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Sample records for gamma xn reactions

  1. Cross Sections for (gamma)-ray Production in the 191Ir (n,xn(gamma)) Reactions

    SciTech Connect

    Fotiades, N; Nelson, R O; Devlin, M; Chadwick, M B; Talou, P; Becker, J A; Garrett, P E; Younes, W

    2005-01-11

    Discrete {gamma}-ray spectra have been measured for nuclei populated in {sup 191}Ir(n{sub 4}xn{gamma}) with x{<=}11, as a function of incident neutron energy using neutrons from the 'white' neutron source at the Los Alamos Neutron Science Center's WNR facility. The energy of the neutrons was determined using the time-of-flight technique. The data were taken using the GEANIE spectrometer. The cross sections for emission of 202 {gamma} rays of {sup 181-191}Ir were determined for neutron energies 0.2 MeV < E{sub n} < 300 MeV. Comparison with model calculations, using the GNASH reaction model, and with GEANIE results from the similar {sup 193}Ir(n{sub 4}xn{gamma}) reactions is made.

  2. Probing reaction dynamics with the {sup 196}Pt(n,xn{gamma}) reactions for x{le}15

    SciTech Connect

    Bernstein, L.A.; Becker, J.A.; Younes, W.; Archer, D.E.; Hauschild, K.; Nelson, R.O.; Wilburn, W.S. Drake, D.M.

    1998-06-01

    Discrete {gamma}-ray spectra have been measured as a function of incident neutron energy for nuclei produced in the {sup 196}Pt(n,xn{gamma}) reactions. Spectroscopy was done using the large-scale Compton suppressed Ge {gamma}-ray spectrometer GEANIE. The {open_quotes}white{close_quotes} source neutron beam was produced at the Los Alamos Neutron Science WNR facility. Reaction neutron energy was determined using the time-of-flight technique. Reaction-channel yields were inferred from the measured intensity sum of the 2{sub 1}{sup +}{r_arrow}0{sub 1}{sup +} and the 2{sub 2}{sup +}{r_arrow}0{sub 1}{sup +} transitions for the {sup 196}Pt(n,xn) reactions for x{le}15. Weisskopf-Ewing calculations (including precompound) done with the HMS-ALICE code correctly predict the bulk of the (n,xn) reaction products for low multiplicity. However, they do not accurately predict yield ratios of the different (n,xn) reactions for x{ge}9. In addition, there is no consistent experimental indication of charged-particle reaction channels (n,pxn) for incident neutron energies above 60 MeV where they are predicted to account for approximately 1/3 of the total reaction cross section. Several possible causes are discussed for these discrepancies. Finally, the region of E-J phase space populated in this reaction is probed for several of the strongest reaction channels through the observation of relative yields for different yrast and off-yrast states. {copyright} {ital 1998} {ital The American Physical Society}

  3. Lead 207, 208 (n, xn gamma) reactions for neutron energies up to 200 MeV

    SciTech Connect

    Pavlik, A.; Vonach, H.; Chadwick, M.B.; Haight, R.C.; Nelson, R.O.; Wender, S.A.; Young, P.G.

    1994-07-01

    High-resolution {gamma}-ray spectra from the interaction of neutrons in the energy range from 3 to 200 MeV with {sup 207,208}Pb were measured with the white neutron source at the WNR facility at Los Alamos National Laboratory. From these data, excitation functions for prominent {gamma} transitions in {sup 200,202,204,206,207,208}Pb were derived from threshold to 200 MeV incident neutron energy. These {gamma}-production cross sections represent formation cross sections for excited states of the residual nuclei. The results are compared with the predictions of nuclear reaction calculations based on the exciton model for precompound emission, the Hauser-Feshbach theory for compound nuclear decay, and coupled channels calculations to account for direct excitation of collective levels. Good agreement was obtained over the entire energy range covered in the experiment with reasonable model parameters. The results demonstrate that multiple preequilibrium emission has to be taken into account above about 40 MeV, and that the level density model of Ignatyuk should be used instead of the Gilbert-Cameron and back-shifted Fermi-gas models if excitation energies exceed about 30 MeV.

  4. Cross-Section Measurements for (n,xn) Reactions by In-Beam Gamma-Ray Spectroscopy

    SciTech Connect

    Pavlik, A.; Baumann, P.; Kerveno, M.; Rudolf, G.; Borcea, C.; Mihailescu, L.C.; Jericha, E.; Raskinyte, I.; Jokic, S.; Lukic, S.; Meulders, J.P.; Nolte, R.; Plompen, A.J.M.

    2005-05-24

    The nuclear reactions 207Pb(n,2n)206Pb and 232Th(n,5n)228Th were studied by measuring prompt gamma-ray emission spectra from the interaction of neutrons with an enriched 207Pb sample and a natTh sample. For 207Pb the measurements were performed at the white neutron beam of the GELINA neutron source at IRMM Geel in the neutron energy range up to 20 MeV. The Th measurements were done at the quasi-monoenergetic 7Li(p,n)7Be neutron source at the Universite Catholique de Louvain for five peak neutron energies in the range 29 MeV to 42 MeV. The measurements were complemented by model calculations using the code system EMPIRE-II.

  5. Neutron-multiplicity distributions for (. cap alpha. ,xn. gamma. ) reactions with E/sub. cap alpha. / = 50--120 MeV and the pre-equilibrium neutron deexcitation processes

    SciTech Connect

    Maeda, K.; Shibata, T.; Ejiri, H.; Sakai, H.

    1983-08-01

    Pre-equilibrium and equilibrium deexcitation processes for (..cap alpha..,xn ..gamma..) reactions induced by 50--120 MeV ..cap alpha.. particles were studied. Reaction channels were identified by measuring rotational ..gamma.. rays characteristic of the reaction residues. The branching of the reaction channels gave neutron multiplicity distributions. Features characteristic of the pre-equilibrium process were seen in the reaction channels with small neutron multiplicity x. An exciton model calculation code was developed so as to incorporate both multiparticle emission at the fast pre-equilibrium stage and multiparticle p evaporation at the slow equilibrium stage. The calculation reproduced the neutron multiplicity distributions in the whole range of E/sub ..cap alpha../ = 50--120 MeV. The pre-equilibrium fractions and the entry lines from the pre-equilibrium stage to the equilibrium one were deduced. The pre-equilibrium fractions were found to be approximately 40--60 %, being rather independent of the individual reaction channel. The entry lines slowly increase from 25 to 35 MeV with increasing projectile energy.

  6. GRAPhEME: a setup to measure (n, xn γ) reaction cross sections

    SciTech Connect

    Henning, Greg; Bacquias, A.; Capdevielle, O.; Dessagne, P.; Kerveno, M.; Rudolf, G.; Borcea, C.; Negret, A.; Olacel, A.; Drohe, J.C.; Plompen, A.J.M.; Nyman, M.

    2015-07-01

    Most of nuclear reactor developments are using evaluated data base for numerical simulations. However, the considered databases present still large uncertainties and disagreements. To improve their level of precision, new measurements are needed, in particular for (n, xn) reactions, which are of great importance as they modify the neutron spectrum, the neutron population, and produce radioactive species. The IPHC group started an experimental program to measure (n, xn gamma) reaction cross sections using prompt gamma spectroscopy and neutron energy determination by time of flight. Measurements of (n, xn gamma) cross section have been performed for {sup 235,238}U, {sup 232}Th, {sup nat,182,183,184,186}W, {sup nat}Zr. The experimental setup is installed at the neutron beam at GELINA (Geel, Belgium). The setup has recently been upgraded with the addition of a highly segmented 36 pixels planar HPGe detector. Significant efforts have been made to reduce radiation background and electromagnetic perturbations. The setup is equipped with a high rate digital acquisition system. The analysis of the segmented detector data requires a specific procedure to account for cross signals between pixels. An overall attention is paid to the precision of the measurement. The setup characteristic and the analysis procedure will be presented along with the acquisition and analysis challenges. Examples of results and their impact on models will be discussed. (authors)

  7. Determination of flux-weighted average cross-sections of natPb(γ,xn), 208Pb(γ,xn), and 209Bi(γ,xn) reactions using bremsstrahlung end-point energies of 50-70 MeV

    NASA Astrophysics Data System (ADS)

    Naik, Haladhara; Kim, Guinyun; Kim, Kwangsoo; Zaman, Muhammad; Shahid, Muhammad; Kang, Yeong-Rok; Woo Lee, Man; Shin, Sung-Gyun; Cho, Moo-Hyun

    2016-11-01

    The flux-weighted average cross-sections of the natPb(γ, xn)198-204Pb reaction for the bremsstrahlung end-point energies of 50-70MeV were determined by activation and off-line γ -ray spectrometric technique, using the 100 MeV electron linac at the Pohang Accelerator Laboratory (PAL), Korea. The relative cross-sections of the 208Pb(γ, xn)202-204Pb and 209Bi(γ, xn)203-206Bi reactions from our earlier work were updated to absolute values and compared with the present data. The photo-neutron cross-sections of natPb, 208Pb, and 209Bi were also calculated, as a function of the photon energy using the TALYS 1.6 code. The flux-weighted average cross-sections were obtained from the theoretical values of the TALYS 1.6 code, based on mono-energetic photons, and compared with the present experimental data. The values were found to be in good agreement with the present data for the 209Bi(γ, xn)203-206Bi, 208Pb(γ, xn)202-204Pb, and natPb(γ, xn)198-202Pb reactions. However, the present data for the natPb(γ, xn)203, 204Pb reactions were higher than the flux-weighted values obtained using the TALYS 1.6 code.

  8. Measurement of (n, xnγ) reaction cross sections in W isotopes

    NASA Astrophysics Data System (ADS)

    Henning, Greg; Bacquias, Antoine; Borcea, Catalin; Capote, Roberto; Dessagne, Philippe; Drohé, Jean-Claude; Kawano, Toshihiko; Kerveno, Maëlle; Negret, Alexandru; Nyman, Markus; Olacel, Adina; Plompen, Arjan; Romain, Pascal; Scholtes, Pol; Rudolf, Gérard

    2017-09-01

    Evaluated nuclear data bases currently used for numerical simulation for the development of nuclear reactors still present large uncertainties. Their improvement is necessary, in particular through better reaction models and nuclear data. Among the reactions of interest, (n, xn) reactions are of great importance for the operation of a reactor as they modify the neutron spectrum, the neutron population, and produce radioactive species. Experimental data on (n, xnγ) reaction provide strong constraints on nuclear reaction mechanism theories. Tungsten isotopes - which are deformed like actinides but do not fission - are of interest to test the models. 182,184,186W(n, xnγ) cross sections are measured; results are compared with model calculations by TALYS, EMPIRE and CoH codes.

  9. New data on ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) partial photoneutron reactions

    SciTech Connect

    Varlamov, V. V. Ishkhanov, B. S.; Orlin, V. N.; Peskov, N. N.; Stepanov, M. E.

    2013-11-15

    Systematic discrepancies between the results of various experiments devoted to determining cross sections for total and partial photoneutron reactions are analyzed by using objective criteria of reliability of data in terms of the transitional photoneutron-multiplicity function F{sub i} = {sigma}({gamma}, in)/{sigma}({gamma}, xn), whose values for i = 1, 2, 3, ... cannot exceed by definition 1.00, 0.50, 0.33, ..., respectively. It was found that the majority of experimental data on the cross sections obtained for ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) reactions with the aid of methods of photoneutron multiplicity sorting do not meet objective criteria (in particular, F{sub 2} > 0.50 for a vast body of data). New data on the cross sections for partial reactions on {sup 181}Ta and {sup 208}Pb nuclei were obtained within a new experimental-theoretical method that was proposed for the evaluation of cross sections for partial reactions and in which the experimental neutron yield cross section {sigma}{sup expt}({gamma}, xn) = {sigma}({gamma}, n) + 2{sigma}({gamma}, 2n) + 3{sigma}({gamma}, 3n) + ..., which is free from problems associated with determining neutron multiplicities, is used simultaneously with the functions F{sub i}{sup theor} calculated within a combined model of photonuclear reactions.

  10. Lens-mode operation of a superconducting electron spectrometer in (HI, xn) reactions

    NASA Astrophysics Data System (ADS)

    Kibédi, T.; Dracoulis, G. D.; Byrne, A. P.

    1990-09-01

    An electron spectrometer, consisting of a superconducting solenoidal magnet transporter and a Si(Li) detector, is described. The spectrometer has been used in lens mode, with an envelope baffle system and with the field swept under computer control. The efficiency obtained for the optimum energy at a given field is ˜ 5.9(5)%. Model calculations have been carried out to describe the transmission and efficiency of the swept lens, as well as the effect of the electron angular distribution on conversion-coefficient determinations. The performance of the spectrometer has been tested with radioactive sources and several in-beam experiments using (HI, xn) reactions.

  11. NIF Gamma Reaction History

    NASA Astrophysics Data System (ADS)

    Herrmann, H. W.; Kim, Y.; Young, C. S.; Mack, J. M.; McEvoy, A. M.; Hoffman, N. M.; Wilson, D. C.; Langenbrunner, J. R.; Evans, S.; Batha, S. H.; Stoeffl, W.; Lee, A.; Horsfield, C. J.; Rubery, M.; Miller, E. K.; Malone, R. M.; Kaufman, M. I.

    2010-11-01

    The primary objective of the NIF Gamma Reaction History (GRH) diagnostics is to provide bang time and burn width information based upon measurement of fusion gamma-rays. This is accomplished with energy-thresholded Gas Cherenkov detectors that convert MeV gamma-rays into UV/visible photons for high-bandwidth optical detection. In addition, the GRH detectors can perform γ-ray spectroscopy to explore other nuclear processes from which additional significant implosion parameters may be inferred (e.g., plastic ablator areal density). Implementation is occurring in 2 phases: 1) four PMT-based channels mounted to the outside of the NIF target chamber at ˜6 m from TCC (GRH-6m) for the 3e13-3e16 DT neutron yield range expected during the early ignition-tuning campaigns; and 2) several channels located just inside the target bay shield wall at ˜15 m from TCC (GRH-15m) with optical paths leading through the wall into well-shielded streak cameras and PMTs for the 1e16-1e20 yield range expected during the DT ignition campaign. This suite of diagnostics will allow exploration of interesting γ-ray physics well beyond the ignition campaign. Recent data from OMEGA and NIF will be shown.

  12. Comparison of reactions for the production of 258,257Db: 208Pb(51V,xn) and 209Bi(50Ti,xn)

    SciTech Connect

    Gates, Jacklyn M.; Nelson, Sarah L.; Gregorich, Kenneth E.; Dragojevic, Irena; Dullmann, Christoph E.; Ellison, Paul A.; Folden III, Charles M.; Garcia, Mitch A.; Stavsetra, Liv; Sudowe, Ralf; Hoffman, Darleane C.; Nitsche, Heino

    2008-09-29

    Excitation functions for the 1n and 2n exit channels of the 208Pb(51V,xn)259-xDb reaction were measured. A maximum cross section of the 1n exit channel of 2070+1100/-760 pb was measured at an excitation energy of 16.0 +- 1.8 MeV. For the 2n exit channel, a maximum cross section of 1660+450/-370 pb was measured at 22.0 +- 1.8 MeV excitation energy. The 1n excitation function for the 209Bi(50Ti,n)258Db reaction was remeasured, resulting in a cross section of 5480+1750/-1370 pb at an excitation energy of 16.0 +- 1.6 MeV, in agreement with previous values [F. P. Hebberger, et al., Eur. Phys. J. A 12, 57 (2001)]. Differences in cross section maxima are discussed in terms of the fusion probability below the barrier.

  13. (n,xnγ) cross sections on actinides versus reaction code calculations

    NASA Astrophysics Data System (ADS)

    Kerveno, Maëlle; Bacquias, Antoine; Belloni, Francesca; Borcea, Catalin; Capote, Roberto; Dessagne, Philippe; Dupuis, Marc; Henning, Greg; Hilaire, Stéphane; Kawano, Toshihiko; Nankov, Nicolas; Negret, Alexandru; Nyman, Markus; Party, Eliot; Plompen, Arjan; Romain, Pascal; Rouki, Charoula; Rudolf, Gérard; Stanoiu, Mihai

    2017-09-01

    The experimental setup GRAPhEME (GeRmanium array for Actinides PrEcise MEasurements) has been used at GELINA (EC-JRC, Geel, Belgium) to perform (n,xn γ) cross sections measurements. GRAPhEME has been especially designed to take into account the specific difficulties generated by the use of actinides samples. This work takes place in the context of new nuclear data measurements for nuclear reactor applications. Considering the very tight accuracy requested for new experimental data, special care has been paid to quantify as accurately as possible all the uncertainties from the instruments and the analysis procedure. From the precise (n,xn γ) cross sections produced with GRAPhEME, the use of model calculations is required to obtain (n,xn) cross sections. Beyond the measurements, extensive work on theoretical models is necessary to achieve a better evaluation of the (n,xn) processes. In this paper, we will discuss the final step of the 238U data analysis and present some recent results obtained on 232Th compared to TALYS modellings. A new measurement campaign on 233U has started recently, a first assessment of the recorded data will be presented.

  14. Inclusive measurement of (p,. pi. /sup -/xn) double charge exchange reactions on bismuth from threshold to 800 MeV

    SciTech Connect

    Dombsky, M.; D'Auria, J.M.; Kelson, I.; Yavin, A.I.; Ward, T.E.; Clark, J.L.; Ruth, T.; Sheffer, G.

    1985-07-01

    The energy dependence of the total angle-integrated cross section for the production of astatine isotopes from (p,..pi../sup -/xn) double charge exchange reactions on bismuth (/sup 209/Bi) was measured from 120 to 800 MeV using activation and radiochemical techniques. Chemical yields were estimated by direct radioassaying of /sup 211/At activity in thin (approx.1 mg/cm/sup 2/), irradiated bismuth targets. Calculations of the contributions of secondary (two-step) reactions to these measured astatine yields were performed, based partially upon the observed /sup 211/At activity although even at the highest energies, the contribution to products lighter than /sup 207/At was negligible. These data for products with as many as seven neutrons removed from the doubly coherent product (/sup 210/At) display nearly Gaussian shapes for the mass distributions of the astatine residues, with the maximum occurring for about /sup 204/At. The most probable momentum transfer deduced from these distributions for the initial ..pi../sup -/ production step was 335 MeV/c. The observed excitation functions display a behavior similar to that observed for the yield of /sup 210/Po from a (p,..pi../sup 0/) reaction on /sup 209/Bi, but radically different from that observed for inclusive ..pi../sup -/ reactions on a heavy nucleus. These data are discussed in terms of recent theoretical approaches to negative pion production from bismuth. In addition, a simple, schematic model is developed to treat the rapidly decreasing percentage of the total inclusive ..pi../sup -/ emission which is observed for this double charge exchange reaction. This model reflects the opacity of a nucleus to a source of internal energetic protons.

  15. The equilibrium and preequilibrium neutron-emission spectra of some structural fusion materials for (n, xn) reactions up to 16 MeV energy

    SciTech Connect

    Kaplan, A.; Tel, E.; Aydin, A.

    2009-06-15

    In this study, neutron-emission spectra produced by (n, xn) reactions for some structural fusion materials as {sup 27}Al, {sup 51}V, {sup 52}Cr, {sup 55}Mn, and {sup 56}Fe have been investigated by a neutron beam up to 16 MeV. Multiple preequilibrium mean-free-path constant from internal transition and the preequilibrium and equilibrium level-density parameters have been investigated for some (n, xn) neutron-emission spectra calculated in this study. Preequilibrium neutron-emission spectra were calculated by using new-evaluated hybrid model and geometry-dependent hybrid model, full-exciton model, and cascade-exciton model. The reaction equilibrium component was calculated by Weisskopf-Ewing model. The obtained results have been discussed and compared with the available experimental data and found agreement with each other.

  16. Measurements and usage of cross sections of various (n,xn) threshold reactions

    NASA Astrophysics Data System (ADS)

    Chudoba, P.; Vrzalová, J.; Svoboda, O.; Krása, A.; Kugler, A.; Majerle, M.; Suchopár, M.; Wagner, V.

    2017-03-01

    Current trend in nuclear reactor physics is a transition from technologies using thermal neutrons to technologies utilizing fast neutrons. Unfortunately focus was put mainly on the thermal neutrons for a long time and lead to very good knowledge about this low energy region, but very scarce coverage of the high energy region. This means that there is a gap in the knowledge of excitation functions for higher energies. This gap spreads from 20 MeV up to 1 GeV and higher. This is exactly the energy region needed for description of advanced nuclear systems such as accelerator driven systems (ADS). Our group from Nuclear Physics Institute (NPI) of the CAS is a member of an international collaboration Energy & Transmutation of Radioactive Waste (E&T RAW). This collaboration focuses on ADS for many years. In order to measure neutron field within ADS models it is necessary to know excitation functions of reactions used to monitor the neutron field. In many cases there are almost no experimental data for suitable reactions. Worse and quite common case is that there are no data at all. Therefore we are also focusing on measurements of these data in order to fill the databases as well as to allow further improvements of codes for nuclear data calculations.

  17. Comparison of reactions for the production of {sup 258,257}Db: {sup 208}Pb({sup 51}V,xn) and {sup 209}Bi({sup 50}Ti,xn)

    SciTech Connect

    Gates, J. M.; Nelson, S. L.; Dragojevic, I.; Duellmann, Ch. E.; Ellison, P. A.; Folden III, C. M.; Garcia, M. A.; Hoffman, D. C.; Nitsche, H.; Gregorich, K. E.; Stavsetra, L.; Sudowe, R.

    2008-09-15

    Excitation functions for the 1n and 2n exit channels of the {sup 208}Pb({sup 51}V,xn){sup 259-x}Db reaction were measured. A maximum cross section of the 1n exit channel of 2070{sub -760}{sup +1100} pb was measured at an excitation energy of 16.0 {+-} 1.8 MeV. For the 2n exit channel, a maximum cross section of 1660{sub -370}{sup +450} pb was measured at 22.0 {+-} 1.8 MeV excitation energy. The 1n excitation function for the {sup 209}Bi({sup 50}Ti,n){sup 258}Db reaction was remeasured, resulting in a cross section of 5480{sub -1370}{sup +1730} pb at an excitation energy of 16.0 {+-} 1.6 MeV, in agreement with previous values [F. P. Hessberger et al., Eur. Phys. J. A 12, 57 (2001)]. Differences in cross section maxima are discussed in terms of the fusion probability below the barrier.

  18. Neutron Emission Spectra of 104,105,106,108,110Pd Isotopes for (p,xn) Reactions at 21.6 MeV Proton Incident Energy

    NASA Astrophysics Data System (ADS)

    Büyükuslu, H.; Kaplan, A.; Tel, E.; Aydin, A.; Yıldırım, G.

    2010-02-01

    Palladium, which is a rare and lustrous silvery-white color from precious metals, plays important role in fusion-fission reactions and different fields of nuclear technology. In addition, it is used for not only cold fusion experiments but also separation of hydrogen isotopes researches for fusion reactors. In this study, neutron-emission spectra produced by (p,xn) reactions for structural fusion material 104,105,106,108,110Pd isotopes have been investigated by a proton beam at 21.6 MeV. Moreover, multiple pre-equilibrium mean free paths constant from internal transition, and the pre-equilibrium and equilibrium level density parameters have been analyzed for some (p,xn) neutron-emission spectra calculated. New evaluated hybrid model and geometry dependent hybrid model, full exciton model and cascade exciton model were used to calculate the pre-equilibrium neutron-emission spectra. For the reaction equilibrium component, Weisskopf-Ewing model calculations were preferred. The obtained results have been discussed and compared with the available experimental data and found agreement with each other.

  19. Measurement of the activation cross section for the (p,xn) reactions in niobium with potential applications as monitor reactions

    NASA Astrophysics Data System (ADS)

    Avila-Rodriguez, M. A.; Wilson, J. S.; Schueller, M. J.; McQuarrie, S. A.

    2008-08-01

    Excitation functions of the 93Nb(p,n) 93mMo, 93Nb(p,pn) 92mNb and 93Nb(p,αn) 89Zr nuclear reactions were measured up to 17.4 MeV by the conventional activation method using the stacked-foil technique. Stacks were irradiated at different incident energies on the TR19/9 cyclotron at the Edmonton PET Centre. The potential of the measured excitation functions for use as monitor reactions was evaluated and tested by measuring activity ratios at a different facility. Single Nb foils were irradiated at incident energies in the range from 12 to 19 MeV on the TR19/9 cyclotron at Brookhaven National Laboratory. Results are compared with the published data and with theoretical values as determined by the nuclear reaction model code EMPIRE.

  20. {sup 248}Cm({sup 22}Ne,xn){sup 270-x}Sg reaction and the decay properties of {sup 265}Sg reexamined

    SciTech Connect

    Duellmann, Ch. E.; Tuerler, A.

    2008-06-15

    Recent studies of the hot fusion reaction {sup 248}Cm({sup 26}Mg,xn){sup 274-x}Hs have provided new nuclear decay data on {sup 265,266}Sg and confirmed the existence of an isomeric state in {sup 261}Rf. The results reported in [J. Dvorak et al., Phys. Rev. Lett. 100, 132503 (2008)] suggest that all decay chains observed in previous studies of the reaction {sup 248}Cm({sup 22}Ne,xn){sup 270-x}Sg, which were originally attributed to {sup 266}Sg, originated from {sup 265}Sg. Here, the decay properties of {sup 265}Sg are reevaluated. Indications for the existence of an isomeric state in {sup 265}Sg are found. The half-lives and main {alpha} particle energies of the two {sup 265}Sg states are 8.9 s/8.85 MeV and 16.2 s/8.70 MeV, respectively. Direct production of this isotope as an evaporation residue of a nuclear fusion reaction populates both states with similar intensity while {alpha} decay of {sup 269}Hs into {sup 265}Sg preferentially populates the longer-lived state, which in turn decays almost exclusively into the short-lived state in {sup 261}Rf. The cross section of the reaction {sup 248}Cm({sup 22}Ne,5n){sup 265}Sg is reanalyzed and found to be of the order of a few hundred pb, assuming that {alpha} decay is the only decay mode of {sup 265}Sg. A decay scheme that is consistent with the published data on {sup 265}Sg and {sup 261}Rf is proposed, which can serve as a working hypothesis in the design of new experiments dedicated to study the production and decay of these two isotopes.

  1. Gamma Reaction History for the NIF

    SciTech Connect

    Herrmann, H W; Evans, S C; Kim, Y; Mack, J M; Young, C S; Cox, B C; Frogget, B C; Kaufman, M I; Malone, R M; Tunnell, T W; Stoeffl, W; Horsfield, C J

    2009-06-05

    Bang time and reaction history measurements are fundamental components of diagnosing ICF implosions and will be essential contributors to diagnosing attempts at ignition on the National Ignition Facility (NIF). Fusion gammas provide a direct measure of fusion interaction rate without being compromised by Doppler spreading. Gamma-based gas Cherenkov detectors that convert fusion gamma rays to optical Cherenkov photons for collection by fast recording systems have been developed and fielded at Omega. These systems have established their usefulness in illuminating ICF physics in several experimental campaigns. Bang time precision better than 25 ps has been demonstrated, well below the 50 ps accuracy requirement defined by the NIF System Design Requirements. A staged approach of implementing Gamma Reaction History (GRH) diagnostics on the NIF has been initiated. In the early stage, multiple detectors located close to target chamber center (at 2 and 6 m) and coupled to photomultiplier tubes are geared toward the loweryield THD campaign. In the later stage, streak camera–coupled instruments will be used for improved temporal resolution at the higher yields expected from the DT ignition campaign. Multiple detectors will allow for increased dynamic range and gamma energy spectral information.

  2. Measurement of flux-weighted average cross-sections and isomeric yield ratios for 103Rh(γ,xn) reactions in the bremsstrahlung end-point energies of 55 and 60 MeV

    NASA Astrophysics Data System (ADS)

    Shakilur Rahman, Md.; Kim, Kwangsoo; Kim, Guinyun; Naik, Haladhara; Nadeem, Muhammad; Thi Hien, Nguyen; Shahid, Muhammad; Yang, Sung-Chul; Cho, Young-Sik; Lee, Young-Ouk; Shin, Sung-Gyun; Cho, Moo-Hyun; Woo Lee, Man; Kang, Yeong-Rok; Yang, Gwang-Mo; Ro, Tae-Ik

    2016-07-01

    We measured the flux-weighted average cross-sections and the isomeric yield ratios of 99m, g, 100m, g, 101m, g, 102m, gRh in the 103Rh( γ, xn) reactions with the bremsstrahlung end-point energies of 55 and 60MeV by the activation and the off-line γ-ray spectrometric technique, using the 100MeV electron linac at the Pohang Accelerator Laboratory (PAL), Korea. The flux-weighted average cross-sections were calculated by using the computer code TALYS 1.6 based on mono-energetic photons, and compared with the present experimental data. The flux-weighted average cross-sections of 103Rh( γ, xn) reactions in intermediate bremsstrahlung energies are the first time measurement and are found to increase from their threshold value to a particular value, where the other reaction channels open up. Thereafter, it decreases with bremsstrahlung energy due to its partition in different reaction channels. The isomeric yield ratios (IR) of 99m, g, 100m, g, 101m, g, 102m, gRh in the 103Rh( γ, xn) reactions from the present work were compared with the literature data in the 103Rh(d, x), 102-99Ru(p, x) , 103Rh( α, αn) , 103Rh( α, 2p3n) , 102Ru(3He, x), and 103Rh( γ, xn) reactions. It was found that the IR values of 102, 101, 100, 99Rh in all these reactions increase with the projectile energy, which indicates the role of excitation energy. At the same excitation energy, the IR values of 102, 101, 100, 99Rh are higher in the charged particle-induced reactions than in the photon-induced reaction, which indicates the role of input angular momentum.

  3. From γ emissions to (n,xn) cross sections of interest: The role of GAINS and GRAPhEME in nuclear reaction modeling

    NASA Astrophysics Data System (ADS)

    Kerveno, M.; Bacquias, A.; Borcea, C.; Dessagne, Ph.; Henning, G.; Mihailescu, L. C.; Negret, A.; Nyman, M.; Olacel, A.; Plompen, A. J. M.; Rouki, C.; Rudolf, G.; Thiry, J. C.

    2015-12-01

    During the last 10 years, in the general context of nuclear energy applications and future reactors development, our collaboration has performed measurements of (n, x nγ cross sections to study (n, xn) reactions. Large sets of new and accurate experimental data have been produced on a variety of nuclei from 7Li to 238U. Comparisons with nuclear reaction code calculations have shown that the predictions of these exclusive cross sections are a real challenge for the theoretical codes. Indeed many processes are involved as evaporation, fission if fissionable nucleus, direct and pre-equilibrium reactions, etc. All these processes should be simultaneously well described by the models that using nuclear structure description for optical potential, level densities, decay scheme, etc. In this article, we review what we have learned since the last P(ND)2 workshop held in 2005 (A.J.M. Plompen, Proceedings of the Perspectives on Nuclear data for the Next Decade Workshop, Bruyères-le-Châtel, France, 26-28 September 2005, NEA Report N° 6121, p. 151) and highlight how we can further progress in this field in order to provide new, complete, accurate and relevant experimental data.

  4. Depth profile of production yields of natPb(p, xn) 206,205,204,203,202,201Bi nuclear reactions

    NASA Astrophysics Data System (ADS)

    Mokhtari Oranj, Leila; Jung, Nam-Suk; Kim, Dong-Hyun; Lee, Arim; Bae, Oryun; Lee, Hee-Seock

    2016-11-01

    Experimental and simulation studies on the depth profiles of production yields of natPb(p, xn) 206,205,204,203,202,201Bi nuclear reactions were carried out. Irradiation experiments were performed at the high-intensity proton linac facility (KOMAC) in Korea. The targets, irradiated by 100-MeV protons, were arranged in a stack consisting of natural Pb, Al, Au foils and Pb plates. The proton beam intensity was determined by activation analysis method using 27Al(p, 3p1n)24Na, 197Au(p, p1n)196Au, and 197Au(p, p3n)194Au monitor reactions and also by Gafchromic film dosimetry method. The yields of produced radio-nuclei in the natPb activation foils and monitor foils were measured by HPGe spectroscopy system. Monte Carlo simulations were performed by FLUKA, PHITS/DCHAIN-SP, and MCNPX/FISPACT codes and the calculated data were compared with the experimental results. A satisfactory agreement was observed between the present experimental data and the simulations.

  5. Gamma Reaction History Backgrounds at the NIF

    NASA Astrophysics Data System (ADS)

    Church, J. A.; Stoeffl, W. S.; Watts, P. W.; Carpenter, A. C.; Liebman, J.; Herrmann, H. W.; Kim, Y. H.; Grafil, E.

    2011-10-01

    The Gamma Reaction History (GRH) diagnostic at NIF detects gamma-rays, emitted directly from DT fusion reactions (DT γ) , through the use of four Gas Cherenkov detectors with adjustable gamma-ray energy thresholds. It is primarily used to determine bang time, burn width and total DT yield of the implosion. Background interference to the signal is insignificant when capsules are driven directly by the lasers, but can be significant during indirect-drive using a hohlraum, forming an approximately 20 ns plateau under the narrow ~200 ps FWHM fusion signal. This background is independent of fusion yield and most likely the result of laser-plasma interaction (LPI) induced hot electron bremsstrahlung radiation. These hard x-rays stream out target chamber ports and take multiple scatter paths to reach the GRH photomultiplier tubes (PMT), where they then bypass the Cherenkov conversion process and generate signal by direct interaction with the PMT microchannel plates. An examination of this background contribution to the GRH signal and possible mitigation strategies will be presented. This work performed under the auspices of the U.S. DOE by LLNL under Contract DE-AC52-07NA27344, LLNL-ABS-490832.

  6. Preparation and evaluation of SnO2-based 68Ge/68Ga generator made from 68Ge produced through (nat)Zn(α,xn) reaction.

    PubMed

    Das, Sujata Saha; Chattopadhyay, Sankha; Alam, Md Nayer; Madhusmita; Barua, Luna; Das, Malay Kanti

    2013-09-01

    (68)Ge was produced by (nat)Zn(α,xn)(68)Ge reaction and its production yield was 31.82 kBq/μAh (0.86 μCi/μAh) at the end of irradiation (EOI). A simple chromatographic method using a SnO2 column was employed to separate (68)Ge from the target material and the co-produced non-isotopic radioisotope impurities. (68)Ge retained in the column served as the (68)Ge/(68)Ga generator. Elution efficiency of the column was about 60%. First 2 ml of the eluate contained more than 95% of the elutable activity. Post-elution purification cum concentration was done with a small cation exchange resin column. The presence of the inactive tin ions in the (68)Ga eluate was determined by the ICP-OES technique and was found to be about 0.03 ppm. Radiochemical purity of the final (68)Ga preparation was more than 99.99% and it was found to be suitable for making complex with ethylenediamine-N,N,N',N'-tetrakis(methylene phosphonic acid) (EDTMP). Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Nonelastic nuclear reactions and accompanying gamma radiation

    NASA Technical Reports Server (NTRS)

    Snow, R.; Rosner, H. R.; George, M. C.; Hayes, J. D.

    1971-01-01

    Several aspects of nonelastic nuclear reactions which proceed through the formation of a compound nucleus are dealt with. The full statistical model and the partial statistical model are described and computer programs based on these models are presented along with operating instructions and input and output for sample problems. A theoretical development of the expression for the reaction cross section for the hybrid case which involves a combination of the continuum aspects of the full statistical model with the discrete level aspects of the partial statistical model is presented. Cross sections for level excitation and gamma production by neutron inelastic scattering from the nuclei Al-27, Fe-56, Si-28, and Pb-208 are calculated and compared with avaliable experimental data.

  8. ICF gamma-ray reaction history diagnostics

    NASA Astrophysics Data System (ADS)

    Herrmann, H. W.; Young, C. S.; Mack, J. M.; Kim, Y. H.; McEvoy, A.; Evans, S.; Sedillo, T.; Batha, S.; Schmitt, M.; Wilson, D. C.; Langenbrunner, J. R.; Malone, R.; Kaufman, M. I.; Cox, B. C.; Frogget, B.; Miller, E. K.; Ali, Z. A.; Tunnell, T. W.; Stoeffl, W.; Horsfield, C. J.; Rubery, M.

    2010-08-01

    Reaction history measurements, such as nuclear bang time and burn width, are fundamental components of diagnosing ICF implosions and will be employed to help steer the National Ignition Facility (NIF) towards ignition. Fusion gammas provide a direct measure of nuclear interaction rate (unlike x-rays) without being compromised by Doppler spreading (unlike neutrons). Gas Cherenkov Detectors that convert fusion gamma rays to UV/visible Cherenkov photons for collection by fast optical recording systems have established their usefulness in illuminating ICF physics in several experimental campaigns at OMEGA. In particular, bang time precision better than 25 ps has been demonstrated, well below the 50 ps accuracy requirement defined by the NIF. NIF Gamma Reaction History (GRH) diagnostics are being developed based on optimization of sensitivity, bandwidth, dynamic range, cost, and NIF-specific logistics, requirements and extreme radiation environment. Implementation will occur in two phases. The first phase consists of four channels mounted to the outside of the target chamber at ~6 m from target chamber center (GRH-6m) coupled to ultra-fast photo-multiplier tubes (PMT). This system is intended to operate in the 1013-1017 neutron yield range expected during the early THD campaign. It will have high enough bandwidth to provide accurate bang times and burn widths for the expected THD reaction histories (> 80 ps fwhm). Successful operation of the first GRH-6m channel has been demonstrated at OMEGA, allowing a verification of instrument sensitivity, timing and EMI/background suppression. The second phase will consist of several channels located just inside the target bay shield wall at 15 m from target chamber center (GRH-15m) with optical paths leading through the cement shield wall to well-shielded streak cameras and PMTs. This system is intended to operate in the 1016-1020 yield range expected during the DT ignition campaign, providing higher temporal resolution for the

  9. Using (d,p{gamma}) as a surrogate reaction for (n,{gamma})

    SciTech Connect

    Hatarik, R.; Cizewski, J. A.; Hatarik, A. M.; O'Malley, P. D.; Bernstein, L. A.; Burke, J. T.; Bleuel, D. L.; Lesher, S. R.; Gibelin, J.; Phair, L.; Swan, T.

    2009-01-28

    To benchmark the validity of using the (d,p{gamma}) reaction as a surrogate for (n,{gamma}), the {sup 171,173}Yb(d,p{gamma}) reactions were measured with the goal to reproduce the known neutron capture cross section ratio of these nuclei. Preliminary surrogate results reproduced the measured values within 15%.

  10. Measurement of flux-weight average cross-sections of natZn(γ,xn) reactions in the bremsstrahlung end-point energies of 50, 55, 60, and 65 MeV

    NASA Astrophysics Data System (ADS)

    Zaman, Muhammad; Kim, Guinyun; Naik, Haladhara; Kim, Kwangsoo; Cho, Young-Sik; Lee, Young-Ok; Shin, Sung-Gyun; Cho, Moo-Hyun; Kang, Yeong-Rok; Lee, Man-Woo

    2017-04-01

    The flux-weighted average cross-sections of (γ , xn) reactions on natZn induced by the bremsstrahlung end-point energies of 50, 55, 60, and 65 MeV have been determined by activation and off-line γ-ray spectrometric technique, using the 100 MeV electron linac at the Pohang Accelerator Laboratory (PAL), Pohang, Korea. The theoretical photon-induced reaction cross-sections of natZn as a function of photon energy were taken from TENDL-2014 nuclear data library based on TALYS 1.6 program. The flux-weighted average cross-sections were obtained from the literature data and the theoretical values of TENDL-2014 based on mono-energetic photon. The flux-weighted reaction cross-sections from the present work and literature data at different bremsstrahlung end-point energies are in good agreement with the theoretical values. It was found that the individual natZn(γ , xn) reaction cross-sections increase sharply from reaction threshold to certain values where the next reaction channel opens. There after it remains constant for a while, where the next reaction channel increases. Then it decreases slowly with increase of bremsstrahlung end-point energy due to opening of different reaction channels.

  11. Theoretical analyses of (n,xn) reactions on sup 235 U, sup 238 U, sup 237 Np, and sup 239 Pu for ENDF/B-VI

    SciTech Connect

    Young, P.G.; Arthur, E.D.

    1991-01-01

    Theoretical analyses were performed of neutron-induced reactions on {sup 235}U, {sup 238}U, {sup 237}Np, and {sup 239}Pu between 0.01 and 20 MeV in order to calculate neutron emission cross sections and spectra for ENDF/B-VI evaluations. Coupled-channel optical model potentials were obtained for each target nucleus by fitting total, elastic, and inelastic scattering cross section data, as well as low-energy average resonance data. The resulting deformed optical model potentials were used to calculate direct (n,n{prime}) cross sections and transmission coefficients for use in Hauser-Feshbach statistical theory analyses. A fission model with multiple barrier representation, width fluctuation corrections, and preequilibrium corrections were included in the analyses. Direct cross sections for higher-lying vibrational states were calculated using DWBA theory, normalized using B(E{ell}) values determined from (d,d{prime}) and Coulomb excitation data, where available, and from systematics otherwise. Initial fission barrier parameters and transition state density enhancements appropriate to the compound systems involved were obtained from previous analyses, especially fits to charged-particle fission probability data. The parameters for the fission model were adjusted for each target system to obtain optimum agreement with direct (n,f) cross section measurements, taking account of the various multichance fission channels, that is, the different compound systems involved. The results from these analyses were used to calculate most of the neutron (n,n), (n,n{prime}), and (n,xn) cross section data in the ENDF/B/VI evaluations for the above nuclei, and all of the energy-angle correlated spectra. The deformed optical model and fission model parameterizations are described. Comparisons are given between the results of these analyses and the previous ENDF/B-V evaluations as well as with the available experimental data. 14 refs., 3 figs., 1 tab.

  12. ({gamma},2{ital N}) reaction in {sup 12}C

    SciTech Connect

    McGeorge, J.C.; MacGregor, I.J.D.; Dancer, S.N.; Annand, J.R.M.; Anthony, I.; Crawford, G.I.; Hall, S.J.; Harty, P.D.; Kellie, J.D.; Miller, G.J.; Owens, R.O.; Wallace, P.A.; Branford, D.; Shotter, A.C.; Schoch, B.; Beck, R.; Schmieden, H.; Vogt, J.M.

    1995-04-01

    The {sup 12}{ital C}({gamma},{ital pn}) and {sup 12}{ital C}({gamma},{ital pp}) reactions have been measured for photon energies between 80 and 157 MeV using a photon tagging spectrometer and plastic scintillator detectors. The overall energy resolution was {similar_to}7 MeV, sufficient to determine the initial shells of the emitted nucleons. Corrections were made for solid angle and threshold effects by means of Monte Carlo simulations. For the ({gamma},{ital pn}) reaction both the missing energy and recoil momentum distributions are largely consistent with a two-nucleon absorption process on {ital p}-shell an {ital sp} nucleon pairs. For the much smaller {sup 12}{ital C}({gamma},{ital pp}) cross section the reaction mechanism is not yet understood but the recoil momentum distributions suggest that final state interactions are not dominant.

  13. Gamma ray line production from cosmic ray spallation reactions

    NASA Technical Reports Server (NTRS)

    Silberberg, R.; Tsao, C. H.; Letaw, J. R.

    1985-01-01

    The gamma ray line intensities due to cosmic ray spallation reactions in clouds, the galactic disk and accreting binary pulsars are calculated. With the most favorable plausible assumptions, only a few lines may be detectable to the level of 0.0000001 per sq. cm per sec. The intensities are compared with those generated in nuclear excitation reactions.

  14. Gamma emission in precompound reactions: 2, Numerical application

    SciTech Connect

    Herman, M.; Reffo, G.; Hoering, A. |

    1992-09-01

    The analytically obtained results of the preceding paper on capture gamma ray reactions are used for a direct numerical calculation. It turns out that this formulation allows for a parameter free description of gamma emission in precompound reactions. As an example we choose reactions induced by 14.1 MeV neutrons incident on {sup 59}CO, {sup 93}Nb and {sup 181}Ta. The individual contributions of different terms to the total cross section are discussed in detail and a comparison to experimental data is pursued.

  15. Gamma emission in precompound reactions: 2, Numerical application

    SciTech Connect

    Herman, M.; Reffo, G. ); Hoering, A. Washington Univ., Seattle, WA . Inst. for Nuclear Theory)

    1992-01-01

    The analytically obtained results of the preceding paper on capture gamma ray reactions are used for a direct numerical calculation. It turns out that this formulation allows for a parameter free description of gamma emission in precompound reactions. As an example we choose reactions induced by 14.1 MeV neutrons incident on {sup 59}CO, {sup 93}Nb and {sup 181}Ta. The individual contributions of different terms to the total cross section are discussed in detail and a comparison to experimental data is pursued.

  16. Investigation of {gamma} radiation from {sup 178}Hf in the respective (n, n Prime {gamma}) reaction

    SciTech Connect

    Govor, L. I.; Demidov, A. M.; Kurkin, V. A. Mikhailov, I. V.

    2012-12-15

    The spectra and angular distributions of gamma rays were measured in the reaction {sup 178}Hf(n, n Prime {gamma}) induced by a beam of fast reactor neutrons. Data onmultipole mixtures in gamma transitions and a lot of new information about gamma transitions of energy 1.5 to 3.0 MeV were obtained. A comparison of these results with information known from the respective (n, {gamma}) reaction made it possible to refine the schemes of deexcitation of {sup 178}Hf levels at energies above 1.5 MeV, to determine more precisely features of these levels, and to introduce new levels and rotation bands at excitation energies of about 2MeV.

  17. Depth profiles of production yields of natPb(p, xn)206,205,204,203,202 Bi reactions using 100-MeV proton beam

    NASA Astrophysics Data System (ADS)

    Oranj, Leila Mokhtari; Jung, Nam-Suk; Oh, Joo-Hee; Lee, Arim; Kim, Dong-Hyun; Bae, Oryun; Lee, Hee-Seock

    2017-09-01

    In this study, results of the experimental study on the depth profiles of production yields of 206,205,204,203,202Bi radio-nuclei in the natural Pb target irradiated by a 100-MeV proton beam are presented. Irradiation was performed at proton linac facility (KOMAC) in Korea. The target, irradiated by 100-MeV protons, was arranged in a stack consisting of natural Pb, Al, Au foils and Pb plates. The proton beam intensity was determined by activation analysis method using 27Al(p, 3p1n)24Na, 197Au(p, p1n)196Au, and 197Au(p, p3n)194Au monitor reactions and also using dosimetry method by a Gafchromic film. The production yields of produced Bi radio-nuclei in the natural Pb foils and monitor reactions were measured by gamma-ray spectroscopy. Monte Carlo simulations were performed by FLUKA, PHITS, and MCNPX codes and compared with the measurements in order to verify validity of physical models and nuclear data libraries in the Monte Carlo codes. A fairly good agreement was observed between the present experimental data and the simulations by FLUKA, PHITS, and MCNPX. However, physical models and the nuclear data relevant to the end of range of protons in the codes need to be improved.

  18. Study of (178m2)hafnium(gamma, gamma')(178)hafnium reaction by nuclear spectroscopy methods

    NASA Astrophysics Data System (ADS)

    Rusu, Claudiu

    Controlled release of the energy stored in nuclear isomers is very attractive for producing powerful sources of induced gamma-ray radiation. High-energy nuclear isomers can have very long lifetimes of the order of years and thus they can serve as good energy storage media. For instance, 1 mg of the 178m2Hf isomer stores about 1 MJ as excitation energy of the isomeric state. One of the most promising ways to release the energy stored in the isomeric state involves photonuclear reactions in the energy range of soft X-rays. Photons with energies lower than 20 keV can excite the 178m2Hf isomeric state to an intermediate level from which gamma transitions cascade to lower levels with a decay rate much faster than the rate of spontaneous decay of the isomeric state. In this work, the photoexcitation of 178m2Hf by (gamma, gamma ') reactions at low energies was studied by nuclear spectroscopy methods. The experimental arrangement was based on the coincident detection of gamma photons with four large HPGe detectors. A bremsstrahlung X-ray generator was used as excitation source, which covered a continuous energy-range from 0 to 60 keV. The interpretation of the experimental results shows that the decay of the 178m2Hf isomer can be triggered by X-rays at a power on the order of only mW/cm 2. The analysis of the gamma-gamma coincidence data has revealed that during X-ray irradiations, a line of 129.5 keV was found in coincidence with the 213.4 keV ground state band (GSB) transition. The 129.5 keV line has not been previously observed and is not a known transition of the spontaneous decay of 178m2Hf. The 129.5 keV gamma transition must be a member of a sequence of gamma transitions that bypasses most of the normal decay cascade populated by spontaneous decay. This result leads to a deeper understanding of the (gamma, gamma ') reactions at low energies. These photonuclear reactions are of special interest because of the importance of possible practical applications. The studies

  19. Measurement of the {sup 157}Gd(n,{gamma}) reaction with the DANCE {gamma} calorimeter array

    SciTech Connect

    Chyzh, A.; Dashdorj, D.; Baramsai, B.; Mitchell, G. E.; Walker, C. L.; Becker, J. A.; Parker, W.; Wu, C. Y.; Becvar, F.; Kroll, J.; Krticka, M.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.

    2011-07-15

    The {sup 157}Gd(n,{gamma}) reaction was measured with the DANCE {gamma} calorimeter (consisting of 160 BaF{sub 2} scintillation detectors) at the Los Alamos Neutron Science Center. The multiplicity distributions of the {gamma} decay were used to determine the resonance spins up to E{sub n}=300 eV. The {gamma}-ray energy spectra for different multiplicities were measured for the s-wave resonances. The shapes of these spectra were compared with simulations based on the use of the DICEBOX statistical model code. Simulations showed that the scissors mode is required not only for the ground-state transitions but also for transitions between excited states.

  20. Excitation functions of 125Te(p, xn)-reactions from their respective thresholds up to 100 MeV with special reference to the production of 124I.

    PubMed

    Hohn, A; Nortier, F M; Scholten, B; van der Walt, T N; Coenen, H H; Qaim, S M

    2001-08-01

    Excitation functions of the nuclear reactions 125Te(p, xn) (119,120m, 120g, 121,122,123,124,125)I were measured for the first time from their respective thresholds up to 100 MeV using the stacked-foil technique. Thin samples were prepared by electrolytic deposition of 98.3% enriched 125Te on Ti-backing. In addition to experimental studies, excitation functions were calculated by the modified hybrid model code ALICE-IPPE. The experimental and theoretical data generally showed good agreement. From the measured cross section data, integral yields of (123,124,125)I were calculated. The energy range Ep 21 --> 15 MeV appears to be very suitable for the production of the medically interesting radionuclide 124I (T(1/2) = 4.18 d; I(beta)+ = 25%). The thick target yield of 124I amounts to 81 MBq/microA h and the level of 125I-impurity to 0.9%. The 125Te(p,2n)124I reaction gives 124I yield about four times higher than the commonly used 124Te(p,n)124I and 124Te(d,2n)124I reactions. The proposed production energy range is too high for small cyclotrons but large quantities of 124I can be produced with medium-sized commercial machines.

  1. Excitation functions of 124Te(d,xn)124,125I reactions from threshold up to 14 MeV: comparative evaluation of nuclear routes for the production of 124I.

    PubMed

    Bastian, T H; Coenen, H H; Qaim, S M

    2001-09-01

    Excitation functions of the nuclear reactions 124Te(d,xn)124-125I were measured from their respective thresholds up to 14.0 MeV via the stacked-foil technique. Thin samples were prepared by electrolytic deposition of 99.8% enriched 124Te on Ti-backing. The excitation function of the 124Te(d,n)125I reaction was measured for the first time. The present data for the 124Te(d,2n)124I reaction are by an order of magnitude higher than the literature experimental data but are in good agreement with the results of a hybrid model calculation. From the measured cross sections, integral yields of 124,125I were calculated. The energy range Ed = 14 --> 10 MeV appears to be the best compromise between 124I-yield and 1251-impurity. The calculated 124I-yield amounts to 17.5 MBq/microA h and the 125I-impurity to 1.7%. A critical evaluation of the three nuclear routes for the production of 124I, viz. 124Te(d,2n)-, 124Te(p,n)- and 125Te(p,2n)-processes, is given. The reaction studied in this work proved to be least suitable. The 124Te(p,n)-reaction gives 124I of the highest radionuclidic purity, and a small-sized cyclotron is adequate for production purposes. The 125Te(p,2n)-reaction is more suitable at a medium-sized cyclotron: the yield of 124I is four times higher than in the other two reactions but the level of 0.9% 125I-impurity is relatively high.

  2. Excitation functions of 120Te(d,xn)121,120m,gI reactions from threshold up to 13.5 MeV: comparative studies on the production of 120gI.

    PubMed

    Hohn, A; Coenen, H H; Qaim, S M

    2000-04-01

    Excitation functions of the nuclear reactions 120Te(d,xn)121,120m,gI were measured for the first time from their respective thresholds up to 13.5 MeV. Thin samples prepared by electrolytic deposition of 99.0% enriched 120Te on Ti-backing were used. Integral yields of 121,120m,gI were calculated from the measured cross section data. A comparison of the 122Te(p,3n)-, 120Te(p,n)- and 120Te(d,2n)-processes for the production of 120gI is given. The 120Te(d,2n)-process is unsuitable for production purposes since the yield of 120gI is very low and the level of 121I impurity very high. The choice lies either on the 122Te(p,3n)- or the 120Te(p,n)-reaction and is governed by the available proton energy and the financial resources for procuring the enriched target material.

  3. Measurement of natW(p,xn)177,178,179Re excitation function of natural tungsten by using a 100-MeV proton beam

    NASA Astrophysics Data System (ADS)

    Yoon, Jungran; Lee, Jieun; Lee, Samyol

    2017-01-01

    Measurements of the proton-induced excitation function for the natW(p,xn)177,178,179Re nuclear reaction has been measured in the energy region below 100 MeV by using the 100-MeV proton linear accelerator at the Korea Multi-Purpose Accelerator Complex. The stacked foil activation technique was adopted in the present study. The gamma-rays generated from the proton-irradiated samples were measured by using a gamma-ray spectroscopy system with a HPGe detector. The 27Al(p,3p+n)24Na reaction was used as a monitor reaction for proton flux monitoring. The nuclear reactions of natW(p,xn)177,178,179Re were observed in the present study. The proton-induced excitation functions of natural tungsten were derived from the delayed gamma-ray yield of the produced nucleus. The present results were compared with the previous experimental excitation function data of Yu. E. Titarenko et al. [1].

  4. Experimental Study of Level Density and {gamma}-strength Functions from Compound Nuclear Reactions

    SciTech Connect

    Voinov, A. V.; Grimes, S. M.; Brune, C. R.; Massey, T. N.; Schiller, A.; Guttormsen, M.; Siem, S.

    2008-04-17

    The current status of experimental study of level density and {gamma}-strength functions is reviewed. Three experimental techniques are used. These are measurements of particle evaporation spectra from compound nuclear reactions, the measurements of particle-{gamma} coincidences from inelastic scattering and pick-up reactions and the method of two-step {gamma}-cascades following neutron/proton radiative capture. Recent experimental data on level densities from neutron evaporation spectra are shown. The first results on the cascade {gamma}-spectrum from the {sup 59}Co(p,2{gamma}){sup 60}Ni reaction are presented.

  5. Updated level scheme of 172Yb from 171Yb(nth, γ) reaction studied via gamma-gamma coincidence spectrometer

    NASA Astrophysics Data System (ADS)

    Nguyen, Ngoc Anh; Nguyen, Xuan Hai; Pham, Dinh Khang; Nguyen, Quang Hung; Ho, Huu Thang

    2017-08-01

    This paper provides the updated information on the level scheme of 172Yb nucleus studied via 171Yb(nth, γ) reaction using the gamma-gamma coincidence spectrometer at Dalat Nuclear Research Institute (Viet Nam). The latter is used because of its advantages in achieving the low Compton background as well as in identifying the correlated gamma transitions. We have detected in total the energies and intensities of 128 two-step gamma cascades corresponding to 79 primary transitions. By comparing the measured data with those extracted from the ENSDF library, 61 primary gamma transitions and corresponding energy levels together with 20 secondary gamma transitions are found to be the same as the ENSDF data. Beside that, 18 additional primary gamma transitions and corresponding energy levels plus 108 secondary ones are not found to currently exist in this library and they are therefore considered as the new data.

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

    SciTech Connect

    Jorn Langheinrich; Ana Lima; Barry Berman

    2006-06-01

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

  7. Validation of (n,gamma) surrogate methods and the 95Mo(n,gamma) reaction

    NASA Astrophysics Data System (ADS)

    Cizewski, J. A.; Adekola, A. S.; Howard, M. E.; Manning, B.; Ratkiewicz, A.; Couture, A. J.; Devlin, M.; Fotiades, N.; Nelson, R. O.; O'Donnell, J. M.; Peters, W. A.; Burke, J. T.; Escher, J. E.; Hatarik, R.; Scielzo, N. D.

    2012-10-01

    Neutron capture on unstable isotopes is important for the synthesis of heavy elements through both the r and s processes and so for nuclear energy and stockpile stewardship science. However, it is difficult to measure these cross sections directly with neutrons on targets that live less than about 100 days. Therefore, there has been a concerted effort by many groups [J.E. Escher RMP 84, 353 (2012) and references therein] to develop a validated surrogate reaction for neutron capture, a reaction that predominantly occurs at relatively low neutron energies where the angular momentum dependence needs to be taken into account. Many of the surrogate approaches use partial cross sections of discrete low-lying gamma-ray transitions to deduce the decay of the compound nucleus. Yet there have been very few measurements of the intensity of these discrete transitions in (n,g) as a function of neutron energy up to 200 keV. As part of the program to validate (d,pg) as a surrogate for neutron capture, we have recently measured the intensity of yrast transitions in 96Mo populated by the 95Mo(n,g) reaction with a small array of HPGe detectors on FP12 at the Lujan Center of LANSCE. Preliminary results of these measurements and the status of the (d,pg) validation program with 95Mo targets will be presented.

  8. Reaction of gamma-tocopherol with hypochlorous acid.

    PubMed

    Nguyen, Quyen; Southwell-Keely, Peter T

    2007-03-01

    In addition to being a very good antioxidant, gamma-tocopherol is also an excellent electrophile trap. This is a study of the reactivity of gamma-tocopherol with hypochlorous acid/hypochlorite, a potential biological foe that is both an oxidant and an electrophile. Aqueous sodium hypochlorite (1.72 mmol; pH 7.4) was stirred with gamma-tocopherol (0.12 mmol) in hexane for 2 min at room temperature. The following products were isolated: gamma-tocopheryl quinone (0.6%), tocored (10%), 3-chloro-gamma-tocopheryl quinone (14%), an ether dimer of 3-chloro-gamma-tocopheryl quinone (0.4%), two isomers of 5-(5-gamma-tocopheryl)-gamma-tocopherol (3 and 2% respectively), 5-chloro-gamma-tocopherol (14%) and two chlorinated dimers (14 and 24% respectively) which were identified as diastereomers of (3R,10R)-11a-chloro-2,3,9,10-tetrahydro-3,5,6,10,12,13-hexamethyl-3,10-bis[(4R,8R)-4,8,12-trimethyltridecyl]-1H-pyrano(3,2a)-8H-pyrano(3,2g)-dibenzofuran-14(7aH)(14aH)-one. The chlorinated dimers, 5-chloro-gamma-tocopherol, 3-chloro-gamma-tocopheryl quinone and its ether dimer are new compounds.

  9. The Consolidated Fleet XN2Y-1

    NASA Technical Reports Server (NTRS)

    1935-01-01

    The Consolidated Fleet XN2Y-1 was a Fleet 1 trainer purchased by the Navy for evaluation. The purchase of several N2Y-1 aircraft followed, for use as trainers for the pilots who would fly the 'parasite' fighters attached to the airships Akron and Macon. The XN2Y-1 was turned over to the NACA for research work. Note the that vertical surfaces are instrumented for NACA spin work.

  10. Thick target measurement of the 40Ca(alpha,gamma)44Ti reaction rate

    SciTech Connect

    Sheets, S A; Burke, J T; Scielzo, N D; Phair, L; Bleuel, D; Norman, E B; Grant, P G; Hurst, A M; Tumey, S; Brown, T A; Stoyer, M

    2009-02-06

    The thick-target yield for the {sup 40}Ca({alpha},{gamma}){sup 44}Ti reaction has been measured for E{sub beam} = 4.13, 4.54, and 5.36 MeV using both an activation measurement and online {gamma}-ray spectroscopy. The results of the two measurements agree. From the measured yield a reaction rate is deduced that is smaller than statistical model calculations. This implies a smaller {sup 44}Ti production in supernova compared to recently measured {sup 40}Ca({alpha},{gamma}){sup 44}Ti reaction rates.

  11. Identification of mouse selenomethionine alpha,gamma-elimination enzyme: cystathionine gamma-lyase catalyzes its reaction to generate methylselenol.

    PubMed

    Okuno, Tomofumi; Motobayashi, Shinji; Ueno, Hitoshi; Nakamuro, Katsuhiko

    2005-01-01

    The purpose of this study was to identify the seleno-L-methionine (L-SeMet) alpha,gamma-elimination enzyme that catalyzes L-SeMet to generate methylselenol (CH3SeH), a notable intermediate for the metabolism of selenium compounds, in mammalian tissues. The enzyme purified from ICR mouse liver was separated by one-dimensional gel electrophoresis, and the specific band was subjected to in-gel trypsin digestion followed by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometric analysis. In the peptide mass fingerprinting search, the mass numbers of 14 peptides produced by tryptic digestion of the enzyme were consistent with the theoretical mass numbers calculated from the amino acid sequence of murine cystathionine gamma-lyase (E.C. 4.4.1.1). The peptide sequence tags search was also performed to obtain the amino acid sequence data of five tryptic peptides. These peptides were significantly identical to the partial amino acid sequences of cystathionine gamma-lyase. This enzyme was clearly shown to catalyze the alpha,gamma-elimination reaction of L-cystathionine by the enzymological research. The Km value for the catalysis of L-cystathionine was 0.81 mM and Vmax was 0.0013 unit/mg protein. These results suggested that cystathionine gamma-lyase catalyzes L-SeMet to generate CH3SeH by its alpha,gamma-elimination reaction.

  12. Formation of gamma(sup prime)-Ni3Al via the Peritectoid Reaction: gamma + beta (+ Al2O3)=gamma(sup prime)(+ Al2O3)

    NASA Technical Reports Server (NTRS)

    Copeland, Evan

    2008-01-01

    The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8-32 at.%Al and temperature range T=1400-1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma(sup prime)-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3)=gamma + Beta(+ Al2O3), at 1640 +/- 1 K and a liquid composition of 24.8 +/- 0.2 at.%al (at an unknown oxygen content). The {gamma + Beta (+Al2O3} phase field is stable over the temperature range 1633-1640 K, and gamma(sup prime)-Ni3Al forms via the peritectoid, gamma + Beta (+ Al2O3)=gamma(sup prime) (+ Al2O3), at 1633 +/- 1 K. This behavior is consistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady-state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma(sup prime)-Ni2Al phase field.

  13. Formation of gamma'-Ni3Al via the Peritectoid Reaction: gamma plus beta (+Al2O3) equals gamma'(+Al2O3)

    NASA Technical Reports Server (NTRS)

    Copland, Evan

    2008-01-01

    The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8 - 32 at.%Al and temperature range T = 1400 - 1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma'-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3) = gamma + beta (+ Al2O3), at 1640 plus or minus 1 K and a liquid composition of 24.8 plus or minus 0.2 at.%Al (at an unknown oxygen content). The {gamma + beta + Al2O3} phase field is stable over the temperature range 1633 - 1640 K, and gamma'-Ni3Al forms via the peritectiod, gamma + beta (+ Al2O3) = gamma'(+ Al2O3), at 1633 plus or minus 1 K. This behavior is inconsistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma'-Ni3Al phase field.

  14. A reduced model for the ICF gamma-ray reaction history diagnostic

    SciTech Connect

    Schmitt, Mark J; Wilson, Douglas C; Hoffman, Nelson M; Langenbrunner, Jamie R; Hermann, H W; Kim, Y H; Young, C S; Evans, S C; Cerjan, C J; Stoeffl, Wolfgang; Munro, D H; Dauffy, L S; Miller, K M; Horsfield, C J; Rubery, M S

    2009-01-01

    An analytic model for the gamma reaction history (GRH) diagnostic to be fielded on the National Ignition Facility is described. The application of the GRH diagnostic for the measurement of capsule rho-R during burn using 4.4 MeV carbon gamma rays is demonstrated by simulation.

  15. A reduced model for the ICF Gamma-Ray reaction history diagnostic

    NASA Astrophysics Data System (ADS)

    Schmitt, M. J.; Wilson, D. C.; Hoffman, N. M.; Langenbrunner, J. R.; Herrmann, H. W.; Kim, Y. H.; Young, C. S.; Evans, S. C.; Cerjan, C. J.; Stoeffl, Wolfgang; Munro, D. H.; Dauffy, L. S.; Miller, K. M.; Horsfield, C. J.; Rubery, M. S.

    2010-08-01

    An analytic model for the gamma reaction history (GRH) diagnostic to be fielded on the National Ignition Facility is described. The application of the GRH diagnostic for the measurement of capsule rho-R during burn using 4.4 MeV carbon gamma rays is demonstrated by simulation.

  16. Optomechanical design of a prompt gamma reaction history diagnostic

    SciTech Connect

    Hermann, Hans W; Kaufman, Morris I; Malone, Robert M; Frogget, Brent C; Tunnell, Thomas W; Cox, Brian; Frayer, Daniel K; Ali, Zaheer; Stoeffl, Wolfgang

    2009-01-01

    The National Ignition Facility and the Omega Laser Facility both have a need for measuring prompt gamma radiation as part of a nuclear diagnostic program. A new gamma-detection diagnostic using off-axis-parabolic mirrors has been built. Some new techniques were used in the design, construction, and tolerancing of this gamma ray diagnostic. Because of the wavelength requirement (250-700 nm), the optical element surface finishes were a key design consideration. The optical enclosure had to satisfy pressure safety concerns and shielding against electromagnetic interference induced by gammas and neutrons. Structural finite element analysis was needed to meet rigorous optical and safety requirements. The optomechanical design is presented. Alignment issues are also discussed.

  17. Study of radionuclides created by sup 181 Ta(. gamma. ,xn yp) reactions for bremsstrahlung photons produced by 150-MeV electrons

    SciTech Connect

    Miller, M.A. ); Dickens, J.K. )

    1991-12-01

    Ten radionuclides, including isomers, from {sup 172}Ta to {sup 180}Ta and {sup 180m}Hf were produced by photon interactions with a sample of elemental tantalum and measured by counting photons using a high-resolution detection system. Relative yields of these radionuclides were obtained. In addition, precision half lives were obtained for {sup 175,176,180}Ta and {sup 180m}Hf. Those obtained for the three Ta isotopes agree with previously reported values. For {sup 180m}Hf, the present measurements resulted in a half life determination of 6.05{plus minus}0.06 hr, or about 10% longer than the currently adopted value for this half life.

  18. Study of radionuclides created by {sup 181}Ta({gamma},xn yp) reactions for bremsstrahlung photons produced by 150-MeV electrons

    SciTech Connect

    Miller, M.A.; Dickens, J.K.

    1991-12-01

    Ten radionuclides, including isomers, from {sup 172}Ta to {sup 180}Ta and {sup 180m}Hf were produced by photon interactions with a sample of elemental tantalum and measured by counting photons using a high-resolution detection system. Relative yields of these radionuclides were obtained. In addition, precision half lives were obtained for {sup 175,176,180}Ta and {sup 180m}Hf. Those obtained for the three Ta isotopes agree with previously reported values. For {sup 180m}Hf, the present measurements resulted in a half life determination of 6.05{plus_minus}0.06 hr, or about 10% longer than the currently adopted value for this half life.

  19. Neutron reactions in accreting neutron stars: a new pathway to efficient crust heating.

    PubMed

    Gupta, Sanjib S; Kawano, Toshihiko; Möller, Peter

    2008-12-05

    In our calculation of neutron star crust heating we include several key new model features. In earlier work electron capture (EC) only allowed neutron emission from the daughter ground state; here we calculate, in a deformed quasi-random-phase approximation (QRPA) model, EC decay rates to all states in the daughter that are allowed by Gamow-Teller selection rules and energetics. The subsequent branching ratios between the 1n,...,xn channels and the competing gamma decay are calculated in a Hauser-Feshbach model. In our multicomponent plasma model a single (EC, xn) reaction step can produce several neutron-deficient nuclei, each of which can further decay by (EC, xn). Hence, the neutron emission occurs more continuously with increasing depth as compared to that in a one-component plasma model.

  20. Mice lacking the gamma interferon receptor have an impaired granulomatous reaction to Schistosoma mansoni infection.

    PubMed Central

    Rezende, S A; Oliveira, V R; Silva, A M; Alves, J B; Goes, A M; Reis, L F

    1997-01-01

    The egg-induced granulomatous reaction in Schistosoma mansoni-infected individuals develops within the portal system of the liver and is the major pathological finding in schistosomiasis. We have infected mice lacking the gamma interferon (IFN-gamma) receptor with S. mansoni larvae and studied the development of hepatic granulomas in these mutant mice in comparison to that in control wild-type mice. In the absence of IFN-gamma activity, a dramatic reduction in the size and architecture of the granuloma was observed. Granulomas from mutant mice were smaller than those from the control group and showed a significant reduction in the number of infiltrating inflammatory cells. Moreover, they appear to prematurely progress to the chronic phase of the reaction at a time when the control group still has acute inflammation. Our data suggests a pivotal role for IFN-gamma in the early events of the granulomatous reaction in vivo. PMID:9234812

  1. Simulation of a gamma reaction history (GRH) detector for use at the National Ignition Facility (NIF)

    NASA Astrophysics Data System (ADS)

    Grafil, Elliot; Toebbe, Jonathan

    2009-10-01

    Reaction history measurements are critical to diagnosing inertial confinement fusion (ICF) implosions. As such they will be essential components of the National Ignition Facility (NIF) diagnostics. One proposed method to record the reaction history is the construction of a gamma-sensitive gas Cerenkov detector. An array of these Cerenkov detectors can be used to discriminate between the different gamma ray energies produced during the ICF implosion. These fusion gammas are converted to optical photons for collection by fast recording systems. We have simulated the gamma reaction history (GRH) detector under development at NIF and LANL using Geant4. Our simulations have been used to determine energy cut-off ranges for photon production in various gases, optimizing converter material and thickness, and discriminating between proposed detector geometries in order to minimize the temporal spread of the signal.

  2. Measuring the charged pion polarizability in the gamma gamma -> pi+pi- reaction

    SciTech Connect

    Lawrence, David W.; Miskimen, Rory A.; Mushkarenkov, Alexander Nikolaevich; Smith, Elton S.

    2013-08-01

    Development has begun of a new experiment to measure the charged pion polarizability $\\alpha_{\\pi}-\\beta_{\\pi}$. The charged pion polarizability ranks among the most important tests of low-energy QCD presently unresolved by experiment. Analogous to precision measurements of $\\pi^{\\circ}\\rightarrow\\gamma\\gamma$ that test the intrinsic odd-parity (anomalous) sector of QCD, the pion polarizability tests the intrinsic even-parity sector of QCD. The measurement will be performed using the $\\gamma\\gamma\\rightarrow\\pi^{+{}}\\pi^{-{}}$ cross section accessed via the Primakoff mechanism on nuclear targets using the GlueX detector in Hall D at Jefferson Lab. The linearly polarized photon source in Hall-D will be utilized to separate the Primakoff cross-section from coherent $\\rho^{\\circ}$ production.

  3. Partial (gamma)-Ray Cross Sections for the Reaction 239Pu(n,2n(gamma)i) and the 239Pu(n,2n) Cross Section

    SciTech Connect

    Beacker, J.A.; Bernstein, L.A.; Younes, W.; McNabb, D.P.; Garrett, P.E.; Archer, D.; McGrath, C.A.; Stoyer, M.A.; Chen, H.; Ormand, W.E.; Nelson, R.O.; Chadwick, M.B.; Johns, G.D.; Drake, D.; Young, P.G.; Devlin, M.; Fotiades, N.; Wilburn, W.S.

    2001-09-14

    Absolute partial {gamma}-ray cross sections for production of discrete {gamma} rays in the {sup 239}Pu(n,2n{gamma}i){sup 238}Pu reaction have been measured. The experiments were performed at LANSCE/WNR on the 60R flight line. Reaction {gamma}-rays were measured using the large-scale Compton-suppressed array of Ge detectors, GEANIE. The motivation for this experiment, an overview of the partial {gamma}-ray cross-section measurement, and an introduction to the main experimental issues will be presented. The energy resolution of the Ge detectors allowed identification of reaction {gamma} rays above the background of sample radioactivity and fission {gamma} rays. The use of planar Ge detectors with their reduced sensitivity to neutron interactions and improved line shape was also important to the success of this experiment. Absolute partial {gamma}-ray cross sections are presented for the 6{sub 1}{sup +} {yields} 4{sub 1}{sup +} member of the ground state rotational band in {sup 238}Pu, together with miscellaneous other {gamma}-ray partial cross sections. The n,2n reaction cross section shape and magnitude as a function of neutron energy was extracted from these partial cross sections using nuclear modeling (enhanced Hauser-Feshbach) to relate partial {gamma}-ray cross sections to the n,2n cross section. The critical nuclear modeling issue is the ratio of a partial cross section to the reaction channel cross section, and not the prediction of the absolute magnitude.

  4. Unbound states of (32)Cl andthe (31)S(p,gamma)(32)Cl reaction rate

    SciTech Connect

    Matos, M.; Blackmon, Jeff C; Linhardt, Laura; Bardayan, Daniel W; Nesaraja, Caroline D; Clark, Jason; Diebel, C.; O'Malley, Patrick; Parker, P.D.

    2011-01-01

    The {sup 31}S(p,{gamma}){sup 32}Cl reaction is expected to provide the dominant break-out path from the SiP cycle in novae and is important for understanding enrichments of sulfur observed in some nova ejecta. We studied the {sup 32}S(3He,t){sup 32}Cl charge-exchange reaction to determine properties of proton-unbound levels in {sup 32}Cl that have previously contributed significant uncertainties to the {sup 31}S(p,{gamma}){sup 32}Cl reaction rate. Measured triton magnetic rigidities were used to determine excitation energies in {sup 32}Cl. Proton-branching ratios were obtained by detecting decay protons from unbound {sup 32}Cl states in coincidence with tritons. An improved {sup 31}S(p,{gamma}){sup 32}Cl reaction rate was calculated including robust statistical and systematic uncertainties.

  5. Cu(. gamma. ,p)X reaction at E/sub. gamma. / = 150 and 300 MeV

    SciTech Connect

    Schumacher, R.A.; Adams, G.S.; Ingham, D.R.; Matthews, J.L.; Sapp, W.W.; Turley, R.S.; Owens, R.O.; Roberts, B.L.

    1982-05-01

    Inclusive photoproton cross sections for the reaction Cu(..gamma..,p)X have been measured for a photon energy of 300 MeV at proton angles 45/sup 0/, 90/sup 0/, and 135/sup 0/, and for 150 MeV at 45/sup 0/. The data are compared with an intranuclear-cascade calculation and with Ni(..pi../sup + -/,p) data. The angular distribution is analyzed to obtain an estimate of the number of nucleons involved in the interaction.

  6. Multi-objective optimization for the National Ignition Facility's Gamma Reaction History diagnostic

    NASA Astrophysics Data System (ADS)

    Labaria, George R.; Liebman, Judith A.; Sayre, Daniel B.; Herrmann, Hans W.; Bond, Essex J.; Church, Jennifer A.

    2013-02-01

    The National Ignition Facility (NIF) is producing experimental results for the study of Inertial Confinement Fusion (ICF). The Gamma Reaction History (GRH) diagnostic at NIF can detect gamma rays to measure fusion burn parameters such as fusion burn width, bang time, neutron yield, and areal density of the compressed ablator for cryogenic deuterium-tritium (DT) implosions. Gamma-ray signals detected with this diagnostic are inherently distorted by hardware impulse response functions (IRFs) and gains, and are comprised of several components including gamma rays from laser-plasma interactions (LPI). One method for removing hardware distortions to approximate the gamma-ray reaction history is deconvolution. However, deconvolution of the distorted signal to obtain the gamma-ray reaction history and its associated parameters presents an ill-posed inverse problem and does not separate out the source components of the gamma-ray signal. A multi-dimensional parameter space model for the distorted gamma-ray signal has been developed in the literature. To complement a deconvolution, we develop a multi-objective optimization algorithm to determine the model parameters so that the error between the model and the collected gamma-ray data is minimized in the least-squares sense. The implementation of the optimization algorithm must be suffciently robust to be used in automated production software. To achieve this level of robustness, impulse response signals must be carefully processed and constraints on the parameter space based on theory and experimentation must be implemented to ensure proper convergence of the algorithm. In this paper, we focus on the optimization algorithm's theory and implementation.

  7. Observable in the reversible reaction gamma + d yields n + p. [photodisintegration of deuteron

    NASA Technical Reports Server (NTRS)

    Rustgi, M. L.; Vyas, R.; Nunemaker, R. D.

    1984-01-01

    Calculations are presented on the effect of the two-body charge and current density effects on the observables in the photodisintegration of a deuteron. The computations are performed in a cartesian coordinate system, initially for gamma rays plane-polarized in the x-direction. Unpolarized photons are treated with an incoherent superposition of transition amplitudes for gamma rays polarized in the x- and y- directions. Account is taken of recoil and interaction energies after an initial state is defined. Consideration is focused on the cross section, polarization, and asymmetry of the reaction at low and medium energy incident gamma rays.

  8. Simulation of a fusion gamma reaction history diagnostic for the Shenguang-III facility

    NASA Astrophysics Data System (ADS)

    Song, Zifeng; Chen, Jiabin; Xu, Tao; Liu, Zhongjie; Zhan, Xiayu; Tang, Qi

    2017-05-01

    The fusion gamma has an advantage to measure fusion reaction history in the deuterium-tritium (DT) fuel implosion experiments. A gas Cherenkov detector is available to measure DT fusion gamma in a high background environment. Simulation is carried out by Geant4 to evaluate the conversion efficiency and the time response of this Cherenkov detector. The background gamma rays are roughly estimated based on ENDF/B-VII.0 data, and the signal-to-noise (SNR) is evaluated based on the simulated energy response curve. The simulation result and the SNR analysis are helpful to construct the Cherenkov detector at Shenguang-III facility.

  9. Evaluation of proton inelastic reaction models in Geant4 for prompt gamma production during proton radiotherapy

    NASA Astrophysics Data System (ADS)

    Jeyasugiththan, Jeyasingam; Peterson, Stephen W.

    2015-10-01

    During proton beam radiotherapy, discrete secondary prompt gamma rays are induced by inelastic nuclear reactions between protons and nuclei in the human body. In recent years, the Geant4 Monte Carlo toolkit has played an important role in the development of a device for real time dose range verification purposes using prompt gamma radiation. Unfortunately the default physics models in Geant4 do not reliably replicate the measured prompt gamma emission. Determining a suitable physics model for low energy proton inelastic interactions will boost the accuracy of prompt gamma simulations. Among the built-in physics models, we found that the precompound model with a modified initial exciton state of 2 (1 particle, 1 hole) produced more accurate discrete gamma lines from the most important elements found within the body such as 16O, 12C and 14N when comparing them with the available gamma production cross section data. Using the modified physics model, we investigated the prompt gamma spectra produced in a water phantom by a 200 MeV pencil beam of protons. The spectra were attained using a LaBr3 detector with a time-of-flight (TOF) window and BGO active shield to reduce the secondary neutron and gamma background. The simulations show that a 2 ns TOF window could reduce 99% of the secondary neutron flux hitting the detector. The results show that using both timing and active shielding can remove up to 85% of the background radiation which includes a 33% reduction by BGO subtraction.

  10. Evaluation of proton inelastic reaction models in Geant4 for prompt gamma production during proton radiotherapy.

    PubMed

    Jeyasugiththan, Jeyasingam; Peterson, Stephen W

    2015-10-07

    During proton beam radiotherapy, discrete secondary prompt gamma rays are induced by inelastic nuclear reactions between protons and nuclei in the human body. In recent years, the Geant4 Monte Carlo toolkit has played an important role in the development of a device for real time dose range verification purposes using prompt gamma radiation. Unfortunately the default physics models in Geant4 do not reliably replicate the measured prompt gamma emission. Determining a suitable physics model for low energy proton inelastic interactions will boost the accuracy of prompt gamma simulations. Among the built-in physics models, we found that the precompound model with a modified initial exciton state of 2 (1 particle, 1 hole) produced more accurate discrete gamma lines from the most important elements found within the body such as 16O, 12C and 14N when comparing them with the available gamma production cross section data. Using the modified physics model, we investigated the prompt gamma spectra produced in a water phantom by a 200 MeV pencil beam of protons. The spectra were attained using a LaBr3 detector with a time-of-flight (TOF) window and BGO active shield to reduce the secondary neutron and gamma background. The simulations show that a 2 ns TOF window could reduce 99% of the secondary neutron flux hitting the detector. The results show that using both timing and active shielding can remove up to 85% of the background radiation which includes a 33% reduction by BGO subtraction.

  11. Gamma Processes

    DTIC Science & Technology

    1986-01-01

    E[exp{-Bn Xn 1 U-Y nU-X vi ] - EeUY )Ee (v+Bu)X1 (2.4) where, in the last step, we have dropped the indices n and n-1 because of stationarity and...1967). "Some Problems of Statistical Inference Relating to Double-Gamma Distribution," Trabajos de Estadistica , 18, 67-87. Hugus, D. K. (1982

  12. Cascade production in the reactions gamma p --> K+ K+ (X) and gamma p --> K+ K+ pi- (X)

    SciTech Connect

    Lei Guo

    2007-08-01

    Photoproduction of the cascade resonances has been investigated in the reactions {gamma}p {yields} K{sup +}K{sup +}(X) and {gamma}p {yields} K{sup +}K{sup +}{pi}{sup -}(X). The mass split of the {Xi} doublet is measured to be 5.4 {+-} 1.8 MeV/c{sup 2}, consistent with existing measurements. The differential (total) cross sections for the {Xi}{sup -} have been determined for photon beam energies from 2.75 to 3.85 (4.75) GeV, and are consistent with a possible production mechanism of Y* {yields} K{sup +}{Xi}{sup -} through a t-channel process. The reaction {gamma}p {yields} K{sup +}K{sup +}{pi}{sup -}({Xi}{sup 0}) has also been investigated in search of excited cascade resonances. No significant signal of excited cascade states other than the {Xi}{sup -}(1530) is observed. The cross section results of the {Xi}{sup -}(1530) have also been obtained for photon beam energies from 3.35 to 4.75 GeV.

  13. High-precision (p,t) reaction to determine {sup 25}Al(p,{gamma}){sup 26}Si reaction rates

    SciTech Connect

    Matic, A.; Berg, A. M. van den; Harakeh, M. N.; Woertche, H. J.; Berg, G. P. A.; Couder, M.; Goerres, J.; LeBlanc, P.; O'Brien, S.; Wiescher, M.; Fujita, K.; Hatanaka, K.; Sakemi, Y.; Shimizu, Y.; Tameshige, Y.; Tamii, A.; Yosoi, M.; Adachi, T.; Fujita, Y.; Shimbara, Y.

    2010-08-15

    Since the identification of ongoing {sup 26}Al production in the universe, the reaction sequence {sup 24}Mg(p,{gamma}){sup 25}Al({beta}{sup +{nu}}){sup 25}Mg(p,{gamma}){sup 26}Al has been studied intensively. At temperatures where the radiative capture on {sup 25}Al (t{sub 1/2}=7.2 s) becomes faster than the {beta}{sup +} decay, the production of {sup 26}Al can be reduced due to the depletion of {sup 25}Al. To determine the resonances relevant for the {sup 25}Al(p,{gamma}){sup 26}Si bypass reaction, we measured the {sup 28}Si(p,t){sup 26}Si reaction with high-energy precision using the Grand Raiden spectrometer at the Research Center for Nuclear Physics, Osaka. Several new energy levels were found above the p threshold and for known states excitation energies were determined with smaller uncertainties. The calculated stellar rates of the bypass reaction agree well with previous results, suggesting that these rates are well established.

  14. Neutron Capture Surrogate Reaction on 75As in Inverse Kinematics Using (d,p(gamma))

    SciTech Connect

    Peters, W A; Cizewski, J A; Hatarik, R; O?Malley, P D; Jones, K L; Schmitt, K; Moazen, B H; Chae, K Y; Pittman, S T; Kozub, R L; Vieira, D; Jandel, M; Wilhelmy, J B; Matei, C; Escher, J; Bardayan, D W; Pain, S D; Smith, M S

    2009-11-09

    The {sup 75}As(d,p{gamma}) reaction in inverse kinematics as a surrogate for neutron capture was performed at Oak Ridge National Laboratory using a deuterated plastic target. The intensity of the 165 keV {gamma}-ray from {sup 76}As in coincidence with ejected protons, from exciting {sup 76}As above the neutron separation energy populating a compound state, was measured. A tight geometry of four segmented germanium clover {gamma}-ray detectors together with eight ORRUBA-type silicon-strip charged-particle detectors was used to optimize geometric acceptance. The preliminary analysis of the {sup 75}As experiment, and the efficacy and future plans of the (d,p{gamma}) surrogate campaign in inverse kinematics, are discussed.

  15. Direct-reaction studies by particle-{gamma} coincidence spectroscopy using Csi-Hpge and Si-Hpge arrays

    SciTech Connect

    Allmond, J. M.

    2013-04-19

    Particle-{gamma} and particle-{gamma}-{gamma} coincidence spectroscopy has several advantages in the study of direct reactions (particularly in inverse kinematics) since it can generally allow determination of: decay paths; high-precision level energies; multipolarities of transitions; and cross sections. Techniques for studying direct reactions by particle-{gamma} coincidence spectroscopy are presented for two cases: (1) heavy-ion reactions with CsI-HPGe, and (2) light-ion reactions with Si-HPGe. Future direct-reaction studies with radioactive ion beams (RIBs) will mostly involve low beam intensities and inverse kinematics (i.e., A{sub beam}>A{sub target}), which eliminates the traditional use of magnetic spectrometers. Particle-{gamma} coincidence spectroscopy currently provides the most viable method to study direct reactions with nuclei of any level density. In the present study, the capabilities and limitations of the technique are explored.

  16. Design and Construction of a Gamma Reaction History Diagnostic for the National Ignition Facility

    SciTech Connect

    R.M. Malone, B.C. Cox, B.C. Frogget, M.I. Kaufman, T.W. Tunnell; H.W. Herrmann, S.C. Evans, J.M. Mack, C.S. Young; W. Stoeffl

    2009-06-05

    Gas Cherenkov detectors have been used to convert fusion gammas into photons to achieve gamma reaction history (GRH) measurements. These gas detectors include a converter, pressurized gas volume, relay optics, and a photon detector. A novel design for the National Ignition Facility (NIF) using 90º Off-Axis Parabolic mirrors efficiently collects signal from fusion gammas with 8-ps time dispersion.1 Fusion gammas are converted to Compton electrons, which generate broadband Cherenkov light (our response is from 250 to 700 nm) in a pressurized gas cell. This light is relayed into a high-speed detector using three parabolic mirrors. The detector optics collect light from a 125-mm-diameter by 600-mm-long interchangeable gas (CO2 or SF6) volume. Because light is collected from source locations throughout the gas volume, the detector is positioned at the stop position rather than at an image position. The stop diameter and its position are independent of the light-generation locations along the gas cell. This design incorporates a fixed time delay that allows the detector to recover from prompt radiation. Optical ray tracings demonstrate how light can be collected from different angled trajectories of the Compton electrons as they traverse the gas volume. A Monte Carlo model of the conversion process from gammas to Cherenkov photons is used to generate photon trajectories. The collection efficiencies for different gamma energies are evaluated. At NIF, a cluster of four channels will allow for increased dynamic range, as well as different gamma energy thresholds. This GRH design is compared to a gas Cherenkov detector that utilizes a Cassegrain reflector now used at the OMEGA laser facility. 1. R. M. Malone, H. W. Herrmann, W. Stoeffl, J. M. Mack, C. S. Young, “Gamma bang time/reaction history diagnostics for the National Ignition Facility using 90º off-axis parabolic mirrors,” Rev. Sci. Instrum. 79, 10E532 (2008).

  17. Thermonuclear breakup reactions of light nuclei. II - Gamma-ray line production and other applications

    NASA Technical Reports Server (NTRS)

    Guessoum, Nidhal

    1989-01-01

    The main consequence of nuclear breakup reactions in high-temperature plasmas is shown to be to reduce the production of the gamma-ray lines, due to the breakup of these species at high temperature. Results of the emissivities of all the relevant gamma-ray lines are discussed. It is shown that the magnitude of the breakup effect on the line emissivities depends strongly on temperature, but more importantly on the plasma density and on the available time for the ion processes. Other effects considered include the production of neutrons (from the breakup of helium) and its consequences (such as the production of gamma rays from n-capture reactions and dynamical effects in accretion disk plasmas).

  18. Thermonuclear breakup reactions of light nuclei. II - Gamma-ray line production and other applications

    NASA Technical Reports Server (NTRS)

    Guessoum, Nidhal

    1989-01-01

    The main consequence of nuclear breakup reactions in high-temperature plasmas is shown to be to reduce the production of the gamma-ray lines, due to the breakup of these species at high temperature. Results of the emissivities of all the relevant gamma-ray lines are discussed. It is shown that the magnitude of the breakup effect on the line emissivities depends strongly on temperature, but more importantly on the plasma density and on the available time for the ion processes. Other effects considered include the production of neutrons (from the breakup of helium) and its consequences (such as the production of gamma rays from n-capture reactions and dynamical effects in accretion disk plasmas).

  19. 232Th(n,{gamma})233Th Thermal Reaction Cross-Section Measurement

    SciTech Connect

    Maidana, Nora L.; Vanin, Vito R.; Pascholati, Paulo R.; Helene, Otaviano; Castro, Ruy M.; Dias, Mauro S.; Koskinas, Marina F.

    2005-05-24

    The 232Th(n,{gamma})233Th thermal neutron-capture reaction cross section was measured using targets of {approx} 1.5 mg of high-purity metallic thorium irradiated in the IPEN IEA-R1m 5 MW pool research reactor. The 197Au(n,{gamma})198Au reaction was used to monitor the thermal and epithermal neutron fluxes in the irradiation position, which was found using the Westcott formalism. The residual gamma-ray activity was followed with an HPGe detector. The detector efficiency curve was fitted by the least-squares method applying covariance analysis to all uncertainties involved. The experimental result is {sigma}0 =7.20{+-}0.20 b, in agreement with previous published values.

  20. New approach to analyzing and evaluating cross sections for partial photoneutron reactions

    SciTech Connect

    Varlamov, V. V. Ishkhanov, B. S.; Orlin, V. N.

    2012-11-15

    The presence of substantial systematic discrepancies between the results of different experiments devoted to determining cross sections for partial photoneutron reactions-first of all, ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) reactions-is a strong motivation for studying the reliability and authenticity of these data and for developing methods for taking into account and removing the discrepancies in question. In order to solve the first problem, we introduce objective absolute criteria involving transitional photoneutron-multiplicity functions F{sub 1}, F{sub 2}, F{sub 3}, Horizontal-Ellipsis ; by definition, their values cannot exceed 1.0, 0.5, 0.33, Horizontal-Ellipsis , respectively. With the aim of solving the second problem, we propose a new experimental-theoretical approach. In this approach, reaction cross sections are evaluated by simultaneously employing experimental data on the cross section for the total photoneutron yield, {sigma}{sup expt}({gamma}, xn) = {sigma}{sup expt}({gamma}, n) + 2{sigma}{sup expt}({gamma}, 2n) + 3{sigma}{sup expt}({gamma}, 3n) + Horizontal-Ellipsis , which are free from drawbacks plaguing experimental methods for sorting neutrons in multiplicity, and the results obtained by calculating the functions F{sub theor}{sup 1}, F{sub theor}{sup 2}, F{sub theor}{sup 3}, Horizontal-Ellipsis on the basis of the modern model of photonuclear reactions. The reliability and authenticity of data on the cross sections for ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) partial reactions-{sigma}{sup eval}({gamma}, in) = F{sub i}{sup theor}{sigma}{sup expt}({gamma}, xn)-were evaluated for the {sup 90}Zr, {sup 115}In, {sup 112,114,116,117,118,119,120,122,124}Sn, {sup 159}Tb, and {sup 197}Au nuclei.

  1. Excitation functions for complete-fusion and transfer reactions in {sup 4}He interaction with {sup 197}Au nuclei

    SciTech Connect

    Kulko, A. A.; Demekhina, N. A.; Kalpakchieva, R.; Muzychka, Yu. A.; Penionzhkevich, Yu. E.; Rassadov, D. N.; Skobelev, N. K.; Testov, D. A.

    2007-04-15

    Excitation functions are measured for the fusion reactions {sup 197}Au({sup 4}He, xn){sup 201-xn}Tl that are induced by alpha-particle interaction with gold nuclei in the energy range 14-36 MeV and in which x neutrons (0 {<=} x {<=} 3) are evaporated. The stack-activation technique was used to record and separate reaction products. Experimental data on the fusion reactions followed by evaporation of one to three neutrons agree with results of previous studies. For the radiative-capture reaction {sup 197}Au({sup 4}He,{gamma}){sup 201}Tl, the upper limit on the cross section proved to be much lower. The excitation functions for the reactions subjected to measurements are compared with the results of calculations based on the statistical model and with the results of an experiment performed previously in a {sup 6}He beam.

  2. Particle-gamma and particle-particle correlations in nuclear reactions using Monte Carlo Hauser-Feshback model

    SciTech Connect

    Kawano, Toshihiko; Talou, Patrick; Watanabe, Takehito; Chadwick, Mark

    2010-01-01

    Monte Carlo simulations for particle and {gamma}-ray emissions from an excited nucleus based on the Hauser-Feshbach statistical theory are performed to obtain correlated information between emitted particles and {gamma}-rays. We calculate neutron induced reactions on {sup 51}V to demonstrate unique advantages of the Monte Carlo method. which are the correlated {gamma}-rays in the neutron radiative capture reaction, the neutron and {gamma}-ray correlation, and the particle-particle correlations at higher energies. It is shown that properties in nuclear reactions that are difficult to study with a deterministic method can be obtained with the Monte Carlo simulations.

  3. Precision investigations of nuclei and nucleons with the (e, e'. gamma. ) reaction

    SciTech Connect

    Papanicolas, C.N.; Ammons, E.A.; Cardman, L.S.; Deininger, J.R.; Dolfini, S.M.; Mandeville, J.B.; Mueller, P.E.; Williamson, S.E.

    1988-11-20

    Recent theoretical and experimental investigations of the (e, e'..gamma..) reaction show that it provides a probe of unparalleled precision and selectivity. Experiments aimed towards the isolation of multipole form factors in mixed transitions, the study of continuum excitations in nuclei, and the measurement of the response of the proton are underway at several laboratories.

  4. Neutron-induced gamma-ray production

    SciTech Connect

    Nelson, R.O.; Drake, D.M.; Haight, R.C.; Laymon, C.M.; Wender, S.A.; Young, P.G. ); Drosg, M.; Pavlik, A.; Vonach, H. . Inst. fuer Radiumforschung und Kernphysik); Larson, D.C. )

    1990-01-01

    High resolution Ge detectors coupled with the WNR high-intensity, high-energy, pulsed neutron source at LAMPF recently have been used to measure a variety of reactions including (n,xn) for 1 {le} x {le} 11, (n,n{alpha}), (n,np), etc. The reactions are identified by the known gamma-ray energies of prompt transitions between the low lying states in the final nuclei. With our spallation neutron source cross section data are obtained at all neutron energies from a few MeV to over 200 MeV. Applications of the data range from assisting the interpretation of the planned Mars Observer mission to map the elemental composition of the martian surface, to providing data for nuclear model verification and understanding reaction mechanisms. For example, a study of the Pb(n,xn) reactions for 2 {le} x {le} 11 populating the first excited states of the even Pb isotopes is underway. These data will be used to test preequilibrium and other reaction models. 9 refs., 5 figs.

  5. Using {sup 171,173}Yb(d,p{gamma}) to Benchmark a Surrogate Reaction for Neutron Capture

    SciTech Connect

    Hatarik, R.; Cizewski, J. A.; Hatarik, A. M.; O'Malley, P. D.; Bernstein, L. A.; Bleuel, D. L.; Burke, J. T.; Lesher, S. R.; Gibelin, J.; Phair, L.; Swan, T.

    2009-03-10

    The {sup 171,173}Yb(d,p{gamma}) reactions have been measured to determine the efficacy of this reaction as a surrogate for neutron capture on radioactive nuclei. Preliminary results for the surrogate cross section ratios, with gating conditions that best mimic the spin distribution of neutron capture, reproduce the Wisshak et al., (n,{gamma}) cross section ratios within 15%.

  6. Geant4 supplied parameters for gamma reaction history at NIF

    NASA Astrophysics Data System (ADS)

    Rubery, Michael; Horsfield, Colin; Herrmann, Hans; Kim, Yongho; Mack, Joe; Young, Carl; Evans, Scott; Sedillo, Tom; Miller, Kirk; Stoeffl, Wolfgang; Grafil, Elliot

    2011-10-01

    The GRH diagnostics at NIF and Omega report ICF burn parameters through detection of multi-MeV γ emissions. Of particular interest is ` γ bang-time' (GBT), defined as the temporal separation between light impacting the capsule and peak in the nuclear reaction history; GBT can constrain shock and compression parameters, and indicate fuel/ablator mix. Early NIF commissioning experiments have identified contributions to GRH signals from n,n' γ reactions with remaining capsule ablator, hohlraum and thermo-mechanical package, outside the fuel hotspot region. Such contributions are mitigated by increasing the Cherenkov threshold above the energy of these emissions. The pressure adjustment modifies parameters important to GBT, such as cell time-of-flight and detector FWHM; corrections simulated using Geant4 are presented using models experimentally validated at Duke University. Beyond GBT, studies suggest GRH may be capable of recording ablator ρR, unfolding the DT γ spectrum, and inferring the DTγ /DTn branching ratio. All calculations rely on the energy-resolved intensity response as a function of gas pressure. Geant4 response simulations, together with calculations by LANL using the experimentally validated ACCEPT code, are also presented.

  7. Extracting the Asymptotic Normalization Coefficients in Neutron Transfer Reactions to Determine the Astrophysical Reaction Rates for {sup 22}Mg(p,{gamma}){sup 23}Al and {sup 17}F(p,{gamma}){sup 18}Ne

    SciTech Connect

    Al-Abdullah, T.; Chen, X.; Clark, H.; Fu, C.; Gagliardi, C. A.; Lui, Y.-W.; Mukhamedzhanov, A. M.; Tabacaru, G.; Tokimoto, Y.; Trache, L.; Tribble, R. E.; Zhai, Y.; Carstoiu, F.

    2008-01-24

    It was expected that {gamma} rays from {sup 18}F and {sup 22}Na would be observed in massive One novae, but neither has been to date. The {sup 17}F(p,{gamma}){sup 18}Ne and {sup 22}Mg(p,{gamma}){sup 23}Al reactions may play important roles in the production and destruction of {sup 18}F and {sup 22}Na. We have determined the asymptotic normalization coefficients for {sup 18}Ne and {sup 23}Al through measurements of peripheral neutron transfer reactions in the mirror nuclear systems. We use the ANCs to calculate the astrophysical S-factors and reaction rates for these two reactions.

  8. Design and Construction of a Gamma Reaction History Diagnostic for the National Ignition Facility

    SciTech Connect

    Malone, R M; Evans, S C; Frogget, B C; Herrmann, H W; Kaufman, M I; Kim, Y H; Mack, J M; McGillivray, K D; Palagi, M; Stoeffl, W; Tibbitts, A; Tunnell, T W; Young, C S

    2009-10-22

    Gas Cherenkov detectors have been used to convert fusion gammas into photons to record gamma reaction history measurements. These gas detectors include a converter, pressurized gas volume, relay collection optics, and a photon detector. A novel design for the National Ignition Facility (NIF) using 90° off-axis parabolic mirrors efficiently collects signal from fusion gammas with 8-ps time dispersion. Fusion gammas are converted to Compton electrons, which generate broadband Cherenkov light (response is from 250 to 700 nm) in a pressurized gas cell. This light is relayed into a high-speed detector using three parabolic mirrors. The relay optics collect light from a 125-mm-diameter by 600-mm-long interchangeable gas (CO2 or SF6) volume. The parabolic mirrors were electroformed instead of diamond turned to reduce scattering of the UV light. All mirrors are bare aluminum coated for maximum reflectivity. This design incorporates a 4.2-ns time delay that allows the detector to recover from prompt radiation before it records the gamma signal. At NIF, a cluster of four channels will allow for increased dynamic range, as well as different gamma energy thresholds.

  9. Determininig the (n,{gamma}) cross section of {sup 153}Gd using surrogate reactions

    SciTech Connect

    Scielzo, N. D.; Bernstein, L. A.; Bleuel, D. L.; Burke, J. T.; Lesher, S. R.; Norman, E. B.; Sheets, S. A.; Basunia, M. S.; Clark, R. M.; Fallon, P.; Gibelin, J.; Lyles, B.; McMahan, M. A.; Moretto, L. G.; Phair, L. W.; Rodriguez-Vieitez, E.; Wiedeking, M.; Allmond, J. M.; Beausang, C. W.

    2008-04-17

    The astrophysical s-process is responsible for the synthesis of many of the nuclei heavier than iron through a series of low-energy (n,{gamma}) reactions and {beta}-decays. For nuclei for which the neutron capture and {beta}-decay rates are comparable, the branching is crucial for tests of s-process models. Direct measurements of (n,{gamma}) cross sections for these nuclei are extremely challenging due to the inherent difficulties associated with radioactive targets and the low intensity of available neutron beams. The surrogate reaction technique can be used to circumvent these difficulties by creating the same compound nucleus through light-ion reactions on a stable target. The cross section can be determined by combining optical model calculations for the formation of the compound nucleus with the measured exit channel probability for {gamma}-ray emission. We have collected data to determine the low-energy (n,{gamma}) cross section for the unstable nucleus {sup 153}Gd by bombarding a stable {sup 154}Gd target with protons from the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory to create the desired {sup 154}Gd* compound nucleus. The STARS/LiBerACE silicon and clover germanium detector arrays were used to detect {gamma}-rays in coincidence with the scattered protons. Additional cross section measurements using {sup 156}Gd and {sup 158}Gd targets will be compared to direct measurements of the (n,{gamma}) cross sections for {sup 155}Gd and {sup 157}Gd. The current status of the analysis is summarized.

  10. Excitation Functions for Complete Fusion and Transfer Reactions in the Interaction of 4He Nuclei with 197Au

    SciTech Connect

    Kulko, A. A.; Demekhina, N. A.; Kalpakchieva, R.; Muzychka, Yu. A.; Penionzhkevich, Yu. E.; Rassadov, D. N.; Skobelev, N. K.; Testov, D. A.

    2007-05-22

    Excitation functions have been measured for the fusion reaction 197Au({alpha}xn)201-xnTl with the evaporation of x neutrons (0{<=}x{<=}3) in the energy range 14-36 MeV. The induced-activation method was used for registration and identification of the reaction products. The experimental cross sections for the (1-3)-neutron evaporation residues are in good agreement with the results known from literature. For the radiation capture reaction 197Au({alpha},{gamma})201Tl, the upper limit was obtained essentially lower. The excitation functions for the measured reactions are compared with calculations in the frame of the statistical model, as well as with formerly measured similar data with a 6He beam.

  11. 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.

  12. Search for the $\\Theta^+$ pentaquark in the reaction $\\gamma d \\to p K^- K^+ n$

    SciTech Connect

    B. McKinnon; K. Hicks; N.A. Baltzell; D.S. Carman; M.D. Mestayer; T. Mibe; M. Mirazita; S. Niccolai; P. Rossi; S. Stepanyan; D.J. Tedeschi; et. al.

    2006-04-04

    A search for the {Theta}{sup +} in the reaction {gamma}d {yields} pK{sup -} K{sup +} n was completed using the CLAS detector at Jefferson Lab. An earlier publication of the same reaction by the CLAS Collaboration, with lower statistics, reported the observation of a narrow resonance, identified as the {Theta}{sup +} pentaquark. The present experiment, with more than 30 times the integrated luminosity of our earlier measurement, does not show any evidence for a narrow pentaquark resonance. The upper limit on {Theta}{sup +} production in the mass range of 1.52 to 1.56 GeV/c{sup 2} for the {gamma}d {yields} pK{sup -}{Theta}{sup +} reaction is less than 0.3 nb (95% confidence level), and less than 0.6 nb over the mass range 1.48 to 1.70 GeV/c{sup 2}. Using {Lambda}(1520) production as an empirical measure of rescattering in the deuteron, the cross section upper limit for the elementary {gamma}n {yields} K{sup -}{Theta}{sup +} reaction is estimated to be a factor of 10 higher.

  13. Interfacial reaction of coated SiC fibers with gamma-TiAl

    SciTech Connect

    Goo, G.K.; Graves, J.A.; Mecartney, M.L. Rockwell International Science Center, Thousand Oaks, CA )

    1992-04-01

    The reaction products at the interface between a gamma-TiAl matrix and reinforcing SiC fibers are presently identified by Auger spectroscopy, TEM, and EDS. A scheme is suggested for the reaction kinetics involved, in which the initial reaction between the TiAl and the C-rich SiC produces TiC(1-x); unreacted Al, rejected from this carbide, can then diffuse into both the matrix and (to a lesser extent) the SiC fiber itself. The unreacted Si in the fiber coating is rejected back into the fiber, but some diffuses through the TiC(1-x) layer to the reaction zone/matrix boundary, while trace amounts of unreacted Si remain in the reaction layer in solid solution. 22 refs.

  14. Reaction of glass during gamma irradiation in a saturated tuff environment. Part 1. SRL 165 glass

    SciTech Connect

    Bates, J.K.; Fischer, D.F.; Gerding, T.J.

    1986-02-01

    The influence of gamma irradiation on the reaction of actinide-doped borosilicate glass (SRL 165) in a saturated tuff environment has been studied in a series of tests lasting up to 56 days. The following conclusions were reached. The reaction of, and subsequent actinide release from, the glass depends on the dynamic interaction between radiolysis effects, which cause the solution pH to become more acidic; glass reaction, which drives the pH more basic; and test component interactions that may extract glass components from solution. The use of large gamma irradiation dose rates to accelerate reactions that may occur in an actual repository radiation field may affect this dynamic balance by unduly influencing the mechanism of the glass-water reaction. Comparisons between the present results and data obtained by reacting similar glasses using MCC-1 and NNWSI rock cup procedures indicate that the irradiation conditions used in the present experiments do not dramatically influence the reaction rate of the glass. 8 figs., 9 tabs.

  15. Prompt gamma ray diagnostics and enhanced hadron-therapy using neutron-free nuclear reactions

    NASA Astrophysics Data System (ADS)

    Giuffrida, L.; Margarone, D.; Cirrone, G. A. P.; Picciotto, A.; Cuttone, G.; Korn, G.

    2016-10-01

    We propose a series of simulations about the potential use of Boron isotopes to trigger neutron-free (aneutronic) nuclear reactions in cancer cells through the interaction with an incoming energetic proton beam, thus resulting in the emission of characteristic prompt gamma radiation (429 keV, 718 keV and 1435 keV). Furthermore assuming that the Boron isotopes are absorbed in cancer cells, the three alpha-particles produced in each p-11B aneutronic nuclear fusion reactions can potentially result in the enhancement of the biological dose absorbed in the tumor region since these multi-MeV alpha-particles are stopped inside the single cancer cell, thus allowing to spare the surrounding tissues. Although a similar approach based on the use of 11B nuclei has been proposed in [Yoon et al. Applied Physics Letters 105, 223507 (2014)], our work demonstrate, using Monte Carlo simulations, the crucial importance of the use of 10B nuclei (in a solution containing also 11B) for the generation of prompt gamma-rays, which can be applied to medical imaging. In fact, we demonstrate that the use of 10B nuclei can enhance the intensity of the 718 keV gamma-ray peak more than 30 times compared to the solution containing only 11B nuclei. A detailed explanation of the origin of the different prompt gamma-rays, as well as of their application as real-time diagnostics during a potential cancer treatment, is here discussed.

  16. Radiation reaction in the interaction of ultraintense laser with matter and gamma ray source

    NASA Astrophysics Data System (ADS)

    Ong, J. F.; Teo, W. R.; Moritaka, Toseo; Takabe, H.

    2016-05-01

    Radiation reaction (RR) force plays an important role in gamma ray production in the interaction of ultraintense laser with relativistic counterpropagating electron at intensity 1022 W/cm2 and beyond. The relationship between emission spectrum and initial kinetic energy of electron at such intensities is yet to be clear experimentally. On the other hand, the energy from both the relativistic electron beam and laser pulse may be converted into the gamma rays. Therefore, the conversion efficiency of energy purely from laser pulse into gamma rays is of great interest. We present simulation results of an electron dynamics in strong laser field by taking into account the RR effects. We investigated how the RR effects influence the emission spectrum and photon number distribution for different laser condition. We showed that the peaks of emission spectra are suppressed if higher initial kinetic energy of electron interacts with long laser pulse duration. We then list the conversion efficiencies of laser pulse energy into gamma ray. We note that an electron with energy of 40 MeV would convert up to 80% of the total of electromagnetic work and initial kinetic energy of electron when interacting with 10 fs laser pulse at intensity 2 ×1023 W/cm2. For a bunch of electron with charge 1 nC would emit around 0.1 J of energy into gamma ray emission.

  17. Dipole strength in the {sup 235}U(gamma,gamma{sup '}) reaction up to 2.8 MeV

    SciTech Connect

    Yevetska, O.; Enders, J.; Fritzsche, M.; Neumann-Cosel, P. von; Romig, C.; Savran, D.; Sonnabend, K.; Oberstedt, S.; Richter, A.

    2010-04-15

    Spectra of the {sup 235}U(gamma,gamma{sup '}) reaction were measured at the S-DALINAC at bremsstrahlung end-point energies E{sub 0}=3.5 and 4.4 MeV and scattering angles of 90 deg. and 135 deg. with respect to the beam axis. Discrete transitions are observed at excitation energies below 2.3 MeV only. The deduced cross sections are in rough agreement with the findings of Bertozzi et al. [Phys. Rev. C 78, 041601(R) (2008)] except for the most prominent transition, where the present result is lower by a factor of about 2. Evidence for unresolved dipole strength is found in the spectra by means of a fluctuation analysis, which was carried out up to an excitation energy of 2.8 MeV. If this unresolved strength exhibits the same ratio of E1/M1 cross sections as observed in the even-mass neighbor {sup 236}U, then the energy centroid E{sub x}=2.5(3) MeV and total strength SIGMAB(M1)arrow up=3.6(1.3)mu{sub N}{sup 2} of the M1 part are in good agreement with the systematics of the scissors mode in even-even actinide nuclei.

  18. {gamma}-ray spectroscopy of {sub 17}{sup 38}Cl using grazing reactions

    SciTech Connect

    O'Donnell, D.; Chapman, R.; Liang, X.; Burns, M.; Hodsdon, A.; Keyes, K.; Ollier, J.; Papenberg, A.; Smith, J. F.; Spohr, K. M.; Wang, Z. M.; Azaiez, F.; Ibrahim, F.; Stanoiu, M.; Verney, D.; Haas, F.; Caurier, E.; Curien, D.; Nowacki, F.; Salsac, M.-D.

    2010-02-15

    Excited states of {sub 17}{sup 38}Cl{sub 21} were populated in binary grazing reactions during the interaction of a beam of {sub 16}{sup 36}S{sub 20} ions of energy 215 MeV with a {sub 82}{sup 208}Pb{sub 126} target. The combination of the PRISMA magnetic spectrometer and the CLARA {gamma}-ray detector array was used to identify the reaction fragments and to detect their decay via {gamma}-ray emission. A level scheme for {sup 38}Cl is presented and discussed within the context of the systematics of neighboring nuclei and is compared with the results of state-of-the-art shell-model calculations.

  19. Investigation of the d(γ,n)p reaction for gamma beam monitoring at ELI-NP

    NASA Astrophysics Data System (ADS)

    Matei, C.; Mueller, J. M.; Sikora, M. H.; Suliman, G.; Ur, C. A.; Weller, H. R.

    2016-05-01

    The Extreme Light Infrastructure - Nuclear Physics facility will deliver brilliant gamma beams with high spectral density and a high degree of polarization starting in 2018 in Bucharest-Magurele, Romania. Several monitoring instruments are proposed for measuring the spectral, temporal, and spatial characteristics of the gamma beam. The d(γ,n)p reaction has been investigated for its use in determining the gamma beam parameters in a series of measurements carried out at the High Intensity Gamma Source, Durham, U.S.A.. Measurements of the emitted neutrons have been performed using liquid scintillator and 6Li-glass neutron detectors at several incident gamma energies between 2.5 to 20 MeV . The experimental results presented in this paper have shown that an instrument based on the d(γ,n)p reaction can be used to monitor the intensity and polarization of the gamma beam to be produced at ELI-NP.

  20. Phosphite radicals and their reactions. Examples of redox, substitution, and addition reactions. [Gamma rays and electrons

    SciTech Connect

    Schaefer, K.; Asmus, K.D.

    1980-08-21

    Phosphite radicals HPO/sub 3/- and PO/sub 3//sup 2/-, which exist in an acid-base equilibrium with pK = 5.75, are shown to take part in various types of reactions. In the absence of scavengers, they disappear mainly by second-order disproportionation and combination; a first-order contribution to the decay is also indicated. HPO/sub 3/- and PO/sub 3//sup 2/- are good reductants toward electron acceptors such as tetranitromethane. In this reaction phosphate and C(NO/sub 2/)/sub 3/- are formed. Phosphite radicals can, however, also act as good oxidants, e.g., toward thiols and thiolate ions. These reactions lead to the formation of RS. radicals which were identified either directly, as in the case of penicillamine, through the optical absorption of PenS. or more indirectly through equilibration of RS. with RS- to the optically absorbing RSSR-. disulfide radical anion. A homolytic substitution reaction (S/sub H/2) occurs in the reaction of the phosphite radicals with aliphatic disulfides, yielding RS. radicals and phosphate thioester RSPO/sub 3//sup 2/-. Lipoic acid, as an example of a cyclic disulfide, is reduced to the corresponding RSSR-. radical anion and also undergoes the S/sub H/2 reaction with about equal probability. An addition reaction is observed between phosphite radicals and molecular oxygen. The resulting peroxo phosphate radicals establish an acid-base equilibrium HPO/sub 5//sup -/. reversible PO/sub 5//sup 2 -/. + H+ with a pK = 3.4. Absolute rate constants were determined for all reactions discussed.

  1. Study of near-stability nuclei populated as fission fragments in heavy-ion fusion reactions

    SciTech Connect

    Fotiadis, Nikolaos; Nelson, Ronald O; Devlin, Matthew; Cizewski, Jolie A; Krucken, Reiner; Clark, R M; Fallon, Paul; Lee, I Yang; Macchiavelli, Agusto O; Becker, John A; Younes, Walid

    2010-01-01

    Examples are presented to illustrate the power of prompt {gamma}-ray spectroscopy of fission fragments from compound nuclei with A {approx} 200 formed in fusion-evaporation reactions in experiments using the Gammasphere Ge-detector array. Complementary methods, such as Coulomb excitation and deep-inelastic processes, are also discussed. In other cases (n, xn{gamma}) reactions on stable isotopes have been used to establish neutron excitation functions for {gamma}-rays using a pulsed 'white'-neutron source, coupled to a high-energy-resolution germanium-detector array. The excitation functions can unambiguously assign {gamma}-rays to a specific reaction product. Results from all these methods bridge the gaps in the systematics of high-spin states between the neutron-deficient and neutron-rich nuclei. Results near shell closures should motivate new shell model calculations.

  2. Molecular diagnosis of A gamma hereditary persistence of fetal hemoglobin using polymerase chain reaction and oligonucleotide analysis.

    PubMed

    Gottardi, E; Alfarano, A; Serra, A; Sciarratta, G; Bertero, M T; Saglio, G; Camaschella, C

    1990-01-01

    By combining the polymerase chain reaction (PCR) of the gamma globin gene promoters with synthetic oligonucleotide analysis we have diagnosed the -196 C----T and the -117 G----A substitutions in heterozygous carriers of non deletional A gamma HPFH from two unrelated Italian families. The identification of the beta-thalassemic defect in a compound heterozygote for -196 A gamma HPFH/beta thalassemia allows us to discuss the effect of this gamma promoter mutation on the globin chain synthetic pattern, and to make a comparison with the mutation at the -117 position.

  3. /sup 204/Pb(n,n'. gamma. )/sup 204/Pb reaction

    SciTech Connect

    Dawson, W.K.; Green, P.W.; Hooper, H.R.; Neilson, G.C.; Sheppard, D.M.; Siefken, H.E.; Smith, D.L.; Davidson, J.M.

    1980-08-01

    The excited states of /sup 204/Pb were studied using the /sup 204/Pb(n,n'..gamma..) reaction. Gamma-ray excitation functions and angular distributions were recorded using a small-sample technique. Previously unreported /sup 204/Pb levels were observed at 1605 +- 1, 1682 +- 1, 1762 +- 1, 1873 +- 1, and 2276 +- 3 keV excitation. The spins of the levels at 1682, 1762, 1873, and 2276 keV are J=1, 2, or 3/sup -/. The spin and parity of the 1605 keV level is limited to J/sup ..pi../=3/sup +/ or 4/sup +/. Multipole mixing ratios were measured for several transitions where the initial and final state spins and parities were firmly established from previous work.

  4. Search for the Theta+ pentaquark in the gamma d -> Lambda n K+ reaction measured with CLAS

    SciTech Connect

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

    2006-04-26

    For the first time, the reaction gamma d -> Lambda n K+ has been analyzed in order to search for the exotic pentaquark baryon Theta+(1540). The data were taken at Jefferson Lab, using the Hall-B tagged-photon beam of energy between 0.8 and 3.6 GeV and the CEBAF Large Acceptance Spectrometer (CLAS). No statistically significant structures were observed in the nK+ invariant mass distribution. The upper limit on the gamma d -> Lambda Theta+ integrated cross section has been calculated and found to be between 5 and 25 nb, depending on the production model assumed. The upper limit on the differential cross section is also reported.

  5. Investigation of phonon excitations in {sup 114}Cd with the (n,n{sup '}{gamma}) reaction

    SciTech Connect

    Bandyopadhyay, D.; Lesher, S. R.; Fransen, C.; Boukharouba, N.; McEllistrem, M. T.; Garrett, P. E.; Green, K. L.; Yates, S. W.

    2007-11-15

    Properties of low-spin states in {sup 114}Cd have been studied with the (n,n{sup '}{gamma}) reaction. Gamma-ray angular distributions and excitation functions have been used to characterize the decays of the excited levels. Level lifetimes have been obtained with the Doppler-shift attenuation method. Sixteen new levels and many new transitions have been suggested below 3.5 MeV in excitation energy. Levels belonging to the phonon multiplets have been proposed based on their decay patterns and collectivity, and the existing intruder structure has been extended. A two-phonon 1{sub ms}{sup +} state has been suggested. Excitation of the hexadecapole moment has been considered. Data have been compared with the theoretical calculations of the interacting boson model.

  6. 40Ca(alpha, gamma)44Ti reaction in the energy regime of supernova nucleosynthesis.

    PubMed

    Nassar, H; Paul, M; Ahmad, I; Ben-Dov, Y; Caggiano, J; Ghelberg, S; Goriely, S; Greene, J P; Hass, M; Heger, A; Heinz, A; Henderson, D J; Janssens, R V F; Jiang, C L; Kashiv, Y; Nara Singh, B S; Ofan, A; Pardo, R C; Pennington, T; Rehm, K E; Savard, G; Scott, R; Vondrasek, R

    2006-02-03

    The 44Ti(t1/2=59 yr) nuclide, an important signature of supernova nucleosynthesis, has recently been observed as live radioactivity by gamma-ray astronomy from the Cas A remnant. We investigate in the laboratory the major 44Ti production reaction 40Ca(alpha, gamma)44Ti (Ec.m. approximately 0.6-1.2 MeV/u by direct off-line counting of 44Ti nuclei. The yield, significantly higher than inferred from previous experiments, is analyzed in terms of a statistical model using microscopic nuclear inputs. The associated stellar rate has important astrophysical consequences, increasing the calculated supernova 44Ti yield by a factor approximately 2 over previous estimates and bringing it closer to Cas A observations.

  7. Gamma Spectroscopy of States in {sup 32}Cl Relevant for the {sup 31}S({ital p},{gamma}){sup 32}Cl Reaction Rate

    DOE PAGES

    Afanasieva, L.; Blackmon, J. C.; Deibel, C. M.; ...

    2017-09-01

    Background: The 31S(p,gamma) 32Cl reaction becomes important for sulfur production in novae if the P-31(p, alpha)Si-28 reaction rate is somewhat greater than currently accepted. The rate of the S-31(p,gamma) Cl-32 reaction is uncertain, primarily due to the properties of resonances at E-c.m. = 156 and 549 keV. Purpose: We precisely determined the excitation energies of states in Cl-32 through high-resolution. spectroscopy including the two states most important for the S-31(p,gamma) Cl-32 reaction at nova temperatures. Method: Excited states in Cl-32 were populated using the B-10(Mg-24, 2n) Cl-32 reaction with a Mg-24 beam from the ATLAS facility at Argonne National Laboratory.more » The reaction channel of interest was selected using recoils in the Fragment Mass Analyzer, and precise level energies were determined by detecting. rays with Gammasphere. Results: We observed. rays from the decay of six excited states in Cl-32. The excitation energies for two unbound levels at E-x = 1738.1 (6) keV and 2130.5 (10) keV were determined and found to be in agreement with a previous high-precision measurement of the S-32(He-3, t) Cl-32 reaction [1]. Conclusions: An updated 31S(p,gamma) Cl-32 reaction rate is presented. With the excitation energies of important levels firmly established, the dominant uncertainty in the reaction rate at nova temperatures is due to the strength of the resonance corresponding to the 2131-keV state in Cl-32.« less

  8. Study of the 11C(p,gamma) reaction via the indirect d(11C,12N)ntransfer reaction

    SciTech Connect

    Lee, Dongwon; Powell, James; Perajarvi, Kari; Guo, Fanqing; Moltz, Dennis; Cerny, Joseph

    2008-01-07

    The {sup 11}C(p,{gamma}){sup 12}N reaction is expected to be an important branch point in supermassive low-metallicity stars because it could produce CNO seed nuclei before the traditional triple-alpha process turns on. In the present work, the d({sup 11}C, {sup 12}N)n transfer reaction was employed to evaluate this reaction using a radioactive ion beam of 150 MeV {sup 11}C with 6 x 10{sup 5} ions/s on target from the BEARS project at the 88-inch cyclotron at Lawrence Berkeley National Laboratory. Excellent agreement was obtained between the experimental cross sections ({theta}{sub c.m.} = 10.9{sup o} to 71.5{sup o}) and DWBA calculations. The asymptotic normalization coefficient was deduced to be (C{sub eff}{sup 12N}){sup 2} = (C{sub p1/2}{sup 12N}){sup 2} + (C{sub p3/2}{sup 12N}){sup 2} = 1.83 {+-} 0.27 fm{sup -1}.

  9. Unitary model for the {gamma}p {yields} {gamma}{pi}{sup 0}p reaction and the magnetic dipole moment of the {Delta}{sup +}(1232)

    SciTech Connect

    W.T. Chiang; Marc Vanderhaeghen; S.N. Yang; D. Drechsel

    2004-09-01

    Radiative pion photoproduction in the {Delta}(1232) resonance region is studied with the aim to access the {Delta}{sup +}(1232) magnetic dipole moment. We present a unitary model of the {gamma}p {yields} {gamma}{pi}N ({pi}N) = ({pi}{sup 0}p, {pi}{sup +}n) reactions, where the {pi}N rescattering is included in an on-shell approximation. In this model, the low energy theorem which couples the {gamma}p {yields} {gamma}{pi}N process in the limit of a soft final photon to the {gamma}p {yields} {pi}N process is exactly satisfied. We study the sensitivity of the {gamma}p {yields} {gamma}{pi}{sup 0}p process at higher values of the final photon energy to the {Delta}{sup +}(1232) magnetic dipole moment. We compare our results with existing data and give predictions for forthcoming measurements of angular and energy distributions. It is found that the photon asymmetry and a helicity cross section are particularly sensitive to the {Delta}{sup +} magnetic dipole moment.

  10. Li production in alpha-alpha reactions. [relation to gamma ray observation

    NASA Technical Reports Server (NTRS)

    Kozlovsky, B.; Ramaty, R.

    1974-01-01

    The cross section for Li-7 production in alpha-alpha reactions is shown to be increased by about a factor of 2 due to the excitation levels of Li-7 and Be-7 at 478 keV and 431 keV, respectively. The cross section for Li-6 production, however, remains the same as calculated on the basis of the detailed balance principle. The lines at 478 keV and 431 keV may link Li-7 production to feasible gamma-ray observations.

  11. 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.

  12. Li production in alpha-alpha reactions. [relation to gamma ray observation

    NASA Technical Reports Server (NTRS)

    Kozlovsky, B.; Ramaty, R.

    1974-01-01

    The cross section for Li-7 production in alpha-alpha reactions is shown to be increased by about a factor of 2 due to the excitation levels of Li-7 and Be-7 at 478 keV and 431 keV, respectively. The cross section for Li-6 production, however, remains the same as calculated on the basis of the detailed balance principle. The lines at 478 keV and 431 keV may link Li-7 production to feasible gamma-ray observations.

  13. Differential cross sections and spin density matrix elements for the reaction gamma p -> p omega

    SciTech Connect

    M. Williams, D. Applegate, M. Bellis, C.A. Meyer

    2009-12-01

    High-statistics differential cross sections and spin density matrix elements for the reaction gamma p -> p omega have been measured using the CLAS at Jefferson Lab for center-of-mass (CM) energies from threshold up to 2.84 GeV. Results are reported in 112 10-MeV wide CM energy bins, each subdivided into cos(theta_CM) bins of width 0.1. These are the most precise and extensive omega photoproduction measurements to date. A number of prominent structures are clearly present in the data. Many of these have not previously been observed due to limited statistics in earlier measurements.

  14. Lewis acid promoted reactions of ethenetricarboxylates with allenes: synthesis of indenes and gamma-lactones via conjugate addition/cyclization reaction.

    PubMed

    Yamazaki, Shoko; Yamamoto, Yuko; Fukushima, Yugo; Takebayashi, Masachika; Ukai, Tetsuma; Mikata, Yuji

    2010-08-06

    Indenes are important core structures in organic chemistry. Few simple arylallenes have been used to construct indene skeletons by Friedel-Crafts reaction. Lewis acid catalyzed reaction of ethenetricarboxylates 1 and arylallenes has been examined in this study. The reaction of arylallenes and ethenetricarboxylate triesters with SnCl(4) gave indene derivatives efficiently, via a conjugate addition/Friedel-Crafts cyclization reaction. On the other hand, the reactions of 1,1-diethyl 2-hydrogen ethenetricarboxylate and arylallenes or alkylallenes with SnCl(4) at -78 degrees C or room temperature and subsequent treatment with Et(3)N gave gamma-lactones. The reactions of triethyl ethenetricarboxylate and 1,1-dialkylallenes with SnCl(4) at room temperature also gave gamma-lactones.

  15. Excitation functions of natGe(p,xn)71,72,73,74 As reactions up to 100 MeV with a focus on the production of 72 As for medical and 73 As for environmental studies.

    PubMed

    Spahn, I; Steyn, G F; Nortier, F M; Coenen, H H; Qaim, S M

    2007-09-01

    Excitation functions for the formation of the arsenic radionuclides (71)As, (72)As, (73)As and (74)As in the interaction of protons with (nat)Ge were measured from the respective threshold energy up to 100 MeV. The conventional stacked-foil technique was used and the needed thin samples were prepared by sedimentation. Irradiations were done at three cyclotrons: CV 28 and injector of COSY at Forschungszentrum Jülich, and Separate Sector Cyclotron at iThemba LABS, Somerset West. The radioactivity was measured via high-resolution gamma-ray spectrometry. The measured cross section data were compared with the literature data as well as with the nuclear model calculations. In both cases, the results generally agree but there are discrepancies in some areas, the results of nuclear model calculation and some of the literature data being somewhat higher than our data. The integral yields of the four radionuclides were calculated from the measured excitation functions. The beta(+) emitting nuclide (72)As (T(1/2)=26.01 h) can be produced with reasonable radionuclidic purity ((71)As impurity: <10%) over the energy range E(p) = 18-->8 MeV; the yield of 93 MBq/microAh is, however, low. The radionuclide (73)As (T(1/2)=80.30 d), a potentially useful indicator in environmental studies, could be produced with good radionuclidic purity ((74)As impurity: <11%) over the energy range E(p) = 30 --> 18 MeV, provided, a decay time of about 60 days is allowed. Its yield would then correspond to 2.4 MBq/microAh, and GBq amounts could be produced when using a high current target.

  16. Search for $\\Theta^{++}$ Pentaquarks in the Exclusive Reaction $\\gamma p\\to K^+K^-p$

    SciTech Connect

    V. Kubarovsky; Marco Battaglieri; Raffaella De Vita; John Goett; Lei Guo; Gordon Mutchler; Paul Stoler; Dennis Weygand; Pawel Ambrozewicz; Marco Anghinolfi; Gegham Asryan; Harutyun AVAKIAN; Harutyun Avakian; H. Bagdasaryan; Nathan Baillie; Jacques Ball; Nathan Baltzell; V. Batourine; Ivan Bedlinski; Ivan Bedlinskiy; Matthew Bellis; Nawal Benmouna; Barry Berman; Angela Biselli; Sylvain Bouchigny; Sergey Boyarinov; Robert Bradford; Derek Branford; William Briscoe; William Brooks; Stephen Bueltmann; Volker Burkert; Cornel Butuceanu; John Calarco; Sharon Careccia; Daniel Carman; Shifeng Chen; Eric Clinton; Philip Cole; Patrick Collins; Philip Coltharp; Donald Crabb; Hall Crannell; Volker Crede; John Cummings; Rita De Masi; Daniel Dale; Enzo De Sanctis; Pavel Degtiarenko; Alexandre Deur; Kahanawita Dharmawardane; Chaden Djalali; Gail Dodge; Joseph Donnelly; David Doughty; Michael Dugger; Oleksandr Dzyubak; Hovanes Egiyan; Kim Egiyan; Latifa Elouadrhiri; Paul Eugenio; Gleb Fedotov; Herbert Funsten; Marianna Gabrielyan; Liping Gan; Michel Garcon; Ashot Gasparian; Gagik Gavalian; Gerard Gilfoyle; Kevin Giovanetti; Francois-Xavier Girod; Oleksandr Glamazdin; John Goetz; Evgueni Golovatch; Atilla Gonenc; Christopher Gordon; Ralf Gothe; Keith Griffioen; Michel Guidal; Nevzat Guler; Vardan Gyurjyan; Cynthia Hadjidakis; Kawtar Hafidi; Rafael Hakobyan; John Hardie; F. Hersman; Kenneth Hicks; Ishaq Hleiqawi; Maurik Holtrop; Charles Hyde-Wright; Yordanka Ilieva; David Ireland; Boris Ishkhanov; Eugeny Isupov; Mark Ito; David Jenkins; Hyon-Suk Jo; Kyungseon Joo; Henry Juengst; James Kellie; Mahbubul Khandaker; Wooyoung Kim; Franz Klein; Friedrich Klein; Alexei Klimenko; Mikhail Kossov; Laird Kramer; Joachim Kuhn; Sebastian Kuhn; Sergey Kuleshov; Jeff Lachniet; Jean Laget; Jorn Langheinrich; David Lawrence; Tsung-shung Lee; Ji Li; Kenneth Livingston; Hai-jiang Lu; Marion MacCormick; Nikolai Markov; Bryan McKinnon; Bernhard Mecking; Joseph Melone; Mac Mestayer; Curtis Meyer; Tsutomu Mibe; Konstantin Mikhaylov; Ralph Minehart; Marco Mirazita; Rory Miskimen; Vasiliy Mochalov; Viktor Mokeev; Ludyvine Morand; Steven Morrow; Maryam Moteabbed; Pawel Nadel-Turonski; Itaru Nakagawa; Rakhsha Nasseripour; Silvia Niccolai; Gabriel Niculescu; Maria-Ioana Niculescu; Bogdan Niczyporuk; Megh Niroula; Rustam Niyazov; Mina Nozar; Mikhail Osipenko; Alexander Ostrovidov; Kijun Park; Evgueni Pasyuk; Craig Paterson; Joshua Pierce; Nikolay Pivnyuk; Dinko Pocanic; Oleg Pogorelko; Sergey Pozdnyakov; John Price; Yelena Prok; Dan Protopopescu; Brian Raue; Gregory Riccardi; Giovanni Ricco; Marco Ripani; Barry Ritchie; Federico Ronchetti; Guenther Rosner; Patrizia Rossi; Franck Sabatie; Carlos Salgado; Joseph Santoro; Vladimir Sapunenko; Reinhard Schumacher; Vladimir Serov; Youri Sharabian; Nikolay Shvedunov; Elton Smith; Lee Smith; Daniel Sober; Aleksey Stavinskiy; Samuel Stepanyan; Stepan Stepanyan; Burnham Stokes; Igor Strakovski; Steffen Strauch; Mauro Taiuti; David Tedeschi; Aram Teymurazyan; Ulrike Thoma; Avtandil Tkabladze; Svyatoslav Tkachenko; Luminita Todor; Clarisse Tur; Maurizio Ungaro; Michael Vineyard; Alexander Vlassov; Lawrence Weinstein; Michael Williams; Elliott Wolin; Michael Wood; Amrit Yegneswaran; Lorenzo Zana; Jixie Zhang; Bo Zhao

    2006-04-28

    The reaction {gamma}p {yields} K{sup +}K{sup -}p was studied at Jefferson Lab with photon energies from 1.8 to 3.8 GeV using a tagged photon beam. The goal was to search for a {Theta}{sup ++} pentaquark, a narrow doubly charged baryon state having strangeness S = +1 and isospin I = 1, in the pK{sup +} invariant mass spectrum. No statistically significant evidence of a {Theta}{sup ++} was found. Upper limits on the total and differential production cross section for the reaction {gamma}p {yields} K{sup -}{Theta}{sup ++} were obtained in the mass range from 1.5 to 2.0 GeV/c{sup 2}, with an upper limit of about 0.15 nb, 95% C.L. for a narrow resonance with a mass M{sub {Theta}{sup ++}} = 1.54 GeV/c{sup 2}. This result places a very stringent upper limit on the {Theta}{sup ++} width.

  17. Measurement of proton polarization in the d({gamma},p)n reaction

    SciTech Connect

    Geesaman, D.F.; Jackson, H.E.; Jones, C.E.

    1995-08-01

    A proposal was approved by CEBAF PAC7 to measure angular distributions of the proton polarization for the d({gamma},p)n reaction in the GeV region. This proposed measurement will test the validity of extensions of conventional nuclear-physics theories to the higher energy regime. The results of the experiment will further constrain the evidence from SLAC experiments NE8 and NE17 that asymptotic scaling was observed above a photon energy of 1.3 GeV. Photoproton polarization measurements at lower energy indicate that the magnitude of the polarization increases with energy. This is consistent with the observation that polarizations are large in high-energy processes, e.g. A{sub nn} in pp {yields} pp scattering or A{sub y} in pp {yields} {pi}{sup 0}X. However, the polarizations in hadron-hadron scattering are believed to arise from Landshoff mechanisms. The higher energy photoproton experiment will permit the first measurements of polarization for a reaction, {gamma}d {yields} pn, where there are no Landshoff terms. The experiment would make use of a polarimeter installed in either the High Resolution Spectrometer in Hall A or the Short Orbit Spectrometer in Hall C at CEBAF.

  18. (n,xn) cross section measurements for Y-89 foils used as detectors for high energy neutron measurements in the deeply subcritical assembly "QUINTA"

    NASA Astrophysics Data System (ADS)

    Bielewicz, Marcin; Kilim, Stanisław; Strugalska-Gola, Elżbieta; Szuta, Marcin; Wojciechowski, Andrzej; Tyutyunnikov, Sergey; Prokofiev, Alexander; Passoth, Elke

    2017-09-01

    Study of the deep subcritical systems (QUINTA) using relativistic beams is performed within the project "Energy and Transmutation of Radioactive Wastes" (E&T - RAW). The experiment assembly was irradiated by deuteron/proton beam (Dubna NUCLOTRON). We calculated the neutron energy spectrum inside the whole assembly by using threshold energy (n,xn) reactions in yttrium (Y-89) foils. There are almost no experimental cross section data for those reactions. New Y-89(n,xn) cross section measurements were carried out at The Svedberg laboratory (TSL) in Uppsala, Sweden in 2015. In this paper we present preliminary results of those experiments.

  19. The reaction gammap-->pi0gamma'p and the magnetic dipole moment of the Delta+ 1232 resonance.

    PubMed

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

    2002-12-30

    The reaction gammap-->pi(0)gamma'p has been measured with the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI for energies between sqrt[s]=1221-1331 MeV. The cross section's differential in angle and energy have been determined for the photon gamma' in three bins of the excitation energy. This reaction channel provides access to the magnetic dipole moment of the Delta(+)(1232) resonance and, for the first time, a value of mu(Delta(+))=[2.7(+1.0)(-1.3)(stat)+/-1.5(syst)+/-3(theor)]mu(N) has been extracted.

  20. Gamma-ray spectroscopy of 131Sn81 via the (9Be, 8Be γ) reaction

    NASA Astrophysics Data System (ADS)

    Burcher, Sean; Bey, A.; Jones, K.; Ahn, S. H.; Ayres, A.; Schmitt, K. T.; Allmond, J.; Galindo-Urribari, A.; Radford, D. C.; Liang, J. F.; Neseraja, C. D.; Pain, S. D.; Pittman, S. T.; Smith, M. S.; Stracener, D. W.; Varner, R. L.; Bardayan, D. W.; O'Malley, P. D.; Cizewski, J. A.; Howard, M. E.; Manning, B. M.; Garcia Ruiz, R. F.; Kozub, R. L.; Matos, M.; Padilla-Rodal, E.

    2016-09-01

    Nuclear data in the region of the doubly-magic nucleus 132Sn82 is useful for benchmarking nuclear structure theories due to the clean single-particle nature of the nuclear wavefunction near the closed shells. At the Holifield Radioactive Ion Beam Facility (HRIBF) neutron-rich beams in the 132Sn82 region were produced via proton-induced fission of a Uranium-Carbide target. The CLARION array of HPGe detectors was coupled with the HyBall array of CsI detectors to allow for particle-gamma coincidence measurements. The gamma-ray de-excitation of the four lowest lying single-neutron states has been observed for the first time via the (9Be,8Be γ) reaction. The excitation energy of these states have been measured to higher precision than was possible with the previous charged particle measurement. This work was supported in part by the U.S. Department of Energy and the National Science Foundation.

  1. Particle-Gamma Studies of Transitional Gd Nuclei Via Light-Ion Reactions

    NASA Astrophysics Data System (ADS)

    Hughes, R. O.; Ross, T. J.; Beausang, C. W.; Allmond, J. M.; Burke, J. T.; Phair, L.; Angell, C. T.; Basunia, M. S.; Bleuel, D. L.; Casperson, R. J.; Fallon, P.; Hatarik, R.; Munson, J.; Paschalis, S.; Petri, M.; Ressler, J. J.; Scielzo, N. D.

    2010-11-01

    Gd nuclei with N ˜ 90 are of great interest due to a rapid change from vibrational to rotational character. Numerous experiments that have studied these nuclei were limited to either pure γ-ray or pure charged-particle studies. Recently, a series of experiments have been carried out at the 88-Inch cyclotron at LBNL, which combine relatively high-efficiency γ-ray and charged-particle spectroscopy in the same experiment. A beam of 25 MeV protons was incident on enriched ^154Gd, ^155Gd, ^156Gd and ^158Gd targets. Charged particles from the (p,p'), (p,d), and (p,t) reaction channels were detected using a Si-telescope array (STARS) and the coincident gamma-rays (in ^152-158Gd) were detected using the Liberace HPGe clover array. The relatively high particle-gamma efficiency, precise energy resolution (via the γ rays), and particle-γ angular information provides a precision tool for spectroscopic studies. Preliminary results will be presented. This work was supported in part by the DOE under grant Nos. DE-FG02-05 ER41379 & DE-FG52-06 NA26206 (UR), DE-AC52 07NA27344 (LLNL), DE-AC02 05CH11231 (LBNL).

  2. The {sup 12}C({sup 3}He,p{gamma}){sup 14}N reaction cross section for {gamma}-ray spectroscopy simulation of fusion plasmas

    SciTech Connect

    Proverbio, I.; Nocente, M.; Tardocchi, M.; Gorini, G.; Kiptily, V. G.; Collaboration: JET-EFDA Contributors

    2010-10-15

    High resolution {gamma}-ray spectroscopy measurements were performed in JET ({sup 3}He)D plasmas with high energy ion populations driven by radio-frequency (RF) heating. One of the first reactions investigated was {sup 12}C({sup 3}He,p{gamma}){sup 14}N, which was observed at low {sup 3}He concentrations. In order to interpret the measurements in this work, cross section data for the {sup 12}C({sup 3}He,p{gamma}){sup 14}N reaction are evaluated. Available data for the population of excited states in {sup 14}N up to the eighth level are assessed in the range E{sub 3He}=0-5 MeV. Discrepancies and gaps in the database have been solved by means of interpolations and consistency analysis. The evaluated cross section data are used to predict the intensity ratio of characteristic 2.31 and 1.63 MeV {gamma}-rays.

  3. Gamma ray astronomy and the origin of the light nuclei. [cosmic ray and interstellar gas reactions

    NASA Technical Reports Server (NTRS)

    Reeves, H.

    1978-01-01

    Nuclear reactions induced by the collisions of the protons and alphas of the galactic cosmic ray with heavy nuclei of the interstellar gas are responsible for the continuous production of the light elements lithium, beryllium, and boron in the galaxy. To better than one order of magnitude, the observed ratios of these abundances to hydrogen abundance and the nuclidic abundance ratios between themselves are accounted for by simply considering the effect of fast protons and alphas with a flux and an energy spectrum as observed in galactic cosmic rays, for a period comparable with the life of our galaxy. The role of gamma ray astronomy in solving problems that occur when accurate agreement is sought with increasingly accurate data is discussed.

  4. Gamma-resonance study of the reaction of iron ions with synthetic L-dopa melanin

    SciTech Connect

    Bagirov, R.M.; Stukan, R.A.; Lapina, V.A.; Dontsov, A.E.; Ostrovskii, M.A.

    1986-07-01

    The reaction of Fe/sup 3 +/ and Fe/sup 2 +/ ions with synthetic L-dopa melanin, which is a model compound of natural melanin (the melanoprotein granules in the pigment epithelial cells in vertebrate and human eyes), has been studied by gamma-resonance spectroscopy. The investigations showed that L-dopa melanin is capable of effectively binding iron ions and that it displays oxidative or reducing properties with respect to Fe, depending on the composition of the subsystem of the Fe ions and the ambient pH. Trivalent Fe/sup 3 +/ ions form stronger complexes with L-dopa melanin than do Fe/sup 2 +/ ions. The coordination takes place mainly with the carboxyl groups and the amino and imino groups of the polymer. The conformational state of the polymer apparently changes as the pH is varied.

  5. Measurement and analysis of the pp{yields}pp{gamma} reaction at 310 MeV

    SciTech Connect

    Johansson, A.; Haberzettl, H.; Nakayama, K.; Wilkin, C.

    2011-05-15

    The pp{yields}pp{gamma} reaction has been studied at a beam energy of 310 MeV by detecting both final protons at the PROMICE-WASA facility and identifying the photon through the resulting missing-mass peak. The photon angular distribution in the center-of-mass system and those of the proton-proton relative momentum with respect to the beam direction and to that of the recoil photon were determined reliably up to a final pp excitation energy of E{sub pp}{approx}30 MeV. Except for very small E{sub pp} values, the behavior of these distributions with excitation energy is well reproduced by a new refined model of the hard bremsstrahlung process. The model reproduces absolutely the total cross section and its energy dependence to within the experimental and theoretical uncertainties.

  6. Induced Polarization in the 2H(gamma,n)p Reaction at Low Energy

    SciTech Connect

    Rocco Schiavilla

    2005-05-01

    The induced polarization, P{prime}{sub y}, of the neutron in the deuteron photo-disintegration from threshold up to 30 MeV is calculated using a variety of different, latest-generation potentials--Argonne v{sub 18}, Bonn 2000, and Nijmegen I--and a realistic model for the nuclear electromagnetic current operator, including one- and two-body terms. The model dependence of the theoretical predictions is found to be very small. These predictions are systematically larger in magnitude than the measured P{prime}{sub y} values, and corroborate the conclusions of an earlier, and much older, study. There is considerable scatter in the available experimental data. New and more accurate measurements of the induced polarization in the {sup 2}H({gamma},{rvec n}){sup 1}H reaction are needed in order to establish unequivocally whether there is a discrepancy between theory and experiment.

  7. A study of non-elastic reaction rates for the ADS materials in the environment of spallation neutrons produced by 1.6 GeV d-beam.

    PubMed

    Bhatia, Chitra; Adam, J; Kumar, V; Katovsky, K; Majerle, M; Solnyshkin, A A; Tsoupko-Sitnikov, V M

    2012-07-01

    For the design and modeling of Accelerator Driven sub-critical System (ADS) a detailed study of response of ADS materials to the spallation neutrons is required. For this purpose reaction rates of different reactions like (n, xn) and (n, xnyp) in 209Bi, natMo, 56Fe, natNi, 55Mn, natTi and natCo materials are determined in an experiment conducted at Nuclotron of JINR, Dubna, using 1.6 GeV d-beam in the 'Energy+Transmutation' set-up. Reaction rates of various (n, xn) and (n, xnyp) reactions are studied in these samples. Results of reaction rates deduced from all the gamma peaks observed in case of 209Bi (n, xn) reactions with x=3-9, natMo (n, γ), (n, 3n), (n, 6n), 56Fe (n, p), (n, p2n), (n, p4n), natNi (n, 2n), (n, 3n), (n, p), (n, d), (n, t), 55Mn (n, γ), (n, 2n), (n, 4n), natTi (n, p), (n, d), (n, t) and natCo (n, γ), (n, xn) reactions with x=2-5 along with (n, p), (n, 2p2n), (n, 2p4n) and (n, 2p6n) are presented. The measured reaction rates for all the elements show good consistency for all the reaction channels and all observed Eγ's of the product nucleus. For all the above mentioned reactions, both experimental as well as theoretical spectrum average cross-sections (σsp.av.cs) are deduced and compared. A close agreement is found between the experimental σsp.av.cs and theoretical σsp.av.cs values. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Geant4 simulations of the Gamma Reaction History Diagnostic at the NIF, Omega and HIGS calibration facility

    NASA Astrophysics Data System (ADS)

    Rubery, Michael; Horsfield, Colin; Herrmann, Hans; Kim, Yong Ho; Mack, Joseph; Young, Carlton; Caldwell, Steven; Evans, Scott; Sedillo, Tom; McEvoy, Aaron; Miller, Kirk; Stoeffl, Wolfgang; Ali, Zaheer; Grafil, Elliott

    2010-11-01

    This paper discusses the development of a Geant4 model of the Gamma Reaction History (GRH) diagnostic at NIF and Omega, Inertial Confinement Fusion (ICF) laser facilities. The GRH diagnostic has been developed to measure bang-time and burn-width parameters for ICF implosions at both facilities, further investigations have also shown that measurements, such as ablator aerial density and ion temperature, may also be possible. Absolute gamma calibration experiments have been performed at the High Intensity Gamma Source (HIGS) facility at Duke University to increase confidence in parameters supplied by simulation for the use in calculations at both laser facilities. A comparison between HIGS data, Geant4 and the ITS ACCEPT code will be presented along with other important GRH properties, such as temporal unit response function, peak-timing shift and Cherenkov production profile, all as a function of pressure and incident gamma energy.

  9. Witnessing quantum discord in 2xN systems

    SciTech Connect

    Bylicka, Bogna; Chruscinski, Dariusz

    2010-06-15

    Bipartite states with vanishing quantum discord are necessarily separable and hence positive partial transpose (PPT). We show that 2xN states satisfy additional property: the positivity of their partial transposition is recognized with respect to the canonical factorization of the original density operator. We call such states strong PPT (SPPT). Therefore, we provide a natural witness for a quantum discord: if a 2xN state is not SPPT it must contain nonclassical correlations measured by quantum discord. It is an analog of the celebrated Peres-Horodecki criterion: if a state is not PPT it must be entangled.

  10. Photon Beam Asymmetry Measurement from the gamma n -> K+ Sigma- Reaction

    NASA Astrophysics Data System (ADS)

    Munevar Espitia, Edwin

    Strangeness channels are important in the experimental search for missing baryon resonances. Phenomenological reaction models for the extraction of resonance parameters, such as coupled-channels analyses, require data for many observables, in different channels, and on different targets. The analysis presented in this thesis is the first measurement of the beam asymmetry over a wide range in the kaon azimuthal center-of-mass angle (which is essential for accessing the s-channel contribution) for the exclusive gamma n → K+ Sigma-- reaction, using the deuteron as a quasi-free neutron target. The data used were from the CLAS g13b run period (experiment E06-103) at Jefferson Lab, which used linearly polarized tagged real photons with energies between 1.1 and 2.3 GeV. Results are shown for two photon-energy bins: 1.9-2.1 and 2.1-2.3 GeV. They agree well (within uncertainties) with the beam asymmetries obtained at LEPS for forward angles, but show a clear disagreement with the predictions from the current Kaon-MAID over wide range of kaon c.m. angles.

  11. 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.

  12. Relationships between pre-stimulus gamma power and subsequent P300 and reaction time break down in schizophrenia

    PubMed Central

    Reinhart, Robert M.G.; Mathalon, Daniel H.; Roach, Brian J.; Ford, Judith M.

    2010-01-01

    Introduction Little is known about the relationship between gamma-band oscillations prior to the arrival of a target stimulus and subsequent sensory processing and response execution. Although schizophrenia has been associated with abnormalities in gamma-band oscillations, P300, and reaction time (RT), few studies have examined the possible correspondence between these three neurobiological and behavioral markers in schizophrenia. To characterize the relationship between preparatory processes, information processing, and subsequent behavioral performance in schizophrenia, the present study investigated the relationships between pre-stimulus gamma-band power, RT and P300 amplitude. Methods EEG and behavioral data were collected from 18 schizophrenia patients and 21 healthy controls during a conventional auditory oddball task. Results In controls, single-trial pre-stimulus gamma power was positively correlated with RT, and average P300 amplitude was positively correlated with average pre-stimulus gamma power. Discussion We interpret these findings as evidence that gamma power enhancement reflects a state of greater pre-stimulus preparation resulting in fuller evaluation of the target stimulus and therefore slower RT, as proposed by Jokeit and Makieg (1994). Consistent with previous research, schizophrenia patients exhibited RT slowing and P300 amplitude reductions relative to controls. Importantly, neither RT nor P300 amplitude were related to pre-stimulus gamma power in schizophrenia, suggesting a breakdown in the preparatory brain state critical for stimulus processing and later motor execution. The present findings underscore the behavioral significance of gamma-band responses, and provide an additional link between gamma-band oscillations and information processing abnormalities in schizophrenia. PMID:20816708

  13. Investigation of the surrogate-reaction method via the simultaneous measurement of gamma-emission and fission probabilities

    NASA Astrophysics Data System (ADS)

    Jurado, B.; Marini, P.; Mathieu, L.; Aiche, M.; Czajkowski, S.; Tsekhanovich, I.; Audouin, L.; Boutoux, G.; Denis-Petit, D.; Guttormsen, M.; Kessedjian, G.; Lebois, M.; Méot, V.; Oberstedt, A.; Oberstedt, S.; Roig, O.; Sérot, O.; Tassan-Got, L.; Wilson, J. N.

    2017-09-01

    We present the results of two experiments where we have measured for the first time simultaneously the fission and gamma-decay probabilities induced by different surrogate reactions. In particular, we have investigated the 238U(d,p), 238U(3He,t) and 238U(3He,4He) reactions as surrogates for the neutron-induced n + 238U, n + 237Np and n + 236U reactions, respectively. In the region where gamma emission, neutron emission and fission compete, our results for the fission probabilities agree fairly well with the neutron-induced data, whereas our gamma-decay probabilities are significantly higher than the neutron-induced data. The interpretation of these results is not obvious and is discussed within the framework of the statistical model with preliminary results for calculated spin-parity distributions populated in surrogate reactions. We also present future plans for surrogate-reaction studies in inverse kinematics with radioactive-ion beams at storage rings.

  14. Side feeding patterns and nuclear lifetime determinations by the Doppler shift attenuation method in ({alpha},n{gamma}) reactions

    SciTech Connect

    Mihai, C.; Filipescu, D.; Ivascu, M.; Bucurescu, D.; Cata-Danil, G.; Cata-Danil, I.; Deleanu, D.; Ghita, D.; Glodariu, T.; Marginean, N.; Marginean, R.; Negret, A.; Pascu, S.; Sava, T.; Stroe, L.; Suliman, G.; Zamfir, N. V.; Pasternak, A. A.; Lobach, Yu. N.

    2010-03-15

    {gamma} rays were measured at several angles in both singles and coincidence mode in the {sup 119}Sn({alpha},n{gamma}){sup 122}Te reaction at 15 MeV on a thick target. Lifetimes of excited states in {sup 122}Te were determined from a Monte Carlo Doppler shift attenuation method (DSAM) analysis of the Doppler broadened lines shapes of {gamma} rays de-exciting the levels. A comparison of several deduced lifetimes with recent results obtained with the (n,n{sup '}) reaction allowed us to validate the choice of a parameter used to calculate the contribution of the side feeding times. The ingredients of the DSAM line-shape analysis (stopping power, description of instrumental line shapes, and side feeding evaluation) are presented in some detail. It is concluded that with proper treatment of side feeding, a DSAM line-shape analysis of peaks in singles or coincidence spectra obtained following the ({alpha},n{gamma}) reaction is able to provide rather accurate values for the lifetimes of levels with low and medium spins.

  15. Study of {sup 60}Fe(n,gamma){sup 61}Fe reaction of astrophysical interest via d({sup 60}Fe,pgamma) indirect reaction

    SciTech Connect

    Giron, S.; Hammache, F.; Sereville, N. de; Beaumel, D.; Franchoo, S.; Guillot, J.; Marechal, F.; Matta, A.; Matea, Y.; Perrot, L.; Scarpaci, J. A.; Stefan, I.; Burgunder, J.; Caceres, L.; Clement, E.; De France, G.; Fernandez, B.; Grevy, S.; Raabe, R.; Sorlin, O.

    2010-03-01

    INTEGRAL and RHESSI spacecrafts recently detected the 1.173 and 1.333 MeV gamma-ray lines coming from the {sup 60}Fe-{sup 60}Co-{sup 60}Ni radioactive decay chain. The long lived isotope {sup 60}Fe (T{sub 1/2} = 1.5 10{sup 6}y) is believed to be primarily produced in core-collapse supernovae. However the interpretation of the observations is difficult because of the large uncertainties concerning {sup 59}Fe(n,gamma){sup 60}Fe and {sup 60}Fe(n,gamma){sup 61}Fe cross sections, involved in {sup 60}Fe nucleosynthesis.The direct component of the {sup 60}Fe(n,gamma){sup 61}Fe reaction was studied indirectly via the d({sup 60}Fe,pgamma){sup 61}Fe transfer reaction. The experiment performed in GANIL in spring 2009 will allow to determine the excitation energies of the populated excited states of {sup 61}Fe and for the first time their spectroscopic factors as well as their transfer angular momentum.I will first give an overview of the astrophysical context, then I will describe the experimental setup and finally present some preliminary results of the ongoing analysis.

  16. Absolute cross section for the reaction /sup 3/H(p,. gamma. /sub 0/)/sup 4/He and a review of /sup 4/He(. gamma. , p/sub 0/)/sup 3/H measurements

    SciTech Connect

    Calarco, J.R.; Hanna, S.S.; Chang, C.C.; Diener, E.M.; Kuhlmann, E.; Fisher, G.A.

    1983-08-01

    Accurate differential cross sections have been measured at 90/sup 0/ for the reaction /sup 3/H(p,..gamma..)/sup 4/He at E/sub p/ = 8.34 and 13.6 MeV. Previously published results for both /sup 3/H(p,..gamma..)/sup 4/He and /sup 4/He(..gamma..,p)/sup 3/H are reviewed and compared with the present data. The theoretical implications of the results are briefly discussed.

  17. An Improved Reaction Rate Formulation for Charged-Particle Induced Thermonuclear Reaction of {sup 2}H(d,{gamma}){sup 4}He

    SciTech Connect

    Aziz, Azni Abdul; Yusof, Norhasliza; Idris, Mahirah; Kassim, Hasan Abu

    2011-03-30

    The reaction rate formula utilized in compilations such as the Nuclear Astrophysics Compilation of Reaction Rates (NACRE) uses low energy approximation due to temperatures in stars are in the region of a few keVs. Most nuclear reaction experiments were done in MeV range and the interior temperatures of massive stars are {approx}10{sup 9} K. Hence an improved formulation for calculating the nuclear reaction rate that is applicable to high temperatures is discussed in this work. The exact tunneling probability that is applicable for all energies is obtained by solving the Schroedinger equation. This yields an enhanced expression for the astrophysical S-factor for calculating the thermonuclear reaction rate at high temperature. The thermonuclear reaction rate from this work is applied to the {sup 2}H(d,{gamma}){sup 4}He reaction and is compared with the NACRE compilation. This improved reaction rate can be included in the nuclear reaction network in a Big Bang nucleosynthesis (BBN) code or a stellar nuclear network code.

  18. Measurement and R-matrix analysis of the nitrogen-15(p,gamma0)oxygen-16 reaction cross section

    NASA Astrophysics Data System (ADS)

    Leblanc, Paul James, IV

    2010-12-01

    Along with the p-p chains, the CNO cycle is the main source of energy production inside of stars with masses larger than the sun. The 15 N + p reaction is the first branch point of this cycle, where the (p,alpha) reaction returns material to the CN cycle and the (p,gamma) reaction leads to the NO cycle, and thus plays a role in determining the final energy production of the process and influences the abundances of oxygen isotopes. This project involves obtaining new measurements for the 15N(p,gamma 0)16O reaction. Dominated by two broad resonances at Ep = 338 and 1028 keV [45], measurements of this reaction were performed in the proton energy range from 1800 keV down to 130 keV. Particular attention was paid to the area between the two dominant resonances, along with the low energy region, as these are the most important regions in determining the S(0) extrapolations [48]. To obtain this measurement, article accelerators at both the University of Notre Dame's Nuclear Science Laboratory (NSL) and the Underground Laboratory for Nuclear Astrophysics (LUNA) in Gran Sasso, Italy were used. In both locations, high purity germanium detectors were used to detect gamma-rays from the reaction of around 13 MeV. It was not possible to measure down to energies corresponding to relevant stellar environment temperatures, and so theoretical fits and extrapolations to the data must be made. To this end, the multi-level, multi-channel R-matrix code AZURE was used. The resulting S factor calculations were used to calculate new reaction rates for different temperature values, and gives up to a factor of 2 difference from currently used compilations [4].

  19. From perception to action: phase-locked gamma oscillations correlate with reaction times in a speeded response task

    PubMed Central

    Fründ, Ingo; Busch, Niko A; Schadow, Jeanette; Körner, Ursula; Herrmann, Christoph S

    2007-01-01

    Background Phase-locked gamma oscillations have so far mainly been described in relation to perceptual processes such as sensation, attention or memory matching. Due to its very short latency (≈90 ms) such oscillations are a plausible candidate for very rapid integration of sensory and motor processes. Results We measured EEG in 13 healthy participants in a speeded reaction task. Participants had to press a button as fast as possible whenever a visual stimulus was presented. The stimulus was always identical and did not have to be discriminated from other possible stimuli. In trials in which the participants showed a fast response, a slow negative potential over central electrodes starting approximately 800 ms before the response and highly phase-locked gamma oscillations over central and posterior electrodes between 90 and 140 ms after the stimulus were observed. In trials in which the participants showed a slow response, no slow negative potential was observed and phase-locked gamma oscillations were significantly reduced. Furthermore, for slow response trials the phase-locked gamma oscillations were significantly delayed with respect to fast response trials. Conclusion These results indicate the relevance of phase-locked gamma oscillations for very fast (not necessarily detailed) integration processes. PMID:17439642

  20. Cross sections for proton-induced reactions on Pd isotopes at energies relevant for the {gamma} process

    SciTech Connect

    Dillmann, I.; Coquard, L.; Domingo-Pardo, C.; Kaeppeler, F.; Marganiec, J.; Uberseder, E.; Giesen, U.; Heiske, A.; Feinberg, G.; Hentschel, D.; Hilpp, S.; Leiste, H.; Rauscher, T.; Thielemann, F.-K.

    2011-07-15

    Proton-activation reactions on natural and enriched palladium samples were investigated via the activation technique in the energy range of E{sub p}=2.75-9 MeV, close to the upper end of the respective Gamow window of the {gamma} process. We have determined cross sections for {sup 102}Pd(p, {gamma}){sup 103}Ag, {sup 104}Pd(p, {gamma}){sup 105}Ag, and {sup 105}Pd(p, n){sup 105}Ag, as well as partial cross sections of {sup 104}Pd(p, n){sup 104}Ag{sup g}, {sup 105}Pd(p, {gamma}){sup 106}Ag{sup m}, {sup 106}Pd(p, n){sup 106}Ag{sup m}, and {sup 110}Pd(p, n){sup 110}Ag{sup m} with uncertainties between 3% and 15% for constraining theoretical Hauser-Feshbach rates and for direct use in {gamma}-process calculations.

  1. Measurements of the reaction e/+/e/-/ yielding gamma-gamma at center-of-mass energies in the range 6.2-7.4 GeV

    NASA Technical Reports Server (NTRS)

    Hilger, E.; Beron, B. L.; Carrington, R. L.; Ford, R. L.; Hill, W. T.; Hofstadter, R.; Hughes, E. B.; Liberman, A. D.; Martin, T. W.; Oneill, L. H.

    1977-01-01

    The cross section for the pair-annihilation reaction e(+)e(-) yields gamma-gamma were measured at center-of-mass energies in the range 6.2-7.4 GeV and at production angles close to 90 deg. The experimental apparatus consisted of two identical spectrometers which were set to view the luminous region at SPEAR-II from opposite directions at an azimuthal angle of 45 deg. In each spectrometer there was a NaI(TI) crystal 20 radiation lengths thick and 30 in. in diameter to measure the gamma-ray energies. Annihilation events were detected by an electronic trigger which required only the observation in coincidence of more than 0.2 GeV in each NaI(TI) crystal within + or - 15 nsec of the crossing beams. The observed rates of pair-annihilation events were found to be in agreement with those expected from quantum electrodynamics (QED) at all the center-of-mass energies used.

  2. Measurements of the reaction e/+/e/-/ yielding gamma-gamma at center-of-mass energies in the range 6.2-7.4 GeV

    NASA Technical Reports Server (NTRS)

    Hilger, E.; Beron, B. L.; Carrington, R. L.; Ford, R. L.; Hill, W. T.; Hofstadter, R.; Hughes, E. B.; Liberman, A. D.; Martin, T. W.; Oneill, L. H.

    1977-01-01

    The cross section for the pair-annihilation reaction e(+)e(-) yields gamma-gamma were measured at center-of-mass energies in the range 6.2-7.4 GeV and at production angles close to 90 deg. The experimental apparatus consisted of two identical spectrometers which were set to view the luminous region at SPEAR-II from opposite directions at an azimuthal angle of 45 deg. In each spectrometer there was a NaI(TI) crystal 20 radiation lengths thick and 30 in. in diameter to measure the gamma-ray energies. Annihilation events were detected by an electronic trigger which required only the observation in coincidence of more than 0.2 GeV in each NaI(TI) crystal within + or - 15 nsec of the crossing beams. The observed rates of pair-annihilation events were found to be in agreement with those expected from quantum electrodynamics (QED) at all the center-of-mass energies used.

  3. Heavy-ion reaction mechanisms studied with the spin spectrometer

    SciTech Connect

    Halbert, M.L.

    1983-01-01

    Experimental data and statistical-model calculations for xn and ..cap alpha..xn products of the reaction /sup 20/Ne + /sup 146/Nd at 136 MeV are shown to be in generally good agreement, indicating that equilibrium processes are dominant. Preliminary results on the heavy-ion ejectiles from /sup 19/F + /sup 159/Tb are presented.

  4. Meson-exchange calculation of the d(. gamma. ,p)n reaction in the GeV energy region

    SciTech Connect

    Lee, T.S.H.

    1991-01-01

    We show that a meson-exchange model of the d({gamma},p) reaction can be constructed to reproduce the energy-dependence of the existing data for the differential cross section at 90{degree}. The prediction of the model in the GeV energy region is found to be radically different from the QCD prediction by Brodsky and Hiller. The results will be compared with the new data presented in a companion paper. 12 refs., 4 figs.

  5. Threshold states in 19Ne and the CNO breakout reaction 15O({alpha},{gamma})19Ne

    SciTech Connect

    Tan, W. P.; Goerres, J.; Daly, J.; Couder, M.; Couture, A.; Lee, H. Y.; Stech, E.; Strandberg, E.; Ugalde, C.; Wiescher, M.

    2006-03-13

    The 15O({alpha},{gamma})19Ne reaction is one of the most important breakout reactions for the hot CNO cycles. However, the relevant states in 19Ne at excitation energies of 4-5 MeV have not been well studied. The lifetimes of these states are not known and are only constrained by experimental upper/lower limits. In particular, the accurate knowledge of the {gamma}- and {alpha}- decay widths of the 4.03 MeV state of 19Ne is important, since the resonance strength of this level dominates the reaction rate for the astrophysically relevant temperatures T9 < 0.6. In this work, we employed an improved DSAM approach to obtain lifetime values of this and other states via 17O(3He,n - {gamma})19Ne. For the 4.03 MeV state, the measured excitation energy is 4034.5{+-}0.8 keV and the mean lifetime, measured here for the first time, is 13{sub -6}{sup +9} fs at the confidence level of 1{sigma} and 13{sub -9}{sup +16} fs at the confidence level of 2{sigma}. This result is in excellent agreement with the 9 fs prediction by Langanke, Wiescher, Fowler, and Goerres.

  6. Estimation of DNA damage and repair in tissues of gamma-irradiated animals using the polymerase chain reaction.

    PubMed

    Ploskonosova, I I; Baranov, V I; Gaziev, A I

    1999-11-01

    Damage and repair of DNA isolated from brain and spleen of gamma-irradiated rats were assayed using the polymerase chain reaction (PCR) method. Damage produced by gamma-radiation in DNA in cells of these tissues of exposed animals was shown to block PCR with the Tth polymerase. This blockage was noted as a decrease in the level of amplification of the fragments of a transcribed gene (beta-actin), an inducible gene (p53), and a nontranscribed one (IgE, heavy chain). The most pronounced decrease in the amplification of the gene fragments was observed on the DNA template isolated from rats immediately after their gamma-irradiation. When DNA was isolated 0.5-5.0 h after exposure, the amplification level was restored, no matter what transcription activity the genes possessed. For comparison, we used in PCR in vitro gamma-irradiated DNA as well as DNA templates with UV-damage, 8-oxy-2;-deoxyguanosine (8-O-dG), and apurinic sites (AP-sites). We found that gamma- and UV-irradiated DNA as well as DNA with AP-sites blocked the Tth polymerase in PCR, whereas 8-O-dG did not effect the level of PCR amplification of gene fragments. The observed changes in the level of PCR amplification of genes on the DNA template from tissues of gamma-irradiated animals are due to various radiation-induced lesions capable of blocking the Tth polymerase. The results show that the PCR method can be used for assaying the integral DNA damage and repair in cells from irradiated animals.

  7. Photoelectrochemical etching of InxGa1-xN

    NASA Astrophysics Data System (ADS)

    Hwang, J. M.; Hsieh, J. T.; Ko, C. Y.; Hwang, H. L.; Hung, W. H.

    2000-06-01

    Photoelectrochemical (PEC) etching of InxGa1-xN in the KOH solution under illumination of a Hg-arc lamp is studied. An indium oxide surface layer is formed during PEC etching, which slows down the etching rate. The PEC etch rate of InxGa1-xN is determined by dissolution of indium oxides into the solution. Increase of the solution temperature results in an increase of solubility of indium oxides and thus enhances the PEC etch rate. It is found that stirring the solution can accelerate indium oxides to dissolve into the solution and increase the etch rate. The thick indium oxide layer on the PEC-etched InxGa1-xN surface can be effectively removed by the treatment of using a hot 6N HCl solution. A post-treatment by using a 3.2 M KOH solution can provide a smooth sidewall on the PEC-etched surface for the potential application to laser cavity.

  8. Overview of the gamma reaction history diagnostic for the national ignition facility (NIF)

    SciTech Connect

    Kim, Yong Ho; Evans, Scott C; Herrmann, Hans W; Mack, Joseph M; Young, Carl S; Malone, Robert M; Cox, Brian C; Frogget, Brent C; Kaufman, Morris I; Tunnell, Thomas W; Tibbitts, Aric; Palagi, Martin J

    2010-01-01

    The National Ignition Facility (NIF) has a need for measuring gamma radiation as part of a nuclear diagnostic program. A new gamma-detection diagnostic uses 900 off-axis parabolic mirrors to rel ay Cherenkov light from a volume of pressurized gas. This non imaging optical system has the high-speed detector placed at a stop position with the Cherenkov light delayed until after the prompt gammas have passed through the detector. Because of the wavelength range (250 to 700 nm), the optical element surface finish was a key design constraint. A cluster of four channels (each set to a different gas pressure) will collect the time histories for different energy ranges of gammas.

  9. Overview of the Gamma Reaction History Diagnostic for the National Ignition Facility (NIF)

    SciTech Connect

    Malone, R M; Frogget, B C; Kaufman, M I; Tibbitts, A; Tunnell, T W; Evans, S C; Herrmann, H W; Kim, Y H; Mack, J M; Young, C S; McGillivray, K D; Palagi, M J; Stoeffl, W

    2010-09-01

    The National Ignition Facility (NIF) has a need for measuring gamma radiation as part of a nuclear diagnostic program. A new gamma-detection diagnostic uses 90º off-axis parabolic mirrors to relay Cherenkov light from a volume of pressurized gas. This nonimaging optical system has the high-speed detector placed at a stop position with the Cherenkov light delayed until after the prompt gammas have passed through the detector. Because of the wavelength range (250 to 700 nm), the optical element surface finish was a key design constraint. A cluster of four channels (each set to a different gas pressure) will collect the time histories for different energy ranges of gammas.

  10. Gamma-ray production cross sections in multiple channels for neutron induced reaction on 48Ti for En=1 to 200 MeV

    SciTech Connect

    Dashdorj, D; Mitchell, G E; Garrett, P E; Agvaanluvsan, U; Becker, J A; Bernstein, L A; Chadwick, M B; Devlin, M; Fotiades, N; Kawano, T; Nelson, R O; Younes, W

    2006-07-06

    Prompt {gamma}-ray production cross sections were measured on a {sup 48}Ti sample for incident neutron energies from 1 MeV to 200 MeV. Partial {gamma}-ray cross sections for transitions in {sup 45-48}Ti, {sup 45-48}Sc, and {sup 43-45}Ca were determined. The observation of about 130 transitions from 11 different isotopes in the present work provides a demanding test of reaction model calculations, and is the first study in this mass region to extract partial {gamma}-ray cross sections for many different reaction channels over a wide range of incident neutron energies. The neutrons were produced by the Los Alamos National Laboratory spallation neutron source located at the LANSCE/WNR facility. The prompt-reaction {gamma} rays were detected with the large-scale Compton-suppressed GErmanium Array for Neutron Induced Excitations (GEANIE). Event neutron energies were determined by the time-of-flight technique. The {gamma}-ray excitation functions were converted to partial {gamma}-ray cross sections and then compared with model calculations using the enhanced GNASH reaction code. Compound nuclear, pre-equilibrium emission and direct reaction mechanisms are included. Overall the model calculations of the partial {gamma}-ray cross sections are in good agreement with measured values.

  11. Thermal stability and chemical bonding states of AlO xN y/Si gate stacks revealed by synchrotron radiation photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    He, G.; Toyoda, S.; Shimogaki, Y.; Oshima, M.

    2010-12-01

    Annealing-temperature dependence of the thermal stability and chemical bonding states of AlO xN y/SiO 2/Si gate stacks grown by metalorganic chemical vapor deposition (MOCVD) using new chemistry was investigated by synchrotron radiation photoemission spectroscopy (SRPES). Results have confirmed the formation of the AlN and AlNO compounds in the as-deposited samples. Annealing the AlO xN y samples in N 2 ambient in 600-800 °C promotes the formation of SiO 2 component. Meanwhile, there is no formation of Al-O-Si and Al-Si binding states, suggesting no interdiffusion of Al with the Si substrate. A thermally induced reaction between Si and AlO xN y to form volatile SiO and Al 2O is suggested to be responsible for the full disappearance of the Al component that accompanies annealing at annealing temperature of 1000 °C. The released N due to the breakage of the Al-N bonding will react with the SiO 2 interfacial layer and lead to the formation of the Si 3-N-O/Si 2-N-O components at the top of Si substrate. These results indicate high temperature processing induced evolution of the interfacial chemistry and application range of AlO xN y/Si gate stacks in future CMOS devices.

  12. Cherenkov radiation conversion and collection considerations for a gamma bang time/reaction history diagnostic for the NIF.

    PubMed

    Herrmann, Hans W; Mack, Joseph M; Young, Carlton S; Malone, Robert M; Stoeffl, Wolfgang; Horsfield, Colin J

    2008-10-01

    Bang time and reaction history measurements are fundamental components of diagnosing inertial confinement fusion (ICF) implosions and will be essential contributors to diagnosing attempts at ignition on the National Ignition Facility (NIF). Fusion gammas provide a direct measure of fusion interaction rate without being compromised by Doppler spreading. Gamma-based gas Cherenkov detectors that convert fusion gamma rays to optical Cherenkov photons for collection by fast recording systems have been developed and fielded at Omega. These systems have established their usefulness in illuminating ICF physics in several experimental campaigns. Bang time precision better than 25 ps has been demonstrated, well below the 50 ps accuracy requirement defined by the NIF system design requirements. A comprehensive, validated numerical study of candidate systems is providing essential information needed to make a down selection based on optimization of sensitivity, bandwidth, dynamic range, cost, and NIF logistics. This paper presents basic design considerations arising from the two-step conversion process from gamma rays to relativistic electrons to UV/visible Cherenkov radiation.

  13. Structure of /sup 209/Bi deduced from the /sup 208/Pb(t,2n. gamma. ) reaction

    SciTech Connect

    Maier, K.H.; Nail, T.; Sheline, P.K.

    1983-04-01

    States in /sup 209/Bi were populated with the /sup 208/Pb(t,2n) reaction. Incident triton energies between 11 and 16 MeV were used. Gamma-ray excitation functions, angular distributions, and ..gamma..-..gamma..-time coincidence spectra were measured. Approximately 50 newly-observed ..gamma.. rays have been assigned to transitions in /sup 209/Bi. Previously-unresolved doublets at E/sub x/ = 2600, 3135, and 3154 keV have been identified. A new level at 3270 keV is reported, and the 3197-keV level is verified. /sup 209/Bi level energies are reported with an accuracy of 600 eV or less. A level scheme for E/sub x/<4.14 MeV is presented, including spin-parity assignments. A new M1 transition between the (5/2)/sup +/ and (3/2)/sup +/ members of the ..pi..h/sub 9/2/x3/sup -/ septuplet is reported. The 19 levels belonging to the ..nu..g/sub 9/2/p/sub 1/2/ /sup -1/, ..pi..h/sub 9/2/ are identified.

  14. Partial gamma-ray cross section measurements in 109Ag(n, x n y p gamma) reactions

    SciTech Connect

    Fotiadis, Nikolaos; Devlin, Matthew James; Nelson, Ronald Owen; Carroll, James

    2015-06-02

    We report on absolute partial cross sections for production of discrete γ-rays using 109Ag(n, xnypγ) reactions with x ≤ 7 and y ≤ 1 in a total of 12 reaction channels. The data were taken using the GEANIE spectrometer comprised of 20 high-purity Ge detectors with 20 BGO escape-suppression shields. The broad-spectrum pulsed neutron beam of the Los Alamos Neutron Science Center’s (LANSCE) WNR facility provided neutrons in the energy range from 0.2 to 300 MeV. The time-of- flight technique was used to determine the incident neutron energies. Partial γ-ray cross sections have been measured for a total of 109 transitions and for neutron energies 0.8 MeV< En<300 MeV. An estimate of the population of isomers in the (n, n'), (n, 2n) and (n, 3n) channels was made.

  15. Search for {theta}{sup ++} Pentaquarks in the Exclusive Reaction {gamma}p{yields}K{sup +}K{sup -}p

    SciTech Connect

    Kubarovsky, V.; Battaglieri, M.; Vita, R. De; Anghinolfi, M.; Ricco, G.; Ripani, M.; Taiuti, M.; Goett, J.; Stoler, P.; Cummings, J. P.; Li, Ji; Guo, L.; Weygand, D. P.; Avakian, H.; Boiarinov, S.; Brooks, W. K.; Burkert, V. D.; Degtyarenko, P. V.; Deur, A.; Egiyan, H.

    2006-09-08

    The reaction {gamma}p{yields}pK{sup +}K{sup -} was studied at Jefferson Lab with photon energies from 1.8 to 3.8 GeV using a tagged photon beam. The goal was to search for a {theta}{sup ++} pentaquark, a narrow, doubly charged baryon state having strangeness S=+1 and isospin I=1, in the pK{sup +} invariant mass spectrum. No statistically significant evidence of a {theta}{sup ++} was found. Upper limits on the total and differential cross section for the reaction {gamma}p{yields}K{sup -}{theta}{sup ++} were obtained in the mass range from 1.5 to 2.0 GeV/c{sup 2}, with an upper limit for a narrow resonance with a mass M{sub {theta}{sup ++}}=1.54 GeV/c{sup 2} of about 0.15 nb, 95% C.L.. This result places a stringent upper limit on the {theta}{sup ++} width {gamma}{sub {theta}{sup ++}}<0.1 MeV/c{sup 2}.

  16. Experimental search for the radiative capture reaction d + d {yields} {sup 4}He + {gamma} from the dd{mu} muonic molecule state J = 1

    SciTech Connect

    Baluev, V. V.; Bogdanova, L. N.; Bom, V. R.; Demin, D. L.; Eijk, C. W. E. van; Filchenkov, V. V.; Grafov, N. N.; Grishechkin, S. K.; Gritsaj, K. I.; Konin, A. D.; Mikhailyukov, K. L.; Rudenko, A. I.; Vinogradov, Yu. I.; Volnykh, V. P.; Yukhimchuk, A. A.; Yukhimchuk, S. A.

    2011-07-15

    A search for the muon-catalyzed fusion reaction d + d {yields} {sup 4}He + {gamma} in the dd{mu} muonic molecule was performed using the experimental installation TRITON with BGO detectors for {gamma}-quanta. A high-pressure target filled with deuterium was exposed to the negative muon beam of the JINR Phasotron to detect {gamma}-quanta with the energy 23.8 MeV. An experimental estimation for the yield of radiative deuteron capture from the dd{mu} state J = 1 was obtained at the level of {eta}{sub {gamma}} {<=} 8 Multiplication-Sign 10{sup -7} per fusion.

  17. Lifetime measurements by the Doppler-shift attenuation method in the {sup 115}Sn({alpha},n{gamma}){sup 118}Te reaction

    SciTech Connect

    Mihai, C.; Pasternak, A. A.; Pascu, S.; Filipescu, D.; Ivascu, M.; Bucurescu, D.; Cata-Danil, I.; Deleanu, D.; Ghita, D. G.; Glodariu, T.; Marginean, N.; Marginean, R.; Negret, A.; Sava, T.; Stroe, L.; Suliman, G.; Zamfir, N. V.; Cata-Danil, G.

    2011-05-15

    {gamma} rays were measured at several angles in both singles and coincidence modes in the {sup 115}Sn({alpha},n{gamma}){sup 118}Te reaction at 15 MeV on a thick target. Multipolarities and mixing ratios were determined from the {gamma}-ray angular distribution analysis. Lifetimes of 11 low- and medium-spin excited states in {sup 118}Te were determined from a Monte Carlo Doppler-shift attenuation method analysis of the Doppler broadened line shapes of {gamma} rays deexciting the levels. The results are discussed in comparison with the predictions of the interacting boson model.

  18. In situ calibration of the Gamma Reaction History instrument using reference samples ("pucks") for areal density measurements

    NASA Astrophysics Data System (ADS)

    Hoffman, N. M.; Herrmann, H. W.; Kim, Y. H.; Hsu, H. H.; Horsfield, C. J.; Rubery, M. S.; Wilson, D. C.; Stoeffl, W. W.; Young, C. S.; Mack, J. M.; Miller, E. K.; Grafil, E.; Evans, S. C.; Sedillo, T. J.; Glebov, V. Yu.; Duffy, T.

    2013-11-01

    The introduction of a sample of carbon, for example a disk or "puck", near an imploding DT-filled capsule creates a source of 12C gamma rays that can serve as a reference for calibrating the response of the Gamma Reaction History (GRH) detector [1]. Such calibration is important in the measurement of ablator areal density ⟨ρR⟩abl in plastic-ablator DT-filled capsules at OMEGA [2], by allowing ⟨ρR⟩abl to be inferred as a function of ratios of signals rather than from absolute measurements of signal magnitudes. Systematic uncertainties in signal measurements and detector responses therefore cancel, permitting more accurate measurements of ⟨ρR⟩abl.

  19. Inelastic partial {gamma}-ray cross sections of {sup 150}Sm+n reactions for E{sub n} = 1-15 MeV

    SciTech Connect

    Dashdorj, D.; Kawano, T.; Devlin, M.; Fotiades, N.; Nelson, R. O.; Mitchell, G. E.; Becker, J. A.; Garrett, P. E.; Kunieda, S.

    2011-06-28

    The {sup 150}Sm(n,n'{gamma}) reaction was measured from E{sub n} = 1 to 15 MeV at the Los Alamos Neutron Science Cemter (LANSCE). The {gamma} rays were detected with the Compton-suppressed Germanium Array for Neutron Induced Excitations (GEANIE). Measured {gamma}-ray excitation functions were converted to partial {gamma}-ray cross sections, Twenty four individual {gamma}-rays up to E{sub x} = 1.8 MeV in {sup 150}Sm were measured. Results are compared with enhanced Hauser Feshbach model calculations: the spin distribution in the pre-equilibrium reaction is calculated with the quantum mechanical model of Feshbach, Kerman and Koonin. The particle transmission coefficients were calculated with two different global optical model potential parameter sets. We employed the coupled-channel optical model based on the soft rotor model and with spherical potential.

  20. Cross Sections for the $\\gamma p \\to K^{*0}\\Sigma^+$ Reaction at $E_\\gamma = 1.7 - 3.0$ GeV

    SciTech Connect

    I. Hleiqawi; K. Hicks; D.Carman; T.Mibe

    2007-04-01

    Differential cross sections for the reaction $\\gamma p \\to K^{*0} \\Sigma^+$ are presented at nine bins in photon energy in the range from 1.7 to 3.0 GeV. The \\kstar was detected by its decay products, $K^+\\pi^-$, in the CLAS detector at Jefferson Lab. These data are the first \\kstar photoproduction cross sections ever published over a broad range of angles. Comparison with a theoretical model based on the vector and tensor $K^*$-quark couplings shows good agreement with the data in general, after adjusting the model's two parameters in a fit to our data. Disagreement between the data at forward angles and the global angle-energy fit to the model suggests that the role of scalar $\\kappa$ meson exchange in $t$-channel diagrams should be investigated.

  1. Thulium-169 neutron inelastic scattering cross section measurements via the (169)Tm(n,n'gamma) reaction

    NASA Astrophysics Data System (ADS)

    Ko, Young June

    1999-11-01

    A neutron inelastic scattering study for low-lying states of thulium-169 below 1 MeV has been pursued by the detection of gamma rays from the 169Tm(n,n'γ) reaction. The inelastic level cross sections, which are important to obtain nuclear potential parameters and to understand reaction mechanisms, were obtained in this study. Incident neutrons were generated by bombarding a metallic lithium target with protons from the Lowell Van de Graaff accelerator. A germanium detector was used for gamma-ray observation. Excitation functions were measured from 0.2 to 1 MeV in 50 keV intervals at a scattering angle of 125°. Gamma-ray production cross sections were obtained for 37 observed transitions from 16 levels. Gamma-ray angular distributions from 35° to 135°, in 10° steps were measured at a neutron energy of 750 keV. The angular distributions were fitted with Legendre polynomials of even (up to fourth) order. Neutron inelastic level cross sections were inferred from the excitation functions and the angular distributions. Because cross-section data from previous experimental or theoretical work were not available, no direct comparison with previous work was made. A comparison of the magnitude and behavior of the (n,inelastic) cross section for thulium with those of neighboring odd-A nuclei indicated reasonable agreement. A classical model for angular momentum transfer indicates that states with spin >=/(+) may be excited only through the compound nucleus process, but for states with spin <=/(-) compound nucleus and direct interaction processes may both participate in the excitation.

  2. Application of the BINS superheated drop detector spectrometer to the {sup 9}Be(p,xn) neutron energy spectrum determination

    SciTech Connect

    Di Fulvio, A.; Ciolini, R.; Mirzajani, N.; Romei, C.; D'Errico, F.; Bedogni, R.; Esposito, J.; Zafiropoulos, D.; Colautti, P.

    2013-07-18

    In the framework of TRASCO-BNCT project, a Bubble Interactive Neutron Spectrometer (BINS) device was applied to the characterization of the angle-and energy-differential neutron spectra generated by the {sup 9}Be(p,xn)reaction. The BINS spectrometer uses two superheated emulsion detectors, sequentially operated at different temperatures and thus provides a series of six sharp threshold responses, covering the 0.1-10 MeV neutron energy range. Spectrum unfolding of the data was performed by means of MAXED code. The obtained angle, energy-differential spectra were compared with those measured with a Bonner sphere spectrometer, a silicon telescope spectrometer and literature data.

  3. 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.}

  4. Astrophysical reaction rates for {sup 58,60}Ni(n,{gamma}) from new neutron capture cross section measurements

    SciTech Connect

    Guber, K. H.; Derrien, H.; Leal, L. C.; Arbanas, G.; Wiarda, D.; Koehler, P. E.; Harvey, J. A.

    2010-11-15

    New neutron capture cross sections of {sup 58,60}Ni were measured in the energy range from 100 eV to 600 keV using the Oak Ridge Electron Linear Accelerator. The combination of these new neutron capture data with previous transmission data allowed a resonance analysis up to 900 keV using R-matrix theory. The theoretically determined direct capture cross sections were included in the analyses. From these resonance parameters and the direct capture contribution, new (n,{gamma}) astrophysical reaction rates were determined over the entire energy range needed by the latest stellar models describing the so-called weak s process.

  5. Low-spin structure of {sup 96}Mo studied with the (n,n{sup '}{gamma}) reaction

    SciTech Connect

    Lesher, S. R.; Yates, S. W.; McKay, C. J.; Bandyopadhyay, D.; Boukharouba, N.; Fransen, C.; Orce, J. N.; McEllistrem, M. T.; Mynk, M.

    2007-03-15

    Extensive studies of the low-spin excited states in {sub 42}{sup 96}Mo{sub 54} with the (n,n{sup '}{gamma}) reaction have clarified the level scheme below 3.7 MeV excitation energy and determined detailed information about {sup 96}Mo, including lifetimes from the Doppler-shift attenuation method, branching ratios, and multipole mixing ratios. Also, B(E2) and B(M1) values were determined for many transitions, multiphonon states were identified, and several low-spin states were characterized in terms of collective, mixed-symmetry states.

  6. Nuclear reaction rate uncertainties and the 22Ne( p,gamma)23Na reaction: Classical novae and globular clusters

    NASA Astrophysics Data System (ADS)

    Kelly, Keegan John

    The overall theme of this thesis is the advancement of nuclear astrophysics via the analysis of stellar processes in the presence of varying levels of precision in the available nuclear data. With regard to classical novae, the level of mixing that occurs between the outer layers of the white dwarf core and the solar accreted material in oxygen-neon novae is presently undetermined by stellar models, but the nuclear data relevant to these explosive phenomena are fairly precise. This precision allowed for the identification of a series of elemental ratios indicative of the level of mixing occurring in novae. Direct comparisons of the modelled elemental ratios to observations showed that there is likely to be much less of this mixing than was previously assumed. Thus, our understanding of classical novae was altered via the investigation of the nuclear reactions relevant to this phenomenon. However, this level of experimental precision is rare and large nuclear reaction uncertainties can hinder our understanding of certain astrophysical phenomena. For example, it is commonly believed that uncertainties in the 22Ne(p,g)23Na reaction rate at temperatures relevant to thermally-pulsing asymptotic giant branch stars are largely responsible for our inability to explain the observed sodium-oxygen anti-correlation in globular clusters. With this motivation, resonances in the 22Ne(p,g) 23Na reaction at E_{c.m.} = 458, 417, 178, and 151 keV were measured. The direct-capture contribution was also measured at E_{lab} = 425 keV. It was determined that the 22Ne(p,g)23Na reaction rate in the astrophysically relevant temperature range is dominated by the resonances at 178 and 151 keV and that the total reaction rate is greater than the previously assumed rate by a factor of approximately ˜40 at 0.15 GK. This increased reaction rate impacts the expected nucleosynthesis that occurs in these stars and will shed light onto the origin of this anti-correlation as it is incorporated into

  7. Kinetics of the. gamma. -radiation-initiated reaction of 2-propanol with tri- and hexafluoropropylene

    SciTech Connect

    Zamyslov, R.A.; Shostenko, A.G.; Dobrov, I.V.; Tarasova, N.P.

    1988-02-01

    The initiation of telomerization reactions by ionizing radiation provides good opportunities for studying the kinetics of free radical reactions. The fluoroalcohols and their derivatives prepared using fluoroolefins and aliphatic alcohols find wide practical application. The object of this exercise was to study the reactivity of trifluoropropylene and hexafluoropropylene with 2-propanol. The reaction products were analyzed gas chromatographically.

  8. Performance evaluation of the Sysmex haematology XN modular system.

    PubMed

    Briggs, Carol; Longair, Ian; Kumar, Punamar; Singh, Deepak; Machin, Samuel J

    2012-11-01

    The Sysmex XN haematology instrument performs automatic reflex testing, depending on sample results. A nucleated red blood cell (NRBC) count is provided on all samples. The instrument has a smaller footprint (34%) than previous Sysmex XE analysers. An evaluation comparing all results to the Sysmex XE-2100 and manual microscopic differential and morphology (n=390) was performed followed by a workflow study of 1000 samples to compare speed of operation and number of blood films reviews required from both systems. The new features on the instrument are: (1) white cell and NRBC channel, all samples include the NRBC count; (2) white cell precursor channel: false positive flags for blasts, abnormal lymphocytes and atypical lymphocytes are reduced significantly without a statistical increase of false negatives; (3) low white cell count mode: suggested setting of <0.5×10(9)/l. An extended count is more precise and provides an accurate differential. Fluorescent platelet count is performed in a dedicated channel. If the red cell or platelet size histograms are abnormal or if the platelet count is low, then a fluorescent platelet count is automatically performed. Good correlation with the XE-2100 and manual differential was found and the improved results compared to the reference flow cytometric analysis for platelet counts, especially below 30×10(9)/l (XE-2100, R(2)=0.500; XN, R(2)=0.875). The XN showed reduced sample turnaround time of 10% and reduced number of blood films for examination, 49% less than the XE-2100 without loss of sensitivity with more precise and accurate results on low cell counts.

  9. Kinetic studies on the conformational isomerization reaction of the four diastereomers of beta,gamma-bidentate CrATP.

    PubMed

    Gruys, K J; Gregory, P R; Schuster, S M

    1986-09-01

    The rates of the conformational isomerization reaction of the diastereomers of beta,gamma-bidentate CrATP were studied as a function of pH, buffer concentration, ionic strength, and temperature. The progress of the reaction was monitored by quenching the reaction at various times, and then isolating the individual diastereomers and quantitating the percent of each. This was accomplished using the reverse-phase high-performance liquid chromatography separation technique developed in this laboratory [K. J. Gruys, and S. M. Schuster, Anal. Biochem. 125, 66-73 (1982)]. The rate constants for this isomerization were then determined by obtaining the best computer fit of the data to a reversible binary mechanism (i.e., A in equilibrium B) using interative descent methods. The reaction rate was shown to be dependent on pH, temperature, and ionic strength, but independent of buffer concentration. Keq. constants were independent of all variables except ionic strength. The results from this study are interpreted in terms of a reaction mechanism involving a preequilibrium ionization of the diastereomers followed by a rate-limiting interconversion process.

  10. Particle-gamma studies of Gd isotopes by (p,p'), (p,d) and (p,t) reactions

    NASA Astrophysics Data System (ADS)

    Ross, T. J.; Hughes, R. O.; Beausang, C. W.; Allmond, J. M.; Burke, J. T.; Phair, L. W.; Scielzo, N.; Angell, C. T.; Basunia, M. S.; Bleuel, D. L.; Casperson, R. J.; Fallon, P.; Hatarik, R.; Munson, J.; Paschalis, S.; Petri, M.; Ressler, J. J.

    2010-11-01

    An experiment was conducted using the STARS-LIBERACE array at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory to study Gd isotopes around the N=90 transition region. A 25 MeV proton beam was incident on ^158/155/154Gd targets and used to populate states in ^152-158Gd by (p,p'), (p,d) and (p,t) reactions. This experiment compliments our earlier work on ^156Gd(p,x),[1]. The exit channel is selected by gating on charged particles using the STARS (Silicon Telescope Array for Reaction Studies) array, which also gives the excitation energy of the residual nucleus. Coincident gamma information is obtained using the LIBERACE (LIvermore BErkeley Array for Collaborative Experiments) clover detector array. Particle-gamma coincidence measurements provide a strong tool for probing the residual nucleus, [1]. Preliminary results pertaining to ^158Gd will be presented. [1] J. M. Allmond et al. Phys. Rev. C 81, 064316 (2010) This work is supported in part via DOE grant numbers DE-FG02-05 ER41379 & DE-FG52-06 NA26206(University of Richmond), DE-AC52 07NA27344(LLNL) and DE-AC02 05CH11231(LBNL).

  11. Xanthohumol, a main prenylated chalcone from hops, reduces liver damage and modulates oxidative reaction and apoptosis in hepatitis C virus infected Tupaia belangeri.

    PubMed

    Yang, Mingbo; Li, Na; Li, Fang; Zhu, Qianqian; Liu, Xi; Han, Qunying; Wang, Yawen; Chen, Yanping; Zeng, Xiaoyan; Lv, Yi; Zhang, Pingping; Yang, Cuiling; Liu, Zhengwen

    2013-08-01

    Hepatitis C virus (HCV) infection in Tupaia belangeri (Tupaia) represents an important model of HCV infection. Xanthohumol (XN), a major prenylated chalcone from hops, has various biological activities including hepatopreventive and anti-viral activities. In this study, Tupaias infected with HCV RNA positive serum were used to evaluate the effects of XN on liver damage, oxidative reaction, apoptosis and viral protein expression in liver tissues. The Tupaias inoculated with HCV positive serum had elevated serum aminotransferase levels and inflammation, especially hepatic steatosis, and HCV core protein expression in liver tissue. In the animals inoculated with HCV positive serum, XN significantly decreased aminotransferase levels, histological activity index, hepatic steatosis score and transforming growth factor β1 expression in liver tissue compared with the animals without XN intervention. XN reduced HCV core protein expression in liver tissue compared with those without XN intervention but the difference was not significant. XN significantly decreased malondialdehyde, potentiated superoxide dismutase and glutathione peroxidase, reduced Bax expression, promoted Bcl-xL and inhibited caspase 3 activity in liver tissues compared with the animals without XN intervention. These results indicate that XN may effectively improve hepatic inflammation, steatosis and fibrosis induced by HCV in Tupaias primarily through inhibition of oxidative reaction and regulation of apoptosis and possible suppression of hepatic stellate cell activation. The anti-HCV potential of XN needs further investigation.

  12. Gamma irradiation of human dendritic cells influences proliferation and cytokine profile of T cells in autologous mixed lymphocyte reaction.

    PubMed

    Cao, Meng-De; Chen, Zong-De; Xing, Ying

    2004-01-01

    Dendritic cells (DC) are the most potent antigen-presenting cells (APC); their ability to induce proliferation of T cells in a mixed lymphocyte reaction (MLR) assay is commonly used for the evaluation of their function. It is a general thought that gamma irradiation of APC does not influence their ability to activate T-cell proliferation, but the data from several studies are controversial. To further determine the mechanisms involved in DC-induced T-cell activation in MLR assay, human DC induced from peripheral blood mononuclear cells (PBMC) were gamma-irradiated and determine their effects on the proliferation and cytokine profiles of T cells in an autologous MLR. DC were induced from the PBMC of 11 multiple sclerosis (MS) patients with RMPI 640 medium containing recombinant human GM-CSF (rhGM-CSF; 800 U/ml) and recombinant human IL-4 (rhIL-4; 500 U/ml). DC harvested on day 7 were divided into two equal parts. One part was not irradiated (naive DC); the other was gamma-irradiated at a dose of 30 Gy. Cell surface molecules were analyzed by flow cytometry. T-cell proliferation was determined using a beta-scintillation counter. The levels of IL-2, IL-4, IL-6 and IL-10 in co-culture supernatants were measured by ELISA. The results indicated that gamma irradiation reduced expression of CD86, CD80 and HLA-DR molecules on DC, especially CD86 (P=0.0072). DC, irradiated or non-irradiated, effectively stimulated autologous T-cell proliferation. Compared to naive DC, irradiated DC showed a markedly lower capacity to promote T-cell proliferation (P=0.0073), and strikingly up-regulated secretion of IL-4 (P=0.0145) and IL-2 (P=0.0323) by autologous T cells. No significant differences were noted in IL-6 and IL-10 production between T cells co-cultured with naive DC and irradiated DC (P>0.05). It is concluded that gamma irradiation of DC not only influences the phenotype of DC but also alters their capacity to stimulate the proliferation and the cytokine profiles of autologous T

  13. A Study on Low Spin States in 154Gd Using (p ,p') Reaction

    NASA Astrophysics Data System (ADS)

    Bidaman, Harris; Hadinia, B.; Garrett, P. E.; University of Liverpool Collaboration; Daresbury Laboratory Collaboration; University of Jyväskylä Collaboration; University of Guelph Collaboration

    2016-09-01

    Located at the stability line, the low lying spin states of the 154Gd nucleus were investigated at the University of Jyväskylä accelerator laboratory in Finland using the 154Gd(p ,p' γ) reaction. A proton beam of 12 MeV was used to excite the 154Gd target, with the gamma-rays from the reaction detected with the JUROGAM II array, while the LISA charged-particle spectrometer was used for detection of the inelastically scattered protons. This experiment marked one of the first uses of the LISA spectrometer at Jyväskylä, which enabled the efficient tagging of the proton-emitting reactions, thus helping to distinguish between the (p ,p') and the much more copious (p , xn) channels. By analysing the peaks obtained from the gamma-gamma, and gamma-gamma-proton coincidence matrices, a decay scheme has been built using the RadWare software Escl8r. Experimental methods, new transitions, and future steps will be discussed. Canada Foundation for Innovation, the Natural Sciences and Engineering Research Council of Canada, the National Research Council of Canada and the Canadian Research Chairs program.

  14. Localized surface grafting reactions on carbon nanofibers induced by gamma and e-beam irradiation

    NASA Astrophysics Data System (ADS)

    Evora, M. C.; Araujo, J. R.; Ferreira, E. H. M.; Strohmeier, B. R.; Silva, L. G. A.; Achete, C. A.

    2015-04-01

    Electron beam and gamma-ray irradiation have potential application to modify the carbon fiber nanostructures in order to produce useful defects in the graphitic structure and create reactive sites. In this study, the methodology to functionalize carbon nanofiber (CNF), via a radiation process and using acrylic acid as a source of oxygen functional groups, was investigated. The samples were submitted to a direct grafting radiation process with electron beam and gamma-ray source. Several parameters were changed such as: acrylic acid concentration, radiation dose and percentage of inhibitor necessary to achieve functionalization, with higher percentage of oxygen functional groups on CNF surface, and better dispersion. The better results achieved were when mixing CNF in a solution of acrylic acid with 6% of inhibitor (FeSO4·7H2O) and irradiated at 100 kGy. The samples were characterized by X-ray photoelectron spectroscopy and the surface composition (atomic%) showed a significant increase of oxygen content for the samples after irradiation. Also, the dispersion of the functionalized CNF in water was stable during months which may be a good indication that the functionalization process of CNF via ionizing radiation was successful.

  15. Performance evaluation of the automated nucleated red blood cell enumeration on Sysmex XN analyser.

    PubMed

    Tantanate, C; Klinbua, C

    2015-06-01

    Presence of peripheral blood nucleated red blood cell (NRBC) is associated with pathological conditions and leads to the overestimation of white blood cell count in automated haematology analysers (HA). The authors evaluated NRBC enumeration by a new HA Sysmex XN (XN) to demonstrate the precision and comparability to manual count (MC) at the various NRBC values. Specimens with initially NRBC positive were included. For precision assessment, 8 levels of NRBCs were repeatedly analysed. For comparison study, 234 specimens were analysed by both XN and MC. For precision study, the percentage of coefficient of variation ranged from 14% to 45.6% and 1.2% to 4.4% for MC and XN, respectively. For comparison study between XN and MC, NRBCs ranged from 0% to 612.5%. Regression analysis demonstrated an r(2) of 0.98. The mean bias of 14.1% with 95% limits of agreement between -48.76% and 76.95% was found. The NRBC counts from XN appeared to be more in accordance with MC when the NRBCs were lower than 200% with the concordance rate of 94.2%. The automated NRBC enumeration by XN was precise and could replace the traditional MC, especially for the specimens with NRBCs lower than 200%. © 2014 John Wiley & Sons Ltd.

  16. 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.

  17. [The macrophage disappearance reaction in guinea pigs sensitized with bovine gamma globulin or human scrum albumin (author's transl)].

    PubMed

    Schimke, R; Bernstein, B; Ambrosius, H

    1977-01-01

    The macrophage disappearance reaction (MDR) is a suitable test for detection of cell mediated immunity against bovine gamma globulin (BGG) and human serum albumin (HSA) in guinea pigs. The MDR is a technical simple, good manipulable, and quantifiable test. The optimal test conditions for the antigens BGC and HSA are the following: Peritoneal exudat cells (PEC) were stimulated with paraffin oil. On the 5th day after receiving oil the animals were injected with 80 microgram BGG or 30 microgram HSA i.p. 5 hours later the PEC were harvested and counted. With the MDR it is possible to detect differences with respect to degree of cell-mediated immunity. Supernatants of sensitized lymphocytes produces the MDR too.

  18. Role of high-spin hyperon resonances in the reaction of $\\gamma p \\to K^+ K^+ \\Xi^-$

    SciTech Connect

    J. Ka Shing Man, Yongseok Oh, K. Nakayama

    2011-05-01

    The recent data taken by the CLAS Collaboration at the Thomas Jefferson National Accelerator Facility for the reaction of $\\gamma p \\to K^+ K^+ \\Xi^-$ are reanalyzed within a relativistic meson-exchange model of hadronic interactions. The present model is an extension of the one developed in an earlier work by Nakayama, Oh, and Haberzettl [Phys. Rev. C 74, 035205 (2006)]. In particular, the role of the spin-5/2 and -7/2 hyperon resonances, which were not included in the previous model, is investigated in the present study. It is shown that the contribution of the $\\Sigma(2030)$ hyperon having spin-7/2 and positive parity has a key role to bring the model predictions into a fair agreement with the measured data for the $K^+\\Xi^-$ invariant mass distribution.

  19. Using multi-layered roll bonding and reaction annealing to process gamma-titanium aluminide sheet material

    NASA Astrophysics Data System (ADS)

    Chaudhari, Gajanan Prabhakar

    The process of roll bonding and reaction annealing was used to process gamma-titanium aluminide sheets with a nearly fully lamellar microstructure. Cold roll bonding was employed to bond elemental Al and Ti foils. The bonded sheets were annealed at 600 °C to convert all of the Al into TiAl3. The effect of rolling strain on the reaction kinetics was studied. Accumulative roll bonding was also employed to study the effect of increased rolling strain on the microstructures resulting after annealing. After the first annealing stage, a cold rolling step resulted in a denser microstructure. A second annealing treatment at 1300 °C for 6 h resulted in a microstructure consisting of two phases, gamma and alpha2, along with Kirkendall porosity. Further densification of the sheets was carried out using hot rolling. A final heat treatment at 1400 °C for 0.3 h resulted in nearly fully lamellar microstructure. The porosity evolution was evaluated at different stages of processing. The mechanical properties of the processed sheet were determined and compared with the data available in the literature. The process of bi-metal multi-layer roll bonding was modeled using the equilibrium force balance method (slab method). The effect of anisotropy and strain hardening was included in the model. The effect of different variables such as total reduction, coefficient of friction, roll radius and initial foil thickness ratio, on the thickness fraction of metals in the bonded composite was investigated. The model enables the estimation of the final composition of the roll bonded composite. The results of the model were compared with the experimental results, and good agreement was observed.

  20. Future prospects of nuclear reactions induced by gamma-ray beams at ELI-NP

    NASA Astrophysics Data System (ADS)

    Filipescu, D.; Balabanski, D. L.; Camera, F.; Gheorghe, I.; Ghita, D.; Glodariu, T.; Kaur, J.; Ur, C. A.; Utsunomiya, H.; Varlamov, V. V.

    2017-01-01

    The future prospects of photonuclear reactions studies at the new Extreme Light Infrastructure—Nuclear Physics (ELI-NP) facility are discussed in view of the pursuit of investigating the electromagnetic response of nuclei using γ-ray beams of unprecedented energy resolution and intensity characteristics. We present here the features of the γ-ray beam source, the emerging ELI-NP experimental program involving photonuclear reactions cross section measurements and spectroscopy and angular measurements of γ-rays and neutrons along with the detection arrays currently under implementation.

  1. 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.

  2. Observation of parity nonconservation in the integrated. gamma. spectrum from (n,. gamma. ) reactions in Cl, Br, Cd, Sn, and La nuclei

    SciTech Connect

    Vesna, V.A.; Kolomenskii, E.A.; Lobashev, V.M.; Nazarenko, V.A.; Pirozhkov, A.N.; Smotritskii, L.M.; Sobolev, Y.V.; Titov, N.A.

    1982-09-05

    A P-odd asymmetry has been observed in the emission of ..gamma.. rays upon the capture of polarized thermal neutrons by Cl, Br, and La nuclei. A circular polarization of the ..gamma.. rays has been observed during the capture of unpolarized neutrons by Cl, Br, Sn, and La nuclei.

  3. Determination of the (24)Mg(p,gamma)(25)Al reaction rate at low stellar temperatures

    NASA Astrophysics Data System (ADS)

    Powell, Denise Catherine

    Recent observations of isotopic abundances in the atmospheres of M13 red giant branch stars show an anticorrelation between Al and 24Mg abundances. These correlations are thought to be the result of deep mixing of material from the surface of the star into regions where the temperature is high enough to allow proton captures to take place. Production of Al and destruction of 24Mg depend on the 24Mg( p, γ)25Al reaction rate at stellar temperatures T9 ~ 0.04 (where T9 denotes temperature in units of 109 K). However, the commonly used rate is too low to account for the observations within the present mixing models. There exists an uncertainty in the total width Γ of the ER = 223-keV (Ex = 2485 keV) resonance in the 24Mg(p,γ)25Al reaction which could lead to enhancements in the reaction rate up to a factor of 32 at T9 = 0.04. The main goal of this thesis is to accurately determine the properties of the ER = 223-keV resonance in order to improve the reaction rate estimate for 24Mg(p, γ) 25Al. Resonance strength ωγ-, γ-ray branching ratios Γ γ/Γ, and mean lifetimes τ were determined for the E R = 223- and 419-keV resonances in 24Mg(p, γ) 25Al. These parameters allow for the determination of proton partial widths Γp, γ-ray partial widths Γ γ, and total widths Γ necessary for the calculation of the resonant cross section at Ep < 500 keV. The rate for the 24Mg(p, γ)25Al reaction for temperatures of T9 = 0.02 - 2 was calculated. The reaction rate deviates from the previous estimates by 18% to 45%, and therefore, the total width of the ER = 223-keV resonance does not have a significant influence on the reaction rate. In addition, branching ratios were determined for the 223-, 419-, 1616-, and 1654-keV resonances in 24Mg(p, γ) 25Al, and for the 406-keV resonance in 27Al( p, γ)28Si. Spectroscopic factors were determined from the proton partial widths for the states corresponding to the E R = 223- and 419-keV resonances. Resonance strength values were also

  4. Interferon gamma mRNA quantitative real-time polymerase chain reaction for the diagnosis of latent tuberculosis: a novel interferon gamma release assay.

    PubMed

    Kim, Sunghyun; Kim, Young Keun; Lee, Hyejon; Cho, Jang-Eun; Kim, Hyo Youl; Uh, Young; Kim, Young Mi; Kim, Hyunjung; Cho, Sang-Nae; Jeon, Bo-Young; Lee, Hyeyoung

    2013-01-01

    The interferon gamma (IFN-γ) release assay (IGRA) is widely used as a diagnostic method for latent tuberculosis infection (LTBI). The QuantiFERON-TB Gold and QuantiFERON-TB Gold In-tube (QFT-IT) tests measure plasma IFN-γ levels using enzyme-linked immunosorbent assay (ELISA), and T-SPOT.TB counts IFN-γ-producing cells using enzyme-linked immunosorbent spot assay. IFN-γ mRNA was evaluated as an indicator of IGRA in comparison with QFT-IT IFN-γ ELISA in 46 subjects with active TB and in 73 at low risk for TB. Significant IFN-γ mRNA expression was detected from 30 min and peaked 4 h after stimulation with MTB antigens or mitogen. This was defined as the optimal time point for IFN-γ mRNA real-time polymerase chain reaction (PCR). The sensitivities of IFN-γ mRNA real-time PCR and IFN-γ ELISA were 84.8% (39/46) and 89.1% (41/46), respectively (no significant difference). Although the specificities of IFN-γ ELISA was 4.1% higher than that of IFN-γ mRNA real-time PCR (60.3% versus 56.2%), the difference was not statistically significant. The overall agreement between IFN-γ mRNA real-time PCR and IFN-γ ELISA was 79.8% (kappa = 0.475). Whilst there was no difference in the performance of IFN-γ mRNA real-time PCR and IFN-γ ELISA, IFN-γ mRNA real-time PCR was superior to IFN-γ ELISA in terms of the time required for detection of MTB infection. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. Production cross sections of short-lived silver radionuclides from natPd(p,xn) nuclear processes

    NASA Astrophysics Data System (ADS)

    Khandaker, Mayeen Uddin; Kim, Kwangsoo; Kim, Guinyun

    2012-03-01

    Production cross-sections of short-lived 103Ag, 104mAg and 104gAg radionuclides from proton-induced reactions on natural palladium (Pd) were measured up to 41 MeV by using a stacked-foil activation technique combined with high resolution γ-ray spectrometry. The present results are compared with the available literature values as well as theoretical data calculated by the TALYS and the ALICE-IPPE computer codes. Note that production cross-sections of the 104mAg radionuclide from natPd(p,xn) processes has been measured here for the first time. Physical thick target yields for the investigated radionuclides were deduced from the respective threshold energy to 41 MeV taking into account that the total energy is absorbed in the targets. Measured data of the short-lived 103Ag radionuclide are noteworthy due to its possible applications as a precursor for the indirect production of widely used therapeutic 103Pd radionuclide via natPd(p,xn)103Ag → 103Pd processes. On the other hand, the investigated 104Ag radionuclide finds importance due to its potential use as a diagnostic and positron emission tomography (PET) imaging analogue. Above all, measured data will enrich the literature database leading to various applications in science and technology.

  6. Experimental determination of the {sup 17}O(p,{alpha}){sup 14}N and {sup 17}O(p,{gamma}){sup 18}F reaction rates

    SciTech Connect

    Chafa, A.; Ouichaoui, S.; Tatischeff, V.; Coc, A.; Garrido, F.; Kiener, J.; Lefebvre-Schuhl, A.; Thibaud, J.-P.; Aguer, P.; Barhoumi, S.; Hernanz, M.; Jose, J.; Sereville, N. de

    2007-03-15

    The {sup 17}O(p,{alpha}){sup 14}N and {sup 17}O(p,{gamma}){sup 18}F reactions are of major importance to hydrogen-burning nucleosynthesis in a number of different stellar sites. In particular, {sup 17}O and {sup 18}F nucleosynthesis in classical novae is strongly dependent on the thermonuclear rates of these two reactions. The previously estimated rate for {sup 17}O(p,{alpha}){sup 14}N carries very large uncertainties in the temperature range of classical novae (T=0.01-0.4 GK), whereas a recent measurement has reduced the uncertainty of the {sup 17}O(p,{gamma}){sup 18}F rate. We report on the observation of a previously undiscovered resonance at E{sub c.m.}=183.3 keV in the {sup 17}O(p,{alpha}){sup 14}N reaction, with a measured resonance strength {omega}{gamma}{sub p{alpha}}=(1.6{+-}0.2)x10{sup -3} eV. We studied in the same experiment the {sup 17}O(p,{gamma}){sup 18}F reaction by an activation method, and the resonance strength was found to amount to {omega}{gamma}{sub p{gamma}}=(2.2{+-}0.4)x10{sup -6} eV. The excitation energy of the corresponding level in {sup 18}F was determined to be 5789.8{+-}0.3 keV in a Doppler shift attenuation method measurement, which yielded a value of {tau}<2.6 fs for the level lifetime. The {sup 17}O(p,{alpha}){sup 14}N and {sup 17}O(p,{gamma}){sup 18}F reaction rates were calculated using the measured resonance properties and reconsidering some previous analyses of the contributions of other levels or processes. The {sup 17}O(p,{alpha}){sup 14}N rate is now well established below T=1.5 GK, with uncertainties reduced by orders of magnitude in the temperature range T=0.1-0.4 GK. The uncertainty in the {sup 17}O(p,{gamma}){sup 18}F rate is somewhat larger because of remaining obscurities in the knowledge of the direct capture process. These new resonance properties have important consequences for {sup 17}O nucleosynthesis and {gamma}-ray emission of classical novae.

  7. {sup 48}Ti(n,xnpa{gamma}) reaction cross sections using spallation neutrons for E{sub n} = 1 to 20 MeV

    SciTech Connect

    Dashdorj, D; Mitchell, G E; Garrett, P E; Agvaanluvsan, U; Becker, J A; Bernstein, L A; Cooper, J R; Hoffman, R D; Younes, W; Devlin, N; Fotiades, N; Nelson, R O

    2005-01-06

    {gamma}-ray excitation functions have been measured for the interaction of fast neutrons with {sup 48}Ti (neutron energy from 1 MeV to 250 MeV). The Los Alamos National Laboratory spallation neutron source, at the LANSCE/WNR facility, provided a ''white'' neutron beam which is produced by bombarding a natural W target with a pulsed proton beam. The prompt-reaction {gamma} rays were measured with the large-scale Compton-suppressed Ge spectrometer, GEANIE. Neutron energies were determined by the time-of-flight technique. Excitation functions were converted to partial {gamma}-ray cross sections, taking into account the dead-time correction, the target thickness, the detector efficiency, and neutron flux (monitored with an in-line fission chamber). The data analysis is presented here for neutron energies between 1 to 20 MeV. Partial {gamma}-ray cross sections for transitions in {sup 47,48}Ti, {sup 48}Sc, and {sup 45}Ca have been determined. These results are compared to Hauser-Feshbach predictions calculated using the STAPRE code, which includes compound nuclear and pre-equilibrium emission. The partial cross sections for {gamma} rays, whose discrete {gamma}-ray cascade path leads to the ground state in {sup 48}Ti, {sup 47}Ti, {sup 48}Sc, and {sup 45}Ca have been summed to obtain estimates of the lower limits for reaction cross sections. Partial cross sections for unobserved {gamma}-rays are predicted from the STAPRE code. These lower limits are combined with Hauser-Feshbach calculations to deduce {sup 48}Ti(n,n'){sup 48}Ti, {sup 48}Ti(n,2n){sup 47}Ti, {sup 48}Ti(n,p){sup 48}Sc, and {sup 48}Ti(n,{alpha}){sup 45}Ca reaction channel cross sections.

  8. Production of free amino acids and gamma-aminobutyric acid by autolysis reactions from wheat bran.

    PubMed

    Nogata, Yoichi; Nagamine, Takashi

    2009-02-25

    To find added value for wheat-milling byproduct, an approach for producing free amino acids and gamma-aminobutyric acid (GABA) was examined. Milled whole grain, bran, shorts, red dog, and 60% extracted flour all released amino acids using a water-soaking treatment. Little difference was found in amino acid production yield from whole grain between the soft and hard wheat cultivars investigated. Among the milled fractions, shorts produced the largest amount of total amino acids followed by bran, red dog, and 60% extracted flour in decreasing order. From the byproduct fraction (mixture of bran and shorts), leucine (Leu), arginine (Arg), valine (Val), lysine (Lys), glutamine (Gln), phenylalanine (Phe), isoleucine (Ile), and GABA were produced at 486, 421, 316, 329, 321, 279, 227, and 118 mg/100 g, respectively, in 120 h at 40 degrees C. Optimal pH for the byproduct fraction was 3.5-5.0 for alpha-amino acids and 5.5 for GABA. The production levels rose with increasing temperature up to 40-50 degrees C for alpha-amino acids and up to 40 degrees C for GABA. The yield of all amino acids increased in the experimented period until 120 h except for aspartic acid (Asp) and asparagine (Asn). Thus, wheat-milling byproducts have the potential to become effective materials for developing foods enriched in branched-chain amino acids (BCAA), Arg, Lys, Gln, Phe, and GABA.

  9. Dynamics of deuterium turnover in the human body using 2(1)D(gamma, n) reaction.

    PubMed

    Malik, S R

    1987-01-01

    A rapid non-destructive and sensitive technique is used by which total body water and its rate of turnover (excretion) in human subjects can be easily measured. Subsequently, a simple calculation is made in estimating the total body fat and lean body mass. The measurements are, therefore, expected to shed useful light on the measurement technique as well as on the movement of body water in humans, and this will glean an understanding of physiological laws governing such movements. The method employs the activation of deuterium in water by bremsstrahlung radiations which are produced by stopping 3 MeV electrons in a gold target. The detection of photoneutrons, so obtained in the reaction 2(1)D(gamma, n), is accomplished by the capture of fission fragments in Solid State Nuclear Track Detector (SSNTD) issuing from the 235U(n, f) reaction. These fission events are then automatically counted by a spark counter. Thermal neutrons, required for the 235U fissioning, are obtained by employing a graphite moderator assembly at the core of which water and urine samples are being irradiated. The development of a few basic measurement parameters and their utilization in such measurements are also reported in the paper.

  10. 1H NMR studies of substrate hydrogen exchange reactions catalyzed by L-methionine gamma-lyase.

    PubMed

    Esaki, N; Nakayama, T; Sawada, S; Tanaka, H; Soda, K

    1985-07-16

    Hydrogen exchange reactions of various L-amino acids catalyzed by L-methionine gamma-lyase (EC 4.4.1.11) have been studied. The enzyme catalyzes the rapid exchange of the alpha- and beta-hydrogens of L-methionine and S-methyl-L-cysteine with deuterium from the solvent. The rate of alpha-hydrogen exchange was about 40 times faster than that of the enzymatic elimination reaction of the sulfur-containing amino acids. The enzyme also catalyzes the exchange reaction of alpha- and beta-hydrogens of the following straight-chain L-amino acids which are not susceptible to elimination: norleucine, norvaline, alpha-aminobutyrate, and alanine. The exchange rates of the alpha-hydrogen and the total beta-hydrogens of L-alanine and L-alpha-aminobutyrate with deuterium followed first-order kinetics. For L-norvaline, L-norleucine, S-methyl-L-cysteine, and L-methionine, the rate of alpha-hydrogen exchange followed first-order kinetics, but the rate of total beta-hydrogen exchange decreased due to a primary isotope effect at the alpha-position. One beta-hydrogen of S-methyl-L-cysteine was exchanged faster than the other, although both the beta-hydrogens were exchanged completely with deuterium ultimately. L-Phenylalanine and L-tryptophan slowly underwent alpha-hydrogen exchange. The pro-R hydrogen of glycine was deuterated stereospecifically. None of the following amino acids were susceptible to the enzymatic hydrogen exchange: D isomers of the above amino acids, branched chain L-amino acids, acidic L-amino acids, and basic L-amino acids.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Experimental study and nuclear model calculations of 3He-induced nuclear reactions on zinc

    NASA Astrophysics Data System (ADS)

    Al-Abyad, M.; Mohamed, Gehan Y.; Ditrói, F.; Takács, S.; Tárkányi, F.

    2017-05-01

    Excitation functions of 3He -induced nuclear reactions on natural zinc were measured using the standard stacked-foil technique and high-resolution gamma-ray spectrometry. From their threshold energies up to 27MeV, the cross-sections for natZn (3He, xn) 69Ge, natZn(3He, xnp) 66,67,68Ga, and natZn(3He, x)62,65Zn reactions were measured. The nuclear model codes TALYS-1.6, EMPIRE-3.2 and ALICE-IPPE were used to describe the formation of these products. The present data were compared with the theoretical results and with the available experimental data. Integral yields for some important radioisotopes were determined.

  12. Cross-section measurement of the /sup 3/He(n,. gamma. ) reaction at E/sub n/ = 24. 5 keV

    SciTech Connect

    Wervelman, R.; Abrahams, K.; Stecher-Rasmussen, F. ); Postma, H.; Davids, G.J.; Bots, G.J.C. )

    1989-08-01

    At 24.5-keV neutron energy, the radiative capture of neutrons proceeds with only a few parts per million compared to to the scattering and (n,p) reactions. Nevertheless, the radiative capture is of interest in the study of fusion reactions, which occur in the sun or in fusion reactors. This reaction yields very high energy (20.6-MeV) gamma rays which are outstanding above any background and therefore may be of diagnostic value in fusion reactor research. A cross-section value {sigma}/sub n{gamma}/ (24.5 keV) = 9.2 +- 2.0 {mu}b is obtained, which is in good agreement with the value 12 +- 6 {mu}b from earlier literature.

  13. Low-temperature sequential pulsed chemical vapor deposition of ternary B{sub x}Ga{sub 1-x}N and B{sub x}In{sub 1-x}N thin film alloys

    SciTech Connect

    Haider, Ali E-mail: biyikli@unam.bilkent.edu.tr; Kizir, Seda; Ozgit-Akgun, Cagla; Biyikli, Necmi E-mail: biyikli@unam.bilkent.edu.tr; Okyay, Ali Kemal

    2016-01-15

    In this work, the authors have performed sequential pulsed chemical vapor deposition of ternary B{sub x}Ga{sub 1-x}N and B{sub x}In{sub 1-x}N alloys at a growth temperature of 450 °C. Triethylboron, triethylgallium, trimethylindium, and N{sub 2} or N{sub 2}/H{sub 2} plasma have been utilized as boron, gallium, indium, and nitrogen precursors, respectively. The authors have studied the compositional dependence of structural, optical, and morphological properties of B{sub x}Ga{sub 1-x}N and B{sub x}In{sub 1-x}N ternary thin film alloys. Grazing incidence X-ray diffraction measurements showed that boron incorporation in wurtzite lattice of GaN and InN diminishes the crystallinity of B{sub x}Ga{sub 1-x}N and B{sub x}In{sub 1-x}N sample. Refractive index decreased from 2.24 to 1.65 as the B concentration of B{sub x}Ga{sub 1-x}N increased from 35% to 88%. Similarly, refractive index of B{sub x}In{sub 1-x}N changed from 1.98 to 1.74 for increase in B concentration value from 32% to 87%, respectively. Optical transmission band edge values of the B{sub x}Ga{sub 1-x}N and B{sub x}In{sub 1-x}N films shifted to lower wavelengths with increasing boron content, indicating the tunability of energy band gap with alloy composition. Atomic force microscopy measurements revealed an increase in surface roughness with boron concentration of B{sub x}Ga{sub 1-x}N, while an opposite trend was observed for B{sub x}In{sub 1-x}N thin films.

  14. Partial wave analysis of the reaction {gamma}p{yields}p{omega} and the search for nucleon resonances

    SciTech Connect

    Williams, M.; Applegate, D.; Bellis, M.; Meyer, C. A.; Dey, B; Dickson, R.; Krahn, Z.; McCracken, M. E.; Moriya, K.; Schumacher, R. A.; Adhikari, K. P.; Careccia, S. L.; Dodge, G. E.; Guler, N.; Klein, A.; Mayer, M.; Nepali, C. S.; Niroula, M. R.; Seraydaryan, H.; Tkachenko, S.

    2009-12-15

    An event-based partial wave analysis (PWA) of the reaction {gamma}p{yields}p{omega} has been performed on a high-statistics dataset obtained using the CLAS at Jefferson Lab for center-of-mass energies from threshold up to 2.4 GeV. This analysis benefits from access to the world's first high-precision spin-density matrix element measurements, available to the event-based PWA through the decay distribution of {omega}{yields}{pi}{sup +}{pi}{sup -}{pi}{sup 0}. The data confirm the dominance of the t-channel {pi}{sup 0} exchange amplitude in the forward direction. The dominant resonance contributions are consistent with the previously identified states F{sub 15}(1680) and D{sub 13}(1700) near threshold, as well as the G{sub 17}(2190) at higher energies. Suggestive evidence for the presence of a J{sup P}=5/2{sup +} state around 2 GeV, a ''missing'' state, has also been found. Evidence for other states is inconclusive.

  15. Nuclear Structure of the Closed Subshell Nucleus 90Zr Studied with the (n,n'(gamma)) Reaction

    SciTech Connect

    Garrett, P E; Younes, Y; Becker, J A; Bernstein, L A; Baum, E M; DiPrete, D P; Gatenby, R A; Johnson, E L; McGrath, C A; Yates, S W; Devlin, M; Fotiades, N; Nelson, R O; Brown, B A

    2003-06-12

    States in {sup 90}Zr have been observed with the (n,n{prime}{gamma}) reaction using both spallation and monoenergetic accelerator-produced neutrons. A scheme comprised of 81 levels and 157 transitions was constructed concentrating on levels below 5.6 MeV in excitation energy. Spins have been determined by considering data from all experimental studies performed for {sup 90}Zr. Lifetimes have been deduced using the Doppler-shift attenuation method for many of the states and transition rates have been obtained. A spherical shell-model interpretation in terms of particle-hole excitations assuming a {sup 88}Sr closed core is given. In some cases, enhancements in B(M1) and B(E2) values are observed that cannot be explained by assuming simple particle-hole excitations. Shell-model calculations using an extended f pg-shell model space reproduce the spectrum of excited states very well, and the gross features of the B(M1) and B(E2) transition rates. Transition rates for individual levels show discrepancies between calculations and experimental values.

  16. Search for W and Z bosons in the reaction anti-p p ---> 2 jets + gamma at s**(1/2) = 1.8-TeV

    SciTech Connect

    Acosta, D.; Affolder, Anthony A.; Albrow, M.G.; Ambrose, D.; Amidei, D.; Anikeev, K.; Antos, J.; Apollinari, G.; Arisawa, T.; Artikov, A.; Ashmanskas, W.; Azfar, F.; Azzi-Bacchetta, P.; Bacchetta, N.; Bachacou, H.; Badgett, W.; Barbaro-Galtieri, A.; Barnes, V.E.; Barnett, B.A.; Baroiant, S.; Barone, M.; /Florida U. /UC, Santa Barbara /Fermilab /Pennsylvania U. /Michigan U. /MIT, LNS /Taiwan, Inst. Phys. /Waseda U. /Dubna, JINR /Argonne /Oxford U. /Padua U. /INFN, Padua /LBL, Berkeley /Purdue U. /Johns Hopkins U. /UC, Davis /Frascati /INFN, Pisa /Pisa U. /Pisa, Scuola Normale Superiore

    2005-07-01

    The authors present a study of the dijet invariant mass distribution for the reaction {bar p}p {yields} 2 jets+{gamma} + X, at a center of mass energy of 1.8 TeV, using data collected by the CDF experiment. They compare the data to predictions for the production of a photon with two jets, together with the resonant processes {bar p}p {yields} W/Z + {gamma} + X, in which the W and Z bosons decay hadronically. A fit is made to the dijet invariant mass distribution combining the non-resonant background and resonant processes. They use the result to establish a limit for the inclusive production cross section of W/Z + {gamma} with hadronic decay of the W and Z bosons.

  17. In-beam gamma-ray spectroscopy of states in /sup 197/Au and /sup 199/Au populated by the (t,2n) reaction

    SciTech Connect

    Nail, T.W.

    1982-08-01

    The (t,2n) reaction has been used to study /sup 197/Au and /sup 199/Au. Excitation function, pulsed beam and gamma-gamma coincidence experiments were performed on both nuclei, and gamma-ray angular distributions were measured in /sup 199/Au. Level schemes were constructed for each nucleus. The resulting levels indicate that the systematic trends seen in the lighter odd-mass gold nuclei, for both the positive-parity states and for the negative-partiy band built on the h/sub 11/2/ shell-model orbital, appear to continue in /sup 197/Au; but significant deviations occur in /sup 199/Au. A 6 +- 2 ns isomer was observed in /sup 197/Au. The cluster-vibration coupling model seems to give the best qualitative agreement with the observed levels.

  18. Molecular beam epitaxy of free-standing wurtzite AlxGa1-xN layers

    NASA Astrophysics Data System (ADS)

    Novikov, S. V.; Staddon, C. R.; Martin, R. W.; Kent, A. J.; Foxon, C. T.

    2015-09-01

    Recent developments with group III nitrides present AlxGa1-xN based LEDs as realistic devices for new alternative deep ultra-violet light sources. Because there is a significant difference in the lattice parameters of GaN and AlN, AlxGa1-xN substrates would be preferable to either GaN or AlN for ultraviolet device applications. We have studied the growth of free-standing wurtzite AlxGa1-xN bulk crystals by plasma-assisted molecular beam epitaxy (PA-MBE). Thick wurtzite AlxGa1-xN films were grown by PA-MBE on 2-in. GaAs (111)B substrates and were removed from the GaAs substrate after growth to provide free standing AlxGa1-xN samples. X-ray microanalysis measurements confirm that the AlN fraction is uniform across the wafer and mass spectroscopy measurements show that the composition is also uniform in depth. We have demonstrated that free-standing wurtzite AlxGa1-xN wafers can be achieved by PA-MBE for a wide range of AlN fractions. In order to develop a commercially viable process for the growth of wurtzite AlxGa1-xN substrates, we have used a novel Riber plasma source and have demonstrated growth rates of GaN up to 1.8 μm/h on 2-in. diameter GaAs and sapphire wafers.

  19. 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.

  20. Observation of the chi_c2(2P) meson in the reaction gamma gamma -> D Dbar at BaBar

    SciTech Connect

    Aubert, B.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Battaglia, M.; Brown, D.N.; Hooberman, B.; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G. /UC, Berkeley /Birmingham U. /Ruhr U., Bochum /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UC, Riverside /UC, San Diego /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /Frascati /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /Harvard U. /Heidelberg U. /Humboldt U., Berlin /Imperial Coll., London /Iowa State U. /Iowa State U. /Johns Hopkins U. /Paris U., VI-VII /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Louisville U. /Mainz U., Inst. Kernphys. /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT /McGill U. /INFN, Milan /Milan U. /INFN, Milan /INFN, Milan /Milan U. /Mississippi U. /Montreal U. /Mt. Holyoke Coll. /INFN, Naples /Naples U. /INFN, Naples /INFN, Naples /Naples U. /NIKHEF, Amsterdam /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /INFN, Padua /INFN, Padua /Padua U. /Paris U., VI-VII /Pennsylvania U. /INFN, Perugia /Perugia U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa, Scuola Normale Superiore /INFN, Pisa /Pisa U. /INFN, Pisa /Princeton U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /Rostock U. /Rutherford /DAPNIA, Saclay /SLAC /South Carolina U. /Stanford U., Phys. Dept. /SUNY, Albany /Tel Aviv U. /Tennessee U. /Texas Nuclear Corp., Austin /Texas U., Dallas /INFN, Turin /Turin U. /INFN, Trieste /Trieste U. /Valencia U. /Victoria U. /Warwick U. /Wisconsin U., Madison

    2010-05-26

    A search for the Z(3930) resonance in {gamma}{gamma} production of the D{bar D} system has been performed using a data sample corresponding to an integrated luminosity of 384 fb{sup -1} recorded by the BABAR experiment at the PEP-II asymmetric-energy electron-positron collider. The D{bar D} invariant mass distribution shows clear evidence of the Z(3930) state with a significance of 5.8{sigma}. We determine mass and width values of (3926.7 {+-} 2.7 {+-} 1.1)MeV/c{sup 2} and (21.3 {+-} 6.8 {+-} 3.6)MeV, respectively. A decay angular analysis provides evidence that the Z(3930) is a tensor state with positive parity and C-parity (J{sup PC} = 2{sup ++}); therefore we identify the Z(3930) state as the {chi}{sub c2}(2P) meson. The value of the partial width {Lambda}{sub {gamma}{gamma}} x {Beta}(Z(3930) {yields} D{bar D}) is found to be (0.24 {+-} 0.05 {+-} 0.04) keV.

  1. Reaction rate sensitivity of 44Ti production in massive stars and implications of a thick target yield measurement of 40Ca(alpha,gamma)44Ti

    SciTech Connect

    Hoffman, R D; Sheets, S A; Burke, J T; Scielzo, N D; Rauscher, T; Norman, E B; Tumey, S; Brown, T A; Grant, P G; Hurst, A M; Phair, L; Stoyer, M A; Wooddy, T; Fisker, J L; Bleuel, D

    2010-02-16

    We evaluate two dominant nuclear reaction rates and their uncertainties that affect {sup 44}Ti production in explosive nucleosynthesis. Experimentally we develop thick-target yields for the {sup 40}Ca({alpha},{gamma}){sup 44}Ti reaction at E{sub {alpha}} = 4.13, 4.54, and 5.36 MeV using {gamma}-ray spectroscopy. At the highest beam energy, we also performed an activation measurement which agrees with the thick target result. From the measured yields a stellar reaction rate was developed that is smaller than current statistical-model calculations and recent experimental results, which would suggest lower {sup 44}Ti production in scenarios for the {alpha}-rich freeze out. Special attention has been paid to assessing realistic uncertainties of stellar reaction rates produced from a combination of experimental and theoretical cross sections. With such methods, we also develop a re-evaluation of the {sup 44}Ti({alpha},p){sup 47}V reaction rate. Using these two rates we carry out a sensitivity survey of {sup 44}Ti synthesis in eight expansions representing peak temperature and density conditions drawn from a suite of recent supernova explosion models. Our results suggest that the current uncertainty in these two reaction rates could lead to as large an uncertainty in {sup 44}Ti synthesis as that produced by different treatments of stellar physics.

  2. New astrophysical S factor for the {sup 15}N(p,{gamma}){sup 16}O reaction via the asymptotic normalization coefficient (ANC) method

    SciTech Connect

    Mukhamedzhanov, A. M.; Gagliardi, C. A.; Goldberg, V. Z.; Plunkett, A.; Trache, L.; Tribble, R. E.; Bem, P.; Burjan, V.; Hons, Z.; Kroha, V.; Mrazek, J.; Novak, J.; Piskor, S.; Simeckova, E.; Vesely, F.; Vincour, J.; La Cognata, M.; Pizzone, R. G.; Romano, S.; Spitaleri, C.

    2008-07-15

    The {sup 15}N(p,{gamma}){sup 16}O reaction provides a path from the CN cycle to the CNO bi-cycle and CNO tri-cycle. The measured astrophysical factor for this reaction is dominated by resonant capture through two strong J{sup {pi}}=1{sup -} resonances at E{sub R}=312 and 962 keV and direct capture to the ground state. Asymptotic normalization coefficients (ANCs) for the ground and seven excited states in {sup 16}O were extracted from the comparison of experimental differential cross sections for the {sup 15}N({sup 3}He,d){sup 16}O reaction with distorted-wave Born approximation calculations. Using these ANCs and proton and {alpha} resonance widths determined from an R-matrix fit to the data from the {sup 15}N(p,{alpha}){sup 12}C reaction, we carried out an R-matrix calculation to obtain the astrophysical factor for the {sup 15}N(p,{gamma}){sup 16}O reaction. The results indicate that the direct capture contribution was previously overestimated. We find the astrophysical factor to be S(0)=36.0{+-}6.0 keV b, which is about a factor of 2 lower than the presently accepted value. We conclude that for every 2200{+-}300 cycles of the main CN cycle one CN catalyst is lost due to this reaction.

  3. New reaction rate for {sup 16}O(p,{gamma}){sup 17}F and its influence on the oxygen isotopic ratios in massive AGB stars

    SciTech Connect

    Iliadis, C.; Angulo, C.; Descouvemont, P.; Lugaro, M.; Mohr, P.

    2008-04-15

    The {sup 16}O(p,{gamma}){sup 17}F reaction rate is revisited with special emphasis on the stellar temperature range of T=60-100 MK, important for hot bottom burning in asymptotic giant branch (AGB) stars. We evaluate existing cross-section data that were obtained since 1958 and, if appropriate, correct published data for systematic errors that were not noticed previously, including the effects of coincidence summing and updated effective stopping powers. The data are interpreted by using two different models of nuclear reactions, that is, a potential model and R-matrix theory. A new astrophysical S factor and recommended thermonuclear reaction rates are presented. As a result of our work, the {sup 16}O(p,{gamma}){sup 17}F reaction has now the most precisely known rate involving any target nucleus in the mass A{>=}12 range, with reaction rate errors of about 7% over the entire temperature region of astrophysical interest (T=0.01-2.5 GK). The impact of the present improved reaction rate with its significantly reduced uncertainties on the hot bottom burning in AGB stars is discussed. In contrast to earlier results we find now that there is not clear evidence to date for any stellar grain origin from massive AGB stars.

  4. Comparison of the (p,xn) cross sections from /sup 238/U, /sup 235/U, and /sup 232/Th targets irradiated with 200-MeV protons

    SciTech Connect

    Chu, Y.Y.; Zhou, M.L.

    1982-01-01

    We have measured absolute cross sections for (p,xn) reactions (x ranges from 0 to 8) from /sup 238/U, /sup 235/U, and /sup 232/Th targets irradiated with 200-MeV protons at the Brookhaven AGS Linac injector. Chemical yields were determined by using /sup 239/Np and /sup 233/Pa as tracers. Yield patterns obtained in this work can be compared to the experimental results and theoretical calculations from earlier work, and they are consistent within the framework of intranuclear cascade followed by neutron evaporation and fission competition.

  5. Estimating Reaction Cross Sections from Measured (Gamma)-Ray Yields: The 238U(n,2n) and 239Pu(n,2n) Cross Sections

    SciTech Connect

    Younes, W

    2002-11-18

    A procedure is presented to deduce the reaction-channel cross section from measured partial {gamma}-ray cross sections. In its simplest form, the procedure consists in adding complementary measured and calculated contributions to produce the channel cross section. A matrix formalism is introduced to provide a rigorous framework for this approach. The formalism is illustrated using a fictitious product nucleus with a simple level scheme, and a general algorithm is presented to process any level scheme. In order to circumvent the cumbersome algebra that can arise in the matrix formalism, a more intuitive graphical procedure is introduced to obtain the same reaction cross-section estimate. The features and limitations of the method are discussed, and the technique is applied to extract the {sup 235}U (n,2n) and {sup 239}Pu(n,2n) cross sections from experimental partial {gamma}-ray cross sections, coupled with (enhanced) Hauser-Feshbach calculations.

  6. Nuclear structure of {sup 10}B studied with (e,e{prime}), ({pi},{pi}{prime}) and ({gamma},{pi}) reactions

    SciTech Connect

    Sato, T.; Odagawa, N.; Ohtsubo, H.; Lee, T.S.H.

    1994-05-01

    The authors studied nuclear structure of {sup 10}B using (e,e{prime}),({pi},{pi}{prime}) and ({gamma},{pi}) reactions under the distorted wave impulse approximation (DWIA). For this purpose the off-shell dependence of the amplitude was taken into account in the momentum space DWIA. They used the off-shell elementary amplitude of ({pi},{pi}) and ({gamma},{pi}) by the model of Nozawa, Blankleider and Lee. The first order core polarization effects were incorporated with the p-shell wave functions of Cohen and Kurath and Hauge and Maripuu. It was shown that the core-polarization effects greatly improve the agreement with the experimental data and that the simultaneous study of these reactions is useful to probe the spin structure of p-shell nuclei.

  7. Nb(x)Ti(1-x)N Superconducting-Nanowire Single-Photon Detectors

    NASA Technical Reports Server (NTRS)

    Stem, Jeffrey A.; Farr, William H.; Leduc, Henry G.; Bumble, Bruce

    2008-01-01

    Superconducting-nanowire singlephoton detectors (SNSPDs) in which Nb(x)Ti(1-x)N (where x<1) films serve as the superconducting materials have shown promise as superior alternatives to previously developed SNSPDs in which NbN films serve as the superconducting materials. SNSPDs have potential utility in optical communications and quantum cryptography. Nb(x)Ti(1-x)N is a solid solution of NbN and TiN, and has many properties similar to those of NbN. It has been found to be generally easier to stabilize NbxTi1 xN in the high-superconducting-transitiontemperature phase than it is to so stabilize NbN. In addition, the resistivity and penetration depth of polycrystalline films of Nb(x)Ti(1-x)N have been found to be much smaller than those of films of NbN. These differences have been hypothesized to be attributable to better coupling at grain boundaries within Nb(x)Ti(1-x)N films.

  8. Nb(x)Ti(1-x)N Superconducting-Nanowire Single-Photon Detectors

    NASA Technical Reports Server (NTRS)

    Stern, Jeffrey A.; Farr, William H.; Leduc, Henry G.; Bumble, Bruce

    2008-01-01

    Superconducting-nanowire single-photon detectors (SNSPDs) in which Nb(x)Ti(1-x)N (where x<1) films serve as the superconducting materials have shown promise as superior alternatives to previously developed SNSPDs in which NbN films serve as the superconducting materials. SNSPDs have potential utility in optical communications and quantum cryptography. Nb(x)Ti(1-x)N is a solid solution of NbN and TiN, and has many properties similar to those of NbN. It has been found to be generally easier to stabilize Nb(x)Ti(1-x)N in the high-superconducting-transition temperature phase than it is to so stabilize NbN. In addition, the resistivity and penetration depth of polycrystalline films of Nb(x)Ti(1-x)N have been found to be much smaller than those of films of NbN. These differences have been hypothesized to be attributable to better coupling at grain boundaries within Nb(x)Ti(1-x)N films.

  9. Wurtzite Al xGa 1- xN bulk crystals grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Novikov, S. V.; Staddon, C. R.; Powell, R. E. L.; Akimov, A. V.; Luckert, F.; Edwards, P. R.; Martin, R. W.; Kent, A. J.; Foxon, C. T.

    2011-05-01

    We have studied the growth of wurtzite GaN and Al xGa 1- xN layers and bulk crystals by molecular beam epitaxy (MBE). MBE is normally regarded as an epitaxial technique for the growth of very thin layers with monolayer control of their thickness. However, we have used the MBE technique for bulk crystal growth and have produced 2 in diameter wurtzite Al xGa 1- xN layers up to 10 μm in thickness. Undoped wurtzite Al xGa 1- xN films were grown on GaAs (1 1 1)B substrates by a plasma-assisted molecular beam epitaxy (PA-MBE) method and were removed from the GaAs substrate after the growth. The fact that free-standing ternary Al xGa 1- xN wafers can be grown is very significant for the potential future production of wurtzite Al xGa 1- xN substrates optimized for AlGaN-based device structures.

  10. Multichannel study of the {sup 13}C({alpha},n){sup 16}O and {sup 16}O(n,{gamma}){sup 17}O reactions

    SciTech Connect

    Dufour, M.; Descouvemont, P.

    2005-07-01

    The {sup 13}C({alpha},n){sup 16}O reaction is investigated in a microscopic two-cluster model with an effective interaction recently developed for transfer reactions. The wave functions are defined in the generator coordinate method. The basis includes all {sup 13}C+{alpha} and {sup 16}O+n channels with {sup 13}C and {sup 16}O described in the p shell. Particle-hole excitations in the sd shell are also taken into account in order to include the {sup 16}O(3{sup -})+n channel. The {sup 17}O spectroscopy is in good agreement with experiment. In particular, the width of the astrophysically relevant 1/2{sub 2}{sup +} state is well reproduced ({gamma}=121 keV as compared to the experimental value {gamma}=124{+-}12 keV). The calculation of the {sup 13}C({alpha},n){sup 16}O S factor shows the importance of the 3/2{sub 3}{sup +} resonance, and provides S(0.2 MeV)=2.1x10{sup 6} MeV b, slightly lower than the NACRE recommended value (2.5x10{sup 6} MeV b). The same model is applied to the {sup 16}O(n,{gamma}){sup 17}O radiative-capture reaction at thermal and astrophysical energies.

  11. A microdosimetric study of {sup 10}B(n,{alpha}){sup 7}Li and {sup 157}Gd(n,{gamma}) reactions for neutron capture therapy

    SciTech Connect

    Wang, C.K.C.; Sutton, M.; Evans, T.M.; Laster, B.H.

    1999-01-01

    This paper presents the microdosimetric analysis for the most interesting cell survival experiment recently performed at the Brookhaven National Laboratory (BNL). In this experiment, the cells were first treated with a gadolinium (Gd) labeled tumor-seeking boronated porphyrin (Gd-BOPP) or with BOPP alone, and then irradiated with thermal neutrons. The resulting cell-survival curves indicate that the {sup 157}Gd(n,{gamma}) reactions are very effective in cell killing. The death of a cell treated with Gd-BOPP was attributed to either the {sup 10}B(n,{alpha}){sup 7}Li reactions or the {sup 157}Gd(n,{gamma}) reactions (or both). However, the quantitative relationship between the two types of reaction and the cell-survival fraction was not clear. This paper presents the microdosimetric analysis for the BNL experiment based on the measured experimental parameters, and the results clearly suggest a quantitative relationship between the two types of reaction and the cell survival fraction. The results also suggest new research in gadolinium neutron capture therapy (GdNCT) which may lead to a more practical modality than the boron neutron capture therapy (BNCT) for treating cancers.

  12. A microdosimetric study of {sup 10}B(n,{alpha}){sup 7}Li and {sup 157}Gd(n,{gamma}) reactions for neutron capture therapy

    SciTech Connect

    Wang, C.K.C.; Sutton, M.; Evans, T.M.; Laster, B.H.

    1996-12-31

    This paper presents the microdosimetric analysis for the most interesting cell survival experiment recently performed at the Brookhaven National Laboratory (BNL). In this experiment, the cells were first treated with a gadolinium (Gd) labeled tumor-seeking boronated porphyrin (Gd-BOPP) or with BOPP alone, and then irradiated with thermal neutrons. The resulting cell survival curves indicate that the {sup 157}Gd(n,{gamma}) reactions is very effective in cell killing. The death of a cell treated with GD-BOPP were attributed to either the {sup 10}B(n,{alpha}) {sup 7}Li reactions or the {sup 157}Gd(n,{gamma}) reactions (or both). However, the quantitative relationship between the two types of reaction and the cell survival fraction was not clear. This paper presents the microdosimetric analysis for the BNL experiment based on the measured experimental parameters, and the results clearly suggest a quantitative relationship between the two types of reaction and the cell survival fraction. The results also suggest new research in Gadolinium neutron capture therapy (GDNCT) which may lead to a more practical modality than the boron neutron capture therapy (BNCT) for treating cancers.

  13. Estimation of {sup 237}U Level Density and Radiative Strength Functions from the (n-bar,{gamma}) Reaction

    SciTech Connect

    Sukhovoj, Anatoly M.; Khitrov, Valery A.; Maslov, Vladimir M.

    2009-01-28

    Intensity distribution of the primary {gamma}-transitions following resonance neutron capture in {sup 236}U about the mean value was approximated in different energy intervals of these quanta and neutrons. Extrapolation of the obtained functions to zero registration threshold of {gamma}-transitions allowed independent estimation of the expected level number of both parities for spin values J = 1/2, 3/2 and sum of radiative widths for both electric and magnetic gamma-transitions to levels with excitation energy up to {approx_equal}2.3 MeV.

  14. Gamma Bang Time/Reaction History Diagnostics for the National Ignition Facility (NIF) Using 90-degree Off-axis Parabolic Mirrors

    SciTech Connect

    H.W. Herrmann, R.M. Malone, W. Stoeffl, J.M. Mack, C.S. Young

    2008-06-01

    Gas Cherenkov detectors (GCD) have been used to convert fusion gamma into photons to achieve gamma bang time (GBT) and reaction history measurements. The GCD designed for Omega used Cassegrain reflector optics in order to fit inside a ten-inch manipulator. A novel design for the National Ignition Facility (NIF) using 90º Off-Axis Parabolic (OAP) mirrors will increase light collection efficiency from fusion gammas and achieve minimum time dispersion. The broadband Cherenkov light (from 200 to 800 nm) is relayed into a high-speed detector using three parabolic mirrors. Because light is collected from many source planes throughout the CO2 gas volume, the detector is positioned at the stop position rather than an image position. The stop diameter and its position are independent of the light-generation location along the gas cell. The current design collects light from a 100-mm diameter by 500-mm-long gas volume. Optical ray tracings demonstrate how light can be collected from different angled trajectories of the Compton electrons as they fly through the CO2 gas volume. A cluster of four channels will allow for increased dynamic range as well as different gamma energy threshold sensitivities. 52.70.La, 29.40.Ka, 42.15.Eq, 07.60.-j, 07.85.-m

  15. Selectivity guidelines and a reductive elimination-based model for predicting the stereochemical course of conjugate addition reactions of organocuprates to gamma-alkoxy-alpha,beta-enoates.

    PubMed

    Kireev, Artem S; Manpadi, Madhuri; Kornienko, Alexander

    2006-03-31

    Current models used to predict the stereochemical outcome of organocopper conjugate addition processes focus on the nucleophilic addition step as stereochemistry-determining. Recent kinetic, NMR, kinetic isotope effect, and theoretical density functional studies strongly support the proposal that stereochemical preferences in these processes are dictated by the reductive elimination step, transforming Cu(III) to Cu(I) intermediates. A new model that considers various steric and stereoelectronic factors involved in the transition state of the reductive elimination step is proposed and then used to interpret the results of systematic studies of arylcuprate conjugate addition reactions with cis and trans gamma-alkoxy-alpha,beta-enoates. The results give rise to the following selectivity guidelines for this process. To achieve high anti-addition diastereoselectivities the use of trans esters with a bulky nonalkoxy substituent at the gamma-position is recommended. While stereoelectronics disfavor syn-addition, a judicious choice of properly sized gamma-substituents may lead to the predominant formation of syn-products, especially with cis enoates. However, high syn-selectivities may be achieved by using gamma-amino-alpha,beta-enoates.

  16. Experimental measurements of the 15O(alpha,gamma)19Ne reaction rate and the stability of thermonuclear burning on accreting neutron stars

    SciTech Connect

    Fisker, J; Tan, W; Goerres, J; Wiescher, M; Cooper, R

    2007-05-08

    Neutron stars in close binary star systems often accrete matter from their companion stars. Thermonuclear ignition of the accreted material in the atmosphere of the neutron star leads to a thermonuclear explosion which is observed as an X-ray burst occurring periodically between hours and days depending on the accretion rate. The ignition conditions are characterized by a sensitive interplay between the accretion rate of the fuel supply and its depletion rate by nuclear burning in the hot CNO cycle and the rp-process. For accretion rates close to stable burning the burst ignition therefore depends critically on the hot CNO breakout reaction {sup 15}O({alpha}, {gamma}){sup 19}Ne that regulates the flow between the hot CNO cycle and the rapid proton capture process. Until recently, the {sup 15}O({alpha}, {gamma}){sup 19}Ne reaction rate was not known experimentally and the theoretical estimates carried significant uncertainties. In this paper we perform a parameter study of the uncertainty of this reaction rate and determine the astrophysical consequences of the first measurement of this reaction rate. Our results corroborate earlier predictions and show that theoretically burning remains unstable up to accretion rates near the Eddington limit, in contrast to astronomical observations.

  17. Gamma-ray fast-timing coincidence measurements from the 18O+18O fusion-evaporation reaction using a mixed LaBr3-HPGe array.

    PubMed

    Alharbi, T; Mason, P J R; Regan, P H; Podolyák, Zs; Mărginean, N; Nakhostin, M; Bowry, M; Bucurescu, D; Căta-Danil, G; Căta-Danil, I; Deleanu, D; Filipescu, D; Glodariu, T; Ghiţă, D; Mărginean, R; Mihai, C; Negret, A; Pascu, S; Sava, T; Stroe, L; Suliman, G; Zamfir, N V; Bruce, A M; Rodriguez Triguero, C; Bender, P C; Garg, U; Erduran, M N; Kusoglu, A; Bostan, M; Detistov, P; Alkhomashi, N; Sinha, A K; Chakrabarti, R; Ghugre, S S

    2012-07-01

    We report on a gamma-ray coincidence analysis using a mixed array of hyperpure germanium and cerium-doped lanthanum tri-bromide (LaBr3:Ce) scintillation detectors to study nuclear electromagnetic transition rates in the pico-to-nanosecond time regime in 33,34P and 33S following fusion-evaporation reactions between an 18O beam and an isotopically enriched 18O implanted tantalum target. Energies from decay gamma-rays associated with the reaction residues were measured in event-by-event coincidence mode, with the measured time difference information between the pairs of gamma-rays in each event also recorded using the ultra-fast coincidence timing technique. The experiment used the good full-energy peak resolution of the LaBr3:Ce detectors coupled with their excellent timing responses in order to determine the excited state lifetime associated with the lowest lying, cross-shell, Iπ=4- "intruder" state previously reported in the N=19 isotone 34P. The extracted lifetime is consistent with a mainly single-particle M2 multipolarity associated with a f7/2→d5/2 single particle transition. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. Measurement of activation cross-sections for high-energy neutron-induced reactions of Bi and Pb

    NASA Astrophysics Data System (ADS)

    Zaman, Muhammad; Kim, Guinyun; Kim, Kwangsoo; Naik, Haladhara; Shahid, Muhammad; Lee, Manwoo

    2015-08-01

    The cross-sections for 209Bi(n, 4n)206Bi, 209Bi(n, 5n)205Bi, natPb(n, xn)204mPb, natPb(n, xn)203Pb, natPb(n, xn)202mPb,natPb(n, xn)201Pb, natPb(n, xn)200Pb, natPb(n, αxn)203Hg and natPb(n, p xn)202Tl reactions were determined at the Korean Institute of Radiological and Medical Sciences (KIRAMS), Korea in the neutron energy range of 15.2 to 37.2 MeV. The above cross-sections were obtained by using the activation and off-line γ-ray spectrometric technique. The quasi-monoenergetic neutron used for the above reactions are based on the 9Be(p, n) reaction. Simulations of the spectral flux from the Be target were done using the MCNPX program. The cross-sections were estimated with the TALYS 1.6 code using the default parameter. The data from the present work and literature were compared with the data from the EAF-2010 and the TENDL-2013 libraries, and calculated values of TALYS 1.6 code. It shows that appropriate level density model, the γ-ray strength function, and the spin cut-off parameter are needed to obtain a good agreement between experimental data and theoretical values from TALYS 1.6 code.

  19. Structure of Resonances in the Gamow Burning Window for the {sup 25}Al({rho},{gamma}){sup 26}Si Reaction in Novae

    SciTech Connect

    Doherty, D. T.; Woods, P. J.; Seweryniak, D.; Albers, M.; Ayangeakaa, A. D.; Carpenter, M. P.; Chiara, C. J.; David, H. M.; Harker, J. L.; Janssens, R. V. F.; Kankainen, A.; Lederer, C.; Zhu, S.

    2015-09-17

    A -ray spectroscopy study of excited states in 26Si has been performed using the 24Mg(3He,n) reaction at a beam energy of 10 MeV. In particular, states have been studied above the proton threshold relevant for burning in the 25Al(p, )26Si reaction in novae. This reaction in uences the amount of 26Al injected into the interstellar medium by novae, which contributes to the overall ux of cosmic gamma-ray emission from 26Al observed in satellite missions. The present results point strongly to the existence of a 0+ state at an excitation energy of 5890 keV lying within the Gamow burning window, which raises questions about the existence and properties of another, higher-lying state/resonance reported in previous experimental work. The existence of two such states within this excitation energy region cannot be understood in the framework of sd shell-model calculations.

  20. IgG antibody subclasses, tumor necrosis factor and IFN-gamma levels in patients with type II lepra reaction on thalidomide treatment.

    PubMed

    Partida-Sanchez, S; Favila-Castillo, L; Pedraza-Sanchez, S; Gomez-Melgar, M; Saul, A; Estrada-Parra, S; Estrada-Garcia, I

    1998-05-01

    A group of 9 Mexican lepromatous leprosy patients was studied at the beginning of a type II reaction (erythema nodosum leprosum, ENL) and after 1 or 2 months of thalidomide treatment. ENL patients at the onset of the reaction had slightly higher amounts of anti-Mycobacterium leprae IgG1 and IgG2 antibodies, compared to similar lepromatous patients that did not develop ENL. Neither these antibody levels nor IgM and the other IgG subclasses were importantly modified after thalidomide treatment. Serum TNF was significantly higher in the patients that developed ENL compared to those that did not develop the reaction. TNF levels were slightly decreased after 1 month of thalidomide treatment and significantly decreased after 2 months of treatment. Serum IFN-gamma was significantly lower in patients at the onset of ENL and was increased after 1 and 2 months of thalidomide treatment.

  1. Investigation of giant-dipole-resonance decay in the ({gamma}, n) reactions on {sup 52}Cr and {sup 51}V nuclei

    SciTech Connect

    Verbitsky, S. S.; Lapic, A.M. Ratner, B. S.; Rusakov, A. V.; Tikanov, M. A.; Tulupov, B. A.; Tzelebrovsky, A. N.

    2009-03-15

    The cross sections for the emission of fast neutrons ({epsilon}{sub n} > 3.7 MeV) in the reactions {sup 52}Cr({gamma}, n){sup 51}Cr and {sup 51}V({gamma}, n){sup 50}V at incident-photon energies in the range between 16.0 and 25.8 MeV were studied. The neutron energy spectra were measured at the bremsstrahlung-photon endpoint energies of 18.5, 21.0, and 23.0 MeV for the {sup 52}Cr and {sup 51}V nuclei and at the bremsstrahlung-photon energy of 25.5 MeV for the {sup 51}V nucleus. Special features of giant-dipole-resonance decay that are associated with the existence of a structure in photoneutron cross sections and spectra are discussed.

  2. In-beam gamma-ray spectroscopy of {sup 248,250,252}Cf by neutron-transfer reactions using a Cf target

    SciTech Connect

    Takahashi, R.; Ishii, T.; Asai, M.; Nagae, D.; Makii, H.; Tsukada, K.; Toyoshima, A.; Ishii, Y.; Matsuda, M.; Makishima, A.; Shizuma, T.; Kohno, T.; Ogawa, M.

    2010-05-15

    The ground-state bands of {sup 248,250,252}Cf have been established up to the 10{sup +}, 12{sup +}, and 10{sup +} states, respectively, by in-beam gamma-ray spectroscopy using neutron-transfer reactions with a 153-MeV {sup 18}O beam and a highly radioactive Cf target. The deexcitation gamma rays in {sup 248,250,252}Cf were identified by taking coincidences with outgoing particles of {sup 16-19}O measured with Si DELTAE-E detectors, and by selecting their kinetic energies. Moments of inertia of {sup 248,250,252}Cf were discussed in terms of the N=152 deformed shell gap.

  3. The reaction of glass in a gamma irradiated saturated tuff environment: Part 2, Data package for ATM-1c and ATM-8 glasses

    SciTech Connect

    Bates, J.K.; Gerding, T.J.; Fischer, D.F.; Ebert, W.L.

    1987-11-01

    A series of experiments have been performed in support of the Nevada Nuclear Waste Storage Investigations (NNWSI) project that investigate the efects of gamma radiation on groundwater and glass reaction. Experiments have been done in a gamma radiation field at exposure rates ranging between 2 x 10{sup 5} and 0 R/h, and have been performed over a period of four years. All the data that have been generated during these experiments and which were used in writing the article are presented. The report consists of a series of Tables that provide the (1) groundwater compositions; (2) glass compositions; (3) experimental matrices and selected results; (4) cation analyses; (5) anion analyses; (6) Np and Pu analyses; (7) SEM/EDS analyses; and (8) SIMS analyses exposure rates of 2 x 10{sup 5} (2R), 1 x 10{sup 3} (1R), and 0 (OR) R/h. 2 refs., 7 figs., 16 tabs.

  4. An easy stereoselective access to beta,gamma-aziridino alpha-amino ester derivatives via mannich reaction of benzophenone imines of glycine esters with N-sulfonyl alpha-chloroaldimines.

    PubMed

    Kiss, Loránd; Mangelinckx, Sven; Sillanpää, Reijo; Fülöp, Ferenc; De Kimpe, Norbert

    2007-09-14

    Mannich-type addition of benzophenone imine glycinates across newly synthesized N-(p-toluenesulfonyl) alpha-chloroaldimines afforded gamma-chloro-alpha,beta-diamino ester derivatives with moderate diastereoselectivity as separable mixtures of anti and syn diastereomers. The gamma-chloro-alpha,beta-diamino esters were efficiently cyclized under basic conditions to the corresponding beta,gamma-aziridino alpha-amino ester derivatives, representing a new class of conformationally constrained heterocyclic alpha,beta-diamino acid derivatives. The relative configuration of the aziridines was determined via X-ray diffraction analysis. Mechanisms and intermediate transition states to explain the stereochemical outcome of the Mannich reaction with different substrates or under different conditions are proposed. The synthetic importance of the beta,gamma-aziridino alpha-amino ester derivatives is demonstrated by their conversion into the corresponding Boc-protected derivatives and ring opening reactions to alpha,beta-diamino esters and a gamma-amino alpha,beta-unsaturated amino ester.

  5. Multiplex polymerase chain reaction-based deletion analysis of spontaneous, gamma ray- and alpha-induced hprt mutants of CHO-K1 cells.

    PubMed

    Schwartz, J L; Rotmensch, J; Sun, J; An, J; Xu, Z; Yu, Y; Hsie, A W

    1994-11-01

    Independent Chinese hamster ovary (CHO)-K1 cell mutants at the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus were isolated from untreated, 60Co gamma ray- and 212Bi alpha-exposed cells and the genetic changes underlying the mutation determined by multiplex polymerase chain reaction (PCR)-based exon deletion analysis. In the 71 spontaneous mutants analyzed, 77.5% of the clones showed no change in exon number or size, 15.5% showed a loss of a single exon, 4.2% showed a loss of 2-8 exons, and 2.8% showed loss of all nine hprt exons (total gene deletion). Exposure to 6 Gy of gamma rays, which reduced survival levels to 10%, produced a significantly different deletion spectrum that was shifted toward deletions with 45% of the 20 mutants analyzed showing a loss of a single exon and 30% showing a loss of all nine exons. Exposure to 2 Gy alpha radiation from 212Bi, a 220Rn daughter, a dose which also reduced survival levels to about 10%, resulted in a deletion spectrum similar to the gamma-ray spectrum in that more than 75% of the 49 mutants analyzed were deletions. The alpha spectrum, however, was significantly different from both the spontaneous and gamma spectra with 55.1% of the alpha mutants showing a loss of all nine exons, 10.2% showing loss of a single exon, and 14.3% showing loss of 2-8 exons. Thus, alpha-radiation appears to produce larger intragenic deletions than gamma radiation. The results suggest that intragenic deletion size should be considered when low- and high linear energy transfer (LET) mutation spectra are compared.

  6. Polymerase chain reaction-deletion analysis of spontaneous, gamma ray-, and alpha-induced hprt mutants of CHO-K1 cells.

    SciTech Connect

    Schwartz, J. L.; Rotmensch, J.; Sun, J.; An, J.; Xu, Z.; Yu, Y.; Hsie, A. W.; Center for Mechanistic Biology and Biotechnology; Univ. of Chicago; Univ. of Texas Medical Branch

    1994-01-01

    Independent Chinese hamster ovary (CHO)-K1 cell mutants at the hypoxanthine-guanine phosphoribosyltransferase (hprt) locus were isolated from untreated, {sup 60}Co {gamma} ray-and {sup 212}Bi {alpha}-exposed cells and the genetic changes underlying the mutation determined by multiplex polymerase chain reaction (PCR)-based exon deletion analysis. In the 71 spontaneous mutants analyzed, 77.5% of the clones showed no change in exon number or size, 15.5% showed a loss of a single exon, 4.2% showed a loss of 2-8 exons, and 2.8% showed loss of all nine hprt exons (total gene deletion). Exposure to 6 Gy of {gamma} rays, which reduced survival levels to 10%, produced a significantly different deletion spectrum that was shifted toward deletions with 45% of the 20 mutants analyzed showing a loss of a single exon and 30% showing a loss of all nine exons. Exposure to 2 Gy {alpha} radiation from 212Bi, a 220Rn daughter, a dose which also reduced survival levels to about 10%, resulted in a deletion spectrum similar to the {gamma}-ray spectrum in that more than 75% of the 49 mutants analyzed were deletions. The {alpha} spectrum, however, was significantly different from both the spontaneous and {gamma} spectra with 55.1% of the {alpha} mutants showing a loss of all nine exons, 10.2% showing loss of a single exon, and 14.3% showing loss of 2-8 exons. Thus, {alpha}-radiation appears to produce larger intragenic deletions than {gamma} radiation. The results suggest that intragenic deletion size should be considered when low- and high linear energy transfer (LET) mutation spectra are compared.

  7. Measurement of cross sections for {alpha}-induced reactions on {sup 197}Au and thick-target yields for the ({alpha},{gamma}) process on {sup 64}Zn and {sup 63}Cu

    SciTech Connect

    Basunia, M. S.; Smith, A. R.; Shugart, H. A.; Norman, E. B.

    2007-01-15

    We have measured the cross sections for the {sup 197}Au({alpha},{gamma}){sup 201}Tl and {sup 197}Au({alpha},2n){sup 199}Tl reactions in the 17.9- to 23.9-MeV energy range, and {sup 197}Au({alpha},n){sup 200}Tl reaction in the 13.4- to 23.9-MeV energy range using an activation technique. Thick-target yields for the {sup 64}Zn({alpha},{gamma}){sup 68}Ge (7- to 14-MeV) and {sup 63}Cu({alpha},{gamma}){sup 67}Ga (7-MeV) reactions were measured. For all measurements, natural elements were bombarded with He{sup +} beams from the 88 In. Cyclotron at the Lawrence Berkeley National Laboratory (LBNL). Irradiated samples were counted using a {gamma}-spectrometry system at LBNL's Low Background Facility. Measured {sup 197}Au({alpha},{gamma}){sup 201}Tl cross sections were compared with the NON-SMOKER theoretical values. The thick-target yields for the {sup 64}Zn({alpha},{gamma}){sup 68}Ge and {sup 63}Cu({alpha},{gamma}){sup 67}Ga reactions are also compared with the theoretical yield, calculated numerically using the energy dependent NON-SMOKER cross section data. In both cases, measured values are found to follow a trend of overlapping the predicted value near the alpha nucleus barrier height and fall below with a slowly widening difference between them in the sub-barrier energy points.

  8. {sup 57}Co(n,{gamma}){sup 58}Co reaction cross section: Thermal and resonance integral measurements and energy dependence

    SciTech Connect

    Maidana, Nora L.; Mesa, Joel; Vanin, Vito R.; Castro, Ruy M.; Dias, Mauro S.; Koskinas, Marina F.

    2004-07-01

    The {sup 57}Co(n,{gamma}){sup 58}Co thermal and resonance integral cross section were measured as 51(5) b and 20.0(19) b, respectively, by irradiating aliquots of {sup 57}Co solution sealed inside quartz bottles near the core of the IEA-R1 IPEN research reactor and counting the gamma-ray residual activity. The irradiations were monitored using Au-Al alloy foils, with and without Cd cover. The gamma-ray measurements were performed with a shielded HPGe detector. Westcott formalism was applied for the average neutron flux determination. The cross section energy dependence was evaluated using the multilevel Breit-Wigner expression considering the first two resonances and the statistical model for energies above the second resonance. Maxwellian averaged neutron capture cross section with neutron temperatures between 5 and 100 keV were also evaluated.

  9. High-Resolution Neutron Capture and Total Cross-Section Measurements, and the Astrophysical 95Mo(n,gamma) Reaction Rate at s-process Temperatures

    SciTech Connect

    Koehler, Paul Edward; Guber, Klaus H; Harvey, John A; Wiarda, Dorothea

    2008-01-01

    Abundances of Mo isotopes predicted by stellar models of the s process are, except for {sup 95}Mo, in good agreement with data from single grains of mainstream presolar SiC. Because the meteorite data seemed sound and no reasonable modification to stellar theory resulted in good agreement for {sup 95}Mo, it has been suggested that the recommended neutron capture reaction rate for this nuclide is 30% too low. Therefore, we have made a new determination of the {sup 95}Mo(n,{gamma}) reaction rate via high-resolution measurements of the neutron-capture and total cross sections of {sup 95}Mo at the Oak Ridge Electron Linear Accelerator. These data were analyzed with the R-matrix code SAMMY to obtain parameters for resonances up to E{sub n} = 10 keV. Also, a small change to our capture apparatus allowed us to employ a new technique to vastly improve resonance spin and parity assignments. These new resonance parameters, together with our data in the unresolved range, were used to calculate the {sup 95}Mo(n,{gamma}) reaction rate at s-process temperatures. We compare the currently recommended rate to our new results and discuss their astrophysical impact.

  10. Nuclear gamma rays from 720-MeV alpha-induced reactions on Al-27 and Si-28

    NASA Technical Reports Server (NTRS)

    Lieb, B. J.; Plendl, H. S.; Funsten, H. O.; Stronach, C. E.; Lind, V. G.

    1980-01-01

    Prompt gamma rays from the interaction of 720-MeV alpha particles with Al-27 and Si-28 were detected and analyzed to identify residual nuclei and to determine cross sections for production of specific levels. No gamma-ray transitions were detected from nuclei heavier than the target. From Doppler broadening, the momentum of the residual nuclei was estimated. The results are compared with previous results for 140- and 1600-MeV alphas on Al-27 and approximately 200-MeV positive or negative pions on Al-27 and Si-28 and fitted to a spallation-yield formula.

  11. Development of a code system DEURACS for theoretical analysis and prediction of deuteron-induced reactions

    NASA Astrophysics Data System (ADS)

    Nakayama, Shinsuke; Kouno, Hiroshi; Watanabe, Yukinobu; Iwamoto, Osamu; Ye, Tao; Ogata, Kazuyuki

    2017-09-01

    We have developed an integrated code system dedicated for theoretical analysis and prediction of deuteron-induced reactions, which is called DEUteron-induced Reaction Analysis Code System (DEURACS). DEURACS consists of several calculation codes based on theoretical models to describe respective reaction mechanisms and it was successfully applied to (d,xp) and (d,xn) reactions. In the present work, the analysis of (d,xn) reactions is extended to higher incident energy up to nearly 100 MeV and also DEURACS is applied to (d,xd) reactions at 80 and 100 MeV. The DEURACS calculations reproduce the experimental double-differential cross sections for the (d,xn) and (d,xd) reactions well.

  12. IMPACT OF A REVISED {sup 25}Mg(p, {gamma}){sup 26}Al REACTION RATE ON THE OPERATION OF THE Mg-Al CYCLE

    SciTech Connect

    Straniero, O.; Cristallo, S.; Imbriani, G.; DiLeva, A.; Limata, B.; Strieder, F.; Bemmerer, D.; Broggini, C.; Caciolli, A.; Corvisiero, P.; Costantini, H.; Lemut, A.; Formicola, A.; Gustavino, C.; Junker, M.; Elekes, Z.; Fueloep, Zs.; Gyuerky, Gy.; Gervino, G.; Guglielmetti, A.; and others

    2013-02-15

    Proton captures on Mg isotopes play an important role in the Mg-Al cycle active in stellar H-burning regions. In particular, low-energy nuclear resonances in the {sup 25}Mg(p, {gamma}){sup 26}Al reaction affect the production of radioactive {sup 26}Al{sup gs} as well as the resulting Mg/Al abundance ratio. Reliable estimations of these quantities require precise measurements of the strengths of low-energy resonances. Based on a new experimental study performed at the Laboratory for Underground Nuclear Astrophysics, we provide revised rates of the {sup 25}Mg(p, {gamma}){sup 26}Al{sup gs} and the {sup 25}Mg(p, {gamma}){sup 26}Al {sup m} reactions with corresponding uncertainties. In the temperature range 50-150 MK, the new recommended rate of {sup 26}Al {sup m} production is up to five times higher than previously assumed. In addition, at T = 100 MK, the revised total reaction rate is a factor of two higher. Note that this is the range of temperature at which the Mg-Al cycle operates in a H-burning zone. The effects of this revision are discussed. Due to the significantly larger {sup 25}Mg(p, {gamma}){sup 26}Al {sup m} rate, the estimated production of {sup 26}Al{sup gs} in H-burning regions is less efficient than previously obtained. As a result, the new rates should imply a smaller contribution from Wolf-Rayet stars to the galactic {sup 26}Al budget. Similarly, we show that the asymptotic giant branch (AGB) extra-mixing scenario does not appear able to explain the most extreme values of {sup 26}Al/{sup 27}Al, i.e., >10{sup -2}, found in some O-rich presolar grains. Finally, the substantial increase of the total reaction rate makes the hypothesis of self-pollution by massive AGBs a more robust explanation for the Mg-Al anticorrelation observed in globular-cluster stars.

  13. The preparation of nitrogen-doped TiO 2- xN x photocatalyst coated on hollow glass microbeads

    NASA Astrophysics Data System (ADS)

    Shifu, Chen; Xuqiang, Liu; Yunzhang, Liu; Gengyu, Cao

    2007-01-01

    In this paper, the effective method for nitrogen-doped TiO 2- xN x photocatalyst coated on hollow glass microbeads is described, which uses titanium tetraisopropoxide [Ti( iso-OC 3H 7) 4] as the raw materials and gaseous ammonia as a heat treatment atmosphere. The effects of heat treatment temperature and time on the photocatalytic activity of TiO 2- xN x/beads are studied. The photocatalyst is characterized by the UV-vis diffuse reflection spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis and scanning electron microscopy (SEM). The results show that when the TiO 2- xN x/beads is heated at 650 °C for 5 h, the photocatalytic activity of the TiO 2- xN x/beads is the best. Compared with TiO 2, the photoabsorption wavelength range of nitrogen-doped TiO 2- xN x red shifts of about 60 nm, and the photoabsorption intensity increases as well. The photocatalytic activity of the TiO 2- xN x/beads is higher than that of the TiO 2/beads under visible light irradiation. The presence of nitrogen neither influences on the transformation of anatase to rutile, nor creates new crystal phases. When the TiO 2- xN x/beads is heated at 650 °C for 5 h, the amount of nitrogen-doped is 0.53 wt.% in the TiO 2- xN x. As the density of TiO 2- xN x/beads prepared is lower than 1.0 g/cm 3, it may float on water surface and use broader sunlight spectrum directly.

  14. Study of {sup 27}Al(n,x{gamma}) reactions up to a neutron energy of 400 MeV

    SciTech Connect

    Hitzenberger, H.; Pavlik, A.; Vonach, H.; Chadwick, M.B.; Haight, R.C.; Nelson, R.O.; Young, P.G.

    1994-06-01

    The prompt {gamma}-radiation from the interaction of fast neutrons with Al was measured using the white neutron beam of the WNR facility at the Los Alamos National Laboratory. Partial production cross sections for residual nuclei in the range from F to Al were measured from threshold up to 400 MeV by observing the most intense {gamma}-transitions between low lying levels of these nuclei. Two-dimensional neutron time-of-flight versus gamma pulse height spectra from the interaction of the neutrons with Al were observed after flight-paths of about 20 and 40 m with a high-purity Ge-detector. The neutron cross sections for prominent {gamma}-transitions in a large number of residual nuclei could be derived with typical uncertainties of 10--20% up to a neutron energy of 400 MeV. The energy resolution varies from {approx}0.2 MeV at 10 MeV to {approx}50 MeV at 400 MeV. In the low energy range (up to 60 MeV) the results are compared with nuclear model calculations using the code GNASH. A very good overall agreement is obtained without special adjustment of parameters.

  15. Fabrication of fiber-optic localized surface plasmon resonance sensor and its application to detect antibody-antigen reaction of interferon-gamma

    NASA Astrophysics Data System (ADS)

    Jeong, Hyeon-Ho; Erdene, Norov; Lee, Seung-Ki; Jeong, Dae-Hong; Park, Jae-Hyoung

    2011-12-01

    A fiber-optic localized surface plasmon (FO LSPR) sensor was fabricated by gold nanoparticles (Au NPs) immobilized on the end-face of an optical fiber. When Au NPs were formed on the end-face of an optical fiber by chemical reaction, Au NPs aggregation occurred and the Au NPs were immobilized in various forms such as monomers, dimers, trimers, etc. The component ratio of the Au NPs on the end-face of the fabricated FO LSPR sensor was slightly changed whenever the sensors were fabricated in the same condition. Including this phenomenon, the FO LSPR sensor was fabricated with high sensitivity by controlling the density of Au NPs. Also, the fabricated sensors were measured for the resonance intensity for the different optical systems and analyzed for the effect on sensitivity. Finally, for application as a biosensor, the sensor was used for detecting the antibody-antigen reaction of interferon-gamma.

  16. Absolute Determination for the Sodium-22(p,gamma)Magnesium-23 Reaction Rate: Consequences for Nucleosynthesis of Sodium-22 in Novae

    NASA Astrophysics Data System (ADS)

    Sallaska, Anne L.

    2010-11-01

    Hydrodynamic simulations of classical novae on ONe white dwarfs predict substantial production of 22Na. Observation of 22Na decay should be correlated with the corresponding nova because the half life of 22Na is only 2.6 years. The 1275-keV gamma ray from the beta decay of 22Na is, therefore, an excellent diagnostic for the nova phenomenon and a long-sought target of gamma-ray telescopes. Nova simulations determine the maximum 22Na-detection distance to be < 1 kpc for the INTEGRAL spectrometer SPI, consistent with its non-observation to date. However, model estimates are strongly dependent on the thermonuclear rate of the 22Na(p, gamma)23Mg reaction, which is the main destruction mechanism of 22Na in novae. The 22Na(p,gamma)23Mg rate is expected to be dominated by narrow, isolated resonances with Ep < 300 key. The currently employed rate is based on a single set of absolute resonance-strength measurements with Ep ≥ 290 keV, and one relative measurement of resonances with Ep ≥ 214 keV. Recently, a new level has been found in 23Mg which would correspond to a resonance at Ep = 198 keV that might dominate the reaction rate at nova temperatures. We have measured the 22Na(p, gamma) 23Mg resonance strengths directly and absolutely, in addition to resonance energies and branches. Proton beams were produced at the University of Washington and delivered to a specially designed beam line that included rastering and cold vacuum protection of the 22Na-implanted targets (fabricated at TRIUMF-ISAC). Two high-purity germanium detectors were employed and surrounded by anticoincidence shields to reduce cosmic backgrounds. Measurements were made on known 22Na+p resonances, which we observed at laboratory energies Ep = 213, 288, 454, 610 keV and on proposed resonances at Ep = 198, 209, and 232 key. The proposed resonances were not observed, and the upper limit placed on the 198-keV resonance strength indicates that the resonance at Ep = 213 keV still dominates the reaction rate

  17. THE EFFECT OF THE {sup 14}N(p, {gamma}){sup 15}O REACTION ON THE BLUE LOOPS IN INTERMEDIATE-MASS STARS

    SciTech Connect

    Halabi, Ghina M.; El Eid, Mounib F.; Champagne, Arthur

    2012-12-10

    We present stellar evolutionary sequences of stars in the mass range 5-12 M{sub Sun }, having solar-like initial composition. The stellar models are obtained using updated input physics, including recent rates of thermonuclear reactions. We investigate the effects of a modification of the {sup 14}N(p, {gamma}){sup 15}O reaction rate, as suggested by recent evaluations, on the formation and extension of the blue loops encountered during the evolution of the stars in the above mass range. We find that a reduced {sup 14}N(p, {gamma}){sup 15}O rate, as described in the text, has a striking impact on the physical conditions of burning and mixing during shell hydrogen burning when the blue loops are formed. In particular, we find that the efficiency of shell hydrogen burning is crucial for the formation of an extended blue loop. We show that a significantly reduced {sup 14}N(p, {gamma}){sup 15}O rate affects severely the extension of the blue loops and the time spent by the star in the blue part of the Hertzsprung-Russell diagram in the mass range 5-7 M{sub Sun} if the treatment of convection is based on the Schwarzschild criterion only. In this case, envelope overshooting helps to restore well-extended blue loops as supported by the observations of the Cepheid stars. If core overshooting is included during the core hydrogen and core helium burning phases, the loop formation and its properties depend on how this overshooting is treated for a given stellar mass range, as well as on its efficiency.

  18. Direct-Reaction Studies by Particle-Gamma Coincidence Spectroscopy Using HPGe-CsI and HPGe-Si Arrays

    SciTech Connect

    Allmond, James M

    2013-01-01

    Particle- and particle- - coincidence spectroscopy has several advantages in the study of direct reactions(particularly in inverse kinematics) since it can generally allow determination of: decay paths; high-precision level energies; multipolarities of transitions; and cross sections. Techniques for studying direct reactions by particle- coincidence spectroscopy are presented for two cases: (1) heavy-ion reactions with HPGe-CsI, and (2) light-ion reactions with HPGe-Si. Future direct-reaction studies with radioactive ion beams (RIBs) will mostly involve low beam intensities and inverse kinematics (i.e., Abeam>Atarget), which eliminates the traditional use of magnetic spectrometers. Particle- coincidence spectroscopy currently provides the most viable method to study direct reactions with nuclei of any level density. In the present study, the capabilities and limitations of the technique are explored.

  19. New measurements of excitation functions of 186W(p,x) nuclear reactions up to 65 MeV. Production of a 178W/178mTa generator

    NASA Astrophysics Data System (ADS)

    Tárkányi, F.; Ditrói, F.; Takács, S.; Hermanne, A.

    2017-01-01

    New experimental excitation functions for proton induced reactions on natW are presented in the 32-65 MeV energy range. The cross-sections for natW(p,xn)186,184m,184g,183, 182m,182g,181Re, natW(p,x)178W, natW(p,x)183,182, 180m, 177,176,175Ta, 175Hf and 177Lu were measured via an activation method by using a stacked-foil irradiation technique and high resolution gamma-ray spectroscopy. The results were compared with predicted values obtained with the nuclear reaction code TALYS (results taken from the TENDL 2014 and TENDL 2015 on-line libraries). Production routes of the medically relevant radionuclides 186Re, the 178W → 178Ta generator and 181W are discussed.

  20. Comparison of abnormal cell flagging of the hematology analyzers Sysmex XN and Sysmex XE-5000 in oncohematologic patients.

    PubMed

    Furundarena, J R; Sainz, M; Uranga, A; Cuevas, L; Lopez, I; Zubicaray, J; Bizjak, A; Robado, N; Araiz, M

    2017-02-01

    Hematology analyzers should optimize flagging while minimizing false-negative results and unnecessary microscopic reviews. We compared flagging performance of Sysmex XE-5000 and XN analyzers in oncohematologic patients. Differential counts were performed by Cellavision digital system (100 cells) and a hematologist (another 100 cells). First, we included 292 samples (86 with blasts): 28 acute lymphoblastic leukemia, 88 acute myeloid leukemia, 91 myelodysplastic syndromes, 45 chronic myeloproliferative neoplasms, and 40 chronic myelomonocytic leukemia. Sensitivity, specificity and efficiency to detect blasts were 59.3%, 88.3%, and 79.8% for XE-5000 analyzer and 70.9%, 91.3%, and 85.2% for the XN analyzer. Then, we included 111 lymphoid malignancies. In 55 CLL XE-5000 flagged for Abn Lympho/L_Blasts?, XN flagged for Abn Lympho?. In one-third of 19 samples with splenic marginal lymphoma, none of the analyzers flagged. In 5 Sézary syndrome cases, XE-5000 triggered the Abn Lympho/L_Blasts? flag while the flagging in XN was less consistent: Abn Lympho? Blasts? and Atypical Lympho?. In 5 hairy cell leukemias, both analyzers only flagged one sample. In 13 myelomas, XE-5000 generated Atypical Lympho? flag; XN triggered more variable flags. In other lymphoid malignancies, flags were variable. XN analyzer generates less samples with false basophilia. XN analyzer has improved blast detection in oncohematologic patients. Operators cannot rely on the blast flag alone but have to consider other flags and hemogram data. In lymphoproliferative disorders, XN analyzer yields less samples with pseudobasophilia. Both analyzers must improve flagging for hairy cell leukemia. © 2016 John Wiley & Sons Ltd.

  1. The value of the white precursor cell channel (WPC) on the Sysmex XN-1000 analyser in a specialist paediatric hospital.

    PubMed

    Jones, Amanda S; Tailor, Hitesh; Liesner, Ri; Machin, Samuel J; Briggs, Carol J

    2015-02-01

    Historically, haematology analyser flags for abnormal white blood cells (WBCs) show good sensitivity but lower specificity, causing unnecessary blood film reviews. While the WBC differential channel on Sysmex XE and XN instruments reports a combined flag for blasts/abnormal lymphocytes, the new white precursor cell channel (WPC) on the XN series has been introduced to separate this into a specific flag for either cell type or, if no abnormality, remove the flag entirely. To compare the efficiency of abnormal WBC flags from the XN WPC to our existing analyser and determine whether WPC can reduce false positive flags and blood films required. Abnormal WBC flags from the Sysmex XE-5000 and XN-1000 were compared to manual differential and blood film morphology on 300 K2EDTA samples from infants and children. The XN WPC flag for blasts was more sensitive and specific than flags indicating blasts on the XE-5000, with a reduction in false positives from 64% (XE) to 36% (XN). Overall efficiency of the WPC flag for abnormal lymphocytes was 94% vs 79% on the XE. WPC reduced false positive flags for blasts and abnormal lymphocytes on neonatal samples by 50%. Automatic reflex analysis by WPC correctly removed a false positive flag from the white cell differential channel on 46% of samples. Total abnormal WBC flags from XN WPC were less (73) than the XE-5000 (92). XN WPC demonstrated superior efficiency of abnormal WBC flags on paediatric samples, compared to the XE-5000, with greater sensitivity and specificity of flagging, reducing blood films for review. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  2. Low-temperature growth of InxGa1-xN films by radio-frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Wang, J.; Shi, X. J.; Zhu, J.

    2013-01-01

    The low-temperature growth of InxGa1-xN films on quartz glass substrates utilizing radio-frequency magnetron sputtering is investigated. In the InxGa1-xN films prepared using an In-Ga alloy target, grazing incidence X-ray diffraction (GIXRD) peaks corresponding to wurtzite structure were observed. X-ray photoelectron spectroscopy (XPS) was applied to study the extent of oxygen contamination and chemical states, and secondary ion mass spectrometry (SIMS) was used to evaluate the distribution profiles of oxygen impurity in the as-grown InxGa1-xN thin films. XPS and SIMS analysis indicate that the entire thin films have oxide phases. However, no evidence of In2O3, Ga2O3, or indium oxynitride phases was shown in XRD studies. It may be predicted that the oxygen impurities formed amorphous oxide phases embedded in InxGa1-xN matrix. According to our findings, indium is a major phase in the InxGa1-xN thin films which suggests that a significant amount of indium remains un-reacted with N2. The optical transmittance spectra of the as-grown films show interference fringe patterns. The indium fraction x of the as-deposited InxGa1-xN thin films can be calculated out by the transmittance data.

  3. Cytokine mRNA expression in leprosy: a possible role for interferon-gamma and interleukin-12 in reactions (RR and ENL).

    PubMed

    Moraes, M O; Sarno, E N; Almeida, A S; Saraiva, B C; Nery, J A; Martins, R C; Sampaio, E P

    1999-11-01

    Leprosy patients during the natural course of the disease may develop reactional episodes, namely reversal reaction (RR) and erythema nodosum leprosum (ENL). Immunological events described as occurring during RR indicate up-regulation of the immune response, whereas in ENL the events are not fully understood. The aim of this study was to analyse the in vivo pattern of cytokine gene expression in the reactional states of leprosy. Peripheral blood mononuclear cells (PBMC, n = 14) and tissue samples (n = 17) obtained from patients with ENL and RR were obtained and assayed by RT-PCR. PBMC obtained from unreactional patients (n = 15) and normal individuals (n = 5) were also assessed. Expression of interferon (IFN)gamma, granulocyte-macrophage colony stimulating factor (GM-CSF), interleukin (IL)-2Rp55, perforin and IL-1beta mRNA in PBMC were detected mostly in ENL/RR patients, but not in unreactional patients. Likewise, cytokines such as IL-6, IL-8, tumour necrosis factor (TNF)alpha and TNFbeta were also present in reactional and tuberculoid patients as opposed to lepromatous leprosy (BL/LL). Interestingly, the majority of ENL/RR patients showed messages for IL-6, IL-10, IL-12 and TNFalpha in the skin. IFNgamma was detected in 84.6% (ENL) and 100% (RR) of the patients, whereas IL-4 was detected only in few individuals (38.5 and 25%, respectively). Although mRNA expression and protein levels may be different, the data reported in this study suggest a cytokine mRNA profile that seems to be indistinguishable for RR and ENL. In addition, it shows up-regulation of immuno-inflammatory cytokines in the blood and tissue of the same patient examined before and during reaction. Furthermore, it is suggested that this pattern of response results from an immunological reactivation that might lead to an acute inflammatory response in both reactional episodes.

  4. Significant elastic anisotropy in Ti{sub 1-x}Al{sub x}N alloys

    SciTech Connect

    Tasnadi, Ferenc; Abrikosov, Igor A.; Rogstroem, Lina; Johansson, Mats P.; Oden, Magnus; Almer, Jonathan

    2010-12-06

    Strong compositional-dependent elastic properties have been observed theoretically and experimentally in Ti{sub 1-x}Al{sub x}N alloys. The elastic constant, C{sub 11}, changes by more than 50% depending on the Al-content. Increasing the Al-content weakens the average bond strength in the local octahedral arrangements resulting in a more compliant material. On the other hand, it enhances the directional (covalent) nature of the nearest neighbor bonds that results in greater elastic anisotropy and higher sound velocities. The strong dependence of the elastic properties on the Al-content offers new insight into the detailed understanding of the spinodal decomposition and age hardening in Ti{sub 1-x}Al{sub x}N alloys.

  5. Physical properties and applications of InxGa1-xN nanowires

    NASA Astrophysics Data System (ADS)

    Segura-Ruiz, J.; Gómez-Gómez, M.; Garro, N.; Martínez-Criado, G.; Cantarero, A.; Denker, C.; Malindretos, J.; Rizzi, A.

    2014-05-01

    We have successfully grown InxGa1-xN nanowires by plasma-assisted molecular beam epitaxy on silicon substrates. The alloy composition and crystal quality have been analyzed by Raman scattering, photoluminescence spectroscopy and x-ray fluorescence nanoprobe techniques. InxGa1-xN is an one-mode alloy, where the different optical modes have an intermediate frequency of that of pure InN and GaN. The sample composition can be derived from the Raman data. On the other hand, by using the optical gap provided by the emission spectra, we conclude that the samples have a lower Ga content than that provided by the Raman analysis. X-ray fluorescence maps and photoluminescence measured in single nanowires help to explain this contradictory result.

  6. Band gap bowing and electron localization of (GaxIn1-x)N

    SciTech Connect

    Lee, Byounghak; Wang, Lin-Wang

    2006-05-09

    The band gap bowing and the electron localization ofGaxIn1-xN are calculated using both the local density approximation (LDA)and screened-exchange local density functional (sX-LDA) methods. Thecalculated sX-LDA band gaps are in good agreement with the experimentallyobserved values, with errors of -0.26 and 0.09 eV for bulk GaN and InN,respectively. The LDA band gap errors are 1.33 and 0.81 eV for GaN andInN, in order. In contrast to the gap itself, the band gap bowingparameter is found to be very similar in sX-LDA and LDA. We identify thelocalization of hole states in GaxIn1-xN alloys along In-N-In chains. Thepredicted localizationis stronger in sX-LDA.

  7. Overview of reaction mechanisms for calculating the high energy component of fast-nucleon induced gamma spectra

    SciTech Connect

    Dietrich, F.S.

    1995-02-21

    This presentation reviews the current status of quantum mechanical models for understanding the high-energy component of gamma spectra resulting from radiative capture of fast nucleons; i.e., the part of the spectrum that is not amenable to standard statistical model (Hauser-Feshbach) treatments. These models are based on the direct-semidirect (DSD) model and its variants. Included are recent results on the extension of the DSD model to unbound final states, a discussion of problems and improvements in understanding the form factors in this model, and a brief discussion of a model closely related to the DSD, the pure-resonance model.

  8. Data on photoneutron reactions from various experiments for 133Cs, 138Ba and 209Bi nuclei

    NASA Astrophysics Data System (ADS)

    Varlamov, V. V.; Ishkhanov, B. S.; Orlin, V. N.; Peskov, N. N.

    2016-07-01

    Basic methods for determining cross sections for photoneutron partial reactions are examined. They are obtained directly in experiments with quasimonoeneregetic annihilation photons or from the cross section for the ( γ, xn) = ( γ, 1 n) + 2( γ, 2 n) + 3( γ, 3 n) +... neutron-yield reaction in experiments with bremsstrahlung photons by introducing corrections based on statistical nuclear-reaction theory. The difference in the conditions of these experiments, which leads to discrepancies between their results because of sizable systematic errors, is analyzed. Physical criteria are used to study the reliability of data on the photodisintegration of 133Cs, 138Ba, and 209Bi nuclei. The cross sections for partial and total reactions satisfying the reliability criteria are evaluated within the experimental-theoretical method ( σ eval( γ, in) = F i theor × σ expt( γ, xn)) on the basis of the experimental cross sections σ expt( γ, xn) and the results of the calculations within the combined model of photonuclear reactions.

  9. Structure and electronic properties of conducting, ternary TixTa1-xN films

    NASA Astrophysics Data System (ADS)

    Matenoglou, G. M.; Lekka, Ch. E.; Koutsokeras, L. E.; Karras, G.; Kosmidis, C.; Evangelakis, G. A.; Patsalas, P.

    2009-05-01

    We report on the electronic structure and optical properties of conducting ternary transition metal nitrides consisting of metals of different groups of the periodic table of elements. For the study of the bonding, electronic structure, and optical properties of conducting TixTa1-xN film growth, optical spectroscopy and ab initio calculations were used. Despite the different valence electron configuration of the constituent elements, Ta(d3s2) and Ti(d2s2), we show that TiN and TaN are completely soluble due to the hybridization of the d and sp electrons of the metals and N, respectively, that stabilizes the ternary TixTa1-xN systems to the rocksalt structure. The optical properties of TixTa1-xN have been studied using spectroscopic methods and detailed electronic structure calculations, revealing that the plasma energy of the fully dense TixTa1-xN is varying between 7.8 and 9.45 eV. Additional optical absorption bands are manifested due to the N p →Ti/Ta d interband transition the t2g→eg transition due to splitting of the metals' d band, with the major exception of the Ti0.50Ta0.50N, where the eg unoccupied states are not manifested due to the local structure of the ternary system; this finding is observed for the first time and proves previous assignments of optical transitions in TaN.

  10. Distribution of cations in wurtzitic InxGa1-xN and InxAl1-xN alloys: Consequences for energetics and quasiparticle electronic structures

    NASA Astrophysics Data System (ADS)

    de Carvalho, Luiz Cláudio; Schleife, André; Furthmüller, Jürgen; Bechstedt, Friedhelm

    2012-03-01

    The ternary, isostructural, wurtzite-derived group-III mononitride alloys InxGa1-xN and InxAl1-xN are reexamined within a cluster expansion approach. Using density functional theory together with the AM05 exchange-correlation functional, the total energies and the optimized atomic geometries of all 22 clusters classes of the cluster expansion for each material system are calculated. The computationally demanding calculation of the corresponding quasiparticle electronic structures is achieved for all cluster classes by means of a recently developed scheme to approximately solve the quasiparticle equation based on the HSE06 hybrid functional and the G0W0 approach. Using two different alloy statistics, the configurational averages for the lattice parameters, the mixing enthalpies, and the bulk moduli are calculated. The composition-dependent electronic structures of the alloys are discussed based on configurationally averaged electronic states, band gaps, and densities of states. Ordered cluster arrangements are found to be energetically rather unfavorable, however, they possess the smallest energy gaps and, hence, contribute to light emission. The influence of the alloy statistics on the composition dependencies and the corresponding bowing parameters of the band gaps is found to be significant and should, hence, lead to different signatures in the optical-absorption or -emission spectra.

  11. Distribution of cations in wurtzitic InxGa1-xN and InxAl1-xN alloys: Consequences for energetics and quasiparticle electronic structures

    DOE PAGES

    de Carvalho, Luiz Cláudio; Schleife, André; Furthmüller, Jürgen; ...

    2012-03-27

    The ternary, isostructural, wurtzite-derived group-III mononitride alloys InxGa1-xN andInxAl1-xN are reexamined within a cluster expansion approach. Using density functional theory together with the AM05 exchange-correlation functional, the total energies and the optimized atomic geometries of all 22 clusters classes of the cluster expansion for each material system are calculated. The computationally demanding calculation of the corresponding quasiparticle electronic structures is achieved for all cluster classes by means of a recently developed scheme to approximately solve the quasiparticle equation based on the HSE06 hybrid functional and the G₀W₀ approach. Using two different alloy statistics, the configurational averages for the lattice parameters,more » the mixing enthalpies, and the bulk moduli are calculated. The composition-dependent electronic structures of the alloys are discussed based on configurationally averaged electronic states, band gaps, and densities of states. Ordered cluster arrangements are found to be energetically rather unfavorable, however, they possess the smallest energy gaps and, hence, contribute to light emission. The influence of the alloy statistics on the composition dependencies and the corresponding bowing parameters of the band gaps is found to be significant and should, hence, lead to different signatures in the optical-absorption or -emission spectra.« less

  12. R-matrix analysis of the {sup 236}U(n,{gamma}) reaction in the resolved resonance energy region

    SciTech Connect

    Mezentseva, Zh.; Berthoumieux, E.; Gunsing, F.; Cennini, P.; Furman, W.; Goverdovski, A.; Mengoni, A.

    2009-01-28

    The neutron capture cross section of {sup 236}U was measured in the neutron energy range from 1 eV to 10 keV by the neutron time-of-flight method at the GELINA white pulsed neutron source of the Institute for Reference Materials and Measurements (IRMM) in Geel (Belgium). The gamma rays originating from neutron capture events were detected by two C{sub 6}D{sub 6}-based liquid scintillators using the pulse height weighting technique. The weighting function has been derived from Monte-Carlo simulations of the detector response to monoenergetic gamma rays.The sample under investigation with a total amount of 338 mg of {sup 236}U was located in the neutron beam at a distance of 28.6 m from the source. The shape of the neutron flux was determined by a {sup 10}B neutron counter, placed approximately 60 cm upstream in the neutron beam line.The neutron capture yield in the resolved resonance region up to 1 keV has been derived from time-of-flight spectra.

  13. Local verification between the hematological analyzers Sysmex XN-series and XE-5000.

    PubMed

    Pérez, I; Redín, M E; Vives, A; Garrido, A; Urrechaga, E; Lacasta, M

    2016-06-01

    The aim of this study was to perform a verification of the hematology analyzer Sysmex XN-2000 by comparing with the previous XE-5000. This study assessed the precision and carryover on the XN-2000 and the systematic error between the both counters according to desirable biological variability criterion and a flag comparison study. Within-run precision and between-batch precision were measured according to the ICSH guidelines. A comparative study was performed analyzing two hundred and six samples of peripheral blood from patients. The statistical study was conducted using the Passing-Bablok and Bland-Altman analyses. The leucocyte flag comparison was made by measuring the efficiency rate. Between-batch precision was lower than that recommended by the biological variability criterion and manufacturer specifications. The comparison gave nonagreement results for neutrophil and basophil counts according to the criterion of biological variability. Erythroblasts and immature granulocytes showed nonagreement, but there is no available biological variation database for these parameters to compare with. Nevertheless, excellent absolute agreement was found for red blood cell parameters, and for platelet, lymphocyte, monocyte, and eosinophil counts. The global results obtained for the precision, comparability, and efficiency provide a satisfactory integration of the XN-2000 in the core laboratory routine and accomplish an optimal reliability. © 2016 John Wiley & Sons Ltd.

  14. Mechanical, Anisotropic, and Electronic Properties of XN (X = C, Si, Ge): Theoretical Investigations.

    PubMed

    Ma, Zhenyang; Liu, Xuhong; Yu, Xinhai; Shi, Chunlei; Wang, Dayun

    2017-08-08

    The structural, mechanical, elastic anisotropic, and electronic properties of Pbca-XN (X = C, Si, Ge) are investigated in this work using the Perdew-Burke-Ernzerhof (PBE) functional, Perdew-Burke-Ernzerhof for solids (PBEsol) functional, and Ceperly and Alder, parameterized by Perdew and Zunger (CA-PZ) functional in the framework of density functional theory. The achieved results for the lattice parameters and band gap of Pbca-CN with the PBE functional in this research are in good accordance with other theoretical results. The band structures of Pbca-XN (X = C, Si, Ge) show that Pbca-SiN and Pbca-GeN are both direct band gap semiconductor materials with a band gap of 3.39 eV and 2.22 eV, respectively. Pbca-XN (X = C, Si, Ge) exhibits varying degrees of mechanical anisotropic properties with respect to the Poisson's ratio, bulk modulus, shear modulus, Young's modulus, and universal anisotropic index. The (001) plane and (010) plane of Pbca-CN/SiN/GeN both exhibit greater elastic anisotropy in the bulk modulus and Young's modulus than the (100) plane.

  15. Phase degradation in BxGa1-xN films grown at low temperature by metalorganic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Gunning, Brendan P.; Moseley, Michael W.; Koleske, Daniel D.; Allerman, Andrew A.; Lee, Stephen R.

    2017-04-01

    Using metalorganic vapor phase epitaxy, a comprehensive study of BxGa1-xN growth on GaN and AlN templates is described. BGaN growth at high-temperature and high-pressure results in rough surfaces and poor boron incorporation efficiency, while growth at low-temperature and low-pressure (750-900 °C and 20 Torr) using nitrogen carrier gas results in improved surface morphology and boron incorporation up to 7.4% as determined by nuclear reaction analysis. However, further structural analysis by transmission electron microscopy and x-ray pole figures points to severe degradation of the high boron composition films, into a twinned cubic structure with a high density of stacking faults and little or no room temperature photoluminescence emission. Films with <1% triethylboron (TEB) flow show more intense, narrower x-ray diffraction peaks, near-band-edge photoluminescence emission at 362 nm, and primarily wurtzite-phase structure in the x-ray pole figures. For films with >1% TEB flow, the crystal structure becomes dominated by the cubic phase. Only when the TEB flow is zero (pure GaN), does the cubic phase entirely disappear from the x-ray pole figure, suggesting that under these growth conditions even very low boron compositions lead to mixed crystalline phases.

  16. The effects of acetaldehyde, glyoxal and acetic acid on the heterogeneous reaction of nitrogen dioxide on gamma-alumina.

    PubMed

    Sun, Zhenyu; Kong, Lingdong; Ding, Xiaoxiao; Du, Chengtian; Zhao, Xi; Chen, Jianmin; Fu, Hongbo; Yang, Xin; Cheng, Tiantao

    2016-04-14

    Heterogeneous reactions of nitrogen oxides on the surface of aluminium oxide result in the formation of adsorbed nitrite and nitrate. However, little is known about the effects of other species on these heterogeneous reactions and their products. In this study, diffuse reflectance infrared spectroscopy (DRIFTS) was used to analyze the process of the heterogeneous reaction of NO2 on the surface of aluminium oxide particles in the presence of pre-adsorbed organic species (acetaldehyde, glyoxal and acetic acid) at 298 K and reveal the influence of these organic species on the formation of adsorbed nitrite and nitrate. It was found that the pre-adsorption of organic species (acetaldehyde, glyoxal and acetic acid) on γ-Al2O3 could suppress the formation of nitrate to different extents. Under the same experimental conditions, the suppression of the formation of nitrate by the pre-adsorption of acetic acid is much stronger than that by pre-adsorption of acetaldehyde and glyoxal, indicating that the influence of acetic acid on the heterogeneous reaction of NO2 is different from that of acetaldehyde and glyoxal. Surface nitrite is formed and identified to be an intermediate product. For the heterogeneous reaction of NO2 on the surface of γ-Al2O3 with and without the pre-adsorption of acetaldehyde and glyoxal, it is firstly formed and then gradually disappears as the reaction proceeds, but for the reaction with the pre-adsorption of acetic acid, it is the final main product besides nitrate. This indicates that the pre-adsorption of acetic acid would promote the formation of nitrite, while the others would not change the trend of the formation of nitrite. The possible influence mechanisms of the pre-adsorption of acetaldehyde, glyoxal and acetic acid on the heterogeneous conversion of NO2 on γ-Al2O3 are proposed and atmospheric implications based on these results are discussed.

  17. Apparent Polyploidization after Gamma Irradiation: Pitfalls in the Use of Quantitative Polymerase Chain Reaction (qPCR) for the Estimation of Mitochondrial and Nuclear DNA Gene Copy Numbers

    PubMed Central

    Kam, Winnie W. Y.; Lake, Vanessa; Banos, Connie; Davies, Justin; Banati, Richard

    2013-01-01

    Quantitative polymerase chain reaction (qPCR) has been widely used to quantify changes in gene copy numbers after radiation exposure. Here, we show that gamma irradiation ranging from 10 to 100 Gy of cells and cell-free DNA samples significantly affects the measured qPCR yield, due to radiation-induced fragmentation of the DNA template and, therefore, introduces errors into the estimation of gene copy numbers. The radiation-induced DNA fragmentation and, thus, measured qPCR yield varies with temperature not only in living cells, but also in isolated DNA irradiated under cell-free conditions. In summary, the variability in measured qPCR yield from irradiated samples introduces a significant error into the estimation of both mitochondrial and nuclear gene copy numbers and may give spurious evidence for polyploidization. PMID:23722662

  18. Properties of {sup 112}Cd from the (n,n{sup '}{gamma}) reaction: Lifetimes and transition rates

    SciTech Connect

    Garrett, P. E.; Green, K. L.; Lehmann, H.; Jolie, J.; McGrath, C. A.; Yeh, M.; Yates, S. W.

    2007-05-15

    Lifetimes of levels below 4 MeV in {sup 112}Cd have been measured using the Doppler shift attenuation technique following inelastic scattering of monoenergetic neutrons. Reduced transition rates are determined using the results of previous studies and the current lifetimes. The electromagnetic properties of {sup 112}Cd are outlined, and together with results from previous nucleon-transfer studies and inelastic scattering, the levels in {sup 112}Cd are interpreted in terms of single-particle configurations and collective excitations, assuming a vibrational model with intruder states. The collective states and their {gamma}-ray decays are compared with IBM-2 model calculations that allow for the mixing between the normal phonon states and intruder configurations. Levels below 1.5 MeV are reproduced reasonably well, whereas at higher excitation energy the calculations fail to reproduce the data in detail.

  19. The 28Si(p,t)26Si*(p) reaction and implications for the astrophysical 25Al(p,gamma)26Si reaction rate

    SciTech Connect

    Chipps, K.; Bardayan, Daniel W; Chae, K. Y.; Cizewski, J. A.; Kozub, R. L.; Liang, J Felix; Matei, Catalin; Moazen, Brian; Nesaraja, Caroline D; O'Malley, Patrick; Pain, S. D.; Peters, W. A.; Pittman, S. T.; Schmitt, Kyle; Smith, Michael Scott

    2010-10-01

    Several resonances in 25Al(p, )26Si have been studied via the 28Si(p,t)26Si reaction. Triton energies and angular distributions were measured using a segmented annular detector array. An additional silicon detector array was used to simultaneously detect the coincident protons emitted from the decay of states in 26Si above the proton threshold, in order to determine branching ratios. A resonance at 5927 4 keV has been experimentally confirmed as the first = 0 state above the proton threshold, with a proton branching ratio consistent with one.

  20. Search for genetic variants in the retinoid X receptor-gamma-gene by polymerase chain reaction-single-strand conformation polymorphism in patients with resistance to thyroid hormone without mutations in thyroid hormone receptor beta gene.

    PubMed

    Romeo, Stefano; Menzaghi, Claudia; Bruno, Rocco; Sentinelli, Federica; Fallarino, Mara; Fioretti, Francesca; Filetti, Sebastiano; Balsamo, Armando; Di Mario, Umberto; Baroni, Marco G

    2004-05-01

    Resistance to thyroid hormone (RTH) is an inherited disease characterized by reduced tissue sensitivity to thyroid hormone. Approximately 90% of subjects with RTH have mutation in the thyroid hormone receptor beta (TRbeta) gene. Approximately 10% of subjects diagnosed as having RTH do not carry mutation in the TRbeta gene. A possible linkage was reported with the retinoid X receptor-gamma (RXR-gamma) gene in two families. The aim of this study is to search for mutation within the RXR-gamma gene in unrelated subjects with diagnosed RTH without mutations in the TRbeta gene. Four subjects with RTH were studied, and sequence variants in the RXR-gamma gene were searched by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP). Analysis of all the 10 exons of the RXR-gamma gene, including intron-exon boundaries, promoter region and 3' untranslated region (UTR) reveled two variant bands in subjects II and III. Sequencing of these variants showed two single nucleotide polymorphisms (SNPs): 447C > T in exon 3 for patients II and IVS9 + 6A > G for patient III. Both SNPs were also present at high frequency in a group of normal subjects and in nonaffected relatives of subject III. In conclusion, in patients with RTH we have found two SNPs in the RXR-gamma gene; these SNPS are common in the general population, thus excluding a role for the RXR-gamma gene in these patients.

  1. Pentaquark {Theta}{sup +} production from the reaction {gamma}p {yields} {pi}{sup +} K{sup -} {Theta}{sup +}

    SciTech Connect

    W. Liu; C. M. Ko; V. Kubarovsky

    2004-02-01

    The cross section for {Theta}{sup +} production from the reaction {gamma}p {yields} {pi}{sup +} K{sup -} {Theta}{sup +}, which was observed in the CLAS experiment at the Jefferson National Laboratory, is evaluated in a hadronic model that includes couplings of {Theta}{sup +} to both KN and K*N. With their coupling constants determined from the empirical {pi} NN(1710) and {rho} NN(1710) coupling constants using the SU(3) symmetry, the cross section for this reaction has been evaluated by taking {Theta}{sup +} to have spin 1/2 and isospin 0 but either positive or negative parity. We find that the cross section is 10-15 nb if {Theta}{sup +} has positive parity as predicted by the chiral soliton model. The cross section is reduced by more than a factor of 10 if {Theta}{sup +} has negative parity as given by lattice QCD studies. For both parities, the differential distribution peaks at small negative four momentum transfer as expected from the dominating t-channel kaon-exchange diagram that involves only the coupling of {Theta}{sup +} to KN.

  2. A review of the synthesis of reduced defect density InxGa1-xN for all indium compositions

    NASA Astrophysics Data System (ADS)

    Clinton, Evan A.; Vadiee, Ehsan; Fabien, Chloe A. M.; Moseley, Michael W.; Gunning, Brendan P.; Doolittle, W. Alan; Fischer, Alec M.; Wei, Yong O.; Xie, Hongen; Ponce, Fernando A.

    2017-10-01

    A review of metal rich and nitrogen rich (N-rich), low-temperature grown InxGa1-xN is provided, focusing on two low-temperature approaches that have resulted in non-phase separated InxGa1-xN. The metal modulated epitaxy (MME) and N-rich, low temperature approaches to the reduction of defects in InxGa1-xN are described and are capable of growing InxGa1-xN throughout the miscibility gap. MME films remain smooth at all thicknesses but show device quality material primarily for x < 0.2 and x > 0.6. Low temperature, N-rich grown films show a critical thickness extend well beyond the theoretical values and results in slower relaxation through the 0.2 < x < 0.6 range most interesting for light emitters and solar cells. This reduced defect density results in improved optical emission, but due to increased roughening with increased thickness, low temperature, N-rich films are limited to thin layers. Future thick InxGa1-xN substrates are necessary to increase design freedom, as well as improve optoelectronic device performance. Initial results with films up to 800 nm are shown to display evidence of defect annihilation which could be promising for future thick optoelectronic templates and thick devices.

  3. Search for the pentaquark Theta+ in the gamma He-3 ---> p Lambda Theta+ reaction measured at CLAS

    SciTech Connect

    Niccolai, Silvia

    2004-07-01

    Preliminary results of the analysis of the γ3He→ pΛΘ+ channel, a reaction not observed until now, are here summarized. The data have been obtained at Jefferson Lab with the CLAS detector for photon energies from threshold up to 1.55 GeV. The final state has been identified through the reconstruction of the decay modes Λ → pπ−, Θ+ → pK0, K0 → π+π−, as well as Θ+ → nK+. Three independent analysis techniques have been used.

  4. Synergistic effect among Cl2, SO2 and NO2 in their heterogeneous reactions on gamma-alumina

    NASA Astrophysics Data System (ADS)

    Huang, Zhenling; Zhang, Zhaohui; Kong, Weiheng; Feng, Shuo; Qiu, Ye; Tang, Siqun; Xia, Chuanqin; Ma, Lingling; Luo, Min; Xu, Diandou

    2017-10-01

    Severe haze in China has been a global concern in recent years. Most studies about the mechanism of haze formation mare only focused on the heterogeneous reactions of SO2 and NO2 on mineral aerosols. However, little is known about the role of molecular chlorine (Cl2) in those reactions. Here, we investigated the heterogeneous uptake of Cl2, SO2 and NO2 on γ-Al2O3 particles under different conditions using a quartz-based flow reactor. We found that the existence of γ-Al2O3 seed aerosols significantly promotes the formation of secondary chloride, sulfate and nitrate aerosols, and Cl2, NO2 and SO2 have synergistic effects when they react on γ-Al2O3 surface under humid condition. The results also shows that Cl2 can promote the formation of secondary sulfate and nitrate aerosols on γ-Al2O3 surface. Moreover, Cl2 is much easier to react with the surface of γ-Al2O3 and form secondary Cl- aerosol when comparing with NO2 and SO2, suggesting that Cl2 is of great importance in atmospheric chemistry, it has the potential to alter the surface properties (e.g., chemical composition and fraction) of mineral aerosol, enhance the production of secondary inorganic aerosols in the troposphere, and thus cause adverse effects on the climate and human health.

  5. MedXN: an open source medication extraction and normalization tool for clinical text

    PubMed Central

    Sohn, Sunghwan; Clark, Cheryl; Halgrim, Scott R; Murphy, Sean P; Chute, Christopher G; Liu, Hongfang

    2014-01-01

    Objective We developed the Medication Extraction and Normalization (MedXN) system to extract comprehensive medication information and normalize it to the most appropriate RxNorm concept unique identifier (RxCUI) as specifically as possible. Methods Medication descriptions in clinical notes were decomposed into medication name and attributes, which were separately extracted using RxNorm dictionary lookup and regular expression. Then, each medication name and its attributes were combined together according to RxNorm convention to find the most appropriate RxNorm representation. To do this, we employed serialized hierarchical steps implemented in Apache's Unstructured Information Management Architecture. We also performed synonym expansion, removed false medications, and employed inference rules to improve the medication extraction and normalization performance. Results An evaluation on test data of 397 medication mentions showed F-measures of 0.975 for medication name and over 0.90 for most attributes. The RxCUI assignment produced F-measures of 0.932 for medication name and 0.864 for full medication information. Most false negative RxCUI assignments in full medication information are due to human assumption of missing attributes and medication names in the gold standard. Conclusions The MedXN system (http://sourceforge.net/projects/ohnlp/files/MedXN/) was able to extract comprehensive medication information with high accuracy and demonstrated good normalization capability to RxCUI as long as explicit evidence existed. More sophisticated inference rules might result in further improvements to specific RxCUI assignments for incomplete medication descriptions. PMID:24637954

  6. Composition dependent dynamics of biexciton localization in AlxGa1-xN mixed crystals

    NASA Astrophysics Data System (ADS)

    Hirano, Daisuke; Tayagaki, Takeshi; Yamada, Yoichi; Kanemitsu, Yoshihiko

    2009-08-01

    We report the localization-dependent dynamics of biexcitons in AlxGa1-xN mixed crystals under exciton resonant excitation at low temperatures. After intense laser excitation, biexcitons rapidly localize into the band-tail states. The formation time of localized biexcitons becomes shorter with increasing Al composition. Both the inhomogeneous linewidth and the binding energy of biexcitons increase with the inhomogeneous linewidth of excitons. The biexciton binding energy is enhanced by the restriction of exciton motion to disordered potentials and the dynamics of stable biexcitons determines the optical spectrum in mixed crystals.

  7. Experimental analysis of neutron and background gamma-ray energy spectra of 80-400 MeV 7Li(p,n) reactions under the quasi-monoenergetic neutron field at RCNP, Osaka University

    NASA Astrophysics Data System (ADS)

    Iwamoto, Yosuke; Sato, Tatsuhiko; Satoh, Daiki; Hagiwara, Masayuki; Yashima, Hiroshi; Masuda, Akihiko; Matsumoto, Tetsuro; Iwase, Hiroshi; Shima, Tatsushi; Nakamura, Takashi

    2017-09-01

    To develop the 100-400 MeV quasi-monoenergetic neutron field, we measured neutron and unexpected gamma-ray energy spectra of the 7Li(p,n) reaction with 80-389 MeV protons in the 100-m time-of-flight (TOF) tunnel at the Research Center for Nuclear Physics (RCNP) cyclotron facility. Neutron energy spectra with energies above 3 MeV were measured by the TOF method, which had been reported in our previous papers, and photon energy spectra with energies above 0.1 MeV were measured by the automatic unfolding function of the radiation dose monitor DARWIN. For neutron spectra, the contribution of peak intensity to the total intensity integrated with energies above 3 MeV varied between 0.38 and 0.48 in the proton energy range of 80-389 MeV. For gamma-ray spectra, highenergetic gamma-rays at around 70 MeV originated from the decay of π0 were observed with proton energies higher than 200 MeV. For the 246-MeV proton incident reaction, the contribution of gamma-ray dose to neutron dose is negligible because the ratio of gamma-ray dose to neutron dose is 0.014.

  8. Growth of low-density GaN quantum dots on Al xGa 1-xN

    NASA Astrophysics Data System (ADS)

    Pakuła, K.; Bożek, R.; Surowiecka, K.; Stępniewski, R.; Wysmołek, A.; Baranowski, J. M.

    2006-04-01

    The growth of low-density GaN quantum dots on Al xGa 1-xN by metalorganic vapor phase epitaxy (MOVPE) using in situ etching of the Al xGa 1-xN surface in the presence of SiH 4, is reported. Subsequent growth stages have been verified by atomic force microscopy and micro-photoluminescence ( μPL). The low temperature μPL shows sharp emission lines originating from single quantum dots, without any artificial masks or mesa structures. This proves that the proposed growth technique offers unique possibility for detailed optical studies of energetic structure and recombination processes of single GaN/Al xGa 1-xN quantum dots.

  9. Dynamics of biexciton localization in AlxGa1-xN mixed crystals under exciton resonant excitation

    NASA Astrophysics Data System (ADS)

    Hirano, Daisuke; Tayagaki, Takeshi; Yamada, Yoichi; Kanemitsu, Yoshihiko

    2008-05-01

    We report the localization dynamics of biexcitons in AlxGa1-xN mixed crystals under exciton resonant excitation at low temperatures. During a few tens of picoseconds just after intense laser excitation, the photoluminescence (PL) spectral shape obeys an inverse Maxwell Boltzmann distribution and free biexcitons dominate the PL spectrum. With a further increase in the delay time, the biexciton PL peak energy and edge energy shift to lower energies. These redshift behaviors in AlxGa1-xN mixed crystals are completely different from the behaviors of free biexcitons in GaN crystals. Our observations reveal the rapid transformation dynamics from free to localized biexcitons in band-tail states in AlxGa1-xN mixed crystals.

  10. The first enantioselective organocatalytic Mukaiyama-Michael reaction: a direct method for the synthesis of enantioenriched gamma-butenolide architecture.

    PubMed

    Brown, Sean P; Goodwin, Nicole C; MacMillan, David W C

    2003-02-05

    The first enantioselective organocatalytic Mukaiyama-Michael reaction using alpha,beta-unsaturated aldehydes has been accomplished. The use of iminium catalysis has provided a new strategy for the enantioselective addition of 2-silyloxy furans to unsaturated aldehydes to generate a variety of butenolide systems, an important chiral synthon found among many natural isolates. The (2S,5S)-5-benzyl-2-tert-butyl-imidazolidinone amine catalyst has been found to mediate the conjugate addition of a wide variety of substituted and unsubstituted silyloxy furans to unsaturated aldehydes. A diverse range of aldehyde substrates can be accommodated in this new organocatalytic transformation. Application of this new asymmetric technology to the enantioselective total synthesis of spiculisporic acid and the corresponding 5-epi-spiculisporic acid analogue is also discussed.

  11. Astrophysical reaction rates for Ni-58,Ni-60(n,gamma) from new neutron capture cross section measurements

    SciTech Connect

    Guber, Klaus H; Derrien, Herve; Leal, Luiz C; Arbanas, Goran; Wiarda, Dorothea; Koehler, Paul; Harvey, John A

    2010-01-01

    New neutron capture cross section of 58,60Ni were measured in the energy range from 100 eV to 600 keV using the Oak Ridge Electron Linear Accelerator (ORELA). The combination of these new neutron capture data with previous transmission data allowed a resonance analysis up to 900 keV using R-matrix theory. The theoretically determined direct capture (DC) cross sections were included in the analyses. From these resonance parameters and the DC contribution, new (n,y) astrophysical reaction rates were determined over the entire energy range needed by the lastest stellar models describing the so-called weak s process. PACS numbers: 25.40.Lw, 26.20Kn, 27.40.+z, 27.50.+e, 97.10.Cv

  12. Photocatalytic activity of nanostructured {gamma}-Al{sub 2}O{sub 3}/TiO{sub 2} composite powder formed via a polyelectrolyte-multilayer-assisted sol-gel reaction

    SciTech Connect

    Logar, Manca; Kocjan, Andraz; Dakskobler, Ales

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer PEM assisted synthesis for {gamma}-Al{sub 2}O{sub 3}/TiO{sub 2} composite powder is developed. Black-Right-Pointing-Pointer Nanoparticulate TiO{sub 2} layer results in high specific surface area composite powder. Black-Right-Pointing-Pointer {gamma}-Al{sub 2}O{sub 3}/TiO{sub 2} composite powder exhibit enhanced photocatalytic activity. -- Abstract: Nanostructured, {gamma}-Al{sub 2}O{sub 3}/TiO{sub 2} composite powder was fabricated via an in situ, sol-gel reaction of titanium iso-propoxide in a self-assembled, polyelectrolyte multilayer (PEM) formed on the surface of high-specific-area, polycrystalline, {gamma}-Al{sub 2}O{sub 3} lamellas. The infiltration of the titanium precursor into the PEM, followed by the hydrolysis and condensation reactions with the water absorbed in the PEM after annealing, resulted in the formation of a nanostructured TiO{sub 2} layer on the surface of the {gamma}-Al{sub 2}O{sub 3} lamellas. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were employed to evaluate the morphology, the chemical composition and the crystallinity of the {gamma}-Al{sub 2}O{sub 3}/TiO{sub 2} particles of the composite powder. The as-formed, nanostructured, {gamma}-Al{sub 2}O{sub 3}/TiO{sub 2} composite powder exhibited a 2.7-times-higher photo-activity in the near-UV region compared to commercially available TiO{sub 2} (Degusa P25), as monitored by the photo-decomposition of a methylene blue (MB) dye.

  13. DNA Double-Strand Break Analysis by {gamma}-H2AX Foci: A Useful Method for Determining the Overreactors to Radiation-Induced Acute Reactions Among Head-and-Neck Cancer Patients

    SciTech Connect

    Goutham, Hassan Venkatesh; Mumbrekar, Kamalesh Dattaram; Vadhiraja, Bejadi Manjunath; Fernandes, Donald Jerard; Sharan, Krishna; Kanive Parashiva, Guruprasad; Kapaettu, Satyamoorthy; Bola Sadashiva, Satish Rao

    2012-12-01

    Purpose: Interindividual variability in normal tissue toxicity during radiation therapy is a limiting factor for successful treatment. Predicting the risk of developing acute reactions before initiation of radiation therapy may have the benefit of opting for altered radiation therapy regimens to achieve minimal adverse effects with improved tumor cure. Methods and Materials: DNA double-strand break (DSB) induction and its repair kinetics in lymphocytes of head-and-neck cancer patients undergoing chemoradiation therapy was analyzed by counting {gamma}-H2AX foci, neutral comet assay, and a modified version of neutral filter elution assay. Acute normal tissue reactions were assessed by Radiation Therapy Oncology Group criteria. Results: The correlation between residual DSBs and the severity of acute reactions demonstrated that residual {gamma}-H2AX foci in head-and-neck cancer patients increased with the severity of oral mucositis and skin reaction. Conclusions: Our results suggest that {gamma}-H2AX analysis may have predictive implications for identifying the overreactors to mucositis and skin reactions among head-and-neck cancer patients prior to initiation of radiation therapy.

  14. Statistical theory of light nucleus reactions with 1p-shell light nuclei

    NASA Astrophysics Data System (ADS)

    Xiaojun, Sun; Jingshang, Zhang

    2017-09-01

    The 1p-shell light elements (Li, Be, B, C, N, and O) had long been selected as the most important materials for improving neutron economy in thermal and fast fission reactors and in the design of accelerator-driven spallation neutron sources. A statistical theory of light nucleus reactions (STLN) is proposed to describe the double-differential cross sections for both neutron and light charged particle induced nuclear reactions with 1p-shell light nuclei. The dynamics of STLN is described by the unified Hauser-Feshbach and exciton model, in which the angular momentum and parity conservations are strictly considered in equilibrium and pre-equilibrium processes. The Coulomb barriers of the incoming and outgoing charged particles, which significantly influence the open channels of the reaction, can be reasonably considered in incident channel and different outgoing channels. In kinematics, the recoiling effects in various emission processes are strictly taken into account. The analytical energy and angular spectra of the reaction products in sequential and simultaneous emission processes are obtained in terms of the new integral formula proposed in our recent paper. Taking 12C(n, xn), 9Be(n, xn), 16O(n, xn), and 9Be(p,xn) reactions as examples, we had calculated the double-differential cross sections of outgoing neutrons and compared with the experimental data. In addition, we had also calculated the partition and total kerma coefficients for 12C(n, xn) and 16O(n, xn) reactions, respectively. The existing experimental data can be remarkably well reproduced by STLN, which had been used to set up file-6 in CENDL database.

  15. Usefulness of thresholds for smear review of neutropenic samples analyzed with a Sysmex XN-10 analyzer.

    PubMed

    Ronez, Emily; Geara, Carole; Coito, Sylvie; Jacqmin, Hugues; Cornet, Edouard; Troussard, Xavier; Chatelain, Bernard; Mullier, François

    2017-10-01

    Neutropenia is one of the main criteria for a blood smear review. The objective of this study was to compare the thresholds proposed by the international consensus group for hematology review (1.0 10(9)/L) and the French speaking Group for Cellular Haematology (1.5 10(9)/L) in terms of the number of useless smears. We collected 112,097 analyzed samples from four laboratories equipped with XN instruments (Sysmex, Kobe, Japan) during early 2016. The only exclusion criterion was a leucocyte count below 0.5 10(9)/L. In the absence of abnormal cells and/or morphology suggesting haematological disease, samples were classified as 'negative for morphology' and the differential from the XN-10 was reported. These smear procedures were considered as uninformative. Some 2202 samples met the criterion for neutropenia (<1.5 10(9)/L) for slide review representing 1.96% of the total. These included 1031 with neutropenia alone and 1171 neutropenia plus other abnormalities. Of the 1031 with neutropenia alone, 886 had a neutrophil count between 1.0 10(9)/L and 1.5 10(9)/L. The smear was uninformative for all of these samples. In conclusion, microscopic examination of a blood smear provided very limited information in cases of neutropenia without other abnormalities.

  16. Asteroid Lightcurve Analysis at Riverland Dingo Observatory (RDO): 185 Eunike, (17252) 2000 GJ127, and (152858) 1999 XN35

    NASA Astrophysics Data System (ADS)

    Hills, Kevin

    2013-04-01

    Lightcurves for three asteroids selected from the Collaborative Asteroid Lightcurve Link (CALL; Warner 2011) were obtained at Riverland Dingo Observatory (RDO) in the period October 13 through December 5, 2012: 185 Eunike, (17252) 2000 GJ127, and (152858) 1999 XN35.

  17. Development of epitaxial AlxSc1-xN for artificially structured metal/semiconductor superlattice metamaterials

    DOE PAGES

    Sands, Timothy D.; Stach, Eric A.; Saha, Bivas; ...

    2015-02-01

    Epitaxial nitride rocksalt metal/semiconductor superlattices are emerging as a novel class of artificially structured materials that have generated significant interest in recent years for their potential application in plasmonic and thermoelectric devices. Though most nitride metals are rocksalt, nitride semiconductors in general have hexagonal crystal structure. We report rocksalt aluminum scandium nitride (Al,Sc)N alloys as the semiconducting component in epitaxial rocksalt metal/semiconductor superlattices. The AlxSc1-xN alloys when deposited directly on MgO substrates are stabilized in a homogeneous rocksalt (single) phase when x < 0.51. Employing 20 nm TiN as a seed layer on MgO substrates, the homogeneity range for stabilizingmore » the rocksalt phase has been extended to x < 0.82 for a 120 nm film. The rocksalt AlxSc1-xN alloys show moderate direct bandgap bowing with a bowing parameter, B = 1.41 ± 0.19 eV. The direct bandgap of metastable rocksalt AlN is extrapolated to be 4.70 ± 0.20 eV. The tunable lattice parameter, bandgap, dielectric permittivity, and electronic properties of rocksalt AlxSc1-xN alloys enable high quality epitaxial rocksalt metal/AlxSc1-xN superlattices with a wide range of accessible metamaterials properties.« less

  18. Ab initio study of {sup 2}H(d,{gamma}){sup 4}He, {sup 2}H(d,p){sup 3}H, and {sup 2}H(d,n){sup 4}He reactions and the tensor force

    SciTech Connect

    Arai, K.; Aoyama, S.; Suzuki, Y.; Descouvemont, P.; Baye, D.

    2012-11-12

    The {sup 2}H(d,p){sup 3}H, {sup 2}H(d,n){sup 3}He, and {sup 2}H(d,{gamma}){sup 4}He reactions at low energies are studied with realistic nucleon-nucleon interactions in an ab initio approach. The obtained astrophysical S-factors are all in very good agreement with experiment. The most important channels for both transfer and radiative capture are all found to dominate thanks to the tensor force.

  19. Asymptotic Normalization Coefficients from the {sup 15}N({sup 3}He,d){sup 16}O Reaction and the Astrophysical Factor for the {sup 15}N(p,{gamma}){sup 16}O Capture

    SciTech Connect

    Burjan, V.; Bem, P.; Hons, Z.; Kroha, V.; Mrazek, J.; Novak, J.; Piskor, S.; Simeckova, E.; Vincour, J.; Cherubini, S.; La Cognata, M.; Pizzone, R. G.; Romano, S.; Spitaleri, C.; Tumino, A.; Gagliardi, C. A.; Mukhamedzhanov, A. M.; Plunkett, A.; Trache, L.; Tribble, R. E.

    2008-05-12

    The angular distributions of the {sup 15}N({sup 3}He,d){sup 16}O reaction were measured with the aim to determine the direct capture rate of the astrophysical reaction {sup 15}N(p, {gamma}){sup 16}O by deducing asymptotic normalization coefficients (ANC). The {sup 15}N(p,{gamma}){sup 16}O reaction is a part of the CNO cycle having importance in the nucleosynthesis of the N and O isotopes. The measurement was carried out on the cyclotron U120M of NPI CAS at the energy 25.74 MeV of {sup 3}He ions in a gas chamber containing the high purity {sup 15}N isotope. The preliminary results of corresponding spectroscopic factors and ANC's were used for the estimation of the S-factor for the direct capture {sup 15}N(p,{gamma}){sup 16}O. Using the widths of the resonances E{sub R} = 312 and 962 keV, the total S-factor was determined within the framework of the R-matrix approach.

  20. Synthesis of a peroxime proliferator activated receptor (PPAR) alpha/gamma agonist via stereocontrolled Williamson ether synthesis and stereospecific SN2 reaction of S-2-chloro propionic acid with phenoxides.

    PubMed

    Aikins, James A; Haurez, Michael; Rizzo, John R; Van Hoeck, Jean-Pierre; Brione, Willy; Kestemont, Jean-Paul; Stevens, Christophe; Lemair, Xavier; Stephenson, Gregory A; Marlot, Eric; Forst, Mindy; Houpis, Ioannis N

    2005-06-10

    The stereospecific synthesis of the PPAR alpha/gamma agonist 1 was accomplished via ethylation of the optically pure trihydroxy derivative 6, itself derived via an enzymatic resolution. The ethylation can be accomplished without epimerization only under strict control of the reaction conditions and the choice of base (sodium tert-amylate), temperature (-30 degrees C), order of addition, and solvent (DMF). The key diastereospecific SN2 reaction of the phenol 4 with S-2-chloropropionic acid is best achieved via the sodium phenoxide of 4 derived from Na0 as the reagent of choice. The structure elucidation and key purification protocols to achieve pharmaceutical purity will also be described.

  1. Radiation chemical effects in experiments to study the reaction of glass in an environment of gamma-irradiated air, groundwater, and tuff

    SciTech Connect

    Van Konynenburg, R.A.

    1986-05-02

    The results of experiments performed by John K. Bates et al. on the reaction of nuclear waste glass with a gamma-irradiated 90{sup 0}C aqueous solution were analyzed using theory developed from past research in radiation chemistry. The aqueous solution they used is similar to what would be expected in a water-saturated environment in a nuclear waste repository in tuff. The purpose of our study was to develop an understanding of the radiation-chemical processes that occurred in the Bates et al. experiments so the results could be applied to the design and performance analysis of a proposed repository in unsaturated tuff in Nevada. For the Bates et al. experiments at the highest dose (269 Mrad), which originally contained about 16 ml of "equilibrated" water taken from Nevada Test Site Well J-13 and 5.4 ml of air, we predicted that water decomposition to H{sub 2} and O{sub 2} would produce a pressure increase of at least 1.0 MPa at 20{sup 0}C. We also predicted that nitrogen fixation from the air would occur, producing an increase of 1.6 x 10{sup -4} M in total fixed nitrogen concentration in solution. In addition, an equimolar production of H{sup +} would occur, which would be buffered by the HCO{sub 3}{sup -} in the water. The fixed nitrogen in solution was predicted to be present as NO{sub 2}{sup -} and NO{sub 3}{sup -} with the ratio influenced by the presence of materials catalytic to the decomposition of H{sub 2}O{sub 2}. We found reasonable agreement between our predictions and the observations of Bates et al., where comparisons were possible. We apply the results to the proposed Nevada repository to the degree possible, given the different expected conditions.

  2. Ga{sub 1-x}Mn{sub x}N epitaxial films with high magnetization

    SciTech Connect

    Kunert, G.; Kruse, C.; Figge, S.; Hommel, D.; Dobkowska, S.; Jakiela, R.; Stefanowicz, W.; Sawicki, M.; Li, Tian; Bonanni, A.; Reuther, H.; Grenzer, J.; Borany, J. von; Dietl, T.

    2012-07-09

    We report on the fabrication of pseudomorphic wurtzite Ga{sub 1-x}Mn{sub x}N grown on GaN with Mn concentrations up to 10% using molecular beam epitaxy. According to Rutherford backscattering, the Mn ions are mainly at the Ga-substitutional positions, and they are homogeneously distributed according to depth-resolved Auger-electron spectroscopy and secondary-ion mass-spectroscopy measurements. A random Mn distribution is indicated by transmission electron microscopy, and no Mn-rich clusters are present for optimized growth conditions. A linear increase of the c-lattice parameter with increasing Mn concentration is found using x-ray diffraction. The ferromagnetic behavior is confirmed by superconducting quantum-interference measurements showing saturation magnetizations of up to 150 emu/cm{sup 3}.

  3. Origin of background electron concentration in InxGa1-xN alloys

    DOE PAGES

    Pantha, B. N.; Wang, H.; Khan, N.; ...

    2011-08-15

    The origin of high background electron concentration (n) in InxGa1-xN alloys has been investigated. A shallow donor was identified as having an energy level (ED1) that decreases with x (ED1 = 16 meV at x = 0 and ED1 = 0 eV at x ~ 0.5) and that crossover the conduction band at x ~ 0.5. This shallow donor is believed to be the most probable cause of high n in InGaN. This understanding is consistent with the fact that n increases sharply with an increase in x and becomes constant for x > 0.5. A continuous reduction in nmore » was obtained by increasing the V/III ratio during the epilayer growth, suggesting that nitrogen vacancy-related impurities are a potential cause of the shallow donors and high background electron concentration in InGaN« less

  4. Isomeric yield ratios of 87m,gY from different nuclear reactions

    NASA Astrophysics Data System (ADS)

    Naik, H.; Kim, G. N.; Kim, K.; Zaman, M.; Sahid, M.; Yang, S.-C.; Lee, M. W.; Kang, Y. R.; Shin, S. G.; Cho, M.-H.; Goswami, A.; Song, T. Y.

    2014-07-01

    The independent isomeric yield ratios of 87m,gY produced from the 93Nb( γ, α2n) and natZr( γ, p xn) reactions with the end-point bremsstrahlung energy of 45-70 MeV have been determined by an off-line γ-ray spectrometric technique using 100 MeV electron linac at the Pohang accelerator laboratory, Korea. The isomeric yield ratios of 87m,gY were also determined from the natZr(p, αxn) and the 89Y(p,p2n) reactions with E P = 15-45 MeV as well as those from the 89Y( α, α2n) reaction with E α = 32-43 MeV using the MC-50 cyclotron at the Korea Institute of Radiological and Medical Science, Korea. The isomeric yield ratios of 87m,gY from the present work in the 93Nb( γ, α2n), natZr( γ, p xn), natZr(p, αxn), 89Y(p,p2n), and 89Y( α, α2n) reactions were compared with those of the literature data in the 85Rb( α, 2n), the 86,87,88Sr(d, xn), 89Y(n,3n), and the 89Y( γ, 2n) reactions to examine the role of target, projectiles, and ejectiles through compound nucleus excitation energy and input angular momentum. The isomeric yield ratios of 87m,gY in the above eleven reactions were also calculated using the computer code TALYS 1.4 and compared with the experimental data. The different behaviors between photon- and neutron-induced reactions and charged-particle-induced reactions are discussed from the viewpoint of compound and non-compound (pre-equilibrium) process.

  5. Synthesis of a galacto-configured C-ketoside-based gamma-sugar-amino acid and its use in peptide coupling reactions.

    PubMed

    Schweizer, Frank; Hindsgaul, Ole

    2006-07-24

    Gamma-sugar-amino acid analogues in the form of C-ketosides can be prepared in 5-6 steps starting from D-galactono-1,5-lactone. The key step in the synthesis is the trimethylsilyl trifluoromethanesulfonate (TMSOTf) promoted C-glycosylation of 2-deoxy-3-ulopyranosonates with trimethylsilyl cyanide. Hydrogenation of the resulting beta-cyano esters provides C-ketoside-based gamma-sugar-amino acids that serve as building blocks for the synthesis of unnatural neoglycopeptides.

  6. Magnetic and magneto-transport properties of Ga 1-xMn xN grown by MOCVD

    NASA Astrophysics Data System (ADS)

    Yang, Xuelin; Chen, Zhitao; Wu, Jiejun; Pan, Yaobo; Zhang, Yan; Yang, Zhijian; Yu, Tongjun; Zhang, Guoyi

    2007-07-01

    The Ga 1-xMn xN epitaxial films were grown by metalorganic chemical vapor deposition (MOCVD) with tricarbonyl (methycyclopentadienyl) manganese ((MCP) 2Mn) as dopant source. Magnetic measurements indicate that the films are n-type conductivity ( x=0.01), ferromagnetic ordering with Curie temperature above room temperature. The magnetic moment per Mn atom decreases when the Mn concentration changes from 0.01 to 0.03. Magneto-transport properties were performed in the temperature range of 2-300 K. The magneto-resistance (MR) changes from negative effect to positive effect with increasing temperature. The negative MR effect at low temperature is due to the reduction of the magnetic scattering of the Mn ions under the applied magnetic field. Furthermore, the zero-field-cooled (ZFC)/field-cooled (FC) and MR behavior at low temperature confirm that the ferromagnetism and paramagnetism coexist in Ga 1-xMn xN films.

  7. Gamma Knife

    MedlinePlus

    ... equipment? How is safety ensured? What is this equipment used for? The Gamma Knife® and its associated ... in size. top of page How does the equipment work? The Gamma Knife® utilizes a technique called ...

  8. A new measurement of the rare decay eta -> pi^0 gamma gamma with the Crystal Ball/TAPS detectors at the Mainz Microtron

    SciTech Connect

    Nefkens, B M; Prakhov, S; Aguar-Bartolom��, P; Annand, J R; Arends, H J; Bantawa, K; Beck, R; Bekrenev, V; Bergh��user, H; Braghieri, A; Briscoe, W J; Brudvik, J; Cherepnya, S; Codling, R F; Collicott, C; Costanza, S; Danilkin, I V; Denig, A; Demissie, B; Dieterle, M; Downie, E J; Drexler, P; Fil'kov, L V; Fix, A; Garni, S; Glazier, D I; Gregor, R; Hamilton, D; Heid, E; Hornidge, D; Howdle, D; Jahn, O; Jude, T C; Kashevarov, V L; K��ser, A; Keshelashvili, I; Kondratiev, R; Korolija, M; Kotulla, M; Koulbardis, A; Kruglov, S; Krusche, B; Lisin, V; Livingston, K; MacGregor, I J; Maghrbi, Y; Mancel, J; Manley, D M; McNicoll, E F; Mekterovic, D; Metag, V; Mushkarenkov, A; Nikolaev, A; Novotny, R; Oberle, M; Ortega, H; Ostrick, M; Ott, P; Otte, P B; Oussena, B; Pedroni, P; Polonski, A; Robinson, J; Rosner, G; Rostomyan, T; Schumann, S; Sikora, M H; Starostin, A; Strakovsky, I I; Strub, T; Suarez, I M; Supek, I; Tarbert, C M; Thiel, M; Thomas, A; Unverzagt, M; Watts, D P; Werthmueller, D; Witthauer, L

    2014-08-01

    A new measurement of the rare, doubly radiative decay eta->pi^0 gamma gamma was conducted with the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. New data on the dependence of the partial decay width, Gamma(eta->pi^0 gamma gamma), on the two-photon invariant mass squared, m^2(gamma gamma), as well as a new, more precise value for the decay width, Gamma(eta->pi^0 gamma gamma) = (0.33+/-0.03_tot) eV, are based on analysis of 1.2 x 10^3 eta->pi^0 gamma gamma decays from a total of 6 x 10^7 eta mesons produced in the gamma p -> eta p reaction. The present results for dGamma(eta->pi^0 gamma gamma)/dm^2(gamma gamma) are in good agreement with previous measurements and recent theoretical calculations for this dependence.

  9. Synthesis of different chiral amino gamma-butyrolactones and amino gamma-butenolides.

    PubMed

    Concellón, José M; Riego, Estela; Bernad, Pablo L

    2002-04-18

    Different transformations of chiral epoxy esters 1 afford two different amino gamma-butyrolactones 2 and 6, and amino gamma-butenolides 8, by different nucleophilic opening-closing processes. [reaction: see text

  10. The changes in small metal cluster size with adsorption Be13Xn, X = H, O, S, Cl and F

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.

    1985-01-01

    The Be-Be and Be-adsorbate distances are optimized for small Be13Xn clusters,s assuming only two independent degrees of freedom. Results for chemisorption into the three-fold hollows are quite similar to those found for small metal clusters on supports. It is predicted that Cl and F will have the same effect on the metal-metal bond lengths, and so will O and S.

  11. Structural and electronic properties of GaN nanowires with embedded InxGa1-xN nanodisks

    NASA Astrophysics Data System (ADS)

    Kioseoglou, J.; Pavloudis, Th.; Kehagias, Th.; Komninou, Ph.; Karakostas, Th.; Latham, C. D.; Rayson, M. J.; Briddon, P. R.; Eickhoff, M.

    2015-07-01

    In the present study, the effects of various types of strain and indium concentration on the total energy and optoelectronic properties of GaN nanowires (NWs) with embedded InxGa1-xN nanodisks (NDs) are examined. In particular, the bi-axial, hydrostatic, and uniaxial strain states of the embedded InxGa1-xN NDs are investigated for multiple In concentrations. Density functional theory is employed to calculate the band structure of the NWs. The theoretical analysis finds that the supercell-size-dependent characteristics calculated for our 972-atom NW models are very close to the infinite supercell-size limit. It is established that the embedded InxGa1-xN NDs do not induce deep states in the band gap of the NWs. A bowing parameter of 1.82 eV is derived from our analysis in the quadratic Vegard's formula for the band gaps at the various In concentrations of the investigated InxGa1-xN NDs in GaN NW structures. It is concluded that up to ˜10% of In, the hydrostatic strain state is competitive with the bi-axial due to the radial absorption of the strain on the surfaces. Above this value, the dominant strain state is the bi-axial one. Thus, hydrostatic and bi-axial strain components coexist in the embedded NDs, and they are of different physical origin. The bi-axial strain comes from growth on lattice mismatched substrates, while the hydrostatic strain originates from the lateral relaxation of the surfaces.

  12. Chemically ordered Al{sub x}Ga{sub 1-x}N alloys: Spontaneous formation of natural quantum wells

    SciTech Connect

    Albrecht, M.; Lymperakis, L.; Neugebauer, J.; Northrup, J.E.; Kirste, L.; Leroux, M.; Grzegory, I.; Porowski, S.; Strunk, H.P.

    2005-01-15

    We combine transmission electron microscopy, high-resolution x-ray diffraction, cathodoluminescence, and photoluminescence experiments with first-principles calculations to study the formation, thermodynamic stability, structural, and optical properties of chemically ordered Al{sub x}Ga{sub 1-x}N alloys (0x}N alloys. The ordered alloys have unique properties: (i) the band gap is redshifted up to 110 meV with respect to the disordered alloy of the same composition and (ii) the band gap reduction is caused by localization of the band edge wave functions in the GaN layer. Ordered Al{sub x}Ga{sub 1-x}N thus can be seen as a natural quantum well structure where electrons and holes are localized and confined in monolayer GaN quantum wells.

  13. ECR-assisted MBE growth of In 1- xGa xN heteroepitaxial films on Si

    NASA Astrophysics Data System (ADS)

    Yodo, Tokuo; Kitayama, Yasunari; Miyaki, Kazunari; Yona, Hiroaki; Harada, Yoshiyuki

    2004-10-01

    We have investigated characteristics of hexagonal- ( α-) In 1- xGa xN alloy films grown on Si(111) substrates with residual O impurities below 1% (estimated to be ˜ 0.5˜ 1%). The abnormally high incorporation efficiency of Ga atoms in In 1- xGa xN under the III-family-rich condition was suppressed under an N-rich condition: the surface morphology became mirror-like morphology without In or/and Ga droplets on the surface and the Ga composition (x) was well-controlled as a linear function of Ga beam flux pressure under the condition. Although the band-gap energies of α-In 1- xGa xN films agreed very well with the results of Y. Nanishi, Y. Saito and T. Yamaguchi [Japan. J. Appl. Phys. 42 (2003) 2549] in the high x-region of x≧0.7, they largely deflected from their data toward the higher energy side in the x-region of x<0.7. This large deflection is not explainable by phase separation, because phase separation becomes heavier particularly in the high x-region. We suspect the influence of residual O impurities at lower than 1% in the alloy films to be the cause of the large deflection.

  14. Role of biaxial strain and microscopic ordering for structural and electronic properties of InxGa1 -xN

    NASA Astrophysics Data System (ADS)

    Cui, Ying; Lee, Sangheon; Freysoldt, Christoph; Neugebauer, Jörg

    2015-08-01

    The structural and electronic properties of InxGa1 -xN alloys are studied as a function of c -plane biaxial strain and In ordering by density functional theory with the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional. A nonlinear variation of the c lattice parameter with In content is observed in biaxial strain and should be taken into account when deducing In content from interplanar distances. From compressive to tensile strain, the character of the top valence-band state changes, leading to a nonlinear variation of the band gap in InxGa1 -xN . Interestingly, the well-known bowing of the InxGa1 -xN band gap is largely removed for alloys grown strictly coherently on GaN, while the actual values for band gaps at x <0.33 are hardly affected by strain. Ordering plays a minor role for lattice constants but may induce changes of the band gap up to 0.15 eV.

  15. Asymptotic normalization coefficients from the {sup 20}Ne({sup 3}He, d){sup 21}Na reaction and astrophysical factor for {sup 20}Ne(p,{gamma}){sup 21}Na

    SciTech Connect

    Mukhamedzhanov, A.M.; Gagliardi, C.A.; Tribble, R.E.; Bem, P.; Burjan, V.; Kroha, V.; Novak, J.; Piskor, S; Simeckova, E.; Vesely, F.; Vincour, J.; Irgaziev, B.F.

    2006-03-15

    The {sup 20}Ne(p,{gamma}){sup 21}Na reaction rate at stellar energies is dominated by capture to the ground state through the tail of a subthreshold resonance state at an excitation energy of 2425 keV in {sup 21}Na. Both resonant and direct capture contribute to the reaction rate while direct captures to other bound states are negligible. The overall normalization of direct capture to the subthreshold state is determined by the asymptotic normalization coefficient (ANC). Simultaneously this ANC determines the proton partial width of the subthreshold resonance state. To determine the ANC, the {sup 20}Ne({sup 3}He,d){sup 21}Na proton transfer reaction has been measured, at an incident energy of 25.83 MeV. Angular distributions for proton transfer to the ground and first three excited states were measured, and ANCs were then extracted from comparison with distorted-wave Born approximation calculations. Using these ANCs, we calculated the astrophysical factor for {sup 20}Ne(p,{gamma}){sup 21}Na. Our total astrophysical factor is S(0)=5900{+-}1200 keV b. Our analysis confirms that only nonresonant and resonant captures through the subthreshold state are important.

  16. Sperm gamma-aminobutyric acid type A receptor delta subunit (GABRD) and its interaction with purinergic P2X2 receptors in progesterone-induced acrosome reaction and male fertility.

    PubMed

    Xu, Wenming; Wang, Ke; Chen, Yan; Liang, Xiao Tong; Yu, Mei Kuen; Yue, Huanxun; Tierney, M Louise

    2017-02-13

    The mechanism underlying the non-genomic action of progesterone in sperm functions and related Ca2+ mobilisation remains elusive. Herein we report the expression of gamma-aminobutyric acid type A receptor delta subunit (GABRD) in human and rodent sperm and its involvement in mediating the progesterone-induced acrosome reaction. GABRD was localised in the sperm head/neck region. A δ(392-422)-specific inhibitory peptide against GABRD blocked the progesterone-induced acrosome reaction and the associated increase in intracellular Ca2+. Similarly, an inhibitory effect against both progesterone-induced Ca2+ influx and the acrosome reaction was observed with a P2X2 receptor antagonist. The lack of synergism between the GABRD and P2X2 inhibitors suggests that these two receptors are playing a role in the same pathway. Furthermore, a co-immunoprecipitation experiment demonstrated that GABRD could undergo protein-protein interactions with the Ca2+-conducting P2X2 receptor. This interaction between the receptors could be reduced following progesterone (10μM) inducement. Significantly reduced GABRD expression was observed in spermatozoa from infertile patients with reduced acrosome reaction capacity, suggesting that normal expression of GABRD is critical for the sperm acrosome reaction and thus male fertility. The results of the present study indicate that GABRD represents a novel progesterone receptor or modulator in spermatozoa that is responsible for the progesterone-induced Ca2+ influx required for the acrosome reaction through its interaction with the P2X2 receptor.

  17. Effects of {Delta}-isobar degrees of freedom on the reactions {sup 3}He(n,{gamma}){sup 4}He and {sup 3}He(p,e{sup +}{nu}{sub e}){sup 4}He at low-energy

    SciTech Connect

    Schiavilla, R.

    1991-12-31

    The cross sections of the radiative {sup 3}He(n,{gamma}){sup 4}He and weak {sup 3}He(p,e{sup +}{nu}{sub e}){sup 4}He capture reactions at thermal neutron and keV proton energies have been calculated with the Variational Monte Carlo method. The ground state and low-energy continuum wave functions have been determined variationally from a realistic Hamiltonian, and include both nucleon and {Delta}-isobar degrees of freedom. The electroweak transition operator contains one- and two-body components in the N + {Delta} Hilbert space.

  18. Effects of. Delta. -isobar degrees of freedom on the reactions sup 3 He(n,. gamma. ) sup 4 He and sup 3 He(p,e sup +. nu. sub e ) sup 4 He at low-energy

    SciTech Connect

    Schiavilla, R.

    1991-01-01

    The cross sections of the radiative {sup 3}He(n,{gamma}){sup 4}He and weak {sup 3}He(p,e{sup +}{nu}{sub e}){sup 4}He capture reactions at thermal neutron and keV proton energies have been calculated with the Variational Monte Carlo method. The ground state and low-energy continuum wave functions have been determined variationally from a realistic Hamiltonian, and include both nucleon and {Delta}-isobar degrees of freedom. The electroweak transition operator contains one- and two-body components in the N + {Delta} Hilbert space.

  19. Nuclear gamma rays from energetic particle interactions

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Kozlovsky, B.; Lingenfelter, R. E.

    1978-01-01

    Gamma ray line emission from nuclear deexcitation following energetic particle reactions is evaluated. The compiled nuclear data and the calculated gamma ray spectra and intensities can be used for the study of astrophysical sites which contain large fluxes of energetic protons and nuclei. A detailed evaluation of gamma ray line production in the interstellar medium is made.

  20. Luminescence studies in InxGa1-xN epitaxial layers with different indium contents

    NASA Astrophysics Data System (ADS)

    Wu, T. Y.; Chang, C. C.; Tiong, K. K.; Lee, Y. C.; Hu, S. Y.; Lin, L. Y.; Lin, T. Y.; Feng, Z. C.

    2013-08-01

    The optical properties of InxGa1-xN epitaxial layers (x = 0.02, 0.04, 0.11, 0.15, 0.30 and 0.33) grown by metalorganic chemical vapor deposition (MOCVD) have been investigated by temperature-dependent photoluminescence (PL) measurement. The surface morphologies of InGaN samples are studied by scanning electron microscopy (SEM) images. The PL feature at 12 K has shown an increase in full-width at half-maximum (FWHM) with increasing In content. An anomalous S-shaped temperature dependence of the PL peak energy exhibited by InGaN films with higher In content enabled the evaluation of the exciton localization energy. The broadened FWHM and S-shaped emission shift are attributed to larger compositional fluctuation due to compositional inhomogeneity of In. Additionally, the luminescence mechanism relating to the phase separation has to be considered for the much larger FWHM value and the pronounced S-shaped behavior for the InGaN samples with In content of 0.30 and 0.33.

  1. Sample stability for complete blood cell count using the Sysmex XN haematological analyser

    PubMed Central

    Daves, Massimo; Zagler, Elmar M.; Cemin, Roberto; Gnech, Flora; Joos, Alexandra; Platzgummer, Stefan; Lippi, Giuseppe

    2015-01-01

    Background Sample stability is a crucial aspect for the quality of results of a haematology laboratory. This study was conducted to investigate the reliability of haematological testing using Sysmex XN in samples stored for up to 24 h at different temperatures. Materials and methods Haematological tests were performed on whole blood samples collected from 16 ostensibly healthy outpatients immediately after collection and 3 h, 6 h or 24 h afterwards, with triple aliquots kept at room temperature, 4 °C or 37 °C. Results No meaningful bias was observed after 3 h under different storage conditions, except for red blood cell distribution width (RDW) and platelet count (impedance technique, PLT-I) at 37 °C. After 6 h, meaningful bias was observed for mean corpuscular haemoglobin (MCH) and mean corpuscular volume (MCV) at room temperature, red blood cell (RBC) count, mean corpuscular haemoglobin concentration (MCHC), MCH, MCV and PLT-I at 4 °C, and RBC, RDW, MCHC, MCH and PLT-I at 37 °C. After 24 h, a meaningful bias was observed for MCHC, MCV, platelet count (fluorescent technique, PLT-F) and mean platelet volume (MPV) at room temperature, MCHC, MCV, PLT-I and MPV at 4 °C, and all parameters except RBC count and MPV at 37 °C. Discussion Great caution should be observed when analysing results of haematological tests conducted more than 3 h after sample collection. PMID:26057491

  2. InxAl1-xN chiral nanorods mimicking the polarization features of scarab beetles

    NASA Astrophysics Data System (ADS)

    Magnusson, R.; Birch, J.; Hsiao, C.-L.; Sandström, P.; Arwin, H.; Järrendahl, K.

    2015-03-01

    The scarab beetle Cetonia aurata is known to reflect light with brilliant colors and a high degree of circular polarization. Both color and polarization effects originate from the beetles exoskeleton and have been attributed to a Bragg reflection of the incident light due to a twisted laminar structure. Our strategy for mimicking the optical properties of the Cetonia aurata was therefore to design and fabricate transparent, chiral films. A series of films with tailored transparent structures of helicoidal InxAl1-xN nanorods were grown on sapphire substrates using UHV magnetron sputtering. The value of x is tailored to gradually decrease from one side to the other in each nanorod normal to its growth direction. This introduces an in-plane anisotropy with different refractive indices in the direction of the gradient and perpendicular to it. By rotating the sample during film growth the in-plane optical axis will be rotated from bottom to top and thereby creating a chiral film. Based on Muellermatrix ellipsometry, optical modeling has been done suggesting that both the exoskeleton of Cetonia aurata and our artificial material can be modeled by an anisotropic film made up of a stack of thin layers, each one with its in-plane optical axis slightly rotated with respect to the previous layer. Simulations based on the optical modeling were used to investigate how pitch and thickness of the film together with the optical properties of the constitutive materials affects the width and spectral position of the Bragg reflection band.

  3. Fragmented red cells reference range (Sysmex XN(®) automated blood cell counter).

    PubMed

    Lesesve, Jean-François; Daigney, Amandine; Henry, Sylvain; Speyer, Elodie

    2015-01-01

    Fragmented red cells (FRCs) is a new parameter automatedly determined by recent blood cell counters. Their count might be of interest because FRCs are supposed to reflect schistocytes counts measured on a stained peripheral blood smear observed under the microscope. But FRCs depend from the technical procedure used to detect them and thus reference ranges are device-dependent. The XN-9000(®) is one of the last model from Sysmex series. We aimed to establish reference range for FRCs, from 2389 controls. The mean ± SD was 0.32% ± 0.81, the median 0.02% (95% confidence interval ot the mean: 0.29-0.35%). We observed that the percentage of red blood cells with less than 17 pg of hemoglobin content (Hypo-He) was correlated to FRC increase, Hypo-He increase resulting in spurious FRCs majoration. FRCs reference range should be useful for: 1) laboratory staff in order to select which blood smears to check optically; 2) Sysmex company to set-up more optimal rules proposed with the counter (automated making of blood smear).

  4. Cluster-transfer reactions with radioactive beams: A spectroscopic tool for neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Bottoni, S.; Leoni, S.; Fornal, B.; Raabe, R.; Rusek, K.; Benzoni, G.; Bracco, A.; Crespi, F. C. L.; Morales, A. I.; Bednarczyk, P.; Cieplicka-Oryńczak, N.; Królas, W.; Maj, A.; Szpak, B.; Callens, M.; Bouma, J.; Elseviers, J.; De Witte, H.; Flavigny, F.; Orlandi, R.; Reiter, P.; Seidlitz, M.; Warr, N.; Siebeck, B.; Hellgartner, S.; Mücher, D.; Pakarinen, J.; Vermeulen, M.; Bauer, C.; Georgiev, G.; Janssens, R. V. F.; Balabanski, D.; Sferrazza, M.; Kowalska, M.; Rapisarda, E.; Voulot, D.; Lozano Benito, M.; Wenander, F.

    2015-08-01

    An exploratory experiment performed at REX-ISOLDE to investigate cluster-transfer reactions with radioactive beams in inverse kinematics is presented. The aim of the experiment was to test the potential of cluster-transfer reactions at the Coulomb barrier as a mechanism to explore the structure of exotic neutron-rich nuclei. The reactions 7Li(98Rb,α xn ) and 7Li(98Rb,t xn ) were studied through particle-γ coincidence measurements, and the results are presented in terms of the observed excitation energies and spins. Moreover, the reaction mechanism is qualitatively discussed as a transfer of a clusterlike particle within a distorted-wave Born approximation framework. The results indicate that cluster-transfer reactions can be described well as a direct process and that they can be an efficient method to investigate the structure of neutron-rich nuclei at medium-high excitation energies and spins.

  5. The neutron-gamma Feynman variance to mean approach: Gamma detection and total neutron-gamma detection (theory and practice)

    NASA Astrophysics Data System (ADS)

    Chernikova, Dina; Axell, Kåre; Avdic, Senada; Pázsit, Imre; Nordlund, Anders; Allard, Stefan

    2015-05-01

    Two versions of the neutron-gamma variance to mean (Feynman-alpha method or Feynman-Y function) formula for either gamma detection only or total neutron-gamma detection, respectively, are derived and compared in this paper. The new formulas have particular importance for detectors of either gamma photons or detectors sensitive to both neutron and gamma radiation. If applied to a plastic or liquid scintillation detector, the total neutron-gamma detection Feynman-Y expression corresponds to a situation where no discrimination is made between neutrons and gamma particles. The gamma variance to mean formulas are useful when a detector of only gamma radiation is used or when working with a combined neutron-gamma detector at high count rates. The theoretical derivation is based on the Chapman-Kolmogorov equation with the inclusion of general reactions and corresponding intensities for neutrons and gammas, but with the inclusion of prompt reactions only. A one energy group approximation is considered. The comparison of the two different theories is made by using reaction intensities obtained in MCNPX simulations with a simplified geometry for two scintillation detectors and a 252Cf-source. In addition, the variance to mean ratios, neutron, gamma and total neutron-gamma are evaluated experimentally for a weak 252Cf neutron-gamma source, a 137Cs random gamma source and a 22Na correlated gamma source. Due to the focus being on the possibility of using neutron-gamma variance to mean theories for both reactor and safeguards applications, we limited the present study to the general analytical expressions for Feynman-alpha formulas.

  6. Measurement of the gamma gamma* --> eta and gamma gamma* --> eta' transition form factors

    SciTech Connect

    del Amo Sanchez et al, P.

    2011-02-07

    We study the reactions e{sup +}e{sup -} {yields} e{sup +}e{sup -} {eta}{sup (/)} in the single-tag mode and measure the {gamma}{gamma}* {yields} {eta}{sup (/)} transition form factors in the momentum transfer range from 4 to 40 GeV{sup 2}. The analysis is based on 469 fb{sup -1} of integrated luminosity collected at PEP-II with the BABAR detector at e{sup +}e{sup -} center-of-mass energies near 10.6 GeV.

  7. Cell Population Data and reflex testing rules of cell analysis in pleural and ascitic fluids using body fluid mode on Sysmex XN-9000.

    PubMed

    Buoro, Sabrina; Mecca, Tommaso; Azzarà, Giovanna; Seghezzi, Michela; Dominoni, Paola; Crippa, Alberto; Ottomano, Cosimo; Lippi, Giuseppe

    2016-01-15

    Although optical microscopy (OM) remains the reference technique for analysis of ascitic (AF) and pleural (PF) fluids, novel hematological analyzers are equipped with modules for body fluid (BF) analysis. This study was aimed to analyze the performance of XN-BF module in Sysmex XN-9000, and to develop validation rules for automated cell counts in BFs. The evaluation of XN-BF module included assessment of carryover, Limit of Blank (LoB), Limit of Detection (LoD), Limit of Quantitation (LoQ), linearity, data comparison with OM, and development of rules for assisting the validation of automated analysis of BFs and activating reflex testing. The carryover was negligible. The LoB, LoD, LoQ and linearity were always excellent. The comparison with OM was characterized by Pearson's correlations ranging from r=0.50 to r=0.99 (p<0.001), modest bias and high diagnostic concordance (Area Under the Curve between 0.85 and 0.99). The use of instrument-specific cut-offs further increased diagnostic concordance. The implementation of reflex testing rules based on XN-BF data increased sensitivity and specificity of BFs classification to 0.98 and 0.95. Our results suggest that the XN-BF module on Sysmex-9000 may be a suitable alternative to OM for screening BF samples, especially when specific validation rules are used. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Band-edge exciton transitions in (Ga 1- xMn x)N diluted magnetic semiconductor films with above room temperature ferromagnetic transition

    NASA Astrophysics Data System (ADS)

    Jeon, H. C.; Kang, T. W.; Kim, T. W.; Cho, Y. H.

    2006-06-01

    (Ga 1- xMn x)N thin films grown on GaN buffer layers by using molecular beam epitaxy were investigated with the goal of producing diluted magnetic semiconductors (DMSs) with band-edge exciton transitions for applications in optomagnetic devices. The magnetization curve as a function of the magnetic field at 5 K indicated that ferromagnetism existed in the (Ga 1- xMn x)N thin films, and the magnetization curve as a function of the temperature showed that the ferromagnetic transition temperature of the (Ga 1- xMn x)N thin film was above room temperature. Photoluminescence and photoluminescence excitation spectra showed that band-edge exciton transitions in (Ga 1- xMn x)N thin films appeared. These results indicate that the (Ga 1- xMn x)N DMSs with a magnetic single phase hold promise for potential applications in spin optoelectronic devices in the blue region of the spectrum.

  9. Massive free-space optical 1xN fiber switch using an adaptive membrane mirror

    NASA Astrophysics Data System (ADS)

    Gonte, Frederic; Peter, Yves-Alain; Herzig, Hans Peter; Daendliker, Rene

    2002-02-01

    We present a 1xN switch for single mode fiber optical communication systems, which is composed of an array of fibers, an achromatic lens, and an adaptive membrane mirror. The working principle of the optical switch is as follows: the center fiber of the array delivers the input signal, this signal is collimated by the lens, back reflected on the membrane mirror and refocused by the lens to an other fiber. The addressing of the receiving fiber is made by lateral displacement of the lens. However, using the achromatic lens under off-axis conditions introduces aberrations, which cause coupling losses to the receiving single-mode fibers. The deformable membrane mirror is used to adaptively correct these aberrations. The optimization of the coupling efficiency is made with the help of a genetic algorithm. For each position of the lens, the optimized voltages on the electrodes of the membrane mirror can be stored during the calibration procedure and afterwards recalled during operation of the switch. A demonstrator has been set up with a commercially available linear array of 32 single-mode fibers disposed in V-grooves, an achromatic lens mounted on a two-dimensional translation stage, and a membrane mirror made of silicon nitride coated with aluminum and electro-statically activated by thirty-seven electrodes. To demonstrate the capabilities of the aberration correction we used the first fiber in the array as input fiber and optimized the coupling efficiency to all the other fibers in the array. We obtained insertion losses of less than 3 dB and a cross talk below 30 dB. These results prove the feasibility to build a switch with a two-dimensional array of more than 1000 addressable fibers.

  10. gamma. -hexachlorocyclohexane (. gamma. -HCH) activates washed rabbit platelets

    SciTech Connect

    Lalau-Keraly, C.; Delautier, D.; Benveniste, J.; Puiseux-Dao, S.

    1986-03-01

    In guinea-pig macrophages, ..gamma..-HCH triggers activation of the phosphatidylinositol cycle and Ca/sup 2 +/ mobilization. Since these two biochemical events are also involved in platelet activation, the authors examined the effects of ..gamma..-HCH on washed rabbit platelets. Release of /sup 14/C-serotonin (/sup 14/C-5HT) and ATP from platelets prelabelled with /sup 14/C-5HT was measured simultaneously with aggregation. ..gamma..-HCH induced shape-change, aggregation and release reaction of platelets. Maximal aggregation (89 arbitrary units, AU), was observed using 170 ..mu..M ..gamma..-HCH, and was associated with 38.1 +/- 6.9% and 161 +/- 48 nM for /sup 14/C-5HT and ATP release respectively (mean +/- 1 SD, n=3). Using 80 ..mu..M ..gamma..-HCH yielded 18 AU, 12.8 +/- 1.0% and 27 +/- 14 nM for aggregation, C-5HT and ATP release respectively (n=3). No effect was observed with 40 ..mu.. M ..gamma..-HCH. Aspirin (ASA), a cyclooxygenase blocker, did not affect ..gamma..-HCH-induced platelet activation. Apyrase (APY), an ADP scavenger, inhibited by 90% aggregation induced by 170 ..mu..M ..gamma..-HCH and slightly inhibited (15%) the /sup 14/C-5HT release. In the presence of both ASA and APY, 96% inhibition of aggregation and 48% inhibition of /sup 14/C-5HT release were observed. Thus, ..gamma..-HCH induced platelet activation in a dose-dependent manner ADP, but not cyclooxygenase-dependent arachidonate metabolites, is involved in ..gamma..-HCH-induced aggregation, whereas, both appear to play a role in ..gamma..-HCH-induced release reaction.

  11. Evaluation of the Flagging Performance of the Hematology Analyzer Sysmex XN Series on the Basis of "Q Values".

    PubMed

    Kweon, Oh Joo; Lee, Mi-Kyung; Kim, Hye Ryoun

    2017-08-31

    - In the XN series of hematology analyzers (Sysmex, Kobe, Japan), the probability of the presence of abnormal cells is indicated by flags based on Q values. - To evaluate the Q values performance of the Sysmex XN-20 modular analyzer. - The interinstrumental concordance, intrainstrumental precision, and diagnostic accuracy of Q values, with tested flags of "blasts/abnormal lymphocytes," "atypical lymphocytes," and "blasts," were investigated. - Absolute concordance rates in flagging between 2 analyzers ranged from 69.8% to 80.8%, and κ values ranged from 0.43 to 0.61. In samples with absolute related cell counts lower than 100/μL, the values ranged from 0.31 to 0.52. For intrainstrumental precision, standard deviations ranged from 4.8 to 23.9 for the blasts/abnormal lymphocytes, from 18.7 to 59.1 for the blasts, and from 11.0 to 23.0 for the atypical lymphocytes. Using a default Q value cutoff, diagnostic accuracy values based on the area under the curve, sensitivity, and specificity were, respectively, 0.910, 90.9%, and 72.2% for blasts/abnormal lymphocytes; 0.927, 84.9%, and 89.8% for blasts; and 0.865, 74.4%, and 84.9% for atypical lymphocytes. The diagnostic accuracy of Q values was much lower in samples with absolute related cell counts lower than 100/μL than in those 100/μL or higher. - Q values of the Sysmex XN-20 analyzer were found to be imprecise and irreproducible, especially with samples containing a small number of pathologic cells. Adjustments in the Q value threshold may help in the detection of these cells.

  12. First-Principles Calculations for the Structural and Electronic Properties of ScxAl1-xN Alloys

    NASA Astrophysics Data System (ADS)

    Mohammad, Rezek; Katircioğlu, Şenay

    2013-10-01

    The first-principles calculations based on Density Functional Theory (DFT) within generalized gradient approximation (GGA) of Engel-Vosko-Perdew-Wang and modified exact exchange potential of Becke-Johnson have been introduced for the structural and electronic properties of the ScxAl1-xN alloys, respectively. The present lattice constants calculated for the ScAlN alloys and the end compounds (AlN and ScN) are found to be in very good agreement with the available experimental and theoretical ones. The stable ground state structures of the ScxAl1-xN alloys are determined to be wurtzite for the Sc concentration less than 0.403 and rock-salt for the higher Sc concentrations. The present electronic band structure calculations within Becke-Johnson scheme are found to be capable of providing energy band gaps of the AlN and ScN compounds very close to the ones of the available experiments and expensive calculations. According to the calculations of Becke-Johnson potential, the ScxAl1-xN alloys in the wurtzite and zinc-blende structures are direct band gap materials for the Sc concentrations in the ranges of (0.056 ≤ x ≤ 0.833) and (0.03125 ≤ x ≤ 0.0625, 0.375 ≤ x ≤ 0.96875), respectively. However, the ScAlN alloys in the rock-salt phase are determined to be direct band gap materials for total range of the Sc concentration considered in this work. While the energy gaps of the RS-AlScN alloys are found to be extending from near ultraviolet to near infrared with a large (negative) bowing, the ones of the WZ-AlScN and ZB-AlScN alloys are determined to be varying in a small energy range around near ultraviolet with a small (negative) bowing.

  13. Curved-lattice epitaxial growth of In(x)Al(1-x)N nanospirals with tailored chirality.

    PubMed

    Hsiao, Ching-Lien; Magnusson, Roger; Palisaitis, Justinas; Sandström, Per; Persson, Per O Å; Valyukh, Sergiy; Hultman, Lars; Järrendahl, Kenneth; Birch, Jens

    2015-01-14

    Chirality, tailored by external morphology and internal composition, has been realized by controlled curved-lattice epitaxial growth of In(x)Al(1-x)N nanospirals. The curved morphology of the spiral segments is a result of a lateral compositional gradient while maintaining a preferred crystallographic growth direction, implying a lateral gradient in optical properties. Individual nanospirals show an asymmetric core-shell structure with curved basal planes. Mueller matrix spectroscopic ellipsometry shows that the tailored chirality is manifested in the polarization state of light reflected off the nanospirals.

  14. Temperature-controlled epitaxy of In{sub x}Ga{sub 1-x}N alloys and their band gap bowing

    SciTech Connect

    Liu, S. T.; Wang, X. Q.; Chen, G.; Zhang, Y. W.; Feng, L.; Huang, C. C.; Xu, F. J.; Tang, N.; Shen, B.; Sang, L. W.; Sumiya, M.

    2011-12-01

    In{sub x}Ga{sub 1-x}N alloys (0 {<=} x {<=} 1) have been grown on GaN/sapphire templates by molecular beam epitaxy. Growth temperature controlled epitaxy was proposed to modulate the In composition so that each In{sub x}Ga{sub 1-x}N layer was grown at a temperature as high as possible and thus their crystalline quality was improved. The bandgap energies of the In{sub x}Ga{sub 1-x}N alloys have been precisely evaluated by optical transmission spectroscopy, where the effect of residual strain and electron concentration (the Burstein-Moss effect) on the bandgap energy shift has been considered. Finally, a bowing parameter of {approx}1.9 {+-} 0.1 eV has been obtained by the well fitting In-composition dependent bandgap energy.

  15. Thick target neutron yields and spectra from the Li(d,xn) reaction at 35 MeV

    SciTech Connect

    Johnson, D.L.; Mann, F.M.; Watson, J.W.; Brady, F.P.; Ullmann, J.L.; Romero, J.L.; Castaneda, C.M.; Zanelli, C.I.; Wyckoff, W.G.

    1980-05-01

    Measurements were performed using a 35 MeV deuteron beam from the isochronous cyclotron at the University of California at Davis. Data were obtained using the time-of-flight technique with an NE213 liquid scintillator. One set of measurements was used to observe the neutron spectrum from approx. 1 MeV to approx. 50 MeV, the maximum kinematically allowed energy. Observation angles were from 0/sup 0/ to 150/sup 0/ with emphasis on forward angles. Spectral data below approx. 1.5 MeV had poor accuracy. It was felt that a significant fraction of the neutron yield might lie at still lower energies, therefore a second set of measurements was performed to investigate the spectra to as low an energy as possible. Additional measurements were performed with a target enriched in the isotope /sup 6/Li replacing the natural lithium target used in previous measurements. The main advantage of a /sup 6/Li target is that the maximum kinematically allowed neutron energy is only about 38 MeV, hence reducing shielding requirements. The experiments, preliminary results, and future needs will be described.

  16. Lattice damage and compositional changes in Xe ion irradiated InxGa1-xN (x = 0.32-1.0) single crystals

    SciTech Connect

    Zhang, Limin; Jiang, Weilin; Dissanayake, Amila C.; Peng, Jinxin; Ai, Wensi; Zhang, Jiandong; Zhu, Zihua; Wang, Tieshan; Shutthanandan, V.

    2016-06-27

    Lattice disorder and compositional changes in InxGa1-xN (x=0.32, 0.47, 0.7, 0.8 and 1.0) films on GaN/Al2O3 substrates, induced by room-temperature irradiation of 5 MeV Xe ions, have been investigated using both Rutherford backscattering spectrometry under ion-channeling conditions and time-of-flight secondary ion mass spectrometry. The results show that for a fluence of 3E13 cm-2, the relative level of lattice disorder in InxGa1-xN increases monotonically from 59% to 90% with increasing indium concentration x from 0.32 to 0.7; a further increase in x up to 1.0 leads to little increase in the disorder level. In contrast to Ga-rich InxGa1-xN (x=0.32 and 0.47), significant volume swelling of up to ~25% accompanied with oxidation in In-rich InxGa1-xN (x=0.7, 0.8 and 1.0) is observed. In addition, irradiation-induced atomic mixing occurs at the interface of In-rich InxGa1-xN and GaN. The results from this study indicate an extreme susceptibility of the high In-content InxGa1-xN to heavy-ion irradiation, and suggest that cautions must be exercised in applying ion-implantation techniques to these materials at room temperature. Further studies of the irradiation behavior at elevated temperatures are warranted.

  17. Lattice damage and compositional changes in Xe ion irradiated InxGa1-xN (x = 0.32-1.0) single crystals

    NASA Astrophysics Data System (ADS)

    Zhang, Limin; Jiang, Weilin; Dissanayake, Amila; Peng, Jinxin; Ai, Wensi; Zhang, Jiandong; Zhu, Zihua; Wang, Tieshan; Shutthanandan, Vaithiyalingam

    2016-06-01

    Lattice disorder and compositional changes in InxGa1-xN (x = 0.32, 0.47, 0.7, 0.8, and 1.0) films on GaN/Al2O3 substrates, induced by room-temperature irradiation of 5 MeV Xe ions, have been investigated using both Rutherford backscattering spectrometry under ion-channeling conditions and time-of-flight secondary ion mass spectrometry. The results show that for a fluence of 3 × 1013 cm-2, the relative level of lattice disorder in InxGa1-xN increases monotonically from 59% to 90% with increasing indium concentration x from 0.32 to 0.7; a further increase in x up to 1.0 leads to little increase in the disorder level. In contrast to Ga-rich InxGa1-xN (x = 0.32 and 0.47), significant volume swelling of up to ˜25% accompanied with oxidation in In-rich InxGa1-xN (x = 0.7, 0.8, and 1.0) is observed. In addition, irradiation-induced atomic mixing occurs at the interface of In-rich InxGa1-xN and GaN. The results from this study indicate an extreme susceptibility of the high In-content InxGa1-xN to heavy-ion irradiation, and suggest that cautions must be exercised in applying ion-implantation techniques to these materials at room temperature. Further studies of the irradiation behavior at elevated temperatures are warranted.

  18. Influence of the Al distribution on the structure, elastic properties, and phase stability of supersaturated Ti{sub 1-x}Al{sub x}N

    SciTech Connect

    Mayrhofer, P. H.; Music, D.; Schneider, J. M.

    2006-11-01

    Ti{sub 1-x}Al{sub x}N films and/or their alloys are employed in many industrial applications due to their excellent mechanical and thermal properties. Synthesized by plasma-assisted vapor deposition, Ti{sub 1-x}Al{sub x}N is reported to crystallize in the cubic NaCl (c) structure for AlN mole fractions below 0.4-0.91, whereas at larger Al contents the hexagonal ZnS-wurtzite (w) structure is observed. Here we use ab initio calculations to analyze the effect of composition and Al distribution on the metal sublattice on phase stability, structure, and elastic properties of c-Ti{sub 1-x}Al{sub x}N and w-Ti{sub 1-x}Al{sub x}N. We show that the phase stability of supersaturated c-Ti{sub 1-x}Al{sub x}N not only depends on the chemical composition but also on the Al distribution of the metal sublattice. An increase of the metastable solubility limit of AlN in c-Ti{sub 1-x}Al{sub x}N from 0.64 to 0.74 is obtained by decreasing the number of Ti-Al bonds. This can be understood by considering the Al distribution induced changes of the electronic structure, bond energy, and configurational entropy. This may in part explain the large variation of the metastable solubility limit reported in the literature.

  19. Fusion gamma diagnostics

    NASA Astrophysics Data System (ADS)

    Medley, S. S.; Cecil, F. E.; Cole, D.; Conway, M. A.; Wilkinson, F. J., III

    1985-05-01

    Nuclear reactions of interest in fusion research often possess a branch yielding prompt emission of gamma radiation in excess of 15 MeV which can be exploited to provide a new fusion reaction diagnostic having applications similar to conventional neutron emission measurements. Conceptual aspects of fusion gamma diagnostics are discussed with emphasis on application to the Tokamak Fusion Test Reactor (TFTR) during deuterium neutral beam heating of D-T and D-3He plasmas. Recent measurements of the D (T, γ)5He, D(3He, γ)5Li, and D(D, γ)4He branching ratios at low center-of-mass energy (30-100 keV) and of the response of a large volume Ne226 detector for gamma detection in high neutron backgrounds are presented. Using a well-shielded Ne226 detector during 20 MW-120 kV deuterium beam heating of a tritium plasma in TFTR, the D(T, γ)5He gamma signal level is estimated to be 3.5×105 cps.

  20. High pressure stability analysis and chemical bonding of Ti{sub 1-x}Zr{sub x}N alloy: A first principle study

    SciTech Connect

    Chauhan, Mamta; Gupta, Dinesh C. E-mail: mamta-physics@yahoo.co.in

    2016-05-23

    First-principles pseudo-potential calculations have been performed to analyze the stability of Ti{sub 1-x}Zr{sub x}N alloy under high pressures. The first order phase transition from B1 to B2 phase has been observed in this alloy at high pressure. The variation of lattice parameter with the change in concentration of Zr atom in Ti{sub 1-x}Zr{sub x}N is also reported in both the phases. The calculations for density of states have been performed to understand the alloying effects on chemical bonding of Ti-Zr-N alloy.

  1. Excitation functions for complete-fusion and transfer reactions in 4He interaction with 197Au nuclei

    NASA Astrophysics Data System (ADS)

    Kulko, A. A.; Demekhina, N. A.; Kalpakchieva, R.; Muzychka, Yu. A.; Penionzhkevich, Yu. E.; Rassadov, D. N.; Skobelev, N. K.; Testov, D. A.

    2007-04-01

    Excitation functions are measured for the fusion reactions 197Au(4He, xn)201-xn Tl that are induced by alpha-particle interaction with gold nuclei in the energy range 14 36 MeV and in which x neutrons (0 ≤ x ≤ 3) are evaporated. The stack-activation technique was used to record and separate reaction products. Experimental data on the fusion reactions followed by evaporation of one to three neutrons agree with results of previous studies. For the radiative-capture reaction 197Au(4He,γ)201Tl, the upper limit on the cross section proved to be much lower. The excitation functions for the reactions subjected to measurements are compared with the results of calculations based on the statistical model and with the results of an experiment performed previously in a 6He beam.

  2. Characterization of Ti{sub 1-x}Al{sub x}N coatings with selective IR reflectivity

    SciTech Connect

    Godinho, V.; Philippon, D.; Rojas, T.C.; Fernandez, A.; Novikova, N.N.; Yakovlev, V.A.; Vinogradov, E.A.

    2010-08-15

    Ti{sub 1-x}Al{sub x}N thin films were deposited by reactive magnetron sputtering. The obtained different stoichiometries give rise to different optical properties as the films change from metallic to dielectric. In this work the IR reflectivity of these coatings is investigated taking into account different application fields for IR selective Ti{sub 1-x}Al{sub x}N thin films. Low Al content coatings present high reflectivity, high absorptance and low thermal emittance. High Al compositions give raise to coatings with high absorptance and high thermal emittance. The composition of the coatings was evaluated combining electron energy loss spectroscopy (EELS) and energy dispersive spectroscopy. Scanning electron microscopy (SEM) revealed a columnar structure. Reflectance spectra for the visible and infrared spectral ranges were used to obtain the solar absorptance and thermal emittance values, used to calculate the equilibrium temperature of the coatings. The thermal stability in air from 300 to 600 C was also evaluated. (author)

  3. Spectroscopic analysis of the NIR emission in Tm implanted AlxGa1-xN layers

    NASA Astrophysics Data System (ADS)

    Rodrigues, J.; Fialho, M.; Esteves, T. C.; Santos, N. F.; Ben Sedrine, N.; Rino, L.; Neves, A. J.; Lorenz, K.; Alves, E.; Monteiro, T.

    2016-08-01

    AlxGa1-xN samples, with different AlN molar fractions, x = 0, 0.15, 0.77, and 1, grown by halide vapor phase epitaxy were implanted with Tm ions. Photoluminescence (PL) measurements revealed that after thermal annealing all the samples exhibit intraionic Tm3+ luminescence. In samples with x > 0, the low temperature emission is dominated by the lines that appear in the near infrared (NIR) spectral region, corresponding to the overlapped 1G4 → 3H5 and 3H4 → 3H6 multiplet transitions. A detailed spectroscopic analysis of NIR emission of the thulium implanted and annealed AlxGa1-xN layers is presented by using temperature dependent steady-state PL, room temperature PL excitation, and time resolved PL. The results indicate that the excitonic features sensitive to the alloy disorder are involved in the excitation population processes of the Tm3+ luminescence and the highest thermal stability for the NIR emission occurs for the AlN:Tm sample.

  4. Microstructure and dielectric properties of piezoelectric magnetron sputtered w-ScxAl1-xN thin films

    SciTech Connect

    Zukauskaite, Agne; Wingqvist, Gunilla; Palisaitis, Justinas; Jensen, Jens; Persson, Per; Matloub, Ramin; Muralt, Paul; Kim, Yunseok; Birch, Jens; Hultman, Lars

    2012-01-01

    Piezoelectric wurtzite ScxAl1 xN (x = 0, 0.1, 0.2, 0.3) thin films were epitaxially grown by reactive magnetron co-sputtering from elemental Sc and Al targets. Al2O3(0001) wafers with TiN(111) seed and electrode layers were used as substrates. X-ray diffraction shows that an increase in the Sc content results in the degradation of the crystalline quality. Samples grown at 400 C possess true dielectric behavior with quite low dielectric losses and the leakage current is negligible. For ScAlN samples grown at 800 C, the crystal structure is poor and leakage current is high. Transmission electron microscopy with energy dispersive x-ray spectroscopy mapping shows a mass separation into ScN-rich and AlN-rich domains for x 0.2 when substrate temperature is increased from 400 to 800 C. The piezoelectric response of epitaxial ScxAl1 xN films measured by piezoresponse force microscopy and double beam interferometry shows up to 180% increase by the addition of Sc up to x = 0.2 independent of substrate temperature, in good agreement with previous theoretical predictions based on density-functional theory.

  5. Role of electronic excitations and nuclear collisions for color center creation in AlxGa1-xN semiconductors

    NASA Astrophysics Data System (ADS)

    Moisy, F.; Grygiel, C.; Ribet, A.; Sall, M.; Balanzat, E.; Monnet, I.

    2016-07-01

    In this work, AlxGa1-xN (x = 0; 0.1; 0.3; 0.5; 0.65; 0.7; 0.8; 1) wurtzite epilayers, grown on c-plane sapphire substrates, have been irradiated with Swift Heavy Ions at GANIL facility. Modifications induced by irradiation are characterized with in-situ optical absorption spectroscopy at 15 K. Spectra of these irradiated alloys exhibit optical absorption band formation, related to new energy levels in their bandgaps, whose positions only depend on the composition of the layer. However, these absorption bands are not observed in the AlxGa1-xN with Al molar fraction less than 0.3, likely because the energy level of the corresponding defect is located above the conduction band. Moreover, using different irradiation conditions, a coupled effect between nuclear collisions and electronic excitations for these color center creation have been investigated. A synergy between these two phenomena has been shown and appears to be independent of the composition of the alloy.

  6. Tensor Force Manifestations in Ab Initio Study of the {sup 2}H(d,{gamma}){sup 4}He, {sup 2}H(d,p){sup 3}H, and {sup 2}H(d,n){sup 3}He Reactions

    SciTech Connect

    Arai, K.; Aoyama, S.; Suzuki, Y.; Descouvemont, P.; Baye, D.

    2011-09-23

    The {sup 2}H(d,p){sup 3}H, {sup 2}H(d,n){sup 3}He, and {sup 2}H(d,{gamma}){sup 4}He reactions are studied at low energies in a multichannel ab initio model that takes into account the distortions of the nuclei. The internal wave functions of these nuclei are given by the stochastic variational method with the AV8{sup '} realistic interaction and a phenomenological three-body force included to reproduce the two-body thresholds. The obtained astrophysical S factors are all in very good agreement with the experiment. The most important channels for both transfer and radiative capture are identified by comparing to calculations with an effective central force. They are all found to dominate thanks to the tensor force.

  7. Products of the reaction between alpha- or gamma-tocopherol and nitrogen oxides analyzed by high-performance liquid chromatography with UV-visible and atmospheric pressure chemical ionization mass spectrometric detection.

    PubMed

    Nagata, Yoshiko; Matsumoto, Yohta; Kanazawa, Hideko

    2004-05-21

    The reaction products of alpha- or gamma-tocopherol with nitric oxide in the presence of molecular oxygen were isolated and characterized. The consumption of tocopherols and the formation of the major products were monitored by high-performance liquid chromatography (HPLC) by a gradient elution method. The quantitative analysis of these compounds with UV-Vis detectors, however, was interfered by several minor products having similar UV spectra and retention times as those of the major ones. In order to establish a quantitative analytical method for the products, we investigated other detection methods, and found that atmospheric pressure chemical ionization (APCI), LC-MS was a more selective and better analytical method for these compounds.

  8. Experimental Cross Sections for Reactions of Heavy Ions and 208Pb, 209Bi, 238U, and 248Cm Targets

    SciTech Connect

    Patin, Joshua Barnes

    2002-01-01

    The study of the reactions between heavy ions and 208Pb, 209Bi, 238U, and 248Cm Cm targets was performed to look at the differences between the cross sections of hot and cold fusion reactions. Experimental cross sections were compared with predictions from statistical computer codes to evaluate the effectiveness of the computer code in predicting production cross sections. Hot fusion reactions were studied with the MG system, catcher foil techniques and the Berkeley Gas-filled Separator (BGS). 3n- and 4n-exit channel production cross sections were obtained for the 238U(18O,xn)256-xFm, 238U(22Ne,xn)260-xNo, and 248Cm(15N,xn)263-xLr reactions and are similar to previous experimental results. The experimental cross sections were accurately modeled by the predictions of the HIVAP code using the Reisdorf and Schaedel parameters and are consistent with the existing systematics of 4n exit channel reaction products. Cold fusion reactions were examined using the BGS. The 48Pb(238Ca,xn)256-xNo, 208Pb(50Ti,xn)258-xRf, 208Pb(51V,xn)259-xDb, 50Bi(238Ti,xn)259-xDb, and 209Bi(51V,xn)260-xSg reactions were studied. The experimental production cross sections are in agreement with the results observed in previous experiments. It was necessary to slightly alter the Reisdorf and Schaedel parameters for use in the HIVAP code in order to more accurately model the experimental data. The cold fusion experimental results are in agreement with current 1n- and 2n-exit channel systematics.

  9. New approach to description of (d,xn) spectra at energies below 50 MeV in Monte Carlo simulation by intra-nuclear cascade code with Distorted Wave Born Approximation

    NASA Astrophysics Data System (ADS)

    Hashimoto, S.; Iwamoto, Y.; Sato, T.; Niita, K.; Boudard, A.; Cugnon, J.; David, J.-C.; Leray, S.; Mancusi, D.

    2014-08-01

    A new approach to describing neutron spectra of deuteron-induced reactions in the Monte Carlo simulation for particle transport has been developed by combining the Intra-Nuclear Cascade of Liège (INCL) and the Distorted Wave Born Approximation (DWBA) calculation. We incorporated this combined method into the Particle and Heavy Ion Transport code System (PHITS) and applied it to estimate (d,xn) spectra on natLi, 9Be, and natC targets at incident energies ranging from 10 to 40 MeV. Double differential cross sections obtained by INCL and DWBA successfully reproduced broad peaks and discrete peaks, respectively, at the same energies as those observed in experimental data. Furthermore, an excellent agreement was observed between experimental data and PHITS-derived results using the combined method in thick target neutron yields over a wide range of neutron emission angles in the reactions. We also applied the new method to estimate (d,xp) spectra in the reactions, and discussed the validity for the proton emission spectra.

  10. Measurements of 15.11-MeV gamma-ray flux produced in the reactions C-12(p, p')-C-12*(15.11 MeV) and O-16(p, p' alpha)-C-12*(15.11 MeV)

    NASA Technical Reports Server (NTRS)

    Lapides, J. R.; Crannell, C. J.; Crannell, H.; Hornyak, W. F.; Seltzer, S. M.; Trombka, J. I.; Wall, N. S.

    1978-01-01

    The flux of 15.11 MeV gamma rays relative to the flux of 4.44 MeV gamma rays which are emitted from the corresponding states of C-12 are a sensitive measure of the spectrum of exciting particles in solar flares and other cosmic sources. Emission of 15.11 MeV gamma rays may result not only from the direct excitation of C-12 but also from the interaction O-16 (p,p' alpha) C-12* sup 15.11 MeV. Although the cross sections for the direct reaction was studied extensively, the cross section for the spallation interaction with O-16 is not reported in the literature. Preliminary measurements demonstrated the feasibility of measuring the production of 15.11 MeV gamma rays by proton interactions with O-16 using the University of Maryland cyclotron facility. For both carbon and oxygen targets the flux of 15.11 MeV gamma rays is being measured relative to the flux of 4.44 MeV gamma rays. The gamma ray emission from de-excitation of the giant dipole resonances is being measured.

  11. Aluminum incorporation in Ti{sub 1-x}Al{sub x}N films studied by x-ray absorption near-edge structure

    SciTech Connect

    Gago, R.; Redondo-Cubero, A.; Endrino, J. L.; Jimenez, I.; Shevchenko, N.

    2009-06-01

    The local bonding structure of titanium aluminum nitride (Ti{sub 1-x}Al{sub x}N) films grown by dc magnetron cosputtering with different AlN molar fractions (x) has been studied by x-ray absorption near-edge structure (XANES) recorded in total electron yield mode. Grazing incidence x-ray diffraction (GIXRD) shows the formation of a ternary solid solution with cubic structure (c-Ti{sub 1-x}Al{sub x}N) that shrinks with the incorporation of Al and that, above a solubility limit of xapprox0.7, segregation of w-AlN and c-Ti{sub 1-x}Al{sub x}N phases occurs. The Al incorporation in the cubic structure and lattice shrinkage can also be observed using XANES spectral features. However, contrary to GIXRD, direct evidence of w-AlN formation is not observed, suggesting a dominance and surface enrichment of cubic environments. For x>0.7, XANES shows the formation of Ti-Al bonds, which could be related to the segregation of w-AlN. This study shows the relevance of local-order information to assess the atomic structure of Ti{sub 1-x}Al{sub x}N solutions.

  12. Analysis of Vegard's law for lattice matching InxAl1-xN to GaN by metalorganic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Foronda, Humberto M.; Mazumder, Baishakhi; Young, Erin C.; Laurent, Matthew A.; Li, Youli; DenBaars, Steven P.; Speck, James S.

    2017-10-01

    Coherent InxAl1-xN (x = 0.15 to x = 0.28) films were grown by metalorganic chemical vapor deposition on GaN templates to investigate if the films obey Vegard's Law by comparing the film stress-thickness product from wafer curvature before and after InxAl1-xN deposition. The In composition and film thickness were verified using atom probe tomography and high resolution X-ray diffraction, respectively. Ex-situ curvature measurements were performed to analyze the curvature before and after the InxAl1-xN deposition. At ∼In0.18Al0.82N, no change in curvature was observed following InAlN deposition; confirming that films of this composition are latticed matched to GaN, obeying Vegard's law. The relaxed a0- and c0- lattice parameters of InxAl1-xN were experimentally determined and in agreement with lattice parameters predicted by Vegard's law.

  13. Performance evaluation of the Sysmex XN-1000 hematology analyzer in assessment of the white blood cell count differential in pediatric specimens.

    PubMed

    Becker, P-H; Fenneteau, O; Da Costa, L

    2016-02-01

    The automated XN-1000 hematology analyzer enables to perform a blood cell count and a leukocyte differential. When abnormal cells were detected, a flag was generated by the analyzer and a manual microscopic examination of the corresponding blood film was performed. We compared the white blood cell differentials provided by the automated hematology analyzer XN-1000 in a pediatric population (n = 765) with those obtained through microscopic examination by cytologists and those obtained using a previous version of this analyzer, the XE-2100. Leukocytes count as well as flags sensitivity and specificity was analyzed. The leukocytes count provided by the analyzer is in good accordance with the differential obtained by manual count in children older than 3 months. The sensitivity for blast detection is 99% and the detection of reactive cells is 63%. The flag specificity remains low (<35%) for blood samples collected from infants between 8 days and 2 years of age, but increases up to 67% thereafter. The results obtained with the XN-1000 analyzer show an improvement in comparison with those obtained with the XE-2100 analyzer. The automated WBC differential provided by the XN-1000 analyzer in the pediatric setting is accurate, but a meticulous microscopic examination of blood smears remains necessary for infants up to 3 months of age to validate the analyzer flags. © 2015 John Wiley & Sons Ltd.

  14. Mechanical properties of AlxGa1-xN films with high Al composition grown on AlN/sapphire templates

    NASA Astrophysics Data System (ADS)

    Xu, F. J.; Shen, B.; Wang, M. J.; Xu, J.; Lu, L.; Miao, Z. L.; Yang, Z. J.; Qin, Z. X.; Zhang, G. Y.; Lin, B.; Bai, S. L.

    2007-08-01

    Mechanical properties of AlxGa1-xN thin films with high Al composition (0.33⩽x⩽1) grown on AlN/sapphire templates have been investigated by means of the nanoindentation technique. It is found that Young's modulus E of the films increases with increasing Al composition. In addition, it is also found that the occurrence of the clear and sudden displacement discontinuity ("pop-in") in the plastic deformation (PD) process is dependent on Al composition in AlxGa1-xN films. The higher Al composition results in less occurrence of the pop-in in the PD process of the films. With increasing Al composition, it is believed that the increase of the bond strength and the decrease of the lattice mismatch between AlxGa1-xN films and AlN/sapphire templates result in greater resistance to the formation of dislocations, which is responsible for the pop-in behavior in AlxGa1-xN films.

  15. One-electron reduction of ferriporphyrins and reactions of ferric and ferrous porphyrins with a halothane-derived radical. [Gamma Radiation

    SciTech Connect

    Brault, D.; Neta, P.

    1982-08-19

    The reduction of ferrideuteroporphyrin by ..cap alpha..-hydroxyisopropyl radicals is investigated in acidic 2-propanol and acidic 2-propanol-water mixtures by means of steady-state and pulse radiolysis. The rate constant of the reaction is much higher (k approx. = 1.3 x 10/sup 9/ M/sup -1/s/sup -1/) than that reported for neutral solutions emphasizing the effect of the positive charge carried by the ferric porphyrin in acidic solutions (due to protonation of the alkoxide ligand). Competition kinetic experiments using p-nitroacetophenone as a referene solute show that ..cap alpha..-hydroxyisopropyl radicals are readily scavenged by halothane (CF/sub 3/CHClBr), leading to CF/sub 3/CHCl radicals. Pulse irradiation of ferriporphyrin solutions containing halothane allows investigation of the reaction of CF/sub 3/CHCl radicals with either ferric or ferrous prophyrins depending on the halothane concentration. No reaction of CF/sub 3/CHCl radicals with ferriporphyrin can be detected (k less than or equal to 10/sup 6/ M/sup -1/ s/sup -1/). On the other hand, a nearly diffusion-controlled reaction is observed between CF/sub 3/CHCl radicals and ferrous porphyrin leading to the sigma-bonded alkyl complex of the ferric porphyrin (PFe/sup III/CF/sub 3/CHCl, where CF/sub 3/CHCl stands for the alkyl anion). These results are discussed with regard to the reactivity of other alkyl radicals. The relevance to biological models of toxicity of halothane (a widely used anesthetic agent) is outlined.

  16. Search for the {theta}{sup +} Pentaquark in the Reaction {gamma}d{yields}pK{sup 0}K{sup -}(p) with CLAS

    SciTech Connect

    Baltzell, Nathan A.

    2007-10-26

    A search for photo-production of the {theta}{sup +}(1540) pentaquark and its decay to pK{sup 0} was performed with the CLAS detector system at Jefferson Lab. In the exclusive channel {gamma}d{yields}pK{sup 0}{sub s}K{sup -}(p), about twenty-thousand events with a slow missing proton, {pi}{sup +}{pi}{sup -} decay of the neutral kaon, and photon energy between 1.6 and 3.6 GeV are fully reconstructed. Included are numerous hyperon and meson resonances, with their decays to pK{sup -} and K{sup 0}K{sup -} respectively. To understand the possibility of a pentaquark signal amidst the backgrounds, a phenomenological isobar-inspired model of complex Breit-Wigner amplitudes and decay angular distributions for the resonances is fit to the data with a maximum likelihood method. No pentaquark signal is found above the background. The upper limit on the total production cross section is measured to be consistent with other channels published by the collaboration, but systematic studies are still in progress.

  17. Laser Electron Gamma Source Facility biennial progress report, June 1992

    SciTech Connect

    Caracappa, A.; Kuczewski, A.; Kistner, O.C.; Lincoln, F. ); Hoblit, S. . Dept. of Physics); Whisnant, C.S. South Carolina Univ., Columbia, SC . Dept. of Physics)

    1992-01-01

    This report briefly discusses the Laser Electron Gamma Source facility and the following experiments conducted here: polarization in D(gamma, p)n and N-N tensor forces for energies less than 225 Mev; constraints on the nuclear tensor force from D(gamma, p)n for energies less than 315 Mev; the p(gamma, neutral pion) reaction and the E2 excitation of delta resonance; quasi-two- and three-body absorption in helium 3(gamma, N-N); and the delta-nucleon interaction in D(gamma,p-negative pion)p and D(gamma, p-n)neutral pions. (LSP).

  18. Laser Electron Gamma Source Facility biennial progress report, June 1992

    SciTech Connect

    Caracappa, A.; Kuczewski, A.; Kistner, O.C.; Lincoln, F.; Hoblit, S.; Whisnant, C.S. |

    1992-08-01

    This report briefly discusses the Laser Electron Gamma Source facility and the following experiments conducted here: polarization in D(gamma, p)n and N-N tensor forces for energies less than 225 Mev; constraints on the nuclear tensor force from D(gamma, p)n for energies less than 315 Mev; the p(gamma, neutral pion) reaction and the E2 excitation of delta resonance; quasi-two- and three-body absorption in helium 3(gamma, N-N); and the delta-nucleon interaction in D(gamma,p-negative pion)p and D(gamma, p-n)neutral pions. (LSP).

  19. Excitation Functions for Complete Fusion and Transfer Reactions in the Interaction of 4He Nuclei with 197Au

    NASA Astrophysics Data System (ADS)

    Kulko, A. A.; Demekhina, N. A.; Kalpakchieva, R.; Muzychka, Yu. A.; Penionzhkevich, Yu. E.; Rassadov, D. N.; Skobelev, N. K.; Testov, D. A.

    2007-05-01

    Excitation functions have been measured for the fusion reaction 197Au(αxn)201-xnTl with the evaporation of x neutrons (0⩽x⩽3) in the energy range 14-36 MeV. The induced-activation method was used for registration and identification of the reaction products. The experimental cross sections for the (1-3)-neutron evaporation residues are in good agreement with the results known from literature. For the radiation capture reaction 197Au(α,γ)201Tl, the upper limit was obtained essentially lower. The excitation functions for the measured reactions are compared with calculations in the frame of the statistical model, as well as with formerly measured similar data with a 6He beam.

  20. Assessment of a quantitative 5' nuclease real-time polymerase chain reaction using the nicotinamide adenine dinucleotide dehydrogenase gamma subunit (nuoG) for Bartonella species in domiciled and stray cats in Brazil.

    PubMed

    André, Marcos Rogério; Dumler, John Stephen; Herrera, Heitor M; Gonçalves, Luiz R; de Sousa, Keyla Cm; Scorpio, Diana Gerardi; de Santis, Ana Cláudia Gabriela Alexandre; Domingos, Iara Helena; de Macedo, Gabriel Carvalho; Machado, Rosangela Zacarias

    2016-10-01

    The objective of this study was to develop a quantitative 5' nuclease real-time polymerase chain reaction (PCR) assay to diagnose infections caused by Bartonella species. Between January and April 2013 whole blood samples were collected by convenience from 151 cats (86 domiciled and 65 stray cats). The feline blood samples were subjected to a novel quantitative 5' nuclease real-time PCR (qPCR) for Bartonella species targeting the nictonamide adenine dinucleotide dehydrogenase gamma subunit (nuoG) and conventional PCR assays targeting intergenic transcribed spacer, ribC, gltA, pap31 and rpoB, followed by sequencing and basic local alignment search tool analysis. The qPCR assay detected as few as 10 copies of plasmid per reaction. Forty-six (54.4% domiciled and 45.6% stray cats) of 151 sampled cats showed positive results in nuoG qPCR for Bartonella species. The absolute quantification of nuoG Bartonella DNA in sampled cats ranged from 1.1 × 10(4) to 1.3 × 10(4). Eighteen (39.1%) of 46 positive samples in the qPCR were also positive in conventional PCR assays. The sequencing confirmed that Bartonella henselae and Bartonella clarridgeiae circulate in cats in midwestern Brazil. The present work provides details of a novel qPCR assay to diagnose infections caused by Bartonella species. © The Author(s) 2015.

  1. Growth of free-standing bulk wurtzite AlxGa1-xN layers by molecular beam epitaxy using a highly efficient RF plasma source

    NASA Astrophysics Data System (ADS)

    Novikov, S. V.; Staddon, C. R.; Sahonta, S.-L.; Oliver, R. A.; Humphreys, C. J.; Foxon, C. T.

    2016-12-01

    The recent development of group III nitrides allows researchers world-wide to consider AlGaN based light emitting diodes as a possible new alternative deep ultra-violet light source for surface decontamination and water purification. In this paper we will describe our recent results on plasma-assisted molecular beam epitaxy (PA-MBE) growth of free-standing wurtzite AlxGa1-xN bulk crystals using the latest model of Riber's highly efficient nitrogen RF plasma source. We have achieved AlGaN growth rates up to 3 μm/h. Wurtzite AlxGa1-xN layers with thicknesses up to 100 μm were successfully grown by PA-MBE on 2-inch and 3-inch GaAs (111)B substrates. After growth the GaAs was subsequently removed using a chemical etch to achieve free-standing AlxGa1-xN wafers. Free-standing bulk AlxGa1-xN wafers with thicknesses in the range 30-100 μm may be used as substrates for further growth of AlxGa1-xN-based structures and devices. High Resolution Scanning Transmission Electron Microscopy (HR-STEM) and Convergent Beam Electron Diffraction (CBED) were employed for detailed structural analysis of AlGaN/GaAs (111)B interface and allowed us to determine the N-polarity of AlGaN layers grown on GaAs (111)B substrates. The novel, high efficiency RF plasma source allowed us to achieve free-standing AlxGa1-xN layers in a single day's growth, making this a commercially viable process.

  2. Validation of the body fluid module on the new Sysmex XN-1000 for counting blood cells in cerebrospinal fluid and other body fluids.

    PubMed

    Fleming, Chérina; Brouwer, Rob; Lindemans, Jan; de Jonge, Robert

    2012-10-01

    We evaluated the body fluid (BF) module on the new Sysmex XN-1000 for counting blood cells. One hundred and eighty-seven BF samples [73 cerebrospinal fluid (CSF), 48 continuous ambulatory peritoneal dialysis (CAPD), 46 ascites, and 20 pleural fluid] were used for method comparison between the XN-1000 and manual microscopy (Fuchs-Rosenthal chamber and stained cytospin slides) for counting red blood cells (RBCs) and white blood cells (WBCs) (differential). Good agreement was found for counting WBCs (y=1.06x+0.09, n=67, R2=0.96) and mononuclear cells (MNs) (y=1.04x-0.01, n=40, R2=0.93) in CSF. However, the XN-1000 systematically counted more polymorphonuclear cells (PMNs) (y=1.48x+0.18, n=40, R2=0.99) compared to manual microscopy. Excellent correlation for RBCs >1×109/L (y=0.99x+116.56, n=26, R2=0.99) in CSF was found. For other fluids (CAPD, ascites and pleural fluid) excellent agreement was found for counting WBCs (y=1.06x+0.26, n=109, R2=0.98), MNs (y=1.06x-0.41, n=93, R2=0.96), PMNs (y=1.06x+0.81, n=93, R2=0.98) and RBCs (y=1.04x+110.04, n=43, R2=0.98). By using BF XN-check, the lower limit of quantitation (LLoQ) for WBC was defined at 5×106/L. Linearity was excellent for both the WBCs (R2=0.99) and RBCs (R2=0.99) and carry-over never exceeded 0.05%. The BF module on the XN-1000 is a suitable tool for fast and accurate quantification of WBC (differential) and RBC counts in CSF and other BFs in a diagnostic setting.

  3. Possibilities of synthesis of unknown isotopes of superheavy nuclei with charge numbers Z > 108 in asymmetric actinide-based complete fusion reactions

    NASA Astrophysics Data System (ADS)

    Hong, Juhee; Adamian, G. G.; Antonenko, N. V.

    2016-10-01

    The possibilities of production of new isotopes of superheavy nuclei with charge numbers Z = 109-114 in various asymmetric hot fusion reactions are studied for the first time. The excitation functions of the formation of these isotopes in the xn evaporation channels are predicted and the optimal conditions for the synthesis are proposed. The products of the suggested reactions can fill a gap of unknown isotopes between the isotopes of the heaviest nuclei obtained in cold and hot complete fusion reactions.

  4. Gamma II

    NASA Astrophysics Data System (ADS)

    Barker, Thurburn; Castelaz, M.; Cline, J.; Owen, L.; Boehme, J.; Rottler, L.; Whitworth, C.; Clavier, D.

    2011-05-01

    GAMMA II is the Guide Star Automatic Measuring MAchine relocated from STScI to the Astronomical Photographic Data Archive (APDA) at the Pisgah Astronomical Research Institute (PARI). GAMMA II is a multi-channel laser-scanning microdensitometer that was used to measure POSS and SERC plates to create the Guide Star Catalog and the Digital Sky Survey. The microdensitometer is designed with submicron accuracy in x and y measurements using a HP 5507 laser interferometer, 15 micron sampling, and the capability to measure plates as large as 0.5-m across. GAMMA II is a vital instrument for the success of digitizing the direct, objective prism, and spectra photographic plate collections in APDA for research. We plan several targeted projects. One is a collaboration with Drs. P.D. Hemenway and R. L. Duncombe who plan to scan 1000 plates of 34 minor planets to identify systematic errors in the Fundamental System of celestial coordinates. Another is a collaboration with Dr. R. Hudec (Astronomical Institute, Academy of Sciences of the Czech Republic) who is working within the Gaia Variability Unit CU7 to digitize objective prism spectra on the Henize plates and Burrell-Schmidt plates located in APDA. These low dispersion spectral plates provide optical counterparts of celestial high-energy sources and cataclysmic variables enabling the simulation of Gaia BP/RP outputs. The astronomical community is invited to explore the more than 140,000 plates from 20 observatories now archived in APDA, and use GAMMA II. The process of relocating GAMMA to APDA, re-commissioning, and starting up the production scan programs will be described. Also, we will present planned research and future upgrades to GAMMA II.

  5. Radioimmunoassay for. gamma. -melanocyte stimulating hormone

    SciTech Connect

    Shibasaki, T.; Ling, N.; Guillemin, R.

    1980-05-26

    A specific radioimmunoassay for ..gamma..-melanocyte stimulating hormone-like peptides was developed. An antiserum raised in rabbit to synthetic bovine ..gamma../sub 3/-MSH, one of the possible ..gamma..-MSH peptides, specifically recognizes the portion between His/sup 5/ and Arg/sup 14/ of ..gamma../sub 3/-MSH without significant cross-reaction with other synthetic ..gamma..-MSH-like peptides, ..cap alpha..-, ..beta..-MSH, adrenocorticotropin, and ..beta..-endorphin. The usable range of this RIA is 10 pg to 600 pg of synthetic ..gamma../sub 3/-MSH. Three immunoreactive ..gamma..-MSH peaks were thus found in gel permeation chromatography of the whole bovine pituitary extract.

  6. Luminescence and superradiance in electron-beam-excited Al{sub x}Ga{1-sub x}N

    SciTech Connect

    Bokhan, P. A.; Gugin, P. P.; Zakrevsky, Dm. E.; Malin, T. V.; Zhuravlev, K. S.; Osinnykh, I. V.; Solomonov, V. I.; Spirina, A. V.

    2014-09-21

    Luminescence and superradiance characteristics of 0.5–1.2-μm thick Al{sub x}Ga{sub 1-x}N films grown by molecular-beam epitaxy on sapphire substrates were studied under excitation of the films with low-energy (<20 keV) and high-energy (170 keV) electron beams. In both cases, the luminescence spectra looked quite similarly; they exhibited a band-edge luminescence with x-dependent wavelength ranging from 365 nm to 310 nm and a broadband emission taking over the whole visible spectral region. Superradiance within the broad band was obtained by pumping the samples with powerful an electron beam in the form of an open-discharge-generated filament.

  7. Barrier height of Pt-InxGa1-xN (0<=x<=0.5) nanowire Schottky diodes

    NASA Astrophysics Data System (ADS)

    Guo, Wei; Banerjee, Animesh; Zhang, Meng; Bhattacharya, Pallab

    2011-05-01

    The barrier height of Schottky diodes made on InxGa1-xN nanowires have been determined from capacitance-voltage measurements. The nanowires were grown undoped on n-type (001) silicon substrates by plasma-assisted molecular beam epitaxy. The length, diameter and density of the nanowires are ˜1 μm, 20 nm, and 1×1011 cm-2. The Schottky contact was made on the top surface of the nanowires with Pt after planarizing with parylene. The measured barrier height ΦB varies from 1.4 eV (GaN) to 0.44 eV (In0.5Ga0.5N) and agrees well with the ideal barrier heights in the Schottky limit.

  8. Half metallic ferromagnetism in alkaline-earth metal nitrides XN (X=Ca, Sr and Ba): A first principles study

    NASA Astrophysics Data System (ADS)

    Palanichamy, R. Rajeswara; Priyanga, G. Sudha; Cinthia, A. Jemmy; Murugan, A.; Meenaatci, A. T. Asvini; Iyakutti, K.

    2013-11-01

    The structural, electronic, mechanical and magnetic properties of 3 alkaline-earth metal nitrides (XN: X=Ca, Sr, and Ba) are investigated by the first principles calculations based on density functional theory using the Vienna ab-initio simulation code. At ambient pressure all the 3 nitrides are stable in the ferromagnetic state with a cubic NaCl structure. The calculated lattice parameters are in good agreement with the available results. The electronic structure reveals that these materials are half metallic ferromagnets at normal pressure. A pressure-induced structural phase transition from NaCl (B1) to CsCl (B2) phase is observed in CaN, SrN and BaN. On further increasing the pressure, a half metallic to metallic transition is also observed in these nitrides. Ferromagnetism is quenched in all the 3 nitrides at high pressures.

  9. Tuning of superconductivity by Ni substitution into noncentrosymmetric ThC o1 -xN ixC2

    NASA Astrophysics Data System (ADS)

    Grant, T. W.; Cigarroa, O. V.; Rosa, P. F. S.; Machado, A. J. S.; Fisk, Z.

    2017-07-01

    The recently discovered noncentrosymmetric superconductor ThCoC2 was observed to show unusual superconducting behavior with a critical temperature of Tc=2.65 K . Here we investigate the effect of nickel substitution on the superconducting state in ThC o1 -xN ixC2 . Magnetization, resistivity, and heat capacity measurements demonstrate Ni substitution has a dramatic effect with critical temperature increased up to Tc=12.1 K for x =0.4 Ni concentration, which is a rather high transition temperature for a noncentrosymmetric superconductor. In addition, the unusual superconducting characteristics observed in pure ThCoC2 appear to be suppressed or tuned with Ni substitution towards a more conventional fully gapped superconductor.

  10. Performance evaluation of the white cell precursor channel on the Sysmex XN hematology analyzer in HIV specimens.

    PubMed

    Schapkaitz, Elise; Khoza, Phoyisile

    2017-09-26

    Automated hematology analyzers generate white blood cell (WBC) suspect flags to indicate smears requiring manual review. In a human immunodeficiency virus (HIV) patient population with a high frequency of abnormal specimens, the usefulness of these flags depends on their sensitivity and specificity. The white cell precursor (WPC) channel on the Sysmex XN-9000 analyzer (Sysmex Corporation, Kobe, Japan) has recently been introduced in order to distinguish immature cells such as blasts and abnormal lymphocytes. The efficiency of the flags generated by WPC reflex testing was compared to the white cell differential (WDF) on the Sysmex XN-9000 in 400 routine HIV samples. A flag was generated by the WDF channel in 346 (86.50%) samples. Addition of the WPC to the WDF resulted in a 20.99% reduction in the smear review rate. WPC analysis correctly identified the initial WDF flag in 59 (60.82%) samples with 'blasts?' or 'abnormal lympho?' flags. WPC showed an excellent sensitivity of 100%. However, the specificity remained poor. On investigation, samples with chronic infection/inflammation (35.00%) and lymphopenia (63.25%) were associated with a high false positive rate of 76.32% and 55.56%, respectively. WPC analysis removed 45 (51.72%) coexisting 'atypical lympho?' false positive WDF flags. The 'atypical lympho?' flag showed an increased sensitivity and specificity of 88.46% and 74.67%, respectively. White cell precursor reflex testing showed improved flagging efficiency for the 'atypical lympho?' flag, which was a good indicator of reactive lymphocytes during chronic infection/inflammation. Nevertheless, the false positive rate for 'abnormal lympho/blasts?' was high in the presence of lymphopenia and infection. © 2017 Wiley Periodicals, Inc.

  11. Performance evaluation of platelet counting by novel fluorescent dye staining in the XN-series automated hematology analyzers.

    PubMed

    Tanaka, Yuzo; Tanaka, Yumiko; Gondo, Kazumi; Maruki, Yoshiko; Kondo, Tamiaki; Asai, Satomi; Matsushita, Hiromichi; Miyachi, Hayato

    2014-09-01

    Conventional automated hematology analyzers have limitations in platelet measurements such as poor accuracy and precision in the low count range and interference by nonplatelet particles. In order to improve it, the newly developed XN-Series automated hematology analyzers (Sysmex Corporation, Kobe, Japan) have been installed with a new dedicated channel for platelet analysis (PLT-F), which is based on a fluorescence flow cytometry method with uses of a novel fluorescent dye specifically staining platelets. We evaluated the basic performance of this new PLT-F channel. Basic performance of the PLT-F channel in within-run reproducibility and assay linearity was studied using standard methods. Correlation was studied between PLT-F and a conventional automated hematology analyzer (XE-2100) and immunoplatelet analysis using anti-CD61 monoclonal antibody (Cell-Dyn Sapphire; Abbott Laboratories). The assay interference by nonplatelet particles such as fragmented red and white blood cells was evaluated by using clinical samples, respectively, from burn injury and acute leukemia. Basic performance of the PLT-F platelet counting was satisfactory in within-run reproducibility, linearity and correlation with the conventional analyzer. The correlation was satisfactory also with the immunoplatelet analysis, even for samples from a patient with burn injury, and those with white blood cell fragments displayed, platelet abnormal flag and low platelet counts (<50 × 10(9)/l). The platelet counting performance of the PLT-F channel of the XN Series had improved accuracy and precision in the low range and in abnormal samples, avoiding the interference by nonplatelet particles. © 2014 Wiley Periodicals, Inc.

  12. Thermoelectric and piezoelectric properties of the predicted AlxIn1-xN composites based on ab initio calculations.

    PubMed

    Chang, Yee Hui Robin; Yoon, Tiem Leong; Lim, Thong Leng; Tuh, Moi Hua; Goh, Eong Sheng

    2017-09-20

    Theoretical investigations of the thermoelectric and piezoelectric characteristics in the AlxIn1-xN system have been carried out based on a first principles approach in combination with the semi-classical Boltzmann transport concept and density functional perturbation theory. Based on our previous work, herein, the study specimens Al5InN6, Al6In2N8, Al4In2N6, Al3In3N6, Al2In4N6, and AlIn7N8 have been predicted to be stable phases. These novel phases intrinsically exhibit moderate positive Seebeck curves (199.1-284.6 μV K(-1)) and a ZT close to unity that varies marginally over a broad temperature range of 200-800 K, demonstrating the sign of good bipolar effect tolerance. Addition of heftier elements, such as In, results in lower thermal conductivity, which in turn generates a high power factor (0.019-0.345 W m(-1) K(-2)) in these alloys. While hole doping enhances the peak Seebeck coefficient of each phase, the electrical conductivity has been greatly compromised, resulting in a lower power factor. These composites also exhibit large piezoelectric constants, in which their respective largest piezoelectric tensor is several orders higher than that of quartz. The decomposition process shows that In and N are the main contributors of the internal piezoelectric term. Overall results indicate that AlxIn1-xN show bright prospects in thermoelectric and piezoelectric applications.

  13. First results from ASP on resonance production in. gamma gamma. interactions

    SciTech Connect

    Roe, N.

    1988-05-01

    The reaction e/sup +/e/sup -//yields/e/sup +/e/sup -//gamma/sup *//gamma/sup *///yields/(e/sup +/e/sup -/)/eta/, with subsequent decay of the /eta/ into two photons, has been observed with the ASP detector at the PEP e/sup +/e/sup -/ storage ring at /radical/ s=29 GeV. A measurement of the radiative width of the /eta/ yields the preliminary result /Gamma/(/eta//yields//gamma//gamma/) = .489 /+-/ .009 /+-/ .055 keV. Evidence for the production of the /eta/' with decay into two photons has also been observed.

  14. Gamma watermarking

    DOEpatents

    Ishikawa, Muriel Y.; Wood, Lowell L.; Lougheed, Ronald W.; Moody, Kenton J.; Wang, Tzu-Fang

    2004-05-25

    A covert, gamma-ray "signature" is used as a "watermark" for property identification. This new watermarking technology is based on a unique steganographic or "hidden writing" digital signature, implemented in tiny quantities of gamma-ray-emitting radioisotopic material combinations, generally covertly emplaced on or within an object. This digital signature may be readily recovered at distant future times, by placing a sensitive, high energy-resolution gamma-ray detecting instrument reasonably precisely over the location of the watermark, which location may be known only to the object's owner; however, the signature is concealed from all ordinary detection means because its exceedingly low level of activity is obscured by the natural radiation background (including the gamma radiation naturally emanating from the object itself, from cosmic radiation and material surroundings, from human bodies, etc.). The "watermark" is used in object-tagging for establishing object identity, history or ownership. It thus may serve as an aid to law enforcement officials in identifying stolen property and prosecuting theft thereof. Highly effective, potentially very low cost identification-on demand of items of most all types is thus made possible.

  15. Upbend and M1 scissors mode in neutron-rich nuclei - consequences for r-process $$(n,\\gamma )$$ reaction rates

    DOE PAGES

    Larsen, A. C.; Goriely, S.; Bernstein, L. A.; ...

    2015-01-01

    An enhanced probability for low-energy γ-emission (upbend, Eγ < 3 MeV) at high excitation energies has been observed for several light and medium-mass nuclei close to the valley of stability. Also the M1 scissors mode seen in deformed nuclei increases the γ-decay probability for low-energy γ-rays (Eγ ≈ 2–3 MeV). These phenomena, if present in neutron-rich nuclei, have the potential to increase radiative neutron-capture rates relevant for the r-process. Furthermore, the experimental and theoretical status of the upbend is discussed, and preliminary calculations of (n,γ) reaction rates for neutron-rich, mid-mass nuclei including the scissors mode are shown.

  16. Upbend and M1 scissors mode in neutron-rich nuclei - consequences for r-process $(n,\\gamma )$ reaction rates

    SciTech Connect

    Larsen, A. C.; Goriely, S.; Bernstein, L. A.; Bleuel, D. L.; Bracco, A.; Brown, B. A.; Camera, F.; Eriksen, T. K.; Frauendorf, S.; Giacoppo, F.; Guttormsen, M.; Gorgen, A.; Harissopulos, S.; Leoni, S.; Liddick, S. N.; Naqvi, F.; Nyhus, H. T.; Rose, S. J.; Renstrom, T.; Schwengner, R.; Siem, S.; Spyrou, A.; Tveten, G. M.; Voinov, A. V.; Wiedeking, M.

    2015-01-01

    An enhanced probability for low-energy γ-emission (upbend, Eγ < 3 MeV) at high excitation energies has been observed for several light and medium-mass nuclei close to the valley of stability. Also the M1 scissors mode seen in deformed nuclei increases the γ-decay probability for low-energy γ-rays (Eγ ≈ 2–3 MeV). These phenomena, if present in neutron-rich nuclei, have the potential to increase radiative neutron-capture rates relevant for the r-process. Furthermore, the experimental and theoretical status of the upbend is discussed, and preliminary calculations of (n,γ) reaction rates for neutron-rich, mid-mass nuclei including the scissors mode are shown.

  17. Enantioseparation of isoxanthohumol in beer by hydroxypropyl-gamma-cyclodextrin-modified micellar electrokinetic chromatography.

    PubMed

    Kodama, Shuji; Yamamoto, Atsushi; Sato, Atsushi; Suzuki, Kentaro; Yamashita, Tomohisa; Kemmei, Tomoko; Taga, Atsushi; Hayakawa, Kazuichi

    2007-08-08

    Chiral resolution of isoxanthohumol (IX) in beer samples was performed by hydroxypropyl-gamma-cyclodextrin-modified micellar electrokinetic chromatography. The optimum running conditions were found to be 20 mM phosphate buffer (pH 7.0) containing 45 mM hydroxypropyl-gamma-cyclodextrin and 100 mM sodium dodecyl sulfate with an effective voltage of +20 kV at 20 degrees C using direct detection at 210, 295, and 370 nm. IX was detected in 12 beer samples and the total levels of (+)- and (-)-IX ranged from 0.15 to 1.4 mg/L. But the amount of xanthohumol (XN) was below the detection limit (0.017 mg/L). Each level of (-)-IX was almost the same as that of (+)-IX, suggesting that IX was a racemic mixture in these beer samples. The racemization of IX in beer could be attributed to the production of a racemic mixture from XN during boiling and to the fact that IX enantiomers were easily interconverted.

  18. Clinical value of whole-blood interferon-gamma assay in patients with suspected pulmonary tuberculosis and AFB smear- and polymerase chain reaction-negative bronchial aspirates.

    PubMed

    Lee, Jaehee; Lee, Shin Yup; Yoo, Seung Soo; Cha, Seung Ick; Won, Dong Il; Park, Jae Yong; Lee, Won-Kil; Kim, Chang Ho

    2012-07-01

    Combining a polymerase chain reaction (PCR) test with bronchoscopy is frequently performed to allow a rapid diagnosis of smear-negative pulmonary tuberculosis (PTB). However, limited data are available concerning clinical judgment in patients with suspected PTB and AFB smear- and PCR-negative bronchial aspirates (BA). The present study evaluated the usefulness of whole-blood QuantiFERON-TB Gold In-Tube (QFT) testing in these patients. Of 166 patients with suspected PTB who had undergone bronchoscopy because of smear-negative sputum or inadequate sputum production, 93 (56%) were diagnosed with culture-positive PTB. Seventy-four patients were either AFB smear- or PCR-positive. In the 75 patients whose BA AFB smear and PCR results were both negative, 19 were finally diagnosed with PTB by culture. The QFT test had a negative predictive value of 91% for PTB. The QFT test may be useful for excluding PTB in patients with suspected PTB whose BA AFB smear and PCR results are both negative. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. GaN Epitaxial Layer Grown with Conductive Al(x)Ga(1-x)N Buffer Layer on SiC Substrate Using Metal Organic Chemical Vapor Deposition.

    PubMed

    So, Byeongchan; Lee, Kyungbae; Lee, Kyungjae; Heo, Cheon; Pyeon, Jaedo; Ko, Kwangse; Jang, Jongjin; Nam, Okhyun

    2016-05-01

    This study investigated GaN epitaxial layer growth with a conductive Al(x)Ga(1-x)N buffer layer on n-type 4H-SiC by high-temperature metalorganic chemical vapor deposition (HT-MOCVD). The Al composition of the Al(x)Ga(1-x)N buffer was varied from 0% to 100%. In terms of the crystal quality of the GaN layer, 79% Al was the optimal composition of the Al(x)Ga(1-x)N buffer layer in our experiment. A vertical conductive structure was fabricated to measure the current voltage (I-V) characteristics as a function of Al composition, and the I-V curves showed that the resistance increased with increasing Al concentration of the Al(x)Ga(1-x)N buffer layer.

  20. Is (d,p{gamma}) a surrogate for neutron capture?

    SciTech Connect

    Hatarik, R.; Cizewski, J. A.; O'Malley, P. D.; Bernstein, L. A.; Burke, J. T.; Lesher, S. R.; Gibelin, J. D.; Phair, L. W.; Swan, T.

    2008-04-17

    To benchmark the validity of using the (d,p{gamma}) reaction as a surrogate for (n,{gamma}), the {sup 171,173}Yb(d,p{gamma}) reactions were measured and compared with the neutron capture cross sections measured by Wisshak et al. The (d,p{gamma}) ratios were measured using an 18.5 MeV deuteron beam from the 88-Inch Cyclotron at LBNL. Preliminary results comparing the surrogate ratios with the known (n,{gamma}) cross sections are discussed.

  1. Unified studies of structure and reactions in light unstable nuclei

    NASA Astrophysics Data System (ADS)

    Ito, Makoto

    2016-06-01

    The generalized two-center cluster model (GTCM), which can treat covalent, ionic and atomic configurations in general systems with two inert cores plus valence nucleons, is formulated in the basis of the microscopic cluster model. In this model, the covalent configurations constructed by the molecular orbital (MO) method and the atomic (or ionic) configuration obtained by the valence bonding (VB) method can be described in a consistent manner. GTCM is applied to the light neutron-rich system, 10,12Be = α + α + XN (X = 2,4), and the unified studies of the structural changes and the reaction problem are performed. In the structure study, the calculated energy levels are characterized in terms of the chemical bonding like structures, such as the covalent MO or ionic VB structures. The chemical bonding structures changes from level to level within a small energy interval. In the unbound region, the structure problem with the total system of α + α + XN and the reaction problem, induced by the collision of an asymptotic VB state of α+6,8He, are combined by GTCM. The properties of unbound resonant states are discussed in a close connection to the reaction mechanism, and some enhancement factors originated from the properties of the intrinsic states are predicted in the reaction observables. The unified calculation of the structures and the reactions is applied to the Coulomb shift problem in the mirror system, such the 10Be and 10C nuclei. The Coulomb displacement energy of the mirror systems are discussed.

  2. Data on photoneutron reactions from various experiments for {sup 133}Cs, {sup 138}Ba and {sup 209}Bi nuclei

    SciTech Connect

    Varlamov, V. V. Ishkhanov, B. S.; Orlin, V. N.; Peskov, N. N.

    2016-07-15

    Basic methods for determining cross sections for photoneutron partial reactions are examined. They are obtained directly in experiments with quasimonoeneregetic annihilation photons or from the cross section for the (γ, xn) = (γ, 1n) + 2(γ, 2n) + 3(γ, 3n) +... neutron-yield reaction in experiments with bremsstrahlung photons by introducing corrections based on statistical nuclear-reaction theory. The difference in the conditions of these experiments, which leads to discrepancies between their results because of sizable systematic errors, is analyzed. Physical criteria are used to study the reliability of data on the photodisintegration of {sup 133}Cs, {sup 138}Ba, and {sup 209}Bi nuclei. The cross sections for partial and total reactions satisfying the reliability criteria are evaluated within the experimental–theoretical method (σ{sup eval}(γ, in) = F{sub i}{sup theor} × σ{sup expt}(γ, xn)) on the basis of the experimental cross sections σ{sup expt}(γ, xn) and the results of the calculations within the combined model of photonuclear reactions.

  3. A new formulation of UMC and an Evaluation of the {sup 55}Mn(n,{gamma}){sup 56}Mn Dosimetry Reaction Cross Section (a.k.a. 'Toy Story 4')

    SciTech Connect

    Capote, R.; Smith, D.L.; Trkov, A.; Meghzifene, M.

    2011-07-01

    Two relatively new approaches to neutron cross section data evaluation are described. They are known collectively as Unified Monte Carlo (versions UMC-G and UMC-B). Comparisons are made between these two methods, as well as with the well-known generalized least-squares (GLSQ) technique, through the use of simple, hypothetical (toy) examples. These new Monte Carlo methods are based on stochastic sampling of probability functions that are constructed with the use of theoretical and experimental data by applying the principle of maximum entropy. No further assumptions are involved in either UMC-G or UMC-B. However, the GLSQ procedure requires the linearization of non-linear terms, such as those that occur when cross section ratio data are included in an evaluation. It is shown that these two stochastic techniques yield results that agree well with each other, and with the GLSQ method, when linear data are involved, or when the perturbations due to data discrepancies and nonlinearity effects are small. Otherwise, there can be noticeable differences. The present investigation also demonstrates, as observed in earlier work, that the least-squares approach breaks down when these conditions are not satisfied. This paper also presents an actual evaluation of the {sup 55}Mn(n,{gamma}) {sup 56}Mn neutron dosimetry reaction cross section in the energy range from 100 keV to 20 MeV, which was performed using both GLSQ and UMC-G approaches. (authors)

  4. Tests of quantum chromodynamics in exclusive e sup + e sup minus and. gamma. gamma. processes

    SciTech Connect

    Brodsky, S.J.

    1989-09-01

    This paper discusses the following topics: Factorization theorem for exclusive processes; Electromagnetic form factors of baryons; Suppression of final state interactions; The {gamma}{pi}{sub 0} Transition form factor; Exclusive charmonium decays; The {pi}-{rho} puzzle; Time-like compton processes; Multi-hadron production; Heavy Quark exclusive states and form factor zeros in QCD; Exclusive {gamma}{gamma} reactions; Higher twist effects; and Tauonium and threshold {tau}{sup +}{tau}{sup {minus}} production. 41 refs., 15 figs. (LSP)

  5. Determination of the Al Composition of Al{sub x}Ga{sub 1-x}N Thin Films By Means Of EDX and XRD Techniques

    SciTech Connect

    Ng, S. S.; Hassan, Z.; Hassan, H. Abu

    2010-07-07

    In this paper, the determinations of Al composition x of Al{sub x}Ga{sub 1-x}N(0{<=}x{<=}1) thin films by means of the energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analyses are reported. Through these non-destructive and contactless techniques, a large probed area of the Al{sub x}Ga{sub 1-x}N samples can be selected. Consequently, the uncertainty due to the inhomogeneity of the Al composition can be avoided. For EDX measurements, the Al composition is calculated based on the weight percent of the Al and Ga elements, while that in the XRD measurements is based on lattice constant c and Vegard's law. The results from these two independent techniques are in good agreement with each other.

  6. Conducting transition metal nitride thin films with tailored cell sizes: The case of {delta}-Ti{sub x}Ta{sub 1-x}N

    SciTech Connect

    Koutsokeras, L. E.; Abadias, G.; Lekka, Ch. E.; Matenoglou, G. M.; Anagnostopoulos, D. F.; Patsalas, P.; Evangelakis, G. A.

    2008-07-07

    We present results on the stability and tailoring of the cell size of conducting {delta}-Ti{sub x}Ta{sub 1-x}N obtained by film growth and ab initio calculations. Despite the limited solubility of Ta in Ti, we show that TiN and TaN are soluble due to the hybrization of the d and sp electrons of the metal and N, respectively, that stabilizes the ternary system to the rocksalt structure. The stress-free cell sizes follow the Vegard's rule; nevertheless, process-dependent stresses expand the cell size of the as-grown films. The electronic properties of {delta}-Ti{sub x}Ta{sub 1-x}N films ({rho}=180 {omega} cm) are similar to those of TiN and TaN.

  7. Structural characterization of zincblende Ga{sub 1-x}Mn{sub x}N epilayers grown by molecular beam epitaxy on (001) GaAs substrates

    SciTech Connect

    Fay, M.W.; Han, Y.; Brown, P.D.; Novikov, S.V.; Edmonds, K.W.; Campion, R.P.; Gallagher, B.L.; Foxon, C.T.

    2005-07-18

    Zincblende p-type Ga{sub 1-x}Mn{sub x}N epilayers, grown with and without AlN/GaN buffer layers using plasma-assisted molecular beam epitaxy on (001) oriented GaAs substrates, have been investigated using a variety of complementary transmission electron microscopy techniques. The epilayers were found to contain a high anisotropic density of stacking faults and microtwins. MnAs inclusions were identified at the Ga{sub 1-x}Mn{sub x}N/(001)GaAs interface extending into the substrate. The use of AlN/GaN buffer layers was found to inhibit the formation of these inclusions.

  8. Growth and oxidization stability of cubic Zr{sub 1−x}Gd{sub x}N solid solution thin films

    SciTech Connect

    Höglund, C.; Alling, B.; Jensen, J.; Hultman, L.; Birch, J.; Hall-Wilton, R.

    2015-05-21

    We report Zr{sub 1−x}Gd{sub x}N thin films deposited by magnetron sputter deposition. We show a solid solubility of the highly neutron absorbing GdN into ZrN along the whole compositional range, which is in excellent agreement with our recent predictions by first-principles calculations. An oxidization study in air shows that Zr{sub 1−x}Gd{sub x}N with x reaching from 1 to close to 0 fully oxidizes, but that the oxidization is slowed down by an increased amount of ZrN or stopped by applying a capping layer of ZrN. The crystalline quality of Zr{sub 0.5}Gd{sub 0.5}N films increases with substrate temperatures increasing from 100 °C to 900 °C.

  9. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Growth and Characteristics of Epitaxial AlxGa1-xN by MOCVD

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Guo, Li-Wei; Chen, Yao; Xu, Pei-Qiang; Ding, Guo-Jian; Peng, Ming-Zeng; Jia, Hai-Qiang; Zhou, Jun-Ming; Chen, Hong

    2009-06-01

    AlxGa1-xN epilayers with a wide Al composition range (0.2 <= x <= 0.68) were grown on AlN/sapphire templates by low-pressure metalorganic chemical vapour deposition (LP-MOCVD). X-ray diffraction results reveal that both the (0002) and (10bar 15) full widths at half-maximum (FWHM) of the AlxGa1-xN epilayer decrease with increasing Al composition due to the smaller lattice mismatch to the AlN template. However, the surface morphology becomes rougher with increasing Al composition due to the weak migration ability of Al atoms. Low temperature photoluminescence (PL) spectra show pronounced near band edge (NBE) emission and the NBE FWHM becomes broader with increasing Al composition mainly caused by alloy disorder. Meanwhile, possible causes of the low energy peaks in the PL spectra are discussed.

  10. Bulk lattice parameter and band gap of cubic InXGa1-XN (001) alloys on MgO (100) substrates

    NASA Astrophysics Data System (ADS)

    Compeán García, V. D.; Orozco Hinostroza, I. E.; Escobosa Echavarría, A.; López Luna, E.; Rodríguez, A. G.; Vidal, M. A.

    2015-05-01

    InxGa1-xN (001) ternary alloys were grown on GaN/MgO (100) substrates in a plasma assisted molecular beam epitaxy system. We determined the in-plane [001] and in-growth [110] lattice parameters, as well as the bulk lattice parameter of the alloys for different In concentrations by high resolution X-ray diffraction. The In concentration was determined assuming Vegard's law for the alloy lattice parameter. The optical energy gap of InxGa1-xN has been determined by transmittance measurements from absorption edges for several In concentrations. Our results show that the alloys have a direct band gap for all In concentrations and a bowing parameter b=1.84.

  11. Near-zero temperature coefficient of resistivity associated with magnetic ordering in antiperovskite Mn3+xNi1-xN

    NASA Astrophysics Data System (ADS)

    Deng, Sihao; Sun, Ying; Wang, Lei; Wu, Hui; Shi, Kewen; Hu, Pengwei; Huang, Qingzhen; Wang, Cong

    2016-01-01

    The near-zero temperature coefficient of resistivity (NZ-TCR) behavior is reported in the antiperovskite compounds Mn3+xNi1-xN (0 ≤ x ≤ 0.333). Our results indicate that the broad temperature range (above 275 K extending to above 220 K) of NZ-TCR is obtained by Mn doping at the Ni site. The short-range magnetic ordering is revealed by both neutron powder diffraction and inverse magnetic susceptibility. Further, we find a strong correlation between the anomalous resistivity change of Mn3+xNi1-xN from the metal-like to the NZ-TCR behavior and the lack of the long-range magnetic ordering. The possible mechanism of NZ-TCR behavior is discussed using the spin-disorder scattering model.

  12. Pulsed pyroelectric crystal-powered gamma source

    SciTech Connect

    Chen, A. X.; Antolak, A. J.; Leung, K.-N.; Raber, T. N.; Morse, D. H.

    2013-04-19

    A compact pulsed gamma generator is being developed to replace radiological sources used in commercial, industrial and medical applications. Mono-energetic gammas are produced in the 0.4 - 1.0 MeV energy range using nuclear reactions such as {sup 9}Be(d,n{gamma}){sup 10}B. The gamma generator employs an RF-driven inductively coupled plasma ion source to produce deuterium ion current densities up to 2 mA/mm{sup 2} and ampere-level current pulses can be attained by utilizing an array extraction grid. The extracted deuterium ions are accelerated to approximately 300 keV via a compact stacked pyroelectric crystal system and then bombard the beryllium target to generate gammas. The resulting microsecond pulse of gammas is equivalent to a radiological source with curie-level activity.

  13. Gamma-Rhythmic Gain Modulation.

    PubMed

    Ni, Jianguang; Wunderle, Thomas; Lewis, Christopher Murphy; Desimone, Robert; Diester, Ilka; Fries, Pascal

    2016-10-05

    Cognition requires the dynamic modulation of effective connectivity, i.e., the modulation of the postsynaptic neuronal response to a given input. If postsynaptic neurons are rhythmically active, this might entail rhythmic gain modulation, such that inputs synchronized to phases of high gain benefit from enhanced effective connectivity. We show that visually induced gamma-band activity in awake macaque area V4 rhythmically modulates responses to unpredictable stimulus events. This modulation exceeded a simple additive superposition of a constant response onto ongoing gamma-rhythmic firing, demonstrating the modulation of multiplicative gain. Gamma phases leading to strongest neuronal responses also led to shortest behavioral reaction times, suggesting functional relevance of the effect. Furthermore, we find that constant optogenetic stimulation of anesthetized cat area 21a produces gamma-band activity entailing a similar gain modulation. As the gamma rhythm in area 21a did not spread backward to area 17, this suggests that postsynaptic gamma is sufficient for gain modulation. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Complete Genome Sequence of Staphylococcus aureus XN108, an ST239-MRSA-SCCmec III Strain with Intermediate Vancomycin Resistance Isolated in Mainland China

    PubMed Central

    Zhang, Xia; Xu, Xiaomeng; Yuan, Wenchang; Hu, Qiwen; Shang, Weilong; Hu, Xiaomei

    2014-01-01

    ST239-MRSA-SCCmec III (ST239, sequence type 239; MRSA, methicillin-resistant Staphylococcus aureus; SCCmec III, staphylococcal cassette chromosome mec type III) is the most predominant clone of hospital-acquired methicillin-resistant S. aureus in mainland China. We report here the complete genome sequence of XN108, the first vancomycin-intermediate S. aureus strain isolated from a steam-burned patient with a wound infection. PMID:25059856

  15. Bandgap measurements and the peculiar splitting of E2H phonon modes of InxAl1-xN nanowires grown by plasma assisted molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Tangi, Malleswararao; Mishra, Pawan; Janjua, Bilal; Ng, Tien Khee; Anjum, Dalaver H.; Prabaswara, Aditya; Yang, Yang; Albadri, Abdulrahman M.; Alyamani, Ahmed Y.; El-Desouki, Munir M.; Ooi, Boon S.

    2016-07-01

    The dislocation free InxAl1-xN nanowires (NWs) are grown on Si(111) by nitrogen plasma assisted molecular beam epitaxy in the temperature regime of 490 °C-610 °C yielding In composition ranges over 0.50 ≤ x ≤ 0.17. We study the optical properties of these NWs by spectroscopic ellipsometry (SE), photoluminescence, and Raman spectroscopies since they possesses minimal strain with reduced defects comparative to the planar films. The optical bandgap measurements of InxAl1-xN NWs are demonstrated by SE where the absorption edges of the NW samples are evaluated irrespective of substrate transparency. A systematic Stoke shift of 0.04-0.27 eV with increasing x was observed when comparing the micro-photoluminescence spectra with the Tauc plot derived from SE. The micro-Raman spectra in the NWs with x = 0.5 showed two-mode behavior for A1(LO) phonons and single mode behavior for E2H phonons. As for x = 0.17, i.e., high Al content, we observed a peculiar E2H phonon mode splitting. Further, we observe composition dependent frequency shifts. The 77 to 600 K micro-Raman spectroscopy measurements show that both AlN- and InN-like modes of A1(LO) and E2H phonons in InxAl1-xN NWs are redshifted with increasing temperature, similar to that of the binary III group nitride semiconductors. These studies of the optical properties of the technologically important InxAl1-xN nanowires will path the way towards lasers and light-emitting diodes in the wavelength of the ultra-violet and visible range.

  16. Negative anisotropic magnetoresistance resulting from minority spin transport in NixFe4-xN (x = 1 and 3) epitaxial films

    NASA Astrophysics Data System (ADS)

    Takata, Fumiya; Kabara, Kazuki; Ito, Keita; Tsunoda, Masakiyo; Suemasu, Takashi

    2017-01-01

    We grew 50 nm-thick NixFe4-xN (x = 1 and 3) epitaxial films on a SrTiO3(001) single-crystal substrate by molecular beam epitaxy and measured their anisotropic magnetoresistance (AMR) ratios rAMR in the temperature range of 5-300 K with current directions set along either NixFe4-xN [100] or [110]. A negative rAMR was obtained up to 200 K or higher. Their magnitude | rAMR | increased with decreasing temperature. From the negative AMR effect and the negative spin-polarization of density of states for NixFe4-xN at the Fermi level, it can be stated that the minority spin transport is dominant in NixFe4-xN, similar to Fe4N and Co3FeN. The rAMR depends on the current direction that arises from the current direction dependence of s-d scattering. In the case of Ni3FeN, the rAMR decreased to nearly zero at 260 K. This temperature agreed well with the Curie temperature determined from the temperature dependence of magnetization. The AMR curves were reproduced well by using both cos2ϕ and cos4ϕ components below 100 K, whereas a cos2ϕ component was enough to fit those obtained above 100 K. It is assumed that the tetragonal crystal field was enhanced at low temperatures (<100 K) similar to Fe4N (<50 K).

  17. Free polaron energy levels in AlyGa1-yN/AlxGa1-xN triangle quantum well structures

    NASA Astrophysics Data System (ADS)

    Pan, Hong Yu; Zhao, Feng Qi

    2017-06-01

    In this work, a variational method is used to examine the problems relevant to the free polaron energy spectrum in a wurtzite AlyGa1-yN/AlxGa1-xN triangle quantum well structure. The numerical calculations for the ground state energy, transition energy and polaron energy shifts as the functions of well-width d and composition x are carried out by considering the anisotropies of the parameters, such as the optical phonon frequency, dielectric constant and electron effective mass, as well as their observed changes with coordinate z in this system. The research results show that the polaron energy shift caused by the electron-optical phonon interaction is large, and leads to an obvious energy decrease in the AlyGa1-yN/AlxGa1-xN triangular quantum well structure. The contribution of the confined phonon is found to increase with the increasing of the well-width and composition x, while that of the half space phonon is observed to decrease with the increasing of the well-width and composition x. The total contribution of the phonon increases with the increasing composition x, while a minimum is found to occur to the total contribution of the phonon during the decreasing process with the well-width. As the d increases, the free polaron energies and transition energies decrease. Meanwhile, with the increasing of the composition x, the energy and transition energy are found to be increased. In the AlyGa1-yN/AlxGa1-xN triangular quantum well structure, the trends of the free polaron energy, transition energy and polaron energy shifts with the well-width and composition x are found to be similar to those in the GaN/AlxGa1-xN square quantum well structure. However, the corresponding values in the triangular quantum well structure are obviously greater than those in the square quantum well structure.

  18. High-Throughput Investigation of a Lead-Free AlN-Based Piezoelectric Material, (Mg,Hf)xAl1-xN.

    PubMed

    Nguyen, Hung H; Oguchi, Hiroyuki; Van Minh, Le; Kuwano, Hiroki

    2017-06-12

    We conducted a high-throughput investigation of the fundamental properties of (Mg,Hf)xAl1-xN thin films (0 < x < 0.24) aiming for developing high-performance AlN-based piezoelectric materials. For the high-throughput investigation, we prepared composition-gradient (Mg,Hf)xAl1-xN films grown on a Si(100) substrate at 600 °C by cosputtering AlN and MgHf targets. To measure the properties of the various compositions at different positions within a single sample, we used characterization techniques with spatial resolution. X-ray diffraction (XRD) with a beam spot diameter of 1.0 mm verified that Mg and Hf had substituted into the Al sites and caused an elongation of the c-axis of AlN from 5.00 Å for x = 0 to 5.11 Å for x = 0.24. In addition, the uniaxial crystal orientation and high crystallinity required for piezoelectric materials to be used as application devices were confirmed. The piezoelectric response microscope indicated that this c-axis elongation increased the piezoelectric coefficient almost linearly from 1.48 pm/V for x = 0 to 5.19 pm/V for x = 0.24. The dielectric constants of (Mg,Hf)xAl1-xN were investigated using parallel plate capacitor structures with ∼0.07 mm(2) electrodes and showed a slight increase by substitution. These results verified that (Mg,Hf)xAl1-xN is a promising material for piezoelectric-based application devices, especially for vibrational energy harvesters.

  19. M5-brane defect and quantum Hall effect in AdS{sub 4}xN(1,1)/N=3 superconformal field theory

    SciTech Connect

    Fujita, Mitsutoshi

    2011-05-15

    We study the d=11 gravity dual AdS{sub 4}xN(1,1) of the d=3 N=3 flavored Chern-Simons-matter theory. In the dual gravity side, we analyze the M5-brane filling AdS{sub 3} inside AdS{sub 4} and derive the quantized Hall conductivity of the dual gauge theory. In the gauge theory side, this M5-brane intersects the gauge theory at the codimension-one defect.

  20. Computational Replication of the Primary Isotope Dependence of Secondary Kinetic Isotope Effects in Solution Hydride-Transfer Reactions: Supporting the Isotopically Different Tunneling Ready State Conformations.

    PubMed

    Derakhshani-Molayousefi, Mortaza; Kashefolgheta, Sadra; Eilers, James E; Lu, Yun

    2016-06-30

    We recently reported a study of the steric effect on the 1° isotope dependence of 2° KIEs for several hydride-transfer reactions in solution (J. Am. Chem. Soc. 2015, 137, 6653). The unusual 2° KIEs decrease as the 1° isotope changes from H to D, and more in the sterically hindered systems. These were explained in terms of a more crowded tunneling ready state (TRS) conformation in D-tunneling, which has a shorter donor-acceptor distance (DAD) than in H-tunneling. To examine the isotopic DAD difference explanation, in this paper, following an activated motion-assisted H-tunneling model that requires a shorter DAD in a heavier isotope transfer process, we computed the 2° KIEs at various H/D positions at different DADs (2.9 Å to 3.5 Å) for the hydride-transfer reactions from 2-propanol to the xanthylium and thioxanthylium ions (Xn(+) and TXn(+)) and their 9-phenyl substituted derivatives (Ph(T)Xn(+)). The calculated 2° KIEs match the experiments and the calculated DAD effect on the 2° KIEs fits the observed 1° isotope effect on the 2° KIEs. These support the motion-assisted H-tunneling model and the isotopically different TRS conformations. Furthermore, it was found that the TRS of the sterically hindered Ph(T)Xn(+) system does not possess a longer DAD than that of the (T)Xn(+) system. This predicts a no larger 1° KIE in the former system than in the latter. The observed 1° KIE order is, however, contrary to the prediction. This implicates the stronger DAD-compression vibrations coupled to the bulky Ph(T)Xn(+) reaction coordinate.

  1. Evaluation of Sysmex XN-1000 hematology analyzer for cell count and screening of malignant cells of serous cavity effusion

    PubMed Central

    Xu, Weiyi; Yu, Qian; Xie, Lixia; Chen, Baode; Zhang, Ling

    2017-01-01

    Abstract Over the years, with the advancement in hematology analyzer technology, the use of fluid analysis method has seen a drastic increase in clinical examinations. Cell counting and classification in independent body fluid analysis method are conducted by semiconductor laser flow cytometry and nucleic acid fluorescence staining techniques. This study is to evaluate the efficacy of Sysmex XN-1000 hematology analyzer in cell counting and to screen malignant cells with serous cavity effusion. Specimens (N = 206) with serous cavity effusion from our hospital were included in this study. Manual and instrumental methods for cell counting, nucleated cell classification, and high-fluorescent cells (HFC) were used in this study. The correlation between RBC, nucleated cell count (NUC), the percentages of polymorphonuclear cell (PMN%), and mononuclear cells (MN%) was statistically analyzed using manual and instrumental methods. The regression equations of RBC, NUC, PMN%, and MN% in the manual and instrumental methods were RBC y = 0.88x + 426.4; NUC y = 0.85x + 33.4; PMN% y = 0.91x + 4.2; and MN% y = 0.91x + 5.1. Correlation coefficient R2 was 0.99, 0.98, 0.90, and 0.90 (P < .001). ROC curve analysis showed that when the cut-off value of HFC% was 4.4% and HFC# was 24.5/μL, area under curve (AUC), sensitivity, specificity, and 95% confidence interval were 0.707, 0.792, 0.558, 0.637–0.777; 0.708, 0.753, 0.550, 0.635–0.780, respectively. XN-1000 hematology analyzer body fluid method can accurately and rapidly count cell and nucleated cell classification with serous cavity effusion. HFC can indicate the possible existence of malignant cells; however, further investigations are required to validate its efficacy. PMID:28682907

  2. Establishment of Age- and Gender-Specific Reference Ranges for 36 Routine and 57 Cell Population Data Items in a New Automated Blood Cell Analyzer, Sysmex XN-2000.

    PubMed

    Park, Sang Hyuk; Park, Chan Jeoung; Lee, Bo Ra; Kim, Mi Jeong; Han, Min Young; Cho, Young Uk; Jang, Seongsoo

    2016-05-01

    We established age- and gender-specific reference ranges for the 36 routine complete blood cell (CBC) and 57 cell population data (CPD) items in the Sysmex XN-2000 (Sysmex, Japan). In total, 280 peripheral blood samples were obtained from an equal number of healthy adults. Values for 36 routine items and 57 CPD items were obtained for each sample, and the results were categorized into six subgroups (N>39 in each subgroup) according to patient age (20-40, 41-60, and >60 yr) and gender (male and female), and compared with respect to age and gender differences. The majority of data items (22 of 36 routine CBC items and 44 of 57 CPD items) exhibited significant differences (P≤0.05) in their results with respect to age or gender, and several red cell-, lymphocyte-, and platelet-related data tended to decrease in women or older adults. These results provide a basis for establishing age- and gender-specific reference ranges for routine and CPD items in Sysmex XN-2000. Furthermore, these reference ranges could be used to determine clinical significance for new items of Sysmex XN-2000 in further studies.

  3. Shape-controlled synthesis of one-dimensional AlxGa1-xN nanotower arrays: structural characteristics and growth mechanism

    NASA Astrophysics Data System (ADS)

    Chen, Fei; Ji, Xiaohong; Lu, Zhenya; Shen, Yanhua; Zhang, Qinyuan

    2014-02-01

    Tower-like AlxGa1-xN nanostructures with flat tops/sharp tips have been synthesized by catalyst-template-free chemical vapour deposition. Structural and morphological properties have been systematically investigated by x-ray diffraction, field-emission scanning electron microscopy, and transmission electron microscopy. It has been found that typical tower-like nanostructures exhibit quasi-hexagonal nanocolumns stacking in layer-by-layer behaviour. The morphology of AlxGa1-xN nanotowers is strongly dependent on the evaporation temperature of precursors. A high evaporation temperature of precursors would induce the formation of a nanotower with large diameter and a flat top, and a low evaporation temperature of precursors would lead to the formation of a nanotower with small diameter and a sharp tip. The formation of AlxGa1-xN nanotowers has been proposed to be two-dimensional growth of hexagonal nanocolumns and one-dimensional stacking in the direction perpendicular to the previous nucleated section due to the existence of an Ehrlich-Schwoebel barrier. Raman scattering analysis reveals the hexagonal behaviour of tower-like nanostructures. The obtained nanotowers might have potential applications as functional blocks in future nanodevices.

  4. Establishment of Age- and Gender-Specific Reference Ranges for 36 Routine and 57 Cell Population Data Items in a New Automated Blood Cell Analyzer, Sysmex XN-2000

    PubMed Central

    Park, Sang Hyuk; Lee, Bo-Ra; Kim, Mi-Jeong; Han, Min-Young; Cho, Young-Uk; Jang, Seongsoo

    2016-01-01

    We established age- and gender-specific reference ranges for the 36 routine complete blood cell (CBC) and 57 cell population data (CPD) items in the Sysmex XN-2000 (Sysmex, Japan). In total, 280 peripheral blood samples were obtained from an equal number of healthy adults. Values for 36 routine items and 57 CPD items were obtained for each sample, and the results were categorized into six subgroups (N>39 in each subgroup) according to patient age (20-40, 41-60, and >60 yr) and gender (male and female), and compared with respect to age and gender differences. The majority of data items (22 of 36 routine CBC items and 44 of 57 CPD items) exhibited significant differences (P≤0.05) in their results with respect to age or gender, and several red cell-, lymphocyte-, and platelet-related data tended to decrease in women or older adults. These results provide a basis for establishing age- and gender-specific reference ranges for routine and CPD items in Sysmex XN-2000. Furthermore, these reference ranges could be used to determine clinical significance for new items of Sysmex XN-2000 in further studies. PMID:26915613

  5. Stress controlled pulsed direct current co-sputtered Al{sub 1−x}Sc{sub x}N as piezoelectric phase for micromechanical sensor applications

    SciTech Connect

    Fichtner, Simon; Reimer, Tim; Chemnitz, Steffen; Wagner, Bernhard; Lofink, Fabian

    2015-11-01

    Scandium alloyed aluminum nitride (Al{sub 1−x}Sc{sub x}N) thin films were fabricated by reactive pulsed direct current co-sputtering of separate scandium and aluminum targets with x ≤ 0.37. A significant improvement of the clamped transversal piezoelectric response to strain e{sub 31,f} from −1.28 C/m{sup 2} to −3.01 C/m{sup 2} was recorded, while dielectric constant and loss angle remain low. Further, the built-in stress level of Al{sub 1−x}Sc{sub x}N was found to be tuneable by varying pressure, Ar/N{sub 2} ratio, and Sc content. The thus resulting enhancement of the expectable signal to noise ratio by a factor of 2.1 and the ability to control built-in stress make the integration of Al{sub 1−x}Sc{sub x}N as the piezoelectric phase of micro-electro-mechanical system sensor applications highly attractive.

  6. Point defects introduced by InN alloying into In{sub x}Ga{sub 1-x}N probed using a monoenergetic positron beam

    SciTech Connect

    Uedono, A.; Tsutsui, T.; Watanabe, T.; Kimura, S.; Zhang, Y.; Lozac'h, M.; Sang, L. W.; Sumiya, M.; Ishibashi, S.

    2013-03-28

    Native defects in In{sub x}Ga{sub 1-x}N (x = 0.06-0.14) grown by metal organic chemical vapor deposition were studied using a monoenergetic positron beam. Measurements of Doppler broadening spectra of the annihilation radiation as a function of incident positron energy for In{sub x}Ga{sub 1-x}N showed that vacancy-type defects were introduced with increasing InN composition, and the major defect species was identified as complexes between a cation vacancy and a nitrogen vacancy. The concentration of the divacancy, however, was found to be suppressed by Mg doping. The momentum distribution of electrons at the In{sub x}Ga{sub 1-x}N/GaN interface was close to that in defect-free GaN or In{sub x}Ga{sub 1-x}N, which was attributed to localization of positrons at the interface due to the built-in electric field, and to suppression of positron trapping by vacancy-type defects. We have also shown that the diffusion property of positrons is sensitive to an electric field near the In{sub x}Ga{sub 1-x}N/GaN interface.

  7. About cosmic gamma ray lines

    NASA Astrophysics Data System (ADS)

    Diehl, Roland

    2017-06-01

    Gamma ray lines from cosmic sources convey the action of nuclear reactions in cosmic sites and their impacts on astrophysical objects. Gamma rays at characteristic energies result from nuclear transitions following radioactive decays or high-energy collisions with excitation of nuclei. The gamma-ray line from the annihilation of positrons at 511 keV falls into the same energy window, although of different origin. We present here the concepts of cosmic gamma ray spectrometry and the corresponding instruments and missions, followed by a discussion of recent results and the challenges and open issues for the future. Among the lessons learned are the diffuse radioactive afterglow of massive-star nucleosynthesis in 26Al and 60Fe gamma rays, which is now being exploited towards the cycle of matter driven by massive stars and their supernovae; large interstellar cavities and superbubbles have been recognised to be of key importance here. Also, constraints on the complex processes making stars explode as either thermonuclear or core-collapse supernovae are being illuminated by gamma-ray lines, in this case from shortlived radioactivities from 56Ni and 44Ti decays. In particular, the three-dimensionality and asphericities that have recently been recognised as important are enlightened in different ways through such gamma-ray line spectroscopy. Finally, the distribution of positron annihilation gamma ray emission with its puzzling bulge-dominated intensity disctribution is measured through spatially-resolved spectra, which indicate that annihilation conditions may differ in different parts of our Galaxy. But it is now understood that a variety of sources may feed positrons into the interstellar medium, and their characteristics largely get lost during slowing down and propagation of positrons before annihilation; a recent microquasar flare was caught as an opportunity to see positrons annihilate at a source.

  8. A Comparison of Mindray BC-6800, Sysmex XN-2000, and Beckman Coulter LH750 Automated Hematology Analyzers: A Pediatric Study.

    PubMed

    Ciepiela, Olga; Kotuła, Iwona; Kierat, Szymon; Sieczkowska, Sandra; Podsiadłowska, Anna; Jenczelewska, Anna; Księżarczyk, Karolina; Demkow, Urszula

    2016-11-01

    Modern automated laboratory hematology analyzers allow the measurement of over 30 different hematological parameters useful in the diagnostic and clinical interpretation of patient symptoms. They use different methods to measure the same parameters. Thus, a comparison of complete blood count made by Mindray BC-6800, Sysmex XN-2000 and Beckman Coulter LH750 was performed. A comparison of results obtained by automated analysis of 807 anticoagulated blood samples from children and 125 manual microscopic differentiations were performed. This comparative study included white blood cell count, red blood cell count, and erythrocyte indices, as well as platelet count. The present study showed a poor level of agreement between white blood cell enumeration and differentiation of the three automated hematology analyzers under comparison. A very good agreement was found when comparing manual blood smear and automated granulocytes, monocytes, and lymphocytes differentiation. Red blood cell evaluation showed better agreement than white blood cells between the studied analyzers. To conclude, studied instruments did not ensure satisfactory interchangeability and did not facilitate a substitution of one analyzer by another. © 2016 Wiley Periodicals, Inc.

  9. Optical and structural properties of Eu-implanted In{sub x}Al{sub 1-x}N

    SciTech Connect

    Roqan, I. S.; O'Donnell, K. P.; Martin, R. W.; Trager-Cowan, C.; Matias, V.; Vantomme, A.; Lorenz, K.; Alves, E.; Watson, I. M.

    2009-10-15

    Off-axis implantation of 80 keV Eu ions into epitaxial c-plane InAlN/GaN bilayers confines rare-earth (RE) doping largely to the InAlN layer. Rutherford backscattering spectrometry and x-ray diffraction show good correlations between the Eu{sup 3+} emission linewidth and key structural parameters of In{sub x}Al{sub 1-x}N films on GaN in the composition range near lattice matching (xapprox0.17). In contrast to GaN:Eu, selectively excited photoluminescence (PL) and PL excitation spectra reveal the presence of a single dominant optical center in InAlN. Eu{sup 3+} emission from In{sub 0.13}Al{sub 0.87}N:Eu also shows significantly less thermal quenching than GaN:Eu. InAlN films are therefore superior to GaN for RE optical doping.

  10. Temperature-dependent elastic properties of Ti{sub 1−x}Al{sub x}N alloys

    SciTech Connect

    Shulumba, Nina; Hellman, Olle; Rogström, Lina; Raza, Zamaan; Tasnádi, Ferenc; Odén, Magnus; Abrikosov, Igor A.

    2015-12-07

    Ti{sub 1−x}Al{sub x}N is a technologically important alloy that undergoes a process of high temperature age-hardening that is strongly influenced by its elastic properties. We have performed first principles calculations of the elastic constants and anisotropy using the symmetry imposed force constant temperature dependent effective potential method, which include lattice vibrations and therefore the effects of temperature, including thermal expansion and intrinsic anharmonicity. These are compared with in situ high temperature x-ray diffraction measurements of the lattice parameter. We show that anharmonic effects are crucial to the recovery of finite temperature elasticity. The effects of thermal expansion and intrinsic anharmonicity on the elastic constants are of the same order, and cannot be considered separately. Furthermore, the effect of thermal expansion on elastic constants is such that the volume change induced by zero point motion has a significant effect. For TiAlN, the elastic constants soften non-uniformly with temperature: C{sub 11} decreases substantially when the temperature increases for all compositions, resulting in an increased anisotropy. These findings suggest that an increased Al content and annealing at higher temperatures will result in a harder alloy.

  11. Band-gap Engineering in Sputter Deposited Amorphous/Microcrystalline Sc(x)Ga(1-x)N

    NASA Technical Reports Server (NTRS)

    Little, Mark E.; Kordesch, Martin E.; Bushnell, Dennis M. (Technical Monitor)

    2001-01-01

    Reactive sputtering was used to grow thin films of Sc(x)Ga(1-x)N with scandium concentrations of 20%-70% on quartz substrates at temperatures of 300-675 K. X-ray diffraction (XRD) of the films showed either weak or no structure, suggesting the films are amorphous or microcrystalline. Optical absorption spectra were taken of each sample and the optical band gap was determined. The band gap varied linearly with increasing Ga concentration between 2.0 and 3.5 eV. Ellipsometry was used to confirm the band gap measurements and provide optical constants in the range 250-1200 nm. ScN and GaN have different crystal structures (rocksalt and wurzite, respectively), and thus may form a heterogeneous mixture as opposed to an alloy. Since the XRD data were inconclusive, bilayers of ScN/GaN were grown and optical absorption spectra taken. A fundamental difference in the spectra between the bilayer films and alloy films was seen, suggesting the films are alloys, not heterogeneous mixtures.

  12. Clinical significance of cell population data (CPD) on Sysmex XN-9000 in septic patients with our without liver impairment

    PubMed Central

    Seghezzi, Michela; Vavassori, Mauro; Dominoni, Paola; Apassiti Esposito, Sara; Manenti, Barbara; Mecca, Tommaso; Marchesi, Gianmariano; Castellucci, Enrico; Azzarà, Giovanna; Ottomano, Cosimo; Lippi, Giuseppe

    2016-01-01

    Background This study evaluated the clinical significance of cell population data (CPD) parameters obtained on Sysmex XN-9000 in septic patients admitted to intensive care unit (ICU) and stratified according to liver function. Methods The study population consisted in 84 patients, 44 of whom did not develop sepsis (NS), whereas the remaining 40 developed sepsis (SE) (n=24) or septic shock (SS) (n=16). Two hundred ostensibly healthy blood donors [healthy subjects (HS)], undergoing routine blood testing before a regular blood donation, were studied. Results Except for neutrophils and lymphocytes cell size (NE-FCS and LY-Z), all other CPD values were significantly different in ICU patients compared to HS. Neutrophils and monocytes fluorescence intensity (NE-SFL and MO-X) values were significantly higher in SS compared to sepsis and not develop sepsis patients. The value of many parameters was also different according to liver function. Overall, MO-X and neutrophils fluorescence intensity (NE-SFL) exhibited the best performance for diagnosing sepsis in all patients (AUC, 0.75 and 0.72), as well as in those with (AUC, 0.95 and 0.89) or without (AUC, 0.72 for both) liver impairment. These parameters were also significantly correlated with Sequential Organ Failure Assessment (SOFA) score. Conclusions This study suggested that some novel CPD parameters (namely NE-SFL and MO-X) may provide useful information for diagnosis and management of sepsis. PMID:27942509

  13. Electrical characteristics of AlxGa1-xN Schottky diodes prepared by a two-step surface treatment

    NASA Astrophysics Data System (ADS)

    Motayed, Abhishek; Sharma, Ashok; Jones, Kenneth A.; Derenge, Michael A.; Iliadis, Agis A.; Mohammad, S. Noor

    2004-09-01

    Near-ideal Schottky barrier contacts to n-type Al0.22Ga0.78N have been developed by a two-step surface treatment technique. Plasma etching of the AlxGa1-xN surface prior to Schottky metal deposition, combined with sequential chemical treatment of the etched surface, holds promise for developing high quality low-leakage Schottky contacts for low noise applications and for recessed gate high electron mobility transistors. In this work, the effect of postetch chemical treatment of the n-type Al0.22Ga0.78N surface on the performance of the Ni /Au based Schottky contact has been investigated. Three different types of chemical treatment: viz, reactive ion etching, reactive ion etching plus dipping in hot aqua regia, and reactive ion etching plus dipping in hot KOH, are studied. Detailed current-voltage studies of three different surface treated diodes and a comparison with as-deposited diodes reveal significant improvement in the diode characteristics. The latter surface treatment yields Ni /Au Schottky diodes with very low reverse leakage currents, breakdown voltages greater than 44V, and an ideality factor as low as 1.14.

  14. Optical investigation of semi-polar (11-22) AlxGa1-xN with high Al composition

    NASA Astrophysics Data System (ADS)

    Li, Z.; Wang, L.; Jiu, L.; Bruckbauer, J.; Gong, Y.; Zhang, Y.; Bai, J.; Martin, R. W.; Wang, T.

    2017-02-01

    Exciton localization generally disturbs uniform population inversion, leading to an increase in the threshold current for lasing. High Al content AlGaN is required for the fabrication of deep ultra-violet (DUV) laser diodes (LDs), and this also generates exciton localization. Temperature-dependent photoluminescence and room temperature cathodoluminescence measurements have been performed on high quality semi-polar (11-22) AlxGa1-xN alloys with high Al composition ranging from 0.37 to 0.56 in order to systematically study the optical properties (in particular, exciton localization) of both the near-band-edge emission and the basal-plane stacking faults related emission, demonstrating different behaviours. Further comparison with the exciton localization of their c-plane counterparts has been performed, exhibiting that the exciton localization in semi-polar (11-22) AlGaN is much smaller than that in c-plane AlGaN. As a consequence, semi-polar (11-22) AlGaN demonstrates a greater potential than its c-plane counterpart in terms of the growth of DUV LDs.

  15. Impact of implantation geometry and fluence on structural properties of AlxGa1-xN implanted with thulium

    NASA Astrophysics Data System (ADS)

    Fialho, M.; Magalhães, S.; Chauvat, M. P.; Ruterana, P.; Lorenz, K.; Alves, E.

    2016-10-01

    AlxGa1-xN (x = 0.15 and 0.77) films, grown by halide vapor phase epitaxy, were implanted with 300 keV Tm ions. Implantation damage accumulation is investigated with Rutherford backscattering spectrometry/channeling (RBS/C), transmission electron microscopy (TEM), and high resolution X-ray diffraction (XRD). Distinct damage behavior for samples with different AlN contents was found. Surface nanocrystallization occurs for samples with x = 0.15, similar to implantation effects observed in GaN. Samples with x = 0.77 approach the behavior of AlN. In particular, surface nanocrystallization is suppressed and the depth range of the stacking fault network, typical for implanted III-nitrides, is decreased. The crystalline quality of the sample with x = 0.15 was investigated to compare random and channeled implantation, showing less concentration of damage but with a higher range for channeled implantation. Surprisingly, the strain field caused by the implantation reaches much deeper into the sample than the defect profiles measured by RBS/C and TEM. This is attributed to the fact that XRD is much more sensitive to low defect densities caused by ions which are channeled to deep regions of the sample.

  16. Electronic and optical properties of TaO1-xN1+x-based alloys

    NASA Astrophysics Data System (ADS)

    Al-Aqtash, Nabil; Apostol, Florin; Mei, Wai-Ning; Sabirianov, Renat F.

    2013-02-01

    TaON is considered as a potential candidate as a visible-light responsive photocatalyst. We report the results of ab initio studies of electronic structure of TaON-based alloys. Specifically, we show that the position of conduction and valence band can be modified by varying the oxygen and nitrogen concentrations in TaO1-xN1+x. We find that the band gap decreases monotonically with the increase of N/O ratio. The band gap energy is decreased in monoclinic TaON from near 2.3 eV to just over 1.7 eV (i.e., by 35%) when N/O ratio is increased from 3/5 to 5/3. Our calculations show that the band gap reduces in a series of experimentally fabricated alloys ZrTa3O5N3→TaON→YTa7O7N8. The band gap reduction is mostly associated with the change in the position of the valence band due to the hybridization of N 2p states, while the conduction band consisting mostly of Ta 5d-states is not sensitive to N content. The calculated optical absorption spectra show reduction in the optical band gap with increasing N/O ratio.

  17. Maximum Torque and Momentum Envelopes for Reaction Wheel Arrays

    NASA Technical Reports Server (NTRS)

    Reynolds, R. G.; Markley, F. Landis

    2001-01-01

    Spacecraft reaction wheel maneuvers are limited by the maximum torque and/or angular momentum which the wheels can provide. For an n-wheel configuration, the torque or momentum envelope can be obtained by projecting the n-dimensional hypercube, representing the domain boundary of individual wheel torques or momenta, into three dimensional space via the 3xn matrix of wheel axes. In this paper, the properties of the projected hypercube are discussed, and algorithms are proposed for determining this maximal torque or momentum envelope for general wheel configurations. Practical implementation strategies for specific wheel configurations are also considered.

  18. Understanding band alignments in semiconductor heterostructures: Composition dependence and type-I-type-II transition of natural band offsets in nonpolar zinc-blende AlxGa1 -xN /AlyGa1 -yN composites

    NASA Astrophysics Data System (ADS)

    Landmann, M.; Rauls, E.; Schmidt, W. G.

    2017-04-01

    The composition dependence of the natural band alignment at nonpolar AlxGa1 -xN /AlyGa1 -yN heterojunctions is investigated via hybrid functional based density functional theory. Accurate band-gap data are provided using Heyd-Scuseria-Ernzerhof (HSE) type hybrid functionals with a composition dependent exact-exchange contribution. The unstrained band alignment between zincblende (zb) AlxGa1 -xN semiconductor alloys is studied within the entire ternary composition range utilizing the Branch-point technique to align the energy levels related to the bulklike direct Γv→Γc and indirect, pseudodirect, respectively, Γv→Xc type transitions in zb-AlxGa1 -xN . While the zb-GaN/AlxGa1 -xN band edges consistently show a type-I alignment, the relative position of fundamental band edges changes to a type-II alignment in the Al-rich composition ranges of zb-AlxGa1 -xN /AlN and zb-AlxGa1 -xN /AlyGa1 -yN systems. The presence of a direct-indirect band-gap transition at xc=0.63 in zb-AlxGa1 -xN semiconductor alloys gives rise to a notably different composition dependence of band discontinuities in the direct and indirect energy-gap ranges. Below the critical direct-indirect Al/Ga-crossover concentration, the band offsets show a close to linear dependence on the alloy composition. In contrast, notable bowing characteristics of all band discontinuities are observed above the critical crossover composition.

  19. Exclusive production of pion pairs in {gamma}*{gamma} collisions at Large Q{sup 2}

    SciTech Connect

    Diehl, M.

    2000-03-15

    The authors perform a QCD analysis of the exclusive production of two mesons in {gamma}*{gamma} collisions in the kinematical domain of large photon virtuality Q and small hadronic invariant mass W. This reaction is dominated by a scale invariant mechanism which factorizes into a perturbative subprocess, {gamma}*{gamma} {r{underscore}arrow} q{anti q} or {gamma}*{gamma} {r{underscore}arrow} gg, and a generalized two-meson distribution amplitude. The authors develop in detail the phenomenology of this process at e{sup +}e{sup {minus}} colliders. Using a simple model for the two-pion distribution amplitude, based on its general properties, the authors estimate the cross section for the kinematics accessible at BABAR, BELLE, CLEO and LEP.

  20. Measurement of gamma and 2 beta + gamma

    SciTech Connect

    Albert, J.

    2005-01-03

    We report on the initial measurements of the angle {gamma} and the sum of angles 2{beta} +{gamma} of the Unitarity Triangle. When compared with indirect information on the value of {gamma} from other measurements of CKM parameters, the measurement of these angles will provide a precise test of Standard Model predictions, as statistics increase. There are several methods for directly measuring {gamma} and 2{beta} +{gamma}. We report on the status of each of these techniques, and the resulting constraints on the values of these angles.

  1. NUCLEAR REACTION MODELING FOR RIA ISOL TARGET DESIGN

    SciTech Connect

    S. MASHNIK; ET AL

    2001-03-01

    Los Alamos scientists are collaborating with researchers at Argonne and Oak Ridge on the development of improved nuclear reaction physics for modeling radionuclide production in ISOL targets. This is being done in the context of the MCNPX simulation code, which is a merger of MCNP and the LAHET intranuclear cascade code, and simulates both nuclear reaction cross sections and radiation transport in the target. The CINDER code is also used to calculate the time-dependent nuclear decays for estimating induced radioactivities. They give an overview of the reaction physics improvements they are addressing, including intranuclear cascade (INC) physics, where recent high-quality inverse-kinematics residue data from GSI have led to INC spallation and fission model improvements; and preequilibrium reactions important in modeling (p,xn) and (p,xnyp) cross sections for the production of nuclides far from stability.

  2. Compact Electronic Gamma Source For Radiotherapy

    SciTech Connect

    Chen, A. X.; Antolak, A. J.; Raber, T. N.; Morse, D. H.; Leung, K.-N.

    2011-06-01

    A compact mono-energetic gamma source is being developed to replace the radiological sources used in radiotherapy and other medical instruments. The electronic gamma source utilizes low-energy nuclear reactions to generate gammas in the 0.5 to 1.0 MeV energy range. Independent control of the ion current and energy is achieved by decoupling the RF-driven ion source and pyroelectric crystal-based acceleration systems The ions are accelerated to voltages above 100 keV and bombard a reaction target to produce gammas. Thermal management of the pyroelectric crystal-based accelerator is achieved by convective dielectric fluid flow around the crystal. This approach provides better temperature uniformity in the crystal and higher dielectric strength for suppressing voltage breakdown and enabling faster thermal cycling rates.

  3. Surrogate Nuclear Reactions using STARS

    SciTech Connect

    Bernstein, L A; Burke, J T; Church, J A; Ahle, L; Cooper, J R; Hoffman, R D; Moody, K; Punyon, J; Schiller, A; Algin, E; Plettner, C; Ai, H; Beausang, C W; Casten, R F; Hughes, R; Ricard-McCutchan, E; Meyer, D; Ressler, J J; Caggiano, J A; Zamfir, N V; Amro, H; Heinz, A; Fallon, P; McMahan, M A; Macchiavelli, A O; Phair, L W

    2004-10-26

    The results from two surrogate reaction experiments using the STARS (Silicon Telescope Array for Reaction Studies) spectrometer are presented. The surrogate method involves measuring the particle and/or {gamma}-ray decay probabilities of excited nuclei populated via a direct reaction. These probabilities can then be used to deduce neutron-induced reaction cross sections that lead to the same compound nuclei. In the first experiment STARS coupled to the GAMMASPHERE {gamma}-ray spectrometer successfully reproduce surrogate (n,{gamma}), (n,n'{gamma}) and (n,2n{gamma}) cross sections on {sup 155,156}Gd using Gd {sup 3}He-induced reactions. In the second series of experiments an energetic deuteron beam from the ESTU tandem at the Wright Nuclear Structure Lab at Yale University was used to obtain the ratio of fission probabilities for {sup 238}U/ {sup 236}U and {sup 237}U/ {sup 239}U populated using the {sup 236,238}U(d,d'f) and {sup 236,238}U(d,pf) reactions. Results from these experiments are presented and the implications for the surrogate reaction technique are discussed.

  4. Tumor necrosis factor alpha and interleukin 11 secreted by malignant breast epithelial cells inhibit adipocyte differentiation by selectively down-regulating CCAAT/enhancer binding protein alpha and peroxisome proliferator-activated receptor gamma: mechanism of desmoplastic reaction.

    PubMed

    Meng, L; Zhou, J; Sasano, H; Suzuki, T; Zeitoun, K M; Bulun, S E

    2001-03-01

    The dense layer of fibroblasts that accumulate around malignant breast epithelial cells (i.e., desmoplastic reaction) arises from the breast adipose tissue and provides structural and biochemical support for breast cancer. We report herein a number of epithelial-stromal interactions responsible for desmoplastic reaction in breast cancer using cultured 3T3-L1 murine fibroblasts and human adipose fibroblasts, which can be activated with a mixture of hormones to differentiate to mature adipocytes. Adipocyte differentiation was inhibited by coculturing fibroblasts with various breast cancer cell lines (T47D, MCF-7, SSC202, SSC78, and SSC30) completely or by breast cancer cell conditioned media in a dose-dependent manner; on the other hand, adipocyte differentiation was not inhibited by coculturing with normal human primary mammary epithelial cell conditioned medium. This tumor effect was eliminated using neutralizing antibodies against tumor necrosis factor (TNF)-alpha or interleukin (IL)-11. TNF-alpha and IL-11 levels were 2.5-3 times higher in T47D conditioned medium compared with control medium, and TNF-alpha transcripts were detectable in T47D but not in 3T3-L1 cells in culture, indicating that the malignant epithelial cell is the major site of cytokine production. This was confirmed in vivo in mastectomy specimens, where immunoreactive TNF-alpha and IL-11 were readily detectable in malignant epithelial cells but not in the majority of the surrounding fibroblasts. Adipocyte differentiation is mediated by the expression of a cascade of adipogenic transcription factors, including CCAAT/enhancer binding protein (C/EBP)beta, C/EBPdelta, peroxisome proliferator-activated receptor (PPAR)gamma and C/EBPalpha. C/EBPalpha and PPARgamma are essential for this process. We demonstrated by Northern analysis that exposure of activated 3T3-L1 cells to T47D cell conditioned medium strikingly decreased the levels of PPARgamma and C/EBPalpha transcripts and increased the levels of C

  5. Evaluation of micromechanical properties of buckled SiO xN y-loaded membranes by combining the Twyman-Green interferometry with nanoindentation and point-wise deflection technique

    NASA Astrophysics Data System (ADS)

    Józwik, Michal; Gorecki, Christophe; Sabac, Andrei; Delobelle, Patrick; Kujawińska, Małgorzata

    2004-05-01

    In view of applications in MOEMS technology, an interferometric technique has been developed for determination of micromechanical properties of PECVD-deposited SiO xN y thin films. By combining the Twyman-Green interferometry with nanoindentation technique, an original "point-wise" deflection method is proposed, particularly appropriated to measure the residual stress in the case of silicon membranes compressively prestressed by SiO xN y deposition. For such SiO xN y membranes, operating at the first mode of buckling, the nonindentation permits the extraction of Young's modulus and interferometry measures the out-of-plan displacements, respectively. The proposed point-wise deflection technique combines both the interferometric and Young's modulus data, giving the access to the distribution of residual stress versus the optical quality of SiO xN y films. The residual stress is monitored as a function of the refractive index of SiO xN y, establishing the relationship between the optical and micromechanical properties of deposited thin films. High measuring accuracy and resolution have been demonstrated, allowing measurements to be used to enhance PECVD process control

  6. The C-terminus of the {gamma}2 chain but not of the {beta}3 chain of laminin-332 is indirectly but indispensably necessary for integrin-mediated cell reactions

    SciTech Connect

    Navdaev, Alexei; Heitmann, Vanessa; Santana Evangelista, Karla de; Moergelin, Matthias; Wegener, Joachim; Eble, Johannes A.

    2008-02-01

    Using a recombinant mini-laminin-332, we showed that truncation of the three C-terminal amino acids of the {gamma}2 chain, but not of the C-terminal amino acid of the {beta}3 chain, completely abolished {alpha}3{beta}1 integrin binding and its cellular functions, such as attachment and spreading. However, a synthetic peptide mimicking the {gamma}2 chain C-terminus did not interfere with {alpha}3{beta}1 integrin binding or cell adhesion and spreading on laminin-332 as measured by protein interaction assays and electric cell-substrate impedance sensing. Nor was the soluble peptide able to restore the loss of integrin-mediated cell adhesiveness to mini-laminin-332 after deletion of the {gamma}2 chain C-terminus. These findings spoke against the hypothesis that the {gamma}2 chain C-terminus of laminin-332 is a part of the {alpha}3{beta}1 integrin interaction site. In addition, structural studies with electron microscopy showed that truncation of the {gamma}2 chain C-terminus opened up the compact supradomain structure of LG1-3 domains. Thus, by inducing or stabilizing an integrin binding-competent conformation or array of the LG1-3 domains, the {gamma}2 chain C-terminus plays an indirect but essential role in laminin-332 recognition by {alpha}3{beta}1 integrin and, hence, its cellular functions.

  7. Inelastic cross sections from gamma-ray measurements

    SciTech Connect

    Nelson, Ronald Owen

    2010-12-06

    Measurements of gamma rays following neutron induced reactions have been studied with the Germanium Array for Neutron-induced Excitations (GEANIE) at the Los Alamos Neutron Science Center (LANSCE) for many years. Gamma-ray excitation functions and coincidence studies provide insight into nuclear reaction mechanisms as well as expanding our knowledge of energy levels and gamma-rays. Samples studied with Ge detectors at LANSCE range from Be to Pu. Fe, Cr and Ti have been considered for use as reference cross sections. An overview of the measurements and efforts to create a reliable neutron-induced gamma-ray reference cross section will be presented.

  8. Gamma ray generator

    SciTech Connect

    Firestone, Richard B; Reijonen, Jani

    2014-05-27

    An embodiment of a gamma ray generator includes a neutron generator and a moderator. The moderator is coupled to the neutron generator. The moderator includes a neutron capture material. In operation, the neutron generator produces neutrons and the neutron capture material captures at least some of the neutrons to produces gamma rays. An application of the gamma ray generator is as a source of gamma rays for calibration of gamma ray detectors.

  9. Critical assessment of the claim of a significant difference between the results of measurements of the Coulomb dissociation of {sup 8}B and the {sup 7}Be(p,{gamma}){sup 8}B direct capture reaction

    SciTech Connect

    Gai, Moshe

    2006-08-15

    The Coulomb dissociation (CD) of {sup 8}B has emerged as a landmark testing ground of the very method of CD for measuring the cross section of the low-energy {sup 7}Be(p,{gamma}){sup 8}B direct capture (DC) reaction. Recent claims of evidence of slope difference between CD and DC results are critically examined. We include all relevant RIKEN2 data and all previously published DC data, and we examine the extracted so-called average scale-independent slope (b). The parametrization used by the Seattle group to extract the so-called b-slope parameter is also examined at energies above 300 keV. Considering the physical slope (S{sup '}=dS/dE) above 300 keV, we observe a (1.7{sigma}) agreement between slopes (S{sup '}) measured in CD and DC above 300 keV. The claim that S{sub 17}(0) values extracted from CD data are inconsistent and lower than DC results arises from a neglect of substantial systematic uncertainty of low-energy CD data. A consideration of the published CD S{sub 17}(0) results yields very consistent S{sub 17}(0) values that agree with most recent DC measurements. The recent correction of the b-slope parameter suggested by Esbensen, Bertsch, and Snover (EBS) was applied to the wrong b slope calculated using part of the RIKEN2 data. When the correct slope of the RIKEN2 data is used, the EBS correction in fact leads to a substantial disagreement between the slopes of the RIKEN2 data and DC data. In spite of an agreement between CD and DC data neither allow for extracting the slope above 300 keV with high accuracy. Uncertainty of the slope (S{sup '}) leads to an additional uncertainty of the extrapolated S{sub 17}(0). The slope of the astrophysical cross-section factor S{sub 17} must be measured with high precision to enable extraction of the d/s ratio and a high-precision extrapolation of S{sub 17}(0)

  10. Performance evaluation of the Sysmex(®) XP-300 in an oncology setting: evaluation and comparison of hematological parameters with the Sysmex(®) XN-3000.

    PubMed

    van Dievoet, M A; Louagie, H; Ghys, T

    2016-10-01

    The Sysmex XP-300(®) (XP-300) is a new, fully automated hematology analyzer, designed to generate complete blood counts (CBC) with 3-part differential. In our study, the XP-300 was evaluated as a point-of-care (POC) analyzer in an oncology setting. In which blood samples from patients with different pathologies and treatments, affecting hematopoiesis, were analyzed. Performance was evaluated according to the International Council for Standardization in Haematology (ICSH) guidelines and CLSI protocol H20-A2 . Beside precision, linearity and carry-over, a comparison study with the Sysmex(®) XN-3000 (XN-3000) and a manual reference leukocyte differential was performed. Flagging performance was also evaluated. XP-300 showed excellent precision and linearity results. For within- and between-run precision, the criteria, according to Ricos et al. , were met for all parameters tested, except for platelets in the low level. Less than or equal to 0.5% carry-over was seen for all parameters tested. Comparison studies showed an acceptable correlation with both XN-3000 and the manual reference leukocyte count. A suboptimal flagging performance was demonstrated. In the context of diagnosing cytopenia due to myelosuppressing agents or leukocytosis due to infection, the XP-300 showed good analytical performance. However, in the thrombocytopenic range, precision was suboptimal. In follow-up of hematological malignancies with the occurrence of abnormal cells, we advise verification with a more advanced analyzer or with microscopic review, although further studies with a higher prevalence of abnormal cells are needed. © 2016 John Wiley & Sons Ltd.

  11. Attempt to produce element 120 in the 244Pu + 58Fe reaction

    SciTech Connect

    Oganessian, Y T; Utyonkov, V K; Lobanov, Y V; Abdullin, F S; Polyakov, A N; Sagaidak, R N; Shorokovsky, I V; Tsyganov, Y S; Voinov, A A; Mezentsev, A N; Subbotin, V G; Sukhov, A M; Subotic, K; Zagrebaev, V I; Dmitriev, S N; Henderson, R A; Moody, K J; Kenneally, J M; Landrum, J H; Shaughnessy, D A; Stoyer, M A; Stoyer, N J; Wilk, P A

    2008-10-24

    An experiment aimed at the synthesis of isotopes of element 120 has been performed using the {sup 244}Pu({sup 58}Fe,xn){sup 302-x} 120 reaction. No decay chains consistent with fusion-evaporation reaction products were observed during an irradiation with a beam dose of 7.1 x 10{sup 18} 330-MeV {sup 58}Fe projectiles. The sensitivity of the experiment corresponds to a cross section of 0.4 pb for the detection of one decay.

  12. High-Temperature Ferromagnetism in Cr- and Mn-Implanted Al(sub x)Ga(sub 1-x)N

    DTIC Science & Technology

    2007-09-23

    films of AlxGa1-xN that display ferromagnetism. Although recent advances in ion-implantation doping of group-III nitrides with Cr and Mn are making...annealed from 675 to 775 oC at AFIT in an Oxy -Gon furnace using the rapid thermal annealing method in an N2 environment for 5 min to anneal out the...layer). After implantation, the samples were annealed in an Oxy -Gon annealing furnace at temperatures between 650 and 775 oC for 5 min. Before

  13. Simulation of prompt gamma-ray emission during proton radiotherapy.

    PubMed

    Verburg, Joost M; Shih, Helen A; Seco, Joao

    2012-09-07

    The measurement of prompt gamma rays emitted from proton-induced nuclear reactions has been proposed as a method to verify in vivo the range of a clinical proton radiotherapy beam. A good understanding of the prompt gamma-ray emission during proton therapy is key to develop a clinically feasible technique, as it can facilitate accurate simulations and uncertainty analysis of gamma detector designs. Also, the gamma production cross-sections may be incorporated as prior knowledge in the reconstruction of the proton range from the measurements. In this work, we performed simulations of proton-induced nuclear reactions with the main elements of human tissue, carbon-12, oxygen-16 and nitrogen-14, using the nuclear reaction models of the GEANT4 and MCNP6 Monte Carlo codes and the dedicated nuclear reaction codes TALYS and EMPIRE. For each code, we made an effort to optimize the input parameters and model selection. The results of the models were compared to available experimental data of discrete gamma line cross-sections. Overall, the dedicated nuclear reaction codes reproduced the experimental data more consistently, while the Monte Carlo codes showed larger discrepancies for a number of gamma lines. The model differences lead to a variation of the total gamma production near the end of the proton range by a factor of about 2. These results indicate a need for additional theoretical and experimental study of proton-induced gamma emission in human tissue.

  14. Lattice damage and compositional changes in Xe ion irradiated In{sub x}Ga{sub 1-x}N (x = 0.32−1.0) single crystals

    SciTech Connect

    Zhang, Limin Peng, Jinxin; Ai, Wensi; Zhang, Jiandong; Wang, Tieshan; Jiang, Weilin; Dissanayake, Amila; Zhu, Zihua; Shutthanandan, Vaithiyalingam

    2016-06-28

    Lattice disorder and compositional changes in In{sub x}Ga{sub 1-x}N (x = 0.32, 0.47, 0.7, 0.8, and 1.0) films on GaN/Al{sub 2}O{sub 3} substrates, induced by room-temperature irradiation of 5 MeV Xe ions, have been investigated using both Rutherford backscattering spectrometry under ion-channeling conditions and time-of-flight secondary ion mass spectrometry. The results show that for a fluence of 3 × 10{sup 13 }cm{sup −2}, the relative level of lattice disorder in In{sub x}Ga{sub 1-x}N increases monotonically from 59% to 90% with increasing indium concentration x from 0.32 to 0.7; a further increase in x up to 1.0 leads to little increase in the disorder level. In contrast to Ga-rich In{sub x}Ga{sub 1-x}N (x = 0.32 and 0.47), significant volume swelling of up to ∼25% accompanied with oxidation in In-rich In{sub x}Ga{sub 1-x}N (x = 0.7, 0.8, and 1.0) is observed. In addition, irradiation-induced atomic mixing occurs at the interface of In-rich In{sub x}Ga{sub 1-x}N and GaN. The results from this study indicate an extreme susceptibility of the high In-content In{sub x}Ga{sub 1-x}N to heavy-ion irradiation, and suggest that cautions must be exercised in applying ion-implantation techniques to these materials at room temperature. Further studies of the irradiation behavior at elevated temperatures are warranted.

  15. The gamma-ray telescope Gamma-1

    NASA Technical Reports Server (NTRS)

    Akimov, V. V.; Nesterov, V. E.; Kalinkin, L. F.; Balibanov, V. M.; Prilutsky, O. F.; Rodin, V. G.; Leikov, N. G.; Bielaoussov, A. S.; Dobrian, L. B.; Poluektov, V. P.

    1985-01-01

    French and Soviet specialists have designed and built the gamma-ray telescope GAMMA-1 to detect cosmic gamma rays above 50 MeV. The sensitive area of the detector is 1400 sq cm, energy resolution is 30% at 300 MeV, and angular resolution 1.2 deg at 300 MeV (and less than 20' arc when a coded aperture mask is used). Results on calibration of the qualification model and Monte-Carlo calculations are presented.

  16. Higgs mediated flavor violating top quark decays t{yields}u{sub i}H, u{sub i{gamma}}, u{sub i{gamma}{gamma}}, and the process {gamma}{gamma}{yields}tc in effective theories

    SciTech Connect

    Aranda, J. I.; Ramirez-Zavaleta, F.; Tututi, E. S.; Toscano, J. J.

    2010-04-01

    The rare top quark couplings tu{sub i{gamma}} and tu{sub i{gamma}{gamma}} (u{sub i}=u, c) induced at the one-loop level by a flavor violating tu{sub i}H vertex are studied within the context of an effective Yukawa sector that incorporates SU{sub L}(2)xU{sub Y}(1)-invariant operators of up to dimension six. Data on the recently observed D{sup 0}-D{sup 0} mixing are employed to constrain the tu{sub i}H vertex, which is then used to predict the t{yields}u{sub i}H, t{yields}u{sub i{gamma}}, and t{yields}u{sub i{gamma}{gamma}} decays, as well as the {gamma}{gamma}{yields}tu{sub i}+tu{sub i} reaction in the context of the ILC. It is found that the t{yields}cH and t{yields}c{gamma}{gamma} decays can reach sizable branching ratios as high as 5x10{sup -3} and 10{sup -4}, respectively. As for the t{yields}c{gamma} decay, it can have a branching ratio of 5x10{sup -8} that is about 6 orders of magnitude larger than the standard model prediction, which, however, is still very small to be detected. As for tc production, it is found that, due to the presence of a resonant effect in the convoluted cross section {sigma}(e{sup +}e{sup -{yields}{gamma}{gamma}{yields}}tc+tc), about (0.5-2.7)x10{sup 3} tc events may be produced at the ILC for a value of the Higgs mass near to the top mass.

  17. High Energy Neutron Induced Gamma Production

    SciTech Connect

    Brown, D A; Johnson, M; Navratil, P

    2007-09-28

    N Division has an interest in improving the physics and accuracy of the gamma data it provides to its customers. It was asked to look into major gamma producing reactions for 14 MeV incident neutrons for several low-Z materials and determine whether LLNL's processed data files faithfully represent the current state of experimental and theoretical knowledge for these reactions. To address this, we surveyed the evaluations of the requested materials, made recommendations for the next ENDL release and noted isotopes that will require further experimental study. This process uncovered several major problems in our translation and processing of the ENDF formatted evaluations, most of which have been resolved.

  18. Incorporation of Mn in AlxGa1 -xN probed by x-ray absorption and emission spectroscopy, high-resolution microscopy, x-ray diffraction, and first-principles calculations

    NASA Astrophysics Data System (ADS)

    Rovezzi, Mauro; Schlögelhofer, Wolfgang; Devillers, Thibaut; Szwacki, Nevill Gonzalez; Li, Tian; Adhikari, Rajdeep; Glatzel, Pieter; Bonanni, Alberta

    2015-09-01

    Synchrotron radiation x-ray absorption and emission spectroscopy techniques, complemented by high-resolution transmission electron microscopy methods and density functional theory calculations, are employed to investigate the effect of Mn in AlxGa1 -xN :Mn samples with an Al content up to 100%. The atomic and electronic structure of Mn is established together with its local environment and valence state. A dilute alloy without precipitation is obtained for AlxGa1 -xN :Mn with Al concentrations up to 82%, and the surfactant role of Mn in the epitaxial process is confirmed.

  19. Photonuclear reaction to test cluster structure of Lithium

    SciTech Connect

    Akkurt, Iskender

    2008-11-11

    The lithium can be pictured as an {alpha} particle with 2 extra nucleon surrounding it. A photonuclear reaction experiment has been performed to test this structure at Maxlab in Lund-Sweden. The cross-section of the {sup 6}Li({gamma},n) reaction have been measured using TOF methods and the results were compared with results of {sup 6}Li({gamma},p) and also {sup 4}He({gamma},n) reaction.

  20. On the microstructure of Al{sub x}Ga{sub 1-x}N layers grown on 6H-SiC(0001) substrates

    SciTech Connect

    Kroeger, Roland; Einfeldt, Sven; Chierchia, Rosa; Hommel, Detlef; Reitmeier, Zachary J.; Davis, Robert F.; Liu, Quincy K.K.

    2005-04-15

    The microstructural as well as the compositional evolution of Al{sub x}Ga{sub 1-x}N (x{approx}0.15) layers grown on 6H-SiC(0001) substrates by metalorganic vapor phase epitaxy were analyzed by atomic force microscopy, X-ray diffraction, and transmission electron microscopy in conjunction with energy dispersive X-ray spectroscopy. The epitaxial growth was followed from the early nucleation stage on the substrate to the development of a thick bulk-like film. Phase separation was observed during the early stage of growth; that is, islands of two different shapes formed whose Al mole fractions were about 0.035 and 0.18, respectively. The Al{sub x}Ga{sub 1-x}N coalesced at a film thickness of about 100 nm with the domains of varying Al content being fully coherent. Such domains were not only found at the film/substrate interface but also further away from the interface. They were arranged in layers that were shifted laterally against each other; that is, Al-deficient domains formed on top of Al-rich domains and vice versa. Increasing the film thickness to more than 100 nm finally led to a homogeneous Al distribution. Finite-element simulations were performed to calculate the strain distribution in these inhomogeneous systems. They allowed the experimental results to be explained by an interplay of strain minimization in the epitaxial film and growth kinetics.

  1. Influence of carbon content and nitrogen vacancies on the bonding structure and mechanical performance of graphite-like BC{sub x}N thin films

    SciTech Connect

    Caretti, Ignacio; Jimenez, Ignacio

    2012-09-15

    X-ray absorption near edge structure (XANES) was used to investigate two sets of graphite-like BC{sub x}N thin films with similar B:C:N ratios but different amounts of nitrogen vacancies, which become oxygen-filled in the surface-most region. The two sets of samples were grown on Si (100) at room temperature by ion beam assisted deposition using two different ion/atom ratios. Nitrogen vacancy defects were detected in the B1s XANES spectra due to an oxygen decoration mechanism taking place at the film surface, which is correctly described by a core-level shift model. Analysis of the O1s XANES spectra showed two different types of oxygen incorporation in the samples under study. The tribomechanical properties of the BC{sub x}N samples were tested by the pin-on-disk technique, revealing the substantial role played by both the carbon intake in the hexagonal BCN planes and the concentration of nitrogen vacancies generated during the growth.

  2. SQUID measurements of MnxSc(1-x)N and Fe0.1Sc0.9N Films Grown by Molecular Beam Epitaxy

    NASA Astrophysics Data System (ADS)

    Chia, Han-Jong; Constantin, Costel; Wang, Kangkang; Chinchore, Abhijit; Smith, Arthur; Markert, John

    2009-03-01

    We report SQUID magnetic measurements on N-rich and N-poor MnxSc(1-x)N and Fe0.1Sc0.9N films grown on ScN(001)/MgO(001) substrates by radio frequency plasma assisted molecular beam epitaxy. Ferromagnetism is present in both the Mn doped (x ranging from 3 to 15%) and the Fe doped ScN samples. Measurements on N-poor Mn0.03Sc0.97N and Mn0.15Sc0.85N (x=15%) show Curie temperatures of 383 K and 361 K, respectively. The Fe0.1Sc0.9N film shows a Curie temperature above 350 K as well. Further studies will be required to determine the origin of the ferromagnetism and the Curie temperature of the remaining MnxSc(1-x)N films. This work is supported by: Seton Hall: University Research Council; Ohio University: DOE-BES Grant No. DE-FG02-06ER46317 and NSF Grant No. 0730257; and UT Austin: NSF Grant Nos. DMR-0605828 and DGE-0549417, Welch Foundation Grant No. F-1191.

  3. Spin-glass-like behavior and negative thermal expansion in antiperovskite Mn{sub 3}Ni{sub 1−x}Cu{sub x}N compounds

    SciTech Connect

    Ding, Lei; Wang, Cong Sun, Ying; Colin, Claire V.; Chu, Lihua

    2015-06-07

    The Cu-doping effect on the lattice and magnetic properties in Mn{sub 3}Ni{sub 1−x}Cu{sub x}N (x = 0, 0.3, 0.5, 0.7, 1.0) was extensively investigated. We observed that the Cu-doping at the Ni site complicated the magnetic ground states, which induced the competition of antiferromagnetic and ferromagnetic interactions. Spin-glass-like behavior, arising from possible site-randomness and competing interactions of magnetism, was observed in compounds with x = 0.3, 0.5, and 0.7, and typically discussed by means of the measurement of ac magnetic susceptibility for x = 0.7. The negative thermal expansion (NTE) behavior, due to the magnetic ordering transition, was observed in Mn{sub 3}Ni{sub 1−x}Cu{sub x}N compounds using variable temperature x-ray diffraction. It reveals that the introduction of Cu effectively broadens the temperature range displaying negative thermal expansion. The relationship between the local lattice distortion and the competing magnetic ground states might play an important role in broadening the NTE temperature range in this antiperovskite compound.

  4. Spectroscopic analysis of the NIR emission in Tm implanted Al{sub x}Ga{sub 1-x}N layers

    SciTech Connect

    Rodrigues, J. Esteves, T. C.; Santos, N. F.; Ben Sedrine, N.; Rino, L.; Neves, A. J.; Monteiro, T.; Fialho, M.; Lorenz, K.; Alves, E.

    2016-08-28

    Al{sub x}Ga{sub 1-x}N samples, with different AlN molar fractions, x = 0, 0.15, 0.77, and 1, grown by halide vapor phase epitaxy were implanted with Tm ions. Photoluminescence (PL) measurements revealed that after thermal annealing all the samples exhibit intraionic Tm{sup 3+} luminescence. In samples with x > 0, the low temperature emission is dominated by the lines that appear in the near infrared (NIR) spectral region, corresponding to the overlapped {sup 1}G{sub 4} → {sup 3}H{sub 5} and {sup 3}H{sub 4} → {sup 3}H{sub 6} multiplet transitions. A detailed spectroscopic analysis of NIR emission of the thulium implanted and annealed Al{sub x}Ga{sub 1-x}N layers is presented by using temperature dependent steady-state PL, room temperature PL excitation, and time resolved PL. The results indicate that the excitonic features sensitive to the alloy disorder are involved in the excitation population processes of the Tm{sup 3+} luminescence and the highest thermal stability for the NIR emission occurs for the AlN:Tm sample.

  5. X-ray magnetic circular dichroism for CoxFe4-xN (x = 0, 3, 4) films grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Ito, Keita; Sanai, Tatsunori; Yasutomi, Yoko; Zhu, Siyuan; Toko, Kaoru; Takeda, Yukiharu; Saitoh, Yuji; Kimura, Akio; Suemasu, Takashi

    2014-05-01

    We evaluated orbital (morb) and spin magnetic moments (mspin) of CoxFe4-xN (x = 0, 3, 4) epitaxial thin films grown by molecular beam epitaxy using x-ray magnetic circular dichroism, and discussed the dependence of these values on x. Site-averaged mspin value of Fe atoms was deduced to be 1.91 μB per atom, and that of Co atoms to be 1.47 μB per atom in Co3FeN at 300 K. These values are close to 1.87 μB per Fe atom in Fe4N and 1.43 μB per Co atom in Co4N, respectively. This result implies that the Fe and Co atoms in the Co3FeN films were located both at corner and face-centered sites in the anti-perovskite lattice. Spin magnetic moments per unit cell were decreased linearly with increasing x in CoxFe4-xN. This tendency is in good agreement with theory predicted by the first-principle calculation.

  6. Microstructure and dielectric properties of piezoelectric magnetron sputtered w-Sc{sub x}Al{sub 1-x}N thin films

    SciTech Connect

    Zukauskaite, Agne; Wingqvist, Gunilla; Palisaitis, Justinas; Jensen, Jens; Persson, Per O. A.; Birch, Jens; Hultman, Lars; Matloub, Ramin; Muralt, Paul; Kim, Yunseok

    2012-05-01

    Piezoelectric wurtzite Sc{sub x}Al{sub 1-x}N (x = 0, 0.1, 0.2, 0.3) thin films were epitaxially grown by reactive magnetron co-sputtering from elemental Sc and Al targets. Al{sub 2}O{sub 3}(0001) wafers with TiN(111) seed and electrode layers were used as substrates. X-ray diffraction shows that an increase in the Sc content results in the degradation of the crystalline quality. Samples grown at 400 deg. C possess true dielectric behavior with quite low dielectric losses and the leakage current is negligible. For ScAlN samples grown at 800 deg. C, the crystal structure is poor and leakage current is high. Transmission electron microscopy with energy dispersive x-ray spectroscopy mapping shows a mass separation into ScN-rich and AlN-rich domains for x {>=} 0.2 when substrate temperature is increased from 400 to 800 deg. C. The piezoelectric response of epitaxial Sc{sub x}Al{sub 1-x}N films measured by piezoresponse force microscopy and double beam interferometry shows up to 180% increase by the addition of Sc up to x = 0.2 independent of substrate temperature, in good agreement with previous theoretical predictions based on density-functional theory.

  7. An assessment of the evaporation and condensation phenomena of lithium during the operation of a Li(d,xn) fusion relevant neutron source.

    PubMed

    Knaster, J; Kanemura, T; Kondo, K

    2016-12-01

    The flowing lithium target of a Li(d,xn) fusion relevant neutron source must evacuate the deuteron beam power and generate in a stable manner a flux of neutrons with a broad peak at 14 MeV capable to cause similar phenomena as would undergo the structural materials of plasma facing components of a DEMO like reactors. Whereas the physics of the beam-target interaction are understood and the stability of the lithium screen flowing at the nominal conditions of IFMIF (25 mm thick screen with +/-1 mm surface amplitudes flowing at 15 m/s and 523 K) has been demonstrated, a conclusive assessment of the evaporation and condensation of lithium during operation was missing. First attempts to determine evaporation rates started by Hertz in 1882 and have since been subject of continuous efforts driven by its practical importance; however intense surface evaporation is essentially a non-equilibrium process with its inherent theoretical difficulties. Hertz-Knudsen-Langmuir (HKL) equation with Schrage's 'accommodation factor' η = 1.66 provide excellent agreement with experiments for weak evaporation under certain conditions, which are present during a Li(d,xn) facility operation. An assessment of the impact under the known operational conditions for IFMIF (574 K and 10(-3)Pa on the free surface), with the sticking probability of 1 inherent to a hot lithium gas contained in room temperature steel walls, is carried out. An explanation of the main physical concepts to adequately place needed assumptions is included.

  8. Detection of malignant cells in serous body fluids by counting high-fluorescent cells on the Sysmex XN-2000 hematology analyzer.

    PubMed

    Labaere, D; Boeckx, N; Geerts, I; Moens, M; Van den Driessche, M

    2015-10-01

    The body fluid mode of the Sysmex XN-2000 hematology analyzer differentiates cells into mononuclear and polymorphonuclear white blood cells (WBC) and high-fluorescent cells (HFC). The aim of this study was to evaluate the performance of the HFC count for detecting malignant cells in serous body fluids. Two-hundred and thirty serous fluids were analyzed on the Sysmex XN body fluid mode. HFC were measured as relative count (HFC/100 WBC) and absolute count (HFC/μL). All samples were microscopically screened on cytospin slides for the presence of malignant cells. Malignant cells were found by microscopic examination in 49 of 230 samples (21.3%). Malignant samples contained significantly higher percentages (10.2 vs. 2.6/100 WBC) and absolute numbers (65 vs. 10/μL) of HFC than nonmalignant samples (P < 0.001). Areas under the ROC curve for relative and absolute HFC count were 0.69 and 0.77, respectively. A cutoff level of ≥17 HFC/μL showed the best performance to predict malignancy, with 88% sensitivity and 61% specificity. As serous body fluids will be more analyzed on automated analyzers in the future, HFC count can be a useful tool to select samples for microscopic review. Microscopic evaluation should be performed if HFC values are above a certain threshold (e.g. ≥17 HFC/μL) or in case of clinical suspicion of malignancy. © 2015 John Wiley & Sons Ltd.

  9. Structures and stabilities of group 13 adducts [(NHC)(EX3)] and [(NHC)2(E2X(n))] (E=B to In; X=H, Cl; n=4, 2, 0; NHC=N-heterocyclic carbene) and the search for hydrogen storage systems: a theoretical study.

    PubMed

    Holzmann, Nicole; Stasch, Andreas; Jones, Cameron; Frenking, Gernot

    2011-11-25

    Quantum chemical calculations using density functional theory at the BP86/TZVPP level and ab initio calculations at the SCS-MP2/TZVPP level have been carried out for the group 13 complexes [(NHC)(EX(3))] and [(NHC)(2)(E(2)X(n))] (E=B to In; X=H, Cl; n=4, 2, 0; NHC=N-heterocyclic carbene). The monodentate Lewis acids EX(3) and the bidentate Lewis acids E(2) X(n) bind N-heterocyclic carbenes rather strongly in donor-acceptor complexes [(NHC)(EX(3))] and [(NHC)(2)(E(2)X(n))]. The equilibrium structures of the bidentate complexes depend on the electronic reference state of E(2)X(n), which may vary for different atoms E and X. All complexes [(NHC)(2)(E(2)X(4))] possess C(s) symmetry in which the NHC ligands bind in a trans conformation to the group 13 atoms E. The complexes [(NHC)(2)(E(2)H(2))] with E=B, Al, Ga have also C(s) symmetry with a trans arrangement of the NHC ligands and a planar CE(H)E(H)C moiety that has a E=E π bond. In contrast, the indium complex [(NHC)(2)(In(2) H(2))] has C(i) symmetry with pyramidal-coordinated In atoms in which the hydrogen atoms are twisted above and below the CInInC plane. The latter C(i) form is calculated for all chloride systems [(NHC)(2)(E(2)Cl(2))], but the boron complex [(NHC)(2)(B(2)Cl(2))] deviates only slightly from C(s) symmetry. The B(2) fragment in the linear coordinated complex [(NHC)(2)(B(2))] has a highly excited (3)(1)Σ(g)(-) reference state, which gives an effective B≡B triple bond with a very short interatomic distance. The heavier homologues [(NHC)(2)(E(2))] (E=Al to In) exhibit a anti-periplanar arrangement of the NHC ligands in which the E(2) fragments have a (1)(1) Δ(g) reference state and an E=E double bond. The calculated energies suggest that the dihydrogen release from the complexes [(NHC)(EH(3))] and [(NHC)(2)(E(2)H(n))] becomes energetically more favourable when atom E becomes heavier. The indium complexes should therefore be the best candidates of the investigated series for hydrogen-storage systems

  10. gamma-Hexachlorocyclohexane (gamma-HCH)

    Integrated Risk Information System (IRIS)

    gamma - Hexachlorocyclohexane ( gamma - HCH ) ; CASRN 58 - 89 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Asse

  11. A tandem-based compact dual-energy gamma generator

    SciTech Connect

    Persaud, A.; Kwan, J.W.; Leitner, M.; Leung, K.N.; Ludewigt, B.; Tanaka, N.; Waldron, W.; Wilde, S.; Antolak, A.J.; Morse, D.H.; Raber, T.

    2009-11-11

    A dual-energy tandem-type gamma generator has been developed at E.O. Lawrence Berkeley National Laboratory and Sandia National Laboratories. The tandem accelerator geometry allows higher energy nuclear reactions to be reached, thereby allowing more flexible generation of MeV-energy gammas for active interrogation applications.

  12. Gamma radiolysis of chlorinated hydrocarbons

    SciTech Connect

    Arbon, R.E.; Mincher, B.J.; Meikrantz, D.H.

    1992-08-01

    This program is the Idaho National Engineering Laboratory (INEL) component of a joint collarborative effort with Lawrence Livermore National Laboratory (LLNL). The purpose of this effort is to demonstrate a viable process for breaking down hazardous halogenated organic wastes to simpler, non-hazardous waste using high energy ionizing radiation. The INEL effort focuses on the use of spent reactor fuel gamma radiation sources to decompose complex wastes such as PCBs. At LLNL, halogenated solvents such as carbon tetrachloride and trichloroethylene are being studied using accelerator radiation sources. The INEL irradiation experiments concentrated on a single PCB congener so that a limited set of decomposition reactions could be studied. The congener 2,2{prime}, 3,3{prime},4,5{prime},6,6{prime} - octachlorobiphenyl was examined following exposure to various gamma doses at the Advanced Test Reactor (AIR) spent fuel pool. The decomposition rates and products in several solvents are discussed. 3 refs.

  13. Gamma radiolysis of chlorinated hydrocarbons

    SciTech Connect

    Arbon, R.E.; Mincher, B.J.; Meikrantz, D.H.

    1992-01-01

    This program is the Idaho National Engineering Laboratory (INEL) component of a joint collarborative effort with Lawrence Livermore National Laboratory (LLNL). The purpose of this effort is to demonstrate a viable process for breaking down hazardous halogenated organic wastes to simpler, non-hazardous waste using high energy ionizing radiation. The INEL effort focuses on the use of spent reactor fuel gamma radiation sources to decompose complex wastes such as PCBs. At LLNL, halogenated solvents such as carbon tetrachloride and trichloroethylene are being studied using accelerator radiation sources. The INEL irradiation experiments concentrated on a single PCB congener so that a limited set of decomposition reactions could be studied. The congener 2,2{prime}, 3,3{prime},4,5{prime},6,6{prime} - octachlorobiphenyl was examined following exposure to various gamma doses at the Advanced Test Reactor (AIR) spent fuel pool. The decomposition rates and products in several solvents are discussed. 3 refs.

  14. Solar flare gamma-ray line shapes

    NASA Technical Reports Server (NTRS)

    Werntz, C.; Kim, Y. E.; Lang, Frederick L.

    1990-01-01

    A computer code has been developed which is used to calculate ab initio the laboratory shapes and energy shifts of gamma-ray lines from (C-12)(p, gamma/4.438/)p-prime(C-12) and (O-16)(p, gamma/6.129/)p-prime(O-16) reactions and to calculate the expected shapes of these lines from solar flares. The sensitivity of observable solar flare gamma-ray line shapes to the directionality of the incident particles is investigated for several projectile angular distributions. Shapes of the carbon and oxygen lines are calculated assuming realistic proton energy spectra for particles in circular orbits at the mirror points of magnetic loops, for particle beams directed downward into the photosphere, and for isotropic particle distributions. Line shapes for flare sites near the center of the sun and on the limb are shown for both thin-target and thick-target interaction models.

  15. HotSpotter? Neutron/Gamma Detector

    SciTech Connect

    Bell, Z.W.

    2003-04-01

    The HotSpotter{trademark} Neutron/Gamma Detector combines in a single detecting module high sensitivity to gamma rays up to 3 MeV and sensitivity to neutrons. Using a 15 mm cubic CdWO{sub 4} (cadmium tungstate) crystal mounted on a 25 mm photomultiplier, the instrument realizes a factor of 5 increased photopeak efficiency over NaI(Tl) at 1 MeV, and a factor of 2 improvement over CsI(Tl). The addition of a 0.5 mm layer of {sup 10}B- impregnated epoxy covering the crystal provides neutron sensitivity without sacrificing gamma ray spectroscopic characteristics. Neutrons are detected by the presence of the 478 keV gamma from the {sup 10}B(n,{alpha}){sup 7}Li* reaction. In this paper, we describe the electronics and software of the instrument, and some of its characteristics.

  16. Solar flare gamma-ray line shapes

    NASA Technical Reports Server (NTRS)

    Werntz, C.; Kim, Y. E.; Lang, Frederick L.

    1990-01-01

    A computer code has been developed which is used to calculate ab initio the laboratory shapes and energy shifts of gamma-ray lines from (C-12)(p, gamma/4.438/)p-prime(C-12) and (O-16)(p, gamma/6.129/)p-prime(O-16) reactions and to calculate the expected shapes of these lines from solar flares. The sensitivity of observable solar flare gamma-ray line shapes to the directionality of the incident particles is investigated for several projectile angular distributions. Shapes of the carbon and oxygen lines are calculated assuming realistic proton energy spectra for particles in circular orbits at the mirror points of magnetic loops, for particle beams directed downward into the photosphere, and for isotropic particle distributions. Line shapes for flare sites near the center of the sun and on the limb are shown for both thin-target and thick-target interaction models.

  17. Gamma ray detector shield

    DOEpatents

    Ohlinger, R.D.; Humphrey, H.W.

    1985-08-26

    A gamma ray detector shield comprised of a rigid, lead, cylindrical-shaped vessel having upper and lower portions with an pneumatically driven, sliding top assembly. Disposed inside the lead shield is a gamma ray scintillation crystal detector. Access to the gamma detector is through the sliding top assembly.

  18. (n,{gamma}) Experiments on tin isotopes

    SciTech Connect

    Baramsai, B.; Mitchell, G. E.; Walker, C. L.; Rusev, G.; Bredeweg, T. A.; Couture, A.; Haight, R. C.; Jandel, M.; Mosby, S.; O'Donnell, J. M.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Becvar, F.; Krticka, M.; Kroll, J.; Agvaanluvsan, U.; Dashdorj, D.; Erdenehuluun, B.; Tsend-Ayush, T.

    2013-04-19

    Neutron capture experiments on highly enriched {sup 117,119}Sn isotopes were performed with the DANCE detector array located at the Los Alamos Neutron Science Center. The DANCE detector provides detailed information about the multi-step {gamma}-ray cascade following neutron capture. Analysis of the experimental data provides important information to improve understanding of the neutron capture reaction, including a test of the statistical model, the assignment of spins and parities of neutron resonances, and information concerning the Photon Strength Function (PSF) and Level Density (LD) below the neutron separation energy. Preliminary results for the (n,{gamma}) reaction on {sup 117,119}Sn are presented. Resonance spins of the odd-A tin isotopes were almost completely unknown. Resonance spins and parities have been assigned via analysis of the multi-step {gamma}-ray spectra and directional correlations.

  19. Rehabilitation of gamma

    NASA Astrophysics Data System (ADS)

    Poynton, Charles A.

    1998-07-01

    Gamma characterizes the reproduction of tone scale in an imaging system. Gamma summarizes, in a single numerical parameter, the nonlinear relationship between code value--in an 8-bit system, from 0 through 255--and physical intensity. Nearly all image coding systems are nonlinear, and so involve values of gamma different from unity. Owing to poor understanding of tone scale reproduction, and to misconceptions about nonlinear coding, gamma has acquired a terrible reputation in computer graphics and image processing. In addition, the world-wide web suffers from poor reproduction of grayscale and color images, due to poor handling of nonlinear image coding. This paper aims to make gamma respectable again.

  20. Gamma-ray waveguides

    SciTech Connect

    Tournear, D. M.; Hoffbauer, M. A.; Akhadov, E. A.; Chen, A. T.; Pendleton, S. J.; Williamson, T. L.; Cha, K. C.; Epstein, R. I.

    2008-04-14

    We have developed an approach for gamma-ray optics using layered structures acting as planar waveguides. Experiments demonstrating channeling of 122 keV gamma rays in two prototype waveguides validate the feasibility of this technology. Gamma-ray waveguides allow one to control the direction of radiation up to a few MeV. The waveguides are conceptually similar to polycapillary optics, but can function at higher gamma-ray energies. Optics comprised of these waveguides will be able to collect radiation from small solid angles or concentrate radiation into small area detectors. Gamma-ray waveguides may find applications in medical imaging and treatment, astrophysics, and homeland security.

  1. Effect of nitrogen flow rate on structural, morphological and optical properties of In-rich InxAl1-xN thin films grown by plasma-assisted dual source reactive evaporation

    NASA Astrophysics Data System (ADS)

    Alizadeh, M.; Ganesh, V.; Goh, B. T.; Dee, C. F.; Mohmad, A. R.; Rahman, S. A.

    2016-08-01

    In-rich InxAl1-xN thin films were deposited on quartz substrate at various nitrogen flow rates by plasma-assisted dual source reactive evaporation technique. The elemental composition, surface morphology, structural and optical properties of the films were investigated by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), Raman spectroscopy, X-ray diffraction (XRD), UV-vis spectrophotometer and photoluminescence (PL) measurements. XPS results revealed that the indium composition (x) of the InxAl1-xN films increases from 0.90 to 0.97 as the nitrogen flow rate is increased from 40 to 100 sccm, respectively. FESEM images of the surface and cross-sectional microstructure of the InxAl1-xN films showed that by increasing the N2 flow rate, the grown particles are highly agglomerated. Raman and XRD results indicated that by increasing nitrogen flow rate the In-rich InxAl1-xN films tend to turn into amorphous state. It was found that band gap energy of the films are in the range of 0.90-1.17 eV which is desirable for the application of full spectra solar cells.

  2. Effect of substitution of nitrogen ions to red-emitting Sr 3B 2O 6-3/2 xN x:Eu 2+ oxy-nitride phosphor for the application to white LED

    NASA Astrophysics Data System (ADS)

    Hoon Jung, Sang; Seok Kang, Dong; Young Jeon, Duk

    2011-07-01

    The luminescence properties of orange-red-emitting Eu 2+ activated Sr 3B 2O 6-3/2 xN x were optimized for application to blue/near UV light-emitting diodes (LEDs). Sr 3B 2O 6-3/2 xN x:Eu 2+ phosphor showed broad orange-red emission peaking at 600-650 nm under blue and n-UV excitations of 450 and 360 nm, respectively; the emission peak of phosphor was affected by nitrogen ion substitution. Boron nitride raw materials affect luminescence properties of phosphor; a small amount of BN reacts as a flux for synthesis of Sr 3B 2O 6 and a large amount of BN helps Sr 3B 2O 6-3/2 xN x:Eu 2+ phosphor to have longer-wavelength emission peak. A 447 nm-emitting blue LED-pumped white LED with a mixture of Sr 3B 2O 6-3/2 xN x:Eu 2+ ( x=1) and Ba 2SiO 4:Eu 2+ green-emitting phosphor was fabricated; it is observed that it showed color coordinates of (0.3648, 0.3605) and CRI value of 96.

  3. Spectroscopic characterization of the plasma generated during the deposition of AlxGa1-xN films by pulsed laser co-ablation of Al and GaAs targets in electron cyclotron resonance nitrogen plasma

    NASA Astrophysics Data System (ADS)

    Liang, Peipei; Cai, Hua; Li, Yanli; Yang, Xu; You, Qinghu; Sun, Jian; Xu, Ning; Wu, Jiada

    2015-06-01

    A nitrogen-aluminum-gallium-arsenic plasma is formed by pulsed laser co-ablation of an Al target and a GaAs target in electron cyclotron resonance discharge-generated nitrogen plasma for AlxGa1-xN film deposition. The formed plasma was characterized by time-integrated and time-resolved optical emission spectroscopy measurements and the process of AlxGa1-xN deposition was discussed. The plasma contains excited species originally present in the working N2 gas and energetic species ablated from the targets, and its emission is abundant in the emission bands of diatomic nitrogen molecules and molecular ions and the emission lines of monoatomic aluminum, gallium, and arsenic atoms and atomic ions. The temporal and spatial features of the plasma emission reveal that the nitrogen species in the electron cyclotron resonance nitrogen plasma experience additional excitations due to the expanding ablation plumes, and the ablated species are excited frequently when traveling with the expanding plumes in the nitrogen plasma, making the formed plasma very reactive, which is very important in the process of AlxGa1-xN film deposition. The deposited film was evaluated for composition analysis by energy-dispersive x-ray spectroscopy and structure characterization by x-ray diffraction. The AlxGa1-xN film is slightly nitrogen rich with an aluminum content x of about 0.6 and featured with hexagonal wurtzite crystal structure with preferred c-axis orientation.

  4. Metabolism of fatty acid in yeast: addition of reducing agents to the reaction medium influences beta-oxidation activities, gamma-decalactone production, and cell ultrastructure in Sporidiobolus ruinenii cultivated on ricinoleic acid methyl ester.

    PubMed

    Feron, Gilles; Mauvais, Geneviève; Lherminier, Jeanine; Michel, Joël; Wang, Xiao-Dong; Viel, Christophe; Cachon, Rémy

    2007-06-01

    The sensitivity of Sporidiobolus ruinenii yeast to the use of reducing agents, reflected in changes in the oxidoreduction potential at pH 7 (Eh7) environment, ricinoleic acid methyl ester catabolism, gamma-decalactone synthesis, cofactor level, beta-oxidation activity, and ultrastructure of the cell, was studied. Three environmental conditions (corresponding to oxidative, neutral, and reducing conditions) were fixed with the use of air or air and reducing agents (hydrogen and dithiothreitol). Lowering Eh7 to neutral conditions (Eh7 = +30 mV and +2.5 mV) favoured the production of lactone more than the more oxidative condition (Eh7 = +350 mV). In contrast, when a reducing condition was used (Eh7 = -130 mV), the production of gamma-decalactone was very low. These results were linked to changes in the cofactor ratio during lactone production, to the beta-oxidation activity involved in decanolide synthesis, and to ultrastructural modification of the cell.

  5. A tandem-based compact dual-energy gamma generator.

    PubMed

    Persaud, A; Kwan, J W; Leitner, M; Leung, K-N; Ludewigt, B; Tanaka, N; Waldron, W; Wilde, S; Antolak, A J; Morse, D H; Raber, T

    2010-02-01

    A dual-energy tandem-type gamma generator has been developed at E. O. Lawrence Berkeley National Laboratory and Sandia National Laboratories. The tandem accelerator geometry allows higher energy nuclear reactions to be reached, thereby allowing more flexible generation of MeV-energy gammas for active interrogation applications. Both positively charged ions and atoms of hydrogen are created from negative ions via a gas stripper. In this paper, we show first results of the working tandem-based gamma generator and that a gas stripper can be utilized in a compact source design. Preliminary results of monoenergetic gamma production are shown.

  6. {lambda}(1520) {yields} {lambda}{gamma} Radiative-Decay Width

    SciTech Connect

    Vavilov, D.V.; Antipov, Yu.M.; Artamonov, A.V.; Batarin, V.A.; Victorov, V.A.; Golovkin, S.V.; Gorin, Yu.P.; Eroshin, O.V.; Kozhevnikov, A.P.; Konstantinov, A.S.; Kubarovsky, V.P.; Kurshetsov, V.F.; Landsberg, L.G.; Leontiev, V.M.; Molchanov, V.V.; Mukhin, V.A.; Patalakha, D.I.; Petrenko, S.V.; Petrukhin, A.I.; Kolganov, V.Z.

    2005-03-01

    The radiative decay {lambda}(1520) {yields} {lambda}{gamma} was recorded in the exclusive reaction p + N {yields} {lambda}(1520)K{sup +} + N at the SPHINX facility. The branching ratio for this decay and the corresponding partial width were found to be, respectively, Br[{lambda}(1520) {yields} {lambda}{gamma}] = (1.02 {+-} 0.21) x 10{sup -2} and {gamma}[{lambda}(1520) {yields} {lambda}{gamma}] = 159 {+-} 35 keV (the quoted errors are purely statistical, the systematic errors being within 15%)

  7. First-principles study of the structural and elastic properties of Cr{sub 2}AlX (X=N, C) compounds

    SciTech Connect

    Cui Shouxin; Wei Dongqing; Hu Haiquan; Feng Wenxia; Gong Zizheng

    2012-07-15

    The structural, electronic and elastic properties of Cr{sub 2}AlX, with X=N, C, have been investigated at the density functional theory level by applying a plane-wave pseudopotential approach. The band structure and density of states reveal the metallic features of Cr{sub 2}AlX. The total and projected density of states indicate that the bonding is achieved through a hybridization of Cr 3d states with Al and X-atom p states. The Cr 3d-X2p bonds are lower in energy and are stiffer than Cr 3d-Al 3p bonds. The charge density distributions indicate that there exist soft Cr-Al and relatively strong Cr-X covalent bonds, which might be responsible for their hardness. The elastic constants were obtained in the pressure range 0-100 GPa, and satisfy the stability conditions for hexagonal crystal, which indicates that these two compounds are stable in the pressure regime studied. By analyzing bulk modulus to shear modulus ratio and Cauchy pressure, Cr{sub 2}AlC is predicted to be brittleness and Cr{sub 2}AlN is ductile. The Debye temperature was obtained from the average sound velocity. - Graphical abstract: The heterogeneity of chemical bonds in Cr{sub 2}AlX (X=N, C) is observed: soft Cr-Al and relatively strong Cr-X covalent bonds might be contributed to their hardness. Highlights: Black-Right-Pointing-Pointer Cr 3d-X2p (X=N, C) bonds are lower in energy and stiffer than Cr 3d-Al 3p bonds for Cr{sub 2}AlX. Black-Right-Pointing-Pointer The hardness of Cr{sub 2}AlX might be ascribed to soft Cr-Al and relatively strong Cr-X covalent bonds. Black-Right-Pointing-Pointer The predicted brittleness of Cr{sub 2}AlC and ductility of Cr{sub 2}AlN originated from their novel structure.

  8. Intentional anisotropic strain relaxation in (112{sup ¯}2) oriented Al{sub 1−x}In{sub x}N one-dimensionally lattice matched to GaN

    SciTech Connect

    Buß, E. R. Rossow, U.; Bremers, H.; Hangleiter, A.; Meisch, T.; Caliebe, M.; Scholz, F.

    2014-09-22

    We report on (112{sup ¯}2) oriented Al{sub 1−x}In{sub x}N grown by low pressure metal organic vapor phase epitaxy on (112{sup ¯}2) GaN templates on patterned r-plane sapphire. The indium incorporation efficiency as well as the growth rate of (112{sup ¯}2) oriented layers are similar to c-plane oriented Al{sub 1−x}In{sub x}N layers. Deposition of thick Al{sub 1−x}In{sub x}N layers does not lead to additional roughening like in case of c-plane oriented Al{sub 1−x}In{sub x}N. Independent of the thickness, the degree of relaxation of layers lattice matched in m-direction is in the range of 33%–45% in [112{sup ¯}3{sup ¯}]-direction. Associated with the relaxation in [112{sup ¯}3{sup ¯}]-direction, there is a tilt of the Al{sub 1−x}In{sub x}N layers around the [11{sup ¯}00] axis due to slip of threading dislocations on the basal (0001)-plane. Relaxation in m-direction is not observable for layers lattice matched in [112{sup ¯}3{sup ¯}] direction. The possibility to adjust the lattice parameter of AlInN in [112{sup ¯}3{sup ¯}] direction without changing the lattice parameter in m-direction by anisotropic strain relaxation opens up opportunities for subsequent growth of optically active structures. One possibility is to form relaxed buffer layers for GaInN quantum well structures.

  9. Resonance production in. gamma gamma. collisions

    SciTech Connect

    Renard, F.M.

    1983-04-01

    The processes ..gamma gamma.. ..-->.. hadrons can be depicted as follows. One photon creates a q anti q pair which starts to evolve; the other photon can either (A) make its own q anti q pair and the (q anti q q anti q) system continue to evolve or (B) interact with the quarks of the first pair and lead to a modified (q anti q) system in interaction with C = +1 quantum numbers. A review of the recent theoretical activity concerning resonance production and related problems is given under the following headings: hadronic C = +1 spectroscopy (q anti q, qq anti q anti q, q anti q g, gg, ggg bound states and mixing effects); exclusive ..gamma gamma.. processes (generalities, unitarized Born method, VDM and QCD); total cross section (soft and hard contributions); q/sup 2/ dependence of soft processes (soft/hard separation, 1/sup +- +/ resonances); and polarization effects. (WHK)

  10. Cluster-transfer reactions with radioactive beams: A spectroscopic tool for neutron-rich nuclei

    DOE PAGES

    Bottoni, S.; Leoni, S.; Fornal, B.; ...

    2015-08-27

    An exploratory experiment performed at REX-ISOLDE to investigate cluster-transfer reactions with radioactive beams in inverse kinematics is presented. The aim of the experiment was to test the potential of cluster-transfer reactions at the Coulomb barrier as a mechanism to explore the structure of exotic neutron-rich nuclei. The reactions 7Li(98Rb,αxn) and 7Li(98Rb,txn) were studied through particle-γ coincidence measurements, and the results are presented in terms of the observed excitation energies and spins. Moreover, the reaction mechanism is qualitatively discussed as a transfer of a clusterlike particle within a distorted-wave Born approximation framework. The results indicate that cluster-transfer reactions can be describedmore » well as a direct process and that they can be an efficient method to investigate the structure of neutron-rich nuclei at medium-high excitation energies and spins.« less

  11. Activation cross-sections of longer lived radioisotopes of proton induced nuclear reactions on terbium up to 65MeV.

    PubMed

    Tárkányi, F; Hermanne, A; Ditrói, F; Takács, S; Ignatyuk, A V

    2017-09-01

    Experimental cross sections are presented for the (159)Tb(p,xn)(153,155,157,159)Dy, (152,153,155,156m2,m1,g,158)Tb and (153,151)Gd nuclear reactions up to 65MeV. The experimental results are compared with the recently reported experimental data and with the results of the nuclear reaction codes ALICE-IPPE, EMPIRE and TALYS as reported in the TENDL-2015 on-line library. Integral thick-target yields are also derived for the reaction products used in practical applications and production routes are discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Synthesis of rutherfordium isotopes in the 238U(26Mg, xn)264-xRf reaction and study of their decay properties

    SciTech Connect

    Gates, Jacklyn M; Gates, J.M.; Garcia, M.A.; Gregorich, K.E.; Dullmann, Ch.E.; Dragojevic, I.; Dvorak, J.; Eichler, R.; Folden III, C.M.; Loveland, W.; Nelson, S.L.; Pang, G.K.; Stavsetra, L.; Sudowe, R.; Turler, A.; Nitsche, H.

    2008-01-15

    Isotopes of rutherfordium (258-261Rf) were produced in irradiations of 238U targets with 26Mg beams. Excitation functions were measured for the 4n, 5n and 6n exit channels. Production of 261Rf in the 3n exit channel with a cross section of 28+92-26 pb was observed. Alpha decay of 258Rf was observed for the first time with an alpha-particle energy of 9.05+-0.03 MeV and an alpha/total decay branching ratio of 0.31+-0.11. In 259Rf, the electron capture/total decay branching ratio was measured to be 0.15+-0.04. The measured half-lives for 258Rf, 259Rf and 260Rf were 14.7+1.2-1.0 ms, 2.5+0.4-0.3 s and 22.2+3.0-2.4 ms, respectively, in agreement with literature data. The systematics of the alpha decay Q values and of the partial spontaneous fission half-lives were evaluated for even-even nuclides in the region of the N = 152, Z = 100 deformed shell. The influence of the N = 152 shell on the alpha decay Q values for rutherfordium was observed to be similar to that of the lighter elements (96<_ Z<_ 102). However, the N = 152 shell does not stabilize the rutherfordium isotopes against spontaneous fission, as it does in the lighter elements (96<_ Z<_102).

  13. Nature of the Pygmy Resonance in Continuous Gamma-Spectra

    SciTech Connect

    Rekstad, J; Siem, S; Bernstein, L; Schiller, A; Garrett, P; Nelson, R; Guttormsen, M; Algin, E; Voinov, A

    2003-12-01

    Two-step-cascade spectra of the {sup 171}Yb(n, {gamma}{gamma}){sup 172}Yb reaction have been measured using thermal neutrons. They are compared to calculations based on experimental values of the level density and radiative strength function obtained from the {sup 173}Yb({sup 3}He,{alpha}{gamma}){sup 172}Yb reaction. The multipolarity of a 6.5(15) {mu}{sub N}{sup 2} resonance at 3.3(1) MeV in the strength function is determined to be M1 by this comparison.

  14. Texture and microstructure evolution in single-phase Ti{sub x}Ta{sub 1-x}N alloys of rocksalt structure

    SciTech Connect

    Koutsokeras, L. E.; Abadias, G.; Patsalas, P.

    2011-08-15

    The mechanisms controlling the structural and morphological features (texture and microstructure) of ternary transition metal nitride thin films of the Ti{sub x}Ta{sub 1-x}N system, grown by various physical vapor deposition techniques, are reported. Films deposited by pulsed laser deposition, dual cathode magnetron sputtering, and dual ion beam sputtering have been investigated by means of x-ray diffraction in various geometries and scanning electron microscopy. We studied the effects of composition, energetic, and kinetics in the evolution of the microstructure and texture of the films. We obtain films with single and mixed texture as well as films with columnar ''zone-T'' and globular type morphology. The results have shown that the texture evolution of ternary transition metal nitrides as well as the microstructural features of such films can be well understood in the framework of the kinetic mechanisms proposed for their binary counterparts, thus giving these mechanisms a global application.

  15. Correlated high-resolution x-ray diffraction photoluminescence and atom probe tomography analysis of continuous and discontinuous InxGa1-xN quantum wells

    DOE PAGES

    Ren, Xiaochen; Riley, James R.; Koleske, Daniel; ...

    2015-07-14

    In this study, atom probe tomography (APT) is used to characterize the influence of hydrogen dosing duringGaN barrier growth on the indium distribution of InxGa1-xN quantum wells, and correlatedmicro-photoluminescence is used to measure changes in the emission spectrum and efficiency. We found that relative to the control growth, hydrogen dosing leads to a 50% increase in emission intensity arising from discontinuous quantum wells that are narrower, of lower indium content, and with more abrupt interfaces. Additionally, simulations of carrier distributions based on APT composition profiles indicate that the greater carrier confinement leads to an increased radiative recombination rate. Furthermore, APTmore » analysis of quantum well profiles enables refinement of x-ray diffractionanalysis for more accurate nondestructive measurements of composition.« less

  16. The Structural Quality of AlxGa1-xN Epitaxial Layers Grown by Digitally-AlloyedModulated Precursor Epitaxy Determined by Transmission Electron Microscopy

    SciTech Connect

    Hawkridge, Michael E; Liliental-Weber, Zuzanna; Kim, Hee Jin; Choi, Suk; Yoo, Dongwon; Ryou, Jae-Hyun; Dupuis, Russell

    2008-10-13

    Al(x)Ga(1-x)N layers of varying composition (0.5

  17. Anomalous Hall effect in epitaxial ferrimagnetic anti-perovskite Mn{sub 4−x}Dy{sub x}N films

    SciTech Connect

    Meng, M.; Wu, S. X. Zhou, W. Q.; Ren, L. Z.; Wang, Y. J.; Wang, G. L.; Li, S. W.

    2015-08-07

    Anomalous Hall effect (AHE) has been studied for ferrimagnetic antiperovskite Mn{sub 4−x}Dy{sub x}N films grown by molecular-beam epitaxy. The introduction of Dy changes the AHE dramatically, even changes its sign, while the variations in magnetization are negligible. Two sign reversals of the AHE (negative-positive-negative) are ascribed to the variation of charge carriers as a result of Fermi surface reconstruction. We further demonstrate that the AHE current J{sub AH} is dissipationless (independent of the scattering rate), by confirming that anomalous Hall conductivity, σ{sub AH}, is proportional to the carrier density n at 5 K. Our study may provide a route to further utilize antiperovskite manganese nitrides in spintronics.

  18. High efficiency ultraviolet emission from AlxGa1-xN core-shell nanowire heterostructures grown on Si (111) by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Wang, Q.; Nguyen, H. P. T.; Cui, K.; Mi, Z.

    2012-07-01

    High crystalline quality, vertically aligned AlxGa1-xN nanowire heterostructures are grown on GaN nanowire templates on Si (111) substrates by plasma-assisted molecular beam epitaxy. The nanowires exhibit unique core-shell structures, with enhanced Al compositions in the near-surface region. The emission wavelength can be varied across nearly the entire ultraviolet A (˜3.10-3.94 eV) and B (˜3.94-4.43 eV) spectral range by controlling the Al compositions. Such nanowire structures can exhibit extremely high internal quantum efficiency (up to ˜58%) at room-temperature, which is attributed to the superior carrier confinement offered by the core-shell structures and to the use of defect-free GaN nanowire templates.

  19. Crystal structure study of dielectric oxynitride perovskites La1-xSrxTiO2+xN1-x (x=0, 0.2)

    NASA Astrophysics Data System (ADS)

    Habu, Daiki; Masubuchi, Yuji; Torii, Shuki; Kamiyama, Takashi; Kikkawa, Shinichi

    2016-05-01

    As is the case with SrTaO2N, both cis-ordering of nitride anions and octahedral titling are also preferable in La1-xSrxTiO2+xN1-x (x=0, 0.2) oxynitride perovskites. A larger dielectric constant of εr≈5.0×103 was estimated for the pure oxynitride with x=0.2, compared with εr≈750 for the product with x=0, by extrapolating the εr values obtained from powders mixed with paraffin at various mixing ratios. The crystal structure of x=0.2 with larger tolerance factor than x=0 increased the octahedral tilting, which contributes to the increased dielectric constant. The increased dielectric constant supports the exchange mechanism for the dielectric property between two kinds of -Ti-N- helical coils (clockwise and anticlockwise) derived from the above cis-ordering of nitride anions.

  20. Synthesis and characterization of novel rocksalt-type oxynitrides, LiTi nO xN y ( n=1, 2, 3, 4 and 8)

    NASA Astrophysics Data System (ADS)

    Katsumata, Tetsuhiro; Takaki, Seiko; Inaguma, Yoshiyuki; Shan, Yue Jin

    2004-12-01

    Novel oxynitrides, LiTi nO xN y ( n=1, 2, 3, 4 and 8) were synthesized by sintering under NH 3 gas atmosphere. These compounds have rocksalt-type structure and the existence of cation vacancies is suggested. While the lattice parameters of these compound slightly vary, obvious tendency for the Li or nitride content is not found. For these compounds, the temperature dependence of the electronic conductivity shows the semiconducting behavior. However, the measurement of magnetic susceptibility and the Seebeck coefficient suggest that the transport in these compound is metallic. The electric conductivity seems to be dominated by the resistance of the grain boundary and the transport property of these compounds is metallic.

  1. Oligomerization of L-gamma-carboxyglutamic acid

    NASA Technical Reports Server (NTRS)

    Hill, A. R. Jr; Orgel, L. E.; Bada, J. L. (Principal Investigator)

    1999-01-01

    Unlike glutamic acid, L-gamma-carboxyglutamic acid does not oligomerize efficiently when treated with carbonyldiimidazole in aqueous solution. However, divalent ions such as Mg2+ catalyze the reaction, and lead to the formation of oligomers in good yield. In the presence of hydroxylapatite, L-gamma-carboxyglutamic acid oligomerizes efficiently in a reaction that proceeds in the absence of divalent ions but is further catalyzed when they are present. After 'feeding' 50 times with activated amino acid in the presence of the Mg2+ ion, oligomers longer than the 20-mer could be detected. The effect of hydroxylapatite on peptide elongation is very sensitive to the nature of the activated amino acid and the acceptor peptide. Glutamic acid oligomerizes more efficiently than L-gamma-carboxyglutamic acid on hydroxylapatite and adds more efficiently to decaglutamic acid in solution. One might, therefore, expect that glutamic acid would add more efficiently than L-gamma-carboxyglutamic acid to decaglutamic acid on hydroxylapatite. The contrary is true--the addition of L-gamma-carboxyglutamic acid is substantially more efficient. This suggests that oligomerization on the surface of hydroxylapatite depends on the detailed match between the structure of the surface of the mineral and the structure of the oligomer.

  2. Oligomerization of L-gamma-carboxyglutamic acid.

    PubMed

    Hill, A R; Orgel, L E

    1999-03-01

    Unlike glutamic acid, L-gamma-carboxyglutamic acid does not oligomerize efficiently when treated with carbonyldiimidazole in aqueous solution. However, divalent ions such as Mg2+ catalyze the reaction, and lead to the formation of oligomers in good yield. In the presence of hydroxylapatite, L-gamma-carboxyglutamic acid oligomerizes efficiently in a reaction that proceeds in the absence of divalent ions but is further catalyzed when they are present. After 'feeding' 50 times with activated amino acid in the presence of the Mg2+ ion, oligomers longer than the 20-mer could be detected. The effect of hydroxylapatite on peptide elongation is very sensitive to the nature of the activated amino acid and the acceptor peptide. Glutamic acid oligomerizes more efficiently than L-gamma-carboxyglutamic acid on hydroxylapatite and adds more efficiently to decaglutamic acid in solution. One might, therefore, expect that glutamic acid would add more efficiently than L-gamma-carboxyglutamic acid to decaglutamic acid on hydroxylapatite. The contrary is true--the addition of L-gamma-carboxyglutamic acid is substantially more efficient. This suggests that oligomerization on the surface of hydroxylapatite depends on the detailed match between the structure of the surface of the mineral and the structure of the oligomer.

  3. Oligomerization of L-gamma-carboxyglutamic acid

    NASA Technical Reports Server (NTRS)

    Hill, A. R. Jr; Orgel, L. E.; Bada, J. L. (Principal Investigator)

    1999-01-01

    Unlike glutamic acid, L-gamma-carboxyglutamic acid does not oligomerize efficiently when treated with carbonyldiimidazole in aqueous solution. However, divalent ions such as Mg2+ catalyze the reaction, and lead to the formation of oligomers in good yield. In the presence of hydroxylapatite, L-gamma-carboxyglutamic acid oligomerizes efficiently in a reaction that proceeds in the absence of divalent ions but is further catalyzed when they are present. After 'feeding' 50 times with activated amino acid in the presence of the Mg2+ ion, oligomers longer than the 20-mer could be detected. The effect of hydroxylapatite on peptide elongation is very sensitive to the nature of the activated amino acid and the acceptor peptide. Glutamic acid oligomerizes more efficiently than L-gamma-carboxyglutamic acid on hydroxylapatite and adds more efficiently to decaglutamic acid in solution. One might, therefore, expect that glutamic acid would add more efficiently than L-gamma-carboxyglutamic acid to decaglutamic acid on hydroxylapatite. The contrary is true--the addition of L-gamma-carboxyglutamic acid is substantially more efficient. This suggests that oligomerization on the surface of hydroxylapatite depends on the detailed match between the structure of the surface of the mineral and the structure of the oligomer.

  4. In-Beam Gamma Spectroscopy

    NASA Astrophysics Data System (ADS)

    Mayank, .; Muralithar, S.; Sihotra, S.; Kumar, S.; Mehta, D.; Singh, R. P.; Rathore, Urvashi

    2016-09-01

    In-beam Gamma ray spectroscopic techniques have been studied using Indian National Gamma Array, IUAC which has a relative photo-peak efficiency of 5%. Data of a previous experiment where high angular momentum states of various nuclides were populated in the fusion-evaporation reaction 75As (28Si, 2p2n) at Elab = 120MeV. When gammas from populated nuclides are emanated during de-excitation, they are emitted with a certain angular distribution depending upon their multipolarity. Angular distribution of dipole and quadrupole transitions in 96Ru has been obtained from this data. The efficiency corrected angular distribution plot has been compared with the theoretical angular distribution function. The distribution co-efficients A2 and A4 for dipole and quadrupole were extracted from fitting the distribution with the equation: W (θ) = 1 +A2 *P2(cosθ) +A4 *P4(cosθ) . The Directional-correlation of Oriented Nuclei method was used to assign various other transitions as quadrupole or dipole. A DCO matrix between detectors at 1480 versus 900 was created using CANDLE. Intensities of transitions that have similar multipolarity as the gated transition would be equal in both the projected spectrums. In case of different multipolarity intensities would vary by a factor of 2. RDCO plots for 96Ru transitions have been obtained. To determine the nature of transitions whether magnetic or electric, a plot between polarization asymmetry (Δ) and DCO-ratio for transitions in 96Ru has been obtained.

  5. MOLE: A new high-energy gamma-ray diagnostic

    SciTech Connect

    Moran, M.J.; Chang, B.

    1992-01-21

    Continued interest in high-energy {gamma} rays associated with fusion reactions has motivated an ongoing search for simple, effective measurement techniques. Past experiments have measured 16.7-MeV {gamma} rays with Compton-magnetic spectrometers. Some measurements have been performed with threshold Cherenkov detectors with enhanced sensitivity to high-energy {gamma} rays. The Compton spectrometers work quite well, but they require extensive calibrations and tend to be expensive and cumbersome. The threshold Cherenkov detectors are simpler to calibrate and physically compact, but have poor spectral definition and are vulnerable to background signals. This report is to describe a new type of {gamma}-ray detector, the MOLE, that may retain the simplicity of a threshold Cherenkov detector while still having sufficient energy discrimination to be effective for measuring high-energy {gamma}-rays in the presence of lower-energy {gamma}-ray fluxes.

  6. New insights from cosmic gamma rays

    NASA Astrophysics Data System (ADS)

    Roland, Diehl

    2016-04-01

    The measurement of gamma rays from cosmic sources at ~MeV energies is one of the key tools for nuclear astrophysics, in its study of nuclear reactions and their impacts on objects and phenomena throughout the universe. Gamma rays trace nuclear processes most directly, as they originate from nuclear transitions following radioactive decays or high-energy collisions with excitation of nuclei. Additionally, the unique gamma-ray signature from the annihilation of positrons falls into this astronomical window and is discussed here: Cosmic positrons are often produced from β-decays, thus also of nuclear physics origins. The nuclear reactions leading to radioactive isotopes occur inside stars and stellar explosions, which therefore constitute the main objects of such studies. In recent years, both thermonuclear and core-collapse supernova radioactivities have been measured though 56Ni, 56Co, and 44Ti lines, and a beginning has thus been made to complement conventional supernova observations with such measurements of the prime energy sources of supernova light created in their deep interiors. The diffuse radioactive afterglow of massive-star nucleosynthesis in gamma rays is now being exploited towards astrophysical studies on how massive stars feed back their energy and ejecta into interstellar gas, as part of the cosmic cycle of matter through generations of stars enriching the interstellar gas and stars with metals. Large interstellar cavities and superbubbles have been recognised to be the dominating structures where new massive-star ejecta are injected, from 26Al gamma-ray spectroscopy. Also, constraints on the complex interiors of stars derive from the ratio of 60Fe/26Al gamma rays. Finally, the puzzling bulge-dominated intensity distribution of positron annihilation gamma rays is measured in greater detail, but still not understood; a recent microquasar flare provided evidence that such objects may be prime sources for positrons in interstellar space, rather than

  7. Gamma titanium aluminide alloys

    SciTech Connect

    Yamaguchi, M.; Inui, H.; Kishida, K.; Matsumuro, M.; Shirai, Y.

    1995-08-01

    Extensive progress and improvements have been made in the science and technology of gamma titanium aluminide alloys within the last decade. In particular, the understanding of their microstructural characteristics and property/microstructure relationships has been substantially deepened. Based on these achievements, various engineering two-phase gamma alloys have been developed and their mechanical and chemical properties have been assessed. Aircraft and automotive industries arc pursuing their introduction for various structural components. At the same time, recent basic studies on the mechanical properties of two-phase gamma alloys, in particular with a controlled lamellar structure have provided a considerable amount of fundamental information on the deformation and fracture mechanisms of the two-phase gamma alloys. The results of such basic studies are incorporated in the recent alloy and microstructure design of two-phase gamma alloys. In this paper, such recent advances in the research and development of the two-phase gamma alloys and industrial involvement are summarized.

  8. Electrochemical evidences for promoted interfacial reactions: the role of Fe(II) adsorbed onto gamma-Al2O3 and TiO2 in reductive transformation of 2-nitrophenol.

    PubMed

    Li, Fang-Bai; Tao, Liang; Feng, Chun-hua; Li, Xiang-Zhong; Sun, Ke-Wen

    2009-05-15

    This study was aimed at elucidating the role of adsorbed Fe(II) on minerals in the reductive transformation of 2-nitrophenol (2-NP) by using electrochemical methods. The studies of Fe(ll) adsorption and 2-NP reduction kinetics showed that the identity of minerals such as gamma-Al2O3 and TiO and the solution pH were crucial factors to determine the Fe(ll) adsorption behavior and to influence the rate constant (k) of 2-NP reduction. Furthermore, two electrochemical methods, cyclic voltammetry (CV) and electrochemical impedance spectrometry (EIS), were applied to characterize the Fe(II) reactivity with both the mineral-coated and mineral-free electrodes. The electrochemical evidence confirmed that the peak oxidation potential (Ep) of complex Fe(II) can be significantly affected by the solution pH;the enhanced reductive transformation of 2-NP can be related to the reduced Ep of surface-complex Fe(II) and the reduced charge transfer resistance (R(CT)) of the Fe(III)/Fe(II) couple. All these relationships were studied quantitatively. At pH 6.7, the measured Ep and R(CT) decreased in the order TiO2/GC < gamma-Al2O3/ GC < GC (Ep, 0.140 < 0.190 < 0.242 V; R(CT), 0.30 < 0.41 < 0.78 komega), while the 2-NP reduction on different minerals were in the order TiO2 > gamma-Al2O3 > nonmineral (k x 10-2, 7.91 > 0.64 > 0.077 min(-l)).

  9. Indirect Signatures of CP Violation in the Processes {gamma}{gamma} {yields} {gamma}{gamma}, {gamma}Z, and ZZ

    SciTech Connect

    Petriello, Frank J

    2001-07-25

    This paper studies the utility of the processes {gamma}{gamma} {yields} {gamma}{gamma}, {gamma}Z, and ZZ in searching for sources of CP violation arising from energy scales beyond the production thresholds of planned future colliders. In the context of an effective Lagrangian approach we consider the most general set of CP odd SU(2) x U(1) operators that give rise to genuinely quartic gauge boson couplings which can be probed in 2 {yields} 2 scattering processes at a {gamma}{gamma} collider. We study each process in detail, emphasizing the complementary information that is obtained by varying the initial beam polarizations. Finally, we compare our results to other constraints in the literature on CP odd gauge boson interactions and quartic gauge boson couplings; the search reaches obtained here are typically stronger and nicely complement previous studies which have focused primarily on W boson, top quark, or Higgs production.

  10. Next Generation Gamma Ray Diagnostics for the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Herrmann, Hans; Kim, Y. H.; McEvoy, A. M.; Zylstra, A. B.; Young, C. S.; Lopez, F. E.; Griego, J. R.; Fatherley, V. E.; Oertel, J. A.; Jorgenson, H. J.; Barlow, D. B.; Stoeffl, W.; Church, J. A.; Hernandez, J. E.; Carpenter, A.; Rubery, M. S.; Horsfield, C. J.; Gales, S.; Leatherland, A.; Hilsabeck, T.; Kilkenny, J. D.; Malone, R. M.; Moy, K.; Hares, J. D.; Milnes, J.

    Fusion reaction history and ablator areal density measurements based on gamma ray detection are an essential part of Inertial Confinement Fusion (ICF) experiments on the National Ignition Facility (NIF). Capability improvements are being implemented in sensitivity, temporal and spectral response relative to the existing Gamma Reaction History diagnostic (GRH-6m). The ``Super'' Gas Cherenkov Detector (GCD) will provide 200x more sensitivity, reduce the effective temporal resolution from 100 to 10 ps, and lower the energy threshold from 2.9 to 1.8 MeV, relative to GRH-6m. The Gamma-to-Electron Magnetic Spectrometer (GEMS) - a Compton spectrometer intended to provide true gamma energy resolution (<=5%) for isolation of specific lines such as t(d, γ) , D(n, γ) , 12C(n,n' γ) and energetic charged particle nuclear reactions indicative of ablator/fuel mix

  11. Gamma ray transients

    NASA Technical Reports Server (NTRS)

    Cline, Thomas L.

    1987-01-01

    The discovery of cosmic gamma ray bursts was made with systems designed at Los Alamos Laboratory for the detection of nuclear explosions beyond the atmosphere. HELIOS-2 was the first gamma ray burst instrument launched; its initial results in 1976, seemed to deepen the mystery around gamma ray transients. Interplanetary spacecraft data were reviewed in terms of explaining the behavior and source of the transients.

  12. {gamma} production at CDF

    SciTech Connect

    Abe, F.

    1995-07-01

    We report on preliminary measurements of the {gamma}(1S), {gamma}(2S) and {gamma}(3S) differential and integrated cross sections in p{bar p} at {radical}s = 1.8 TeV using a sample of 16.6 {+-} 0.6 pb{sup -1} collected by the Collider Detector at Fermilab. The three resonances were reconstructed through the decay {gamma} {yields} {mu}{sup +}{mu}{sup -} in the rapidity region {vert_bar}y{vert_bar} < 0.4. The cross section results are compared to theoretical models of direct bottomonium production.

  13. A model reaction assesses contribution of H-tunneling and coupled motions to enzyme catalysis.

    PubMed

    Liu, Qi; Zhao, Yu; Hammann, Blake; Eilers, James; Lu, Yun; Kohen, Amnon

    2012-08-17

    To assess the contribution of physical features to enzyme catalysis, the enzymatic reaction has to be compared to a relevant uncatalyzed reaction. While such comparisons have been conducted for some hydrolytic and radical reactions, it is most challenging for biological hydride transfer and redox reactions in general. Here, the same experimental tools used to study the H-tunneling and coupled motions for enzymatic hydride transfer between two carbons were used in the study of an uncatalyzed model reaction. The enzymatic oxidations of benzyl alcohol and its substituted analogues mediated by alcohol dehydrogenases were compared to the oxidations by 9-phenylxanthylium cation (PhXn(+)). The PhXn(+) serves as an NAD(+) model, while the solvent, acetonitrile, models the protein environment. Experimental comparisons included linear free energy relations with Hammett reaction constant (ρ) of zero versus -2.7; temperature-independent versus temperature-dependent primary KIEs; deflated secondary KIEs with deuteride transfer (i.e., primary-secondary coupled motion) versus no coupling between secondary KIEs and H- or D-transfer; and large versus small secondary KIEs for the enzymatic versus uncatalyzed alcohol oxidation. Some of the differences may come from differences in the order of microscopic steps between the catalyzed versus uncatalyzed reactions. However, several of these comparative experiments indicate that in contrast to the uncatalyzed reaction the transition state of the enzymatic reaction is better reorganized for H-tunneling and its H-donor is better rehybridized prior to the C-H→C transfer. These findings suggest an important role for these physical features in enzyme catalysis.

  14. Detection and quantification of hypo- and hypergranulated neutrophils on the new Sysmex XN hematology analyzer: establishment of an adapted reference interval for the neutrophil-granularity-intensity compared to XE-technology in adult patients.

    PubMed

    Zimmermann, Mathias; Steenhuis, Pieter; Linssen, Jo; Weimann, Andreas

    2015-01-01

    Since the recent introduction of Sysmex hematology analyzers of the XN-series it can be expected that the values of individual hematological parameters might differ between the new XN and the well-established XE platform. One such parameter is called Neutrophil-Granularity-Intensity or NEUT-GI on the XN-series and NEUT-X on the XE-series. Both parameters are used by clinicians to calculate the Granularity-Index (GI-Index), an important tool to detect hypo- or hypergranulated neutrophils occurring during myelodysplasia or inflammation. The aims of this study were to determine if previously reported reference intervals for NEUT-X can be used for NEUT-GI as well and if the GI-Indices on both analyzer platforms correlate with each other. NEUT-GI and NEUT-X were assessed in a set of 789 blood samples (n = 543 samples from adult intensive care units and n = 246 samples from adult "blood-healthy" control patients) and the corresponding Granularity-Indices were calculated for all samples using data obtained from XE-5000 and XN-1000 hematology analyzers. NEUT-GI and NEUT-X correlated significantly with each other (r2: 0.6512; p < 0.0001) with statistically significant higher values for NEUT-GI compared to NEUT-X in the control group (p < 0.0001) as well as in the ICU patients (p < 0.0001). This indicated that previously established reference intervals for NEUT-X cannot be used for NEUT-GI. In contrast, the GI-Indices showed no statistically significant difference between the analyzers in both groups. The GI-Indices were higher in the ICU patients compared to the control group on both analyzer platforms (p < 0.0001), as would be expected. Our study revealed the emphatic need for a new reference interval for NEUT-GI on the XN platform. The resulting 95% reference intervals were 140.91 - 160.46 channels for NEUT-GI and 129.20 - 142.33 channels for NEUT-X. The GI-Indices showed no significant statistical difference between the XN- and XE-series in both cohorts.

  15. Directional gamma detector

    DOEpatents

    LeVert, Francis E.; Cox, Samson A.

    1981-01-01

    An improved directional gamma radiation detector has a collector sandwiched etween two layers of insulation of varying thicknesses. The collector and insulation layers are contained within an evacuated casing, or emitter, which releases electrons upon exposure to gamma radiation. Delayed electrons and electrons entering the collector at oblique angles are attenuated as they pass through the insulation layers on route to the collector.

  16. Gamma-Ray Pulsars

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    2011-01-01

    The Fermi Gamma-Ray Space Telescope has revolutionized the study of pulsar physics with the detection of over 80 gamma-ray pulsars. Several new populations have been discovered, including 24 radio quiet pulsars found through gamma-ray pulsations alone and about 20 millisecond gamma-ray pulsars. The gamma-ray pulsations from millisecond pulsars were discovered by both folding at periods of known radio millisecond pulsars or by detecting them as gamma-ray sources that are followed up by radio pulsar searches. The second method has resulted in a phenomenally successful synergy, with -35 new radio MSPs (to date) having been discovered at Fermi unidentified source locations and the gamma-ray pulsations having then been detected in a number of these using the radio timing solutions. The higher sensitivity and larger energy range of the Fermi Large Area Telescope has produced detailed energy-dependent light curves and phase-resolved spectroscopy on brighter pulsars, that have ruled out polar cap models as the major source of the emission in favor of outer magnetosphere accelerators. The large number of gamma-ray pulsars now allows for the first time meaningful population and sub-population studies that are revealing surprising properties of these fascinating sources.

  17. Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    Kouveliotou, Chryssa; Wijers, Ralph A. M. J.; Woosley, Stan

    2012-11-01

    Prologue C. Kouveliotou, R. A . M. J. Wijers and S. E. Woosley; 1. The discovery of the gamma-ray burst phenomenon R. W. Klebesadel; 2. Instrumental principles E. E. Fenimore; 3. The BATSE era G. J. Fishman and C. A. Meegan; 4. The cosmological era L. Piro and K. Hurley; 5. The Swift era N. Gehrels and D. N. Burrows; 6. Discoveries enabled by multi-wavelength afterglow observations of gamma-ray bursts J. Greiner; 7. Prompt emission from gamma-ray bursts T. Piran, R. Sari and R. Mochkovitch; 8. Basic gamma-ray burst afterglows P. Mészáros and R. A. M. J. Wijers; 9. The GRB-supernova connection J. Hjorth and J. S. Bloom; 10. Models for gamma-ray burst progenitors and central engines S. E. Woosley; 11. Jets and gamma-ray burst unification schemes J. Granot and E. Ramirez-Ruiz; 12. High-energy cosmic rays and neutrinos E. Waxman; 13. Long gamma-ray burst host galaxies and their environments J. P. U. Fynbo, D. Malesani and P. Jakobsson; 14. Gamma-ray burst cosmology V. Bromm and A. Loeb; 15. Epilogue R. D. Blandford; Index.

  18. Gamma-ray astrophysics

    NASA Technical Reports Server (NTRS)

    Stecker, F. W. (Editor); Trombka, J. I. (Editor)

    1973-01-01

    Conference papers on gamma ray astrophysics are summarized. Data cover the energy region from about 0.3 MeV to a few hundred GeV and theoretical models of production mechanisms that give rise to both galactic and extragalactic gamma rays.

  19. Muons in gamma showers

    NASA Technical Reports Server (NTRS)

    Stanev, T.; Vankov, C. P.; Halzen, F.

    1985-01-01

    Muon production in gamma-induced air showers, accounting for all major processes. For muon energies in the GeV region the photoproduction is by far the most important process, while the contribution of micron + micron pair creation is not negligible for TeV muons. The total rate of muons in gamma showers is, however, very low.

  20. Dosimetry in mixed neutron-gamma fields

    SciTech Connect

    Remec, I.

    1998-04-01

    The gamma field accompanying neutrons may, in certain circumstances, play an important role in the analysis of neutron dosimetry and even in the interpretation of radiation induced steel embrittlement. At the High Flux Isotope Reactor pressure vessel the gamma induced reactions dominate the responses of {sup 237}Np and {sup 238}U dosimeters, and {sup 9}Be helium accumulation fluence monitors. The gamma induced atom displacement rate in steel is higher than corresponding neutron rate, and is the cause of ``accelerated embrittlement`` of HFIR materials. In a large body of water, adjacent to a fission plate, photofissions contribute significantly to the responses of fission monitors and need to be taken into account if the measurements are used for the qualification of the transport codes and cross-section libraries.

  1. Optical gamma thermometer

    DOEpatents

    Koster, Glen Peter; Xia, Hua; Lee, Boon Kwee

    2013-08-06

    An optical gamma thermometer includes a metal mass having a temperature proportional to a gamma flux within a core of a nuclear reactor, and an optical fiber cable for measuring the temperature of the heated metal mass. The temperature of the heated mass may be measured by using one or more fiber grating structures and/or by using scattering techniques, such as Raman, Brillouin, and the like. The optical gamma thermometer may be used in conjunction with a conventional reactor heat balance to calibrate the local power range monitors over their useful in-service life. The optical gamma thermometer occupies much less space within the in-core instrument tube and costs much less than the conventional gamma thermometer.

  2. Catalytic action of L-methionine gamma-lyase on selenomethionine and selenols.

    PubMed

    Esaki, N; Tanaka, H; Uemura, S; Suzuki, T; Soda, K

    1979-02-06

    We examined the catalytic action of L-methionine gamma-lyase (EC 4.4.1.11) on selenomethionine (2-amino-4-(methylseleno)butyric acid), methaneselenol, l-hexaneselenol, and benzeneselenol. The enzyme catalyzes alpha, gamma-elimination of selenomethionine to yield alpha-letobutyrate, ammonia, and methaneselenol, and also its gamma-replacement reaction with various thiols to produce S-substituted homocysteines. Selenomethionine is an even better substrate than methionine in alpha, gamma-elimination but is less effective in gamma-replacement. In addition, L-methionine gamma-lyase catalyzes gamma-replacement reaction of methionine and its derivatives with selenols to form the corresponding Se-substituted selenohomocysteines, although selenols are less efficient substituent donors than thiols. This is the first proven mechanism for the incorporation of selenium atom into amino acids.

  3. Activation cross sections of α-particle induced nuclear reactions on hafnium and deuteron induced nuclear reaction on tantalum: production of ¹⁷⁸W/(178m)Ta generator.

    PubMed

    Tárkányi, F; Takács, S; Ditrói, F; Hermanne, A; Ignatyuk, A V; Uddin, M S

    2014-09-01

    In the frame of a systematic study of charged particle production routes of medically relevant radionuclei, the excitation function for indirect production of (178m)Ta through (nat)Hf(α,xn)(178)W-(178m)Ta nuclear reaction was measured for the first time up to 40 MeV. In parallel, the side reactions (nat)Hf(α,x)(179,177,176,175)W, (183,182,178g,177,176,175)Ta, (179m,177m,175)Hf were also assessed. Stacked foil irradiation technique and γ-ray spectrometry were used. New experimental cross section data for the (nat)Ta(d,xn)(178)W reaction are also reported up to 40 MeV. The measured excitation functions are compared with the results of the ALICE-IPPE, and EMPIRE nuclear reaction model codes and with the TALYS 1.4 based data in the TENDL-2013 library. The thick target yields were deduced and compared with yields of other charged particle ((p,4n), (d,5n) and ((3)He,x)) production routes for (178)W. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Design of an innovative gamma ray spectroscopy image-based telescope by assigning reciprocal vision color to each gamma photon depending on the energy of gamma photons

    NASA Astrophysics Data System (ADS)

    Rahmani Nejad, Akbar; Olia, M. A.

    2009-08-01

    In this paper an innovative method to devise a new astronomical observation instrument by simultaneous implementation of a gamma telescope and a gamma spectroscope is presented. Electromagnetic beams emitted from a star e.g. the sun is spread all electromagnetic spectrum from gamma rays to radio waves, but there is a fingerprint in such a wide spectrum that shows the exact fusion reaction which can be traced by associated gamma photons. This means if gamma photons, emitted from each part of sun, to be detected by this instrument, then spatial information is provided by telescope and information about the energy is recorded by spectrometer, by convolving two above mentioned data, there will be an illustration of a star like the sun that can show which area emits associated gamma photons that in turn illustrates the spatial distribution of elements that produce these gamma photons e.g. hydrogen, deuterium, tritium, helium, etc. we choose a reference color for each principle gamma photon, according to method similar to gamut color space of CIE [1], by specific linear transformation, or transformation matrix having photon-energy dependence coefficients, then there will be a colorful illustration of sun or any star (or even a GRB) that depicts distribution of elements, released energy, density of elements, etc. This information in turn will reveal the rate and topological variation of matter, energy, magnetic fields, etc. This information will also help to provide enough data to find spatial distribution function of energy, matter, variation and displacement of matters on stars and in turn, it will provide unique information about behaviors of stars. Finally, the method of vibrating holes to increase the spatial resolution of gamma detectors to hundreds times is presented. This method increases the spatial resolution of semiconductor-gamma telescopes to hundreds of times without decreasing the size of gamma sensor pixels and without any major effort to improve the

  5. Excitation function and yield for the (103)Rh(d,2n)(103)Pd nuclear reaction: Optimization of the production of palladium-103.

    PubMed

    Manenti, Simone; Alí Santoro, María Del Carmen; Cotogno, Giulio; Duchemin, Charlotte; Haddad, Ferid; Holzwarth, Uwe; Groppi, Flavia

    2017-03-06

    Deuteron-induced nuclear reactions for the generation of (103)Pd were investigated using the stacked-foil activation technique on rhodium targets at deuteron energies up to Ed=33MeV. The excitation functions of the reactions (103)Rh(d,xn)(101,103)Pd, (103)Rh(d,x)(100g,cum,101m,g,102m,g)Rh and (103)Rh(d,2p)(103)Ru have been measured, and the Thick-Target Yield for (103)Pd has been calculated.

  6. Maximum Torque and Momentum Envelopes for Reaction Wheel Arrays

    NASA Technical Reports Server (NTRS)

    Markley, F. Landis; Reynolds, Reid G.; Liu, Frank X.; Lebsock, Kenneth L.

    2009-01-01

    Spacecraft reaction wheel maneuvers are limited by the maximum torque and/or angular momentum that the wheels can provide. For an n-wheel configuration, the torque or momentum envelope can be obtained by projecting the n-dimensional hypercube, representing the domain boundary of individual wheel torques or momenta, into three dimensional space via the 3xn matrix of wheel axes. In this paper, the properties of the projected hypercube are discussed, and algorithms are proposed for determining this maximal torque or momentum envelope for general wheel configurations. Practical strategies for distributing a prescribed torque or momentum among the n wheels are presented, with special emphasis on configurations of four, five, and six wheels.

  7. Infrared dielectric functions, phonon modes, and free-charge carrier properties of high-Al-content AlxGa1-xN alloys determined by mid infrared spectroscopic ellipsometry and optical Hall effect

    NASA Astrophysics Data System (ADS)

    Schöche, S.; Hofmann, T.; Nilsson, D.; Kakanakova-Georgieva, A.; Janzén, E.; Kühne, P.; Lorenz, K.; Schubert, M.; Darakchieva, V.

    2017-05-01

    We report on the analysis of a combined mid-infrared spectroscopic ellipsometry and mid-infrared optical Hall effect investigation of wurtzite structure c-plane oriented, crack-free, single crystalline, and high-Al-content AlxGa1-xN layers on 4H-SiC. For high-Al-content AlxGa1-xN, a two mode behavior is observed for both transverse and longitudinal branches of the infrared-active modes with E1 symmetry, while a single mode behavior is found for the longitudinal modes with A1(LO) symmetry. We report their mode dependencies on the Al content. We determine and discuss static and high frequency dielectric constants depending on x. From the analysis of the optical Hall effect data, we determine the effective mass parameter in high-Al-content AlxGa1-xN alloys and its composition dependence. Within the experimental uncertainty limits, the effective mass parameters are found isotropic, which depend linearly on the Al content. The combination of all data permits the quantification of the free electron density N and mobility parameters μ.

  8. Digitally alloyed modulated precursor flow epitaxial growth of Al xGa 1-xN layers with AlN and Al yGa 1-yN monolayers

    NASA Astrophysics Data System (ADS)

    Choi, Suk; Kim, Hee Jin; Ryou, Jae-Hyun; Dupuis, Russell D.

    2009-06-01

    We propose a new growth scheme of digitally alloyed modulated precursor flow epitaxial growth (DA-MPEG) using metalorganic and hydride precursors for the growth of AlxGa1-xN layers with high-Al content at relatively low temperatures. The growth of high-quality, high-Al content AlxGa1-xN layers (xAl>50%) that are composed of AlN and AlyGa1-yN monolayers on AlN/sapphire template/substrates by DA-MPEG was demonstrated. The overall composition of the ternary AlxGa1-xN material by DA-MPEG can be controlled continuously by adjusting the Column III mole fraction of the atomic AlyGa1-yN sub-layer. X-ray diffraction and optical transmittance results show that the AlGaN materials have good crystalline quality. The surface morphology of DA-MPEG AlGaN samples measured by atomic force microscopy are comparable to high-temperature-grown AlGaN and are free from surface features such as nano-pits.

  9. Gamma-ray strength functions and their relation to astrophysics

    SciTech Connect

    Larsen, A. C.; Buerger, A.; Guttormsen, M.; Hagen, T. W.; Nyhus, H. T.; Rekstad, J. B.; Renstroem, T.; Rose, S. J.; Ruud, I. E.; Siem, S.; Syed, N. U. H.; Toft, H. K.; Tveten, G. M.; Wikan, K.; Algin, E.; Agvaanluvsan, U.; Goergen, A.

    2011-10-28

    The nuclear {gamma}-ray strength function is one of the indispensable inputs needed for reaction-rate calculations, and is particularly important for the neutron-capture cross section. The nuclear physics group at the Oslo Cyclotron Laboratory has developed a method to extract simultaneously nuclear level density and {gamma}-ray strength function from particle-{gamma} coincidence measurements. Data on the strength functions of Sn nuclei as well as for lighter elements are presented. The Sn isotopes all display a resonance-like structure close to the neutron threshold, that could possibly be due to the neutron-skin oscillation mode. This so-called pygmy dipole resonance greatly influences the neutron-capture rates. In the lighter nuclei, an enhancement of the strength function at low {gamma} energies is observed. The possible impact of this increase on Maxwellian-averaged reaction rates has been investigated.

  10. Sneaky Gamma-Rays: Using Gravitational Lensing to Avoid Gamma-Gamma-Absorption

    NASA Astrophysics Data System (ADS)

    Boettcher, Markus; Barnacka, Anna

    2014-08-01

    It has recently been suggested that gravitational lensing studies of gamma-ray blazars might be a promising avenue to probe the location of the gamma-ray emitting region in blazars. Motivated by these prospects, we have investigated potential gamma-gamma absorption signatures of intervening lenses in the very-high-energy gamma-ray emission from lensedblazars. We considered intervening galaxies and individual stars within these galaxies. We find that the collective radiation field of galaxies acting as sources of macrolensing are not expected to lead to significant gamma-gamma absorption. Individual stars within intervening galaxies could, in principle, cause a significant opacity to gamma-gamma absorption for VHE gamma-rays if the impact parameter (the distance of closest approach of the gamma-ray to the center of the star) is small enough. However, we find that the curvature of the photon path due to gravitational lensing will cause gamma-ray photons to maintain a sufficiently large distance from such stars to avoid significant gamma-gamma absorption. This re-inforces the prospect of gravitational-lensing studies of gamma-ray blazars without interference due to gamma-gamma absorption due to the lensing objects.

  11. Experimental Study of 17O(p,{alpha})14N and 17O(p,{gamma})18F for Classical Nova Nucleosynthesis

    SciTech Connect

    Chafa, A.; Ouichaoui, S.; Tatischeff, V.; Coc, A.; Garrido, F.; Kiener, J.; Lefebvre-Schuhl, A.; Thibaud, J.-P.; Aguer, P.; Barhoumi, S.; Hernanz, M.; Jose, J.; Sereville, N. de

    2006-04-26

    We investigated the proton-capture reactions on 17O occurring in classical nova explosions. We observed a previously undiscovered resonance at E{sub R}{sup lab}=194.1{+-}0.6 keV in the 17O(p,{alpha})14N reaction, with a measured resonance strength {omega}{gamma}p{alpha}=1.6{+-}0.2 meV. We studied in the same experiment the 17O(p,{gamma})18F reaction by an activation method and the resonance-strength ratio was found to be {omega}{gamma}p{alpha}/{omega}{gamma}p{gamma}=470{+-}50. The corresponding excitation energy in the 18F compound nucleus was determined to be 5789.8{+-}0.3 keV by {gamma}-ray measurements using the 14N({alpha},{gamma})18F reaction. These new resonance properties have important consequences for 17O nucleosynthesis and {gamma}-ray astronomy of classical novae.

  12. The gamma-ray observatory

    NASA Technical Reports Server (NTRS)

    1991-01-01

    An overview is given of the Gamma Ray Observatory (GRO) mission. Detection of gamma rays and gamma ray sources, operations using the Space Shuttle, and instruments aboard the GRO, including the Burst and Transient Source Experiment (BATSE), the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (COMPTEL), and the Energetic Gamma Ray Experiment Telescope (EGRET) are among the topics surveyed.

  13. THE {gamma}SF METHOD

    SciTech Connect

    Utsunomiya, H.; Akimune, H.; Yamagata, T.; Kondo, T.; Iwamoto, C.; Okamoto, A.; Goriely, S.; Harada, H.; Kitatani, F.; Goko, S.; Toyokawa, H.; Yamada, K.; Lui, Y.-W.; Hilaire, S.; Koning, A. J.

    2011-10-28

    The {gamma}-ray strength function ({gamma}SF) interconnects radiative neutron capture and photoneutron emission as a common ingredient in the statistical model. Outlined here is an indirect method of determining radiative neutron-capture cross sections for unstable nuclei based on the {gamma}-ray strength function. Application examples of the {gamma}SF method are demonstrated.

  14. Gamma-ray astronomy

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1982-01-01

    Cosmic gamma rays, the physical processes responsible for their production and the astrophysical sites from which they were seen are reported. The bulk of the observed gamma ray emission is in the photon energy range from about 0.1 MeV to 1 GeV, where observations are carried out above the atmosphere. There are also, however, gamma ray observations at higher energies obtained by detecting the Cerenkov light produced by the high energy photons in the atmosphere. Gamma ray emission was observed from sources as close as the Sun and the Moon and as distant as the quasar 3C273, as well as from various other galactic and extragalactic sites. The radiation processes also range from the well understood, e.g. energetic particle interactions with matter, to the still incompletely researched, such as radiation transfer in optically thick electron positron plasmas in intense neutron star magnetic fields.

  15. Gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.

    1991-01-01

    Miscellaneous tasks related to the development of the Bursts and Transient Source Experiment on the Gamma Ray Observatory and to analysis of archival data from balloon flight experiments were performed. The results are summarized and relevant references are included.

  16. Analogs of the giant dipole and spin-dipole resonances in {sup 4}He and in {alpha} clusters of {sup 6,7}Li studied by the {sup 4}He,{sup 6,7}Li({sup 7}Li,{sup 7}Be{gamma}) reactions

    SciTech Connect

    Nakayama, S.; Matsumoto, E.; Fushimi, K.; Hayami, R.; Kawasuso, H.; Yasuda, K.; Yamagata, T.; Akimune, H.; Ikemizu, H.; Asaji, S.; Ishida, T.; Kudoh, T.; Sagara, K.; Fujiwara, M.; Hashimoto, H.; Kawase, K.; Nakanishi, K.; Oota, T.; Yosoi, M.; Greenfield, M. B.

    2008-07-15

    We studied analogs of the giant dipole resonance (GDR) and spin-dipole resonance (SDR) in {sup 4}He and in the {alpha} clusters of {sup 6,7}Li via the ({sup 7}Li,{sup 7}Be{gamma}) reactions on {sup 4}He, {sup 6}Li, and {sup 7}Li at an incident energy of 455 MeV and at a scattering angle of 0 deg. by measuring spin-nonflip and spin-flip spectra. The reaction Q-values for the analogs of the GDR and SDR in the {alpha} clusters of {sup 6,7}Li were found to be more negative than those in {sup 4}He by 2.0{+-}0.5 MeV. The ratios of the cross section for the analog of the GDR to that for the analog of the SDR in {sup 4}He and in the {alpha} clusters of {sup 6}Li and {sup 7}Li were found to be the same within errors, 0.5{+-}0.1. The cross sections for the analogs of the GDR as well as those for the analogs of the SDR in the {alpha} clusters of {sup 6,7}Li were 0.6{approx}0.8 times smaller than those in {sup 4}He. These results suggest that excitations of {alpha} clusters embedded in nuclei are suppressed as compared with excitations of free {alpha} particles.

  17. New calculation method for initial exciton numbers on nucleon induced pre-equilibrium reactions

    SciTech Connect

    Tel, E.; Sarer, B.; Aydin, A.; Kaplan, A.

    2008-05-15

    In this study, we investigate the pre-equilibrium effect by using new evaluated geometry dependent hybrid model for the {sup 208}Pb (p,xn) reaction at 25.5 and 62.9 MeV incident proton energies. We also suggest that the initial neutron and proton exciton numbers for the nucleon induced precompound reactions be calculated from the neutron and proton density by using an effective nucleon-nucleon interaction with Skyrme force. We calculate the initial exciton numbers obtained from SKM* and SLy4 for a proton induced reaction on target nuclei {sup 208}Pb. The obtained results have been investigated and compared with the pre-equilibrium calculations and experimental results.

  18. Dynamic gamma knife radiosurgery

    NASA Astrophysics Data System (ADS)

    Luan, Shuang; Swanson, Nathan; Chen, Zhe; Ma, Lijun

    2009-03-01

    Gamma knife has been the treatment of choice for various brain tumors and functional disorders. Current gamma knife radiosurgery is planned in a 'ball-packing' approach and delivered in a 'step-and-shoot' manner, i.e. it aims to 'pack' the different sized spherical high-dose volumes (called 'shots') into a tumor volume. We have developed a dynamic scheme for gamma knife radiosurgery based on the concept of 'dose-painting' to take advantage of the new robotic patient positioning system on the latest Gamma Knife C™ and Perfexion™ units. In our scheme, the spherical high dose volume created by the gamma knife unit will be viewed as a 3D spherical 'paintbrush', and treatment planning reduces to finding the best route of this 'paintbrush' to 'paint' a 3D tumor volume. Under our dose-painting concept, gamma knife radiosurgery becomes dynamic, where the patient moves continuously under the robotic positioning system. We have implemented a fully automatic dynamic gamma knife radiosurgery treatment planning system, where the inverse planning problem is solved as a traveling salesman problem combined with constrained least-square optimizations. We have also carried out experimental studies of dynamic gamma knife radiosurgery and showed the following. (1) Dynamic gamma knife radiosurgery is ideally suited for fully automatic inverse planning, where high quality radiosurgery plans can be obtained in minutes of computation. (2) Dynamic radiosurgery plans are more conformal than step-and-shoot plans and can maintain a steep dose gradient (around 13% per mm) between the target tumor volume and the surrounding critical structures. (3) It is possible to prescribe multiple isodose lines with dynamic gamma knife radiosurgery, so that the treatment can cover the periphery of the target volume while escalating the dose for high tumor burden regions. (4) With dynamic gamma knife radiosurgery, one can obtain a family of plans representing a tradeoff between the delivery time and the

  19. Gamma-Ray Telescopes

    NASA Astrophysics Data System (ADS)

    Weekes, T.; Murdin, P.

    2000-11-01

    Gamma-rays are the highest-energy photons in the ELECTROMAGNETIC SPECTRUM and their detection presents unique challenges. On one hand it is easy to detect γ-rays. The interaction cross-sections are large and above a few MeV the pair production interaction, the dominant γ-ray interaction with matter, is easily recognized. Gamma-ray detectors were far advanced when the concept of `γ-ray astronomy' ...

  20. [Gamma (or immune) interferon].

    PubMed

    Maniu, H

    1987-01-01

    Research on interferon progressed very much during the last years, especially studies on the gamma type of interferon. Historical data about the research conducted on the gamma interferon, its inductors, its physical, chemical and biological properties, the methods of preparation and purification, as well as the perspective of therapeutical utilisation of this type of interferon, in spite of some reversible side effects, are presented and discussed.