the differential cross section data. In addition, we also show the extracted coefficients of the best model.

  10. Break-up and Coherent Photoproduction of {eta} Mesons on the Deuteron

    SciTech Connect

    Hoffmann-Rothe, P.; Breuer, M.; Hourany, E.; Rigney, M.; Ajaka, J.; Berrier-Ronsin, G.; Didelez, J.; Rosier, L.; Hey, J.; Anton, G.; Beulertz, W.; Bock, A.; Helbing, K.; Krebeck, M.; Edel, G.v.; Maass, R.; Schumacher, M.; Smend, F.; Blanpied, G.; Preedom, B.; Richie, B.; Saghai, B.; Arends, J.

    1997-06-01

    We present new break-up and coherent data for {eta} meson photoproduction on the deuteron, using a deuterium target and tagged bremsstrahlung photons up to 1GeV. The differential cross sections for the coherent process were measured from threshold to 800MeV. They are much smaller than those previously reported. The break-up channel provides a direct measurement of the neutron to proton differential cross section ratios. At the S{sub 11}(1535) resonance peak, {sigma}{sub n}/{sigma}{sub p}=0.68{plus_minus}0.06 leading to an isoscalar to isovector amplitude ratio of A{sub s}/A{sub {upsilon}}=0.096{plus_minus}0.02 . {copyright} {ital 1997} {ital The American Physical Society}

  11. First measurement of coherent $\\phi$-meson photoproduction on deuteron at low energies

    SciTech Connect

    Tsutomu Mibe; Haiyan Gao; Kenneth Hicks; Kevin Kramer; Stepan Stepanyan; David Tedeschi; Moscov Amaryan; Pawel Ambrozewicz; Marco Anghinolfi; G. Asryan; Gerard Audit; Harutyun Avakian; Hovhannes Baghdasaryan; Nathan Baillie; Jacques Ball; Nathan Baltzell; Marco Battaglieri; Ivan Bedlinski; Ivan Bedlinskiy; Matthew Bellis; Nawal Benmouna; Barry Berman; Angela Biselli; Lukasz Blaszczyk; Sylvain Bouchigny; Sergey Boyarinov; Robert Bradford; Derek Branford; William Briscoe; William Brooks; Stephen Bueltmann; Volker Burkert; Cornel Butuceanu; John Calarco; Sharon Careccia; Daniel Carman; Shifeng Chen; Philip Cole; Patrick Collins; Philip Coltharp; Donald Crabb; Hall Crannell; Volker Crede; John Cummings; Natalya Dashyan; Rita De Masi; Raffaella De Vita; Enzo De Sanctis; Pavel Degtiarenko; Alexandre Deur; Kahanawita Dharmawardane; Richard Dickson; Chaden Djalali; Gail Dodge; Joseph Donnelly; David Doughty; Michael Dugger; Oleksandr Dzyubak; Hovanes Egiyan; Kim Egiyan; Lamiaa Elfassi; Latifa Elouadrhiri; Paul Eugenio; Gleb Fedotov; Gerald Feldman; Herbert Funsten; Michel Garcon; Gagik Gavalian; Gerard Gilfoyle; Kevin Giovanetti; Francois-Xavier Girod; John Goetz; Atilla Gonenc; Christopher Gordon; Ralf Gothe; Keith Griffioen; Michel Guidal; Nevzat Guler; Lei Guo; Vardan Gyurjyan; Cynthia Hadjidakis; Kawtar Hafidi; Hayk Hakobyan; Rafael Hakobyan; Charles Hanretty; John Hardie; F. Hersman; Ishaq Hleiqawi; Maurik Holtrop; Charles Hyde; Charles Hyde-Wright; Yordanka Ilieva; David Ireland; Boris Ishkhanov; Eugeny Isupov; Mark Ito; David Jenkins; Hyon-Suk Jo; John Johnstone; Kyungseon Joo; Henry Juengst; Narbe Kalantarians; James Kellie; Mahbubul Khandaker; Wooyoung Kim; Andreas Klein; Franz Klein; Alexei Klimenko; Mikhail Kossov; Zebulun Krahn; Laird Kramer; V. Kubarovsky; Joachim Kuhn; Sebastian Kuhn; Sergey Kuleshov; Viacheslav Kuznetsov; Jeff Lachniet; Jean Laget; Jorn Langheinrich; David Lawrence; Tsung-shung Lee; Ji Li; Kenneth Livingston; Haiyun Lu; Marion MacCormick; Claude Marchand; Nikolai Markov; Paul Mattione; Bryan McKinnon; Bernhard Mecking; Joseph Melone; Mac Mestayer; Curtis Meyer; Konstantin Mikhaylov; Ralph Minehart; Marco Mirazita; Rory Miskimen; Viktor Mokeev; Kei Moriya; Steven Morrow; M. Moteabbed; E. Munevar; Gordon Mutchler; P. Nadel-Turonski; Rakhsha Nasseripour; Silvia Niccolai; Gabriel Niculescu; Maria-Ioana Niculescu; Bogdan Niczyporuk; Megh Niroula; Rustam Niyazov; Mina Nozar; Mikhail Osipenko; Alexander Ostrovidov; K. Park; Evgueni Pasyuk; Craig Paterson; S. Anefalos Pereira; Joshua Pierce; Nikolay Pivnyuk; Dinko Pocanic; Oleg Pogorelko; S. Pozdniakov; John Price; Yelena Prok; Dan Protopopescu; Brian Raue; Gregory Riccardi; Giovanni Ricco; Marco Ripani; Barry Ritchie; Federico Ronchetti; Guenther Rosner; Patrizia Rossi; Franck Sabatie; Julian Salamanca; Carlos Salgado; Joseph Santoro; Vladimir Sapunenko; Reinhard Schumacher; Vladimir Serov; Youri Sharabian; Dmitri Sharov; Nikolay Shvedunov; Elton Smith; Lee Smith; Daniel Sober; Daria Sokhan; A. Stavinsky; Samuel Stepanyan; B.E. Stokes; Paul Stoler; I.I. Strakovsky; Steffen Strauch; Mauro Taiuti; Ulrike Thoma; Avtandil Tkabladze; Svyatoslav Tkachenko; Luminita Todor; Clarisse Tur; Maurizio Ungaro; Michael Vineyard; Alexander Vlassov; Daniel Watts; Lawrence Weinstein; Dennis Weygand; M. Williams; Elliott Wolin; Michael Wood; Amrit Yegneswaran; Lorenzo Zana; Jixie Zhang; Bo Zhao; Zhiwen Zhao

    2007-11-01

    The cross section and decay angular distributions for the coherent \\phi meson photoproduction on the deuteron have been measured for the first time up to a squared four-momentum transfer t =(p_{\\gamma}-p_{\\phi})^2 =-2 GeV^2/c^2, using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The cross sections are compared with predictions from a re-scattering model. In a framework of vector meson dominance, the data are consistent with the total \\phi-N cross section \\sigma_{\\phi N} at about 10 mb. If vector meson dominance is violated, a larger \\sigma_{\\phi N} is possible by introducing larger t-slope for the \\phi N \\to \\phi N process than that for the \\gamma N \\to \\phi N process. The decay angular distributions of the \\phi are consistent with helicity conservation.

  12. {phi}-Meson Photoproduction with Linearly Polarized Photons at Threshold Energies

    SciTech Connect

    Salamanca, Julian; Cole, Philip L.

    2007-10-26

    The observables provided by linearly-polarized photons are of interest in delineating the contributions of the various hadronic processes giving rise to vector meson photoproduction. In particular, we describe how {phi}-meson production affords an incisive tool for exploring the nature of the parity exchange at threshold energies, the strangeness content of proton, as well as extracting signatures for the violation of Okubo-Zweig-Iizuka observation (OZI rule). Our goal is to study the {gamma}-vectorp{yields}{phi}p reaction, with {phi}{yields}K{sup +}K{sup -}, in the photon energy range of 1.7 to 2.1 GeV by using the Coherent Linear Bremsstrahlung Facility in Hall B of Jefferson Laboratory, Newport News, VA. The data were collected during the g8b run in the summer of 2005.

  13. Differential Photoproduction Cross Sections of the Sigma0(1385), Lambda(1405), and Lambda(1520)

    SciTech Connect

    Moriya, Kei; Schumacher, Reinhard A.

    2013-10-01

    We report the exclusive photoproduction cross sections for the Sigma(1385), Lambda(1405), and Lambda(1520) in the reactions gamma + p -> K+ + Y* using the CLAS detector for energies from near the respective production thresholds up to a center-of-mass energy W of 2.85 GeV. The differential cross sections are integrated to give the total exclusive cross sections for each hyperon. Comparisons are made to current theoretical models based on the effective Lagrangian approach and fitted to previous data. The accuracy of these models is seen to vary widely. The cross sections for the Lambda(1405) region are strikingly different for the Sigma+pi-, Sigma0 pi0, and Sigma- pi+ decay channels, indicating the effect of isospin interference, especially at W values close to the threshold.

  14. Polarization transfer in wide-angle Compton scattering and single-pion photoproduction from the proton

    SciTech Connect

    Fanelli, Cristiano V.

    2015-10-06

    Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The WACS polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θPcm = 70°. The longitudinal transfer KLL, measured to be 0.645 ± 0.059 ± 0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ~3 times larger than predicted by the GPD-based calculations, which indicates a significant unknown contribution to the scattering amplitude.

  15. Polarization transfer in wide-angle Compton scattering and single-pion photoproduction from the proton

    DOE PAGESBeta

    Fanelli, Cristiano V.

    2015-10-06

    Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The WACS polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θPcm = 70°. The longitudinal transfer KLL, measured to be 0.645 ± 0.059 ± 0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton.more » However, the observed value is ~3 times larger than predicted by the GPD-based calculations, which indicates a significant unknown contribution to the scattering amplitude.« less

  16. Differential cross sections of D*+/- photoproduction in ep collisions at HERA

    NASA Astrophysics Data System (ADS)

    Breitweg, J.; Derrick, M.; Krakauer, D.; Magill, S.; Mikunas, D.; Musgrave, B.; Repond, J.; Stanek, R.; Talaga, R. L.; Yoshida, R.; Zhang, H.; Mattingly, M. C. K.; Anselmo, F.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Romeo, G. Cara; Castellini, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; Gialas, I.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; de Pasquale, S.; Pesci, A.; Polini, A.; Sartorelli, G.; Garcia, Y. Zamora; Zichichi, A.; Amelung, C.; Bornheim, A.; Brock, I.; Coböken, K.; Crittenden, J.; Deffner, R.; Eckert, M.; Feld, L.; Grothe, M.; Hartmann, H.; Heinloth, K.; Heinz, L.; Hilger, E.; Jakob, H.-P.; Katz, U. F.; Paul, E.; Pfeiffer, M.; Rembser, Ch.; Stamm, J.; Wedemeyer, R.; Bailey, D. S.; Campbell-Robson, S.; Cottingham, W. N.; Foster, B.; Hall-Wilton, R.; Hayes, M. E.; Heath, G. P.; Heath, H. F.; Piccioni, D.; Roff, D. G.; Tapper, R. J.; Arneodo, M.; Ayad, R.; Capua, M.; Garfagnini, A.; Iannotti, L.; Schioppa, M.; Susinno, G.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Pac, M. Y.; Caldwell, A.; Cartiglia, N.; Jing, Z.; Liu, W.; Parsons, J. A.; Ritz, S.; Sampson, S.; Sciulli, F.; Straub, P. B.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Jakubowski, Z.; Przybycień, M. B.; Zachara, M.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Zajac, J.; Duliński, Z.; Kotański, A.; Kotański, A.; Abbiendi, G.; Abramowicz, H.; Bauerdick, L. A. T.; Behrens, U.; Beier, H.; Bienlein, J. K.; Cases, G.; Deppe, O.; Desler, K.; Drews, G.; Gilkinson, D. J.; Glasman, C.; Göttlicher, P.; Große-Knetter, J.; Haas, T.; Hain, W.; Hasell, D.; Heßling, H.; Iga, Y.; Johnson, K. F.; Kasemann, M.; Koch, W.; Kötz, U.; Kowalski, H.; Labs, J.; Lindemann, L.; Löhr, B.; Löwe, M.; Mainusch, J.; Mańczak, O.; Milewski, J.; Monteiro, T.; Ng, J. S. T.; Notz, D.; Ohrenberg, K.; Park, I. H.; Pellegrino, A.; Pelucchi, F.; Piotrzkowski, K.; Roco, M.; Rohde, M.; Roldán, J.; Savin, A. A.; Schneekloth, U.; Schulz, W.; Selonke, F.; Surrow, B.; Tassi, E.; Voß, T.; Westphal, D.; Wolf, G.; Wollmer, U.; Youngman, C.; Żarnecki, A. F.; Zeuner, W.; Burow, B. D.; Grabosch, H. J.; Meyer, A.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Pelfer, P.; Maccarrone, G.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Markun, P.; Trefzger, T.; Wölfle, S.; Bromley, J. T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Saxon, D. H.; Sinclair, L. E.; Strickland, E.; Utley, M. L.; Waugh, R.; Wilson, A. S.; Bohnet, I.; Gendner, N.; Holm, U.; Meyer-Larsen, A.; Salehi, H.; Wick, K.; Gladilin, L. K.; Klanner, R.; Lohrmann, E.; Poelz, G.; Schott, W.; Zetsche, F.; Bacon, T. C.; Butterworth, I.; Cole, J. E.; Harris, V. L.; Howell, G.; Hung, B. H. Y.; Lamberti, L.; Long, K. R.; Miller, D. B.; Pavel, N.; Prinias, A.; Sedgbeer, J. K.; Sideris, D.; Whitfield, A. F.; Mallik, U.; Wang, S. M.; Wu, J. T.; Cloth, P.; Filges, D.; An, S. H.; Lee, S. B.; Nam, S. W.; Park, H. S.; Park, S. K.; Barreiro, F.; Fernandez, J. P.; Graciani, R.; Hernández, J. M.; Hervás, L.; Labarga, L.; Martinez, M.; del Peso, J.; Puga, J.; Terron, J.; de Trocóniz, J. F.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Murray, W. N.; Ochs, A.; Riveline, M.; Stairs, D. G.; St-Laurent, M.; Ullmann, R.; Tsurugai, T.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Golubkov, Yu. A.; Kobrin, V. D.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Yu.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Zotov, N. P.; Bokel, C.; Botje, M.; Brümmer, N.; Chlebana, F.; Engelen, J.; de Kamps, M.; Kooijman, P.; Kruse, A.; van Sighem, A.; Tiecke, H.; Verkerke, W.; Vossebeld, J.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Nylander, P.; Romanowski, T. A.; Blaikley, H. E.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Edmonds, J. K.; Harnew, N.; Lancaster, M.; McFall, J. D.; Nath, C.; Noyes, V. A.; Quadt, A.; Tickner, J. R.; Uijterwaal, H.; Walczak, R.; Waters, D. S.; Yip, T.; Bertolin, A.; Brugnera, R.; Carlin, R.; dal Corso, F.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Bulmahn, J.; Feild, R. G.; Oh, B. Y.; Okrasiński, J. R.; Whitmore, J. J.; D'Agostini, G.; Marini, G.; Nigro, A.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Barberis, E.; Dubbs, T.; Heusch, C.; van Hook, M.; Lockman, W.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Williams, D. C.; Schwarzer, O.; Walenta, A. H.; Briskin, G.; Dagan, S.; Doeker, T.; Levy, A.; Abe, T.; Fleck, J. I.; Inuzuka, M.; Ishii, T.; Kuze, M.; Nagano, K.; Nakao, M.; Suzuki, I.; Tokushuku, K.; Umemori, K.; Yamada, S.; Yamazaki, Y.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Matsushita, T.; Yamauchi, K.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Petrucci, M. C.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Brkic, M.; Fagerstroem, C.-P.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sampson, C. R.; Simmons, D.; Teuscher, R. J.; Butterworth, J. M.; Catterall, C. D.; Jones, T. W.; Kaziewicz, P. B.; Lane, J. B.; Saunders, R. L.; Shulman, J.; Sutton, M. R.; Lu, B.; Mo, L. W.; Ciborowski, J.; Grzelak, G.; Kasprzak, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Pawlak, R.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Adamus, M.; Coldewey, C.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Revel, D.; Zer-Zion, D.; Badgett, W. F.; Chapin, D.; Cross, R.; Dasu, S.; Foudas, C.; Loveless, R. J.; Mattingly, S.; Reeder, D. D.; Smith, W. H.; Vaiciulis, A.; Wodarczyk, M.; Bhadra, S.; Frisken, W. R.; Khakzad, M.; Schmidke, W. B.

    1997-02-01

    Inclusive photoproduction of D*+/- in ep collisions at HERA has been measured with the ZEUS detector for photon-proton centre of mass energies in the range 115 < W < 280 GeV and photon virtuality Q2 < 4 GeV2. The cross section σep -> D* X integrated over the kinematic region pD*⊥ > 3 GeV and -1.5 < ηD* < 1.0 is (10.6 +/- 1.7 (stat.) +/-1.61.3 (syst.)) nb. Differential cross sections as functions of pD*⊥, ηD* and W are given. The data are compared with two next-to-leading order perturbative QCD predictions. For a calculation using a massive charm scheme the predicted cross sections are smaller than the measured ones. A recent calculation using a massless charm scheme is in agreement with the data.

  17. Observation of isolated high-ET photons in photoproduction at HERA

    NASA Astrophysics Data System (ADS)

    ZEUS Collaboration; Breitweg, J.; Derrick, M.; Krakauer, D.; Magill, S.; Mikunas, D.; Musgrave, B.; Repond, J.; Stanek, R.; Talaga, R. L.; Yoshida, R.; Zhang, H.; Mattingly, M. C. K.; Anselmo, F.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Castellini, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; de Pasquale, S.; Gialas, I.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Polini, A.; Ricci, F.; Sartorelli, G.; Zamora Garcia, Y.; Zichichi, A.; Amelung, C.; Bornheim, A.; Brock, I.; Coböken, K.; Crittenden, J.; Deffner, R.; Eckert, M.; Grothe, M.; Hartmann, H.; Heinloth, K.; Heinz, L.; Hilger, E.; Jakob, H.-P.; Katz, U. F.; Kerger, R.; Paul, E.; Pfeiffer, M.; Rembser, Ch.; Stamm, J.; Wedemeyer, R.; Wieber, H.; Bailey, D. S.; Campbell-Robson, S.; Cottingham, W. N.; Foster, B.; Hall-Wilton, R.; Hayes, M. E.; Heath, G. P.; Heath, H. F.; Piccioni, D.; Roff, D. G.; Tapper, R. J.; Arneodo, M.; Ayad, R.; Capua, M.; Garfagnini, A.; Iannotti, L.; Schioppa, M.; Susinno, G.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Pac, M. Y.; Caldwell, A.; Cartiglia, N.; Jing, Z.; Liu, W.; Mellado, B.; Parsons, J. A.; Ritz, S.; Sampson, S.; Sciulli, F.; Straub, P. B.; Zhu, Q.; Borzemski, P.; Chwastowski, J.; Eskreys, A.; Jakubowski, Z.; Przybycień , M. B.; Zachara, M.; Zawiejski, L.; Adamczyk, L.; Bednarek, B.; Bukowy, M.; Jeleń , K.; Kisielewska, D.; Kowalski, T.; Przybycień , M.; Rulikowska-Zarȩ Bska, E.; Suszycki, L.; Zaja C, J.; Duliń Ski, Z.; Kotań Ski, A.; Abbiendi, G.; Bauerdick, L. A. T.; Behrens, U.; Beier, H.; Bienlein, J. K.; Cases, G.; Deppe, O.; Desler, K.; Drews, G.; Fricke, U.; Gilkinson, D. J.; Glasman, C.; Göttlicher, P.; Große-Knetter, J.; Haas, T.; Hain, W.; Hasell, D.; Johnson, K. F.; Kasemann, M.; Koch, W.; Kötz, U.; Kowalski, H.; Labs, J.; Lindemann, L.; Löhr, B.; Löwe, M.; Mań Czak, O.; Milewski, J.; Monteiro, T.; Ng, J. S. T.; Notz, D.; Ohrenberg, K.; Park, I. H.; Pellegrino, A.; Pelucchi, F.; Piotrzkowski, K.; Roco, M.; Rohde, M.; Roldán, J.; Ryan, J. J.; Savin, A. A.; Schneekloth, U.; Selonke, F.; Surrow, B.; Tassi, E.; Voß, T.; Westphal, D.; Wolf, G.; Wollmer, U.; Youngman, C.; Zsolararnecki, A. F.; Zeuner, W.; Burow, B. D.; Grabosch, H. J.; Meyer, A.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Pelfer, P.; Maccarrone, G.; Votano, L.; Bamberger, A.; Eisenhardt, S.; Markun, P.; Trefzger, T.; Wölfle, S.; Bromley, J. T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Saxon, D. H.; Sinclair, L. E.; Strickland, E.; Utley, M. L.; Waugh, R.; Wilson, A. S.; Bohnet, I.; Gendner, N.; Holm, U.; Meyer-Larsen, A.; Salehi, H.; Wick, K.; Gladilin, L. K.; Horstmann, D.; Kçira, D.; Klanner, R.; Lohrmann, E.; Poelz, G.; Schott, W.; Zetsche, F.; Bacon, T. C.; Butterworth, I.; Cole, J. E.; Harris, V. L.; Howell, G.; Hung, B. H. Y.; Lamberti, L.; Long, K. R.; Miller, D. B.; Pavel, N.; Prinias, A.; Sedgbeer, J. K.; Sideris, D.; Whitfield, A. F.; Mallik, U.; Wang, S. M.; Wu, J. T.; Cloth, P.; Filges, D.; Fleck, J. I.; Ishii, T.; Kuze, M.; Nakao, M.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; An, S. H.; Lee, S. B.; Nam, S. W.; Park, H. S.; Park, S. K.; Barreiro, F.; Fernández, J. P.; García, G.; Graciani, R.; Hernández, J. M.; Hervás, L.; Labarga, L.; Martínez, M.; del Peso, J.; Puga, J.; Terrón, J.; de Trocóniz, J. F.; Corriveau, F.; Hanna, D. S.; Hartmann, J.; Hung, L. W.; Lim, J. N.; Murray, W. N.; Ochs, A.; Riveline, M.; Stairs, D. G.; St-Laurent, M.; Ullmann, R.; Tsurugai, T.; Bashkirov, V.; Dolgoshein, B. A.; Stifutkin, A.; Bashindzhagyan, G. L.; Ermolov, P. F.; Golubkov, Yu. A.; Khein, L. A.; Korotkova, N. A.; Korzhavina, I. A.; Kuzmin, V. A.; Lukina, O. Yu.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Zotkin, S. A.; Bokel, C.; Botje, M.; Brümmer, N.; Chlebana, F.; Engelen, J.; Kooijman, P.; van Sighem, A.; Tiecke, H.; Tuning, N.; Verkerke, W.; Vossebeld, J.; Vreeswijk, M.; Wiggers, L.; de Wolf, E.; Acosta, D.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Nylander, P.; Romanowski, T. A.; Blaikley, H. E.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Edmonds, J. K.; Harnew, N.; Lancaster, M.; McFall, J. D.; Nath, C.; Noyes, V. A.; Quadt, A.; Ruske, O.; Tickner, J. R.; Uijterwaal, H.; Walczak, R.; Waters, D. S.; Bertolin, A.; Brugnera, R.; Carlin, R.; dal Corso, F.; Dosselli, U.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Bulmahn, J.; Feild, R. G.; Oh, B. Y.; Okrasiń Ski, J. R.; Whitmore, J. J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Raso, M.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Epperson, D.; Heusch, C.; Rahn, J. T.; Sadrozinski, H. F.-W.; Seiden, A.; Williams, D. C.; Schwarzer, O.; Walenta, A. H.; Abramowicz, H.; Briskin, G.; Dagan, S.; Kananov, S.; Levy, A.; Abe, T.; Fusayasu, T.; Inuzuka, M.; Nagano, K.; Suzuki, I.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Homma, K.; Kitamura, S.; Matsushita, T.; Yamauchi, K.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Petrucci, M. C.; Sacchi, R.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Brkic, M.; Fagerstroem, C.-P.; Hartner, G. F.; Joo, K. K.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Polenz, S.; Sampson, C. R.; Simmons, D.; Teuscher, R. J.; Butterworth, J. M.; Catterall, C. D.; Jones, T. W.; Kaziewicz, P. B.; Lane, J. B.; Saunders, R. L.; Shulman, J.; Sutton, M. R.; Lu, B.; Mo, L. W.; Ciborowski, J.; Grzelak, G.; Kasprzak, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Pawlak, R.; Tymieniecka, T.; Wróblewski, A. K.; Zakrzewski, J. A.; Adamus, M.; Coldewey, C.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Revel, D.; Badgett, W. F.; Chapin, D.; Cross, R.; Dasu, S.; Foudas, C.; Loveless, R. J.; Mattingly, S.; Reeder, D. D.; Smith, W. H.; Vaiciulis, A.; Wodarczyk, M.; Bhadra, S.; Frisken, W. R.; Khakzad, M.; Schmidke, W. B.

    1997-11-01

    Events containing an isolated prompt photon with high transverse energy, together with a balancing jet, have been observed for the first time in photoproduction at HERA. The data were taken with the ZEUS detector, in a γp centre of mass energy range 120-250 GeV. The fraction of the incoming photon energy participating in the production of the prompt photon and the jet, xγ, shows a strong peak near unity, consistent with LO QCD Monte Carlo predictions. In the transverse energy and pseudorapidity range 5<=ET γ<10 GeV, -0.7<=ηγ<0.8, ET jet>=5 GeV, and -1.5<=ηjet<=1.8, with xγOBS>0.8, the measured cross section is 15.3+/-3.8+/-1.8 pb, in good agreement with a recent NLO calculation.

  18. Penrose photoproduction processes - A high efficiency energy mechanism for active galactic nuclei and quasars

    NASA Technical Reports Server (NTRS)

    Leiter, D.; Kafatos, M.

    1979-01-01

    Recent observations of NGC 4151 and 3C273 suggest that the nuclei of active galaxies have very high gamma ray efficiencies. In addition, optical studies of M87 have indicated the possibility of a massive black hole in its central region. The above facts have led to study of a new physical mechanism, Penrose Photoproduction Processes, in the ergospheres of massive Kerr black holes, as a way to account for the fluctuating, high efficiency, energy production associated with active galaxies and quasars. Observational signatures, associated with this mechanism, occur in the form of approximately 2 MeV and approximately 2 GeV gamma ray cutoffs which might be corroborated by the observed spectra of NGC 4151 and 3C273, respectively.

  19. Polarization Transfer in Wide-Angle Compton Scattering and Single-Pion Photoproduction from the Proton.

    PubMed

    Fanelli, C; Cisbani, E; Hamilton, D J; Salmé, G; Wojtsekhowski, B; Ahmidouch, A; Annand, J R M; Baghdasaryan, H; Beaufait, J; Bosted, P; Brash, E J; Butuceanu, C; Carter, P; Christy, E; Chudakov, E; Danagoulian, S; Day, D; Degtyarenko, P; Ent, R; Fenker, H; Fowler, M; Frlez, E; Gaskell, D; Gilman, R; Horn, T; Huber, G M; de Jager, C W; Jensen, E; Jones, M K; Kelleher, A; Keppel, C; Khandaker, M; Kohl, M; Kumbartzki, G; Lassiter, S; Li, Y; Lindgren, R; Lovelace, H; Luo, W; Mack, D; Mamyan, V; Margaziotis, D J; Markowitz, P; Maxwell, J; Mbianda, G; Meekins, D; Meziane, M; Miller, J; Mkrtchyan, A; Mkrtchyan, H; Mulholland, J; Nelyubin, V; Pentchev, L; Perdrisat, C F; Piasetzky, E; Prok, Y; Puckett, A J R; Punjabi, V; Shabestari, M; Shahinyan, A; Slifer, K; Smith, G; Solvignon, P; Subedi, R; Wesselmann, F R; Wood, S; Ye, Z; Zheng, X

    2015-10-01

    Wide-angle exclusive Compton scattering and single-pion photoproduction from the proton have been investigated via measurement of the polarization transfer from a circularly polarized photon beam to the recoil proton. The wide-angle Compton scattering polarization transfer was analyzed at an incident photon energy of 3.7 GeV at a proton scattering angle of θ_{cm}^{p}=70°. The longitudinal transfer K_{LL}, measured to be 0.645±0.059±0.048, where the first error is statistical and the second is systematic, has the same sign as predicted for the reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton. However, the observed value is ~3 times larger than predicted by the generalized-parton-distribution-based calculations, which indicates a significant unknown contribution to the scattering amplitude. PMID:26550716

  20. Cascade Spectroscopy and Recent Xi* Photo-production Results from CLAS

    SciTech Connect

    John T. Goetz

    2010-08-01

    Doubly-strange baryon resonances provide new insights into baryon structure. The standard QCD Lagrangian implies that for every N* and Delta* resonance, there should be a corresponding Xi (cascade resonance). This is due to the flavor symmetry of the strong force. Therefore, one can investigate baryon structure by observing aspects of the doubly-strange baryons like regularities such as parity doublets. At energies above approximately 1.5 GeV, the light-quark baryon resonances are broad and overlap while the cascades in this range are narrow and therefore more readily observed. An overview of the world cascade spectrum and a comparison to the lighter baryon spectra will be presented. Recent results from an on-going analysis from the G12 (5.4 GeV) photo-production experiment using the CLAS detector at JLab will be highlighted.

  1. Measurement of π0 photoproduction on the proton at MAMI C

    NASA Astrophysics Data System (ADS)

    Adlarson, P.; Afzal, F.; Akondi, C. S.; Annand, J. R. M.; Arends, H. J.; Azimov, Ya. I.; Beck, R.; Borisov, N.; Braghieri, A.; Briscoe, W. J.; Cherepnya, S.; Cividini, F.; Collicott, C.; Costanza, S.; Denig, A.; Downie, E. J.; Dieterle, M.; Ferretti Bondy, M. I.; Fil'kov, L. V.; Fix, A.; Gardner, S.; Garni, S.; Glazier, D. I.; Glowa, D.; Gradl, W.; Gurevich, G.; Hamilton, D. J.; Hornidge, D.; Huber, G. M.; Käser, A.; Kashevarov, V. L.; Kay, S.; Keshelashvili, I.; Kondratiev, R.; Korolija, M.; Krusche, B.; Kulikov, V. V.; Lazarev, A.; Linturi, J.; Lisin, V.; Livingston, K.; MacGregor, I. J. D.; Manley, D. M.; Martel, P. P.; Martemianov, M.; McGeorge, J. C.; Meyer, W.; Middleton, D. G.; Miskimen, R.; Mushkarenkov, A.; Neganov, A.; Neiser, A.; Oberle, M.; Ostrick, M.; Ott, P.; Otte, P. B.; Oussena, B.; Paudyal, D.; Pedroni, P.; Polonski, A.; Polyanski, V. V.; Prakhov, S.; Rajabi, A.; Reicherz, G.; Ron, G.; Rostomyan, T.; Sarty, A.; Schott, D. M.; Schumann, S.; Sfienti, C.; Sokhoyan, V.; Spieker, K.; Steffen, O.; Strakovsky, I. I.; Strub, Th.; Supek, I.; Taragin, M. F.; Thiel, A.; Thiel, M.; Tiator, L.; Thomas, A.; Unverzagt, M.; Usov, Yu. A.; Wagner, S.; Watts, D. P.; Werthmüller, D.; Wettig, J.; Witthauer, L.; Wolfes, M.; Workman, R. L.; Zana, L. A.; A2 Collaboration at MAMI

    2015-08-01

    Differential cross sections for the γ p →π0p reaction have been measured with the A2 tagged-photon facilities at the Mainz Microtron, MAMI C, up to the center-of-mass energy W =1.9 GeV . The new results, obtained with a fine energy and angular binning, increase the existing quantity of π0 photoproduction data by ˜47 % . Owing to the unprecedented statistical accuracy and the full angular coverage, the results are sensitive to high partial-wave amplitudes. This is demonstrated by the decomposition of the differential cross sections in terms of Legendre polynomials and by further comparison to model predictions. A new solution of the SAID partial-wave analysis obtained after adding the new data into the fit is presented.

  2. Dalitz Decay of Pseudoscalar Mesons from Photoproduction on Hydrogen Target with CLAS

    NASA Astrophysics Data System (ADS)

    Kunkel, Michael; Amaryan, Moskov; Paolone, Michael; Weygand, Dennis; CLAS Collaboration

    2013-10-01

    Experimental results on the Dalitz decay of pseudoscalar mesons P(π0 , η ,η') -->e+e- γ produced in the photoproduction reaction γ + p --> P(π0 , η , η ') + p on a Hydrogen target, with CLAS setup at Thomas Jefferson National Accelerator Facility (TJNAF), are presented. The total statistics collected for π0 , η Dalitz decay exceeds the world's published statistics by an order of magnitude, while the Dalitz decay of η' -->e+e- γ is observed and measured for the first time. The data obtained will allow for measurements of transition form factors that are encoded in the mass spectrum of the e+e- system. The current status of analysis of the π0 , η transition form factors and the search for the heavy photon from the e+e- mass system will be discussed.

  3. Measurement of the transverse target and beam-target asymmetries in η meson photoproduction at MAMI.

    PubMed

    Akondi, C S; Annand, J R M; Arends, H J; Beck, R; Bernstein, A; Borisov, N; Braghieri, A; Briscoe, W J; Cherepnya, S; Collicott, C; Costanza, S; Downie, E J; Dieterle, M; Fix, A; Fil'kov, L V; Garni, S; Glazier, D I; Gradl, W; Gurevich, G; Hall Barrientos, P; Hamilton, D; Hornidge, D; Howdle, D; Huber, G M; Kashevarov, V L; Keshelashvili, I; Kondratiev, R; Korolija, M; Krusche, B; Lazarev, A; Lisin, V; Livingston, K; MacGregor, I J D; Mancel, J; Manley, D M; Martel, P; McNicoll, E F; Meyer, W; Middleton, D; Miskimen, R; Mushkarenkov, A; Nefkens, B M K; Neganov, A; Nikolaev, A; Oberle, M; Ostrick, M; Ortega, H; Ott, P; Otte, P B; Oussena, B; Pedroni, P; Polonski, A; Polyanski, V V; Prakhov, S; Reicherz, G; Rostomyan, T; Sarty, A; Schumann, S; Steffen, O; Strakovsky, I I; Strub, Th; Supek, I; Tiator, L; Thomas, A; Unverzagt, M; Usov, Yu A; Watts, D P; Werthmüller, D; Witthauer, L; Wolfes, M

    2014-09-01

    We present new data for the transverse target asymmetry T and the very first data for the beam-target asymmetry F in the γ[over →]p[over →]→ηp reaction up to a center-of-mass energy of W=1.9  GeV. The data were obtained with the Crystal-Ball/TAPS detector setup at the Glasgow tagged photon facility of the Mainz Microtron MAMI. All existing model predictions fail to reproduce the new data indicating a significant impact on our understanding of the underlying dynamics of η meson photoproduction. The peculiar nodal structure observed in existing T data close to threshold is not confirmed. PMID:25238349

  4. Scaling behavior in exclusive meson photoproduction from Jefferson Lab at large momentum transfers

    SciTech Connect

    Dey, Biplab

    2014-07-01

    With the availability of new high-statistics and wide-angle measurements for several exclusive non-πN meson photoproduction channels from Jefferson Lab, we examine the fundamental scaling law of 90° scattering in QCD that was originally derived in the high-energy perturbative limit. The data show scaling to be prominently visible even in the medium-energy domain of 2.5 GeV ≲√s≲2.84 GeV, where √s is the center-of-mass energy. While constituent quark exchange suffices for pseudoscalar mesons, additional gluon exchanges from higher Fock states of the hadronic wave functions appear be needed for vector-meson production. Finally, the case of the Φ(1020), where two-gluon exchanges are known to dominate, is especially illuminating.

  5. Sulfolobus Mutants, Generated via PCR Products, Which Lack Putative Enzymes of UV Photoproduct Repair

    PubMed Central

    Sakofsky, Cynthia J.; Runck, Laura A.; Grogan, Dennis W.

    2011-01-01

    In order to determine the biological relevance of two S. acidocaldarius proteins to the repair of UV photoproducts, the corresponding genes (Saci_1227 and Saci_1096) were disrupted, and the phenotypes of the resulting mutants were examined by various genetic assays. The disruption used integration by homologous recombination of a functional but heterologous pyrE gene, promoted by short sequences attached to both ends via PCR. The phenotypic analyses of the disruptants confirmed that ORF Saci_1227 encodes a DNA photolyase which functions in vivo, but they could not implicate ORF Saci_1096 in repair of UV- or other externally induced DNA damage despite its similarity to genes encoding UV damage endonucleases. The success of the gene-disruption strategy, which used 5′ extensions of PCR primers to target cassette integration, suggests potential advantages for routine construction of Sulfolobus strains. PMID:21785574

  6. Extraction of polarization observables in vector-meson photoproduction using a polarized target at CLAS

    NASA Astrophysics Data System (ADS)

    Roy, P.

    2016-05-01

    Baryon spectroscopy is an indispensable tool for investigating the nature of strong interaction within baryons. The study of vector-meson photoproduction is expected to improve our understanding of the properties of known baryon resonances and also immensely aid in discovering new higher-mass resonances. Polarization observables, in addition to unpolarized cross sections, are required to identify the contributing resonances to these reactions with minimal ambiguities. Preliminary results from the FROST experiment on beam-polarization observables in γ →p →→p ω as well as γ →p →→p π+π- using a linearly-polarized beam and a transversely-polarized FROzen Spin butanol Target will be presented. The latter reaction will provide important information on N* to (broad) ρ vector-meson decay modes, which is difficult to extract directly from the data.

  7. First measurement of the helicity asymmetry E in η photoproduction on the proton

    NASA Astrophysics Data System (ADS)

    Senderovich, I.; Morrison, B. T.; Dugger, M.; Ritchie, B. G.; Pasyuk, E.; Tucker, R.; Brock, J.; Carlin, C.; Keith, C. D.; Meekins, D. G.; Seely, M. L.; Rönchen, D.; Döring, M.; Collins, P.; Adhikari, K. P.; Adikaram, D.; Akbar, Z.; Anderson, M. D.; Anefalos Pereira, S.; Badui, R. A.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A. S.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Cortes, O.; Credé, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Filippi, A.; Fleming, J. A.; Fradi, A.; Garillon, B.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Glazier, D. I.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Hattawy, M.; Hicks, K.; Ho, D.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jenkins, D.; Jiang, H.; Jo, H. S.; Joo, K.; Joosten, S.; Keller, D.; Khachatryan, G.; Khandaker, M.; Kim, A.; Klein, F. J.; Kubarovsky, V.; Kunkel, M. C.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Mattione, P.; McKinnon, B.; Meyer, C. A.; Mineeva, T.; Mokeev, V.; Montgomery, R. A.; Movsisyan, A.; Munoz Camacho, C.; Nadel-Turonski, P.; Net, L. A.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Park, K.; Park, S.; Peng, P.; Phelps, W.; Pisano, S.; Pogorelko, O.; Price, J. W.; Prok, Y.; Puckett, A. J. R.; Ripani, M.; Rizzo, A.; Rosner, G.; Roy, P.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Simonyan, A.; Skorodumina, Iu.; Smith, G. D.; Sober, D. I.; Sparveris, N.; Stepanyan, S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Sytnik, V.; Tian, Ye; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Wei, X.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; Zonta, I.

    2016-04-01

    Results are presented for the first measurement of the double-polarization helicity asymmetry E for the η photoproduction reaction γp → ηp. Data were obtained using the FROzen Spin Target (FROST) with the CLAS spectrometer in Hall B at Jefferson Lab, covering a range of center-of-mass energy W from threshold to 2.15 GeV and a large range in center-of-mass polar angle. As an initial application of these data, the results have been incorporated into the Jülich-Bonn model to examine the case for the existence of a narrow N* resonance between 1.66 and 1.70 GeV. The addition of these data to the world database results in marked changes in the predictions for the E observable from that model. Further comparison with several theoretical approaches indicates these data will significantly enhance our understanding of nucleon resonances.

  8. Cascade spectroscopy in photoproduction on a proton target at Jefferson Lab

    SciTech Connect

    L. Guo; D. P. Weygand

    2005-10-01

    The CLAS Collaboration at Jefferson Lab conducted a photoproduction experiment on a proton target using a tagged photon beam with an energy range of 1.5-3.8 GeV during May-July 2004. With an integrated luminosity of about 75 pb{sup -1}, this experiment provides the largest data set for photon-proton reactions ever collected. The reaction {gamma}p {yields} K{sup +}K{sup +}{Xi}{sup -}(1320) has been investigated and the preliminary results of the cross section measurement of {Xi}{sup -}(1320) for the photon energy range of 2.7-3.8 GeV have been obtained. In a search for excited cascade states, the reaction of {gamma}p {yields} K{sup +}K{sup +}{pi}{sup -}({Xi}{sup 0}(1320)) has also been explored.

  9. Photoproduction of the omega meson on the proton at large momentum transfer.

    PubMed

    Battaglieri, M; Brunoldi, M; De Vita, R; Laget, J M; Osipenko, M; Ripani, M; Taiuti, M; Adams, G; Amaryan, M J; Anciant, E; Anghinolfi, M; Armstrong, D S; Asavapibhop, B; Asryan, G; Audit, G; Auger, T; Avakian, H; Barrow, S; Beard, K; Bektasoglu, M; Berman, B L; Bersani, A; Bianchi, N; Biselli, A S; Boiarinov, S; Bouchigny, S; Bradford, R; Branford, D; Briscoe, W J; Brooks, W K; Burkert, V D; Calarco, J R; Capitani, G P; Carman, D S; Carnahan, B; Cazes, A; Cetina, C; Cole, P L; Coleman, A; Cords, D; Corvisiero, P; Crabb, D; Crannell, H; Cummings, J P; DeSanctis, E; Degtyarenko, P V; Demirchyan, R; Denizli, H; Dennis, L; Dharmawardane, K V; Dhuga, K S; Djalali, C; Dodge, G E; Doughty, D; Dragovitsch, P; Dugger, M; Dytman, S; Eckhause, M; Egiyan, H; Egiyan, K S; Elouadrhiri, L; Farhi, L; Feuerbach, R J; Ficenec, J; Forest, T A; Freyberger, A P; Frolov, V; Funsten, H; Gaff, S J; Gai, M; Garcon, M; Gavalian, G; Gilad, S; Gilfoyle, G P; Giovanetti, K L; Golovach, E; Griffioen, K; Guidal, M; Guillo, M; Guo, L; Gyurjyan, V; Hadjidakis, C; Hancock, D; Hardie, J; Heddle, D; Hersman, F W; Hicks, K; Hicks, R S; Holtrop, M; Hyde-Wright, C E; Ito, M M; Joo, K; Kelley, J H; Khandaker, M; Kim, W; Klein, A; Klein, F J; Klimenko, A V; Klusman, M; Kossov, M; Kramer, L H; Kuang, Y; Kuhn, S E; Lachniet, J; Lawrence, D; Lucas, M; Lukashin, K; Major, R W; Manak, J J; Marchand, C; McAleer, S; McCarthy, J; McNabb, J W C; Mecking, B A; Mestayer, M D; Meyer, C A; Mikhailov, K; Mirazita, M; Miskimen, R; Mokeev, V; Morrow, S; Mozer, M U; Muccifora, V; Mueller, J; Mutchler, G S; Napolitano, J; Nelson, S O; Niccolai, S; Niczyporuk, B B; Niyazov, R A; Nozar, M; O'Brien, J T; Opper, A K; Peterson, G; Philips, S A; Pivnyuk, N; Pocanic, D; Pogorelko, O; Polli, E; Preedom, B M; Price, J W; Protopopescu, D; Qin, L M; Raue, B A; Reolon, A R; Riccardi, G; Ricco, G; Ritchie, B G; Ronchetti, F; Rossi, P; Rowntree, D; Rubin, P D; Sabourov, K; Salgado, C; Sapunenko, V; Schumacher, R A; Serov, V S; Shafi, A; Sharabian, Y G; Shaw, J; Skabelin, A V; Smith, E S; Smith, T; Smith, L C; Sober, D I; Spraker, M; Stavinsky, A; Stepanyan, S; Stoler, P; Taylor, S; Tedeschi, D J; Todor, L; Thoma, U; Thompson, R; Vineyard, M F; Vlassov, A V; Wang, K; Weinstein, L B; Weller, H; Weygand, D P; Whisnant, C S; Wolin, E; Wood, M; Yegneswaran, A; Yun, J; Zhang, B; Zhao, J; Zhou, Z

    2003-01-17

    The differential cross section, dsigma/dt, for omega meson exclusive photoproduction on the proton above the resonance region (2.6

  10. Beam-helicity asymmetries in double-charged-pion photoproduction on the proton.

    PubMed

    Strauch, S; Berman, B L; Adams, G; Ambrozewicz, P; Anghinolfi, M; Asavapibhop, B; Asryan, G; Audit, G; Avakian, H; Bagdasaryan, H; Baillie, N; Ball, J P; Baltzell, N A; Barrow, S; Batourine, V; Battaglieri, M; Beard, K; Bedlinskiy, I; Bektasoglu, M; Bellis, M; Benmouna, N; Bennhold, C; Biselli, A S; Boiarinov, S; Bouchigny, S; Bradford, R; Branford, D; Briscoe, W J; Brooks, W K; Bültmann, S; Burkert, V D; Butuceanu, C; Calarco, J R; Careccia, S L; Carman, D S; Carnahan, B; Chen, S; Cole, P L; Coleman, A; Coltharp, P; Cords, D; Corvisiero, P; Crabb, D; Crannell, H; Cummings, J P; Degtyarenko, P V; Denizli, H; Dennis, L; De Sanctis, E; Deur, A; Devita, R; Dharmawardane, K V; Dhuga, K S; Djalali, C; Dodge, G E; Donnelly, J; Doughty, D; Dragovitsch, P; Dugger, M; Dytman, S; Dzyubak, O P; Egiyan, H; Egiyan, K S; Elouadrhiri, L; Empl, A; Eugenio, P; Fatemi, R; Fedotov, G; Feldman, G; Feuerbach, R J; Fix, A; Forest, T A; Funsten, H; Gavalian, G; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Gothe, R W; Griffioen, K A; Guidal, M; Guler, N; Guo, L; Gyurjyan, V; Hadjidakis, C; Hakobyan, R S; Hardie, J; Heddle, D; Hersman, F W; Hicks, K; Hleiqawi, I; Holtrop, M; Hu, J; Huertas, M; Hyde-Wright, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Ito, M M; Jenkins, D; Jo, H S; Joo, K; Juengst, H G; Kellie, J D; Khandaker, M; Kim, K Y; Kim, K; Kim, W; Klein, A; Klein, F J; Klimenko, A V; Klusman, M; Kossov, M; Kramer, L H; Kubarovsky, V; Kuhn, J; Kuhn, S E; Lachniet, J; Laget, J M; Langheinrich, J; Lawrence, D; Lee, T; Lima, A C S; Livingston, K; Lukashin, K; Manak, J J; Marchand, C; McAleer, S; McKinnon, B; McNabb, J W C; Mecking, B A; Mestayer, M D; Meyer, C A; Mibe, T; Mikhailov, K; Minehart, R; Mirazita, M; Miskimen, R; Mokeev, V; Morrow, S A; Muccifora, V; Mueller, J; Mutchler, G S; Nadel-Turonski, P; Napolitano, J; Nasseripour, R; Niccolai, S; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niyazov, R A; Nozar, M; O'rielly, G V; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E; Paterson, C; Philips, S A; Pierce, J; Pivnyuk, N; Pocanic, D; Pogorelko, O; Polli, E; Pozdniakov, S; Preedom, B M; Price, J W; Prok, Y; Protopopescu, D; Qin, L M; Raue, B A; Riccardi, G; Ricco, G; Ripani, M; Ritchie, B G; Roberts, W; Ronchetti, F; Rosner, G; Rossi, P; Rowntree, D; Rubin, P D; Sabatié, F; Salgado, C; Santoro, J P; Sapunenko, V; Schumacher, R A; Serov, V S; Shafi, A; Sharabian, Y G; Shaw, J; Skabelin, A V; Smith, E S; Smith, L C; Sober, D I; Stavinsky, A; Stepanyan, S S; Stepanyan, S; Stokes, B E; Stoler, P; Strakovsky, I I; Suleiman, R; Taiuti, M; Taylor, S; Tedeschi, D J; Thoma, U; Thompson, R; Tkabladze, A; Tkachenko, S; Todor, L; Tur, C; Ungaro, M; Vineyard, M F; Vlassov, A V; Wang, K; Weinstein, L B; Weygand, D P; Williams, M; Wolin, E; Wood, M H; Yegneswaran, A; Yun, J; Zana, L; Zhang, J

    2005-10-14

    Beam-helicity asymmetries for the two-pion-photoproduction reaction gammap-->ppi(+)pi(-) have been studied for the first time in the resonance region for center-of-mass energies between 1.35 and 2.30 GeV. The experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer using circularly polarized tagged photons incident on an unpolarized hydrogen target. Beam-helicity-dependent angular distributions of the final-state particles were measured. The large cross-section asymmetries exhibit strong sensitivity to the kinematics and dynamics of the reaction. The data are compared with the results of various phenomenological model calculations, and show that these models currently do not provide an adequate description for the behavior of this new observable. PMID:16241787

  11. Photoproduction of Hydrogen by Sulfur-Deprived Chlamydomonas reinhardtii Mutants with Impaired Photosystem II Photochemical Activity

    SciTech Connect

    Makarova, V. V.; Kosourov, S.; Krendeleva, T. E.; Semin, B. K.; Kukarskikh, G. P.; Rubin, A. B.; Sayre, R. T.; Ghirardi, M. L.; Seibert, M.

    2007-01-01

    Photoproduction of H2 was examined in a series of sulfur-deprived Chlamydomonas reinhardtii D1-R323 mutants with progressively impaired PSII photochemical activity. In the R323H, R323D, and R323E D1 mutants, replacement of arginine affects photosystem II (PSII) function, as demonstrated by progressive decreases in O2-evolving activity and loss of PSII photochemical activity. Significant changes in PSII activity were found when the arginine residue was replaced by negatively charged amino acid residues (R323D and R323E). However, the R323H (positively charged or neutral, depending on the ambient pH) mutant had minimal changes in PSII activity. The R323H, R323D, and R323E mutants and the pseudo-wild-type (pWt) with restored PSII function were used to study the effects of sulfur deprivation on H2-production activity. All of these mutants exhibited significant changes in the normal parameters associated with the H2-photoproduction process, such as a shorter aerobic phase, lower accumulation of starch, a prolonged anaerobic phase observed before the onset of H2-production, a shorter duration of H2-production, lower H2 yields compared to the pWt control, and slightly higher production of dark fermentation products such as acetate and formate. The more compromised the PSII photochemical activity, the more dramatic was the effect of sulfur deprivation on the H2-production process, which depends both on the presence of residual PSII activity and the amount of stored starch.

  12. The Enzyme-Mediated Direct Reversal of a Dithymine Photoproduct in Germinating Endospores

    PubMed Central

    Yang, Linlin; Li, Lei

    2013-01-01

    Spore photoproduct lyase (SPL) repairs a special thymine dimer, 5-thyminyl-5,6-dihydrothymine, which is commonly called spore photoproduct, or SP, in germinating endospores. SP is the exclusive DNA photo-damaging product found in endospores; its generation and swift repair by SPL are responsible for the spores’ extremely high UV resistance. Early in vivo studies suggested that SPL utilizes a direct reversal strategy to repair SP in the absence of light. Recently, it has been established that SPL belongs to the radical S-adenosylmethionine (SAM) superfamily. The enzymes in this superfamily utilize a tri-cysteine CXXXCXXC motif to bind a [4Fe-4S] cluster. The cluster provides an electron to the S-adenosylmethionine (SAM) to reductively cleave its C5′-S bond, generating a reactive 5′-deoxyadenosyl (5′-dA) radical. This 5′-dA radical abstracts the proR hydrogen atom from the C6 carbon of SP to initiate the repair process; the resulting SP radical subsequently fragments to generate a putative thymine methyl radical, which accepts a back-donated H atom to yield the repaired TpT. The H atom donor is suggested to be a conserved cysteine141 in B. subtilis SPL; the resulting thiyl radical likely interacts with a neighboring tyrosine99 before oxidizing the 5′-dA to 5′-dA radical and, subsequently, regenerating SAM. These findings suggest SPL to be the first enzyme in the large radical SAM superfamily (>44,000 members) to utilize a radical transfer pathway for catalysis; its study should shed light on the mechanistic understanding of the SAM regeneration process in other members of the superfamily. PMID:23799365

  13. Photoproduction of Scalar Mesons Using the CEBAF Large Acceptance Spectrometer (CLAS)

    NASA Astrophysics Data System (ADS)

    Chandavar, Shloka K.

    The search for glueballs has been ongoing for several decades. The lightest glueball has been predicted by quenched lattice QCD to have mass in the range of 1.0--1.7 GeV and JPC = 0++ . The mixing of glueball states with neighbouring meson states complicates their identification and hence several experiments have been carried out over the years to study the glueball candidates. By analyzing the decay channels and production mechanisms of these candidates, their glueball content can theoretically be determined. In reality, a lot of confusion still exists about the status of these glueball candidates. The f0(1500) is one of several contenders for the lightest glueball, which has been extensively studied in several different kinds of experiments. However, there exists no photoproduction data on this particle. In the analysis presented in this dissertation, the presence of the f0(1500) in the KS 0KS0 channel is investigated in photoproduction using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility, also called Jefferson Lab (JLab). This is done by studying the reaction, gammap → fJp → KS0 KS0p → 2(pi +pi-)p using data from the g12 experiment. A clear peak is seen at 1500 MeV in the background subtracted data. This is enhanced if the momentum transfer is restricted to be less than 1 GeV2. Comparing with simulations, it is seen that this peak is associated with t channel production mechanism. The f 2'(1525) has a mass of 1525 MeV and a width of 73 MeV, and hence there is a possibility of it contributing to the peak observed in our data. A moments analysis seems to suggest some presence of a D wave, however, the low acceptance at forward and backward angles prohibits a definitive conclusion.

  14. Photoproduction of hydrogen by sulfur-deprived C. reinhardtii mutants with impaired photosystem II photochemical activity.

    PubMed

    Makarova, Valeria V; Kosourov, Sergey; Krendeleva, Tatiana E; Semin, Boris K; Kukarskikh, Galina P; Rubin, Andrei B; Sayre, Richard T; Ghirardi, Maria L; Seibert, Michael

    2007-10-01

    Photoproduction of H2 was examined in a series of sulfur-deprived Chlamydomonas reinhardtii D1-R323 mutants with progressively impaired PSII photochemical activity. In the R323H, R323D, and R323E D1 mutants, replacement of arginine affects photosystem II (PSII) function, as demonstrated by progressive decreases in O2-evolving activity and loss of PSII photochemical activity. Significant changes in PSII activity were found when the arginine residue was replaced by negatively charged amino acid residues (R323D and R323E). However, the R323H (positively charged or neutral, depending on the ambient pH) mutant had minimal changes in PSII activity. The R323H, R323D, and R323E mutants and the pseudo-wild-type (pWt) with restored PSII function were used to study the effects of sulfur deprivation on H2-production activity. All of these mutants exhibited significant changes in the normal parameters associated with the H2-photoproduction process, such as a shorter aerobic phase, lower accumulation of starch, a prolonged anaerobic phase observed before the onset of H2-production, a shorter duration of H2-production, lower H2 yields compared to the pWt control, and slightly higher production of dark fermentation products such as acetate and formate. The more compromised the PSII photochemical activity, the more dramatic was the effect of sulfur deprivation on the H2-production process, which depends both on the presence of residual PSII activity and the amount of stored starch. PMID:17701084

  15. Measurement of Elastic Photoproduction of J/psi Meson at ZEUS

    NASA Astrophysics Data System (ADS)

    Li, Canguo

    1995-01-01

    This dissertation describes the cross section measurement of the elastic photoproduction process gamma p to J/psi p performed at HERA using the ZEUS detector. HERA, the world's only electron -proton collider, provides photon-proton collisions via the well-known Bremsstrahlung process. The J/ psi was detected in its leptonic decay into a pair of e^+e^-. This measurement was based on a data sample collected in 1993 with an integrated electron-proton luminosity of 488nb^{ -1}, corresponding to an equivalent photon -proton luminosity of 55nb^{-1} . The signature of this process was a pair of e^+e^- detected in the central tracking detector without presence of any other particles in the main detector(scattered electron and proton traveling down the beam pipe were not observed). This corresponds to the range in the photon-proton center of mass energy W = 40GeV{~}140GeV and Q^2 < 4GeV^2 for the photon. Contribution from the diffractive photoproduction process gamma pto J/psi X, where the proton was dissociated into a jet of unspecified particles traveling down the beam pipe, was subtracted in the offline analysis. The cross section was determined to be (45 +/- 9_{stat }+/- 7_{sys} )nb. Compared with the cross sections measured before HERA at W < 28GeV, the rise of the cross section is better described by the QCD inspired models than by the extended vector-meson-dominance models, and corroborates the rise of the proton structure function F_2 previously observed in deep inelastic scattering at HERA.

  16. Bose-Einstein correlations between two neutral pions from photoproduction below 1.2 GeV

    NASA Astrophysics Data System (ADS)

    He, Qinghua; Hashimoto, Ryo; Ishikawa, Takatsugu; Masumoto, Shinichi; Miyabe, Manabu; Muramatsu, Norihito; Shimizu, Hajime; Tajima, Yasuhisa; Tsuchikawa, Yusuke; Yamazaki, Hirohito; Yamazaki, Ryuji; Forest Collaboration

    2014-09-01

    For the first time, we studied the space-time properties of the excited nucleons in the non-perturbative QCD region, via Bose-Einstein correlations (BEC) between two neutral pions from photoproduction off the proton/deuteron at incident photon energies below 1.2 GeV. In order to measure the Bose-Einstein correlations of two pions, an event mixing technique was developed and proved to be effective. The experiment was carried out at the Research Center for Electron Photon Science (ELPH) at Tohoku University. A 4 π electromagnetic calorimeter complex, named FOREST, was employed to detect neutral pions decaying into photons as well as some charged particles in the final state. In this work, we present the results of the spatial extension of the reaction region obtained from the BEC analysis. In addition, the BEC analysis provides useful information about the underlying mechanism of double neutral pion photoproduction. Preliminary results related to this study will be given.

  17. Upper limits for the photoproduction cross section for the Φ⁻⁻(1860) pentaquark state off the deuteron

    DOE PAGESBeta

    Egiyan, H.; Langheinrich, J.; Gothe, R. W.; Graham, L.; Holtrop, M.; Lu, H.; Mattione, P.; Mutchler, G.; Park, K.; Smith, E. S.; et al

    2012-01-30

    We searched for the Φ⁻⁻(1860) pentaquark in the photoproduction process off the deuteron in the Ξ⁻π⁻-decay channel using CLAS. The invariant-mass spectrum of the Ξ⁻π⁻ system does not indicate any statistically significant enhancement near the reported mass M=1.860 GeV. The statistical analysis of the sideband-subtracted mass spectrum yields a 90%-confidence-level upper limit of 0.7 nb for the photoproduction cross section of Φ⁻⁻(1860) with a consecutive decay intoΞ⁻π⁻ in the photon-energy range 4.5GeVγ<5.5GeV.

  18. Upper limits for the photoproduction cross section for the Φ⁻⁻(1860) pentaquark state off the deuteron

    SciTech Connect

    Egiyan, H.; Langheinrich, J.; Gothe, R. W.; Graham, L.; Holtrop, M.; Lu, H.; Mattione, P.; Mutchler, G.; Park, K.; Smith, E. S.; Stepanyan, S.; Zhao, Z. W.; Adhikari, K. P.; Aghasyan, M.; Anghinolfi, M.; Baghdasaryan, H.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Bedlinskiy, I.; Bennett, R. P.; Biselli, A. S.; Bookwalter, C.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Contalbrigo, M.; D’Angelo, A.; Daniel, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Dey, B.; Dickson, R.; Djalali, C.; Doughty, D.; Dupre, R.; El Alaoui, A.; El Fassi, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fradi, A.; Gabrielyan, M. Y.; Gevorgyan, N.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Griffioen, K. A.; Guidal, M.; Guler, N.; Guo, L.; Gyurjyan, V.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Heddle, D.; Hicks, K.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jo, H. S.; Joo, K.; Khetarpal, P.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Kubarovsky, V.; Kuleshov, S. V.; Livingston, K.; MacGregor, I. J. D.; Mao, Y.; Mayer, M.; McKinnon, B.; Mokeev, V.; Munevar, E.; Nadel-Turonski, P.; Ni, A.; Niculescu, G.; Ostrovidov, A. I.; Paolone, M.; Pappalardo, L.; Paremuzyan, R.; Park, S.; Pasyuk, E.; Anefalos Pereira, S.; Phelps, E.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Raue, B. A.; Ricco, G.; Rimal, D.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Seraydaryan, H.; Sharabian, Y. G.; Smith, G. D.; Sober, D. I.; Stepanyan, S. S.; Strauch, S.; Taiuti, M.; Tang, W.; Taylor, C. E.; Tedeschi, D. J.; Ungaro, M.; Voutier, E.; Watts, D. P.; Weinstein, L. B.; Weygand, D. P.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhao, B.

    2012-01-30

    We searched for the Φ⁻⁻(1860) pentaquark in the photoproduction process off the deuteron in the Ξ⁻π⁻-decay channel using CLAS. The invariant-mass spectrum of the Ξ⁻π⁻ system does not indicate any statistically significant enhancement near the reported mass M=1.860 GeV. The statistical analysis of the sideband-subtracted mass spectrum yields a 90%-confidence-level upper limit of 0.7 nb for the photoproduction cross section of Φ⁻⁻(1860) with a consecutive decay intoΞ⁻π⁻ in the photon-energy range 4.5GeVγ<5.5GeV.

  19. Polarization observables in the longitudinal basis for pseudo-scalar meson photoproduction using a density matrix approach

    SciTech Connect

    Biplab Dey, Michael E. McCracken, David G. Ireland, Curtis A. Meyer

    2011-05-01

    The complete expression for the intensity in pseudo-scalar meson photoproduction with a polarized beam, target, and recoil baryon is derived using a density matrix approach that offers great economy of notation. A Cartesian basis with spins for all particles quantized along a single direction, the longitudinal beam direction, is used for consistency and clarity in interpretation. A single spin-quantization axis for all particles enables the amplitudes to be written in a manifestly covariant fashion with simple relations to those of the well-known CGLN formalism. Possible sign discrepancies between theoretical amplitude-level expressions and experimentally measurable intensity profiles are dealt with carefully. Our motivation is to provide a coherent framework for coupled-channel partial-wave analysis of several meson photoproduction reactions, incorporating recently published and forthcoming polarization data from Jefferson Lab.

  20. A novel photoproduct of 2'-deoxyguanosine induced by acetone photosensitization: 8-(2,3,4-trihydroxybutyl)guanine.

    PubMed Central

    Sharma, N D; Davies, R J; Phillips, D R; McCloskey, J A

    1989-01-01

    Acetone photosensitisation of 2'-deoxyguanosine in deaerated aqueous solution gives 8-(2,3,4-trihydroxybutyl)guanine as a major photoproduct. Its structure and that of its tetraacetate have been determined primarily by high resolution 1H NMR and mass spectrometry; a di-isopropylidene derivative has also been prepared. Mechanistic aspects of this novel photochemical transformation are discussed, particularly in relation to the alkaline cleavage of acetone photosensitised DNA at the sites of guanine bases. PMID:2922279

  1. Characterization of the Intermediate in and Identification of the Repair Mechanism of (6-4) Photolesions by Photolyases.

    PubMed

    Faraji, Shirin; Zhong, Dongping; Dreuw, Andreas

    2016-04-18

    Quantum mechanics/molecular mechanics calculations are employed to assign previously recorded experimental spectroscopic signatures of the intermediates occurring during the photo-induced repair of (6-4) photolesions by photolyases to specific molecular structures. Based on this close comparison of experiment and theory it is demonstrated that the acting repair mechanism involves proton transfer from the protonated His365 to the N3' nitrogen of the lesion, which proceeds simultaneously with intramolecular OH transfer along an oxetane-like transition state. PMID:26996356

  2. Mechanistic Studies of the Spore Photoproduct Lyase (SPL) via a Single Cysteine Mutation

    PubMed Central

    Yang, Linlin; Lin, Gengjie; Nelson, Renae S.; Jian, Yajun; Telser, Joshua; Li, Lei

    2012-01-01

    5-thyminyl-5,6-dihydrothymine (also called spore photoproduct or SP) is the exclusive DNA photo-damage product in bacterial endospores. It is repaired by a radical SAM (S-adenosylmethionine) enzyme, the spore photoproduct lyase (SPL), at the bacterial early germination phase. Our previous studies proved that SPL utilizes the 5′-dA• generated by SAM cleavage reaction to abstract the H6proR atom to initiate the SP repair process. The resulting thymine allylic radical was suggested to take an H atom from an unknown protein source, most likely the cysteine 141. Here we show that C141 can be readily alkylated in the native SPL by iodoacetamide treatment, suggesting that it is accessible to the TpT radical. SP repair by the SPL C141A mutant yields TpTSO2− and TpT simultaneously from the very beginning of the reaction; no lag phase is observed for the TpTSO2− formation. Should any other protein residue serve as the H donor, its presence would result in TpT as the major product at least for the first enzyme turnover. These observations provide strong evidence to support C141 as the direct H atom donor. Moreover, due to the lack of this intrinsic H donor, the C141A mutant produces TpT via an unprecedented thymine cation radical reduction (proton coupled electron transfer) process, contrasting to the H atom transfer mechanism in the WT SPL reaction. The C141A mutant repairs SP at a rate which is ~3-fold slower than the WT enzyme. Formation of TpTSO2− and TpT exhibit a Vmax deuterium kinetic isotope effect (KIE) of 1.7 ± 0.2 respectively, which is smaller than the DVmax KIE of 2.8 ± 0.3 determined in the WT SPL reaction. These findings suggest that removing the intrinsic H atom donor disturbs the rate-limiting process in the enzyme catalysis. As expected, the pre-reduced C141A mutant only supports ~ 0.4 turnover, which is in sharp contrast to the > 5 turnovers exhibited by the WT SPL reaction, suggesting that the enzyme catalytic cycle (SAM regeneration) is

  3. Mechanistic studies of the radical SAM enzyme spore photoproduct lyase (SPL).

    PubMed

    Li, Lei

    2012-11-01

    Spore photoproduct lyase (SPL) repairs a special thymine dimer 5-thyminyl-5,6-dihydrothymine, which is commonly called spore photoproduct or SP at the bacterial early germination phase. SP is the exclusive DNA photo-damage product in bacterial endospores; its generation and swift repair by SPL are responsible for the spores' extremely high UV resistance. The early in vivo studies suggested that SPL utilizes a direct reversal strategy to repair the SP in the absence of light. The research in the past decade further established SPL as a radical SAM enzyme, which utilizes a tri-cysteine CXXXCXXC motif to harbor a [4Fe-4S] cluster. At the 1+ oxidation state, the cluster provides an electron to the S-adenosylmethionine (SAM), which binds to the cluster in a bidentate manner as the fourth and fifth ligands, to reductively cleave the CS bond associated with the sulfonium ion in SAM, generating a reactive 5'-deoxyadenosyl (5'-dA) radical. This 5'-dA radical abstracts the proR hydrogen atom from the C6 carbon of SP to initiate the repair process; the resulting SP radical subsequently fragments to generate a putative thymine methyl radical, which accepts a back-donated H atom to yield the repaired TpT. SAM is suggested to be regenerated at the end of each catalytic cycle; and only a catalytic amount of SAM is needed in the SPL reaction. The H atom source for the back donation step is suggested to be a cysteine residue (C141 in Bacillus subtilis SPL), and the H-atom transfer reaction leaves a thiyl radical behind on the protein. This thiyl radical thus must participate in the SAM regeneration process; however how the thiyl radical abstracts an H atom from the 5'-dA to regenerate SAM is unknown. This paper reviews and discusses the history and the latest progress in the mechanistic elucidation of SPL. Despite some recent breakthroughs, more questions are raised in the mechanistic understanding of this intriguing DNA repair enzyme. This article is part of a Special Issue

  4. Exclusive Photoproduction of Charged Pions in Hydrogen and Deuterium from 1 to 6 GeV

    SciTech Connect

    Lingyan Zhu

    2004-02-28

    The study of the transition region in the description of exclusive processes and hadron structure, from the nucleon-meson degrees of freedom in meson-exchange models at low energy to the quark-gluon degrees of freedom in pQCD at high energy, is essential for us to understand the strong interaction. The differential cross section measurements for exclusive reactions at fixed center-of-mass angles enable us to investigate the constituent counting rule, which explicitly connects the quark-gluon degrees of freedom to the energy dependence of differential cross sections. JLab Experiment E94-104 was carried out in Hall A with two high resolution spectrometers. It included the coincidence cross section measurement for the [gamma]n --> pi{sup -}[p] process with a deuterium target and the singles measurement for the [gamma]p --> pi{sup +}[n] process with a hydrogen target. The untagged real photons were generated by the electron beam impinging on a copper radiator. The photon energies ranged from 1.1 to 5.5 GeV, corresponding to the center-of-mass energies from 1.7 to 3.4 GeV. The pion center-of-mass angles were fixed at 50 deg, 70 deg, 90 deg, and also 100 deg, 110 deg at a few energies. The JLab E94-104 data presented in this thesis contain four interesting features. The data exhibit a global scaling behavior for both [pi]{sup -} and [pi]{sup +} photoproduction at high energies and high transverse momenta, consistent with the constituent counting rule and the existing [pi]{sup +} photoproduction data. This implies that the quark-gluon degrees of freedom start to play a role at this energy scale. The data suggests possible substructure of the scaling behavior, which might be oscillations around the scaling value. There are several possible mechanisms that can cause oscillations, for example the one associated with the generalized constituent counting rule involving quark orbital angular momentum. The data show an enhancement in the scaled cross section at center

  5. Mechanism elucidation of the radical SAM enzyme spore photoproduct lyase (SPL)

    PubMed Central

    Li, Lei

    2011-01-01

    Spore photoproduct lyase (SPL) repairs a special thymine dimer 5-thyminyl-5,6-dihydrothymine, which is commonly called spore photoproduct or SP at the bacterial early germination phase. SP is the exclusive DNA photo-damage product in bacterial endospores; its generation and swift repair by SPL are responsible for the spores’ extremely high UV resistance. The early in vivo studies suggested that SPL utilizes a direct reversal strategy to repair the SP in the absence of light. The research in the past decade further established SPL as a radical SAM enzyme, which utilizes a tri-cysteine CXXXCXXC motif to harbor a [4Fe-4S] cluster. At the 1+ oxidation state, the cluster provides an electron to the S-adenosylmethionine (SAM), which binds to the cluster in a bidentate manner as the fourth and fifth ligands, to reductively cleave the C-S bond associated with the sulfonium ion in SAM, generating a reactive 5′-deoxyadenosyl (5′-dA) radical. This 5′-dA radical abstracts the proR hydrogen atom from the C6 carbon of SP to initiate the repair process; the resulting SP radical subsequently fragments to generate a putative thymine methyl radical, which accepts a back-donated H atom to yield the repaired TpT. SAM is suggested to be regenerated at the end of each catalytic cycle; and only a catalytic amount of SAM is needed in the SPL reaction. The H atom source for the back donation step is suggested to be a cysteine residue (C141 in B. subtilis SPL), and the H-atom transfer reaction leaves a thiyl radical behind on the protein. This thiyl radical thus must participate in the SAM regeneration process; however how the thiyl radical abstracts an H atom from the 5′-dA to regenerate SAM is unknown. This paper reviews and discusses the history and the latest progress in the mechanistic elucidation of SPL. Despite some recent breakthroughs, more questions are raised in the mechanistic understanding of this intriguing DNA repair enzyme. PMID:22197590

  6. Parameterization of Highly Charged Metal Ions Using the 12-6-4 LJ-Type Nonbonded Model in Explicit Water

    PubMed Central

    2015-01-01

    Highly charged metal ions act as catalytic centers and structural elements in a broad range of chemical complexes. The nonbonded model for metal ions is extensively used in molecular simulations due to its simple form, computational speed, and transferability. We have proposed and parametrized a 12-6-4 LJ (Lennard-Jones)-type nonbonded model for divalent metal ions in previous work, which showed a marked improvement over the 12-6 LJ nonbonded model. In the present study, by treating the experimental hydration free energies and ion–oxygen distances of the first solvation shell as targets for our parametrization, we evaluated 12-6 LJ parameters for 18 M(III) and 6 M(IV) metal ions for three widely used water models (TIP3P, SPC/E, and TIP4PEW). As expected, the interaction energy underestimation of the 12-6 LJ nonbonded model increases dramatically for the highly charged metal ions. We then parametrized the 12-6-4 LJ-type nonbonded model for these metal ions with the three water models. The final parameters reproduced the target values with good accuracy, which is consistent with our previous experience using this potential. Finally, tests were performed on a protein system, and the obtained results validate the transferability of these nonbonded model parameters. PMID:25145273

  7. Effect of Electron Beam Freeform Fabrication (EBF3) Processing Parameters on Composition of Ti-6-4

    NASA Technical Reports Server (NTRS)

    Lach, Cynthia L.; Taminger, Karen; Schuszler, A. Bud, II; Sankaran, Sankara; Ehlers, Helen; Nasserrafi, Rahbar; Woods, Bryan

    2007-01-01

    The Electron Beam Freeform Fabrication (EBF3) process developed at NASA Langley Research Center was evaluated using a design of experiments approach to determine the effect of processing parameters on the composition and geometry of Ti-6-4 deposits. The effects of three processing parameters: beam power, translation speed, and wire feed rate, were investigated by varying one while keeping the remaining parameters constant. A three-factorial, three-level, fully balanced mutually orthogonal array (L27) design of experiments approach was used to examine the effects of low, medium, and high settings for the processing parameters on the chemistry, geometry, and quality of the resulting deposits. Single bead high deposits were fabricated and evaluated for 27 experimental conditions. Loss of aluminum in Ti-6-4 was observed in EBF3 processing due to selective vaporization of the aluminum from the sustained molten pool in the vacuum environment; therefore, the chemistries of the deposits were measured and compared with the composition of the initial wire and base plate to determine if the loss of aluminum could be minimized through careful selection of processing parameters. The influence of processing parameters and coupling between these parameters on bulk composition, measured by Direct Current Plasma (DCP), local microchemistries determined by Wavelength Dispersive Spectrometry (WDS), and deposit geometry will also be discussed.

  8. Theoretical investigation of optical and paramagnetic resonance spectra of [NiF6]4- clusters with orthorhombic symmetry

    NASA Astrophysics Data System (ADS)

    Fang, Wang; Shao, Chang-Sheng; Cheng, Wen-De; Tang, Hai-Yan; Zheng, Wen-Chen

    2013-11-01

    The ground state absorption spectra of [NiF6]4- clusters with orthorhombic symmetry (Ni2+ in NiF2 crystal and Ni2+-doped ZnF2 crystal, D2h point group) are theoretically calculated and assigned by diagonalization of 45 × 45 complete energy matrix for 3d8 configuration and the spin-Hamiltonian (SH) parameters (zero-field splitting D and E, and g factors gx, gy, gz) are studied by use of high-order perturbation method, in the frame of semi-empirical molecular orbital (MO) scheme based on strong crystal field framework. In those energy matrix, all the configuration interactions though the cubic crystal field (CF), the orthorhombic crystal field, the Coulomb interaction are taken into account. The calculated results are in good agreement with the experimental data. The local structure (bond length and bond angle) of [NiF6]4- clusters are determined, and the results shows that the structure data given by Stout are more plausible than those given by Baur.

  9. Theoretical investigation of optical and paramagnetic resonance spectra of [NiF6](4-) clusters with orthorhombic symmetry.

    PubMed

    Fang, Wang; Shao, Chang-Sheng; Cheng, Wen-De; Tang, Hai-Yan; Zheng, Wen-Chen

    2013-11-01

    The ground state absorption spectra of [NiF6](4-) clusters with orthorhombic symmetry (Ni(2+) in NiF2 crystal and Ni(2+)-doped ZnF2 crystal, D2h point group) are theoretically calculated and assigned by diagonalization of 45×45 complete energy matrix for 3d(8) configuration and the spin-Hamiltonian (SH) parameters (zero-field splitting D and E, and g factors gx, gy, gz) are studied by use of high-order perturbation method, in the frame of semi-empirical molecular orbital (MO) scheme based on strong crystal field framework. In those energy matrix, all the configuration interactions though the cubic crystal field (CF), the orthorhombic crystal field, the Coulomb interaction are taken into account. The calculated results are in good agreement with the experimental data. The local structure (bond length and bond angle) of [NiF6](4-) clusters are determined, and the results shows that the structure data given by Stout are more plausible than those given by Baur. PMID:23871975

  10. Crystal structures of ethyl 6-(4-methyl-phen-yl)-4-oxo-4H-chromene-2-carboxyl-ate and ethyl 6-(4-fluoro-phen-yl)-4-oxo-4H-chromene-2-carboxyl-ate.

    PubMed

    Gomes, Ligia R; Low, John Nicolson; Fernandes, Carlos; Gaspar, Alexandra; Borges, Fernanda

    2016-01-01

    The crystal structures of two chromone derivatives, viz. ethyl 6-(4-methyl-phen-yl)-4-oxo-4H-chromene-2-carboxyl-ate, C19H16O4, (1), and ethyl 6-(4-fluoro-phen-yl)-4-oxo-4H-chromene-2-carboxyl-ate C18H13FO4, (2), have been determined: (1) crystallizes with two mol-ecules in the asymmetric unit. A comparison of the dihedral angles beween the mean planes of the central chromone core with those of the substituents, an ethyl ester moiety at the 2-position and a para-substituted phenyl ring at the 6-position shows that each mol-ecule differs significantly from the others, even the two independent mol-ecules (a and b) of (1). In all three mol-ecules, the carbonyl groups of the chromone and the carboxyl-ate are trans-related. The supra-molecular structure of (1) involves only weak C-H⋯π inter-actions between H atoms of the substituent phenyl group and the phenyl group, which link mol-ecules into a chain of alternating mol-ecules a and b, and weak π-π stacking inter-actions between the chromone units. The packing in (2) involves C-H⋯O inter-actions, which form a network of two inter-secting ladders involving the carbonyl atom of the carboxyl-ate group as the acceptor for H atoms at the 7-position of the chromone ring and from an ortho-H atom of the exocyclic benzene ring. The carbonyl atom of the chromone acts as an acceptor from a meta-H atom of the exocyclic benzene ring. π-π inter-actions stack the mol-ecules by unit translation along the a axis. PMID:26870574

  11. The investigation of strangeness photoproduction in the threshold region at ELPH-Tohoku

    NASA Astrophysics Data System (ADS)

    Kaneta, M.; Beckford, B.; Bydžovský, P.; Fujibayashi, T.; Fujii, T.; Fujii, Y.; Futatsukawa, K.; Gogami, T.; Han, Y. C.; Hashimoto, O.; Hirose, K.; Hosomi, K.; Honda, R.; Iguchi, A.; Ishikawa, T.; Kanda, H.; Kaneko, Y.; Kasai, Y.; Kawasaki, T.; Kimura, C.; Kiyokawa, S.; Koike, T.; Maeda, K.; Maruyama, N.; Matsubara, M.; Miwa, K.; Miyagi, Y.; Nagao, S.; Nakamura, S. N.; Okuyama, A.; Sotona, M.; Tamae, T.; Tamura, H.; Tsukada, K.; Terada, N.; Wang, T. S.; Yamamoto, F.; Yamamoto, T. O.; Yamazaki, H.

    2013-09-01

    The strangeness photoproduction processes near the threshold have been intensively studied by measuring K+ in reactions such as γ+p→K++Λ(Σ0). There has been no reliable data on the neutron and as a consequence theoretical investigation suffered seriously from the lack of the data. We have an effort to measure the γ+d→K0(Λ)+X reaction in the π+π- (pπ-) decay channel of KS0 (Λ) using a liquid D2 target and internally-tagged photon beams (Eγ=0.80-1.08 GeV) at Research Center for Electron Photon Science (ELPH), Tohoku University. We have renewed the spectrometer (NKS2) and took data with a liquid D2 target in 2005-2007. More recently, we took data in 2010 after a detector upgrade in the vertex region to substantially increase the acceptance. The results of Λ single measurements on a deuterium target were obtained for differential cross-section as a function of momentum, as a function of angle, and integrated cross-section as a function of beam energy. The results are compared with recent theoretical studies: Isobar models (Kaon-MAID and Saclay-Lyon A) and a Regge-plus-Resonance model.

  12. Investigation of Strangeness Photoproduction near the Threshold at ELPH, Tohoku University

    NASA Astrophysics Data System (ADS)

    Kaneta, Masashi; Beckford, Brian; Bydžovský, Petr; Fujibayashi, Takeshi; Fujii, Takao; Fujii, Yu; Futatsukawa, Kenta; Gogami, Toshiyuki; Han, Yuncheng; Hashimoto, Osamu; Hirose, Kentaro; Hosomi, Kenji; Honda, Ryotarou; Iguchi, Aran; Ishikawa, Takatsugu; Kanda, Hiroki; Kaneko, Yusuke; Kasai, Yuma; Kawasaki, Taito; Kimura, Chigusa; Kiyokawa, Shogo; Koike, Takeshi; Maeda, Kazushige; Maruyama, Nayuta; Matsubara, Masao; Miwa, Koji; Miyagi, Yohei; Nagao, Sho; Nakamura, Satoshi N.; Nishizawa, Takashi; Okuyama, Akira; Sotona, Miloslav; Tamae, Tadaaki; Tamura, Hirokazu; Tsukada, Kyo; Terada, Nobu; Wang, Tieshan; Yamamoto, Fumiya; Yamamoto, Takeshi O.; Yamazaki, Hirohito

    The strangeness photoproduction processes in the threshold region have been intensively studied by measuring K+ in reactions such as γ + P → K+ + Λ(Σ0). There has been no reliable data on the neutron and as a consequence theoretical investigation suffered seriously from the lack of the data. We have made a significant effort to measure the γ + d → K0(Λ) + X reaction in the π+π- (pπ-) decay channel of KS0 (Λ) using a liquid D2 target and internally-tagged photon beams (Eγ = 0.80-1.08 GeV) at Research Center for Electron Photon Science (ELPH), Tohoku University. We have renewed the spectrometer (NKS2) and took data with a liquid D2 target in 2005-2007. More recently, we took data in 2010 after a detector upgrade in the vertex region to substantially increase the acceptance. The results of Λ single measurements on a deuterium target were obtained for differential cross-section as a function of momentum, as a function of angle, and integrated cross-section as a function of beam energy. The results are compared with recent theoretical studies: Isobar models (Kaon-MAID and Saclay-Lyon A) and a Regge-plus-Resonance model.

  13. Genotoxicity of sulcotrione pesticide and photoproducts on Allium cepa root meristem.

    PubMed

    Goujon, Eric; Sta, Chaima; Trivella, Aurélien; Goupil, Pascale; Richard, Claire; Ledoigt, Gérard

    2014-07-01

    Contamination by toxic agents in the environment has become matters of concern to agricultural countries. Sulcotrione, a triketone herbicide used to control dicotyledonous weeds in maize culture is rapidly photolyzed on plant foliage and generate two main photoproducts the xanthene-1,9-dione-3,4-dihydro-6-methylsulfonyl and 2-chloro-4-mesylbenzoic acid (CMBA). The aim of this study was to analyze the potential toxicity of the herbicide and the irradiated herbicide cocktail. Cytotoxicity and genotoxicity of non irradiated and irradiated sulcotrione were investigated in Allium cepa test. The sulcotrione irradiation was monitored under sunlight simulated conditions to reach 50% of phototransformation. Concentrations of sulcotrione in the range 5 × 10(-)(9)-5 × 10(-)(5)M were tested. Cytological analysis of root tips cells showed that both non irradiated and irradiated sulcotrione caused a dose-dependent decrease of mitotic index with higher cytotoxicity for the irradiated herbicide which can lead to 24.2% reduction of mitotic index compared to water control. Concomitantly, chromosomal aberrations were observed in A.cepa root meristems. Both non irradiated sulcotrione and irradiated sulcotrione induced a dose-dependent increase of chromosomal abnormalities frequencies to a maximal value of 33.7%. A saturating effect in anomaly frequencies was observed in meristems treated with high concentrations of non irradiated sulcotrione only. These data suggest that photolyzed sulcotrione cocktail have a greater cytotoxicity and genotoxicity than parent molecule and question about the impact of photochemical process on environment. PMID:25052526

  14. DNA repair of a single UV photoproduct in a designed nucleosome

    SciTech Connect

    Kosmoskil, Joseph V.; Ackerman, Eric J. ); Smerdon, Michael J.

    2001-08-28

    Eukaryotic DNA repair enzymes must interact with the architectural hierarchy of chromatin. The challenge of finding damaged DNA complexed with histone proteins in nucleosomes is complicated by the need to maintain local chromatin structures involved in regulating other DNA processing events. The heterogeneity of lesions induced by DNA-damaging agents has led us to design homogeneously damaged substrates to directly compare repair of naked DNA with that of nucleosomes. Here we report that nucleotide excision repair in Xenopus nuclear extracts can effectively repair a single UV radiation photoproduct located 5 bases from the dyad center of a positioned nucleosome, although the nucleosome is repaired at about half the rate at which the naked DNA fragment is. Extract repair within the nucleosome is > 50-fold more rapid than either enzymatic photoreversal or endonuclease cleavage of the lesion in vitro. Furthermore, nucleosome formation occurs (after repair) only on damaged naked DNA ( 165-bp fragments) during a 1-h incubation in these extracts, even in the presence of a large excess of undamaged DNA. This is an example of selective nucleosome assembly by Xenopus nuclear extracts on a short linear DNA fragment containing a DNA lesion.

  15. Search for Resonances in the Photoproduction of Proton-Antiproton Pairs

    SciTech Connect

    Burnham Stokes

    2006-06-30

    Results are reported on the reaction {gamma}p {yields} p{bar p}p with beam energy in the range 4.8-5.5 GeV. The data were collected at the Thomas Jefferson National Accelerator Facility in CLAS experiment E01-017(G6C). The focus of this study is an understanding of the mechanisms of photoproduction of proton-antiproton pairs, and to search for intermediate resonances, both narrow and broad, which decay to p{bar p}. The total measured cross section in the photon energy range 4.8-5.5 GeV is {sigma} = 33 {+-} 2 nb. Measurement of the cross section as a function of energy is provided. An upper limit on the production of a narrow resonance state previously observed with a mass of 2.02 GeV/c{sup 2} is placed at 0.35 nb. No intermediate resonance states were observed. Meson exchange production appears to dominate the production of the proton-antiproton pairs.

  16. Helicity asymmetry E measurement for single pi^0 photoproduction with a frozen spin target

    SciTech Connect

    Hideko Iwamoto

    2012-04-01

    The helicity asymmetry for single neutral pion photoproduction was measured using the CLAS detector in Hall B at the Thomas Jefferson National Accelerator Facility. This measurement used longitudinally polarized protons and circularly polarized photons with photon energies between 0.35 GeV to 2.4 GeV. The target was a frozen-spin butanol (C{sub 4}H{sub 9}OH) target, polarized at about 85%. The helicity asymmetry E for the {gamma}p {yields} p{pi}{sup 0} was measured with missing-mass technique at the high statistics of about 12 x 10{sup 6} events. The experimental results are compared to three available theoretical predictions, SAID, MAID, and EBAC. The preliminary results are in good agreement with the model calculations at low E{sub {gamma}} energy bins. However, a significant deviation is observed at high energy bins. Therefore, the new data will help to constrain the parameters of the theoretical models.

  17. Photodegradation of fluoroquinolones in surface water and antimicrobial activity of the photoproducts.

    PubMed

    Sturini, Michela; Speltini, Andrea; Maraschi, Federica; Pretali, Luca; Profumo, Antonella; Fasani, Elisa; Albini, Angelo; Migliavacca, Roberta; Nucleo, Elisabetta

    2012-11-01

    The widespread presence of fluoroquinolone antibiotics (FQs) in natural ecosystems is a health hazard for humans and other living organisms. The role of sunlight in degrading FQs present in environmental waters has been studied. In particular, the photodegradation of four largely employed FQs, viz. Ciprofloxacin (CIP), Danofloxacin (DAN), Levofloxacin (LEV) and Moxifloxacin (MOX) has been studied in not tampered river water. Degradation rates have been investigated at ppb levels (20-50 μg L(-1)) under solar light, and the results have been commented critically. The products distribution has been studied by HPLC-ESI-MS/MS analysis and structures have been attributed on the basis of their mass fragmentation spectra. Importantly from the environmental point of view, the (potentially toxic) FQ nucleus remained intact over the early stages of the degradation. Indeed, the photoproducts were proved to possess residual antibacterial activity, as shown from in vitro antibacterial activity tests against different well characterized human and environmental bacterial strains, carried out on the above FQs, as well as for Enrofloxacin (ENR) and Marbofloxacin (MAR). PMID:22901305

  18. Low-energy {omega} ({yields}{pi}{sup 0}{gamma}) meson photoproduction in the nucleus

    SciTech Connect

    Das, Swapan

    2011-06-15

    The {pi}{sup 0{gamma}} invariant mass distribution spectra in the ({gamma},{pi}{sup 0{gamma}}) reaction were measured by the TAPS/ELSA Collaboration to look for the hadron parameters of the {omega} meson in the Nb nucleus. We study the mechanism for this reaction, where we consider that the elementary reaction in the Nb nucleus proceeds as {gamma}N{yields}{omega}N;{omega}{yields}{pi}{sup 0}{gamma}. The {omega}-meson photoproduction amplitude for this reaction is extracted from the measured four-momentum transfer distribution in the {gamma}p{yields}{omega}p reaction. The propagation of the {omega} meson and the distorted wave function for the {pi}{sup 0} meson in the final state are described by the eikonal form. The {omega} and {pi}{sup 0} mesons' nucleus optical potentials, appearing in the {omega} meson propagator and {pi}{sup 0} meson distorted wave function respectively, are estimated using the t{rho} approximation. The effects of pair correlation and color transparency are also studied. The calculated results do not show medium modification for the {omega} meson produced in the nucleus for momentum greater than 200 MeV. It occurs because the {omega} meson predominantly decays outside the nucleus. The dependence of the cross section on the final-state interaction is also investigated. The broadening of the {omega}-meson mass distribution spectra is shown to occur due to the large resolution width associated with the detector used in the experiment.

  19. Photoproduction of J /ψ mesons in peripheral and semicentral heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Kłusek-Gawenda, Mariola; Szczurek, Antoni

    2016-04-01

    We calculate total and differential cross sections for J /ψ photoproduction in ultrarelativistic lead-lead collisions at the LHC energy √{sN N}=2.76 TeV. In the present approach we use a simple model based on vector dominance picture and multiple scattering of the hadronic (c c ¯ ) state in a cold nucleus as an example. In our analysis we use both the classical mechanics and quantum (Glauber) formulas for calculating σtot ,J /ψ P b which is a building block of our model. We compare our UPC results with ALICE and CMS data. For semicentral collisions (b

  20. Diffractive photoproduction of /J/ψ mesons with large momentum transfer at HERA

    NASA Astrophysics Data System (ADS)

    H1 Collaboration; Aktas, A.; Andreev, V.; Anthonis, T.; Astvatsatourov, A.; Babaev, A.; Backovic, S.; Bähr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Baumgartner, S.; Becker, J.; Beckingham, M.; Beglarian, A.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, Ch.; Berndt, T.; Bizot, J. C.; Böhme, J.; Boenig, M.-O.; Boudry, V.; Bracinik, J.; Braunschweig, W.; Brisson, V.; Bröker, H.-B.; Brown, D. P.; Bruncko, D.; Büsser, F. W.; Bunyatyan, A.; Burrage, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A. J.; Caron, S.; Cassol-Brunner, F.; Chekelian, V.; Clarke, D.; Collard, C.; Contreras, J. G.; Coppens, Y. R.; Coughlan, J. A.; Cousinou, M.-C.; Cox, B. E.; Cozzika, G.; Cvach, J.; Dainton, J. B.; Dau, W. D.; Daum, K.; Davidsson, M.; Delcourt, B.; Delerue, N.; Demirchyan, R.; de Roeck, A.; de Wolf, E. A.; Diaconu, C.; Dingfelder, J.; Dixon, P.; Dodonov, V.; Dowell, J. D.; Dubak, A.; Duprel, C.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P. J. W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Ferron, S.; Fleischer, M.; Fleischmann, P.; Fleming, Y. H.; Flucke, G.; Flügge, G.; Fomenko, A.; Foresti, I.; Formánek, J.; Franke, G.; Frising, G.; Gabathuler, E.; Gabathuler, K.; Garvey, J.; Gassner, J.; Gayler, J.; Gerhards, R.; Gerlich, C.; Ghazaryan, S.; Goerlich, L.; Gogitidze, N.; Gorbounov, S.; Grab, C.; Grabski, V.; Grässler, H.; Greenshaw, T.; Grindhammer, G.; Haidt, D.; Hajduk, L.; Haller, J.; Heinemann, B.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Henshaw, O.; Heremans, R.; Herrera, G.; Herynek, I.; Hildebrandt, M.; Hilgers, M.; Hiller, K. H.; Hladký, J.; Höting, P.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Ibbotson, M.; Jacquet, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jönsson, L.; Johnson, C.; Johnson, D. P.; Jones, M. A. S.; Jung, H.; Kant, D.; Kapichine, M.; Karlsson, M.; Katzy, J.; Keil, F.; Keller, N.; Kennedy, J.; Kenyon, I. R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Kluge, T.; Knies, G.; Koblitz, B.; Kolya, S. D.; Korbel, V.; Kostka, P.; Koutouev, R.; Koutov, A.; Kroseberg, J.; Krüger, K.; Kueckens, J.; Kuhr, T.; Landon, M. P. J.; Lange, W.; Laštovička, T.; Laycock, P.; Lebedev, A.; Leißner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; List, B.; Lobodzinska, E.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lueders, H.; Lüders, S.; Lüke, D.; Lytkin, L.; Makankine, A.; Malden, N.; Malinovski, E.; Mangano, S.; Marage, P.; Marks, J.; Marshall, R.; Martyn, H.-U.; Martyniak, J.; Maxfield, S. J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A. B.; Meyer, H.; Meyer, J.; Michine, S.; Mikocki, S.; Milstead, D.; Mohrdieck, S.; Moreau, F.; Morozov, A.; Morris, J. V.; Müller, K.; Murín, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, Th.; Newman, P. R.; Niebergall, F.; Niebuhr, C.; Nikitin, D.; Nowak, G.; Nozicka, M.; Olivier, B.; Olsson, J. E.; Ozerov, D.; Panassik, V.; Pascaud, C.; Patel, G. D.; Peez, M.; Perez, E.; Petrukhin, A.; Phillips, J. P.; Pitzl, D.; Pöschl, R.; Povh, B.; Raicevic, N.; Rauschenberger, J.; Reimer, P.; Reisert, B.; Risler, C.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rusakov, S.; Rybicki, K.; Sankey, D. P. C.; Sauvan, E.; Schätzel, S.; Scheins, J.; Schilling, F.-P.; Schleper, P.; Schmidt, D.; Schmidt, S.; Schmitt, S.; Schneider, M.; Schoeffel, L.; Schöning, A.; Schröder, V.; Schultz-Coulon, H.-C.; Schwanenberger, C.; Sedlák, K.; Sefkow, F.; Sheviakov, I.; Shtarkov, L. N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, A.; Spitzer, H.; Stamen, R.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Thompson, G.; Thompson, P. D.; Tomasz, F.; Traynor, D.; Truöl, P.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Turney, J. E.; Tzamariudaki, E.; Uraev, A.; Urban, M.; Usik, A.; Valkár, S.; Valkárová, A.; Vallée, C.; van Mechelen, P.; Vargas Trevino, A.; Vassiliev, S.; Vazdik, Y.; Veelken, C.; Vest, A.; Vichnevski, A.; Volchinski, V.; Wacker, K.; Wagner, J.; Wallny, R.; Waugh, B.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; Wessling, B.; Winde, M.; Winter, G.-G.; Wissing, Ch.; Woehrling, E.-E.; Wünsch, E.; Wyatt, A. C.; Žáček, J.; Zálešák, J.; Zhang, Z.; Zhokin, A.; Zomer, F.; Zur Nedden, M.

    2003-08-01

    The diffractive photoproduction of /J/ψ mesons is measured with the H1 detector at the /ep collider HERA using an integrated luminosity of 78 pb-1. The differential cross section /dσ(γp-->J/ψY)/dt is studied in the range 2

  1. Diffractive photoproduction of J/ ψ mesons with large momentum transfer at HERA

    NASA Astrophysics Data System (ADS)

    Aktas, A.; Andreev, V.; Anthonis, T.; Astvatsatourov, A.; Babaev, A.; Backovic, S.; Bähr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Baumgartner, S.; Becker, J.; Beckingham, M.; Beglarian, A.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, Ch.; Berndt, T.; Bizot, J. C.; Böhme, J.; Boenig, M.-O.; Boudry, V.; Bracinik, J.; Braunschweig, W.; Brisson, V.; Bröker, H.-B.; Brown, D. P.; Bruncko, D.; Büsser, F. W.; Bunyatyan, A.; Burrage, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A. J.; Caron, S.; Cassol-Brunner, F.; Chekelian, V.; Clarke, D.; Collard, C.; Contreras, J. G.; Coppens, Y. R.; Coughlan, J. A.; Cousinou, M.-C.; Cox, B. E.; Cozzika, G.; Cvach, J.; Dainton, J. B.; Dau, W. D.; Daum, K.; Davidsson, M.; Delcourt, B.; Delerue, N.; Demirchyan, R.; De Roeck, A.; De Wolf, E. A.; Diaconu, C.; Dingfelder, J.; Dixon, P.; Dodonov, V.; Dowell, J. D.; Dubak, A.; Duprel, C.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P. J. W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Ferron, S.; Fleischer, M.; Fleischmann, P.; Fleming, Y. H.; Flucke, G.; Flügge, G.; Fomenko, A.; Foresti, I.; Formánek, J.; Franke, G.; Frising, G.; Gabathuler, E.; Gabathuler, K.; Garvey, J.; Gassner, J.; Gayler, J.; Gerhards, R.; Gerlich, C.; Ghazaryan, S.; Goerlich, L.; Gogitidze, N.; Gorbounov, S.; Grab, C.; Grabski, V.; Grässler, H.; Greenshaw, T.; Grindhammer, G.; Haidt, D.; Hajduk, L.; Haller, J.; Heinemann, B.; Heinzelmann, G.; Henderson, R. C. W.; Henschel, H.; Henshaw, O.; Heremans, R.; Herrera, G.; Herynek, I.; Hildebrandt, M.; Hilgers, M.; Hiller, K. H.; Hladký, J.; Höting, P.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Ibbotson, M.; Jacquet, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jönsson, L.; Johnson, C.; Johnson, D. P.; Jones, M. A. S.; Jung, H.; Kant, D.; Kapichine, M.; Karlsson, M.; Katzy, J.; Keil, F.; Keller, N.; Kennedy, J.; Kenyon, I. R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Kluge, T.; Knies, G.; Koblitz, B.; Kolya, S. D.; Korbel, V.; Kostka, P.; Koutouev, R.; Koutov, A.; Kroseberg, J.; Krüger, K.; Kueckens, J.; Kuhr, T.; Landon, M. P. J.; Lange, W.; Laštovička, T.; Laycock, P.; Lebedev, A.; Leißner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; List, B.; Lobodzinska, E.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lueders, H.; Lüders, S.; Lüke, D.; Lytkin, L.; Makankine, A.; Malden, N.; Malinovski, E.; Mangano, S.; Marage, P.; Marks, J.; Marshall, R.; Martyn, H.-U.; Martyniak, J.; Maxfield, S. J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A. B.; Meyer, H.; Meyer, J.; Michine, S.; Mikocki, S.; Milstead, D.; Mohrdieck, S.; Moreau, F.; Morozov, A.; Morris, J. V.; Müller, K.; Murín, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, Th.; Newman, P. R.; Niebergall, F.; Niebuhr, C.; Nikitin, D.; Nowak, G.; Nozicka, M.; Olivier, B.; Olsson, J. E.; Ozerov, D.; Panassik, V.; Pascaud, C.; Patel, G. D.; Peez, M.; Perez, E.; Petrukhin, A.; Phillips, J. P.; Pitzl, D.; Pöschl, R.; Povh, B.; Raicevic, N.; Rauschenberger, J.; Reimer, P.; Reisert, B.; Risler, C.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rusakov, S.; Rybicki, K.; Sankey, D. P. C.; Sauvan, E.; Schätzel, S.; Scheins, J.; Schilling, F.-P.; Schleper, P.; Schmidt, D.; Schmidt, S.; Schmitt, S.; Schneider, M.; Schoeffel, L.; Schöning, A.; Schröder, V.; Schultz-Coulon, H.-C.; Schwanenberger, C.; Sedlák, K.; Sefkow, F.; Sheviakov, I.; Shtarkov, L. N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, A.; Spitzer, H.; Stamen, R.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Thompson, G.; Thompson, P. D.; Tomasz, F.; Traynor, D.; Truöl, P.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Turney, J. E.; Tzamariudaki, E.; Uraev, A.; Urban, M.; Usik, A.; Valkár, S.; Valkárová, A.; Vallée, C.; Van Mechelen, P.; Vargas Trevino, A.; Vassiliev, S.; Vazdik, Y.; Veelken, C.; Vest, A.; Vichnevski, A.; Volchinski, V.; Wacker, K.; Wagner, J.; Wallny, R.; Waugh, B.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; Wessling, B.; Winde, M.; Winter, G.-G.; Wissing, Ch.; Woehrling, E.-E.; Wünsch, E.; Wyatt, A. C.; Žáček, J.; Zálešák, J.; Zhang, Z.; Zhokin, A.; Zomer, F.; zur Nedden, M.; H1 Collaboration

    2003-08-01

    The diffractive photoproduction of J/ψ mesons is measured with the H1 detector at the ep collider HERA using an integrated luminosity of 78 pb-1. The differential cross section dσ(γp→J/ψY)/dt is studied in the range 2<|t|<30 GeV2, where t is the square of the four-momentum transferred at the proton vertex. The cross section is also presented as a function of the photon-proton centre-of-mass energy Wγp in three t intervals, spanning the range 50

  2. Analysis of recent CLAS data on Σ*(1385) photoproduction off a neutron target

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Yun; He, Jun; Haberzettl, Helmut

    2016-04-01

    Based on recent experimental data obtained by the CLAS Collaboration, the Σ (1385 ) photoproduction off a neutron target at laboratory photon energies Eγ up to 2.5 GeV is investigated in an effective Lagrangian approach including s -, u -, and t -channel Born-term contributions. The present calculation does not take into account any explicit s -channel baryon-resonance contributions; however, in the spirit of duality, we include t -channel exchanges of mesonic Regge trajectories. The onset of the Regge regime is controlled by smoothly interpolating between Feynman-type single-meson exchanges and full-fledged Regge-trajectory exchanges. Gauge invariance broken by the Regge treatment is fully restored by introducing contact-type interaction currents that result from the implementation of local gauge invariance in terms of generalized Ward-Takahashi identities. The cross sections for the γ n →K+Σ*(1385) - reaction are calculated and compared with experimental results from the CLAS and LEPS collaborations. Despite its simplicity, the present theoretical approach provides a good description of the main features of the data. However, the parameters fitted to the data show that the gauge-invariance-restoring contact term plays a large role, which may point to large contributions from final-state interactions.

  3. Transverse polarization of {Lambda} and {bar {Lambda}} hyperons in quasireal photoproduction.

    SciTech Connect

    Airapetian, A.; Akopov, N.; Amarian, M.; Ammosov, V. V.; Andrus, A.; Elalaoui-Moulay, A.; Hafidi, K.; Jackson, H. E.; Potterveld, D. H.; Reimer, P. E.; Sanjiev, I.; Physics; Yerevan Physics Inst.; Inst. Nazionaled di Fisica Nucleare; Inst. High Energy Physics

    2007-11-01

    The HERMES experiment has measured the transverse polarization of Lambda and {ovr Lambda} hyperons produced inclusively in quasireal photoproduction at a positron beam energy of 27.6 GeV. The transverse polarization P{sub n}{sup Lambda} of the Lambda hyperon is found to be positive while the observed {ovr Lambda} polarization is compatible with zero. The values averaged over the kinematic acceptance of HERMES are P{sub n}{sup Lambda} =0.078 {+-} 0.006(stat) {+-} 0.012(syst) and P{sub n}{sup {ovr Lambda}} = -0.025 {+-} 0.015(stat) {+-} 0.018(syst) for Lambda and {ovr Lambda}, respectively. The dependences of P{sub n}{sup Lambda} and P{sub n}{sup {ovr Lambda}} on the fraction zeta of the beam's light-cone momentum carried by the hyperon and on the hyperon's transverse momentum p{sub T} were investigated. The measured Lambda polarization rises linearly with p{sub T} and exhibits a different behavior for low and high values of zeta, which approximately correspond to the backward and forward regions in the center-of-mass frame of the gamma*N reaction.

  4. Prompt photon photoproduction at HERA within the framework of the quark Reggeization hypothesis

    NASA Astrophysics Data System (ADS)

    Saleev, V. A.

    2008-12-01

    We study the inclusive production of isolated prompt photons within the framework of the quasi-multi-Regge-kinematic approach, applying the quark Reggeization hypothesis. We describe accurately and without free parameters the transverse momentum and pseudorapidity spectra of prompt photons in the inclusive photoproduction at the HERA Collider. It is shown that the main mechanism of the inclusive prompt photon production in the γp collisions is the fusion of a Reggeized quark (antiquark) from the proton and a collinear antiquark (quark) from the photon into a photon, via the effective Reggeon-quark-gamma vertex. The fragmentation of the quark, which is produced via the gamma-Reggeon-quark and quark-Reggeon-quark vertices, into a photon is strongly suppressed by the isolation cone condition and it gives a significant contribution in the region of a large negative pseudorapidity only. At the stage of numerical calculations we use the Kimber-Martin-Ryskin prescription for unintegrated quark and gluon distribution functions, with the following collinear parton densities as input: Martin-Roberts-Stirling-Thorne for a proton and Glück-Reya-Vogt for a photon.

  5. Photoproduction of the \\Theta^+ resonance on the nucleon in a Regge model

    SciTech Connect

    H. Kwee; M. Guidal; M. Polyakov; M. Vanderhaeghen

    2005-09-15

    We estimate the reaction mechanisms for the photoproduction of the {Theta}{sup +}(1540) resonance on the nucleon, through K and K* Regge exchanges. We compare the size of the cross sections for the {gamma}n {yields} K{sup -} {Theta}{sup +} and {gamma}p {yields} {bar K}{sup 0} {Theta}{sup +} reactions, and investigate their sensitivity to the spin-parity assignments J{sup P} = (1/2){sup {+-}}, (3/2){sup {+-}} for the {Theta}{sup +} resonance. The model allows to estimate the cross sections corresponding with a given upper bound on the width of the {Theta}{sup +}. Within this model, the cross sections on the neutron are found to be around a factor 5 larger than the ones on the proton, due to the presence of charged K exchange for the reaction on a neutron target. Furthermore, the photon asymmetry is found to display a pronounced sensitivity to the parity of the {Theta}{sup +}, making it a very promising observable to help determining the quantum numbers of the {Theta}{sup +} resonance.

  6. Photoproduction for N* and Related Topics at LEPS/LEPS2

    NASA Astrophysics Data System (ADS)

    Kohri, Hideki

    We have been carrying out photoproduction experiments by using polarized photon beams with energies of 1.5-3 GeV at the LEPS beamline of SPring-8 since 2000. The study of N* is one of the main physics subjects. Several bump structures suggesting N* and Δ* are observed in the γp → K+Λ, K+Σ0, K+Λ(1520), ηp, and ωp reactions. We newly took charged pion data with high momenta at forward pion angles in 2007. The γp → π+n, π+Δ0, and π-Δ++ reactions are observed clearly. Preliminary cross section ratios of dσ(π+Δ0)/dσ(π-Δ++) at the most forward pion angles are close to 1/3 which is expected from the Clebsch-Gordan coefficients with the isospin 1 exchange in the t-channel. The ratios become larger than 1/3 at larger pion angles at high energies. It is interesting that the dbar{d} production is found to be enhanced compared with the ubar{u} production. We are developing a polarized hydrogen-deuteride (HD) target and the LEPS2 solenoid spectrometer for complete measurements of all physics observables in the near future experiments.

  7. PHOTOPRODUCTION OF γp → pπ0 η AT ELSA IN BONN

    NASA Astrophysics Data System (ADS)

    Crede, V.

    2003-07-01

    The study of nucleon resonances provides important information on many open questions in baryon spectroscopy. The key to any progress is the identification of the effective degrees of freedom leading to a qualitative understanding of strong QCD. The problem of missing resonances predicted by quark models is discussed on the basis of experimental results of the CB-ELSA experiment at the e- accelerator ELSA in Bonn. Resonance production and even cascades of the type N**(∆**) → N*(∆*) → pπ0π0(pπ0η) are observed as well as ηη photoproduction off the proton. Indications for a ∆ resonance around 1900 MeV are seen. The latter is particularly interesting if it had negative parity because a confirmation of this state would be in contradiction with constituent quark models1,5. Both, the quark models using one-gluon exchange and the quark model using instantoninduced forces as short-range residual quark-quark interaction predict the three states ∆5/2- (1930), ∆3/2- (1940) and ∆1/2- (1900) at masses in the 2100 MeV region.

  8. Photochemistry. Chemiexcitation of melanin derivatives induces DNA photoproducts long after UV exposure.

    PubMed

    Premi, Sanjay; Wallisch, Silvia; Mano, Camila M; Weiner, Adam B; Bacchiocchi, Antonella; Wakamatsu, Kazumasa; Bechara, Etelvino J H; Halaban, Ruth; Douki, Thierry; Brash, Douglas E

    2015-02-20

    Mutations in sunlight-induced melanoma arise from cyclobutane pyrimidine dimers (CPDs), DNA photoproducts that are typically created picoseconds after an ultraviolet (UV) photon is absorbed at thymine or cytosine. We found that in melanocytes, CPDs are generated for >3 hours after exposure to UVA, a major component of the radiation in sunlight and in tanning beds. These "dark CPDs" constitute the majority of CPDs and include the cytosine-containing CPDs that initiate UV-signature C→T mutations. Dark CPDs arise when UV-induced reactive oxygen and nitrogen species combine to excite an electron in fragments of the pigment melanin. This creates a quantum triplet state that has the energy of a UV photon but induces CPDs by energy transfer to DNA in a radiation-independent manner. Melanin may thus be carcinogenic as well as protective against cancer. These findings also validate the long-standing suggestion that chemically generated excited electronic states are relevant to mammalian biology. PMID:25700512

  9. Chemiexcitation of Melanin Derivatives Induces DNA Photoproducts Long after UV Exposure

    PubMed Central

    Premi, Sanjay; Wallisch, Silvia; Mano, Camila M.; Weiner, Adam B.; Bacchiocchi, Antonella; Wakamatsu, Kazumasa; Bechara, Etelvino J. H.; Halaban, Ruth; Douki, Thierry; Brash, Douglas E.

    2015-01-01

    Mutations in sunlight-induced melanoma arise from cyclobutane pyrimidine dimers (CPD), DNA photoproducts that are typically created picoseconds after an ultraviolet (UV) photon is absorbed at thymine or cytosine. Here we show that in melanocytes, CPD are generated for >3 hours after exposure to UVA, a major component of the radiation in sunlight and in tanning beds. These “dark CPD” constitute the majority of CPD and include the cytosine-containing CPD that initiate UV-signature C→T mutations. Dark CPD arise when UV-induced reactive oxygen and nitrogen species combine to excite an electron in fragments of the pigment melanin. This creates a quantum triplet state that has the energy of a UV photon but that induces CPD by energy transfer to DNA in a radiation-independent manner. Melanin may thus be carcinogenic as well as protective against cancer. These findings also validate the long-standing suggestion that chemically-generated excited electronic states are relevant to mammalian biology. PMID:25700512

  10. Photoproduction of π0 mesons off neutrons in the nucleon resonance region.

    PubMed

    Dieterle, M; Keshelashvili, I; Ahrens, J; Annand, J R M; Arends, H J; Bantawa, K; Bartolome, P A; Beck, R; Bekrenev, V; Braghieri, A; Branford, D; Briscoe, W J; Brudvik, J; Cherepnya, S; Demissie, B; Downie, E J; Drexler, P; Fil'kov, L V; Fix, A; Glazier, D I; Hamilton, D; Heid, E; Hornidge, D; Howdle, D; Huber, G M; Jaegle, I; Jahn, O; Jude, T C; Käser, A; Kashevarov, V L; Kondratiev, R; Korolija, M; Kruglov, S P; Krusche, B; Kulbardis, A; Lisin, V; Livingston, K; MacGregor, I J D; Maghrbi, Y; Mancell, J; Manley, D M; Marinides, Z; Martinez, M; McGeorge, J C; McNicoll, E; Mekterovic, D; Metag, V; Micanovic, S; Middleton, D G; Mushkarenkov, A; Nefkens, B M K; Nikolaev, A; Novotny, R; Oberle, M; Ostrick, M; Oussena, B; Pedroni, P; Pheron, F; Polonski, A; Prakhov, S N; Robinson, J; Rosner, G; Rostomyan, T; Schumann, S; Sikora, M H; Sober, D; Starostin, A; Supek, I; Thiel, M; Thomas, A; Unverzagt, M; Watts, D P; Werthmüller, D; Witthauer, L

    2014-04-11

    Precise angular distributions have been measured for the first time for the photoproduction of π0 mesons off neutrons bound in the deuteron. The effects from nuclear Fermi motion have been eliminated by a complete kinematic reconstruction of the final state. The influence of final-state-interaction effects has been estimated by a comparison of the reaction cross section for quasifree protons bound in the deuteron to the results for free protons and then applied as a correction to the quasifree neutron data. The experiment was performed at the tagged photon facility of the Mainz Microtron MAMI with the Crystal Ball and TAPS detector setup for incident photon energies between 0.45 and 1.4 GeV. The results are compared to the predictions from reaction models and partial-wave analyses based on data from other isospin channels. The model predictions show large discrepancies among each other and the present data will provide much tighter constraints. This is demonstrated by the results of a new analysis in the framework of the Bonn-Gatchina coupled-channel analysis which included the present data. PMID:24765945

  11. Hyperon Photoproduction from Polarized H and D: towards a complete N* experiment

    SciTech Connect

    Sandorfi, Andrew M.; Hoblit, S.

    2013-09-01

    New complete experiments in pseudoscalar meson photo-production are being pursued at several laboratories. Here the designation of complete refers to measurements of most if not all of the possible reaction observables, of which there are 16 involving spins of the beam, target and recoil baryon. Hyperon production to Λ or Σ{sup +} final states affords attractive opportunities, since their weak decays provide an efficient self-analysis of their polarization. When the beam and target are also polarized, the resulting triple polarization measurements determine the full suite of observables with a single target orientation. This has been a focus at Jefferson Lab in the recently completed g9/FROST and g14/HDice experiments now under analysis. Multipole analyses of γp->K{sup +}Λ have been carried out with a large though incomplete set of recently published polarization data, and the uniqueness of the extracted amplitudes has been studied. Experiments with realistically achievable uncertainties require a significantly greater number of spin asymmetries than the in-principle minimum needed for a mathematical solution of the amplitude.

  12. Polarisation observables for strangeness photoproduction on a frozen spin target with CLAS at Jefferson Lab

    SciTech Connect

    Stuart Fegan

    2012-04-01

    The FROST experiment at Jefferson Lab used the CLAS detector in Hall B with the intention of performing a complete measurement of polarization observables associated with strangeness photoproduction, in combination with data from previous JLab experiments. This was achieved by utilizing the FROST polarized target in conjunction with polarized photon beams, allowing direct measurement of beam-target double polarization observables. By studying strangeness reactions, such as {gamma}p {yields} K{sup +}{Lambda}{sup 0}, it may be possible to find 'missing' baryon resonances, predicted by symmetric quark models but not observed in previous experiments, whose results are consistent with the di-quark model. It is thought these 'missing' resonances remain undiscovered because they have different coupling strengths for different reaction channels, such as the strangeness reactions, whereas the current data is dominated by studies of pN reactions. Observing these resonances therefore has important implications for our knowledge of the excited states of nucleons, and the models predicting the quark interactions within them. The G polarization observable is one of the beam-target double polarization observables, associated with a longitudinally polarized target and a linearly polarized photon beam, and its measurement for the strangeness reaction {gamma}p {yields} K{sup +}{Lambda}{sup 0} is the focus of the work presented.

  13. Extraction of Meson Resonances from Three-pions Photo-production Reactions

    SciTech Connect

    S. X. Nakamura, H. Kamano, T.-S. H. Lee, T. Sato

    2012-12-01

    We have investigated the model dependence of meson resonance properties extracted from the Dalitz-plot analysis of the three-pions photoproduction reactions on the nucleon. Within a unitary model developed in Phys. Rev. D 84, 114019 (2011), we generate Dalitz-plot distributions as data to perform an isobar model fit that is similar to most of the previous analyses of three-pion production reactions. It is found that the resonance positions from the two models agree well when both fit the data accurately, except for the resonance poles near branch points. The residues of the resonant amplitudes extracted from the two models and by the usual Breit-Wigner procedure agree well only for the isolated resonances with narrow widths. For overlapping resonances, most of the extracted residues could be drastically different. Our results suggest that even with high precision data, the resonance extraction should be based on models within which the amplitude parametrization is constrained by three-particle unitarity condition.

  14. Enhanced photoproduction of hydrogen peroxide by humic substances in the presence of phenol electron donors.

    PubMed

    Zhang, Yi; Simon, Kelli A; Andrew, Andrea A; Del Vecchio, Rossana; Blough, Neil V

    2014-11-01

    Addition of a series of phenol electron donors to solutions of humic substances (HS) enhanced substantially the initial rates of hydrogen peroxide (H2O2) photoproduction (RH2O2), with enhancement factors (EF) ranging from a low of ∼3 for 2,4,6-trimethylphenol (TMP) to a high of ∼15 for 3,4-dimethoxyphenol (DMOP). The substantial inhibition of the enhanced RH2O2 following borohydride reduction of the HS, as well as the dependence of RH2O2 on phenol and dioxygen concentrations are consistent with a mechanism in which the phenols react with the triplet excited states of (aromatic) ketones within the HS to form initially a phenoxy and ketyl radical. The ketyl radical then reacts rapidly with dioxygen to regenerate the ketone and form superoxide (O2-), which subsequently dismutates to H2O2. However, as was previously noted for the photosensitized loss of TMP, the incomplete inhibition of the enhanced RH2O2 following borohydride reduction suggests that there may remain another pool of oxidizing triplets. The results demonstrate that H2O2 can be generated through an additional pathway in the presence of sufficiently high concentrations of appropriate electron donors through reaction with the excited triplet states of aromatic ketones and possibly of other species such as quinones. However, in some cases, the much lower ratio of H2O2 produced to phenol consumed suggests that secondary reactions could alter this ratio significantly. PMID:25288017

  15. 2-pi Photoproduction from CLAS and CB-ELSA - The Search for Missing Resonances

    SciTech Connect

    Ulrike Thoma

    2003-10-01

    2-pi-photoproduction is one of the promising reactions to search for baryon resonances that have been predicted but have not yet been observed. The gamma-rho --> rho-pi{sup 0}-pi{sup 0}(CB-ELSA) and the gamma-rho --> rho-pi{sup +}-pi{sup -} (CLAS) data show interesting resonance structures. A partial wave analysis (PWA) has to be done to determine which baryon resonances contribute what their quantum numbers and their relative couplings to the different accessible rho-2-pi-channels and to the photon are. First preliminary PWA-results on the lowest energy rho-pi{sup 0}-pi{sup 0} data (sq rt s<1.8 GeV)look very promising. From an extension of this analysis to higher energies combining the rho-pi{sup 0}-pi{sup 0} and the rho-pi{sup +}-pi{sup -}-data, one can expect; interesting results on resonances decaying into Delta-pi, N-rho, N(pi-pi)s, N*-pi, and Delta*-pi.

  16. 40 CFR 180.437 - Methyl 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-p-toluate and methyl 6-(4-isopropyl-4...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...-imidazolin-2-yl)-p-toluate and methyl 6-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-m-toluate; tolerances... Tolerances § 180.437 Methyl 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-p-toluate and methyl 6-(4... for the combined residues of the herbicide methyl...

  17. Hydrogen film cooling with incident and swept-shock interactions in a Mach 6.4 nitrogen free stream

    NASA Technical Reports Server (NTRS)

    Olsen, George C.; Nowak, Robert J.

    1995-01-01

    The effectiveness of slot film cooling of a flat plate in a Mach 6.4 flow with and without incident and swept oblique shock interactions was experimentally investigated. Hydrogen was the primary coolant gas, although some tests were conducted using helium as the coolant. Tests were conducted in the Calspan 48-Inch Shock Tunnel with a nitrogen flow field to preclude combustion of the hydrogen coolant gas. A two-dimensional highly instrumented model developed in a previous test series was used. Parameters investigated included coolant mass flow rate, coolant gas, local free-stream Reynolds number, incident oblique shock strength, and a swept oblique shock. Both gases were highly effective coolants in undisturbed flow; however, both incident and swept shocks degraded that effectiveness.

  18. Hg196 and the ``magical quartet'' of the extended Uν(6/12)⊗Uπ(6/4) supersymmetry

    NASA Astrophysics Data System (ADS)

    Bernards, C.; Heinze, S.; Jolie, J.; Albers, M.; Fransen, C.; Radeck, D.

    2010-02-01

    We present the results of a γγ angular correlation experiment investigating the nucleus Hg196 and compare these with a theoretical description of Hg196 within the Uν(6/12)⊗Uπ(6/4) extended supersymmetry. To populate excited Hg196 states, we used the Cologne FN Tandem accelerator inducing the reaction Pt194(α,2n)Hg196 and analyzed the γ decays of levels up to an excitation energy of 2.4 MeV with the HORUS cube spectrometer. The new results on this mercury isotope allow a comparison between the experimental data and the supersymmetrical predictions and show good agreement. This way we can add Hg196 as a fifth supermultiplet member to the so-called magical quartet consisting of Pt194,195 and Au195,196.

  19. 30/20 GHz and 6/4 GHz band transponder development for communications satellite CS-3

    NASA Astrophysics Data System (ADS)

    Tanaka, Masayoshi; Nakamura, Makoto; Okamoto, Teruki; Kumazawa, Hiroyuki

    The next phase communications satellite CS-3 will be launched in 1988 as a successor to CS-2. The CS-3 is composed of two 6/4 GHz band and ten 30/20 GHz band transponders and its mission life is seven years. This paper describes the newly developed CS-3 transponder, especially a 4 GHz band 7 watt GaAs FET amplifier, Ka-band frequency single-conversion, a 30 GHz band low noise amplifier, and a 20 GHz band 10 watt TWTA. The introduction of these new technologies contributes significantly to reducing the CS-3 transponder weight and size, and to improving performance characteristics and insuring a long life.

  20. The SKW 6.4 line of human B lymphocytes specifically binds and responds to vasoactive intestinal peptide.

    PubMed

    Cheng, P P; Sreedharan, S P; Kishiyama, J L; Goetzl, E J

    1993-05-01

    Vasoactive intestinal peptide (VIP1-28) is a neuromediator recognized by high-affinity receptors on human lymphocytes, which inhibits T-cell proliferation and cytokine secretion, and suppresses immunoglobulin production by mitogen-stimulated mixed mononuclear leucocytes. The direct interactions of VIP1-28 with B cells were studied in the SKW 6.4 line of EBV-transformed human B cells, that express a mean (+/- SD) of 6116 +/- 969 receptors for [125I]VIP1-28 with a mean Kd of 59 nM, that decreases to 12 nM after exposure to phorbol 12-myristate 13-acetate (PMA). The secretion of IgM by SKW 6.4 B cells stimulated optimally with 100 ng/ml of PMA, but not unstimulated secretion of IgM, was suppressed significantly by 10(-12) M to 10(-9) M VIP1-28 and up to a mean maximum (+/- SD) of 40 +/- 2% by 10(-10) M VIP1-28. VIP1-28 elicited concomitant increases in intracellular cyclic AMP up to a mean maximum of 163% at 10(-10) M VIP1-28. The requirement for specific signal transduction by the occupied VIP receptors to inhibit IgM secretion was demonstrated by the lack of effect of VIP4-28 on both cyclic AMP concentration and IgM secretion, despite the equal affinity of binding of VIP4-28 and VIP1-28. The effects of VIP on immunoglobulin secretion by stimulated mixed mononuclear leucocytes thus may be due in part to a direct action on B cells. PMID:8509142

  1. The SKW 6.4 line of human B lymphocytes specifically binds and responds to vasoactive intestinal peptide.

    PubMed Central

    Cheng, P P; Sreedharan, S P; Kishiyama, J L; Goetzl, E J

    1993-01-01

    Vasoactive intestinal peptide (VIP1-28) is a neuromediator recognized by high-affinity receptors on human lymphocytes, which inhibits T-cell proliferation and cytokine secretion, and suppresses immunoglobulin production by mitogen-stimulated mixed mononuclear leucocytes. The direct interactions of VIP1-28 with B cells were studied in the SKW 6.4 line of EBV-transformed human B cells, that express a mean (+/- SD) of 6116 +/- 969 receptors for [125I]VIP1-28 with a mean Kd of 59 nM, that decreases to 12 nM after exposure to phorbol 12-myristate 13-acetate (PMA). The secretion of IgM by SKW 6.4 B cells stimulated optimally with 100 ng/ml of PMA, but not unstimulated secretion of IgM, was suppressed significantly by 10(-12) M to 10(-9) M VIP1-28 and up to a mean maximum (+/- SD) of 40 +/- 2% by 10(-10) M VIP1-28. VIP1-28 elicited concomitant increases in intracellular cyclic AMP up to a mean maximum of 163% at 10(-10) M VIP1-28. The requirement for specific signal transduction by the occupied VIP receptors to inhibit IgM secretion was demonstrated by the lack of effect of VIP4-28 on both cyclic AMP concentration and IgM secretion, despite the equal affinity of binding of VIP4-28 and VIP1-28. The effects of VIP on immunoglobulin secretion by stimulated mixed mononuclear leucocytes thus may be due in part to a direct action on B cells. PMID:8509142

  2. A Rare and Exclusive Endoperoxide Photoproduct Derived from a Thiacalix[4]arene Crown-Shaped Derivative Bearing a 9,10-Substituted Anthracene Moiety.

    PubMed

    Zhao, Jiang-Lin; Wu, Chong; Tomiyasu, Hirotsugu; Zeng, Xi; Elsegood, Mark R J; Redshaw, Carl; Yamato, Takehiko

    2016-05-20

    A rare and exclusive endoperoxide photoproduct was quantitatively obtained from a thiacalix[4]arene crown-shaped derivative upon irradiation at λ=365 nm; the structure was unambiguously confirmed by (1) H/(13) C NMR spectroscopy and X-ray crystallography. The prerequisites for the formation of the endoperoxide photoproduct have also been discussed. Furthermore, the photochemical reaction rate could be greatly enhanced in the presence of the thiacalix[4]arene platform because it served as a host to capture oxygen. PMID:26994971

  3. Light Vector Meson Photoproduction off of H at Jefferson Lab and rho-omega Interference in the Leptonic Decay Channel

    SciTech Connect

    Chaden Djalali

    2011-12-01

    Recent studies of light vector meson production in heavy nuclear targets has generated interest in {rho}-{omega} interference in the leptonic e{sup +}e{sup -} decay channel. An experimental study of the elementary process provides valuable input for theoretical models and calculations. In experiment E04-005 (g12), high statistics photoproduction data has been taken in Jefferson Lab's Hall B with the Cebaf Large Acceptance Spectrometer (CLAS). The invariant mass spectrum is fitted with two interfering relativistic Breit-Wigner functions to determine the interference phase. Preliminary analysis indicate a measurable {rho}-{omega} interference.

  4. Eta' photoproduction on the proton for photon energies from 1.527 to 2.227 GeV.

    PubMed

    Dugger, M; Ball, J P; Collins, P; Pasyuk, E; Ritchie, B G; Adams, G; Ambrozewicz, P; Anciant, E; Anghinolfi, M; Asavapibhop, B; Asryan, G; Audit, G; Avakian, H; Bagdasaryan, H; Baillie, N; Baltzell, N A; Barrow, S; Batourine, V; Battaglieri, M; Beard, K; Bedlinskiy, I; Bektasoglu, M; Bellis, M; Benmouna, N; Berman, B L; Bianchi, N; Biselli, A S; Bonner, B E; Bouchigny, S; Boiarinov, S; Bradford, R; Branford, D; Briscoe, W J; Brooks, W K; Bültmann, S; Burkert, V D; Butuceanu, C; Calarco, J R; Careccia, S L; Carman, D S; Carnahan, B; Chen, S; Cole, P L; Coleman, A; Coltharp, P; Cords, D; Corvisiero, P; Crabb, D; Crannell, H; Credé, V; Cummings, J P; De Sanctis, E; DeVita, R; Degtyarenko, P V; Denizli, H; Dennis, L; Deur, A; Dharmawardane, K V; Dhuga, K S; Djalali, C; Dodge, G E; Donnelly, J; Doughty, D; Dragovitsch, P; Dytman, S; Dzyubak, O P; Egiyan, H; Egiyan, K S; Elouadrhiri, L; Empl, A; Eugenio, P; Fatemi, R; Fedotov, G; Feldman, G; Feuerbach, R J; Forest, T A; Funsten, H; Garçon, M; Gavalian, G; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Gothe, R W; Griffioen, K A; Guidal, M; Guillo, M; Guler, N; Guo, L; Gyurjyan, V; Hadjidakis, C; Hakobyan, R S; Hardie, J; Heddle, D; Hersman, F W; Hicks, K; Hleiqawi, I; Holtrop, M; Hu, J; Huertas, M; Hyde-Wright, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Ito, M M; Jenkins, D; Jo, H S; Joo, K; Juengst, H G; Kellie, J D; Khandaker, M; Kim, K Y; Kim, K; Kim, W; Klein, A; Klein, F J; Klimenko, A V; Klusman, M; Kossov, M; Kramer, L H; Kubarovsky, V; Kuhn, J; Kuhn, S E; Lachniet, J; Laget, J M; Langheinrich, J; Lawrence, D; Lee, T; Lima, A C S; Livingston, K; Lukashin, K; Manak, J J; Marchand, C; Maximon, L C; McAleer, S; McKinnon, B; McNabb, J W C; Mecking, B A; Mestayer, M D; Meyer, C A; Mibe, T; Mikhailov, K; Minehart, R; Mirazita, M; Miskimen, R; Mokeev, V; Morrow, S A; Muccifora, V; Mueller, J; Mutchler, G S; Nadel-Turonski, P; Napolitano, J; Nasseripour, R; Niccolai, S; Niculescu, G; Niczyporuk, B B; Niyazov, R A; Nozar, M; O'Rielly, G V; Osipenko, M; Ostrovidov, A I; Park, K; Paterson, C; Philips, S A; Pierce, J; Pivnyuk, N; Pocanic, D; Pogorelko, O; Pozdniakov, S; Preedom, B M; Price, J W; Prok, Y; Protopopescu, D; Qin, L M; Raue, B A; Riccardi, G; Ricco, G; Ripani, M; Ronchetti, F; Rosner, G; Rossi, P; Rowntree, D; Rubin, P D; Sabatié, F; Salgado, C; Santoro, J P; Sapunenko, V; Schumacher, R A; Serov, V S; Shafi, A; Sharabian, Y G; Shaw, J; Simionatto, S; Skabelin, A V; Smith, E S; Smith, L C; Sober, D I; Spraker, M; Stavinsky, A; Stepanyan, S S; Stepanyan, S; Stokes, B E; Stoler, P; Strakovsky, I I; Strauch, S; Taiuti, M; Taylor, S; Tedeschi, D J; Thoma, U; Thompson, R; Tkabladze, A; Tkachenko, S; Tur, C; Ungaro, M; Vineyard, M F; Vlassov, A V; Wang, K; Weinstein, L B; Weller, H; Weygand, D P; Williams, M; Wolin, E; Wood, M H; Yegneswaran, A; Yun, J; Zana, L; Zhang, J

    2006-02-17

    Differential cross sections for the reaction gamma p --> eta' p have been measured with the CLAS spectrometer and a tagged photon beam with energies from 1.527 to 2.227 GeV. The results reported here possess much greater accuracy than previous measurements. Analyses of these data suggest for the first time the coupling of the eta'N channel to both the S11(1535) and P11(1710) resonances, known to couple strongly to the etaN channel in photoproduction on the proton, and the importance of J = 3/2 resonances in the process. PMID:16605984

  5. A fundamental approach to adhesion: Synthesis, surface analysis, thermodynamics and mechanics. [acid-base properties of titanium 6-4 surfaces

    NASA Technical Reports Server (NTRS)

    Siriwardane, R.; Wightman, J. P.

    1980-01-01

    The acid-base properties of titanium 6-4 plates (low surface area) were investigated after three different pretreatments, namely Turco, phosphate-fluoride and Pasa-Jell. A series of indicators was used and color changes were detected using diffuse reflectance visible spectroscopy. Electron spectroscopy for chemical analysis was used to examine the indicator on the Ti 6-4 surface. Specular reflectance infra-red spectroscopy was used to study the adsorption of stearic acid from cyclohexane solutions on the Ti 6-4 surface.

  6. Near-threshold incoherent ϕ photoproduction on the deuteron: Searching for traces of a resonance

    NASA Astrophysics Data System (ADS)

    Kiswandhi, Alvin; Yang, Shin Nan; Dong, Yu Bing

    2016-07-01

    We study the near-threshold incoherent ϕ photoproduction on the deuteron based on a model of γ N →ϕ N , consisting of Pomeron, (π ,η ) exchanges, and a JP=3 /2- resonance, which describes the low-energy γ p →ϕ p LEPS data well, including the peak in the forward differential cross section. The calculation is done up to double rescatterings, with the spin dependence of the elementary γ N →ϕ N amplitude retained throughout the calculation. The Fermi motion and final-state interactions (FSIs) are all properly treated as prescribed by realistic nucleon-nucleon interaction. The couplings of the resonance to γ n and ϕ n channels are estimated with the help of a constituent quark model. The main features of the LEPS and CLAS data are described reasonably well except for some quantitative discrepancies at very low energies and low-momentum-transfer regions. It is found that contributions of Fermi motion, p n FSI, and resonance are all indispensable in bridging the differences between the single-scattering results and the data. The off-shell rescattering is found to be important because it cancels out a large portion of the on-shell contribution. The discrepancies at low-momentum-transfer regions might be related to the binning size of the data. No peak is found to be associated with the weak resonance because it gets smeared out by the Fermi motion and FSI with the deuterium target. The problem at very-low-energy regions hints at the possible contributions from other mechanisms and should be investigated in depth with the use of recent high-statistics γ p →ϕ p data from CLAS.

  7. Charm decays and high energy photoproduction. Final report, April 1994--May 1997

    SciTech Connect

    Lopez, A.M.

    1997-12-31

    This project involved continued participation by the Physics Department at the Mayaguez Campus of the University of Puerto Rico (UPR) in high energy physics experiments carried out at Fermilab. The UPR is a member of the E831 collaboration which includes Fermilab and leading US, Italian, Brazilian and Korean universities. E831 is an upgrade to the E687 spectrometer with the goal of a tenfold increase in the statistics for the study of the photoproduction and decay of charmed particles. This spectrometer has been significantly upgraded to maintain and expand its capabilities even at considerably higher beam intensities. E687 completed its last data run in January 1992. Approximately 100,000 charm events were fully reconstructed from this data and results of the analysis have appeared in several publications. The UPR has been participating in E687 since 1985 when the experiment was in its early stages of construction. A grant from the DOE Division of High Energy Physics (starting in April 1994) and another from the DOE EPSCoR Program (starting in October 1994) allowed a considerable increase in the activities of the UPR group. Given the group`s capable performance, the responsibilities assigned to it by the collaboration have increased to the point where they now include four major detectors in E831. All four detectors were ready on time for the start of the E831 run in July 1996. This is a remarkable performance if one considers that there is only one senior member in the group and that the students are all MS or undergraduate students. The group has also been active in the development of simulation, data acquisition and analysis software.

  8. Sensitizing effect of Z,Z-bilirubin IXα and its photoproducts on enzymes in model solutions

    NASA Astrophysics Data System (ADS)

    Plavskii, V. Yu.; Mostovnikov, V. A.; Tret'yakova, A. I.; Mostovnikova, G. R.

    2008-05-01

    In model systems, we have studied side effects which may be induced by light during phototherapy of hyperbilirubinemia (jaundice) in newborn infants, with the aim of reducing the Z,Z-bilirubin IXα (Z,Z-BR IXα) level. We have shown that the sensitizing effect of Z,Z-BR IXα, localized at strong binding sites of the human serum albumin (HSA) macromolecule, is primarily directed at the amino acid residues of the carrier protein and does not involve the molecules of the enzyme (lactate dehydrogenase (LDH)) present in the buffer solution. The detected photodynamic damage to LDH is due to sensitization by bilirubin photoisomers, characterized by lower HSA association constants and located (in contrast to native Z,Z-BR IXα) on the surface of the HSA protein globule. Based on study of the spectral characteristics of the photoproducts of Z,Z-BR IXα and comparison of their accumulation kinetics in solution and the enzyme photo-inactivation kinetics, we concluded that the determining role in sensitized damage to LDH is played by lumirubin. The photosensitization effect depends on the wavelength of the radiation used for photoconversion of bilirubin. When (at the beginning of exposure) we make sure that identical numbers of photons are absorbed by the pigment in the different spectral ranges, the side effect is minimal for radiation corresponding to the long-wavelength edge of the bilirubin absorption band. We have shown that for a bilirubin/HSA concentration ratio >2 (when some of the pigment molecules are sorbed on the surface of the protein globule), the bilirubin can act as a photosensitizing agent for the enzyme present in solution. We discuss methods for reducing unfavorable side effects of light on the body of newborn infants during phototherapy of hyperbilirubinemia.

  9. Post-seismic deformation of the Mw 6.4 Shonbeh earthquake (south western Iran) of April 9th, 2013

    NASA Astrophysics Data System (ADS)

    Fathian Baneh, Aram; Tolomei, Cristiano; Lugari, Alessandro; Trasatti, Elisa; Salvi, Stefano

    2016-04-01

    The study of post-seismic deformation within a region is of high significance to have a better understanding of the kinematic behavior of a seismogenic fault. We perform the Small Baseline Subset (SBAS) method to process a large number of X-Band, COSMO-SkyMed images to measure the post-seismic deformation due to the Shonbeh earthquake (Iran) of 9th April 2013 (Mw 6.4). The meizoseismal zone of the earthquake and following aftershocks' epicenters cover an area in the frontal edge of the Zagros Simply Folded Zone, in the southwest of Iran, between Kaki and Kangan anticlines. Exploiting the available dataset of images from the beginning of 2013 to mid 2014, we observe the concentration of the deformation along at least two NW- striking, southwest-dipping fault segments arranged in right-step pattern and parallel to the trend of the folds. The preliminary InSAR results illustrate the migration of the post-seismic deformation and stress relaxation from the southeastern toward the northwestern fault segments.

  10. Structural Basis of Enzymatic Activity for the Ferulic Acid Decarboxylase (FADase) from Enterobacter sp. Px6-4

    PubMed Central

    Liang, Lianming; Sun, Yuna; Huang, Jingwen; Li, Xuemei; Cao, Yi; Meng, Zhaohui; Zhang, Ke-Qin

    2011-01-01

    Microbial ferulic acid decarboxylase (FADase) catalyzes the transformation of ferulic acid to 4-hydroxy-3-methoxystyrene (4-vinylguaiacol) via non-oxidative decarboxylation. Here we report the crystal structures of the Enterobacter sp. Px6-4 FADase and the enzyme in complex with substrate analogues. Our analyses revealed that FADase possessed a half-opened bottom β-barrel with the catalytic pocket located between the middle of the core β-barrel and the helical bottom. Its structure shared a high degree of similarity with members of the phenolic acid decarboxylase (PAD) superfamily. Structural analysis revealed that FADase catalyzed reactions by an “open-closed” mechanism involving a pocket of 8×8×15 Å dimension on the surface of the enzyme. The active pocket could directly contact the solvent and allow the substrate to enter when induced by substrate analogues. Site-directed mutagenesis showed that the E134A mutation decreased the enzyme activity by more than 60%, and Y21A and Y27A mutations abolished the enzyme activity completely. The combined structural and mutagenesis results suggest that during decarboxylation of ferulic acid by FADase, Trp25 and Tyr27 are required for the entering and proper orientation of the substrate while Glu134 and Asn23 participate in proton transfer. PMID:21283705

  11. The 29 July 2014 (Mw 6.4) Southern Veracruz, Mexico Earthquake: Scenary Previous to Its Occurrence.

    NASA Astrophysics Data System (ADS)

    Yamamoto, J.

    2014-12-01

    On 29 July 2014 (10:46 UTC) a magnitude 6.4 (Mw) earthquake occurred at the southern Veracruz, Mexico region. The epicenter was preliminary located at 17.70° N and 95.63° W. It was a normal fault event with the slip on a fault that trend NNW and a focus approximately 117 km below the surface of the Gulf of Mexico costal plane. The earthquake was widely felt through centro and southern Mexico. In Oaxaca City 133 km to the south a person die of a hearth attack. No damages were reported. Most prominent moderate-sized earthquakes occurring in the southern Veracruz region since 1959 has been concentrated along two well defined seismic belts. One belt runs off the coast following nearly its contour. Here the earthquakes are shallow depth and mostly show a reverse fault mechanism. This belt of seismicity begins at the Los Tuxtlas volcanic field. Another seismic belt is located inland 70 km to the west. Here most earthquakes are of intermediate-depth (108-154 km) focus and normal faulting mechanism. The July 2014 earthquake is located near to this second seismic belt. In the present paper we discuss, within the regional geotectonic framework, the location and some aspects of the rupture process of the July 2014 earthquake.

  12. Detection of Anomalous Machining Damages in Inconel 718 and TI 6-4 by Eddy Current Techniques

    NASA Astrophysics Data System (ADS)

    Lo, C. C. H.; Shimon, M.; Nakagawa, N.

    2010-02-01

    This paper reports on an eddy current (EC) study aimed at detecting anomalous machining damages in Inconel 718 and Ti 6-4 samples, including (i) surface discontinuities such as re-depositing of chips onto the machined surface, and (ii) microstructural damages manifested as a white surface layer and a subsurface layer of distorted grains, typically tens of microns thick. A series of pristine and machine-damaged coupons were studied by EC scans using a differential probe operated at 2 MHz to detect discontinuous surface anomalies, and by swept high frequency EC (SHFEC) measurements from 0.5 MHz to 65.5 MHz using proprietary detection coils to detect surface microstructural damages. In general, the EC c-scan data from machine-damaged surfaces show spatial variations with larger standard deviations than those from the undamaged surfaces. In some cases, the c-scan images exhibit characteristic bipolar indications in good spatial correlation with surface anomalies revealed by optical microscopy and laser profilometry. Results of the SHFEC measurements indicate a reduced near-surface conductivity of the damaged surfaces compared to the undamaged surfaces.

  13. Final report on SIM.T-K6.4: Comparison of INMETRO and INTI humidity standards

    NASA Astrophysics Data System (ADS)

    Brionizio, J. D.; Skabar, J. G.

    2013-01-01

    The aim of this paper is to describe a bilateral comparison carried out by the hygrometry laboratories of the National Metrological Institutes of Brazil and Argentina, INMETRO and INTI, respectively. This comparison was planned and carried out as an informal comparison. But, in view of the lack of and the need for humidity comparison reports in the region of the Inter American Metrology System (SIM), we decided to register this comparison as a bilateral key comparison of the regional metrology organization (RMO), SIM.T-K6.4-INMETRO/INTI. The comparison was performed in the range from -20 ºC to +60 ºC dew/frost point temperatures in 20 °C steps. This paper presents the calibration methods of the laboratories, the uncertainty analysis and the comparison results. The measurements results of the comparison are also presented in terms of the normalised error (En) as a function of the dew/frost point temperature. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  14. Auxiliary KCNE subunits modulate both homotetrameric Kv2.1 and heterotetrameric Kv2.1/Kv6.4 channels

    PubMed Central

    David, Jens-Peter; Stas, Jeroen I.; Schmitt, Nicole; Bocksteins, Elke

    2015-01-01

    The diversity of the voltage-gated K+ (Kv) channel subfamily Kv2 is increased by interactions with auxiliary β-subunits and by assembly with members of the modulatory so-called silent Kv subfamilies (Kv5-Kv6 and Kv8-Kv9). However, it has not yet been investigated whether these two types of modulating subunits can associate within and modify a single channel complex simultaneously. Here, we demonstrate that the transmembrane β-subunit KCNE5 modifies the Kv2.1/Kv6.4 current extensively, whereas KCNE2 and KCNE4 only exert minor effects. Co-expression of KCNE5 with Kv2.1 and Kv6.4 did not alter the Kv2.1/Kv6.4 current density but modulated the biophysical properties significantly; KCNE5 accelerated the activation, slowed the deactivation and steepened the slope of the voltage-dependence of the Kv2.1/Kv6.4 inactivation by accelerating recovery of the closed-state inactivation. In contrast, KCNE5 reduced the current density ~2-fold without affecting the biophysical properties of Kv2.1 homotetramers. Co-localization of Kv2.1, Kv6.4 and KCNE5 was demonstrated with immunocytochemistry and formation of Kv2.1/Kv6.4/KCNE5 and Kv2.1/KCNE5 complexes was confirmed by Fluorescence Resonance Energy Transfer experiments performed in HEK293 cells. These results suggest that a triple complex consisting of Kv2.1, Kv6.4 and KCNE5 subunits can be formed. In vivo, formation of such tripartite Kv2.1/Kv6.4/KCNE5 channel complexes might contribute to tissue-specific fine-tuning of excitability. PMID:26242757

  15. Spin density matrix elements for radiative decays of the omega meson in photoproduction at 5 GeV

    NASA Astrophysics Data System (ADS)

    Mokaya, Fridah

    2016-03-01

    The photoproduction of ω(782) meson on the nucleon at high energies is well described by a sum of t-channel exchanges. In the high energy limit of diffractive scattering, where Pomeron exchange dominates the total cross section, the helicity of the incident photon is transferred directly to the vector meson. At intermediate energies, other Regge exchanges compete with the Pomeron, leading to a complex energy dependence in the spin density matrix for vector mesons like the omega. High statistics measurements of the spin density matrix elements for the reaction γp ωp, ω π0 γ are presented based on data taken with the Radphi experiment at Jefferson Lab in the energy range 4.4 - 5.5 GeV. The results binned in Eγ and |t | are analysed in both the Gottfried Jackson and s-channel helicity frames and compared to a model with the Pomeron and other Regge exchanges contributing to the omega meson photoproduction amplitude.

  16. Chemical Synthesis, Crystal Structure and Enzymatic Evaluation of a Dinucleotide Spore Photoproduct Analogue Containing a Formacetal Linker

    PubMed Central

    Lin, Gengjie; Chen, Chun-Hsing; Pink, Maren; Pu, Jingzhi; Li, Lei

    2011-01-01

    Spore photoproduct (SP) is the exclusive DNA photodamage product found in bacterial endospores. Its photoformation and repair by a metal-loenzyme spore photoproduct lyase (SPL) composes the unique SP biochemistry. Despite the fact that the SP was discovered almost 50 years ago, its crystal structure is still unknown and the lack of structural information greatly hinders the study of SP biochemistry. Employing a formacetal linker and organic synthesis, we successfully prepared a dinucleotide SP isostere 5R-CH2SP, which contains a neutral CH2 moiety between the two thymine residues instead of a phosphate. The neutral linker dramatically facilitates the crystallization process, allowing us to obtain the crystal structure for this intriguing thymine dimer half a century after its discovery. Further ROESY spectroscopic, DFT computational, and enzymatic studies of this 5R-CH2SP compound prove that it possesses similar properties with the 5R-SP species, suggesting that the revealed structure truly reflects that of SP generated in Nature. PMID:21780208

  17. Probing the gluon density of the proton in the exclusive photoproduction of vector mesons at the LHC: a phenomenological analysis

    NASA Astrophysics Data System (ADS)

    Gonçalves, V. P.; Martins, L. A. S.; Sauter, W. K.

    2016-02-01

    The current uncertainty on the gluon density extracted from the global parton analysis is large in the kinematical range of small values of the Bjorken- x variable and low values of the hard scale Q^2. An alternative to reduces this uncertainty is the analysis of the exclusive vector meson photoproduction in photon-hadron and hadron-hadron collisions. This process offers a unique opportunity to constrain the gluon density of the proton, since its cross section is proportional to the gluon density squared. In this paper we consider current parametrisations for the gluon distribution and estimate the exclusive vector meson photoproduction cross section at HERA and LHC using the leading logarithmic formalism. We perform a fit of the normalisation of the γ h cross section and the value of the hard scale for the process and demonstrate that the current LHCb experimental data are better described by models that assume a slow increasing of the gluon distribution at small x and low Q^2.

  18. Control of Hydrogen Photoproduction by the Proton Gradient Generated by Cyclic Electron Flow in Chlamydomonas reinhardtii[W

    PubMed Central

    Tolleter, Dimitri; Ghysels, Bart; Alric, Jean; Petroutsos, Dimitris; Tolstygina, Irina; Krawietz, Danuta; Happe, Thomas; Auroy, Pascaline; Adriano, Jean-Marc; Beyly, Audrey; Cuiné, Stéphan; Plet, Julie; Reiter, Ilja M.; Genty, Bernard; Cournac, Laurent; Hippler, Michael; Peltier, Gilles

    2011-01-01

    Hydrogen photoproduction by eukaryotic microalgae results from a connection between the photosynthetic electron transport chain and a plastidial hydrogenase. Algal H2 production is a transitory phenomenon under most natural conditions, often viewed as a safety valve protecting the photosynthetic electron transport chain from overreduction. From the colony screening of an insertion mutant library of the unicellular green alga Chlamydomonas reinhardtii based on the analysis of dark-light chlorophyll fluorescence transients, we isolated a mutant impaired in cyclic electron flow around photosystem I (CEF) due to a defect in the Proton Gradient Regulation Like1 (PGRL1) protein. Under aerobiosis, nonphotochemical quenching of fluorescence (NPQ) is strongly decreased in pgrl1. Under anaerobiosis, H2 photoproduction is strongly enhanced in the pgrl1 mutant, both during short-term and long-term measurements (in conditions of sulfur deprivation). Based on the light dependence of NPQ and hydrogen production, as well as on the enhanced hydrogen production observed in the wild-type strain in the presence of the uncoupling agent carbonyl cyanide p-trifluoromethoxyphenylhydrazone, we conclude that the proton gradient generated by CEF provokes a strong inhibition of electron supply to the hydrogenase in the wild-type strain, which is released in the pgrl1 mutant. Regulation of the trans-thylakoidal proton gradient by monitoring pgrl1 expression opens new perspectives toward reprogramming the cellular metabolism of microalgae for enhanced H2 production. PMID:21764992

  19. Autotrophic hydrogen photoproduction by operation of carbon-concentrating mechanism in Chlamydomonas reinhardtii under sulfur deprivation condition.

    PubMed

    Hong, Min Eui; Shin, Ye Sol; Kim, Byung Woo; Sim, Sang Jun

    2016-03-10

    Under autotrophic conditions, starch plays an important role in establishing anoxic conditions during PSII-dependent hydrogen (H2) photoproduction in microalgae. This is because starch is the sole organic substrate during respiratory consumption of internal oxygen (O2) from PSII-dependent direct pathway. Herein, we propose a novel approach to further facilitate the internal starch synthesis of Chlamydomonas reinhardtii through the operation of carbon-concentrating mechanism (CCM) along with a two-stage process based on sulfur (S) deprivation, thereby resulting in enhanced anaerobic capacity during PSII-dependent H2 photoproduction. When CCM-induced cells were exposed to high levels of carbon dioxide (CO2) (5%, v/v) with S deprivation, internal levels of starch were significantly elevated by retaining a functional CCM with the boosted photosynthetic activity during 24h of O2 evolution phase (I) of S deprivation. Consequently, during H2 production phase of S deprivation at irradiance of 50μEm(-2)s(-1), the concentrations of starch and H2 in CCM-induced cells were remarkably enhanced by 65.0% and 218.9% compared to that of CCM-uninduced cells, respectively. The treatment of low-CO2-driven CCM induction prior to S deprivation is a cost-effective and energy-efficient strategy that significantly improves the solar-driven H2 production by microalgae; this is particularly realizable in an industrial scale. PMID:26812657

  20. The effect of sulfur re-addition on H(2) photoproduction by sulfur-deprived green algae.

    PubMed

    Kosourov, Sergey; Makarova, Valeriya; Fedorov, Alexander S; Tsygankov, Anatoly; Seibert, Michael; Ghirardi, Maria L

    2005-09-01

    Sulfur deprivation of algal cultures selectively and partially inactivates photosystem II (PSII)-catalyzed O(2) evolution, induces anaerobiosis and hydrogenase expression, and results in sustained H(2) photoproduction for several days. We show that re-addition of limiting amounts of sulfate (1-10 microM final concentration) to the cultures during the H(2)-production phase temporarily reactivates PSII photochemical and O(2)-evolution activity and re-establishes higher rates of electron transport through the photosynthetic electron transport chain. The reactivation of PSII occurs by de novo D1 protein synthesis, but does not result in the re-establishment of aerobic conditions in the reactor, detectable by dissolved-O(2) sensors. However, concomitant H(2) photoproduction is inhibited, possibly due to excessive intra-cellular levels of photosynthetically-evolved O(2). The partial recovery of electron transport rates correlates with the re-oxidation of the plastoquinone (PQ) pool, as observed by pulse-amplitude modulated (PAM) and fluorescence-induction measurements. These results show that the presence of a more oxidized PQ pool releases some of the down-regulation of electron transport caused by the anaerobic conditions. PMID:16170632

  1. Distinct photoproducts of hydroxylated polybromodiphenyl ethers from different photodegradation pathways: a case study of 2'-HO-BDE-68.

    PubMed

    Xie, Qing; Chen, Jingwen; Zhao, Hongxia; Wang, Xingbao; Xie, Hong-Bin

    2015-02-01

    Hydroxylated polyhalodiphenyl ethers (HO-PXDEs) are emerging aquatic pollutants. Previous studies have shown that HO-PXDEs can photogenerate dioxins and phenolic compounds. However, it is unclear which photochemical pathways are responsible for the various photoproducts. This study investigates the direct photolysis and photooxidation initiated by (1)O2 and ˙OH that can be formed by photosensitization, taking 2'-HO-2,3',4,5'-tetrabromodiphenyl ether (2'-HO-BDE-68) as a case study. The results show that 1,3,8-tribromodibenzo-p-dioxin can only be produced during direct photolysis. By mass spectrum analysis, four dihydroxylated polybromodiphenyl ethers, generated from both direct and indirect photodegradation were confirmed. Among them, di-HO-tribromodiphenyl ether (di-HO-TBDE) was the main product generated from direct photohydrolysis. Most probably, the di-HO-TBDE is 2',5'-HO-2,3',4-tribromodiphenyl ether, as was suggested by density functional theory calculations. Ether bond cleavage is a dominant pathway for the direct photolysis and photooxidation reactions leading to 2,4-dibromophenol as the dominant product. The yields of the products, which are irrespective of reaction time and can be employed to compare the ability of different HO-PXDEs to photogenerate a given product, were reported. This study indicates that for accurate ecological risk assessment of HO-PXDEs, their different photodegradation pathways that may lead to different photoproducts should be considered. PMID:25569145

  2. Hydrogen peroxide photoproduction by immobilized cells of the blue-green alga Anabaena variabilis: A way to solar energy conversion

    SciTech Connect

    Morales, I.; La Rosa, F.F. de )

    1992-07-01

    A photosystem for hydrogen peroxide photoproduction formed by immobilized cells of the blue-green alga, Anabaena variabilis and the redox mediator methyl viologen is described. Hydrogen peroxide is produced in a redox catalyst cycle in which methyl viologen is reduced by electrons from water obtained by the photosynthetic apparatus of the algae using solar energy, and reoxidized by the introduction of oxygen into the solution. Hydrogen peroxide is produced during methyl viologen re-oxidation in two steps by means of the formation of superoxide. Experimental conditions for maximum photoproduction (catalyst charge, chlorophyll, and agar final concentration for cell immobilization) have been investigated using a continuous photosystem with immobilized A. variabilis as photocatalyst. Under the determined optimum conditions, the photosystem with immobilized A. variabilis is photocatalyst. Under the determined optimum conditions, the photosystem produces hydrogen peroxide at a rate of 100 {mu}moles/mg Chl{center dot}h, maintaining the production for several hours, and with an energy conversion efficiency of about 2%. Taking into account the use of hydrogen peroxide as fuel, this photosystem can be a useful tool in the storage of solar energy.

  3. Photodegradation of sulcotrione in various aquatic environments and toxicity of its photoproducts for some marine micro-organisms.

    PubMed

    Chaabane, Hanène; Vulliet, Emmanuelle; Joux, Fabien; Lantoine, François; Conan, Pascal; Cooper, Jean-François; Coste, Camille-Michel

    2007-04-01

    Photochemical behaviour of sulcotrione, a triketone herbicide, was studied in a variety of aqueous solutions including natural waters (sea and river) under laboratory conditions. Photodegradation experiments were carried out under two irradiation systems (UV-B and simulated solar radiation) in order to evaluate kinetics of active ingredient. The degradation kinetics, more rapid under UV-B radiation than solar simulator, followed a first-order reaction (photolysis half-lives ranged between 3 and 50 h) and appeared strongly dependent on water origin, pH value and molecular structure of the herbicide. Dissolved organic matter showed a retarding effect while low concentrations of nitrate ions had no effect on photolysis rate. Identification of photoproducts indicated that hydrolysis, a pH-dependent process (no degradation at pH >6 but at pH=3, k=0.0344 h(-1)), could be photoassisted. These results were compared to those of mesotrione, another triketone herbicide, which appeared more stable under UV-B irradiation. Toxicological studies on two marine heterotrophic bacteria and one cyanobacterium showed absence of effects up to 100 microgL(-1) for both sulcotrione and its photoproducts. PMID:17303209

  4. [Fe(CN)6]4- decorated mesoporous gelatin thin films for colorimetric detection and as sorbents of heavy metal ions.

    PubMed

    Shi, Li; Huang, Hubiao; Sun, Luwei; Lu, Yanping; Du, Binyang; Mao, Yiyin; Li, Junwei; Ye, Zhizhen; Peng, Xinsheng

    2013-09-28

    [Fe(CN)6](4-) decorated mesoporous gelatin films, acting as colorimetric sensors and sorbents for heavy metal ions, were prepared by incorporating [Fe(CN)6](4-) ions into the mesoporous gelatin films through electrostatic interaction. Gelatin-Prussian blue (PB) and gelatin-PB analogue composite films were successfully synthesized by immersing the [Fe(CN)6](4-) decorated gelatin films into aqueous solutions of metal ions, such as Fe(3+), Cu(2+), Co(2+), Pb(2+) and Cd(2+) (all as nitrates). The in situ formation process of PB or its analogues in the films was investigated using quartz crystal microbalance (QCM) measurements. According to the different colors of the PB nanoparticles and its analogues, the [Fe(CN)6](4-) decorated mesoporous gelatin films demonstrated colorimetric sensor abilities for detecting the corresponding metal ions by the naked eye with sufficient sensitivity at 1 ppm level and a quite short response time of 5 minutes. Moreover, due to the [Fe(CN)6](4-) functionality and other functional groups of gelatin itself, this [Fe(CN)6](4-) decorated mesoporous gelatin film shows a tens times higher adsorption ability for heavy metal ions in water than that of activated carbon. Due to both the efficient detection and high adsorption ability for heavy metal ions, this film has wide potential applications for the detection and purification of heavy metal ions from polluted water. PMID:23887280

  5. The DDX6-4E-T interaction mediates translational repression and P-body assembly.

    PubMed

    Kamenska, Anastasiia; Simpson, Clare; Vindry, Caroline; Broomhead, Helen; Bénard, Marianne; Ernoult-Lange, Michèle; Lee, Benjamin P; Harries, Lorna W; Weil, Dominique; Standart, Nancy

    2016-07-27

    4E-Transporter binds eIF4E via its consensus sequence YXXXXLΦ, shared with eIF4G, and is a nucleocytoplasmic shuttling protein found enriched in P-(rocessing) bodies. 4E-T inhibits general protein synthesis by reducing available eIF4E levels. Recently, we showed that 4E-T bound to mRNA however represses its translation in an eIF4E-independent manner, and contributes to silencing of mRNAs targeted by miRNAs. Here, we address further the mechanism of translational repression by 4E-T by first identifying and delineating the interacting sites of its major partners by mass spectrometry and western blotting, including DDX6, UNR, unrip, PAT1B, LSM14A and CNOT4. Furthermore, we document novel binding between 4E-T partners including UNR-CNOT4 and unrip-LSM14A, altogether suggesting 4E-T nucleates a complex network of RNA-binding protein interactions. In functional assays, we demonstrate that joint deletion of two short conserved motifs that bind UNR and DDX6 relieves repression of 4E-T-bound mRNA, in part reliant on the 4E-T-DDX6-CNOT1 axis. We also show that the DDX6-4E-T interaction mediates miRNA-dependent translational repression and de novo P-body assembly, implying that translational repression and formation of new P-bodies are coupled processes. Altogether these findings considerably extend our understanding of the role of 4E-T in gene regulation, important in development and neurogenesis. PMID:27342281

  6. Heterogeneous stress field in the source area of the 2003 M6.4 Northern Miyagi Prefecture, NE Japan, earthquake

    NASA Astrophysics Data System (ADS)

    Yoshida, Keisuke; Hasegawa, Akira; Okada, Tomomi

    2016-07-01

    We investigated a detailed spatial distribution of principal stress axis orientations in the source area of the 2003 M6.4 Northern Miyagi Prefecture earthquake that occurred in the forearc of northeastern Japan. Aftershock hypocentres were precisely relocated by applying the double difference method to arrival time data obtained at temporary stations as well as at surrounding routine stations. We picked many P-wave polarity data from seismograms at these stations, which enabled us to obtain 312 well-determined focal mechanism solutions. Stress tensor inversions were performed by using these focal mechanism data. The results show that quite a lot of focal mechanisms are difficult to explain by the uniform stress field, especially near the large slip area of the main-shock rupture. Stress tensor inversions at the location of individual earthquakes show that σ1 axes are orientated mainly to WSW-ENE in the northern part of the source area, while they are oriented to NW-SE in the southern part. This spatial pattern is roughly similar to those of the static stress change by the main shock, which suggests that the observed spatially heterogeneous stress field was formed by the static stress change. If this is the case, the deviatoric stress magnitude before the main shock was very small. Another possibility is the heterogeneous stress field observed after the main shock had existed even before the main shock, although we do not know why it was formed. Unfavourable orientation of the main shock fault with respect to this stress field suggests that the fault is not strong in this case too.

  7. p{sup 0} photoproduction in ultraperipheral relativistic heavy ion collisions at {radical}{ovr s}{sub NN} = 200 GeV.

    SciTech Connect

    Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Anderson, B. D.; Arkhipkin, D.; Krueger, K.; Spinka, H. M.; Underwood, D. G.; STAR Collaboration; High Energy Physics; Univ. of Illinois; Panjab Univ.; Variable Energy Cyclotron Centre; Kent State Univ.; Particle Physic Lab.

    2008-01-01

    Photoproduction reactions occur when the electromagnetic field of a relativistic heavy ion interacts with another heavy ion. The STAR Collaboration presents a measurement of {rho}{sup 0} and direct {pi}{sup +}{pi}{sup -} photoproduction in ultraperipheral relativistic heavy ion collisions at {radical}s{sub NN} = 200 GeV. We observe both exclusive photoproduction and photoproduction accompanied by mutual Coulomb excitation. We find a coherent cross section of {sigma} (AuAu {yields} Au{sup +}Au{sup +} {rho}{sup 0}) = 530 {+-} 19(stat.) {+-} 57(syst.) mb, in accord with theoretical calculations based on a Glauber approach, but considerably below the predictions of a color dipole model. The {rho}{sup p} transverse momentum spectrum (p{sub T}{sup 2}) is fit by a double exponential curve including both coherent and incoherent coupling to the target nucleus; we find {sigma}{sub inc}/{sigma}{sub coh} = 0.29 {+-} 0.03(stat.) {+-} 0.08(syst.). The ratio of direct {pi}{sup +}{pi}{sup -} to {rho}{sup 0} production is comparable to that observed in {gamma}{sub p} collisions at HERA and appears to be independent of photon energy. Finally, the measured {rho}{sup 0} spin helicity matrix elements agree within errors with the expected s-channel helicity conservation.

  8. Structural elucidation and estimation of the acute toxicity of the major UV-visible photoproduct of fludioxonil - detection in both skin and flesh samples of grape.

    PubMed

    Lassalle, Yannick; Nicol, Édith; Genty, Christophe; Bourcier, Sophie; Bouchonnet, Stéphane

    2015-06-01

    Ultraviolet (UV)-visible irradiation of fludioxonil was investigated with two photoreactors using either a mercury or xenon vapor lamp. In both cases, it led to the formation of only one photoproduct in significant amount: 2-(2,2-difluorobenzo[d][1,3]dioxol-4-yl)-2-(nitrosomethylene)-4-oxobutanenitrile, which has been characterized using Liquid Chromatography - High Resolution - Tandem Mass Spectrometry (LC-HR-MS/MS) coupling. A photolysis pathway has been proposed to rationalize its formation in degassed water. In vitro bioassays on Vibrio fischeri bacteria showed that UV-vis irradiation of an aqueous solution of fludioxonil significantly increases its toxicity. Because no other by-product was detected in significant amount, the photoproduct mentioned above may be considered mainly responsible for this increase in toxicity. Grape berries treated with a 50 ppm aqueous solution of fludioxonil were submitted to UV-visible irradiation under laboratory conditions. The fungicide and photoproduct were detected in both skin and flesh of berries, even after they have been rinsed with water. The ability of the photoproduct to pass through the fruit skin is comparable with that of fludioxonil. These results are of concern for consumers because they mean that water tap rinsing does not lead to efficient removing of both compounds. PMID:26169141

  9. Identification of unwanted photoproducts of cosmetic preservatives in personal care products under ultraviolet-light using solid-phase microextraction and micro-matrix solid-phase dispersion.

    PubMed

    Alvarez-Rivera, Gerardo; Llompart, Maria; Garcia-Jares, Carmen; Lores, Marta

    2015-04-17

    The photochemical transformation of widely used cosmetic preservatives including benzoates, parabens, BHA, BHT and triclosan has been investigated in this work applying an innovative double-approach strategy: identification of transformation products in aqueous photodegradation experiments (UV-light, 254nm), followed by targeted screening analysis of such photoproducts in UV-irradiated cosmetic samples. Solid-phase microextraction (SPME) was applied, using different fiber coatings, in order to widen the range of detectable photoproducts in water, whereas UV-irradiated personal care products (PCPs) containing the target preservatives were extracted by micro-matrix solid-phase dispersion (micro-MSPD). Both SPME and micro-MSPD-based methodologies were successfully optimized and validated. Degradation kinetics of parent species, and photoformation of their transformation by-products were monitored by gas chromatography coupled to mass spectrometry (GC-MS). Thirty nine photoproducts were detected in aqueous photodegradation experiments, being tentatively identified based on their mass spectra. Transformation pathways between structurally related by-products, consistent with their kinetic behavior were postulated. The photoformation of unexpected photoproducts such as 2- and 4-hydroxybenzophenones, and 2,8-dichlorodibenzo-p-dioxin in PCPs are reported in this work for the first time. PMID:25757820

  10. Study of the Relationship between Surface Rupture and Faulting due to 2010 M6.4 Jiashian Earthquake

    NASA Astrophysics Data System (ADS)

    Huang, I.; Huang, W.; Lee, J.

    2013-12-01

    Near-surface deformation induced by earthquake faulting is one of main causes to the damage of engineering structures during earthquakes. In return, information of distribution of damaged engineering structures and deformation features of surface ruptures can reveal important geological characteristics of the responsible fault. The 4 March 2010 Jaishian earthquake (MW6.4) in southwestern Taiwan caused moderate damage in Chiayi, Tainan and Kaohsiung counties, including ground surface fractures, engineering structure damage and soil liquefaction. This study collects and collates all the data from the reports of the earthquake-induced engineering structure damage and field geological fracture investigation. The collated result shows there were dense open-type surface fractures locally distributed within 4-km-long an northwest-trending rupture zone around Meinong town. The surface fractures can be divided into three sets according to their characteristics. One set of the fractures which oriented in azimuth of 230°× 30° likely resulted from the earthquake faulting because of no evidence connected with the weakness of engineering structures. The locations of tens of densely damaged buildings may reflect the relatively stronger near-fault surface deformation. The formation mechanisms of these fractures were studied via analyzing dynamic peak ground strains derived from peak ground velocities and static strains produced from an elastic half-space dislocation model. The result of the dynamic strain analysis shows that the cause of fracturing due to the seismic shaking cannot be ruled out because the magnitude of the strains could reach the threshold of ground failure but there is no evidence for the directional characteristic. On the contrary, open-type fractures and their orientation of 230°× 30° in azimuth produced from the near-surface modeled static strains are consistent with those discovered in field investigations. Thus, this study suggests the NE-trending set

  11. Properties of the Aftershock Sequences of the 2003 Bingöl, M D = 6.4, (Turkey) Earthquake

    NASA Astrophysics Data System (ADS)

    Öztürk, S.; Çinar, H.; Bayrak, Y.; Karsli, H.; Daniel, G.

    2008-02-01

    Aftershock sequences of the magnitude M W =6.4 Bingöl earthquake of 1 May, 2003 (Turkey) are studied to analyze the spatial and temporal variability of seismicity parameters of the b value of the frequency-magnitude distribution and the p value describing the temporal decay rate of aftershocks. The catalog taken from the KOERI contains 516 events and one month’s time interval. The b value is found as 1.49 ± 0.07 with Mc =3.2. Considering the error limits, b value is very close to the maximum b value stated in the literature. This larger value may be caused by the paucity of the larger aftershocks with magnitude M D ≥ 5.0. Also, the aftershock area is divided into four parts in order to detect the differences in b value and the changes illustrate the heterogeneity of the aftershock region. The p value is calculated as 0.86 ± 0.11, relatively small. This small p value may be a result of the slow decay rate of the aftershock activity and the small number of aftershocks. For the fitting of a suitable model and estimation of correct values of decay parameters, the sequence is also modeled as a background seismicty rate model. Constant background activity does not appear to be important during the first month of the Bingöl aftershock sequences and this result is coherent with an average estimation of pre-existing seismicity. The results show that usage of simple modified Omori law is reasonable for the analysis. The spatial variability in b value is between 1.2 and 1.8 and p value varies from 0.6 to 1.2. Although the physical interpretation of the spatial variability of these seismicity parameters is not straightforward, the variation of b and p values can be related to the stress and slip distribution after the mainshock, respectively. The lower b values are observed in the high stress regions and to a certain extent, the largest b values are related to Holocene alluvium. The larger p values are found in some part of the aftershock area although no slip occurred

  12. Multi-wavelength diagnostics and modelling of the emission during a B6.4 flare of August 20, 2005

    NASA Astrophysics Data System (ADS)

    Awasthi, Arun Kumar; Berlicki, Arkadiusz; Rudawy, Powel; Heinzel, Petr

    2015-08-01

    We study the temporal, spatial and spectral evolution of multi-wavelength emission observed during a B6.4 flare occurred on August 20, 2005 with the motivation to outline the thermal and non-thermal processes during the precursor and gradual phase of the flare. Precursor phase is designated as the gradual enhancement of soft X-ray emission prior to onset of the impulsive phase. Observations from several space and ground based observatories viz. RHESSI, TRACE, GONG, SoHO/EIT and NoRP are included in this study. Temporal evolution of X-ray emission does not show the presence of hard X-rays (>12 keV) emission during the precursor phase of the flare. We synthesized X-ray images in 6-12 keV from RHESSI observations, which show several discrete sources during the precursor phase. Following to this, one of these sources pronounced during the main phase of the flare. We carry out in-depth analysis of chromospheric response in various phases of the flare employing high temporal cadence images of the Sun in Hα line centre as well as wings obtained from the Multi-channel Subtractive Double Pass Spectrograph (MSDP) at the Bialkow Observatory of the University of Wroclaw, Poland. Our analysis of Hα images during the main phase of the flare suggests localized emission in the form of kernels. On the contrary, we note extended and diffused source morphology of emitting region during the precursor phase of the flare. We also study various kinematic properties of different structures visible in the Hα images in the line centre as well as wings. In addition, the correlation of the relative timing of X-ray and Hα emission profile is performed to estimate the delay in the chromospheric response during different phases of flare. Further, we employ thermal plasma parameters estimated during the precursor and gradual phase to model the associated Hα emission. For the modeling we employ NLTE numerical codes modified for flare conditions. The modeled and observed flare emission

  13. Isolation of a novel UVB-tolerant rice mutant obtained by exposure to carbon-ion beams.

    PubMed

    Takano, Nao; Takahashi, Yuko; Yamamoto, Mitsuru; Teranishi, Mika; Yamaguchi, Hiroko; Sakamoto, Ayako N; Hase, Yoshihiro; Fujisawa, Hiroko; Wu, Jianzhong; Matsumoto, Takashi; Toki, Seiichi; Hidema, Jun

    2013-07-01

    UVB radiation suppresses photosynthesis and protein biosynthesis in plants, which in turn decreases growth and productivity. Here, an ultraviolet-B (UVB)-tolerant rice mutant, utr319 (UV Tolerant Rice 319), was isolated from a mutagenized population derived from 2500 M1 seeds (of the UVB-resistant cultivar 'Sasanishiki') that were exposed to carbon ions. The utr319 mutant was more tolerant to UVB than the wild type. Neither the levels of UVB-induced cyclobutane pyrimidine dimers (CPDs) or (6-4) pyrimidine-pyrimidone photodimers [(6-4) photoproducts], nor the repair of CPDs or (6-4) photoproducts, was altered in the utr319 mutant. Thus, the utr319 mutant may be impaired in the production of a previously unidentified factor that confers UVB tolerance. To identify the mutated region in the utr319 mutant, microarray-based comparative genomic hybridization analysis was performed. Two adjacent genes on chromosome 7, Os07g0264900 and Os07g0265100, were predicted to represent the mutant allele. Sequence analysis of the chromosome region in utr319 revealed a deletion of 45 419 bp. RNAi analysis indicated that Os07g0265100 is most likely the mutated gene. Database analysis indicated that the Os07g0265100 gene, UTR319, encodes a putative protein with unknown characteristics or function. In addition, the homologs of UTR319 are conserved only among land plants. Therefore, utr319 is a novel UVB-tolerant rice mutant and UTR319 may be crucial for the determination of UVB sensitivity in rice, although the function of UTR319 has not yet been determined. PMID:23381954

  14. The effects of ultraviolet light on aspects of DNA metabolism in cell lines derived from plodia interpunctella and Trichoplusia ni

    SciTech Connect

    Styer, S.C.

    1991-01-01

    Insect cells are significantly more resistant to the lethal effects of 254 nm ultraviolet light (UV) than mammalian cells. The predominant photoproduct produced by UV is the (5-6) cyclobutyl pyrimidine dimer. There is controversy whether this lesion, or another, the pyrimidine (6-4) pyrimidone, is responsible for the biological effects of UV. Insect cells contain a photolyase which selectively removes the (5-6), but not the (6-4) lesion, so that the relative roles of these lesions can be studied. Insect cell lines derived from the cabbage looper and the Indian meal moth were exposed to UV and analyzed for their ability to incorporate [sup 3]H-thymidine. After exposure, cells from the Indian meal moth exhibited a rapid and prolonged depression in the rate of thymidine incorporation, whereas cells from the cabbage looper showed only a slight drop in incorporation and a rapid recovery. The extent of depression in thymidine incorporation was not correlated to the amount of cell killing by UV in these cell lines. Blockage of fork progression was correlated to the depression in thymidine incorporation. Photoreactivation did not entirely relieve blockage, depression in thymidine incorporation or cell killing, indicating that although the (5-6) dimer appears to be the major lesion responsible for these effects, other lesions, such as the (6-4) photoproduct, may play a role. In addition, activation of alternative sites of replicon initiation appeared to correlate with the depression in thymidine incorporation and the excision capabilities in these cells. The resistance to UV in these insect cells compared to mammalian cells may be due to their ability to rapidly remove the (5-6) lesion, which is the critical lesion in these insect cells.

  15. Evidence for an Exotic Baryon State, Theta{sup +}(1540), in Photoproduction Reactions from Protons and Deuterons with CLAS

    SciTech Connect

    Valery Kubarovsky; Stepan Stepanyan

    2003-05-01

    CLAS photoproduction data on deuterium and hydrogen targets have been analyzed in a search for an exotic baryon state with strangeness S = +1, the {Theta}{sup +} (originally named the Z{sup +}). This resonance was predicted recently in theoretical work based on the chiral soliton model as a lowest mass member of an anti-decuplet of 5-quark states. The reaction {gamma}d {yields} pK{sup -}K{sup +}n, which requires a final state interaction inside the deuteron, was used in the analysis of deuteron data. In the analysis of proton data, the reaction {gamma}p {yields} {pi}{sup +}K{sup -}K{sup +}n was studied. Evidence for the {Theta}{sup +} state is found in both analyzes in the invariant mass distribution of the nK{sup +}. Our results are consistent with previously reported results by LEPS/Spring-8 collaboration (Japan), and by the ITEP (Moscow) group.

  16. Em Calorimeter Complex Forest for the π0 and η Photo-Production Experiments at Lns-Sendai

    NASA Astrophysics Data System (ADS)

    Suzuki, K.; Fujimura, H.; Hashimoto, R.; Ishikawa, T.; Kasagi, J.; Kuwasaki, S.; Mochizuki, K.; Nawa, K.; Okada, Y.; Onodera, Y.; Sato, M.; Shimizu, H.; Yamazaki, H.; Kawano, A.; Sakamoto, Y.; Maeda, K.

    A large solid angle γ-ray detector system, FOREST, has been constructed at LNS-Sendai to study the π0 and η photo-production reactions. The FOREST detector consists of three electro-magnetic calorimeters: pure CsI crystals, Lead/SciFi blocks and Lead Glass Cherenkov counters. It covers about 90% of the total solid angle. A new data acquisition system for the FOREST detector has been developed to handle high rate trigger events with a high efficiency. To investigate performances of FOREST and the DAQ system, a test experiment has been conducted. The π0 and η mesons are clearly observed. A DAQ efficiency of 76% has been obtained at a 2 kHz trigger request.

  17. Study of the effective transverse momentum of partons in the proton using prompt photons in photoproduction at HERA

    NASA Astrophysics Data System (ADS)

    ZEUS Collaboration; Chekanov, S.; Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Pellegrino, A.; Repond, J.; Stanek, R.; Yoshida, R.; Mattingly, M. C. K.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Sartorelli, G.; Zichichi, A.; Aghuzumtsyan, G.; Brock, I.; Goers, S.; Hartmann, H.; Hilger, E.; Irrgang, P.; Jakob, H.-P.; Kappes, A.; Katz, U. F.; Kerger, R.; Kind, O.; Paul, E.; Rautenberg, J.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K. C.; Weber, A.; Wieber, H.; Bailey, D. S.; Brook, N. H.; Cole, J. E.; Foster, B.; Heath, G. P.; Heath, H. F.; Robins, S.; Rodrigues, E.; Scott, J.; Tapper, R. J.; Capua, M.; Mastroberardino, A.; Schioppa, M.; Susinno, G.; Jeoung, H. Y.; Kim, J. Y.; Lee, J. H.; Lim, I. T.; Ma, K. J.; Pac, M. Y.; Caldwell, A.; Helbich, M.; Liu, W.; Liu, X.; Mellado, B.; Paganis, S.; Sampson, S.; Schmidke, W. B.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Klimek, K.; Olkiewicz, K.; Przybycień, M. B.; Stopa, P.; Zawiejski, L.; Bednarek, B.; Jeleń, K.; Kisielewska, D.; Kowal, A. M.; Kowalski, T.; Przybycień, M.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Szuba, D.; Kotański, A.; Bauerdick, L. A. T.; Behrens, U.; Borras, K.; Chiochia, V.; Crittenden, J.; Dannheim, D.; Desler, K.; Drews, G.; Fox-Murphy, A.; Fricke, U.; Geiser, A.; Goebel, F.; Göttlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G. F.; Hebbel, K.; Hillert, S.; Koch, W.; Kötz, U.; Kowalski, H.; Labes, H.; Löhr, B.; Mankel, R.; Martens, J.; Martínez, M.; Milite, M.; Moritz, M.; Notz, D.; Petrucci, M. C.; Polini, A.; Savin, A. A.; Schneekloth, U.; Selonke, F.; Stonjek, S.; Wolf, G.; Wollmer, U.; Whitmore, J. J.; Wichmann, R.; Youngman, C.; Zeuner, W.; Coldewey, C.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.; Barbagli, G.; Gallo, E.; Parenti, A.; Pelfer, P. G.; Bamberger, A.; Benen, A.; Coppola, N.; Markun, P.; Raach, H.; Wölfle, S.; Bell, M.; Bussey, P. J.; Doyle, A. T.; Glasman, C.; Lee, S. W.; Lupi, A.; McCance, G. J.; Saxon, D. H.; Skillicorn, I. O.; Bodmann, B.; Gendner, N.; Holm, U.; Salehi, H.; Wick, K.; Yildirim, A.; Ziegler, A.; Carli, T.; Garfagnini, A.; Gialas, I.; Lohrmann, E.; Foudas, C.; Gonçalo, R.; Long, K. R.; Metlica, F.; Miller, D. B.; Tapper, A. D.; Walker, R.; Cloth, P.; Filges, D.; Ishii, T.; Kuze, M.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Barakbaev, A. N.; Boos, E. G.; Pokrovskiy, N. S.; Zhautykov, B. O.; Ahn, S. H.; Lee, S. B.; Park, S. K.; Lim, H.; Son, D.; Barreiro, F.; García, G.; González, O.; Labarga, L.; del Peso, J.; Redondo, I.; Terrón, J.; Vázquez, M.; Barbi, M.; Corriveau, F.; Padhi, S.; Stairs, D. G.; Wing, M.; Tsurugai, T.; Antonov, A.; Bashkirov, V.; Danilov, P.; Dolgoshein, B. A.; Gladkov, D.; Sosnovtsev, V.; Suchkov, S.; Dementiev, R. K.; Ermolov, P. F.; Golubkov, Y. A.; Katkov, I. I.; Khein, L. A.; Korotkova, N. A.; Korzhavina, I. A.; Kuzmin, V. A.; Levchenko, B. B.; Lukina, O. Y.; Proskuryakov, A. S.; Shcheglova, L. M.; Solomin, A. N.; Vlasov, N. N.; Zotkin, S. A.; Bokel, C.; Botje, M.; Engelen, J.; Grijpink, S.; Koffeman, E.; Kooijman, P.; Schagen, S.; van Sighem, A.; Tassi, E.; Tiecke, H.; Tuning, N.; Velthuis, J. J.; Vossebeld, J.; Wiggers, L.; de Wolf, E.; Brümmer, N.; Bylsma, B.; Durkin, L. S.; Gilmore, J.; Ginsburg, C. M.; Kim, C. L.; Ling, T. Y.; Boogert, S.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Ferrando, J.; Große-Knetter, J.; Matsushita, T.; Rigby, M.; Ruske, O.; Sutton, M. R.; Walczak, R.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; Dusini, S.; Limentani, S.; Longhin, A.; Posocco, M.; Stanco, L.; Turcato, M.; Adamczyk, L.; Iannotti, L.; Oh, B. Y.; Saull, P. R. B.; Toothacker, W. S.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cormack, C.; Hart, J. C.; McCubbin, N. A.; Epperson, D.; Heusch, C.; Sadrozinski, H. F.-W.; Seiden, A.; Williams, D. C.; Park, I. H.; Pavel, N.; Abramowicz, H.; Dagan, S.; Gabareen, A.; Kananov, S.; Kreisel, A.; Levy, A.; Abe, T.; Fusayasu, T.; Kohno, T.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Inuzuka, M.; Kitamura, S.; Matsuzawa, K.; Nishimura, T.; Arneodo, M.; Cartiglia, N.; Cirio, R.; Costa, M.; Ferrero, M. I.; Maselli, S.; Monaco, V.; Peroni, C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Bailey, D. C.; Fagerstroem, C.-P.; Galea, R.; Koop, T.; Levman, G. M.; Martin, J. F.; Mirea, A.; Sabetfakhri, A.; Butterworth, J. M.; Gwenlan, C.; Hayes, M. E.; Heaphy, E. A.; Jones, T. W.; Lane, J. B.; West, B. J.; Ciborowski, J.; Ciesielski, R.; Grzelak, G.; Nowak, R. J.; Pawlak, J. M.; Plucinski, P.; Smalska, B.; Sztuk, J.; Tymieniecka, T.; Ukleja, J.; Zakrzewski, J. A.; Z˙arnecki, A. F.; Adamus, M.; Deppe, O.; Eisenberg, Y.; Gladilin, L. K.; Hochman, D.; Karshon, U.; Breitweg, J.; Chapin, D.; Cross, R.; Kçira, D.; Lammers, S.; Reeder, D. D.; Smith, W. H.; Deshpande, A.; Dhawan, S.; Hughes, V. W.; Straub, P. B.; Bhadra, S.; Catterall, C. D.; Frisken, W. R.; Hall-Wilton, R.; Khakzad, M.; Menary, S.

    2001-06-01

    The photoproduction of prompt photons, together with an accompanying jet, has been measured with the ZEUS detector at HERA using an integrated luminosity of 38.6 pb-1. A study of the effective transverse momentum, , of partons in the proton, as modelled within the framework of the PYTHIA Monte Carlo, gives a value of =1.69+/-0.18+0.18-0.20 GeV for the /γp centre-of-mass energy range /134 to rise with interaction energy.

  18. Measurement of the spin asymmetry in the photoproduction of pairs of high- p(T) hadrons at HERMES

    PubMed

    McIlhany; McKeown; Meissner; Menden; Metz; Meyners; Mikloukho; Miller; Miller; Milner; Most; Muccifora; Naryshkin; Nathan; Neunreither; Niczyporuk; Nowak; O'Neill; Openshaw; Ouyang; Owen; Pate; Potashov; Potterveld; Rakness; Redwine

    2000-03-20

    We present a measurement of the longitudinal spin asymmetry A(||) in photoproduction of pairs of hadrons with high transverse momentum p(T). Data were accumulated by the HERMES experiment using a 27.5 GeV polarized positron beam and a polarized hydrogen target internal to the HERA storage ring. For h(+)h(-) pairs with p(h(1))(T)>1.5 GeV/c and p(h(2))(T)>1.0 GeV/c, the measured asymmetry is A(||) = -0. 28+/-0.12(stat)+/-0.02(syst). This negative value is in contrast to the positive asymmetries typically measured in deep inelastic scattering from protons, and is interpreted to arise from a positive gluon polarization. PMID:11017275

  19. The photoproduction of strange mesons in γ p → ΛK+π+π- with CLAS at Jefferson Lab

    NASA Astrophysics Data System (ADS)

    Ghoul, Hussein Al

    2016-05-01

    The γ p → ΛK+π+π- reaction provides an opportunity to study the photoproduction of excited strange mesons in the K+π+π- system using the g12 experiment dataset at Jefferson Lab. The g12 experiment used the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab with a liquid hydrogen target and a 4 - 5.5 GeV tagged photon beam, producing over 26 billion events of different topologies. The Λ in this reaction is identified via the pπ- decay mode. Studies indicate two dominating decay modes in the K+π+π- system: the K*π+ mode and the K+ρ mode. Studies of the angular distributions and dynamical features were performed. Preliminary results of features of the data are presented.

  20. Continuous hydrogen photoproduction by Chlamydomonas reinhardtii: using a novel two-stage, sulfate-limited chemostat system.

    PubMed

    Fedorov, Alexander S; Kosourov, Sergey; Ghirardi, Maria L; Seibert, Michael

    2005-01-01

    This study demonstrates, for the first time, that it is possible to couple sulfate-limited Chlamydomonas reinhardtii growth to continuous H2 photoproduction for more than 4000 h. A two-stage chemostat system physically separates photosynthetic growth from H2 production, and it incorporates two automated photobioreactors (PhBRs). In the first PhBR, the algal cultures are grown aerobically in chemostat mode under limited sulfate to obtain photosynthetically competent cells. Active cells are then continuously delivered to the second PhBR, where H2 production occurs under anaerobic conditions. The dependence of the H2 production rate on sulfate concentration in the medium, dilution rates in the PhBRs, and incident light intensity is reported. PMID:15917617

  1. Charmonium and e + e - pair photoproduction at mid-rapidity in ultra-peripheral Pb-Pb collisions at

    NASA Astrophysics Data System (ADS)

    Abbas, E.; Abelev, B.; Adam, J.; Adamová, D.; Adare, A. M.; Aggarwal, M. M.; Aglieri Rinella, G.; Agnello, M.; Agocs, A. G.; Agostinelli, A.; Ahammed, Z.; Ahmad, N.; Ahmad Masoodi, A.; Ahmed, I.; Ahn, S. A.; Ahn, S. U.; Aimo, I.; Ajaz, M.; Akindinov, A.; Aleksandrov, D.; Alessandro, B.; Alexandre, D.; Alici, A.; Alkin, A.; Almaráz Aviña, E.; Alme, J.; Alt, T.; Altini, V.; Altinpinar, S.; Altsybeev, I.; Andrei, C.; Andronic, A.; Anguelov, V.; Anielski, J.; Anson, C.; Antičić, T.; Antinori, F.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Arbor, N.; Arcelli, S.; Arend, A.; Armesto, N.; Arnaldi, R.; Aronsson, T.; Arsene, I. C.; Arslandok, M.; Asryan, A.; Augustinus, A.; Averbeck, R.; Awes, T. C.; Äystö, J.; Azmi, M. D.; Bach, M.; Badalà, A.; Baek, Y. W.; Bailhache, R.; Bala, R.; Baldisseri, A.; Baltasar Dos Santos Pedrosa, F.; Bán, J.; Baral, R. C.; Barbera, R.; Barile, F.; Barnaföldi, G. G.; Barnby, L. S.; Barret, V.; Bartke, J.; Basile, M.; Bastid, N.; Basu, S.; Bathen, B.; Batigne, G.; Batyunya, B.; Batzing, P. C.; Baumann, C.; Bearden, I. G.; Beck, H.; Behera, N. K.; Belikov, I.; Bellini, F.; Bellwied, R.; Belmont-Moreno, E.; Bencedi, G.; Beole, S.; Berceanu, I.; Bercuci, A.; Berdnikov, Y.; Berenyi, D.; Bergognon, A. A. E.; Bertens, R. A.; Berzano, D.; Betev, L.; Bhasin, A.; Bhati, A. K.; Bhom, J.; Bianchi, L.; Bianchi, N.; Bianchin, C.; Bielčík, J.; Bielčíková, J.; Bilandzic, A.; Bjelogrlic, S.; Blanco, F.; Blanco, F.; Blau, D.; Blume, C.; Boccioli, M.; Böttger, S.; Bogdanov, A.; Bøggild, H.; Bogolyubsky, M.; Boldizsár, L.; Bombara, M.; Book, J.; Borel, H.; Borissov, A.; Bossú, F.; Botje, M.; Botta, E.; Braidot, E.; Braun-Munzinger, P.; Bregant, M.; Breitner, T.; Broker, T. A.; Browning, T. A.; Broz, M.; Brun, R.; Bruna, E.; Bruno, G. E.; Budnikov, D.; Buesching, H.; Bufalino, S.; Buncic, P.; Busch, O.; Buthelezi, Z.; Caffarri, D.; Cai, X.; Caines, H.; Calvo Villar, E.; Camerini, P.; Canoa Roman, V.; Cara Romeo, G.; Carena, W.; Carena, F.; Carlin Filho, N.; Carminati, F.; Casanova Díaz, A.; Castillo Castellanos, J.; Castillo Hernandez, J. F.; Casula, E. A. R.; Catanescu, V.; Cavicchioli, C.; Ceballos Sanchez, C.; Cepila, J.; Cerello, P.; Chang, B.; Chapeland, S.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chibante Barroso, V.; Chinellato, D. D.; Chochula, P.; Chojnacki, M.; Choudhury, S.; Christakoglou, P.; Christensen, C. H.; Christiansen, P.; Chujo, T.; Chung, S. U.; Cicalo, C.; Cifarelli, L.; Cindolo, F.; Cleymans, J.; Colamaria, F.; Colella, D.; Collu, A.; Conesa Balbastre, G.; Conesa del Valle, Z.; Connors, M. E.; Contin, G.; Contreras, J. G.; Cormier, T. M.; Corrales Morales, Y.; Cortese, P.; Cortés Maldonado, I.; Cosentino, M. R.; Costa, F.; Cotallo, M. E.; Crescio, E.; Crochet, P.; Cruz Alaniz, E.; Cruz Albino, R.; Cuautle, E.; Cunqueiro, L.; Dainese, A.; Dang, R.; Danu, A.; Das, K.; Das, I.; Das, S.; Das, D.; Dash, S.; Dash, A.; De, S.; de Barros, G. O. V.; De Caro, A.; de Cataldo, G.; de Cuveland, J.; De Falco, A.; De Gruttola, D.; Delagrange, H.; Deloff, A.; De Marco, N.; Dénes, E.; De Pasquale, S.; Deppman, A.; D Erasmo, G.; de Rooij, R.; Diaz Corchero, M. A.; Di Bari, D.; Dietel, T.; Di Giglio, C.; Di Liberto, S.; Di Mauro, A.; Di Nezza, P.; Divià, R.; Djuvsland, Ø.; Dobrin, A.; Dobrowolski, T.; Dönigus, B.; Dordic, O.; Dubey, A. K.; Dubla, A.; Ducroux, L.; Dupieux, P.; Dutta Majumdar, A. K.; Elia, D.; Emschermann, D.; Engel, H.; Erazmus, B.; Erdal, H. A.; Eschweiler, D.; Espagnon, B.; Estienne, M.; Esumi, S.; Evans, D.; Evdokimov, S.; Eyyubova, G.; Fabris, D.; Faivre, J.; Falchieri, D.; Fantoni, A.; Fasel, M.; Fehlker, D.; Feldkamp, L.; Felea, D.; Feliciello, A.; Fenton-Olsen, B.; Feofilov, G.; Fernández Téllez, A.; Ferretti, A.; Festanti, A.; Figiel, J.; Figueredo, M. A. S.; Filchagin, S.; Finogeev, D.; Fionda, F. M.; Fiore, E. M.; Floratos, E.; Floris, M.; Foertsch, S.; Foka, P.; Fokin, S.; Fragiacomo, E.; Francescon, A.; Frankenfeld, U.; Fuchs, U.; Furget, C.; Fusco Girard, M.; Gaardhøje, J. J.; Gagliardi, M.; Gago, A.; Gallio, M.; Gangadharan, D. R.; Ganoti, P.; Garabatos, C.; Garcia-Solis, E.; Gargiulo, C.; Garishvili, I.; Gerhard, J.; Germain, M.; Geuna, C.; Gheata, M.; Gheata, A.; Ghidini, B.; Ghosh, P.; Gianotti, P.; Giubellino, P.; Gladysz-Dziadus, E.; Glässel, P.; Gomez, R.; Ferreiro, E. G.; González-Trueba, L. H.; González-Zamora, P.; Gorbunov, S.; Goswami, A.; Gotovac, S.; Graczykowski, L. K.; Grajcarek, R.; Grelli, A.; Grigoras, C.; Grigoras, A.; Grigoriev, V.; Grigoryan, A.; Grigoryan, S.; Grinyov, B.; Grion, N.; Gros, P.; Grosse-Oetringhaus, J. F.; Grossiord, J.-Y.; Grosso, R.; Guber, F.; Guernane, R.; Guerzoni, B.; Guilbaud, M.; Gulbrandsen, K.

    2013-11-01

    The ALICE Collaboration at the LHC has measured the J/ ψ and ψ' photoproduction at mid-rapidity in ultra-peripheral Pb-Pb collisions at . The charmonium is identified via its leptonic decay for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 23 μb-1. The cross section for coherent and incoherent J/ ψ production in the rapidity interval -0.9< y<0.9, are and , respectively. The results are compared to theoretical models for J/ ψ production and the coherent cross section is found to be in good agreement with those models incorporating moderate nuclear gluon shadowing at Bjorken- x around 10-3, such as EPS09 parametrization. In addition the cross section for the process γγ→ e + e - has been measured and found to be in agreement with models implementing QED at leading order.

  2. Factors affecting the photoproduction of ammonia from dinitrogen and water by the cyanobacterium Anabaena sp. strain ATCC 33047

    SciTech Connect

    Ramos, J.L.; Guerrero, M.G.; Losada, M.

    1987-04-01

    Synthesis of ammonia from dinitrogen and water by suspensions of Anabaena sp. strain ATCC 33047 treated with the glutamine synthetase inhibitor L-methionine-D,L-sulfoximine is strictly dependent on light. Under otherwise optimal conditions, the yield of ammonia production is influenced by irradiance, as well as by the density, depth, and turbulence of the cell suspension. The interaction among these factors seems to determine the actual amount of light available to each single cell or filament in the suspension for the photoproduction process. Under convenient illumination, the limiting factor in the synthesis of ammonia seems to be the cellular nitrogenase activity level, but under limiting light conditions the limiting factor could, however, be the assimilatory power required for nitrogen fixation. Photosynthetic ammonia production from atmospheric nitrogen and water can operate with an efficiency of ca. 10% of its theoretical maximum, representing a remarkable process for the conversion of light energy into chemical energy.

  3. Polarization Components in π0 Photoproduction at Photon Energies up to 5.6 GeV

    NASA Astrophysics Data System (ADS)

    Luo, W.; Brash, E. J.; Gilman, R.; Jones, M. K.; Meziane, M.; Pentchev, L.; Perdrisat, C. F.; Puckett, A. J. R.; Punjabi, V.; Wesselmann, F. R.; Ahmidouch, A.; Albayrak, I.; Aniol, K. A.; Arrington, J.; Asaturyan, A.; Ates, O.; Baghdasaryan, H.; Benmokhtar, F.; Bertozzi, W.; Bimbot, L.; Bosted, P.; Boeglin, W.; Butuceanu, C.; Carter, P.; Chernenko, S.; Christy, M. E.; Commisso, M.; Cornejo, J. C.; Covrig, S.; Danagoulian, S.; Daniel, A.; Davidenko, A.; Day, D.; Dhamija, S.; Dutta, D.; Ent, R.; Frullani, S.; Fenker, H.; Frlez, E.; Garibaldi, F.; Gaskell, D.; Gilad, S.; Goncharenko, Y.; Hafidi, K.; Hamilton, D.; Higinbotham, D. W.; Hinton, W.; Horn, T.; Hu, B.; Huang, J.; Huber, G. M.; Jensen, E.; Kang, H.; Keppel, C.; Khandaker, M.; King, P.; Kirillov, D.; Kohl, M.; Kravtsov, V.; Kumbartzki, G.; Li, Y.; Mamyan, V.; Margaziotis, D. J.; Markowitz, P.; Marsh, A.; Matulenko, Y.; Maxwell, J.; Mbianda, G.; Meekins, D.; Melnik, Y.; Miller, J.; Mkrtchyan, A.; Mkrtchyan, H.; Moffit, B.; Moreno, O.; Mulholland, J.; Narayan, A.; Nuruzzaman; Nedev, S.; Piasetzky, E.; Pierce, W.; Piskunov, N. M.; Prok, Y.; Ransome, R. D.; Razin, D. S.; Reimer, P. E.; Reinhold, J.; Rondon, O.; Shabestari, M.; Shahinyan, A.; Shestermanov, K.; Širca, S.; Sitnik, I.; Smykov, L.; Smith, G.; Solovyev, L.; Solvignon, P.; Strakovsky, I. I.; Subedi, R.; Suleiman, R.; Tomasi-Gustafsson, E.; Vasiliev, A.; Veilleux, M.; Wood, S.; Ye, Z.; Zanevsky, Y.; Zhang, X.; Zhang, Y.; Zheng, X.; Zhu, L.

    2012-06-01

    We present new data for the polarization observables of the final state proton in the H1(γ→,p→)π0 reaction. These data can be used to test predictions based on hadron helicity conservation and perturbative QCD. These data have both small statistical and systematic uncertainties and were obtained with beam energies between 1.8 and 5.6 GeV and for π0 scattering angles larger than 75° in the center-of-mass frame. The data extend the polarization measurements database for neutral pion photoproduction up to Eγ=5.6GeV. The results show a nonzero induced polarization above the resonance region. The polarization transfer components vary rapidly with the photon energy and π0 scattering angle in the center-of-mass frame. This indicates that hadron helicity conservation does not hold and that the perturbative QCD limit is still not reached in the energy regime of this experiment.

  4. Probing the reaction mechanism of spore photoproduct lyase (SPL) via diastereoselectively labeled dinucleotide SP TpT substrates

    PubMed Central

    Yang, Linlin; Lin, Gengjie; Liu, Degang; Dria, Karl J.; Telser, Joshua; Li, Lei

    2011-01-01

    5-thyminyl-5,6-dihydrothymine (commonly called spore photoproduct or SP) is the exclusive DNA photo-damage product in bacterial endospores. It is generated in the bacterial sporulation phase and repaired by a radical SAM enzyme, spore photoproduct lyase (SPL), at the early germination phase. SPL utilizes a special [4Fe-4S] cluster to reductively cleave S-adenosylmethionine (SAM) to generate a reactive 5′-dA radical. The 5′-dA radical is proposed to abstract one of the two H atoms at the C6 carbon of SP to initiate the repair process. Via organic synthesis and DNA photochemistry, we selectively labeled the 6-HproS or 6-HproR position with a deuterium in a dinucleotide SP TpT substrate. Monitoring the deuterium migration in enzyme catalysis (employing Bacillus subtilis SPL) revealed that it is the 6-HproR atom of SP that is abstracted by the 5′-dA radical. Surprisingly, the abstracted deuterium was not returned to the resulting TpT after enzymatic catalysis, an H atom from the aqueous buffer was incorporated into TpT instead. This result questions the currently hypothesized SPL mechanism which excludes the involvement of protein residue(s) in SPL reaction, suggesting that some protein residue(s), which is capable of exchanging a proton with the aqueous buffer, is involved in the enzyme catalysis. Moreover, evidence has been obtained for a possible SAM regeneration after each catalytic cycle; however, such a regeneration process is more complex than currently thought, with one or even more protein residues involved as well. These observations have enabled us to propose a modified reaction mechanism for this intriguing DNA repair enzyme. PMID:21671623

  5. Purification, cDNA cloning, and expression profiles of the cyclobutane pyrimidine dimer photolyase of Xenopus laevis.

    PubMed

    Tanida, Hiroaki; Tahara, Eiji; Mochizuki, Miwa; Yamane, Yukiko; Ryoji, Masaru

    2005-12-01

    Photolyase is a light-dependent enzyme that repairs pyrimidine dimers in DNA. Two types of photolyases have been found in frog Xenopus laevis, one for repairing cyclobutane pyrimidine dimers (CPD photolyase) and the other for pyrimidine-pyrimidone (6-4)photoproduct [(6-4)photolyase]. However, little is known about the former type of the Xenopus photolyases. To characterize this enzyme and its expression profiles, we isolated the entire coding region of a putative CPD photolyase cDNA by extending an EST (expressed sequence tag) sequence obtained from the Xenopus database. Nucleotide sequence analysis of the cDNA revealed a protein of 557 amino acids with close similarity to CPD photolyase of rat kangaroo. The identity of this cDNA was further established by the molecular mass (65 kDa) and the partial amino acid sequences of the major CPD photolyase that we purified from Xenopus ovaries. The gene of this enzyme is expressed in various tissues of Xenopus. Even internal organs like heart express relatively high levels of mRNA. A much smaller amount was found in skin, although UV damage is thought to occur most frequently in this tissue. Such expression profiles suggest that CPD photolyase may have roles in addition to the photorepair function. PMID:16302973

  6. Integration and scaling of UV-B radiation effects on plants: from DNA to leaf.

    PubMed

    Suchar, Vasile Alexandru; Robberecht, Ronald

    2015-07-01

    A process-based model integrating the effects of UV-B radiation through epidermis, cellular DNA, and its consequences to the leaf expansion was developed from key parameters in the published literature. Enhanced UV-B radiation-induced DNA damage significantly delayed cell division, resulting in significant reductions in leaf growth and development. Ambient UV-B radiation-induced DNA damage significantly reduced the leaf growth of species with high relative epidermal absorbance at longer wavelengths and average/low pyrimidine cyclobutane dimers (CPD) photorepair rates. Leaf expansion was highly dependent on the number of CPD present in the DNA, as a result of UV-B radiation dose, quantitative and qualitative absorptive properties of epidermal pigments, and repair mechanisms. Formation of pyrimidine-pyrimidone (6-4) photoproducts (6-4PP) has no effect on the leaf expansion. Repair mechanisms could not solely prevent the UV-B radiation interference with the cell division. Avoidance or effective shielding by increased or modified qualitative epidermal absorptance was required. Sustained increased UV-B radiation levels are more detrimental than short, high doses of UV-B radiation. The combination of low temperature and increased UV-B radiation was more significant in the level of UV-B radiation-induced damage than UV-B radiation alone. Slow-growing leaves were more affected by increased UV-B radiation than fast-growing leaves. PMID:26257869

  7. Integration and scaling of UV-B radiation effects on plants: from DNA to leaf

    PubMed Central

    Suchar, Vasile Alexandru; Robberecht, Ronald

    2015-01-01

    A process-based model integrating the effects of UV-B radiation through epidermis, cellular DNA, and its consequences to the leaf expansion was developed from key parameters in the published literature. Enhanced UV-B radiation-induced DNA damage significantly delayed cell division, resulting in significant reductions in leaf growth and development. Ambient UV-B radiation-induced DNA damage significantly reduced the leaf growth of species with high relative epidermal absorbance at longer wavelengths and average/low pyrimidine cyclobutane dimers (CPD) photorepair rates. Leaf expansion was highly dependent on the number of CPD present in the DNA, as a result of UV-B radiation dose, quantitative and qualitative absorptive properties of epidermal pigments, and repair mechanisms. Formation of pyrimidine-pyrimidone (6-4) photoproducts (6-4PP) has no effect on the leaf expansion. Repair mechanisms could not solely prevent the UV-B radiation interference with the cell division. Avoidance or effective shielding by increased or modified qualitative epidermal absorptance was required. Sustained increased UV-B radiation levels are more detrimental than short, high doses of UV-B radiation. The combination of low temperature and increased UV-B radiation was more significant in the level of UV-B radiation-induced damage than UV-B radiation alone. Slow-growing leaves were more affected by increased UV-B radiation than fast-growing leaves. PMID:26257869

  8. Human DNA repair disorders in dermatology: A historical perspective, current concepts and new insight.

    PubMed

    Moriwaki, Shinichi

    2016-02-01

    Products of DNA damage, such as cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6-4) pyrimidone photoproducts (6-4 PPs), are continually formed in genomes after exposure to UV radiation. When these DNA damages remain unrepaired in essential DNA sites for prolonged periods, DNA replication and transcription are hampered or mutation is induced, which may cause cell death, cellular senescence, and carcinogenesis of the skin. To protect against such UV-induced DNA damage, living organisms nicely retain "DNA repair systems", which can efficiently repair "harmful" DNA damage through precise mechanisms by the integrated functions of many proteins. In humans, the failure of DNA repair systems causes a variety of disorders. Dermatological conditions such as hereditary photodermatoses, xeroderma pigmentosum (XP) and Cockayne syndrome (CS) are caused by congenital functional defects in the nucleotide excision repair (NER) system or the translesion synthesis (TLS) system. In this review, we describe the historical progress, recent findings, and future prospects of studies of human diseases associated with DNA-repair defects. PMID:26493104

  9. Analysis of 6.4 KEV Moessbauer Spectra Obtained with MIMOS II on MER on Cobbles at Meridiani Planum, Mars and Considerations on Penetration Depths

    NASA Technical Reports Server (NTRS)

    Fleischer, I.; Klingelhoefer, G.; Morris, R. V.; Schroder, C.; Rodionov, D.; deSouza, P.

    2008-01-01

    The miniaturized Moessbauer (MB) spectrometers MIMOS II [1] on board of the two Mars Exploration Rovers Spirit and Opportunity have obtained more than 600 spectra of more than 300 different rock and soil targets [2-7]. Both instruments have simultaneously collected 6.4 keV X-ray and 14.4 keV .-ray spectra in backscattering geometry [1]. With Spirit's MB spectrometer, 6.4 keV and 14.4 keV spectra have been obtained for all targets through sol 461. After this date, only 14.4 keV spectra were collected. With Opportunity's spectrometer, 6.4 keV and 14.4 keV spectra have been collected for all targets to date. The Fe-mineralogy of rock and soil targets at both landing sites reported to date has been exclusively extracted from 14.4 keV spectra [2-5]. The comparison of 6.4 keV and 14.4 keV spectra provides depth selective information about a sample, but interpretation is not always straightforward [8].

  10. Modulation of Closed−State Inactivation in Kv2.1/Kv6.4 Heterotetramers as Mechanism for 4−AP Induced Potentiation

    PubMed Central

    Labro, Alain J.; Snyders, Dirk J.

    2015-01-01

    The voltage−gated K+ (Kv) channel subunits Kv2.1 and Kv2.2 are expressed in almost every tissue. The diversity of Kv2 current is increased by interacting with the electrically silent Kv (KvS) subunits Kv5−Kv6 and Kv8−Kv9, into functional heterotetrameric Kv2/KvS channels. These Kv2/KvS channels possess unique biophysical properties and display a more tissue-specific expression pattern, making them more desirable pharmacological and therapeutic targets. However, little is known about the pharmacological properties of these heterotetrameric complexes. We demonstrate that Kv5.1, Kv8.1 and Kv9.3 currents were inhibited differently by the channel blocker 4−aminopyridine (4−AP) compared to Kv2.1 homotetramers. In contrast, Kv6.4 currents were potentiated by 4−AP while displaying moderately increased affinities for the channel pore blockers quinidine and flecainide. We found that the 4−AP induced potentiation of Kv6.4 currents was caused by modulation of the Kv6.4−mediated closed−state inactivation: suppression by 4−AP of the Kv2.1/Kv6.4 closed−state inactivation recovered a population of Kv2.1/Kv6.4 channels that was inactivated at resting conditions, i.e. at a holding potential of −80 mV. This modulation also resulted in a slower initiation and faster recovery from closed−state inactivation. Using chimeric substitutions between Kv6.4 and Kv9.3 subunits, we demonstrated that the lower half of the S6 domain (S6c) plays a crucial role in the 4−AP induced potentiation. These results demonstrate that KvS subunits modify the pharmacological response of Kv2 subunits when assembled in heterotetramers and illustrate the potential of KvS subunits to provide unique pharmacological properties to the heterotetramers, as is the case for 4−AP on Kv2.1/Kv6.4 channels. PMID:26505474

  11. J/ Φ photo-production measurement at RHIC using the STAR detector for √sNN = 200 GeV Au +Au collisions

    NASA Astrophysics Data System (ADS)

    de Silva, Chanaka

    2014-09-01

    Ultra-peripheral collision events are effectively photo-production on nuclear targets. Relativistic heavy ions carry strong transverse electromagnetic fields that can be treated as sources of quasi-real virtual photons. The ions interact through photon-Pomeron and photon-photon collisions at impact parameters more than twice the nuclear radius, so hadronic interactions are suppressed in ultra-peripheral events. These events also provide an ideal proving ground for new programs in e +A physics. We present the latest results on J/ Φ photo-production using √sNN = 200 GeV Au +Au collisions in the STAR experiment at RHIC. The pT distribution of the J/ Φ mesons peaks at very low pT, consistent with expectations for coherent photo-production. We further discuss the current status of measurements that are expected to provide information on nuclear gluon distributions, gluon shadowing, generalized parton distributions and parton form factors. Finally, we present the measurement of the ratio of J/ Φ to ρ production as a function of rapidity for √sNN = 200 GeV Au +Au collisions. Possible theory comparisons are also discussed.

  12. Crystallographic and infrared spectroscopic study of bond distances in Ln[Fe(CN){sub 6}].4H{sub 2}O (Ln=lanthanide)

    SciTech Connect

    Zhou Xianju; Wong, W.-T.; Faucher, Michele D.; Tanner, Peter A.

    2008-11-15

    Along with crystallographic data of Ln[Fe(CN){sub 6}].4H{sub 2}O (Ln=lanthanide), the infrared spectra are reassigned to examine bond length trends across the series of Ln. The changes in mean Ln-O, Ln-N, C{identical_to}N and Fe-C distances are discussed and the bond natures of Ln-N and Ln-O are studied by bond length linear or quadratic fitting and comparisons with relevant ionic radii. The two different C{identical_to}N bond distances have been simulated by the covalo-electrostatic model. - Graphical abstract: Crystallographic and FTIR data for Ln[Fe(CN){sub 6}].4H{sub 2}O enable the changes in Ln-O, Ln-N, C{identical_to}N and Fe-C distances to be determined and modeled across the lanthanide series.

  13. The SAURON project - XX. The Spitzer [3.6] - [4.5] colour in early-type galaxies: colours, colour gradients and inverted scaling relations

    NASA Astrophysics Data System (ADS)

    Peletier, Reynier F.; Kutdemir, Elif; van der Wolk, Guido; Falcón-Barroso, Jesús; Bacon, Roland; Bureau, Martin; Cappellari, Michele; Davies, Roger L.; de Zeeuw, P. Tim; Emsellem, Eric; Krajnović, Davor; Kuntschner, Harald; McDermid, Richard M.; Sarzi, Marc; Scott, Nicholas; Shapiro, Kristen L.; van den Bosch, Remco C. E.; van de Ven, Glenn

    2012-01-01

    We investigate the [3.6]-[4.5] Spitzer-IRAC colour behaviour of the early-type galaxies of the SAURON survey, a representative sample of 48 nearby ellipticals and lenticulars. We investigate how this colour, which is unaffected by dust extinction, can be used to constrain the stellar populations in these galaxies. We find a tight relation between the [3.6]-[4.5] colour and effective velocity dispersion, a good mass indicator in early-type galaxies: ([3.6]-[4.5])e = (-0.109 ? 0.007)?+ (0.154 ? 0.016). Contrary to other colours in the optical and near-infrared, we find that the colours become bluer for larger galaxies. The relations are tighter when using the colour inside re (scatter 0.013 mag), rather than the much smaller re/8 aperture (scatter 0.023 mag), due to the presence of young populations in the central regions. We also obtain strong correlations between the [3.6]-[4.5] colour and three strong absorption lines (H?, Mgb and Fe 5015). Comparing our data with the models of Marigo et al., which show that more metal rich galaxies are bluer, we can explain our results in a way consistent with results from the optical, by stating that larger galaxies are more metal rich. The blueing is caused by a strong CO absorption band, whose line strength increases strongly with decreasing temperature and which covers a considerable fraction of the 4.5-?m filter. In galaxies that contain a compact radio source, the [3.6]-[4.5] colour is generally slightly redder (by 0.015 ? 0.007 mag using the re/8 aperture) than in the other galaxies, indicating small amounts of either hot dust, non-thermal emission, or young stars near the centre. We find that the large majority of the galaxies show redder colours with increasing radius. Removing the regions with evidence for young stellar populations (from the H? absorption line) and interpreting the colour gradients as metallicity gradients, we find that our galaxies are more metal poor going outwards. The radial [3.6]-[4.5] gradients

  14. Construction of Azabicyclo[6.4.0]dodecatrienes Based on Rhodium(I)-Catalyzed Intramolecular [6+2] Cycloaddition between Azetidine, Allene, and Alkynes.

    PubMed

    Yasuda, Shigeo; Yokosawa, Haruna; Mukai, Chisato

    2016-01-01

    Treatment of the allenylazetidine-alkynes with a catalytic amount of [RhCl(CO)dppp]2 (dppp: 1,3-bis(diphenylphosphino)propane) effected the intramolecular hetero-[6+2]-type ring-closing reaction via the C-C bond cleavage of the azetidine ring to produce azabicyclo[6.4.0]dodecatriene derivatives in good to excellent yields. The formation of the oxa analogue could also be achieved. PMID:27373635

  15. Charm photoproduction at 20 GeV including preliminary lifetime results with improved optical resolution

    SciTech Connect

    Colley, D.C.; Brick, D.; Bacon, T.C.; Cohn, H.O.; Franek, B.; Armenteros, R.; Abe, K.; Kafka, T.; Bingham, H.H.; Brau, J.E.

    1984-07-01

    Sixty five charm events have been observed in an exposure, during 1983, of the SLAC Hybrid Facility (SHF) to a backward scattered laser beam. Preliminary results for the charmed meson lifetimes have been obtained based on 19 neutral and 22 charged decays thereby doubling our earlier data. These lifetimes are consistent with our published results and the two data samples have been combined. From the resulting 42 neutral, 45 charged and 13 topologically ambiguous decays the charmed meson lifetimes are measured to be tau/sub D/sup 0// = (6.4/sub -0.9//sup +1.1/ +- 0.5) x 10/sup -13/s and tau/sub D/sup + -// = (8.2/sub -1.1//sup +1.3/ +- 0.6) x 10/sup -13/s and their ratio tau/sub D//sup + -///tau/sub D/sup 0// = 1.3/sub -0.3/sup +0.5/. The inclusive charm cross-section at a photon energy of 20 GeV has been measured to be 60 +- 8 +- 21) nb.

  16. Enhancement of the catalytic activity of ferulic acid decarboxylase from Enterobacter sp. Px6-4 through random and site-directed mutagenesis.

    PubMed

    Lee, Hyunji; Park, Jiyoung; Jung, Chaewon; Han, Dongfei; Seo, Jiyoung; Ahn, Joong-Hoon; Chong, Youhoon; Hur, Hor-Gil

    2015-11-01

    The enzyme ferulic acid decarboxylase (FADase) from Enterobacter sp. Px6-4 catalyzes the decarboxylation reaction of lignin monomers and phenolic compounds such as p-coumaric acid, caffeic acid, and ferulic acid into their corresponding 4-vinyl derivatives, that is, 4-vinylphenol, 4-vinylcatechol, and 4-vinylguaiacol, respectively. Among various ferulic acid decarboxylase enzymes, we chose the FADase from Enterobacter sp. Px6-4, whose crystal structure is known, and produced mutants to enhance its catalytic activity by random and site-directed mutagenesis. After three rounds of sequential mutations, FADase(F95L/D112N/V151I) showed approximately 34-fold higher catalytic activity than wild-type for the production of 4-vinylguaiacol from ferulic acid. Docking analyses suggested that the increased activity of FADase(F95L/D112N/V151I) could be due to formation of compact active site compared with that of the wild-type FADase. Considering the amount of phenolic compounds such as lignin monomers in the biomass components, successfully bioengineered FADase(F95L/D112N/V151I) from Enterobacter sp. Px6-4 could provide an ecofriendly biocatalytic tool for producing diverse styrene derivatives from biomass. PMID:26059194

  17. Photoaffinity derivative of colchicine: 6'-(4'-azido-2'-nitrophenylamino)hexanoyldeacetylcolchicine. Photolabeling and location of the colchicine-binding site on the alpha-subunit of tubulin

    SciTech Connect

    Williams, R.F.; Mumford, C.L.; Williams, G.A.; Floyd, L.J.; Aivaliotis, M.J.; Martinez, R.A.; Robinson, A.K.; Barnes, L.D.

    1985-11-05

    A photoaffinity analog of colchicine, 6-(4'-azido-2'-nitrophenylamino)hexanoyldeacetylcolchicine, was synthesized by reacting deacetylcolchicine or (TH)deacetylcochicine with N-succinimidyl-6-(4'-azido-2'-nitrophenylamino)hexanoate. Homogeneity of the photoaffinity analog was established by thin-layer chromatography and high-pressure liquid chromatography. The structure of the photoaffinity analog was determined by H and TC NMR, infrared and ultraviolet-visible spectroscopies, and elemental analysis. Binding of 6-(4'-azido-2'-nitrophenylamino)hexanoyldeacetylcolchicine to bovine renal tubulin was measured by competition with (TH)colchicine. The value of the apparent Ki for the photoaffinity analog was 0.28 microM in the concentration range of 0.8-1.2 microM of the analog. A value of 0.50 microM for the apparent Kd was measured by the direct binding of the tritiated photoaffinity analog to tubulin. The analog is slightly more potent an inhibitor of microtubule formation than colchicine. The photoaffinity analog reacted with renal tubulin upon irradiation with a mercury lamp equipped with a 420-nm cutoff filter. Spectral and radiochemical analyses of the tubulin after photolysis and dialysis have demonstrated a stoichiometric incorporation of the photoaffinity analog in the alpha-subunit of the tubulin. Covalent labeling of tubulin with the photoaffinity analog decreases the extent of (TH)colchicine binding by more than 90%.

  18. Theoretical study of photoproduction of an η'N bound state on a deuteron target with forward proton emission

    NASA Astrophysics Data System (ADS)

    Sekihara, Takayasu; Sakai, Shuntaro; Jido, Daisuke

    2016-08-01

    Possibilities of observing a signal of an η'n bound state are investigated by considering photoproductions of the η and η' mesons on a deuteron target with forward proton emission. For this purpose, we take the η'n interaction from the linear σ model with a coupling to η n , in which an s -wave η'n bound state can be dynamically generated, and we fix the γ p →η p and η'p scattering amplitudes so as to reproduce the experimental cross sections with forward proton emission. By using these γ p →η(')p and η(')n →η(')n amplitudes, we calculate cross sections of the γ d →η n p and η'n p reactions with forward proton emission in single and η(')-exchange double-scattering processes. As a result, we find that the signal of the η'n bound state can be seen below the η'n threshold in the η n invariant mass spectrum of the γ d →η n p reaction and is comparable with the contribution from the quasifree η' production above the η'n threshold. We also discuss the behavior of the signal of the η'n bound state in several experimental conditions and model parameters.

  19. Polarization components in π0 photoproduction at photon energies up to 5.6 GeV

    SciTech Connect

    Luo, W.; Brash, E. J.; Gilman, R.; Jones, M. K.; Meziane, M.; Pentchev, L.; Perdrisat, C. F; Puckett, A. J.R.; Punjabi, V.; Wesselmann, F. R.; Marsh, A.; Matulenko, Y.; Maxwell, J.; Meekins, D.; Melnik, Y.; Miller, J.; Mkrtchyan, A.; Mkrtchyan, H.; Moffit, B.; Moreno, O.; Mulholland, J.; Narayan, A.; Nuruzzaman, .; Nedev, S.; Piasetzky, E.; Pierce, W.; Piskunov, N. M.; Prok, Y.; Ransome, R. D.; Razin, D. S.; Reimer, P. E.; Reinhold, J.; Rondon, O.; Shabestari, M.; Shahinyan, A.; Shestermanov, K.; Sirca, S.; Sitnik, I.; Smykov, L.; Smith, G.; Solovyev, L.; Solvignon, P.; Strakovsky, I. I; Subedi, R.; Suleiman, R.; Tomasi-Gustafsson, E.; Vasiliev, A.; Veilleux, M.; Wood, S.; Ye, Z.; Zanevsky, Y.; Zhang, X.; Zhang, Y.; Zheng, X.; Zhu, L.; Ahmidouch, A.; Albayrak, I.; Aniol, K. A.; Arrington, J.; Asaturyan, A.; Ates, O.; Baghdasaryan, H.; Benmokhtar, F.; Bertozzi, W.; Bimbot, L.; Bosted, P.; Boeglin, W.; Butuceanu, C.; Carter, P.; Chernenko, S.; Christy, M. E.; Commisso, M.; Cornejo, J. C.; Covrig, S.; Danagoulian, S.; Daniel, A.; Davidenko, A.; Day, D.; Dhamija, S.; Dutta, D.; Ent, R.; Frullani, S.; Fenker, H.; Frlez, E.; Garibaldi, F.; Gaskell, D.; Gilad, S.; Goncharenko, Y.; Hafidi, K.; Hamilton, D.; Higinbotham, D. W.; Hinton, W.; Horn, T.; Hu, B.; Huang, J.; Huber, G. M.; Jensen, E.; Kang, H.; Keppel, C.; Khandaker, M.; King, P.; Kirillov, D.; Kohl, M.; Kravtsov, V.; Kumbartzki, G.; Li, Y.; Mamyan, V.; Margaziotis, D. J.; Markowitz, P.

    2012-05-31

    We present new data for the polarization observables of the final state proton in the 1H(→ γ, → p)π0 reaction. These data can be used to test predictions based on hadron helicity conservation (HHC) and perturbative QCD (pQCD). These data have both small statistical and systematic uncertainties, and were obtained with beam energies between 1.8 and 5.6 GeV and for π0 scattering angles larger than 75{sup o} in center-of-mass (c.m.) frame. The data extend the polarization measurements data base for neutral pion photoproduction up to Eγ = 5.6 GeV. The results show non-zero induced polarization above the resonance region. The polarization transfer components vary rapidly with the photon energy and π0 scattering angle in the center-of-mass frame. This indicates that HHC does not hold and that the pQCD limit is still not reached in the energy regime of this experiment.

  20. Polarization components in π0 photoproduction at photon energies up to 5.6 GeV

    DOE PAGESBeta

    Luo, W.; Brash, E. J.; Gilman, R.; Jones, M. K.; Meziane, M.; Pentchev, L.; Perdrisat, C. F; Puckett, A. J.R.; Punjabi, V.; Wesselmann, F. R.; et al

    2012-05-31

    We present new data for the polarization observables of the final state proton in the 1H(→ γ, → p)π0 reaction. These data can be used to test predictions based on hadron helicity conservation (HHC) and perturbative QCD (pQCD). These data have both small statistical and systematic uncertainties, and were obtained with beam energies between 1.8 and 5.6 GeV and for π0 scattering angles larger than 75{sup o} in center-of-mass (c.m.) frame. The data extend the polarization measurements data base for neutral pion photoproduction up to Eγ = 5.6 GeV. The results show non-zero induced polarization above the resonance region. Themore » polarization transfer components vary rapidly with the photon energy and π0 scattering angle in the center-of-mass frame. This indicates that HHC does not hold and that the pQCD limit is still not reached in the energy regime of this experiment.« less

  1. Photoproduction of lepton pairs in proton-nucleus and nucleus-nucleus collisions at RHIC and LHC energies

    SciTech Connect

    Moreira, B. D.; Goncalves, V. P.; De Santana Amaral, J. T.

    2013-03-25

    In this contribution we study coherent interactions as a probe of the nonlinear effects in the Quantum Electrodynamics (QED). In particular, we study the multiphoton effects in the production of leptons pairs for proton-nucleus and nucleus-nucleus collisions for heavy nuclei. In the proton-nucleus we assume the ultrarelativistic proton as a source of photons and estimate the photoproduction of lepton pairs on nuclei at RHIC and LHC energies considering the multiphoton effects associated to multiple rescattering of the projectile photon on the proton of the nucleus. In nucleus - nucleus colllisions we consider the two nuclei as a source of photons. As each scattering contributes with a factor {alpha}Z to the cross section, this contribution must be taken into account for heavy nuclei. We consider the Coulomb corrections to calculate themultiple scatterings and estimate the total cross section for muon and tau pair production in proton-nucleus and nucleus-nucleus collisions at RHIC and LHC energies.

  2. Two-Photon Absorption of Bacteriorhodopsin: Formation of a Red-Shifted Thermally Stable Photoproduct F620

    PubMed Central

    Fischer, Thorsten; Hampp, Norbert A.

    2005-01-01

    By means of high-intensity 532 nm laser pulses, a photochemical conversion of the initial B570 state of bacteriorhodopsin (BR) to a stable photoproduct absorbing maximally at ≈620 nm in BR suspensions and at ≈610 nm in BR films is induced. This state, which we named F620, is photochemically further converted to a group of three products with maximal absorptions in the wavelength range from 340 nm to 380 nm, which show identical spectral properties to the so-called P360 state reported in the literature. The photoconversion from B570 to F620 is most likely a resonant two-photon absorption induced step. The formation of F620 and P360 leads to a distinguished photo-induced permanent optical anisotropy in BR films. The spectral dependence of the photo-induced anisotropy and the anisotropy orientations at the educt (B570) and product (F620) wavelengths are strong indicators that F620 is formed in a direct photochemical step from B570. The chemical nature of the P360 products probably is that of a retro-retinal containing BR, but the structural characteristics of the F620 state are still unclear. The photo-induced permanent anisotropy induced by short laser pulses in BR films helps to better understand the photochemical pathways related to this transition, and it is interesting in view of potential applications as this feature is the molecular basis for permanent optical data storage using BR films. PMID:15894635

  3. Rapidity and momentum transfer distributions of coherent J/ψ photoproduction in ultraperipheral pPb collisions at the LHC

    NASA Astrophysics Data System (ADS)

    Guzey, V.; Zhalov, M.

    2014-02-01

    Based on accurate calculations of the flux of equivalent photons of the proton and heavy nuclei and the pQCD framework for the gluon distribution in the proton and nuclei, we analyze the rapidity and momentum transfer distributions of coherent J/ψ photoproduction in ultraperipheral proton-Pb collisions at the LHC. We demonstrate that unlike the case of proton-proton UPCs marred by certain theoretical uncertainties and experimental limitations, after a cut excluding the region of small momentum transfers, ultraperipheral proton-Pb collisions offer a clean way to study the gluon distribution in the proton down to x ≈ 10-5. Our analysis of the momentum transfer distributions shows that an interplay of J/ψ production by low-energy photons on the nucleus and by high-energy photons on the proton in proton-Pb UPCs can result in some excess of events at small p t in a definite region of the rapidity y.

  4. Hydrogen photoproduction by nutrient-deprived Chlamydomonas reinhardtii cells immobilized within thin alginate films under aerobic and anaerobic conditions.

    PubMed

    Kosourov, Sergey N; Seibert, Michael

    2009-01-01

    A new technique for immobilizing H2-photoproducing green algae within a thin (<400 microm) alginate film has been developed. Alginate films with entrapped sulfur/phosphorus-deprived Chlamydomonas reinhardtii, strain cc124, cells demonstrate (a) higher cell density (up to 2,000 microg Chl mL(-1) of matrix), (b) kinetics of H2 photoproduction similar to sulfur-deprived suspension cultures, (c) higher specific rates (up to 12.5 micromol mg(-1) Chl h(-1)) of H2 evolution, (d) light conversion efficiencies to H2 of over 1% and (e) unexpectedly high resistance of the H2-photoproducing system to inactivation by atmospheric O2. The algal cells, entrapped in alginate and then placed in vials containing 21% O2 in the headspace, evolved up to 67% of the H2 gas produced under anaerobic conditions. The results indicate that the lower susceptibility of the immobilized algal H2-producing system to inactivation by O2 depends on two factors: (a) the presence of acetate in the medium, which supports higher rates of respiration and (b) the capability of the alginate polymer itself to effectively separate the entrapped cells from O2 in the liquid and headspace and restrict O2 diffusion into the matrix. The strategy presented for immobilizing algal cells within thin polymeric matrices shows the potential for scale-up and possible future applications. PMID:18823051

  5. Polarization components in π0 photoproduction at photon energies up to 5.6 GeV.

    PubMed

    Luo, W; Brash, E J; Gilman, R; Jones, M K; Meziane, M; Pentchev, L; Perdrisat, C F; Puckett, A J R; Punjabi, V; Wesselmann, F R; Ahmidouch, A; Albayrak, I; Aniol, K A; Arrington, J; Asaturyan, A; Ates, O; Baghdasaryan, H; Benmokhtar, F; Bertozzi, W; Bimbot, L; Bosted, P; Boeglin, W; Butuceanu, C; Carter, P; Chernenko, S; Christy, M E; Commisso, M; Cornejo, J C; Covrig, S; Danagoulian, S; Daniel, A; Davidenko, A; Day, D; Dhamija, S; Dutta, D; Ent, R; Frullani, S; Fenker, H; Frlez, E; Garibaldi, F; Gaskell, D; Gilad, S; Goncharenko, Y; Hafidi, K; Hamilton, D; Higinbotham, D W; Hinton, W; Horn, T; Hu, B; Huang, J; Huber, G M; Jensen, E; Kang, H; Keppel, C; Khandaker, M; King, P; Kirillov, D; Kohl, M; Kravtsov, V; Kumbartzki, G; Li, Y; Mamyan, V; Margaziotis, D J; Markowitz, P; Marsh, A; Matulenko, Y; Maxwell, J; Mbianda, G; Meekins, D; Melnik, Y; Miller, J; Mkrtchyan, A; Mkrtchyan, H; Moffit, B; Moreno, O; Mulholland, J; Narayan, A; Nuruzzaman; Nedev, S; Piasetzky, E; Pierce, W; Piskunov, N M; Prok, Y; Ransome, R D; Razin, D S; Reimer, P E; Reinhold, J; Rondon, O; Shabestari, M; Shahinyan, A; Shestermanov, K; Širca, S; Sitnik, I; Smykov, L; Smith, G; Solovyev, L; Solvignon, P; Strakovsky, I I; Subedi, R; Suleiman, R; Tomasi-Gustafsson, E; Vasiliev, A; Veilleux, M; Wood, S; Ye, Z; Zanevsky, Y; Zhang, X; Zhang, Y; Zheng, X; Zhu, L

    2012-06-01

    We present new data for the polarization observables of the final state proton in the (1)H(γ,p)π(0) reaction. These data can be used to test predictions based on hadron helicity conservation and perturbative QCD. These data have both small statistical and systematic uncertainties and were obtained with beam energies between 1.8 and 5.6 GeV and for π(0) scattering angles larger than 75° in the center-of-mass frame. The data extend the polarization measurements database for neutral pion photoproduction up to E(γ)=5.6 GeV. The results show a nonzero induced polarization above the resonance region. The polarization transfer components vary rapidly with the photon energy and π(0) scattering angle in the center-of-mass frame. This indicates that hadron helicity conservation does not hold and that the perturbative QCD limit is still not reached in the energy regime of this experiment. PMID:23180491

  6. Seasonal and spatial variabilities in the water chemistry of prairie pothole wetlands influence the photoproduction of reactive intermediates.

    PubMed

    McCabe, Andrew J; Arnold, William A

    2016-07-01

    The hydrology and water chemistry of prairie pothole wetlands vary spatially and temporally, on annual and decadal timescales. Pesticide contamination of wetlands arising from agricultural activities is a foremost concern. Photochemical reactions are important in the natural attenuation of pesticides and may be important in limiting ecological and human exposure. Little is known, however, about the variable influence of wetland water chemistry on indirect photochemistry. In this study, seasonal water samples were collected from seven sites throughout the prairie pothole region over three years to understand the spatiotemporal dynamics of reactive intermediate photoproduction. Samples were classified by the season in which they were collected (spring, summer, or fall) and the typical hydroperiod of the wetland surface water (temporary or semi-permanent). Under photostable conditions, steady-state concentrations and apparent quantum yields or quantum yield coefficients were measured for triplet excited states of dissolved organic matter, singlet oxygen, hydroxyl radical, and carbonate radical under simulated sunlight. Steady-state concentrations and quantum yields increased on average by 15% and 40% from spring to fall, respectively. Temporary wetlands had 40% higher steady-state concentrations of reactive intermediates than semi-permanent wetlands, but 50% lower quantum yields. Computed quantum yields for reactive intermediate formation were used to predict the indirect photochemical half-lives of seven pesticides in average temporary and semi-permanent prairie pothole wetlands. As a first approximation, the predictions agree to within two orders of magnitude of previously reported half-lives. PMID:27174849

  7. Coherent π{sup 0}-photoproduction on the deuteron near the η-production threshold including polarization observables

    SciTech Connect

    Darwish, Eed M.; Al-Thoyaib, Suleiman S.

    2014-12-15

    Coherent π{sup 0}-photoproduction on the deuteron including polarization observables is studied in the energy region near the η-production threshold at backward center-of-mass angles of the outgoing pion. This work is motivated by the measurements of the CLAS Collaboration at Jefferson Lab, where a cusp-like structure in the energy dependence of the differential cross section has been observed at extremely backward pion angles. The present approach is based on the impulse approximation and first-order rescattering diagrams with intermediate production of both π- and η-mesons. Numerical results for unpolarized cross sections, the linear photon asymmetry (Σ), the vector (T{sub 11}) and tensor (T{sub 2M}, M=0, 1, 2) deuteron target asymmetries, and the double polarization E-asymmetry are predicted and compared with available experimental data and other theoretical models. The effect of first-order rescattering is found to be much larger in spin asymmetries than in the unpolarized cross sections. It reaches on average about 40% in the tensor target and E asymmetries. Compared to the experimental data from CLAS Collaboration, sizable discrepancies are found. This is not the case for the linear photon asymmetry, for which a better comparison with the data from YerPhI Collaboration is obtained.

  8. High efficiency antireflection coating in MWIR region (3.6-4.9 μm) simultaneously effective for Germanium and Silicon optics

    NASA Astrophysics Data System (ADS)

    Bhatt, Meenakshi; Nautiyal, B. B.; Bandyopadhyay, P. K.

    2010-01-01

    Antireflection coatings have critical importance in thermal imaging system working in MWIR region (3-5 μm) since optics of high refractive index materials are used. Germanium (Ge) and Silicon (Si) optics are used extensively in the MWIR thermal systems. In this paper a study has been carried out on the design and fabrication of multi-substrate antireflection coating effective for Germanium and Silicon optics in MWIR (3.6-4.9 μm) region. The wave band 3.6-4.9 μm is chosen for the reported work because detector system used in MWIR region has a band selection filter effective in the same wavelength region and atmospheric transmission window in MWIR region is effective in 3-5 μm spectral band. Comprehensive search method was used to design the multilayer stack on the substrate. The coating materials used in the design were Germanium (Ge), Hafnium oxide (HfO 2) and Y-Ba-Fluoride (IR-F625). The fabrication of coating was made in a coating plant fitted with Cryo pump system and residual gas analyzer (RGA). The evaporation was carried out at high vacuum (2-6 × 10 -6 mbar) with the help of electron beam gun system and layer thicknesses were measured with crystal monitor. The result achieved for the antireflection coating was 98.5% average transmission in 3.6-4.9 μm band for Germanium and Silicon optics. This work will be helpful in reducing the plant operation time, material and power consumption, as two different kinds of optics are simultaneously coated in a single coating cycle.

  9. The Odd Gold Isotopes and the UB(6) × UF (4) Bose-Fermi Symmetry and the U(6/4) Supersymmetry

    NASA Astrophysics Data System (ADS)

    Jolie, J.; Thomas, T.; Regis, J.-M.; Bernards, Ch.; Heinze, S.

    2013-03-01

    We have performed experiments on 193,195Au at the 10 MV Tandem accelerator in Cologne using the HORUS and Double ORANGE spectrometers and fast LaBr3(Ce) scintillators to perform γ, - γ, γ - e- and e- - e- coincidences. The level schemes were considerably extended and absolute transition rates were obtained. This allowed a detailed comparison with the predictions of the U(6/4) supersymmetry for the positive parity states in 193Au. We also present a systematic and almost parameter free description of these states in 189-199Au within the Bose-Fermi symmetry UB (6) × UF(4).

  10. Negative superhelicity promotes ATP-dependent binding of yeast RAD3 protein to ultraviolet-damaged DNA.

    PubMed

    Sung, P; Watkins, J F; Prakash, L; Prakash, S

    1994-03-18

    The RAD3 gene of Saccharomyces cerevisiae is required for excision repair of UV-damaged DNA and is essential for cell viability. Remarkable homology exists between RAD3 and the human excision repair gene XPD, whose mutational inactivation underlies the cancer-prone disorder in xeroderma pigmentosum group D patients. Our previous work demonstrated that RAD3-encoded protein contains a DNA helicase activity. Here, we show that RAD3 binds preferentially to UV-damaged DNA over nondamaged DNA. Removal of pyrimidine dimers from damaged DNA by enzymatic photoreactivation does not affect binding, suggesting an affinity of RAD3 for pyrimidine (6-4) pyrimidone photoproducts. Damage-specific binding by RAD3 is strongly dependent on ATP and on the degree of negative superhelicity in DNA. The requirement of superhelicity in damage binding may target RAD3 to regions of DNA undergoing transcription, resulting in the preferential repair of these regions. The rad3 Arg-48 mutant protein, which lacks the DNA helicase activity, also binds UV-damaged DNA preferentially, indicating that DNA helicase and damage binding are two distinct and separable functional entities in RAD3. PMID:8132553

  11. Yeast DNA-repair gene RAD14 encodes a zinc metalloprotein with affinity for ultraviolet-damaged DNA

    SciTech Connect

    Guzder, S.N.; Sung, P.; Prakash, S. ); Prakash, L. )

    1993-06-15

    Xeroderma pigmentosum (XP) patients suffer from a high incidence of skin cancers due to a defect in excision repair of UV light-damaged DNA. Of the seven XP complementation groups, A--G, group A represents a severe and frequent form of the disease. The Saccharomyces cerevisiae RAD14 gene is a homolog of the XP-A correcting (XPAC) gene. Like XP-A cells, rad14-null mutants are defective in the incision step of excision repair of UV-damaged DNA. The authors have purified RAD14 protein to homogeneity from extract of a yeast strain genetically tailored to overexpress RAD14. As determined by atomic emission spectroscopy, RAD14 contains one zinc atom. They also show in vitro that RAD14 binds zinc but does not bind other divalent metal ions. In DNA mobility-shift assays, RAD14 binds specifically to UV-damaged DNA. Removal of cyclobutane pyrimidine dimers from damaged DNA by enzymatic photoreactivation has no effect on binding, strongly suggesting that RAD14 recognizes pyrimidine(6-4)pyrimidone photoproduct sites. These findings indicate that RAD14 functions in damage recognition during excision repair. 37 refs., 4 figs.

  12. Characterization of Red/Green Cyanobacteriochrome NpR6012g4 by Solution Nuclear Magnetic Resonance Spectroscopy: A Hydrophobic Pocket for the C15-E,anti Chromophore in the Photoproduct.

    PubMed

    Rockwell, Nathan C; Martin, Shelley S; Lim, Sunghyuk; Lagarias, J Clark; Ames, James B

    2015-06-23

    Cyanobacteriochromes (CBCRs) are cyanobacterial photosensory proteins distantly related to phytochromes. Like phytochromes, CBCRs reversibly photoconvert between a dark-stable state and a photoproduct via photoisomerization of the 15,16-double bond of their linear tetrapyrrole (bilin) chromophores. CBCRs provide cyanobacteria with complete coverage of the visible spectrum and near-ultraviolet region. One CBCR subfamily, the canonical red/green CBCRs typified by AnPixJg2 and NpR6012g4, can function as sensors of light color or intensity because of their great variation in photoproduct stability. The mechanistic basis for detection of green light by the photoproduct state in this subfamily has proven to be a challenging research topic, with competing hydration and trapped-twist models proposed. Here, we use ¹³C-edited and ¹⁵N-edited ¹H-¹H NOESY solution nuclear magnetic resonance spectroscopy to probe changes in chromophore configuration and protein-chromophore interactions in the NpR6012g4 photocycle. Our results confirm a C15-Z,anti configuration for the red-absorbing dark state and reveal a C15-E,anti configuration for the green-absorbing photoproduct. The photoactive chromophore D-ring is located in a hydrophobic environment in the photoproduct, surrounded by both aliphatic and aromatic residues. Characterization of variant proteins demonstrates that no aliphatic residue is essential for photoproduct tuning. Taken together, our results support the trapped-twist model over the hydration model for the red/green photocycle of NpR6012g4. PMID:25989712

  13. Origin of anomalous electronic circular dichroism spectrum of RuPt2(tppz)2Cl2(PF6)4 in acetonitrile.

    PubMed

    Yu, Hua-Gen

    2014-07-24

    We report a theoretical study of the structures, energetics, and electronic spectra of the Pt(II)/Ru(II) mixed-metal complex RuPt2(tppz)2Cl2(PF6)4 (tppz = 2,3,5,6-tetra(2-pyridyl)pyrazine) in acetonitrile. The hybrid B3LYP density functional theory and its TDDFT methods were used with a complete basis set (CBS) extrapolation scheme and a conductor polarizable continuum model (C-PCM) for solvation effects. Results showed that the trinuclear complex has four types of stable conformers and/or enantiomers. They are separated by high barriers owing to the repulsive H/H geometrical constraints in tppz. A strong entropy effect was found for the dissociation of RuPt2(tppz)2Cl2(PF6)n in acetonitrile. The UV-visible and emission spectra of the complex were also simulated. They are in good agreement with experiments. In this work we have largely focused on exploring the origin of anomalous electronic circular dichroism (ECD) spectra of the RuPt2(tppz)2Cl2(PF6)4 complex in acetonitrile. As a result, a new mechanism has been proposed together with a clear illustration by using a physical model. PMID:25026322

  14. Faster DNA Repair of Ultraviolet-Induced Cyclobutane Pyrimidine Dimers and Lower Sensitivity to Apoptosis in Human Corneal Epithelial Cells than in Epidermal Keratinocytes.

    PubMed

    Mallet, Justin D; Dorr, Marie M; Drigeard Desgarnier, Marie-Catherine; Bastien, Nathalie; Gendron, Sébastien P; Rochette, Patrick J

    2016-01-01

    Absorption of UV rays by DNA generates the formation of mutagenic cyclobutane pyrimidine dimers (CPD) and pyrimidine (6-4) pyrimidone photoproducts (6-4PP). These damages are the major cause of skin cancer because in turn, they can lead to signature UV mutations. The eye is exposed to UV light, but the cornea is orders of magnitude less prone to UV-induced cancer. In an attempt to shed light on this paradox, we compared cells of the corneal epithelium and the epidermis for UVB-induced DNA damage frequency, repair and cell death sensitivity. We found similar CPD levels but a 4-time faster UVB-induced CPD, but not 6-4PP, repair and lower UV-induced apoptosis sensitivity in corneal epithelial cells than epidermal. We then investigated levels of DDB2, a UV-induced DNA damage recognition protein mostly impacting CPD repair, XPC, essential for the repair of both CPD and 6-4PP and p53 a protein upstream of the genotoxic stress response. We found more DDB2, XPC and p53 in corneal epithelial cells than in epidermal cells. According to our results analyzing the protein stability of DDB2 and XPC, the higher level of DDB2 and XPC in corneal epithelial cells is most likely due to an increased stability of the protein. Taken together, our results show that corneal epithelial cells have a better efficiency to repair UV-induced mutagenic CPD. On the other hand, they are less prone to UV-induced apoptosis, which could be related to the fact that since the repair is more efficient in the HCEC, the need to eliminate highly damaged cells by apoptosis is reduced. PMID:27611318

  15. Study of Double Delta Photoproduction on the Deuteron in the Energy Region of Eγ = 0.65-1.1 GeV

    NASA Astrophysics Data System (ADS)

    Yamamoto, Fumiya; Beckford, Brian; Fujibayashi, Takeji; Fujii, Takao; Fujii, Yu; Futatsukawa, Kenta; Gogami, Toshiyuki; Han, Yun-Cheng; Hashimoto, Osamu; Hirose, Kentaro; Hosomi, Kenji; Honda, Ryotaro; Iguchi, Alan; Ishikawa, Takatsugu; Kanda, Hiroki; Kaneta, Masashi; Kaneko, Yusuke; Kawasaki, Taito; Kimura, Chigusa; Kiyokawa, Shogo; Koike, Takeshi; Maeda, Kazushige; Maruyama, Nayuta; Matsubara, Masao; Miwa, Koji; Miyagi, Yohei; Nagao, Sho; Nakamura, Satoshi N.; Okuyama, Akira; Shimizu, Hajime; Suzuki, Kotaku; Tamae, Tadaaki; Tamura, Hirokazu; Tsukada, Kyo; Terada, Nobu; Ukai, Mifuyu; Wang, Tie-Shan; Yamazaki, Hirohito

    We have studied π+ π- photoproduction on the deuteron in an energy region of Eγ = 0.65-1.1 GeV at Research Center for Electron Photon Science (ELPH), Tohoku University. The charged particles were detected using Neutral Kaon Spectrometer 2 (NKS2). The invariant mass distributions reconstructed from the π+ p and π-n combinations suggested the double Delta excitations in the intermediate state. There distributions were compared with simulations taking into account the Δ+ +Δ- → π+π-pn, the Δ+Δ0 → π+π-pn, and the 4 body phase space.

  16. Evidence of subnucleonic degrees of freedom in J /ψ photoproduction in ultraperipheral collisions at energies available at the CERN Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Andrade-II, E.; González, I.; Deppman, A.; Bertulani, C. A.

    2015-12-01

    We present calculations for the incoherent photoproduction of J /ψ vector mesons in ultraperipheral heavy ion collisions (UPCs) in terms of hadronic interactions. This study was carried out using the recently developed Monte Carlo model CRISP extended to include UPCs at energies available at the CERN Large Hadron Collider. A careful study of rescattering and destruction of the J /ψ particles is presented for Pb + Pb collisions at √{sN N}=2.76 TeV. We have also compared our method to Au + Au collisions at √{sN N}=200 GeV measured at the BNL Relativistic Heavy Ion Collider.

  17. Measurements of exclusive photoproduction processes at large values of t and u from 4 to 7.5 GeV

    USGS Publications Warehouse

    Anderson, R.L.; Gustavson, D.B.; Ritson, D.M.; Weitsch, G.A.; Halpern, H.J.; Prepost, R.; Tompkins, D.H.; Wiser, D.E.

    1976-01-01

    Exclusive photoproduction cross sections have been measured for the processes p+n, p0p, p-++, p0p, pK+, and pK+0 at large t and u values at several energies for each process between 4 and 7.5 GeV. These measurements taken together with past data taken at small values of t and u provide complete angular distributions. The data show the usual small t and u peaks and a central region in which the cross section decreases approximately as s-7. The results are discussed within the context of parton or constituent models. ?? 1976 The American Physical Society.

  18. eta-prime photoproduction on the proton for photon energies from 1.527 to 2.227 GeV

    SciTech Connect

    M. Dugger; J. P. Ball; P. Collins; E. Pasyuk; B. G. Ritchie

    2006-01-13

    Differential cross sections for the reaction gamma p {yields} eta-prime p have been measured with the CLAS spectrometer and a tagged photon beam with energies from 1.527 to 2.227 GeV. The results reported here possess much greater accuracy than previous measurements. Analyses of these data indicate for the first time the coupling of the eta prime N channel to both the S{sub 11}(1535) and P{sub 11}(1710) resonances, known to couple strongly to the eta N channel in photoproduction on the proton, and the importance of j=3/2 resonances in the process.

  19. Inclusive photoproduction of bottom quarks for low and medium pT in the general-mass variable-flavour-number scheme

    NASA Astrophysics Data System (ADS)

    Kramer, G.; Spiesberger, H.

    2016-02-01

    We present predictions for b-quark production in photoproduction and compare with experimental data from HERA. Our theoretical predictions are obtained at next-to-leading-order in the general-mass variable-flavor-number scheme, an approach which takes into account the finite mass of the b quarks. We use realistic evolved nonperturbative fragmentation functions obtained from fits to e+e- data. We find in general good agreement of data with both the GM-VFNS and the FFNS calculations, while the more precise ZEUS data seem to prefer the GM-VFNS predictions.

  20. (1)H, (13)C, and (15)N chemical shift assignments of cyanobacteriochrome NpR6012g4 in the green-absorbing photoproduct state.

    PubMed

    Lim, Sunghyuk; Yu, Qinhong; Rockwell, Nathan C; Martin, Shelley S; Lagarias, J Clark; Ames, James B

    2016-04-01

    Cyanobacteriochromes (CBCRs) are cyanobacterial photosensory proteins with a tetrapyrrole (bilin) chromophore that belong to the phytochrome superfamily. Like phytochromes, CBCRs photoconvert between two photostates with distinct spectral properties. NpR6012g4 from Nostoc punctiforme is a model system for widespread CBCRs with conserved red/green photocycles. Atomic-level structural information for the photoproduct state in this subfamily is not known. Here, we report NMR backbone chemical shift assignments of the light-activated state of NpR6012g4 (BMRB no. 26577) as a first step toward determining its atomic resolution structure. PMID:26537963

  1. Hydrogen Photoproduction by Nutrient-Deprived Chalamydomonas reinhardtii Cells Immobilized Within Thin Alginate Films Under Aerobic and Anaerobic Conditions

    SciTech Connect

    Kosourov, S. N.; Seibert, M.

    2009-01-01

    A new technique for immobilizing H{sub 2}-photoproducing green algae within a thin (<400 {micro}m) alginate film has been developed. Alginate films with entrapped sulfur/phosphorus-deprived Chlamydomonas reinhardtii, strain cc124, cells demonstrate (a) higher cell density (up to 2,000 {micro}g Chl mL{sup -1} of matrix), (b) kinetics of H{sub 2} photoproduction similar to sulfur-deprived suspension cultures, (c) higher specific rates (up to 12.5 {micro}mol mg{sup -1} Chl h{sup -1}) of H{sub 2} evolution, (d) light conversion efficiencies to H{sub 2} of over 1% and (e) unexpectedly high resistance of the H{sub 2}-photoproducing system to inactivation by atmospheric O{sub 2}. The algal cells, entrapped in alginate and then placed in vials containing 21% O{sub 2} in the headspace, evolved up to 67% of the H{sub 2} gas produced under anaerobic conditions. The results indicate that the lower susceptibility of the immobilized algal H{sub 2}-producing system to inactivation by O{sub 2} depends on two factors: (a) the presence of acetate in the medium, which supports higher rates of respiration and (b) the capability of the alginate polymer itself to effectively separate the entrapped cells from O{sub 2} in the liquid and headspace and restrict O{sub 2} diffusion into the matrix. The strategy presented for immobilizing algal cells within thin polymeric matrices shows the potential for scale-up and possible future applications.

  2. Rapid deamination of cyclobutane pyrimidine dimer photoproducts at TCG sites in a translationally and rotationally positioned nucleosome in vivo.

    PubMed

    Cannistraro, Vincent J; Pondugula, Santhi; Song, Qian; Taylor, John-Stephen

    2015-10-30

    Sunlight-induced C to T mutation hot spots in skin cancers occur primarily at methylated CpG sites that coincide with sites of UV-induced cyclobutane pyrimidine dimer (CPD) formation. The C and 5-methyl-C in CPDs are not stable and deaminate to U and T, respectively, which leads to the insertion of A by the DNA damage bypass polymerase η, thereby defining a probable mechanism for the origin of UV-induced C to T mutations. Deamination rates for T(m)CG CPDs have been found to vary 12-fold with rotational position in a nucleosome in vitro. To determine the influence of nucleosome structure on deamination rates in vivo, we determined the deamination rates of CPDs at TCG sites in a stably positioned nucleosome within the FOS promoter in HeLa cells. A procedure for in vivo hydroxyl radical footprinting with Fe-EDTA was developed, and, together with results from a cytosine methylation protection assay, we determined the translational and rotational positions of the TCG sites. Consistent with the in vitro observations, deamination was slower for one CPD located at an intermediate rotational position compared with two other sites located at outside positions, and all were much faster than for CPDs at non-TCG sites. Photoproduct formation was also highly suppressed at one site, possibly due to its interaction with a histone tail. Thus, it was shown that CPDs of TCG sites deaminate the fastest in vivo and that nucleosomes can modulate both their formation and deamination, which could contribute to the UV mutation hot spots and cold spots. PMID:26354431

  3. The photoproduction of superoxide radicals and the superoxide dismutase activity of Photosystem II. The possible involvement of cytochrome b559.

    PubMed

    Ananyev, G; Renger, G; Wacker, U; Klimov, V

    1994-08-01

    In the present study the light induced formation of superoxide and intrinsic superoxide dismutase (SOD) activity in PS II membrane fragments and D1/D2/Cytb559-complexes from spinach have been analyzed by the use of ferricytochrome c (cyt c(III)) reduction and xanthine/xanthine oxidase as assay systems. The following results were obtained: 1.) Photoreduction of Cyt c (III) by PS II membrane fragments is induced by addition of sodium azide, tetracyane ethylene (TCNE) or carbonylcyanide-p-trifluoromethoxy-phenylhydrazone (FCCP) and after removal of the extrinsic polypeptides by a 1M CaCl2-treatment. This activity which is absent in control samples becomes completely inhibited by the addition of exogenous SOD. 2.) The TCNE induced cyt c(III) photoreduction by PS II membrane fragments was found to be characterized by a half maximal concentration of c1/2=10 μM TCNE. Simultaneously, TCNE inhibits the oxygen evolution rate of PS II membrane fragments with c1/2≈ 3 μM. 3.) The photoproduction of O2 (-) is coupled with H(+)-uptake. This effect is diminished by the addition of the O2 (-)-trap cyt c(III). 4.) D1/D2/Cytb559-complexes and PS II membrane fragments deprived of the extrinsic proteins and manganese exhibit no SOD-activity but are capable of producing O2 (-) in the light if a PS II electron donor is added.Based on these results the site(s) of light induced superoxide formation in PS II is (are) inferred to be located at the acceptor side. A part of the PS II donor side and Cyt b559 in its HP-form are proposed to provide an intrinsic superoxide dismutase (SOD) activity. PMID:24310115

  4. The isospin structure of photoproduction of πη pairs from the nucleon in the threshold region

    NASA Astrophysics Data System (ADS)

    Käser, A.; Ahrens, J.; Annand, J. R. M.; Arends, H. J.; Bantawa, K.; Bartolome, P. A.; Beck, R.; Bekrenev, V.; Berghäuser, H.; Braghieri, A.; Branford, D.; Briscoe, W. J.; Brudvik, J.; Cherepnya, S.; Costanza, S.; Demissie, B.; Dieterle, M.; Downie, E. J.; Drexler, P.; Fil'kov, L. V.; Fix, A.; Glazier, D. I.; Hamilton, D.; Heid, E.; Hornidge, D.; Howdle, D.; Huber, G. M.; Jahn, O.; Jaegle, I.; Jude, T. C.; Kashevarov, V. L.; Keshelashvili, I.; Kondratiev, R.; Korolija, M.; Kruglov, S. P.; Krusche, B.; Lisin, V.; Livingston, K.; MacGregor, I. J. D.; Maghrbi, Y.; Mancell, J.; Manley, D. M.; Marinides, Z.; McGeorge, J. C.; McNicoll, E.; Mekterovic, D.; Metag, V.; Micanovic, S.; Middleton, D. G.; Mushkarenkov, A.; Nikolaev, A.; Novotny, R.; Oberle, M.; Ostrick, M.; Otte, P.; Oussena, B.; Pedroni, P.; Pheron, F.; Polonski, A.; Prakhov, S. N.; Robinson, J.; Rosner, G.; Rostomyan, T.; Schumann, S.; Sikora, M. H.; Sober, D. I.; Starostin, A.; Supek, I.; Thiel, M.; Thomas, A.; Unverzagt, M.; Watts, D. P.; Werthmüller, D.; Witthauer, L.

    2015-09-01

    Photoproduction of πη-pairs from nucleons has been investigated from threshold up to incident photon energies of ≈ 1.4 GeV. The quasi-free reactions γp → pπ0 η, γn → nπ0 η, γp → nπ+ η, and γn → pπ- η were for the first time measured from nucleons bound in the deuteron. The corresponding reactions from a free-proton target were also studied to investigate final-state interaction effects (for neutral pions the free-proton results could be compared to previous measurements; the γp → nπ+ η reaction was measured for the first time). For the π0 η final state coherent production via the γd → dπ0 η reaction was also investigated. The experiments were performed at the tagged photon beam of the Mainz MAMI accelerator using an almost 4π coverage electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. The total cross sections for the four different final states obey the relation σ (pπ0 η) ≈ σ (nπ0 η) ≈ 2 σ (pπ- η) ≈ 2 σ (nπ+ η) as expected for a dominant contribution from a Δ⋆ → ηΔ (1232) → πηN reaction chain, which is also supported by the shapes of the invariant-mass distributions of nucleon-meson and π-η pairs. The experimental results are compared to the predictions from an isobar reaction model.

  5. A 6.4MB duplication of the alpha-synuclein locus causing fronto-temporal dementia and parkinsonism - phenotype-genotype correlations

    PubMed Central

    Kara, Eleanna; Kiely, Aoife P; Proukakis, Christos; Giffin, Nicola; Love, Seth; Hehir, Jason; Rantell, Khadija; Pandraud, Amelie; Hernandez, Dena G; Nacheva, Elizabeth; Pittman, Alan M; Nalls, Mike A; Singleton, Andrew B; Revesz, Tamas; Bhatia, Kailash P; Quinn, Niall; Hardy, John; Holton, Janice L; Houlden, Henry

    2015-01-01

    Importance SNCA locus duplications are associated with variable clinical features and reduced penetrance but the reasons underlying this variability are unknown. Objective 1) To report a novel family carrying a heterozygous 6.4Mb duplication of the SNCA locus with an atypical clinical presentation strongly reminiscent of frontotemporal dementia (FTD) and late-onset pallidopyramidal syndromes. 2) To study phenotype-genotype correlations in SNCA locus duplications. Design, Setting, Participants and Data sources We report the clinical and neuropathologic features of a family carrying a 6.4Mb duplication of the SNCA locus. To identify candidate disease modifiers, we undertake a genetic analysis in the family and conduct statistical analysis on previously published cases carrying SNCA locus duplication using regression modelling with robust standard errors to account for clustering at the family level. Main outcome measures To assess whether length of the SNCA locus duplication influences disease penetrance and severity, and whether extra-duplication factors have a disease-modifying role. Results We identified a large 6.4Mb duplication of the SNCA locus in this family. Neuropathological analysis showed extensive α-synuclein pathology with minimal phospho-tau pathology. Genetic analysis showed an increased burden of PD-related risk factors and the disease-predisposing H1/H1 MAPT haplotype. Statistical analysis of previously published cases suggested that there is a trend towards increasing disease severity and disease penetrance with increasing duplication size. The corresponding odds ratios (95% CI) from the univariate analyses were 1.17 (0.81 to 1.68) and 1.34 (0.78 to 2.31) respectively. Gender was significantly associated with both disease risk and severity; males compared to females had increased disease risk and severity and the corresponding odds ratios (95% CI) from the univariate analyses were 8.36 (1.97 to 35.42) and 5.55 (1.39 to 22.22) respectively

  6. Diaquabis-(thio-cyanato-κN)bis[6-(4H-1,2,4-triazol-4-yl-κN(1))pyridin-2-amine]-cadmium.

    PubMed

    Liu, Yuan-Yuan; Yang, Pan; Ding, Bin

    2012-08-01

    In the title compound, [Cd(NCS)(2)(C(7)H(7)N(5))(2)(H(2)O)(2)], the Cd(II) cation lies on an inversion center and is coordinated by the N atoms of two thiocyanate anions, by N atoms of two 6-(4H-1,2,4-triazol-4-yl)pyridin-2-amine ligands and by the O atoms of two water molecules in a distorted N(4)O(2) octa-hedral geometry. The dihedral angle between the triazole and pyridine rings is 23.15 (12)°. In the crystal, mol-ecules are linked by N-H⋯N and O-H⋯S hydrogen bonds. Offset π-π stacking between parallel pyridine rings of adjacent mol-ecules is also observed, the centroid-centroid distance being 3.6319 (14) Å. PMID:22904754

  7. A Chandra Observation of the Luminous Northeastern Rim of the Galactic Supernova Remnant W28 (G6.4-0.1)

    NASA Astrophysics Data System (ADS)

    Pannuti, Thomas

    2016-06-01

    We present an analysis of a pointed observation made of the luminous northeastern rim of the Galactic supernova remnant (SNR) W28 (G6.4-0.1) with the Chandra X-ray Observatory. W28 is the archetype for the class of SNRs known as the mixed-morphology SNRs: sources in this class of objects feature a shell-like morphology with a contrasting center-filled X-ray morphology. Almost unique amongst mixed-morphology SNRs, W28 exhibits a luminous northeastern rim which is detected in the X-ray, optical and radio: this rim is also the site of a vigorous interaction between W28 and adjacent molecular clouds, as evidenced by the high concentration of hydroxyl (OH) masers seen at this rim. Our pointed Chandra observation of this rim is the highest angular X-ray observation made of this feature: initial analysis and results will be presented and discussed.

  8. Two-fermion-four-boson description of Hg198 within the Uν(6/12)⊗Uπ(6/4) extended nuclear structure supersymmetry

    NASA Astrophysics Data System (ADS)

    Bernards, C.; Heinze, S.; Jolie, J.; Fransen, C.; Linnemann, A.; Radeck, D.

    2009-05-01

    Using the Uν(6/12)⊗Uπ(6/4) extended supersymmetry, we constructed the energy spectrum and electromagnetic transition properties of the supermultiplet member Hg198 with two proton fermions coupled to a neutron boson core. Consistency between the supersymmetric interacting boson fermion fermion approximation (IBFFA) description and the F-spin symmetric interacting boson approximation (IBA-2) description is shown for this two-fermion-N-boson multiplet member. The data of a γγ angular correlation experiment using the HORUS cube γ-ray spectrometer—determining new multipole mixing ratios, level spins, γ transitions, and energy states—shows quite a good agreement, also for the low-energy part of the spectrum, when comparing theoretical predictions and experimental data. This is contrary to the usual assumption that a two-fermion-N-boson constellation should describe just the excited two-quasiparticle states.

  9. {sup 196}Hg and the 'magical quartet' of the extended U{sub {nu}}(6/12) x U{sub {pi}}(6/4) supersymmetry

    SciTech Connect

    Bernards, C.; Heinze, S.; Jolie, J.; Albers, M.; Fransen, C.; Radeck, D.

    2010-02-15

    We present the results of a {gamma}{gamma} angular correlation experiment investigating the nucleus {sup 196}Hg and compare these with a theoretical description of {sup 196}Hg within the U{sub {nu}}(6/12) x U{sub {pi}}(6/4) extended supersymmetry. To populate excited {sup 196}Hg states, we used the Cologne FN Tandem accelerator inducing the reaction {sup 194}Pt({alpha},2n){sup 196}Hg and analyzed the {gamma} decays of levels up to an excitation energy of 2.4 MeV with the HORUS cube spectrometer. The new results on this mercury isotope allow a comparison between the experimental data and the supersymmetrical predictions and show good agreement. This way we can add {sup 196}Hg as a fifth supermultiplet member to the so-called magical quartet consisting of {sup 194,195}Pt and {sup 195,196}Au.

  10. Viscoelastic Response of the Titanium Alloy Ti-6-4: Experimental Identification of Time- and Rate-Dependent Reversible and Irreversible Deformation Regions

    NASA Technical Reports Server (NTRS)

    Lerch, Bradley A.; Arnold, Steven M.

    2014-01-01

    In support of an effort on damage prognosis, the viscoelastic behavior of Ti-6Al-4V (Ti-6-4) was investigated. This report documents the experimental characterization of this titanium alloy. Various uniaxial tests were conducted to low load levels over the temperature range of 20 to 538 C to define tensile, creep, and relaxation behavior. A range of strain rates (6x10(exp -7) to 0.001/s) were used to document rate effects. All tests were designed to include an unloading portion, followed by a hold time at temperature to allow recovery to occur either at zero stress or strain. The titanium alloy was found to exhibit viscoelastic behavior below the "yield" point and over the entire range of temperatures (although at lower temperatures the magnitude is extremely small). These experimental data will be used for future characterization of a viscoelastic model.

  11. Electrochemical study on screen-printed carbon electrodes with modification by iron nanoparticles in Fe(CN)(6) (4-/3-) redox system.

    PubMed

    Lee, Shyh-Hwang; Fang, Hung-Yuan; Chen, Wen-Chang; Lin, Hong-Ming; Chang, C Allen

    2005-10-01

    The remarkable enhancement of electron transfer on screen-printed carbon electrodes (SPCEs) with modification by iron nanoparticles (Fe(nano)), coupled with Fe(CN)(6) (4-/3-) redox species, was characterized with an increase of electroactive area (A (ea)) at electrode surface together with a decrease of heterogeneous electron transfer rate constant (k degrees ) in the system. Hence, Fe(nano)-Fe(CN)(6) (3-) SPCEs with deposition of glucose oxidase (GOD) demonstrated a higher sensitivity to various glucose concentrations than Fe(CN)(6) (3-)/GOD-deposited SPCEs. In addition, an inhibited diffusion current from cyclic voltammograms was also observed with an increase in redox concentration and complicated the estimation of A (ea). Further analysis by the electrochemical impedance method, it was shown that this effect might be resulted from the electrode surface blocking by the products of activated complex decomposition. PMID:16136306

  12. The CYP4502D6 *4 and *6 alleles are the molecular genetic markers for drug response: implications in colchicine non-responder FMF patients.

    PubMed

    Yalcıntepe, Sinem; Ozdemır, Ozturk; Sılan, Coskun; Ozen, Filiz; Uludag, Ahmet; Candan, Ferhan; Sılan, Fatma

    2016-06-01

    The cytochrome P450 2D6 (CYP2D6) is a cytochrome P450 enzyme involved in the oxidative biotransformation of the xenobiotics, carcinogens and various clinically important drugs. Patients are evaluated in three sub-groups of extensive (EM), intermediate (IM) and poor metabolizer (PM) phenotypes due to their drug-metabolising ability for the target CYP2D6 gene. Colchicine non-responsive FMF patients were prospectively genotyped for the major CYP2D6 alleles in the current study. Major CYP2D6 alleles of *1, *3, *4, *5, and *6 were genotyped for 30 responsive and 60 non-responsive FMF patients by multiplex PCR-based reverse-hybridization StripAssay and real-time PCR methods. DNA banks isolated from blood-EDTA were retrospectively used in the current patients and results were compared statistically. Increased CYP2D6 *4 and *6 allele frequencies were highly detected in the colchicine non-responsive FMF patients when compared to the responsive group. Results showed the frequencies of major CYP2D6 *1(wild), *3(2637A > delA), *4(G1934A), *5(total gene deletion) and *6(1707T del) alleles in 0.550, 0.042, 0.158, 0.025 and 0.225 for non-responder and 0.880 and 0.120 (CYP2D6*1 and *4) for the responder groups, respectively. Despite small sample size, this study suggests that there is an association between CYP2D6*4 and CYP2D6*6 alleles and drug intoxicants in colchicine non-responder FMF patients. PMID:25645282

  13. Conserved Negative Charges in the N-terminal Tetramerization Domain Mediate Efficient Assembly of Kv2.1 and Kv2.1/Kv6.4 Channels*

    PubMed Central

    Bocksteins, Elke; Labro, Alain J.; Mayeur, Evy; Bruyns, Tine; Timmermans, Jean-Pierre; Adriaensen, Dirk; Snyders, Dirk J.

    2009-01-01

    Voltage-gated potassium (Kv) channels are transmembrane tetramers of individual α-subunits. Eight different Shaker-related Kv subfamilies have been identified in which the tetramerization domain T1, located on the intracellular N terminus, facilitates and controls the assembly of both homo- and heterotetrameric channels. Only the Kv2 α-subunits are able to form heterotetramers with members of the silent Kv subfamilies (Kv5, Kv6, Kv8, and Kv9). The T1 domain contains two subdomains, A and B box, which presumably determine subfamily specificity by preventing incompatible subunits to assemble. In contrast, little is known about the involvement of the A/B linker sequence. Both Kv2 and silent Kv subfamilies contain a fully conserved and negatively charged sequence (CDD) in this linker that is lacking in the other subfamilies. Neutralizing these aspartates in Kv2.1 by mutating them to alanines did not affect the gating properties, but reduced the current density moderately. However, charge reversal arginine substitutions strongly reduced the current density of these homotetrameric mutant Kv2.1 channels and immunocytochemistry confirmed the reduced expression at the plasma membrane. Förster resonance energy transfer measurements using confocal microscopy showed that the latter was not due to impaired trafficking, but to a failure to assemble the tetramer. This was further confirmed with co-immunoprecipitation experiments. The corresponding arginine substitution in Kv6.4 prevented its heterotetrameric interaction with Kv2.1. These results indicate that these aspartates (especially the first one) in the A/B box linker of the T1 domain are required for efficient assembly of both homotetrameric Kv2.1 and heterotetrameric Kv2.1/silent Kv6.4 channels. PMID:19717558

  14. Energy level properties of 4p{sup 6}4d{sup 3}, 4p{sup 6}4d{sup 2}4f, and 4p{sup 5}4d{sup 4} configurations of the W{sup 35+} ion

    SciTech Connect

    Bogdanovich, P. Kisielius, R.

    2014-11-15

    The ab initio quasirelativistic Hartree–Fock method developed specifically for the calculation of spectroscopic parameters of heavy atoms and highly charged ions was used to derive spectral data for the multicharged tungsten ion W{sup 35+}. The configuration interaction method was applied to include the electron-correlation effects. The relativistic effects were taken into account in the Breit–Pauli approximation for quasirelativistic Hartree–Fock radial orbitals. The energy level spectra, radiative lifetimes τ, and Lande g-factors have been calculated for the 4p{sup 6}4d{sup 3}, 4p{sup 6}4d{sup 2}4f, and 4p{sup 5}4d{sup 4} configurations of the W{sup 35+} ion.

  15. Dephenolization of stored olive-mill wastewater, using four different adsorbing matrices to attain a low-cost feedstock for hydrogen photo-production.

    PubMed

    Padovani, Giulia; Pintucci, Cristina; Carlozzi, Pietro

    2013-06-01

    This investigation deals with the conversion of olive-mill wastewater (OMW) into several feedstocks suitable for hydrogen photo-production. The goal was reached by means of two sequential steps: (i) a pre-treatment process of stored-OMW for the removal of polyphenols, which made it possible to obtain several effluents, and (ii) a photo-fermentative process for hydrogen production by means of Rhodopseudomonas palustris sp. Four different adsorbent matrices (Azolla, granular active carbon, resin, and zeolite) were used to dephenolize stored-OMW. The four liquid fractions attained by using the above process created the same number of effluents, and these were diluted with water and then used for hydrogen photo-production. The maximum hydrogen production rate (14.31 mL/L/h) was attained with the photo-fermenter containing 25% of the effluent, which came from the pre-treatment of stored-OMW using granular active carbon. Using the carbon effluent as feedstock, the greatest light conversion efficiency of 2.29% was achieved. PMID:23612177

  16. Identification of halogenated photoproducts generated after ultraviolet-irradiation of parabens and benzoates in water containing chlorine by solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Alvarez-Rivera, Gerardo; Llompart, Maria; Garcia-Jares, Carmen; Lores, Marta

    2014-07-01

    This work presents a new solid-phase microextraction (SPME)-based approach to investigate the formation of halogenated by-products generated by the UV-induced photodegradation of parabens and their congener benzoates in water containing chlorine. Degradation of parent species, and further identification of their transformation by-products were monitored by gas chromatography coupled to mass spectrometry (GC/MS). In order to improve detectability, SPME was applied as a preconcentration step after UV-irradiation of target preservatives. Experiments performed with dechlorinated water, ultrapure water, and tap water showed that under UV-light, the presence of even low levels of free chlorine, increases the photodegradation rate of target preservatives, enhancing the formation of halogenated photoproducts. Monobrominated, dibrominated and bromochlorinated hydroxybenzoates were identified, and the transformation of benzoates into halogenated parabens was also confirmed. Bromination is expected to occur when free chlorine is present, due to the presence of traces of bromide in water samples. Five halogenated phenols (mainly brominated) were detected as breakdown photoproducts from both families of target preservatives. On the basis of the appearance of the aforementioned by-products, a tentative transformation pathway, consistent with the photoformation-photodecay kinetics of the by-products, is proposed herein for the first time. PMID:24856965

  17. Observation of π+π-π+π- photoproduction in ultraperipheral heavy-ion collisions at sNN=200 GeV at the STAR detector

    NASA Astrophysics Data System (ADS)

    Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Alakhverdyants, A. V.; Anderson, B. D.; Arkhipkin, D.; Averichev, G. S.; Balewski, J.; Barnby, L. S.; Baumgart, S.; Beavis, D. R.; Bellwied, R.; Benedosso, F.; Betancourt, M. J.; Betts, R. R.; Bhasin, A.; Bhati, A. K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Biritz, B.; Bland, L. C.; Bonner, B. E.; Bouchet, J.; Braidot, E.; Brandin, A. V.; Bridgeman, A.; Bruna, E.; Bueltmann, S.; Bunzarov, I.; Burton, T. P.; Cai, X. Z.; Caines, H.; Calderón de La Barca Sánchez, M.; Catu, O.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Choi, K. E.; Christie, W.; Chung, P.; Chung, S. U.; Clarke, R. F.; Codrington, M. J. M.; Corliss, R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Dash, S.; Davila Leyva, A.; de Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Dephillips, M.; Derevschikov, A. A.; Derradi de Souza, R.; Didenko, L.; Djawotho, P.; Dogra, S. M.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Dunlop, J. C.; Dutta Mazumdar, M. R.; Efimov, L. G.; Elhalhuli, E.; Elnimr, M.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Eun, L.; Evdokimov, O.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Fersch, R. G.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Gagliardi, C. A.; Gangadharan, D. R.; Ganti, M. S.; Garcia-Solis, E. J.; Geromitsos, A.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gorbunov, Y. N.; Gordon, A.; Grebenyuk, O.; Grosnick, D.; Grube, B.; Guertin, S. M.; Gupta, A.; Gupta, N.; Guryn, W.; Haag, B.; Hallman, T. J.; Hamed, A.; Han, L.-X.; Harris, J. W.; Hays-Wehle, J. P.; Heinz, M.; Heppelmann, S.; Hirsch, A.; Hjort, E.; Hoffman, A. M.; Hoffmann, G. W.; Hofman, D. J.; Hollis, R. S.; Huang, H. Z.; Humanic, T. J.; Huo, L.; Igo, G.; Iordanova, A.; Jacobs, P.; Jacobs, W. W.; Jakl, P.; Jena, C.; Jin, F.; Jones, C. L.; Jones, P. G.; Joseph, J.; Judd, E. G.; Kabana, S.; Kajimoto, K.; Kang, K.; Kapitan, J.; Kauder, K.; Keane, D.; Kechechyan, A.; Kettler, D.; Kikola, D. P.; Kiryluk, J.; Kisiel, A.; Klein, S. R.; Knospe, A. G.; Kocoloski, A.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Kopytine, M.; Koralt, I.; Korsch, W.; Kotchenda, L.; Kouchpil, V.; Kravtsov, P.; Krueger, K.; Krus, M.; Kumar, L.; Kurnadi, P.; Lamont, M. A. C.; Landgraf, J. M.; Lapointe, S.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, C.-H.; Lee, J. H.; Leight, W.; Levine, M. J.; Li, C.; Li, L.; Li, N.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z.; Lin, G.; Lindenbaum, S. J.; Lisa, M. A.; Liu, F.; Liu, H.; Liu, J.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Love, W. A.; Lu, Y.; Ma, G. L.; Ma, Y. G.; Mahapatra, D. P.; Majka, R.; Mall, O. I.; Mangotra, L. K.; Manweiler, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; Matulenko, Yu. A.; McDonald, D.; McShane, T. S.; Meschanin, A.; Milner, R.; Minaev, N. G.; Mioduszewski, S.; Mischke, A.; Mitrovski, M. K.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Munhoz, M. G.; Nandi, B. K.; Nattrass, C.; Nayak, T. K.; Nelson, J. M.; Netrakanti, P. K.; Ng, M. J.; Nogach, L. V.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Okada, H.; Okorokov, V.; Olson, D.; Pachr, M.; Page, B. S.; Pal, S. K.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Phatak, S. C.; Pile, P.; Planinic, M.; Ploskon, M. A.; Pluta, J.; Plyku, D.; Poljak, N.; Poskanzer, A. M.; Potukuchi, B. V. K. S.; Powell, C. B.; Prindle, D.; Pruneau, C.; Pruthi, N. K.; Pujahari, P. R.; Putschke, J.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Redwine, R.; Reed, R.; Rehberg, J. M.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Rose, A.; Roy, C.; Ruan, L.; Russcher, M. J.; Sahoo, R.; Sakai, S.; Sakrejda, I.; Sakuma, T.; Salur, S.; Sandweiss, J.; Sangaline, E.; Schambach, J.; Scharenberg, R. P.; Schmitz, N.; Schuster, T. R.; Seele, J.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shahaliev, E.; Shao, M.; Sharma, M.; Shi, S. S.; Sichtermann, E. P.; Simon, F.; Singaraju, R. N.; Skoby, M. J.; Smirnov, N.; Sorensen, P.; Sowinski, J.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Staszak, D.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Subba, N. L.; Sumbera, M.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Symons, T. J. M.; Szanto de Toledo, A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarini, L. H.; Tarnowsky, T.; Thein, D.; Thomas, J. H.; Tian, J.; Timmins, A. R.; Timoshenko, S.; Tlusty, D.; Tokarev, M.; Trainor, T. A.; Tram, V. N.; Trentalange, S.; Tribble, R. E.; Tsai, O. D.; Ulery, J.; Ullrich, T.; Underwood, D. G.; van Buren, G.; van Nieuwenhuizen, G.; Vanfossen, J. A., Jr.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Videbaek, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Wada, M.; Walker, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, Q.; Wang, X.; Wang, X. L.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Whitten, C., Jr.; Wieman, H.; Wingfield, E.; Wissink, S. W.; Witt, R.; Wu, Y.; Xie, W.; Xu, N.; Xu, Q. H.; Xu, W.; Xu, Y.; Xu, Z.; Xue, L.; Yang, Y.; Yepes, P.; Yip, K.; Yoo, I.-K.; Yue, Q.; Zawisza, M.; Zbroszczyk, H.; Zhan, W.; Zhang, S.; Zhang, W. M.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, J.; Zhong, C.; Zhou, J.; Zhou, W.; Zhu, X.; Zhu, Y. H.; Zoulkarneev, R.; Zoulkarneeva, Y.; STAR Collaboration

    2010-04-01

    We present a measurement of π+π-π+π- photonuclear production in ultraperipheral Au-Au collisions at sNN=200 GeV from the STAR experiment. The π+π-π+π- final states are observed at low transverse momentum and are accompanied by mutual nuclear excitation of the beam particles. The strong enhancement of the production cross section at low transverse momentum is consistent with coherent photoproduction. The π+π-π+π- invariant mass spectrum of the coherent events exhibits a broad peak around 1540±40 MeV/c2 with a width of 570±60 MeV/c2, in agreement with the photoproduction data for the ρ0(1700). We do not observe a corresponding peak in the π+π- final state and measure an upper limit for the ratio of the branching fractions of the ρ0(1700) to π+π- and π+π-π+π- of 2.5% at 90% confidence level. The ratio of ρ0(1700) and ρ0(770) coherent production cross sections is measured to be 13.4±0.8stat.±4.4syst.%.

  18. Observation of pi+ pi- pi+pi- photoproduction in ultraperipheral heavy-ion collisons at sqrt sNN = 200 GeV at the STAR Detector

    SciTech Connect

    Abelev, B.I.; Dunlop, J.; et al. STAR Collaboration

    2010-04-02

    We present a measurement of {pi}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -} photonuclear production in ultraperipheral Au-Au collisions at {radical}s{sub NN} = 200 GeV from the STAR experiment. The {pi}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -} final states are observed at low transverse momentum and are accompanied by mutual nuclear excitation of the beam particles. The strong enhancement of the production cross section at low transverse momentum is consistent with coherent photoproduction. The {pi}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -} invariant mass spectrum of the coherent events exhibits a broad peak around 1540 {+-} 40 MeV/c{sup 2} with a width of 570 {+-} 60 MeV/c{sup 2}, in agreement with the photoproduction data for the {rho}{sup 0}(1700). We do not observe a corresponding peak in the {pi}{sup +}{pi}{sup -} final state and measure an upper limit for the ratio of the branching fractions of the {rho}{sup 0}(1700) to {pi}{sup +}{pi}{sup -} and {pi}{sup +}{pi}{sup -}{pi}{sup +}{pi}{sup -} of 2.5% at 90% confidence level. The ratio of {rho}{sup 0}(1700) and {rho}{sup 0}(770) coherent production cross sections is measured to be 13.4 {+-} 0.8{sub stat.}{+-}4.4{sub syst.}%.

  19. Exclusive J/ψ photoproduction off protons in ultraperipheral p-Pb collisions at √(s(NN))=5.02 TeV.

    PubMed

    Abelev, B; Adam, J; Adamová, D; Aggarwal, M M; Aglieri Rinella, G; Agnello, M; Agostinelli, A; Agrawal, N; Ahammed, Z; Ahmad, N; Ahmed, I; Ahn, S U; Ahn, S A; Aimo, I; Aiola, S; Ajaz, M; Akindinov, A; Alam, S N; Aleksandrov, D; Alessandro, B; Alexandre, D; Alici, A; Alkin, A; Alme, J; Alt, T; Altinpinar, S; Altsybeev, I; Alves Garcia Prado, C; Andrei, C; Andronic, A; Anguelov, V; Anielski, J; Antičić, T; Antinori, F; Antonioli, P; Aphecetche, L; Appelshäuser, H; Arcelli, S; Armesto, N; Arnaldi, R; Aronsson, T; Arsene, I C; Arslandok, M; Augustinus, A; Averbeck, R; Awes, T C; Azmi, M D; Bach, M; Badalà, A; Baek, Y W; Bagnasco, S; Bailhache, R; Bala, R; Baldisseri, A; Baltasar Dos Santos Pedrosa, F; Baral, R C; Barbera, R; Barile, F; Barnaföldi, G G; Barnby, L S; Barret, V; Bartke, J; Basile, M; Bastid, N; Basu, S; Bathen, B; Batigne, G; Batista Camejo, A; Batyunya, B; Batzing, P C; Baumann, C; Bearden, I G; Beck, H; Bedda, C; Behera, N K; Belikov, I; Bellini, F; Bellwied, R; Belmont-Moreno, E; 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Zichichi, A; Zimmermann, A; Zimmermann, M B; Zinovjev, G; Zoccarato, Y; Zyzak, M

    2014-12-01

    We present the first measurement at the LHC of exclusive J/ψ photoproduction off protons, in ultraperipheral proton-lead collisions at sqrt[s_{NN}]=5.02  TeV. Events are selected with a dimuon pair produced either in the rapidity interval, in the laboratory frame, 2.5photoproduction cross section in γp energies from about 20 to 700 GeV, or equivalently, from Bjorken x scaling variable between ∼2×10^{-2} and ∼2×10^{-5}, thus indicating no significant change in the gluon density behavior of the proton between HERA and LHC energies. PMID:25526123

  20. Photoproduction of 7pi0 on hydrogen with CLAS from 1.1 GeV - 5.45 GeV using e+e --gamma decay

    NASA Astrophysics Data System (ADS)

    Kunkel, Michael C.

    Photoproduction of the pi0 meson was studied using the CLAS detector at the Thomas Jefferson National Accelerator Facility using tagged incident photon energies spanning the range Egamma = 1.1 GeV - 5.45 GeV. The measurement is performed on a liquid hydrogen target in the reaction gammap → pe +e--(gamma). The final state of the reaction is the sum of two subprocesses for pi0 decay, the Dalitz decay mode of gamma0 → e +e--gamma and conversion mode where one photon from pi0 → gammagamma decay is converted into a e+e -- pair. This specific final state reaction avoided limitations caused by single prompt track triggering, while the span of incident photon energies allowed for measurements of gamma0 photoproduction to a domain never systematically measured before. We report the measurement of the gamma0 differential cross sections dsigma/dO and dsigma/dt. The angular distributions agree well with the SAID parametrization for incident beam energies below 3 GeV. As a result with this new data, the chi2/p.d.f. of the global fit in the SAID parametrization improved to 3.1 from 3.7. For incident beam energies greater than 3 GeV a comparison of a model based on Generalized Parton Distributions (GPD) with experimental data shows significant discrepancy, requiring further model developments to describe the data.