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Sample records for 12c nucleus rezonansnye

  1. Microscopic optical model calculations of 4He, 12C-nucleus absorption cross sections

    NASA Technical Reports Server (NTRS)

    Dubey, R. R.; Khandelwal, G. S.; Cucinotta, F. A.; Wilson, J. W.

    1996-01-01

    Calculations of absorption cross sections using a microscopic first-order optical potential for heavy-ion scattering are compared with experiments. In-medium nucleon-nucleon (NN) cross sections were used to calculate the two-body scattering amplitude. A medium-modified first-order optical potential was obtained for heavy-ion scattering using the in-medium two-body scattering amplitude. A partial wave expansion of the Lippmann-Schwinger equation in momentum space was used to calculate the absorption cross sections for various systems. The results are presented for the absorption cross sections for 4He-nucleus and 12C-nucleus scattering systems and are compared with the experimental values in the energy range 18-83A MeV. The use of the in-medium NN cross sections is found to result in significant reduction of the free space absorption cross sections in agreement with experiment.

  2. Study of the bar{K}-Nucleus Interaction by Using the 12C(K-, p) Reaction at J-PARC

    NASA Astrophysics Data System (ADS)

    Ichikawa, Yudai; Ahn, Jung Keun; Akazawa, Yuya; Aoki, Kanae; Botta, Elena; Ekawa, Hiroyuki; Evtoukhovitch, Petr; Feliciello, Alessandro; Fujita, Manami; Gogami, Toshiyuki; Hasegawa, Shoichi; Hasegawa, Tomoyuki; Hayakawa, Shuhei; Hayakawa, Tomonori; Honda, Ryotaro; Hosomi, Kenji; Imai, Ken'ichi; Jung, Wooseung; Kanatsuki, Shunsuke; Kim, Shinhyung; Kinbara, Shinji; Kobayashi, Kazuya; Lee, Jaeyong; Marcello, Simonetta; Miwa, Koji; Moon, Taejin; Nagae, Tomofumi; Nakada, Yoshiyuki; Nakagawa, Manami; Nanamura, Takuya; Naruki, Megumi; Sakaguchi, Atsushi; Sako, Hiroyuki; Sato, Susumu; Sasaki, Yuki; Shirotori, Kotaro; Sugimura, Hitoshi; Takahashi, Toshiyuki; Tamura, Hirokazu; Tanida, Kiyoshi; Tsamalaidze, Zviadi; Ukai, Mifuyu; Yamamoto, Takeshi. O.

    We have measured the inclusive missing-mass spectrum of the 12C(K-, p) reaction at a K- beam momentum of 1.8 GeV/c. This experiment was carried out as a by-product of a pilot run of the J-PARC E05 experiment, which was conceived to search Ξ-hypernuclei by using the (K-, K+) reaction at J-PARC K1.8 beam line. In present measurement, we study the bar{K}-nucleus interaction by comparing the observed missing-mass spectrum with a DWIA calculation. In a preliminary analysis, a "KINK" structure, which might be originated from the threshold of K-N → Σπ absorption, was found.

  3. Phenomenological and semi-microscopic analysis for 16O and 12C elastically scattering on the nucleus of 16O and 12C at Energies near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Hamada, Sh; Burtebayev, N.; Amangeldi, N.; Gridnev, K. A.; Rusek, K.; Kerimkulov, Zh; Maltsev, N.

    2012-09-01

    The nuclear burning process proceeds from the conservation of the most abundant element hydrogen to helium, then from helium to carbon and oxygen, and then from these to heavier elements. Some of the key reactions for the carbon and oxygen burning stages of the nucleosynthesis are 12C+12C and 16O+16O leading to all possible final states. This paper contains the experimental measurements of 12C+12C and 16O+16O angular distributions performed at the cyclotron DC-60 in Astana, Kazakhstan. The extracted beam of 16O and 12C was accelerated up to two energies 1.75 and 1.5 MeV/n and then directed to an Al2O3 target of thickness 20 μg/cm2 and a carbon self-supporting target of thickness 17.4 μg/cm2. The angular distribution calculations were performed using both the phenomenological optical potential (SPI-GENOA) code and the double folding potential (FRESCO) code.

  4. Description of nuclear systems with a self-consistent configuration-mixing approach: Theory, algorithm, and application to the 12C test nucleus

    NASA Astrophysics Data System (ADS)

    Robin, C.; Pillet, N.; Peña Arteaga, D.; Berger, J.-F.

    2016-02-01

    Background: Although self-consistent multiconfiguration methods have been used for decades to address the description of atomic and molecular many-body systems, only a few trials have been made in the context of nuclear structure. Purpose: This work aims at the development of such an approach to describe in a unified way various types of correlations in nuclei in a self-consistent manner where the mean-field is improved as correlations are introduced. The goal is to reconcile the usually set-apart shell-model and self-consistent mean-field methods. Method: This approach is referred to as "variational multiparticle-multihole configuration mixing method." It is based on a double variational principle which yields a set of two coupled equations that determine at the same time the expansion coefficients of the many-body wave function and the single-particle states. The solution of this problem is obtained by building a doubly iterative numerical algorithm. Results: The formalism is derived and discussed in a general context, starting from a three-body Hamiltonian. Links to existing many-body techniques such as the formalism of Green's functions are established. First applications are done using the two-body D1S Gogny effective force. The numerical procedure is tested on the 12C nucleus to study the convergence features of the algorithm in different contexts. Ground-state properties as well as single-particle quantities are analyzed, and the description of the first 2+ state is examined. Conclusions: The self-consistent multiparticle-multihole configuration mixing method is fully applied for the first time to the description of a test nucleus. This study makes it possible to validate our numerical algorithm and leads to encouraging results. To test the method further, we will realize in the second article of this series a systematic description of more nuclei and observables obtained by applying the newly developed numerical procedure with the same Gogny force. As

  5. Non-coplanar compact configurations of nuclei and non-compound-nucleus contribution in the fusion cross section of the 12C+93Nb reaction

    NASA Astrophysics Data System (ADS)

    Chopra, Sahila; Hemdeep, Kaur, Arshdeep; Gupta, Raj K.

    2016-02-01

    Background: In our earlier study of the 12C+93Nb→*105Ag reaction at three near- and below-barrier energies (Ec .m .=41.097 , 47.828, and 54.205 MeV), using the dynamical cluster-decay model (DCM) with various nuclear interaction potentials (the Blocki et al. pocket formula and others derived from the Skyrme energy density formalism) for compact, coplanar (Φc=00 ) nuclei, we found a large non-compound-nucleus (nCN) contribution in the measured fusion cross section of this reaction. Purpose: In the present work, we look for the effect of using non-coplanar, compact configurations (Φc≠00 ), in the Blocki et al. pocket formula of the nuclear proximity potential, on the non-compound-nucleus (nCN) contribution, using the DCM. Methods: Allowing the Φ degree of freedom in the DCM formalism, we calculate the compound-nucleus (CN) and nCN cross sections. The only parameter of the DCM is the neck-length parameter Δ R , which also fits the empirically determined nCN cross section nearly exactly, under the assumption of considering it like a quasifission process where the fragment preformation factor P0=1 . Results: With the Φ degree of freedom included, at the higher two energies the nCN cross section gets enhanced, and hence the pure CN cross section is decreased, since the calculated (total) fusion cross section is fitted to experimental data. The parameter Δ R for the nCN contribution is smaller, and hence the reaction time larger, than for the CN decay process. Also, the contributing angular momentum ℓmax value increases in going from Φc=00 to Φc≠00 for both the CN and nCN processes. The intermediate mass fragments (IMFs), measured up to mass 13 in this reaction, are shown extended up to mass 16, and the fusion-fission (f f ) region is identified as A /2 ±16 , the same as for the Φc=00 case. Conclusions: As a result of enhanced nCN cross section due to Φc≠00 , the CN fusion probability PCN for *105Ag changes its behavior from an increasing to a

  6. 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

    2008-04-04

    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.

  7. High-spin molecular resonances in 12C + 12C

    NASA Astrophysics Data System (ADS)

    Uegaki, E.; Abe, Y.

    2016-05-01

    Resonances observed in the 12C + 12C collisions are studied with a molecular model. At high spins J = 10-18, a stable dinuclear configuration is found to be an equator-equator touching one. Firstly, normal modes have been solved around the equilibrium, with spin J and K-quantum number being specified for rotation of the whole system. Secondly, with respect to large centrifugal energy, Coriolis coupling has been diagonalized among low-lying 11 states of normal-mode excitations, which brings K-mixing. The analyses of decay widths and excitation functions have been done. The molecular ground state exhibits alignments of the orbital angular momentum and the 12C spins, while some of the molecular excited states exhibit disalignments with small widths. Those results are surprisingly in good agreement with the experiments, which will light up a new physical picture of the highspin 12C + 12C resonances.

  8. Intermediate resonance of inelastic 12C + 12C scattering

    NASA Astrophysics Data System (ADS)

    Osamu, Tanimura

    1980-01-01

    The intermediate resonances observed in the inelastic 12C + 12C cross sections to the single and mutual 2 1+(4.43 MeV) excitations and the single 3 1- (9.64 MeV) excitation are studied by the coupled-channel method with the use of the coupling interaction derived by the folding procedure between 12C and 12C. It is shown that the model is successful in reproducing the gross structures of the inelastic cross sections and especially the correlated resonance energies of the inelastic channels. The inelastic resonances are shown to be due to the molecular resonances in an adiabatic potential between two 12C, which reproduces correctly the coupled channel resonances.

  9. Angular correlation measurements for {sup 12}C{sup 12}C,{sup 12}C{sup 12}C 3{sup -} scattering

    SciTech Connect

    Wuosmaa, A.H.; Betts, R.R.; Freer, M.

    1995-08-01

    Previous studies of inelastic {sup 12}C + {sup 12}C scattering to a variety of final states identified significant resonance behavior in a number of different reaction channels. These resonances can be interpreted as either potential scattering resonances, or as population of cluster structures in the compound nucleus {sup 24}Mg, or as some interplay between the two mechanisms. Currently, for many of these resonances the situation remains unclear. One example is a large peak observed in the excitation function for the 3{sup -} - g.s. excitation, identified in previous work performed at the Daresbury Laboratory in England. This peak is observed at the same center-of-mass energy as one observed in the O{sub 2}{sup +}-O{sub 2}{sup +} inelastic scattering channel. That structure was suggested to correspond to exotic deformed configurations in the compound nucleus {sup 24}Mg. As the peak in the 3{sup -} + g.s. exit channel occurs at precisely the same energy as the purported resonance, it is tempting to associate the two. Before such an association can be confirmed or ruled out, further information must be obtained about the 3{sup -} + g.s. structure. In particular, it is important to determine the angular momenta that dominate the 3{sup -} + g.s. structure.

  10. Neutrino Scattering from 12C

    NASA Astrophysics Data System (ADS)

    Hayes, Anna

    2017-01-01

    Neutrino scattering cross-sections from 12C, which have been measure for pion decay-at-rest and pion decay-in-flight neutrino energies, are difficult to reproduce theoretically. In this talk I discuss the physics issues involved and show the importance of a proper treatment of the conservation of the vector current.

  11. Cluster Emission in 13C + 12C and 12C + 12C Reactions at ~ 6 Mev/nucleon

    NASA Astrophysics Data System (ADS)

    Rana, T. K.; Bhattacharya, C.; Kundu, S.; Banerjee, K.; Bhattacharya, S.; Mukherjee, G.; Ghosh, T. K.; Meena, J. K.; Dhara, P.; Biswas, M.; Pai, H.; Mahata, K.; Kumar, Suresh; Ramachandran, K.; Rout, P. C.; Pandit, S. K.; Nanal, V.; Pillay, R. G.

    Cluster state formation viz. the population of unbound 8Be and the Hoyle state of 12C produced in the reactions 12C(77 MeV) + 12C and 13C(75 MeV) + 12C have been studied using resonance particle spectroscopy. It was observed that there is a large difference in the cluster state formation in these two reactions and the yield of neutron rich isotopes of different fragments is more in the 13C + 12C compared to 12C + 12C reactions at 6 MeV/u.

  12. Experimental investigations of the sub-Coulomb 12C+12C and 12C+16O reactions

    NASA Astrophysics Data System (ADS)

    Courtin, S.; Fruet, G.; Jenkins, D. G.; Jiang, C. L.; Heine, M.; Montanari, D.; Santiago-Gonzalez, D.; Avila-Coronado, M.; Morris, L. G.; Goasduff, A.; Rehm, E.; Back, B.; Bourgin, D.; Beck, C.

    2017-06-01

    Cluster resonances in light heavy-ion systems like 12C+12C and 12C+16O may have a major impact on astrophysics stellar scenarios. Resonant radiative capture reactions have been studied for these systems at energies at and slightly below their Coulomb barriers to investigate the possible 12C-12C and 12C-16O molecular origin of the resonances. Spins have been attributed to the resonances and specificities of their γ-decay have been identified. At deep sub-barrier energies, a fusion cross section measurement using the particle-γ coincidence technique is discussed for the 12C+12C system. A new project is presented to possibly extend the 12C+12C S low-energy S factor study.

  13. YF-12C on ramp

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The so-called YF-12C on the NASA Flight Research Center ramp. Following the loss of a YF-12A in a non-fatal accident in June 1971, NASA acquired the second production SR-71A (61-7951) from the Air Force. Because the SR-71 program was shrouded in the highest secrecy, the Air Force restricted NASA to using the aircraft solely for propulsion testing with YF-12A inlets and engines. It was designated the YF-12C, and given a bogus tail number (06937). The two YF-12As in the program had actual tail numbers 06935 and 06936. The first NASA flight of the YF-12C took place on 24 May 1972. The Flight Research Center's involvement with the YF-12A, an interceptor version of the Lockheed A-12, began in 1967. Ames Research Center was interested in using wind tunnel data that had been generated at Ames under extreme secrecy. Also, the Office of Advanced Research and Technology (OART) saw the YF-12A as a means to advance high-speed technology, which would help in designing the Supersonic Transport (SST). The Air Force needed technical assistance to get the latest reconnaissance version of the A-12 family, the SR-71A, fully operational. Eventually, the Air Force offered NASA the use of two YF-12A aircraft, 60-6935 and 606936. A joint NASA-USAF program was mapped out in June 1969. NASA and Air Force technicians spent three months readying 935 for flight. On 11 December 1969, the flight program got underway with a successful maiden flight piloted by Col. Joe Rogers and Maj. Gary Heidelbaugh of the SR-71/F-12 Test Force. During the program, the Air Force concentrated on military applications, and NASA pursued a loads research program. NASA studies included inflight heating, skin-friction cooling, 'coldwall' research (a heat transfer experiment), flowfield studies, shaker vane research, and tests in support of the Space Shuttle landing program. Ultimately, 935 became the workhorse of the program, with 146 flights between 11 December 1969 and 7 November 1979. The second YF-12A, 936, made

  14. YF-12C on ramp

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The so-called YF-12C on the NASA Flight Research Center ramp. Following the loss of a YF-12A in a non-fatal accident in June 1971, NASA acquired the second production SR-71A (61-7951) from the Air Force. Because the SR-71 program was shrouded in the highest secrecy, the Air Force restricted NASA to using the aircraft solely for propulsion testing with YF-12A inlets and engines. It was designated the YF-12C, and given a bogus tail number (06937). The two YF-12As in the program had actual tail numbers 06935 and 06936. The first NASA flight of the YF-12C took place on 24 May 1972. The Flight Research Center's involvement with the YF-12A, an interceptor version of the Lockheed A-12, began in 1967. Ames Research Center was interested in using wind tunnel data that had been generated at Ames under extreme secrecy. Also, the Office of Advanced Research and Technology (OART) saw the YF-12A as a means to advance high-speed technology, which would help in designing the Supersonic Transport (SST). The Air Force needed technical assistance to get the latest reconnaissance version of the A-12 family, the SR-71A, fully operational. Eventually, the Air Force offered NASA the use of two YF-12A aircraft, 60-6935 and 606936. A joint NASA-USAF program was mapped out in June 1969. NASA and Air Force technicians spent three months readying 935 for flight. On 11 December 1969, the flight program got underway with a successful maiden flight piloted by Col. Joe Rogers and Maj. Gary Heidelbaugh of the SR-71/F-12 Test Force. During the program, the Air Force concentrated on military applications, and NASA pursued a loads research program. NASA studies included inflight heating, skin-friction cooling, 'coldwall' research (a heat transfer experiment), flowfield studies, shaker vane research, and tests in support of the Space Shuttle landing program. Ultimately, 935 became the workhorse of the program, with 146 flights between 11 December 1969 and 7 November 1979. The second YF-12A, 936, made

  15. Delta Electroproduction in 12-C

    SciTech Connect

    McLauchlan, Steven

    2003-01-01

    The Δ-nucleus potential is a crucial element in the understanding of the nuclear system. Previous electroexcitation measurements in the delta region reported a Q2 dependence of the Δ mass indicating that this potential is dependent on the momentum of the Δ. Such a dependence is not observed for protons and neutrons in the nuclear medium. This thesis presents the experimental study of the electroexcitation of the Δ resonance in 12C, performed using the high energy electron beam at the Thomas Jefferson National Accelerator Facility, and the near 4π acceptance detector CLAS that enables the detection of the full reaction final state. Inclusive, semi inclusive, and exclusive cross sections were measured with an incident electron beam energy of 1.162GeV over the Q2 range 0.175-0.475 (GeV/c)2. A Q2 dependence of the Δ mass was only observed in the exclusive measurements indicating that the Δ-nucleus potential is affected by the momentum of the Δ.

  16. Beta-decay studies of states in 12C

    NASA Astrophysics Data System (ADS)

    Pedersen, Solveig; Alcorta, M.; Borge, M. J. G.; Brandenburg, S.; Büscher, J.; Dendooven, P.; Diget, C. Aa.; Van Duppen, P.; Fulton, B.; Fynbo, H. O. U.; Huyse, M.; Jokinen, A.; Jonson, B.; Jungmann, K.; Madurga, M.; Nyman, G.; Onderwater, C. J. G.; Perajärvi, K.; Raabe, R.; Riisager, K.; Rogachevskiy, A.; Saastamoinen, A.; Sohani, M.; Tengblad, O.; Traykov, E.; Wilschut, H. W.; Äystö, J.

    The interest in experimental studies of the 12 C nucleus is partly due to the astrophysical interest in its spectroscopic properties, which determine the triple alpha reaction rate, and partly motivated by the structure of this nucleus, which is not fully explained theoretically. Some aspects are described in the shell model and others by a cluster structure of three alpha particles, but both cannot so far be combined in a unified model. New experiments have been performed to address these problems. The focus of this work is on an implantation experiment, which took place in April 2006 at KVI.

  17. /sup 18/O + /sup 12/C fusion-evaporation reaction

    SciTech Connect

    Heusch, B; Beck, C; Coffin, J P; Freeman, R M; Gallmann, A; Haas, F; Rami, F; Wagner, P; Alburger, D E

    1980-01-01

    A study of the /sup 18/O + /sup 12/C fusion evaporation reaction has been undertaken for 2 reasons: to make a systematic study of the formation cross section for each individual evaporation residue over a broad excitation energy region in the compound nucleus /sup 30/Si:30 to 62 MeV; and to compare all results to fusion-evaporation calculations done in the framework of the Hauser-Feschbach statistical model.

  18. Study of the diffraction scattering 12C + 12C with the excitation of the 12C exotic state 0{2/+} (the Hoyle state)

    NASA Astrophysics Data System (ADS)

    Maslov, V. A.; Astabatyan, R. A.; Damaskin, V. A.; Ivanov, M. P.; Kalpakchieva, R.; Kul'ko, A. A.; Lukyanov, S. M.; Penionzhkevich, Yu. E.; Revenko, R. V.; Skobelev, N. K.; Testov, D. A.; Goncharov, S. A.; Danilov, A. N.; Demyanova, A. S.; Ogloblin, A. A.; Dlougy, Z.

    2011-01-01

    New results from a series of experiments dedicated to the study of the 12C exotic state (the so-called Hoyle state) are presented. In spite of the many investigations that have been carried out, the structure of this state (which lies above the threshold for breaking up into three alpha particles) is still unknown. The different models assume that the nucleus has an abnormally large size in this excited state. However, until recently, methods for measuring the radii of unbound states have not been suggested. The best way to solve this problem seems to be by measuring the angular distributions of elastic and inelastic scattering of 12C on different target nuclei, and the determination of the radii is based on the fact that, at small scattering angles, the cross sections for direct reactions at high enough energies behave like Frauenhofer diffraction on a black ball. Accordingly, an experiment was performed aimed at measuring the elastic and inelastic angular distributions of 12C with an energy of (121.5 ± 0.5) MeV on a 12C target. The elastic scattering was measured in the angular range from 18° to 50° in the c.m. system with uncertainty in the angle of measurement equal to Δθ = ± 0.6°. The inelastic cross section was measured for the 12C excited state 2+ (4.44 MeV) and 0+ (7.65 MeV). Estimates were made for the diffraction radii for the ground and excited states. An increase was observed in the radius of the state at 7.65 MeV compared to those of the ground and first excited states.

  19. Analysis of 12C+12C Elastic and Inelastic Scatterings in the Framework of the Cluster Double Folding Model and Coupled-Channels Mechanism

    NASA Astrophysics Data System (ADS)

    Hassanain, M. A.

    2011-08-01

    A double folding cluster (DFC) model is proposed for the analysis of (12) C+(12) C elastic and inelastic scatterings. The DFC procedure is performed using the alpha-clusters structure of (12) C nucleus. Angular distributions of the (12) C+(12) C elastic and inelastic scatterings in the energy range 70.7-126 MeV were analyzed using the derived DFC potentials in the framework of the coupled-channels (CC) mechanism. Successful descriptions of the data are obtained over the full measured angular range without the need to normalize the DFC potentials. Furthermore, the deduced deformation length and the quadrupole deformation parameter are quite consistent with the corresponding electromagnetic measurements.

  20. Search for 12 C + 12 C clustering in 24 M g ground state

    NASA Astrophysics Data System (ADS)

    Joshi, B. N.; Jain, Arun K.; Biswas, D. C.; John, B. V.; Gupta, Y. K.; Danu, L. S.; Vind, R. P.; Prajapati, G. K.; Mukhopadhyay, S.; Saxena, A.

    2017-02-01

    In the backdrop of many models, the heavy cluster structure of the ground state of 24Mg has been probed experimentally for the first time using the heavy cluster knockout reaction 24Mg(12C,212C)12C in the quasifree scattering kinematic domain. In the (12C,212C) reaction, the direct 12C-knockout cross-section was found to be very small. Finite-range knockout theory predictions were much larger for (12C,212C) reaction, indicating a very small 12C-12C clustering in 24Mg(g.s.). Our present results contradict most of the proposed heavy cluster (12C+12C) structure models for the ground state of 24Mg.

  1. Cluster correlation effects in 12C+12C and 14N+10B fusion-evaporation reactions

    NASA Astrophysics Data System (ADS)

    Morelli, L.; Baiocco, G.; D'Agostino, M.; Gulminelli, F.; Bruno, M.; Cinausero, M.; Degerlier, M.; Fabris, D.; Gramegna, F.; Marchi, T.; Barlini, S.; Bini, M.; Casini, G.; Gelli, N.; Olmi, A.; Pasquali, G.; Piantelli, S.; Valdré, S.

    2015-04-01

    The decay of highly excited states of 24Mg is studied in fusion evaporation events completely detected in charge in the reactions 12C+12C and 14N+10B at 95 and 80 MeV incident energy respectively. The comparison of light charged particles measured spectra with statistical model predictions suggests that the dominant reaction mechanism is compound nucleus (CN) formation and decay. However, in both reactions, a discrepancy with statistical expectations is found for α particles detected in coincidence with Carbon, Oxigen and Neon residues. The comparison between the two reactions shows that this discrepancy is only partly explained by an entrance channel effect. Evidence for cluster correlations in excited 24Mg CN is suggested by the comparison between the measured and calculated branching ratios for the channels involving α particles.

  2. The C-12/C-13 abundance ratio in Comet Halley

    SciTech Connect

    Wyckoff, S.; Lindholm, E.; Wehinger, P.A.; Peterson, B.A.; Zucconi, J.M.

    1989-04-01

    The individual (C-13)N rotational lines in Comet Halley are resolved using high-resolution spectra of the CN B2Sigma(+)-X2Sigma(+) (0,0) band. The observe C-12/C-13 abundance ratio excludes a site of origin for the comet near Uranus and Neptune and suggests a condensation environment quite distinct from other solar system bodies. Two theories are presented for the origin of Comet Halley. One theory suggest that the comet originated 4.5 Gyr ago in an inner Oort cloud at a heliocentric distance greater than 100 AU where chemical fractionation led to the C-13 enrichment in the CN parent molecule prior to condensation of the comet nucleus. According to the other, more plausible theory, the comet nucleus condensed relatively recently from the interstellar medium which has become enriches in C-13 and was subsequently gravitationally captured by the solar system. 107 refs.

  3. Evidence of enhanced radius of Hoyle rotational state in12C inelastic scattering

    NASA Astrophysics Data System (ADS)

    Ito, M.

    2017-06-01

    Nuclear radius of three α rotational state in12C with a life time of 10-21 second, which has been expected to have much more extended radius than the ground12C nucleus, is speculated from systematic analysis of the differential cross section of the α +12C inelastic scattering. Present analysis predicts about 0.6 ∼ 1.0 fm enhancement in the matter radius of the three α rotational state in comparison to the normal radius of the ground state. The spatial extension of the three α rotational state is comparable to the extended radius observed in the neutron halo phenomena.

  4. Fusion measurements of 12C+12C at energies of astrophysical interest

    NASA Astrophysics Data System (ADS)

    Santiago-Gonzalez, D.; Jiang, C. L.; Rehm, K. E.; Alcorta, M.; Almaraz-Calderon, S.; Avila, M. L.; Ayangeakaa, A. D.; Back, B. B.; Bourgin, D.; Bucher, B.; Carpenter, M. P.; Courtin, S.; David, H. M.; Deibel, C. M.; Dickerson, C.; DiGiovine, B.; Fang, X.; Greene, J. P.; Haas, F.; Henderson, D. J.; Janssens, R. V. F.; Jenkins, D.; Lai, J.; Lauritsen, T.; Lefebvre-Schuhl, A.; Montanari, D.; Pardo, R. C.; Paul, M.; Seweryniak, D.; Tang, X. D.; Ugalde, C.; Zhu, S.

    2016-05-01

    The cross section of the 12C+12C fusion reaction at low energies is of paramount importance for models of stellar nucleosynthesis in different astrophysical scenarios, such as Type Ia supernovae and Xray superbursts, where this reaction is a primary route for the production of heavier elements. In a series of experiments performed at Argonne National Laboratory, using Gammasphere and an array of Silicon detectors, measurements of the fusion cross section of 12C+12C were successfully carried out with the γ and charged-particle coincidence technique in the center-of-mass energy range of 3-5 MeV. These were the first background-free fusion cross section measurements for 12C+12C at energies of astrophysical interest. Our results are consistent with previous measurements in the high-energy region; however, our lowest energy measurement indicates a fusion cross section slightly lower than those obtained with other techniques.

  5. Transverse electromagnetic form factor in 12C

    NASA Astrophysics Data System (ADS)

    Cha, D.

    1980-04-01

    We calculate the contribution from the convection current to the recently measured transverse form factor of the 12C 2+ level at 4.44 MeV. The convection current dominates for small momentum transfer and is determined by the B(E 2). In this region, theory agrees with experiment. At intermediate momentum transfer, agreement with experiment is only possible assuming a coherent sum of the convection current and magnetization density contributions. NUCLEAR STRUCTURE 12C, E=4.44 MeV; calculated FT2.

  6. Nucleus-nucleus potentials

    SciTech Connect

    Satchler, G.R.

    1983-01-01

    The significance of a nucleus-nucleus potential is discussed. Information about such potentials obtained from scattering experiments is reviewed, including recent examples of so-called rainbow scattering that probe the potential at smaller distances. The evidence for interactions involving the nuclear spins is summarized, and their possible origin in couplings to non-elastic channels. Various models of the potentials are discussed.

  7. The β-decay approach for studying 12C

    NASA Astrophysics Data System (ADS)

    Fynbo, H. O. U.; Diget, C. Aa; Hyldegaard, S.; Jeppesen, H. B.; Knudsen, H. H.; Kirsebom, O.; Riisager, K.; Alcorta, M.; Boutami, R.; Borge, M. J. G.; Madurga, M.; Tengblad, O.; Brandenburg, S.; Dendooven, P.; Jungmann, K.; Onderwater, G. J. G.; Rogachevskly, A.; Sohani, M.; Traykov, E.; Wilschut, H. W.; Büscher, J.; Van Duppen, P.; Huyse, M.; Raabe, R.; Eronen, T.; Huikary, J.; Jokinen, A.; Kankainen, A.; Perajärvi, K.; Moore, I.; Nieminen, A.; Penttilä, H.; Rinta-Antila, S.; Saastamoinen, A.; Wang, Y.; Äystö, J.; Jonson, B.; Nilsson, T.; Nyman, G.; Wilhelmsen, K.; Fulton, B.; Fox, S.; Barker, F. C.

    2008-05-01

    The β-decays of the mirror nuclei 12B and 12N both populate states in 12C and they are therefore a precious source of information about this nucleus. Due to the selection rules of β-decay only 0+, 1+ and 2+ states are populated. This allows a very clean study of unbound states just above the 3α-threshold with those spin and parities. This probe has been applied in two experiments using two complementary experimental techniques: in the first the three α-particles emitted after β-decay are measured in coincidence in separate detectors using the ISOL method, while in the second method 12B and 12N are implanted in a detector and the summed energy of the three α-particles is measured directly. Preliminary results from the two approaches are presented.

  8. Folding model calculations for 6He+12C elastic scattering

    NASA Astrophysics Data System (ADS)

    Awad, A. Ibraheem

    2016-03-01

    In the framework of the double folding model, we used the α+2n and di-triton configurations for the nuclear matter density of the 6He nucleus to generate the real part of the optical potential for the system 6He+12C. As an alternative, we also use the high energy approximation to generate the optical potential for the same system. The derived potentials are employed to analyze the elastic scattering differential cross section at energies of 38.3, 41.6 and 82.3 MeV/u. For the imaginary part of the potential we adopt the squared Woods-Saxon form. The obtained results are compared with the corresponding measured data as well as with available results in the literature. The calculated total reaction cross sections are investigated and compared with the optical limit Glauber model description.

  9. The 12C(12C,α)20Ne and 12C(12C,p)23Na reactions at the Gamow peak via the Trojan Horse Method

    NASA Astrophysics Data System (ADS)

    Tumino, A.; Spitaleri, C.; Cherubini, S.; Guardo, L.; Gulino, M.; Indelicato, I.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Spartá, R.

    2016-05-01

    A measurement of the 12C(14N,α20Ne)2H and 12C(14N,p23Na)2Hreactions has been performed at a 14N beam energy of 30.0 MeV. The experiment aims to explore the extent to which contributing 24Mg excited states can be populated in the quasi-free reaction off the deuteron in 14N. In particular, the 24Mg excitation region explored in the measurement plays a key role in stellar carbon burning whose cross section is commonly determined by extrapolating high-energy fusion data. From preliminary results, α and proton channels are clearly identified. In particular, ground and first excited states of 20Ne and 23Na play a major role.

  10. First Direct Measurement of (12)C((12)C,n)(23)Mg at Stellar Energies.

    PubMed

    Bucher, B; Tang, X D; Fang, X; Heger, A; Almaraz-Calderon, S; Alongi, A; Ayangeakaa, A D; Beard, M; Best, A; Browne, J; Cahillane, C; Couder, M; deBoer, R J; Kontos, A; Lamm, L; Li, Y J; Long, A; Lu, W; Lyons, S; Notani, M; Patel, D; Paul, N; Pignatari, M; Roberts, A; Robertson, D; Smith, K; Stech, E; Talwar, R; Tan, W P; Wiescher, M; Woosley, S E

    2015-06-26

    Neutrons produced by the carbon fusion reaction (12)C((12)C,n)(23)Mg play an important role in stellar nucleosynthesis. However, past studies have shown large discrepancies between experimental data and theory, leading to an uncertain cross section extrapolation at astrophysical energies. We present the first direct measurement that extends deep into the astrophysical energy range along with a new and improved extrapolation technique based on experimental data from the mirror reaction (12)C((12)C,p)(23)Na. The new reaction rate has been determined with a well-defined uncertainty that exceeds the precision required by astrophysics models. Using our constrained rate, we find that (12)C((12)C,n)(23)Mg is crucial to the production of Na and Al in pop-III pair instability supernovae. It also plays a nonnegligible role in the production of weak s-process elements, as well as in the production of the important galactic γ-ray emitter (60)Fe.

  11. Microwave Spectrum of 12C16O

    NASA Astrophysics Data System (ADS)

    Tashkun, S. A.; Mikhailenko, S. N.

    2010-06-01

    12C16O microwave spectrum of the 0-0,1-1,2-2, and 3-3 bands up to J=50 will be presented. The spectrum was calculated from an experimental dataset of energy levels. Calculated frequencies are given together with 99% confidence intervals. Comparison of the spectrum with microwave data containing in spectroscopic databanks will be discussed. This work was supported by CRDF (USA) Grant RUG1-2954-TO-09 and by RFBR. Grant 09-05-92508. S.A. Tashkun, T.I. Velichko, S.N. Mikhailenko, JQSRT, in press (2010).

  12. YF-12C in flight at sunset

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The so-called YF-12C in flight at sunset. The YF-12C was the second production SR-71A (61-7951), modified with YF-12A inlets and engines, and given a bogus tail number (06937). It replaced a YF-12A (60-6936) that crashed during a joint USAF-NASA research program. The Flight Research Center's involvement with the YF-12A, an interceptor version of the Lockheed A-12, began in 1967. Ames Research Center was interested in using wind tunnel data that had been generated at Ames under extreme secrecy. Also, the Office of Advanced Research and Technology (OART) saw the YF-12A as a means to advance high-speed technology, which would help in designing the Supersonic Transport (SST). The Air Force needed technical assistance to get the latest reconnaissance version of the A-12 family, the SR-71A, fully operational. Eventually, the Air Force offered NASA the use of two YF-12A aircraft, 60-6935 and 60-6936. A joint NASA-USAF program was mapped out in June 1969. NASA and Air Force technicians spent three months readying 935 for flight. On 11 December 1969, the flight program got underway with a successful maiden flight piloted by Col. Joe Rogers and Maj. Gary Heidelbaugh of the SR-71/F-12 Test Force. During the program, the Air Force concentrated on military applications, and NASA pursued a loads research program. NASA studies included inflight heating, skin-friction cooling, 'coldwall' research (a heat transfer experiment), flowfield studies, shaker vane research, and tests in support of the Space Shuttle landing program. Ultimately, 935 became the workhorse of the program, with 146 flights between 11 December 1969 and 7 November 1979. The second YF-12A, 936, made 62 flights. It was lost in a non-fatal crash on 24 June 1971. It was replaced by the YF-12C. The YF-12C was delivered to NASA on 16 July 1971. From then until 22 December 1978, it made 90 flights. The Lockheed A-12 family, known as the Blackbirds, were designed by Clarence 'Kelly' Johnson. They were constructed mostly

  13. YF-12C in flight at sunset

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The so-called YF-12C in flight at sunset. The YF-12C was the second production SR-71A (61-7951), modified with YF-12A inlets and engines, and given a bogus tail number (06937). It replaced a YF-12A (60-6936) that crashed during a joint USAF-NASA research program. The Flight Research Center's involvement with the YF-12A, an interceptor version of the Lockheed A-12, began in 1967. Ames Research Center was interested in using wind tunnel data that had been generated at Ames under extreme secrecy. Also, the Office of Advanced Research and Technology (OART) saw the YF-12A as a means to advance high-speed technology, which would help in designing the Supersonic Transport (SST). The Air Force needed technical assistance to get the latest reconnaissance version of the A-12 family, the SR-71A, fully operational. Eventually, the Air Force offered NASA the use of two YF-12A aircraft, 60-6935 and 60-6936. A joint NASA-USAF program was mapped out in June 1969. NASA and Air Force technicians spent three months readying 935 for flight. On 11 December 1969, the flight program got underway with a successful maiden flight piloted by Col. Joe Rogers and Maj. Gary Heidelbaugh of the SR-71/F-12 Test Force. During the program, the Air Force concentrated on military applications, and NASA pursued a loads research program. NASA studies included inflight heating, skin-friction cooling, 'coldwall' research (a heat transfer experiment), flowfield studies, shaker vane research, and tests in support of the Space Shuttle landing program. Ultimately, 935 became the workhorse of the program, with 146 flights between 11 December 1969 and 7 November 1979. The second YF-12A, 936, made 62 flights. It was lost in a non-fatal crash on 24 June 1971. It was replaced by the YF-12C. The YF-12C was delivered to NASA on 16 July 1971. From then until 22 December 1978, it made 90 flights. The Lockheed A-12 family, known as the Blackbirds, were designed by Clarence 'Kelly' Johnson. They were constructed mostly

  14. Investigation of the /sup 12/C(. gamma. ,pn) reaction using tagged photons

    SciTech Connect

    Dancer, S.N.; MacGregor, I.J.D.; Annand, J.R.M.; Anthony, I.; Crawford, G.I.; Hall, S.J.; Kellie, J.D.; McGeorge, J.C.; Owens, R.O.; Wallace, P.A.; and others

    1988-09-05

    Tagged-photon measuremens of the /sup 12/C(..gamma..,pn) reaction in the photon energy range 83--133 MeV are reported. The measurements have achieved a good angular resolution, approx. =4/sup 0/, and a better missing-energy resolution, approx. =8 MeV, than any previous measurement. This has allowed events to be selected in which both the neutron and proton are ejected from the 1p shell of the /sup 12/C nucleus. The correlated momenta of the outgoing nucleon pairs are quantitatively explained by the quasideuteron mechanism.

  15. Recent Findings in Relativistic Dissociation of {}^{10}B and {}^{12}C Nuclei

    NASA Astrophysics Data System (ADS)

    Artemenkov, D. A.; Mamatkulov, K. Z.; Kharlamov, S. P.; Zaitsev, A. A.; Zarubin, P. I.

    2017-03-01

    Recent findings related with the unstable nuclei ^8Be and ^9B in the coherent dissociation of relativistic nuclei ^{10}C, ^{10}B and ^{12}C in nuclear track emulsion ("white" stars) are highlighted The ^8Be_{g.s.} nucleus is manifested in the coherent dissociation ^{10}B → 2He + H with a probability of 25 ± 5% including 14 ± 3% of ^9B decays. A probability ratio of the mirror channels ^9B + n and ^9Be + p is estimated to be 6 ± 1. Reanalysis of relativistic ^{12}C dissociation in lead enriched emulsion revealed nine 3α -events corresponding to the Hoyle state.

  16. Ab initio calculations of ^12C and neutron drops

    NASA Astrophysics Data System (ADS)

    Pieper, Steven C.

    2009-10-01

    Ab initio calculations of nuclei, which treat a nucleus as a system of A nucleons interacting by realistic two- and three-nucleon forces, have made tremendous progress in the last 15 years. This is a result of better Hamiltonians, rapidly increasing computer power, and new or improved many-body methods. Three methods are principally being used: Green's function Monte Carlo (GFMC), no-core shell model, and coupled cluster. In the limit of large computer resources, all three methods produce exact eigenvalues of a given nuclear Hamiltonian. With DOE SciDAC and INCITE support, all three methods are using the largest computers available today. Under the UNEDF SciDAC grant, the Argonne GFMC program was modified to efficiently use more than 2000 processors. E. Lusk (Argonne), R.M. Butler (Middle Tennessee State U.) and I have developed an Asynchronous Dynamic Load-Balancing (ADLB) library. In addition all the cores in a node are used via OpenMP as one ADLB/MPI client. In this way we obtain very good scalability up to 30,000 processors on Argonne's IBM Blue Gene/P. Two systems of particular interest that require this computer power are ^12C and neutron drops. V.R. Pandharipande (UIUC, deceased), J. Carlson (LANL), R.B. Wiringa (Argonne), and I have developed new trial wave functions that explicitly contain the three-alpha particle structure of ^12C. These are being used with the Argonne V18 and Illinois-7 potentials which reproduce the energies of 51 states in 3<=A<=12 nuclei with an rms error of 600,eV. Neutron drops are collections of neutrons confined in an artificial external well and interacting with realistic NN and NNN potentials. Their properties can be used as ``experimental data'' for developing energy-density functionals.

  17. Energy dependence of 12C+12C single-neutron transfer cross sections

    NASA Astrophysics Data System (ADS)

    Winfield, J. S.; Austin, Sam M.; Crawley, G. M.; Djalali, C.; Ogilvie, C. A.; Smith, R. J.; Chen, Ziping; Torres, M.

    1988-04-01

    The one-neutron transfer reaction induced by 25, 35 and 50 MeV/nucleon 12C beams on a 12C target has been studied. The observed angular distributions for the 13Cg.s-11Cg.s. final state agree in shape and magnitude with predictions of the exact finite- range distorted wave Born approximation. Above roughly 30 MeV/nucleon, the angel integrated cross section falls off with an approximately exponential slope in accordance with the expectations of the reaction dynamics at high bombarding energies. Present address: Department of Health Physics, University of Michigan, Ann Arbor, MI 48109, USA.

  18. Probing the Statistical Decay and α-clustering effects in 12C + 12C and 14N + 10B reactions

    NASA Astrophysics Data System (ADS)

    Morelli, L.; Baiocco, G.; D'Agostino, M.; Bruno, M.; Gulminelli, F.; Cinausero, M.; Degerlier, M.; Fabris, D.; Gramegna, F.; Marchi, T.; Barlini, S.; Bini, M.; Casini, G.; Gelli, N.; Lopez, A.; Pasquali, G.; Piantelli, S.; Valdrè, S.

    2014-03-01

    An experimental campaign has been undertaken at Laboratori Nazionali di Legnaro (LNL INFN), Italy, in order to progress in our understanding of the statistical properties of light nuclei at excitation energies above particle emission threshold, by measuring exclusive data from fusion-evaporation reactions. On the experimental side, a first reaction: 12C+12C at 95 MeV beam energy has been measured, using the GARFIELD + Ring Counter (RCo) apparatuses. Fusion-evaporation events have been exclusively selected out of the entire data set. The comparison to a dedicated Hauser-Feshbach calculation allows us to give constraints on the nuclear level density at high excitation energy for light systems ranging from C up to Mg. Out-of-equilibrium aα emission has been evidenced and attributed both to an entrance channel effect (favoured by the cluster nature of reaction partners), and, in more dissipative events, to the persistence of cluster correlations well above the 24Mg threshold for 6 α's decay. In order to study the same 24Mg compound nucleus at similar excitation energy with respect to this first reaction a new measurement, 14N + 10B at 5.7 A.MeV, was performed at LNL laboratories with the same experimental setup. The comparison between the two systems would allow us to further constrain the level density of light nuclei in the mass-excitation energy range of interest. In this perspective, deviations from a statistical behaviour can be used as a tool to get information on nuclear clustering, both in the ground-state for projectile and target and in the hot source formed in the collision.

  19. The Hoyle state in 12C

    NASA Astrophysics Data System (ADS)

    Freer, M.; Fynbo, H. O. U.

    2014-09-01

    The 7.65 MeV, Jπ=0+, second excited state in 12C is known as the Hoyle-state after Fred Hoyle. In the 1950s Hoyle proposed the existence of the state in order to account for the stellar abundance of carbon. Aside from its key role in the synthesis of the elements it is believed to possess a rather unusual structure, where the dominant degrees of freedom are those of α-particle clusters rather than nucleons. An understanding of the properties of the Hoyle state, for example its radius and excitations, has been the focus of a major experimental activity. Similarly, unravelling precisely why a cluster state should arise at precisely the right energy to promote synthesis of carbon has been a central theoretical challenge. To a significant extent, the Hoyle-state has become a cornerstone for state-of-the-art nuclear theory. This review examines the present status of both theory and experiment and indicates directions for future developments to resolve some of the remaining open questions.

  20. Spin alignment and density matrix measurement in sup 28 Si + sup 12 C orbiting reaction

    SciTech Connect

    Ray, A.; Shapira, D.; Halbert, M.L.; Gomez del Campo, J.; Kim, H.J. ); Sullivan, J.P. . Cyclotron Inst.); Shivakumar, B.; Mitchell, J. . Wright Nuclear Structure Lab.)

    1990-01-01

    Gamma-ray angular correlations have been measured for the strongly damped reactions {sup 12}C({sup 28}Si,{sup 12}C){sup 28}Si between {theta}{sub cm} = (120{degree} {minus} 160{degree}) for E{sub cm} = 43.5 and 48 MeV. We find that the density matrices for the {sup 12}C(2{sub 1}{sup +}) and {sup 28}Si states are almost diagonal with respect to the direction of motion of the outgoing particle. The measured density matrices and spin alignments are consistent with the picture of formation of a long-lived dinuclear complex undergoing orbiting, bending and wriggling motions, but not with those obtained from statistical compound nucleus or sticking model calculations. 17 refs., 2 figs., 1 tab.

  1. Decay strength distributions in {sup 12}C({sup 12}C,{gamma}) radiative capture

    SciTech Connect

    Jenkins, D. G.; Fulton, B. R.; Marley, P.; Fox, S. P.; Glover, R.; Wadsworth, R.; Watson, D. L.; Courtin, S.; Haas, F.; Lebhertz, D.; Beck, C.; Papka, P.; Rousseau, M.; Sanchez i Zafra, A.; Hutcheon, D. A.; Davis, C.; Ottewell, D.; Pavan, M. M.; Pearson, J.; Ruiz, C.

    2007-10-15

    The heavy-ion radiative capture reaction, {sup 12}C({sup 12}C,{gamma}), has been investigated at energies both on- and off-resonance, with a particular focus on known resonances at E{sub c.m.}=6.0, 6.8, 7.5, and 8.0 MeV. Gamma rays detected in a BGO scintillator array were recorded in coincidence with {sup 24}Mg residues at the focal plane of the DRAGON recoil separator at TRIUMF. In this manner, the relative strength of all decay pathways through excited states up to the particle threshold could be examined for the first time. Isovector M1 transitions are found to be a important component of the radiative capture from the E{sub c.m.}=6.0 and 6.8 MeV resonances. Comparison with Monte Carlo simulations suggests that these resonances may have either J=0 or 2, with a preference for J=2. The higher energy resonances at E{sub c.m.}=7.5 and 8.0 MeV have a rather different decay pattern. The former is a clear candidate for a J=4 resonance, whereas the latter has a dominant J=4 character superposed on a J=2 resonant component underneath. The relationship between these resonances and the well-known quasimolecular resonances as well as resonances in breakup and electrofission of {sup 24}Mg into two {sup 12}C nuclei are discussed.

  2. Measurement of the ^12C+^12C Fusion Reaction with MUSIC

    NASA Astrophysics Data System (ADS)

    Carnelli, P. F. F.; Almaraz-Calderon, S.; Henderson, D.; Rehm, K. E.; Albers, M.; Alcorta, M.; Bertone, P. F.; Esbensen, H.; Fernandez-Niello, J. O.; Jiang, C. L.; Lighthall, J. C.; Marley, S. T.; Palchan-Hazan, T.; Pardo, R. C.; Paul, M.

    2012-10-01

    The fusion of the ^12C+^12C system is of great interest in nuclear structure and nuclear astrophysics. Above the Coulomb barrier, the excitation function of this system exhibits oscillations, which are not well understood. There is also a significant discrepancy between the experimental fusion cross-section and recent coupled-channel calculations that is not present in other carbon systems. To address these issues, we have re-measured the fusion excitation function for ^12,13C+^12C in the energy range of 10 MeV < Ecm < 20 MeV using a Multi-Sampling Ionization Chamber (MUSIC) detector. The gas of the ionization chamber (CH4) served as both the target material and the counter gas. One of the main advantages of this method is that the excitation function is measured over a large range of energies using only one beam energy. This method has been proven to be successful and it will be used to measure fusion reactions in other light systems. The experimental results will be presented and compared to previous experimental data and theoretical models.

  3. Current and Future Tests of the Algebraic Cluster Model of12C

    NASA Astrophysics Data System (ADS)

    Gai, Moshe

    2017-07-01

    A new theoretical approach to clustering in the frame of the Algebraic Cluster Model (ACM) has been developed. It predicts, in12C, rotation-vibration structure with rotational bands of an oblate equilateral triangular symmetric spinning top with a D 3h symmetry characterized by the sequence of states: 0+, 2+, 3-, 4±, 5- with a degenerate 4+ and 4- (parity doublet) states. Our newly measured {2}2+ state in12C allows the first study of rotation-vibration structure in12C. The newly measured 5- state and 4- states fit very well the predicted ground state rotational band structure with the predicted sequence of states: 0+, 2+, 3-, 4±, 5- with almost degenerate 4+ and 4- (parity doublet) states. Such a D 3h symmetry is characteristic of triatomic molecules, but it is observed in the ground state rotational band of12C for the first time in a nucleus. We discuss predictions of the ACM of other rotation-vibration bands in12C such as the (0+) Hoyle band and the (1-) bending mode with prediction of (“missing 3- and 4-”) states that may shed new light on clustering in12C and light nuclei. In particular, the observation (or non observation) of the predicted (“missing”) states in the Hoyle band will allow us to conclude the geometrical arrangement of the three alpha particles composing the Hoyle state at 7.6542 MeV in12C. We discuss proposed research programs at the Darmstadt S- DALINAC and at the newly constructed ELI-NP facility near Bucharest to test the predictions of the ACM in isotopes of carbon.

  4. Solving the {sup 12}C+{sup 12}C scattering puzzle: is there the '4th elephant'?

    SciTech Connect

    Demyanova, A. S.; Danilov, A. N.; Ogloblin, A. A.; Goncharov, S. A.; Bohlen, H. G.; Khlebnikov, S. V.; Tyurin, G. P.; Maslov, V. A.; Penionzkevich, Yu. E.; Sobolev, Yu. G.; Trzaska, W.

    2010-04-30

    Differential cross sections of the {sup 12}C+{sup 12}C and the {sup 13}C+{sup 12}C elastic scattering were measured at the projectile energies 240 MeV ({sup 12}C) and 250 MeV ({sup 13}C) up to the largest angles. The positions of the 1{sup st} Airy minima known from the former experiments were confirmed.

  5. Thermal properties of light nuclei from 12C + 12C fusion-evaporation reactions

    NASA Astrophysics Data System (ADS)

    Morelli, L.; Baiocco, G.; D'Agostino, M.; Gulminelli, F.; Bruno, M.; Abbondanno, U.; Appannababu, S.; Barlini, S.; Bini, M.; Casini, G.; Cinausero, M.; Degerlier, M.; Fabris, D.; Gelli, N.; Gramegna, F.; Kravchuk, V. L.; Marchi, T.; Olmi, A.; Pasquali, G.; Piantelli, S.; Valdré, S.; Raduta, Ad R.

    2014-07-01

    The 12C + 12C reaction at 95 MeV has been studied through the complete charge identification of its products by means of the GARFIELD+RCo experimental set-up at INFN Laboratori Nazionali di Legnaro (LNL). In this paper, the first of a series of two, a comparison to a dedicated Hauser-Feshbach calculation allows selecting a set of dissipative events which corresponds, to a large extent, to the statistical evaporation of highly excited 24Mg. Information on the isotopic distribution of the evaporation residues in coincidence with their complete evaporation chain is also extracted. The set of data puts strong constraints on the behaviour of the level density (LD) of light nuclei above the threshold for particle emission. In particular, a fast increase of the LD parameter with excitation energy is supported by the data. Residual deviations from a statistical behaviour are seen in two specific channels, and tentatively associated with a contamination from direct reactions and/or α-clustering effects. These channels are studied in further details in the second paper of the series.

  6. Investigation of proton-proton short-range correlations via the 12C(e,e'pp) reaction.

    PubMed

    Shneor, R; Monaghan, P; Subedi, R; Anderson, B D; Aniol, K; Annand, J; Arrington, J; Benaoum, H; Benmokhtar, F; Bertin, P; Bertozzi, W; Boeglin, W; Chen, J P; Choi, Seonho; Chudakov, E; Cisbani, E; Craver, B; de Jager, C W; Feuerbach, R J; Frullani, S; Garibaldi, F; Gayou, O; Gilad, S; Gilman, R; Glamazdin, O; Gomez, J; Hansen, J-O; Higinbotham, D W; Holmstrom, T; Ibrahim, H; Igarashi, R; Jans, E; Jiang, X; Jiang, Y; Kaufman, L; Kelleher, A; Kolarkar, A; Kuchina, E; Kumbartzki, G; LeRose, J J; Lindgren, R; Liyanage, N; Margaziotis, D J; Markowitz, P; Marrone, S; Mazouz, M; Meekins, D; Michaels, R; Moffit, B; Nanda, S; Perdrisat, C F; Piasetzky, E; Potokar, M; Punjabi, V; Qiang, Y; Reinhold, J; Reitz, B; Ron, G; Rosner, G; Saha, A; Sawatzky, B; Shahinyan, A; Sirca, S; Slifer, K; Solvignon, P; Sulkosky, V; Thompson, N; Ulmer, P E; Urciuoli, G M; Voutier, E; Wang, K; Watson, J W; Weinstein, L B; Wojtsekhowski, B; Wood, S; Yao, H; Zheng, X; Zhu, L

    2007-08-17

    We investigated simultaneously the 12C(e,e'p) and 12C(e,e'pp) reactions at Q2=2 (GeV/c)2, xB=1.2, and in an (e, e'p) missing-momentum range from 300 to 600 MeV/c. At these kinematics, with a missing momentum greater than the Fermi momentum of nucleons in a nucleus and far from the delta excitation, short-range nucleon-nucleon correlations are predicted to dominate the reaction. For (9.5+/-2)% of the 12C(e,e'p) events, a recoiling partner proton was observed back-to-back to the 12C(e,e'p) missing-momentum vector, an experimental signature of correlations.

  7. Investigation of Proton-Proton Short-Range Correlations via the 12C(e,e'pp) Reaction

    SciTech Connect

    J. Arrington; H. Benaoum; F. Benmokhtar; P. Bertin; W. Bertozzi; W. Boeglin; J. P. Chen; Seonho Choi; E. Chudakov; E. Cisbani; B. Craver; C. W. de Jager; R. Feuerbach; S. Frullani; F. Garibaldi; O. Gayou; S. Gilad; R. Gilman; O. Glamazdin; J. Gomez; O. Hansen; D. W. Higinbotham; T. Holmstrom; H. Ibrahim; R. Igarashi; E. Jans; X. Jiang; Y. Jiang; L. Kaufman; A. Kelleher; A. Kolarkar; E. Kuchina; G. Kumbartzki; J. J. LeRose; R. Lindgren; N. Liyanage; D. J. Margaziotis; P. Markowitz; S. Marrone; M. Mazouz; R. Michaels; B. Moffit; S. Nanda; C. F. Perdrisat; E. Piasetzky; M. Potokar; V. Punjabi; Y. Qiang; J. Reinhold; B. Reitz; G. Ron; G. Rosner; A. Saha; B. Sawatzky; A. Shahinyan; S. Sirca; K. Slifer; P. Solvignon; V. Sulkosky; N. Thompson; P. E. Ulmer; G. M. Urciuoli; E. Voutier; K. Wang; J. W. Watson

    2007-08-01

    We investigated simultaneously the 12C(e,e'p) and 12C(e,e'pp) reactions at Q2 = 2 [GeV/c]2, x_B = 1.2, and in an (e,e'p) missing-momentum range from 300 to 600 MeV/c. At these kinematics, with a missing-momentum greater than the Fermi momentum of nucleons in a nucleus and far from the delta excitation, short-range nucleon-nucleon correlations are predicted to dominate the reaction. For(9.5 +/- 2)% of the 12C(e,e'p) events, a recoiling partner proton was observed back-to-back to the 12C(e,e'p) missing momentum vector, an experimental signature of correlations.

  8. Probing the 12C - 12C and 12C - 16O Molecular States by Radiative Capture Reactions:. Present Status and Future

    NASA Astrophysics Data System (ADS)

    Lebhertz, D.; Courtin, S.; Haas, F.; Jenkins, D. G.; Ciemala, M.; Goasduff, A.; Hutcheon, D. A.; Labiche, M.; Michalon, A.; Roberts, O.; Salsac, M.-D.; Stezowski, O.

    Complete γ-decay in the 12C(12C,γ)24Mg and 12C(16O,γ)28Si reactions has been measured at energies close to the Coulomb Barrier using the DRAGON spectrometer and its associated BGO γ-array at the TRIUMF facility. The experimental data show an important feeding of doorway states around 10-11 MeV in both reactions. Comparisons with simulations allow to extract the full capture cross section and the main spin involved in the process. Different models are confronted to the results : completely statistical, semi-statistical with an unique entrance spin and cluster. The resolution of the BGO enables to eliminate a fully statistical scenario but is not enough to disentangle the two remaining scenarii. It is shown that the future PARIS array composed of the recently developed LaBr3 scintillators will have capabilities to distinguish between these two scenarii.

  9. Multi-cluster dynamics in C13Λ and analogy to clustering in 12C

    NASA Astrophysics Data System (ADS)

    Funaki, Y.; Isaka, M.; Hiyama, E.; Yamada, T.; Ikeda, K.

    2017-10-01

    We investigate structure of C13Λ and discuss the difference and similarity between the structures of 12C and C13Λ by answering the questions if the linear-chain and gaslike cluster states, which are proposed to appear in 12C, survives, or new structure states appear or not. We introduce a microscopic cluster model called, Hyper-Tohsaki-Horiuchi-Schuck-Röpke (H-THSR) wave function, which is an extended version of the THSR wave function so as to describe Λ hypernuclei. We obtained two bound states and two resonance (quasi-bound) states for Jπ =0+ in C13Λ, corresponding to the four 0+ states in 12C. However, the inversion of level ordering between the spectra of 12C and C13Λ, i.e. that the 03+ and 04+ states in C13Λ correspond to the 04+ and 03+ states in 12C, respectively, is shown to occur. The additional Λ particle reduces sizes of the 02+ and 03+ states in C13Λ very much, but the shrinkage of the 04+ state is only a half of the other states, in spite of the fact that attractive Λ-N interaction makes nucleus contracted so much when the Λ particle occupies an S-orbit. In conclusion, the Hoyle state becomes quite a compact object with Be9Λ + α configuration in C13Λ and is no more gaslike state composed of the 3α clusters. Instead, the 04+ state in C13Λ, coming from the 12C (03+) state, appears as a gaslike state composed of α + α +Λ5He configuration, i.e. the Hoyle analog state. A linear-chain state in a Λ hypernucleus is for the first time predicted to exist as the 03+ state in C13Λ with more shrunk arrangement of the 3α clusters along z-axis than the 3α linear-chain configuration realized in the 12C (04+) state. All the excited states are shown to appear around the corresponding cluster-decay threshold, reflecting the threshold rule.

  10. Coupling effects in the elastic scattering of 6He on 12C

    NASA Astrophysics Data System (ADS)

    Lapoux, V.; Alamanos, N.; Auger, F.; Fékou-Youmbi, V.; Gillibert, A.; Marie, F.; Ottini-Hustache, S.; Sida, J.-L.; Khoa, D. T.; Blumenfeld, Y.; Maréchal, F.; Scarpaci, J.-A.; Suomijärvi, T.; Kelley, J. H.; Casandjian, J.-M.; Chartier, M.; Cortina-Gil, M. D.; Mac Cormick, M.; Mittig, W.; de Oliveira Santos, F.; Ostrowski, A. N.; Roussel-Chomaz, P.; Kemper, K. W.; Orr, N.; Winfield, J. S.

    2002-09-01

    To study the effect of the weak binding energy on the interaction potential between a light exotic nucleus and a target, elastic scattering of 6He at 38.3 MeV/nucleon on a 12C target was measured at Grand Accélérateur National d'Ions Lourds (GANIL). The 6He beam was produced by fragmentation. The detection of the scattered particles was performed by the GANIL spectrometer. The energy resolution was good enough to separate elastic from inelastic scattering contributions. The measured elastic data have been analyzed within the optical model, with the real part of the optical potential calculated in the double-folding model using a realistic density-dependent nucleon-nucleon interaction and the imaginary part taken in the conventional Woods-Saxon (WS) form. A failure of the ``bare'' real folded potential to reproduce the measured angular distribution over the whole angular range suggests quite a strong coupling of the higher-order breakup channels to the elastic channel. To estimate the strength of the breakup effects, a complex surface potential with a repulsive real part (designed to simulate the polarization effects caused by the projectile breakup) was added to the real folded and imaginary WS potentials. A realistic estimate of the polarization potential caused by the breakup of the weakly bound 6He was made based on a parallel study of 6He+12C and 6Li+12C optical potentials at about the same energies.

  11. Monopole transition strength function of 12C in a three-α model

    NASA Astrophysics Data System (ADS)

    Ishikawa, Souichi

    2016-12-01

    The energy-level structure of the 12C nucleus at a few MeV above the three-α (3 α ) threshold is still unsatisfactorily known. For instance, most microscopic calculations predicted that there exist one 0+ state in this energy region besides the well-known Hoyle state, whereas some experimental and theoretical studies show the existence of two 0+ states. In this paper, I will take a 3 α -boson model for bound and continuum states in 12C and study a transition process from the 12C(01+) ground state to 3 α 0+ continuum states by the electric monopole (E 0 ) operator. The strength distribution of the process will be calculated as a function of 3 α energy using the Faddeev three-body theory. The Hamiltonian for the 3 α system consists of two- and three-α potentials, and some three-α potentials with different range parameters will be examined. Results of the strength function show a double-peaked bump at the low-energy region, which can be considered as two 0+ states. The peak at higher energy may originate from a 3 α resonant state. However, it is unlikely that the peak at the lower energy is related to a resonant state, which suggests that it may be due to a so-called "ghost anomaly." Distributions of decaying particles are also calculated.

  12. Preequilibrium processes in the fusion of {sup 12}C with {sup 103}Rh up to 20 MeV/nucleon

    SciTech Connect

    Birattari, C.; Bonardi, M.; Cavinato, M.; Fabrici, E.; Gadioli, E.; Gadioli Erba, E.; Groppi, F.; Bello, M.; Bovati, C.; Di Filippo, A. |; Stevens, T.G.; Connell, S.H.; Sellschop, J.P.; Mills, S.J.; Nortier, F.M.; Steyn, G.F.; Marchetta, C. |

    1996-12-01

    We have measured the excitation functions of several reactions occurring in the fusion of {sup 12}C with {sup 103}Rh at incident energies up to about 230 MeV. The data can be satisfactorily reproduced by considering the preequilibrium emission of particles during the thermalization of the composite nucleus. The energy evolution of the mean-field interaction is also discussed. {copyright} {ital 1996 The American Physical Society.}

  13. Quasielastic scattering of 8B and 7Be on 12C at 40 MeV/nucleon

    NASA Astrophysics Data System (ADS)

    Pecina, I.; Anne, R.; Bazin, D.; Borcea, C.; Borrel, V.; Carstoiu, F.; Corre, J. M.; Dlouhy, Z.; Fomitchev, A.; Guillemaud-Mueller, D.; Keller, H.; Kordyasz, A.; Lewitowicz, M.; Lukyanov, S.; Mueller, A. C.; Penionzhkevich, Yu.; Roussel-Chomaz, P.; Saint-Laurent, M. G.; Skobelev, N.; Sorlin, O.; Tarasov, O.

    1995-07-01

    The quasielastic scattering of the exotic nucleus 8B on a 12C target has been studied at an energy of 320 MeV and compared with that of 7Be at the same velocity. The quasielastic scattering of 12C + 12C at 20 MeV/nucleon, also performed as a secondary beam experiment, was used to check the data reduction method. The results are interpreted in terms of a semimicroscopic double folding model and coupled-channels calculation. The difference in the total reaction cross section (8%) between 8B and 7Be is consistent with the measured one proton removal cross section and corresponds to an increase in the interaction radius of 4%. The existence of a substantial proton halo in 8B is not supported by the present data.

  14. Terahertz Spectroscopy of the Bending Vibrations of Acetylene 12C2H2 and 12C2D2

    NASA Astrophysics Data System (ADS)

    Yu, Shanshan; Drouin, B.; Pearson, J.

    2009-12-01

    Several fundamental interstellar molecules, e.g., C2H2, CH4 and C3, are completely symmetric molecules and feature no permanent dipole moment and no pure rotation spectrum. As a result they have only previously been observed in the infrared. However, directly observing them with the rest of the molecular column especially when the source is spatially resolved would be very valuable in understanding chemical evolution. Vibrational difference bands provide a means to detect symmetric molecules with microwave precision using terahertz techniques. Herschel, SOFIA and ALMA have the potential to identify a number of vibrational difference bands of light symmetric species. This paper reports laboratory results on 12C2H2 and 12C2D2. Symmetric acetylene isotopologues have two bending modes, the trans bending and the cis bending. Their difference bands are allowed and occur in the microwave, terahertz, and far-infrared wavelengths, with band origins at 3500 GHz for 12C2H2 and 900 GHz for 12C2D2. Twenty 12C2H2 P branch high-J transitions and two hundred and fifty-one 12C2D2 P Q and R branch transitions have been measured in the 0.2 - 1.6 THz region with precision of 50 to 100 kHz. These lines were modeled together with prior data on the pure bending levels. Significantly improved molecular parameters were obtained for 12C2H2 and 12C2D2 with the combined data set, and new frequency and intensity predictions were made to support astrophysics applications. The research was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. S. Y. was supported by an appointment to the NASA Postdoctoral Program, administrated by Oak Ridge Associated Universities through a contract with NASA.

  15. Quantum partner-dance in the 12C + 12C system yields sub-Coulomb fusion resonances

    NASA Astrophysics Data System (ADS)

    Diaz-Torres, Alexis; Wiescher, Michael

    2014-03-01

    A preliminary study of the 12C + 12C sub-Coulomb fusion reaction using the time-dependent wave-packet method is presented. The theoretical sub-Coulomb fusion resonances seem to correspond well with observations. The present method might be a more suitable tool for expanding the cross-section predictions towards lower energies than the commonly used potential-model approximation.

  16. Comparison of clustering effects in 12C fragmentation among p+12C, α+12C, and 14N+12C reactions: Excitation of α-cluster degrees of freedom in nuclear collisions

    NASA Astrophysics Data System (ADS)

    Takemoto, Hiroki; Horiuchi, Hisashi; Ono, Akira

    1998-02-01

    We examine 12C fragmentation in p+12C, α+12C, and 14N+12C reactions using antisymmetrized molecular dynamics. We compare 12C fragmentation among the above three kinds of reactions and find that the alpha-clustering effect in 12C fragmentation depends on the projectile and also on the incident energy. In proton induced reactions 4He fragments are scarcely produced at the early stage of the reaction in a wide range of incident energy. On the other hand, in α and 14N induced reactions many 4He fragments are produced during the dynamical stage at a lower incident energy but fewer 4He fragments are produced with increasing incident energy. We indicate that this abundance of 4He fragments at a lower incident energy in α and 14N induced reactions is due to the excitation of 12C to states with an excitation energy of 7-15 MeV which have the alpha-cluster structure. We see that the upper limit of the incident energy which gives rise to the dynamical production of 4He fragments is lower in the α induced reaction than in the 14N induced reaction. We show that the excitation to the clustering states is caused by the mean field from the projectile and that nucleon-nucleon collisions work to destroy this excitation. We will see that the disappearance of the excitation to the clustering states at high incident energies is partly due to the weakened effect of the mean field of the projectile and partly due to the strengthened effect of nucleon-nucleon collision processes.

  17. The C-12/C-13 Ratio as a Chemistry Indicator

    NASA Technical Reports Server (NTRS)

    Wirstroem, Eva; Geppert, Wolf; Persson, Carina; Charnley, Steven

    2011-01-01

    Isotopic ratios of elements are considered powerful tools, e.g. in tracing the origin of solar system body materials, or the degree of nucleosynthesis processing throughout the Galaxy. In interstellar molecules, some isotopic ratios like H/D and C-12/C-13 can also be used as indicators of their chemical origin. Isotope fractionation in gas-phase chemical reactions and gas-dust interaction makes observations of the ratio between C-12 and C-13 isotopologues suitable to distinguish between different formation scenarios. We will present observations of the C-12/C-13 ratio in methanol and formaldehyde towards a sample of embedded, massive young stellar objects. In relation to this we also present results from theoretical modeling showing the usefulness of the C-12/C-13 ratio as a chemistry indicator.

  18. Ratios of 15N/12C and 4He/12C inclusive electroproduction cross sections in the nucleon resonance region

    SciTech Connect

    Peter Bosted; Robert Fersch

    2007-12-14

    The ratio of inclusive electron scattering cross sections for 15N/12C was determined in the kinematic range 0.8<2 GeV and 0.2<1 GeV2 using 2.285 GeV electrons and the CLAS detector at Jefferson Lab. The ratio exhibits only slight resonance structure, as predicted by a phenomenological model, and also by quark-hadron duality. Within the super-scaling quasi-elastic model, slight evidence is found for a 1 MeV lower effective nucleon binding energy in 15N than in 12C. Ratios of 4He/12C using 1.6 to 2.5 GeV electrons are in good agreement with the phenomenological model.

  19. {sup 12}C formation: A classical quest in new light

    SciTech Connect

    Tengblad, O.; Alcorta, M.; Borge, M. J. G.; Madurga, M.; Perea, A.; Cubero, M.; Fynbo, H. O. U.; Riisager, K.; Kirsebom, O.; Hyldegaard, S.; Jonson, B.; Nyman, G.; Nilsson, T.; Diget, D. G.; Fulton, B.

    2011-10-28

    In this work we have studied the break-up of {sup 12}C following the reactions {sup 10}B({sup 3}He,p{alpha}{alpha}{alpha}) and {sup 11}B({sup 3}He,d{alpha}{alpha}{alpha}). The study was performed at the 5 MV tandem in Madrid. The break-up gives us information on excited states in {sup 12}C from the famous Hoyle state up to an energy of almost 18 MeV. Using a highly segmented experimental set-up the simultaneous detection of the three alpha particles in coincidence with a proton or deuteron respectively made possible a full kinematic reconstruction of the break-up. On the basis of the energies of the 3 {alpha} particles and their angular correlations it has been possible to determine the spin and parity of states for cases in which the assignment has been doubtful. Some of these levels will also de-excite via electromagnetic emission. The comparison between the energy of proton that populate a state of {sup 12}C and the sum of the energies of the 3{alpha} emitted from the same state makes possible to determine the presence of electromagnetic disintegration ({gamma}) to lower states within {sup 12}C followed by the 3{alpha} break-up.

  20. The Rotation-Vibration Structure of 12C

    NASA Astrophysics Data System (ADS)

    Gai, M.; Bijker, R.; Freer, M.; Kokalova, T.; Marin-Lambarri, D. J.; Wheldon, C.

    2014-12-01

    The newly measured high spin Jπ = 5- state at 22.4(2) MeV in 12C reported in this conference, fits very well to the predicted (ground state) rotational band of an oblate equilateral triangular spinning top with a D3h symmetry characterized by the sequence of states: 0+, 2+, 3- 4±, 5- with almost degenerate 4+ and 4- (parity doublet) states. Such a D3h symmetry was observed in triatomic molecules, and it is observed here for the first time in nuclear physics. We discuss a classification of other rotation-vibration bands in 12C such as the (0+) Hoyle band and the (1-) bending mode band and suggest measurements in search of the predicted ("missing") states that may shed new light on clustering in 12C and light nuclei. In particular, the observation (or non observation) of the predicted ("missing") states in the Hoyle band will allow us to conclude the geometrical arrangement of the three alpha particles composing the Hoyle state at 7.654 MeV in 12 C.

  1. Cluster Structure of {sup 12}C and {sup 11}Be

    SciTech Connect

    Freer, M.; Haigh, P. J.; Ashwood, N. I.; Bloxham, T.; Curtis, N.; McEwan, P.; Fujita, H.; Carter, J.; Usman, I.; Buthelezi, Z.; Foertsch, S. V.; Neveling, R.; Perez, S. M.; Smit, F. D.; Fearick, R. W.; Papka, P.; Swartz, J. A.; Bohlen, H. G.; Dorsch, T.; Kokalova, Tz.

    2009-08-26

    The structure of {sup 12}C is discussed, in particular the spectrum of states above the alpha-decay threshold. A search for the 2{sup +} excitation of the Hoyle-state is reported. The structural link between halo-like states and molecular states is explored in the case of {sup 11}Be.

  2. Laboratory Precision Measurements of the Rotational Spectrum of 12C17O and 13C17O

    NASA Astrophysics Data System (ADS)

    Klapper, Gabriele; Surin, Leonid; Lewen, Frank; Müller, Holger S. P.; Pak, Igor; Winnewisser, Gisbert

    2003-01-01

    High-precision millimeter and submillimeter wave measurements were performed on two 17O isotopically substituted carbon monoxide species, i.e., 12C17O and 13C17O. Covering the frequency region from 100 GHz to 1 THz, the accuracy achievable is estimated to be +/-5 kHz in the Doppler-limited mode and +/-1 kHz for sub-Doppler-resolution measurements. From a weighted least-squares fit, the following molecular rotational parameters for 12C17O and 13C17O were obtained: for 12C17O,B0=56,179.99110(28)MHz,D0=174.330(6)kHzand for 13C17O,B0=53,644.7906(29)MHz,D0=158.918(19)kHzin both instances, the H0 values were kept fixed to IR data. The oxygen 17O nucleus exhibits a sizeable electric nuclear quadrupole moment, which has been measured for both isotopomers, i.e., eQq(12C17O)=4.298(44)MHz and eQq(13C17O)=4.355(182)MHz. The high precision of the Lamb dip measurements allowed us to observe additional small hyperfine effects caused by the magnetic moment of the 17O nucleus. These precision measurements allowed the determination of the nuclear spin-rotation constant CI(17O)=-31.60(72)Hz for 12C17O, solely from the Cologne data set. The highly precise transition frequencies reported here should warrant deep interstellar searches for the two molecules 12C17O and 13C17O. The latter has not been detected in space until very recently. On the basis of our laboratory data, we were able to report the discovery of 13C17O (by Bensch and coworkers) along with the observations of two additionalrare CO isotopomers including 12C17O and 12C18O toward core C of the ρ Ophiucus molecular cloud.

  3. Measurement of quasi-elastic 12C(p,2p) scattering at high momentum transfer

    NASA Astrophysics Data System (ADS)

    Mardor, Y.; Aclander, J.; Alster, J.; Barton, D.; Bunce, G.; Carroll, A.; Christensen, N.; Courant, H.; Durrant, S.; Gushue, S.; Heppelmann, S.; Kosonovsky, E.; Mardor, I.; Marshak, M.; Makdisi, Y.; Minor, E. D.; Navon, I.; Nicholson, H.; Piasetzky, E.; Roser, T.; Russell, J.; Sutton, C. S.; Tanaka, M.; White, C.; Wu, J.-Y.

    1998-10-01

    We measured the high-momentum transfer [Q2=4.8 and 6.2 (GeV/c)2] quasi-elastic 12C(p,2p) reaction at θcm~=90 deg for 6 and 7.5 GeV/c incident protons. The momentum components of both outgoing protons and the missing energy and momentum of the proton in the nucleus were measured. We verified the validity of the quasi-elastic picture for ground state momenta up to about 0.5 GeV/c. Transverse and longitudinal momentum distributions of the target proton were measured. They have the same shape with a large momentum tail which is not consistent with independent particle models. We observed that the transverse distribution gets wider as the longitudinal component increases in the beam direction.

  4. Alpha spectroscopic factors from (12)C((6)->Li,d): A thirty year mystery

    NASA Astrophysics Data System (ADS)

    Drummer, Timothy Lee

    1998-10-01

    systems were simultaneously coupled together and transfers from both projectile and target excited states were included. The CCBA calculations showed that the vector analyzing power iT11 required the inclusion of an explicit deuteron spin orbit potential while the tensor analyzing powers resulted from inelastic channel couplings and α-transfer from the 6Li first excited state. Large analyzing powers were predicted for the excited states indicating that coupled channels and inelastic transfer effects are necessary in the description of the excited state data. The 30 year mystery centers around whether th 12C(6Li,d)16O reaction can be used to extract α-widths for bound states in 16O. The large analyzing powers measured in the present work show that statistical compound nucleus contributions to this reaction at the two energies studied here are negligible. (Abstract shortened by UMI.)

  5. Estimation of the Breakup Cross-Sections in 6He + 12C Reaction Within High-Energy Approximation and Microscopic Optical Potential

    NASA Astrophysics Data System (ADS)

    Lukyanov, V. K.; Zemlyanaya, E. V.; Lukyanov, K. V.

    The breakup cross-sections in the reaction 6He + 12C are calculated at about 40 MeV/nucleon using the high-energy approximation (HEA) and with the help of microscopic optical potentials (OP) of interaction with the target nucleus 12C of the projectile nucleus fragments 4He and 2n. Considering the di-neutron h = 2n as a single particle the relative motion hα wave function is estimated so that to explain both the separation energy of h in 6He and the rms radius of the latter. The stripping and absorbtion total cross-sections are calculated and their sum is compared with the total reaction cross-section obtained within a double-folding microscopic OP for the 6He + 12C scattering. It is concluded that the breakup cross-sections contribute to about 50% of the total reaction cross-section.

  6. Revised rates for the stellar triple-α process from measurement of 12C nuclear resonances

    NASA Astrophysics Data System (ADS)

    Fynbo, Hans O. U.; Diget, Christian Aa.; Bergmann, Uffe C.; Borge, Maria J. G.; Cederkäll, Joakim; Dendooven, Peter; Fraile, Luis M.; Franchoo, Serge; Fedosseev, Valentin N.; Fulton, Brian R.; Huang, Wenxue; Huikari, Jussi; Jeppesen, Henrik B.; Jokinen, Ari S.; Jones, Peter; Jonson, Björn; Köster, Ulli; Langanke, Karlheinz; Meister, Mikael; Nilsson, Thomas; Nyman, Göran; Prezado, Yolanda; Riisager, Karsten; Rinta-Antila, Sami; Tengblad, Olof; Turrion, Manuela; Wang, Youbao; Weissman, Leonid; Wilhelmsen, Katarina; Äystö, Juha; ISOLDE Collaboration

    2005-01-01

    In the centres of stars where the temperature is high enough, three α-particles (helium nuclei) are able to combine to form 12C because of a resonant reaction leading to a nuclear excited state. (Stars with masses greater than ~0.5 times that of the Sun will at some point in their lives have a central temperature high enough for this reaction to proceed.) Although the reaction rate is of critical significance for determining elemental abundances in the Universe, and for determining the size of the iron core of a star just before it goes supernova, it has hitherto been insufficiently determined. Here we report a measurement of the inverse process, where a 12C nucleus decays to three α-particles. We find a dominant resonance at an energy of ~11MeV, but do not confirm the presence of a resonance at 9.1MeV (ref. 3). We show that interference between two resonances has important effects on our measured spectrum. Using these data, we calculate the triple-α rate for temperatures from 107K to 1010K and find significant deviations from the standard rates. Our rate below ~5 × 107K is higher than the previous standard, implying that the critical amounts of carbon that catalysed hydrogen burning in the first stars are produced twice as fast as previously believed. At temperatures above 109K, our rate is much less, which modifies predicted nucleosynthesis in supernovae.

  7. Electrophysiological responses of the mouse retina to 12C ions.

    PubMed

    Sannita, Walter G; Peachey, Neal S; Strettoi, Enrica; Ball, Sherry L; Belli, Francesco; Bidoli, Vittorio; Carozzo, Simone; Casolino, Marco; Di Fino, Luca; Picozza, Piergiorgio; Pignatelli, Vincenzo; Rinaldi, Adele; Saturno, Moreno; Schardt, Dieter; Vazquez, Marcelo; Zaconte, Veronica; Narici, Livio

    2007-04-18

    Phosphenes ("light flashes") have been reported by most astronauts on space missions and by healthy subjects whose eyes were exposed to ionizing radiation in early experiments in particle accelerators. The conditions of occurrence suggested retinal effects of heavy ions. To develop an in vivo animal model, we irradiated the eyes of anesthetized wild-type mice with repeated bursts of 12C ions delivered under controlled conditions in accelerator. 12C ions evoked electrophysiological retinal mass responses and activated the visual system as indicated by responses recorded from the visual cortex. No retinal immunohistological damage was detected. Mice proved a suitable animal model to study radiation-induced phosphenes in vivo and our findings are consistent with an origin of phosphenes in radiation activating the retina.

  8. Tests of Predictions of the Algebraic Cluster Model: the Triangular D 3h Symmetry of 12C

    NASA Astrophysics Data System (ADS)

    Gai, Moshe

    2016-07-01

    A new theoretical approach to clustering in the frame of the Algebraic Cluster Model (ACM) has been developed. It predicts rotation-vibration structure with rotational band of an oblate equilateral triangular symmetric spinning top with a D 3h symmetry characterized by the sequence of states: 0+, 2+, 3-, 4±, 5- with a degenerate 4+ and 4- (parity doublet) states. Our measured new 2+ 2 in 12C allows the first study of rotation-vibration structure in 12C. The newly measured 5- state and 4- states fit very well the predicted ground state rotational band structure with the predicted sequence of states: 0+, 2+, 3-, 4±, 5- with almost degenerate 4+ and 4- (parity doublet) states. Such a D 3h symmetry is characteristic of triatomic molecules, but it is observed in the ground state rotational band of 12C for the first time in a nucleus. We discuss predictions of the ACM of other rotation-vibration bands in 12 C such as the (0+) Hoyle band and the (1-) bending mode with prediction of (“missing 3- and 4-”) states that may shed new light on clustering in 12C and light nuclei. In particular, the observation (or non observation) of the predicted (“missing”) states in the Hoyle band will allow us to conclude the geometrical arrangement of the three alpha particles composing the Hoyle state at 7.6542 MeV in 12C. We discuss proposed research programs at the Darmstadt S-DALINAC and at the newly constructed ELI-NP facility near Bucharest to test the predictions of the ACM in isotopes of carbon.

  9. Dielectron production in 12C+12C collisions at 2A GeV with the HADES spectrometer.

    PubMed

    Agakichiev, G; Agodi, C; Alvarez-Pol, H; Bałanda, A; Bertini, D; Bielcik, J; Bellia, G; Böhmer, M; Bokemeyer, H; Boyard, J L; Braun-Munzinger, P; Cabanelas, P; Chernenko, S; Christ, T; Coniglione, R; Cosentino, L; Díaz, J; Dohrmann, F; Durán, I; Eberl, T; Enghardt, W; Fabbietti, L; Fateev, O; Fernandez, C; Finocchiaro, P; Friese, J; Fröhlich, I; Fuentes, B; Garabatos, C; Garzón, J A; Gernhäuser, R; Gilardi, C; Golubeva, M; González-Díaz, D; Grosse, E; Guber, F; Hennino, T; Hlavac, S; Holzmann, R; Homolka, J; Ierusalimov, A; Iori, I; Ivashkin, A; Jaskuła, M; Jurkovic, M; Kagarlis, M; Kajetanowicz, M; Kämpfer, B; Kanaki, K; Karavicheva, T; Kastenmüller, A; Kidoń, L; Kienle, P; Koenig, I; Koenig, W; Körner, H J; Kolb, B W; Kotte, R; Krücken, R; Kugler, A; Kühn, W; Kulessa, R; Kurepin, A; Lang, S; Lange, S; Lehnert, J; Lins, E; Magestro, D; Maiolino, C; Malarz, A; Markert, J; Metag, V; Mousa, J; Münch, M; Müntz, C; Naumann, L; Nekhaev, A; Novotny, J; Otwinowski, J; Pachmayer, Y C; Pechenov, V; Pérez, T; Piattelli, P; Pietraszko, J; Pleskac, R; Płoskoń, M; Pospísil, V; Prokopowicz, W; Przygoda, W; Ramstein, B; Reshetin, A; Ritman, J; Roy-Stephan, M; Rustamov, A; Sadovsky, A; Sailer, B; Salabura, P; Sánchez, M; Sapienza, P; Schmah, A; Schön, H; Schön, W; Schröder, C; Schwab, E; Simon, R S; Smolyankin, V; Smykov, L; Spataro, S; Spruck, B; Ströbele, H; Stroth, J; Sturm, C; Sudoł, M; Suk, M; Taranenko, A; Tlusty, P; Toia, A; Traxler, M; Tsertos, H; Vassiliev, D; Vázquez, A; Wagner, V; Waluś, W; Wiśniowski, M; Wójcik, T; Wüstenfeld, J; Zanevsky, Y; Zeitelhack, K; Zovinec, D; Zumbruch, P

    2007-02-02

    The invariant-mass spectrum of e+e- pairs produced in 12C+12C collisions at an incident energy of 2 GeV per nucleon has been measured for the first time. The measured pair production probabilities span over 5 orders of magnitude from the pi(0)-Dalitz to the rho/omega invariant-mass region. Dalitz decays of pi(0) and eta account for all the yield up to 0.15 GeV/c(2), but for only about 50% above this mass. A comparison with model calculations shows that the excess pair yield is likely due to baryon-resonance and vector-meson decays. Transport calculations based on vacuum spectral functions fail, however, to describe the entire mass region.

  10. Observation of. lambda. -hypernuclei in the reaction /sup 12/C(. pi. /sup +/,K/sup +/)/sub. lambda. //sup 12/C

    SciTech Connect

    Milner, E.C.

    1985-12-01

    The observation of ..lambda..-hypernuclear levels in /sub ..lambda..//sup 12/C by associated production through the (..pi../sup +/,K/sup +/) reaction is reported. Spectrometers used in the measurements are discussed. The /sub ..lambda..//sup 12/C excitation energy spectra were recorded at laboratory scattering angles of 5.6/sup 0/, 10.3/sup 0/, and 15.2/sup 0/. The spectra show two major peaks - one attributed to the ground state, and one about 11 MeV higher in excitation. The peak near 11 MeV excitation energy is believed to be almost entirely composed of a multiplet of three J/sup ..pi../ = 2/sup +/ states. Relativistic DWBA calculations imply support for the expectation that higher spin states are preferentially populated in the (..pi../sup +/,K/sup +/) reaction, compared to the (K/sup -/,..pi../sup -/) reaction in which lower spin states are excited. 29 refs., 40 figs.

  11. Actinides produced by /sup 12/C + /sup 242/Pu and /sup 16/O + /sup 238/U reactions

    SciTech Connect

    Shinohara, N.; Usuda, S.; Ichikawa, S.; Suzuki, T.; Magara, M.; Okashita, H.; Yoshikawa, H.; Horiguchi, T.; Iwata, Y.; Shibata, S.; and others

    1986-09-01

    The cross sections for /sup 250/Fm, /sup 244-246/Cf, /sup 242-244/Cm, and /sup 242/Am/sup g-italic/ produced by the /sup 12/C+ /sup 242/Pu and the /sup 16/O+ /sup 238/U reactions leading to the same compound nucleus of /sup 254/Fm have been measured by using radiochemical methods. The excitation functions show that the difference between the /sup 12/C+ /sup 242/Pu and the /sup 16/O+ /sup 238/U reactions can be attributed mainly to the Coulomb barriers. Our results were compared with others reported previously for /sup 22/Ne+ /sup 232/Th, /sup 12/C+ /sup 238/U, /sup 12/C+ /sup 240,241/Pu, /sup 13/C+ /sup 241/Pu, /sup 16/O+ /sup 233/U, and /sup 16/O+ /sup 242/Pu reaction systems, and support a mechanism involving transfer of ..cap alpha..-particle clusters (C,Be,He) from projectile to target for the production of Cf and Cm isotopes.

  12. In-beam measurements of 13C+12C fusion reaction cross section at energies around and below Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Stefanescu, I.; Chilug, A.; Tudor, D.; Trache, L.; Straticiuc, M.; Burducea, I.; Focsa, I. M.; Ghita, D. G.; Zhang, N.; Tang, X.; Chen, H.

    2017-06-01

    The reaction cross section of the 12C+12C system is difficult to measure because of the presence of the resonances in the Gamow energy window. It has been proved that the 13C+12C reaction is a good alternative to study the behavior of the reaction cross section at energies relevant for astrophysics. We have measured it with activation and online techniques. During online measurements we were interested to determine the relative contributions of the open channels of the 13C+12C reaction. These determinations are necessary to evaluate the total fusion reaction cross section. Therefore, we have measured the γ-ray yields of proton, neutron and alpha particle evaporation channels from the resulting 25Mg compound nucleus using prompt γ-rays measurements. This complements the activation method. The irradiations took place at the 3 MV Tandetron Accelerator at IFIN-HH [1], Bucharest and the prompt gamma-rays were measured using a hyper-pure germanium detector with 100% relative efficiency, shielded with lead bricks. The energy range for the irradiation was from 4.6 up to 11 MeV (in laboratory frame), in steps of 0.2 MeV and the online measurements were performed from 6.4 up to 11 MeV.

  13. Folding model analysis of pion elastic and inelastic scattering from {sup 6}Li and {sup 12}C

    SciTech Connect

    Ebrahim, A. A.

    2013-04-15

    {pi}{sup {+-}}-Nucleus scattering cross sections are calculated applying the Watanabe superposition model with a phenomenological Woods-Saxon potential. The phenomenological potential parameters are searched for {pi}{sup {+-}} scattering from {sup 6}Li and {sup 12}C to reproduce not only differential elastic cross sections but also inelastic and total and reaction cross sections at pion kinetic energies from 50 to 672 MeV. The optical potentials of {sup 6}Li and {sup 12}C are calculated in terms of the alpha particle and deuteron optical potentials. Inelastic scattering has been analyzed using the distorted waves from elastic-scattering data. The values of deformation lengths thus obtained compare very well with the ones reported earlier.

  14. Studies of 12C Using β-DECAYS

    NASA Astrophysics Data System (ADS)

    Hyldegaard, S.; Fynbo, H. O. U.; Riisager, K.; Brandenburg, S.; Dendooven, P.; Jungmann, K.; Onderwater, C. J. G.; Rogachevskiy, A.; Sohani, M.; Traykov, E.; Wilschut, H. W.; Büscher, J.; Huyse, M.; Raabe, R.; Alcorta, M.; Borge, M. J. G.; Madurga, M.; Tengblad, O.; Diget, C. A. A.; Fulton, B. R.; Jokinen, A. S.; Perajärvi, K.; Saastamoinen, A.; Äystö, J.; Jonson, B.; Nyman, G.

    The nuclear structure of states in 12C have been a subject of interest for both theory and experiment since the early days of nuclear physics. Many open questions remain, especially concerning the existence and properties of 0+ and 2+ states in the triple alpha continuum. A series of experiments have been performed using β-decay of 12N and 12B to probe these states. The latest experiment was performed at KVI using an implantation method, measuring the sum energy of the three α-particles directly. Preliminary results from this experiment will be presented.

  15. 2{sup +} excitation of the {sup 12}C Hoyle state

    SciTech Connect

    Freer, M.; Fujita, H.; Carter, J.; Usman, I.; Buthelezi, Z.; Foertsch, S. V.; Neveling, R.; Perez, S. M.; Smit, F. D.; Fearick, R. W.; Papka, P.; Swartz, J. A.

    2009-10-15

    A high-energy-resolution magnetic spectrometer has been used to measure the {sup 12}C excitation energy spectrum to search for the 2{sup +} excitation of the 7.65 MeV, 0{sup +} Hoyle state. By measuring in the diffractive minimum of the angular distribution for the broad 0{sup +} background, evidence is found for a possible 2{sup +} state at 9.6(1) MeV with a width of 600(100) keV. The implications for the {sup 8}Be+{sup 4}He reaction rate in stellar environments are discussed.

  16. AGB fluorine nucleosynthesis studied by means of Trojan-horse method: the case of {sup 15}N(p,{alpha}){sup 12}C

    SciTech Connect

    Pizzone, R. G.; Spitaleri, C.; La Cognata, M.; Cherubini, S.; Crucilla, V.; Gulino, M.; Lamia, L.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, S.; Tumino, A.; Tribble, R.; Trache, L.; Fu, C.; Goldberg, V.; Mukhamedzhanov, A.; Tabacaru, G.

    2008-05-12

    The low-energy bare-nucleus cross section for {sup 15}N(p,{alpha}){sup 12}C is extracted by means of the Trojan-horse Method applied to the {sup 2}H({sup 15}N,{alpha}){sup 12}C)n reaction at E{sub beam} = 60 MeV. The astrophysical S-factor is deduced and compared to the direct data in the same energy region. A fair agreement with direct data down to 80 keV is found if energy resolution effects are taken into account.

  17. Emission of charged particles from excited compound nucleus

    SciTech Connect

    Kalandarov, Sh. A.; Adamian, G. G.; Antonenko, N. V.

    2010-11-24

    The formation and decay of excited compound nucleus are studied within the dinuclear system model[1]. The cross sections of complex fragment emission are calculated and compared with experimental data for the reactions {sup 3}He+{sup 108}Ag, {sup 78,82}Kr+{sup 12}C. Angular momentum dependence of cluster emission in {sup 78}Kr+{sup 12}C and {sup 40}Ca+{sup 78}Kr reactions is demonstrated.

  18. Structure of the Hoyle State in {sup 12}C

    SciTech Connect

    Chernykh, M.; Neumann-Cosel, P. von; Richter, A.; Feldmeier, H.; Neff, T.

    2007-01-19

    The first excited 0{sup +} state in {sup 12}C (Hoyle state) has been predicted to be a dilute self-bound gas of bosonic {alpha} particles, similar to a Bose-Einstein condensate. To clarify this conjecture, precise electron scattering data on form factors of the ground state and the transition to the Hoyle state are compared with results of the fermionic molecular dynamics model, a microscopic {alpha}-cluster model, and an {alpha}-cluster model with reduced degrees of freedom (in the spirit of a Bose-Einstein condensed state). The data indicate clearly a dilute density with a large spatial extension of the Hoyle state. A closer inspection of the model calculations, which reproduce the experimental findings, reveals that the term Bose-Einstein condensation of three {alpha} particles must not be taken too literally.

  19. Study of /sup 12/C interactions at HISS

    SciTech Connect

    Crawford, H.J.

    1982-12-01

    Single-particle inclusive measurements in high-energy nuclear physics have provided the foundation for a number of models of interacting nuclear fluids. Such measurements yield information on the endpoints of the evolution of highly excited nuclear systems. However, they suffer from the fact that observed particles can be formed in a large number of very different evolutionary paths. To learn more about how interactions proceed we have performed a series of experiments in which all fast nuclear fragments are analyzed for each individual interaction. These experiments were performed at the LBL Bevalac HISS (Heavy Ion Spectrometer System) facility where we studied the interaction of 1 GeV/nuc 12C nuclei with targets of C, CH/sub 2/, Cu, and U. In this paper we describe HISS and present some preliminary results of the experiment.

  20. Nuclear mean field and double-folding model of the nucleus-nucleus optical potential

    NASA Astrophysics Data System (ADS)

    Khoa, Dao T.; Phuc, Nguyen Hoang; Loan, Doan Thi; Loc, Bui Minh

    2016-09-01

    Realistic density dependent CDM3Yn versions of the M3Y interaction have been used in an extended Hartree-Fock (HF) calculation of nuclear matter (NM), with the nucleon single-particle potential determined from the total NM energy based on the Hugenholtz-van Hove theorem that gives rise naturally to a rearrangement term (RT). Using the RT of the single-nucleon potential obtained exactly at different NM densities, the density and energy dependence of the CDM3Yn interactions was modified to account properly for both the RT and observed energy dependence of the nucleon optical potential. Based on a local density approximation, the double-folding model of the nucleus-nucleus optical potential has been extended to take into account consistently the rearrangement effect and energy dependence of the nuclear mean-field potential, using the modified CDM3Yn interactions. The extended double-folding model was applied to study the elastic 12C+12C and 16O+12C scattering at the refractive energies, where the Airy structure of the nuclear rainbow has been well established. The RT was found to affect significantly the real nucleus-nucleus optical potential at small internuclear distances, giving a potential strength close to that implied by the realistic optical model description of the Airy oscillation.

  1. Use of Monte Carlo techniques to derive yields for n + sup 12 C multibody breakup reactions: Programming the computer to simulate collisions by fast neutrons

    SciTech Connect

    Dickens, J.K. )

    1989-11-01

    A computer experiment'' using Monte Carlo sampling methods has been designed to simulate the breaking up of {sup 12}C by medium-energy neutrons into final reaction channels having 2, 3, or 4 outgoing charged particles. The calculational nuclear physics concept used in the experiment'' is one of a sequentially decaying, highly excited compound nucleus. Two methods of Monte Carlo sampling, the rejection method and the cumulative-distribution method, are discussed as applied to probability functions developed in the program.

  2. The ^12C(^6Li,d)^16O reaction at 34 MeV

    NASA Astrophysics Data System (ADS)

    Mendez, A. J.; Brune, C. R.; Karwowski, H. J.; Ludwig, E. J.; Veal, K. D.; Bartosz, E. E.; Cathers, P. D.; Drummer, T. L.; Kemper, K. W.; Koslowska, B.

    1996-05-01

    Present models of the ^6Li nucleus are in disagreement(D. R. Lehman, Colloque de Physique suppl. n22, 52), C6-47 (1990).^,(A. M. Eiro et al.), Few Body Systems suppl. 99 (1995). as to the sign of the D- to S-state ratio, η. Transfer reactions induced by polarized ^6Li have been predicted^3 to be sensitive to η, and recent measurements(A. J. Mendez et al.), Phys. Rev. C 51, 651 (1995). have shown a sensitivity to the presence of the D-state in ^6Li. We will present cross-section, A_y, and A_zz angular-distribution measurements for the ^12C(^6Li,d)^16O reaction at 34 MeV over the laboratory angular range 6.5^circ - 60^circ. We find Ay to be large, negative and highly oscillatory for the 0^+ ground state and predominantly negative, but smaller and less oscillatory, for both the 3^- state at 6.13 MeV and the 2^+, 1^- doublet at 7 MeV. The A_zz distributions for the first two states are large and oscillatory about zero, while that of the doublet is predominantly negative. We will present a DWBA analysis of the data and discuss the consequences for η(^6Li).

  3. 29 CFR 779.504 - The retailer and section 12(c).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Child Labor Provisions § 779.504 The retailer and section 12(c). Section 12(c) was amended in 1961 to prohibit the employment of oppressive child labor in any enterprise engaged in commerce or in the... comply with section 12(c) of the child labor provisions of the Act. As stated in § 779.503, compliance...

  4. 29 CFR 779.504 - The retailer and section 12(c).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Child Labor Provisions § 779.504 The retailer and section 12(c). Section 12(c) was amended in 1961 to prohibit the employment of oppressive child labor in any enterprise engaged in commerce or in the... comply with section 12(c) of the child labor provisions of the Act. As stated in § 779.503,...

  5. 29 CFR 779.504 - The retailer and section 12(c).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Child Labor Provisions § 779.504 The retailer and section 12(c). Section 12(c) was amended in 1961 to prohibit the employment of oppressive child labor in any enterprise engaged in commerce or in the... comply with section 12(c) of the child labor provisions of the Act. As stated in § 779.503,...

  6. 29 CFR 779.504 - The retailer and section 12(c).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Child Labor Provisions § 779.504 The retailer and section 12(c). Section 12(c) was amended in 1961 to prohibit the employment of oppressive child labor in any enterprise engaged in commerce or in the... comply with section 12(c) of the child labor provisions of the Act. As stated in § 779.503,...

  7. 29 CFR 779.504 - The retailer and section 12(c).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Child Labor Provisions § 779.504 The retailer and section 12(c). Section 12(c) was amended in 1961 to prohibit the employment of oppressive child labor in any enterprise engaged in commerce or in the... comply with section 12(c) of the child labor provisions of the Act. As stated in § 779.503,...

  8. Cluster folding model analysis of 3He elastic and inelastic scattering from 12C

    NASA Astrophysics Data System (ADS)

    Khallaf, S. A. E.; Nossair, A. M. A.; Ebrahim, A. A.; Ebraheem, Awad A.

    2003-02-01

    Angular distributions of differential cross sections for the 12C( 3He, 3He) 12C, 12C( 3He, 3He) 12C ∗ reactions at E=72 MeV have been analyzed with a double folding cluster model DFC based on five sets of the effective N-N interaction of Gaussian form with different parameters. The transition to the (2 +; 4.44 MeV) state in 12C is studied and the deformation length δ2 is extracted. It is found that the extracted deformation length is sensitive to the nuclear model used and it is similar to the corresponding value found in the literature.

  9. High energy nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Wosiek, B.

    1986-01-01

    Experimental results on high energy nucleus-nucleus interactions are presented. The data are discussed within the framework of standard super-position models and from the point-of-view of the possible formation of new states of matter in heavy ion collisions.

  10. Measurement of Excitation Spectra in the ^{12}C(p,d) Reaction near the η^{'} Emission Threshold.

    PubMed

    Tanaka, Y K; Itahashi, K; Fujioka, H; Ayyad, Y; Benlliure, J; Brinkmann, K-T; Friedrich, S; Geissel, H; Gellanki, J; Guo, C; Gutz, E; Haettner, E; Harakeh, M N; Hayano, R S; Higashi, Y; Hirenzaki, S; Hornung, C; Igarashi, Y; Ikeno, N; Iwasaki, M; Jido, D; Kalantar-Nayestanaki, N; Kanungo, R; Knöbel, R; Kurz, N; Metag, V; Mukha, I; Nagae, T; Nagahiro, H; Nanova, M; Nishi, T; Ong, H J; Pietri, S; Prochazka, A; Rappold, C; Reiter, M P; Rodríguez-Sánchez, J L; Scheidenberger, C; Simon, H; Sitar, B; Strmen, P; Sun, B; Suzuki, K; Szarka, I; Takechi, M; Tanihata, I; Terashima, S; Watanabe, Y N; Weick, H; Widmann, E; Winfield, J S; Xu, X; Yamakami, H; Zhao, J

    2016-11-11

    Excitation spectra of ^{11}C are measured in the ^{12}C(p,d) reaction near the η^{'} emission threshold. A proton beam extracted from the synchrotron SIS-18 at GSI with an incident energy of 2.5 GeV impinges on a carbon target. The momenta of deuterons emitted at 0° are precisely measured with the fragment separator (FRS) operated as a spectrometer. In contrast to theoretical predictions on the possible existence of deeply bound η^{'}-mesic states in carbon nuclei, no distinct structures are observed associated with the formation of bound states. The spectra are analyzed to set stringent constraints on the formation cross section and on the hitherto barely known η^{'}-nucleus interaction.

  11. γ-ray studies of the fission of 238U induced by 12C, spectroscopy and fission dynamics

    NASA Astrophysics Data System (ADS)

    Houry, M.; Korten, W.; Le Coz, Y.; Lucas, R.; Theisen, Ch.; Barreau, G.; Doan, T. P.; Aiche, M.; Aleonard, M. M.; Chemin, J. F.; Scheurer, J. N.; Belier, G.; Meot, V.; Ethvignot, Th.; Durell, J.; Grimwood, D.; Phillips, W. R.; Roach, A.; Smith, A. G.; Varley, B. J.; Deloncle, I.; Porquet, M. G.; Astier, A.; Perries, S.; Redon, N.

    1998-10-01

    Fission studies have been known for a long time to provide neutron-rich nuclei in various states of excitation energy, spin and deformation. Although many studies have been performed concerning fission fragments from spontaneous fission and neutron induced fission, a renewed interest in fission-fragment spectroscopy has occurred with the elaboration of large Ge detector arrays such as EUROBALL. We have recently performed an experiment with EUROBALL III using SAPhIR; a fission-fragment detector made from photovoltaic cells. The compact and versatile geometry of SAPhIR allows it to be installed inside the γ-ray detector, and to obtain additional information from the fission process as well as a timing reference. Neutron-rich nuclei have been populated in the fusion-fission reaction 238U+12C leading to the compound nucleus 250Cf. First results of this experiment are presented.

  12. Reconstruction of ^16O(,)^12C Events in the HIγS Optical Readout Time Projection Chamber

    NASA Astrophysics Data System (ADS)

    Stave, S.; Ahmed, M. W.; Clinton, E. R.; Howell, C. R.; Seo, P.-N.; Weller, H. R.; Gai, M.; Young, A. H.; Bromberger, B.; Dangendorf, V.; Tittelmeier, K.

    2008-10-01

    A new optical readout time projection chamber (O-TPC) is in use at the High Intensity γ-ray Source (HIγS) located at the Free Electron Laser Laboratory on the Duke University campus. One application of the HIγS O-TPC is the study of the inverse of the ^12C(,)^16O reaction which is important for stellar evolution theory. In the O-TPC, incoming γ-rays interact with an ^16O nucleus producing an α and a ^12C which then leave trails of ionization electrons along their path. The O-TPC then provides several signals each of which must be interpreted simultaneously to determine the different particle types, their energies and their directions. Part of the challenge of operating the O-TPC is integrating the fast signals from the photomultiplier tubes and drift chamber with the slow signals from the CCD camera which images the tracks. Automated routines have been developed to take all of the available track information and provide a reliable determination of the interaction cross section. Examples of the method and preliminary results will be presented.

  13. Measurement of the di-electron mass spectrum in 12C+12C collisions at 2 AGeV by HADES

    SciTech Connect

    Sudol, Malgorzata

    2006-07-11

    The High Acceptance DiElectron Spectrometer (HADES) has been constructed at the SIS accelerator (GSI, Darmstadt) to investigate electron-positron pairs produced in proton, pion and heavy-ion induced reactions. The physics programme of HADES is focused on in-medium properties of light vector mesons. In this contribution the HADES experiment is outlined and first results obtained for 12C + 12C collisions at 2 AGeV are presented.

  14. Sensitivity of the halo nuclei-12C elastic scattering at incident nucleon energy 800 MeV to the halo density distribution

    NASA Astrophysics Data System (ADS)

    Hassan, M. A. M.; Nour El-Din, M. S. M.; Ellithi, A.; Hosny, H.; Salama, T. N. E.

    2017-10-01

    In the framework of Glauber optical limit approximation where Coulomb effect is taken into account, the elastic scattering differential cross section for halo nuclei with {}^{12}{C} at 800 MeV/N has been calculated. Its sensitivity to the halo densities and the root mean square of the core and halo is the main goal of the current study. The projectile nuclei are taken to be one-neutron and two-neutron halo. The calculations are carried out for Gaussian-Gaussian, Gaussian-Oscillator and Gaussian-2 s phenomenological densities for each considered projectile in the mass number range 6-29. Also included a comparison between the obtained results of phenomenological densities and the results within the microscopic densities LSSM of {}6{He} and {}^{11}{Li} and microscopic densities GCM of {}^{11}{Be} where the density of the target nucleus {}^{12}{C} obtained from electron-{}^{12}{C} scattering is used. The zero range approximation is considered in the calculations. We found that the sensitivity of elastic scattering differential cross section to the halo density is clear if the nucleus appears as two clear different clusters, core and halo.

  15. Molecular structure in /sup 12/C + /sup 12/C, orbiting in /sup 12/C + /sup 28/Si, and first studies of the /sup 60/Ni + /sup 60/Ni interaction

    SciTech Connect

    Erb, K.A.; Ford, J.L.C. Jr.; Novotny, R.; Shapira, D.

    1981-01-01

    Some physical implications of a recently proposed classification scheme for the /sup 12/C + /sup 12/C Coulomb barrier resonances for which the requisite very large body of experimental data is already available are discussed. New data are presented suggesting that the back angle resonance-like structure previously observed in quasi-elastic /sup 28/Si + /sup 12/C reactions reflects the existence of a fully developed, rotating di-nuclear system that governs back-angle yields in many additional exit channels. Also some very recent data are briefly discussed for /sup 60/Ni + /sup 60/Ni scattering in a first look at a previously unstudied region of the periodic table. (WHK)

  16. Alpha particle condensation in {sup 12}C and nuclear rainbow scattering

    SciTech Connect

    Ohkubo, S.; Hirabayashi, Y.

    2008-05-12

    It is shown that the large radius of the Hoyle state of {sup 12}C with a dilute density distribution in an {alpha} particle condensate can be clearly seen in the shift of the rainbow angle (therefore the Airy minimum) to a larger angle in {alpha}+{sup 12}C rainbow scattering at the high energy region and prerainbow oscillations in {sup 3}He+{sup 12}C scattering at the lower energy region.

  17. (. pi. sup +- ,. pi. sup +- prime N) reactions on sup 12 C and sup 208 Pb near the giant resonance region

    SciTech Connect

    Yoo, Sung Hoon.

    1990-05-01

    Angular distributions for the {sup 12}C({pi}{sup {plus minus}}, {pi}{sup {plus minus}}{prime} p) and {sup 208}Pb({pi}{sup {plus minus}}, {pi}{sup {plus minus}}{prime} p or n) reactions near the giant resonance region have been measured at T{sub {pi}} = 180 MeV, and found different between {pi}{sup +} and {pi}{sup {minus}} data. This observation is interpreted as evidence for different excitation mechanisms dominating the {pi}{sup {minus}}-nucleus and {pi}{sup +}-nucleus interactions in the giant resonance region of these targets. A comparison with the single-nucleon knock-out distorted-wave impulse approximation calculations shows, even though these calculations underestimate ({pi}{sup {plus minus}}, {pi}{sup {plus minus}}{prime} N) data for both targets, the dominance of direct process for ({pi}{sup +}, {pi}{sup {plus}}{prime} p) or ({pi}{sup {minus}}, {pi}{sup {minus}}{prime} n) in contrast to ({pi}{sup {minus}}, {pi}{sup {minus}}{prime} p) or ({pi}{sup +}, {pi}{sup +}{prime} n). In the ({pi}{sup +}, {pi}{sup +}{prime} p) reaction proton-proton hole states are excited directly and appear to have a large probability for direct decay with escape width, whereas in ({pi}{sup {minus}}, {pi}{sup {minus}}{prime} p) the preferentially excited neutron-neutron hole doorway states couple to resonance states and decay with spreading width. This interpretation led us to suggest that the ratio of cross-sections for inelastic scattering to the giant resonance region should be written in terms of an incoherent sum of cross-sections to neutron and proton doorway states. In a heavy nucleus such as {sup 208}Pb, neutron and proton doorway states. In a heavy nucleus such as {sup 208}Pb, neutron and proton doorway states contribute incoherently because the different decay processes do not populate the same final states of the residual nucleus.

  18. Detector system for the angular distribution measurement of 12C + 12C elastic scattering at 200-400A MeV

    NASA Astrophysics Data System (ADS)

    Qu, W. W.; Zhang, G. L.; Terashima, S.; Guo, C. L.; Tanihata, I.; Le, X. Y.; Wang, T. F.; Zhang, X. H.; Sun, Z. Y.; Duan, L. M.; Hu, R. J.; Lu, C. G.; Ma, P.

    2016-10-01

    To obtain the angular distributions of 12C + 12C elastic scatterings with the incident energies of 200-400A MeV for the study of three-body forces, a detector system was constructed at second Radioactive Ion Beam Line in Lanzhou (RIBLL2) of Institute of Modern Physics (IMP). This system was composed of five plastic scintillation detectors with two read-outs for each detector, a Multi Wire Proportional Chamber (MWPC) and a 4×4 CsI(Tl) array. The 12C beam with the incident energy of 200A MeV on a natural carbon target was used to test this detector system. It is found that the plastic scintillation detector can give the good energy loss (Δ E) and time of flight (TOF) signals, it can also reflect the position information of scattered 12C events. MWPC can precisely provide the trajectories of scattered particles. This system has a very good particle identification ability and can clearly distinguish the scattered 12C particles from the fragments. It can be used for the study of the three-body forces effect for high energy heavy-ion scattering.

  19. Dilute Nuclear States: {sup 12}C, {sup 10}Be and {sup 14}C

    SciTech Connect

    Freer, M.

    2008-11-11

    The experimental evidence for dilute {alpha}-particle states in {sup 12}C, {sup 10}Be and {sup 14}C is discussed. The question of the location of the 2{sup +} excitation of the 7.65 MeV {sup 12}C state remains unresolved, as does the existence of possible analogue states in {sup 14}C.

  20. Study of two- and multi-particle correlations in 12C+24Mg and 12C+208Pb reactions at E=35 AMeV

    NASA Astrophysics Data System (ADS)

    Quattrocchi, L.; Acosta, L.; Amorini, F.; Anzalone, A.; Auditore, L.; Berceanu, I.; Cardella, G.; Chbihi, A.; De Filippo, E.; Dell'Aquila, D.; Francalanza, L.; Gnoffo, B.; Grzeszczuk, A.; Lanzalone, G.; Lombardo, I.; Martel, I.; Minniti, T.; Norella, S.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Porto, F.; Rizzo, F.; Rosato, E.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Veselsky, M.; Vigilante, M.

    2016-05-01

    Two and multi particle correlations from the decay of sources produced in 12C+24Mg and 12C+208Pb collisions at E=35 AMeV have been studied by using the forward part (1° < θlab < 30°) of the CHIMERA multi-detector. Correlations and invariant mass spectroscopy are used to explore simultaneous and sequential decays of resonances in light isotopes with Z˜3-6, produced in peripheral collisions via the break-up of excited quasi-projectiles. Among them we mention 5Li, 6Li, 6Be, 8Be and the astrophysically important state in 12C decaying into three alpha particles. Results and future perspectives at the INFN-LNS will be presented.

  1. EFFECTS OF NUCLEAR INDUCED BREAKUP ON THE FUSION OF 6Li+12C AND 6He+12C SYSTEMS AROUND BARRIER ENERGIES

    NASA Astrophysics Data System (ADS)

    Duhan, Sukhvinder S.; Singh, Manjeet; Kharab, Rajesh

    2012-06-01

    We have studied the effects of nuclear induced breakup channel coupling on the fusion cross-section for 6Li+12C and 6He+12C systems in the near barrier energy regime using the dynamic polarization potential (DPP) approach. It has been found that there is enhancement in the fusion cross-section with respect to standard one-dimensional barrier penetration model in the below barrier energy regime while at energies above the barrier there is suppression of fusion cross-section with respect to simple barrier penetration model is observed. The agreement between data and predictions for 6Li+12C system improves significantly as a result of the inclusion of nuclear induced DPP.

  2. Gamma-ray spectroscopy of the nucleus 139Ce

    NASA Astrophysics Data System (ADS)

    Bucurescu, D.; Căta-Danil, G.; Căta-Danil, I.; Ivaşcu, M.; Mărginean, N.; Mărginean, R.; Mihăilescu, L. C.; Rusu, C.; Suliman, G.

    2006-03-01

    Gamma-ray coincidence techniques are used to determine new level structures in the N = 81 nucleus 139Ce, at low spins and excitation energies with the 139La(p, nγ) reaction at 5.0 and 6.0MeV incident energy, and at high spins with the 130Te(12C, 3nγ) reaction at 50.5MeV, respectively. Lifetime determinations are also made in the (p, nγ) reaction with the centroid DSA method. The observed level structures are discussed by comparison with existing calculations and with those in the neighbouring nucleus 140Ce.

  3. Repulsive three-body force and channel-coupling effects via 12C+12C scattering at 100 A MeV

    NASA Astrophysics Data System (ADS)

    Qu, W. W.; Zhang, G. L.; Terashima, S.; Furumoto, T.; Ayyad, Y.; Chen, Z. Q.; Guo, C. L.; Inoue, A.; Le, X. Y.; Ong, H. J.; Pang, D. Y.; Sakaguchi, H.; Sakuragi, Y.; Sun, B. H.; Tamii, A.; Tanihata, I.; Wang, T. F.; Wada, R.; Yamamoto, Y.

    2017-04-01

    The angular distributions of differential cross sections of 12C+12C elastic and inelastic scattering populating the ground and excited states in 12C up to 15 MeV excitation energy are precisely measured for the first time at an incident energy of 100 A MeV to study the effect of repulsive three-body forces. Using the high-resolution spectrometer Grand Raiden at the Research Center for Nuclear Physics (RCNP), Osaka University, we have obtained the differential cross sections for the ground state (01+) and 4.44 MeV (21+) excited state, as well as the summed differential cross sections for the states between 4.44 and 15 MeV in the angular range of 1 .0∘-7 .5∘ . The results are compared with microscopic coupled-channel calculations. The potential between the colliding nuclei is determined by the double folding method with three different complex G -matrix interactions, the ESC, CEG07b, and MPa interactions. The CEG07b and MPa interactions, which include repulsive three-body forces, describe the data well, whereas the ESC interaction, which does not include repulsive three-body forces, fails to reproduce the data. The results provide evidence of repulsive three-body forces in 12C and demonstrate the possible sensitivity of elastic scattering to three-body forces.

  4. Dynamical decay of 32S* and 31P* formed in 20Ne+12C and 19F+12C reactions, respectively, at E*CN = 60 MeV

    NASA Astrophysics Data System (ADS)

    Singh, BirBikram; Kaur, Mandeep; Sharma, Manoj K.; Gupta, Raj K.

    2015-01-01

    The target-like C-yield in the decay of compound systems 32S* and 31P* formed in 20Ne+12C and 19F+12C reactions at E*CN=60 MeV, is studied for the contribution of fusion-fission (ff) decay cross section σff and the deep inelastic (DI) orbiting σorb from the compound nucleus (CN) and non-compound nucleus nCN processes, respectively. The calculations are performed using the collective clusterization of fragments within the dynamical cluster-decay model (DCM) of Gupta and collaborators. Besides studying the competition between ff and DI orbiting phenomenon in the C-yield of these systems, we exclusively investigate the preformation and barrier penetration probabilities P0 and P as a function of angular momentum ℓ values which subsequently affects the contributions of σff and σorb. For calculating the contribution of σff in the C-yield, we have added the contributions from all the minimized intermediate mass fragments (IMFs) for Z=6 in the calculated fragmentation potentials for 32S* (IMFs 11,12,13C are minimized) and for 31P* (IMFs 12,13C are minimized), while calculating subsequently, P0 and the P for these IMFs. The distribution of preformed clusters/fragments as a function of fragment mass visibly explore the nuclear structure effects for the C-yield in decay of these compound systems, wherein, it is shown to be more favoured in the decay of 31P* in comparison to 32S* decay. The contribution of σorb to the C-yield is calculated from P at different allowed ℓ-values (upto ℓmax and also P≤1) of the outgoing fragments (same as that in the entrance channel, i.e., P0=1). Though preliminary but useful results indicates the competition between the CN and nCN process in the C-yield for the compound system 32S* only while the decay of 31P* is of pure CN origin, as observed in the experimental study. The calculations are in good comparison with the available experimental data.

  5. Fusion enhancement at near and sub-barrier energies in 19O + 12C

    NASA Astrophysics Data System (ADS)

    Singh, Varinderjit; Vadas, J.; Steinbach, T. K.; Wiggins, B. B.; Hudan, S.; deSouza, R. T.; Lin, Zidu; Horowitz, C. J.; Baby, L. T.; Kuvin, S. A.; Tripathi, Vandana; Wiedenhöver, I.; Umar, A. S.

    2017-02-01

    Measuring the fusion excitation function for an isotopic chain of projectile nuclei provides a stringent test of a microscopic description of fusion. We report the first measurement of the fusion excitation function at near-barrier energies for the 19O + 12C system. The measured excitation function is compared with the fusion excitation function of 18O + 12C. A significant enhancement in the fusion probability of 19O ions with a 12C target as compared to 18O ions is observed. The experimental cross-sections observed at near-barrier energies are compared with a state-of-the-art microscopic model.

  6. Measurement and extrapolation of total cross sections of 12C+16O fusion at stellar energies

    NASA Astrophysics Data System (ADS)

    Fang, Xiao

    Carbon burning and oxygen burning in massive stars (M ≥ 8M[special character omitted]) are important burning phases in late stellar evolution following helium burning. They determined the nucleosynthesis phases and the initial matter distribution. Hydrostatic burning of 12C and 16O at lower temperatures remains an important feature. The critical reactions are the 12C+12C, 12C+ 16O and 16O+16O fusion processes. Extensive effort, both experimentally and theoretically, has been invested in the determination of the reaction rates for all reaction channels. Despite this effort, there remain large uncertainties in the predicted results that rely primarily on the extrapolation of the data into the Gamow range. The predicted results depend sensitively on the adopted model parameters, hindrance effects, and the possibility of resonances at relevant energies. The astrophysical important energy range of the 12C+12C fusion reaction spans from 1.0 MeV to 3.0 MeV. However, its cross section has not been determined with enough precision, despite numerous studies, due to the extremely low reaction cross sections and the large experimental background. The 12C+16O is difficult for experimental measurement due to the same reason. To allow measurements of the 12C+ 12C and 12C+16O fusions at astrophysical energies, a large-area silicon strip detector array was developed. The total cross section of the 12C+16O fusion has been measured at low energies using the St Ana 5MV accelerator at the University of Notre Dame. A high-intensity oxygen beam was produced impinging on a thick ultra-pure graphite target. Protons and gamma-rays have been measured simultaneously in the center-of-mass energy range of 3.64 to 4.93 MeV, using silicon and HPGe detectors. Statistical model calculations were employed to interpret the experimental results. This provides a more reliable extrapolation for the 12C+16O fusion cross section reducing substantially the uncertainty for stellar model simulations.

  7. Inclusive quasielastic spin observables for p+2H, 12C at 500 Me V

    NASA Astrophysics Data System (ADS)

    Barlett, M. L.; Fergerson, R. W.; Hoffman, G. W.; Marshall, J. A.; Ray, L.; Amann, J. F.; Bonner, B. E.; McClelland, J. B.

    1991-07-01

    Analyzing powers (Ay) and spin-rotation-depolarization parameters (DSS, DSL, DLS, DLL, DNN) were determined for 500 MeV p+2H and p + 12C inclusive quasielastic scattering at 10°, 15°, and 20° laboratory scattering angles. The p+2H data are consistent with the isospin-average of the proton-proton and proton-neutron scattering observables; the p+12C data are not. A relativistic plane wave impulse approximation calculation leads to better agreement with the p+12C spin-observables.

  8. Fusion enhancement at near and sub-barrier energies in 19O + 12C

    DOE PAGES

    Singh, Varinderjit; Vadas, J.; Steinbach, T. K.; ...

    2016-12-12

    Measuring the fusion excitation function for an isotopic chain of projectile nuclei provides a stringent test of a microscopic description of fusion. We report the first measurement of the fusion excitation function at near-barrier energies for the 19O+12C system. The measured excitation function is compared with the fusion excitation function of 18O+12C. A significant enhancement in the fusion probability of 19O ions with a 12C target as compared to 18O ions is observed. As a result, the experimental cross-sections observed at near-barrier energies are compared with a state-of-the-art microscopic model.

  9. 99.996 %{sup 12}C films isotopically enriched and deposited in situ

    SciTech Connect

    Dwyer, K. J.; Pomeroy, J. M.; Simons, D. S.

    2013-06-24

    Ionizing natural abundance carbon dioxide gas, we extract and mass select the ions, depositing thin films isotopically enriched to 99.9961(4) %{sup 12}C as measured by secondary ion mass spectrometry (SIMS). In solid state quantum information, coherence times of nitrogen-vacancy (NV) centers in {sup 12}C enriched diamond exceeding milliseconds demonstrate the viability of NV centers as qubits, motivating improved isotopic enrichment. NV centers in diamond are particularly attractive qubit candidates due to the optical accessibility of the spin states. We present SIMS analysis and cross-sectional scanning electron microscopy of {sup 12}C enriched thin film samples grown with this method.

  10. Exposure to (12)C particles alters the normal dynamics of brain monoamine metabolism and behaviour in rats.

    PubMed

    Belov, Oleg V; Belokopytova, Ksenia V; Bazyan, Ara S; Kudrin, Vladimir S; Narkevich, Viktor B; Ivanov, Aleksandr A; Severiukhin, Yury S; Timoshenko, Gennady N; Krasavin, Eugene A

    2016-09-01

    Planning of the deep-space exploration missions raises a number of questions on the radiation protection of astronauts. One of the medical concerns is associated with exposure of a crew to highly energetic particles of galactic cosmic rays. Among many other health disorders, irradiation with these particles has a substantial impact on the central nervous system (CNS). Although radiation damage to CNS has been addressed extensively during the last years, the mechanisms underlying observed impairments remain mostly unknown. The present study reveals neurochemical and behavioural alterations induced in rats by 1Gy of 500MeV/u (12)C particles with a relatively moderate linear energy transfer (10.6keV/μm). It is found that exposure to carbon ions leads to significant modification of the normal monoamine metabolism dynamics as well as the locomotor, exploratory, and anxiety-like behaviours during a two-month period. The obtained results indicate an abnormal redistribution of monoamines and their metabolites in different brain regions after exposure. The most pronounced impairments are detected in the prefrontal cortex, nucleus accumbens, and hypothalamus that illustrate the sensitivity of these brain regions to densely ionizing radiations. It is also shown that exposure to (12)C particles enhances the anxiety in animals and accelerates the age-related reduction in their exploratory capability. The observed monoamine metabolism pattern may indicate the presence of certain compensatory mechanisms being induced in response to irradiation and capable of partial restoration of monoaminergic systems' functions. Overall, these findings support a possibility of CNS damage by space-born particles of a relatively moderate linear energy transfer.

  11. Exotic atoms, K-nucleus scattering and hypernuclei

    SciTech Connect

    Barnes, P. D.

    1981-01-01

    Recent progress in exotic atom physics, kaon-nucleus scattering, and hypernuclear physics is reviewed. Specific problems discussed include searches for muon-nucleon interactions beyond QED, a comparison of data and recent calculation of K/sup + -/ + /sup 12/C elastic and inelastic scattering, as well as recent studies of ..sigma.. and ..lambda.. hypernuclei including new data on the level structure of /sup 13/C/..lambda...

  12. Neutron propagation in [sup 12]C for energies 20 to 45 MeV

    SciTech Connect

    Harty, P.D.; MacGregor, I.J.D.; McGeorge, J.C.; Dancer, S.N.; Owens, R.O. )

    1993-05-01

    Neutron transmission in [sup 12]C has been estimated by analyzing [sup 12]C([gamma],[ital pn]) and [sup 12]C([gamma],[ital p]) data, that were collected simultaneously using the Mainz Microtron (MAMI-A) tagged-photon system, at photon energies from 80 to 157 MeV. Correction has been made for solid angle and threshold effects by use of a Monte Carlo simulation. The corrected ratio of the ([gamma],[ital pn]) and ([gamma],[ital p]) data gives an indication of the proportion of emitted protons that have an accompanying neutron. This ratio, which can be interpreted as a lower limit for the neutron transmission in [sup 12]C, has been found to be 0.80[plus minus]0.08 for the 20--45 MeV neutrons examined in this experiment. Since the data sets were collected simultaneously, systematic uncertainties associated with the tagger and proton detector cancel in the ratio.

  13. Computational Models of X-Ray Burst Quenching Times and 12C Nucleosynthesis Following a Superburst

    SciTech Connect

    Fisker, J L

    2009-03-19

    Superbursts are energetic events on neutron stars that are a thousand times more powerful than ordinary type I X-ray bursts. They are believed to be powered by a thermonuclear explosion of accumulated {sup 12}C. However, the source of this {sup 12}C remains elusive to theoretical calculations and its concentration and ignition depth are both unknown. Here we present the first computational simulations of the nucleosynthesis during the thermal decay of a superbust, where X-ray bursts are quenched. Our calculations of the quenching time verify previous analytical calculations and shed new light on the physics of stable burning at low accretion rates. We show that concentrated (X{sub {sup 12}C} {approx}> 0.40), although insufficient, amounts of {sup 12}C are generated during the several weeks following the superburst where the decaying thermal flux of the superburst stabilizes the burning of the accreted material.

  14. Search for the rare γ-decay mode in 12C

    NASA Astrophysics Data System (ADS)

    Tsumura, M.; Kawabata, T.; Furuno, T.; Koshikawa, A.; Murata, M.; Morimoto, T.; Adachi, S.; Tamii, A.; Hatanaka, K.; Ito, T.; Zenihiro, J.; Kubono, S.; Itoh, M.; Matsuda, Y.; Maeda, Y.; Sakaguchi, S.; Akimune, H.; Fujimura, H.; Ou, I.; Hashimoto, T.; Iwamoto, C.

    2017-06-01

    Excited states in 12C nuclei play a very important role in the nucleosynthesis in the universe. 12C nuclei are synthesized by the triple α reaction. Normally the triple α process proceeds via the {0}2+ state (Hoyle states) at Ex = 7.65 MeV in 12C. However, at high temperature T > 109, the highly excited 3α resonance states such as the {3}1- state at Ex = 9.64 MeV might play a part of the triple α reaction. Unfortunately, the γ-decay probability of the {3}1- state has not been determined, therefore we planned to measure 1H(12C, 12Cp) reaction without measuring γ-rays. The test experiment using the solid hydrogen target and GAGG(Gd3Al2Ga3O12) was recently carried out at the cyclotron facility in RCNP. The results of the test experiment are reported in this paper.

  15. Cross Section Measurements of 12C+16O Fusion Reaction at Stellar Energies

    NASA Astrophysics Data System (ADS)

    Tan, Wanpeng; Fang, X.; Beard, M.; Gilardy, G.; Jung, H.; Liu, Q.; Lyons, S.; Robertson, D.; Setoodehnia, K.; Seymour, C.; Stech, E.; Vande Kolk, B.; Wiescher, M.; de Souza, R.; Hudan, S.; Singh, V.; Tang, X.; Uberseder, E.

    2016-09-01

    12C+16O is one of the three fusion reactions (12C+12C, 12C+16O, and 16O+16O) that play an important role at the late stage of stellar evolution in massive stars. The previous meassurements of its cross section at low energies rely on the singles measurements of either gamma rays or charged particles. New measurement was conducted for the 12C+16O reaction at Ecm = 3.64 - 4.93 MeV with the detection of both gammas and charged particles using the high intensity St ANA accelerator at the University of Notre Dame. The protons and alphas from the fusion evaporation were measured by a large area silicon strip detector array (SAND) while the gamma rays were detected by one large volume HPGe detector right after the target. Statistical model calculation were employed to interpret the experimental results. This provided a more reliable extrapolation for the 12C+16O fusion cross section, reducing substantially the uncertainty for stellar model simulations. This work was supported by the National Science Foundation through Grant Numbers PHY-1068192 and PHY-1419765 and the Joint Institute for Nuclear Astrophysics under Grant No. PHY-0822648.

  16. Dielectron Production in {sup 12}C+{sup 12}C Collisions at 2A GeV with the HADES Spectrometer

    SciTech Connect

    Agakichiev, G.; Gilardi, C.; Kuehn, W.; Lehnert, J.; Lins, E.; Metag, V.; Pechenov, V.; Perez, T.; Ritman, J.; Spruck, B.; Toia, A.; Agodi, C.; Bellia, G.; Coniglione, R.; Cosentino, L.; Finocchiaro, P.; Maiolino, C.; Piattelli, P.; Sapienza, P.; Vassiliev, D.

    2007-02-02

    The invariant-mass spectrum of e{sup +}e{sup -} pairs produced in {sup 12}C+{sup 12}C collisions at an incident energy of 2 GeV per nucleon has been measured for the first time. The measured pair production probabilities span over 5 orders of magnitude from the {pi}{sup 0}-Dalitz to the {rho}/{omega} invariant-mass region. Dalitz decays of {pi}{sup 0} and {eta} account for all the yield up to 0.15 GeV/c{sup 2}, but for only about 50% above this mass. A comparison with model calculations shows that the excess pair yield is likely due to baryon-resonance and vector-meson decays. Transport calculations based on vacuum spectral functions fail, however, to describe the entire mass region.

  17. The Nucleus Introduced

    PubMed Central

    Pederson, Thoru

    2011-01-01

    Now is an opportune moment to address the confluence of cell biological form and function that is the nucleus. Its arrival is especially timely because the recognition that the nucleus is extremely dynamic has now been solidly established as a paradigm shift over the past two decades, and also because we now see on the horizon numerous ways in which organization itself, including gene location and possibly self-organizing bodies, underlies nuclear functions. PMID:20660024

  18. Coherent fragmentation of 12C nuclei of momentum 4.5 GeV/ c per nucleon through the 8Beg.s.+4He channel in a nuclear photoemulsion containing lead nuclei

    NASA Astrophysics Data System (ADS)

    Belaga, V. V.; Gerasimov, S. G.; Dronov, V. A.; Peresadko, N. G.; Pisetskaya, A. V.; Rusakova, V. V.; Fetisov, V. N.; Kharlamov, S. P.; Shesterkina, L. N.

    2017-07-01

    A two-particle channel in which an unbound nucleus of 8Be in the ground state (8Beg.s.) was one of the fragments was selected among events where 12C nuclei of momentum 4.5 GeV/c per nucleon undergo coherent dissociation into three alpha particles. The events in question were detected in a track nuclear photoemulsion containing lead nuclei, which was irradiated at the synchrophasotron of the Laboratory of High Energies at the Joint Institute for Nuclear Research (JINR, Dubna). The average transverse momentum of alpha particles produced upon the decay of 8Beg.s. nuclei was 87±6 MeV/ c, while that for "single" alpha (αs) particles was 123±15 MeV/ c. The average value of the transverse-momentum transfer in the reaction being considered, Pt(12C), was 223 ± 20 MeV/ c. The average value of the cross section for this channel involving Ag and Br target nuclei was 13 ± 4 mb, while the cross section for the reaction on the Pb nucleus was 40 ± 15 mb. The Coulomb dissociation contribution evaluated on the basis of the number of events where the momentum P t(12C) did not exceed 0.1 GeV/c saturated about 20%. In nine events, the measured total transverse energy of the fragments in the reference frame comoving with the decaying carbon nucleus did not exceed 0.45 MeV, which did not contradict the excitation of the participant 12C nucleus to the level at 7.65 MeV. The average value of the transverse momentum in those events was 234 ± 25 MeV/ c.

  19. Quantitative analysis of two-neutron correlations in the 12C(18O,16O)14C reaction

    NASA Astrophysics Data System (ADS)

    Cavallaro, M.; Cappuzzello, F.; Bondì, M.; Carbone, D.; Garcia, V. N.; Gargano, A.; Lenzi, S. M.; Lubian, J.; Agodi, C.; Azaiez, F.; De Napoli, M.; Foti, A.; Franchoo, S.; Linares, R.; Nicolosi, D.; Niikura, M.; Scarpaci, J. A.; Tropea, S.

    2013-11-01

    The 12C(18O,16O)14C and 12,13C(18O,17O)13,14C reactions are studied at 84 MeV. Mass distributions and energy spectra of the ejectiles are measured, indicating the selectivity of these reactions to populate two- and one-neutron configurations in the states of the residual nucleus, respectively. The measured absolute cross-section angular distributions are analyzed by exact finite range coupled reaction channel calculations based on a parameter free double-folding optical potential. The form factors for the (18O,16O) reaction are extracted within an extreme cluster and independent particles scheme with shell-model-derived coupling strengths. The results show that the measured cross sections are accurately described for the first time without the need for any arbitrary scaling factor. The (18O,16O) reaction is thus found to be a powerful tool for quantitative spectroscopic studies of pair configurations in nuclear states.

  20. Systematic study of pre-equilibrium emission at low energies in 12C- and 16O-induced reactions

    NASA Astrophysics Data System (ADS)

    Sharma, Manoj Kumar; Singh, Pushendra P.; Singh, Devendra P.; Yadav, Abhishek; Sharma, Vijay Raj; Bala, Indu; Kumar, Rakesh; Unnati, Singh, B. P.; Prasad, R.

    2015-01-01

    Background: The role of pre-equilibrium emission within the heavy-ion fusion process has not been fully characterized. An accurate description of this process is important for understanding the formation of the compound nucleus in fusion reactions. Purpose: We develop a systematic description, based on experimental measurements, of the strength of the pre-equilibrium process in heavy-ion fusion reactions. Method: With a view to study pre-equilibrium emission process, the excitation functions for some neutron emission channels occurring in the fusion of 12C with 128Te and 169Tm, and of 16O with 159Tb,169Tm, and 181Ta, respectively, have been measured at incident energies from near the Coulomb barrier to ≈7 MeV/nucleon. The off-line γ -ray spectrometry-based activation technique has been used for the measurements of excitation functions. The measured excitation functions have been compared with theoretical predictions based on pure statistical model code pace4 and Geometry Dependent Hybrid (GDH)-based code alice-91. The strength of pre-equilibrium emission has also determined from comparison of the experimental excitation functions and the pace4 calculations. Results: The measured excitation functions are satisfactorily reproduced by the pace4 calculations in the energy region up to the peak position. However, at relatively higher energies, the enhancement of experimental cross sections in the tail portion of excitation functions as compared to the theoretical predictions of code pace4 has been observed. The observed deviation may be attributed to the pre-equilibrium emission of particles during the thermalization of the compound nucleus. Further, alice-91 calculations which include PE emission satisfactorily reproduce the experimental data even at higher energies, indicating the significant contribution of pre-equilibrium emissions. Conclusions: Analysis of data clearly indicates that pre-equilibrium emission is an important reaction mechanism even at low

  1. IMPROVED LINE DATA FOR THE SWAN SYSTEM {sup 12}C{sup 13}C ISOTOPOLOGUE

    SciTech Connect

    Ram, Ram S.; Brooke, James S. A.; Bernath, Peter F.; Sneden, Christopher; Lucatello, Sara E-mail: rr662@york.ac.uk E-mail: chris@verdi.as.utexas.edu

    2014-03-01

    We present new, accurate predictions for rotational line positions, excitation energies, and transition probabilities of the {sup 12}C{sup 13}C isotopologue Swan d{sup 3}Π-a{sup 3}Π system 0-0, 0–1, 0–2, 1–0, 1–1, 1–2, 2–0, 2–1, and 2–2 vibrational bands. The line positions and energy levels were predicted through new analyses of published laboratory data for the {sup 12}C{sup 13}C lines. Transition probabilities were derived from recent computations of transition dipole moments and related quantities. The {sup 12}C{sup 13}C line data were combined with similar data for {sup 12}C{sub 2,} reported in a companion paper, and applied to produce synthetic spectra of carbon-rich metal-poor stars that have strong C{sub 2} Swan bands. The matches between synthesized and observed spectra were used to estimate band head positions for a few of the {sup 12}C{sup 13}C vibrational bands and to verify that the new computed line data match observed spectra. The much weaker C{sub 2} lines of the bright red giant Arcturus were also synthesized in the band head regions.

  2. Binary reaction decays from {sup 24}Mg+{sup 12}C

    SciTech Connect

    Beck, C.; Papka, P.; Zafra, A. Sanchez i; Azaiez, F.; Bednarczyk, P.; Courtin, S.; Curien, D.; Dorvaux, O.; Lebhertz, D.; Nourreddine, A.; Rousseau, M.; Thummerer, S.; Oertzen, W. von; Gebauer, B.; Wheldon, C.; Kokalova, Tz.; Angelis, G. de; Gadea, A.; Lenzi, S.; Szilner, S.

    2009-09-15

    Charged-particle and {gamma} decays in {sup 24}Mg* are investigated for excitation energies where quasimolecular resonances appear in {sup 12}C+{sup 12}C collisions. Various theoretical predictions for the occurrence of superdeformed and hyperdeformed bands associated with resonance structures with low spin are discussed within the measured {sup 24}Mg* excitation energy region. The inverse kinematics reaction {sup 24}Mg+{sup 12}C is studied at E{sub lab}({sup 24}Mg)=130 MeV, an energy that enables the population of {sup 24}Mg states decaying into {sup 12}C+{sup 12}C resonant breakup states. Exclusive data were collected with the Binary Reaction Spectrometer in coincidence with Euroball IV installed at the Vivitron tandem facility at Strasbourg. Specific structures with large deformation were selectively populated in binary reactions, and their associated {gamma} decays studied. Coincident events associated with inelastic and {alpha}-transfer channels have been selected by choosing the excitation energy or the entry point via the two-body Q values. The analysis of the binary reaction channels is presented with a particular emphasis on {sup 24}Mg-{gamma}, {sup 20}Ne-{gamma}, and {sup 16}O-{gamma} coincidences. New information (spin and branching ratios) is deduced on high-energy states in {sup 24}Mg and {sup 16}O, respectively.

  3. High Resolution Laser Spectroscopy of Mg12C12CD, Mg13C13CH and Mg12C_4H

    NASA Astrophysics Data System (ADS)

    Forthomme, D.; Linton, C.; Tokaryk, D. W.; Adam, A. G.; Granger, A. D.

    2010-06-01

    Carbon and magnesium are abundant elements in the interstellar medium, so it is possible that carbon chain molecules containing a magnesium atom may exist in this environment. With this in mind, radical molecules of the form MgC2nH (n = 1,2,3) have been frequent subjects of both experimental and theoretical studies In this presentation we will discuss our high-resolution experiments of the ~A2Π-~X2Σ+ transitions in the isotopologues Mg12C12CD and Mg13C13CH, which complement our earlier investigation of this spectrum in Mg12C12CH^b. The data permit us to determine the lengths of individual bonds to high precision. In addition, we have expanded on previous studies of the ~A2Π-~X2Σ+ transition of Mg12C_4H, conducted at medium resolution. The parameters obtained from our high-resolution spectra are compared with those obtained from theoretical structure calculations. H. Ding, C. Apetrei, L. Chacaga, J. P. Maier, Astrophys. J. 677 (2008) 348-352 D. W. Tokaryk, A. G. Adam, W. S. Hopkins, J. Mol. Spectrosc. 230 (2005) 54-61 D. E. Woon, Chem. Phys. Lett. 274 (1997) 299-305 C. A. Thompson and L. Andrews, J. Am. Chem. Soc. 118 (1996) 10242-10249 X. Guo, J. Zhang, J. Li, L. Jiang, J. Zhang, Chem. Phys 360 (2009) 27-31 E. Chasovskikh, E. B. Jochnowitz, J. P. Maier, J. Phys. Chem. A. 112 (2008) 8686-8689.

  4. Ruminant Methane δ (13C/12C) - Values: Relation to Atmospheric Methane

    NASA Astrophysics Data System (ADS)

    Rust, Fleet

    1981-03-01

    The δ (13C/12C) - values of methane produced by fistulated steers, dairy cattle, and wethers, and dairy and beef cattle herds show a bimodal distribution that appears to be correlated with the plant type (C3 or C4, that is, producing either a three- or a four-carbon acid in the first step of photosynthesis) consumed by the animals. These results indicate that cattle and sheep, on a global basis, release methane with an average δ (13C/12C) value of -60 and -63 per mil, respectively. Together they are a source of atmospheric methane whose δ (13C/12C) is similar to published values for marsh gas and cannot explain the 20 per mil higher values for atmospheric methane.

  5. Evidence for a new {sup 12}C state at 13.3 MeV

    SciTech Connect

    Freer, M.; Ashwood, N. I.; Barr, M.; Curtis, N.; Malcolm, J. D.; Wheldon, C.; Ziman, V. A.; Almaraz-Calderon, S.; Aprahamian, A.; Bucher, B.; Couder, M.; Fang, X.; Jung, F.; Lu, W.; Roberts, A.; Tan, W. P.; Copp, P.; Lesher, S.

    2011-03-15

    The two reactions {sup 12}C({sup 4}He,{sup 4}He + {sup 4}He + {sup 4}He){sup 4}He and {sup 9}Be({sup 4}He, {sup 4}He + {sup 4}He + {sup 4}He)n were measured using an array of four double-sided strip detectors. Excited states in {sup 12}C were reconstructed filtered by the condition that the {alpha}-decay proceeded via the {sup 8}Be ground state. In both measurements, evidence was found for a new state at 13.3(0.2) MeV with a width 1.7(0.2) MeV. Angular correlation measurements from the {sup 12}C({sup 4}He, {sup 4}He + {sup 4}He + {sup 4}He){sup 4}He reaction indicates that the state may have J{sup {pi}}=4{sup +}.

  6. Investigation of the Hoyle state in12C with a new hodoscope detector

    NASA Astrophysics Data System (ADS)

    Dell'Aquila, D.; Lombardo, I.; Vigilante, M.; De Luca, M.; Acosta, L.; Agodi, C.; Cappuzzello, F.; Carbone, D.; Cavallaro, M.; Cherubini, S.; Cvetinovic, A.; D'Agata, G.; Francalanza, L.; Guardo, G. L.; Gulino, M.; Indelicato, I.; La Cognata, M.; Lamia, L.; Ordine, A.; Pizzone, R.; Puglia, S.; Rapisarda, G.; Romano, S.; Santagati, G.; Spartà, R.; Spitaleri, C.; Tumino, A.; Verde, G.

    2017-07-01

    The {0}2+ state in12C (7.654MeV, the Hoyle state) is important for the understanding of clustering phenomena in nuclei. The pronounced cluster nature of this state allows the triple-α process in stars with a reaction rate regulated by its structure properties. To precisely estimate the direct component in the 3α decay mechanism of the Hoyle state, we developed a new experiment using the14N(d,α)12C reaction at 10.5MeV. An anti-coincidence telescope was used to identify the α ejectiles leading the residual12C in the Hoyle state, while its decays in 3α were studied by means of a new hodoscope of silicon detectors, superOSCAR, placed in kinematical coincidence to fully reconstruct the events. Details of the experiment and preliminary results are discussed in the text.

  7. Reassessment of the 13C/12C and 14C/12C isotopic fractionation ratio and its impact on high-precision radiocarbon dating

    NASA Astrophysics Data System (ADS)

    Fahrni, Simon M.; Southon, John R.; Santos, Guaciara M.; Palstra, Sanne W. L.; Meijer, Harro A. J.; Xu, Xiaomei

    2017-09-01

    The vast majority of radiocarbon measurement results (14C/12C isotopic ratios or sample activities) are corrected for isotopic fractionation processes (measured as 13C/12C isotopic ratios) that occur in nature, in sample preparation and measurement. In 1954 Harmon Craig suggested a value of 2.0 for the fractionation ratio b that is used to correct 14C/12C ratios for shifts in the 13C/12C ratios and this value has been applied by the radiocarbon community ever since. While theoretical considerations suggest moderate deviations of b from 2.0, some measurements have suggested larger differences (e.g. b = 2.3, measured by Saliège and Fontes in 1984). With the high precision attained in radiocarbon measurements today (±2‰), even a relatively small deviation of b from 2.0 can impact the accuracy of radiocarbon data, and it is, therefore, of interest to re-evaluate the fractionation corrections. In the present study, the fractionation ratio b was determined by independent experiments on the chemical reduction of carbon dioxide (CO2) to elemental carbon (graphitization reaction) and on the photosynthetic uptake of CO2 by C3 and C4 plants. The results yielded b = 1.882 ± 0.019 for the reduction of CO2 to solid graphite and b = 1.953 ± 0.025 for the weighted mean of measurements involving C3 and C4 photosynthesis pathways. In addition, the analysis of over 9600 full-sized OX-I and OX-II normalizing standards measured between 2002 and 2012 confirms b values lower than 2.0. The obtained values are in good agreement with quantum mechanical estimates of the equilibrium fractionation and classic kinetic fractionation as well as with results from other light three-isotope systems (oxygen, magnesium, silicon and sulfur). While the value of the fractionation ratio varies with the relative importance of kinetic and equilibrium fractionation, the values obtained in the present study cluster around b = 1.9. Our findings suggest that a significant fraction of all samples

  8. Double Folding Potential of Different Interaction Models for 16O + 12C Elastic Scattering

    NASA Astrophysics Data System (ADS)

    Hamada, Sh.; Bondok, I.; Abdelmoatmed, M.

    2016-12-01

    The elastic scattering angular distributions for 16O + 12C nuclear system have been analyzed using double folding potential of different interaction models: CDM3Y1, CDM3Y6, DDM3Y1 and BDM3Y1. We have extracted the renormalization factor N r for the different concerned interaction models. Potential created by BDM3Y1 model of interaction has the shallowest depth which reflects the necessity to use higher renormalization factor. The experimental angular distributions for 16O + 12C nuclear system in the energy range 115.9-230 MeV exhibited unmistakable refractive features and rainbow phenomenon.

  9. CO bands in V4334 Sgr (Sakurai's Object): The 12C/13C ratio

    NASA Astrophysics Data System (ADS)

    Pavlenko, Ya. V.; Geballe, T. R.; Evans, A.; Smalley, B.; Eyres, S. P. S.; Tyne, V. H.; Yakovina, L. A.

    2004-04-01

    We present the results of our analysis of a high resolution (R≃30 000) infrared spectrum of V4334 Sgr (Sakurai's Object) around the first overtone CO bands, obtained in 1998 July. The 12CO and 13CO bands are well-resolved, and we compute synthetic hydrogen-deficient model atmosphere spectra to determine the 12C/13C ratio. We find 12C/13C ≃ 4 ± 1, consistent with the interpretation of V4334 Sgr as an object that has undergone a very late thermal pulse.

  10. New Astrophysical Reaction Rate for the 12C(α, γ)16O Reaction

    NASA Astrophysics Data System (ADS)

    An, Zhen-Dong; Ma, Yu-Gang; Fan, Gong-Tao; Li, Yong-Jiang; Chen, Zhen-Peng; Sun, Ye-Ying

    2016-01-01

    A new astrophysical reaction rate for 12C(α, γ)16O has been evaluated on the basis of a global R-matrix fitting to the available experimental data. The reaction rates of 12C(α, γ)16O for stellar temperatures between 0.04 ≤ T9 ≤ 10 are provided in a tabular form and by an analytical fitting expression. At T9 = 0.2, the reaction rate is (7.83 ± 0.35) × 1015 cm3 mol-1 s-1, where stellar helium burning occurs.

  11. 40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts are...

  12. 40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts are...

  13. 40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts are...

  14. 40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts are...

  15. 40 CFR 180.1068 - C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false C12-C18 fatty acid potassium salts... RESIDUES IN FOOD Exemptions From Tolerances § 180.1068 C12-C18 fatty acid potassium salts; exemption from the requirement of a tolerance. C12-C18 fatty acids (saturated and unsaturated) potassium salts are...

  16. Kaon-nucleus scattering

    NASA Technical Reports Server (NTRS)

    Hong, Byungsik; Maung, Khin Maung; Wilson, John W.; Buck, Warren W.

    1989-01-01

    The derivations of the Lippmann-Schwinger equation and Watson multiple scattering are given. A simple optical potential is found to be the first term of that series. The number density distribution models of the nucleus, harmonic well, and Woods-Saxon are used without t-matrix taken from the scattering experiments. The parameterized two-body inputs, which are kaon-nucleon total cross sections, elastic slope parameters, and the ratio of the real to the imaginary part of the forward elastic scattering amplitude, are presented. The eikonal approximation was chosen as our solution method to estimate the total and absorptive cross sections for the kaon-nucleus scattering.

  17. Kaon-nucleus scattering

    NASA Technical Reports Server (NTRS)

    Hong, Byungsik; Buck, Warren W.; Maung, Khin M.

    1989-01-01

    Two kinds of number density distributions of the nucleus, harmonic well and Woods-Saxon models, are used with the t-matrix that is taken from the scattering experiments to find a simple optical potential. The parameterized two body inputs, which are kaon-nucleon total cross sections, elastic slope parameters, and the ratio of the real to imaginary part of the forward elastic scattering amplitude, are shown. The eikonal approximation was chosen as the solution method to estimate the total and absorptive cross sections for the kaon-nucleus scattering.

  18. Effect of {sup 12}C+{sup 12}C reaction and convective mixing on the progenitor mass of ONe white dwarfs

    SciTech Connect

    Halabi, Ghina M. El Eid, Mounib

    2015-02-24

    Stars in the mass range ∼8 - 12 M{sub ⊙} are the most numerous massive stars. This mass range is critical because it may lead to supernova (SN) explosion, so it is important for the production of heavy elements and the chemical evolution of the galaxy. We investigate the critical transition mass (M{sub up}), which is the minimum initial stellar mass that attains the conditions for hydrostatic carbon burning. Stars of masses < M{sub up} evolve to the Asymptotic Giant Branch and then develop CO White Dwarfs, while stars of masses ≥ M{sub up} ignite carbon in a partially degenerate CO core and form electron degenerate ONe cores. These stars evolve to the Super AGB (SAGB) phase and either become progenitors of ONe White Dwarfs or eventually explode as electron-capture SN (EC-SN). We study the sensitivity of M{sub up} to the C-burning reaction rate and to the treatment of convective mixing. In particular, we show the effect of a recent determination of the {sup 12}C+{sup 12}C fusion rate, as well as the extension of the convective core during hydrogen and helium burning on M{sub up} in solar metallicity stars. We choose the 9 M{sub ⊙} model to show the detailed characteristics of the evolution with the new C-burning rate.

  19. Searching for the low-energy resonances in the 12C(12C,n)23Mg reaction cross section relevant for s-process nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Bucher, B.; Fang, X.; Almaraz-Calderon, S.; Alongi, A.; Ayangeakaa, A. D.; Beard, M.; Best, A.; Browne, J.; Cahillane, C.; Couder, M.; deBoer, R.; Kontos, A.; Long, A.; Lu, W.; Lyons, S.; Notani, M.; Patel, D.; Paul, N.; Roberts, A.; Robertson, D.; Smith, K.; Stech, E.; Talwar, R.; Tan, W.; Tang, X. D.

    2013-03-01

    The 12C(12C,n) reaction (Q=-2.6 MeV) is a potential neutron source for the weak s-process occurring in shell-carbon burning of massive stars. The uncertainty in this reaction rate limits our understanding of the production of elements in the range 60 < A < 110. Current stellar models must rely on the smooth extrapolation of a dubious statistical model calculation based on experimental data taken at energies well above the Gamow window which lies below 3.2 MeV. At Notre Dame, this reaction cross section has been measured in finer steps at energies above 3.5 MeV, while successful measurements down to 3.1 MeV have just recently been achieved. In addition, a new extrapolation based on measurements of the mirror system has been developed which predicts a number of low-energy resonances while accounting well for the high-energy resonances. An overview of this work along with the most recent results and astrophysical implications are presented.

  20. 33 CFR 157.12c - Construction, maintenance, security, calibration, and training.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... RELATING TO TANK VESSELS CARRYING OIL IN BULK Design, Equipment, and Installation § 157.12c Construction, maintenance, security, calibration, and training. (a) The oil discharge monitoring and control system must be designed to ensure that user access is restricted to essential controls. Access beyond these controls must...

  1. 33 CFR 157.12c - Construction, maintenance, security, calibration, and training.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... RELATING TO TANK VESSELS CARRYING OIL IN BULK Design, Equipment, and Installation § 157.12c Construction, maintenance, security, calibration, and training. (a) The oil discharge monitoring and control system must be designed to ensure that user access is restricted to essential controls. Access beyond these controls must...

  2. 33 CFR 157.12c - Construction, maintenance, security, calibration, and training.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... RELATING TO TANK VESSELS CARRYING OIL IN BULK Design, Equipment, and Installation § 157.12c Construction, maintenance, security, calibration, and training. (a) The oil discharge monitoring and control system must be designed to ensure that user access is restricted to essential controls. Access beyond these controls must...

  3. 33 CFR 157.12c - Construction, maintenance, security, calibration, and training.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... RELATING TO TANK VESSELS CARRYING OIL IN BULK Design, Equipment, and Installation § 157.12c Construction, maintenance, security, calibration, and training. (a) The oil discharge monitoring and control system must be designed to ensure that user access is restricted to essential controls. Access beyond these controls must...

  4. Interaction of (12)C ions with the mouse retinal response to light.

    PubMed

    Carozzo, Simone; Ball, Sherry L; Narici, Livio; Schardt, Dieter; Sannita, Walter G

    2015-06-26

    Astronauts in orbit reported phosphenes varying in shape and orientation across the visual field; incidence was correlated with the radiation flux. Patients with skull tumors treated by (12)C ions and volunteers whose posterior portion of the eye was exposed to highly ionizing particles in early studies reported comparable percepts. An origin in radiation activating the visual system is suggested. Bursts (∼ 4 ms) of (12)C ions evoked electrophysiological mass responses comparable to those to light in the retina of anesthetized wild-type mice at threshold flux intensities consistent with the incidence observed in humans. The retinal response amplitude increased in mice with ion intensity to a maximum at ∼ 2000 ions/burst, to decline at higher intensities; the inverted-U relationship suggests complex effects on retinal structures. Here, we show that bursts of (12)C ions presented simultaneously to white light stimuli reduced the presynaptic mass response to light in the mouse retina, while increasing the postsynaptic retinal and cortical responses amplitude and the phase-locking to stimulus of cortical low frequency and gamma (∼ 25-45 Hz) responses. These findings suggest (12)C ions to interfere with, rather than mimicking the light action on photoreceptors; a parallel action on other retinal structures/mechanisms resulting in cortical activation is conceivable. Electrophysiological visual testing appears applicable to monitor the radiation effects and in designing countermeasures to prevent functional visual impairment during operations in space. Copyright © 2015. Published by Elsevier Ireland Ltd.

  5. Tetrahedral 4 α and 12C+α cluster structures in 16O

    NASA Astrophysics Data System (ADS)

    Kanada-En'yo, Yoshiko

    2017-09-01

    I have investigated structures of the ground and excited states of 16O with the method of variation after spin-parity projection in the antisymmetrized molecular dynamics model combined with the generator coordinate method of 12C+α cluster. The calculation reasonably reproduces the experimental energy spectra; E 2 , E 3 , E 4 , and I S 1 transitions; and α -decay properties. The formation of 4 α clusters has been confirmed from nucleon degrees of freedom in the AMD model without assuming the existence of any clusters. They form "tetrahedral" 4 α - and 12C+α cluster structures. The 12C+α structure constructs the Kπ=0+ band consisting of the 02+, 21+, and 41+ states and the Kπ=0- band of the 12-, 32-, and 51- states. The 01+, 31-, and 42+ states are assigned to the ground band constructed from the tetrahedral 4 α structure. The 01+ and 31- are approximately interpreted as Td band members with the ideal tetrahedral configuration. The ground-state 4 α correlation plays an important role in the enhancement of the E 3 transition strength to the 31-. The 42+ state is not the ideal Td member but constructed from a distorted tetrahedral 4 α structure. Moreover, significant state mixing of the tetrahedral 4 α and 12C+α cluster structures occurs between 41+ and 42+ states, indicating that the Td configuration of 4 α is rather fragile at Jπ=4+ .

  6. Existence of inelastic supernumerary nuclear rainbow in 16O+12C scattering

    NASA Astrophysics Data System (ADS)

    Ohkubo, S.; Hirabayashi, Y.; Ogloblin, A. A.

    2017-08-01

    The existence of a supernumerary nuclear rainbow in inelastic scattering is reported. This is done by studying inelastic 16O scattering from 12C, exciting the 2+ (4.44 MeV) state of 12C and elastic scattering at the incident energies in the range 124-200 MeV, using the coupled channels method. An extended double folding potential is used. This is derived from realistic wave functions for 12C and 16O calculated with a microscopic α cluster model and a finite-range density-dependent nucleon-nucleon force. Excitations to the 2+ (4.44 MeV), 3- (9.64 MeV), and 4+ (14.08 MeV) states of 12C, and the 3- (6.13 MeV) and 2+ (6.92 MeV) states of 16O are included in the coupled channels calculations. The emergence of the supernumerary bow is understood by the properties of both the Luneburg-lens-like potential in the internal region and diffuse attraction in the outer region. The existence of a supernumerary rainbow for inelastic scattering in addition to the existence of a dynamically created secondary rainbow and a dynamically refracted primary rainbow for elastic scattering, which are not observed in meteorological rainbows, further deepens the understanding of nuclear rainbows.

  7. 12C/13C ratio in ethane on titan and implications for methane's replenishment.

    PubMed

    Jennings, Donald E; Romani, Paul N; Bjoraker, Gordon L; Sada, Pedro V; Nixon, Conor A; Lunsford, Allen W; Boyle, Robert J; Hesman, Brigette E; McCabe, George H

    2009-10-22

    The (12)C/(13)C abundance ratio in ethane in the atmosphere of Titan has been measured at 822 cm(-1) from high spectral resolution ground-based observations. The value, 89(8), coincides with the telluric standard and also agrees with the ratio seen in the outer planets. It is almost identical to the result for ethane on Titan found by the composite infrared spectrometer (CIRS) on Cassini. The (12)C/(13)C ratio for ethane is higher than the ratio measured in atmospheric methane by Cassini/Huygens GCMS, 82.3(1), representing an enrichment of (12)C in the ethane that might be explained by a kinetic isotope effect of approximately 1.1 in the formation of methyl radicals. If methane is being continuously resupplied to balance photochemical destruction, then we expect the isotopic composition in the ethane product to equilibrate at close to the same (12)C/(13)C ratio as that in the supply. The telluric value of the ratio in ethane then implies that the methane reservoir is primordial.

  8. Enhanced hydrogen adsorption on Li-coated B12C6N6

    NASA Astrophysics Data System (ADS)

    Jin, Xueling; Qi, Pengtang; Yang, Huihui; Zhang, Yan; Li, Jinyun; Chen, Hongshan

    2016-10-01

    The hydrogen storage property of Li-coated B12C6N6 is investigated by density functional theory calculations. B12C6N6 is an electron deficient fullerene. Li atoms can be strongly bound to this cage by donating their valance electrons to the virtual 2p orbitals of carbon in the cluster. The binding energy (-2.90 eV) is much larger than the cohesive energy (1.63 eV) of bulk Li, and it prevents the Li atoms from aggregation. The coated Li atoms have large positive charges and the adsorbed hydrogen molecules can be moderately polarized by the Li+ ions. The computation shows that each Li atom coated on B12C6N6 can hold 2-3 H2 molecules with adsorption energies in the range of 0.21-0.24 eV/H2. The B12C6N6Li8 can adsorb 16 H2 and achieve a gravimetric hydrogen density of 8.63 wt. %. The present results indicate that alkali-metal atoms coated on electron deficient fullerenes can serve as hydrogen storage materials that can operate at ambient temperatures with high recycling storage capacity.

  9. Enhanced hydrogen adsorption on Li-coated B12C6N6.

    PubMed

    Jin, Xueling; Qi, Pengtang; Yang, Huihui; Zhang, Yan; Li, Jinyun; Chen, Hongshan

    2016-10-28

    The hydrogen storage property of Li-coated B12C6N6 is investigated by density functional theory calculations. B12C6N6 is an electron deficient fullerene. Li atoms can be strongly bound to this cage by donating their valance electrons to the virtual 2p orbitals of carbon in the cluster. The binding energy (-2.90 eV) is much larger than the cohesive energy (1.63 eV) of bulk Li, and it prevents the Li atoms from aggregation. The coated Li atoms have large positive charges and the adsorbed hydrogen molecules can be moderately polarized by the Li(+) ions. The computation shows that each Li atom coated on B12C6N6 can hold 2-3 H2 molecules with adsorption energies in the range of 0.21-0.24 eV/H2. The B12C6N6Li8 can adsorb 16 H2 and achieve a gravimetric hydrogen density of 8.63 wt. %. The present results indicate that alkali-metal atoms coated on electron deficient fullerenes can serve as hydrogen storage materials that can operate at ambient temperatures with high recycling storage capacity.

  10. Ethane's 12C/13C Ratio in Titan: Implications for Methane Replenishment

    NASA Technical Reports Server (NTRS)

    Jennings, Donald E.; Nixon, C. A.; Romani, P. N.; Bjoraker, G. L.; Sada, P. V.; Lunsford, A. W.; Boyle, R. J.; Hesman, B. E.; McCabe, G. H.

    2009-01-01

    As the .main destination of carbon in the destruction of methane in the atmosphere of Titan, ethane provides information about the carbon isotopic composition of the reservoir from which methane is replenished. If the amount of methane entering the atmosphere is presently equal to the amount converted to ethane, the 12C/13C ratio in ethane should be close to the ratio in the reservoir. We have measured the 12C/13C ratio in ethane both with Cassini CIRS(exp 1) and from the ground and find that it is very close to the telluric standard and outer planet values (89), consistent with a primordial origin for the methane reservoir. The lower 12C/13C ratio measured for methane by Huygens GCMS (82.3) can be explained if the conversion of CH4 to CH3 (and C2H6) favors 12C over 13C with a carbon kinetic isotope effect of 1.08. The time required for the atmospheric methane to reach equilibrium, i.e., for replenishment to equal destruction, is approximately 5 methane atmospheric lifetimes.

  11. Experimental evidence for a fusion enhancement in 19O+12C at near barrier energies

    NASA Astrophysics Data System (ADS)

    Singh, Varinderjit; Steinbach, T. K.; Vadas, J.; Wiggins, B. B.; Hudan, S.; Desouza, R. T.; Baby, L. T.; Tripathi, V.; Kuvin, S. A.; Wiedenhover, I.; Umar, A. S.; Oberacker, V. E.

    2016-03-01

    Fusion of neutron-rich light nuclei in the outer crust of an accreting neutron star has been proposed as responsible for triggering X-ray super-bursts. The underlying hypothesis in this proposition is that the fusion of neutron-rich nuclei is enhanced as compared to stable nuclei. To investigate this hypothesis, an experiment has been performed to measure the fusion excitation function for 18O and 19O nuclei incident on a 12C target. A beam of 19O was produced by the 18O(d,p) reaction at Florida State University and separated using the RESOLUT mass spectrometer. The resulting 19O beam bombarded a 100 μg/cm2 12C target at an intensity of 2-4 x 104p/s. Evaporation residues resulting from the de-excitation of the fusion product were distinguished by measuring their energy and time-of-flight. Evaporation residues were detected with high efficiency by measuring them in the angular range 4.4° <=θlab <= 11.7°. The fusion cross-section has been measured down to 170 mb level. As compared to 18O+12C the fusion cross-section for 19O+12C is enhanced by approximately a factor of 3 times at the lowest energy measured. The measured excitation function will be compared with theoretical calculations. Supported by the US DOE under Grant No. DEFG02-88ER-40404.

  12. Relativistic calculations of induced polarization in 12C(e,e'p-->) reactions

    NASA Astrophysics Data System (ADS)

    Johansson, J. I.; Sherif, H. S.

    1999-06-01

    Relativistic calculations of the induced proton polarization in quasifree electron scattering on 12C are presented. Good agreement with the experimental data of Woo et al. is obtained. The relativistic calculations yield a somewhat better description of the data than the nonrelativistic ones. Differences between the two approaches are more pronounced at larger missing momenta suggesting further experimental work in this region.

  13. Inelastic pion scattering to 2 1+ states of pre12C and 28Si

    NASA Astrophysics Data System (ADS)

    Amos, K.; Berge, L.

    1983-08-01

    Large basis, microscopic models of nuclear structure have been used to specify the “collective” form factors for inelastic scattering to the 2 1+ states in 12C and 28Si. They have been used in a Distorted Wave Impulse Approximation, with π-nucleon t-matrices fixed by elastic scattering analyses, to fit inelastic pion scattering data.

  14. {sup 15}N(p,{alpha}{sub 0}){sup 12}C S factor

    SciTech Connect

    Barker, F. C.

    2008-10-15

    Experimental values of the astrophysical S factor for the {sup 15}N(p,{alpha}{sub 0}){sup 12}C reaction are available both from direct measurements and from the Trojan horse method. We here use R-matrix formulas to fit these values and to extrapolate to zero energy to obtain values of S(0)

  15. The widths of the α decaying states of 12C within the three-cluster model

    NASA Astrophysics Data System (ADS)

    Fedorov, D. V.; Jensen, A. S.; Fynbo, H. O. U.

    2003-05-01

    We estimate the widths of the alpha decaying states of 12C (1+, 1-, 1-1, 2+, 2-, 3-, and 4+) within the three-alpha cluster model. We solve the Faddeev equations using the hyperspheric approach and calculate the decisive effective hyper-radial barriers. We calculate the widths in the WKB approximation and compare with experimental data.

  16. GRH Characterization using 4.4 MeV ^12C Gamma-Rays

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Herrmann, H. W.; Langenbrunner, J. R.; Young, C. S.; Barton, B. T.; Mack, J. M.; McEvoy, A. M.; Evans, S.; Sedillo, T.; Stoeffl, W.; Horsfield, C. J.; Rubery, M.; Miller, E. K.; Grafil, E.

    2010-11-01

    The OMEGA Gamma Reaction History (GRH) diagnostic has been characterized using a relatively well-known source of 4.43 MeV gamma rays produced from inelastic scattering of DT-neutrons off of a graphite puck placed near an imploding capsule at the OMEGA laser facility. An independently measured neutron yield, combined with the known ^12C density and ^12C(n,n'γ)^12C cross-section, allows an in-situ calibration of the GRH detection efficiency at 4.43 MeV. GRH data were collected at two different ^12C target locations to confirm the published angular distribution of gamma rays and were compared with MCNP modeling predictions. These in-situ calibrations were used to validate the GRH simulation code based on a coupled MCNP/ACCEPT Monte-Carlo method. By combining these results with other absolute calibration methods, we are able to infer a DT branching ratio for gamma to neutron production and to make an accurate plastic ablator areal density measurement.

  17. Towards Understanding the DO-178C / ED-12C Assurance Case

    NASA Technical Reports Server (NTRS)

    Holloway, C M.

    2012-01-01

    This paper describes initial work towards building an explicit assurance case for DO-178C / ED-12C. Two specific questions are explored: (1) What are some of the assumptions upon which the guidance in the document relies, and (2) What claims are made concerning test coverage analysis?

  18. 16O+12C resonances within the strong absorption region for Ec.m.>23 MeV

    NASA Astrophysics Data System (ADS)

    Jachcinski, C. M.; Braun-Munzinger, P.; Berkowitz, G. M.; Freifelder, R. H.; Gai, M.; Renner, T. R.; Uhlhorn, C. D.

    1980-07-01

    Excitation functions for 12C(16O, 16O)12C elastic and inelastic scattering have been measured in the energy range 23<=Ec.m.<=32 MeV. Two strong structures at Ec.m.=25.5 and 29.6 MeV are observed in the 12C + 16O(3-,6.13 MeV) exit channel; angular correlation measurements at these energies suggest spin assignments of 15- and 16+, respectively. NUCLEAR REACTIONS 12C(16O, 16O*)12C*; Ec.m.=23-32 MeV, θc.m.(16O)=130°-155° measured σ(E) angular correlations.

  19. A = 10 nuclei and 12C with SRG evolved chiral three-nucleon interactions

    NASA Astrophysics Data System (ADS)

    Maris, Pieter; Vary, James; Calci, Angelo; Langhammer, Joachim; Binder, Sven; Roth, Robert

    2014-09-01

    We investigate selected static and transition properties of A = 10 nuclei and 12C using ab initio No-Core Shell Model (NCSM) methods with chiral two- and SRG-evolved three-nucleon interactions. We examine the dependences of observables on the SRG evolution scale and on the model-space parameters. We obtain nearly converged low-lying excitation spectra for 12C. We compare results of the full NCSM with the Importance Truncated NCSM in large model spaces for benchmarking purposes in 12C. The agreement of some observables with experiment is improved significantly by the inclusion of 3N interactions, e.g., the B(M1) from the first (Jπ , T) = (1+ , 1) state to the ground state of 12C. However, in some cases the agreement deteriorates, e.g., for the excitation energy of the first (1+ , 0) state, leaving room for improved next-generation chiral Hamiltonians. On the other hand, the excitation energies of 10C, 10B, and 10Be are not as well converged as those of 12C. In particular the lowest two (1+ , 0) states of 10B are sensitive to both the basis truncation parameters and the 3N interaction. We investigate selected static and transition properties of A = 10 nuclei and 12C using ab initio No-Core Shell Model (NCSM) methods with chiral two- and SRG-evolved three-nucleon interactions. We examine the dependences of observables on the SRG evolution scale and on the model-space parameters. We obtain nearly converged low-lying excitation spectra for 12C. We compare results of the full NCSM with the Importance Truncated NCSM in large model spaces for benchmarking purposes in 12C. The agreement of some observables with experiment is improved significantly by the inclusion of 3N interactions, e.g., the B(M1) from the first (Jπ , T) = (1+ , 1) state to the ground state of 12C. However, in some cases the agreement deteriorates, e.g., for the excitation energy of the first (1+ , 0) state, leaving room for improved next-generation chiral Hamiltonians. On the other hand, the excitation

  20. New determination of 12C(α,γ)16O reaction rate

    NASA Astrophysics Data System (ADS)

    Oulebsir, N.

    2015-12-01

    The reaction 12C(α,γ)16O was investigated through the direct α-transfer reaction (7Li,t) at 28 and 34 MeV incident energies. We determined the reduced α-widths of the sub-threshold 2+ and 1- states of 16O from the DWBA analysis of the transfer reaction 12C(7Li,t)16O performed at two incident energies. The obtained result for the 2+ and 1- sub-threshold resonances as introduced in the R-matrix fitting of radiative capture and elastic-scattering data to determine the E2 and E1 S-factor from 0.01MeV to 4.2MeV in the center-of-mass energy. After determining the astrophysic factor of 12C(α,γ)16O S(E) with Pierre Descouvement code, I determined numerically the new reaction rate of this reaction at a different stellar temperature (0.06 Gk-2 GK). The 12C(α,γ)16O reaction rate at T9 = 0.2 is [7.21-2.25+2.15] × 10-15 cm3 s-1 mol-1. Some comparisons and discussions about our new 12C(α,γ)16O reaction rate are presented. The agreements of the reaction rate below T9 = 2 between our results and with those proposed by NACRE indicate that our results are reliable, and they could be included in the astrophysical reaction rate network.

  1. Investigating {sup 13}C+{sup 12}C reaction by the activation method. Sensitivity tests

    SciTech Connect

    Chesneanu, Daniela Trache, L.; Margineanu, R.; Pantelica, A.; Ghita, D.; Straticiuc, M.; Burducea, I.; Blebea-Apostu, A. M.; Gomoiu, C. M.; Tang, X.

    2015-02-24

    We have performed experiments to check the limits of sensitivity of the activation method using the new 3 MV Tandetron accelerator and the low and ultra-low background laboratories of the “Horia Hulubei” National Institute of Physics and Nuclear Engineering (IFIN-HH). We have used the {sup 12}C+{sup 13}C reaction at beam energies E{sub lab}= 6, 7 and 8 MeV. The knowledge of this fusion cross section at deep sub-barrier energies is of interest for astrophysical applications, as it provides an upper limit for the fusion cross section of {sup 12}C+{sup 12}C over a wide energy range. A {sup 13}C beam with intensities 0.5–2 particleμA was provided by the accelerator and used to bombard graphite targets, resulting in activation with {sup 24}Na from the {sup 12}C({sup 13}C,p) reaction. The 1369 and 2754 keV gamma-rays from {sup 24}Na de-activation were clearly observed in the spectra obtained in two different laboratories used for measurements at low and ultralow background: one at the surface and one located underground in the Unirea salt mine from Slanic Prahova, Romania. In the underground laboratory, for E{sub lab} = 6 MeV we have measured an activity of 0.085 ± 0.011 Bq, corresponding to cross sections of 1–3 nb. This demonstrates that it is possible to measure {sup 12}C targets irradiated at lower energies for at least 10 times lower cross sections than before β–γ coincidences will lead us another factor of 10 lower, proving that this installations can be successfully used for nuclear astrophysics measurements.

  2. Onset of deconfinement in nucleus-nucleus collisions

    SciTech Connect

    Gazdzicki, M.; Gorenstein, M. I.; Seyboth, P.

    2012-05-15

    The energy dependence of hadron production in relativistic nucleus-nucleus collisions reveals anomalies-the kink, horn, and step. They were predicted as signals of the deconfinement phase transition and observed by the NA49 Collaboration in central PbPb collisions at the CERN SPS. This indicates the onset of the deconfinement in nucleus-nucleus collisions at about 30 A GeV.

  3. Study of 12C(γ, 2α)4He with NewSUBARU laser Compton scattered gamma-ray beam

    NASA Astrophysics Data System (ADS)

    Shima, Tatsushi; Nagai, Yasuki; Miyamoto, Shuji; Amano, Sou; Horikawa, Ken; Mochizuki, Takayasu; Utsunomiya, Hiroaki; Akimune, Hidetoshi

    2010-08-01

    The 16O(γ, 2α)4He reaction cross section was measured in the γ-ray energy range from 16 MeV up to 39 MeV using an active target method and a quasi-monochromatic γ-ray beam provided at the Laboratory of Advanced Science and Technology for Industry (LASTI) of the University of Hyogo. The cross section is found to be rather small in the energy region corresponding to the 2+ and 4+ excited states of the intermediate 8Be nucleus, while it becomes large above the energy corresponding to the 8Be 1- state, being in contrast to the latest result reported by Afanas'ev and Khodyachikh. The present result suggests the cross sections are dominated by the contributions of the 1- states in 12C which are excited with the E1 transition.

  4. Probing the possibility of a C-12/C-13 galactic abundance gradient

    NASA Technical Reports Server (NTRS)

    Hawkins, Isabel

    1990-01-01

    High S/N (equal to or greater than 500) observations of interstellar CH+ with the 3.0 m telescope were performed at Lick Observatory and with the 4.0 m telescope at CTIO, of the reddened, early-type stars HD 183143, HD 24432, and HD 157038 in an effort to probe the existence of a C-12/C-13 abundance gradient in our Galaxy. Previous very high quality optical observations of interstellar CH+ toward five stars within 1 kpc of the Sun have yielded a precise weighted mean C-12/C-13 isotope ratio of 43 plus or minus 4 (1 sigma) (Hawkins, Jura, and Meyer 1985; Hawkins and Jura 1987). The isotope ratios derived toward four lines of sight in the local ISM are uniform within 12 percent. The similarity among these carbon isotope ratios determined in diffuse clouds possessing different physical conditions precludes the possibility that the CH+ molecule is suffering from isotope selective effects in these regions. The precise C-12/C-13 derivable from high quality observations of (12)CH+ and (13)CH+ provide the unique opportunity to probe the homogeneity of the ISM in a large scale and the history of nucleosynthesis in our Galaxy. Since CH+ seems to be the most sensitive probe of C-12/C-13 in the diffuse ISM, observations toward more distant stars located up to 2.5 kpc from the Sun are the best way to study the possibility of a Galactic (C-12/C-13) abundance gradient. The researcher obtained 4232 angstrom data toward all three of the stars mentioned above, 3957 angstrom data toward HD 183143 and HD 157038, and 3745 angstrom data toward HD 157038. Because of the poorer quality of the HD 24432 spectrum, and its weaker CH+ absorption lines, the satellite (13)CH+ line was not detected, and thus only a lower limit on the C-12/C-13 ratio toward this star was obtained. The results obtained from careful reduction and analysis of the data toward these stars in the Northern and Southern Hemispheres are presented.

  5. An analysis of the 12C(p,d) reaction at eta'(958) meson production region by microscopic transport model (JAM)

    NASA Astrophysics Data System (ADS)

    Higashi, Yuko; Ikeno, Natumi; Nagahiro, Hideko; Hirenzaki, Satoru; Fujioka, Hiroyuki; Itahashi, Kenta; Tanaka, Yoshiki

    2014-09-01

    We study theoretically the 12C(p , d) reaction for the formation of the η' mesonic nucleus to optimize the experiments at GSI and FAIR, where the missing mass spectroscopy of the 12C(p , d) reaction is adopted to measure η' meson bound states in 11C. This method was proposed in Ref. and the peak structures are expected in the inclusive spectra of the deuteron in case that the discrete states exist. The semi-exclusive measurements are also considered at FAIR to reduce the background, where protons/charged pions are measured in coincidence with the deuteron. We present the theoretical distributions of the emitted charged particle in the (p , d) reaction. The charged particles produced by the η' absorption are expected to have uniform angular distribution with the specific energy of the absorption process, while those by the background distribute in the forward directions. Thus, we can reduce the background largely by the differences of the charged particle distributions from these processes. We use the microscopic transport model and we report the advantages of the semi-exclusive measurements.

  6. Astrophysical S(E) factor of the {sup 15}N(p,{alpha}){sup 12}C reaction at sub-Coulomb energies via the Trojan horse method

    SciTech Connect

    La Cognata, M.; Romano, S.; Spitaleri, C.; Cherubini, S.; Crucilla, V.; Gulino, M.; Lamia, L.; Pizzone, R. G.; Tumino, A.; Tribble, R.; Fu, Changbo; Goldberg, V. Z.; Mukhamedzhanov, A. M.; Schmidt, D.; Tabacaru, G.; Trache, L.; Irgaziev, B. F.

    2007-12-15

    The low-energy bare-nucleus cross section for {sup 15}N(p,{alpha}){sup 12}C is extracted by means of the Trojan horse method applied to the {sup 2}H({sup 15}N,{alpha}{sup 12}C)n reaction at E{sub beam}=60 MeV. For the first time we applied the modified half-off-energy-shell resonant R-matrix method that takes into account off-energy-shell effects and initial- and final-state interactions. In particular it has been shown that inclusion of Coulomb {sup 15}N-d scattering and off-shell effects do not affect the determination of the astrophysical factor. Also the simple plane-wave approximation used in previous analyses is justified. The results extracted via the Trojan horse method are compared to direct data in the same energy region and show very good agreement in the energy interval 70-312 keV. These results confirm the extrapolations of the S factor reported in literature.

  7. Antinucleon-nucleus interactions

    SciTech Connect

    Dover, C.B.

    1987-01-01

    Recent experimental and theoretical results on anti p-nucleus interactions are reviewed. We focus on determinations of the anti p optical potential from elastic scattering, the use of (anti p, anti p') inelastic scattering to reveal aspects of the spin-isospin dependence of N anti N amplitudes, and some puzzling features of (anti p, anti n) charge exchange reactions on nuclei. 47 refs., 7 figs.

  8. 12C-RBS investigation of scolecite crystals interacted with Cs- and Sr-aqueous solutions

    NASA Astrophysics Data System (ADS)

    Misaelides, P.; Godelitsas, A.; Noli, F.; Kossionidis, S.

    1998-04-01

    Crystals of the natural fibrous zeolite scolecite were exposed to cesium and strontium aqueous solutions at room temperature. The reacted mineral crystals were investigated by means of 12C-RBS using the 4.5 MV Tandem accelerator of the NRCPS "Demokritos"/GR. The 12C-RBS spectra indicated an inhomogeneous depth distribution of the sorbed elements on the scolecite and particular a remarkable metal accumulation in the near-surface layers of the material. This phenomenon is more intense in the case of strontium assigned to its bulkier hydrated cations and the structural characteristics of the zeolite. The results of this work can contribute to the understanding of problems related to the treatment of nuclear wastes using zeolitic materials and to their disposal in zeolite-containing geologic formations.

  9. Nucleosynthesis in the Hyades Open Cluster: Evidence for the Enhanced Depletion of 12C

    NASA Astrophysics Data System (ADS)

    Schuler, Simon C.; King, Jeremy R.; The, Lih-Sin

    2010-03-01

    We present the results of a light element abundance analysis of three solar-type main sequence (MS) dwarfs and three red giant branch (RGB) clump stars in the Hyades open cluster using high-resolution and high signal-to-noise spectroscopy. The CNO abundances of each group (MS or RGB) are in excellent star-to-star agreement and confirm that the giants have undergone first dredge-up mixing. The observed abundances are compared to predictions of a standard stellar model based on the Clemson-American University of Beirut (CAUB) stellar evolution code. The model reproduces the observed evolution of the N and O abundances, as well as the previously derived 12C/13C ratio, but it fails to predict the observed level of 12C depletion in the giants. More tellingly, the sum of the observed giant CNO abundances does not equal that of the dwarfs.

  10. Spectroscopy of {sup 16}O Using {alpha}+{sup 12}C Resonant Scattering in Inverse Kinematics

    SciTech Connect

    Ashwood, N. I.; Freer, M.; Bloxham, T. R.; Curtis, N.; Haigh, P. J.; Price, D. L.; Achouri, N. L.; Catford, W. N.; Harlin, C. W.; Patterson, N. P.; Thomas, J. S.; Soic, N.

    2009-08-26

    A measurement of the {alpha}({sup 12}C,{alpha}){sup 12}C reaction has been performed using resonant scattering with a gas target. Beam energies of 46, 51, 56 and 63 MeV were used to populate resonances in the excitation energy range of 11.6 to 22.9 MeV in {sup 16}O. The angular distributions of the elastic scattering were measured at zero degrees using an array of segmented silicon strip detectors with a minimum range of 0 deg. to 30 deg. in the centre of mass. The spins of 8 resonances between 14.1 and 18.5 MeV were obtained, confirming spin assignments made using elastic scattering in normal kinematics. An R-matrix analysis of the data was performed which indicates that the present understanding of {sup 16}O in this region is good, but not complete.

  11. Analysis of the 11B(d,n)12C Reaction

    NASA Astrophysics Data System (ADS)

    Ridling, Nathan; Prior, Richard; Spraker, Mark; Weller, Henry; Perdue, Brent

    2006-10-01

    Studies have been performed on the ^11B(d,n)^12C reaction to measure the absolute astrophysical S factor and its energy dependence, the reaction cross section, and tensor and vector analyzing powers T20, T21, T22, and iT11. The motivation behind this research project is not only its relevance to nuclear astrophysics, but also in the reaction dynamics of (d,n) reactions at very low energies. PSD (Pulse shape discrimination) was used along with PAW (Physics Analysis Workstation) in order to extract the neutrons from the gamma-rays. Using a neutron response function fitting routine in Root, we have determined the number of neutron counts leading to the ground and first excited states of ^12C. These yields were used to construct the angular distributions of the cross section and analyzing powers. Ultimately, we will extract the reaction specific transition matrix elements.

  12. Study of the12C excited states above the Hoyle State.

    NASA Astrophysics Data System (ADS)

    López-Saavedra, E.; Acosta, L.; Araujo, V.; Favela, F.; Huerta, A.; Aspiazu, J.; Murillo, G.; Policroniades, R.; Santa Rita, P.; Varela, A.; Chávez, E.

    2017-07-01

    In this work we study the low-lying excited states of12C, especially above the Hoyle state (0+, 7,654 MeV) through the use of the14N(d,α)12C reaction. The EN-Tandem at ININ delivered deuteron beams between 2.5 and 7.5 MeV. Typical beam intensities were 20-50 nA. Two different compounds were used to produce thin films: Si3N4 (150 nm) and of C5H5N5 (10 μm). Angular distributions of emitted α-particles were measured at each energy. The first results of the analysis are presented including quantum number assignments (energy, spin and parity) of the excited states populated.

  13. Structural studies of 4-aryloctahydro-pyrido[1,2- c]pyrimidine derivatives

    NASA Astrophysics Data System (ADS)

    Pisklak, Maciej; Herold, Franciszek; Anulewicz-Ostrowska, Romana; Wawer, Iwona

    2002-02-01

    13C cross-polarisation magic angle spinning NMR data have been reported for four derivatives of 4-aryl-octahydro-pyrido[1,2- c]pyrimidine-1,3-dione and the X-ray diffraction data for two (with 2'-Me and 2'-OMe). The crystal structures show the presence of centrosymmetric cyclic dimers with intermolecular C1O⋯H-N or C3O⋯H-N hydrogen bonds, the configuration at the chiral centres (C4 and C4 a) was determined as RR (SS). The twisting of aromatic ring at C4 with respect to the pyrido[1,2- c]pyrimidine skeleton is about 68-109°.

  14. Search for the Rare γ-Decay Mode in 12C

    NASA Astrophysics Data System (ADS)

    Tsumura, Miho; Kawabata, Takahiro

    In the normal stellar temperature, the triple α process proceeds via the 02 + state (Hoyle states) at Ex = 7.65 MeV in 12C. At high temperature T > 109 K, highly excited 3α resonance states such as the 31 - state at Ex = 9.64 MeV might play a part of the triple α reaction. However, their γ-decay probabilities have not been determined. We plan to study the 1H(12C, 12Cp) reaction through states higher than 02 + without measuring γ-rays. A test experiment using a solid hydrogen target and GAGG (Gd3Al2Ga3O12) scintillators was recently carried out at the cyclotron facility in RCNP, Osaka University. Its results are reported.

  15. Absolute Line Intensities in the 2nu3 Band of 16O12C32S

    PubMed

    Bermejo; Domenech; Santos; Bouanich; Blanquet

    1997-09-01

    The strengths of 100 lines in the 2nu3 band of 16O12C32S have been measured at high resolution in the spectral range 4069-4118 cm-1, using a tunable difference-frequency laser spectrometer. These intensities were obtained by fitting Voigt profiles to the measured shapes of the lines. The vibrational transition moment [(2.141 ± 0.020) x 10(-2) D] and the absolute intensity (16.19 ± 0.24 cm-2 atm-1 at 296 K) of the 2nu3 band of 16O12C32S are determined from these linestrength measurements. Copyright 1997 Academic Press. Copyright 1997Academic Press

  16. MM1+2C sporadic Creutzfeldt-Jakob disease presenting as rapidly progressive nonfluent aphasia.

    PubMed

    Allegri, Ricardo F; Bartoloni, Leonardo; Iturry, Mónica; Romero, Carlos; Begué, Christián; Sevlever, Gustavo; Taratuto, Ana Lía

    2014-01-01

    We report a 77-year-old man, presenting with progressive aphasia as an initial symptom, who developed severe dementia over the course of 20 months. Frontal cortex PrPSc western blot was type 2 and codon 129 was MM; brain neuropathology showed cortical vacuoles with perivacuolar PrP immunostaining characteristic of MM2C. Cerebellum showed focal coarse, patchy staining in different sections of the molecular layer, diffuse fine punctuate and coarse PrP immunopositive deposits in the granule cell layer, and focal synaptic immunostaining in the molecular layer, suggestive of MM1+2C by histotyping. This clinical presentation has not yet been described in an MM1+2C subtype by histotyping.

  17. Projectile and Target Fragmentation in the Interaction of 12C and 27Al

    SciTech Connect

    Foertsch, S.V.; Steyn, G.F.; Lawrie, J.J.; Smit, F.D.; Cerutti, F.; Colleoni, P.; Gadioli, E.; Mairani, A.; Connell, S.H.; Fearick, R.W.; Thovhogi, T.; Machner, H.; Goldenbaum, F.; Pysz, K.

    2005-05-24

    The emission of intermediate mass fragments (IMFs) produced in the inclusive 12C+27Al and 27Al+12C reactions at incident energies corresponding to a c.m. excitation energy of 107.5 MeV were studied at lab. angles of 12 deg. to 25 deg. Double differential cross sections of the IMF spectra are compared to model calculations, which include direct breakup of both the projectile and target, nucleon coalescence, as well as partial and complete fusion. This study indicates the importance of the complementary nature of a reaction together with its inverse process in fully understanding the driving reaction mechanisms in the interaction of two light-mass nuclei.

  18. The fast neutron component in treatment irradiations with 12C beam.

    PubMed

    Gunzert-Marx, Konstanze; Schardt, Dieter; Simon, Reinhard S

    2004-12-01

    Using 12C beams of 200 AMeV kinetic energy the production of secondary fragments from nuclear reactions in a thick water absorber (12.78 cm) was investigated. Fast neutrons and energetic charged particles (p-, d-, t-, a-particles) emitted in the forward hemisphere were identified by a BaF2/plastic-scintillation detector telescope. Neutron energy spectra were recorded at various angles using time-of-flight techniques. The neutron emission is forward peaked and the energy spectrum shows a broad maximum about half the energy per nucleon of the primary 12C ions. The total yield of fast neutrons emitted into the forward hemisphere integrated over the energy range of 25 to 500 MeV was found to be 0.43 +/- 0.1 per primary ion. The dose contribution of fast neutrons in patient treatments with carbon ions is estimated to be less than 1% of the total treatment dose.

  19. Isoscalar monopole and dipole excitations of cluster states and giant resonances in 12C

    NASA Astrophysics Data System (ADS)

    Kanada-En'yo, Yoshiko

    2016-05-01

    The isoscalar monopole (ISM) and dipole (ISD) excitations in 12C are investigated theoretically with the shifted antisymmetrized molecular dynamics (AMD) plus 3 α -cluster generator coordinate method (GCM). The small-amplitude vibration modes are described by coherent one-particle one-hole excitations expressed by a small shift of single-nucleon Gaussian wave functions within the AMD framework, whereas the large-amplitude cluster modes are incorporated by superposing 3 α -cluster wave functions in the GCM. The coupling of the excitations in the intrinsic frame with the rotation and parity transformation is taken into account microscopically by the angular-momentum and parity projections. The present a calculation that describes the ISM and ISD excitations over a wide energy region covering cluster modes in the low-energy region and the giant resonances in the high-energy region, although the quantitative description of the high-energy part is not satisfactory. The low-energy ISM and ISD strengths of the cluster modes are enhanced by the distance motion between α clusters, and they split into a couple of states because of the angular motion of α clusters. The low-energy ISM strengths exhaust 26% of the energy-weighted sum rule, which is consistent with the experimental data for the 12C(02+; 7.65 MeV) and 12C(03+; 10.3 MeV) measured by (e ,e') ,(α ,α') , and (6Li,6Li' ) scatterings. In the calculated low-energy ISD strengths, two 1- states (the 11- and 12- states) with the significant strengths are obtained over E =10 -15 MeV. The results indicate that the ISD excitations can be a good probe to experimentally search for new cluster states such as the 12C(12-) obtained in the present calculation.

  20. The structure of the Hoyle state and its 2+ partner state in 12C

    NASA Astrophysics Data System (ADS)

    Gai, Moshe

    2012-12-01

    We have measured the 12C(γ, 3α) reaction with an Optical Time Projection Chamber (O-TPC) detector operating with the CO2(80%) + N2(20%) gas mixture and gamma-ray beams from the HIγS facility of the TUNL at Duke. We measured complete angular distributions (between 9.1 - 10.7 MeV) from which we determine the cross section yield curve and E1 - E2 relative phases leading to an unambiguous identification of the second 2+ state in 12C at 10.03(11) MeV. The observed spectrum of 12C below 12 MeV including the 22+ state observed in this work resembles the rotation-vibration spectrum predicted for a triangular shape oblate spinning top in which the Hoyle state is the first vibrational breathing mode of the triangular three alpha-particle system. We also observed a hint of the 23+ state which is predicted by the U(7) model as a member of the 1- bending mode band, but the existence of this 23+ is yet to be confirmed. The predicted rotation-vibration spectrum of a triangular shape oblate spinning top (with a D3h symmetry) allows us to compare the moment of inertia of the predicted Hoyle rotational band to the ground state rotational band and in this way extract the (large) rms radius of the Hoyle state of 3.22(8) fm. We compare the deduced rms radius with recent ab-initio theories and cluster models as well as the radius extracted from 12C(p, p') data.

  1. Reaction mechanisms in 12C(γ,pp) near 200 MeV

    NASA Astrophysics Data System (ADS)

    Hackett, E. D.; McDonald, W. J.; Opper, A. K.; Quraan, M. A.; Rodning, N. L.; Rozon, F. M.; Feldman, G.; Kolb, N. R.; Pywell, R. E.; Skopik, D. M.; Tiller, D. E.; Vogt, J. M.; Korkmaz, E.; O'rielly, G. V.

    1996-03-01

    Inclusive 12C(γ,pp) cross sections have been measured with tagged photons in the range Eγ=187-227 MeV using the Saskatchewan-Alberta Large Acceptance Detector (SALAD). The large angular acceptance allowed the measurement of noncoplanar pp emission. The cross sections were compared to a Monte Carlo intranuclear cascade calculation. Agreement was reasonable for the shapes of the cross sections but the calculated total cross section was 3.9 times larger than the data.

  2. C-12/C-13 Ratio in Ethane on Titan and Implications for Methane's Replenishment

    NASA Technical Reports Server (NTRS)

    Jennings, Donald E.; Romani, Paul N.; Bjoraker, Gordon L.; Sada, Pedro V.; Nixon, Conor A.; Lunsford, Allen W.; Boyle, Robert J.; Hesman, Brigette E.; McCabe, George H.

    2009-01-01

    The C-12/C-13 abundance ratio in ethane in the atmosphere of Titan has been measured at 822 cm(sup -1) from high spectral resolution ground-based observations. The value 89(8), coincides with the telluric standard and also agrees with the ratio seen in the outer planets. It is almost identical to the result for ethane on Titan found by the composite infrared spectrometer (CIRS) on Cassini. The C-12/C-13 ratio for ethane is higher than the ratio measured in atmospheric methane by Cassini/Huygens GCMS, 82.3(l), representing an enrichment of C-12 in the ethane that might be explained by a kinetic isotope effect of approximately 1.1 in the formation of methyl radicals. If methane is being continuously resupplied to balance photochemical destruction, then we expect the isotopic composition in the ethane product to equilibrate at close to the same C-12/C-13 ratio as that in the supply. The telluric value of the ratio in ethane then implies that the methane reservoir is primordial.

  3. Decomposition of nuclear response functions for neutrino-induced reactions on 12C

    NASA Astrophysics Data System (ADS)

    Kim, Byungjick; Kim, K. S.; Kim, Hungchong; So, W. Y.; Cheoun, Myung-Ki

    2014-10-01

    We investigate the nuclear response functions in neutrino-induced reaction via a neutral current (NC) on 12C, which functions are comprised of Coulomb, longitudinal, magnetic and electric transitions. Those response functions in the NC reaction are closely related to those extracted from other types of NC reactions by electrons, protons and other light nuclei, such as A( e, e')A *, A( p, p')A *, A( d, d')A *, and A(6Li,6Li')A *. For example, the magnetic response function for the J π = 1+ state (M1) which is associated with the spin transfer reaction can be measured in inelastic scattering and may give us valuable information for the NC neutrino-induced reaction. Therefore, if we exploit response functions deduced by using other nuclear reactions, neutrino reactions could be estimated indirectly without relying on neutrino-induced reaction experiments. For the purpose, in this work, we decompose every response function in the neutrino reaction 12C( ν e , ν' e )12C*( J π = 1+) and address the role of each response function in the reaction.

  4. Effect of ^{12}C+α clustering on the E0 transition in ^{16}O

    NASA Astrophysics Data System (ADS)

    Matsuno, H.; Itagaki, N.; Ichikawa, T.; Yoshida, Y.; Kanada-En'yo, Y.

    2017-06-01

    We investigate cluster structures and E0 transitions of 0^+ states in ^{16}O. In particular, we discuss the mixing effect of 3α and α breaking components in the ^{12}C cluster on the E0 transitions. To this end, we perform a microscopic calculation including α cluster and cluster-breaking model spaces. By analyzing the obtained results, we confirm that the 0_2^+ and 0_3^+ states of ^{16}O are indeed the weak-coupling ^{12}C(0^+)+α and ^{12}C(2^+)+α cluster states, respectively. We find mainly two important mechanisms for reducing the E0 transition: (i) the difference in intrinsic spin configurations between the initial and final states caused by the cluster breaking and (ii) the mixing of planar 4α configurations in the excited states. We show that the E0 operator excites the initial (ground) state not to planar 4α configurations but predominantly to triangular pyramid 4α configurations. Thus, the mixture of the planar 4α configurations in the 0_2^+ state significantly reduces the E0 transition matrix elements to this state. We conclude that the E0 transitions tend to be enhanced by cluster states, but they are affected by various mechanisms originating in the detailed structures of the final states.

  5. Measurement of γ-rays from giant resonances of 12 C and 16 O

    NASA Astrophysics Data System (ADS)

    Ou, Iwa; RCNP E398 Collaboration

    2014-09-01

    Oxygen and carbon are the most common targets in neutrino experiments such as Super Kamiokande (H2O) and Daya-Bay (liquid scintillator). The γ-ray production from neutral current (NC) ν-16 O and ν-12 C (inelastic scattering) is applicable to the measurement of core-collapse supernova neutrinos. A core-collapse supernova emits all type of neutrino with mean energy of 10--20 MeV. In most neutrino detectors, the main signal is charged current event which can detect electron type neutrino only. While in NC event, mu and tau type neutrino can be detected. Therefore NC event is very important for the understanding of supernova mechanism. NC events will be identified by detecting the γ-rays emitted from giant resonances of 16O and 12C. But there is no experimental data for γ-ray production from these resonances. Our goal is to measure the γ-ray emission probability and energy spectrum from these resonances. We carried out an experiment to measure γ-rays from giant resonance of 16O and 12C using 400 MeV proton beam, magnetic spectrometer ``Grand Raiden'' and NaI(Tl) γ-detecter at Research Center for Nuclear Physics in Osaka University. In this talk, experimental setup and current analysis status will be presented.

  6. Separable representation of multichannel nucleon-nucleus optical potentials

    NASA Astrophysics Data System (ADS)

    Hlophe, L.; Elster, Ch.

    2017-05-01

    Background: One important ingredient for many applications of nuclear physics to astrophysics, nuclear energy, and stockpile stewardship is cross sections for reactions of neutrons with rare isotopes. Since direct measurements are often not feasible, indirect methods, e.g., (d ,p ) reactions, should be used. Those (d ,p ) reactions may be viewed as three-body reactions and described with Faddeev techniques. Purpose: Faddeev equations in momentum space have a long tradition of utilizing separable interactions in order to arrive at sets of coupled integral equations in one variable. Optical potentials representing the effective interactions in the neutron (proton) nucleus subsystem are usually non-Hermitian as well as energy dependent. Including excitations of the nucleus in the calculation requires a multichannel optical potential. The purpose of this paper is to introduce a separable, energy-dependent multichannel representation of complex, energy-dependent optical potentials that contain excitations of the nucleus and that fulfill reciprocity exactly. Methods: Momentum space Lippmann-Schwinger integral equations are solved with standard techniques to obtain the form factors for the separable representation. Results: Starting from energy-dependent multichannel optical potentials for neutron and proton scattering from 12C, separable representations based on a generalization of the Ernst-Shakin-Thaler (EST) scheme are constructed which fulfill reciprocity exactly. Applications to n +12C and p +12C scattering are investigated for energies from 0 to 50 MeV. Conclusions: We find that the energy-dependent separable representation of complex, energy-dependent phenomenological multichannel optical potentials describes scattering data with the same quality as the original potential.

  7. Leukocyte nucleus segmentation and nucleus lobe counting.

    PubMed

    Chan, Yung-Kuan; Tsai, Meng-Hsiun; Huang, Der-Chen; Zheng, Zong-Han; Hung, Kun-Ding

    2010-11-12

    Leukocytes play an important role in the human immune system. The family of leukocytes is comprised of lymphocytes, monocytes, eosinophils, basophils, and neutrophils. Any infection or acute stress may increase or decrease the number of leukocytes. An increased percentage of neutrophils may be caused by an acute infection, while an increased percentage of lymphocytes can be caused by a chronic bacterial infection. It is important to realize an abnormal variation in the leukocytes. The five types of leukocytes can be distinguished by their cytoplasmic granules, staining properties of the granules, size of cell, the proportion of the nuclear to the cytoplasmic material, and the type of nucleolar lobes. The number of lobes increased when leukemia, chronic nephritis, liver disease, cancer, sepsis, and vitamin B12 or folate deficiency occurred. Clinical neutrophil hypersegmentation has been widely used as an indicator of B12 or folate deficiency.Biomedical technologists can currently recognize abnormal leukocytes using human eyes. However, the quality and efficiency of diagnosis may be compromised due to the limitations of the biomedical technologists' eyesight, strength, and medical knowledge. Therefore, the development of an automatic leukocyte recognition system is feasible and necessary. It is essential to extract the leukocyte region from a blood smear image in order to develop an automatic leukocyte recognition system. The number of lobes increased when leukemia, chronic nephritis, liver disease, cancer, sepsis, and vitamin B12 or folate deficiency occurred. Clinical neutrophil hypersegmentation has been widely used as an indicator of B12 or folate deficiency. The purpose of this paper is to contribute an automatic leukocyte nuclei image segmentation method for such recognition technology. The other goal of this paper is to develop the method of counting the number of lobes in a cell nucleus. The experimental results demonstrated impressive segmentation accuracy

  8. Nucleus from string theory

    NASA Astrophysics Data System (ADS)

    Hashimoto, Koji; Morita, Takeshi

    2011-08-01

    In generic holographic QCD, we find that baryons are bound to form a nucleus, and that its radius obeys the empirically-known mass-number (A) dependence r∝A1/3 for large A. Our result is robust, since we use only a generic property of D-brane actions in string theory. We also show that nucleons are bound completely in a finite volume. Furthermore, employing a concrete holographic model (derived by Hashimoto, Iizuka, and Yi, describing a multibaryon system in the Sakai-Sugimoto model), the nuclear radius is evaluated as O(1)×A1/3[fm], which is consistent with experiments.

  9. Reality of comet nucleus.

    NASA Technical Reports Server (NTRS)

    Lyttleton, R. A.

    1972-01-01

    The prime problem of a comet mission must be to settle whether the cometary nucleus has an actual tangible material existence, or whether it arises from some optical effect present only at times within comets. The absence of any large particles in a comet seems to be demonstrated by certain meteor showers. A feature that would seem to indicate that a comet consists primarily of a swarm of particles is that the coma in general contracts as the comet approaches the sun, roughly in proportion within the distance, and then expands again as it recedes.

  10. Neutrino-nucleus interactions

    SciTech Connect

    Gallagher, H.; Garvey, G.; Zeller, G.P.; /Fermilab

    2011-01-01

    The study of neutrino oscillations has necessitated a new generation of neutrino experiments that are exploring neutrino-nuclear scattering processes. We focus in particular on charged-current quasi-elastic scattering, a particularly important channel that has been extensively investigated both in the bubble-chamber era and by current experiments. Recent results have led to theoretical reexamination of this process. We review the standard picture of quasi-elastic scattering as developed in electron scattering, review and discuss experimental results, and discuss additional nuclear effects such as exchange currents and short-range correlations that may play a significant role in neutrino-nucleus scattering.

  11. Coincident emission of neutrons and charged particles after π- absorption in 6Li, 7Li, 12C, 59Co and 197Au

    NASA Astrophysics Data System (ADS)

    Heusi, P.; Isaak, H. P.; Pruys, H. S.; Engfer, R.; Hermes, E. A.; Kozlowski, T.; Sennhauser, U.; Walter, H. K.

    1983-10-01

    Energy spectra d 3W/d E1 d E2 d cos ϑ of neutron-neutron and neutron-charged particle pairs (nn, np, nd, nt) emitted after the absorption of stopped negative pions in 6Li, 7Li, 12C, 59Co and 197Au have been measured for opening angles between 50° and 180°. Particle pairs emitted from light nuclei without energy loss due to final-state interactions were identified by the energy balance. Pion absorption on two nucleons (quasi-deuteron mechanism) was found to be the main process. The yields of nucleon pairs from quasi-free absorption on a quasi-deuteron are 0.52 ± 0.09 per π-stop, 0.57 ± 0.10 per π-stop and 0.19 ± 0.04 per π-stop for 6Li, 7Li and 12C, respectively. The ratio R of np to pp pairs that absorb the pion was determined for quasi-free absorption on p-shell nucleons of 12C: R(p-shell) = 6.3 ± 1.4. For pion absorption on s-shell nucleons of lithium lower limits R(s-shell) > 4.4 for 6Li and R(s-shell) > 7.8 for 7Li were determined. These values are larger than the statistical ratios Rstat = 2 N/( Z - 1) of np to pp pairs in the nucleus. Lower limits for the probability for pion absorption on heavier clusters ( 3He, α) are W(hc) > 0.16 per π-stop for 6Li, W(hc) > 0.11 per π-stop for 7Li and W( α) > 0.01 per π-stop for 12C. The shape of the energy spectra of pairs emitted directly after quasi-free absorption on 2 or 4 nucleons could be explained by a simple model for the momentum distribution of the absorbing nucleons. The results are in agreement with the parameters of the momentum distributions known from other reactions. Energy spectra and opening-angle distributions were compared with the intranuclear cascade calculations of Chiang, Hüfner and Hachenberg. For 59Co and 197Au the spectra are strongly influenced by the final-state interactions; lower limits of R > 1.8 for 59Co and R > 2.5 for 197Au were determined.

  12. Higgs-boson production in nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Norbury, J. W.; Townsend, L. W. (Principal Investigator)

    1990-01-01

    Cross-section calculations are presented for the production of intermediate-mass Higgs bosons produced in ultrarelativistic nucleus-nucleus collisions via two-photon fusion. The calculations are performed in position space using Baur's method for folding together the Weizsacker-Williams virtual-photon spectra of the two colliding nuclei. It is found that two-photon fusion in nucleus-nucleus collisions is a plausible way of finding intermediate-mass Higgs bosons at the Superconducting Super Collider or the CERN Large Hadron Collider.

  13. Higgs-Boson Production in Nucleus-Nucleus Collisions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.

    1992-01-01

    Cross section calculations are presented for the production of intermediate-mass Higgs bosons produced in ultrarelativistic nucleus-nucleus collisions via two photon fusion. The calculations are performed in position space using Baur's method for folding together the Weizsacker-Williams virtual-photon spectra of the two colliding nuclei. It is found that two photon fusion in nucleus-nucleus collisions is a plausible way of finding intermediate-mass Higgs bosons at the Superconducting Super Collider or the CERN Large Hadron Collider.

  14. Higgs-Boson Production in Nucleus-Nucleus Collisions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.

    1992-01-01

    Cross section calculations are presented for the production of intermediate-mass Higgs bosons produced in ultrarelativistic nucleus-nucleus collisions via two photon fusion. The calculations are performed in position space using Baur's method for folding together the Weizsacker-Williams virtual-photon spectra of the two colliding nuclei. It is found that two photon fusion in nucleus-nucleus collisions is a plausible way of finding intermediate-mass Higgs bosons at the Superconducting Super Collider or the CERN Large Hadron Collider.

  15. Higgs-boson production in nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Norbury, J. W.; Townsend, L. W. (Principal Investigator)

    1990-01-01

    Cross-section calculations are presented for the production of intermediate-mass Higgs bosons produced in ultrarelativistic nucleus-nucleus collisions via two-photon fusion. The calculations are performed in position space using Baur's method for folding together the Weizsacker-Williams virtual-photon spectra of the two colliding nuclei. It is found that two-photon fusion in nucleus-nucleus collisions is a plausible way of finding intermediate-mass Higgs bosons at the Superconducting Super Collider or the CERN Large Hadron Collider.

  16. Experimental Energy Levels and Partition Function of the 12C2 Molecule

    NASA Astrophysics Data System (ADS)

    Furtenbacher, Tibor; Szabó, István; Császár, Attila G.; Bernath, Peter F.; Yurchenko, Sergei N.; Tennyson, Jonathan

    2016-06-01

    The carbon dimer, the 12C2 molecule, is ubiquitous in astronomical environments. Experimental-quality rovibronic energy levels are reported for 12C2, based on rovibronic transitions measured for and among its singlet, triplet, and quintet electronic states, reported in 42 publications. The determination utilizes the Measured Active Rotational-Vibrational Energy Levels (MARVEL) technique. The 23,343 transitions measured experimentally and validated within this study determine 5699 rovibronic energy levels, 1325, 4309, and 65 levels for the singlet, triplet, and quintet states investigated, respectively. The MARVEL analysis provides rovibronic energies for six singlet, six triplet, and two quintet electronic states. For example, the lowest measurable energy level of the {{a}}{}3{{{\\Pi }}}{{u}} state, corresponding to the J = 2 total angular momentum quantum number and the F 1 spin-multiplet component, is 603.817(5) cm-1. This well-determined energy difference should facilitate observations of singlet-triplet intercombination lines, which are thought to occur in the interstellar medium and comets. The large number of highly accurate and clearly labeled transitions that can be derived by combining MARVEL energy levels with computed temperature-dependent intensities should help a number of astrophysical observations as well as corresponding laboratory measurements. The experimental rovibronic energy levels, augmented, where needed, with ab initio variational ones based on empirically adjusted and spin-orbit coupled potential energy curves obtained using the Duo code, are used to obtain a highly accurate partition function, and related thermodynamic data, for 12C2 up to 4000 K.

  17. Analysis of α-12C elastic scattering at intermediate energies by the S-matrix model

    NASA Astrophysics Data System (ADS)

    Berezhnoy, Yu. A.; Onyshchenko, G. M.; Pilipenko, V. V.

    The results of calculations of differential cross-sections for α-12C elastic scattering by the S-matrix model are presented for 10 energy values in the energy range 65MeV ≤ Eα ≤ 386MeV in a wide range of scattering angles. The behavior of various scattering characteristics as functions of the projectile energy is analyzed. It is shown that the chosen parametrization of S-matrix allows describing correctly the Fraunhofer oscillations of the cross-sections in the region of small scattering angles and the rainbow scattering pattern in the region of sufficiently large angles.

  18. New Measurement of the Direct 3 α Decay from the 12C Hoyle State

    NASA Astrophysics Data System (ADS)

    Smith, R.; Kokalova, Tz.; Wheldon, C.; Bishop, J. E.; Freer, M.; Curtis, N.; Parker, D. J.

    2017-09-01

    Excited states in certain atomic nuclei possess an unusual structure, where the dominant degrees of freedom are those of α clusters rather than individual nucleons. It has been proposed that the diffuse 3 α system of the 12C Hoyle state may behave like a Bose-Einstein condensate, where the α clusters maintain their bosonic identities. By measuring the decay of the Hoyle state into three α particles, we obtained an upper limit for the rare direct 3 α decay branch of 0.047%. This value is now at a level comparable with theoretical predictions and could be a sensitive probe of the structure of this state.

  19. Clarification of the Three-Body Decay of 12C (12.71MeV)

    NASA Astrophysics Data System (ADS)

    Fynbo, H. O.; Prezado, Y.; Bergmann, U. C.; Borge, M. J.; Dendooven, P.; Huang, W. X.; Huikari, J.; Jeppesen, H.; Jones, P.; Jonson, B.; Meister, M.; Nyman, G.; Riisager, K.; Tengblad, O.; Vogelius, I. S.; Wang, Y.; Weissman, L.; Rolander, K. Wilhelmsen; Äystö, J.

    2003-08-01

    Using β decays of a clean source of 12N produced at the IGISOL facility, we have measured the breakup of the 12C (12.71MeV) state into three α particles with a segmented particle detector setup. The high quality of the data permits solving the question of the breakup mechanism of the 12.71MeV state, a longstanding problem in few-body nuclear physics. Among existing models, a modified sequential model fits the data best, but systematic deviations indicate that a three-body description is needed.

  20. New information on 12C states from the decays of 12N and 12B

    NASA Astrophysics Data System (ADS)

    Fynbo, H. O. U.; Bergmann, U. C.; Borge, M. J. G.; Dendooven, P.; Diget, C. Aa.; Huang, W.; Huikari, J.; Jeppesen, H.; Jonson, B.; Jones, P.; Meister, M.; Nyman, G.; Prezado, Y.; Riisager, K.; Storgaard Vogelius, I.; Tengblad, O.; Wang, Y.; Weissman, L.; Wilhelmsen Rolander, K.; Äystö, J.

    2003-05-01

    The properties of states in 12C above the 3α-threshold are of high current interest for nuclear astrophysics and for the nuclear many-body problem in general. We have initiated a series of experiments aimed at elucidating this region by using the β-decays of 12N and 12B. By applying the ISOL method for producing these radioactive isotopes, in combination with modern segmented charged particle detectors, our approach has significant advantages over previous studies of this region.

  1. 12C+16O sub-barrier radiative capture cross-section measurements

    NASA Astrophysics Data System (ADS)

    Goasduff, A.; Courtin, S.; Haas, F.; Lebhertz, D.; Jenkins, D. G.; Beck, C.; Fallis, J.; Ruiz, C.; Hutcheon, D. A.; Amandruz, P.-A.; Davis, C.; Hager, U.; Ottewell, D.; Ruprecht, G.

    2011-10-01

    We have performed a heavy ion radiative capture reaction between two light heavy ions, 12C and 16O, leading to 28Si. The present experiment has been performed below Coulomb barrier energies in order to reduce the phase space and to try to shed light on structural effects. Obtained γ-spectra display a previously unobserved strong feeding of intermediate states around 11 MeV at these energies. This new decay branch is not fully reproduced by statistical nor semi-statistical decay scenarii and may imply structural effects. Radiative capture cross-sections are extracted from the data.

  2. Reaction mechanisms in {sup 12}C({gamma},{ital pp}) near 200 MeV

    SciTech Connect

    Hackett, E.D.; McDonald, W.J.; Opper, A.K.; Quraan, M.A.; Rodning, N.L.; Rozon, F.M.; Feldman, G.; Kolb, N.R.; Pywell, R.E.; Skopik, D.M.; Tiller, D.E.; Vogt, J.M.; Korkmaz, E.; ORielly, G.V.

    1996-03-01

    Inclusive {sup 12}C({gamma},{ital pp}) cross sections have been measured with tagged photons in the range {ital E}{sub {gamma}}=187{endash}227 MeV using the Saskatchewan-Alberta Large Acceptance Detector (SALAD). The large angular acceptance allowed the measurement of noncoplanar {ital pp} emission. The cross sections were compared to a Monte Carlo intranuclear cascade calculation. Agreement was reasonable for the shapes of the cross sections but the calculated total cross section was 3.9 times larger than the data. {copyright} {ital 1996 The American Physical Society.}

  3. C12/C13-ratio determination in nanodiamonds by atom-probe tomography.

    PubMed

    Lewis, Josiah B; Isheim, Dieter; Floss, Christine; Seidman, David N

    2015-12-01

    The astrophysical origins of ∼ 3 nm-diameter meteoritic nanodiamonds can be inferred from the ratio of C12/C13. It is essential to achieve high spatial and mass resolving power and minimize all sources of signal loss in order to obtain statistically significant measurements. We conducted atom-probe tomography on meteoritic nanodiamonds embedded between layers of Pt. We describe sample preparation, atom-probe tomography analysis, 3D reconstruction, and bias correction. We present new data from meteoritic nanodiamonds and terrestrial standards and discuss methods to correct isotopic measurements made with the atom-probe tomograph. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Observation of a Quasideuteron Component in the Reaction 12C(π+, 2p)

    NASA Astrophysics Data System (ADS)

    Altman, A.; Piasetzky, E.; Lichtenstadt, J.; Yavin, A. I.; Ashery, D.; Powers, R. J.; Bertl, W.; Felawka, L.; Walter, H. K.; Winter, R. G.; Pluym, J. V. D.

    1983-04-01

    The reaction 12C(π+, 2p) was studied at 165 and 245 MeV over a broad kinematic range by coincidence measurement of the outgoing protons. The p-p angular correlations and proton energy spectra allow an identification of the "quasideuteron" component of the reaction. The angular distribution of this component has a shape similar to that of the π+d-->pp reaction. It is found that one-step quasideuteron absorption accounts for at most 25% of the total absorption cross section.

  5. Neutral weak-current two-body contributions in inclusive scattering from {sup 12}C

    SciTech Connect

    Lovato, Alessandro; Gandolfi, Stefano; Carlson, Joseph; Pieper, S. C.; Schiavilla, Rocco

    2014-05-01

    An {\\it ab initio} calculation of the sum rules of the neutral weak response functions in $^{12}$C is reported, based on a realistic Hamiltonian, including two- and three-nucleon potentials, and on realistic currents, consisting of one- and two-body terms. We find that the sum rules of the response functions associated with the longitudinal and transverse components of the (space-like) neutral current are largest and that a significant portion ($\\simeq 30$\\%) of the calculated strength is due to two-body terms. This fact may have implications for the MiniBooNE and other neutrino quasi-elastic scattering data on nuclei.

  6. Survey of A asymmetries in semi-exclusive electron scattering on 4He and 12C

    NASA Astrophysics Data System (ADS)

    Protopopescu, D.; Hersman, F. W.; Holtrop, M.; Adams, G.; Ambrozewicz, P.; Anciant, E.; Anghinolfi, M.; Asavapibhop, B.; Asryan, G.; Audit, G.; Auger, T.; Avakian, H.; Bagdasaryan, H.; Ball, J. P.; Barrow, S.; Battaglieri, M.; Beard, K.; Bektasoglu, M.; Bellis, M.; Benmouna, N.; Berman, B. L.; Bertozzi, W.; Bianchi, N.; Biselli, A. S.; Boiarinov, S.; Bonner, B. E.; Bouchigny, S.; Bradford, R.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Butuceanu, C.; Calarco, J. R.; Carman, D. S.; Carnahan, B.; Cetina, C.; Chen, S.; Cole, P. L.; Coleman, A.; Cords, D.; Corvisiero, P.; Crabb, D.; Crannell, H.; Cummings, J. P.; Debruyne, D.; De Sanctis, E.; DeVita, R.; Degtyarenko, P. V.; Dennis, L.; Dharmawardane, K. V.; Dhuga, K. S.; Djalali, C.; Dodge, G. E.; Doughty, D.; Dragovitsch, P.; Dugger, M.; Dytman, S.; Dzyubak, O. P.; Egiyan, H.; Egiyan, K. S.; Elouadrhiri, L.; Empl, A.; Eugenio, P.; Fatemi, R.; Feuerbach, R. J.; Forest, T. A.; Funsten, H.; Gavalian, G.; Gilad, S.; Gilfoyle, G. P.; Giovanetti, K. L.; Girard, P.; Gordon, C. I. O.; 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.; Hicks, K.; Hleiqawi, I.; Hu, J.; Hyde-Wright, C. E.; Ingram, W.; Ireland, D.; Ito, M. M.; Jenkins, D.; Joo, K.; Juengst, H. G.; Kelley, J. H.; 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.; Kuhn, S. E.; Kuhn, J.; Lachniet, J.; Laget, J. M.; Langheinrich, J.; Lawrence, D.; Lee, T.; Li, Ji; Livingston, K.; Lukashin, K.; Manak, J. J.; Marchand, C.; McAleer, S.; McLauchlan, S. T.; McNabb, J. W. C.; Mecking, B. A.; Melone, J. J.; Mestayer, M. D.; Meyer, C. A.; Mikhailov, K.; Minehart, R.; Mirazita, M.; Miskimen, R.; Morand, L.; Morrow, S. A.; Muccifora, V.; Mueller, J.; Mutchler, G. S.; Napolitano, J.; Nasseripour, R.; Nelson, S. O.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Niczyporuk, B. B.; Niyazov, R. A.; Nozar, M.; O'Rielly, G. V.; Osipenko, M.; Ostrovidov, A.; Park, K.; Pasyuk, E.; Peterson, G.; Philips, S. A.; Pivnyuk, N.; Pocanic, D.; Pogorelko, O.; Polli, E.; Pozdniakov, S.; Preedom, B. M.; Price, J. W.; Prok, Y.; Qin, L. M.; Raue, B. A.; Riccardi, G.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Ronchetti, F.; Rosner, G.; Rossi, P.; Rowntree, D.; Rubin, P. D.; Ryckebusch, J.; Sabatié, F.; Sabourov, K.; Salgado, C.; Santoro, J. P.; Sapunenko, V.; Schumacher, R. A.; Serov, V. S.; 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.; Stokes, B. E.; Stoler, P.; Strauch, S.; Taiuti, M.; Taylor, S.; Tedeschi, D. J.; Thoma, U.; Thompson, R.; Tkabladze, A.; Todor, L.; Tur, C.; Ungaro, M.; Vineyard, M. F.; Vlassov, A. V.; Wang, K.; Weinstein, L. B.; Weller, H.; Weygand, D. P.; Whisnant, C. S.; Williams, M.; Wolin, E.; Wood, M. H.; Yegneswaran, A.; Yun, J.; Zana, L.; Zhang, B.; CLAS Collaboration

    2005-02-01

    Single spin azimuthal asymmetries A were measured at Jefferson Lab using 2.2 and 4.4 GeV longitudinally polarised electrons incident on 4He and 12C targets in the CLAS detector. A is related to the imaginary part of the longitudinal-transverse interference and in quasifree nucleon knockout it provides an unambiguous signature for final state interactions (FSI). Experimental values of A were found to be below 5%, typically |A|⩽3% for data with good statistical precision. Optical model in eikonal approximation (OMEA) and relativistic multiple-scattering Glauber approximation (RMSGA) calculations are shown to be consistent with the measured asymmetries.

  7. Networking the nucleus

    PubMed Central

    Rajapakse, Indika; Scalzo, David; Tapscott, Stephen J; Kosak, Steven T; Groudine, Mark

    2010-01-01

    The nuclei of differentiating cells exhibit several fundamental principles of self-organization. They are composed of many dynamical units connected physically and functionally to each other—a complex network—and the different parts of the system are mutually adapted and produce a characteristic end state. A unique cell-specific signature emerges over time from complex interactions among constituent elements that delineate coordinate gene expression and chromosome topology. Each element itself consists of many interacting components, all dynamical in nature. Self-organizing systems can be simplified while retaining complex information using approaches that examine the relationship between elements, such as spatial relationships and transcriptional information. These relationships can be represented using well-defined networks. We hypothesize that during the process of differentiation, networks within the cell nucleus rewire according to simple rules, from which a higher level of order emerges. Studying the interaction within and among networks provides a useful framework for investigating the complex organization and dynamic function of the nucleus. PMID:20664641

  8. Measurement of the 3-α decay from the Hoyle and the broad 10 MeV states in12C

    NASA Astrophysics Data System (ADS)

    Itoh, M.; Ando, S.; Aoki, T.; Arikawa, H.; Ezure, S.; Harada, K.; Hayamizu, T.; Inoue, T.; Ishikawa, T.; Kato, K.; Kawamura, H.; Sakemi, Y.; Uchiyama, A.

    2017-06-01

    The measurements of the 3-α decay from the Hoyle and the broad 10 MeV state in12C have been performed using an inverse kinematic method of the12C(12C,3α)12C reaction at E12C = 110 MeV. In the measurement of the Hoyle state, the upper limit of the direct decay was improved to be 0.2 %. This was inconsistent with the recent reported nonzero value of 0.9 %, but an order larger than the direct decay branch predicted in the 3-α model. The branching ratios of the sequtial decay for the broad 10 MeV state were also obtained. They were higher than those obtained in the RCNP experiment, since they contained the contributions of higer multipole components. Their contributions will be estimated.

  9. Further improvement of the upper limit on the direct 3α decay from the Hoyle state in 12C.

    PubMed

    Itoh, M; Ando, S; Aoki, T; Arikawa, H; Ezure, S; Harada, K; Hayamizu, T; Inoue, T; Ishikawa, T; Kato, K; Kawamura, H; Sakemi, Y; Uchiyama, A

    2014-09-05

    The direct 3α decay branch from the 02+ state at Ex=7.65  MeV in 12C, which is known as the Hoyle state, is considered to affect the triple-α reaction rate strongly and to give crucial information on its structure. We have performed a high-precision measurement of the 3α decay from this state using the 12C(12C,3α)12C reaction at E12C=110  MeV. The branching ratio of the direct 3α decay was under the detection limit in the present experiment. By comparing with Monte Carlo simulations for three decay mechanisms as the sequential decay through the ground state of ^{8}Be, the direct decay with equal energies of three α particles, and the direct decay to the phase space uniformly, we have obtained the upper limit of 0.2% on the direct 3α decay.

  10. 3D silicon microdosimetry and RBE study using 12C ion of different energies

    NASA Astrophysics Data System (ADS)

    Tran, L. T.; Chartier, L.; Bolst, D.; Prokopovich, D.; Guatelli, S.; Petasecca, M.; Lerch, M.; Reinhard, M.; Perevertaylo, V.; Jackson, M.; Matsufuji, N.; Hinde, D.; Dasgupta, M.; Stuchbery, A.; Rosenfeld, A. B.

    2017-02-01

    This paper presents a new version of the 3D mesa “bridge” microdosimeter comprised of an array of 4248 silicon cells fabricated on 10 µm thick silicon-on-insulator substrate. This microdosimeter has been designed to overcome limitations existing in previous generation silicon microdosimeters and it provides well-defined sensitive volumes and high spatial resolution. The charge collection characteristics of the new 3D mesa microdosimeter were investigated using the ANSTO heavy ion microprobe, utilizing 5.5 MeV He2+ ions. Measurement of microdosimetric quantities allowed for the determination of the Relative Biological Effectiveness of 290 MeV/u and 350 MeV/u 12C heavy ion therapy beams at the Heavy Ion Medical Accelerator in Chiba (HIMAC), Japan. The microdosimetric RBE obtained showed good agreement with the tissue-equivalent proportional counter. Utilizing the high spatial resolution of the SOI microdosimeter, the LET spectra for 70 MeV 12C+6 ions, like those present at the distal edge of 290 and 350 MeV/u beams, were obtained as the ions passed through thin layers of polyethylene film. This microdosimeter can provide useful information about the lineal energy transfer (LET) spectra downstream of the protective layers used for shielding of electronic devices for single event upset prediction.

  11. Ferroelectric response in an achiral non-symmetric bent liquid crystal:C12C10

    NASA Astrophysics Data System (ADS)

    Subrahmanyam, S. V.; Chalapathi, P. V.; Mahabaleshwara, S.; Srinivasulu, M.; George, A. K.; Potukuchi, D. M.

    2014-10-01

    An achiral Non-Symmetric Bent Liquid Crystal (BLC) with a Oxadiazole based hetero cyclic central moiety, abbreviated as C12C10 viz., dodecyl[4-{5-(4‧-decyloxy)biphenyl-4-yl}-1,2,4-oxadiazol-3-yl]benzoate, exhibiting FerroElectric (FE) response is reported. Product is confirmed by 1H NMR, 13C NMR and elemental analysis. Characterization of BLC phases is carried out by Polarized Optical Microscopy (POM), Differential Scanning Calorimetry (DSC), Spontaneous Polarization (PS) and Low Frequency (10 Hz-10 MHz) Dielectric Relaxation studies. C12C10 exhibits enantiotropic LC SmA, FE B2, SmG, SmE phase variance. I-SmA, B2-SmG and SmG-SmE transitions are of first order nature. FE B2 phases exhibits a moderate PS of 80 nC cm-2. B2 phase exhibits Curie-Weiss behavior to confirm FE nature. Off-centered low frequency (KHz) dispersion infers a scissor mode and a high frequency (MHz) mode to reflect the distinct time-scale response. Dielectric Dispersion is relatively susceptible in lower frequency KHz region. Arrhenius shift in Relaxation Frequency (fR) infers higher activation energy (Ea) in non-FE phases for HF mode and lower value for KHz mode. Trends of fR, dielectric strength Δε, α-parameter and Ea are discussed in view of the data reported in other LC compounds.

  12. Theoretical investigation of stabilities and optical properties of Si12C12 clusters

    NASA Astrophysics Data System (ADS)

    Duan, Xiaofeng F.; Burggraf, Larry W.

    2015-01-01

    By sorting through hundreds of globally stable Si12C12 isomers using a potential surface search and using simulated annealing, we have identified low-energy structures. Unlike isomers knit together by Si-C bonds, the lowest energy isomers have segregated carbon and silicon regions that maximize stronger C-C bonding. Positing that charge separation between the carbon and silicon regions would produce interesting optical absorption in these cluster molecules, we used time-dependent density functional theory to compare the calculated optical properties of four isomers representing structural classes having different types of silicon and carbon segregation regions. Absorptions involving charge transfer between segregated carbon and silicon regions produce lower excitation energies than do structures having alternating Si-C bonding for which frontier orbital charge transfer is exclusively from separated carbon atoms to silicon atoms. The most stable Si12C12 isomer at temperatures below 1100 K is unique as regards its high symmetry and large optical oscillator strength in the visible blue. Its high-energy and low-energy visible transitions (1.15 eV and 2.56 eV) are nearly pure one-electron silicon-to-carbon transitions, while an intermediate energy transition (1.28 eV) is a nearly pure carbon-to-silicon one-electron charge transfer.

  13. Theoretical investigation of stabilities and optical properties of Si12C12 clusters.

    PubMed

    Duan, Xiaofeng F; Burggraf, Larry W

    2015-01-21

    By sorting through hundreds of globally stable Si12C12 isomers using a potential surface search and using simulated annealing, we have identified low-energy structures. Unlike isomers knit together by Si-C bonds, the lowest energy isomers have segregated carbon and silicon regions that maximize stronger C-C bonding. Positing that charge separation between the carbon and silicon regions would produce interesting optical absorption in these cluster molecules, we used time-dependent density functional theory to compare the calculated optical properties of four isomers representing structural classes having different types of silicon and carbon segregation regions. Absorptions involving charge transfer between segregated carbon and silicon regions produce lower excitation energies than do structures having alternating Si-C bonding for which frontier orbital charge transfer is exclusively from separated carbon atoms to silicon atoms. The most stable Si12C12 isomer at temperatures below 1100 K is unique as regards its high symmetry and large optical oscillator strength in the visible blue. Its high-energy and low-energy visible transitions (1.15 eV and 2.56 eV) are nearly pure one-electron silicon-to-carbon transitions, while an intermediate energy transition (1.28 eV) is a nearly pure carbon-to-silicon one-electron charge transfer.

  14. Vibrational dynamics of a non-degenerate ultrafast rotor: The (C12,C13)-oxalate ion

    PubMed Central

    Kuroda, Daniel G.; Abdo, Mohannad; Chuntonov, Lev; Smith, Amos B.; Hochstrasser, Robin M.

    2013-01-01

    Molecular ions undergoing ultrafast conformational changes on the same time scale of water motions are of significant importance in condensed phase dynamics. However, the characterization of systems with fast molecular motions has proven to be both experimentally and theoretically challenging. Here, we report the vibrational dynamics of the non-degenerate (C12,C13)-oxalate anion, an ultrafast rotor, in aqueous solution. The infrared absorption spectrum of the (C12,C13)-oxalate ion in solution reveals two vibrational transitions separated by approximately 40 cm−1 in the 1500–1600 cm−1 region. These two transitions are assigned to vibrational modes mainly localized in each of the carboxylate asymmetric stretch of the ion. Two-dimensional infrared spectra reveal the presence and growth of cross-peaks between these two transitions which are indicative of coupling and population transfer, respectively. A characteristic time of sub-picosecond cross-peaks growth is observed. Ultrafast pump-probe anisotropy studies reveal essentially the same characteristic time for the dipole reorientation. All the experimental data are well modeled in terms of a system undergoing ultrafast population transfer between localized states. Comparison of the experimental observations with simulations reveal a reasonable agreement, although a mechanism including only the fluctuations of the coupling caused by the changes in the dihedral angle of the rotor, is not sufficient to explain the observed ultrafast population transfer. PMID:24182056

  15. Direct measurement of 11B(p ,γ )12C astrophysical S factors at low energies

    NASA Astrophysics Data System (ADS)

    He, J. J.; Jia, B. L.; Xu, S. W.; Chen, S. Z.; Ma, S. B.; Hou, S. Q.; Hu, J.; Zhang, L. Y.; Yu, X. Q.

    2016-05-01

    We directly measure the absolute cross section of 11B(p ,γ )12C in the energy region of Ec .m .=130 -257 keV by using a thin target for the first time. This work is performed on a 320-kV platform at the Institute of Modern Physics in Lanzhou. The astrophysical S factors of this reaction are obtained for capture to the ground and first excited states of 12C. The properties of the known resonance at ˜150 keV are derived and agree with the previous results. However, in the energy region of 170-240 keV, our S factors are about 15%-50% larger than the adopted values in NACRE II and are also larger than the upper limits of NACRE II by up to ˜20 % . This indicates that our new reaction rate is enhanced by about 15%-50% compared to the NACRE II adopted rate in the temperature region 0.32-0.62 GK.

  16. Measurement of the fusion excitation function for 19O + 12C at near barrier energies

    NASA Astrophysics Data System (ADS)

    Singh, Varinderjit; Steinbach, T. K.; Vadas, J.; Wiggins, B. B.; Hudan, S.; Desouza, R. T.; Baby, L. T.; Tripathi, V.; Kuvin, S. A.; Wiedenhover, I.

    2015-10-01

    Fusion of neutron-rich light nuclei in the outer crust of an accreting neutron star has been proposed as responsible for triggering X-ray super-bursts. The underlying hypothesis in this proposition is that the fusion of neutron-rich nuclei is enhanced as compared to stable nuclei. To investigate this hypothesis, an experiment has been performed to measure the fusion excitation function for 18O and 19O nuclei incident on a 12C target. A beam of 19O was produced by the 18O(d,p) reaction at Florida State University and separated using the RESOLUT mass spectrometer. The resulting 19O beam bombarded a 100 μg/cm2 12C target at an intensity of 2-4 × 103 p/s. Evaporation residues resulting from the de-excitation of the fusion product were distinguished by measuring their energy and time-of-flight. Using silicon detectors, micro-channel plate detectors, and an ionization chamber, evaporation residues were detected in the angular range θlab <= 23° with high efficiency. Initial experimental results including measurement of the fusion cross-section to approximately the 100 mb level will be presented. The measured excitation function will be compared to theoretical predictions. Supported by the US DOE under Grand No. DEFG02-88ER-40404.

  17. Multiple-scattering effects in nucleus-nucleus reactions with Glauber theory

    NASA Astrophysics Data System (ADS)

    Hatakeyama, Shinya; Ebata, Shuichiro; Horiuchi, Wataru; Kimura, Masaaki

    2014-09-01

    A study of new unstable nuclei has become possible in new radioactive beam facilities. In order to understand the relationship between reaction observables and nuclear structure, we need reaction theory which exactly reflects the nuclear structure. The Glauber theory is a powerful tool of analyzing high energy nuclear reactions. The theory describes the multiple scattering processes, whereas the optical limit approximation (OLA), which is widely used, ignores those processes. Those effects are expected to play an important role in the nuclear collision involving unstable nuclei (see for example Phys. Rev. C 54, 1843 (1996)). Here we apply the Glauber theory to nucleus-nucleus reactions. The wave functions are generated by the Skyrme-Hartree-Fock method and are expressed in a Slater determinant that allows us to evaluate the complete Glauber amplitude easily. We calculate total reaction cross sections, elastic cross sections and differential elastic cross sections for 16~24O, 40~70Ca, 56,58Ni, 100~140Sn, 190~214Pb on proton, 4He, 12C targets and compare with experimental data. The Glauber theory gives much better description than the OLA, especially at larger scattering angles.

  18. Meson multiplicity versus energy in relativistic nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Atwater, T. W.; Freier, P. S.

    1986-01-01

    A systematic study of meson multiplicity as a function of energy at energies up to 100 GeV/u in nucleus-nucleus collisions has been made, using cosmic-ray data in nuclear emulsion. The data are consistent with simple nucleon-nucleon superposition models. Multiplicity per interacting nucleon in AA collisions does not appear to differ significantly from pp collisions.

  19. Momentum loss in proton-nucleus and nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Khan, Ferdous; Townsend, Lawrence W.

    1993-01-01

    An optical model description, based on multiple scattering theory, of longitudinal momentum loss in proton-nucleus and nucleus-nucleus collisions is presented. The crucial role of the imaginary component of the nucleon-nucleon transition matrix in accounting for longitudinal momentum transfer is demonstrated. Results obtained with this model are compared with Intranuclear Cascade (INC) calculations, as well as with predictions from Vlasov-Uehling-Uhlenbeck (VUU) and quantum molecular dynamics (QMD) simulations. Comparisons are also made with experimental data where available. These indicate that the present model is adequate to account for longitudinal momentum transfer in both proton-nucleus and nucleus-nucleus collisions over a wide range of energies.

  20. The Galactic Nucleus

    NASA Astrophysics Data System (ADS)

    Melia, Fulvio

    Exciting new broadband observations of the galactic nucleus have placed the heart of the Milky Way under intense scrutiny in recent years. This has been due in part to the growing interest from theorists motivated to study the physics of black hole accretion, magnetized gas dynamics, and unusual star formation. The center of our Galaxy is now known to harbor the most compelling supermassive black hole candidate, weighing in at 3-4 million solar masses. Its nearby environment is comprised of a molecular dusty ring, clusters of evolved and young stars, diffuse hot gas, ionized gas streamers, and several supernova remnants. This chapter will focus on the physical makeup of this dynamic region and the feasibility of actually imaging the black hole's shadow in the coming decade with mm interferometry.

  1. The ^{12}C/^{13}C Ratio in the Galactic Center: Implications for Galactic Chemical Evolution and Isotope Chemistry

    NASA Astrophysics Data System (ADS)

    Halfen, DeWayne T.; Ziurys, Lucy M.

    2017-06-01

    Observations from a spectral-line survey of Sgr B2(N) of the ^{12}C and ^{13}C isotopologues of H_2CS, CH_3CCH, NH_2CHO, CH_2CHCN, and CH_3CH_2CN have been analyzed to more accurately establish the ^{12}C/^{13}C ratio in this cloud. The wide spectral coverage has enabled an accurate evaluation of the ^{12}C/^{13}C ratios in these low abundance molecules, based on numerous transitions. The lines typically exhibited two distinct velocity components at 64 and 73 km s^{-1}. The ^{12}C/^{13}C ratio was found to be in the range 18-24 for all 5 molecules, for optically thin transitions, with an average value of 20.5, and did not significantly vary between the two velocity components. The Galactic gradient has been revised to be ^{12}C/^{13}C = 6.08(0.48) D_{GC} + 15.7(2.9). Furthermore, the ^{12}C/^{13}C ratio did not change with substitution site on the molecule. Therefore, there appears to be very little chemical fractionation or isotope-selective photodissociation occurring in Sgr B2(N), and the ^{12}C/^{13}C ratios are a true reflection of the isotopic abundances generated by stellar nucleosynthesis.

  2. Low-energy theorems for pion photoproduction from nuclei and pion-nucleus coupling constants

    SciTech Connect

    Radutskii, G.M.; Serdyutskii, V.A.

    1982-10-01

    New low-energy theorems for pion photoproduction in light nuclei are derived using a model that allows one to extract all the information contained in the current algebra and the CVC and PCAC hypotheses. From the comparison with the experimental total cross sections for threshold photoproduction of charged pions on the nuclei /sup 6/Li, /sup 12/C, and /sup 14/N, the values of the pion-nucleus coupling constants are obtained and the magnitude of the electric quadrupole moment of the /sup 12/N nucleus is predicted.

  3. Measurement of the Induced Proton Polarization Pn in the 12C(e, e', p) reaction

    SciTech Connect

    Woo, R J; Barkhuff, David; Bertozzi, William; Chen, Jian-ping; Dale, Dan; Dodson, G; Dow, K A; Epstein, Marty; Farkhondeh, Manouchehr; Finn, Mike; Gilad, Shalev; Jones, Mark K; Joo, Kyungseon; Kelly, James; Kowalski, Stanley; Lourie, Bob; Madey, Richard; Margaziotis, Dimitri; Markowitz, Pete; McIntyre, Justin; Mertz, Christoph; Milbrath, Brian; Mitchell, Joseph; Perdrisat, Charles F; Punjabi, Vina; Rutt, Paul; Sarty, Adam; Tieger, D; Tschalaer, C; Turchinetz, William; Ulmer, Paul E; Van Verst, S P; Vellidis, C; Warren, Glen; Weinstein, Lawrence

    1998-01-19

    The first measurements of the induced proton polarization Pn for the 12C(e,e',p) reaction are reported. The experiment was performed at quasifree kinematics for energy and momentum transfer (w,q) = (294 MeV, 765 MeV/c) and sampled a missing momentum range of 0-250 MeV/c. The induced polarization arises from final-state interactions and for these kinematics is dominated by the real part of the spin-orbit optical potential. The distorted-wave impulse approximation provides good agreement with data for the 1 p3/2 shell. The data for the continuum suggest that both the 1s1/2 shell and underlying l > 1 configurations contribute.

  4. A New Decay Path in the {sup 12}C+{sup 16}O Radiative Capture Reaction

    SciTech Connect

    Courtin, S.; Lebhertz, D.; Haas, F.; Beck, C.; Michalon, A.; Salsac, M.-D.; Jenkins, D. G.; Marley, P.; Lister, C. J.

    2009-03-04

    The {sup 12}C({sup 16}O,{gamma}){sup 28}Si radiative capture reaction has been studied at energies close to the Coulomb barrier at Triumf (Vancouver) using the Dragon spectrometer and its associated BGO array. It has been observed that the {gamma} decay flux proceeds mainly via states around 10-11 MeV and via the direct feeding of the {sup 28}Si 3{sub 1}{sup -}(6879 keV) and 4{sub 2}{sup +}(6888 keV) deformed states. A discussion is presented about this selective feeding as well as perspectives for the use of novel detection systems for the study of light heavy-ion radiative capture reactions.

  5. Nuclear reaction measurements of 95 MeV/u 12C interactions on PMMA for hadrontherapy

    NASA Astrophysics Data System (ADS)

    Braunn, B.; Labalme, M.; Ban, G.; Chevallier, M.; Colin, J.; Cussol, D.; Dauvergne, D.; Fontbonne, J. M.; Haas, F.; Guertin, A.; Lebhertz, D.; Le Foulher, F.; Pautard, C.; Ray, C.; Rousseau, M.; Salsac, M. D.; Stuttge, L.; Testa, E.; Testa, M.

    2011-11-01

    The ion dose deposition in tissues is characterized by a favorable depth dose profile (i.e. Bragg peak) and a small lateral spread. In order to keep these benefits of ions in cancer treatments, a very high accuracy is required on the dose deposition (±3%). For given target stoichiometry and geometry, the largest uncertainty on the physical dose deposition is due to the ion nuclear fragmentation. We have performed an experiment at GANIL with a 95 MeV/u 12C beam on thick tissue equivalent PMMA targets (thicknesses: 5, 10, 15, 20 and 25 mm). The main goals of this experiment are to provide experimental fragmentation data for benchmarking the physical models used for treatment planning. Production rates, energy and angular distributions of charged fragments have been measured. The purpose of this paper is to present the results of this experiment.

  6. Search for 28Si cluster states through the 12C+16O radiative capture

    NASA Astrophysics Data System (ADS)

    Courtin, S.; Goasduff, A.; Haas, F.; Lebhertz, D.; Jenkins, D. G.; Hutcheon, D. A.; Davis, C.; Ruiz, C.

    2013-03-01

    The 12C+16O resonant radiative capture reaction has been studied at 5 bombarding energies around the Coulomb barrier, between Elab = 15.4 and 21.4 MeV. These experiments have been performed at the TRIUMF laboratory (Vancouver, Canada) using the Dragon 0° spectrometer and the associated BGO array. The most remarkable result is the previously unobserved decay path through 28Si doorway states of energies around 12 MeV leading to the measurement of new capture cross-sections. The feeding of specific, deformed states in 28Si from the resonances is discussed, as well as the selective feeding of 1+ T=1 states around 11 MeV.

  7. Isotopic resolution of fission fragments from 238U+12C transfer and fusion reactions

    NASA Astrophysics Data System (ADS)

    Caamaño, M.; Rejmund, F.; Derkx, X.; Schmidt, K.-H.; Andouin, L.; Bacri, C.-O.; Barreau, G.; Benlliure, J.; Casarejos, E.; Fernández-Domínguez, B.; Gaudefroy, L.; Golabek, C.; Jurado, B.; Lemasson, A.; Navin, A.; Rejmund, M.; Roger, T.; Shrivastava, A.; Schmitt, C.; Taieb, J.

    2009-10-01

    Recent results from an experiment at GANIL, performed to investigate the main properties of fission-fragment yields and energy distributions in different fissioning nuclei as a function of the excitation energy, in a neutron-rich region of actinides, are presented. Transfer reactions in inverse kinematics between a 238U beam and a 12C target produced different actinides, within a range of excitation energy below 30 MeV. These fissioning nuclei are identified by detecting the target-like recoil, and their kinetic and excitation energy are determined from the reconstruction of the transfer reaction. The large-acceptance spectrometer VAMOS was used to identify the mass, atomic number and charge state of the fission fragments in flight. As a result, the characteristics of the fission-fragment isotopic distributions of a variety of neutron-rich actinides are observed for the first time over the complete range of fission fragments.

  8. 12C(alpha,gamma)16O: the key reaction in stellar nucleosynthesis.

    PubMed

    Kunz, R; Jaeger, M; Mayer, A; Hammer, J W; Staudt, G; Harissopulos, S; Paradellis, T

    2001-04-09

    The angular distributions of gamma rays from the 12C(alpha,gamma)16O reaction have been measured at 20 energy points in the energy range E(cm) = 0.95 to 2.8 MeV. The sensitivity of the present experiment compared to previous direct investigations was raised by 1-2 orders of magnitude, by using an array of highly efficient ( 100%) Ge detectors shielded actively with BGOs, as well as high beam currents of up to 500 microA that were provided by the Stuttgart Dynamitron accelerator. The S(E1) and S(E2) factors deduced from the gamma angular distributions have been extrapolated to the range of helium burning temperatures applying the R-matrix method, which yielded S(300)(E1) = (76+/-20) keV b and S(300)(E2) = (85+/-30) keV b.

  9. Research of digital controlled DC/DC converter based on STC12C5410AD

    NASA Astrophysics Data System (ADS)

    Chen, Dan-Jiang; Jin, Xin; Xiao, Zhi-Hong

    2010-02-01

    In order to study application of digital control technology on DC/DC converter, principle of increment mode PID control algorithm was analyzed in the paper. Then, a SCM named STC12C5410AD was introduced with its internal resources and characteristics. The PID control algorithm can be implemented easily based on it. The output of PID control was used to change the value of a variable that is 255 times than duty cycle, and this reduced the error of calculation. The valid of the presented algorithm was verified by an experiment for a BUCK DC/DC converter. The experimental results indicated that output voltage of the BUCK converter is stable with low ripple.

  10. 12C+p resonant elastic scattering in the Maya active target

    NASA Astrophysics Data System (ADS)

    Sambi, S.; Raabe, R.; Borge, M. J. G.; Caamano, M.; Damoy, S.; Fernández-Domínguez, B.; Flavigny, F.; Fynbo, H.; Gibelin, J.; Grinyer, G. F.; Heinz, A.; Jonson, B.; Khodery, M.; Nilsson, T.; Orlandi, R.; Pancin, J.; Perez-Loureiro, D.; Randisi, G.; Ribeiro, G.; Roger, T.; Suzuki, D.; Tengblad, O.; Thies, R.; Datta, U.

    2015-03-01

    In a proof-of-principle measurement, the Maya active target detector was employed for a 12C( p, p) resonant elastic scattering experiment in inverse kinematics. The excitation energy region from 0 to 3MeV above the proton breakup threshold in 13N was investigated in a single measurement. By using the capability of the detector to localize the reaction vertex and record the tracks of the recoiling protons, data covering a large solid angle could be utilized, at the same time keeping an energy resolution comparable with that of direct-kinematics measurements. The excitation spectrum in 13N was fitted using the R-matrix formalism. The level parameters extracted are in good agreement with previous studies. The active target proved its potential for the study of resonant elastic scattering in inverse kinematics with radioactive beams, when detection efficiency is of primary importance.

  11. The intercalatus nucleus of Staderini.

    PubMed

    Cascella, Marco

    2016-01-01

    Rutilio Staderini was one of the leading Italian anatomists of the twentieth century, together with some scientists, such as Giulio Chiarugi, Giovanni Vitali, and others. He was also a member of a new generation of anatomists. They had continued the tradition of the most famous Italian scientists, which started from the Renaissance up until the nineteenth century. Although he carried out important studies of neuroanatomy and comparative anatomy, as well as embryology, his name is rarely remembered by most medical historians. His name is linked to the nucleus he discovered: the Staderini nucleus or intercalated nucleus, a collection of nerve cells in the medulla oblongata located lateral to the hypoglossal nucleus. This article focuses on the biography of the neuroanatomist as well as the nucleus that carries his name and his other research, especially on comparative anatomy and embryology.

  12. Electromagnetic Selection Rules for \\varvec{^{12}}C in a 3 \\varvec{α } Cluster Model

    NASA Astrophysics Data System (ADS)

    Fortunato, L.; Stellin, G.; Vitturi, A.

    2017-01-01

    The recent successful application of the Algebraic Cluster Model to the energy spectrum of ^{12}C has brought a new impetus on spectroscopy of this and other α -conjugate nuclei. In fact, known spectral properties have been reexamined on the basis of vibrations and rotations of three α particles at the vertexes of an equilateral triangle and new excited states have been measured that fit into this scheme. The analysis of this system entails the application of molecular models for rotational-vibrational spectra to the nuclear context and requires deep knowledge of the underlying group-theoretical properties, based on the D_{3h} symmetry, similarly to what is done in quantum chemistry. We have recently analyzed the symmetries of the model and the quantum numbers in great depth, reproducing the all-important results of Wheeler and we have derived electromagnetic selection rules for the system of three α particles, finding, for instance, that electric dipole E1 and magnetic dipole M1 excitations are excluded from the model. The lowest active modes are therefore E2, E3,\\cdots and M2, M3, \\cdots although there are further restrictions between certain types of bands. The selection rules summarized in the text provide a criterion for assigning of observed lines to the alpha cluster model or not and they might help to further unravel the electromagnetic properties of ^{12}C. With the perspective of new facilities (such as ELI) where photo-excitation and photo-dissociation experiments will play a major role, a complete understanding of e.m. selection rules as a tool to confirm or disprove nuclear structure models, is mandatory.

  13. Correction factors to convert microdosimetry measurements in silicon to tissue in (12)C ion therapy.

    PubMed

    Bolst, David; Guatelli, Susanna; Tran, Linh T; Chartier, Lachlan; Lerch, Michael L F; Matsufuji, Naruhiro; Rosenfeld, Anatoly B

    2017-03-21

    Silicon microdosimetry is a promising technology for heavy ion therapy (HIT) quality assurance, because of its sub-mm spatial resolution and capability to determine radiation effects at a cellular level in a mixed radiation field. A drawback of silicon is not being tissue-equivalent, thus the need to convert the detector response obtained in silicon to tissue. This paper presents a method for converting silicon microdosimetric spectra to tissue for a therapeutic (12)C beam, based on Monte Carlo simulations. The energy deposition spectra in a 10 μm sized silicon cylindrical sensitive volume (SV) were found to be equivalent to those measured in a tissue SV, with the same shape, but with dimensions scaled by a factor κ equal to 0.57 and 0.54 for muscle and water, respectively. A low energy correction factor was determined to account for the enhanced response in silicon at low energy depositions, produced by electrons. The concept of the mean path length [Formula: see text] to calculate the lineal energy was introduced as an alternative to the mean chord length [Formula: see text] because it was found that adopting Cauchy's formula for the [Formula: see text] was not appropriate for the radiation field typical of HIT as it is very directional. [Formula: see text] can be determined based on the peak of the lineal energy distribution produced by the incident carbon beam. Furthermore it was demonstrated that the thickness of the SV along the direction of the incident (12)C ion beam can be adopted as [Formula: see text]. The tissue equivalence conversion method and [Formula: see text] were adopted to determine the RBE10, calculated using a modified microdosimetric kinetic model, applied to the microdosimetric spectra resulting from the simulation study. Comparison of the RBE10 along the Bragg peak to experimental TEPC measurements at HIMAC, NIRS, showed good agreement. Such agreement demonstrates the validity of the developed tissue equivalence correction factors and of

  14. Spectral temperatures of {Delta}{sup 0}(1232) resonances produced in p{sup 12}C and d{sup 12}C collisions at 4.2 GeV/c per nucleon

    SciTech Connect

    Khan, Imran; Olimov, Kh. K.

    2013-07-15

    The reconstructed experimental transverse momentum (p{sub t}) distributions of {Delta}{sup 0}(1232) resonances produced in p{sup 12}C and d{sup 12}C collisions at 4.2 A GeV/c and the corresponding spectra calculated using Modified FRITIOF model were analyzed in the framework of Hagedorn Thermodynamic Model. The spectral temperatures of {Delta}{sup 0}(1232) resonances were extracted from fitting their p{sub t} spectra with one-temperature Hagedorn function. The extracted spectral temperatures of {Delta}{sup 0}(1232) were compared with the corresponding temperatures of {pi}{sup -} mesons in p{sup 12}C and d{sup 12}C collisions at 4.2 A GeV/c obtained similarly from fitting the p{sub t} spectra of {pi}{sup -} by one-temperature Hagedorn function. The spectral temperatures of {Delta}{sup 0}(1232) resonances agreed within uncertainties with the corresponding temperatures of {pi}{sup -} mesons produced in p{sup 12}C and d{sup 12}C collisions at 4.2 A GeV/c.

  15. Mechanics of the Nucleus

    PubMed Central

    Lammerding, Jan

    2015-01-01

    The nucleus is the distinguishing feature of eukaryotic cells. Until recently, it was often considered simply as a unique compartment containing the genetic information of the cell and associated machinery, without much attention to its structure and mechanical properties. This article provides compelling examples that illustrate how specific nuclear structures are associated with important cellular functions, and how defects in nuclear mechanics can cause a multitude of human diseases. During differentiation, embryonic stem cells modify their nuclear envelope composition and chromatin structure, resulting in stiffer nuclei that reflect decreased transcriptional plasticity. In contrast, neutrophils have evolved characteristic lobulated nuclei that increase their physical plasticity, enabling passage through narrow tissue spaces in their response to inflammation. Research on diverse cell types further demonstrates how induced nuclear deformations during cellular compression or stretch can modulate cellular function. Pathological examples of disturbed nuclear mechanics include the many diseases caused by mutations in the nuclear envelope proteins lamin A/C and associated proteins, as well as cancer cells that are often characterized by abnormal nuclear morphology. In this article, we will focus on determining the functional relationship between nuclear mechanics and cellular (dys-)function, describing the molecular changes associated with physiological and pathological examples, the resulting defects in nuclear mechanics, and the effects on cellular function. New insights into the close relationship between nuclear mechanics and cellular organization and function will yield a better understanding of normal biology and will offer new clues into therapeutic approaches to the various diseases associated with defective nuclear mechanics. PMID:23737203

  16. Analysis and theoretical modeling of the 18O enriched carbon dioxide spectrum by CRDS near 1.35 μm: (I) 16O12C18O, 16O12C17O, 12C16O2 and 13C16O2

    NASA Astrophysics Data System (ADS)

    Kassi, S.; Karlovets, E. V.; Tashkun, S. A.; Perevalov, V. I.; Campargue, A.

    2017-01-01

    The room temperature absorption spectrum of 18O enriched carbon dioxide has been recorded by very high-sensitivity Cavity Ring Down spectroscopy between 6977 and 7918 cm-1 (1.43-1.26 μm). The achieved sensitivity (noise equivalent absorption αmin 8×10-11 cm-1) has allowed for the detection of more than 8600 lines belonging to 166 bands of eleven carbon dioxide isotopologues. Line intensities of the weakest observed transitions are on the order of 2×10-30 cm/molecule. In this first part, we present the results relative to the 16O12C18O, 16O12C17O, 12C16O2 and 13C16O2 isotopologues. Their absorption lines were rovibrationally assigned on the basis of the predictions of their respective effective Hamiltonian model. Overall 5476 lines were measured and assigned to 93 bands. Forty nine of them, all belonging to 16O12C18O and 16O12C17O, are reported for the first time. The studied spectral region is formed by ΔP=10-12 series of transitions, where P=2V1+V2+3V3 is the polyad number (Vi are vibrational quantum numbers). The spectroscopic parameters of 58 bands of 16O12C18O and 16O12C17O were determined from a fit of the measured line positions. An inter- and an intrapolyad resonance perturbation were identified and analyzed in the 16O12C18O spectrum. The comparison with the line positions and line intensities included in the AMES line list is discussed. Global fits of the line intensities were performed in order to (i) improve the ΔP=10 and 11 sets of the effective dipole moment parameters of 16O12C18O and the ΔP=11 set of parameters of 16O12C17O and (ii) derive for the first time the ΔP=10 and 12 parameters of 16O12C17O and 16O12C18O, respectively.

  17. {sup 7,9,10}Be elastic scattering and total reaction cross sections on a {sup 12}C target

    SciTech Connect

    Zamora, J. C.; Guimaraes, V.; Barioni, A.; Lepine-Szily, A.; Lichtenthaeler, R.; Faria, P. N. de; Mendes, D. R. Jr.; Gasques, L. R.; Scarduelli, V.; Pires, K. C. C.; Morcelle, V.; Leistenschneider, E.; Condori, R. P.; Zagatto, V. A.; Morais, M. C.; Crema, E.; Shorto, J. M. B.

    2011-09-15

    Elastic scattering angular distributions for {sup 7}Be, {sup 9}Be, and {sup 10}Be isotopes on {sup 12}C target were measured at laboratory energies of 18.8, 26.0, and 23.2 MeV, respectively. The analysis was performed in terms of optical model potentials using Woods-Saxon and double-folding form factors. Also, continuum discretized coupled-channels calculations were performed for {sup 7}Be and {sup 9}Be + {sup 12}C systems to infer the role of breakup in the elastic scattering. For the {sup 10}Be + {sup 12}C system, bound states coupled-channels calculations were considered. Moreover, total reaction cross sections were deduced from the elastic scattering analysis and compared with published data on other weakly and tightly bound projectiles elastically scattered on the {sup 12}C target, as a function of energy.

  18. X-ray diffraction study of the binding of the antisickling agent 12C79 to human hemoglobin

    SciTech Connect

    Wireko, R.C.; Abraham, D.J. )

    1991-03-15

    The hemoglobin binding site of the antisickling agent 12C79 has been determined by x-ray crystallography. 12C79 is recognized as one of the first molecules to reach clinical trials that was designed, de novo, from x-ray-determined atomic coordinates of a protein. Several previous attempts to verify the proposed Hb binding sites via crystallographic studies have failed. Using revised experimental procedures, the authors obtained 12C79-deoxhemoglobin crystals grown after reaction with oxyhemoglobin and cyanoborohydride reduction to stabilize the Schiff base linkage. The difference electron-density Fourier maps show that two 12C79 molecules bind covalently to both symmetry-related N-terminal amino groups of the hemoglobin {alpha} chains. This is in contrast to the original design that proposed the binding of one drug molecule that spans the molecular dyad to interact with both N-terminal {alpha}-amino groups.

  19. {sup {bold 6}}Li(vector)+{sup {bold 12}}C inelastic scattering at 30 and 50 MeV

    SciTech Connect

    Kerr, P.L.; Kemper, K.W.; Green, P.V.; Mohajeri, K.; Myers, E.G.; Schmidt, B.G.; Hnizdo, V.

    1996-09-01

    A complete set of analyzing powers (AP`s), {ital iT}{sub 11}, {ital T}{sub 20}, {ital T}{sub 21}, and {ital T}{sub 22}, for 50 MeV {sup 12}C({sup 6}Li(vector),{sup 6}Li) elastic scattering and inelastic scattering to the {sup 12}C(2{sup +}, 4.44 MeV), {sup 12}C(0{sup +}, 7.65 MeV), and {sup 12}C(3{sup {minus}}, 9.64 MeV) states over the center-of-mass (c.m.) angular range 10{degree}{endash}115{degree} is reported. In addition, cross sections for the excited states 3{sup +}(2.18 MeV), 2{sup +}(4.31 MeV), and 1{sup +}(5.65 MeV) of {sup 6}Li were measured by using the inverse-kinematics reaction {sup 6}Li({sup 12}C,{sup 12}C) at 100 MeV. A combined analysis of the new 50 MeV data and previous 30 MeV data has been carried out using the coupled-channels (CC) code FRESCO. The CC calculations use an optical potential with double-folded (DF) real central, Woods-Saxon imaginary central, and Thomas real spin-orbit (SO) potentials. Calculations include reorientation terms and coupling to the first three excited states of {sup 6}Li and the first two nonzerospin states of {sup 12}C. The {sup 6}Li coupling strengths were fixed by the measured {sup 6}Li excited-state cross sections. The elastic-scattering cross sections and A.P.`s are described well. The need for an explicit SO potential is apparent in the elastic and inelastic-scattering AP`s {ital iT}{sub 11}, more so at 30 MeV than at 50 MeV. The rank-2 AP`s up to 50{degree} c.m. arise mainly from ground-state reorientation effects. The DF potential normalization constant {ital N} approaches unity for the 50 MeV data. At both energies, the {sup 12}C(2{sup +}) cross sections are underestimated at large angles, and the description of the {sup 12}C(3{sup {minus}}) cross sections is poor in detail. The {sup 12}C(3{sup {minus}}) AP`s and the {sup 12}C(2{sup +}) {ital iT}{sub 11} are not reproduced at either energy. {copyright} {ital 1996 The American Physical Society.}

  20. Measurement of γ-rays from Giant Resonances of 16O and 12C with Application to Supernova Neutrino Detection

    NASA Astrophysics Data System (ADS)

    Ou, Iwa; Yamada, Yoshiyuyki; Shirahige, Tetsuya; Fukuda, Daisuke; Yano, Takatomi; Mori, Takaaki; Koshio, Yusuke; Sakuda, Makoto; Dhir, Rohit; Tamii, Atsushi; Aoi, Nori; Yosoi, Masaru; Ideguchi, Eiji; Suzuki, Tomokazu; Iwamoto, Chihiro; Ito, Takeshi; Miura, Masaki; Yamamoto, Tetsuya; Kawabata, Takahiro; Adachi, Satoshi; Tsumura, Miho; Murata, Motoki; Furuno, Tatsuya; Akimune, Hidetoshi; Nakada, Hitoshi

    We report preliminary results on the detection of the γ-rays from giant resonances of 16O and 12C nuclei from the experiment carried out at Research Center for Nuclear Physics Osaka University. These γ-rays can be used to detect the μ and τ type neutrinos and anti-neutrinos, emitted from a core-collapse supernova, through neutral current reactions with 16O and 12C by large-scale neutrino detectors.

  1. Role of break-up processes in the fusion of the {sup 12}C+ {sup 52}Cr system

    SciTech Connect

    Amanuel, F. K.; Zelalem, B.; Chaubey, A. K.; Agarwal, Avinash; Rizvi, I. A.; Maheshwari, Anjana; Ahmed, Tauseef

    2011-08-15

    We present the results and analysis of our investigation of the role of break-up processes on the fusion of a {sup 12}C{sup 6+} beam with a {sup 52}Cr target near, at, and above the Coulomb barrier. In this experiment the excitation functions of evaporation residues produced via ({sup 12}C, 2n), ({sup 12}C, pxn), ({sup 12}C, {alpha}xn), and ({sup 12}C, {alpha}pxn) channels in a {sup 12}C + {sup 52}Cr reaction were measured at several beam energies ranging from {approx_equal}51 to 87 MeV by employing the recoil catcher technique followed by off-line {gamma}-ray spectrometry. The measured excitation functions were compared with theoretical values obtained using the pace4 statistical model code. Further, for a ({sup 12}C, p2n) channel the measured excitation function was compared with the predictions of the alice-91 code, which was chosen as it takes into account pre-equilibrium emissions. For non-{alpha}-emitting channels, the experimentally measured excitation functions--after correcting them for possible contributions from higher charge isobaric precursor decays--were, in general, found to be in good agreement with theoretical predictions. However, for {alpha}-emitting channels, the measured excitation functions had significantly more production cross sections than what pace4 predicted. This enhancement may be attributed to incomplete fusion processes. An attempt was made to estimate the incomplete fusion fraction in order to compare the relative importance of complete and incomplete fusion processes. The incomplete fusion fraction was found to be sensitive to the projectile energy and mass asymmetry of the entrance channel. We also discuss the results in terms of the impact of the frozen {alpha}-cluster structure of the {sup 12}C isotope on various fusion reactions.

  2. Relative biological effectiveness of 12C and 28Si radiation in C57BL/6J mice.

    PubMed

    Suman, Shubhankar; Datta, Kamal; Trani, Daniela; Laiakis, Evagelia C; Strawn, Steven J; Fornace, Albert J

    2012-08-01

    Study of heavy ion radiation-induced effects on mice could provide insight into the human health risks of space radiation exposure. The purpose of the present study is to assess the relative biological effectiveness (RBE) of (12)C and (28)Si ion radiation, which has not been reported previously in the literature. Female C57BL/6J mice (n = 15) were irradiated using 4-8 Gy of (28)Si (300 MeV/nucleon energy; LET 70 keV/μm) and 5-8 Gy of (12)C (290 MeV/nucleon energy; LET 13 keV/μm) ions. Post-exposure, mice were monitored regularly, and their survival observed for 30 days. The LD(50/30) dose (the dose at which 50 % lethality occurred by 30-day post-exposure) was calculated from the survival curve and was used to determine the RBE of (28)Si and (12)C in relation to γ radiation. The LD(50/30) for (28)Si and (12)C ion is 5.17 and 7.34 Gy, respectively, and the RBE in relation to γ radiation (LD(50/30)-7.25 Gy) is 1.4 for (28)Si and 0.99 for (12)C. Determination of RBE of (28)Si and (12)C for survival in mice is not only important for space radiation risk estimate studies, but it also has implications for HZE radiation in cancer therapy.

  3. CO2 and 12C:13C Isotopic Ratios on Phoebe and Iapetus

    NASA Astrophysics Data System (ADS)

    Clark, R. N.; Brown, R. H.; Cruikshank, D. P.

    2016-12-01

    Cassini VIMS has obtained spatially resolved 0.35 to 5.1 micron reflectance spectra of Saturn's satellites beginning with the Phoebe fly-by in 2004 and a close fly-by of Iapetus in 2007. Both surfaces contain relatively abundant CO2. The new (2016 RC19) calibration of VIMS has provided a significant increase in the data quality, such that isotopic absorption bands in CO2 are now well defined. CO2 on Saturn's icy satellites is trapped (Cruikshank et al., 2010, Icarus v206 p561; Pinilla-Alonso et al. 2011, Icarus v211, p75i), predominantly in the dark material (Clark et al. 2012, Icarus v218 p831). Clark et al. modeled the CO2 abundance as 2.8% on Iapetus and 3.7% on Phoebe. The main 12CO2 band in VIMS spectra on Iapetus occurs at 4.253 microns and Phoebe at 4.266 microns. The 13CO2 absorption is strong on Phoebe at 4.367 microns and weak on Iapetus at 4.387 microns. Converting the Phoebe, Iapetus, and a lab reflectance spectrum (of trace H2O-CO2 mixture on a diffuse substrate), we derive preliminary values for the ratio of the equivalent widths of the 12C and 13C absorptions as 19±2 on Phoebe, 82±8 on Iapetus, and 98±10 for the laboratory spectrum. These ratios are related to the 12C/13C ratio, but there may be effects due to intra-molecular and inter-molecular coupling that will contribute to systematic errors in the isotopic abundances derived using equivalent-width measurements that we've yet to quantify. We Believe the effects are small, and will be attempting to quantify them in the future. For comparison, the terrestrial value of the 12C/13C ratio is 90.17, and vibrational coupling may explain the slightly high lab mixture result. The local interstellar medium is 69±15 (Boogert et al., 2000, A&A). Because the CO2 bands on Phoebe and Iapetus dark material have different positions, and because the observed 13C absorption strengths are so different, the surface evolutions must be different. The large enrichment in 13C on Phoebe argues for significant

  4. YF-12A and YF-12C in flight formation at dawn

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The YF-12A (60-6935) carries the 'coldwall' heat transfer pod on a pylon beneath the forward fuselage. The pod is seen with its insulating coating intact. In the background, the YF-12C flies photo chase. The coldwall project, supported by Langley Research Center, consisted of a stainless steel tube equipped with thermocouples and pressure-sensors. A special insulating coating covered the tube, which was chilled with liquid nitrogen. At Mach 3, the insulation could be pyrotechnically blown away from the tube, instantly exposing it to the thermal environment. The experiment caused many inflight difficulties, such as engine unstarts, but eventually researchers got a successful flight. The Flight Research Center's involvement with the YF-12A, an interceptor version of the Lockheed A-12, began in 1967. Ames Research Center was interested in using wind tunnel data that had been generated at Ames under extreme secrecy. Also, the Office of Advanced Research and Technology (OART) saw the YF-12A as a means to advance high-speed technology, which would help in designing the Supersonic Transport (SST). The Air Force needed technical assistance to get the latest reconnaissance version of the A-12 family, the SR-71A, fully operational. Eventually, the Air Force offered NASA the use of two YF-12A aircraft, 60-6935 and 60-6936. A joint NASA-USAF program was mapped out in June 1969. NASA and Air Force technicians spent three months readying 935 for flight. On 11 December 1969, the flight program got underway with a successful maiden flight piloted by Col. Joe Rogers and Maj. Gary Heidelbaugh of the SR-71/F-12 Test Force. During the program, the Air Force concentrated on military applications, and NASA pursued a loads research program. NASA studies included inflight heating, skin-friction cooling, 'coldwall' research (a heat transfer experiment), flowfield studies, shaker vane research, and tests in support of the Space Shuttle landing program. Ultimately, 935 became the workhorse

  5. YF-12A and YF-12C in flight formation at dawn

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The YF-12A (60-6935) carries the 'coldwall' heat transfer pod on a pylon beneath the forward fuselage. The pod is seen with its insulating coating intact. In the background, the YF-12C flies photo chase. The coldwall project, supported by Langley Research Center, consisted of a stainless steel tube equipped with thermocouples and pressure-sensors. A special insulating coating covered the tube, which was chilled with liquid nitrogen. At Mach 3, the insulation could be pyrotechnically blown away from the tube, instantly exposing it to the thermal environment. The experiment caused many inflight difficulties, such as engine unstarts, but eventually researchers got a successful flight. The Flight Research Center's involvement with the YF-12A, an interceptor version of the Lockheed A-12, began in 1967. Ames Research Center was interested in using wind tunnel data that had been generated at Ames under extreme secrecy. Also, the Office of Advanced Research and Technology (OART) saw the YF-12A as a means to advance high-speed technology, which would help in designing the Supersonic Transport (SST). The Air Force needed technical assistance to get the latest reconnaissance version of the A-12 family, the SR-71A, fully operational. Eventually, the Air Force offered NASA the use of two YF-12A aircraft, 60-6935 and 60-6936. A joint NASA-USAF program was mapped out in June 1969. NASA and Air Force technicians spent three months readying 935 for flight. On 11 December 1969, the flight program got underway with a successful maiden flight piloted by Col. Joe Rogers and Maj. Gary Heidelbaugh of the SR-71/F-12 Test Force. During the program, the Air Force concentrated on military applications, and NASA pursued a loads research program. NASA studies included inflight heating, skin-friction cooling, 'coldwall' research (a heat transfer experiment), flowfield studies, shaker vane research, and tests in support of the Space Shuttle landing program. Ultimately, 935 became the workhorse

  6. Investigation of the reaction mechanism for the four-particle photodisintegration of a carbon nucleus

    NASA Astrophysics Data System (ADS)

    Afanas'ev, S. N.; Gorbenko, E. S.; Khodyachikh, A. F.

    2007-05-01

    The four-particle photodisintegration of a carbon nucleus in the reactions 12C(γ, p)3H2α and 12C(γ, n)3H2α is investigated by a method that employs a diffusion chamber in a magnetic field. It is shown that these reactions proceed according a sequential-type scheme: excited states of 11B and 11C nuclei decay to weakly excited states of 8Be, 7Li, and 7Be nuclei. It is concluded that nucleons are knocked out from the s shell. In the excitation curve for the 2α system in the reaction 12C(γ, p)3H2α, a resonance is found between the maxima corresponding to the ground and the first excited state of the 8Be nucleus, and this resonance is identified as a ghost anomaly. The branching fractions of the decay modes are determined. The angular distributions of nucleons in the reaction c.m. frame are measured. The energy dependence of the asymmetry coefficient for the angular distributions is obtained. A fast increase in this coefficient is observed in the energy range 38 40 MeV. It is concluded that the asymmetry coefficient depends on the excitation energy of the final nucleus in the region of intermediate photon energies.

  7. Correction factors to convert microdosimetry measurements in silicon to tissue in 12C ion therapy

    NASA Astrophysics Data System (ADS)

    Bolst, David; Guatelli, Susanna; Tran, Linh T.; Chartier, Lachlan; Lerch, Michael L. F.; Matsufuji, Naruhiro; Rosenfeld, Anatoly B.

    2017-03-01

    Silicon microdosimetry is a promising technology for heavy ion therapy (HIT) quality assurance, because of its sub-mm spatial resolution and capability to determine radiation effects at a cellular level in a mixed radiation field. A drawback of silicon is not being tissue-equivalent, thus the need to convert the detector response obtained in silicon to tissue. This paper presents a method for converting silicon microdosimetric spectra to tissue for a therapeutic 12C beam, based on Monte Carlo simulations. The energy deposition spectra in a 10 μm sized silicon cylindrical sensitive volume (SV) were found to be equivalent to those measured in a tissue SV, with the same shape, but with dimensions scaled by a factor κ equal to 0.57 and 0.54 for muscle and water, respectively. A low energy correction factor was determined to account for the enhanced response in silicon at low energy depositions, produced by electrons. The concept of the mean path length < {{l}\\text{Path}}> to calculate the lineal energy was introduced as an alternative to the mean chord length < l> because it was found that adopting Cauchy’s formula for the < l> was not appropriate for the radiation field typical of HIT as it is very directional. < {{l}\\text{Path}}> can be determined based on the peak of the lineal energy distribution produced by the incident carbon beam. Furthermore it was demonstrated that the thickness of the SV along the direction of the incident 12C ion beam can be adopted as < {{l}\\text{Path}}> . The tissue equivalence conversion method and < {{l}\\text{Path}}> were adopted to determine the RBE10, calculated using a modified microdosimetric kinetic model, applied to the microdosimetric spectra resulting from the simulation study. Comparison of the RBE10 along the Bragg peak to experimental TEPC measurements at HIMAC, NIRS, showed good agreement. Such agreement demonstrates the validity of the developed tissue equivalence correction factors and of the determination of < {{l}\\text{Path}}> .

  8. Hyperon-nucleus potentials

    NASA Astrophysics Data System (ADS)

    Dover, C. B.; Gal, A.

    We review models for the interaction of baryons ( N, Λ, Σ and Ξ) with nuclei, emphasizing the underlying meson exchange picture. Starting from a phenomenological one boson exchange model (the Nijmegen potential, as an example) which accounts for the available NN, ΛN and ΣN two-body scattering data, we show how to construct the effective baryon-nucleon interaction ( G-matrix). Employing the folding model, we then obtain the many-body potentials for bound states in terms of the nuclear density and the appropriate spin-isospin weighted G-matrices. The models we emphasize most impose SU(3) constraints on baryon-baryon coupling constants SU(3) is broken through the use of physical masses), although we also compare with rough estimates based on quark model relations between coupling constants. We stress the essential unity and economy of such models, in which nucleon and hyperon-nucleus potentials are intimately related via SU(3), and the connection between the two-body and many-body potentials is preserved. We decompose the nuclear potentials into central and spin-orbit parts, each of which is isospin dependent. For nucleons, the microscopic origin of the isospin dependent Lane potential V1 N is clarified. For Λ and Σ hyperons, the one boson exchange model with SU(3) constraints leads to one-body spin-orbit strengths VLSB which are relatively weak ( VLSΛ ≈ 1.5-2 MeV, VLSΣ ≈ 2.5-;3 MeV, compared to VLSN ≈ 7-9 MeV). We demonstrate the interplay between symmetric and antisymmetric two-body spin-orbit forces which give rise to these results, as well as the special role of K and K ∗ exchange for hyperons. We contrast these results with predictions based on the naive quark model. From S and P-wave two-body interactions, a Lane potential for the Σ of depth V1 Σ ≈ 50-60 MeV is predicted although this result is somewhat uncertain. For the Ξ, the nuclear potential is very different in various models for the two-body interaction based on SU(3) or the quark

  9. Unexpected doubly-magic nucleus.

    SciTech Connect

    Janssens, R. V. F.; Physics

    2009-01-01

    Nuclei with a 'magic' number of both protons and neutrons, dubbed doubly magic, are particularly stable. The oxygen isotope {sup 24}O has been found to be one such nucleus - yet it lies just at the limit of stability.

  10. Multimodal Imaging Using a 11B(d,nγ)12C Source

    NASA Astrophysics Data System (ADS)

    Nattress, Jason; Rose, Paul; Mayer, Michal; Wonders, Marc; Wilhelm, Kyle; Erickson, Anna; Jovanovic, Igor; Multimodal Imaging; Nuclear Detection (MIND) in Active Interrogation Collaboration

    2016-03-01

    Detection of shielded special nuclear material (SNM) still remains one of the greatest challenges facing nuclear security, where small signal-to-background ratios result from complex, challenging configurations of practical objects. Passive detection relies on the spontaneous radioactive decay, whereas active interrogation (AI) uses external probing radiation to identify and characterize the material. AI provides higher signal intensity, providing a more viable method for SNM detection. New and innovative approaches are needed to overcome specific application constraints, such as limited scanning time. We report on a new AI approach that integrates both neutron and gamma transmission signatures to deduce specific material properties that can be utilized to aid SNM identification. The approach uses a single AI source, single detector type imaging system based on the 11B(d,nγ)12C reaction and an array of eight EJ-309 liquid scintillators, respectively. An integral transmission imaging approach has been employed initially for both neutrons and photons, exploiting the detectors' particle discrimination properties. Representative object images using neutrons and photons will be presented.

  11. Determination of (C-12)/(C-13) in the interstellar medium toward Zeta Ophiuchi and Xi Persei

    NASA Technical Reports Server (NTRS)

    Hawkins, Isabel; Craig, Nahide; Meyer, David M.

    1993-01-01

    The Lick Observatory Reticon (LOR) data presented in Hawkins et al. (1985) are reanalyzed in order to determine the cause of the significant discrepancy in (C-12)/(C-13) isotope ratios determined on the basis of observations of this isotope in the interstellar medium toward Zeta Ophiuchi and Xi Persei. A new set of Lick Observatory observations toward Zeta Oph are obtained using a CCD detector. The KPNO coude feed echelle spectrograph and a CCD detector are used to carry out high-resolution, high SNR ratio observations toward Zeta Oph and Xi Per. The LOR results for Zeta Oph are uncertain, ranging to 40 to 60, owing to the error in continuum placement. The KPNO results toward Zeta Oph are (C-12)H/(C-13)H(+)(0, 0) = 63 +/- 8, (C-12)H(+)/(C-13)H(+)(1, 0) = 67 +/- 19, and (C-12)N/(C-13)N = 100 + 88/- 33. Toward Xi Per, the KPNO measurements yield (C-12)H(+)/(C-13)H(+) = 49 +/- 15 from the 4232-A band, and a lower limit of 45 from the 3957-A observations.

  12. Charged current antineutrino reactions from {sup 12}C at MiniBooNE energies

    SciTech Connect

    Athar, M. Sajjad; Ahmad, Shakeb; Singh, S. K.

    2007-05-01

    A study of charged current induced antineutrino interactions from nuclei has been done for the intermediate energy antineutrinos and applied to {sup 12}C, relevant for ongoing experiment by MiniBooNE collaboration. The calculations have been done for the quasielastic and inelastic lepton production as well as for the incoherent and the coherent pion production processes. The calculations are done in local density approximation. In the case of the quasielastic reaction the effects of Pauli blocking, Fermi motion effects, renormalization of weak transition strengths in nuclear medium and the Coulomb distortion of the outgoing lepton have been taken into account. For the inelastic processes the calculations have been done in the {delta} dominance model and take into account the effect of Pauli blocking, Fermi motion of the nucleon, and renormalization of {delta} properties in a nuclear medium. The effect of final state interactions of pions is also taken into account. The numerical results for the total cross sections for the charged current quasielastic scattering and incoherent pion production processes are compared with earlier experimental results available in freon and freon-propane. It is found that nuclear medium effects give strong reduction in the cross sections leading to satisfactory agreement with the available data.

  13. 12C(α,γ)16O cross sections at stellar energies

    NASA Astrophysics Data System (ADS)

    Ouellet, J. M. L.; Butler, M. N.; Evans, H. C.; Lee, H. W.; Leslie, J. R.; MacArthur, J. D.; McLatchie, W.; Mak, H.-B.; Skensved, P.; Whitton, J. L.; Zhao, X.; Alexander, T. K.

    1996-10-01

    The excitation function of the 12C(α,γ)16O reaction and the angular distribution of its γ rays were measured at nine center-of-mass energies ranging from E=1.37 to 2.98 MeV. These measurements allowed the separation of the E1 and E2 contributions and their extrapolation to the region of astrophysical interest. The analysis of all the available E1 cross sections with the K-matrix method and with a three-level R-matrix method yields a consistent prediction of 79+/-16 keV b for the E1 S factor at 300 keV. The E2 contribution at the same energy is 36+/-6 keV b from a cluster model analysis of the present data. The best estimate of the total S factor at 300 keV is 120 keV b, and it is unlikely that it will fall outside the range of 80-160 keV b.

  14. Accurate partition function for acetylene, 12C2H2, and related thermodynamical quantities.

    PubMed

    Amyay, B; Fayt, A; Herman, M

    2011-12-21

    The internal partition function (Q(int)) of ethyne (acetylene), (12)C(2)H(2), is calculated by explicit summation of the contribution of all individual vibration-rotation energy levels up to 15,000 cm(-1). The corresponding energies are predicted from a global model and constants reproducing within 3σ all 18,415 published vibration-rotation lines in the literature involving vibrational states up to 8900 cm(-1), as produced by Amyay et al. [J. Mol. Spectrosc. 267, 80 (2011)]. Values of Q(int), with distinct calculations for para and ortho species are provided from 1 to 2000 K, in step of 1 K. The total internal partition function at 298.15 K is 104.224387(47) or 416.89755(19), with the nuclear degeneracy spin factors taken as 1/4:3/4 (astronomer convention) or 1:3 (atmospheric convention), respectively, for para:ortho species. The Helmholtz function, Gibbs enthalpy function, entropy, and specific heat at constant pressure are also calculated over the same temperature range. Accuracies as well as the missing contribution of the vinylidene isomer of acetylene in the calculations are discussed.

  15. Electrophysiological effects of 12C on patients undergoing heavy ions therapy at GSI: a pilot study

    NASA Astrophysics Data System (ADS)

    Sannita, W. G.; Narici, L.; Debus, J.; Carozzo, S.; Saturno, M.; Schardt, D.; Schulz-Ertner, D.

    Phosphenes light flashes observed in space have been attributed to heavy ions interfering with the retina photoreceptors However their generating mechanisms are still undefined and neurons of the retina and non-ocular visual structures are as sensitive to ionizing agents as retinal photoreceptors Multiple sources are therefore possible that could question safety in manned space travel Patients undergoing 12C ion therapy of skull tumors also involving the anterior optic pathway often report phosphenes similar to those described by astronauts and volunteers in accelerator experiments In a pilot study their occurrence either within each beam pulse or shortly after it in case of very short pulses correlated with the beam position and local dose deposited near the optic nerve or eye during irradiation Further research is in progress at the GSI Biophysics facilities in Darmstadt FRG Purposes of the study are 1- to identify electrophysiological cortical concomitants of phosphenes 2- to correlate phosphenes with irradiated portions of the anterior visual pathways and with known basic mechanisms of vision and 3- to obtain information to be used in the understanding of phosphenes observed in space We will present preliminary results from the first measurements

  16. Effects of heat treatment on Raman spectra of two-layer 12C/13C graphene.

    PubMed

    Kalbac, Martin; Frank, Otakar; Kavan, Ladislav

    2012-10-22

    The Raman spectra of two-layered graphene on a silicon substrate were studied in the temperature range from 298 to 1073 K in an inert atmosphere. Isotopic engineering was used to fabricate two-layer graphene specimens containing (13)C atoms in the top layer and (12)C atoms in the bottom layer, which allowed the behavior of each particular layer to be distinguished as a function of temperature. It is demonstrated that the top layer exhibits much lower Raman temperature coefficients than the bottom one for both the G and the G' modes. We suggest that the changes in the Raman spectra of graphene observed during thermal cycling are predominantly caused by a superposition of two effects, namely, the mechanical stress in graphene exerted by the substrate and the intrinsic changes in the graphene lattice caused by the temperature itself. The top graphene layer is proposed to be more relaxed than the bottom graphene layer and thus reflects almost exclusively the temperature variations as a freestanding graphene layer would.

  17. Measurements of 12C ions beam fragmentation at large angle with an Emulsion Cloud Chamber

    NASA Astrophysics Data System (ADS)

    Alexandrov, A.; De Lellis, G.; Di Crescenzo, A.; Lauria, A.; Montesi, M. C.; Pastore, A.; Patera, V.; Sarti, A.; Tioukov, V.

    2017-08-01

    Hadron radiotherapy is a powerful technique for the treatment of deep-seated tumours. The physical dose distribution of hadron beams is characterized by a small dose delivered in the entrance channel and a large dose in the Bragg peak area. Fragmentation of the incident particles and struck nuclei occurs along the hadron path. Knowledge of the fragment energies and angular distributions is crucial for the validation of the models used in treatment planning systems. We report on large angle fragmentation measurements of a 400 MeV/n 12C beam impinging on a composite target at the GSI laboratory in Germany. The detector was made of 300 micron thick nuclear emulsion films, with sub-micrometric spatial resolution and large angle track detection capability, interleaved with passive material. Thanks to newly developed techniques in the automated scanning of emulsions it was possible to extend the angular range of detected particles. This resulted in the first measurement of the angular and momentum spectrum for fragments emitted in the range from 34o to 81o.

  18. Carbon isotope ratio (13C/12C) of pine honey and detection of HFCS adulteration.

    PubMed

    Çinar, Serap B; Ekşi, Aziz; Coşkun, İlknur

    2014-08-15

    Carbon isotope ratio ((13)C/(12)C=δ(13)C) of 100 pine honey samples collected from 9 different localities by Mugla region (Turkey) in years 2006, 2007 and 2008 were investigated. The δ(13)Cprotein value of honey samples ranged between -23.7 and -26.6‰, while the δ(13)Choney value varied between -22.7 and -27‰. For 90% of the samples, the difference in the C isotope ratio of protein and honey fraction (δ(13)Cpro-δ(13)Chon) was -1.0‰ and/or higher. Therefore, it can be said that the generally anticipated minimum value of C isotope difference (-1.0‰) for honey is also valid for pine honey. On the other hand, C4 sugar value (%), which was calculated from the δ(13)Cpro-δ(13)Chon difference, was found to be linearly correlated with the amount of adulterant (HFCS) in pine honey. These results indicate that C4 sugar value is a powerful criteria for detecting HFCS adulteration in pine honey. The δ(13)Choney and δ(13)Cprotein-δ(13)Choney values of the samples did not show any significant differences in terms of both year and locality (P>0.05), while the δ(13)Cprotein values showed significant differences due to year (P<0.05) but not due to locality (P>0.05).

  19. Determination of (C-12)/(C-13) in the interstellar medium toward Zeta Ophiuchi and Xi Persei

    NASA Technical Reports Server (NTRS)

    Hawkins, Isabel; Craig, Nahide; Meyer, David M.

    1993-01-01

    The Lick Observatory Reticon (LOR) data presented in Hawkins et al. (1985) are reanalyzed in order to determine the cause of the significant discrepancy in (C-12)/(C-13) isotope ratios determined on the basis of observations of this isotope in the interstellar medium toward Zeta Ophiuchi and Xi Persei. A new set of Lick Observatory observations toward Zeta Oph are obtained using a CCD detector. The KPNO coude feed echelle spectrograph and a CCD detector are used to carry out high-resolution, high SNR ratio observations toward Zeta Oph and Xi Per. The LOR results for Zeta Oph are uncertain, ranging to 40 to 60, owing to the error in continuum placement. The KPNO results toward Zeta Oph are (C-12)H/(C-13)H(+)(0, 0) = 63 +/- 8, (C-12)H(+)/(C-13)H(+)(1, 0) = 67 +/- 19, and (C-12)N/(C-13)N = 100 + 88/- 33. Toward Xi Per, the KPNO measurements yield (C-12)H(+)/(C-13)H(+) = 49 +/- 15 from the 4232-A band, and a lower limit of 45 from the 3957-A observations.

  20. Uncertainties of fluxes and 13C / 12C ratios of atmospheric reactive-gas emissions

    NASA Astrophysics Data System (ADS)

    Gromov, Sergey; Brenninkmeijer, Carl A. M.; Jöckel, Patrick

    2017-07-01

    We provide a comprehensive review of the proxy data on the 13C / 12C ratios and uncertainties of emissions of reactive carbonaceous compounds into the atmosphere, with a focus on CO sources. Based on an evaluated set-up of the EMAC model, we derive the isotope-resolved data set of its emission inventory for the 1997-2005 period. Additionally, we revisit the calculus required for the correct derivation of uncertainties associated with isotope ratios of emission fluxes. The resulting δ13C of overall surface CO emission in 2000 of -(25. 2 ± 0. 7) ‰ is in line with previous bottom-up estimates and is less uncertain by a factor of 2. In contrast to this, we find that uncertainties of the respective inverse modelling estimates may be substantially larger due to the correlated nature of their derivation. We reckon the δ13C values of surface emissions of higher hydrocarbons to be within -24 to -27 ‰ (uncertainty typically below ±1 ‰), with an exception of isoprene and methanol emissions being close to -30 and -60 ‰, respectively. The isotope signature of ethane surface emission coincides with earlier estimates, but integrates very different source inputs. δ13C values are reported relative to V-PDB.

  1. α-particle elastic scattering from 12C, 16O, 24Mg, and 28Si

    NASA Astrophysics Data System (ADS)

    Behairy, Kassem O.; Mahmoud, Zakaria M. M.; Anwar, M.

    2017-01-01

    The elastic scattering of α-particle is analyzed in terms of the optical model over the energy 104-172.2 MeV for 12C, 48.7-146 MeV for 16O, 50-119 MeV for 24Mg, and 104, 166, 120 and 240 MeV for 28Si. We generate the real part of the optical model potential using the single folding model. In the single folding procedure, the ground state density of the target is folded with an effective density dependent α-nucleon interaction. For the imaginary part, the usual Woods-Saxon form is used. The parameters of the effective density dependent α-nucleon interaction are determined by fitting the experimental data of elastic scattering. The effective interaction's parameters are optimized using the χ2 criterion. We reasonably reproduce the elastic scattering cross sections for all studied systems. The obtained results reflect the success of our obtained α-nucleon effective interaction.

  2. Surface albedo of cometary nucleus

    NASA Astrophysics Data System (ADS)

    Mukai, T.; Mukai, S.

    A variation of the albedo on the illuminated disk of a comet nucleus is estimated, taking into account the multiple reflection of incident light due to small scale roughness. The dependences of the average albedo over the illuminated disk on the degree of roughness and on the complex refractive index of the surface materials are examined. The variation estimates are compared with measurements of the nucleus albedo of Comet Halley (Reitsema et al., 1987).

  3. Studies on quinazolines. 5. 2,3-dihydroimidazo[1,2-c]quinazoline derivatives: a novel class of potent and selective alpha 1-adrenoceptor antagonists and antihypertensive agents.

    PubMed

    Chern, J W; Tao, P L; Yen, M H; Lu, G Y; Shiau, C Y; Lai, Y J; Chien, S L; Chan, C H

    1993-07-23

    A series of 2-[(substituted phenylpiperazin-1-yl)methyl]- and 2-[(substituted phenylpiperidin-1-yl)methyl]-2,3-dihydroimidazo[1,2- c]quinazolin-5(6H)-ones or -5(6H)-thiones, and 3-[(substituted phenylpiperazin-1-yl)methyl]-2,3-dihydroimidazo[1,2-c]quinaz oline derivatives were synthesized, as conformationally restricted analogues of SGB-1534 and ketanserin, for evaluation as alpha-antagonists and antihypertensive agents. Most compounds containing a (substituted phenylipiperazinyl)methyl side chain displayed high binding affinity for alpha 1-adrenoceptor with no significant activity at alpha 2-sites. Compounds having a (substituted phenylpiperazinyl)methyl at the 3-position of 2,3-dihydroimidazo[1,2-c]quinazolin-5(6H)-one ring system had a better activity than those with the same substituent at the 2-position. Structure-activity relationships for alpha 1-adrenoceptor affinity are presented and indicate that compounds with substitution at the ortho position on the benzene ring of the phenylpiperazine side chain moiety are more potent than those without substitution and/or substitutions at the 3- and 4-positions. Computer-assisted superimposition of SGB-1534 and 20b showed little structural correspondence between the quinazolinone and 2,3-dihydroimidazo[1,2-c]quinazoline nucleus, and specific interactions of these molecular fragments with the receptor protein appear unlikely. Antihypertensive activity was evaluated via intravenous administration of each compound to spontaneously hypertensive rats, and compounds (16a, 16b, 20b, and 28b) illustrated similar efficacy to SGB-1534 when assessed after 6 h. The pA2 value for 16a against phenylephedrine in rat aorta was much higher than that of prazosin. On the basis of alpha 1-adrenoceptor affinity/selectivity in vitro and duration of antihypertensive action in vivo, compounds 20b and 28b warrant further evaluation.

  4. Sensitivity of cross sections for elastic nucleus-nucleus scattering to halo nucleus density distributions

    SciTech Connect

    Alkhazov, G. D.; Sarantsev, V. V.

    2012-12-15

    In order to clear up the sensitivity of the nucleus-nucleus scattering to the nuclear matter distributions in exotic halo nuclei, we have calculated differential cross sections for elastic scattering of the {sup 6}He and {sup 11}Li nuclei on several nuclear targets at the energy of 0.8 GeV/nucleon with different assumed nuclear density distributions in {sup 6}He and {sup 11}Li.

  5. Activation measurements of 13C+12C fusion cross section at deep sub-barrier energies in IFIN-HH

    NASA Astrophysics Data System (ADS)

    Tudor, D.; Chilug, A. I.; Stefanescu, I. C.; Straticiuc, M.; Burducea, I.; Trache, L.; Focsa, I. M.; Ghita, D. G.; Margineanu, R.; Pantelica, A.; Gomoiu, C.; Zhang, N. T.; Tang, X.; Chen, H.

    2017-06-01

    Heavy-ion fusion reactions between light nuclei such as carbon and oxygen isotopes have been studied because of their significance for a wide variety of stellar burning scenarios [1]. One important stellar reaction is 12C+12C, but it is difficult to measure in the Gamow window because of very low cross sections and several resonances occurring [2]. Hints can be obtained from the study of 13C+12C reaction. We studied 13C+12C fusion trough an activation method for energies from Ec.m.= 2.2 MeV, which is the lowest energy ever reached for this reaction (down into Gamow window), up to 5.3 MeV, using 13C beams from the Bucharest 3 MV Tandetron on thick graphite targets. Thick target yield for the 12C(13C, p)24Na reaction was determined through the measurement of the gamma ray yield following the beta decay of 24Na (T1/2=15 h) in our low and ultralow background laboratories, the latter located in a salt mine about 100 km north of Bucharest. Results of the experiments are shown.

  6. Strong multistep interference effects in 12C(d ,p ) to the 9 /21+ state in 13C

    NASA Astrophysics Data System (ADS)

    Keeley, N.; Kemper, K. W.; Rusek, K.

    2015-11-01

    The population of the 9.50 MeV 9 /21+ resonance in 13C by single-neutron transfer reactions is expected to be dominated by the two-step route through the 12C 21+ (4.44 MeV) state, with another possible contribution via the strongly excited 31- (9.64 MeV) resonance in 12C. However, we find that a good description of the angular distribution for population of this state via the 12C(d ,p )13C reaction is only possible when both direct 01+⊗g9 /2 and two-step (via the 4.44 MeV 12C 21+ state) 21+⊗d5 /2 paths are included in a coupled reaction channel calculation. While the calculated angular distribution is almost insensitive to the presence of the two-step path via the 9.64 MeV 12C 31- resonance, despite a much greater contribution to the wave function from the 31-⊗f7 /2 configuration, its inclusion is required to fit the details of the experimental angular distribution. The very large interference between the various components of the calculations, even when these are small, arises through the "kinematic" effect associated with the different transfer routes.

  7. The 12C(α ,γ )16O reaction and its implications for stellar helium burning

    NASA Astrophysics Data System (ADS)

    deBoer, R. J.; Görres, J.; Wiescher, M.; Azuma, R. E.; Best, A.; Brune, C. R.; Fields, C. E.; Jones, S.; Pignatari, M.; Sayre, D.; Smith, K.; Timmes, F. X.; Uberseder, E.

    2017-07-01

    The creation of carbon and oxygen in our Universe is one of the forefront questions in nuclear astrophysics. The determination of the abundance of these elements is key to our understanding of both the formation of life on Earth and to the life cycles of stars. While nearly all models of different nucleosynthesis environments are affected by the production of carbon and oxygen, a key ingredient, the precise determination of the reaction rate of 12C(α ,γ )16O, has long remained elusive. This is owed to the reaction's inaccessibility, both experimentally and theoretically. Nuclear theory has struggled to calculate this reaction rate because the cross section is produced through different underlying nuclear mechanisms. Isospin selection rules suppress the E 1 component of the ground state cross section, creating a unique situation where the E 1 and E 2 contributions are of nearly equal amplitudes. Experimentally there have also been great challenges. Measurements have been pushed to the limits of state-of-the-art techniques, often developed for just these measurements. The data have been plagued by uncharacterized uncertainties, often the result of the novel measurement techniques that have made the different results challenging to reconcile. However, the situation has markedly improved in recent years, and the desired level of uncertainty ≈10 % may be in sight. In this review the current understanding of this critical reaction is summarized. The emphasis is placed primarily on the experimental work and interpretation of the reaction data, but discussions of the theory and astrophysics are also pursued. The main goal is to summarize and clarify the current understanding of the reaction and then point the way forward to an improved determination of the reaction rate.

  8. 13C/12C isotope ratio MS analysis of testosterone, in chemicals and pharmaceutical preparations.

    PubMed

    de la Torre, X; González, J C; Pichini, S; Pascual, J A; Segura, J

    2001-02-01

    The 13C/12C ratio can be used to detect testosterone misuse in sport because (semi)-synthetic testosterone is supposed to have a 13C abundance different from that of endogenous natural human testosterone. In this study, gas chromatography/combustion isotope ratio mass spectrometry (GC/C/IRMS) analysis for the measurement of the delta 13C/1000 value of testosterone from esterified forms of 13 pharmaceutical preparations, six reagent grade chemicals and three bulk materials (raw materials used in pharmaceutical proarations) obtained world-wide was investigated after applying a strong acidic solvolytic procedure. Mean delta 13C/1000 values of non esterified (free) testosterone from chemicals and bulk materials of several testosterone esters were in the range: -25.91/-32.82/1000 while the value obtained for a (semi)-synthetic, reagent grade, free testosterone was -27.36/1000. The delta 13C/1000 results obtained for testosterone from the pharmaceuticals investigated containing testosterone esters were quite homogeneous (mean and S.D. of delta 13C/1000 values of free testosterone: 27.43 +/- 0.76/1000), being the range between -26.18 and -30.04/1000. Values described above were clearly different from those reported by several authors for endogenous natural human testosterone and its main metabolites excreted into the urine in non-consumers of testosterone (delta 13C/1000 range: from -21.3 to -24.4/1000), while they were similar to those of urinary testosterone and metabolites from individuals treated with testosterone esters and testosterone precursors. This finding justifies the fact that administration of these pharmaceutical formulations led to a statistical decrease of carbon isotope ratio of urinary testosterone and its main metabolites in treated subjects.

  9. Biosphere model simulations of interannual variability in terrestrial 13C/12C exchange

    NASA Astrophysics Data System (ADS)

    van der Velde, I. R.; Miller, J. B.; Schaefer, K.; Masarie, K. A.; Denning, S.; White, J. W. C.; Tans, P. P.; Krol, M. C.; Peters, W.

    2013-09-01

    Previous studies suggest that a large part of the variability in the atmospheric ratio of 13CO2/12CO2originates from carbon exchange with the terrestrial biosphere rather than with the oceans. Since this variability is used to quantitatively partition the total carbon sink, we here investigate the contribution of interannual variability (IAV) in biospheric exchange to the observed atmospheric 13C variations. We use the Simple Biosphere - Carnegie-Ames-Stanford Approach biogeochemical model, including a detailed isotopic fractionation scheme, separate 12C and 13C biogeochemical pools, and satellite-observed fire disturbances. This model of 12CO2 and 13CO2 thus also produces return fluxes of 13CO2from its differently aged pools, contributing to the so-called disequilibrium flux. Our simulated terrestrial 13C budget closely resembles previously published model results for plant discrimination and disequilibrium fluxes and similarly suggests that variations in C3 discrimination and year-to-year variations in C3and C4 productivity are the main drivers of their IAV. But the year-to-year variability in the isotopic disequilibrium flux is much lower (1σ=±1.5 PgC ‰ yr-1) than required (±12.5 PgC ‰ yr-1) to match atmospheric observations, under the common assumption of low variability in net ocean CO2 fluxes. This contrasts with earlier published results. It is currently unclear how to increase IAV in these drivers suggesting that SiBCASA still misses processes that enhance variability in plant discrimination and relative C3/C4productivity. Alternatively, 13C budget terms other than terrestrial disequilibrium fluxes, including possibly the atmospheric growth rate, must have significantly different IAV in order to close the atmospheric 13C budget on a year-to-year basis.

  10. Investigation of the Herzberg (C1Σ+→A1Π) band system in 12C17O

    NASA Astrophysics Data System (ADS)

    Hakalla, Rafał

    2015-10-01

    The C→A (0,1), (0,2) and (0,3) rovibronic bands of the less-abundant 12C17O isotopologue are studied in high resolution using a high-accuracy dispersive optical spectroscopy in the region of 22,800-26,100 cm-1. Calibration with respect to simultaneously recorded thorium atomic lines, obtained from several overlapped orders of the spectrum in the visible range, as well as a stainless steel hollow-cathode molecular lamp with two anodes, yields an absolute accuracy of wavenumbers measurements of about 0.0025 cm-1 for the CO spectra. All 261 spectra lines of the Herzberg band system in 12C17O, up to Jmax=34, were precisely measured and rotationally analyzed. As a result, the merged rotational constants and rotational equilibrium constants for the C1Σ+ Rydberg state, as well as the band origins, the isotope shifts, the RKR turning points, Franck-Condon factors, relative intensities, and r-centroids of the C→A system in the 12C17O isotopologue were obtained. An experimental RKR potential energy curve and vibrational levels of the C1Σ+ state in 12C17O together with highly excited k3Π, c3Π, E1Π, B1Σ+ and D‧1Σ+ states lying in the region between the first dissociation limit and the ionization potential of CO were plotted. A detailed investigation of possible perturbations that should occur in the C1Σ+(υ=0) Rydberg state of less-abundant 12C17O isotopologue in the close vicinity of the k3Π(υ=1, 2) and c3Π(υ=0) states in the region 92,000 cm-1 was performed. In the A1Π, υ=3 state of 12C17O, extensive, multi-state rotational perturbations were found and analyzed. Also, a global isotopic analysis of the C1Σ+ Rydberg state was carried out in the 12C16O, 12C17O, 13C16O, 12C18O, 13C17O, and 13C18O as well as in 14C16O and 14C18O isotopologues. This analysis enabled us to determine, amongst others, the vibrational equilibrium constants in 12C17O for the C1Σ+ state, to improve these constants in the 12C16O, 13C16O, 12C18O, 13C17O, and 13C18O isotopologues and

  11. Analysis and theoretical modeling of 18O enriched carbon dioxide spectrum by CRDS near 1.35 μm: (II) 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2 and 17O13C18O

    NASA Astrophysics Data System (ADS)

    Karlovets, E. V.; Campargue, A.; Kassi, S.; Tashkun, S. A.; Perevalov, V. I.

    2017-04-01

    This contribution is the second part of the analysis of the room temperature absorption spectrum of 18O enriched carbon dioxide by very high sensitivity Cavity Ring Down spectroscopy between 6977 and 7918 cm-1 (1.43-1.26 μm). Overall, more than 8600 lines belonging to 166 bands of eleven carbon dioxide isotopologues were rovibrationnally assigned. In a first part (Kassi et al. J Quant Spectrosc Radiat Transfer 187 (2017) 414-425, http://dx.doi.org/10.1016/j.jqsrt.2016.09.002), the results relative to mono-substituted isotopologues, 16O12C18O, 16O12C17O, 12C16O2 and 13C16O2, were presented. This second contribution is devoted to the multiply-substituted isotopologues or clumped isotopologues of particular importance in geochemistry: 16O13C18O, 16O13C17O, 12C18O2, 17O12C18O, 12C17O2, 13C18O2 and 17O13C18O. On the basis of the predictions of effective Hamiltonian models, a total of 3195 transitions belonging to 73 bands were rovibrationnally assigned for these seven species. Among the 73 observed bands, 55 are newly reported. All the identified bands correspond to ΔP=10 and 11 series of transitions, where P= 2V1+V2+3V3 is the polyad number (Vi are vibrational quantum numbers). The accurate spectroscopic parameters of 70 bands have been determined from the standard band-by-band analysis. Global fits of the measured line intensities of the ΔP=10 series of transitions of 17O12C18O and 16O13C18O and of the ΔP=11 series of transitions of 12C18O2, 17O12C18O, 16O13C18O and 13C18O2 were performed to determine the corresponding sets of the effective dipole moment parameters.

  12. Influence of CYP1A1*2C on high triglyceride levels in female Mexican indigenous Tarahumaras.

    PubMed

    Bailón-Soto, Claudia E; Galaviz-Hernández, Carlos; Lazalde-Ramos, Blanca P; Hernández-Velázquez, Daniel; Salas-Pacheco, José; Lares-Assef, Ismael; Sosa-Macías, Martha

    2014-07-01

    High triglyceride levels are closely related to cardiovascular disease. Its development lays on age, diet, physical activity, ethnicity and genetic factors. Among the last, the CYP1A1*2C allele has an influence on the metabolism of cholesterol and other fatty acids. We undertook this study to determine the frequency of CYP1A1*2C and its association with triglyceride levels in Mexican indigenous Tarahumaras and Tepehuanos. Anthropometric and biochemical data were recorded. Genotyping of CYP1A1*2C by RT-PCR was done in 110 Tepehuano, 69 Tarahumara and 64 Mestizo. Significant differences in age, waist diameter, BMI, creatinine, glucose, cholesterol, triglycerides, HDL and VLDL measurements were found between Tarahumaras and Tepehuanos (p <0.05). Additionally, Tarahumara women showed the highest values of waist diameter, BMI and triglycerides (p <0.05). It was found that Tarahumaras showed a significant association between high triglyceride levels and CYP1A1*2C allele (OR = 2.57; 95% CI 1.12-5.88, p = 0.024) under a recessive inheritance model. However, the Tepehuano group showed a significant protective association between normal triglyceride levels and CYP1A1*2C polymorphism (OR = 0.28; 95% CI 0.10-0.80, p = 0.015) following a dominant inheritance model. The same pattern was observed after analysis with females of both ethnicities. A significant association between CYP1A1*2C and high triglyceride levels in Amerindian Tarahumaras from Chihuahua has been found; this allele was significantly associated with normal triglyceride levels in Tepehuanos from Durango, Mexico. Further studies are needed to elucidate the genetic role of CYP1A1 in cardiovascular disease susceptibility. Copyright © 2014 IMSS. Published by Elsevier Inc. All rights reserved.

  13. The 12C/13C Ratio in Sgr B2(N): Constraints for Galactic Chemical Evolution and Isotopic Chemistry

    NASA Astrophysics Data System (ADS)

    Halfen, D. T.; Woolf, N. J.; Ziurys, L. M.

    2017-08-01

    A study has been conducted of 12C/13C ratios in five complex molecules in the Galactic center. H2CS, CH3CCH, NH2CHO, CH2CHCN, and CH3CH2CN and their 13C-substituted species have been observed in numerous transitions at 1, 2, and 3 mm, acquired in a spectral-line survey of Sgr B2(N), conducted with the telescopes of the Arizona Radio Observatory (ARO). Between 22 and 54 individual, unblended lines for the 12C species and 2-54 for 13C-substituted analogs were modeled in a global radiative transfer analysis. All five molecules were found to consistently exhibit two velocity components near V LSR ˜ 64 and 73 km s-1, with column densities ranging from N tot ˜ 3 × 1014 - 4 × 1017 cm-2 and ˜2 × 1013 - 1 × 1017 cm-2 for the 12C and 13C species, respectively. Based on 14 different isotopic combinations, ratios were obtained in the range 12C/13C = 15 ± 5 to 33 ± 13, with an average value of 24 ± 7, based on comparison of column densities. These measurements better anchor the 12C/13C ratio at the Galactic center, and suggest a slightly revised isotope gradient of 12C/13C = 5.21(0.52) D GC + 22.6(3.3). As indicated by the column densities, no preferential 13C enrichment was found on the differing carbon sites of CH3CCH, CH2CHCN, and CH3CH2CN. Because of the elevated temperatures in Sgr B2(N), 13C isotopic substitution is effectively “scrambled,” diminishing chemical fractionation effects. The resulting ratios thus reflect stellar nucleosynthesis and Galactic chemical evolution, as is likely the case for most warm clouds.

  14. Direct measurement of the 4He (12C, 16O) γ reaction cross section near stellar energies

    NASA Astrophysics Data System (ADS)

    Sagara, Kenshi

    2014-09-01

    The 12C+4He-->16O + γ reaction is one of the key reactions in stellar He-burning, but its total cross section at stellar energy (Ecm = 0.3 MeV) has not been measured yet, in spite of many experiments made in the world for about a half century. At Kyushu University Tandem accelerator Laboratory (KUTL), we have been making direct measurement of the 4He (12C, 16O) γ total cross section below Ecm = 2.4 MeV for about 20 years. We have measured the total cross section at Ecm = 2.4, 1.5 and 1.2 MeV. Now we are preparing to measure the cross section at 1.0 MeV. The direct measurement was made from Ecm = 5 MeV down to 1.9 MeV at Ruhr University, Bochum. We use a pulsed 12C beam and a windowless 4He target, and detect all the 16O recoils in a charge state. A usually continuum 12C beam from our tandem accelerator is pulsed by a pre-buncher, a main buncher, and a beam chopper. Our tandem accelerator was designed to be used at the acceleration voltage of 6-10 MV. For the 4He (12C, 16O) γ experiment we need to use it at 1.3-1.8 MV where beam transmission is very low, then we have invented an acceleration-deceleration method for the tandem accelerator. We have developed a blow-in windowless He target based on an original idea. To separate 16O recoils from the 12C beam, we developed a recoil-mass separator. To reject 12C backgrounds, we developed a long-time chopper, and an ionization chamber. Now, we are preparing to measure time-of-flight of 16O recoils and 12C backgrounds. Many original instruments and the experimental results will be presented. Finally we discuss what are necessary for future direct measurement of the 4He (12C, 16O) γ total cross section below 1.0 MeV, down to 0.7 MeV. A dynamitron accelerator and hard-working researchers may be inevitable. The 12C+4He-->16O + γ reaction is one of the key reactions in stellar He-burning, but its total cross section at stellar energy (Ecm = 0.3 MeV) has not been measured yet, in spite of many experiments made in the world

  15. Reaction mechanism of the /sup 12/C(/sup 3/He,. cap alpha. )/sup 11/C reaction

    SciTech Connect

    Kudo, Y.

    1982-11-01

    The mechanism of the reactions /sup 12/C(/sup 3/He, ..cap alpha..)/sup 11/C leading to the (3/2)/sup -/ ground state and (5/2)/sup -/ second excited state of /sup 11/C is studied using finite-range distorted-wave Born approximation with all one-step direct and exchange processes. By taking into account in detail the cluster structure of /sup 11/C and /sup 12/C, the transition to the (5/2)/sup -/ state which is a j forbidden direct process can be explained well by the exchange process.

  16. VizieR Online Data Catalog: 12C16O lines in Arcturus IR spectrum

    NASA Astrophysics Data System (ADS)

    Tsuji T.

    2009-06-01

    Based on the Infrared Atlas of the Arcturus Spectrum by Hinkle, Wallace, and Livingston (1995, Cat. ), we measured line-depth, full-width at half-maximum (FWHM), and equivalent width (EW) of 12C16O lines including fundamental, first and second overtone bands, and the results are given in table2. We used the electronic version of the ratioed spectra in our measurement and the tabulated results are measured raw data without any correction yet. The resulting data are used to investigate the nature of the infrared spectrum of Arcturus. It is found that only the weak lines (log(W/nu)<-4.75) can be analyzed consistently on the basis of the classical line-formation theory and hence can be used to extract the nature of the photosphere: We found logAC=7.97 (on the scale of log AH=12.00), micro and macro turbulent velocities to be 1.87 and 3.47km/s, respectively, for the photosphere. The nature of CO lines, however, shows abrupt change at about log(W/nu)=-4.75: The EWs of the lines larger than this limit can no longer be accounted for by the photospheric parameters determined from the weaker lines. A more simple demonstration of this fact is that the curves-of-growth of overtone as well as of fundamental CO lines show unpredictable upturn at about log(W/nu)=-4.75. Similar unusual behaviors of empirical curves-of-growth are found in other red giant and supergiant stars, and it looks as if the curves-of-growth are composite of at least two components of different origins. We think it difficult to understand such empirical data as due to the classical photosphere alone, and infrared spectra of cool luminous stars including Arcturus should be hybrid in nature. Although strong lines of the CO fundamentals show strengthening, the weaker lines show slight weakening, and we consider a possibility that these results are due to absorption/emission by the molecular clouds formed in the extended atmosphere. In cooler giant and supergiant stars in which CO lines show

  17. Coral 13C/12C records of vertical seafloor displacement during megathrust earthquakes west of Sumatra

    NASA Astrophysics Data System (ADS)

    Gagan, Michael K.; Sosdian, Sindia M.; Scott-Gagan, Heather; Sieh, Kerry; Hantoro, Wahyoe S.; Natawidjaja, Danny H.; Briggs, Richard W.; Suwargadi, Bambang W.; Rifai, Hamdi

    2015-12-01

    The recent surge of megathrust earthquakes and tsunami disasters has highlighted the need for a comprehensive understanding of earthquake cycles along convergent plate boundaries. Space geodesy has been used to document recent crustal deformation patterns with unprecedented precision, however the production of long paleogeodetic records of vertical seafloor motion is still a major challenge. Here we show that carbon isotope ratios (δ13C) in the skeletons of massive Porites corals from west Sumatra record abrupt changes in light exposure resulting from coseismic seafloor displacements. Validation of the method is based on the coral δ13C response to uplift (and subsidence) produced by the March 2005 Mw 8.6 Nias-Simeulue earthquake, and uplift further south around Sipora Island during a M ∼ 8.4 megathrust earthquake in February 1797. At Nias, the average step-change in coral δ13C was 0.6 ± 0.1 ‰ /m for coseismic displacements of +1.8 m and -0.4 m in 2005. At Sipora, a distinct change in Porites microatoll growth morphology marks coseismic uplift of 0.7 m in 1797. In this shallow water setting, with a steep light attenuation gradient, the step-change in microatoll δ13C is 2.3 ‰ /m, nearly four times greater than for the Nias Porites. Considering the natural variability in coral skeletal δ13C, we show that the lower detection limit of the method is around 0.2 m of vertical seafloor motion. Analysis of vertical displacement for well-documented earthquakes suggests this sensitivity equates to shallow events exceeding Mw ∼ 7.2 in central megathrust and back-arc thrust fault settings. Our findings indicate that the coral 13C /12C paleogeodesy technique could be applied to convergent tectonic margins throughout the tropical western Pacific and eastern Indian oceans, which host prolific coral reefs, and some of the world's greatest earthquake catastrophes. While our focus here is the link between coral δ13C, light exposure and coseismic crustal deformation, the

  18. Fission-like events in the 12C+169Tm system at low excitation energies

    NASA Astrophysics Data System (ADS)

    Sood, Arshiya; Singh, Pushpendra P.; Sahoo, Rudra N.; Kumar, Pawan; Yadav, Abhishek; Sharma, Vijay R.; Shuaib, Mohd.; Sharma, Manoj K.; Singh, Devendra P.; Gupta, Unnati; Kumar, R.; Aydin, S.; Singh, B. P.; Wollersheim, H. J.; Prasad, R.

    2017-07-01

    Background: Fission has been found to be a dominating mode of deexcitation in heavy-ion induced reactions at high excitation energies. The phenomenon of heavy-ion induced fission has been extensively investigated with highly fissile actinide nuclei, yet there is a dearth of comprehensive understanding of underlying dynamics, particularly in the below actinide region and at low excitation energies. Purpose: Prime objective of this work is to study different aspects of heavy-ion induced fission ensuing from the evolution of composite system formed via complete and/or incomplete fusion in the 12C+169Tm system at low incident energies, i.e., Elab≈6.4 , 6.9, and 7.4 A MeV, as well as to understand charge and mass distributions of fission fragments. Method: The recoil-catcher activation technique followed by offline γ spectroscopy was used to measure production cross sections of fission-like events. The evaporation residues were identified by their characteristic γ rays and vetted by the decay-curve analysis. Charge and mass distributions of fission-like events were studied to obtain dispersion parameters of fission fragments. Results: In the present work, 26 fission-like events (32 ≤Z ≤49 ) were identified at different excitation energies. The mass distribution of fission fragments is found to be broad and symmetric, manifesting their production via compound nuclear processes. The dispersion parameters of fission fragments obtained from the analysis of mass and isotopic yield distributions are found to be in good accord with the reported values obtained for different fissioning systems. A self-consistent approach was employed to determine the isobaric yield distribution. Conclusions: The present work suggests that fission is one of the competing modes of deexcitation of complete and/or incomplete fusion composites at low excitation energies, i.e., E*≈57 , 63, and 69 MeV, where evaporation of light nuclear particle(s) and/or γ rays are assumed to be the sole

  19. LED-based Fourier transform spectroscopy of 16O12C18O and 12C18O2 in the 11,260-11,430 cm-1 range

    NASA Astrophysics Data System (ADS)

    Serdyukov, V. I.; Sinitsa, L. N.; Lugovskoi, A. A.; Borkov, Yu. G.; Tashkun, S. A.; Perevalov, V. I.

    2016-07-01

    The absorption spectrum of the 16O12C18O and 12C18O2 carbon dioxide isotopologues has been recorded in the 11,260- 11,430 cm-1 spectral range using Bruker IFS 125 HR Fourier transform spectrometer with resolution 0.05 cm-1 at temperature 297 K and path length 24 m. The 18O enriched sample of carbon dioxide at total pressure 96.5 mbar was used for these purposes. The spectrometer used LED emitter as a light source. This gave possibility to reach the minimal detectable absorption coefficient αmin~1.4×10-7 cm-1 using 23,328 scans. In the recorded spectrum we have assigned the 00051-00001 band for both 16O12C18O and 12C18O2 isotopologues using the predictions performed within the framework of the method of effective operators. The line positions and intensities of the observed bands are found. The comparison of the observed and predicted line positions and intensities is performed confirming good accuracy of the predictions. The spectroscopic parameters for the observed bands are determined.

  20. Resonant and average behavior of the /sup 12/C+/sup 12/C total reaction cross section: 5. 6 < or = E/sub c. m. / < or = 10. 0 MeV

    SciTech Connect

    Erb, K.A.; Betts, R.R.; Korotky, S.K.; Hindi, M.M.; Tung, P.P.; Sachs, M.W.; Willett, S.J.; Bromley, D.A.

    1980-08-01

    The gamma-radiation yields from the /sup 12/C+/sup 12/C interaction were measured in steps of 50 keV over the bombarding energy range 11.8 < or = E/sub lab/ < or = 20 MeV in order to study the energy dependence of the total reaction cross section. Several new resonances, occurring at E/sub c.m./=6.49, 7.30, 7.45, 9.33, and 9.67 MeV, were identified in these yields. Carbon partial widths were determined for a number of resonances, and these widths demonstrate the quasimolecular nature of the corresponding structures. The average or background trend of the energy dependence of the reaction cross section was found to be adequately described by an incoming-waves boundary condition model, however, and no evidence was found in the energy-averaged yields for anomalous absorption in the /sup 12/C+/sup 12/C system.

  1. Formin' actin in the nucleus.

    PubMed

    Baarlink, Christian; Grosse, Robert

    2014-01-01

    Many if not most proteins can, under certain conditions, change cellular compartments, such as, for example, shuttling from the cytoplasm to the nucleus. Thus, many proteins may exert functions in various and very different subcellular locations, depending on the signaling context. A large amount of actin regulatory proteins has been detected in the mammalian cell nucleus, although their potential roles are much debated and are just beginning to emerge. Recently, members of the formin family of actin nucleators were also reported to dynamically localize to the nuclear environment. Here we discuss our findings that specific diaphanous-related formins can promote nuclear actin assembly in a signal-dependent manner.

  2. Functionalized active-nucleus complex sensor

    DOEpatents

    Pines, Alexander; Wemmer, David E.; Spence, Megan; Rubin, Seth

    2003-11-25

    A functionalized active-nucleus complex sensor that selectively associates with one or more target species, and a method for assaying and screening for one or a plurality of target species utilizing one or a plurality of functionalized active-nucleus complexes with at least two of the functionalized active-nucleus complexes having an attraction affinity to different corresponding target species. The functionalized active-nucleus complex has an active-nucleus and a targeting carrier. The method involves functionalizing an active-nucleus, for each functionalized active-nucleus complex, by incorporating the active-nucleus into a macromolucular or molecular complex that is capable of binding one of the target species and then bringing the macromolecular or molecular complexes into contact with the target species and detecting the occurrence of or change in a nuclear magnetic resonance signal from each of the active-nuclei in each of the functionalized active-nucleus complexes.

  3. Comment on 'Low-energy cross sections in the {sup 12}C({alpha},{gamma}){sup 16}O reaction'

    SciTech Connect

    Descouvemont, P.; Dufour, M.

    2010-02-15

    We show that the E1 and E2 S factors recommended by Katsuma [Phys. Rev. C 78, 034606 (2008)] do not include well-known constraints and that the model is inappropriate for the {sup 12}C({alpha},{gamma}){sup 16}O reaction.

  4. Enhancement of fusion at near-barrier energies for neutron-rich light nuclei: 19O +12 C

    NASA Astrophysics Data System (ADS)

    Singh, Varinderjit; Vadas, J.; Steinbach, T. K.; Wiggins, B. B.; Hudan, S.; Desouza, R. T.; Baby, L. T.; Kuvin, S. A.; Tripathi, Vandana; Wiedenhover, I.; Umar, A. S.

    2017-01-01

    Measuring the fusion excitation function for an isotopic chain of projectile nuclei provides a sensitive test of a microscopic description of fusion. To investigate the theoretically predicted fusion enhancement for neutron-rich light nuclei, an experiment was performed to measure the fusion excitation functions for 19 O +12 C and 18 O +12 C . Using the 18O(d,p) reaction and the RESOLUT mass spectrometer at Florida State University, a beam of 19O was produced with an intensity of 2-4 x 103 p/s. This beam bombarded a 100 μg/cm2 carbon target. Using an approach optimized for the measurement of fusion with a low-intensity beam, evaporation residues (ERs) resulting from the de-excitation of the fusion product were measured. The ERs were identified by measuring their energy and time-of-flight. At near-barrier energies, an enhancement of fusion by a factor of three has been observed for 19 O +12 C in comparison to 18 O +12 C . Comparison of the experimental results with the predictions of a density constrained time-dependent Hartree-Fock (DC-TDHF) model provide evidence for the importance of pairing in the fusion process. Supported by the US DOE under Grant No. DEFG02-88ER-40404.

  5. The structure of the Hoyle state via a measurement of the 'Hoyle Rotational Band' in 12C

    NASA Astrophysics Data System (ADS)

    Gai, M.; UConn-Yale-TUNL-Weizmann-PTB-UCL Collaboration

    2013-04-01

    We have measured the 12C(γ, 3α) reaction with an Optical Time Projection Chamber (O-TPC) detector operating with the CO2(80%) + N2(20%) gas mixture and gamma-ray beams from the HIγS facility of the TUNL at Duke. We measured complete angular distributions (between 9.1 - 10.7 MeV) from which we determine the cross section yield curve and E1-E2 relative phases leading to an unambiguous identification of the second 2+ state in 12C at 10.03(11) MeV. The observed spectrum of 12C below 12 MeV including the 2+2 observed in this work resembles the rotation-vibration spectrum predicted for a triangular shape oblate spinning top in which the Hoyle state is the first vibrational breathing mode of the triangular three alpha particle system. The predicted rotation-vibration spectrum of a triangular shape oblate spinning top (with a D3h symmetry) allows us to compare the moment of inertia of the predicted Hoyle rotational band to the ground state rotational band and in this way extract the model radius parameter of the Hoyle state of 3.22(8) fm ( time the r.m.s. radius of the ground state) which is close to the radius extracted from 12C(x,x') data.

  6. Scattering of 14.7 MeV neutrons from 12C and evidence for a new reaction channel

    NASA Astrophysics Data System (ADS)

    Gul, K.; Anwar, M.; Ahmad, M.; Saleem, S. M.; Khan, Naeem A.

    1981-12-01

    Measurements of neutron scattering from carbon have been carried out for 14.7 MeV neutrons using associated particle and time-of-flight techniques. Angular distributions for the ground state, 4.43, and 7.65 MeV states have been measured in the laboratory angular range 30-130° and for the 9.63 MeV state in the range 30-70°. Double differential scattering cross sections have been obtained in the energy range 3-14 MeV. Monte Carlo simulation has been used to correct for multiple scattering including scattered flux attenuation. The integrated cross sections for 4.43 and 7.65 MeV states have been obtained as 214+/-8 and 9.3+/-1.6 mb, respectively. The present data have been compared with the published data. Evidence for a 12C(n,α)9Be reaction populating the 6.76 MeV state and subsequently decaying by emission of a neutron has been observed for the first time. The presence of a neutron group of 5.6 MeV energy at backward angles has been discussed. NUCLEAR REACTIONS 12C(n,n), 12C(n,n'), 12C(n,αn), E=14.7 MeV; measured σ(E,θ), double differential scattering cross sections, integrated cross sections, natural target.

  7. Measurement of 13C/12C of chloroacetic acids by gas chromatography/combustion/isotope ratio mass spectrometry.

    PubMed

    Wong, Charles S; Muir, Derek C G; Mabury, Scott A

    2003-02-01

    This paper describes a novel analytical methodology using gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) to measure the 13C/12C ratios of chloroacetic acids (CAAs). CAAs are a major class of environmental pollutants that are widely distributed throughout the world, often at relatively high concentrations, and are of concern due to their toxic effects, particularly on plants. The 13C/12C of CAA reagents was measured by IRMS subsequent to offline combustion. Aqueous solutions of these CAAs were derivatized to the corresponding methyl chloroacetates (MCAAs) with acidic methanol with a known isotopic composition, extracted into pentane, and analyzed by GC/C/IRMS. Measured 13C/12C ratios of derivatized MCAAs were in agreement with calculated values within 1 per thousand for monochloroacetic acid and trichloroacetic acid and within 2 per thousand for dichloroacetic acid, suggesting that methylation and other analytical methodology steps do not isotopically fractionate derivatized MCAAs. 13C/12C ratios of reagent CAAs from different sources had varying isotopic signatures suggesting differences in source carbon and/or production methods. Our results underscore the potential of stable isotopes to serve as tracers of environmental sources of CAAs.

  8. Low energy antiproton nucleus interactions

    SciTech Connect

    Sainio, M.E.; Ashford, V.; Sakitt, M.; Skelly, J.; Debbe, R.; Fickinger, W.; Marino, R.; Robinson, D.K.

    1984-05-01

    We have studied antiproton quasielastic scattering on Al, Cu, and Pb for two incident momenta, 514 and 633 MeV/c. Combining these data with other existing anti p nucleus data, we have performed a global analysis using a nonrelativistic optical potential of the Woods-Saxon form.

  9. Comet Odyssey: Comet Nucleus Orbiter

    NASA Astrophysics Data System (ADS)

    Weissman, P. R.; Smythe, W. D.; Spitz, S. J.; Bernard, D. E.; Bailey, R. W.

    2004-11-01

    Comet Odyssey is a comet nucleus orbiter mission, proposed to NASA's Discovery program in 2004. The goal of the mission is to completely characterize a cometary nucleus, both physically and compositionally, as can only be done during an extended rendezvous and not with a fast flyby. Comet Odyssey will launch in October 2009 on a Delta II 7925 and use a solar-electric powered spacecraft to effect a rendezvous with periodic comet 46P/Wirtanen in October 2013. Arrival is 96 days after perihelion at a heliocentric distance of 1.61 AU. Comet Odyssey's science payload includes narrow- and wide-angle CCD cameras, an infrared thermal imager, a gas chromatograph/mass spectrometer, an XRD/XRF dust compositional analyzer, and a dust counter and accumulation sensors. The Comet Odyssey spacecraft implementation uses a high heritage approach of flight proven and redundant hardware. The 3-engine ion propulsion subsystem is derived from that on Dawn but includes the capability for multi-engine thrusting. Comet Odyssey will approach the Wirtanen nucleus and make repeated slow flybys through the active cometary coma for a period of three months. It will then be placed in a ˜100-km radius orbit around the nucleus, with a plan to eventually orbit at 40-km altitude or less. From that altitude the narrow-angle camera will map the entire nucleus surface at 1 meter/pixel and the thermal imager will map at 19 meter/pixel. The orbital portion of the nominal mission will last 4.5 months, following the comet outward from the Sun to 3.3 AU as the comet evolves from an active to a quiescent state. En route to P/Wirtanen, the Comet Odyssey spacecraft will perform a close flyby of the 200-km diameter, G-type, main belt asteroid 19 Fortuna in January 2012 and make appropriate remote sensing observations.

  10. Higgs and Particle Production in Nucleus-Nucleus Collisions

    NASA Astrophysics Data System (ADS)

    Liu, Zhe

    We apply a diagrammatic approach to study Higgs boson, a color-neutral heavy particle, pro- duction in nucleus-nucleus collisions in the saturation framework without quantum evolution. We assume the strong coupling constant much smaller than one. Due to the heavy mass and colorless nature of Higgs particle, final state interactions are absent in our calculation. In order to treat the two nuclei dynamically symmetric, we use the Coulomb gauge which gives the appropriate light cone gauge for each nucleus. To further eliminate initial state interactions we choose specific prescriptions in the light cone propagators. We start the calculation from only two nucleons in each nucleus and then demonstrate how to generalize the calculation to higher orders diagrammatically. We simplify the diagrams by the Slavnov-Taylor-Ward identities. The resulting cross section is factorized into a product of two Weizsacker-Williams gluon distributions of the two nuclei when the transverse momentum of the produced scalar particle is around the saturation momentum. To our knowledge this is the first process where an exact analytic formula has been formed for a physical process, involving momenta on the order of the saturation momentum, in nucleus-nucleus collisions in the quasi-classical approximation. Since we have performed the calculation in an unconventional gauge choice, we further confirm our results in Feynman gauge where the Weizsacker-Williams gluon distribution is interpreted as a transverse momentum broadening of a hard gluons traversing a nuclear medium. The transverse momentum factorization manifests itself in light cone gauge but not so clearly in Feynman gauge. In saturation physics there are two different unintegrated gluon distributions usually encountered in the literature: the Weizsacker-Williams gluon distribution and the dipole gluon distribution. The first gluon distribution is constructed by solving classical Yang-Mills equation of motion in the Mc

  11. RCNP E398 {sup 16}O,{sup 12}C(p,p’) experiment: Measurement of the γ-ray emission probability from giant resonances in relation to {sup 16}O,{sup 12}C(ν,ν’) reactions

    SciTech Connect

    Ou, I.; Yamada, Y.; Mori, T.; Yano, T.; Sakuda, M.; Tamii, A.; Suzuki, T.; Yosoi, M.; Aoi, N.; Ideguchi, E.; Hashimoto, T.; Miki, K.; Ito, T.; Iwamoto, C.; Yamamoto, T.; Akimune, H.

    2015-05-15

    We propose to measure the γ-ray emission probability from excited states above 5 MeV including giant resonance of {sup 16}O and {sup 12}C as a function of excitation energy in 1-MeV step. Here, we measure both the excitation energy (E{sub x}=5-30MeV) at the forward scattering angles (0°-3°) of the {sup 16}O, {sup 12}C (p, p’) reaction using Grand-Raiden Spectrometer and the energy of γ-rays (E{sub γ}) using an array of NaI(Tl) counters. The purpose of the experiment is to provide the basic and important information not only for the γ-ray production from primary neutral-current neutrino-oxygen (-carbon) interactions but also for that from the secondary hadronic (neutron-oxygen and -carbon) interactions.

  12. Single nucleon emission in relativistic nucleus-nucleus reactions

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Townsend, Lawrence W.

    1992-01-01

    Significant discrepancies between theory and experiment have previously been noted for nucleon emission via electromagnetic processes in relativistic nucleus-nucleus collisions. The present work investigates the hypothesis that these discrepancies have arisen due to uncertainties about how to deduce the experimental electromagnetic cross section from the total measured cross section. An optical-model calculation of single neutron removal is added to electromagnetic cross sections and compared to the total experimental cross sections. Good agreement is found thereby resolving some of the earlier noted discrepancies. A detailed comparison to the recent work of Benesh, Cook, and Vary is made for both the impact parameter and the nuclear cross section. Good agreement is obtained giving an independent confirmation of the parameterized formulas developed by those authors.

  13. Dynamical nucleus-nucleus potential at short distances

    SciTech Connect

    Jiang Yongying; Wang Ning; Li Zhuxia; Scheid, Werner

    2010-04-15

    The dynamical nucleus-nucleus potentials for fusion reactions {sup 40}Ca+{sup 40}Ca, {sup 48}Ca+{sup 208}Pb, and {sup 126}Sn+{sup 130}Te are studied with the improved quantum molecular dynamics model together with the extended Thomas-Fermi approximation for the kinetic energies of nuclei. The obtained fusion barrier for {sup 40}Ca+{sup 40}Ca is in good agreement with the extracted fusion barrier from the measured fusion excitation function, and the depths of the fusion pockets are close to the results of time-dependent Hartree-Fock calculations. The energy dependence of the fusion barrier is also investigated. The fusion pocket becomes shallow for a heavy fusion system and almost disappears for heavy nearly symmetric systems, and the obtained potential at short distances is higher than the adiabatic potential.

  14. Azimuthal correlation and collective behavior in nucleus-nucleus collisions

    SciTech Connect

    Mali, P.; Mukhopadhyay, A. Sarkar, S.; Singh, G.

    2015-03-15

    Various flow effects of nuclear and hadronic origin are investigated in nucleus-nucleus collisions. Nuclear emulsion data collected from {sup 84}Kr + Ag/Br interaction at an incident energy of 1.52 GeV per nucleon and from {sup 28}Si + Ag/Br interaction at an incident energy of 14.5 GeV per nucleon are used in the investigation. The transverse momentum distribution and the flow angle analysis show that collective behavior, like a bounce-off effect of the projectile spectators and a sidesplash effect of the target spectators, are present in our event samples. From an azimuthal angle analysis of the data we also see a direct flow of the projectile fragments and of the produced charged particles. On the other hand, for both data samples the target fragments exhibit a reverse flow, while the projectile fragments exhibit an elliptic flow. Relevant flow parameters are measured.

  15. Analysis of relativistic nucleus-nucleus interactions in emulsion chambers

    NASA Technical Reports Server (NTRS)

    Mcguire, Stephen C.

    1987-01-01

    The development of a computer-assisted method is reported for the determination of the angular distribution data for secondary particles produced in relativistic nucleus-nucleus collisions in emulsions. The method is applied to emulsion detectors that were placed in a constant, uniform magnetic field and exposed to beams of 60 and 200 GeV/nucleon O-16 ions at the Super Proton Synchrotron (SPS) of the European Center for Nuclear Research (CERN). Linear regression analysis is used to determine the azimuthal and polar emission angles from measured track coordinate data. The software, written in BASIC, is designed to be machine independent, and adaptable to an automated system for acquiring the track coordinates. The fitting algorithm is deterministic, and takes into account the experimental uncertainty in the measured points. Further, a procedure for using the track data to estimate the linear momenta of the charged particles observed in the detectors is included.

  16. Effect of surface energy constant and surface asymmetry constant in the charged particle emission cross-section for the reactions $ (78,82,86) Kr +(12) C $ 78 , 82 , 86 K r + 12 C

    NASA Astrophysics Data System (ADS)

    Nazarzadeh, P.; Davoodabadi, S.

    2016-12-01

    The effects of the surface energy constant and the surface asymmetry constant in the charged particle emission cross section, have been examined by using the proximity potentials Prox77, BW91, AW95. The charged particle emission cross-section for the reactions ^{78,82,86} Kr +^{12} C have been calculated. Good consistency between the results of this work and the experimental data have been obtained using appropriate values of these constants.

  17. Neutrino-nucleus reactions based on recent structure studies

    SciTech Connect

    Suzuki, Toshio

    2015-05-15

    Neutrino-nucleus reactions are studied with the use of new shell model Hamiltonians, which have proper tensor components in the interactions and prove to be successful in the description of Gamow-Teller (GT) strengths in nuclei. The new Hamiltonians are applied to obtain new neutrino-nucleus reaction cross sections in {sup 12}C, {sup 13}C, {sup 56}Fe and {sup 56}Ni induced by solar and supernova neutrinos. The element synthesis by neutrino processes in supernova explosions is discussed with the new cross sections. The enhancement of the production yields of {sup 7}Li, {sup 11}B and {sup 55}Mn is obtained while fragmented GT strength in {sup 56}Ni with two-peak structure is found to result in smaller e-capture rates at stellar environments. The monopole-based universal interaction with tensor force of π+ρ meson exchanges is used to evaluate GT strength in {sup 40}Ar and ν-induced reactions on {sup 40}Ar. It is found to reproduce well the experimental GT strength in {sup 40}Ar.

  18. Changes in vegetation phenology are not reflected in atmospheric CO2 and (13) C/(12) C seasonality.

    PubMed

    Gonsamo, Alemu; D'Odorico, Petra; Chen, Jing M; Wu, Chaoyang; Buchmann, Nina

    2017-10-01

    Northern terrestrial ecosystems have shown global warming-induced advances in start, delays in end, and thus increased lengths of growing season and gross photosynthesis in recent decades. The tradeoffs between seasonal dynamics of two opposing fluxes, CO2 uptake through photosynthesis and release through respiration, determine the influence of the terrestrial ecosystem on the atmospheric CO2 and (13) C/(12) C seasonality. Here, we use four CO2 observation stations in the Northern Hemisphere, namely Alert, La Jolla, Point Barrow, and Mauna Loa Observatory, to determine how changes in vegetation productivity and phenology, respiration, and air temperature affect both the atmospheric CO2 and (13) C/(12) C seasonality. Since the 1960s, the only significant long-term trend of CO2 and (13) C/(12) C seasonality was observed at the northern most station, Alert, where the spring CO2 drawdown dates advanced by 0.65 ± 0.55 days yr(-1) , contributing to a nonsignificant increase in length of the CO2 uptake period (0.74 ± 0.67 days yr(-1) ). For Point Barrow station, vegetation phenology changes in well-watered ecosystems such as the Canadian and western Siberian wetlands contributed the most to (13) C/(12) C seasonality while the CO2 seasonality was primarily linked to nontree vegetation. Our results indicate significant increase in the Northern Hemisphere soil respiration. This means, increased respiration of (13) C depleted plant materials cancels out the (12) C gain from enhanced vegetation activities during the start and end of growing season. These findings suggest therefore that parallel warming-induced increases both in photosynthesis and respiration contribute to the long-term stability of CO2 and (13) C/(12) C seasonality under changing climate and vegetation activity. The summer photosynthesis and the soil respiration in the dormant seasons have become more vigorous which lead to increased peak-to-through CO2 amplitude. As the relative magnitude of the

  19. Formation of a necklike structure in 35Cl+12C and 197Au reactions at 43 MeV/nucleon

    NASA Astrophysics Data System (ADS)

    Larochelle, Y.; Gingras, L.; Beaulieu, L.; Qian, X.; Saddiki, Z.; Djerroud, B.; Doré, D.; Laforest, R.; Roy, R.; Samri, M.; St-Pierre, C.; Ball, G. C.; Bowman, D. R.; Galindo-Uribarri, A.; Hagberg, E.; Horn, D.; López, J. A.; Robinson, T.

    1997-04-01

    The experimental signature of the formation of a necklike structure, with a velocity between that of the projectilelike emitter and that of the targetlike emitter, is investigated with the same beam and experimental setup for targets lighter and heavier than the projectile. The reactions are 35Cl on 12C and on 197Au at 43 MeV/nucleon. Particle velocity distributions are compared with two-source statistical simulations and the presence of a necklike structure is inferred from the data. In the second part of the paper, dynamical model simulations with the formation of a necklike structure are presented for the 35Cl+12C system at 43 MeV/nucleon.

  20. High-Precision Probe of the Fully Sequential Decay Width of the Hoyle State in 12C

    NASA Astrophysics Data System (ADS)

    Dell'Aquila, D.; Lombardo, I.; Verde, G.; Vigilante, M.; Acosta, L.; Agodi, C.; Cappuzzello, F.; Carbone, D.; Cavallaro, M.; Cherubini, S.; Cvetinovic, A.; D'Agata, G.; Francalanza, L.; Guardo, G. L.; Gulino, M.; Indelicato, I.; La Cognata, M.; Lamia, L.; Ordine, A.; Pizzone, R. G.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Santagati, G.; Spartà, R.; Spadaccini, G.; Spitaleri, C.; Tumino, A.

    2017-09-01

    The decay path of the Hoyle state in 12C (Ex=7.654 MeV ) has been studied with the 14N (d ,α2)12C (7.654 ) reaction induced at 10.5 MeV. High resolution invariant mass spectroscopy techniques have allowed us to unambiguously disentangle direct and sequential decays of the state passing through the ground state of 8Be. Thanks to the almost total absence of background and the attained resolution, a fully sequential decay contribution to the width of the state has been observed. The direct decay width is negligible, with an upper limit of 0.043% (95% C.L.). The precision of this result is about a factor 5 higher than previous studies. This has significant implications on nuclear structure, as it provides constraints to 3 α cluster model calculations, where higher precision limits are needed.

  1. Characterization of fragment emission in {sup 20}Ne(7-10 MeV/nucleon)+{sup 12}C reactions

    SciTech Connect

    Dey, Aparajita; Bhattacharya, C.; Bhattacharya, S.; Kundu, S.; Banerjee, K.; Mukhopadhyay, S.; Gupta, D.; Bhattacharjee, T.; Banerjee, S. R.; Bhattacharyya, S.; Rana, T. K.; Basu, S. K.; Saha, R.; Krishan, K.; Mukherjee, A.; Bandopadhyay, D.; Beck, C.

    2007-09-15

    The inclusive energy distributions of the complex fragments (3{<=}Z{<=}7) emitted from the bombardment of {sup 12}C by {sup 20}Ne beams with incident energies between 145 and 200 MeV have been measured in the angular range 10 deg.{<=}{theta}{sub lab}{<=}50 deg. Damped fragment yields in all the cases have been found to have the characteristic of emission from fully energy equilibrated composites. The binary fragment yields are compared with the standard statistical model predictions. Whereas Li and Be fragments yields are in agreement with statistical-model calculations, enhanced yields of entrance channel fragments (5{<=}Z{<=}7) indicate the survival of orbiting-like process in {sup 20}Ne+{sup 12}C system at these energies.

  2. Neutron yield of thick 12C and 13C targets with 20 and 30 MeV deuterons

    NASA Astrophysics Data System (ADS)

    Lhersonneau, G.; Malkiewicz, T.; Fadil, M.; Gorelov, D.; Jones, P.; Ngcobo, P. Z.; Sorri, J.; Trzaska, W. H.

    2016-12-01

    The neutron yield of thick targets of carbon, natural and enriched in 13C, bombarded by deuterons of 20 and 30 MeV has been measured by the activation method. The gain with respect to a 12C target is the same as with protons beams. The yield ratio is about 1.2 only and hardly can justify the use of a 13C target with deuteron beams. The data, apart from being of interest for the design of facilities where secondary neutron beams are used, provide a test case for calculations where both beam and target have a weakly bound neutron. The MCNPx code version 2.6.0, despite failing to reproduce some details of the experimental distributions, describes their global properties fairly well, especially the relative yields of the 12C and 13C targets.

  3. Study of the {sup 12}C ({sup 8}B, {sup 7}Be)X knockout reaction at intermediate energies

    SciTech Connect

    Sadeghi, H. Ghambari, M.; Fereidonnejad, R.

    2016-01-15

    The breakup reactions of {sup 8}B on a {sup 12}C target at 142, 285, 790, and 936MeV/nucleon have been studied. One-proton-removal cross sections, leading to the production of {sup 7}Be fragments in the ground and first excited states (at 0.429MeV), and the longitudinal momentum distributions of the {sup 7}Be fragments are obtained in the Eikonal approximation of the Glauber Model. The results of the calculations including the contribution of the {sup 7}Be to the ground and first excited states of {sup 8}B are compared with the available experimental data. One-proton-removal cross section for the {sup 12}C({sup 8}B, {sup 7}Be)X knockout reaction at 142, 285, 790, and 936 MeV/nucleon energy has been calculated. {sup 8}B and {sup 7}Be cross sections and momentum distribution are in a good agreement with available data.

  4. Mass spectrometric 13C/12C determinations to detect high fructose corn syrup in orange juice: collaborative study.

    PubMed

    Doner, L W; Bills, D D; Carro, O; Drimmie, R; Fritz, P; Gearing, J N; Hillaire-Marcel, C; Parker, P L; Reeseman, F M; Smith, B N; Ziegler, H

    1982-05-01

    The 13C/12C ratios in orange juice are sufficiently uniform and different from those in high fructose corn syrup (HFCS) so that the addition of HFCS to orange juice can be detected. HFCS averages -9.7% (parts per thousand) delta 13C, orange juice averages -24.5%, and mixtures of HFCS and orange juice possess intermediate values. One pure orange juice and 4 orange juice -HFCS mixtures containing from 25 to 70% orange juice were properly classified by 7 collaborators. Samples with delta 13C values less negative than -22.1%, 4 standard deviations from the mean of pure juices, can, with a high degree of confidence, be classified as adulterated. Samples with values more negative than -22.1% must be considered unadulterated with HFCS, because pure orange juices possess a range of delta 13C values. The 13C/12C mass spectrometric method was adopted official first action for detecting HFCS in orange juice.

  5. New silicon microdosimetry probes for RBE and biological dose studies using stationary and movable targets in 12C ion therapy

    NASA Astrophysics Data System (ADS)

    Chartier, L.; Tran, L. T.; Bolst, D.; Pogossov, A.; Guatelli, S.; Petasecca, M.; Lerch, M.; Prokopovich, D.; Reinhard, M.; Perevertaylo, V.; Jackson, M.; Matsufuji, N.; Rosenfeld, A. B.

    2017-01-01

    Due to the high LET and dense ionisation tracks associated with ions, microdosimetric approaches have been used in carbon ion therapy to assess field quality and calculate radiobiological quantities for a variety of cell lines. There is however a lack of instrumentation for simple and routine use in a clinical environment, important for determination of RBE which provides accurate treatment planning and delivery in hadron therapy. In this study, a 10 μm thick silicon microdosimeter with 3D sensitive volumes has been used to investigate the effect of motion on the RBE and field quality of a typical 12C ion therapy beam. For a passively scattered 290 MeV/u 12C beam with 6 cm spread-out Bragg peak (SOBP), variations in biological dose along the SOBP were observed, as well as a significant changes to particle LET when incident on a moving target.

  6. Dynamical explanation for the anomaly in the diffuseness parameter of the nucleus-nucleus potential in heavy-ion fusion reactions

    NASA Astrophysics Data System (ADS)

    Zanganeh, V.; Gharaei, R.; Wang, N.

    2017-03-01

    The abnormally large diffuseness parameter of the Woods-Saxon (WS) potential in heavy-ion fusion reactions is explained for the first time based on the microscopic dynamics simulations. With the improved quantum molecular dynamic (ImQMD) model, we systematically explore the dynamical processes in the fusion reactions 12C+92Zr , 16O+92Zr , 28Si+92Zr , 35Cl+92Zr , 40Ca+46Ti , and 16O+154Sm . Without introducing any free model parameters or additional assumptions, the microscopic ImQMD model can reproduce the measured fusion cross sections of all selected colliding systems with good accuracy. Due to the dynamical evolutions of the density distributions in the fusion processes, the energy dependence of nucleus-nucleus potential can be clearly observed. Based on the dynamical nucleus-nucleus potential of the ImQMD simulations, we extract the corresponding diffuseness parameters of the WS potential. The obtained values locate in a range between a =0.83 and 1.17 fm at different incident energies. In addition, the regular decreasing trend for the diffuseness parameter with the increase of the incident energies is also observed.

  7. Hummingbird Comet Nucleus Analysis Mission

    NASA Technical Reports Server (NTRS)

    Kojiro, Daniel; Carle, Glenn C.; Lasher, Larry E.

    2000-01-01

    Hummingbird is a highly focused scientific mission, proposed to NASA s Discovery Program, designed to address the highest priority questions in cometary science-that of the chemical composition of the cometary nucleus. After rendezvous with the comet, Hummingbird would first methodically image and map the comet, then collect and analyze dust, ice and gases from the cometary atmosphere to enrich characterization of the comet and support landing site selection. Then, like its namesake, Hummingbird would carefully descend to a pre-selected surface site obtaining a high-resolution image, gather a surface material sample, acquire surface temperature and then immediately return to orbit for detailed chemical and elemental analyses followed by a high resolution post-sampling image of the site. Hummingbird s analytical laboratory contains instrumentation for a comprehensive molecular and elemental analysis of the cometary nucleus as well as an innovative surface sample acquisition device.

  8. New decay branches of the radiative capture reaction {sup 12}C({sup 16}O,{gamma}){sup 28}Si

    SciTech Connect

    Lebhertz, D.; Courtin, S.; Haas, F.; Salsac, M.-D.; Beck, C.; Michalon, A.; Rousseau, M.; Marley, P. L.; Glover, R. G.; Kent, P. E.; Hutcheon, D. A.; Davis, C.; Pearson, J. E.

    2009-01-28

    Resonances in the {sup 12}C({sup 16}O,{gamma}){sup 28}Si radiative capture process at energies around the Coulomb barrier have been probed using the very selective 0 deg. Dragon spectrometer at Triumf and its associated BGO {gamma}-array. For the first time the full level scheme involved in this process has been measured and shows previously unobserved {gamma}-decay to doorway states around 11 MeV in {sup 28}Si.

  9. The Simultaneous Investigation of the {sup 6}He+{sup 12}C Reaction Observables Using Folding Potential

    SciTech Connect

    Karakoc, M.; Kucuk, Y.; Boztosun, I.

    2008-11-11

    We investigate the observables of the {sup 6}He+{sup 12}C system by using coupled-channels Born approximation. We try to address the role of the transfer channels in explaining the reaction observables. We noticed the inclusion of the transfer channels does not have large effect. However, we present that deformation of the imaginary potential has an important effect in explaining the elastic, inelastic and transfer reaction data simultaneously for this system.

  10. Early effects of low dos 12C6+ ion or X-ray irradiation on human peripheral blood lymphocytes

    PubMed Central

    Chen, Yingtai; Li, Yumin; Zhang, Hong; Xie, Yi; Chen, Xuezhong; Ren, Jinyu; Zhang, Xiaowei; Zhu, Zijiang; Liu, Hongliang; Zhang, Yawei

    2009-01-01

    The aim of this study was to estimate the acute effects of low dose 12C6+ ions or X-ray radiation on human immune function. The human peripheral blood lymphocytes (HPBL) of seven healthy donors were exposed to 0.05Gy 12C6+ ions or X-ray radiation and cell responses were measured at 24 hours after exposure. The cytotoxic activities of HPBL were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT); the percentages of T and NK cells subsets were detected by flow cytometry; mRNA expression of interleukin (IL)-2, tumor necrosis factor (TNF)-α and interferon (IFN)-γ were examined by real time quantitative RT-PCR (qRT-PCR); and these cytokines protein levels in supernatant of cultured cells were assayed by enzyme-linked immunosorbent assays (ELISA). The results showed that the cytotoxic activity of HPBL, mRNA expression of IL-2, IFN-γ and TNF-α in HPBL and their protein levels in supernatant were significantly increased at 24 hours after exposure to 0.05Gy 12C6+ ions radiation and the effects were stronger than observed for X-ray exposure. However, there was no significant change in the percentage of T and NK cells subsets of HPBL. These results suggested that 0.05Gy high linear energy transfer (LET) 12C6+ radiation was a more effective approach to host immune enhancement than that of low LET X-ray. We conclude that cytokines production might be used as sensitive indicators of acute response to LDI. PMID:20401163

  11. Early effects of low dose 12C6+ ion or X-ray irradiation on human peripheral blood lymphocytes

    NASA Astrophysics Data System (ADS)

    Chen, Yingtai; Li, Yumin; Zhang, Hong; Xie, Yi; Chen, Xuezhong; Ren, Jinyu; Zhang, Xiaowei; Zhu, Zijiang; Liu, Hongliang; Zhang, Yawei

    2010-04-01

    The aim of this study was to estimate the acute effects of low dose 12C6+ ions or X-ray radiation on human immune function. The human peripheral blood lymphocytes (HPBL) of seven healthy donors were exposed to 0.05 Gy 12C6+ ions or X-ray radiation and cell responses were measured at 24 h after exposure. The cytotoxic activities of HPBL were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT); the percentages of T and NK cells subsets were detected by flow cytometry; mRNA expression of interleukin (IL)-2, tumor necrosis factor (TNF)-α and interferon (IFN)-γ were examined by real time quantitative RT-PCR (qRT-PCR); and these cytokines protein levels in supernatant of cultured cells were assayed by enzyme-linked immunosorbent assays (ELISA). The results showed that the cytotoxic activity of HPBL, mRNA expression of IL-2, IFN-γ and TNF-α in HPBL and their protein levels in supernatant were significantly increased at 24 h after exposure to 0.05 Gy 12C6+ ions radiation and the effects were stronger than observed for X-ray exposure. However, there was no significant change in the percentage of T and NK cells subsets of HPBL. These results suggested that 0.05 Gy high linear energy transfer (LET) 12C6+ radiation was a more effective approach to host immune enhancement than that of low LET X-ray. We conclude that cytokines production might be used as sensitive indicators of acute response to LDI.

  12. Background reduction system of {sup 4}He({sup 12}C,{sup 16}O)gamma at KUTL

    SciTech Connect

    Taniguchi, M.; Sagara, K.; Teranishi, T.; Fujita, K.; Iwabuchi, R.; Gotoh, T.; Nakano, K.; Oba, N.

    2010-06-01

    The C-alpha reaction is one of the most important reactions in astrophysics. At Kyushu University Tandem accelerator Laboratory (KUTL), a high detective efficiency measurement has been made by adopting inverse kinematics: {sup 12}C beam is injected on windowless {sup 4}He gas target. In this experiment, a powerful background reduction system is necessary. We describe the effectiveness of the background system consisting of recoil mass separator, a long time chopper, and new movable slits.

  13. Determination of the (13)C/(12)C Carbon Isotope Ratio in Carbonates and Bicarbonates by (13)C NMR Spectroscopy.

    PubMed

    Pironti, Concetta; Cucciniello, Raffaele; Camin, Federica; Tonon, Agostino; Motta, Oriana; Proto, Antonio

    2017-10-09

    This paper is the first study focused on the innovative application of (13)C NMR (nuclear magnetic resonance) spectroscopy to determine the bulk (13)C/(12)C carbon isotope ratio, at natural abundance, in inorganic carbonates and bicarbonates. In the past, (13)C NMR spectroscopy (irm-(13)C NMR) was mainly used to measure isotope ratio monitoring with the potential of conducting (13)C position-specific isotope analysis of organic molecules with high precision. The reliability of the newly developed methodology for the determination of stable carbon isotope ratio was evaluated in comparison with the method chosen in the past for these measurements, i.e., isotope ratio mass spectrometry (IRMS), with very encouraging results. We determined the (13)C/(12)C ratio of carbonates and bicarbonates (∼50-100 mg) with a precision on the order of 1‰ in the presence of a relaxation agent, such as Cr(acac)3, and CH3(13)COONa as an internal standard. The method was first applied to soluble inorganic carbonates and bicarbonates and then extended to insoluble carbonates by converting them to Na2CO3, following a simple procedure and without observing isotopic fractionation. Here, we demonstrate that (13)C NMR spectroscopy can also be successfully adopted to characterize the (13)C/(12)C isotope ratio in inorganic carbonates and bicarbonates with applications in different fields, such as cultural heritage and geological studies.

  14. Measurement of elastic 12C+alpha scattering: details of the experiment, analysis, and discussion of phase shifts

    SciTech Connect

    Couture, Aaron Joseph; Detwiler, Rebecca; Gorres, Joachim; Stech, Edward J; Ugalde, Claudio; Wiescher, Michael C F; Heil, Michael; Kappeler, Franz; Azuma, Richard E; Buchmann, Lothar

    2009-01-01

    Recent global analyses of {sup 12}C({alpha},{gamma}){sup 16}O have incorporated both elastic-scallering and {beta}-decay data in addition to direct measurements. In that context, it has been shown that an improvement in the available elastic-scallering data could help determine the contribution of the two subthreshold states, 6.92(2{sup +}) and 7.12(1{sup -}) MeV, and with excellent statistics could restrict resonance parameters above the threshold. To this end angular distributions of {sup 12}C({alpha}, {alpha}){sup 12}C in the {alpha}-energy range of 2.6-8.2 MeV, at angles from 24 to 166 have been measured at the University of Notre Dame using an array of 32 silicon detectors. Details of the experiment are reported. In the present analysis, the phase shifts have been determined from our previously reported R-matrix fit to these data. The uncertainties in the R-matrix phase shifts ({ell} = 0...6) are derived by a new Monte Carlo analysis technique as described in the article. We provide these phase shifts here for general use, in particular for the improved analysis and extrapolation of the {alpha} radiative capture to low energies.

  15. TERAHERTZ SPECTROSCOPY OF THE BENDING VIBRATIONS OF ACETYLENE {sup 12}C{sub 2}H{sub 2}

    SciTech Connect

    Yu Shanshan; Drouin, Brian J.; Pearson, John C.

    2009-11-01

    Twenty P-branch transitions of {sup 12}C{sub 2}H{sub 2} have been measured in the 0.8-1.6 THz region of its bending vibrational difference band. The accuracy of these measurements is estimated to be 100 kHz. The {sup 12}C{sub 2}H{sub 2} molecules were generated under room temperature by passing 150 mTorr H{sub 2}O vapor through calcium carbide (CaC{sub 2}) powder. The observed transitions were modeled together with prior far-infrared data involving the bending levels with SIGMA{sub t}V{sub t} (t = 4,5)<=2. Frequency predictions of {sup 12}C{sub 2}H{sub 2} in the terahertz region have been greatly improved by adding the first data of 'microwave' precision. The new measurements and predictions reported here will facilitate the analyses of astronomical observations by the high spectral resolution telescopes such as Herschel, SOFIA, and ALMA.

  16. Indolizines and pyrrolo[1,2-c]pyrimidines decorated with a pyrimidine and a pyridine unit respectively.

    PubMed

    Popa, Marcel Mirel; Georgescu, Emilian; Caira, Mino R; Georgescu, Florentina; Draghici, Constantin; Stan, Raluca; Deleanu, Calin; Dumitrascu, Florea

    2015-01-01

    The three possible structural isomers of 4-(pyridyl)pyrimidine were employed for the synthesis of new pyrrolo[1,2-c]pyrimidines and new indolizines, by 1,3-dipolar cycloaddition reaction of their corresponding N-ylides generated in situ from their corresponding cycloimmonium bromides. In the case of 4-(3-pyridyl)pyrimidine and 4-(4-pyridyl)pyrimidine the quaternization reactions occur as expected at the pyridine nitrogen atom leading to pyridinium bromides and consequently to new indolizines via the corresponding pyridinium N-ylides. However, in the case of 4-(2-pyridyl)pyrimidine the steric hindrance directs the reaction to the pyrimidinium N-ylides and, subsequently, to the formation of the pyrrolo[1,2-c]pyrimidines. The new pyrrolo[1,2-c]pyrimidines and the new indolizines were structurally characterized through NMR spectroscopy. The X-ray structures of two of the starting materials, 4-(2-pyridyl)pyrimidine and 4-(4-pyridyl)pyrimidine, are also reported.

  17. Construction of a chimeric lysin Ply187N-V12C with extended lytic activity against staphylococci and streptococci

    PubMed Central

    Dong, Qiuhua; Wang, Jing; Yang, Hang; Wei, Cuihua; Yu, Junping; Zhang, Yun; Huang, Yanling; Zhang, Xian-En; Wei, Hongping

    2015-01-01

    Developing chimeric lysins with a wide lytic spectrum would be important for treating some infections caused by multiple pathogenic bacteria. In the present work, a novel chimeric lysin (Ply187N-V12C) was constructed by fusing the catalytic domain (Ply187N) of the bacteriophage lysin Ply187 with the cell binding domain (146-314aa, V12C) of the lysin PlyV12. The results showed that the chimeric lysin Ply187N-V12C had not only lytic activity similar to Ply187N against staphylococcal strains but also extended its lytic activity to streptococci and enterococci, such as Streptococcus dysgalactiae, Streptococcus agalactiae, Streptococcus pyogenes, Enterococcus faecium and Enterococcus faecalis, which Ply187N could not lyse. Our work demonstrated that generating novel chimeric lysins with an extended lytic spectrum was feasible through fusing a catalytic domain with a cell-binding domain from lysins with lytic spectra across multiple genera. PMID:25219798

  18. Checkerboard Theory of the Nucleus.

    NASA Astrophysics Data System (ADS)

    Lach, Theodore

    2006-04-01

    The Checker Board Model (CBM) is a 2D model of the nucleus that proposes that the synchronization of the 2 outer rotating quarks in the nucleons accounts for magnetic moment of the nucleons and that the magnetic flux from the nucleons couples (weaves) into the 2D checker board array structures and this magnetic coupling in addition to electrostatic forces of the rotating and stationary quarks accounts for the apparent strong nuclear force. The symmetry of the He nucleus helps explain why this 2D structure is so stable. This model explain the mass of the proton and neutron, along with their magnetic moments and their absolute and relative sizes in terms of the above structure and predict the masses of two newly proposed quarks ^(1): the ``up'' and the ``dn'' quarks. Since the masses of the ``up'' and ``dn'' quark determined by the CBM (237.31 MeV and 42.392 MeV respectively) did not fit within the standard model as candidates for u and d, a new model (New Physics) had to be invented. This new particle physics model predicts that nature has 5 generations not 3. (1). T.M. Lach, Checkerboard Structure of the Nucleus, Infinite Energy, Vol. 5, issue 30, (2000). (2). T.M. Lach, Masses of the Sub-Nuclear Particles, nucl-th/0008026, @http://xxx.lanl.gov/

  19. Targeted delivery to the nucleus.

    PubMed

    Pouton, Colin W; Wagstaff, Kylie M; Roth, Daniela M; Moseley, Gregory W; Jans, David A

    2007-08-10

    Macromolecules and supramolecular complexes are frequently required to enter and exit the nucleus during normal cell function, but access is restricted and exchange to and from the nucleus is tightly controlled. We describe the mechanisms which regulate nuclear import of endogenous molecules and indicate how viruses exploit these mechanisms during their life cycle. Opportunities exist to make use of natural pathways for delivery of therapeutic entities, in particular to develop safe and effective methods for gene therapy, although past attempts to design non-viral nuclear delivery systems have met with limited success. To increase the likelihood of success scientists will need an appreciation of the mechanisms by which viruses deliver their genomes to the nucleus, and will need a commitment to control the architecture of non-viral delivery systems at the molecular level. Effective delivery systems will require several attributes to facilitate endosomal escape, microtubular transport and uptake through the nuclear pore complex. The published literature provides a strong foundation for design of nuclear targeting systems. The challenge faced by delivery scientists is to assemble a system which is as effective as, for example, the adenovirus but which lacks its immunogenicity. This article reviews the relevant literature and indicates key areas for future research.

  20. Stimulated Raman scattering-active isotopically pure 12C and 13C diamond crystals: A milestone in the development of diamond photonics

    NASA Astrophysics Data System (ADS)

    Kaminskii, A. A.; Ral'chenko, V. G.; Yoneda, H.; Bol'shakov, A. P.; Inyushkin, A. V.

    2016-09-01

    Isotopically pure 12C and 13C diamonds are synthesized by chemical vapor deposition and impulsive stimulated Raman scattering in these crystals is investigated. The thermal conductivity of 12C isotopically pure damond and natC diamond with natural isotopic composition is measured. Phonon-nondegenerate Stokes lasing based on the χ(3) nonlinearity in the 12C, 13C, and natC diamond "triad" is attained, which opens a new stage in the development of diamond photonics.

  1. Measurement of charge- and mass-changing cross sections for 4He+12C collisions in the energy range 80-220 MeV/u for applications in ion beam therapy

    NASA Astrophysics Data System (ADS)

    Horst, Felix; Schuy, Christoph; Weber, Uli; Brinkmann, Kai-Thomas; Zink, Klemens

    2017-08-01

    4He ions are considered to be used for hadron radiotherapy due to their favorable physical and radiobiological properties. For an accurate dose calculation the fragmentation of the primary 4He ions occurring as a result of nuclear collisions must be taken into account. Therefore precise nuclear reaction models need to be implemented in the radiation transport codes used for dose calculation. A fragmentation experiment using thin graphite targets was conducted at the Heidelberg Ion Beam Therapy Center (HIT) to obtain new and precise 4He-nucleus cross section data in the clinically relevant energy range. Measured values for the charge-changing cross section, mass-changing cross section, as well as the inclusive 3He production cross section for 4He+12C collisions at energies between 80 and 220 MeV /u are presented. These data are compared to the 4He-nucleus reaction model by DeVries and Peng as well as to the parametrizations by Tripathi et al. and by Cucinotta et al., which are implemented in the treatment planning code trip98 and several other radiation transport codes.

  2. Classifiers for centrality determination in proton-nucleus and nucleus-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Altsybeev, Igor; Kovalenko, Vladimir

    2017-03-01

    Centrality, as a geometrical property of the collision, is crucial for the physical interpretation of nucleus-nucleus and proton-nucleus experimental data. However, it cannot be directly accessed in event-by-event data analysis. Common methods for centrality estimation in A-A and p-A collisions usually rely on a single detector (either on the signal in zero-degree calorimeters or on the multiplicity in some semi-central rapidity range). In the present work, we made an attempt to develop an approach for centrality determination that is based on machine-learning techniques and utilizes information from several detector subsystems simultaneously. Different event classifiers are suggested and evaluated for their selectivity power in terms of the number of nucleons-participants and the impact parameter of the collision. Finer centrality resolution may allow to reduce impact from so-called volume fluctuations on physical observables being studied in heavy-ion experiments like ALICE at the LHC and fixed target experiment NA61/SHINE on SPS.

  3. 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.

  4. Absence of jet quenching in peripheral nucleus-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Loizides, Constantin; Morsch, Andreas

    2017-10-01

    Medium effects on the production of high-pT particles in nucleus-nucleus (AA) collisions are generally quantified by the nuclear modification factor (RAA), defined to be unity in absence of nuclear effects. Modeling particle production including a nucleon-nucleon impact parameter dependence, we demonstrate that RAA at midrapidity in peripheral AA collisions can be significantly affected by event selection and geometry biases. Even without jet quenching and shadowing, these biases cause an apparent suppression for RAA in peripheral collisions, and are relevant for all types of hard probes and all collision energies. Our studies indicate that calculations of jet quenching in peripheral AA collisions should account for the biases, or else they will overestimate the relevance of parton energy loss. Similarly, expectations of parton energy loss in light-heavy collision systems based on comparison with apparent suppression seen in peripheral RAA should be revised. Our interpretation of the peripheral RAA data would unify observations for lighter collision systems or lower energies where significant values of elliptic flow are observed despite the absence of strong jet quenching.

  5. Application of multiple scattering theory to lower-energy elastic nucleon-nucleus scattering

    NASA Astrophysics Data System (ADS)

    Chinn, C. R.; Elster, Ch.; Thaler, R. M.; Weppner, S. P.

    1995-03-01

    The optical model potentials for nucleon-nucleus elastic scattering at 65 meV are calculated for 12C, 16O, 28Si, 40Ca, 56Fe, 90Zr, and 208Pb in first-order multiple scattering theory, following the prescription of the spectator expansion, where the only inputs are the free nucleon-nucleon (NN) potentials, the nuclear densities, and the nuclear mean field as derived from microscopic nuclear structure calculations. These potentials are used to predict differential cross sections, analyzing powers, and spin rotation functions for neutron and proton scattering at 65 MeV projectile energy and compared with available experimental data. The theoretical curves are in very good agreement with the data. The modification of the propagator due to the coupling of the struck nucleon to the residual nucleus is seen to be significant at this energy and invariably improves the congruence of theoretical prediction and measurement.

  6. Nucleus morphology of Comet Halley

    NASA Technical Reports Server (NTRS)

    Reitsema, H. J.; Delamere, W. A.; Huebner, W. F.; Keller, H. U.; Schmidt, W. K. H.; Wilhelm, K.; Schmidt, H. U.; Whipple, Fred L.

    1986-01-01

    Images obtained by the Halley multicolor camera were used to determine the projected size and shape of the nucleus. The location of the terminator and numerous surface features were determined. There is good correlation between the brightest surface features and the dust jets; however, many bright features are seen which are not associated with jets. Most of the observed features are circular and appear to be related to surface elevation. The angularity of the terminator gives an indication of the three-dimensional structure of the face which was observed.

  7. Exceptionally bright, compact starburst nucleus

    SciTech Connect

    Margon, B.; Anderson, S.F.; Mateo, M.; Fich, M.; Massey, P.

    1988-11-01

    Observations are reported of a remarkably bright (V about 13) starburst nucleus, 0833 + 652, which has been detected at radio, infrared, optical, ultraviolet, and X-ray wavelengths. Despite an observed flux at each of these wavelengths which is comparable to that of NGC 7714, often considered the 'prototypical' example of the starburst phenomenon, 0833 + 652 appears to be a previously uncataloged object. Its ease of detectability throughout the electromagnetic spectrum should make it useful for a variety of problems in the study of compact emission-line galaxies. 30 references.

  8. Ambiguities in the rate of oxygen formation during stellar helium burning in the 12C(α,γ) reaction

    NASA Astrophysics Data System (ADS)

    Gai, Moshe

    2013-12-01

    The rate of oxygen formation determines the C/O ratio during stellar helium burning. It is the single most important nuclear input in stellar evolution theory, including the evolution of type II and type Ia supernova. However, the low-energy cross section of the fusion of 4He +12C, denoted as the 12C(α,γ)16O reaction, still remains uncertain. I analyze and critically review the most recent measurements of complete angular distributions of the outgoing γ rays at very low energies (Ec.m.≥1.0 MeV). My analysis of the angular distributions measured with the EUROGAM/GANDI arrays leads to considerably larger error bars than have been published, which excludes them from the current sample of “world data.” I show that the current sample of “world data” of the measured E2 cross-section factors below 1.7 MeV cluster into two distinct groups that lead to two distinct extrapolations: SE2(300)≈60 or SE2(300)≈154 keVb. There is a discrepancy between the measured E1-E2 phase difference (ϕ12) and unitarity as required by the Watson theorem, which suggests systematic problem(s) in some of the measured γ-ray angular distributions. The ambiguity of the extrapolated SE2(300) together with the previously observed ambiguity of SE1(300) (approximately 80 or 10 keVb) must be resolved by future measurements of complete and detailed angular distributions of the 12C(α,γ) reaction at very low energies (Ec.m.≤1.0 MeV).

  9. Virulence factors and resistance to antimicrobials in Listeria monocytogenes serotype 1/2c isolated from food.

    PubMed

    Gelbíčová, T; Pantůček, R; Karpíšková, R

    2016-08-01

    The aim of this study was to assess the potential risk posed to the human population by the presence of Listeria monocytogenes serotype 1/2c in food based on the characterization of virulence factors of Listeria involved in the invasion of host cells and sensitivity to antimicrobial agents. In addition to sequencing of the inlA and inlB genes, the presence of genes lapB, aut, fbpA, ami, vip and llsX was tested. A premature stop codon (PMSC) in the inlA gene was detected in all tested strains of serotype 1/2c and, concurrently, two novel PMSC mutation types were identified. However, neither PMSC in the inlB gene nor deletion of the lapB, aut, fbpA, ami and vip genes were found in any of the strains. The presence of the llsX gene was not confirmed. Even though all L. monocytogenes strains showed sensitivity to the tested antimicrobials on the basis of their phenotype, sequencing revealed the presence of IS1542 insertion in the inlA gene, indicating the possibility of sharing of mobile genetic elements associated with antimicrobial resistance among strains. Other than the presence of PMSCs in the inlA gene, no PMSC in inlB or deletion of other factors linked to the invasiveness of listeria were detected. Tested strains showed sensitivity to antibiotics used in the therapy of listeriosis. Strains of L. monocytogenes serotype 1/2c typically carry a PMSC in the inlA gene, but these strains still represent a potential threat to public health. The possibility of transfer of IS1542, associated with resistance to vancomycin, between enterococci and Listeria spp. was revealed. © 2016 The Society for Applied Microbiology.

  10. Reaction mechanisms in {sup 24}Mg+{sup 12}C and {sup 32}S+{sup 24}Mg

    SciTech Connect

    Beck, C.; Sanchez i Zafra, A.; Papka, P.; Thummerer, S.; Azaiez, F.; Courtin, S.; Curien, D.; Dorvaux, O.; Lebhertz, D.; Nourreddine, A.; Rousseau, M.; Oertzen, W. von; Gebauer, B.; Kokalova, Tz.; Wheldon, C.; De Angelis, G.; Gadea, A.; Lenzi, S.; Napoli, D. R.; Szilner, S.

    2009-03-04

    The occurrence of 'exotic' shapes in light N = Z{alpha}-like nuclei is investigated for {sup 24}Mg+{sup 12}C and {sup 32}S+{sup 24}Mg. Various approaches of superdeformed and hyperdeformed bands associated with quasimolecular resonant structures with low spin are presented. For both reactions, exclusive data were collected with the Binary Reaction Spectrometer in coincidence with EUROBALL IV installed at the VIVITRON Tandem facility of Strasbourg. Specific structures with large deformation were selectively populated in binary reactions and their associated {gamma}-decays studied. The analysis of the binary and ternary reaction channels is discussed.

  11. Detailed study and mean field interpretation of {sup 16}O+{sup 12}C elastic scattering at seven medium energies

    SciTech Connect

    Nicoli, M. P.; Haas, F.; Freeman, R. M.; Szilner, S.; Basrak, Z.; Morsad, A.; Satchler, G. R.; Brandan, M. E.

    2000-03-01

    Detailed measurements of the elastic scattering of {sup 16}O ions from {sup 12}C have been carried out at seven energies from 62 to 124 MeV, at center-of-mass angles from about 10 degree sign to about 145 degree sign . A coherent optical model analysis of these data has been performed using both the Woods-Saxon and the folding-model potentials. The extracted results are consistent with analyses of data at higher energies for this and similar light heavy-ion systems. Some model-independent spline forms for the real potentials were also investigated. (c) 2000 The American Physical Society.

  12. Measurements of Atmospheric Methane and 13C/12C of Atmospheric Methane from Flask Air Samples (1999)

    DOE Data Explorer

    Quay, Paul; Stutsman, Johnny

    1999-01-01

    This database offers precise measurements of atmospheric methane and 13C/12C in atmospheric methane from flask air samples collected at eight sites worldwide and aboard NOAA cruises in the Pacific Ocean. The eight sites include Olympic Peninsula, Washington; Cape Grim, Tasmania; Fraserdale, Ontario; Marshall Islands; Baring Head, New Zealand; Mauna Loa, Hawaii; Point Barrow, Alaska; and American Samoa. The measurements span the period 1988 to mid-1996. These data are useful for global methane budget analyses and for determining the atmospheric isotopic composition of methane. All isotopic measurements have been corrected for standard drift.

  13. [sup 12]C([gamma],[ital p])[sup 11]B cross section from 80 to 157 MeV

    SciTech Connect

    Harty, P.D.; McGeorge, J.C.; MacGregor, I.J.D.; Owens, R.O.; Annand, J.R.M.; Anthony, I.; Crawford, G.I.; Dancer, S.N.; Hall, S.J.; Kellie, J.D.; Miller, G.J. ); Schoch, B.; Beck, R.; Schmieden, H.; Vogt, J.M. ); Ryckebusch, J. )

    1995-04-01

    The [sup 12]C([gamma],[ital p])[sup 11]B differential cross section has been measured over proton angles ranging from 58[degree] to 128[degree], using tagged photons of energy 80--157 MeV, for low-lying regions of residual excitation energy in [sup 11]B. The data have been compared with four different types of calculation. It is shown that scaling of the cross section with momentum mismatch occurs for both the ground-state and excited-state data.

  14. Comparative Study of {sup 6}He+{sup 12}C System by using Different Types of Nucleon Density Distributions

    SciTech Connect

    Kucuk, Y.; Boztosun, I.; Ibraheem, A.

    2008-11-11

    In this paper, we present the analysis of the {sup 6}He+{sup 12}C elastic scattering at 18.0 MeV within the framework of the double folding model. In order to make a comparative study, we have used four different types of nucleon density distributions for the ground state of the {sup 6}He in the microscopic potential calculations. We have observed that all these density distributions provide a consistent description of the elastic scattering angular distributions for this system.

  15. Search for η' mesic nuclei by missing-mass spectroscopy of the 12C(p,d) reaction

    NASA Astrophysics Data System (ADS)

    Tanaka, Yoshiki K.; Ayyad, Yassid; Benlliure, Jose; Brinkmann, Kai-Thomas; Friedrich, Stefan; Fujioka, Hiroyuki; Geissel, Hans; Gellanki, Jnaneswari; Guo, Chenlei; Gutz, Eric; Haettner, Emma; Harakeh, Muhsin N.; Hayano, Ryugo S.; Higashi, Yuko; Hirenzaki, Satoru; Hornung, Christine; Igarashi, Yoichi; Ikeno, Natsumi; Itahashi, Kenta; Iwasaki, Masahiko; Jido, Daisuke; Kalantar-Nayestanaki, Nasser; Kanungo, Rituparna; Knoebel, Ronja; Kurz, Nikolaus; Metag, Volker; Mukha, Ivan; Nagae, Tomofumi; Nagahiro, Hideko; Nanova, Mariana; Nishi, Takahiro; Ong, Hooi Jin; Pietri, Stephane; Prochazka, Andrej; Rappold, Christophe; Reiter, Moritz P.; Rodríguez Sánchez, Jose Luis; Scheidenberger, Christoph; Simon, Haik; Sitar, Branislav; Strmen, Peter; Sun, Baohua; Suzuki, Ken; Szarka, Imrich; Takechi, Maya; Tanihata, Isao; Terashima, Satoru; Watanabe, Yuni N.; Weick, Helmut; Widmann, Eberhard; Winfield, John S.; Xu, Xiaodong; Yamakami, Hiroki; Zhao, Jianwei

    2016-11-01

    We performed a missing-mass spectroscopy experiment of the 12C(p, d) reaction at 2.5 GeV proton energy in order to search for η' mesic nuclei. An excitation-energy spectrum of 11C was obtained around the η' production threshold. As no significant peak structure was observed in the spectrum, upper limits of the formation cross section of η' mesic nuclei have been determined. Preliminary results of the experiment as well as future prospects are given.

  16. (α,2α) cluster knockout reaction on 9Be and 12C at 580 MeV

    NASA Astrophysics Data System (ADS)

    Nadasen, A.; Brusoe, J.; Farhat, J.; Rao, K. A. G.; Sisan, D.; Williams, J.; Roos, P. G.; Adimi, F.; Gu, T.; Khayat, M.; Warner, R. E.

    1999-02-01

    Cross-section measurements of the 9Be,12C(α,2α) reaction at 580 MeV bombarding energy are presented. The data are compared with distorted-wave impulse approximation calculations. The agreement between theory and experiment suggests a dominance of the quasifree knockout mechanism. The extracted α-particle spectroscopic factors are in reasonable agreement with theory and proton-induced knockout reactions, unlike measurements for the (α,2α) reaction at energies <=140 MeV, but still show significant angular dependence.

  17. {sup 16}O resonances near 4α threshold through {sup 12}C({sup 6}Li,d) reaction

    SciTech Connect

    Rodrigues, M. R. D.; Borello-Lewin, T.; Miyake, H.; Horodynski-Matsushigue, L. B.; Duarte, J. L. M.; Rodrigues, C. L.; Faria, P. Neto de; Cunsolo, A.; Cappuzzello, F.; Foti, A.; Agodi, C.; Cavallaro, M.; Napoli, M. di; Ukita, G. M.

    2014-11-11

    Several narrow alpha resonant {sup 16}O states were detected through the {sup 12}C({sup 6}Li,d) reaction, in the range of 13.5 to 17.5 MeV of excitation energy. The reaction was measured at a bombarding energy of 25.5 MeV employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion technique. Experimental angular distributions associated with natural parity quasi-bound states around the 4α threshold are presented and compared to DWBA predictions. The upper limit for the resonance widths obtained is near the energy resolution (15 keV)

  18. The induced pseudoscalar coupling and the neutrino helicity from 12C(μ,νμ)12B

    NASA Astrophysics Data System (ADS)

    Botella, F. J.; Bernabéu, J.

    1982-07-01

    Recent measurements by Roesch et al. of recoil polarizations in 12C(μ,νμ)12B (g.s.) are analysed when the sign of the helicity hν of the emitted neutrino is allowed to change. Although the analysis of observables in terms of a ratio of two amplitudes remains the same, the dynamical information on couplings contained in this ratio is different. We conclude, from the experimental results, that the nuclear pseudoscalar coupling is ƒ;p=-1.02 if hν=-1, whereas ƒ;p=+2.79 if hν =+1.

  19. Observation of the Quasifree Reactions 12C(π+/-, π+/-p) at 245 MeV

    NASA Astrophysics Data System (ADS)

    Piasetzky, E.; Ashery, D.; Altman, A.; Yavin, A. I.; Schlepütz, F. W.; Powers, R. J.; Bertl, W.; Felawka, L.; Walter, H. K.; Winter, R. G.; Pluym, J. V. D.

    1981-05-01

    The inclusive reactions 12C(π+/-,π+/-p) were studied at 245 MeV over a broad kinematic range by coincidence measurement of the outgoing particles. The π+/--p angular correlations, proton energy spectra, and the ratio of positive- to negative-pion cross sections are all consistent with those expected from quasifree scattering. For positive pions, quasifree scattering accounts for (30 +/- 3)% of the inclusive pion inelastic scattering to backward angles. The rest is attributed to the (π+,π+n) reaction and to multistep processes.

  20. The Titan 14N/ 15N and 12C/ 13C isotopic ratios in HCN from Cassini/CIRS

    NASA Astrophysics Data System (ADS)

    Vinatier, Sandrine; Bézard, Bruno; Nixon, Conor A.

    2007-11-01

    We report the detection of H 13CN and HC 15N in mid-infrared spectra recorded by the Composite Infrared Spectrometer (CIRS) aboard Cassini, along with the determination of the 12C/ 13C and 14N/ 15N isotopic ratios. We analyzed two sets of limb spectra recorded near 13-15° S (Tb flyby) and 83° N (T4 flyby) at 0.5 cm -1 resolution. The spectral range 1210-1310 cm -1 was used to retrieve the temperature profile in the range 145-490 km at 13° S and 165-300 km at 83° N. These two temperature profiles were then incorporated in the atmospheric model to retrieve the abundance profile of H 12C 14N, H 13CN and HC 15N from their bands at 713, 706 and 711 cm -1, respectively. The HCN abundance profile was retrieved in the range 90-460 km at 15° S and 165-305 km at 83° N. There is no evidence for vertical variations of the isotopic ratios. Constraining the isotopic abundance profiles to be proportional to the HCN one, we find C12/C13=89-18+22 at 15° S, and 68-12+16 at 83° N, two values that are statistically consistent. A combination of these results yields a 12C/ 13C value equal to 75±12. This global result, as well as the 15° S one, envelop the value in Titan's methane ( 82.3±1) [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779-784] measured at 10° S and is slightly lower than the terrestrial inorganic standard value (89). The 14N/ 15N isotopic ratio is found equal to 56-13+16 at 15° S and 56-9+10 at 83° N. Combining the two values yields 14N/ 15N = 56 ± 8, which corresponds to an enrichment in 15N of about 4.9 compared with the terrestrial ratio. These results agree with the values obtained from previous ground-based millimeter observations [Hidayat, T., Marten, A., Bézard, B., Gautier, D., Owen, T., Matthews, H.E., Paubert, G., 1997. Icarus 126, 170-182; Marten, A., Hidayat, T., Biraud, Y., Moreno, R., 2002. Icarus 158, 532-544]. The 15N/ 14N ratio found in HCN is ˜3 times higher than in N 2 [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779

  1. Analyzing powers for {sup 6}{rvec L}i+{sup 12}C scattering at 30 and 50 MeV

    SciTech Connect

    Kerr, P.L.; Reber, E.L.; Green, P.V.; Kemper, K.W.; Mendez, A.J.; Mohajeri, K.; Myers, E.G.; Schmidt, B.G.; Hnizdo, V.

    1995-07-15

    Comparison between elastic analyzing powers at 30 and 50 MeV show no decrease in their magnitude at the higher energy. A combined optical model analysis of both energies shows T{sub 21} to arise from the tensor interaction, T{sub 20} to be an interference between tensor and J dependent interactions, and iT{sub 11} to be the most complicated, arising from an explicit spin-orbit, tensor, and J dependent interactions. The inelastic {sup 12}C vector analyzing powers require an explicit spin-orbit interaction to reproduce the magnitude of the oscillations.

  2. How viruses access the nucleus.

    PubMed

    Cohen, Sarah; Au, Shelly; Panté, Nelly

    2011-09-01

    Many viruses depend on nuclear proteins for replication. Therefore, their viral genome must enter the nucleus of the host cell. In this review we briefly summarize the principles of nucleocytoplasmic transport, and then describe the diverse strategies used by viruses to deliver their genomes into the host nucleus. Some of the emerging mechanisms include: (1) nuclear entry during mitosis, when the nuclear envelope is disassembled, (2) viral genome release in the cytoplasm followed by entry of the genome through the nuclear pore complex (NPC), (3) capsid docking at the cytoplasmic side of the NPC, followed by genome release, (4) nuclear entry of intact capsids through the NPC, followed by genome release, and (5) nuclear entry via virus-induced disruption of the nuclear envelope. Which mechanism a particular virus uses depends on the size and structure of the virus, as well as the cellular cues used by the virus to trigger capsid disassembly and genome release. This article is part of a Special Issue entitled: Regulation of Signaling and Cellular Fate through Modulation of Nuclear Protein Import. 2010 Elsevier B.V. All rights reserved.

  3. Comet nucleus sample return mission

    NASA Technical Reports Server (NTRS)

    1983-01-01

    A comet nucleus sample return mission in terms of its relevant science objectives, candidate mission concepts, key design/technology requirements, and programmatic issues is discussed. The primary objective was to collect a sample of undisturbed comet material from beneath the surface of an active comet and to preserve its chemical and, if possible, its physical integrity and return it to Earth in a minimally altered state. The secondary objectives are to: (1) characterize the comet to a level consistent with a rendezvous mission; (2) monitor the comet dynamics through perihelion and aphelion with a long lived lander; and (3) determine the subsurface properties of the nucleus in an area local to the sampled core. A set of candidate comets is discussed. The hazards which the spacecraft would encounter in the vicinity of the comet are also discussed. The encounter strategy, the sampling hardware, the thermal control of the pristine comet material during the return to Earth, and the flight performance of various spacecraft systems and the cost estimates of such a mission are presented.

  4. Study of 16O(12C,α20Ne)α for the investigation of carbon-carbon fusion reaction via the Trojan Horse Method

    NASA Astrophysics Data System (ADS)

    Rapisarda, G. G.; Spitaleri, C.; Bordeanu, C.; Hons, Z.; Kiss, G. G.; La Cognata, M.; Mrazek, J.; Nita, C.; Pantelica, D.; Petrascu, H.; Pizzone, R. G.; Romano, S.; Szücs, T.; Trache, L.; Tumino, A.; Velisa, G.

    2016-04-01

    Carbon-carbon fusion reaction represents a nuclear process of great interest in astrophysics, since the carbon burning is connected with the third phase of massive stars (M > 8 M⊙) evolution. In spite of several experimental works, carbon-carbon cross section has been measured at energy still above the Gamow window moreover data at low energy present big uncertainty. In this paper we report the results about the study of the 16O(12C,α 20Ne)α reaction as a possible three-body process to investigate 12C(12C,α)20Ne at astrophysical energy via Trojan Horse Method (THM). This study represents the first step of a program of experiments aimed to measure the 12C+12C cross section at astrophysical energy using the THM.

  5. The {sup 12}C({alpha}, {gamma}){sup 16}O E2 cross section at stellar energies

    SciTech Connect

    Descouvemont, P.; Dufour, M.

    2010-08-12

    The E2 component of the {sup 12}C({alpha}, {gamma}){sup 16}O cross section is investigated by a microscopic cluster model, and by R-matrix fits. The first approach provides S{sub E2}(300 keV){approx_equal}50 keV-b for ground-state transitions. In the R-matrix theory, we show that the background term plays a crucial role, and cannot be determined without ambiguity. Only an upper limit on the extrapolated S factor can be obtained [S{sub E2}(300 keV)<190 keV-b]. To constrain the R-matrix analysis, we use the GCM Asymptotic Normalization Constant (ANC) of the 2{sub 1}{sup +} level. This procedure strongly reduces the uncertainties on the R-matrix fit, and we end up with a recommended value of S{sub E2}(300 keV) =42{+-}2 keV-b. As ANC values derived from indirect methods are not consistent with the {sup 12}C({alpha}, {gamma}){sup 16}O cascade transitions to the 2{sub 1}{sup +} state, we suggest a remeasurement of this cross section.

  6. Particle gamma correlations in 12C measured with the CsI(Tl) based detector array CHIMERA

    NASA Astrophysics Data System (ADS)

    Cardella, G.; Acosta, L.; Amorini, F.; Auditore, L.; Berceanu, I.; Castoldi, A.; De Filippo, E.; Dell`Aquila, D.; Francalanza, L.; Gnoffo, B.; Guazzoni, C.; Lanzalone, G.; Lombardo, I.; Minniti, T.; Morgana, E.; Norella, S.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Pop, A.; Quattrocchi, L.; Rizzo, F.; Rosato, E.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Vigilante, M.

    2015-11-01

    The gamma decay of the first excited 4.44 MeV 2+level of 12C, populated by inelastic scattering of proton and 16O beams at various energies was studied in order to test γ-ray detection efficiency and the quality of angular distribution information given by the CsI(Tl) detectors of the 4π CHIMERA array. The γ-decay was measured in coincidence with ejectile scattered particles in an approximately 4π geometry allowing to extract the angular distribution in the reference frame of recoiling 12C target. The typical sin2 (2θ) behavior of angular distribution was observed in the case of 16O beam. Besides that, for the proton beam, in order to explain the observed distribution, the addition of an incoherent flat contribution was required. This latter is the effect of proton spin flip events allowing the population of M=±1 magnetic substates, that is not possible in reactions induced by 16O beam. A comparison with previously collected data, obtained measuring only in and out of plane proton-γ-ray coincidences, confirms the good quality of the angular distribution information given by the apparatus. Possible applications with radioactive beams are outlined.

  7. Interpreting the 13C / 12C ratio of carbon dioxide in an urban airshed in the Yangtze River Delta, China

    NASA Astrophysics Data System (ADS)

    Xu, Jiaping; Lee, Xuhui; Xiao, Wei; Cao, Chang; Liu, Shoudong; Wen, Xuefa; Xu, Jingzheng; Zhang, Zhen; Zhao, Jiayu

    2017-03-01

    Observations of atmospheric CO2 mole fraction and the 13C / 12C ratio (expressed as δ13C) in urban airsheds provide constraints on the roles of anthropogenic and natural sources and sinks in local and regional carbon cycles. In this study, we report observations of these quantities in Nanjing at hourly intervals from March 2013 to August 2015, using a laser-based optical instrument. Nanjing is the second largest city located in the highly industrialized Yangtze River Delta (YRD), eastern China. The mean CO2 mole fraction and δ13C were (439.7 ± 7.5) µmol mol-1 and (-8.48 ± 0.56) ‰ over this observational period. The peak monthly mean δ13C (-7.44 ‰, July 2013) was 0.74 ‰ higher than that observed at Mount Waliguan, a WMO (World Meteorological Organization) baseline site on the Tibetan Plateau and upwind of the YRD region. The highly 13C-enriched signal was partly attributed to the influence of cement production in the region. By applying the Miller-Tans method to nighttime and daytime observations to represent signals from the city of Nanjing and the YRD, respectively, we showed that the 13C / 12C ratio of CO2 sources in the Nanjing municipality was (0.21 ± 0.53) ‰ lower than that in the YRD. Flux partitioning calculations revealed that natural ecosystems in the YRD were a negligibly small source of atmospheric CO2.

  8. A capillary absorption spectrometer for stable carbon isotope ratio (13C/12C) analysis in very small samples

    NASA Astrophysics Data System (ADS)

    Kelly, J. F.; Sams, R. L.; Blake, T. A.; Newburn, M.; Moran, J.; Alexander, M. L.; Kreuzer, H.

    2012-02-01

    A capillary absorption spectrometer (CAS) suitable for IR laser isotope analysis of small CO2 samples is presented. The system employs a continuous-wave (cw) quantum cascade laser to study nearly adjacent rovibrational transitions of different isotopologues of CO2 near 2307 cm-1 (4.34 μm). This initial CAS system can achieve relative isotopic precision of about 10 ppm 13C, or ˜1‰ (per mil in delta notation relative to Vienna Pee Dee Belemnite) with 20-100 picomoles of entrained sample within the hollow waveguide for CO2 concentrations ˜400-750 ppm. Isotopic analyses of such gas fills in a 1-mm ID hollow waveguide of 0.8 m overall physical path length can be carried out down to ˜2 Torr. Overall 13C/12C ratios can be calibrated to ˜2‰ accuracy with diluted CO2 standards. A novel, low-cost method to reduce cw-fringing noise resulting from multipath distortions in the hollow waveguide is presented, which allows weak absorbance features to be studied at the few ppm level (peak-to-rms) after 1000 scans are co-added in ˜10 s. The CAS is meant to work directly with converted CO2 samples from a laser ablation-catalytic combustion micro-sampler to provide 13C/12C ratios of small biological isolates currently operating with spatial resolutions ˜50 μm.

  9. Theoretical investigation of stabilities and optical properties of Si{sub 12}C{sub 12} clusters

    SciTech Connect

    Duan, Xiaofeng F.; Burggraf, Larry W.

    2015-01-21

    By sorting through hundreds of globally stable Si{sub 12}C{sub 12} isomers using a potential surface search and using simulated annealing, we have identified low-energy structures. Unlike isomers knit together by Si–C bonds, the lowest energy isomers have segregated carbon and silicon regions that maximize stronger C–C bonding. Positing that charge separation between the carbon and silicon regions would produce interesting optical absorption in these cluster molecules, we used time-dependent density functional theory to compare the calculated optical properties of four isomers representing structural classes having different types of silicon and carbon segregation regions. Absorptions involving charge transfer between segregated carbon and silicon regions produce lower excitation energies than do structures having alternating Si–C bonding for which frontier orbital charge transfer is exclusively from separated carbon atoms to silicon atoms. The most stable Si{sub 12}C{sub 12} isomer at temperatures below 1100 K is unique as regards its high symmetry and large optical oscillator strength in the visible blue. Its high-energy and low-energy visible transitions (1.15 eV and 2.56 eV) are nearly pure one-electron silicon-to-carbon transitions, while an intermediate energy transition (1.28 eV) is a nearly pure carbon-to-silicon one-electron charge transfer.

  10. Survival of orbiting in {sup 20}Ne (7-10 MeV/nucleon) + {sup 12}C reactions

    SciTech Connect

    Bhattacharya, C.; Dey, A.; Kundu, S.; Banerjee, K.; Bhattacharya, S.; Mukhopadhyay, S.; Gupta, D.; Bhattacharjee, T.; Banerjee, S.R.; Bhattacharyya, S.; Rana, T.; Basu, S.K.; Saha, R.; Bhattacharjee, S.; Krishan, K.; Mukherjee, A.; Bandopadhyay, D.; Beck, C.

    2005-08-01

    The inclusive energy distributions of fragments with Z {>=} 3 emitted from the bombardment of {sup 12}C by {sup 20}Ne beams with incident energies between 145 and 200 MeV have been measured in the angular range {theta}{sub lab}{approx}10 deg. -50 deg. Damped fragment yields in all cases have been found to be characteristic of emission from fully energy equilibrated composites; for B and C fragments, average Q values, , were independent of the center-of-mass emission angle ({theta}{sub c.m.}), and the angular distributions followed a {approx}1/sin{theta}{sub c.m.}-like variation, signifying long lifetimes of the emitting dinuclear systems. Estimates of total yields of these fragments have been found to be much larger than those predicted by the standard statistical model. This may be indicative of the survival of an orbiting-like process in the {sup 12}C+{sup 20}Ne system at these energies.

  11. A comparative study on radioprotective effect of N-acetylcysteine against 12C6+ ion versus X-rays

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Zhang, Hong; Zhang, Luwei

    Purpose: The aim of this study was to evaluate the different protective efficacy of N-acetylcysteine (NAC, 200 mg/kg dose) against 12C6+ ion (4 Gy) and X-rays (4 Gy) - induced damage in vivo model. Method: Kung-Ming female mice were divided into six groups, each composed of twelve animals: control group, two irradiation groups, and two NAC-treated groups, as well as NAC alone-treated group. An acute study was carried out to determine alterations in the oxidative stress (malondialdehyde level) using with colorimetric method and cell apoptosis measuring by flow cytometry as well as DNA-single strand break analyzing by comet assay at 2h after irradiation in mouse liver. Results: Compared with respective irradiation group, NAC can significantly ameliorate injury induced by two types of ionizing irradiation, which marked by the decrease of malondialdehyde level, and the reduction of apoptosis cells percentage and DNA damage. But the greater efficacy of NAC was prominently observed to inhibit the damage induced by X-rays, suggesting that NAC-mediated protective effect is more advisable to X-rays than 12C6+ ion irradiation. Moreover, NAC treatment alone did not result in any damage as compared to the control group. Conclusion: NAC may merit development as a potential radioprotective agent. Furthermore, NAC might exert its best effort to respond X rays-caused damage.

  12. Strain improvement of Trichoderma viride for increased cellulase production by irradiation of electron and (12)C(6+)-ion beams.

    PubMed

    Li, Zhaozhou; Chen, Xiujin; Li, Zhili; Li, Daomin; Wang, Yao; Gao, Hongli; Cao, Li; Hou, Yuze; Li, Songbiao; Liang, Jianping

    2016-06-01

    To improve cellulase production and activity, Trichoderma viride GSICC 62010 was subjected to mutation involving irradiation with an electron beam and subsequently with a (12)C(6+)-ion beam. Mutant CIT 626 was the most promising cellulase producer after preliminary and secondary screening. Soluble protein production and cellulase activities were increased mutifold. The optimum temperature, pH and culture time for the maximum cellulase production of the selected mutant were 35 °C, pH 5 and 6 days. The highest cellulase production was obtained using wheat bran. The prepared cellulases from T. viride CIT 626 had twice the hydrolytic performance with sawdust (83 %) than that from the parent strain (42.5 %). Furthermore, molecular studies demonstrated that there were some key mutation sites suggesting that some amino acid changes in the protein caused by base mutations had led to the enhanced cellulase production and activity. Mutagenesis with electron and (12)C(6+)-ion beams could be developed as an effective tool for improvement of cellulase producing strains.

  13. Determination of 13C/12C Isotope Ratio in Alcohols of Different Origin by 1н Nuclei NMR-Spectroscopy

    NASA Astrophysics Data System (ADS)

    Dzhimak, S. S.; Basov, A. A.; Buzko, V. Yu.; Kopytov, G. F.; Kashaev, D. V.; Shashkov, D. I.; Shlapakov, M. S.; Baryshev, M. G.

    2017-02-01

    A new express method of indirect assessment of 13C/12C isotope ratio on 1H nuclei is developed to verify the authenticity of ethanol origin in alcohol-water-based fluids and assess the facts of various alcoholic beverages falsification. It is established that in water-based alcohol-containing systems, side satellites for the signals of ethanol methyl and methylene protons in the NMR spectra on 1H nuclei, correspond to the protons associated with 13C nuclei. There is a direct correlation between the intensities of the signals of ethanol methyl and methylene protons' 1H- NMR and their side satellites, therefore, the data obtained can be used to assess 13C/12C isotope ratio in water-based alcohol-containing systems. The analysis of integrated intensities of main and satellite signals of methyl and methylene protons of ethanol obtained by NMR on 1H nuclei makes it possible to differentiate between ethanol of synthetic and natural origin. Furthermore, the method proposed made it possible to differentiate between wheat and corn ethanol.

  14. Measurements and Modeling of 16O12C17O Spectroscopic Parameters at 2 μm

    NASA Astrophysics Data System (ADS)

    Jacquemart, David; Sung, Keeyoon; Brown, Linda; Coleman, Max; Mantz, Arlan; Smith, Mary Ann H.

    2014-06-01

    Nearly 1000 line intensities of 16O12C17O between 4604 and 5126 wn were measured using an isotopically-enriched mixture sample having 40 % (determined by mass spectrometry). Spectra were recorded at 0.0056 wn resolution with a Fourier transform spectrometer (Bruker IFS-125HR at JPL) configured to a Herriott cell with a 20.946 m absorption path. Since collisional narrowing effects were observed, the Rautian profile was systematically applied (instead of the Voigt profile) using a multispectrum retrieval procedure. Transition dipole moments and Herman-Wallis factors were derived for 15 bands, and a global comparison with theoretical calculations and predictions was obtained. Accuracies for the line intensities ranged between 2 - 3 % for strong bands and 6 - 30 % for weak bands. Retrieved line positions were calibrated using CO, HCl and some well-known 16O12C16O transitions. For both measured and calculated line positions, the accuracies fell between 0.1 - 1×10-3 wn. Self-broadening was also obtained for a few bands. Complete line lists were generated to support atmospheric remote sensing of the Earth (e.g., OCO-2 mission), Mars and Venus. Research described in this paper was performed at Connecticut College, the Jet Propulsion Laboratory, and California Institute of Technology, and NASA Langley Research Center, under contracts and cooperative agreements with the National Aeronautics and Space Administration.

  15. Integral measurement of the 12C(n, p)12B reaction up to 10 GeV

    NASA Astrophysics Data System (ADS)

    Žugec, P.; Colonna, N.; Bosnar, D.; Ventura, A.; Mengoni, A.; Altstadt, S.; Andrzejewski, J.; Audouin, L.; Barbagallo, M.; Bécares, V.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Boccone, V.; Brugger, M.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Carrapiço, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Cortés, G.; Cortés-Giraldo, M. A.; Cosentino, L.; Diakaki, M.; Domingo-Pardo, C.; Dressler, R.; Duran, I.; Eleftheriadis, C.; Ferrari, A.; Finocchiaro, P.; Fraval, K.; Ganesan, S.; García, A. R.; Giubrone, G.; Gómez-Hornillos, M. B.; Gonçalves, I. F.; González-Romero, E.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Gurusamy, P.; Heinitz, S.; Jenkins, D. G.; Jericha, E.; Käppeler, F.; Karadimos, D.; Kivel, N.; Kokkoris, M.; Krtička, M.; Kroll, J.; Langer, C.; Lederer, C.; Leeb, H.; Leong, L. S.; Lo Meo, S.; Losito, R.; Manousos, A.; Marganiec, J.; Martínez, T.; Massimi, C.; Mastinu, P.; Mastromarco, M.; Mendoza, E.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Mondalaers, W.; Musumarra, A.; Paradela, C.; Pavlik, A.; Perkowski, J.; Plompen, A.; Praena, J.; Quesada, J.; Rauscher, T.; Reifarth, R.; Riego, A.; Roman, F.; Rubbia, C.; Sarmento, R.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Tagliente, G.; Tain, J. L.; Tarrío, D.; Tassan-Got, L.; Tsinganis, A.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Versaci, R.; Vermeulen, M. J.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Weigand, M.; Weiß, C.; Wright, T.

    2016-04-01

    The integral measurement of the 12C(n, p)12B reaction was performed at the neutron time-of-flight facility n_TOF at CERN. The total number of 12B nuclei produced per neutron pulse of the n_TOF beam was determined using the activation technique in combination with a time-of-flight technique. The cross section is integrated over the n_TOF neutron energy spectrum from reaction threshold at 13.6MeV to 10GeV. Having been measured up to 1GeV on basis of the 235U(n, f ) reaction, the neutron energy spectrum above 200MeV has been re-evaluated due to the recent extension of the cross section reference for this particular reaction, which is otherwise considered a standard up to 200MeV. The results from the dedicated GEANT4 simulations have been used to evaluate the neutron flux from 1GeV up to 10GeV. The experimental results related to the 12C(n, p)12B reaction are compared with the evaluated cross sections from major libraries and with the predictions of different GEANT4 models, which mostly underestimate the 12B production. On the contrary, a good reproduction of the integral cross section derived from measurements is obtained with TALYS-1.6 calculations, with optimized parameters.

  16. High precision measurements of 16O12C17O using a new type of cavity ring down spectrometer

    NASA Astrophysics Data System (ADS)

    Daëron, M.; Stoltmann, T.; Kassi, S.; Burkhart, J.; Kerstel, E.

    2016-12-01

    Laser absorption techniques for the measurement of isotopologue abundances in gases have been dripping into the geoscientific community over the past decade. In the field of carbon dioxide such instruments have mostly been restricted to measurements of the most abundant stable isotopologues. Distinct advantages of CRDS techniques are non-destructiveness and the ability to resolve isobaric isotopologues. The determination of low-abundance isotopologues is predominantly limited by the linewidth of the probing laser, laser jitter, laser drift and system stability. Here we present first measurements of 16O12C17O abundances using a new type of ultra-precise cavity ring down spectrometer. By the use of Optical Feedback Frequency Stabilization, we achieved a laser line width in the sub-kHz regime with a frequency drift of less than 20 Hz/s. A tight coupling with an ultra-stable ring down cavity combined with a frequency tuning mechanism which enables us to arbitrarily position spectral points (Burkart et al., 2013) allowed us to demonstrate a single-scan (2 minutes) precision of 40 ppm on the determination of the 16O12C17O abundance. These promising results imply that routine, direct, high-precision measurements of 17O-anomalies in CO2 using this non-destructive method are in reach. References:Burkart J, Romanini D, Kassi S; Optical feedback stabilized laser tuned by single-sideband modulation; Optical Letters 12:2062-2063 (2013)

  17. Effective source size, radial, angular and energy spread of therapeutic 11C positron emitter beams produced by 12C fragmentation

    NASA Astrophysics Data System (ADS)

    Lazzeroni, Marta; Brahme, Anders

    2014-02-01

    The use of positron emitter light ion beams in combination with PET (Positron Emission Tomography) and PET-CT (Computed Tomography) imaging could significantly improve treatment verification and dose delivery imaging during radiation therapy. The present study is dedicated to the analysis of the beam quality in terms of the effective source size, as well as radial, angular and energy spread of the 11C ion beam produced by projectile fragmentation of a primary point monodirectional and monoenergetic 12C ion beam in a dedicated range shifter of different materials. This study was performed combining analytical methods describing the transport of particles in matter and the Monte Carlo code SHIELD-HIT+. A high brilliance and production yield of 11C fragments with a small effective source size and emittance is best achieved with a decelerator made of two media: a first liquid hydrogen section of about 20 cm followed by a hydrogen rich section of variable length. The calculated intensity of the produced 11C ion beam ranges from about 5% to 8% of the primary 12C beam intensity depending on the exit energy and the acceptance of the beam transport system. The angular spread is lower than 1 degree for all the materials studied, but the brilliance of the beam is the highest with the proposed mixed decelerator.

  18. Theoretical antideuteron-nucleus absorptive cross sections

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    Antideuteron-nucleus absorptive cross sections for intermediate to high energies are calculated using an ion-ion optical model. Good agreement with experiment (within 15 percent) is obtained in this same model for (bar p)-nucleus cross sections at laboratory energies up to 15 GeV. We describe a technique for estimating antinucleus-nucleus cross sections from NN data and suggest that further cosmic ray studies to search for antideuterons and other antinuclei be undertaken.

  19. Oocyte nucleus controls progression through meiotic maturation.

    PubMed

    Polanski, Zbigniew; Hoffmann, Steffen; Tsurumi, Chizuko

    2005-05-15

    We analyzed progression through the meiotic maturation in oocytes manipulated to replace the prophase oocyte nucleus with the nucleus from a cumulus cell, a pachytene spermatocyte or the pronucleus from a fertilized egg. Removal of the oocyte nucleus led to a significant reduction in histone H1 kinase activity. Replacement of the oocyte nucleus by a pronucleus followed by culture resulted in premature pseudomeiotic division and occasional abnormal cytokinesis; however, histone H1 kinase activity was rescued, microtubules formed a bipolar spindle, and chromosomes were condensed. In addition to the anomalies observed after pronuclear transfer, those after transfer of the nucleus from a cumulus cell or spermatocyte included a dramatically impaired ability to form the bipolar spindle or to condense chromosomes, and histone H1 kinase activity was not rescued. Expression of a cyclin B-YFP in enucleated oocytes receiving the cumulus cell nucleus rescued histone H1 kinase activity, but spindle formation and chromosome condensation remained impaired, indicating a pleiotropic effect of oocyte nucleus removal. However, when the cumulus cell nucleus was first transformed into pronuclei (transfer into a metaphase II oocyte followed by activation), such pronuclei supported maturation after transfer into the oocyte in a manner similar to that of normal pronuclei. These results show that the oocyte nucleus contains specific components required for the control of progression through the meiotic maturation and that some of these components are also present in pronuclei.

  20. Projections from the cochlear nucleus to the superior paraolivary nucleus in guinea pigs.

    PubMed

    Schofield, B R

    1995-09-11

    Axonal tracing techniques were used to study the projection from the cochlear nucleus to the superior paraolivary nucleus in guinea pigs. Different tracers were used to identify the cell types that give rise to the projections, the morphology of their axons, and the cell types that they contact in the superior paraolivary nucleus. Injections of Fluoro-Gold or peroxidase-labeled-WGA and HRP into the superior paraolivary nucleus labeled multipolar cells and octopus cells bilaterally in the ventral cochlear nucleus, mainly on the contralateral side. Injections of PHAL into the ventral cochlear nucleus labeled two types of axons in the superior paraolivary nucleus. Thin axons branch infrequently and give rise primarily to small, en passant boutons. Thick axons have larger boutons, many of which are terminal boutons that arise from short collaterals. Thin axons appear to originate from multipolar cells, whereas thick axons probably originate from octopus cells. Both types are found bilaterally after an injection into the ventral cochlear nucleus on one side. Individual thick or thin axons may contact multiple cell types in the superior paraolivary nucleus. Individual cells in the superior paraolivary nucleus can receive convergent input from both thick and thin axons. Combined anterograde and retrograde transport of different fluorescent tracers was used to identify the projections of the cells in the superior paraolivary nucleus that receive inputs from the ventral cochlear nucleus. Cells in the superior paraolivary nucleus that projected to the ipsilateral cochlear nucleus or to the ipsilateral inferior colliculus appeared to be contacted by axons that were labeled by anterograde transport from the contralateral ventral cochlear nucleus. Thus the projections to the superior paraolivary nucleus are in a position to affect the activity in both ascending and descending auditory pathways.

  1. Projections from the central amygdaloid nucleus to the precuneiform nucleus in the mouse.

    PubMed

    Liang, Huazheng; Watson, Charles; Paxinos, George

    2015-01-01

    The mouse precuneiform nucleus has been proposed as the midbrain locomotion center, a function ascribed to its caudal neighbor, cuneiform nucleus, in the rat, cat and other species. The present study investigated the projections from the central amygdaloid nucleus to the precuneiform nucleus in the mouse using retrograde tracer injections (fluoro-gold) into the precuneiform nucleus and anterograde tracer injections (biotinylated dextran amine) into the central amygdaloid nucleus. The entire central amygdaloid nucleus except the rostral pole had retrogradely labeled neurons, especially in the middle portion where labeled neurons were densely packed. Anterogradely labeled amygdaloid fibers approached the precuneiform nucleus from the area ventrolateral to it and terminated in the entire precuneiform nucleus. Labeled fibers were also found in laminae 5 and 6 in the upper cervical cord on the ipsilateral side. The present study is the first demonstration of projections from the central amygdaloid nucleus to the precuneiform nucleus. This projection may underpin the role of the precuneiform nucleus in the modulation of the cardiovascular activity.

  2. The extended chain compounds Ln12(C 2) 3I 17 ( Ln=Pr, Nd, Gd, Dy): Synthesis, structure and physical properties

    NASA Astrophysics Data System (ADS)

    Ryazanov, Mikhail; Mattausch, Hansjürgen; Simon, Arndt

    2007-04-01

    The title compounds are obtained in high yield from stoichiometric mixtures of Ln, LnI 3 and graphite, heated at 900-950 °C in welded Ta containers. The crystal structures of new Pr and Nd phases determined by single-crystal X-ray diffraction are related to those of other Ln12(C 2) 3I 17-type compounds ( C 2/ c, a=19.610(1) and 19.574(4) Å, b=12.406(2) and 12.393(3) Å, c=19.062(5) and 19.003(5) Å, β=90.45(3)° and 90.41(3)°, for Pr 12(C 2) 3I 17 and Nd 12(C 2) 3I 17, respectively). All compounds contain infinite zigzag chains of C 2-centered metal atom octahedra condensed by edge-sharing into the [tcc] ∞ sequence (c= cis, t= trans) and surrounded by edge-bridging iodine atoms as well as by apical iodine atoms that bridge between chains. The polycrystalline Gd 12(C 2) 3I 17 sample exhibits semiconducting thermal behavior which is consistent with an ionic formulation ( Ln3+) 12(C 26-) 3(I -) 17(e -) under the assumption that one extra electron is localized in metal-metal bonding. The magnetization measurements on Nd 12(C 2) 3I 17, Gd 12(C 2) 3I 17 and Dy 12(C 2) 3I 17 indicate the coexistence of competing magnetic interactions leading to spin freezing at Tf=5 K for the Gd phase. The Nd and Dy compounds order antiferromagnetically at TN=25 and 29 K, respectively. For Dy 12(C 2) 3I 17, a metamagnetic transition is observed at a critical magnetic field H≈25 kOe.

  3. Ab initio calculation of the electromagnetic and neutral-weak response functions of 4He and 12C

    SciTech Connect

    Lovato, A.; Benhar, O.; Carlson, J.; Gandalfi, S.; Pieper, S.; Rocco, N.; Schiavilla, Rocco

    2016-03-01

    Precise measurement of neutrino oscillations, and hence the determination of their masses demands a quantitative understanding of neutrino-nucleus interactions. To this aim, two-body meson-exchange currents have to be accounted for along within realistic models of nuclear dynamics. We summarize our progresses towards the construction of a consistent framework, based on quantum Monte Carlo methods and on the spectral function approach, that can be exploited to accurately describe neutrino interactions with atomic nuclei over the broad kinematical region covered by neutrino experiments.

  4. LASER BIOLOGY AND MEDICINE: Laser analysis of the 13C/12C isotope ratio in CO2 in exhaled air

    NASA Astrophysics Data System (ADS)

    Stepanov, E. V.

    2002-11-01

    Tunable diode lasers (TDLs) are applied to the diagnostics of gastroenterological diseases using respiratory tests and preparations enriched with the stable 13C isotope. This method of the analysis of the 13C/12C isotope ratio in CO2 in exhaled air is based on the selective measurement of the resonance absorption at the vibrational — rotational structure of 12CO2 and 13CO2. The CO2 transmission spectra in the region of 4.35 μm were measured with a PbEuSe double-heterostructure TDL. The accuracy of carbon isotope ratio measurements in CO2 of exhaled air performed with the TDL was ~0.5%. The data of clinical tests of the developed laser-based analyser are presented.

  5. Low-energy cross sections in the {sup 12}C({alpha},{gamma}){sup 16}O reaction

    SciTech Connect

    Katsuma, M.

    2008-09-15

    The low-energy {sup 12}C({alpha},{gamma}){sup 16}O reaction is analyzed with the potential model. The potentials are chosen from the deep potential describing the {alpha}-particle nuclear rainbow phenomena at high energies. Below E{sub c.m.}=1 MeV, the cross section is found to be dominated by the E2 transition to the ground state of {sup 16}O. No enhancement of the E1 component at low energies is predicted. The extrapolated astrophysical S-factors at E{sub c.m.}=0.3 MeV are S{sub E2}=150 keV b and S{sub E1}=3 keV b.

  6. Effect of compound nuclear reaction mechanism in 12C(6Li,d) reaction at sub-Coulomb energy

    NASA Astrophysics Data System (ADS)

    Mondal, Ashok; Adhikari, S.; Basu, C.

    2017-09-01

    The angular distribution of the 12C(6Li,d) reaction populating the 6.92 and 7.12 MeV states of 16O at sub-Coulomb energy (Ecm=3 MeV) are analysed in the framework of the Distorted Wave Born Approximation (DWBA). Recent results on excitation function measurements and backward angle angular distributions derive ANC for both the states on the basis of an alpha transfer mechanism. In the present work, we show that considering both forward and backward angle data in the analysis, the 7.12 MeV state at sub-Coulomb energy is populated from Compound nuclear process rather than transfer process. The 6.92 MeV state is however produced from direct reaction mechanism.

  7. Alpha clustering and nuclear molecules in8Be, 12C, 16O, 20Ne, 24Mg, and32S

    NASA Astrophysics Data System (ADS)

    Royer, G.; Eudes, P.

    2017-06-01

    Within a liquid drop model the energy of the12C,16O,20Ne,24Mg and32S 4n-nuclei has been calculated within different configurations of α-molecules : linear chain, triangle, square, tetrahedron, pentagon, trigonal bipyramid, square pyramid, hexagon, octahedron, octagon and cube. The potential barriers governing the decay and entrance channels via α emission or absorption as well as the potential barriers of other possible binary and ternary reactions have been compared. The rms radii of the linear chains do not correspond to the experimental rms radii of the ground states. The binding energies of the three-dimensional molecules at the nascent point of the fragments are higher than the ones of the planar configurations. The A-4 daughter plus α particle configurations have always the lowest potential energy.

  8. Precise Branching Ratios to Unbound 12C States from 12N and 12B (beta)-Decays

    SciTech Connect

    Hyldegaard, S; Forssen, C; Alcorta, M; Barker, F C; Bastin, B; Borge, M G; Boutami, R; Brandenburg, S; Buscher, J; Dendooven, P; Diget, C A; Van Duppen, P; Eronen, T; Fox, S; Fulton, B R; Fynbo, H U; Huikari, J; Huyse, M; Jeppesen, H B; Jokinen, A; Jonson, B; Jungmann, K; Kankainen, A; Kirsebom, O; Madurga, M; Moore, I; Navratil, P; Nilsson, T; Nyman, G; Onderwater, G G; Penttila, H; Perajarvi, K; Raabe, R; Riisager, K; Rinta-Antila, S; Rogachevskiy, A; Saastamoinen, A; Sohani, M; Tengblad, O; Traykov, E; Vary, J P; Wang, Y; Wilhelmsen, K; Wilschut, H W; Aysto, J

    2008-08-20

    Two complementary experimental techniques have been used to extract precise branching ratios to unbound states in {sup 12}C from {sup 12}N and {sup 12}B {beta}-decays. In the first the three {alpha}-particles emitted after {beta}-decay are measured in coincidence in separate detectors, while in the second method {sup 12}N and {sup 12}B are implanted in a detector and the summed energy of the three {alpha}-particles is measured directly. For the narrow states at 7.654 MeV (0{sup +}) and 12.71 MeV (1{sup +}) the resulting branching ratios are both smaller than previous measurements by a factor of {approx_equal} 2. The experimental results are compared to no-core shell model calculations with realistic interactions from chiral perturbation theory, and inclusion of three-nucleon forces is found to give improved agreement.

  9. Experimental controls on D/H and 13C/12C ratios of kerogen, bitumen and oil during hydrous pyrolysis

    USGS Publications Warehouse

    Schimmelmann, A.; Boudou, J.-P.; Lewan, M.D.; Wintsch, R.P.

    2001-01-01

    Large isotopic transfers between water-derived hydrogen and organic hydrogen occurred during hydrous pyrolysis experiments of immature source rocks, in spite of only small changes in organic 13C/12C. Experiments at 330 ??C over 72 h using chips or powder containing kerogen types I and III identify the rock/water ratio as a main factor affecting ????D for water and organic hydrogen. Our data suggest that larger rock permeability and smaller rock grain size increase the H-isotopic transfer between water-derived hydrogen and thermally maturing organic matter. Increasing hydrostatic pressure may have a similar effect, but the evidence remains inconclusive. ?? 2001 Elsevier Science Ltd. All rights reserved.

  10. The Rovibrational Intensities of Five Absorption Bands of (12)C(16)O2 Between 5218 and 5349/cm

    NASA Technical Reports Server (NTRS)

    Giver, Lawrence P.; Brown, Linda R.; Chackerian, Charles, Jr.; Freedman, Richard S.; Gore, Warren J. (Technical Monitor)

    2002-01-01

    Absolute line intensities, band intensities, and Herman-Wallis parameters were measured for the (01(sup 1)2)(sub I) from (00(sup 0)0)(sub I) perpendicular band of (12)C(16)O2 centered at 5315/cm, along with the three nearby associated hot bands: (10(sup 0)2)(sub II) from (01(sup 1)0)(sub I) at 5248/cm, (02(sup 2))(sub I) from (01(sup 1)0)(sub I) at 5291/cm, and (10(sup 0)2)(sub I) from (01(sup 1)0)(sub I) at 5349/cm. The nearby parallel hot band (30(sup 0))(sub I) from (10(sup 0)0)(sub II) at 5218/cm was also included in this study.

  11. Precise branching ratios to unbound 12C states from 12N and 12B β-decays

    NASA Astrophysics Data System (ADS)

    Hyldegaard, S.; Forssén, C.; Diget, C. Aa.; Alcorta, M.; Barker, F. C.; Bastin, B.; Borge, M. J. G.; Boutami, R.; Brandenburg, S.; Büscher, J.; Dendooven, P.; Van Duppen, P.; Eronen, T.; Fox, S.; Fulton, B. R.; Fynbo, H. O. U.; Huikari, J.; Huyse, M.; Jeppesen, H. B.; Jokinen, A.; Jonson, B.; Jungmann, K.; Kankainen, A.; Kirsebom, O.; Madurga, M.; Moore, I.; Navrátil, P.; Nilsson, T.; Nyman, G.; Onderwater, G. J. G.; Penttilä, H.; Peräjärvi, K.; Raabe, R.; Riisager, K.; Rinta-Antila, S.; Rogachevskiy, A.; Saastamoinen, A.; Sohani, M.; Tengblad, O.; Traykov, E.; Vary, J. P.; Wang, Y.; Wilhelmsen, K.; Wilschut, H. W.; Äystö, J.

    2009-08-01

    Two complementary experimental techniques have been used to extract precise branching ratios to unbound states in 12C from 12N and 12B β-decays. In the first the three α-particles emitted after β-decay are measured in coincidence in separate detectors, while in the second method 12N and 12B are implanted in a detector and the summed energy of the three α-particles is measured directly. For the narrow states at 7.654 MeV (0+) and 12.71 MeV (1+) the resulting branching ratios are both smaller than previous measurements by a factor of ≃2. The experimental results are compared to no-core shell model calculations with realistic interactions from chiral perturbation theory, and inclusion of three-nucleon forces is found to give improved agreement.

  12. Quasielastic knockout of light fragments from {sup 12}C and {sup 16}O nuclei by intermediate-energy pions

    SciTech Connect

    Abramov, B. M.; Borodin, Yu. A.; Bulychjov, S. A.; Dukhovskoy, I. A.; Krutenkova, A. P.; Kulikov, V. V. Martemianov, M. A.; Matsuk, M. A.; Tarasov, V. E.; Turdakina, E. N.; Khanov, A. I.

    2007-07-15

    Quasielastic deuteron and triton knockout from {sup 12}C and {sup 16}O nuclei has been studied infull kinematics using a 0.72-GeV/c pion beam. The momentum distributions of the intranuclear quasideuteron motion, excitation-energy spectra of the residual nuclei, and the effective numbers N{sub d}{sup eff} of quasideuterons are determined. The parameters of the quasideuteron intranuclear motion are in reasonable agreement with the results obtained in other beams. The N{sub d}{sup eff} in the nuclei from {sup 6}Li to {sup 16}O measured in full kinematics are virtually independent of the atomic number in contrast to the analogous values in the inclusive deuteron-knockout reaction induced by protons. The phenomenon of triton knockout from these nuclei is observed, which makes possible estimation of the cross section of backward pion-triton elastic scattering in yet unexplored regions of energy and momentum transfer.

  13. Vibration-rotation spectroscopic database on acetylene, X ˜ 1 Σg + (12C2H2)

    NASA Astrophysics Data System (ADS)

    Amyay, B.; Fayt, A.; Herman, M.; Vander Auwera, J.

    2016-06-01

    A complete set of calculated vibration-rotation energies of 12C2H2 ( X ˜ 1 Σg + ) is provided for all vibrational states up to 13 000 cm-1 and some at higher energies, with rotational (J) and vibrational angular momentum (l) quantum numbers such that 0 ≤ J ≤ 100 and 0 ≤ |l| ≤ 20, respectively. The calculation is performed using a global effective Hamiltonian and related spectroscopic constants from the literature [B. Amyay et al., J. Mol. Spectrosc. 267, 80 (2011)], based on the polyad model. The numerical values of all related polyad matrix elements are also provided. The model and equations for the Hamiltonian matrix elements are gathered. The experimental acetylene database used for determining the parameters is listed.

  14. An Investigation of 4He+12C and 4He+16O Reactions Using the Cluster Model

    NASA Astrophysics Data System (ADS)

    A. H., Al-Ghamdi; Awad, A. Ibraheem; M. El-Azab, Farid

    2012-07-01

    The α-target semimicroscopic single folding potentials have been derived by folding a composite (repulsive and attractive) effective α-α interaction with the α-cluster distribution density in the target nuclei. The obtained potentials are considered as the real part of the nuclear optical model potentials, while the imaginary parts are phenomenologicaly expressed using the Woods—Saxon form. Nine sets of measured experimental data of the 4He+12C and 4He+16O elastic rainbow scattering over the energy range 80-240 MeV are analyzed using the obtained potentials. The data are successfully reproduced using the extracted potentials. The resulted reaction cross sections are also investigated and compared with the available corresponding data.

  15. KRAS G12C Drug Development: Discrimination between Switch II Pocket Configurations Using Hydrogen/Deuterium-Exchange Mass Spectrometry.

    PubMed

    Lu, Jia; Harrison, Rane A; Li, Lianbo; Zeng, Mei; Gondi, Sudershan; Scott, David; Gray, Nathanael S; Engen, John R; Westover, Kenneth D

    2017-09-05

    KRAS G12C, the most common RAS mutation found in non-small-cell lung cancer, has been the subject of multiple recent covalent small-molecule inhibitor campaigns including efforts directed at the guanine nucleotide pocket and separate work focused on an inducible pocket adjacent to the switch motifs. Multiple conformations of switch II have been observed, suggesting that switch II pocket (SIIP) binders may be capable of engaging a range of KRAS conformations. Here we report the use of hydrogen/deuterium-exchange mass spectrometry (HDX MS) to discriminate between conformations of switch II induced by two chemical classes of SIIP binders. We investigated the structural basis for differences in HDX MS using X-ray crystallography and discovered a new SIIP configuration in response to binding of a quinazoline chemotype. These results have implications for structure-guided drug design targeting the RAS SIIP. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Improved determination of the astrophysical S(0) factor of the {sup 15}N(p,{alpha}){sup 12}C reaction

    SciTech Connect

    La Cognata, M.; Spitaleri, C.; Goldberg, V. Z.; Mukhamedzhanov, A. M.; Tribble, R. E.

    2009-07-15

    We present new improved R matrix fits of direct data and indirect Trojan Horse data for the {sup 15}N(p,{alpha}){sup 12}C reaction and provide a more accurate recommended value of S(0)=73.0{+-}5.0 MeV b from direct Redder data [A. Redder et al., Z. Phys. A 305, 325 (1982)] and S(0)=70.0{+-}13.5 MeV b from the Trojan Horse data [M. La Cognata et al., Phys. Rev. C 76, 065804 (2007)]. We also analyze a recent fit by Barker [F. C. Barker, Phys. Rev. C 78, 044611 (2008)] and demonstrate that when all the uncertainties are taken into account, our results overlap with his. We also provide a fit of the Trojan Horse data that properly takes into account finite residual energy resolution of the data.

  17. Particle emission in the light heavy-ion fusion reactions: 14N, 16,18O+ 12C

    NASA Astrophysics Data System (ADS)

    Carlin Filho, N.; Coimbra, M. M.; Acquadro, J. C.; Liguori Neto, R.; Szanto, E. M.; Farrelly-Pessoa, E.; Szanto de Toledo, A.

    1985-01-01

    From the energy spectra of light particles produced in light-heavy-ion-induced reactions, level densities of the final nuclei as well as the critical angular momenta for fusion may be obtained. The 14N, 16,18O+ 12C reactions were investigated in the energy range 30 MeV

  18. Reactions induced by 18 MeV 6He beam on 6Li, 7Li and 12C

    NASA Astrophysics Data System (ADS)

    Milin, M.; Cherubini, S.; Davinson, T.; Di Pietro, A.; Figuera, P.; Miljanić, Đ.; Musumarra, A.; Ninane, A.; Ostrowski, A. N.; Pellegriti, M. G.; Shotter, A. C.; Soić, N.; Spitaleri, C.; Zadro, M.

    2004-12-01

    The 6He+ 6,7Li and 6He+ 12C scattering and reactions have been studied using a 18 MeV 6He beam. Experimental results for the elastic scattering on all three targets are in fair agreement with optical model predictions, using the potentials found in the analysis of the 6Li scattering on the same targets and at close energies. Large cross sections are observed for α-transfer reactions to some states of 10Be. The sequential decay reactions 6He+ 6Li→ 6He+ α+ d, 6He+ 6Li→2 α+ t+ n, 6He+ 7Li→ 6He+ α+ t and 6He+ 12C→ 10Be+2 α were clearly seen and analysing them α-clustering of some states in 6Li, 7Li, 8Be, 9Be, 10Be and 14C was recognized.

  19. The nature of the cometary nucleus

    NASA Technical Reports Server (NTRS)

    Delsemme, A. H.

    1985-01-01

    The basic properties of the cometary nucleus are reviewed. Consideration is given to the absence of depth differentiation, the icy conglomerate nature, the possible existence of a halo of icy grains around the nuclear region, the nucleus size and albedo, the mass, the rotation rate, and the chemical composition (elemental and molecular).

  20. Theoretical Investigation Optical Properties of Si12C12 Clusters and Oligomers having Potential as Excitonic Materials

    NASA Astrophysics Data System (ADS)

    Duan, Xiaofeng; Burggraf, Larry

    2015-03-01

    SiC clusters may have potential in 2-D exciton circuits. We determined the most stable SinCn isomer structures (n <=12) out of hundreds to thousands isomers using a method combining Stochastic Potential Surface Search and Pseududopotential Plane-Wave Density Functional Theory Car-Parinello Molecular Dynamics simulated annealing (PSPW-CPMD-SA). Four low-energy Si12C12 isomer structures are discussed to illustrate the varying optical properties of clusters with structures: i) cage type with C- and Si- segregations, ii) symmetric type formed having π-stacked C aromatic rings and exterior Si regions, iii) nearly planar bowl with C fullerene fragment surrounded by Si atoms, and iv) symmetrical SiC cluster having alternate SiC bonding in the structure. We employed B3LYP and PBE0 functionals and both cc-pVTZ and aug-cc-pVTZ basis sets to perform TDDFT calculations of excitation energies and photo-absorption spectra to show how structure and bonding patterns affect photo excitations in different types of SiC clusters. The electron and the hole charge distribution patterns in excitation were calculated for major photoabsorption transitions, reported for the most stable isomer, closo Si12C12. To understand electric field effects we also calculated dynamical polarizabilities for all the four structures using Coupled Perturbed Hartree-Fock (CPHF) at B3LYP/aug-cc-pVTZ and PBE0/aug-cc-pVTZ level of theory. We gratefully acknowledge support from the Air Force Office of Scientific Research in a program managed by Dr Michael Berman.

  1. A Capillary Absorption Spectrometer for Stable Carbon Isotope Ratio (13C/12C) Analysis in Very Small Samples

    SciTech Connect

    Kelly, James F.; Sams, Robert L.; Blake, Thomas A.; Newburn, Matthew K.; Moran, James J.; Alexander, M. L.; Kreuzer, Helen W.

    2012-02-06

    A capillary absorption spectrometer (CAS) suitable for IR laser isotope analysis of small CO{sub 2} samples is presented. The system employs a continuous-wave (cw) quantum cascade laser to study nearly adjacent rovibrational transitions of different isotopologues of CO{sub 2} near 2307 cm{sup -1} (4.34 {mu}m). This initial CAS system can achieve relative isotopic precision of about 10 ppm {sup 13}C, or {approx}1{per_thousand} (per mil in delta notation relative to Vienna Pee Dee Belemnite) with 20-100 picomoles of entrained sample within the hollow waveguide for CO{sub 2} concentrations {approx}400 to 750 ppm. Isotopic analyses of such gas fills in a 1-mm ID hollow waveguide of 0.8 m overall physical path length can be carried out down to {approx}2 Torr. Overall {sup 13}C/{sup 12}C ratios can be calibrated to {approx}2{per_thousand} accuracy with diluted CO{sub 2} standards. A novel, low-cost method to reduce cw-fringing noise resulting from multipath distortions in the hollow waveguide is presented, which allows weak absorbance features to be studied at the few ppm level (peak-to-rms) after 1,000 scans are co-added in {approx}10 sec. The CAS is meant to work directly with converted CO{sub 2} samples from a Laser Ablation-Catalytic-Combustion (LA CC) micro-sampler to provide {sup 13}C/{sup 12}C ratios of small biological isolates with spatial resolutions {approx}50 {mu}m.

  2. Measurement of fragmentation cross sections of 12C ions on a thin gold target with the FIRST apparatus

    NASA Astrophysics Data System (ADS)

    Toppi, M.; Abou-Haidar, Z.; Agodi, C.; Alvarez, M. A. G.; Aumann, T.; Balestra, F.; Battistoni, G.; Bocci, A.; Böhlen, T. T.; Boudard, A.; Brunetti, A.; Carpinelli, M.; Cirio, R.; Cirrone, G. A. P.; Cortes-Giraldo, M. A.; Cuttone, G.; de Napoli, M.; Durante, M.; Fernández-García, J. P.; Finck, Ch.; Golosio, B.; Iarocci, E.; Iazzi, F.; Ickert, G.; Introzzi, R.; Juliani, D.; Krimmer, J.; Kummali, A. H.; Kurz, N.; Labalme, M.; Leifels, Y.; Le Fèvre, A.; Leray, S.; Marchetto, F.; Monaco, V.; Morone, M. C.; Nicolosi, D.; Oliva, P.; Paoloni, A.; Piersanti, L.; Pleskac, R.; Randazzo, N.; Rescigno, R.; Romano, F.; Rossi, D.; Rosso, V.; Rousseau, M.; Sacchi, R.; Sala, P.; Salvador, S.; Sarti, A.; Scheidenberger, C.; Schuy, C.; Sciubba, A.; Sfienti, C.; Simon, H.; Sipala, V.; Spiriti, E.; Tropea, S.; Vanstalle, M.; Younis, H.; Patera, V.; FIRST Collaboration

    2016-06-01

    A detailed knowledge of the light ions interaction processes with matter is of great interest in basic and applied physics. As an example, particle therapy and space radioprotection require highly accurate fragmentation cross-section measurements to develop shielding materials and estimate acute and late health risks for manned missions in space and for treatment planning in particle therapy. The Fragmentation of Ions Relevant for Space and Therapy experiment at the Helmholtz Center for Heavy Ion research (GSI) was designed and built by an international collaboration from France, Germany, Italy, and Spain for studying the collisions of a 12C ion beam with thin targets. The collaboration's main purpose is to provide the double-differential cross-section measurement of carbon-ion fragmentation at energies that are relevant for both tumor therapy and space radiation protection applications. Fragmentation cross sections of light ions impinging on a wide range of thin targets are also essential to validate the nuclear models implemented in MC simulations that, in such an energy range, fail to reproduce the data with the required accuracy. This paper presents the single differential carbon-ion fragmentation cross sections on a thin gold target, measured as a function of the fragment angle and kinetic energy in the forward angular region (θ ≲6° ), aiming to provide useful data for the benchmarking of the simulation softwares used in light ions fragmentation applications. The 12C ions used in the measurement were accelerated at the energy of 400 MeV/nucleon by the SIS (heavy ion synchrotron) GSI facility.

  3. Spin observables in quasi-elastic proton-nucleus scattering near 1 GeV

    SciTech Connect

    Smith, R.D.; Wallace, S.J.

    1985-11-01

    The spin dependence of quasi-elastic proton-nucleus scattering is studied using Glauber's eikonal multiple scattering theory, which is extended to include multiple knockout collisions as well as the full spin dependence of the NN amplitudes. Calculations of the cross section d/sup 2/sigma/d..cap omega.. dp and spin observables DNN, DLL, DSS, DSL, DLS, Ay are presented and compared to data for d/sup 2/sigma/d..cap omega.. dp and Ay from inclusive (p,p') experiments on /sup 12/C at T/sub lab/ = 800 MeV. The main feature seen is a drop in the spin observables in the kinematic region where two nucleon knockout dominates the cross section. As an initial study of the contribution of quasi-free ..delta.. production to the inclusive cross section, multiple scattering theory is used to normalize a plane-wave impulse approximation calculation of d/sup 2/sigma/d..cap omega.. dp for p+/sup 12/C..-->..p+..pi..+/sup 12/C(. .AE

  4. Actomyosin contractility rotates the cell nucleus

    PubMed Central

    Kumar, Abhishek; Maitra, Ananyo; Sumit, Madhuresh; Ramaswamy, Sriram; Shivashankar, G. V.

    2014-01-01

    The cell nucleus functions amidst active cytoskeletal filaments, but its response to their contractile stresses is largely unexplored. We study the dynamics of the nuclei of single fibroblasts, with cell migration suppressed by plating onto micro-fabricated patterns. We find the nucleus undergoes noisy but coherent rotational motion. We account for this observation through a hydrodynamic approach, treating the nucleus as a highly viscous inclusion residing in a less viscous fluid of orientable filaments endowed with active stresses. Lowering actin contractility selectively by introducing blebbistatin at low concentrations drastically reduced the speed and coherence of the angular motion of the nucleus. Time-lapse imaging of actin revealed a correlated hydrodynamic flow around the nucleus, with profile and magnitude consistent with the results of our theoretical approach. Coherent intracellular flows and consequent nuclear rotation thus appear to be an intrinsic property of cells. PMID:24445418

  5. Actomyosin contractility rotates the cell nucleus.

    PubMed

    Kumar, Abhishek; Maitra, Ananyo; Sumit, Madhuresh; Ramaswamy, Sriram; Shivashankar, G V

    2014-01-21

    The cell nucleus functions amidst active cytoskeletal filaments, but its response to their contractile stresses is largely unexplored. We study the dynamics of the nuclei of single fibroblasts, with cell migration suppressed by plating onto micro-fabricated patterns. We find the nucleus undergoes noisy but coherent rotational motion. We account for this observation through a hydrodynamic approach, treating the nucleus as a highly viscous inclusion residing in a less viscous fluid of orientable filaments endowed with active stresses. Lowering actin contractility selectively by introducing blebbistatin at low concentrations drastically reduced the speed and coherence of the angular motion of the nucleus. Time-lapse imaging of actin revealed a correlated hydrodynamic flow around the nucleus, with profile and magnitude consistent with the results of our theoretical approach. Coherent intracellular flows and consequent nuclear rotation thus appear to be an intrinsic property of cells.

  6. Correlation and fluctuations in relativistic nucleus-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Mohsin Khan, M.; Ahmad, N.; Kamal, A.; Masoodi, A. A.; Irfan, M.

    2011-01-01

    Correlation and fluctuations are now well accepted analysis techniques in heavy-ion collisions at relativistic energies. At the current stage of RHIC exploration, matter in bulk and many of the physics questions about the final stage of collisions are addressed with the help of correlation techniques. In the present work after a general introduction to the underlying formalism to the exotic phenomena of correlation and fluctuations, discussion on various parameters disentangling dynamical fluctuations is presented. Analysis to investigate dynamical fluctuations and correlation is carried out in terms of F q - and G q -moments. A study of various other parameters involving multiplicity and pseudorapidity of relativistic charged particles produced in high energy nuclear interactions reveals the presence of correlation and fluctuations in particle production in these collisions. The experimental data on 14.5A GeV/c 28Si-nucleus interactions has been analyzed. A parallel analysis of correlation free data generated using MC-RAND Monte Carlo code, UrQMD data and for the HIJING generated events has also been carried out.

  7. Microscopic time-dependent description of alpha-cluster transfer and incomplete fusion in reactions with 12C and 16O near Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Samarin, V. V.

    2017-06-01

    The time-dependent Schrödinger equation has been numerically solved for the α-cluster wave function the in reaction 12C+51V at the energies near and above the Coulomb barrier. The α-target potential included an imaginary part as in the optical model. The α-cluster mean field of the shell model for 12C and 16O nuclei based on the results of Feynman’s integrals method is proposed. The evolution of the α-cluster probability density was calculated for the complete and incomplete fusion as well as transfer channels. The calculated cross sections show satisfactory agreement with the experimental data for (12C,α) and (12C,2α) transfer channels.

  8. Cross section asymmetry of two-body carbon disintegration 12C (γ , p)11B with polarized photons at energy 40-50 MeV

    NASA Astrophysics Data System (ADS)

    Burdeinyi, D.; Brudvik, J.; Fissum, K.; Ganenko, V.; Hansen, K.; Isaksson, L.; Livingston, K.; Lundin, M.; Nilsson, B.; Schroder, B.

    2017-01-01

    The cross section asymmetry of 12C (γ ,p01)11B and 12C (γ ,p2-6)11B reactions has been studied at the energy range 40-55 MeV, using linearly polarized tagged photons of the MAX-lab facility. The asymmetry of the 12C (γ ,p01)11B processes, which assume the one-body mechanism of the reaction, is Σ ≈ 0.82 ± 0.05 for photon energies 45-50 MeV. The asymmetry for the 12C (γ ,p2-6)11B reactions, which produce a maximum at excitation energy ∼ 6 MeV, is Σ ≈ 0.53 ± 0.13 for a photon energy 49 MeV. It is close to the asymmetry of reaction of the free deuteron photodisintegration, and can be resulted from the two-body mechanism of the photon absorption.

  9. Conformational restriction through C alpha i <--> C alpha i cyclization: Ac12c, the largest cycloaliphatic C alpha,alpha- disubstituted glycine known.

    PubMed

    Saviano, M; Iacovino, R; Menchise, V; Benedetti, E; Bonora, G M; Gatos, M; Graci, L; Formaggio, F; Crisma, M; Toniolo, C

    2000-02-01

    Two complete series of N-protected, monodispersed oligopeptide esters to the pentamer level from 1-aminocyclododecane-1-carboxylic acid (Ac(12)c), an alpha-amino acid conformationally constrained through C(alpha)(i) <--> C(alpha)(i) cyclization, and either L-Ala or Aib residues, along with the N-protected Ac(12)c homopeptide alkylamide series from monomer to trimer, have been synthesized by solution methods and fully characterized. The solution-preferred conformations of these peptides have been assessed by Fourier transform ir absorption and (1)H-nmr techniques. Moreover, the molecular structures of one derivative (Z-Ac(12)c-OH) and three peptides [the tripeptide ester Z-L-Ala-Ac(12)c-L-Ala-OMe, the tripeptide alkylamide Z-(Ac(12)c)(3)-NHiPr, and the tetrapeptide ester Z-(Aib)(2)-Ac(12)c-Aib-OtBu (Aib, alpha-aminoisobutyric acid)] have been determined in the crystal state by x-ray diffraction. The results obtained point to the conclusion that beta-bends and 3(10)-helices are preferentially adopted by peptides based on Ac(12)c, the largest cycloaliphatic C-disubstituted glycine known. A comparison with the structural tendencies extracted from published works on peptides from Aib, the prototype of C-disubstituted glycines, and the other extensively studied members of the class of 1-aminocycloalkane-1-carboxylic acids (Ac(n) c, with n = 3-9), is made and the implications for the use of the Ac(12)c residue in the Ac(n) c scan approach of conformationally restricted analogues of bioactive peptides are briefly discussed.

  10. Methylol polyesters of C12-C22 hydrocarbon substituted succinic anhydride or acid, their preparation and use as additives for lubricants and fuels

    SciTech Connect

    Gutierrez, A.; Ryer, J.; Shaub, H.; Winans, E.D.

    1980-06-24

    Methylol polyester derivatives of C12-C22 hydrocarbon substituted succinic anhydride or acid which are the equimolar reaction products of said C12-C22 hydrocarbon substituted succinic anhydride or acid and a cyclic poly(Methylol) compound provide activity: in fuels as rust inhibitors; in automatic transmission fluids as copper corrosion inhibitors; and, in automotive, industrial and lubricating oils as sludge dispersants , rust-inhibitors, friction reducers (Lubricity agents) and copper alloy corrosion inhibitors.

  11. Music and the nucleus accumbens.

    PubMed

    Mavridis, Ioannis N

    2015-03-01

    Music is a universal feature of human societies over time, mainly because it allows expression and regulation of strong emotions, thus influencing moods and evoking pleasure. The nucleus accumbens (NA), the most important pleasure center of the human brain (dominates the reward system), is the 'king of neurosciences' and dopamine (DA) can be rightfully considered as its 'crown' due to the fundamental role that this neurotransmitter plays in the brain's reward system. Purpose of this article was to review the existing literature regarding the relation between music and the NA. Studies have shown that reward value for music can be coded by activity levels in the NA, whose functional connectivity with auditory and frontal areas increases as a function of increasing musical reward. Listening to music strongly modulates activity in a network of mesolimbic structures involved in reward processing including the NA. The functional connectivity between brain regions mediating reward, autonomic and cognitive processing provides insight into understanding why listening to music is one of the most rewarding and pleasurable human experiences. Musical stimuli can significantly increase extracellular DA levels in the NA. NA DA and serotonin were found significantly higher in animals exposed to music. Finally, passive listening to unfamiliar although liked music showed activations in the NA.

  12. The mediodorsal thalamic nucleus and schizophrenia

    PubMed Central

    Alelú-Paz, Raúl; Giménez-Amaya, José Manuel

    2008-01-01

    The mediodorsal nucleus of the human thalamus is in a crucial position that allows it to establish connections with diverse cerebral structures, particularly the prefrontal cortex. The present review examines existing neurobiologic studies of the brains of people with and without schizophrenia that indicate a possible involvement of the mediodorsal nucleus in this psychiatric disorder. Studies at synaptic and cellular levels of the neurobiology of the mediodorsal nucleus, together with a better anatomic understanding of this diencephalic structure owing to neuroimaging studies, should help to establish a more deep and solid pathophysiologic model of schizophrenia. PMID:18982171

  13. Investigation of carbon-coated lithiated Li{sub 4+x}Ti{sub 5}O{sub 12}/C for lithium-ion batteries

    SciTech Connect

    Pan, Mengjie; Zhang, Lin; Gong, Lijun; Liu, Hongbo; Chen, Yuxi

    2015-11-15

    Highlights: • Lithiated Li{sub 4+x}Ti{sub 5}O{sub 12}/C with pre-stored active Li ions has been synthesized. • The first-cycle coulombic efficiency of Li{sub 4+x}Ti{sub 5}O{sub 12}/C is over 100%. • Li{sub 4+x}Ti{sub 5}O{sub 12}/C displays excellent cyclic stability and capacity retention. • TiO{sub 2} nanoparticles and carbon coating are necessary for formation of Li{sub 4+x}Ti{sub 5}O{sub 12}/C. - Abstract: Carbon-coated Li{sub 4}Ti{sub 5}O{sub 12} and lithiated Li{sub 4+x}Ti{sub 5}O{sub 12} anode materials have been synthesized using nanosized anatase TiO{sub 2} and commercial TiO{sub 2} with mixed structure as Ti sources, respectively. Microstructural investigation indicates that Li{sub 4}Ti{sub 5}O{sub 12} and Li{sub 4+x}Ti{sub 5}O{sub 12} are covered by amorphous carbon layers with thickness of 2–3 nm. Their electrochemical performance has been evaluated, which indicates that an amount of active Li ions have been pre-stored in the Li{sub 4+x}Ti{sub 5}O{sub 12} lattice during solid-state synthesis, resulting in its first-cycle coulombic efficiency over 100%. Further, Li{sub 4+x}Ti{sub 5}O{sub 12}/C exhibits higher cyclic capacities than Li{sub 4}Ti{sub 5}O{sub 12}/C at different current density. The reversible charge capacity retention of Li{sub 4+x}Ti{sub 5}O{sub 12}/C reaches 98.5% after 100 cycles, which indicates that Li{sub 4+x}Ti{sub 5}O{sub 12}/C is promising candidate anode material for long lifetime lithium-ion batteries. The formation mechanism of Li{sub 4+x}Ti{sub 5}O{sub 12}/C has been discussed, in which the nanosized anatase TiO{sub 2} with high chemical activity and the carbon coating play key roles for the formation of Li{sub 4+x}Ti{sub 5}O{sub 12}/C.

  14. The extended chain compounds Ln {sub 12}(C{sub 2}){sub 3}I{sub 17} (Ln=Pr, Nd, Gd, Dy): Synthesis, structure and physical properties

    SciTech Connect

    Ryazanov, Mikhail; Mattausch, Hansjuergen; Simon, Arndt

    2007-04-15

    The title compounds are obtained in high yield from stoichiometric mixtures of Ln, LnI{sub 3} and graphite, heated at 900-950 deg. C in welded Ta containers. The crystal structures of new Pr and Nd phases determined by single-crystal X-ray diffraction are related to those of other Ln {sub 12}(C{sub 2}){sub 3}I{sub 17}-type compounds (C 2/c, a=19.610(1) and 19.574(4) A, b=12.406(2) and 12.393(3) A, c=19.062(5) and 19.003(5) A, {beta}=90.45(3){sup o} and 90.41(3){sup o}, for Pr{sub 12}(C{sub 2}){sub 3}I{sub 17} and Nd{sub 12}(C{sub 2}){sub 3}I{sub 17}, respectively). All compounds contain infinite zigzag chains of C{sub 2}-centered metal atom octahedra condensed by edge-sharing into the [tcc] {sub {infinity}} sequence (c=cis, t=trans) and surrounded by edge-bridging iodine atoms as well as by apical iodine atoms that bridge between chains. The polycrystalline Gd{sub 12}(C{sub 2}){sub 3}I{sub 17} sample exhibits semiconducting thermal behavior which is consistent with an ionic formulation (Ln {sup 3+}){sub 12}(C{sub 2} {sup 6-}){sub 3}(I{sup -}){sub 17}(e{sup -}) under the assumption that one extra electron is localized in metal-metal bonding. The magnetization measurements on Nd{sub 12}(C{sub 2}){sub 3}I{sub 17}, Gd{sub 12}(C{sub 2}){sub 3}I{sub 17} and Dy{sub 12}(C{sub 2}){sub 3}I{sub 17} indicate the coexistence of competing magnetic interactions leading to spin freezing at T {sub f}=5 K for the Gd phase. The Nd and Dy compounds order antiferromagnetically at T {sub N}=25 and 29 K, respectively. For Dy{sub 12}(C{sub 2}){sub 3}I{sub 17}, a metamagnetic transition is observed at a critical magnetic field H{approx}25 kOe. - Graphical abstract: Zigzag chains of edge-sharing metal atom octahedra in Ln {sub 12}(C{sub 2}){sub 3}I{sub 17}.

  15. Quasielastic thinsp{sup 12}C(e,e{sup {prime}}p) reaction at high momentum transfer

    SciTech Connect

    Morrison, J.H.; Baghaei, H.; Bertozzi, W.; Gilad, S.; Glickman, J.; Hyde-Wright, C.E.; Kalantar-Nayestanaki, N.; Lourie, R.W.; Penn, S.; Ulmer, P.E.; Weinstein, L.B.; Cottman, B.H.; Ghedira, L.; Winhold, E.J.; Calarco, J.R.; Wise, J.; Boberg, P.; Chang, C.C.; Zhang, D.; Aniol, K.; Epstein, M.B.; Margaziotis, D.J.; Finn, J.M.; Perdrisat, C.; Punjabi, V.

    1999-01-01

    We measured the {sup 12}C(e,e{sup {prime}}p) cross section as a function of missing energy in parallel kinematics for (q,{omega})=(970 MeV/c, 330 MeV) and (990 MeV/c, 475 MeV). At {omega}=475 MeV, at the maximum of the quasielastic peak, there is a large continuum (E{sub m}{gt}50 MeV) cross section extending out to the deepest missing energy measured, amounting to almost 50{percent} of the measured cross section. The ratio of data to distorted-wave impulse approximation (DWIA) calculation is 0.4 for both {ital p} and {ital s} shells. At {omega}=330 MeV, well below the maximum of the quasielastic peak, the continuum cross section is much smaller and the ratio of data to DWIA calculation is 0.85 for the {ital p} shell and 1.0 for the {ital s} shell. We infer that one or more mechanisms that increase with {omega} transform some of the single-nucleon knockouts into a multinucleon knockout, decreasing the valence knockout cross section and increasing the continuum cross section. {copyright} {ital 1999} {ital The American Physical Society}

  16. Measurement of the interference structure function RLT for the 12C(e,e'p) reaction in the quasielastic region

    NASA Astrophysics Data System (ADS)

    Holtrop, M.; Jordan, D.; McIlvain, T.; Alarcon, R.; Beck, R.; Bertozzi, W.; Bhushan, V.; Boeglin, W.; Chen, J. P.; Dale, D.; Dodson, G.; Dolfini, S.; Dow, K.; Dzengeleski, J.; Epstein, M. B.; Farkhondeh, M.; Gilad, S.; Görgen, J.; Joo, K.; Kelsey, J.; Kim, W.; Laszewski, R.; Lourie, R.; Mandeville, J.; Margaziotis, D. J.; Martinez, D.; Miskimen, R.; Papanicolas, C.; Penn, S.; Sapp, W.; Sarty, A. J.; Tieger, D.; Tschalaer, C.; Turchinetz, W.; Warren, G.; Weinstein, L.; Williamson, S.

    1998-12-01

    The coincidence cross section and the interference structure function, RLT, were measured for the 12C(e,e'p) 11B reaction at quasielastic kinematics and central momentum transfer of \\|q-->\\|=400 MeV/c. The measurement was at an opening angle of θpq=11°, covering a range in missing energy of Em=0 to 65 MeV. The RLT structure function is found to be consistent with zero for Em>50 MeV, confirming an earlier study which indicated that RL vanishes in this region. The integrated strengths of the p- and s-shell are compared with a distorted wave impulse approximation (DWIA) calculation. The s-shell strength and shape are also compared with a Hartree Fock-random phase approximation (HF-RPA) calculation. The DWIA calculation does not succeed in giving a consistent description of both the cross section data and the extracted RLT response for either shell. The HF-RPA calculation describes the data more consistently, which may be due to the inclusion of 2-body currents in this calculation.

  17. Differential cross section measurement of the 12C(e,e'pp)10Beg.s. reaction

    NASA Astrophysics Data System (ADS)

    Makek, M.; Achenbach, P.; Ayerbe Gayoso, C.; Barbieri, C.; Bernauer, J. C.; Böhm, R.; Bosnar, D.; Denig, A.; Distler, M. O.; Friščić, I.; Giusti, C.; Merkel, H.; Müller, U.; Nungesser, L.; Pochodzalla, J.; Sanches Majos, S.; Schlimme, B. S.; Schwamb, M.; Walcher, Th.

    2016-09-01

    The differential cross section was measured for the 12C(e,e'pp)10Be g.s. reaction at energy and momentum transfers of 163MeV and 198MeV/ c, respectively. The measurement was performed at the Mainz Microtron by using two high-resolution magnetic spectrometers of the A1 Collaboration and a newly developed silicon detector telescope. The overall resolution of the detector system was sufficient to distinguish the ground state from the first excited state in 10 Be. We chose a super-parallel geometry that minimizes the effect of two-body currents and emphasizes the effect of nucleon-nucleon correlations. The obtained differential cross section is compared to the theoretical results of the Pavia reaction code in which different processes leading to two-nucleon knockout are accounted for microscopically. The comparison shows a strong sensitivity to nuclear-structure input and the measured cross section is seen to be dominated by the interplay between long- and short-range nucleon-nucleon correlations. Microscopic calculations based on the ab initio self-consistent Green's function method give a reasonable description of the experimental cross section.

  18. High Resolution Infrared Spectrum of Ethylene (12C_2H_4) in the Spectral Region 1820 TO 2300 CM-1

    NASA Astrophysics Data System (ADS)

    Flaud, Jean-Marie; Tchana, F. Kwabia; Lafferty, Walter J.

    2010-06-01

    While the fundamental bands of ethylene have been studied at high resolution, most of the combination bands have not been recorded. In this study, we have recorded the 12C_2H_4 bands in the 1820 to 2300 cm-1 region which consists of a myriad of weak combination bands. Over 10,000 lines were measured. The strongest of these bands are the A-type band, ν_7+ν_8, centered at 1889 cm-1, the A-type band, ν_6+ν_1_0, at 2048 cm-1, and the B-type band, ν_3+ν_1_0, at 2173 cm-1. In addition, there are numerous lines from much weaker bands. All the bands observed are perturbed by Coriolis interactions, and, at this point, we are attempting to fit all the lines to within experimental error using an Hamiltonian matrix including eigth vibrational states among which four are dark states . The most striking resonance is that of the ν_7+ν_8 band whose energy levels are crossed by the very much weaker ν_4+ν_8 band where the intensities of the K=7 lines are enhanced due to mixing with the stronger band.

  19. Measurement of the 12C(e,e‧p)11B two-body breakup reaction at high missing momentum

    NASA Astrophysics Data System (ADS)

    Monaghan, P.; Shneor, R.; Subedi, R.; Anderson, B. D.; Aniol, K.; Annand, J.; Arrington, J.; Benaoum, H. B.; Benmokhtar, F.; Bertin, P.; Bertozzi, W.; Boeglin, W.; Chen, J. P.; Choi, Seonho; Chudakov, E.; Ciofi degli Atti, C.; Cisbani, E.; Cosyn, W.; Craver, B.; de Jager, C. W.; Feuerbach, R. J.; Folts, E.; Frullani, S.; Garibaldi, F.; Gayou, O.; Gilad, S.; Gilman, R.; Glamazdin, O.; Gomez, J.; Hansen, O.; Higinbotham, D. W.; Holmstrom, T.; Ibrahim, H.; Igarashi, R.; Jans, E.; Jiang, X.; Kaufman, L.; Kelleher, A.; Kolarkar, A.; Kuchina, E.; Kumbartzki, G.; LeRose, J. J.; Lindgren, R.; Liyanage, N.; Margaziotis, D. J.; Markowitz, P.; Marrone, S.; Mazouz, M.; Meekins, D.; Michaels, R.; Moffit, B.; Morita, H.; Nanda, S.; Perdrisat, C. F.; Piasetzky, E.; Potokar, M.; Punjabi, V.; Qiang, Y.; Reinhold, J.; Reitz, B.; Ron, G.; Rosner, G.; Ryckebusch, J.; Saha, A.; Sawatzky, B.; Segal, J.; Shahinyan, A.; Širca, S.; Slifer, K.; Solvignon, P.; Sulkosky, V.; Thompson, N.; Ulmer, P. E.; Urciuoli, G. M.; Voutier, E.; Wang, K.; Watson, J. W.; Weinstein, L. B.; Wojtsekhowski, B.; Wood, S.; Yao, H.; Zheng, X.; Zhu, L.

    2014-10-01

    The five-fold differential cross section for the 12C{{(e,{{e}^{\\prime }}p)}^{11}}B reaction was determined over a missing momentum range of 200-400 MeV\\;{{c}^{-1}}, in a kinematics regime with {{x}_{B}}\\gt 1 and {{Q}^{2}}=2.0 {{(GeV\\;{{c}^{-1}})}^{2}}. A comparison of the results with previous lower missing momentum data and with theoretical models are presented. The extracted distorted momentum distribution is shown to be consistent with previous data and extends the range of available data up to 400 MeV\\;{{c}^{-1}}. The theoretical calculations are from two very different approaches, one mean field and the other short range correlated; yet for this system the two approaches show striking agreement with the data and each other up to a missing momentum value of 325 MeV\\;{{c}^{-1}}. For larger momenta, the calculations diverge which is likely due to the factorization approximation used in the short range approach.

  20. Respiratory Carbon Metabolism following Illumination in Intact French Bean Leaves Using 13C/12C Isotope Labeling1

    PubMed Central

    Nogués, Salvador; Tcherkez, Guillaume; Cornic, Gabriel; Ghashghaie, Jaleh

    2004-01-01

    The origin of the carbon atoms in the CO2 respired by French bean (Phaseolus vulgaris) leaves in the dark has been studied using 13C/12C isotopes as tracers. The stable isotope labeling was achieved through a technical device that uses an open gas-exchange system coupled online to an elemental analyzer and linked to an isotope ratio mass spectrometer. The isotopic analysis of the CO2 respired in the dark after a light period revealed that the CO2 was labeled, but the labeling level decreased progressively as the dark period increased. The pattern of disappearance depended on the amount of carbon fixed during the labeling and indicated that there were several pools of respiratory metabolites with distinct turnover rates. We demonstrate that the carbon recently assimilated during photosynthesis accounts for less than 50% of the carbon in the CO2 lost by dark respiration and that the proportion is not influenced by leaf starvation in darkness before the labeling. Therefore, most of the carbon released by dark respiration after illumination does not come from new photosynthates. PMID:15377781

  1. Respiratory carbon metabolism following illumination in intact French bean leaves using (13)C/(12)C isotope labeling.

    PubMed

    Nogués, Salvador; Tcherkez, Guillaume; Cornic, Gabriel; Ghashghaie, Jaleh

    2004-10-01

    The origin of the carbon atoms in the CO(2) respired by French bean (Phaseolus vulgaris) leaves in the dark has been studied using (13)C/(12)C isotopes as tracers. The stable isotope labeling was achieved through a technical device that uses an open gas-exchange system coupled online to an elemental analyzer and linked to an isotope ratio mass spectrometer. The isotopic analysis of the CO(2) respired in the dark after a light period revealed that the CO(2) was labeled, but the labeling level decreased progressively as the dark period increased. The pattern of disappearance depended on the amount of carbon fixed during the labeling and indicated that there were several pools of respiratory metabolites with distinct turnover rates. We demonstrate that the carbon recently assimilated during photosynthesis accounts for less than 50% of the carbon in the CO(2) lost by dark respiration and that the proportion is not influenced by leaf starvation in darkness before the labeling. Therefore, most of the carbon released by dark respiration after illumination does not come from new photosynthates.

  2. [The use of the [13C]/[12C] ratio for the assay of the microbial oxidation of hydrocarbons].

    PubMed

    Ziakun, A M; Kosheleva, I A; Zakharchenko, V N; Kudriavtseva, A I; Peshenko, V A; Filonov, A E; Boronin, A M

    2003-01-01

    The study deals with a comparative analysis of the relative abundances of the carbon isotopes 12C and 13C in the metabolites and biomass of the Burkholderia sp. BS3702 and Pseudomonas putida BS202-p strains capable of utilizing aliphatic (n-hexadecane) and aromatic (naphthalene) hydrocarbons as sources of carbon and energy. The isotope composition of the carbon dioxide, biomass, and exometabolites produced during the growth of Burkholderia sp. BS3702 on n-hexadecane (delta 13C = -44.6 +/- 0.2@1000) were characterized by the isotope effects delta 13CCO2 = -50.2 +/- 0.4@1000, delta 13Cbiom = -46.6 +/- 0.4@1000 and delta 13Cexo = -41.5 +/- 0.4@1000, respectively. The isotope composition of the carbon dioxide, biomass, and exometabolites produced during the growth of the same bacterial strain on naphthalene (delta 13C = -21 +/- 0.4@1000) were characterized by the isotope effects delta 13CCO2 = -24.1 +/- 0.4@1000, delta 13Cbiom = -19.2 +/- 0.4@1000 and delta 13Cexo = -19.1 +/- 0.4@1000, respectively. The possibility of using the isotope composition of metabolic carbon dioxide for the rapid monitoring of the microbial degradation of petroleum hydrocarbons in the enviroment is discussed.

  3. [Carbon isotope (13C/12C) effect of photorespiration in photosynthetic organisms. Evidence for existence, probable mechanism].

    PubMed

    Ivlev, A A

    2002-01-01

    Experimental evidence in favor of the new phenomenon predicted for photosynthesizing organisms, the fractionation of carbon isotopes in photorespiration is presented. A possible mechanism of this process is discussed. The fractionation of carbon in isotopes photorespiration occurs in the oxygenase phase of the functioning of ribulosebisphosphate carboxylase/oxygenase (rubisco), the key enzyme of photosynthesis, which is capable to act as carboxylase and oxygenase. Which function of the enzyme is active depends on CO2/O2 concentration ratio, which periodically changes in a cell. The key reaction in the mechanism of carbon isotope fractionation in photorespiration is glycine decarboxylation, which results in the splitting and removal from the cell of CO2 enriched with 12C and the accumulation of 13C photorespiratory carbon flow. The coupling of photorespiration and CO2 photoassimilation gives rise to two isotopically different carbon flows, which fill up separate carbohydrate pools, which are the sources of carbon in the following syntheses in the dark phase of photosynthesis. This enables one to identify, from the carbon isotope ratio of metabolites, their involvement in the photorespiratory and assimilatory carbon flows, to investigate the pathways of carbon metabolism, and to estimate more thoroughly the biosynthetic role of photorespiration.

  4. In vitro degradation behavior of Fe-20 Mn-1.2C alloy in three different pseudo-physiological solutions.

    PubMed

    Mouzou, Essowè; Paternoster, Carlo; Tolouei, Ranna; Purnama, Agung; Chevallier, Pascale; Dubé, Dominique; Prima, Frédéric; Mantovani, Diego

    2016-04-01

    High manganese austenitic steels such as Fe-20Mn-1.2C alloys are among the most promising candidates for biodegradable stents applications due to their high strength, high ductility and their chemical composition. In the current work, 14 day static in-vitro tests were performed in controlled atmosphere to assess the degradation behavior in three common pseudo-physiological solutions, i.e. commercial Hanks' (CH), modified Hanks' (MH) and albumin-enriched Dulbecco's modified phosphate buffered saline (DPBS) solutions. The degraded samples surfaces as well as the degradation products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Degradation of material and degradation products are shown to be strongly dependent on the test medium due to the presence of different ionic species such as HCO3(-), CO3(2-), Cl(-), Ca(2+) or phosphate groups. In both MH and CH solutions, the increased content of HCO3(-) ions seems to promote MnCO3 crystal growth on sample surfaces whereas the presence of albumin and high content of phosphate ions promotes the formation of an amorphous layer rich in phosphates, iron and manganese.

  5. Yield and recoil properties of iodine isotopes from the interaction of 240 MeV 12C with 238U

    NASA Astrophysics Data System (ADS)

    Yu, Y. W.; Lee, C. H.; Moody, K. J.; Kudo, H.; Lee, D.; Seaborg, G. T.

    1987-12-01

    The independent yields, recoil properties, and forward-to-backward ratios (F/B) of iodine isotopes from the interaction of 240 MeV 12C with 238U have been measured radiochemically by the thick-target/thick-catcher method. The isotopic yield distribution curve has been constructed and is found to consist of two overlapping Gaussians, peaking at A=126.5 and 133.8 with width parameters of 2.29 and 2.04 mass units, respectively. All the measured iodine isotopes had ranges of 7.7+/-0.4 mg/cm2. The neutron-deficient products have F/B of 1.76+/-0.14, but the neutron-excessive products have F/B of only 1.09+/-0.06. The yield curve was analyzed with the liquid drop model and the recoil curve was analyzed by the standard two-step vector model; the results show that the neutron-deficient products are formed from nonequilibrium processes and the neutron-excessive products are formed from the normal low-energy fission process.

  6. 12C(16O,γ)28Si radiative capture: Structural and statistical aspects of the γ decay

    NASA Astrophysics Data System (ADS)

    Lebhertz, D.; Courtin, S.; Haas, F.; Jenkins, D. G.; Simenel, C.; Salsac, M.-D.; Hutcheon, D. A.; Beck, C.; Cseh, J.; Darai, J.; Davis, C.; Glover, R. G.; Goasduff, A.; Kent, P. E.; Levai, G.; Marley, P. L.; Michalon, A.; Pearson, J. E.; Rousseau, M.; Rowley, N.; Ruiz, C.

    2012-03-01

    The heavy-ion radiative capture reaction 12C(16O,γ)28Si has been studied at three energies Ec.m.=8.5, 8.8, and 9 MeV which are close to the Coulomb barrier. The weak radiative capture process has been identified by measuring the 28Si recoils in the highly selective 0∘ spectrometer DRAGON at TRIUMF (Vancouver). The coincident γ rays have been recorded in the associated BGO array. This has allowed a complete measurement of the γ spectrum and the relative strength of all decay pathways. An important part of the decay through quasibound states close to the particle threshold and the feeding of bound states with particular deformation have been identified for the first time. Comparisons with Monte Carlo simulations allowed the extraction of the full experimental radiative capture cross section. Our results suggest an important contribution of spins Jπ=5- and 6+ in the entrance channel. The surprisingly large cross sections from 12 μb at Ec.m.=8.5 MeV to 25 μb at Ec.m.=9.0 MeV for the heavy-ion radiative capture process are discussed in terms of the interplay between statistical and structural aspects of the process.

  7. Detection of adulteration in honey samples added various sugar syrups with 13C/12C isotope ratio analysis method.

    PubMed

    Tosun, Murat

    2013-06-01

    Honey can be adulterated in various ways. One of the adulteration methods is the addition of different sugar syrups during or after honey production. Starch-based sugar syrups, high fructose corn syrup (HFCS), glucose syrup (GS) and saccharose syrups (SS), which are produced from beet or canes, can be used for adulterating honey. In this study, adulterated honey samples were prepared with the addition of HFCS, GS and SS (beet sugar) at a ratio of 0%, 10%, 20%, 40% and 50% by weight. (13)C/(12)C analysis was conducted on these adulterated honey samples using an isotope ratio mass spectrometer in combination with an elemental analyser (EA-IRMS). As a result, adulteration using C(4) sugar syrups (HFCS and GS) could be detected to a certain extent while adulteration of honey using C(3) sugar syrups (beet sugar) could not be detected. Adulteration by using SS (beet sugar) still has a serious detection problem, especially in countries in which beet is used in manufacturing sugar. For this reason, practice and analysis methods are needed to meet this deficit and to detect the adulterations precisely in the studies that will be conducted.

  8. Reaction Mechanisms in 12C+93Nb System:. Excitation Functions and Recoil Range Distributions Below 7 MeV/u

    NASA Astrophysics Data System (ADS)

    Ahmad, Tauseef; Rizvi, I. A.; Agarwal, Avinash; Kumar, Rakesh; Golda, K. S.; Chaubey, A. K.

    The experiments were performed to study excitation functions (EFs) of evaporation residues (ERs), i.e. 103,102,101Ag, 101,100,99Pd, 101,100Rh, 97Ru, 96Tc, 95Tc, 94Tc, 93Mom, 92Nbm populated in the reactions induced by 12C on 93Nb for exploring the reaction dynamics involved at energies ≈ 47-75 MeV. The activation technique followed by offline γ-ray spectrometry has been employed to measure EFs. These measurements were simulated with other reported values available in literature as well as with theoretical predictions based on computer code PACE-2. The effect of variation of level density parameter involved in this code has also been studied. An excellent agreement was found between theoretical and experimental values in some of the fusion evaporation channels. However, significant enhancement of cross-section as observed in α-emission channels may be due to incomplete fusion (ICF) process and/or direct reaction process. To confirm the aforesaid reaction mechanism, Recoil Range Distributions (RRDs) of various ERs have been measured at ≈ 80 MeV. Moreover, an attempt is made to separate the percentage relative contributions of complete and incomplete fusion components from the analysis of the measured RRDs data. Further, the relative percentage ICF fraction, also estimated from EFs data, was found to be sensitive with the projectile energy.

  9. Heavy-Ion Double-Charge Exchange Study via a 12C(18O,18Ne)12Be Reaction

    NASA Astrophysics Data System (ADS)

    Takaki, Motonobu; Matsubara, Hiroaki; Uesaka, Tomohiro; Aoi, Nori; Dozono, Masanori; Hashimoto, Takashi; Kawabata, Takahiro; Kawase, Shoichiro; Kisamori, Keiichi; Kubota, Yuki; Lee, Cheng Soo; Lee, Jenny; Maeda, Yukie; Michimasa, Shin'ichiro; Miki, Kenjiro; Ota, Shinsuke; Sasano, Masaki; Shimoura, Susumu; Suzuki, Tomokazu; Takahisa, Keiji; Tang, Tsz Leung; Tamii, Atsushi; Tokieda, Hiroshi; Yako, Kentaro; Yokoyama, Rin; Zenihiro, Juzo

    Heavy-ion double-charge exchange (HIDCX) reactions are a new promising spectroscopic tool for double spin-isospin flips excitation modes by taking an advantage of transferring isospin and/or spin quantum numbers by an amount of two to target nuclei. However, the data on HIDCX reactions is very scarce. A measurement of a (n,p)-type HIDCX reaction, 12C(18O,18Ne)12Be at 80 MeV/nucleon, was performed by employing the high-resolution spectrometer Grand Raiden at Research Center Nuclear Physics, Osaka University. The excitation energy spectrum of 12Be was obtained, and three clear peaks were observed at 0.0, 2.2, and 4.5 MeV, which are corresponding to ground and excited states of 12Be. The angular distributions of the cross sections for these peaks were obtained within the scattering angle range of 0.0°-4.0° in the center of mass system. We found that the angular distributions have characteristic shapes according to their mulpolarities.

  10. Performances of the Front-End Electronics for the HADES RPC TOF wall on a 12C beam

    NASA Astrophysics Data System (ADS)

    Belver, D.; Cabanelas, P.; Castro, E.; Díaz, J.; Garzón, J. A.; Gil, A.; Gonzalez-Diaz, D.; Koenig, W.; Traxler, M.; Zapata, M.

    2009-05-01

    A Front-End Electronics (FEE) chain for timing accurate measurements has been developed for the RPC wall upgrade of the High-Acceptance DiElectron Spectrometer (HADES). The wall will cover an area of around 8 m with 1122 RPC cells (2244 electronic channels). The FEE chain consists of two boards: a four-channel DaughterBOard (DBO) and a 32-channel MotherBOard (MBO). The DBO uses a fast 2 GHz amplifier feeding a discriminator. The time and the charge information are encoded in the leading and the trailing edge (by a charge to width method) of an LVDS signal. Each MBO houses up to eight DBOs providing them regulated voltage supply, threshold values via DACs, test signals and collection of their trigger outputs. The MBO delivers LVDS signals to a time-to-digital converter readout board (TRB) based on HPTDC for data acquisition. In this work, we present the performance of the FEE measured using: (a) narrow electronic test pulses and (b) real signals read out in a fully instrumented RPC sextant installed in its final position at the HADES. The detector was exposed to particles coming from reactions of a 12C beam on Be and Nb targets at 2 GeV/A kinetic energy. Results for the whole electronic chain (DBO+MBO+TRB) show a timing jitter of around 40 ps/channel for pulses above 100 fC and 80 ps/channel for beam data taken with the RPC.

  11. Determinations of the 12C/13C Ratio for the Secondary Stars of AE Aquarii, SS Cygni, and RU Pegasi

    NASA Astrophysics Data System (ADS)

    Harrison, Thomas E.; Marra, Rachel E.

    2017-07-01

    We present new moderate-resolution near-infrared spectroscopy of three CVs obtained using GNIRS on Gemini-North. These spectra covered three 13CO bandheads found in the K-band, allowing us to derive the isotopic abundance ratios for carbon. We find small 12C/13C ratios for all three donor stars. In addition, these three objects show carbon deficits, with AE Aqr being the most extreme ([C/Fe] = -1.4). This result confirms the conjecture that the donor stars in some long-period CVs have undergone considerable nuclear evolution prior to becoming semi-contact binaries. In addition to the results for carbon, we find that the abundance of sodium is enhanced in these three objects, and the secondary stars in both RU Peg and SS Cyg suffer magnesium deficits. Explaining such anomalies appears to require higher mass progenitors than commonly assumed for the donor stars of CVs. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil).

  12. Hypernuclear production cross section in the reaction of 6Li + 12C at 2 A GeV

    NASA Astrophysics Data System (ADS)

    Rappold, C.; Saito, T. R.; Bertini, O.; Bianchin, S.; Bozkurt, V.; Kim, E.; Kavatsyuk, M.; Ma, Y.; Maas, F.; Minami, S.; Nakajima, D.; Özel-Tashenov, B.; Yoshida, K.; Achenbach, P.; Ajimura, S.; Aumann, T.; Ayerbe Gayoso, C.; Bhang, H. C.; Caesar, C.; Erturk, S.; Fukuda, T.; Göküzüm, B.; Guliev, E.; Hoffmann, J.; Ickert, G.; Ketenci, Z. S.; Khaneft, D.; Kim, M.; Kim, S.; Koch, K.; Kurz, N.; Le Fèvre, A.; Mizoi, Y.; Nungesser, L.; Ott, W.; Pochodzalla, J.; Sakaguchi, A.; Schmidt, C. J.; Sekimoto, M.; Simon, H.; Takahashi, T.; Tambave, G. J.; Tamura, H.; Trautmann, W.; Voltz, S.; Yoon, C. J.

    2015-07-01

    Hypernuclear production cross sections have been deduced for the first time with induced reaction of heavy ion beam on fixed target and by means of the invariant mass method by the HypHI Collaboration exploiting the reaction of 6Li + 12C at 2 A GeV or √{sNN} = 2.70 GeV. A production cross section of 3.9 ± 1.4 μb for 3ΛH and of 3.1 ± 1.0 μb for 4ΛH respectively in the projectile rapidity region was inferred as well as the total production cross section of the Λ hyperon was measured and found to be equal to 1.7 ± 0.8 mb. A global fit based on a Bayesian approach was performed in order to include and propagate statistical and systematic uncertainties. Production ratios of 3ΛH/4ΛH, 3ΛH/Λ and 4ΛH/Λ were included in the inference procedure. The strangeness population factors S3 and S4 of 3ΛH and 4ΛH respectively were extracted. In addition, the multiplicities of the Λ hyperon, 3ΛH, and 4ΛH together with the rapidity and transversal momentum density distributions of the observed hypernuclei were extracted and reported.

  13. Regional localization of the gene for thyroid peroxidase to human chromosome 2p25 and mouse chromosome 12C

    SciTech Connect

    Endo, Yuichi; Onogi, Satoshi; Fujita, Teizo

    1995-02-10

    Thyroid peroxidase (TPO) plays a central role in thyroid gland function. The enzyme catalyzes two important reactions of thyroid hormone synthesis, i.e., the iodination of tyrosine residues in thyroglobulin and phenoxy-ester formation between pairs of iodinated tyrosines to generate the thyroid hormones, thyroxine and triiodothyronine. Previously, we isolated the cDNAs encoding human and mouse TPOs and assigned the human TPO gene to the short arm of chromosome 2 by somatic cell hybrid mapping. By a similar analysis of DNA from somatic cell hybrids, the human TPO gene was mapped to 2pter-p12. The mouse TPO gene was localized to chromosome 12 using a rat TPO cDNA as a probe to hybridize with mouse-hamster somatic cell hybrids. In this study, we used fluorescence in situ hybridization (FISH) to confirm the localization of human and mouse TPO genes to human chromosome 2 and mouse chromosome 12 and to assign them regionally to 2p25 and 12C, respectively. 7 refs., 1 fig.

  14. 14N + 13C fusion cross sections and compound nucleus limitation in 27Al

    NASA Astrophysics Data System (ADS)

    Digregorio, D. E.; Gomez del Campo, J.; Chan, Y. D.; Ford, J. L. C., Jr.; Shapira, D.; Ortiz, M. E.

    1982-10-01

    Fusion cross sections for the 14N + 13C system have been measured by detecting the evaporation residues at five bombarding energies which correspond to high excitation energies in the compound nucleus: E*(27Al)=64-110 MeV. The 27Al nucleus can be populated by four different heavy-ion entrance channels-15N + 12C, 16O + 11B, 14N + 13C, and 17O + 10B-which are accessible to experimental measurements. Comparing the present data with those already existing for the above channels, it is found that for E*>60 MeV the curves E* vs Jcr for each system converge, which may be indicative of a limitation imposed by the compound nucleus. The data are discussed in terms of existing models for entrance channel and statistical yrast line limitations. The highest energy point also suggests the existence of a maximum absolute angular momentum limit of ~28ℏ. NUCLEAR REACTIONS 14N + 13C E(14N)=86.0, 103.8, 149.0, 161.3, and 180.0 MeV; measured d2σdΩdE for reaction products from Z=5 to 12. Extracted σfus, σD, σR.

  15. Dynamic risk control by human nucleus accumbens

    PubMed Central

    Lopez-Sosa, Fernando; Gonzalez-Rosa, Javier Jesus; Galarza, Ana; Avecillas, Josue; Pineda-Pardo, Jose Angel; Lopez-Ibor, Juan José; Reneses, Blanca; Barcia, Juan Antonio

    2015-01-01

    Real-world decisions about reward often involve a complex counterbalance of risk and value. Although the nucleus accumbens has been implicated in the underlying neural substrate, its criticality to human behaviour remains an open question, best addressed with interventional methodology that probes the behavioural consequences of focal neural modulation. Combining a psychometric index of risky decision-making with transient electrical modulation of the nucleus accumbens, here we reveal profound, highly dynamic alteration of the relation between probability of reward and choice during therapeutic deep brain stimulation in four patients with treatment-resistant psychiatric disease. Short-lived phasic electrical stimulation of the region of the nucleus accumbens dynamically altered risk behaviour, transiently shifting the psychometric function towards more risky decisions only for the duration of stimulation. A critical, on-line role of human nucleus accumbens in dynamic risk control is thereby established. PMID:26428667

  16. Microtubules move the nucleus to quiescence.

    PubMed

    Laporte, Damien; Sagot, Isabelle

    2014-01-01

    The nucleus is a cellular compartment that hosts several macro-molecular machines displaying a highly complex spatial organization. This tight architectural orchestration determines not only DNA replication and repair but also regulates gene expression. In budding yeast microtubules play a key role in structuring the nucleus since they condition the Rabl arrangement in G1 and chromosome partitioning during mitosis through their attachment to centromeres via the kinetochore proteins. Recently, we have shown that upon quiescence entry, intranuclear microtubules emanating from the spindle pole body elongate to form a highly stable bundle that spans the entire nucleus. Here, we examine some molecular mechanisms that may underlie the formation of this structure. As the intranuclear microtubule bundle causes a profound re-organization of the yeast nucleus and is required for cell survival during quiescence, we discuss the possibility that the assembly of such a structure participates in quiescence establishment.

  17. Dynamic risk control by human nucleus accumbens.

    PubMed

    Nachev, Parashkev; Lopez-Sosa, Fernando; Gonzalez-Rosa, Javier Jesus; Galarza, Ana; Avecillas, Josue; Pineda-Pardo, Jose Angel; Lopez-Ibor, Juan José; Reneses, Blanca; Barcia, Juan Antonio; Strange, Bryan

    2015-12-01

    Real-world decisions about reward often involve a complex counterbalance of risk and value. Although the nucleus accumbens has been implicated in the underlying neural substrate, its criticality to human behaviour remains an open question, best addressed with interventional methodology that probes the behavioural consequences of focal neural modulation. Combining a psychometric index of risky decision-making with transient electrical modulation of the nucleus accumbens, here we reveal profound, highly dynamic alteration of the relation between probability of reward and choice during therapeutic deep brain stimulation in four patients with treatment-resistant psychiatric disease. Short-lived phasic electrical stimulation of the region of the nucleus accumbens dynamically altered risk behaviour, transiently shifting the psychometric function towards more risky decisions only for the duration of stimulation. A critical, on-line role of human nucleus accumbens in dynamic risk control is thereby established.

  18. 13C/12C and 15N/14N Isotope Analysis to Characterize Natural Degradation of Atrazine: Evidence from Parent and Daughter Compound Values

    NASA Astrophysics Data System (ADS)

    Elsner, Martin; Meyer, Armin

    2013-04-01

    The mobile and still herbicidal metabolites desethylatrazine (DEA) and desisopropylatrazine (DIA) are frequently detected together with its parent compound atrazine (Atz) in the aquatic environment. Interpretation of their transformation state is often difficult with current methods, which are mainly measuring concentrations. Alternatively, compound specific isotope analyses (CSIA) has become a novel tool to detect degradation processes of contaminants in groundwater. The aim of our study was to investigate on the lab scale 13C/12C and 15N/14N isotope trends in parent and daughter compounds associated with different degradation scenarios of atrazine likely to occur in the environment. Thus atrazine was dealkylated with (i) permanganate and (ii) the bacterium Rhodococcus sp. NI86/21. In both transformations, 13C/12C ratios of atrazine increased strongly (epsilon carbon/permanganate = -4.6 ± 0.6 ‰ and epsilon carbon/Rhodoccoccus = -3.8 ± 0.2 ‰) whereas nitrogen isotope fractionation was small. 13C/12C ratios of DEA showed the following trends. (i) When DEA was formed as only product (Atz + permanganate) 13C/12C remained constant, close to the initial value of Atz. (ii) When DEA was formed together with deisopropylatrazine (biodegradation of Atz) 13C/12C increased, but only within 2‰. (iii) When DEA and DIA was further biodegraded, 13C/12C increased for both metabolites up to 9‰. Thus strong enrichment of 13C/12C in the metabolites in comparison to Atz can give strong testimony for further breakdown of the metabolite.

  19. Phase II study of the oxygen saturation curve left shifting agent BW12C in combination with the hypoxia activated drug mitomycin C in advanced colorectal cancer

    PubMed Central

    Propper, D J; Levitt, N C; O'Byrne, K; Braybrooke, J P; Talbot, D C; Ganesan, T S; Thompson, C H; Rajagopalan, B; Littlewood, T J; Dixon, R M; Harris, A L

    2000-01-01

    BW12C (5-[2-formyl-3-hydroxypenoxyl] pentanoic acid) stabilizes oxyhaemoglobin, causing a reversible left-shift of the oxygen saturation curve (OSC) and tissue hypoxia. The activity of mitomycin C (MMC) is enhanced by hypoxia. In this phase II study, 17 patients with metastatic colorectal cancer resistant to 5-fluorouracil (5-FU) received BW12C and MMC. BW12C was given as a bolus loading dose of 45 mg kg−1over 1 h, followed by a maintenance infusion of 4 mg kg−1h−1for 5 h. MMC 6 mg m−2was administered over 15 min immediately after the BW12C bolus. The 15 evaluable patients had progressive disease after a median of 2 (range 1–4) cycles of chemotherapy. Haemoglobin electrophoresis 3 and 5 h after the BW12C bolus dose showed a fast moving band consistent with the BW12C-oxyhaemoglobin complex, accounting for approximately 50% of total haemoglobin. The predominant toxicities – nausea/vomiting and vein pain – were mild and did not exceed CTC grade 2. Liver31P magnetic resonance spectroscopy of patients with hepatic metastases showed no changes consistent with tissue hypoxia. The principle of combining a hypoxically activated drug with an agent that increases tissue hypoxia is clinically feasible, producing an effect equivalent to reducing tumour oxygen delivery by at least 50%. However, BW12C in combination with MMC for 5-FU-resistant colorectal cancer is not an effective regimen. This could be related to drug resistance rather than a failure to enhance cytotoxicity. © 2000 Cancer Research Campaign PMID:10839290

  20. Improved Cloud Condensation Nucleus Spectrometer

    NASA Technical Reports Server (NTRS)

    Leu, Ming-Taun

    2010-01-01

    An improved thermal-gradient cloud condensation nucleus spectrometer (CCNS) has been designed to provide several enhancements over prior thermal- gradient counters, including fast response and high-sensitivity detection covering a wide range of supersaturations. CCNSs are used in laboratory research on the relationships among aerosols, supersaturation of air, and the formation of clouds. The operational characteristics of prior counters are such that it takes long times to determine aerosol critical supersaturations. Hence, there is a need for a CCNS capable of rapid scanning through a wide range of supersaturations. The present improved CCNS satisfies this need. The improved thermal-gradient CCNS (see Figure 1) incorporates the following notable features: a) The main chamber is bounded on the top and bottom by parallel thick copper plates, which are joined by a thermally conductive vertical wall on one side and a thermally nonconductive wall on the opposite side. b) To establish a temperature gradient needed to establish a supersaturation gradient, water at two different regulated temperatures is pumped through tubes along the edges of the copper plates at the thermally-nonconductive-wall side. Figure 2 presents an example of temperature and supersaturation gradients for one combination of regulated temperatures at the thermally-nonconductive-wall edges of the copper plates. c) To enable measurement of the temperature gradient, ten thermocouples are cemented to the external surfaces of the copper plates (five on the top plate and five on the bottom plate), spaced at equal intervals along the width axis of the main chamber near the outlet end. d) Pieces of filter paper or cotton felt are cemented onto the interior surfaces of the copper plates and, prior to each experimental run, are saturated with water to establish a supersaturation field inside the main chamber. e) A flow of monodisperse aerosol and a dilution flow of humid air are introduced into the main

  1. BFKL Pomeron calculus: solution to equations for nucleus-nucleus scattering in the saturation domain

    NASA Astrophysics Data System (ADS)

    Contreras, Carlos; Levin, Eugene; Meneses, Rodrigo

    2013-04-01

    In this paper we solve the equation for nucleus-nucleus scattering in the BFKL Pomeron calculus, suggested by Braun [1-3]. We find these solutions analytically at high energies as well as numerically in the entire region of energies inside the saturation region. The semi-classical approximation is used to select out the infinite set of the parasite solutions. The nucleus-nucleus cross sections at high energy are estimated and compared with the Glauber-Gribov approach. It turns out that the exact formula gives the estimates that are very close to the ones based on Glauber-Gribov formula which is important for the practical applications.

  2. Comparisons of longitudinal and lateral dose profiles and relative biological effectiveness for DNA double strand breaks among 1H, 4He and 12C beams

    NASA Astrophysics Data System (ADS)

    Lin, Yu-Shen; Chao, Tsi-Chian; Hong, Ji-Hong; Tung, Chuan-Jong

    2017-08-01

    Monte Carlo FLUKA and MCDS codes were used to study 1H, 4He and 12C ion beams with similar ranges in water phantom. The longitudinal and lateral dose profiles and the relative biological effectiveness (RBE) were investigated. Simulations were performed with particular emphasis in the vicinity of the Bragg peak (BP). The impact of individual nuclear fragments created by the primary beams was examined. Comparisons were made for the BP width, lateral dose profile width, and RBE value at different depths in the phantom. RBE values for the induction of DNA double-strand breaks were estimated, particularly in the vicinity of the BP. Results showed that 12C beam had the narrowest BP width, smallest lateral dose profile, and largest RBE value, followed by 4He and 1H beams. However, the differences between 4He and 12C were smaller than those between 1H and 4He. It also showed that the influence of nuclear fragments was significant for 12C beam, moderate for 4H beam, and minor for 1H beam. This influence was important for 12C at depths beyond the BP. Our results suggest that 4He beam is also a promising option for cancer therapy.

  3. Rem GTPase Interacts with the Proximal Cav1.2 C-terminus and Modulates Calcium-dependent Channel Inactivation

    PubMed Central

    Pang, Chunyan; Crump, Shawn M.; Jin, Ling; Correll, Robert N.; Finlin, Brian S.; Satin, Jonathan; Andres, Douglas A.

    2011-01-01

    The Rem, Rem2, Rad, and Gem/Kir (RGK) GTPases, comprise a subfamily of small Ras-related GTP-binding proteins, and have been shown to potently inhibit high voltage-activated Ca2+ channel current following overexpression. Although the molecular mechanisms underlying RGK-mediated Ca2+ channel regulation remains controversial, recent studies suggest that RGK proteins inhibit Ca2+ channel currents at the plasma membrane in part by interactions with accessory channel β subunits. In this paper, we extend our understanding of the molecular determinants required for RGK-mediated channel regulation by demonstrating a direct interaction between Rem and the proximal C-terminus of CaV1.2 (PCT), including the CB/IQ domain known to contribute to Ca2+/calmodulin (CaM)-mediated channel regulation. The Rem2 and Rad GTPases display similar patterns of PCT binding, suggesting that the CaV1.2 C-terminus represents a common binding partner for all RGK proteins. In vitro Rem:PCT binding is disrupted by Ca2+/CaM, and this effect is not due to Ca2+/CaM binding to the Rem C-terminus. In addition, co-overexpression of CaM partially relieves Rem-mediated L-type Ca2+ channel inhibition and slows the kinetics of Ca2+-dependent channel inactivation. Taken together, these results suggest that the association of Rem with the PCT represents a crucial molecular determinant in RGK-mediated Ca2+ channel regulation and that the physiological function of the RGK GTPases must be reevaluated. Rather than serving as endogenous inhibitors of Ca2+ channel activity, these studies indicate that RGK proteins may play a more nuanced role, regulating Ca2+ currents via modulation of Ca2+/CaM-mediated channel inactivation kinetics. PMID:20458179

  4. The 1- v″ bands progression of the B2Σ + → X2Σ + system of 12C 17O +

    NASA Astrophysics Data System (ADS)

    Szajna, W.; Kepa, R.; Hakalla, R.; Zachwieja, M.

    2006-11-01

    The B2Σ + → X2Σ + (0-1, 2, 3, 4 progression) electronic transition of 12C 17O + was first observed and analyzed by Szajna and Kȩpa [Spectrochim. Acta A 65 (2006) 1014-1020]. We have now extended our previous studies. The use of high resolution conventional spectroscopic techniques has allowed first rotational analysis of the 1-2, 1-3, 1-4 and 1-5 bands of the first negative system in the 37,000-43,000 cm -1 spectral region. Approximately 500 transition wavenumbers were measured with an estimated accuracy of 0.005 cm -1. The present data were combined with the previous measurements to yield an improved set of molecular constants for the B2Σ +( v' = 0, 1) and X2Σ +( v″ = 1, 2, 3, 4, 5). The v' = 1 and v″ = 5 vibrational levels were observed for the first time and the main molecular constants are (in cm -1, one standard deviation in parentheses) B2Σ +X2Σ +B1 = 1.710792(20) B5 = 1.825694(23) D1 = 7.799(15) × 10 -6D5 = 6.085(21) × 10 -6γ1 = 1.9491(37) × 10 -2γ5 = [8.381] × 10 -3. The principal equilibrium molecular constants for the B2Σ + and X2Σ + states have also been derived and the vibrational terms values for the ground and excited states have been calculated.

  5. Definite evidence of the Landau-Zener transition in nucleus-nucleus collisions

    SciTech Connect

    Imanishi, B.; von Oertzen, W.; Voit, H.

    1987-01-01

    It is shown that the Landau-Zener transition mechanism due to the formation of molecular orbitals of the active neutron exists in the inelastic scattering /sup 13/C(/sup 12/C, /sup 12/C)/sup 13/C/sup */ (3.086 MeV, (1/2)/sup +/). The evidence stems from characteristic changes of the angular distributions observed as a function of the incident energy.

  6. Dynamical evolution of comet nucleus rotation

    NASA Astrophysics Data System (ADS)

    Scheeres, D. J.; Sidorenko, V. V.; Neishtadt, A. I.; Vasiliev, A. A.

    2001-11-01

    The rotational dynamics of outgassing cometary nuclei are investigated analytically using dynamical systems theory. We develop a general theory for the averaged evolution of a comet nucleus rotation state assuming that the nucleus is a spheroid (either prolate or oblate) and that the outgassing torques are a function of solar insolation and heliocentric distance. The resulting solutions are a function of the comet outgassing properties, its heliocentric orbit, and the assumed distribution of active regions on its surface. We find that the long-term evolution of the comet nucleus rotation is a strong function of the distribution of active regions over its surface. Specifically, we find that a comet nucleus with a uniformly active surface will tend towards a rotation state with a nutation angle of ~ 55 degrees and an angular momentum perpendicular to the sun-perihelion direction. Conversely, a comet nucleus with an isolated active region will tend towards a zero nutation angle with its symmetry axis and angular momentum aligned parallel to the sun-perihelion direction. For active surface regions between these extremes we find 4 qualitatively different dynamical outcomes. In all cases, the theory predicts that the comet nucleus angular momentum will have a secular increase, a phenomenon that could contribute to nucleus splitting of active comets. These results can be used to discriminate between competing theories of comet outgassing based on a nucelus' rotation state. They also allow for a range of plausible a priori constraints to be placed on a comet's rotation state to aid in the interpretation of its outgassing structure. This work was supported by the NASA JURRISS program under Grant NAG5-8715. AIN, AAV and VVS acknowledge support from Russian Foundation for Basic research via Grants 00-01-00538 and 00-01-0174 respectively. DJS acknowledges support from the PG&G program via Grant NAG5-9017.

  7. Antifungal agents. Part 4: Synthesis and antifungal activities of novel indole[1,2-c]-1,2,4-benzotriazine derivatives against phytopathogenic fungi in vitro.

    PubMed

    Xu, Hui; Fan, Ling-Ling

    2011-01-01

    A series of novel indole[1,2-c]-1,2,4-benzotriazine derivatives were obtained by a modified Sandmeyer reaction in the presence of tert-butylnitrite (t-BuONO). As compared with hymexazol, a commercially available agricultural fungicide, at the concentration of 50 μg/mL, two indole[1,2-c]-1,2,4-benzotriazines, 5h and 5k, exhibited the more promising and pronounced antifungal activities in vitro against five phytopathogenic fungi. It clearly demonstrated that introduction of appropriate substituents on the indolyl ring of indole[1,2-c]-1,2,4-benzotriazine (5a) would lead to the more potent derivatives.

  8. 2H/(1)H and (13)C/(12)C isotope ratios of trans-anethole using gas chromatography-isotope ratio mass spectrometry.

    PubMed

    Bilke, Steffi; Mosandl, Armin

    2002-07-03

    Authenticity assessment of trans-anethole is deduced from (2)H/(1)H and (13)C/(12)C isotope ratios, determined by gas chromatography-isotope ratio mass spectrometry (GC-IRMS). For that purpose, self-prepared anise and fennel oils, and synthetic and "natural" samples of trans-anethole, as well as commercially available anise and fennel oils have been investigated. Authenticity ranges of (2)H/(1)H and (13)C/(12)C isotope ratios of trans-anethole were defined. Scope and limitations of the applied online GC-IRMS techniques are discussed.

  9. High density QCD and nucleus-nucleus scattering deeply in the saturation region

    NASA Astrophysics Data System (ADS)

    Kormilitzin, Andrey; Levin, Eugene; Miller, Jeremy S.

    2011-06-01

    In this paper we solve the equations that describe nucleus-nucleus scattering, in high density QCD, in the framework of the BFKL Pomeron Calculus. We found that (i) the contribution of short distances to the opacity for nucleus-nucleus scattering dies at high energies, (ii) the opacity tends to unity at high energy, and (iii) the main contribution that survives comes from soft (long distance) processes for large values of the impact parameter. The corrections to the opacity Ω(Y,b)=1 were calculated and it turns out that they have a completely different form, namely ( 1-Ω→exp(-Const √{Y} )) than the opacity that stems from the Balitsky-Kovchegov equation, which is ( 1-Ω→exp(-Const Y)). We reproduce the formula for the nucleus-nucleus cross section that is commonly used in the description of nucleus-nucleus scattering, and there is no reason why it should be correct in the Glauber-Gribov approach.

  10. The signature of the 13C/12C of dissolved inorganic carbon in the Strait of Gibraltar: a mixing case

    NASA Astrophysics Data System (ADS)

    Huertas, E.; Flecha, S.; Navarro, G.; Ruiz, J.; Stutsman, J.; Quay, P.

    2012-12-01

    The Strait of Gibraltar is a narrow and shallow channel that connects the Mediterranean Sea with the Atlantic Ocean. Previous studies have revealed that the water exchange pattern through the Strait plays an important role in the biogeochemical budgets of the Mediterranean and the North Atlantic. In particular, carbon fluxes in this area significantly contribute to the total carbon inventory of the North Atlantic, as the entrance of surface young Atlantic anthropogenic CO2 (CANT) rich waters into the Mediterranean through the Strait alleviates the accumulation of CANT in the former (Flecha et al., 2012). Recently, a carbon budget in the Strait was released, which shows the transport of the different species of carbon between the two water masses that encounter in this region (Huertas et al., 2009). However, the 13C/12C ratio (expressed as δ13C) of the total dissolved inorganic carbon (DIC) contained in both water types, which is a useful tracer of CO2 derived from fossil fuel and deforestation sources, had not been examined up to date. This work presents the first δ13C measurements in the Strait of Gibraltar using data collected in two oceanographic campaigns conducted in November 2011 and February 2012. The δ13C of the DIC was measured using the procedures described in Quay et al., (2003). Results obtained were also compared with other biogeochemical parameters recorded in the area, such as the apparent oxygen utilization (AOU) and nutrients. The spatial distribution of δ13C indicates that the Atlantic inflow (AI), as expected, presents higher values (maximum of 1.06 ‰) of the tracer in relation to the Mediterranean outflow (MOW) (minimum of 0.5 ‰) due to the enhanced biological activity in surface waters. This pattern leads to a net vertical δ13C loss equivalent to -19 ‰ in the water column. In addition, the relationship between AOU and δ13C reflects that the deep MOW is strongly influenced by the remineralization of organic matter that occurs in the

  11. Target nucleus in relativistic nuclear collisions

    SciTech Connect

    Gutbrod, H.H.; Warwick, A.I.; Wieman, H.

    1982-03-01

    Both the fireball model and hydrodynamical model predict, in a central collision, a fast energy dissipation in the early diving stage of the projectile into the target nucleus. In the final state both models show total incident energy largely dispersed over the whole target nucleus. In a quantitative comparison with the data for the Intranuclear Cascade Calculations, however, the 90/sup 0/ double differential cross section seems to be flatter than the calculated one. If the slope is reflecting the temperature in the system then the data are having apparently a higher temperature than the cascade would predict. This report suggests and discusses a picture of the reaction mechanism where the light projectile (e.g. Ne) gets stopped very early in the large target nucleus (e.g. Au or U) forming a small fireball at approximately half the beam rapidity, which decays inside the target nucleus, heating it up and causing thee whole system to expand. The expansion cools the system and big clusters can condense out if the total energy and thus entropy in the system is not too high to prevent it. Such a qualitative picture of a reaction mechanism emerges when we consider the information obtained about relativistic nuclear collisions from measurements of the remnants of a large target nucleus struck by a smaller projectile (Ne + Au) and relate it to the complementary information from earlier measurements of fast light reaction products. (WHK)

  12. Cell Biology of the Caenorhabditis elegans Nucleus.

    PubMed

    Cohen-Fix, Orna; Askjaer, Peter

    2017-01-01

    Studies on the Caenorhabditis elegans nucleus have provided fascinating insight to the organization and activities of eukaryotic cells. Being the organelle that holds the genetic blueprint of the cell, the nucleus is critical for basically every aspect of cell biology. The stereotypical development of C. elegans from a one cell-stage embryo to a fertile hermaphrodite with 959 somatic nuclei has allowed the identification of mutants with specific alterations in gene expression programs, nuclear morphology, or nuclear positioning. Moreover, the early C. elegans embryo is an excellent model to dissect the mitotic processes of nuclear disassembly and reformation with high spatiotemporal resolution. We review here several features of the C. elegans nucleus, including its composition, structure, and dynamics. We also discuss the spatial organization of chromatin and regulation of gene expression and how this depends on tight control of nucleocytoplasmic transport. Finally, the extensive connections of the nucleus with the cytoskeleton and their implications during development are described. Most processes of the C. elegans nucleus are evolutionarily conserved, highlighting the relevance of this powerful and versatile model organism to human biology. Copyright © 2017 by the Genetics Society of America.

  13. Structural dynamics of the cell nucleus

    PubMed Central

    Wiegert, Simon; Bading, Hilmar

    2011-01-01

    Neuronal morphology plays an essential role in signal processing in the brain. Individual neurons can undergo use-dependent changes in their shape and connectivity, which affects how intracellular processes are regulated and how signals are transferred from one cell to another in a neuronal network. Calcium is one of the most important intracellular second messengers regulating cellular morphologies and functions. In neurons, intracellular calcium levels are controlled by ion channels in the plasma membrane such as NMDA receptors (NMDARs), voltage-gated calcium channels (VGCCs) and certain α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) as well as by calcium exchange pathways between the cytosol and internal calcium stores including the endoplasmic reticulum and mitochondria. Synaptic activity and the subsequent opening of ligand and/or voltage-gated calcium channels can initiate cytosolic calcium transients which propagate towards the cell soma and enter the nucleus via its nuclear pore complexes (NPCs) embedded in the nuclear envelope. We recently described the discovery that in hippocampal neurons the morphology of the nucleus affects the calcium dynamics within the nucleus. Here we propose that nuclear infoldings determine whether a nucleus functions as an integrator or detector of oscillating calcium signals. We outline possible ties between nuclear mophology and transcriptional activity and discuss the importance of extending the approach to whole cell calcium signal modeling in order to understand synapse-to-nucleus communication in healthy and dysfunctional neurons. PMID:21738832

  14. Control of nucleus positioning in mouse oocytes.

    PubMed

    Almonacid, Maria; Terret, Marie-Emilie; Verlhac, Marie-Hélène

    2017-08-12

    The position of the nucleus in a cell can instruct morphogenesis in some cases, conveying spatial and temporal information and abnormal nuclear positioning can lead to disease. In oocytes from worm, sea urchin, frog and some fish, nucleus position regulates embryo development, it marks the animal pole and in Drosophila it defines the future dorso-ventral axis of the embryo and of the adult body plan. However, in mammals, the oocyte nucleus is centrally located and does not instruct any future embryo axis. Yet an off-center nucleus correlates with poor outcome for mouse and human oocyte development. This is surprising since oocytes further undergo two extremely asymmetric divisions in terms of the size of the daughter cells (enabling polar body extrusion), requiring an off-centering of their chromosomes. In this review we address not only the bio-physical mechanism controlling nucleus positioning via an actin-mediated pressure gradient, but we also speculate on potential biological relevance of nuclear positioning in mammalian oocytes and early embryos. Copyright © 2017. Published by Elsevier Ltd.

  15. Measurements of parity violation in neutron-nucleus reactions

    SciTech Connect

    Seestrom, S.J.; Bowman, C.D.; Bowman, J.D.; Knudson, J.; Mortensen, R.; Penttila, S.; Szymanski, J.J.; Wender, S.A.; Yoo, S.H.; Yuan, V.W. ); Frankle, C.M.; Gould, C.R.; Haase, D.G.; Mitchell, G.E. Triangle Universities Nuclear Lab., Durham, NC ); Roberson, N.R.; Zhu, X. (Duke Univ., Durham, NC

    1991-01-01

    In this talk I describe a new generation of experiments studying the weak interaction between nucleons. Measurements of the effect of this interaction are few in number and the significance of the observed effects are generally small. It is well known that the weak interaction violates parity. This was first experimentally established by C. S. Wu through measurement of an asymmetry of electrons emitted in the beta-decay of polarized {sup 60}Co. The measured asymmetry was large because beta decay is a weak interaction process. For a process in which the strong interaction can contribute, we expect much smaller asymmetries, of order 10{sup {minus}7}. In the work I will describe here we study the effects of the weak interaction through the signal of the parity violation associated with that interaction. There are two basic classes of experiment used to detect parity violation. The first relies on the measurement of a cross section or width that would vanish if parity were conserved. One example of this type of experiment in nuclear physics is the decay of an unnatural parity state to a 0+ nucleus and an {alpha}-particle. Such measurements have been made for two nuclei: {sup 16}O(2{sup {minus}}) {implies} {sup 12} C(g.s) + {alpha} and {sup 20}N{var epsilon}(1{sup +}) {implies} {sup 16} O(g.s) + {alpha}. Parity-violating widths as small as of 10{sup {minus}10} eV have been measured in these experiments. The second class of experiments involves a measurement of pseudo-scalar observables which are odd under parity inversion. These involve correlations between spin and linear angular momenta, for example circular polarization of {gamma}-rays ({sigma}{sub {gamma}} {center dot} {kappa}{sub {gamma}}) or longitudinal analyzing power ({sigma}{sub p} {center dot} {kappa}{sub p}). 20 refs., 6 figs.

  16. The dynamic landscape of the cell nucleus.

    PubMed

    Austin, Christopher M; Bellini, Michel

    2010-01-01

    While the cell nucleus was described for the first time almost two centuries ago, our modern view of the nuclear architecture is primarily based on studies from the last two decades. This surprising late start coincides with the development of new, powerful strategies to probe for the spatial organization of nuclear activities in both fixed and live cells. As a result, three major principles have emerged: first, the nucleus is not just a bag filled with nucleic acids and proteins. Rather, many distinct functional domains, including the chromosomes, resides within the confines of the nuclear envelope. Second, all these nuclear domains are highly dynamic, with molecules exchanging rapidly between them and the surrounding nucleoplasm. Finally, the motion of molecules within the nucleoplasm appears to be mostly driven by random diffusion. Here, the emerging roles of several subnuclear domains are discussed in the context of the dynamic functions of the cell nucleus.

  17. Organisation of the human dorsomedial hypothalamic nucleus.

    PubMed

    Koutcherov, Yuri; Mai, Juergen K; Ashwell, Ken W; Paxinos, George

    2004-01-19

    This study used acetylcholinesterase (AChE) histochemistry to reveal the organization of the dorsomedial hypothalamic nucleus (DM) in the human. Topographically, the human DM is similar to DM in the monkey and rat. It is wedged between the paraventricular nucleus, dorsally, and the ventromedial nucleus, ventrally. Laterally, DM borders the lateral hypothalamic area while medially it approaches the 3rd ventricle. The AChE staining distinguished two subcompartments of the human DM: the larger diffuse and the smaller compact DM. The subcompartmental organization of the human DM appears homologous to that found in the monkey and less complex than that reported in rats. Understanding of the organization of DM creates meaningful anatomical reference for physiological and pharmacological studies in the human hypothalamus.

  18. L'intérêt de la sélection du faisceau (12)C par rapport au (13)C pour la radiothérapie du cancer

    NASA Astrophysics Data System (ADS)

    Farés, G.; Hachem, A.; Bimbot, R.; Roussel-Chomaz, P.; Anne, R.; Mirea, M.; Belahbib, S.; Benfoughal, T.; Cabot, C.; Clapier, F.; Freeman, R.; Lewitowicz, M.; Saint-Laurent, M. G.; Sauvestre, J. E.; Sida, J. L.

    1998-04-01

    Heavy ions having interesting properties as Bragg's peak require an important energy in order to attain a deep tumor. At intermediate and relativist energies, fragmentation reactions occur throughout their path and produce fragments lighter than the projectile. Consequently, the product fragments give a residual dose beyond the Bragg peak. For these reasons, the interesting ions in radiotherapy of cancer converge toward heavy light ions (C - Ne). Moreover, for a better treatment safety, it is envisaged also to use β(+) transmitting radioactive ion beams. This allows to provide the picture of the really irradiated volume by using a positon camera. In this context, our works essentially is concentrated on production rates and cross sections calculations for nucleus products in the fragmentation of (12)C at 95 MeV/u and (13)C at 75 MeV/u. Les ions lourds possédant des propriétés balistiques importantes tel que le pic de Bragg nécessitent une énergie importante pour atteindre une tumeur profonde. Aux énergies intermédiaires et relativistes, des réactions de fragmentation se produisent tout au long de leur trajet et donnent naissance à des fragments plus légers que le projectile. Ces derniers entraînent une dose résiduelle au-delà du pic de Bragg. Pour cette raison, les ions les plus intéressants en radiothérapie convergent vers les ions lourds - légers (C à Ne). Par ailleurs, pour une sécurité accrue du traitement, on envisage d'utiliser aussi des faisceaux d'ions radioactifs émetteurs β(+). Ceci permet de fournir l'image du volume réellement irradié en utilisant une caméra à positon. Dans ce contexte, nos travaux ont porté essentiellement sur le calcul de taux de production et de la section efficace des noyaux issus de la fragmentation du (12)C à 95 MeV/u et du (13)C à 75 MeV/u.

  19. Crystal and molecular structures of benzo[4,5]imidazo[1,2-c]quinazolin-6-one and 10-carboxybenzo[4,5]imidazo[1,2-c]quinazolin-6-one: A quantum-chemical study of their tautomerism

    SciTech Connect

    Koval'chukova, O. V.; Stash, A. I.; Strashnov, P. V.; Neborak, E. V.; Strashnova, S. B.; Zaitsev, B. E.

    2011-03-15

    Benzo[4,5]imidazo[1,2-c]quinazolin-6-one and 10-carboxybenzo[4,5]imidazo[1,2-c]quinazolin-6-one were isolated in the crystalline state and studied by X-ray diffraction. The crystal and molecular structures of these compounds were determined by X-ray diffraction. The energy characteristics of the tautomeric and ionic forms were calculated by the quantum-chemical PM3 method.

  20. UNCOVERING THE NUCLEUS CANDIDATE FOR NGC 253

    SciTech Connect

    Günthardt, G. I.; Camperi, J. A.; Agüero, M. P.; Díaz, R. J.; Gomez, P. L.; Schirmer, M.; Bosch, G. E-mail: camperi@oac.uncor.edu E-mail: rdiaz@gemini.edu E-mail: mschirmer@gemini.edu

    2015-11-15

    NGC 253 is the nearest spiral galaxy with a nuclear starburst that becomes the best candidate for studying the relationship between starburst and active galactic nucleus activity. However, this central region is veiled by large amounts of dust, and it has been so far unclear which is the true dynamical nucleus to the point that there is no strong evidence that the galaxy harbors a supermassive black hole co-evolving with the starburst as was supposed earlier. Near-infrared (NIR) spectroscopy, especially NIR emission line analysis, could be advantageous in shedding light on the true nucleus identity. Using Flamingos-2 at Gemini South we have taken deep K-band spectra along the major axis of the central structure and through the brightest infrared source. In this work, we present evidence showing that the brightest NIR and mid-infrared source in the central region, already known as radio source TH7 and so far considered just a large stellar supercluster, in fact presents various symptoms of a genuine galactic nucleus. Therefore, it should be considered a valid nucleus candidate. Mentioning some distinctive aspects, it is the most massive compact infrared object in the central region, located at 2.″0 of the symmetry center of the galactic bar, as measured in the K-band emission. Moreover, our data indicate that this object is surrounded by a large circumnuclear stellar disk and it is also located at the rotation center of the large molecular gas disk of NGC 253. Furthermore, a kinematic residual appears in the H{sub 2} rotation curve with a sinusoidal shape consistent with an outflow centered in the candidate nucleus position. The maximum outflow velocity is located about 14 pc from TH7, which is consistent with the radius of a shell detected around the nucleus candidate, observed at 18.3 μm (Qa) and 12.8 μm ([Ne ii]) with T-ReCS. Also, the Brγ emission line profile shows a pronounced blueshift and this emission line also has the highest equivalent width at this

  1. Nucleus model for periodic Comet Tempel 2

    NASA Technical Reports Server (NTRS)

    Sekanina, Zdenek

    1991-01-01

    Observational data obtained primarily during 1988 are analyzed and synthesized to develop a comprehensive physical model for the nucleus of Periodic Comet Tempel 2, one of the best studied members of Jupiter's family of short-period comets. It is confirmed that a previous investigation provided reliable information on the comet's spin-axis orientation, which implies and obliquity of 54 degrees of the orbit plane to the equatorial plane and which appears to have varied little - if at all - with time. This conclusion is critical for fitting a triaxial ellipsoid to approximate the figure of the nucleus.

  2. Uncovering the Nucleus Candidate for NGC 253

    NASA Astrophysics Data System (ADS)

    Günthardt, G. I.; Agüero, M. P.; Camperi, J. A.; Díaz, R. J.; Gomez, P. L.; Bosch, G.; Schirmer, M.

    2015-11-01

    NGC 253 is the nearest spiral galaxy with a nuclear starburst that becomes the best candidate for studying the relationship between starburst and active galactic nucleus activity. However, this central region is veiled by large amounts of dust, and it has been so far unclear which is the true dynamical nucleus to the point that there is no strong evidence that the galaxy harbors a supermassive black hole co-evolving with the starburst as was supposed earlier. Near-infrared (NIR) spectroscopy, especially NIR emission line analysis, could be advantageous in shedding light on the true nucleus identity. Using Flamingos-2 at Gemini South we have taken deep K-band spectra along the major axis of the central structure and through the brightest infrared source. In this work, we present evidence showing that the brightest NIR and mid-infrared source in the central region, already known as radio source TH7 and so far considered just a large stellar supercluster, in fact presents various symptoms of a genuine galactic nucleus. Therefore, it should be considered a valid nucleus candidate. Mentioning some distinctive aspects, it is the most massive compact infrared object in the central region, located at 2.″0 of the symmetry center of the galactic bar, as measured in the K-band emission. Moreover, our data indicate that this object is surrounded by a large circumnuclear stellar disk and it is also located at the rotation center of the large molecular gas disk of NGC 253. Furthermore, a kinematic residual appears in the H2 rotation curve with a sinusoidal shape consistent with an outflow centered in the candidate nucleus position. The maximum outflow velocity is located about 14 pc from TH7, which is consistent with the radius of a shell detected around the nucleus candidate, observed at 18.3 μm (Qa) and 12.8 μm ([Ne ii]) with T-ReCS. Also, the Brγ emission line profile shows a pronounced blueshift and this emission line also has the highest equivalent width at this

  3. Compound Nucleus Contributions to the Optical Potential

    SciTech Connect

    Thompson, I. J.; Dietrich, F. S.; Escher, J. E.; Dupuis, M.

    2008-04-17

    An ab-initio calculation of the optical potential for neutron-nucleus scattering has been performed by explicitly coupling the elastic channel to all the particle-hole (p-h) excitation states in the target. These p-h states may be regarded as doorway states through which the flux flows to more complicated configurations, and (in the end) to long-lived compound nucleus resonances. The random-phase approximation (RPA) provides the linear combinations of p-h states that include the residual interactions within the target, and we show preliminary results for elastic flux loss using both p-h and RPA descriptions of target excitations.

  4. Quasi-elastic neutrino-nucleus reactions

    NASA Astrophysics Data System (ADS)

    Valverde, M.; Nieves, J.; Amaro, J. E.

    2006-05-01

    The quasi-elastic contribution of the nuclear inclusive electron scattering model developed in [A. Gil, J. Nieves, and E. Oset: Nucl. Phys. A 627 (1997) 543] is extended to the study of electroweak charged current induced nuclear reactions at intermediate energies of interest for future neutrino oscillation experiments. The model accounts for long-range nuclear (RPA) correlations, final state interaction and Coulomb corrections. RPA correlations are shown to play a crucial role in the whole range of neutrino energies, up to 500 MeV, studied in this work. Predictions for inclusive muon capture for different nuclei, and for the reactions 12C(ν μ , μ -)X and 12C(ν e, e-)X near threshold are also given.

  5. Identification of high-risk Listeria monocytogenes serotypes in lineage I (serotype 1/2a, 1/2c, 3a and 3c) using multiplex PCR

    USDA-ARS?s Scientific Manuscript database

    Aims: Using molecular subtyping techniques, Listeria monocytogenes is divided into three major phylogenetic lineages, and a multiplex PCR method can differentiate five L. monocytogenes subgroups: 1/2a-3a, 1/2c-3c, 1/2b-3b-7, 4b-4d-4e, and 4a-4c. In the current study, we conducted genome comparison...

  6. Regiospecific synthesis of 3-substituted imidazo[1,2-a]pyridines, imidazo[1,2-a]pyrimidines, and imidazo[1,2-c]pyrimidine.

    PubMed

    Katritzky, Alan R; Xu, Yong-Jiang; Tu, Hongbin

    2003-06-13

    3-Substituted imidazo[1,2-a]pyridines, imidazo[1,2-a]pyrimidines, and imidazo[1,2-c]pyrimidine were obtained regiospecifically in yields of 35-92% in one pot by reaction of 2-aminopyridines or 2-(or 4-)aminopyrimidines, respectively, with 1,2-bis(benzotriazolyl)-1,2-(dialkylamino)ethanes.

  7. Draft Genome Sequences of Listeria monocytogenes Serotype 4b Strains 944 and 2993 and Serotype 1/2c Strains 198 and 2932

    PubMed Central

    Casey, Aidan; Fox, Edward M.; Leong, Dara; Gahan, Cormac G. M.; Jordan, Kieran

    2016-01-01

    Listeria monocytogenes is a foodborne pathogen and the causative agent of listeriosis among humans and animals. The draft genome sequences of L. monocytogenes serotype 4b strains 944 and 2993 and serotype 1/2c strains 198 and 2932 are reported here. PMID:27257200

  8. Isotopically-selective two-photon ionization of 12C- and 13C-benzene and hexadeuterobenzene in a time-of-flight mass spectrometer

    NASA Astrophysics Data System (ADS)

    de La Cruz, A.; Ortiz, M.; Cabrera, J. A.; Campos, J.

    1994-04-01

    In this work the 610 band spectra for 12C6H6, 12C6D6, 13C12C5H6 and 13C12C5D6 isotopically-substituted benzenes are reported. Spectra of deuterated species are given for the first time. These molecular spectra can be employed to test the technical performances of REMPI-TOFMS systems. The experimental method was laser-induced two-photon ionization of molecules cooled in a He supersonic beam followed by time-of-flight mass spectrometry. A splitting of the 610 band appears when a 13C atom is present in the benzene-ring, favoring the isotope selectivity. In the present experiment a complete mass discrimination has been accomplished by using appropriate electronic circuits. A proportional counter has been used to obtain the corresponding spectra of the molecules at 300 K. The device is very useful to tune the laser wavelength to resonance in this kind of mass spectrometry experiment.

  9. Kinetic 12C/13C isotope fractionation by invertase: evidence for a small in vitro isotope effect and comparison of two techniques for the isotopic analysis of carbohydrates.

    PubMed

    Mauve, Caroline; Bleton, Jean; Bathellier, Camille; Lelarge-Trouverie, Caroline; Guérard, Florence; Ghashghaie, Jaleh; Tchapla, Alain; Tcherkez, Guillaume

    2009-08-30

    The natural (13)C/(12)C isotope composition (delta(13)C) of plants and organic compounds within plant organs is a powerful tool to understand carbon allocation patterns and the regulation of photosynthetic or respiratory metabolism. However, many enzymatic fractionations are currently unknown, thus impeding our understanding of carbon trafficking pathways within plant cells. One of them is the (12)C/(13)C isotope effect associated with invertases (EC 3.2.1.26) that are cornerstone enzymes for Suc metabolism and translocation in plants. Another conundrum of isotopic plant biology is the need to measure accurately the specific delta(13)C of individual carbohydrates. Here, we examined two complementary methods for measuring the delta(13)C value of sucrose, glucose and fructose, that is, off-line high-performance liquid chromatography (HPLC) purification followed by elemental analysis and isotope ratio mass spectrometry (EA-IRMS) analysis, and gas chromatography-combustion (GC-C)-IRMS. We also used these methods to determine the in vitro (12)C/(13)C isotope effect associated with the yeast invertase. Our results show that, although providing more variable values than HPLC approximately EA-IRMS, and being sensitive to derivatization conditions, the GC-C-IRMS method gives reliable results. When applied to the invertase reaction, both methods indicate that the (12)C/(13)C isotope effect is rather small and it is not affected by the use of heavy water (D(2)O). 2009 John Wiley & Sons, Ltd.

  10. The effect of microdosimetric 12C6+ heavy ion irradiation and Mg2+ on canthaxanthin production in a novel strain of Dietzia natronolimnaea

    PubMed Central

    2013-01-01

    Background Dietzia natronolimnaea is one of the most important bacterial bioresources for high efficiency canthaxanthin production. It produces the robust and stable pigment canthaxanthin, which is of special interest for the development of integrated biorefineries. Mutagenesis employing 12C6+ irradiation is a novel technique commonly used to improve microorganism productivity. This study presents a promising route to obtaining the highest feasible levels of biomass dry weight (BDW), and total canthaxanthin by using a microdosimetric model of 12C6+ irradiation mutation in combination with the optimization of nutrient medium components. Results This work characterized the rate of both lethal and non-lethal dose mutations for 12C6+ irradiation and the microdosimetric kinetic model using the model organism, D. natronolimnaea svgcc1.2736. Irradiation with 12C6+ ions resulted in enhanced production of canthaxanthin, and is therefore an effective method for strain improvement of D. natronolimnaea svgcc1.2736. Based on these results an optimal dose of 0.5–4.5 Gy, Linear energy transfer (LET) of 80 keV μm-1and energy of 60 MeV u-1 for 12C6+ irradiation are ideal for optimum and specific production of canthaxanthin in the bacterium. Second-order empirical calculations displaying high R-squared (0.996) values between the responses and independent variables were derived from validation experiments using response surface methodology. The highest canthaxanthin yield (8.14 mg) was obtained with an optimized growth medium containing 21.5 g L-1 D-glucose, 23.5 g L-1 mannose and 25 ppm Mg2+ in 1 L with an irradiation dose of 4.5 Gy. Conclusions The microdosimetric 12C6+ irradiation model was an effective mutagenic technique for the strain improvement of D. natronolimnaea svgcc1.2736 specifically for enhanced canthaxanthin production. At the very least, random mutagenesis methods using 12C6+ions can be used as a first step in a combined approach with long-term continuous

  11. Pion-nucleon scattering and pion production in nucleon-nucleon and nucleus-nucleus collisions

    SciTech Connect

    Dover, C.B.

    1982-01-01

    Lecture notes are presented on the following: (1) basic aspects of ..pi..N interactions (properties of pions and nucleons, SU(3) and SU(6) classification phenomenology of ..pi..N scattering ((3.3) resonance; phase shift analysis, and bag model approach to ..pi..N); (2) pion production and absorption in the two nucleon system (NN ..-->.. NN..pi.. (isobar model) and ..pi..d reversible NN (existence of dibaryon resonances)); (3) pion absorption in complex nuclei (multiparticle aspects and cascade calculations); and (4) pion production with nuclear targets including (a) nucleon-nucleus, (b) nucleus-nucleus (Fermi-averaged 2-body vs thermodynamic models), and (c) ..pi pi.. interoferometry.

  12. TWO-PHOTON PHYSICS IN NUCLEUS-NUCLEUS COLLISIONS AT RHIC.

    SciTech Connect

    NYSTRAND,J.

    1998-09-10

    Ultra-relativistic heavy-ions carry strong electromagnetic and nuclear fields. Interactions between these fields in peripheral nucleus-nucleus collisions can probe many interesting physics topics. This presentation will focus on coherent two-photon and photonuclear processes at RHIC. The rates for these interactions will be high. The coherent coupling of all the protons in the nucleus enhances the equivalent photon flux by a factor Z{sup 2} up to an energy of {approx} 3 GeV. The plans for studying coherent interactions with the STAR experiment will be discussed. Experimental techniques for separating signal from background will be presented.

  13. Two-photon physics in nucleus-nucleus collisions at RHIC

    SciTech Connect

    Nystrand, J.; Klein, S.

    1998-09-01

    Ultra-relativistic heavy-ions carry strong electromagnetic and nuclear fields. Interactions between these fields in peripheral nucleus-nucleus collisions can probe many interesting physics topics. This presentation will focus on coherent two-photon and photonuclear processes at RHIC. The rates for these interactions will be high. The coherent coupling of all the protons in the nucleus enhances the equivalent photon flux by a factor Z{sup 2} up to an energy of {approx} 3 GeV. The plans for studying coherent interactions with the STAR experiment will be discussed. Experimental techniques for separating signal from background will be presented.

  14. Fermi-motion effect on the intermediate energy nucleus-nucleus collision

    NASA Astrophysics Data System (ADS)

    Fan, G. W.; Kong, W. Y.; Han, T. F.; Li, X. C.; Ma, J. B.; Sheng, Z. Q.; Shi, G. Z.; Tian, F.; Wang, J.; Zhang, C.

    2016-11-01

    The Glauber model is modified with the Fermi-motion effect in the calculation of elastic differential cross-sections and momentum distributions of a fragment from mother nucleus. Different reaction systems at low energies are calculated with the modified Glauber model. It is found that calculations including the Fermi-motion provide a better prescription relating the model to a proper nuclear density distribution by comparing with the experimental data. On the basis of the studies, the influence of the correction on the extracted nuclear radius is quantified. The results further confirm the importance of the Fermi-motion in the nucleus-nucleus collision reactions at low energies.

  15. The Checkerboard Model of the Nucleus

    NASA Astrophysics Data System (ADS)

    Lach, Theodore

    2015-04-01

    The Checker Board Model (CBM) of the nucleus and the associated extended standard model predicts that nature has 5 generations of quarks not 3 and that Nucleus is 2 dimensional. The CBM theory began with an insight into the structure of the He nucleus around the year 1989. Details of how this theory evolved which took many years, and is found on my web site (http://checkerboard.dnsalias.net) or in the following references One independent check of this model is that the wavelength of the ``up'' quark orbiting inside the proton at 84.8123% the speed of light (around the ``dn'' quark in the center of the proton) turns out to be exactly one de Broglie wavelength something determined after the mass and speed of the up quark were determined by other means. This theory explains the mass of the proton and neutron and their magnetic moments and this along with the beautiful symmetric 2D structure of the He nucleus led to the evolution of this theory. When this theory was first presented at Argonne in 1996, it was the first time that anyone had predicted the quarks orbited inside the proton at relativistic speeds and it was met with skepticism.

  16. The Nucleus and the Simple Microscope.

    ERIC Educational Resources Information Center

    Ford, Brian J.

    1982-01-01

    The 150th anniversary of the naming of the nucleus by Robert Brown in 1831 was commemorated by re-creating some of his most important observations using two of his microscopes. Comments on Brown's career and the microtechnique employed during his time are provided. (Author/JN)

  17. Oral alprazolam acutely increases nucleus accumbens perfusion

    PubMed Central

    Wolf, Daniel H.; Pinkham, Amy E.; Satterthwaite, Theodore D.; Ruparel, Kosha; Elliott, Mark A.; Valdez, Jeffrey; Smith, Mark A.; Detre, John A.; Gur, Ruben C.; Gur, Raquel E.

    2014-01-01

    Benzodiazepines treat anxiety, but can also produce euphoric effects, contributing to abuse. Using perfusion magnetic resonance imaging, we provide the first direct evidence in humans that alprazolam (Xanax) acutely increases perfusion in the nucleus accumbens, a key reward-processing region linked to addiction. PMID:23070072

  18. THE ROLE OF THE NUCLEUS IN OXIDATION.

    PubMed

    Osterhout, W J

    1917-10-12

    Injury produces in the leaf-cells of the Indian Pipe (Monotropa uniflora) a darkening which is due to oxidation. The oxidation is much more rapid in the nucleus than in the cytoplasm and the facts indicate that this is also the case with the oxidation of the uninjured cell.

  19. Nucleon-nucleus interactions from JACEE

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Dake, S.; Fuki, M.; Gregory, J. C.; Hayashi, T.; Holynski, R.; Iwai, J.; Jones, W. V.; Jurak, A.; Lord, J. J.

    1985-01-01

    Results on hadron-nucleus interactions from the Japanese-American Cooperation Emulsion Experiment experiment are presented. Angular distributions for charged particles, and angular and transverse momentum spectra for photons have been measured for a sample of events with sigma epsilon sub gamma. Results on central rapidity density and transverse energy flow are discussed.

  20. Nucleus-associated actin in Amoeba proteus.

    PubMed

    Berdieva, Mariia; Bogolyubov, Dmitry; Podlipaeva, Yuliya; Goodkov, Andrew

    2016-10-01

    The presence, spatial distribution and forms of intranuclear and nucleus-associated cytoplasmic actin were studied in Amoeba proteus with immunocytochemical approaches. Labeling with different anti-actin antibodies and staining with TRITC-phalloidin and fluorescent deoxyribonuclease I were used. We showed that actin is abundant within the nucleus as well as in the cytoplasm of A. proteus cells. According to DNase I experiments, the predominant form of intranuclear actin is G-actin which is associated with chromatin strands. Besides, unpolymerized actin was shown to participate in organization of a prominent actin layer adjacent to the outer surface of nuclear envelope. No significant amount of F-actin was found in the nucleus. At the same time, the amoeba nucleus is enclosed in a basket-like structure formed by circumnuclear actin filaments and bundles connected with global cytoplasmic actin cytoskeleton. A supposed architectural function of actin filaments was studied by treatment with actin-depolymerizing agent latrunculin A. It disassembled the circumnuclear actin system, but did not affect the intranuclear chromatin structure. The results obtained for amoeba cells support the modern concept that actin is involved in fundamental nuclear processes that have evolved in the cells of multicellular organisms.

  1. New developments in nucleus pulposus replacement technology.

    PubMed

    Carl, Allen; Ledet, Eric; Yuan, Hansen; Sharan, Alok

    2004-01-01

    Attempts to alleviate the pain attributed to degeneration of the nucleus pulposus using replacement or reinforcement techniques dating back to the 1950s are reviewed. The various materials and their insertion techniques are discussed as are results available from early clinical experiences. These techniques are in evolution and clinical outcomes will be necessary to establish the efficacy of these approaches.

  2. Average transverse momentum and energy density in high-energy nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Dake, S.; Fuki, M.; Gregory, J. C.; Hayashi, T.; Holynski, R.; Iwai, J.; Jones, W. V.; Jurak, A.; Lord, J. J.

    1986-01-01

    Emulsion chambers were used to measure the transverse momenta of photons or pi(0) mesons produced in high-energy cosmic-ray nucleus-nucleus collisions. A group of events having large average transverse momenta has been found which apparently exceeds the expected limiting values. Analysis of the events at early interaction times, of the order of 1 fm/c, indicates that the observed transverse momentum increases with both rapidity density and energy density.

  3. Average transverse momentum and energy density in high-energy nucleus-nucleus collisions

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Dake, S.; Fuki, M.; Gregory, J. C.; Hayashi, T.; Holynski, R.; Iwai, J.; Jones, W. V.; Jurak, A.; Lord, J. J.

    1986-01-01

    Emulsion chambers were used to measure the transverse momenta of photons or pi(0) mesons produced in high-energy cosmic-ray nucleus-nucleus collisions. A group of events having large average transverse momenta has been found which apparently exceeds the expected limiting values. Analysis of the events at early interaction times, of the order of 1 fm/c, indicates that the observed transverse momentum increases with both rapidity density and energy density.

  4. Results on ultra-relativistic nucleus-nucleus interactions from balloon-borne emulsion chambers

    NASA Technical Reports Server (NTRS)

    Burnett, T. H.; Dake, S.; Derrickson, J. H.; Fountain, W.; Meegan, C. A.; Takahashi, Y.; Watts, J. W.; Fuki, M.; Gregory, J. C.; Hayashi, T.

    1985-01-01

    The results of balloon-borne emulsion-chamber measurements on high-energy cosmic-ray nuclei (Burnett et al., 1983) are summarized in tables and graphs and briefly characterized. Special consideration is given to seven nucleus-nucleus interaction events at energy in excess of 1 TeV/A with multiplicity greater than 400, and to Fe interactions (53 with CHO, 10 with emulsion, and 14 with Pb) at 20-60 GeV/A.

  5. Ventral nucleus of the lateral lemniscus in guinea pigs: cytoarchitecture and inputs from the cochlear nucleus.

    PubMed

    Schofield, B R; Cant, N B

    1997-03-17

    Cytoarchitectonic criteria were used to distinguish three subdivisions of the ventral nucleus of the lateral lemniscus in guinea pigs. Axonal tracing techniques were used to examine the projections from the cochlear nucleus to each subdivision. Based on the cell types they contain and their patterns of input, we distinguished ventral, dorsal, and anterior subdivisions of the ventral nucleus of the lateral lemniscus. All three subdivisions receive bilateral inputs from the cochlear nucleus, with contralateral inputs greatly outnumbering ipsilateral inputs. However, the relative density of the inputs varies: the ventral subdivision receives the densest projection, whereas the anterior subdivision receives the sparsest projection. Further differences are apparent in the morphology of the afferent axons. Following an injection of Phaseolus vulgaris-leucoagglutinin into the ventral cochlear nucleus, most of the axons on the contralateral side and all of the axons on the ipsilateral side are thin. Thick axons are present only in the ventral subdivision contralateral to the injection site. The evidence from both anterograde and retrograde tracing studies suggests that the thick axons originate from octopus cells, whereas the thin axons arise from multipolar cells and spherical bushy cells. The differences in constituent cell types and in patterns of inputs suggest that each of the three subdivisions of the ventral nucleus of the lateral lemniscus makes a distinct contribution to the analysis of acoustic signals.

  6. The Neutrophil Nucleus and Its Role in Neutrophilic Function.

    PubMed

    Carvalho, Leonardo Olivieri; Aquino, Elaine Nascimento; Neves, Anne Caroline Dias; Fontes, Wagner

    2015-09-01

    The cell nucleus plays a key role in differentiation processes in eukaryotic cells. It is not the nucleus in particular, but the organization of the genes and their remodeling that provides the data for the adjustments to be made according to the medium. The neutrophil nucleus has a different morphology. It is a multi-lobed nucleus where some researchers argue no longer function. However, studies indicate that it is very probable the occurrence of chromatin remodeling during activation steps. It may be that the human neutrophil nucleus also contributes to the mobility of neutrophils through thin tissue spaces. Questions like these will be discussed in this small review. The topics include morphology of human neutrophil nucleus, maturation process and modifications of the neutrophil nucleus, neutrophil activation and chromatin modifications, causes and consequences of multi-lobulated segmented morphology, and importance of the nucleus in the formation of neutrophil extracellular traps (NETs). © 2015 Wiley Periodicals, Inc.

  7. Why do we have a caudate nucleus?

    PubMed

    Villablanca, Jaime R

    2010-01-01

    In order to understand the physiological role of the caudate nucleus, we combine here our laboratory data on cats with reports of patients with selective damage to this nucleus. Cats with bilateral removal of the caudate nuclei showed a stereotyped behavior consisting of persistently approaching and then following a person, another cat, or any object, and attempting to contact the target. Simultaneously, the animals exhibited a friendly disposition and persistent docility together with purring and forelimbs treading/kneading. The magnitude and duration of this behavior was proportional to the extent of the removal reaching a maximum after ablations of 65% or more of the caudate tissue. These cats were hyperactive but they had lost the feline elegance of movements. Additional features of acaudate cats were: (1) postural and accuracy deficits (plus perseveration) in paw usage tasks including bar pressing for food reward; (2) cognitive and perceptual impairments on a T-maze battery of tasks and on the bar pressing tasks; (3) blockage or blunting of the species-specific behavioral response to a single injection of morphine; Unilateral caudate nucleus removal did not produce global behavioral effects, but only deficit in the contralateral paw contact placing reaction and paw usage/bar pressing. Moreover and surprisingly, we found hypertrophy of the ipsilateral caudate nucleus following prenatal focal neocortical removal. The findings in human were also behavioral (not neurological) and also occurred with unilateral caudate damage. The main manifestations consisted of loss of drive (apathy), obsessive-compulsive behavior, cognitive deficits, stimulus-bound perseverative behavior, and hyperactivity. Based on all of the above data we propose that the specific function of the caudate nucleus is to control approach-attachment behavior, ranging from plain approach to a target, to romantic love. This putative function would account well for the caudate involvement in the

  8. Collateral projections from the lateral parabrachial nucleus to the paraventricular thalamic nucleus and the central amygdaloid nucleus in the rat.

    PubMed

    Liang, Shao-Hua; Yin, Jun-Bin; Sun, Yi; Bai, Yang; Zhou, Kai-Xiang; Zhao, Wen-Jun; Wang, Wei; Dong, Yu-Lin; Li, Yun-Qing

    2016-08-26

    Combined the retrograde double tracing with immunofluorescence histochemical staining, we examined the neurons in the lateral parabrachial nucleus (LPB) sent collateral projections to the paraventricular thalamic nucleus (PVT) and central amygdaloid nucleus (CeA) and their roles in the nociceptive transmission in the rat. After the injection of Fluoro-gold (FG) into the PVT and tetramethylrhodamine-dextran (TMR) into the CeA, respectively, FG/TMR double-labeled neurons were observed in the LPB. The percentages of FG/TMR double-labeled neurons to the total number of FG- or TMR-labeled neurons were 6.18% and 9.09%, respectively. Almost all of the FG/TMR double-labeled neurons (95%) exhibited calcitonin gene-related peptide (CGRP) immunoreactivity. In the condition of neuropathic pain, 94% of these neurons showed FOS immunoreactivity. The present data indicates that some of CGRP-expressing neurons in the LPB may transmit nociceptive information toward the PVT and CeA by way of axon collaterals.

  9. FeCl3-mediated three-component cascade reaction: an effective approach to the construction of highly functionalized pyrrolo[1,2-c]quinazolinones.

    PubMed

    Zheng, Hu-Fei; Yu, Zhi-Hua; Yuan, Wei; Tang, Zi-Long; Clough, John; Gu, Yu-Cheng; Shi, De-Qing

    2014-02-03

    An unexpected FeCl3-mediated three-component cascade reaction has been used to construct structurally diverse pyrrolo[1,2-c]quinazolinone derivatives with potential biological activities. This method has advantages of mild conditions, simple work-up, as well as wide substrate scope, which makes it a powerful approach to the synthesis of diverse pyrrolo[1,2-c]quinazolinones. This cascade reaction involves 1,3-dipolar cycloaddition between azomethine ylides and allenoates, followed by intramolecular nucleophilic addition in the presence of FeCl3. The obtained products could be easily transformed into derivatives with the pyrrolo[2,3-c]quinazoline alkaloid skeleton. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Angular distribution of 4.43-MeV γ-rays produced in inelastic scattering of 14.1-MeV neutrons by 12C nuclei

    NASA Astrophysics Data System (ADS)

    Bystritsky, V. M.; Grozdanov, D. N.; Zontikov, A. O.; Kopach, Yu. N.; Rogov, Yu. N.; Ruskov, I. N.; Sadovsky, A. B.; Skoy, V. R.; Barmakov, Yu. N.; Bogolyubov, E. P.; Ryzhkov, V. I.; Yurkov, D. I.

    2016-07-01

    The work is devoted to measuring the angular distribution of 4.43-MeV γ-rays produced in inelastic scattering of 14.1-MeV neutrons by 12C nuclei. A portable ING-27 neutron generator (designed and fabricated at VNIIA, Moscow) with a built-in 64-pixel silicon α-detector was used as a source of tagged neutrons. The γ-rays of characteristic nuclear radiation from 12C were detected with a spectrometric system that consisted of 22 γ-detectors based on NaI(Tl) crystals arranged around the carbon target. The measured angular distribution of 4.43-MeV γ-rays is analyzed and compared with the results of other published experimental works.

  11. Elastic scattering of 10 MeV [sup 6]He from [sup 12]C, [sup nat]Ni, and [sup 197]Au

    SciTech Connect

    Warner, R.E.; Becchetti, F.D.; Jaenecke, J.W.; Roberts, D.A. ); Butts, D.; Carpenter, C.L.; Fetter, J.M.; Muthukrishnan, A. ); Kolata, J.J.; Lamkin, K.; Belbot, M.; Zahar, M. ); Galonsky, A.; Ieki, K.; Zecher, P. )

    1995-01-01

    A radioactive nuclear beam of 10.2 MeV [sup 6]He, with typical intensity 5[times]10[sup 4] s[sup [minus]1], was produced via the [sup 9]Be([sup 7]Li,[sup 6]He)[sup 10]B reaction and elastically scattered from targets of [sup 12]C, [sup nat]Ni, and [sup 197]Au. Scattering from C and Ni was observed through sufficiently large angles (up to 60[degree] c.m. and 85[degree] c.m., respectively) to show large deviations from Rutherford scattering. The Au target gave, as expected, pure Rutherford scattering. Optical potential previously used for low-energy [sup 6]Li and [sup 8]Li ions generally accounted for the shapes of the angular distributions but, for [sup 12]C, predict oscillations not present in the [sup 6]He data. [sup 4]He optical potentials predict much smaller deviations from Rutherford scattering than those observed.

  12. CACA-TOCSY with alternate 13C–12C labeling: a 13Cα direct detection experiment for mainchain resonance assignment, dihedral angle information, and amino acid type identification

    PubMed Central

    Takeuchi, Koh; Frueh, Dominique P.; Sun, Zhen-Yu J.; Hiller, Sebastian

    2010-01-01

    We present a 13C direct detection CACA-TOCSY experiment for samples with alternate 13C–12C labeling. It provides inter-residue correlations between 13Cα resonances of residue i and adjacent Cαs at positions i − 1 and i + 1. Furthermore, longer mixing times yield correlations to Cα nuclei separated by more than one residue. The experiment also provides Cα-to-sidechain correlations, some amino acid type identifications and estimates for ψ dihedral angles. The power of the experiment derives from the alternate 13C–12C labeling with [1,3-13C] glycerol or [2-13C] glycerol, which allows utilizing the small scalar 3JCC couplings that are masked by strong 1JCC couplings in uniformly 13C labeled samples. PMID:20383561

  13. {sup 12}C({alpha},{gamma}){sup 16}O E2 cross section: R-matrix fits combined with a microscopic cluster model

    SciTech Connect

    Dufour, M.

    2008-07-15

    The E2 component of the {sup 12}C({alpha},{gamma}){sup 16}O cross section is investigated in two ways: by a microscopic cluster model, and by R-matrix fits. The {alpha}+{sup 12}C microscopic calculation is performed in the framework of the generator coordinate method (GCM) by including all {sup 12}C states (T=0) within the p shell. Using different nucleon-nucleon interactions we find S{sub E2}(300 keV){approx_equal}50 keV {center_dot} b for ground-state transitions. We also study cascade transitions to the 0{sub 2}{sup +} and 2{sub 1}{sup +} excited states of {sup 16}O. Then the S-factor is analyzed in the phenomenological R-matrix theory. We show that the background term plays a crucial role, and cannot be determined without ambiguity. Using the experimental phase shifts and capture cross sections, only an upper limit on the extrapolated S factor can be obtained [S{sub E2}(300 keV)<190 keV {center_dot} b]. To constrain the R-matrix analysis, we use the GCM asymptotic normalization constant (ANC) of the 2{sub 1}{sup +} level, well known to be a cluster state. This procedure strongly reduces the uncertainties on the R-matrix fit, and we end up with a recommended value of S{sub E2}(300 keV)=42{+-}2 keV {center_dot} b. We show that ANC values derived from indirect methods are not consistent with the {sup 12}C({alpha},{gamma}){sup 16}O cascade transitions to the 2{sub 1}{sup +} state, and suggest that a remeasurement of this cross section is desirable.

  14. Comparative study of dose distributions and cell survival fractions for 1H, 4He, 12C and 16O beams using Geant4 and Microdosimetric Kinetic model

    NASA Astrophysics Data System (ADS)

    Burigo, Lucas; Pshenichnov, Igor; Mishustin, Igor; Bleicher, Marcus

    2015-04-01

    Depth and radial dose profiles for therapeutic 1H, 4He, 12C and 16O beams are calculated using the Geant4-based Monte Carlo model for Heavy-Ion Therapy (MCHIT). 4He and 16O ions are presented as alternative options to 1H and 12C broadly used for ion-beam cancer therapy. Biological dose profiles and survival fractions of cells are estimated using the modified Microdosimetric Kinetic model. Depth distributions of cell survival of healthy tissues, assuming 10% and 50% survival of tumor cells, are calculated for 6 cm SOBPs at two tumor depths and for different tissues radiosensitivities. It is found that the optimal ion choice depends on (i) depth of the tumor, (ii) dose levels and (iii) the contrast of radiosensitivities of tumor and surrounding healthy tissues. Our results indicate that 12C and 16O ions are more appropriate to spare healthy tissues in the case of a more radioresistant tumor at moderate depths. On the other hand, a sensitive tumor surrounded by more resistant tissues can be better treated with 1H and 4He ions. In general, 4He beam is found to be a good candidate for therapy. It better spares healthy tissues in all considered cases compared to 1H. Besides, the dose conformation is improved for deep-seated tumors compared to 1H, and the damage to surrounding healthy tissues is reduced compared to heavier ions due to the lower impact of nuclear fragmentation. No definite advantages of 16O with respect to 12C ions are found in this study.

  15. Measurements of the Elastic and Inelastic Scattering Cross Sections of 13C Ions on 12C Nuclei at the Near Coulomb Barrier Energy

    NASA Astrophysics Data System (ADS)

    Burtebayev, N.; Burtebayeva, J.; Duisebayev, A.; Zholdybayev, T.; Nassurlla, Maulen; Nassurlla, Marzhan; Spitaleri, C.; Sakuta, S. B.; Piasecki, E.; Rusek, K.; Trzcińska, A.; Wolińska-Cichocka, M.; Artemov, S. V.

    Differential cross sections for elastic scattering of 13C ions on the nuclei 12C were measured using extracted beam from the cyclotron K = 160 HIL (Warsaw University) in wide range of angles at energy 2.5 MeV/nucleon. The angular distribution showed almost monotonic decrease of the cross sections at forward hemisphere. An increase in differential cross section starting from intermediate angles is predicted by coupled channels calculations.

  16. The Galactic R Coronae Borealis Stars: The C2 Swan Bands, the Carbon Problem, and the 12C/13C Ratio

    NASA Astrophysics Data System (ADS)

    Hema, B. P.; Pandey, Gajendra; Lambert, David L.

    2012-03-01

    Observed spectra of R Coronae Borealis (RCB) and hydrogen-deficient carbon (HdC) stars are analyzed by synthesizing the C2 Swan bands (1, 0), (0, 0), and (0, 1) using our detailed line list and the Uppsala model atmospheres. The (0, 1) and (0, 0) C2 bands are used to derive the 12C abundance, and the (1, 0) 12C13C band to determine the 12C/13C ratios. The carbon abundance derived from the C2 Swan bands is about the same for the adopted models constructed with different carbon abundances over the range 8.5 (C/He = 0.1%) to 10.5 (C/He = 10%). Carbon abundances derived from C I lines are about a factor of four lower than the carbon abundance of the adopted model atmosphere over the same C/He interval, as reported by Asplund et al., who dubbed the mismatch between adopted and derived C abundance as the "carbon problem." In principle, the carbon abundances obtained from C2 Swan bands and that assumed for the model atmosphere can be equated for a particular choice of C/He that varies from star to star. Then, the carbon problem for C2 bands is eliminated. However, such C/He ratios are in general less than those of the extreme helium stars, the seemingly natural relatives to the RCB and HdC stars. A more likely solution to the C2 carbon problem may lie in a modification of the model atmosphere's temperature structure. The derived carbon abundances and the 12C/13C ratios are discussed in light of the double degenerate and the final flash scenarios.

  17. Bisannelation with a benzo(1,2-c:4,5-c-prime) difuran equivalent - A new route to linear acene derivatives

    NASA Technical Reports Server (NTRS)

    Luo, Jihmei; Hart, Harold

    1988-01-01

    It was observed that the base peak in the mass spectra of all the Diels-Alder bis adducts of anthracene diendoxide as well as of its tetrahydro derivative appear at m/e 158, corresponding to the radical cation of benzo(1,2-c:4,5-c-prime) difuran (BDF). This paper describes a synthetic equivalent of BDF and demonstrates its utility for obtaining linear acene derivatives.

  18. Bisannelation with a benzo(1,2-c:4,5-c-prime) difuran equivalent - A new route to linear acene derivatives

    NASA Technical Reports Server (NTRS)

    Luo, Jihmei; Hart, Harold

    1988-01-01

    It was observed that the base peak in the mass spectra of all the Diels-Alder bis adducts of anthracene diendoxide as well as of its tetrahydro derivative appear at m/e 158, corresponding to the radical cation of benzo(1,2-c:4,5-c-prime) difuran (BDF). This paper describes a synthetic equivalent of BDF and demonstrates its utility for obtaining linear acene derivatives.

  19. Resonance strengths in the {sup 14}N(p,gamma){sup 15}O and {sup 15}N(p,alphagamma){sup 12}C reactions

    SciTech Connect

    Marta, Michele; Trompler, Erik; Bemmerer, Daniel; Beyer, Roland; Grosse, Eckart; Hannaske, Roland; Junghans, Arnd R.; Nair, Chithra; Schwengner, Ronald; Wagner, Andreas; Yakorev, Dmitry; Broggini, Carlo; Caciolli, Antonio; Erhard, Martin; Menegazzo, Roberto; Fueloep, Zsolt; Gyuerky, Gyoergy; Szuecs, Tamas; Vezzu, Simone

    2010-05-15

    The {sup 14}N(p,gamma){sup 15}O reaction is the slowest reaction of the carbon-nitrogen-oxygen cycle of hydrogen burning in stars. As a consequence, it determines the rate of the cycle. The {sup 15}N(p,alphagamma){sup 12}C reaction is frequently used in inverse kinematics for hydrogen depth profiling in materials. The {sup 14}N(p,gamma){sup 15}O and {sup 15}N(p,alphagamma){sup 12}C reactions have been studied simultaneously, using titanium nitride targets of natural isotopic composition and a proton beam. The strengths of the resonances at E{sub p} = 1058 keV in {sup 14}N(p,gamma){sup 15}O and at E{sub p} = 897 and 430 keV in {sup 15}N(p,alphagamma){sup 12}C have been determined with improved precision, relative to the well-known resonance at E{sub p} = 278 keV in {sup 14}N(p,gamma){sup 15}O. The new recommended values are omegagamma=0.353+-0.018, 362+-20, and 21.9+-1.0 eV for their respective strengths. In addition, the branching ratios for the decay of the E{sub p} = 1058 keV resonance in {sup 14}N(p,gamma){sup 15}O have been redetermined. The data reported here should facilitate future studies of off-resonant capture in the {sup 14}N(p,gamma){sup 15}O reaction that are needed for an improved R-matrix extrapolation of the cross section. In addition, the data on the 430 keV resonance in {sup 15}N(p,alphagamma){sup 12}C may be useful for hydrogen depth profiling.

  20. Nonequilibrium neutron emission from /sup 12/C + /sup 158/Gd and /sup 13/C + /sup 157/Gd reactions. [103 to 160 MeV

    SciTech Connect

    Plasil, F.; Beene, J.R.; Ferguson, R.L.

    1981-01-01

    The energy dependence of nonequilibrium neutron emission (NNE) and the effects of projectile structure were investigated in these reactions between 103 and 160 MeV. Neutron energy spectra and angular distributions were measured. Typical spectra show no projectile structure effect. The absence of difference in NNE between /sup 12/C- and /sup 13/C-induced reactions was also noted. The Wilczynski model agrees well with the data. 5 figures, 1 table. (RWR)

  1. Four-body calculation of {sup 12}C(α, γ){sup 16}O radiative capture reaction at stellar energies

    SciTech Connect

    Sadeghi, H.; Firoozabadi, M. M.

    2016-01-15

    On the basis of the four-alphamodel, the {sup 12}C(α, γ){sup 16}Oradiative capture process is investigated by using the four-body Faddeev–Yakubovsky equations as well as the two- and three-body electromagnetic currents. The present calculation is an application of our current conservation realistic potentials method for the {sup 12}C(α, γ){sup 16}Oradiative capture process. This work clears the way formore refinedmodels of radiative capture based on two- and three-body realistic potentials and current conservation. The calculation is carried out by considering the {sup 4}He + {sup 12}C (1 + 3) and the {sup 8}Be + {sup 8}Be (2 + 2) subamplitudes, respectively. Radiative capture {sup 12}C(α, γ){sup 16}Oreaction is one of the most important reactions in nuclear astrophysics. For this reaction, the electric dipole transitions between states with the same isospin are forbidden in the first order. Because the state 1{sup +} and 0{sup +} ground state nuclei {sup 16}O have zero isospin, thus the electric dipole radiations are not at the first order between two levels and electric dipole radiation will be the second order and electric dipole radiation is the same order as the electric quadrupole radiation. Therefore, we must consider the effects of both radiations. In comparison with other theoretical methods and available experimental data, good agreement is achieved for the E{sub 1} and E{sub 2} contribution to the cross section and the astrophysical S factor for this process.

  2. THE GALACTIC R CORONAE BOREALIS STARS: THE C{sub 2} SWAN BANDS, THE CARBON PROBLEM, AND THE {sup 12}C/{sup 13}C RATIO

    SciTech Connect

    Hema, B. P.; Pandey, Gajendra; Lambert, David L. E-mail: pandey@iiap.res.in

    2012-03-10

    Observed spectra of R Coronae Borealis (RCB) and hydrogen-deficient carbon (HdC) stars are analyzed by synthesizing the C{sub 2} Swan bands (1, 0), (0, 0), and (0, 1) using our detailed line list and the Uppsala model atmospheres. The (0, 1) and (0, 0) C{sub 2} bands are used to derive the {sup 12}C abundance, and the (1, 0) {sup 12}C{sup 13}C band to determine the {sup 12}C/{sup 13}C ratios. The carbon abundance derived from the C{sub 2} Swan bands is about the same for the adopted models constructed with different carbon abundances over the range 8.5 (C/He = 0.1%) to 10.5 (C/He = 10%). Carbon abundances derived from C I lines are about a factor of four lower than the carbon abundance of the adopted model atmosphere over the same C/He interval, as reported by Asplund et al., who dubbed the mismatch between adopted and derived C abundance as the 'carbon problem'. In principle, the carbon abundances obtained from C{sub 2} Swan bands and that assumed for the model atmosphere can be equated for a particular choice of C/He that varies from star to star. Then, the carbon problem for C{sub 2} bands is eliminated. However, such C/He ratios are in general less than those of the extreme helium stars, the seemingly natural relatives to the RCB and HdC stars. A more likely solution to the C{sub 2} carbon problem may lie in a modification of the model atmosphere's temperature structure. The derived carbon abundances and the {sup 12}C/{sup 13}C ratios are discussed in light of the double degenerate and the final flash scenarios.

  3. Inelastic scattering of 65 MeV protons from /sup 12/C, /sup 24/Mg, /sup 28/Si, and /sup 32/S

    SciTech Connect

    Kato, S.; Okada, K.; Kondo, M.; Hosono, K.; Saito, T.; Matsuoka, N.; Hatanaka, K.; Noro, T.; Nagamachi, S.; Shimizu, H.; Ogino, K.; Kadota, Y.; Matsuki, S.; Wakai, M.

    1985-05-01

    Measurements of angular distributions of the cross sections and analyzing powers for the elastic and inelastic scatterings of 65 MeV polarized protons from /sup 12/C, /sup 24/Mg, /sup 28/Si, and /sup 32/S are reported. Coupled channels analyses of the scattering data are presented assuming the 0/sub 1//sup +/, 2/sub 1//sup +/, and 4/sub 1//sup +/ states to be members of the ground band, the 0/sub 2//sup +/ state to begin the

  4. Different metabolic responses to PI3K inhibition in NSCLC cells harboring wild-type and G12C mutant KRAS

    PubMed Central

    Marabese, Mirko; Broggini, Massimo; Lupi, Monica; Pastorelli, Roberta

    2016-01-01

    KRAS mutations in non-small-cell lung cancer (NSCLC) patients are considered a negative predictive factor and indicate poor response to anticancer treatments. KRAS mutations lead to activation of the PI3K/akt/mTOR pathway, whose inhibition remains a challenging clinical target. Since the PI3K/akt/mTOR pathway and KRAS oncogene mutations all have roles in cancer cell metabolism, we investigated whether the activity of PI3K/akt/mTOR inhibitors (BEZ235 and BKM120) in cells harboring different KRAS status is related to their metabolic effect. Isogenic NSCLC cell clones expressing wild-type (WT) and mutated (G12C) KRAS were used to determine the response to BEZ235 and BKM120. Metabolomics analysis indicated the impairment of glutamine in KRAS-G12C and serine metabolism in KRAS-WT, after pharmacological blockade of the PI3K signaling, although the net effect on cell growth, cell cycle distribution and caspase activation was similar. PI3K inhibitors caused autophagy in KRAS-WT, but not in KRAS-G12C, where there was a striking decrease in ammonia production, probably a consequence of glutamine metabolism impairment. These findings lay the grounds for more effective therapeutic combinations possibly distinguishing wild-type and mutated KRAS cancer cells in NSCLC, exploiting their different metabolic responses to PI3K/akt/mTOR inhibitors. PMID:27283493

  5. Millimeter-Wave Observations of Circumstellar 14N/15N and 12C/13C Ratios: New Insights into J-Type Stars

    NASA Astrophysics Data System (ADS)

    Adande, Gilles; Ziurys, Lucy M.; Woolf, Neville

    2016-06-01

    Measurements of 14N/15N and 12C/13C isotopic ratios have been conducted towards circumstellar envelopes of a sample of evolved stars using the J = 3→2 rotational transitions of the isotopologues of HCN, observed with the Submillimeter Telescope (SMT) of the Arizona Radio Observatory (ARO). Towards the J-type stars Y CVn and RY Dra, where 12C/13C ~ 3, the 14N/15N ratios were found to be 120-180 and 225, respectively. The 14N/15N ratio is thus anomalously low relative to interstellar values and a factor ~100 lower than equilibrium values predicted from the CNO cycle. Combining these results with previous chemical and isotopic prior observations of these stars, we conclude that two anomalous behaviors are likely to have occurred in Y CVn and RY Dra. First, the stellar envelope failed to participate in the normal mixing seen in low mass red giants, in which C and then O are substantially converted to N. Secondly, both the carbon enrichment and anomalous isotopic composition of both 13C and15N could have been caused by a plume of hot gas, hydrogen poor but enriched in 12C, from a helium flash mixing into the envelope.

  6. 8Be+8Be and 12C+α breakup states in 16O populated via the 13C(4He,4 α )n reaction

    NASA Astrophysics Data System (ADS)

    Curtis, N.; Almaraz-Calderon, S.; Aprahamian, A.; Ashwood, N. I.; Barr, M.; Bucher, B.; Copp, P.; Couder, M.; Fang, X.; Freer, M.; Goldring, G.; Jung, F.; Lesher, S. R.; Lu, W.; Malcolm, J. D.; Roberts, A.; Tan, W. P.; Wheldon, C.; Ziman, V. A.

    2016-09-01

    The 13C(4He,4 α )n breakup reaction has been studied at beam energies of 27.0, 27.5, and 28.0 MeV. A comparison with previous measurements of the 12C(4He,8Be)8Be excitation function and 12C(16O,4 α )12C breakup channel suggests the Be8gs+Be8gs decay of 16O is observed from a possible 2+ state at 17.3 ±0.2 MeV, a 4+ state at 18.0 ±0.2 MeV, a 2+ or 4+ state at 19.4 ±0.2 MeV, and a 4+ or 6+ state at 21.0 ±0.2 MeV. The 2+ or 4+ assignment for the (19.4 ±0.2 )-MeV state appears to be supported by the relative cross sections expected for resonant and sequential breakup reactions.

  7. Vitamin B12[c-lactone], a biologically inactive corrinoid compound, occurs in cultured and dried lion's mane mushroom (Hericium erinaceus) fruiting bodies.

    PubMed

    Teng, Fei; Bito, Tomohiro; Takenaka, Shigeo; Yabuta, Yukinori; Watanabe, Fumio

    2014-02-19

    This study determined the vitamin B12 content of the edible medicinal mushroom Hericium erinaceus, lion's mane mushroom fruiting body, using a microbiological assay based on Lactobacillus delbrueckii ATCC 7830. Trace levels (0.04-0.36 μg/100 g dry weight) of vitamin B12 were found in most of the dried mushroom samples, and two samples contained slightly higher levels (0.56 and 1.04 μg/100 g dry weight, respectively) of vitamin B12. We purified the corrinoid compounds from the extracts of dried lion's mane mushroom fruiting bodies using an immunoaffinity column and identified them as vitamin B12 or vitamin B12[c-lactone] (or both) based on LC/ESI-MS/MS chromatograms. This is the first report on an unnatural corrinoid, vitamin B12[c-lactone], occurring in foods. Vitamin B12[c-lactone] was simple to produce during incubation of authentic vitamin B12 and chloramine-T, an antimicrobial agent, at varying pH values (3.0-7.0) and was completely inactive in the vitamin B12-dependent bacteria that are generally used in vitamin B12 bioassays.

  8. Effects of triple-α and 12C(α, γ)16O reaction rates on the supernova nucleosynthesis in a massive star of 25 Mʘ

    NASA Astrophysics Data System (ADS)

    Kikuchi, Yukihiro; Hashimoto, Masa-aki; Ono, Masaomi; Fukuda, Ryohei

    2015-06-01

    We investigate the effects of triple-α and ^{12}{C}(α ,γ )^{16}O reaction rates on the production of supernova yields for a massive star of 25 M_{⊙}. We combine the reaction rates to examine the rate dependence, where the rates are considered to cover the possible variation of the rates based on experiments on the earth and on theory. We adopt four combinations of the reaction rates from two triple-α reaction rates and two ^{12}C(α ,γ )^{16}O ones. First, we examine the evolution of massive stars of 20 M_{⊙} and 25 M_{⊙} whose helium cores correspond to helium stars of 6 M_{⊙} and 8 M_{⊙}, respectively. While the 25 M_{⊙} stars evolve to the presupernova stages for all combinations of the reaction rates, the evolutionary paths of the 20 M_{⊙} stars proceed significantly differently for some combinations, which are unacceptable for progenitors of supernovae. Second, we perform calculations of supernova explosions within the limitation of spherical symmetry and compare the calculated abundance ratios with solar system abundances. We can deduce some constraints to the reaction rates. The results show that a conventional rate is adequate for a triple-α reaction rate and a rather higher value of the reaction rate within the upper limit for the experimental uncertainties is favorable for a ^{12}{C}(α ,γ )^{16}O rate.

  9. DNA methylation in 5-aza-2'-deoxycytidine-resistant variants of C3H 10T1/2 C18 cells.

    PubMed Central

    Flatau, E; Gonzales, F A; Michalowsky, L A; Jones, P A

    1984-01-01

    A cell line (T17) was derived from C3H 10T1/2 C18 cells after 17 treatments with increasing concentrations of 5-aza-2'-deoxycytidine. The T17 cell line was very resistant to the cytotoxic effects of 5-aza-2'-deoxycytidine, and the 50% lethal dose for 5-aza-2'-deoxycytidine was ca. 3 microM, which was 30-fold greater than that of the parental C3H 10T1/2 C18 cells. Increased drug resistance was not due to a failure of the T17 cell line to incorporate 5-aza-2'-deoxycytidine into DNA. The cells were also slightly cross-resistant to 5-azacytidine. The percentage of cytosines modified to 5-methylcytosine in T17 cells was 0.7%, a 78% decrease from the level of 3.22% in C3H 10T1/2 C18 cells. The DNA cytosine methylation levels in several clones isolated from the treated lines were on the order of 0.7%, and clones with methylation levels lower than 0.45% were not obtained even after further drug treatments. These highly decreased methylation levels appeared to be unstable, and DNA modification increased as the cells divided in the absence of further drug treatment. The results suggest that it may not be possible to derive mouse cells with vanishingly low levels of 5-methylcytosine and that considerable de novo methylation can occur in cultured lines. PMID:6209556

  10. Raman spectroscopy of isotopically pure ({sup 12}C, {sup 13}C) and isotopically mixed ({sup 12.5}C) diamond single crystals at ultrahigh pressures

    SciTech Connect

    Enkovich, P. V. Brazhkin, V. V.; Lyapin, S. G.; Novikov, A. P.; Kanda, H.; Stishov, S. M.

    2016-09-15

    The Raman scattering by isotopically pure {sup 12}C and {sup 13}C diamond single crystals and by isotopically mixed {sup 12.5}C diamond single crystals is studied at a high accuracy. The studies are performed over a wide pressure range up to 73 GPa using helium as a hydrostatic pressure-transferring medium. It is found that the quantum effects, which determine the difference between the ratio of the Raman scattering frequencies in the {sup 12}C and {sup 13}C diamonds and the classical ratio (1.0408), increase to 30 GPa and then decrease. Thus, inversion in the sign of the quantum contribution to the physical properties of diamond during compression is detected. Our data suggest that the maximum possible difference between the bulk moduli of the {sup 12}C and {sup 13}C diamonds is 0.15%. The investigation of the isotopically mixed {sup 12.5}C diamond shows that the effective mass, which determines the Raman frequency, decreases during compression from 12.38 au at normal pressure to 12.33 au at 73 GPa.

  11. Concise synthesis and anti-HIV activity of pyrimido[1,2-c][1,3]benzothiazin-6-imines and related tricyclic heterocycles.

    PubMed

    Mizuhara, Tsukasa; Oishi, Shinya; Ohno, Hiroaki; Shimura, Kazuya; Matsuoka, Masao; Fujii, Nobutaka

    2012-09-07

    3,4-Dihydro-2H,6H-pyrimido[1,2-c][1,3]benzothiazin-6-imine (PD 404182) is a virucidal heterocyclic compound active against various viruses, including HCV, HIV, and simian immunodeficiency virus. Using facile synthetic approaches that we developed for the synthesis of pyrimido[1,2-c][1,3]benzothiazin-6-imines and related tricyclic derivatives, the parallel structural optimizations of the central 1,3-thiazin-2-imine core, the benzene part, and the cyclic amidine part of PD 404182 were investigated. Replacement of the 6-6-6 pyrimido[1,2-c][1,3]benzothiazin-6-imine framework with 5-6-6 or 6-6-5 derivatives led to a significant loss of anti-HIV activity, and introduction of a hydrophobic group at the 9- or 10-positions improved the potency. In addition, we demonstrated that the PD 404182 derivative exerts anti-HIV effects at an early stage of viral infection.

  12. A practical synthesis of long-chain iso-fatty acids (iso-C12-C19) and related natural products.

    PubMed

    Richardson, Mark B; Williams, Spencer J

    2013-01-01

    A gram-scale synthesis of terminally-branched iso-fatty acids (iso-C12-C19) was developed commencing with methyl undec-10-enoate (methyl undecylenate) (for iso-C12-C14) or the C15 and C16 lactones pentadecanolide (for iso-C15-C17) and hexadecanolide (for iso-C18-C19). Central to the approaches outlined is the two-step construction of the terminal isopropyl group through addition of methylmagnesium bromide to the ester/lactones and selective reduction of the resulting tertiary alcohols. Thus, the C12, C17 and C18 iso-fatty acids were obtained in three steps from commercially-available starting materials, and the remaining C13-C16 and C19 iso-fatty acids were prepared by homologation or recursive dehomologations of these fatty acids or through intercepting appropriate intermediates. Highlighting the synthetic potential of the iso-fatty acids and various intermediates prepared herein, we describe the synthesis of the natural products (S)-2,15-dimethylpalmitic acid, (S)-2-hydroxy-15-methylpalmitic acid, and 2-oxo-14-methylpentadecane.

  13. Synthesis and anticonvulsant activity of 3a,4-dihydro-3H-indeno[1,2-c]pyrazole-2-carboxamide/carbothioamide analogues.

    PubMed

    Ahsan, Mohamed Jawed; Khalilullah, Habibullah; Stables, James P; Govindasamy, Jeyabalan

    2013-06-01

    A series of fourteen 3a,4-dihydro-3H-indeno[1,2-c]pyrazole-2-carboxamide/carbothioamide analogues were synthesized and evaluated for anticonvulsant activity according to the Antiepileptic Drug Development Programme (ADD) protocol. Some of the synthesized compounds showed significant activity in minimal clonic seizure model (6 Hz psychomotor seizure test). 3-(4-Fluorophenyl)-N-(4-bromophenyl)-6,7-dimethoxy-3a,4-dihydro-3H-indeno[1,2-c]pyrazole-2-carboxamide (4c) was found to be the most active compound of the series showing 75% (3/4, 0.25-2.0 h) and 50% (2/4, 4.0 h) protection against minimal clonic seizure at 100 mg/kg without any toxicity. 3-(Pyridin-4-yl)-N-(4-chlorophenyl)-6,7-dimethoxy-3a,4-dihydro-3H-indeno[1,2-c]pyrazole-2-carboxamide (4f) showed protection in maximal electroshock (MES) seizure and subcutaneous metrazol (scMET) seizure at 300 mg/kg.

  14. Feasibility of multichannel human cochlear nucleus stimulation.

    PubMed

    Luetje, C M; Whittaker, C K; Geier, L; Mediavilla, S J; Shallop, J K

    1992-01-01

    Bipolar electrical stimulation of the brainstem cochlear nucleus (CN) following acoustic tumor removal in an only-hearing ear can provide beneficial hearing. However, the benefits of multichannel stimulation have yet to be defined. Following removal of a second acoustic tumor in a patient with neurofibromatosis 2, a Nucleus mini-22 channel implant device was inserted with the electrode array tip from the foramen of Luschka cephalad along the root entry zone of the eighth nerve, secured by a single suture superficially in the brain stem. Initial stimulation on the sixth postoperative day indicated that electrodes 18 to 22 were capable of CN stimulation without seventh nerve stimulation. Presumed electrode migration precluded further CN stimulation 1 month later. This report illustrates the feasibility of brainstem CN stimulation with an existing multichannel system.

  15. Cell Nucleus-Targeting Zwitterionic Carbon Dots

    PubMed Central

    Jung, Yun Kyung; Shin, Eeseul; Kim, Byeong-Su

    2015-01-01

    An innovative nucleus-targeting zwitterionic carbon dot (CD) vehicle has been developed for anticancer drug delivery and optical monitoring. The zwitterionic functional groups of the CDs introduced by a simple one-step synthesis using β-alanine as a passivating and zwitterionic ligand allow cytoplasmic uptake and subsequent nuclear translocation of the CDs. Moreover, multicolor fluorescence improves the accuracy of the CDs as an optical code. The CD-based drug delivery system constructed by non-covalent grafting of doxorubicin, exhibits superior antitumor efficacy owing to enhanced nuclear delivery in vitro and tumor accumulation in vivo, resulting in highly effective tumor growth inhibition. Since the zwitterionic CDs are highly biocompatible and effectively translocated into the nucleus, it provides a compelling solution to a multifunctional nanoparticle for substantially enhanced nuclear uptake of drugs and optical monitoring of translocation. PMID:26689549

  16. Core-nucleus distortation in hypernuclei

    SciTech Connect

    Bodmer, A.R.; Usmani, Q.N.

    1995-08-01

    We are completing a study of the effects of the spherical distortion of the {open_quotes}core{close_quotes} nucleus by the {Lambda} in a hypernucleus. The response of the core was determined by an appropriately chosen energy-density functional which depends, in particular, on the nuclear compressibility. The forcing action of the A is determined by the nuclear density dependence of the {Lambda} binding in nuclear matter which is obtained from our work on the {Lambda} single-particle energies. Because of the strongly repulsive {Lambda}NN forces, this {Lambda} binding {open_quotes}saturates{close_quotes} at a density close to the central density of nuclei, and results in a reduced core-nucleus distortion much less than would otherwise be obtained. The effects of the core distortion then turn out to be very small even for quite light hypernuclei. This result justifies the assumption that spherical core nuclei are effectively undistorted in a hypernucleus.

  17. Gustatory Reward and the Nucleus Accumbens

    PubMed Central

    Norgren, R.; Hajnal, A.; Mungarndee, S.S.

    2011-01-01

    The concept of reward is central to psychology, but remains a cipher for neuroscience. Considerable evidence implicates dopamine in the process of reward and much of the data derives from the nucleus accumbens. Gustatory stimuli are widely used for animal studies of reward, but the connections between the taste and reward systems are unknown. In a series of experiments, our laboratory has addressed this issue using functional neurochemistry and neuroanatomy. First, using microdialysis probes, we demonstrated that sapid sucrose releases dopamine in the nucleus accumbens. The effect is dependent on oral stimulation and concentration. We subsequently determined that this response was independent of the thalamocortical gustatory system, but substantially blunted by damage to the parabrachial limbic taste projection. Further experiments using c-fos histochemistry confirmed that the limbic pathway was the prime carrier for the gustatory afferent activity that drives accumbens dopamine release. PMID:16822531

  18. Finite nucleus effects on relativistic energy corrections

    NASA Technical Reports Server (NTRS)

    Dyall, Kenneth G.; Faegri, Knut, Jr.

    1993-01-01

    The effect of using a finite nucleus model in quantum-chemical calculations is examined. Relativistic corrections from the first order Foldy-Wouthuysen terms are affected indirectly by the change in wavefunction, but also directly as a result of revised expressions for the Darwin and spin-orbit terms due to the change in nuclear potential. A calculation for the Rn atom indicates that the mass-velocity and Darwin corrections are much more sensitive to the finite nucleus than the non-relativistic total energy, but that the total contribution for these two terms is quite stable provided the revised form of the Darwin term is used. The spin-orbit interaction is not greatly affected by the choice of nuclear model.

  19. Cell Nucleus-Targeting Zwitterionic Carbon Dots.

    PubMed

    Jung, Yun Kyung; Shin, Eeseul; Kim, Byeong-Su

    2015-12-22

    An innovative nucleus-targeting zwitterionic carbon dot (CD) vehicle has been developed for anticancer drug delivery and optical monitoring. The zwitterionic functional groups of the CDs introduced by a simple one-step synthesis using β-alanine as a passivating and zwitterionic ligand allow cytoplasmic uptake and subsequent nuclear translocation of the CDs. Moreover, multicolor fluorescence improves the accuracy of the CDs as an optical code. The CD-based drug delivery system constructed by non-covalent grafting of doxorubicin, exhibits superior antitumor efficacy owing to enhanced nuclear delivery in vitro and tumor accumulation in vivo, resulting in highly effective tumor growth inhibition. Since the zwitterionic CDs are highly biocompatible and effectively translocated into the nucleus, it provides a compelling solution to a multifunctional nanoparticle for substantially enhanced nuclear uptake of drugs and optical monitoring of translocation.

  20. Physical Properties of Cometary Nucleus Candidates

    NASA Technical Reports Server (NTRS)

    Jewitt, David; Hillman, John (Technical Monitor)

    2003-01-01

    In this proposal we aim to study the physical properties of the Centaurs and the dead comets, these being the precursors to, and the remnants from, the active cometary nuclei. The nuclei themselves are very difficult to study, because of the contaminating effects of near-nucleus coma. Systematic investigation of the nuclei both before they enter the zone of strong sublimation and after they have depleted their near-surface volatiles should neatly bracket the properties of these objects, revealing evolutionary effects.