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Sample records for 6li 7li nuclear

  1. (6)Li, (7)Li Nuclear Magnetic Resonance Investigation of Lithium Coordination in Binary Phosphate Glasses

    SciTech Connect

    Alam, T.M.; Boyle, T.J.; Brow, R.K.; Conzone, S.

    1999-02-08

    {sup 6}Li and {sup 7}Li solid state magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy has been used to investigate the local coordination environment of lithium in a series of xLi{sub 2}O {center_dot} (1-x)P{sub 2}O{sub 5} glasses, where 0.05 {le} x {le} 0.55. Both the {sup 6}Li and {sup 7}Li show chemical shift variations with changes in the Li{sub 2}O concentration, but the observed {sup 6}Li NMR chemical shifts closely approximate the true isotropic chemical shift and can provide a measure of the lithium bonding environment. The {sup 6}Li NMR results indicate that in this series of lithium phosphate glasses the Li atoms have an average coordination between four and five. The results for the metaphosphate glass agree with the coordination number and range of chemical shifts observed for crystalline LiPO{sub 3}. An increase in the {sup 6}Li NMR chemical shift with increasing Li{sub 2}O content was observed for the entire concentration range investigated, correlating with increased cross-linking of the phosphate tetrahedral network by O-Li-O bridges. The {sup 6}Li chemical shifts were also observed to vary monotonically through the anomalous glass transition temperature (T{sub g}) minimum. This continuous chemical shift variation shows that abrupt changes in the Li coordination environment do not occur as the Li{sub 2}O concentration is increased, and such abrupt changes can not be used to explain the T{sub g} minimum.

  2. Transport properties derived from ion-atom collisions: 6Li-6Li+ and 6Li-7Li+ Cases

    NASA Astrophysics Data System (ADS)

    Bouledroua, Moncef; Bouchelaghem, Fouzia; LPR Team

    2014-10-01

    This investigation treats quantum-mechanically the ion- atom collisions and computes the transport coefficients, such as the coefficients of mobility and diffusion. For the case of lithium, the calculations start by determining the gerade and ungerade potential curves through which ionic lithium approaches ground lithium. Then, by considering the isotopic effects and nuclear spins, the elastic and charge-transfer cross sections are calculated for the case of 6Li+and7Li+ colliding with 6Li. Finally, the temperature-dependent diffusion and mobility coefficients are analyzed, and the results are contrasted with those obtained from literature. The main results of this work have been recently published in. This work has been realized within the frames of the CNEPRU Project D01120110036 of the Algerian Ministry of Higher Education.

  3. A 2D MOT design optimized for dual-species 6 Li-7 Li experiments

    NASA Astrophysics Data System (ADS)

    Cai, Yanping; Evans, Jesse; Wright, Kevin

    2016-05-01

    We have built a 2D MOT optimized for simultaneous capture and cooling of 6 Li and 7 Li. The design includes a vapor source located very close to the capture region, which reduces depletion of the low-velocity part of the oven flux. The source is angled so that the most probable longitudinal velocity of captured atoms is near optimal for transferring to a 3D MOT, even without a push beam. Because 6 Li D2 repump light can impede capture and cooling of 7 Li, we have characterized the system performance with 6 Li repumped on both the D1 and D2 transitions. This design provides ample cold atom flux to load a dual-species 3D MOT for quantum degenerate gas experiments.

  4. Line shift, line asymmetry, and the ^6Li/^7Li isotopic ratio determination

    NASA Astrophysics Data System (ADS)

    Cayrel, R.; Steffen, M.; Chand, H.; Bonifacio, P.; Spite, M.; Spite, F.; Petitjean, P.; Ludwig, H.-G.; Caffau, E.

    2007-10-01

    Context: Line asymmetries are generated by convective Doppler shifts in stellar atmospheres, especially in metal-poor stars, where convective motions penetrate to higher atmospheric levels. Such asymmetries are usually neglected in abundance analyses. The determination of the ^6Li/^7Li isotopic ratio is prone to suffering from such asymmetries, as the contribution of ^6Li is a slight blending reinforcement of the red wing of each component of the corresponding ^7Li line, with respect to its blue wing. Aims: The present paper studies the halo star HD 74000 and estimates the impact of convection-related asymmetries on the Li isotopic ratio determination. Methods: Two methods are used to meet this aim. The first, which is purely empirical, consists in deriving a template profile from another element that can be assumed to originate in the same stellar atmospheric layers as Li I, producing absorption lines of approximately the same equivalent width as individual components of the ^7Li I resonance line. The second method consists in conducting the abundance analysis based on NLTE line formation in a 3D hydrodynamical model atmosphere, taking into account the effects of photospheric convection. Results: The results of the first method show that the convective asymmetry generates an excess absorption in the red wing of the ^7Li absorption feature that mimics the presence of ^6Li at a level comparable to the hitherto published values. This opens the possibility that only an upper limit on ^6Li/^7Li has thus far been derived. The second method confirms these findings. Conclusions: From this work, it appears that a systematic reappraisal of former determinations of ^6Li abundances in halo stars is warranted. Based on observations carried out at the European Southern Observatory (ESO), under prog. ID 75.D-0600. Tables 1-3, and additional references are only available in electronic form at http://www.aanda.org

  5. Systematics of the breakup probability function for 6Li and 7Li projectiles

    NASA Astrophysics Data System (ADS)

    Capurro, O. A.; Pacheco, A. J.; Arazi, A.; Carnelli, P. F. F.; Fernández Niello, J. O.; Martinez Heimann, D.

    2016-01-01

    Experimental non-capture breakup cross sections can be used to determine the probability of projectile and ejectile fragmentation in nuclear reactions involving weakly bound nuclei. Recently, the probability of both type of dissociations has been analyzed in nuclear reactions involving 9Be projectiles onto various heavy targets at sub-barrier energies. In the present work we extend this kind of systematic analysis to the case of 6Li and 7Li projectiles with the purpose of investigating general features of projectile-like breakup probabilities for reactions induced by stable weakly bound nuclei. For that purpose we have obtained the probabilities of projectile and ejectile breakup for a large number of systems, starting from a compilation of the corresponding reported non-capture breakup cross sections. We parametrize the results in accordance with the previous studies for the case of beryllium projectiles, and we discuss their systematic behavior as a function of the projectile, the target mass and the reaction Q-value.

  6. Quantum effects in the case of (6)Li+ and (7)Li+ ions evolving in a neutral (6)Li gas at a wide range of temperatures.

    PubMed

    Bouchelaghem, F; Bouledroua, M

    2014-02-01

    This work deals with the quantum-mechanical calculation of the temperature-dependent mobility of ionic lithium atoms diffusing in their parent gas. The computation of the quantal phase shifts in connection with the gerade and ungerade potential-energy curves, through which Li(+) approaches Li(2s), leads to the computation of the charge-transfer and diffusion cross sections. The behavior of the coefficients of diffusion and mobility with temperature is also examined. Throughout this work, the isotopic effects in the (6)Li(+)-(6)Li and (7)Li(+)-(6)Li collisions are emphasized. PMID:24326775

  7. Fast neutron measurements with 7Li and 6Li enriched CLYC scintillators

    NASA Astrophysics Data System (ADS)

    Giaz, A.; Blasi, N.; Boiano, C.; Brambilla, S.; Camera, F.; Cattadori, C.; Ceruti, S.; Gramegna, F.; Marchi, T.; Mattei, I.; Mentana, A.; Million, B.; Pellegri, L.; Rebai, M.; Riboldi, S.; Salamida, F.; Tardocchi, M.

    2016-07-01

    The recently developed Cs2LiYCl6:Ce (CLYC) crystals are interesting scintillation detectors not only for their gamma energy resolution (<5% at 662 keV) but also for their capability to identify and measure the energy of both gamma rays and fast/thermal neutrons. The thermal neutrons were detected by the 6Li(n,α)t reaction while for the fast neutrons the 35Cl(n,p)35S and 35Cl(n,α)32P neutron-capture reactions were exploited. The energy of the outgoing proton or α particle scales linearly with the incident neutron energy. The kinetic energy of the fast neutrons can be measured using both the Time Of Flight (TOF) technique and using the CLYC energy signal. In this work, the response to monochromatic fast neutrons (1.9-3.8 MeV) of two CLYC 1″×1″ crystals was measured using both the TOF and the energy signal. The observables were combined to identify fast neutrons, to subtract the thermal neutron background and to identify different fast neutron-capture reactions on 35Cl, in other words to understand if the detected particle is an α or a proton. We performed a dedicated measurement at the CN accelerator facility of the INFN Legnaro National Laboratories (Italy), where the fast neutrons were produced by impinging a proton beam (4.5, 5.0 and 5.5 MeV) on a 7LiF target. We tested a CLYC detector 6Li-enriched at about 95%, which is ideal for thermal neutron measurements, in parallel with another CLYC detector 7Li-enriched at more than 99%, which is suitable for fast neutron measurements.

  8. Asymptotic and near-target direct breakup of 6Li and 7Li

    NASA Astrophysics Data System (ADS)

    Kalkal, Sunil; Simpson, E. C.; Luong, D. H.; Cook, K. J.; Dasgupta, M.; Hinde, D. J.; Carter, I. P.; Jeung, D. Y.; Mohanto, G.; Palshetkar, C. S.; Prasad, E.; Rafferty, D. C.; Simenel, C.; Vo-Phuoc, K.; Williams, E.; Gasques, L. R.; Gomes, P. R. S.; Linares, R.

    2016-04-01

    Background: Li,76 and 9Be are weakly bound against breakup into their cluster constituents. Breakup location is important for determining the role of breakup in above-barrier complete fusion suppression. Recent works have pointed out that experimental observables can be used to separate near-target and asymptotic breakup. Purpose: Our purpose is to distinguish near-target and asymptotic direct breakup of Li,76 in reactions with nuclei in different mass regions. Method: Charged particle coincidence measurements are carried out with pulsed Li,76 beams on 58Ni and 64Zn targets at sub-barrier energies and compared with previous measurements using 208Pb and 209Bi targets. A detector array providing a large angular coverage is used, along with time-of-flight information to give definitive particle identification of the direct breakup fragments. Results: In interactions of 6Li with 58Ni and 64Zn, direct breakup occurs only asymptotically far away from the target. However, in interactions with 208Pb and 209Bi, near-target breakup occurs in addition to asymptotic breakup. Direct breakup of 7Li into α -t is not observed in interactions with 58Ni and 64Zn. However, near-target dominated direct breakup was observed in measurements with 208Pb and 209Bi. A modified version of the Monte Carlo classical trajectory model code platypus, which explicitly takes into account lifetimes associated with unbound states, is used to simulate sub-barrier breakup reactions. Conclusions: Near-target breakup in interactions with Li,76 is an important mechanism only for the heavy targets 208Pb and 209Bi. There is insignificant near-target direct breakup of 6Li and no direct breakup of 7Li in reactions with 58Ni and 64Zn. Therefore, direct breakup is unlikely to suppress the above-barrier fusion cross section in reactions of Li,76 with 58Ni and 64Zn nuclei.

  9. An atomic beam of 6Li7Li for high resolution spectroscopy from matrix isolation sublimation

    NASA Astrophysics Data System (ADS)

    Oliveira, A. N.; Sacramento, R. L.; Silva, B. A.; Uhlmann, F. O.; Wolff, W.; Cesar, C. L.

    2016-07-01

    We propose the Matrix Isolation Sublimation (MlSu) technique for generating cold lithium atoms for the measurement of the 6Li - 7Li isotope shift in D1 and D2 transitions. The technique is capable of generating cold 6Li and 7Li beams at 4 K with forward velocity of 125 m/s. Using this beam we offer a distinguished source of lithium atoms for transitions measurements, adding a new possibility to make high resolution spectroscopy towards improving the experimental checks of the theory.

  10. An Ultra-high-Resolution Survey of the Interstellar 7Li/6Li Isotope Ratio in the Solar Neighborhood

    NASA Astrophysics Data System (ADS)

    Knauth, David C.; Federman, S. R.; Lambert, David L.

    2003-03-01

    In an effort to probe the extent of variations in the interstellar 7Li/6Li ratio seen previously, ultra-high-resolution (R~360,000), high signal-to-noise spectra of stars in the Perseus OB2 and Scorpius OB2 associations were obtained. These measurements confirm our earlier findings of an interstellar 7Li/6Li ratio of about 2 toward ο Per, the value predicted from models of Galactic cosmic-ray spallation reactions. Observations of other nearby stars yield limits consistent with the isotopic ratio of ~12 seen in carbonaceous chondrite meteorites. If this ratio originally represented the gas toward ο Per, then to decrease the original isotope ratio to its current value an order of magnitude increase in the Li abundance is expected, but it is not seen. The elemental K/Li ratio is not unusual, although Li and K are formed via different nucleosynthetic pathways. Several proposals to account for the low 7Li/6Li ratio were considered, but none seems satisfactory. Analysis of the Li and K abundances from our survey highlighted two sight lines where depletion effects are prevalent. There is evidence for enhanced depletion toward X Per, since both abundances are lower by a factor of 4 when compared to other sight lines. Moreover, a smaller Li/H abundance is observed toward 20 Aql, but the K/H abundance is normal, suggesting enhanced Li depletion (relative to K) in this direction. Our results suggest that the 7Li/6Li ratio has not changed significantly during the last 4.5 billion years and that a ratio of ~12 represents most gas in the solar neighborhood. In addition, there appears to be a constant stellar contribution of 7Li, indicating that one or two processes dominate its production in the Galaxy.

  11. Ionic Pathways in Li13Si4 investigated by (6)Li and (7)Li solid state NMR experiments.

    PubMed

    Dupke, Sven; Langer, Thorsten; Winter, Florian; Pöttgen, Rainer; Winter, Martin; Eckert, Hellmut

    2015-02-01

    Local environments and dynamics of lithium ions in the binary lithium silicide Li13Si4 have been studied by (6)Li MAS-NMR, (7)Li spin-lattice relaxation time and site-resolved (7)Li 2D exchange NMR measurements as a function of mixing time. Variable temperature experiments result in distinct differences in activation energies characterizing the transfer rates between the different lithium sites. Based on this information, a comprehensive picture of the preferred ionic transfer pathways in this silicide has been developed. With respect to local mobility, the results of the present study suggests the ordering Li6/Li7>Li5>Li1>Li4 >Li2/Li3. Mobility within the z=0.5 plane is distinctly higher than within the z=0 plane, and the ionic transfer between the planes is most facile via Li1/Li5 exchange. The lithium ionic mobility can be rationalized on the basis of the type of the coordinating silicide anions and the lithium-lithium distances within the structure. Lithium ions strongly interacting with the isolated Si(4-) anions have distinctly lower mobility than those the coordination of which is dominated by Si2(6-) dumbbells. PMID:25524128

  12. On the hyperfine structures of the ground state(s) in the 6Li and 7Li atoms

    NASA Astrophysics Data System (ADS)

    Frolov, A. M.

    2016-06-01

    Hyperfine structure of the ground 22 S-states of the three-electron atoms and ions is investigated. By using our recent numerical values for the doublet electron density at the atomic nucleus we determine the hyperfine structure of the ground (doublet) 22 S-state(s) in the 6Li and 7Li atoms. Our predicted values (228.2058MHz and 803.5581MHz, respectivly) agree well with the experimental values 228.20528(8) MHz (6Li) and 803.50404(48) MHz (7Li (R.G. Schlecht and D.W. McColm, Phys. Rev. 142, 11 (1966))). The hyperfine structures of a number of lithium isotopes with short life-times, including 8Li, 9Li and 11Li atoms are also predicted. The same method is used to obtain the hyperfine structures of the three-electron 7Be+ and 9Be+ ions in their ground 22 S-states. Finally, we conclude that our approach can be generalized to describe the hyperfine structure in the triplet n 3 S-states of the four-electron atoms and ions.

  13. A New 6Li Detection in a Halo Subgiant, and Constraints for the Depletion of the Big Bang 7Li Abundance

    NASA Astrophysics Data System (ADS)

    Deliyannis, C. P.; Ryan, S. G.

    2000-05-01

    We present measurements of the 6Li/7Li isotope ratio in ten metal-poor stars derived from very high resolution (100,000) and S/N (300-800/pixel) McDonald 2.7-meter coude spectra, including two possible 6Li detections. We present specific new evidence that we have indeed detected the 6Li absorption feature, and not a convective asymmetry of the 7Li feature. One of our detections argues in favor of a protostellar (and not a surface-spallated) origin for this 6Li. We find that 6Li has either not evolved strongly with metallicity, in contrast to what is observed for Be and B, or else concurrent 6Li production is matched by stellar depletion. While such fine-tuning seems unlikely, no models can explain the origin of 6Li without such depletion. In the context of the observed 9Be/7Li depletion correlation and its slow-mixing explanation, taking our data at face value implies that the Big Bang 7Li abundance is no more than 0.2-0.3 dex higher than the values observed in the halo Li plateau.

  14. Threshold behavior of interaction potential for the system 7Li + 64Ni: Comparison with 6Li + 64Ni

    NASA Astrophysics Data System (ADS)

    Shaikh, Md. Moin; Das, Mili; Roy, Subinit; Sinha, M.; Pradhan, M. K.; Basu, P.; Datta, U.; Ramachandran, K.; Shrivastava, A.

    2016-09-01

    The elastic scattering angular distributions for the system 7Li + 64Ni were measured in the bombarding energy range of 12 MeV ≤Elab ≤ 26.4 MeV. A phenomenological optical model analysis was performed for the measured data. The strengths of the fitted potential components at the surface were estimated to extract their variation with energy. Further analyses of the measured angular distributions were performed with a hybrid potential composed of a renormalized folded real and a phenomenological imaginary potential. Both the model potentials predict similar energy dependent behavior for the effective interaction potential around the barrier. Unlike the heavy targets, 7Li + 64Ni does not show a normal threshold behavior. It also does not clearly exhibit a behavior similar to 6Li + 64Ni. The real potential for 7Li + 64Ni does not exhibit any significant energy dependence and the imaginary potential strength remains almost independent of energy above the Coulomb barrier (∼ 14 MeV). However, at energies below the barrier, a sudden drop in the imaginary potential strength is observed.

  15. New high S/N observations of the (6Li) /(7) Li blend in HD 84937 and two other metal-poor stars

    NASA Astrophysics Data System (ADS)

    Cayrel, R.; Spite, M.; Spite, F.; Vangioni-Flam, E.; Cassé, M.; Audouze, J.

    1999-03-01

    High signal to noise ratio spectra have been obtained with the GECKO spectrograph at CFHT, at a spectral resolution of 100 000, for three metal-poor stars in order to obtain more accurate abundances of the very fragile element (6) Li. For two newly observed stars, BD +42 2667 and BD +36 2165 it appears that the first may have a detectable amount of (6) Li, whereas no (6) Li is found in the second one. The S/N ratio of only a few hundreds obtained for these two faint stars preclude however a firm conclusion. For the third star, the well known object HD84937, a very high S/N of 650 per pixel (over 1000 per resolved spectral element) was obtained, yielding greatly improved accuracy over previous determinations. A value of (6) Li / (7) Li = 0.052 +/- 0.019 (one sigma) is obtained. We also conclude that the no- (6) Li assumption is ruled out at the 95 per cent level, even in the most permissive case, when a variation of all the other free parameters (wavelength zero-point, continuum location, macroturbulent broadening, abundance of (7) Li) is allowed. The possibility that the (6) Li feature is an artifact due to a once suspected binarity of HD 84937 is discussed, with the conclusion that this assumption is ruled out by the extant data on the radial velocity of the object. The (6) Li abundance is compared with recent models of formation of the light elements Li, Be and B. This comparison shows that (6) Li is either undepleted, or only moderately depleted in HD 84937, from its initial value. Under the assumption that the atmospheric depletion of (6) Li and (7) Li in stars is by slow mixing with hot layers (underneath the convective zone), in which these elements can burn, we conclude that the depletion of (7) Li by this mechanism in HD 84937 is less than 0.1 dex. This new upper limit to the efficiency of the depletion of (7) Li by slow mixing burning, in a star located on the Spite plateau, leads to a more secure estimation of the primordial abundance of (7) Li. However

  16. Trojan horse particle invariance studied with the {sup 6}Li(d,{alpha}){sup 4}He and {sup 7}Li(p,{alpha}){sup 4}He reactions

    SciTech Connect

    Pizzone, R. G.; Spitaleri, C.; Lamia, L.; Cherubini, S.; La Cognata, M.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Bertulani, C.; Mukhamedzhanov, A.; Blokhintsev, L.; Burjan, V.; Hons, Z.; Kroha, V.; Mrazek, J.; Piskor, S.; Kiss, G. G.; Li, C.; Tumino, A.

    2011-04-15

    The Trojan horse nucleus invariance for the binary reaction cross section extracted from the Trojan horse reaction was tested using the quasifree {sup 3}He({sup 6}Li,{alpha}{alpha})H and {sup 3}He({sup 7}Li,{alpha}{alpha}){sup 2}H reactions. The cross sections for the {sup 6}Li(d,{alpha}){sup 4}He and {sup 7}Li(p,{alpha}){sup 4}He binary processes were extracted in the framework of the plane wave approximation. They are compared with direct behaviors as well as with cross sections extracted from previous indirect investigations of the same binary reactions using deuteron as the Trojan horse nucleus instead of {sup 3}He. The very good agreement confirms the applicability of the plane wave approximation which suggests the independence of the binary indirect cross section on the chosen Trojan horse nucleus, at least for the investigated cases.

  17. Width measurement of the {sup 6}Li{sub 4.31} state by the {sup 7}Li({sup 3}He, {alpha}d){alpha} reaction

    SciTech Connect

    Arena, N.; Cavallaro, S.; D`Agostino, P.; D`Arrigo, A.; Fazio, G.; Giardina, G.; Sacchi, M.; Eremin, N.V.; Klochko, T.U.; Lombardi, M.

    1995-02-01

    The J{sup {pi}} = 2{sup +}, T = 0 {sup 6}Li state at E{sub x} = 4.31 MeV was populated by the {sup 7}Li({sup 3}He, {alpha}d){alpha} reaction performed at 4, 5, and 6 MeV {sup 3}He incident energies. The values obtained for {Gamma}({sup 6}Li{sub 4.31}) were compared with those deduced from the above reaction at E({sup 3}He) = 2.5 MeV. In contrast to the findings of other authors, no dependence of the above parameter on incident energy was observed. 23 refs., 1 fig., 2 tabs.

  18. Test of level density models from reactions of {sup 6}Li on {sup 58}Fe and {sup 7}Li on {sup 57}Fe

    SciTech Connect

    Oginni, B. M.; Grimes, S. M.; Voinov, A. V.; Adekola, A. S.; Brune, C. R.; Carter, D. E.; Heinen, Z.; Jacobs, D.; Massey, T. N.; O'Donnell, J. E.; Schiller, A.

    2009-09-15

    The reactions of {sup 6}Li on {sup 58}Fe and {sup 7}Li on {sup 57}Fe have been studied at 15 MeV beam energy. These two reactions produce the same compound nucleus, {sup 64}Cu. The charged particle spectra were measured at backward angles. The data obtained have been compared with Hauser-Feshbach model calculations. The level density parameters of {sup 63}Ni and {sup 60}Co have been obtained from the particle evaporation spectra. We also find contributions from the break up of the lithium projectiles to the low energy region of the {alpha} spectra.

  19. Metals, a Plasma of the Poor Man: Electron Screening in 7Li(p,{alpha}){alpha} and 6Li(p,{alpha})3He for Different Environments

    SciTech Connect

    Rolfs, C.

    2006-05-24

    The electron screening in the 7Li(p,{alpha}){alpha} reaction has been studied at Ep = 30 to 100 keV for different environments: Li2WO4 insulator, Li metal, and PdLi alloys. For the insulator a screening potential energy of Ue = 185{+-}150 eV was observed, consistent with previous work and the atomic adiabatic limit. However, for the Li metal and the PdLi alloys we find large values of Ue = 1280{+-}60 and 3790{+-}330 eV, respectively: the values can be explained by the plasma model of Debye applied to the quasi-free metallic electrons in these samples. Similar results have been found for the 6Li(p,{alpha})3He reaction supporting the hypothesis of the isotopic independence of the electron screening effect. The data together with previous studies of d(d,p)t and 9Be(p,{alpha})6Li in metals verify the Debye model scaling Ue {proportional_to} Zt (charge number of target)

  20. The cosmological 7Li problem from a nuclear physics perspective

    NASA Astrophysics Data System (ADS)

    Broggini, C.; Canton, L.; Fiorentini, G.; Villante, F. L.

    2012-06-01

    The primordial abundance of 7Li as predicted by Big Bang Nucleosynthesis (BBN) is more than a factor 2 larger than what has been observed in metal-poor halo stars. Herein, we analyze the possibility that this discrepancy originates from incorrect assumptions about the nuclear reaction cross sections relevant for BBN. To do this, we introduce an efficient method to calculate the changes in the 7Li abundance produced by arbitrary (temperature dependent) modifications of the nuclear reaction rates. Then, considering that 7Li is mainly produced from 7Be via the electron capture process 7Be+e- → 7Li+νe, we assess the impact of the various channels of 7Be destruction. Differently from previous analysis, we consider the role of unknown resonances by using a complete formalism which takes into account the effect of Coulomb and centrifugal barrier penetration and that does not rely on the use of the narrow-resonance approximation. As a result of this, the possibility of a nuclear physics solution to the 7Li problem is significantly suppressed. Given the present experimental and theoretical constraints, it is unlikely that the 7Be+n destruction rate is underestimated by the 2.5 factor required to solve the problem. We exclude, moreover, that resonant destruction in the channels 7Be+t and 7Be+3He can explain the 7Li puzzle. New unknown resonances in 7Be+d and 7Be+α could potentially produce significant effects. Recent experimental results have ruled out such a possibility for 7Be+d. On the other hand, for the 7Be+α channel very favorable conditions are required. The possible existence of a partially suitable resonant level in 11C is studied in the framework of a coupled-channel model and the possibility of a direct measurement is considered.

  1. Microscopic Structure of Contact Ion Pairs in Concentrated LiCl- and LiClO4-Tetrahydrofuran Solutions Studied by Low-Frequency Isotropic Raman Scattering and Neutron Diffraction with (6)Li/(7)Li Isotopic Substitution Methods.

    PubMed

    Kameda, Yasuo; Ebina, Saki; Amo, Yuko; Usuki, Takeshi; Otomo, Toshiya

    2016-05-26

    Low-frequency isotropic Raman scattering and time-of-flight neutron diffraction measurements were carried out for (6)Li/(7)Li and H/D isotopically substituted *LiCl- and *LiClO4-tetrahydrofuran (*THF) solutions in order to obtain microscopic insight into solvated Li(+), Li(+)···Cl(-) and Li(+)···ClO4(-) contact ion pairs formed in concentrated THF solutions. Symmetrical stretching vibrational mode of solvated Li(+) in LiCl and LiClO4 solutions was observed at ν = 181-184 and 140 cm(-1), respectively. The stretching vibrational mode of Li(+)···Cl(-) and Li(+)···ClO4(-) solvated contact ion pairs formed in 4 mol % (6)LiCl-THF-h8 and (7)LiCl-THF-h8 solutions was found at ν = 469 and 435 cm(-1), respectively. Detailed structural properties of solvated Li(+) and the contact ion pairs were derived from the least-squares fitting analyses of the first-order difference function, ΔLi(Q), obtained from neutron diffraction measurements on (6)Li/(7)Li isotopically substituted THF-d8 solutions. It has been revealed that Li(+) takes 4-fold coordination in the average local structure of Li(+)X(-)(THF)3, X = Cl and ClO4. The nearest neighbor Li(+)···O(THF) distance was determined to be 2.21 ± 0.01 Å and 2.07 ± 0.01 Å for 4 mol % *LiCl- and 10 mol % *LiClO4-THF-d8 solutions, respectively. The Li(+)···anion distances for Li(+)···Cl(-) and Li(+)···O(ClO4(-)) contact ion pairs were determined to be 2.4 ± 0.1 Å and 2.19 ± 0.01 Å, respectively. The nearest neighbor Li(+)···THF interaction is significantly modified by the anion in the first solvation shell. PMID:27157529

  2. Cross sections for neutron-producing reactions induced by 14. 1 MeV neutrons incident on /sup 6/Li, /sup 7/Li, /sup 10/B, /sup 11/B, and carbon

    SciTech Connect

    Drosg, M.; Lisowski, P.W.; Drake, D.M.; Hardekopf, R.A.; Muellner, M.

    1988-10-01

    Using the time-of-flight technique, we have measured neutron emission spectra for /sup 6/Li, /sup 7/Li, /sup 10/B, /sup 11/B and carbon at an incident neutron energy of 14.1 MeV and at 10 angles between 30/degree/ and 143/degree/. Double differential cross sections and their integrated values have been extracted and are presented in tables and graphs. The nonelastic portion of the neutron emission spectra is noticeably higher than expected which may be due to uncertainties in the input library (ENDF/B-IV) used in the Monte Carlo correction for multiple scattering. In particular, the library for /sup 11/B appears to be very unrealistic with an integrated elastic cross section which should be higher by 50%. 20 refs., 1 fig., 12 tabs.

  3. TU-F-BRE-07: In Vivo Neutron Detection in Patients Undergoing Stereotactic Ablative Radiotherapy (SABR) for Primary Kidney Cancer Using 6Li and 7Li Enriched TLD Pairs

    SciTech Connect

    Lonski, P; Kron, T; Franich, R; Keehan, S; Siva, S; Taylor, M

    2014-06-15

    Purpose: Stereotactic ablative radiotherapy (SABR) for primary kidney cancer often involves the use of high-energy photons combined with a large number of monitor units. While important for risk assessment, the additional neutron dose to untargeted healthy tissue is not accounted for in treatment planning. This work aims to detect out-of-field neutrons in vivo for patients undergoing SABR with high-energy (>10 MV) photons and provides preliminary estimates of neutron effective dose. Methods: 3 variations of high-sensitivity LiF:Mg,Cu,P thermoluminescent dosimeter (TLD) material, each with varying {sup 6}Li / {sup 7}Li concentrations, were used in custom-made Perspex holders for in vivo measurements. The variation in cross section for thermal neutrons between Li isotopes was exploited to distinguish neutron from photon signal. Measurements were made out-of-field for 7 patients, each undergoing 3D-conformal SABR treatment for primary kidney cancer on a Varian 21iX linear accelerator. Results: In vivo measurements show increased signal for the {sup 6}Li enriched material for patients treated with 18 MV photons. Measurements on one SABR patient treated using only 6 MV showed no difference between the 3 TLD materials. The out-of-field photon signal decreased exponentially with distance from the treatment field. The neutron signal, taken as the difference between {sup 6}Li enriched and {sup 7}Li enriched TLD response, remains almost constant up to 50 cm from the beam central axis. Estimates of neutron effective dose from preliminary TLD calibration suggest between 10 and 30 mSv per 1000 MU delivered at 18 MV for the 7 patients. Conclusion: TLD was proven to be a useful tool for the purpose of in vivo neutron detection at out-of-field locations. Further work is required to understand the relationship between TL signal and neutron dose. Dose estimates based on preliminary TLD calibration in a neutron beam suggest the additional neutron dose was <30 mSv per 1000 MU at 18 MV.

  4. Nuclear structure constrains on resonant energies: A solution of the cosmological 7Li problem?

    NASA Astrophysics Data System (ADS)

    Civitarese, O.; Mosquera, M. E.

    2013-01-01

    In this work, we study the cosmological 7Li problem from a nuclear structure point of view, by including resonances in the reactions which populate beryllium. The calculation of primordial abundances is performed by solving the balance equations semi-analytically. It is found that the primordial abundance of lithium is indeed reduced, as a consequence of the presence of resonant channels in the relevant cross sections. We set limits on the resonant energy for each reaction relevant for the chain leading to 7Li, by performing a statistical analysis of the available observational data.

  5. Contributions of excited {sup 6}Li and {sup 7}Li nuclei to the production of {sup 4}He+{sup 2}H and {sup 4}He+{sup 3}H systems in {sup 16}O{sub p} collisions at a momentum of 3.25 GeV/c per nucleon

    SciTech Connect

    Olimov, K.; Glagolev, V. V.; Gulamov, K. G.; Lutpullaev, S. L.; Kurbanov, A. R.; Olimov, A. K.; Petrov, V. I.; Yuldashev, A. A.

    2013-07-15

    New experimental data on the cross sections for the yield of excited {sup 6}Li* and {sup 7}Li* nuclei and on their contributions to the production of {sup 4}He + {sup 2}H and {sup 4}He+{sup 3}H light dinuclear systems in {sup 16}O{sub p} collisions at a momentumof 3.25 A GeV/c per nucleon are presented.

  6. The cosmological {sup 7}Li problem from a nuclear physics perspective

    SciTech Connect

    Broggini, C.; Canton, L.; Fiorentini, G.; Villante, F.L. E-mail: luciano.canton@pd.infn.it E-mail: francesco.villante@lngs.infn.it

    2012-06-01

    The primordial abundance of {sup 7}Li as predicted by Big Bang Nucleosynthesis (BBN) is more than a factor 2 larger than what has been observed in metal-poor halo stars. Herein, we analyze the possibility that this discrepancy originates from incorrect assumptions about the nuclear reaction cross sections relevant for BBN. To do this, we introduce an efficient method to calculate the changes in the {sup 7}Li abundance produced by arbitrary (temperature dependent) modifications of the nuclear reaction rates. Then, considering that {sup 7}Li is mainly produced from {sup 7}Be via the electron capture process {sup 7}Be+e{sup −} → {sup 7}Li+ν{sub e}, we assess the impact of the various channels of {sup 7}Be destruction. Differently from previous analysis, we consider the role of unknown resonances by using a complete formalism which takes into account the effect of Coulomb and centrifugal barrier penetration and that does not rely on the use of the narrow-resonance approximation. As a result of this, the possibility of a nuclear physics solution to the {sup 7}Li problem is significantly suppressed. Given the present experimental and theoretical constraints, it is unlikely that the {sup 7}Be+n destruction rate is underestimated by the 2.5 factor required to solve the problem. We exclude, moreover, that resonant destruction in the channels {sup 7}Be+t and {sup 7}Be+{sup 3}He can explain the {sup 7}Li puzzle. New unknown resonances in {sup 7}Be+d and {sup 7}Be+α could potentially produce significant effects. Recent experimental results have ruled out such a possibility for {sup 7}Be+d. On the other hand, for the {sup 7}Be+α channel very favorable conditions are required. The possible existence of a partially suitable resonant level in {sup 11}C is studied in the framework of a coupled-channel model and the possibility of a direct measurement is considered.

  7. {sup 7}Li(p,n) NUCLEAR DATA LIBRARY FOR INCIDENT PROTON ENERGIES TO 150 MEV

    SciTech Connect

    S. MASHNIK; ET AL

    2000-11-01

    Researchers at Los Alamos National Laboratory are considering the possibility of using the Low Energy Demonstration Accelerator (LEDA), constructed at LANSCE for the Accelerator Production of Tritium program (APT), as a neutron source. Evaluated nuclear data are needed for the p+{sup 7}Li reaction, to predict neutron production from thin and thick lithium targets. In this report we describe evaluation methods that make use of experimental data, and nuclear model calculations, to develop an ENDF-formatted data library for incident protons with energies up to 150 MeV. The important {sup 7}Li(p,n{sub 0}) and {sup 7}Li(p,n{sub 1}) reactions are evaluated from the experimental data, with their angular distributions represented using Lengendre polynomial expansions. The decay of the remaining reaction flux is estimated from GNASH nuclear model calculations. This leads to the emission of lower-energy neutrons and other charged particles and gamma-rays from preequilibrium and compound nucleus decay processes. The evaluated ENDF-data are described in detail, and illustrated in numerous figures. We also illustrate the use of these data in a representative application by a radiation transport simulation with the code MCNPX.

  8. Electron affinity of (7)Li calculated with the inclusion of nuclear motion and relativistic corrections.

    PubMed

    Stanke, Monika; Kedziera, Dariusz; Bubin, Sergiy; Adamowicz, Ludwik

    2007-10-01

    Explicitly correlated Gaussian functions have been used to perform very accurate variational calculations for the ground states of (7)Li and (7)Li(-). The nuclear motion has been explicitly included in the calculations (i.e., they have been done without assuming the Born-Oppenheimer (BO) approximation). An approach based on the analytical energy gradient calculated with respect to the Gaussian exponential parameters was employed. This led to a noticeable improvement of the previously determined variational upper bound to the nonrelativistic energy of Li(-). The Li energy obtained in the calculations matches those of the most accurate results obtained with Hylleraas functions. The finite-mass (non-BO) wave functions were used to calculate the alpha(2) relativistic corrections (alpha=1c). With those corrections and the alpha(3) and alpha(4) corrections taken from Pachucki and Komasa [J. Chem. Phys. 125, 204304 (2006)], the electron affinity (EA) of (7)Li was determined. It agrees very well with the most recent experimental EA. PMID:17919011

  9. 6Li from Solar Flares.

    PubMed

    Ramaty; Tatischeff; Thibaud; Kozlovsky; Mandzhavidze

    2000-05-10

    By introducing a hitherto ignored 6Li producing process, due to accelerated 3He reactions with 4He, we show that accelerated particle interactions in solar flares produce much more 6Li than 7Li. By normalizing our calculations to gamma-ray data, we demonstrate that the 6Li produced in solar flares, combined with photospheric 7Li, can account for the recently determined solar wind lithium isotopic ratio, obtained from measurements in lunar soil, provided that the bulk of the flare-produced lithium is evacuated by the solar wind. Further research in this area could provide unique information on a variety of problems, including solar atmospheric transport and mixing, solar convection and the lithium depletion issue, and solar wind and solar particle acceleration. PMID:10813684

  10. {sup 7}Li-nuclear magnetic resonance observation of lithium insertion into mesocarbon microbeads

    SciTech Connect

    Tatsumi, K.; Akai, T.; Imamura, T.; Zaghib, K.; Iwashita, N.; Higuchi, S.; Sawada, Y.

    1996-06-01

    The stacking order of graphite layers in mesocarbon microbeads (MCMBs) heat-treated between 700 and 3,000 C was examined by analyses of X-ray diffraction measurements, and lithium insertion into the MCMBs has been observed using solid-state {sup 7}Li-nuclear magnetic resonance ({sup 7}Li-NMR) spectroscopy. In MCMBs heat-treated above 2,000 C, the fully lithiated MCMBs showed two bands at ca. 45 ppm (vs. KiCl) and ca. 27 ppm in their {sup 7}Li-NMR spectra. The profile of the band at 45 ppm was very close to that for the first-stage lithium graphite intercalation compound (Li-GIC), though the other band at 27 ppm could not be assigned to any phases of Li-GICs. From these results, it is suggested that the structures of the MCMBs heat-treated above 2,000 C for lithium insertion are classified as graphitic structure, which has the AB stacking order of graphite layers, and turbostatic structure with a random stacking sequence of graphite layers; the fully lithiated compositions of both structures were estimated as LiC{sub 6} and ca. Li{sub 0.2}C{sub 6}, respectively. Although MCMB heat-treated at 700 C gave a higher capacity than LiC{sub 6}, the line shift in the {sup 7}Li-NMR spectra indicated that lithium stored in the MCMB displayed an ionic character. Capacity change of the MCMBs during charge-discharge cycling up to 20 cycles and capacity loss at higher current densities (<200 mA/g) were also examined.

  11. Sympathetic cooling of {sup 6}Li atoms

    SciTech Connect

    van Abeelen, F.A.; Verhaar, B.J.; Moerdijk, A.J.

    1997-06-01

    We use recently measured cold photoassociation and two-photon data to extract the singlet and triplet accumulated radial phases of interacting ground-state lithium atoms. Using the resulting values we predict scattering lengths, Feshbach resonances, and exchange decay rates for cold collisions between {sup 7}Li and {sup 6}Li atoms that are of interest for the possibility of sympathetic cooling of {sup 6}Li and for the coexistence of the bosonic and fermionic quantum-degenerate phases of {sup 7}Li and {sup 6}Li. In addition, we calculate scattering lengths and exchange decay rates for cold collisions between identical lithium isotopes in different hyperfine states. These quantities are used to examine the possibilities of coexisting {sup 7}Li Bose condensates and of evaporatively cooling coexisting {sup 6}Li subsystems. {copyright} {ital 1997} {ital The American Physical Society}

  12. Galactic evolution of 7Li

    NASA Astrophysics Data System (ADS)

    Matteucci, Francesca

    2010-04-01

    Lithium represents a key element in cosmology, as it is one of the few nuclei synthesized during the Big Bang. The primordial abundance of 7Li allows us to impose constraints on the primordial nucleosynthesis and on the baryon density of the universe. However, 7Li is not only produced during the Big Bang but also during galactic evolution: measures of stellar Li in our Galaxy suggest an almost constant Li abundance (the so-called Spite plateau) at low metallicities and a subsequent increase in the disk stars, leading to a Li abundance in Population I stars higher by a factor of ten than in Population II stars. This means that there must exist several possible stellar sources of 7Li: asymptotic giant branch stars, supernovae, novae, red giant stars. 7Li is also partly produced in spallation processes while 6Li is entirely produced by such processes. All of these sources have been included in galactic chemical evolution models and constraints have been derived on the primordial 7Li and its evolution, as well on stellar models. I will review these models and their results and what we have learned about 7Li evolution. Some still open problems, such as the disagreement between the primordial 7Li abundance as derived by WMAP and as measured in Population II stars, and the uncertainties about the main sources of stellar 7Li will be discussed.

  13. Neutron Energy Spectra and Yields from the 7Li(p,n) Reaction for Nuclear Astrophysics

    NASA Astrophysics Data System (ADS)

    Tessler, M.; Friedman, M.; Schmidt, S.; Shor, A.; Berkovits, D.; Cohen, D.; Feinberg, G.; Fiebiger, S.; Krása, A.; Paul, M.; Plag, R.; Plompen, A.; Reifarth, R.

    2016-01-01

    Neutrons produced by the 7Li(p, n)7Be reaction close to threshold are widely used to measure the cross section of s-process nucleosynthesis reactions. While experiments have been performed so far with Van de Graaff accelerators, the use of RF accelerators with higher intensities is planned to enable investigations on radioactive isotopes. In parallel, high-power Li targets for the production of high-intensity neutrons at stellar energies are developed at Goethe University (Frankfurt, Germany) and SARAF (Soreq NRC, Israel). However, such setups pose severe challenges for the measurement of the proton beam intensity or the neutron fluence. In order to develop appropriate methods, we studied in detail the neutron energy distribution and intensity produced by the thick-target 7Li(p,n)7Be reaction and compared them to state-of- the-art simulation codes. Measurements were performed with the bunched and chopped proton beam at the Van de Graaff facility of the Institute for Reference Materials and Measurements (IRMM) using the time-of-flight (TOF) technique with thin (1/8") and thick (1") detectors. The importance of detailed simulations of the detector structure and geometry for the conversion of TOF to a neutron energy is stressed. The measured neutron spectra are consistent with those previously reported and agree well with Monte Carlo simulations that include experimentally determined 7Li(p,n) cross sections, two-body kinematics and proton energy loss in the Li-target.

  14. Analysis of 6Li Scattering at 240 MeV Using Different Nuclear Potentials

    NASA Astrophysics Data System (ADS)

    Al-Ghamdi, A. H.; Ibraheem, Awad A.

    2016-06-01

    Angular distributions of the elastic and inelastic scattering cross sections of 6Li projectile on different heavy ion target nuclei including the 24Mg, 28Si, 48Ca, 58Ni, 90Zr, and 116Sn at energy of 240 MeV have been analyzed by using two different folded potentials based on the CDM3Y6 and São Paulo potentials for the real part of the optical potential, while the imaginary parts have a phenomenological Woods-Saxon shape. Coupled channel calculations for the low-lying 2+ state at 1.369, 1.779, 3.832, 1.454, 2.186, and 1.29 MeV for 24Mg, 28Si, 48Ca, 58Ni, 90Zr, and 116Sn, respectively, have been carried out, and the best fit values for B(EL) with the above models have been extracted by fitting the inelastic scattering cross section and compared with the values of previous works. The total reaction cross section and real and imaginary volume integrals have also been investigated.

  15. Target structure independent 7Li elastic scattering at lowmomentum transfers

    SciTech Connect

    Momotyuk, O.A.; Keeley, N.; Kemper, K.W.; Roeder, B.T.; Crisp,A.M.; Cluff, W.; Schmidt, B.G.; Wiedeking, M.; Marechal, F.; Rusek, K.; Mezhevych, S.Yu.; Liendo, J.

    2006-07-20

    Analyzing powers and cross sections for the elastic scattering of polarized 7Li by targets of 6Li, 7Li and 12C are shown to depend only on the properties of the projectile for momentum transfers of less than 1.0 fm-1. The result of a detailed analysis of the experimental data within the framework of the coupled channels model with ground state reorientation and transitions to the excited states of the projectile and targets included in the coupling schemes are presented. This work suggests that nuclear properties of weakly-bound nuclei can be tested by elastic scattering experiments, independent of the target used, if data are acquired for momentum transfers less than {approx}1.0 fm-1.

  16. The Application of U-Np Fuel and {sup 6}Li Burnable Poison for Space Reactors

    SciTech Connect

    Nikitin, Konstantin L.; Saito, Masaki; Artisyuk, Vladimir V.

    2003-11-15

    The possible application of {sup 6}Li as a burnable poison and U-Np nitride as a fuel for space nuclear reactors has been studied. The analysis was performed for an infinite lattice with a leakage in the form of buckling and (U-Np)N fuel with 20% uranium enrichment. The combination of {sup 7}Li as a coolant and {sup 6}Li as a burnable poison results in a favorable criticality behavior during burnup. The parameters taken into consideration include the different fuel and coolant compositions, the form of absorber material, and the various absorber mass and concentrations. It was found that absorption properties of {sup 6}Li allow reaching the burnup value up to 67 GWd/tHM while reactivity swing is comparable with {beta}{sub eff}. The corresponding reactor lifetime is {approx}10 to 30 yr.

  17. First direct measurement of the 2H(α,γ)6Li cross section at big bang energies and the primordial lithium problem.

    PubMed

    Anders, M; Trezzi, D; Menegazzo, R; Aliotta, M; Bellini, A; Bemmerer, D; Broggini, C; Caciolli, A; Corvisiero, P; Costantini, H; Davinson, T; Elekes, Z; Erhard, M; Formicola, A; Fülöp, Zs; Gervino, G; Guglielmetti, A; Gustavino, C; Gyürky, Gy; Junker, M; Lemut, A; Marta, M; Mazzocchi, C; Prati, P; Rossi Alvarez, C; Scott, D A; Somorjai, E; Straniero, O; Szücs, T

    2014-07-25

    Recent observations of (6)Li in metal poor stars suggest a large production of this isotope during big bang nucleosynthesis (BBN). In standard BBN calculations, the (2)H(α,γ)(6)Li reaction dominates (6)Li production. This reaction has never been measured inside the BBN energy region because its cross section drops exponentially at low energy and because the electric dipole transition is strongly suppressed for the isoscalar particles (2)H and α at energies below the Coulomb barrier. Indirect measurements using the Coulomb dissociation of (6)Li only give upper limits owing to the dominance of nuclear breakup processes. Here, we report on the results of the first measurement of the (2)H(α,γ)(6)Li cross section at big bang energies. The experiment was performed deep underground at the LUNA 400 kV accelerator in Gran Sasso, Italy. The primordial (6)Li/(7)Li isotopic abundance ratio has been determined to be (1.5 ± 0.3) × 10(-5), from our experimental data and standard BBN theory. The much higher (6)Li/(7)Li values reported for halo stars will likely require a nonstandard physics explanation, as discussed in the literature. PMID:25105610

  18. Investigation of {sup 6}Li + {sup 13}C scattering and observation of a nuclear quasi-rainbow

    SciTech Connect

    Dem`yanova, A.S.; Ogloblin, A.A.; Osadchii, O.Ya.

    1994-11-01

    Differential cross sections for elastic scattering of {sup 6}Li ions by {sup 13}C at E{sub c.m.s.} = 26 MeV are measured in the range of c.m.s. angles 14 - 163{degrees} at the Kurchatov Institute cyclotron in both direct and inverse kinematics by the {Delta}E-E telescope technique. A broad maximum in the angular distribution that is exhausted completely by the far component is observed at approximately 100{degrees}. The maximum is a typical manifestation of the nuclear rainbow and can be explained by the interference of waves arriving from the two branches of the deflection function (DF). However, for the potential chosen in this study, the DF has a singularity, and nuclear-rainbow scattering cannot formally take place because there is no finite scattering angle. The observed effect, which is referred to as a quasi-rainbow, demonstrates that the principal peculiarities of elastic scattering are the same in the two energy regions that are considered in a direct semiclassical approximation as corresponding to two fundamentally different phenomena: orbiting and the rainbow. 11 refs., 4 figs., 1 tab.

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

    SciTech Connect

    Rekalo, M.P.

    1986-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  1. 7Li relaxation time measurements at very low magnetic field by 1H dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Zeghib, Nadir; Grucker, Daniel

    2001-09-01

    Dynamic nuclear polarization (DNP) of water protons was used to measure the relaxation time of lithium at very low magnetic field as a demonstration of the use of DNP for nuclei less abundant than water protons. Lithium (Li+) was chosen because it is an efficient treatment for manic-depressive illness, with an unknown action mechanism. After having recalled the theoretical basis of a three-spin system comprising two nuclei - the water proton of the solvent, the dissolved Li+ ion and the free electron of a free radical - we have developed a transient solution in order to optimize potential biological applications of Li DNP. The three-spin model has allowed computation of all the parameters of the system - the longitudinal relaxation rate per unit of free radical concentration, the dipolar and scalar part of the coupling between the nuclei and the electron, and the maximum signal enhancement achievable for both proton and lithium spins. All these measurements have been obtained solely through the detection of the proton resonance.

  2. Estimation of the nuclear distortion in the Coulomb breakup of 6Li into α + d in the field of 208Pb ion

    NASA Astrophysics Data System (ADS)

    Irgaziev, B. F.

    2014-04-01

    In this article the results of the evaluation of the contribution of nuclear disintegration, based on the basis of diffraction theory in the 208Pb(6Li, αd)208Pb Coulomb breakup at an energy of 156 MeV is presented. Comparison of the results of the calculation with the experimental data of Kiener et al. [Phys. Rev. C 44, 2195 (1991)] gives evidence for the dominance of the Coulomb dissociation mechanism and contribution of nuclear distortion, but essentially smaller than the value reported byHammache et al. [Phys. Rev. C 82, 065803 (2010)] and Sümmerer [Prog. Part. Nucl. Phys. 66, 298 (2011)].

  3. Nuclear structure with accurate chiral perturbation theory nucleon-nucleon potential: Application to 6Li and 10B

    SciTech Connect

    Navratil, P; Caurier, E

    2003-10-14

    The authors calculate properties of A = 6 system using the accurate charge-dependent nucleon-nucleon (NN) potential at fourth order of chiral perturbation theory. By application of the ab initio no-core shell model (NCSM) and a variational calculation in the harmonic oscillator basis with basis size up to 16 {h_bar}{Omega} they obtain the {sup 6}Li binding energy of 28.5(5) MeV and a converged excitation spectrum. Also, they calculate properties of {sup 10}B using the same NN potential in a basis space of up to 8 {h_bar}{Omega}. The results are consistent with results obtained by standard accurate NN potentials and demonstrate a deficiency of Hamiltonians consisting of only two-body terms. At this order of chiral perturbation theory three-body terms appear. It is expected that inclusion of such terms in the Hamiltonian will improve agreement with experiment.

  4. Hyperpolarized (6)Li as a probe for hemoglobin oxygenation level.

    PubMed

    Balzan, Riccardo; Mishkovsky, Mor; Simonenko, Yana; van Heeswijk, Ruud B; Gruetter, Rolf; Eliav, Uzi; Navon, Gil; Comment, Arnaud

    2016-01-01

    Hyperpolarization by dissolution dynamic nuclear polarization (DNP) is a versatile technique to dramatically enhance the nuclear magnetic resonance (NMR) signal intensity of insensitive long-T1 nuclear spins such as (6)Li. The (6)Li longitudinal relaxation of lithium ions in aqueous solutions strongly depends on the concentration of paramagnetic species, even if they are present in minute amounts. We herein demonstrate that blood oxygenation can be readily detected by taking advantage of the (6)Li signal enhancement provided by dissolution DNP, together with the more than 10% decrease in (6)Li longitudinal relaxation as a consequence of the presence of paramagnetic deoxyhemoglobin. PMID:26265292

  5. Effects of projectile resonances on the total, Coulomb, and nuclear breakup cross sections in the 6Li+152Sm reaction

    NASA Astrophysics Data System (ADS)

    Mukeru, B.; Lekala, M. L.

    2016-08-01

    In this paper we analyze the effects of the projectile resonances on the total, Coulomb, and nuclear breakup cross sections as well as on the Coulomb-nuclear interferences at different arbitrary incident energies. It is found that these resonances have non-negligible effects on the total, Coulomb, and nuclear breakup cross sections. Qualitatively, they have no effects on the constructiveness or destructiveness of the Coulomb-nuclear interferences. Quantitatively, we obtained that these resonances increase by 7.38%, 7.58%, and 20.30% the integrated total, Coulomb, and nuclear breakup cross sections, respectively at Elab=35 MeV . This shows that the nuclear breakup cross sections are more affected by the effects of the projectile resonances than their total and Coulomb breakup counterparts. We also obtain that the effects of the resonances on the total, Coulomb, and nuclear breakup cross sections decrease as the incident energy increases.

  6. Search for solar axion emission from {sup 7}Li and D(p, γ){sup 3}He nuclear decays with the CAST γ-ray calorimeter

    SciTech Connect

    Andriamonje, S.; Aune, S.; Dafni, T.; Ferrer-Ribas, E.; Autiero, D.; Barth, K.; Davenport, M.; Lella, L. Di; Belov, A.; Beltrán, B.; Carmona, J.M.; Cebrián, S.; Bräuninger, H.; Englhauser, J.; Friedrich, P.; Collar, J.I.; Eleftheriadis, C.; Fanourakis, G.; Fischer, H.; Franz, J.; Collaboration: CAST collaboration; and others

    2010-03-01

    We present the results of a search for a high-energy axion emission signal from {sup 7}Li (0.478 MeV) and D(p, γ){sup 3}He (5.5 MeV) nuclear transitions using a low-background γ-ray calorimeter during Phase I of the CAST experiment. These so-called ''hadronic axions'' could provide a solution to the long-standing strong-CP problem and can be emitted from the solar core from nuclear M1 transitions. This is the first such search for high-energy pseudoscalar bosons with couplings to nucleons conducted using a helioscope approach. No excess signal above background was found.

  7. In situ7Li and 133Cs nuclear magnetic resonance investigations on the role of Cs+ additive in lithium-metal deposition process

    NASA Astrophysics Data System (ADS)

    Hu, Jian Zhi; Zhao, Zhenchao; Hu, Mary Y.; Feng, Ju; Deng, Xuchu; Chen, Xilin; Xu, Wu; Liu, Jun; Zhang, Ji-Guang

    2016-02-01

    Cesium ion (Cs+) has been reported to be an effective electrolyte additive to suppress Li dendrite growth which prevents the application of lithium (Li) metal as an anode for rechargeable Li batteries. In this work, we investigated the effect of Cs+ additive on Li depositions using quantitative in situ7Li and 133Cs nuclear magnetic resonance (NMR) with planar symmetric Li cells. It's found that the addition of Cs+ can significantly enhance both the formation of well aligned Li nanorods and reversibility of the Li electrode. In situ133Cs NMR directly confirms that Cs+ migrates to Li electrode to form a positively charged electrostatic shield during the charging process. Much more electrochemical "active" Li was found in Li films deposited with Cs+ additive, while more electrochemical "dead" and thicker Li rods were identified in Li films deposited without Cs+. Combining the in situ and the previous ex-situ results, a Li deposition model has been proposed to explain these observations.

  8. R-matrix analysis of reactions in the 9B compound system applied to the 7Li problem in BBN

    NASA Astrophysics Data System (ADS)

    Paris, M.; Hale, G.; Hayes-Sterbenz, A.; Jungman, G.

    2016-01-01

    Recent activity in solving the ‘lithium problem’ in big bang nucleosynthesis has focused on the role that putative resonances may play in resonance-enhanced destruction of 7Li. Particular attention has been paid to the reactions involving the 9B compound nuclear system, d+7Be → 9B. These reactions are analyzed via the multichannel, two-body unitary R-matrix method using the code EDA developed by Hale and collaborators. We employ much of the known elastic and reaction data, in a four-channel treatment. The data include elastic 3He +6Li differential cross sections from 0.7 to 2.0 MeV, integrated reaction cross sections for energies from 0.7 to 5.0 MeV for 6Li(3He,p)8Be* and from 0.4 to 5.0 MeV for the 6Li(3He,d)7Be reaction. Capture data have been added to an earlier analysis with integrated cross section measurements from 0.7 to 0.825 MeV for 6Li(3He,γ)9B. The resulting resonance parameters are compared with tabulated values, and previously unidentified resonances are noted. Our results show that there are no near d+7Be threshold resonances with widths that are 10’s of keV and reduce the likelihood that a resonance-enhanced mass-7 destruction mechanism, as suggested in recently published work, can explain the 7Li problem.

  9. Effect of breakup coupling on fusion for 6,7Li+24Mg systems

    NASA Astrophysics Data System (ADS)

    Pradhan, M. K.; Mukherjee, A.; Dasmahapatra, B.

    2015-01-01

    To study the effect of breakup coupling on fusion we have derived fusion cross sections in the framework of continuum discretised coupled channels (CDCC) method using the coupled channels code FRESCO for the systems 6,7Li+24Mg. The CDCC predicted fusion cross sections for the 7Li+24Mg system agree well with the experimental fusion data whereas for the 6Li+24Mg system the agreement is reasonable at below barrier energies. However, within the limits of the present work no definite conclusion could be obtained from the quality of agreement at above barrier energies for the 6Li+24Mg system.

  10. Neutron-induced background by an α-beam incident on a deuterium gas target and its implications for the study of the 2H(α,γ)6Li reaction at LUNA

    NASA Astrophysics Data System (ADS)

    Anders, M.; Trezzi, D.; Bellini, A.; Aliotta, M.; Bemmerer, D.; Broggini, C.; Caciolli, A.; Costantini, H.; Corvisiero, P.; Davinson, T.; Elekes, Z.; Erhard, M.; Formicola, A.; Fülöp, Zs.; Gervino, G.; Guglielmetti, A.; Gustavino, C.; Gyürky, Gy.; Junker, M.; Lemut, A.; Marta, M.; Mazzocchi, C.; Menegazzo, R.; Prati, P.; Rossi Alvarez, C.; Scott, D.; Somorjai, E.; Straniero, O.; Szücs, T.

    2013-02-01

    The production of the stable isotope 6Li in standard Big Bang nucleosynthesis has recently attracted much interest. Recent observations in metal-poor stars suggest that a cosmological 6Li plateau may exist. If true, this plateau would come in addition to the well-known Spite plateau of 7Li abundances and would point to a predominantly primordial origin of 6Li , contrary to the results of standard Big Bang nucleosynthesis calculations. Therefore, the nuclear physics underlying Big Bang 6Li production must be revisited. The main production channel for 6Li in the Big Bang is the 2H(α,γ)6Li reaction. The present work reports on neutron-induced effects in a high-purity germanium detector that were encountered in a new study of this reaction. In the experiment, an α-beam from the underground accelerator LUNA in Gran Sasso, Italy, and a windowless deuterium gas target are used. A low neutron flux is induced by energetic deuterons from elastic scattering and, subsequently, the 2H(d,n)3He reaction. Due to the ultra-low laboratory neutron background at LUNA, the effect of this weak flux of 2-3MeV neutrons on well-shielded high-purity germanium detectors has been studied in detail. Data have been taken at 280 and 400keV α-beam energy and for comparison also using an americium-beryllium neutron source.

  11. Investigation of Mechanical Activation on Li-N-H Systems Using 6Li Magic Angle Spinning Nuclear Magnetic Resonance at Ultra-High Field

    SciTech Connect

    Hu, Jian Zhi; Kwak, Ja Hun; Yang, Zhenguo; Osborn, William; Markmaitree, Tippawan; Shaw, Leonard D.

    2008-07-15

    Abstract The significantly enhanced spectral resolution in the 6Li MAS NMR spectra of Li-N-H systems at ultra-high field of 21.1 tesla is exploited, for the first time, to study the detailed electronic and chemical environmental changes associated with mechanical activation of Li-N-H system using high energy balling milling. Complementary to ultra-high field studies, the hydrogen discharge dynamics are investigated using variable temperature in situ 1H MAS NMR at 7.05 tesla field. The significantly enhanced spectral resolution using ultra-high filed of 21.1 tesla was demonstrated along with several major findings related to mechanical activation, including the upfield shift of the resonances in 6Li MAS spectra induced by ball milling, more efficient mechanical activation with ball milling at liquid nitrogen temperature than with ball milling at room temperature, and greatly enhanced hydrogen discharge exhibited by the liquid nitrogen ball milled samples.

  12. Medium Modification of α Cluster Size in 6Li

    NASA Astrophysics Data System (ADS)

    Yamagata, T.; Akimune, H.; Nakayama, S.; Shima, T.; Miyamoto, S.

    2015-10-01

    The giant dipole resonance (GDR) in 6Li was investigated via the 6LI(γ, xn) reaction, where x = 1, 2 or 3 at an incident energy range of Eγ =5-55. The(γ, n) cross section was the most dominant cross section among them. The GDR in 6Li was found to consist of two components at Ex = 11 MeV and 33 MeV. The component at Ex = 11 MeV seems to be the intrinsic GDR in 6Li. The other at Ex = 33 MeV is inferred to be the GDR due to the α cluster excitation in 6Li, based on the comparison with the results in light ion reactions. The GDR in free 4He is known to locate at Ex= 26 MeV. However, the GDR excitation energy due tothe α cluster excitation in 6Li is found to be higher than that of the 4He. This fact suggests that the size of the α cluster in 6Li is smaller than that of 4He due to the nuclear medium effect.

  13. REVISED BIG BANG NUCLEOSYNTHESIS WITH LONG-LIVED, NEGATIVELY CHARGED MASSIVE PARTICLES: UPDATED RECOMBINATION RATES, PRIMORDIAL {sup 9}Be NUCLEOSYNTHESIS, AND IMPACT OF NEW {sup 6}Li LIMITS

    SciTech Connect

    Kusakabe, Motohiko; Kim, K. S.; Cheoun, Myung-Ki; Kajino, Toshitaka; Kino, Yasushi; Mathews, Grant J. E-mail: kyungsik@kau.ac.kr E-mail: kajino@nao.ac.jp E-mail: gmathews@nd.edu

    2014-09-01

    We extensively reanalyze the effects of a long-lived, negatively charged massive particle, X {sup –}, on big bang nucleosynthesis (BBN). The BBN model with an X {sup –} particle was originally motivated by the discrepancy between the {sup 6,} {sup 7}Li abundances predicted in the standard BBN model and those inferred from observations of metal-poor stars. In this model, {sup 7}Be is destroyed via the recombination with an X {sup –} particle followed by radiative proton capture. We calculate precise rates for the radiative recombinations of {sup 7}Be, {sup 7}Li, {sup 9}Be, and {sup 4}He with X {sup –}. In nonresonant rates, we take into account respective partial waves of scattering states and respective bound states. The finite sizes of nuclear charge distributions cause deviations in wave functions from those of point-charge nuclei. For a heavy X {sup –} mass, m{sub X} ≳ 100 GeV, the d-wave → 2P transition is most important for {sup 7}Li and {sup 7,} {sup 9}Be, unlike recombination with electrons. Our new nonresonant rate of the {sup 7}Be recombination for m{sub X} = 1000 GeV is more than six times larger than the existing rate. Moreover, we suggest a new important reaction for {sup 9}Be production: the recombination of {sup 7}Li and X {sup –} followed by deuteron capture. We derive binding energies of X nuclei along with reaction rates and Q values. We then calculate BBN and find that the amount of {sup 7}Be destruction depends significantly on the charge distribution of {sup 7}Be. Finally, updated constraints on the initial abundance and the lifetime of the X {sup –} are derived in the context of revised upper limits to the primordial {sup 6}Li abundance. Parameter regions for the solution to the {sup 7}Li problem and the primordial {sup 9}Be abundances are revised.

  14. Revised Big Bang Nucleosynthesis with Long-lived, Negatively Charged Massive Particles: Updated Recombination Rates, Primordial 9Be Nucleosynthesis, and Impact of New 6Li Limits

    NASA Astrophysics Data System (ADS)

    Kusakabe, Motohiko; Kim, K. S.; Cheoun, Myung-Ki; Kajino, Toshitaka; Kino, Yasushi; Mathews, Grant. J.

    2014-09-01

    We extensively reanalyze the effects of a long-lived, negatively charged massive particle, X -, on big bang nucleosynthesis (BBN). The BBN model with an X - particle was originally motivated by the discrepancy between the 6, 7Li abundances predicted in the standard BBN model and those inferred from observations of metal-poor stars. In this model, 7Be is destroyed via the recombination with an X - particle followed by radiative proton capture. We calculate precise rates for the radiative recombinations of 7Be, 7Li, 9Be, and 4He with X -. In nonresonant rates, we take into account respective partial waves of scattering states and respective bound states. The finite sizes of nuclear charge distributions cause deviations in wave functions from those of point-charge nuclei. For a heavy X - mass, mX >~ 100 GeV, the d-wave → 2P transition is most important for 7Li and 7, 9Be, unlike recombination with electrons. Our new nonresonant rate of the 7Be recombination for mX = 1000 GeV is more than six times larger than the existing rate. Moreover, we suggest a new important reaction for 9Be production: the recombination of 7Li and X - followed by deuteron capture. We derive binding energies of X nuclei along with reaction rates and Q values. We then calculate BBN and find that the amount of 7Be destruction depends significantly on the charge distribution of 7Be. Finally, updated constraints on the initial abundance and the lifetime of the X - are derived in the context of revised upper limits to the primordial 6Li abundance. Parameter regions for the solution to the 7Li problem and the primordial 9Be abundances are revised.

  15. Puzzle of the {sup 6}Li Quadrupole Moment: Steps toward Solving It

    SciTech Connect

    Blokhintsev, L.D.; Kukulin, V.I.; Pomerantsev, V.N.

    2005-07-01

    The problem of the origin of the quadrupole deformation in the {sup 6}Li ground state is investigated with allowance for the three-deuteron component of the {sup 6}Li wave function. Two long-standing puzzles related to the tensor interaction in the {sup 6}Li nucleus are known: that of an anomalous smallness of the {sup 6}Li quadrupole moment (being negative, it is smaller in magnitude than the {sup 7}Li quadrupole moment by a factor of 5) and that of an anomalous behavior of the tensor analyzing power T{sub 2q} in the scattering of polarized {sup 6}Li nuclei on various targets. It is shown that a large (in magnitude) negative exchange contribution to the {sup 6}Li quadrupole moment from the three-deuteron configuration cancels almost completely the 'direct' positive contribution due to the {alpha}d folding potential. As a result, the total quadrupole moment proves to be close to zero and highly sensitive to fine details of the tensor nucleon-nucleon interaction in the {sup 4}He nucleus and of its wave function.

  16. New mass measurement of {sup 6}Li and ppb-level systematic studies of the Penning trap mass spectrometer TITAN

    SciTech Connect

    Brodeur, M.; Ettenauer, S.; Smith, M.; Dilling, J.; Brunner, T.; Champagne, C.; Lapierre, A.; Ringle, R.; Ryjkov, V. L.; Delheij, P.; Audi, G.; Lunney, D.

    2009-10-15

    The frequency ratio of {sup 6}Li to {sup 7}Li was measured using the TITAN Penning trap mass spectrometer. This measurement resolves a 16-ppb discrepancy between the {sup 6}Li mass of 6.015 122 795(16) u from the Atomic Mass Evaluation 2003 (AME03), which is based on a measurement by JILATRAP, and the more recent measurement of 6.015 122 890(40) u by SMILETRAP. Our measurement agrees with SMILETRAP and a more precise mass value for {sup 6}Li of 6.015 122 889(26) u is presented along with systematic evaluations of the measurement uncertainties. This result makes {sup 6}Li a solid anchor point for future mass measurements on highly charged ions with m/q{approx}6.

  17. Destructions of {sup 7}Be and {sup 7}Li in Big Bang nucleosynthesis through reactions with exotic long-lived sub-strongly interacting massive particles

    SciTech Connect

    Kusakabe, Motohiko; Kawasaki, Masahiro

    2012-11-12

    An observed plateau abundance of {sup 7}Li in metal-poor halo stars indicates its primordial origin. The {sup 7}Li abundances are about a factor of three smaller than that predicted in standard big bang nucleosynthesis (BBN) model. In addition, some of the stars possibly contain {sup 6}Li in abundances larger than standard BBN prediction. Particle models sometimes include heavy longlived colored particles which are confined in exotic strongly interacting massive particles (SIMPs). We have found reactions which destroy {sup 7}Be and {sup 7}Li during BBN in the scenario of BBN affected by a long-lived sub-strongly interactingmassive particle (sub-SIMP, X). The reactions are non radiative X captures of {sup 7}Be and {sup 7}Li which can operate if the X particle interacts with nuclei strongly enough to drive {sup 7}Be destruction but not strongly enough to form a bound state with {sup 4}He of relative angular momentum L = 1. The processes can be a cause of the {sup 7}Li problem. In this paper we suggest new possible reactions for {sup 6}Li production. Especially, a {sup 6}Li production through the deuteron capture of {sup 4}He bound to X can operate in the parameter region solving the {sup 7}Li problem.

  18. {sup 13}C, {sup 1}H, {sup 6}Li magic-angle spinning nuclear magnetic resonance, electron paramagnetic resonance, and Fourier transform infrared study of intercalation electrodes based in ultrasoft carbons obtained below 3100 K

    SciTech Connect

    Alcantara, R.; Madrigal, F.J.F.; Lavela, P.; Tirado, J.L.; Mateos, J.M.J.; Stoyanova, R.; Zhecheva, E.

    1999-01-01

    The past decade has seen an important development of materials for high-performance energy storage systems. Particularly, the field of electrode materials for advanced lithium batteries has attracted the interest of numerous researchers. Petroleum coke samples of different origins and heat treated at different temperatures below 3100 K have been studied by spectroscopic and electrochemical procedures. According to {sup 13}C and {sup 1}H magic-angle spinning (MAS) nuclear magnetic resonance (NMR), infrared (IR), and electron paramagnetic resonance (EPR) data, aromatic compounds and surface OH groups are present in green coke samples. The preparation of CMB (combustible) sample from 1673 K leads to a low-temperature graphitization process, as shown by the occurrence of multiphase products containing both turbostatic and graphitized solid. This process is accompanied by the loss of aromatic compounds and surface hydroxyls. The optimization of the lithium intercalation electrodes based in the green coke materials was carried out by thermal treatment at 1023 K under dynamic vacuum conditions. Such pretreatment of the electrode material leads to marked enhancement of reversible capacities without the higher temperatures usually required for other soft carbon materials. Finally, the results of {sup 6}Li MAS NMR and EPR have been correlated with the experimental determination of lithium diffusion coefficients and surface properties. On the basis of these results, spin resonance spectroscopies are found to be a powerful tool to discern between the different petroleum coke samples to select the active electrode material with best performance.

  19. High-pressure superconducting phase diagram of 6Li: Isotope effects in dense lithium

    PubMed Central

    Schaeffer, Anne Marie; Temple, Scott R.; Bishop, Jasmine K.; Deemyad, Shanti

    2015-01-01

    We measured the superconducting transition temperature of 6Li between 16 and 26 GPa, and report the lightest system to exhibit superconductivity to date. The superconducting phase diagram of 6Li is compared with that of 7Li through simultaneous measurement in a diamond anvil cell (DAC). Below 21 GPa, Li exhibits a direct (the superconducting coefficient, α, Tc∝M−α, is positive), but unusually large isotope effect, whereas between 21 and 26 GPa, lithium shows an inverse superconducting isotope effect. The unusual dependence of the superconducting phase diagram of lithium on its atomic mass opens up the question of whether the lattice quantum dynamic effects dominate the low-temperature properties of dense lithium. PMID:25538300

  20. Fusion of {sup 6}Li with {sup 159}Tb at near-barrier energies

    SciTech Connect

    Pradhan, M. K.; Mukherjee, A.; Basu, P.; Goswami, A.; Kshetri, R.; Roy, Subinit; Chowdhury, P. Roy; Sarkar, M. Saha; Palit, R.; Parkar, V. V.; Santra, S.; Ray, M.

    2011-06-15

    Complete and incomplete fusion cross sections for {sup 6}Li + {sup 159}Tb have been measured at energies around the Coulomb barrier by the {gamma}-ray method. The measurements show that the complete fusion cross sections at above-barrier energies are suppressed by {approx}34% compared to coupled-channel calculations. A comparison of the complete fusion cross sections at above-barrier energies with the existing data for {sup 11,10}B + {sup 159}Tb and {sup 7}Li + {sup 159}Tb shows that the extent of suppression is correlated with the {alpha} separation energies of the projectiles. It has been argued that the Dy isotopes produced in the reaction {sup 6}Li + {sup 159}Tb at below-barrier energies are primarily due to the d transfer to unbound states of {sup 159}Tb, while both transfer and incomplete fusion processes contribute at above-barrier energies.

  1. A direct measurement of the 6Li(n,t)4He cross section at sub-thermal neutron energy

    NASA Astrophysics Data System (ADS)

    Yue, A.; Dewey, M.; Gilliam, D.; Nico, J.; Greene, G.; Laptev, A.

    2014-09-01

    The thermal neutron capture cross section for the 6Li(n,t)4He reaction is an important neutron cross section standard. Yet few measurements of it have been performed and the ENDF/B-VII recommended value of (938 . 5 +/- 1 . 3) b is based heavily on measurements performed at higher energies. The first absolute, direct measurement of the 6Li(n,t)4He cross section at sub-thermal neutron energy has been performed at the NIST Center for Neutron Research. An alpha-gamma counter was used to measure the absolute neutron fluence of a monoenergetic neutron beam to sub-0.1% precision. The alpha-gamma counter used a thick, totally absorbing target of 10B-enriched boron carbide. The rate of absorbed neutrons was determined by counting the 478 keV 10B(n, γ)7Li gamma rays with calibrated high-purity germanium detectors. Simultaneously, the absolute rate of neutron-induced charged particles was measured for three thin 6Li targets of known density with a defined solid-angle counter. Using the known density of the 6Li targets and measurements of the rate of charged particles from the 6Li targets, the fluence of the neutron beam, and the energy of the neutron beam, we determine the 6Li(n,t)4He cross section at En = 3 . 3 meV to 0.3% uncertainty.

  2. Probing the fusion of 7Li with 64Ni at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Shaikh, Md. Moin; Roy, Subinit; Rajbanshi, S.; Mukherjee, A.; Pradhan, M. K.; Basu, P.; Nanal, V.; Pal, S.; Shrivastava, A.; Saha, S.; Pillay, R. G.

    2016-04-01

    Background: The stable isotopes of Li, 6Li6 and 7Li, have two-body cluster structures of α +d and α +t with α -separation energies or breakup thresholds at 1.47 and 2.47 MeV, respectively. The weak binding of these projectiles introduces several new reaction channels not usually observed in the case of strongly bound projectiles. The impact of these breakup or breakup-like reaction channels on fusion, the dominant reaction process at near-barrier energies, with different target masses is of current interest. Purpose: Our purpose is to explore the fusion, at above and below the Coulmb barrier, of 7Li with 64Ni target in order to understand the effect of breakup or breakup-like processes with medium-mass target in comparison with 6Li, which has a lower breakup threshold. Measurement: The total fusion (TF) excitation of the weakly bound projectile 7Li with the medium-mass target 64Ni has been measured at the near-barrier energies (0.8 to 2 VB). The measurement was performed using the online characteristic γ -ray detection method. The complete fusion (CF) excitation function for the system was obtained using the x n -evaporation channels with the help of statistical model predictions. Results: At the above barrier energies CF cross sections exhibit an average suppression of about 6.5% compared to the one-dimensional barrier penetration model (1DBPM) predictions, while the model describes the measured TF cross section well. But below the barrier, both TF and CF show enhancements compared to 1DBPM predictions. Unlike 6Li, enhancement of CF for 7Li could not be explained by inelastic coupling alone. Conclusion: Whereas the σTF cross sections are almost the same for both the systems in the above barrier region, the suppression of σCF at above the barrier is less for the 7Li+64Ni system than for the 6+64Ni system. Also direct cluster transfer has been identified as the probable source for producing large enhancement in TF cross sections.

  3. Reaction mechanism of 7Li(3He,p)9Be and 7Li(3H,n)9Be and primordial nucleosynthesis of 9Be

    NASA Astrophysics Data System (ADS)

    Yamamoto, Y.; Kajino, T.; Kubo, K.-I.

    1993-02-01

    We investigate in a unified way the reaction mechanism of 7Li(3H,n)9Be and 7Li(3He, p)9Be at the low energies Ec.m.<=2 MeV of astrophysical interest. Assuming charge independence of the nuclear reaction amplitudes and taking account of the effects from different isospin contribution, Coulomb interaction, and associated kinematical conditions properly, we constrain the upper and lower bounds of the total cross section of 7Li(3H,n)9Be theoretically by using knowledge of the 7Li(3He, p)9Be reaction. It is found that the total cross section of 7Li(3H,n)9Be at Gamow window energy E~250 keV is dominated by the near-threshold T=1 resonance whose resonance parameters are not determined at all experimentally, although the direct reaction process makes progressively important contributions at higher energies 500 keV<=Ec.m.. Primordial abundance of 9Be calculated in the inhomogeneous and standard big-bang models by using the inferred reaction cross section for 7Li(3H,n)9Be is compared with recent results of astronomical observations.

  4. 6Li foil thermal neutron detector

    SciTech Connect

    Ianakiev, Kiril D; Swinhoe, Martyn T; Favalli, Andrea; Chung, Kiwhan; Macarthur, Duncan W

    2010-01-01

    In this paper we report on the design of a multilayer thermal neutron detector based on {sup 6}Li reactive foil and thin film plastic scintillators. The {sup 6}Li foils have about twice the intrinsic efficiency of {sup 10}B films and about four times higher light output due to a unique combination of high energy of reaction particles, low self absorption, and low ionization density of tritons. The design configuration provides for double sided readout of the lithium foil resulting in a doubling of the efficiency relative to a classical reactive film detector and generating a pulse height distribution with a valley between neutron and gamma signals similar to {sup 3}He tubes. The tens of microns thickness of plastic scintillator limits the energy deposited by gamma rays, which provides the necessary neutron/gamma discrimination. We used MCNPX to model a multilayer Li foil detector design and compared it with the standard HLNCC-II (18 {sup 3}He tubes operated at 4 atm). The preliminary results of the {sup 6}Li configuration show higher efficiency and one third of the die-away time. These properties, combined with the very short dead time of the plastic scintillator, offer the potential of a very high performance detector.

  5. Lithium and Isotopic Ratio Li6/Li7 in Magnetic roAp Stars as an Indicator of Active Processes

    NASA Astrophysics Data System (ADS)

    Polosukhina, N.; Shavrina, A.; Lyashko, D.; Nesvacil, N.; Drake, N.; Smirnova, M.

    2015-04-01

    The lines of lithium at 6708 Å and 6103 Å are analyzed in high resolution spectra of some sharp-lined and slowly rotating roAp stars. Three spectral synthesis codes— STARSP, ZEEMAN2, and SYNTHM—were used. New lines of rare earth elements (REE) from the DREAM database and the lines calculated on the basis of the NIST energy levels were included. Magnetic splitting and other line broadening processes were taken into account. For both lithium lines, the enhanced abundances of lithium in the atmospheres of the stars studied are obtained. The lithium abundance determined from the Li 6103 Å line is higher than that from the Li 6708 Å for all the stars. This may be evidence of vertical lithium stratification, abnormal temperature distribution, or unidentified blending of the 6103 Å line. Our work on two roAp stars, HD 83368 and HD 60435 (Shavrina et al. 2001) provides evidence of an enhanced lithium abundance near the magnetic-field poles. We can expect similar effects in the sharp-lined roAp stars. High lithium abundance for all the stars and the estimates of the 6Li/7Li ratio (0.2-0.5) can be explained by production of Li in the cosmic ray spallation reactions in the interstellar medium where the stars were born, and by preservation of the original 6Li and 7Li by strong magnetic fields of these stars. The values of the 6Li/7Li ratio expected from production by cosmic rays are about 0.5-0.8 (Knauth et al. 2003; Webber et al. 2002). New laboratory and theoretical gf-values for REE lines are necessary in order to refine our estimates of lithium abundances and the isotopic ratio.

  6. 6Li(p,Δ++)6He reaction reanalysed

    NASA Astrophysics Data System (ADS)

    Kundu, Bijoy; Jain, B. K.

    1998-03-01

    Using our recently developed formalism for the (p,Δ) reaction, which includes the decay of Δ inside the nuclear medium, we study the 6Li(p,Δ++)6He reaction, and compare the calculated cross sections with those measured some time back at Saturne. In the formalism, the Δ resonance decays into pπ+ either inside or outside the nuclear medium. The medium effects on Δ as well as on p and π+ are incorporated through appropriate optical potentials. The transition potential for the elementary process pp-->nΔ++ is taken to be one pion-exchange, whose parameters are constrained to reproduce the measured spin averaged cross sections on the pp--> nΔ++ reaction over a large energy range. The calculated results agree well with the measured cross sections. © 1998

  7. Neutron spectroscopy with {sup 6}LiF bolometers

    SciTech Connect

    Gironnet, J.; Brandt, B. van den; Hautle, P.; Filges, U.; Konter, J. A.; Coron, N.; Marcillac, P. de; Torres, L.

    2009-12-16

    A compact and semi-portable neutron detector has been built based on the bolometric technique. Its unique features open new possibilities for the radioprotection survey of fast neutrons at nuclear installations and the investigations of background problems of sensitive neutron scattering instruments. This cryogenic detector, operated at 300-400 mK, consists of a 0.5 g LiF 95%{sup 6}Li enriched crystal read out by a NTD-Ge sensor and is based on the {sup 6}Li(n, {alpha}){sup 3}H neutron capture reaction. It is used to define the energy of neutrons up to 5 MeV. Measurements with {sup 252}Cf source have been performed to determine the energy resolution of the detector. We report the first results obtained with this neutron detector. From developments made in view of the ROSEBUD (Rare Objects SEarch with Bolometers UndergrounD) collaboration we suggest a possible further improvement of the neutron detector by employing a combined heat and light detection. In the case of dark matter experiments, such a detector would allow to monitor the residual fast neutron component.

  8. Spectroscopic information of 6Li from elastic scattering of deuterons, 3He and 4He by 6Li

    NASA Astrophysics Data System (ADS)

    Amar, A.

    2014-07-01

    The elastic scattering of deuterons, 3He and 4He on 6Li at different incident energies have been analyzed in the framework of the optical model (OM) using ECIS88 as well as SPI GENOA codes. The optical potential parameters were extracted in the phenomenological treatment. A good agreement between theoretical and experimental differential cross-sections was obtained in whole angular range. Parameters for real part of potential have been also calculated microscopically with double-folding model for the d, 3He and 4He scattering, respectively, using DFPOT code. The elastic transfer mechanism has been studied by coupled reaction channel (CRC) method using FRESCO code. Spectroscopic amplitudes of 6Li ≡ t + 3He and 6Li ≡ α + d configurations have been extracted from d, 3He and 4He scattering on 6Li at wide energy range. A comparison between spectroscopic amplitudes obtained from deuteron and α elastically scattering from 6Li has been made. The extracted spectroscopic amplitudes of 6Li ≡ 4He + d(SF = SA2) from 6Li(d, 6Li)d and 6Li(α, 6Li)α are not the same as expected theoretically.

  9. A method for investigation of the D(4He, γ)6Li reaction in the Ultralow energy region under a high background

    NASA Astrophysics Data System (ADS)

    Bystritsky, V. M.; Dudkin, G. N.; Krylov, A. R.; Gazi, S.; Huran, J.; Nechaev, B. A.; Padalko, V. N.; Sadovsky, A. B.; Tuleushev, Yu. Zh.; Filipowicz, M.; Philippov, A. V.

    2016-07-01

    The cosmological lithium problem, that is, a noticeable discrepancy between the predicted and observed abundances of lithium, is in conflict with the Standard Big Bang Nucleosynthesis model. For example, the abundance of 7Li is 2-4 times smaller than predicted by the Standard Big Bang Nucleosynthesis. As to the abundance of 6Li, recent more accurate optical investigations have yielded only the upper limit on the 6Li/7Li ratio, which makes the problem of 6Li abundance and accordingly of disagreement with the Standard Big Bang Nucleosynthesis predictions less acute. However, experimental study of the D(4He, γ)6Li reaction cross section is still of current importance because there is a theoretical approach predicting its anomalously large value in the region of energies below the Standard Big Bang Nucleosynthesis energy. The work is dedicated to the measurement of the cross section for the D(4He, γ)6Li reaction proceeding in zirconium deuteride at the incident 4He+ion energy of 36 keV. The experiment is performed at a pulsed Hall plasma accelerator with an energy spread of 20% FWHM. A method for direct measurement of the background from the reaction chain D(4He, 4He)D→D(D, n)3He→(n, γ) and/or (n, n‧γ) ending with activation of the surrounding material by neutrons is proposed and implemented in the work. An upper limit on the D(4He, γ)6Li reaction cross section σ≤7·10-36 cm2 at the 90% confidence level is obtained.

  10. Efimov physics in {sup 6}Li atoms

    SciTech Connect

    Braaten, Eric; Hammer, H.-W.; Kang, Daekyoung; Platter, Lucas

    2010-01-15

    A new narrow three-atom loss resonance associated with an Efimov trimer crossing the three-atom threshold has recently been discovered in a many-body system of ultracold {sup 6}Li atoms in the three lowest hyperfine spin states at a magnetic field near 895 G. O'Hara and coworkers have used measurements of the three-body recombination rate in this region to determine the complex three-body parameter associated with Efimov physics. Using this parameter as the input, we calculate the universal predictions for the spectrum of Efimov states and for the three-body recombination rate in the universal region above 600 G where all three scattering lengths are large. We predict an atom-dimer loss resonance at 672+-2 G associated with an Efimov trimer disappearing through an atom-dimer threshold. We also predict an interference minimum in the three-body recombination rate at 759+-1 G where the three-spin mixture may be sufficiently stable to allow experimental study of the many-body system.

  11. Breakup Reactions and Exclusive Measurements in the {sup 6,7}Li+{sup 144}Sm Systems

    SciTech Connect

    Heimann, D. Martinez; Pacheco, A. J.; Arazi, A.; Figueira, J. M.; Negri, A. E.; Capurro, O. A.; Carnelli, P.; Fimiani, L.; Grinberg, P.; Marti, G. V.; Testoni, J. E.; Monteiro, D. S.; Marta, H. D.

    2009-06-03

    The breakup of the projectile-like nuclei in reactions induced by 30 MeV {sup 6}Li and {sup 7}Li beams on a {sup 144}Sm target have been measured through the coincident detection of the in-plane emitted light particles. The primary ion that undergoes breakup has been identified and the physically meaningful variables that characterize the reaction have been obtained on a purely experimental basis. Distributions have been obtained for both the binary emission angle and for the breakup emission angle in the reference frame of the breakup products.

  12. Primordial α +d →6Li+γ reaction and second lithium puzzle

    NASA Astrophysics Data System (ADS)

    Mukhamedzhanov, A. M.; Shubhchintak, Bertulani, C. A.

    2016-04-01

    During the Big Bang, 6Li was synthesized via the 2H(α ,γ ) 6Li reaction. After almost 25 years of the failed attempts to measure the 2H(α ,γ ) 6Li reaction in the laboratory at Big Bang energies, just recently the LUNA Collaboration presented the first successful measurements at two different Big Bang energies [Anders et al., Phys. Rev. Lett. 113, 042501 (2014), 10.1103/PhysRevLett.113.042501]. In this paper we will discuss how to improve the accuracy of the direct experiment. To this end the photon's angular distribution is calculated in the potential model. It contains contributions from electric dipole and quadrupole transitions and their interference, which dramatically changes the photon's angular distribution. The calculated distributions at different Big Bang energies have a single peak at ˜50∘ . These calculations provide the best kinematic conditions to measure the 2H(α ,γ ) 6Li reaction. The expressions for the total cross section and astrophysical factor are also derived by integrating the differential cross section over the photon's solid angle. The LUNA data are in excellent agreement with our calculations using a potential approach combined with a well established asymptotic normalization coefficient for 6Li→α +d . Comparisons of the available experimental data for the S24 astrophysical factor and different calculations are presented. The Big Bang lithium isotopic ratio 6Li/7Li=(1.5 ±0.3 ) ×10-5 following from the LUNA data and the present analysis are discussed in the context of the disagreement between the observational data and the standard Big Bang model, which constitutes the second

  13. Spectroscopic study of the C 1Σ+ state of 7LiH

    NASA Astrophysics Data System (ADS)

    Chen, Jye-Jong; Luh, Wei-Tzou; Jeung, Gwang-Hi

    1999-03-01

    Forty-two vibrational (v=2-43) levels of the 7LiH C 1Σ+ excited electronic state have been observed by a pulsed optical-optical double resonance fluorescence depletion spectroscopic technique. The absolute vibrational numbering of the C 1Σ+ state is identified with the measurements of the isotopic shifts between 7LiH and 6LiH among several rotation-vibration bands of the C 1Σ+-A 1Σ+ electronic system, and it is further demonstrated by the consistency between observed spectral intensities and calculated ones. The highest observed quasi bound rotational level for the v=43 level is J=8. The spectral term values for those vibrational levels lying above v=33 occur in an irregular order. The level of v=34 lies mainly in the inner, tiny well. The term values for the observed rovibrational levels (2⩽v⩽32, 0⩽J⩽11) in the outer ionic well are described by a set of Dunham-type coefficients, with which a Rydberg-Klein-Rees (RKR) potential energy curve is constructed. This RKR potential is combined with an ab initio potential to construct an effective hybrid potential. The calculated electronic transition moment function for the C-A transition is also given.

  14. Exclusive Measurements of Breakup Reactions in the {sup 7}Li+{sup 144}Sm System

    SciTech Connect

    Heimann, D. Martinez; Pacheco, A. J.; Arazi, A.; Figueira, J. M.; Negri, A.; Capurro, O. A.; Carnelli, P.; Fimiani, L.; Grinberg, P.; Marti, G. V.; Testoni, J. E.; Monteiro, D. S.; Marta, H. D.

    2009-03-04

    Breakup reactions induced by a 30 MeV {sup 7}Li beam on a {sup 144}Sm target were measured through the coincident detection of the light particles emitted in the reaction plane. The emphasis of the measurements and data analysis was placed in the complete characterization of the reaction by means of the identification of the breakup products and the experimental extraction of the physically relevant magnitudes. The coincident yield of the emitted light particles was compared with the results of kinematical calculations that were done assuming different distributions for these magnitudes and taking into account the geometric response of the detection system. The results of this comparison indicate in all cases a clear dominance of a process compatible with the breakup of {sup 6}Li through the 3{sup +} resonant state at 2.186 MeV following one-neutron transfer from the projectile to the target, over the breakup of the projectile itself. Relative cross sections as a function of the emission angle of the {sup 6}Li and the in-plane anisotropy of the subsequent emission of breakup products were extracted from the data.

  15. Colorado School of Mines Low Energy Nuclear Physics Project technical progress report

    SciTech Connect

    Cecil, F.E.

    1990-01-05

    This report summarizes the activity and accomplishments of the Colorado School of Mines Low Energy Nuclear Physics project during the calendar year 1989. Many of the projects which were anticipated in the original grant proposal have been completed. Among these completed projects we include of study of the radiative capture of low energy protons on {sup 6}Li, {sup 7}Li, {sup 9}Be, and {sup 11}B. Preliminary measurements of the branching ratios and yields of these reactions were reported in last year's Technical Progress Report. These measurements are now complete and have been used to extract the respective astrophysical S-factors and the corresponding thermonuclear reactivities. While not complete, progress has been made in some of the other originally proposed studies. Among these include a fairly extensive study of the interaction of low energy deuterons with {sup 6}Li and {sup 7}Li. In the course of this study we have made a solid observation of the Oppenheimer-Phillips effect in the D-{sup 6}Li system. Progress has been made in our study of the radiative capture of alpha particles by deuterons, {sup 6}Li, and {sup 7}Li but considerable work remains in these studies. In our earlier reports we noted the observation of d-d reactions during the bombardment of deuterated targets with energetic beams of protons, alpha particles, and other light-to-medium ions. We believe we now understand this phenomenon and feel it has some fairly significant consequences both for our studies and for those of other researchers. Our susceptibility to mob hysteria led us to invest a significant effort in cold nuclear fusion, both employing a fairly unique accelerator based approach at CSM and as one of the gamma ray diagnosticians on the Princeton Plasma Physics Laboratory's Cold Fusion Task Force.

  16. Electrical conductivity, differential scanning calorimetry, X-ray diffraction, and 7Li nuclear magnetic resonance studies of n-C x H(2 x+1)OSO3Li ( x = 12, 14, 16, 18, and 20)

    NASA Astrophysics Data System (ADS)

    Hirakawa, Satoru; Morimoto, Yoshiaki; Honda, Hisashi

    2015-04-01

    Electrical conductivity ( σ), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) measurements of n-C x H (2 x+1) OSO 3Li ( x= 12, 14, 16, 18, and 20) crystals were performed as a function of temperature. In addition, σ, DSC, and XRD observations of n-C x H (2 x+1) OSO 3Na and n-C x H (2 x+1) OSO 3K ( x= 12, 14, 16, 18, and 20) crystals were carried out for comparison. DSC results of the salts revealed several solid-solid phase transitions with large entropy changes (Δ S). For n-C 18 H 37 OSO 3Li and n-C 20 H 41 OSO 3Li salts, each melting point produced a small Δ S mp value compared with the total entropy change in the solid phases (Δ S tr1+Δ S tr2). Additionally, Li + ion diffusion was detected in the highest temperature solid phases. For K salts, larger σ values were detected for potassium alkylsulfates compared with those reported for alkyl carboxylate. 7Li NMR spectra of n-C 18 H 37 OSO 3Li crystals recorded in the low-temperature phase showed large asymmetry parameters, suggesting the Li + ions are localized at asymmetric sites in the crystals.

  17. Integrated readout of organic scintillator and ZnS:Ag/6LiF for segmented antineutrino detectors.

    SciTech Connect

    Kiff, Scott D.; Reyna, David; Monahan, James; Bowden, Nathaniel S.

    2010-11-01

    Antineutrino detection using inverse beta decay conversion has demonstrated the capability to measure nuclear reactor power and fissile material content for nuclear safeguards. Current efforts focus on aboveground deployment scenarios, for which highly efficient capture and identification of neutrons is needed to measure the anticipated antineutrino event rates in an elevated background environment. In this submission, we report on initial characterization of a new scintillation-based segmented design that uses layers of ZnS:Ag/{sup 6}LiF and an integrated readout technique to capture and identify neutrons created in the inverse beta decay reaction. Laboratory studies with multiple organic scintillator and ZnS:Ag/{sup 6}LiF configurations reliably identify {sup 6}Li neutron captures in 60 cm-long segments using pulse shape discrimination.

  18. Differential cross section measurements for the 6Li(n,t)alpha reaction in the few MeV region

    SciTech Connect

    Devlin, Matthew J; Taddeucci, Terence N; Hale, Gerald M; Haight, Robert C; O' Donnell, Johhn M

    2008-01-01

    New measured differential cross sections of tritons and alpha particles following the {sup 6}Li(n,t){alpha} reaction are reported for incident neutron energies between 0.2 and approximately 20 MeV. The neutrons were produced by spallation at the WNR facility at the Los Alamos Neutron Science CEnter (LANSCE), with the incident neutron energy determined by the time-of-flight method. Four E-{Delta}E telescopes were used at eight laboratory angles. These data have been incorporated into a prior R-matrix fit for the compound {sup 7}Li system, and result in an (n,t) reaction cross section that is 4% to 10% higher than previous evaluations in the 1-3 MeV incident neutron energy region.

  19. UCN detection with 6Li-doped glass scintillators

    NASA Astrophysics Data System (ADS)

    Ban, G.; Bodek, K.; Lefort, T.; Naviliat-Cuncic, O.; Pierre, E.; Plonka, C.; Rogel, G.

    2009-12-01

    We report the results of test measurements aimed at determining the performance of 6Li-doped glass scintillators for ultra-cold neutron detection. Investigations have mainly focused on the reduction of the gamma-ray sensitivity of the scintillators. The probability of gamma interaction has been considerably lowered using very thin glasses. For signals corresponding to full-energy deposition, a background count rate of 8×10 -3 s -1 was obtained for a shielded 0.5 cm 3 GS10 scintillator located near the PF2 turbine at ILL. The neutron-gamma separation has further been improved using a stack with an 6Li-depleted scintillator and an 6Li-enriched one. Neutron captures leading to partial energy deposition (so-called "edge events") have strongly been reduced resulting in a clear separation between the neutron and the gamma contributions.

  20. CNO and 6Li from big-bang nucleosynthesis-Impact of unmeasured reaction rates

    NASA Astrophysics Data System (ADS)

    Madsen, Jes

    1990-04-01

    Rates for a number of nuclear reactions not studied in the laboratory are crucial for predicting the outcome of big-bang nucleosynthesis. It is shown in the present investigation that the mass fraction of CNO elements produced in neutron-rich zones in inhomogeneous nucleosynthesis (other parameters fixed) spans almost 3 orders of magnitude depending on the unmeasured rate of 8Li(α,n)11B. The possibility of producing observable quantities of primordial 6Li via 3H(3He,γ)6Li is discussed for the first time, and finally it is reported that helium production through 2H(2H, γ)4He is negligible in all nucleosynthesis scenarios, in spite of recent measurements increasing the low-energy rate by a factor 32.

  1. CDCC calculations of elastic scattering for the systems 6Li+144Sm and 6Li+208Pb. Effect of resonances of 6Li on elastic scattering angular distributions

    NASA Astrophysics Data System (ADS)

    Gómez Camacho, A.

    2015-01-01

    Calculations of elastic scattering angular distributions for reactions of the weakly bound projectile 6Li with targets 144Sm and 208Pb at energies above the barrier, are performed with the Continuum Discretized Coupled-Channel method (CDCC). Ground, resonant and nonresonant continuum states of 6Li are included up to some maximum energy epsilonmax for which convergence is achieved. In the three-body system, global interactions are used for the α-target and d - target sub-systems. The effect of continuum resonant states of 6Li, i.e., l = 2, jπ = 3+, 2+ and 1+ on elastic scattering angular distributions is investigated by extracting these states from the continuum space. It is found that the calculated elastic scattering angular distributions are in good agreement with the measurements for most of the cases studied where consideration of couplings to continuum states is essential. It is also found that the resonance character of the continuum states is in some cases important to obtain agreement with the data.

  2. [sup 26]Mg([sup 6]L[rvec i],[sup 7]Li)[sup 25]Mg reaction at 60 MeV

    SciTech Connect

    Ward, R.P.; Clarke, N.M. School of Physics and Space Research, University of Birmingham, Edgbaston, Birmingham B15 2TT ); Pearce, K.I.; Pinder, C.N. ); Blyth, C.O.; Choi, H.D.; Dee, P.R.; Roman, S.; Tungate, G. ); Davis, N.J. )

    1995-03-01

    Angular distributions of differential cross section and vector analyzing power have been measured for the [sup 26]Mg([sup 6]L[rvec i],[sup 7]Li)[sup 25]Mg reaction at 60 MeV bombarding energy. Finite-range distorted-wave Born approximation calculations were found to reproduce much of the structure of the data, although the predictions were approximately 3[degree] out of phase with the data. Finite-range coupled-channels Born approximation calculations including inelastic excitations in [sup 6]Li and [sup 7]Li, using coupling schemes derived from elastic scattering analyses, modified the predictions only slightly and did not remove the phase discrepancy.

  3. Reaction mechanisms in the 6Li+ 52Cr system

    NASA Astrophysics Data System (ADS)

    Pandey, Bhawna; Prajapati, P. M.; Patel, D.; Desai, V. V.; Kumar, H.; Suranarayana, S. V.; Nayak, B. K.; Saxena, Alok; Jakhar, S.; Rao, CVS; Basu, T. K.

    2015-01-01

    Reactions induced by the weakly bound 6Li projectile interacting with the intermediate mass target 52Cr are investigated. The choice of this particular reaction in our study is because it is proposed as a surrogate reaction [6Li(52Cr, d)56Fe*] for the measurement of 55Fe(n,p) reaction cross-section, which has been found to be very important in fusion reactor studies. All the conditions which have to be satisfied for using the surrogate method have been checked. The energy of 6Li beam is selected in a way so as to get equivalent neutron energy in the region of 9-14 MeV, which is of primary interest in fusion reactor application. In the present work, statistical model calculations PACE (Projection-Angular-Momentum-Coupled-Evaporation), ALICE and Continuum-Discretized-Coupled-Channel (CDCC: FRESCO) have been used to provide information for the 6Li + 52Cr system and the respective contributions of different reaction mechanisms. The present theoretical work is an important step in the direction towards studying the cross-section of the 55Fe(n, p)55Mn reaction by surrogate method.

  4. Near- and subbarrier elastic and quasielastic scattering of the weakly bound {sup 6}Li projectile on {sup 144}Sm

    SciTech Connect

    Monteiro, D. S.; Otomar, D. R.; Lubian, J.; Gomes, P. R. S.; Arazi, A.; Figueira, J. M.; Heimann, D. Martinez; Negri, A. E.; Pacheco, A. J.; Niello, J. O. Fernandez; Guimaraes, V.

    2009-01-15

    High-precision data of backward-angle elastic and quasielastic scattering for the weakly bound {sup 6}Li projectile on {sup 144}Sm target at deep-sub-barrier, near-, and above-barrier energies were measured. From the deep-sub-barrier data, the surface diffuseness of the nuclear interacting potential was studied. Barrier distributions were extracted from the first derivatives of the elastic and quasielastic excitation functions. It is shown that sequential breakup through the first resonant state of the {sup 6}Li is an important channel to be included in coupled-channels calculations, even at deep-sub-barrier energies.

  5. Investigations of 6LiIn1-xGaxSe2 semi-insulating crystals for neutron detection

    NASA Astrophysics Data System (ADS)

    Wiggins, Brenden; Bell, Joseph; Burger, Arnold; Stassun, Keivan; Stowe, Ashley C.

    2015-08-01

    Neutron detectors are used for illicit material detection, neutron radiography, stellar investigations of chemical content including biological compounds in planetary terrain and to monitor nuclear power plant fuel products and radioactive waste. Li-containing chalcogenide materials are promising alternative thermal neutron detection materials due to the incorporation of the 6Li isotope at high density. 6LiInSe2 is limited in its effective thermal neutron efficiency by 115In neutron capture which results in gamma decay rather than charge creation. This study includes investigations of mixed crystalline material 6LiIn1-xGaxSe2 where the indium concentration is reduced by Ga substitution. The optical properties have been tuned by gallium substitution and radiation response has been observed.

  6. Photoassociation spectroscopy of long-range molecular states below the 2s + 3p 6Li2 asymptote

    NASA Astrophysics Data System (ADS)

    Gross, Christian; Chaudhuri, Saptarishi; Gan, Jaren; Dieckmann, Kai

    2015-05-01

    We present photoassociation spectra of high-lying vibrational states of the interatomic potentials correlating to the 2s + 3p asymptote of 6Li2 . Starting from an atomic cloud in a magneto-optical trap we first drive a free-to-bound transition into a molecular bound state using a tunable ultra-violet laser. Thereafter we ionize these long-range molecules using a 532 nm laser and detect the resulting ions with a channeltron. We determine the absolute positions of the transitions with MHz precision utilizing a frequency comb based calibration. Lithium dimers are extensively studied theoretically using various models and methods. Spectroscopic measurements are crucial to test and benchmark these methods and are available for various electronic states and inter-nuclear distances of 6Li2 molecule. Our study provides the first experimental observation of long-range states of the 2s + 3p asymptote of 6Li2 .

  7. Elastic Scattering of 7Li+27Al at Backward Angles in the 7-11 MeV Energy Range for Application in RBS

    NASA Astrophysics Data System (ADS)

    Carnelli, P. F. F.; Abriola, D.; Arazi, A.; Capurro, O. A.; Cardona, M. A.; Fernández Niello, J. O.; Figueira, J. M.; Fimiani, L.; Grinberg, P.; Hojman, D.; Martí, G. V.; Martinez Heimann, D.; Negri, A. E.; Pacheco, A. J.

    2010-08-01

    We have measured elastic excitation functions for the 7Li+27Al system, in an energy range close to its Coulomb barrier (Elab = 8.4 MeV) in steps of 0.25 MeV. For this purpose, an array of eight surface-barrier detectors was used. To get an insight on the background composition (mainly α particles), a telescope-detector was used for atomic-number identification. Identical measurements for the 6Li+27Al system are planned for the near future.

  8. Elastic Scattering of {sup 7}Li+{sup 27}Al at Backward Angles in the 7-11 MeV Energy Range for Application in RBS

    SciTech Connect

    Carnelli, P. F. F.; Arazi, A.; Cardona, M. A.; Figueira, J. M.; Hojman, D.; Martinez Heimann, D.; Negri, A. E.; Pacheco, A. J.; Abriola, D.; Capurro, O. A.; Fimiani, L.; Grinberg, P.; Marti, G. V.; Fernandez Niello, J. O.

    2010-08-04

    We have measured elastic excitation functions for the {sup 7}Li+{sup 27}Al system, in an energy range close to its Coulomb barrier (E{sub lab} = 8.4 MeV) in steps of 0.25 MeV. For this purpose, an array of eight surface-barrier detectors was used. To get an insight on the background composition (mainly {alpha} particles), a telescope-detector was used for atomic-number identification. Identical measurements for the {sup 6}Li+{sup 27}Al system are planned for the near future.

  9. Coulomb breakup of 6Li into α+d in the field of a 208Pb ion

    NASA Astrophysics Data System (ADS)

    Irgaziev, B. F.; Nabi, Jameel-Un; Khan, Darwaish

    2011-12-01

    The triple differential cross section of the 208Pb(6Li,αd)208Pb quasielastic breakup is calculated at a collision energy of 156 MeV and a scattering angle range of 2∘-6∘. We fit the parameters of the Woods-Saxon potential using the experimental α-d phase shifts for different states to describe the relative motion of the α particle and deuteron. To check the validity of the two particle approach for the α-d system, we apply a potential model to describe the 2H(α,γ)6Li radiative capture. We calculate the Coulomb breakup using the semiclassical method while an estimation of the nuclear breakup is made on the basis of the diffraction theory. A comparison of our calculation with the experimental data of Kiener [Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.44.2195 44, 2195 (1991)] gives evidence for the dominance of the Coulomb dissociation mechanism and the contribution of nuclear distortion, but is essentially smaller than the value reported by Hammache [Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.82.065803 82, 065803 (2010)]. The results of our calculation for the triple cross sections (contributed by the Coulomb and nuclear mechanisms) of the 6Li breakup hint toward a forward-backward asymmetry in the relative direction of the α particle and deuteron emission, especially at smaller scattering angles, in the 6Li center-of-mass (c.m.) system.

  10. New nuclear physics for big bang nucleosynthesis

    SciTech Connect

    Boyd, Richard N.; Brune, Carl R.; Fuller, George M.; Smith, Christel J.

    2010-11-15

    We discuss nuclear reactions which could play a role in big bang nucleosynthesis. Most of these reactions involve lithium and beryllium isotopes and the rates for some of these have not previously been included in BBN calculations. Few of these reactions are well studied in the laboratory. We also discuss novel effects in these reactions, including thermal population of nuclear target states, resonant enhancement, and nonthermal neutron reaction products. We perform sensitivity studies which show that even given considerable nuclear physics uncertainties, most of these nuclear reactions have minimal leverage on the standard BBN abundance yields of {sup 6}Li and {sup 7}Li. Although a few have the potential to alter the yields significantly, we argue that this is unlikely.

  11. An update on the big bang nucleosynthesis prediction for {sup 7}Li: the problem worsens

    SciTech Connect

    Cyburt, Richard H; Fields, Brian D; Olive, Keith A E-mail: bdfields@uiuc.edu

    2008-11-15

    The lithium problem arises from the significant discrepancy between the primordial {sup 7}Li abundance as predicted by big bang nucleosynthesis (BBN) theory and the Wilkinson Microwave Anisotropy Probe (WMAP) baryon density, and the pre-Galactic lithium abundance inferred from observations of metal-poor (Population II) stars. This problem has loomed for the past decade, with a persistent discrepancy of a factor of 2-3 in {sup 7}Li/H. Recent developments have sharpened all aspects of the Li problem. Namely: (1) BBN theory predictions have sharpened due to new nuclear data; in particular, the uncertainty on the reaction rate for{sup 3}He({alpha},{gamma}){sup 7}Be has reduced to 7.4%, nearly a factor of 2 tighter than previous determinations. (2) The WMAP five-year data set now yields a cosmic baryon density with an uncertainty reduced to 2.7%. (3) Observations of metal-poor stars have tested for systematic effects. With these, we now find that the BBN+WMAP predicts{sup 7}Li/H = (5.24{sub -0.67}{sup +0.71}) Multiplication-Sign 10{sup -10}. The central value represents an increase by 23%, most of which is due to the upward shift in the{sup 3}He({alpha},{gamma}){sup 7}Be rate. More significant is the reduction in the{sup 7}Li/H uncertainty by almost a factor of 2, tracking the reduction in the{sup 3}He({alpha},{gamma}){sup 7}Be error bar. These changes exacerbate the Li problem; the discrepancy is now a factor 2.4 or 4.2{sigma} (from globular cluster stars) to 4.3 or 5.3{sigma} (from halo field stars). Possible resolutions to the lithium problem are briefly reviewed, and key experimental and astronomical measurements highlighted.

  12. Atomic masses of {sup 6}Li,{sup 23}Na,{sup 39,41}K,{sup 85,87}Rb, and {sup 133}Cs

    SciTech Connect

    Mount, Brianna J.; Redshaw, Matthew; Myers, Edmund G.

    2010-10-15

    The atomic masses of the alkali-metal isotopes {sup 6}Li,{sup 23}Na,{sup 39,41}K,{sup 85,87}Rb, and {sup 133}Cs have been obtained from measurements of cyclotron frequency ratios of pairs of ions simultaneously trapped in a Penning trap. The results, with one standard deviation uncertainty, are: M({sup 6}Li)=6.015 122 887 4(16)u,M({sup 23}Na)=22.989769 282 8(26)u,M({sup 39}K)=38.963 706 485 6(52)u,M({sup 41}K)=40.961 825 257 4(48)u,M({sup 85}Rb)=84.911 789739(9)u,M({sup 87}Rb)=86.909 180 535(10)u, and M({sup 133}Cs)=132.905 451 963(13)u. Our mass of {sup 6}Li yields an improved neutron separation energy for {sup 7}Li of 7251.1014(45) keV.

  13. Cluster folding model for /sup 12/C(/sup 6/Li,/sup 6/Li) scattering at 156 Mev

    SciTech Connect

    Majka, Z.; Gils, H.J.; Rebel, H.

    1982-06-01

    A double-folding cluster model generated from d-..cap alpha.. and ..cap alpha..-..cap alpha.. interactions and internal cluster wave functions of the projectile and the target nuclei is proposed to describe the differential cross sections for /sup 6/Li elastic scattering from /sup 12/C at 156 MeV. Results of these calculations are compared with standard double-folding models and the phenomenological optical model predictions.

  14. Barrier distributions for the 7Li+27Al reaction

    NASA Astrophysics Data System (ADS)

    Cárdenas, W. H. Z.

    2010-08-01

    Barrier distributions can be obtained from the first derivative of the elastic and quasielastic (QEL) backward angle excitation functions [1]. In this work we present a study of the barrier distribution for the 7Li+27Al reaction from a Coupled-Channels Born Approximation (CCBA) calculations using the code FRESCO [2].

  15. Neutron detection and identification using ZnS:Ag/ 6LiF in segmented antineutrino detectors

    NASA Astrophysics Data System (ADS)

    Kiff, Scott D.; Bowden, Nathaniel; Lund, Jim; Reyna, David

    2011-10-01

    Antineutrino detection using inverse beta-decay conversion has demonstrated capability to measure nuclear reactor power and fissile material content for nuclear safeguards. Current efforts focus on aboveground deployment scenarios, for which a successful background rejection strategy will be needed to measure the anticipated antineutrino event rates. In this paper, we report on initial studies to quantify the intrinsic capture efficiency and particle identification capabilities of a new scintillation-based segmented design that uses layers of ZnS:Ag/ 6LiF to capture and identify neutrons created in the inverse beta-decay reaction. Laboratory efficiency measurements are consistent with MCNP5 calculations, estimating 6Li neutron conversion efficiency above 50% for practical full-scale detector configurations.

  16. Non-thermal processes in standard big bang nucleosynthesis: II. Two-body disintegration of D, 7Li, 7Be nuclei by fast neutrons

    NASA Astrophysics Data System (ADS)

    Voronchev, Victor T.; Nakamura, Makoto; Nakao, Yasuyuki

    2009-05-01

    Continuing the analysis of non-thermal effects in standard big bang nucleosynthesis (JCAP05(2008)010), we examine the role of suprathermal nuclear reactions induced in the early universe plasma by energetic nucleons of various origins. The processes of present interest are break-ups of D, 7Li, 7Be nuclei induced by 14-MeV neutrons generated in the plasma via the T(d, n)4He reaction. It is shown that this reaction forms the ensemble of fast neutrons whose fraction in the plasma neutron component is at the level of 0.01 %. In spite of the small percentage, such neutrons can effectively destroy the loosely bound D, 7Li, 7Be nuclei. It is found that at temperatures T9 < 0.8 the n-induced non-thermal break-ups of D and 7Li dominate over other reactions occurring in the n+D and n+7Li systems. However, the non-thermal neutronic effects prove to be insufficiently strong to modify the standard picture of nucleosynthesis. The D, 3He, 4He abundances are obtained to remain unchanged, and only a little effect is marked for primordial 7Li. The 0.01 % fraction of plasma neutrons (fast DT neutrons) reduces the 7Li abundance by 0.02 %.

  17. Population of Nuclei Via 7Li-Induced Binary Reactions

    SciTech Connect

    Clark, Rodney M.; Phair, Larry W.; Descovich, M.; Cromaz, Mario; Deleplanque, M.A.; Fall on, Paul; Lee, I-Yang; Macchiavelli, A.O.; McMahan, Margaret A.; Moretto, Luciano G.; Rodriguez-Vieitez, E.; Sinha,Shrabani; Stephens, Frank S.; Ward, David; Wiedeking, Mathis

    2005-08-08

    The authors have investigated the population of nuclei formed in binary reactions involving {sup 7}Li beams on targets of {sup 160}Gd and {sup 184}W. The {sup 7}Li + {sup 184}W data were taken in the first experiment using the LIBERACE Ge-array in combination with the STARS Si {Delta}E-E telescope system at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. By using the Wilczynski binary transfer model, in combination with a standard evaporation model, they are able to reproduce the experimental results. This is a useful method for predicting the population of neutron-rich heavy nuclei formed in binary reactions involving beams of weakly bound nuclei formed in binary reactions involving beams of weakly bound nuclei and will be of use in future spectroscopic studies.

  18. Population of Nuclei Via 7Li-Induced Binary Reactions

    SciTech Connect

    Clark, R M; Phair, L W; Descovich, M; Cromaz, M; Deleplanque, M A; Fallon, P; Lee, I Y; Macchiavelli, A O; McMahan, M A; Moretto, L G; Rodriguez-Vieitez, E; Sinha, S; Stephens, F S; Ward, D; Wiedeking, M; Bernstein, L A; Burke, J T; Church, J A

    2005-08-09

    The authors have investigated the population of nuclei formed in binary reactions involving {sup 7}Li beams on targets of {sup 160}Gd and {sup 184}W. The {sup 7}Li + {sup 184}W data were taken in the first experiment using the LIBERACE Ge-array in combination with the STARS Si {Delta}E-E telescope system at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. By using the Wilczynski binary transfer model, in combination with a standard evaporation model, they are able to reproduce the experimental results. This is a useful method for predicting the population of neutron-rich heavy nuclei formed in binary reactions involving beams of weakly bound nuclei and will be of use in future spectroscopic studies.

  19. Note: {sup 6}Li III light intensity observation for {sup 6}Li{sup 3+} ion beam operation at Hyper-Electron Cyclotron Resonance ion source

    SciTech Connect

    Muto, Hideshi; Ohshiro, Yukimitsu; Yamaka, Shoichi; Yamaguchi, Hidetoshi; Shimoura, Susumu; Watanabe, Shin-ichi; Oyaizu, Michihiro; Kobayashi, Kiyoshi; Kotaka, Yasuteru; Nishimura, Makoto; Kase, Masayuki; Kubono, Shigeru; Hattori, Toshiyuki

    2014-12-15

    The light intensity of {sup 6}Li III line spectrum at λ = 516.7 nm was observed during {sup 6}Li{sup 3+} beam tuning at the Hyper-Electron Cyclotron Resonance (ECR) ion source. Separation of ion species of the same charge to mass ratio with an electromagnetic mass analyzer is known to be an exceptionally complex process. However, {sup 6}Li III line intensity observation conducted in this study gives new insights into its simplification of this process. The light intensity of {sup 6}Li III line spectrum from the ECR plasma was found to have a strong correlation with the extracted {sup 6}Li{sup 3+} beam intensity from the RIKEN Azimuthal Varying Field cyclotron.

  20. Analyzing powers for ^12C(^6Li,d) at E(^6Li) = 50 MeV

    NASA Astrophysics Data System (ADS)

    Drummer, T. L.; Bartosz, E. E.; Cathers, P. D.; Fauerbach, M.; Kemper, K. W.; Myers, E. G.; Rusek, K.

    1998-04-01

    A complete set of analyzing powers (iT_11, T_20, T_21, T_22 and ^TT_20) have been measured for the stripping reaction ^12C(^6Li,d) at E(^6Li) = 50 MeV. At this energy, only states that have ``well known'' α + ^12C structures are strongly populated. Both DWBA and very detailed coupled reaction channels calculations have been performed to study the sensitivity of the extracted α spectroscopic factors to assumptions made regarding the coupling between states in the different projectile, target and ejectile inelastic channels. The coupled channels calculations were performed using the computer code FRESCO written by Ian Thompson running on Pentium PCs using the operating system Linux. The vector analyzing powers are almost totally determined by the deuteron spin-orbit potentials. DWBA and CCBA calculations both describe the data quite well. The extracted ground state spectroscopic factors are the same within 20% when previous data from 34 MeV(Data taken with C.R. Brune, H.J. Karwowski, E.J. Ludwig, A.J. Mendez, K.D. Veal and B. Kozlowska, University of North Carolina.) are analyzied with the present data. Supported by the National Science Foundation, the State of Florida and the State Committee for Scientific Research (KBN) of Poland.

  1. A Cluster Model of ^6He and ^6Li

    NASA Astrophysics Data System (ADS)

    Armstrong, Jeremy; Sakharuk, Alexander; Zelevinsky, Vladimir

    2007-10-01

    Small nuclei provide an ideal testing ground of few-body theories. ^6He is particularly interesting in that it shows an extended particle distribution similar to a halo nucleus, is loosely bound, and is a Borromean system. We apply the Brink Formalism in secondary quantization to study the structure of ^6He. This formalism allows for the proper treatment of Fermi statistics and correct projection into eigenstates of angular momentum. The alpha plus dineutron configuration and ``cigar'' (neutron, alpha, neutron chain) configuration were studied to obtain binding energies, charge radii, matter radii, and B(E2) for ^6He. The same configurations were used to obtain the same observables for ^6Li. We were then able to calculate the log ft value for the beta decay of ^6He. We now examine the effects of different nucleon-nucleon interactions on our systems.

  2. Experimental Progress in a 6Li-133Cs Atomic Mixture

    NASA Astrophysics Data System (ADS)

    Feng, Lei; Johansen, Jacob; Parker, Colin; Chin, Cheng

    2015-05-01

    We report experimental progress in a mixture of 6Li and 133Cs. The mass imbalance of this system results in a particular challenge, as gravity has a significant influence on Cs position, but not on Li, separating the two gases at temperatures on the order of 200 nK. We overcome this difficulty using a two color optical dipole trap. We demonstrate mixing of these species below 100 nK in preparation for studies of quantum degenerate mixtures of this system. We further report on progress toward degeneracy and many-body physics measurements in this trap. Finally, we consider Efimov physics in this system, studying the effects of Cs-Cs interaction on the spectrum of LiCsCs trimers by a comparison of Feshbach resonances at 843 and 889 G. This work is supported by NSF and Chicago MRSEC.

  3. Efimov Physics in a 6Li-133Cs Atomic Mixture

    NASA Astrophysics Data System (ADS)

    Johansen, Jacob; Feng, Lei; Parker, Colin; Chin, Cheng; Wang, Yujun

    2015-05-01

    We investigate Efimov physics based on three-body recombination in an atomic mixture of 6Li and 133Cs in the vicinity of interspecies Feshbach resonances at 843 and 889 G. This allows us to compare the loss spectra near different resonances and test the universality of Efimov states. Theoretically the Efimov spectrum near 889 G is expected to be similar to that near 843 G, except that the first resonance is absent near the former Feshbach resonance. This is due to the difference in the Cs-Cs scattering length near the two resonances: At 843 G it is negative, whereas at 889 G it is positive. Although it is primarily the Li-Cs interactions that lead to Efimov resonances, the Cs-Cs scattering length is expected to influence the spectrum. This work is supported by NSF and Chicago MRSEC.

  4. All-optical production of 6Li quantum gases

    NASA Astrophysics Data System (ADS)

    Burchianti, A.; Seman, J. A.; Valtolina, G.; Morales, A.; Inguscio, M.; Zaccanti, M.; Roati, G.

    2015-03-01

    We report efficient production of quantum gases of 6Li using a sub-Doppler cooling scheme based on the D1 transition. After loading in a standard magneto-optical trap, an atomic sample of 109 atoms is cooled at a temperature of 40 μK by a bichromatic D1 gray-molasses. More than 2×107 atoms are then transferred into a high-intensity optical dipole trap, where a two-spin state mixture is evaporatively cooled down to quantum degeneracy. We observe that D1 cooling remains effective in the deep trapping potential, allowing an effective increase of the atomic phase-space density before starting the evaporation. In a total experimental cycle of 11 s, we produce weakly-interacting degenerate Fermi gases of 7×105 atoms at T/TF < 0.1 and molecular Bose-Einstein condensates of up 5×105 molecules. We further describe a simple and compact optical system both for high-resolution imaging and for imprinting a thin optical barrier on the atomic cloud; this represents a first step towards the study of quantum tunneling in strongly interacting superfluid Fermi gases.

  5. Production cross section of At radionuclides from 7Li+natPb and 9Be+natTl reactions

    NASA Astrophysics Data System (ADS)

    Maiti, Moumita; Lahiri, Susanta

    2011-12-01

    Earlier we reported theoretical studies on the probable production of astatine radionuclides from 6,7Li- and 9Be-induced reactions on natural lead and thallium targets, respectively. The production of astatine radionuclides were investigated experimentally with two heavy-ion-induced reactions: 9Be + natTl and 7Li + natPb. Formation cross sections of the evaporation residues, 207,208,209,210At, produced in the (HI,xn) channel, were measured by the stacked-foil technique followed by off-line γ spectrometry at low incident energies (<50 MeV). Measured excitation functions were interpreted in terms of a compound nuclear reaction mechanism using Weisskopf-Ewing and Hauser-Feshbach models. Measured cross-section values are lower than the respective theoretical predictions.

  6. Neutron characterization study for D-T, p-7Li neutron sources with new BCA based direct collision coupling method

    NASA Astrophysics Data System (ADS)

    Wang, Guan-bo; Yang, Xin; Qian, Da-zhi; Li, Run-dong; Tang, Bin

    2014-09-01

    The T(D,n)4He and 7Li(p,n)7Be neutron sources have been used for decades in nuclear physics research, stellar nucleosynthesis research and neutron therapy research. In this work, the neutron characterization including neutron yield, spectra, and angular distribution for D-T and p-7Li sources have been studied with our new binary collision approximation (BCA) based direct collision coupling method. Distinguished from the traditional path integration method for getting the neutron weight, the new model establishes a relationship between the scattering cross section and the impact parameter, which allows the secondary neutron generation carrying out jointly with ions BCA tracking. The experimental measurements of neutron characterizations have been employed for these two reactions, and the new algorithm is validated.

  7. Fragmentation of {sup 7}Li relativistic nuclei on a proton into the {sup 3}H + {sup 4}He channel

    SciTech Connect

    Peresadko, N. G.; Alexandrov, Yu. A. Gerasimov, S. G.; Dronov, V. A.; Larionova, V. G.; Pisetskaya, A. V.; Tamm, E. I.; Fetisov, V. N.; Kharlamov, S. P.; Shesterkina, L. N.

    2010-11-15

    In a track nuclear photoemulsion exposed to a beam of {sup 7}Li nuclei accelerated to a momentum of 3 GeV/c per nucleon at the synchrophasotron of the Joint Institute for Nuclear Research (JINR, Dubna), 13 events in which {sup 7}Li nuclei interacting with protons break up into {sup 3}H and {sup 4}He fragments were detected among 3730 inelastic-interaction events. For this fragmentation channel, the cross section was found to be 8 {+-} 2 mb. The average value of the fragment total transverse momentum was 214 {+-} 5 MeV/c. This value exceeds markedly the average value of the transverse-momentum transfer in the coherent dissociation of {sup 7}Li nuclei on track-emulsion nuclei (166{+-}5MeV/c). The recoil-proton transverse momentum was on average 98% of the total proton momentum. The longitudinal-momentum distribution of protons was characterized by a variance of 16 MeV/c and a mean value of 37 {+-} 2MeV/c.

  8. 7Li NMR study of normal human erythrocytes

    NASA Astrophysics Data System (ADS)

    Pettegrew, J. W.; Post, J. F. M.; Panchalingam, K.; Withers, G.; Woessner, D. E.

    The biological action of lithium is of great interest because of the therapeutic efficacy of the cation in manic-depressive illness. To investigate possible molecular interactions of lithium, 7Li NMR studies were conducted on normal human erythrocytes which had been incubated with lithium chloride. The uptake of lithium ions was followed by 7Li NMR, using a dysprosium, tripolyphosphate shift reagent. Lithium uptake followed single-exponential kinetics with a time constant of 14.7 h. The intracellular lithium relaxation times were T 1 ⋍ 5 s and T 2 ⋍ 0.15 s, which implies a lengthening of the lithium correlation time. It was found that lithium does not interact significantly with hemoglobin, the erythrocyte membrane, or artificial phospholipid membranes. Based on measurements of lithium T1 and T2 in concentrated agar gels, the large difference between T1 and T2 for intracellular lithium ions may be due to diffusion of the hydrated lithium ion through heterogeneous electrostatic field gradients created by the erythrocyte membrane-associated cytoskeletal network. Lithium binding to the membrane-associated cytoskeleton, however, cannot be ruled out. Because of the large differences between T1 and T2 of intracellular lithium ions, 1Li NMR may be a sensitive and promising noninvasive method to probe the intracellular environment.

  9. Metastable charged sparticles and the cosmological {sup 7}Li problem

    SciTech Connect

    Cyburt, Richard H.; Ellis, John; Luo, Feng; Fields, Brian D.; Olive, Keith A.; Spanos, Vassilis C. E-mail: John.Ellis@cern.ch E-mail: feng.luo@kcl.ac.uk E-mail: spanos@inp.demokritos.gr

    2012-12-01

    We consider the effects of metastable charged sparticles on Big-Bang Nucleosynthesis (BBN), including bound-state reaction rates and chemical effects. We make a new analysis of the bound states of negatively-charged massive particles with the light nuclei most prominent in BBN, and present a new code to track their abundances, paying particular attention to that of {sup 7}Li. Assuming, as an example, that the gravitino is the lightest supersymmetric particle (LSP), and that the lighter stau slepton, τ-tilde {sub 1}, is the metastable next-to-lightest sparticle within the constrained minimal supersymmetric extension of the Standard Model (CMSSM), we analyze the possible effects on the standard BBN abundances of τ-tilde {sub 1} bound states and decays for representative values of the gravitino mass. Taking into account the constraint on the CMSSM parameter space imposed by the discovery of the Higgs boson at the LHC, we delineate regions in which the fit to the measured light-element abundances is as good as in standard BBN. We also identify regions of the CMSSM parameter space in which the bound state properties, chemistry and decays of metastable charged sparticles can solve the cosmological {sup 7}Li problem.

  10. The crystal structure of ^7Li2ND

    NASA Astrophysics Data System (ADS)

    Tsubota, Masami; Sorby, Magnus H.; Hino, Satoshi; Ichikawa, Takayuki; Hauback, Bjorn C.; Kojima, Yoshitsugu

    2008-03-01

    Recently much attention has been given to reversible hydrogen storage materials possessing high gravimetric capacity. Lithium amide/imide systems are promising candidates. Chen et al.[1] found that a mixture of lithium amide and lithium hydride can reversibly store hydrogen up to 6.5 mass% forming lithium imide (Li2NH). Among them, the crystal structure of Li2NH is still controversial. Balogh et al.[2] have reported a cubic structure model. However, this model differs significantly from theoretical structure models. In this work, the crystal structure of the isotopically substituted ^7Li2ND has been investigated by powder neutron and synchrotron X-ray diffraction experiments. In our data some peaks, which should be a single peak for cubic symmetry, were obviously split indicating a lower symmetry than cubic for lithium imide. The structure of ^7Li2ND will be described. [1] P. Chen et al., J. Phys. Chem. B 107 (2003) 10967. [2] M.P. Balogh et al., J. Alloys Compd. 420 (2006) 326.

  11. The Underground Nuclear Astrophysics in the Precision Era of BBN: Present Results and Future Perspectives

    NASA Astrophysics Data System (ADS)

    Gustavino, C.

    2016-01-01

    The abundance of light isotopes such as D, 3He, 4He, 6Li and 7Li produced during Big Bang Nucleosynthesis (BBN) only depends on particle physics, baryon density and relevant nuclear processes. At BBN energies (0.01 ÷ 1 MeV) the cross section of many BBN processes is very low because of the Coulomb repulsion between the interacting nuclei. As low-energy measurements on earth's surface are predominantly hampered by the effects of cosmic rays in the detectors, it is convenient to study the relevant reactions with facilities operating deep underground. Starting from the present uncertainty of the relevant parameters in BBN (i.e. baryon density, observed abundance of isotopes and nuclear cross-sections), it will be shown that the study of several reactions of the BBN chain, with existing or proposed underground accelerator facilities, can improve the accuracy of BBN calculations, providing a powerful tool to constrain astrophysics, cosmology and particle physics. In particular, a precise measurement of D(p, γ)3He reaction at BBN energies is of primary importance to calculate the baryon density of universe with an accuracy similar to the one obtained by Cosmic Microwave Background (CMB) experiments, and to constrain the number of active neutrino species. For what concern the so called ’’Lithium problems”, i.e. the disagreement between computed and observed abundances of the 7Li and 6Li isotopes, it will be also shown the importance of a renewed study of the D(α, γ) 6Li reaction.

  12. 7Li-induced reactions for fast-timing with LaBr3:Ce detectors

    NASA Astrophysics Data System (ADS)

    Mason, P. J. R.; Podolyàk, Zs.; Mǎrginean, N.; Regan, P. H.; Alexander, T.; Algora, A.; Alharbi, T.; Bowry, M.; Britton, R.; Bucurescu, D.; Bruce, A. M.; Bunce, M.; Cǎta-Danil, G.; Cǎta-Danil, I.; Cooper, N.; Deleanu, D.; Delion, D.; Filipescu, D.; Gelletly, W.; Glodariu, T.; Gheorghe, I.; Ghiťǎ, D.; Ilie, G.; Ivanova, D.; Kisyov, S.; Lalkovski, S.; Lica, R.; Liddick, S. N.; Mǎrginean, R.; Mihai, C.; Mulholland, K.; Negret, A.; Nita, C. R.; Rice, S.; Roberts, O. J.; Sava, T.; Smith, J. F.; Söderström, P.-A.; Stevenson, P. D.; Stroe, L.; Toma, S.; Townsley, C.; Werner, V.; Wilson, E.; Wood, R. T.; Zamfir, N. V.; Zhekova, M.

    2012-10-01

    7Li induced-reactions have been used with a 186W target to populate nuclei around A˜180-190 at the National Institute of Physics and Nuclear Engineering in Bucharest, Romania. An array of high-purity germanium (HPGe) and cerium-doped lanthanum bromide (LaBr3:Ce) detectors have been used to measure sub-nanosecond half-lives with fast-timing techniques. The yrast 2+ state in 190Os was measured to be t1/2 = 375(20)ps, in excellent agreement with the literature value. The previously unreported half-life of the 564-keV state in 189Ir has also been measured and a value of t1/2 = 540(100)ps ps obtained.

  13. TLD efficiency of 7LiF for doses deposited by high-LET particles

    NASA Technical Reports Server (NTRS)

    Benton, E. R.; Frank, A. L.; Benton, E. V.

    2000-01-01

    The efficiency of 7 LiF TLDs (TLD-700) in registering dose from high-LET (> or = 10 keV/micrometers) charged particles (relative to 137Cs gamma rays) has been measured for a number of accelerated heavy ions at various particle accelerator facilities. These measured efficiency values have been compared with similar results obtained from the open literature and a dose efficiency function has been fitted to the combined data set. While it was found that the dose efficiency is not only a function of LET, but also of the charge of the incident particle, the fitted function can be used to correct the undermeasured value of dose from exposures made in mixed radiation fields where LET information is available. This LET-dependent dose efficiency function is used in our laboratory in determining total absorbed dose and dose equivalent from combined TLD and CR-39 plastic nuclear track detector measurements.

  14. The D 1Σ+ state of 7LiH

    NASA Astrophysics Data System (ADS)

    Huang, Yen-Ling; Luh, Wei-Tzou; Jeung, Gwang-Hi; Gadéa, F. Xavier

    2000-07-01

    The 7LiH D 1Σ+ excited electronic state has been observed for the first time by a pulsed optical-optical double resonance fluorescence depletion spectroscopic technique. Several rovibrational levels of the A 1Σ+ and B 1Π electronic states have been used as the intermediate states. Among 22 vibrational levels, 128 rovibrational levels have been observed. The spectral assignment is identified by the observed rotational structures and term values and by a comparison between the derived vibrational and rotational constants with the theoretical values. An ab initio adiabatic potential energy curve for the D 1Σ+ state and relevant D 1Σ+-A1Σ+ and D 1Σ+-B 1Π transition moment functions are presented. An overall measure of three different aspects, the energetics, the spectral line shape, and the transition probability, strongly favors the argument that the vibronic approach is a better approach for characterizing the excited D 1Σ+ electronic state.

  15. Reexamination of the astrophysical S factor for the {alpha}+d{yields}{sup 6}Li+{gamma} reaction

    SciTech Connect

    Mukhamedzhanov, A. M.; Blokhintsev, L. D.; Irgaziev, B. F.

    2011-05-15

    Recently, a new measurement of the {sup 6}Li (150 A MeV)dissociation in the field of {sup 208}Pb has been reported [Hammache et al., Phys. Rev. C 82, 065803 (2010)] to study the radiative capture {alpha}+d{yields}{sup 6}Li+{gamma} process. However, the dominance of the nuclear breakup over the Coulomb one prevented the information about the {alpha}+d{yields}{sup 6}Li+{gamma} process from being obtained from the breakup data. The astrophysical S{sub 24}(E) factor has been calculated within the {alpha}-d two-body potential model with potentials determined from the fits to the {alpha}-d elastic scattering phase shifts. However, the scattering phase shift, according to the theorem of the inverse scattering problem, does not provide a unique {alpha}-d bound-state potential, which is the most crucial input when calculating the S{sub 24}(E) astrophysical factor at astrophysical energies. In this work, we emphasize the important role of the asymptotic normalization coefficient (ANC) for {sup 6}Li{yields}{alpha}+d, which controls the overall normalization of the peripheral {alpha}+d{yields}{sup 6}Li+{gamma} process and is determined by the adopted {alpha}-d bound-state potential. Since the potential determined from the elastic scattering data fit is not unique, the same is true for the ANC generated by the adopted potential. However, a unique ANC can be found directly from the elastic scattering phase shift, without invoking intermediate potential, by extrapolation the scattering phase shift to the bound-state pole [Blokhintsev et al., Phys. Rev. C 48, 2390 (1993)]. We demonstrate that the ANC previously determined from the {alpha}-d elastic scattering s-wave phase shift [Blokhintsev et al., Phys. Rev. C 48, 2390 (1993)], confirmed by ab initio calculations, gives S{sub 24}(E), which at low energies is about 38% less than the other one reported [Hammache et al., Phys. Rev. C 82, 065803 (2010)]. We recalculate also the reaction rates, which are lower than those obtained in

  16. {sup 16}O resonances near 4α threshold through {sup 12}C({sup 6}Li,d) reaction

    SciTech Connect

    Rodrigues, M. R. D.; Borello-Lewin, T.; Miyake, H.; Horodynski-Matsushigue, L. B.; Duarte, J. L. M.; Rodrigues, C. L.; Faria, P. Neto de; Cunsolo, A.; Cappuzzello, F.; Foti, A.; Agodi, C.; Cavallaro, M.; Napoli, M. di; Ukita, G. M.

    2014-11-11

    Several narrow alpha resonant {sup 16}O states were detected through the {sup 12}C({sup 6}Li,d) reaction, in the range of 13.5 to 17.5 MeV of excitation energy. The reaction was measured at a bombarding energy of 25.5 MeV employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion technique. Experimental angular distributions associated with natural parity quasi-bound states around the 4α threshold are presented and compared to DWBA predictions. The upper limit for the resonance widths obtained is near the energy resolution (15 keV)

  17. Spectroscopic characterization of the first singlet (Ã 1B1) excited state of 7Li16O7Li

    NASA Astrophysics Data System (ADS)

    Bellert, D.; Winn, D. K.; Breckenridge, W. H.

    2003-11-01

    Using laser induced fluorescence (LIF) and resonance enhanced two-photon ionization (R2PI) spectroscopy, several (ν1',ν2',ν3') vibrational bands of the à 1B1(K'=1)←X˜ 1Σg+(0,0,0) perpendicular transition of the 7Li16O7Li molecule have been rotationally resolved and analyzed to yield effective A',B',C' values. The estimated geometry of the à 1B1 state does not vary with ν1' (symmetric stretch mode), but θ' increases and R' decreases slightly as ν2' (bending mode) increases. Extrapolation leads to an estimate for the (0,0,0) state of θ0'=105±5°, R0'=1.86±0.04 Å, and for the potential minimum θe'=102±5°, Re'=1.87±0.04 Å. The strongly bent nature of the à 1B1 state is due to promotion of an O-2 p-electron (b1) from the strongly ionic, linear Li+O-2Li+ ground state to an a1 molecular orbital which has Li/Li bonding character. The Ã1B1 state thus has an approximately Li+1/2O-1Li+1/2 charge distribution, so that the ionic bonding is less strong than in the linear ground state, where (from this study and an earlier stimulation-emission pumping study) R0″=1.611±0.003 Å. In fact, the Li-Li distance in the à 1B1 state, ˜3.0 Å, is quite similar to that of the Li2+1 ion, so the bonding may be described as that of Li2+1 bound ionically to the O-1 ion.

  18. First determination of the 8Li valence neutron asymptotic normalization coefficient using the 7Li(8Li,7Li)8Li reaction

    NASA Astrophysics Data System (ADS)

    Howell, D.; Davids, B.; Greene, J. P.; Kanungo, R.; Mythili, S.; Ruiz, C.; Ruprecht, G.; Thompson, I. J.

    2013-08-01

    We report here a determination of the asymptotic normalization coefficient of the valence neutron in 8Li from a measurement of the angular distribution of the 7Li(8Li,7Li)8Li reaction at 11 MeV. Using isospin symmetry the 8B ANC has also been calculated and used to infer a value for S17(0) of 20.2 ± 4.4 eV b.

  19. Influence of the {alpha}-d motion in {sup 6}Li on Trojan horse applications

    SciTech Connect

    Pizzone, R.G.; Spitaleri, C.; Cherubini, S.; La Cognata, M.; Lamia, L.; Musumarra, A.; Romano, S.; Tumino, A.; Tudisco, S.; Miljanic, D.; Typel, S.

    2005-05-01

    The {alpha}-d cluster structure of {sup 6}Li has been extensively investigated in the past few decades. In particular the width of the {alpha} momentum distribution in {sup 6}Li has been studied as a function of the transferred momentum. These investigations are now reviewed and updated after recent experiments. Trojan horse method applications are also discussed because the momentum distribution of the spectator particle inside the Trojan horse nucleus is a necessary input for this method. The impact of the width (FWHM) variation in the extraction of the astrophysical S(E) factor is discussed for the {sup 6}Li(d,{alpha}){sup 4}He reaction.

  20. /sup 14/C(/sup 6/Li,t)/sup 17/O reaction at E(/sup 6/Li) = 34 MeV

    SciTech Connect

    Cunsolo, A.; Foti, A.; Imme, G.; Pappalardo, G.; Raciti, G.; Saunier, N.

    1981-11-01

    Energy spectra and angular distributions of tritons from the /sup 14/C(/sup 6/Li,t)/sup 17/O reaction have been measured at 34 MeV /sup 6/Li incident enegy and between theta/sub lab/ = 5/sup 0/ and 45/sup 0/. The observed selectivity and the forward peaked angular distributions suggest a predominantly direct reaction mechanism. /sup 17/O states with main 3p-2h configuration are tentatively identified. The experimental data have been analyzed in terms of Hauser-Feshbach and exact-finite-range distorted-wave Born approximation theories. /sup 3/He spectroscopic strengths are extracted.

  1. Use of 7Li(p,n) reaction as a neutron source in a PGNAA setup.

    PubMed

    Naqvi, A A; Nagadi, M M

    2005-03-01

    The performance of a 7Li(p,n) reaction-based Prompt Gamma Ray Neutron Activation Analysis (PGNAA) setup has been determined for analysis of Portland cement samples using Monte Carlo study. The calculations were carried out for a 7Li(p,n) reaction-based PGNAA setup with an external moderator similar to the one used in a previous 2.8 MeV neutrons-based PGNAA setup. The optimum values of geometry parameters of the 7Li(p,n) reaction-based setup are different from those of the 2.8 MeV neutrons-based setup resulting in better performance of the 7Li(p,n) reaction-based setup. The prompt gamma-ray yield from the 7Li(p,n) reaction-based setup is 60-70% higher than that from the 2.8 MeV neutrons-based setup. Although the performances of the 7Li(p,n) reaction-based setup is comparable with that of a previously studied 3H(p,n) reaction-based setup, yet performance of the 7Li(p,n) reaction-based setup is superior to that of the 3H(p,n) reaction-based setup because it has less radiation hazard due to utilization of non-radioactive neutron producing target. This study has provided a theoretical base for experimental test of a 7Li(p,n) reaction-based PGNAA setup. PMID:15607917

  2. Prospects of lithium enrichment on 7Li isotope by method of controlled ions electro-migration

    NASA Astrophysics Data System (ADS)

    Martoyan, G. A.; Kalugin, M. M.; Gabrielyan, A. V.; Martoyan, A. G.

    2016-01-01

    This paper deals with a new electro-membrane method of enrichment of 7Li isotope. The data are presented on the importance and application fields regarding the use of 7Li isotopes. Existing methods and criteria of separation of lithium isotopes are discussed. The principle of new technology, regimes of enrichment experiments, and analysis details of obtained products are briefly described.

  3. Determining the 6Li doped side of a glass scintillator for ultra cold neutrons

    NASA Astrophysics Data System (ADS)

    Jamieson, Blair; Rebenitsch, Lori Ann

    2015-08-01

    Ultracold neutron (UCN) detectors using two visually very similar, to the microscopic level, pieces of optically contacted cerium doped lithium glasses have been proposed for high rate UCN experiments. The chief difference between the two glass scintillators is that one side is 6Li depleted and the other side 6Li doped. This note outlines a method to determine which side of the glass stack is doped with 6Li using AmBe and 252Cf neutron sources, and a Si surface barrier detector. The method sees an excess of events around the α and triton energies of neutron capture on 6Li when the enriched side is facing the Si surface barrier detector.

  4. Basic technology for 6Li enrichment using an ionic-liquid impregnated organic membrane

    NASA Astrophysics Data System (ADS)

    Hoshino, Tsuyoshi; Terai, Takayuki

    2011-10-01

    The tritium needed as a fuel for fusion reactors is produced by the neutron capture reaction of lithium-6 ( 6Li) in tritium breeding materials. However, natural Li contains only about 7.6 at.% 6Li. In this paper, a new lithium isotope separation technique using an ionic-liquid impregnated organic membrane is proposed. In order to separate and concentrate lithium isotopes, only lithium ions are able to move through the membrane by electrodialysis between the cathode and the anode in lithium solutions. Preliminary experiments of lithium isotope separation were conducted using this phenomenon. Organic membranes impregnated with TMPA-TFSI and PP13-TFSI as ionic liquids were prepared, and the relationship between the 6Li separation coefficient and the applied electrodialytic conditions was evaluated using them. The results showed that the 6Li isotope separation coefficient in this method (about 1.1-1.4) was larger than that in the mercury amalgam method (about 1.06).

  5. Non-Gaussian error distribution of 7Li abundance measurements

    NASA Astrophysics Data System (ADS)

    Crandall, Sara; Houston, Stephen; Ratra, Bharat

    2015-07-01

    We construct the error distribution of 7Li abundance measurements for 66 observations (with error bars) used by Spite et al. (2012) that give A(Li) = 2.21 ± 0.065 (median and 1σ symmetrized error). This error distribution is somewhat non-Gaussian, with larger probability in the tails than is predicted by a Gaussian distribution. The 95.4% confidence limits are 3.0σ in terms of the quoted errors. We fit the data to four commonly used distributions: Gaussian, Cauchy, Student’s t and double exponential with the center of the distribution found with both weighted mean and median statistics. It is reasonably well described by a widened n = 8 Student’s t distribution. Assuming Gaussianity, the observed A(Li) is 6.5σ away from that expected from standard Big Bang Nucleosynthesis (BBN) given the Planck observations. Accounting for the non-Gaussianity of the observed A(Li) error distribution reduces the discrepancy to 4.9σ, which is still significant.

  6. Studies of the Efimov Effect in 7 Li

    NASA Astrophysics Data System (ADS)

    Luo, D.; Nguyen, J. H. V.; Hulet, R. G.

    2016-05-01

    Ultracold atomic gases provide an ideal environment to study few body physics in the universal regime. Passive techniques, such as monitoring loss of the atomic sample while varying the hold time allows us to explore properties such as the scaling behavior of Efimov trimers. In our experiment, we explore how the Efimov states are affected by non-zero temperature. We measure the three-body loss rate for a 7 Li atom gas at different scattering lengths and extract the location and width of an Efimov recombination minimum for various temperatures. Alternatively, we may perform more active experiments such as creating dimers using RF-field modulation as a probe of molecular binding energies. We use RF-association to form Feshbach dimers and Efimov trimers, and find a strong enhancement of the dimer formation rate at the atom-dimer resonance, which could be explained by an avalanche mechanism. In the past the enhancement in the three-body recombination rate at the same location had also been observed, and attributed to the avalanche. We explore the link between these findings with a side-by-side comparison of the dimer-formation rate and the three-body loss rate. Work supported by the NSF, an ARO MURI Grant, and the Welch Foundation.

  7. ( sup 6 Li, sup 6 He) measurements as an alternative calibration for solar neutrino detectors

    SciTech Connect

    Aschenauer, E.; Dennert, H.; Eyrich, W.; Lehmann, A.; Moosburger, M.; Wirth, H. ); Gils, H.J.; Rebel, H.; Zagromski, S. )

    1991-12-01

    The ({sup 6}Li,{sup 6}He) reaction was studied on the nuclei {sup 37}Cl and {sup 71}Ga at {ital E}{sub 6Li}=156 MeV at extreme forward angles including zero degree. Gamow-Teller strength and the corresponding {ital B}(GT) values were extracted. It is shown that these measurements provide an alternative method to calibrate solar neutrino detectors.

  8. 6LiF oleic acid capped nanoparticles entrapment in siloxanes for thermal neutron detection

    NASA Astrophysics Data System (ADS)

    Carturan, S.; Maggioni, G.; Marchi, T.; Gramegna, F.; Cinausero, M.; Quaranta, A.; Palma, M. Dalla

    2016-07-01

    The good light output of siloxane based scintillators as displayed under γ-rays and α particles has been exploited here to obtain clear and reliable response toward thermal neutrons. Sensitization towards thermal neutrons has been pursued by adding 6LiF, in form of nanoparticles. Aiming at the enhancement of compatibility between the inorganic nanoparticles and the low polarity, siloxane based surrounding medium, oleic acid-capped 6LiF nanoparticles have been synthesized by thermal decomposition of Li trifluoroacetate. Thin pellets siloxane scintillator maintained their optical transmittance up to weight load of 2% of 6Li. Thin samples with increasing 6Li concentration and thicker ones with fixed 6Li amount have been prepared and tested with several sources (α, γ-rays, moderated neutrons). Light output as high as 80% of EJ212 under α irradiation was measured with thin samples, and negligible changes have been observed as a result of 6LiF addition. In case of thick samples, severe light loss has been observed, as induced by opacity. Nevertheless, thermal neutrons detection has been assessed and the data have been compared with GS20, based on Li glass, taken as a reference material.

  9. On 7LI Enrichment by Low-Mass Metal-Poor Red Giant Branch Stars

    NASA Astrophysics Data System (ADS)

    de la Reza, Ramiro; da Silva, Licio; Drake, Natalia A.; Terra, Marco A.

    2000-06-01

    First-ascent red giants with strong and very strong Li lines have just been discovered in globular clusters. Using the stellar internal prompt 7Li enrichment-mass-loss scenario, we explore the possibility of 7Li enrichment in the interstellar matter of the globular cluster M3 produced by these Li-rich giants. We found that enrichment as large as 70% or more compared to the initial 7Li content of M3 can be obtained during the entire life of this cluster. However, because M3 will cross into the Galactic plane several times, the new 7Li will be very probably removed by ram pressure into the disk. Globular clusters appear then as possible new sources of 7Li in the Galactic disk. It is also suggested that the known Na/Al variations in stars of globular clusters could be somehow related to the 7Li variations and that the cool bottom process mixing mechanism acting in the case of 7Li could also play a role in the case of Na and Al surface enrichments.

  10. Nucleon and triton production from nucleon-induced reactions on 7Li

    NASA Astrophysics Data System (ADS)

    Watanabe, Yukinobu; Guo, Hairui; Nagaoka, Kohei; Matsumoto, Takuma; Ogata, Kazuyuki; Yahiro, Masanobu

    2016-06-01

    Nucleon (N) and triton production from nucleon-induced reactions on 7Li at an incident energy of 14 MeV are analyzed by using three-body continuum discretized coupled channels method (CDCC), final state interaction (FSI) model, and sequential decay (SD) model. The CDCC is used to describe nucleon and triton production via breakup continuum channels, 7Li(N,N')7Li*→ t + α. Triton production from p(n) + 7Li → t + 5Li(5He) channel and nucleon production from sequential decay of the ground-state 5Li(5He) are calculated by the FSI model and the SD model, respectively. The calculated double differential cross sections for both nucleon and triton production are in good agreement with experimental ones except at relatively low nucleon emission energies.

  11. Thermal neutron calibration of a tritium extraction facility using the /sup 6/Li(n,t)/sup 4/He//sup 197/Au(n,. gamma. )/sup 198/Au cross section ratio for standardization

    SciTech Connect

    Bretscher, M.M.; Smith, D.L.

    1980-08-01

    Absolute tritium activities in a neutron-activated metallic lithium samples have been measured by liquid scintillation methods to provide data needed for the determination of capture-to-fission ratios in fast breeder reactor spectra and for recent measurements of the /sup 7/Li(n,n't)/sup 4/He cross section. The tritium extraction facility used for all these experiments has now been calibrated by measuring the /sup 6/Li(n,t)/sup 4/He//sup 197/Au/n,..gamma..)/sup 198/Au activity ratio for thermal neutrons and comparing the result with the well-known cross sections. The calculated-to-measured activity ratio was found to be 1.033 +- 0.018. 2 figures, 20 tables.

  12. Triply degenerate quantum mixture of 41K, 40K and 6Li

    NASA Astrophysics Data System (ADS)

    Wu, Cheng-Hsun; Santiago, Ibon; Park, Jee Woo; Ahmadi, Peyman; Zwierlein, Martin

    2011-05-01

    We report the observation of a triply quantum degenerate mixture of 41K, 40K and 6Li atoms. It is demonstrated that bosonic 41K atom is an efficient coolant for sympathetic cooling of fermionic 40K and 6Li atoms. We also present our investigation of 41K and 40K, a Bose-Fermi mixture where a 12 G s-wave resonance is observed. Negligible differential gravitational sag between potassium isotopes makes this resonance an excellent candidate for studying unexplored properties of Bose- Fermi mixtures. The 40K and 6Li mixture provides access to strongly correlated Fermi-Fermi mixtures with imbalanced masses. This work was supported by the NSF, AFOSR-MURI, AFOSR-YIP, ARO-MURI, a grant from the Army Research Office with funding from the DARPA OLE program, the David and Lucille Packard Foundation and the Alfred P. Sloan Foundation.

  13. Production of beams from solid materials at Center for Nuclear Study electron cyclotron resonance ion source

    NASA Astrophysics Data System (ADS)

    Ohshiro, Y.; Yamaka, S.; Watanabe, S.; Kobayashi, K.; Kotaka, Y.; Nishimura, M.; Kase, M.; Muto, H.; Yamaguchi, H.; Shimoura, S.

    2014-02-01

    Two methods for the feed of vapor from solid materials in the Center for Nuclear Study ECR ion source are described. A rod placed near the wall of the plasma chamber, operating up to a melting point of 2600 °C, has been used for CaO, SiO2, and FeO. An oven with a number of openings, operating up to 800 °C, has been used for P2O5, Li, and S. Typical ion beam intensities of 7Li2+, 6Li3+, 40Ca12+, and 56Fe15+ are achieved 280, 75, 28, and 7 eμA, respectively. High intensity heavy ion beams are stably supplied into the azimuthally varying field cyclotron.

  14. Alpha-particle scattering from sup 6 Li near the. alpha. - d breakup threshold

    SciTech Connect

    Samanta, C.; Ghosh, S.; Lahiri, M. ); Ray, S. ); Banerjee, S.R. )

    1992-04-01

    The {sup 6}Li({alpha},{alpha}{prime}) reaction was studied at {ital E}{sub {alpha}}=50 MeV. The angular distribution of the continuum region near the {sup 6}Li{r arrow}{alpha}+{ital d} breakup threshold (1.475 MeV) was measured for {theta}{sub lab}=7{degree}--40{degree}. The data were analyzed in terms of plane-wave and distorted-wave impulse approximation calculations. To study the possible effects of recombination of the breakup clusters in the exit channel, distorted-wave Born approximation calculations were also performed.

  15. Properties of 4He and 6Li with improved chiral EFT interactions

    NASA Astrophysics Data System (ADS)

    Maris, P.; Binder, S.; Calci, A.; Epelbaum, E.; Furnstahl, R. J.; Golak, J.; Hebeler, K.; Kamada, H.; Krebs, H.; Langhammer, J.; Liebig, S.; Meißner, U.-G.; Minossi, D.; Nogga, A.; Potter, H.; Roth, R.; Skibiński, R.; Topolnicki, K.; Vary, J. P.; Witala, H.

    2016-03-01

    We present recent results for 4He and 6Li obtained with improved NN interactions derived from chiral effective field theory up to N4LO. The many-body calculations are performed order-by-order in the chiral expansion. At N3LO and N4LO additional renormalization using the Similarity Renormalization Group is adopted to improve numerical convergence of the many-body calculations. We discuss results for the ground state energies, as well as the magnetic moment and the low-lying spectrum of 6Li.

  16. Supertransferred hyperfine fields at {sup 7}Li: Variable temperature {sup 7}Li NMR studies of LiMn{sub 2}O{sub 4}-based spinels

    SciTech Connect

    Gee, B.; Horne, C.R.; Cairns, E.J.; Reimer, J.A. |

    1998-12-10

    The temperature dependence of the {sup 7}Li NMR shift was measured for LiMn{sub 2}O{sub 4}, LiMn{sub 2{minus}y}Ni{sub y}O{sub 4} (y = 0.1, 0.25, 0.33), LiMn{sub 2{minus}y}Co{sub y}O{sub 4} (y = 0.25, 0.5, 1.0), Li[Mn{sub 2{minus}y}Li{sub y}]O{sub 4} (y = 0.1, 0.33), and {lambda}-MnO{sub 2} spinel oxides. The {sup 7}Li NMR shift can be separated into temperature-independent and -dependent components. The temperature-dependent shift follows the Curie-Weiss behavior of the bulk magnetic susceptibility. The temperature-independent shift is attributed to contributions from van Vleck and diamagnetic susceptibilities. Pauli susceptibility may also contribute to the temperature-independent shift in the nickel- and cobalt-substituted spinels. Supertransferred hyperfine (STH) coupling constants were derived from the {sup 7}Li NMR shifts and bulk magnetic susceptibility data. The progressive increase in average nominal manganese oxidation state from +3.5 to +4 results in an increase in the supertransferred hyperfine field at the {sup 7}Li nucleus in the lithium-substituted samples. Replacement of manganese by either cobalt or nickel also results in a larger STH field at the {sup 7}Li nuclei. The increase in STH field for the lithium-, nickel-, and cobalt-substituted spinel oxides may arise from a greater covalence in these materials relative to the parent LiMn{sub 2}O{sub 4} spinel oxide.

  17. Processes controlling δ7Li in rivers illuminated by study of streams and groundwaters draining basalts

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Ming; Wanner, Christoph; Rudnick, Roberta L.; McDonough, William F.

    2015-01-01

    We evaluate the factors influencing the abundance, [Li], and isotopic composition of riverine Li delivered to the oceans through analyses and modeling of [Li] and δ7Li in streams and groundwaters draining a single continental lithology, the Columbia River Basalts (CRBs). The streams were sampled in different climate zones that lie east (dry), and west (wet) of the Cascades Mountains, and during two different seasons (summer and late winter) in order to evaluate climatic and seasonal influences on Li isotopes in rivers. Dissolved Li (δLi7dis = + 9.3 to +30.4) is systematically heavier than that of fresh or weathered CRBs (-4.7 to +6.0, Liu et al., 2013), suspended loads (-5.9 to -0.3), and shallow groundwaters (+6.7 to +9.4), consistent with previous studies showing that Li isotope fractionation is affected by equilibration between stream water and secondary minerals. However, the lack of correlation between δ7Lidis and climate zone, the uniform secondary minerals and bedrock, coupled with the highly variable (> 20 ‰) δLi7dis indicate that other factors exert a strong control on δ7Lidis. In particular, the heavier Li in streams compared to the shallow groundwaters that feed them indicates that continued isotopic fractionation between stream water and suspended and/or bed loads has a major influence on riverine δ7Li. Seasonal δ7Li variation is observed only for streams west of the Cascades, where the difference in precipitation rate between the dry and wet seasons is greatest. Reactive transport model simulations reveal that riverine δ7Li is strongly controlled by subsurface residence times and the Li isotope fractionation occurring within rivers. The latter explains why there is no positive correlation between δ7Li and traditional weathering proxies such as Si or normalized Si in rivers, as riverine Li isotope fractionation drives δ7Li to higher values during transport, whereas the concentrations of major cations and anions are diluted. The varying

  18. 6Li-loaded directionally sensitive anti-neutrino detector for possible geo-neutrinographic imaging applications

    NASA Astrophysics Data System (ADS)

    Tanaka, H. K. M.; Watanabe, H.

    2014-04-01

    Despite the latent and unique benefits of imaging uranium and thorium's distribution in the earth's interior, previously proposed experimental techniques used to identify the incoming geo-neutrino's direction are not applicable to practical imaging due to the high miss-identification in a neutrino's track reconstruction. After performing experimental studies and Monte-Carlo simulations, we confirmed that a significant improvement is possible in neutrino tracking identification with a 6Li-loaded neutrino detector. For possible imaging applications, we also explore the feasibility of producing geo-neutrinographic images of gigantic magmatic reservoirs and deep structure in the mantle. We anticipate and plan to apply these newly designed detectors to radiographic imaging of the Earth's interior, monitoring of nuclear reactors, and tracking astrophysical sources of neutrinos.

  19. 6Li-loaded directionally sensitive anti-neutrino detector for possible geo-neutrinographic imaging applications

    PubMed Central

    Tanaka, H. K. M.; Watanabe, H.

    2014-01-01

    Despite the latent and unique benefits of imaging uranium and thorium's distribution in the earth's interior, previously proposed experimental techniques used to identify the incoming geo-neutrino's direction are not applicable to practical imaging due to the high miss-identification in a neutrino's track reconstruction. After performing experimental studies and Monte-Carlo simulations, we confirmed that a significant improvement is possible in neutrino tracking identification with a 6Li-loaded neutrino detector. For possible imaging applications, we also explore the feasibility of producing geo-neutrinographic images of gigantic magmatic reservoirs and deep structure in the mantle. We anticipate and plan to apply these newly designed detectors to radiographic imaging of the Earth's interior, monitoring of nuclear reactors, and tracking astrophysical sources of neutrinos. PMID:24759616

  20. Reexamining closed-form formulae for inclusive breakup: Application to deuteron- and 6Li-induced reactions

    NASA Astrophysics Data System (ADS)

    Lei, Jin; Moro, A. M.

    2015-10-01

    The problem of the calculation of inclusive breakup cross sections in nuclear reactions is reexamined. For that purpose, the post-form theory proposed by Ichimura, Austern, and Vincent [Phys. Rev. C 32, 431 (1985), 10.1103/PhysRevC.32.431] is revisited, and an alternative derivation of the nonelastic breakup part of the inclusive breakup is presented, making use of the coupled-channels optical theorem. Using the distorted-wave Born approximation (DWBA) version of this model, several applications to deuteron and 6Li reactions are presented and compared with available data. The validity of the zero-range approximation of the DWBA formula is also investigated by comparing zero-range with full finite-range calculations.

  1. Alpha Resonances in {sup 13}C Excited by the {sup 9}Be ({sup 6}Li,d) Reaction

    SciTech Connect

    Rodrigues, M. R. D.; Borello-Lewin, T.; Horodynski-Matsushigue, L. B.; Duarte, J. L. M.; Rodrigues, C. L.; Souza, M. A.; Miyake, H.; Cunsolo, A.; Cappuzzello, F.; Ukita, G. M.

    2010-05-21

    The {sup 9}Be({sup 6}Li,d){sup 13}C reaction was used to investigate alpha resonant states in {sup 13}C up to 13 MeV of excitation. The reaction was measured at a bombarding energy of 25.5 MeV employing the Sao Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion detection technique. The resolution of 50 keV allowed for the separation of the resonant contributions to the known 7/2{sup -} at 10.753 MeV and (5/2{sup -}) at 10.818 MeV {sup 13}C states. The alpha resonance seen at the (3alpha+n) threshold was not previously reported. The experimental angular distributions are presented in comparison with DWBA predictions.

  2. A Neutron Detector Constructed Using Shards of ^6Li-loaded Glass Scintillator

    NASA Astrophysics Data System (ADS)

    Gardiner, Steven; Czirr, Bart; Rees, Lawrence

    2012-10-01

    Because of a global shortage of ^3He, an essential component of many neutron detectors, much work is currently being done to develop new neutron detectors based on alternative materials for homeland security applications. One of the possible replacements for ^3He is Ce^3+-activated, ^6Li-loaded glass scintillator. Although this material has been widely used in neutron detectors for over half a century, its relatively high gamma sensitivity has made it unattractive for use in radiation portal monitors. We have tested a new technique for reducing the gamma sensitivity of a neutron detector based on ^6Li glass. Our prototype neutron detector consists of small (about 1 mm^3) shards of ^6Li-loaded glass scintillator embedded in optical epoxy. Mineral oil is placed behind the glass and epoxy for moderation. Our tests indicate that this detector can achieve a gamma sensitivity that is at least 100 times lower than a comparable neutron detector constructed using a thin sheet of ^6Li glass. Modeling performed using the particle transport codes MCNP and PENELOPE suggests that the gamma sensitivity of the glass shards is lower because more high-energy Compton electrons escape them before depositing their full energy.

  3. Tensor analyzing powers and energy dependence of the {sup 7}Li+{sup 16}O interaction

    SciTech Connect

    Rudchik, A. T.; Rudchik, A. A.; Chesnokova, V. D.; Kyryanchuk, V. M.; Ponkratenko, O. A.; Kemper, K. W.; Crisp, A. M.; Marechal, F.; Roeder, B. T.; Momotyuk, O. A.; Rusek, K.

    2007-02-15

    The differential cross section angular distribution and the analyzing powers {sup T}T{sub 10},{sup T}T{sub 20}, for {sup 7}Li+{sup 16}O elastic scattering were measured at E{sub lab}({sup 7}Li(vector sign)) = 42 MeV. These and previously published {sup 7}Li+{sup 16}O scattering data measured at E{sub c.m.} = 6.26-34.78 MeV were analyzed with the optical model and coupled-reaction channels (CRC) methods to determine the energy dependence of the parameters of the scattering potential. It was found that the optical model potentials are energy independent for {sup 7}Li laboratory bombarding energies above 28 MeV, except for a slight decrease in the real potential strength as the bombarding energy increases. The calculations presented show that the tensor analyzing power {sup T}T{sub 20} arises from a coherent combination of contributions from the ground-state reorientation and central scattering potential. The energy-dependent CRC potentials were shown to describe the data for the {sup 16}O({sup 7}Li,t){sup 20}Ne reaction.

  4. The dipole moment of 7LiH and 7LiD in the excited A 1Σ + state: A test of the born-oppenheimer approximation

    NASA Astrophysics Data System (ADS)

    Brieger, M.; Renn, A.; Sodeik, A.; Hese, A.

    1983-02-01

    Continuing our Stark quantum beat experiments on 7LiH at electric field strengths of 100 kV/cm and above, we were le to observe quantum beat signals for the vibrational level v' = 5 of the A 1v+ state. The evaluation of these signals yields a field reduced splitting Δ W/ E2 = 1.157(70) kHz/(kV/cm) 2 which would correspond to an "effective" value of 1μ eff( v' = 5)1 = 0.051 (5) D for the dipole moment, if the ordinarily used formula were applicable. A serious check of all available data, however, shows that neighbouring vibrational levels of the A 1v+ state and also the sum over the levels of the electronic ground state X 1Σ +, though counteracting, have the main effect on the residual splitting thus preventing a straightforward evaluation for the dipole moment. Taking account of these polarizability effects and including the possibility for a slight shift of the theoretical dipole moment function a value of 1μ( v' = 5)1 = 0.089(14) D is the most probable one. In the case of 7LiD according to the usual formula an "effective" value of 1μ eff( v' = 6)1 = 0.425(20) D was deduced from a beat signal obtained at an electric field strength of 24 kV/cm. Here the influence of neighbouring vibrational levels and electronic states is only of minor importance leading to a corrected value of 1μ( v' = 6)1 = 0.43(2) D for the dipole moment. This value differs by 13% from the theoretical one calculated on the basis of the dipole moment function of 7LiH and the adiabatically corrected potential energy curve of 7LiD, thus indicating non-adiabatic effects.

  5. Lithium Visibility in Rat Brain and Muscle in Vivoby 7Li NMR Imaging

    NASA Astrophysics Data System (ADS)

    Komoroski, Richard A.; Pearce, John M.; Newton, Joseph E. O.

    1998-07-01

    The apparent concentration of lithium (Li)in vivowas determined for several regions in the brain and muscle of rats by7Li NMR imaging at 4.7 T with inclusion of an external standard of known concentration and visibility. The average apparent concentrations were 10.1 mM for muscle, and 4.2-5.3 mM for various brain regions under the dosing conditions used. The results were compared to concentrations determinedin vitroby high-resolution7Li NMR spectroscopy of extracts of brain and muscle tissue from the same rats. The comparison provided estimates of the7Li NMR visibility of the Li cation in each tissue region. Although there was considerable scatter of the calculated visibilities among the five rats studied, the results suggested essentially full visibility (96%) for Li in muscle, and somewhat reduced visibility (74-93%) in the various brain regions.

  6. Elastic and inelastic angular distributions of the 7Li+120Sn system for energies near the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Zagatto, V. A. B.; Oliveira, J. R. B.; Gasques, L. R.; Alcántara-Núñez, J. A.; Duarte, J. G.; Aguiar, V. P.; Medina, N. H.; Seale, W. A.; Pires, K. C. C.; Freitas, A.; Lubian, J.; Shorto, J. M. B.; Genezini, F. A.; Rossi, E. S., Jr.

    2016-06-01

    The reaction of 7Li+120Sn has been measured at bombarding energies of 21, 24 and 27 MeV. The {2}+\\to {0}+ γ -ray transition in 120Sn was observed and the angular distribution for the 2+ excited state was obtained. Coupled channels and coupled-reaction channels calculations, including the dynamical polarization potential due to the projectile break-up, obtained from continuum discretized coupled channel calculations, were performed. The comparison between the existing experimental elastic angular distribution with the coupled-reaction channels calculations indicates that the 1n stripping transfer is the most intense channel to be coupled and the 2n stripping reaction occurs sequentially rather than directly, however, further data must be analyzed to confirm this indication. The experimental elastic and inelastic scattering data were well described by the calculations, but some discrepancies in these channels may indicate the need for corrections to the nuclear potential and/or the necessity to incorporate further channels.

  7. Report for in-situ 7Li NMR experiment in PNNL Phase -1

    SciTech Connect

    Hu, Jian Zhi

    2014-08-19

    To understand the detailed local structural evolution, an in-situ 7Li NMR study was performed. An operando identification of the lithium germanide phases under various cycling regimens permitted understanding of the kinetics of phase transition between different structural phases, including the amorphous phases, and how these correlated with capacity retention. Combining data from TEM and in-situ 7Li NMR, we discovered that the phase inter-conversion during cycling was mediated by co-existing amorphous and crystalline phases, and that the high capacity observed was correlated with an over-lithiated lithium germanide phase.

  8. High-resolution photoassociation spectroscopy of the 6Li2 A(11Σu+) state

    NASA Astrophysics Data System (ADS)

    Gunton, Will; Semczuk, Mariusz; Dattani, Nikesh S.; Madison, Kirk W.

    2013-12-01

    We present spectroscopic measurements of seven vibrational levels v=29-35 of the A(11Σu+) excited state of Li2 molecules by the photoassociation of a degenerate Fermi gas of 6Li atoms. The absolute uncertainty of our measurements is ±0.00002 cm-1 (±600 kHz) and we use these new data to further refine an analytic potential for this state. This work provides high accuracy photoassociation resonance locations essential for the eventual high-resolution mapping of the X(11Σg+) state enabling further improvements to the s-wave scattering length determination of Li and enabling the eventual creation of ultracold ground-state 6Li2 molecules.

  9. Investigation of the reaction D(4He, γ)6Li at ultralow energies

    NASA Astrophysics Data System (ADS)

    Burkatovskaya, Yu. B.; Bystritsky, V. M.; Dudkin, G. N.; Krylov, A. R.; Lysakov, A. S.; Gazi, S.; Huran, J.; Nechaev, B. A.; Padalko, V. N.; Sadovsky, A. B.; Tuleushev, Yu. G.; Filipowicz, M.; Philippov, A. V.

    2016-03-01

    The cross section of the reaction D(4He, γ)6Li with titanium and zirconium deuterides as targets is measured for incident 4He+ ion energies of 30 and 36 keV, respectively. The ion beam is generated by a Hall pulsed plasma accelerator. For the first time, upper limits on the cross section of the reaction D(4He, γ)6Li at ultralow energies are imposed (at 90% confidence level): σ ≤ 1.2 × 10-35 cm2 for the TiD2 target and E(4He+) = 30 keV, and σ ≤ 7 × 10-36 cm2 for the ZrD2 target and E(4He+) = 36 keV

  10. E0 strength in /sup 12/C from /sup 6/Li scattering

    SciTech Connect

    Eyrich, W.; Hofmann, A.; Lehmann, A.; Muehldorfer, B.; Schloesser, H.; Wirth, H.; Gils, H.J.; Rebel, H.; Zagromski, S.

    1987-07-01

    The (/sup 6/Li,/sup 6/Li') reaction was studied on /sup 12/C at E/sub Li/ = 156 MeV at extreme forward angles including theta = 0/sup 0/. Spectra were taken in the excitation energy region E/sub x/approx. <30 MeV. E0 strength was deduced at E/sub x/ = 7.65 MeV (9.5% energy weighted sum rule) around E/sub x/ = 10.2 MeV (5% +- 1% energy weighted sum rule) and in the region 19 MeVless than or equal toE/sub x/less than or equal to21.5 MeV (5% +- 2% energy weighted sum rule).

  11. Impact of 6Li resonances on the near-barrier elastic scattering with 144Sm

    NASA Astrophysics Data System (ADS)

    Camacho, A. Gómez; Diaz-Torres, A.; Gomes, P. R. S.; Lubian, J.

    2016-02-01

    Converged continuum discretized coupled-channel calculations of elastic-scattering differential cross sections for reactions induced by the 6Li projectile on the 144Sm target, at energies around the Coulomb barrier, are presented. The impact of the low-lying α -deuteron resonant states in 6Li (l =2 ,Jπ=3+,2+,1+ ) on those elastic angular distributions is quantified. This is done by two types of calculations, namely, (a) by omitting from the continuum energy spectrum all states where the resonances are constructed in the discretization process, and (b) by considering only the resonance discretized space. Dynamical polarization potentials are used for interpreting the effect of continuum couplings. Resonant couplings play a more significant role than nonresonance ones at back-scattering angles and at incident energies below the Coulomb barrier. However, their effect becomes weaker as the incident energy increases above the barrier energy.

  12. Thermal neutron detection using a silicon pad detector and {sup 6}LiF removable converters

    SciTech Connect

    Barbagallo, Massimo; Cosentino, Luigi; Marchetta, Carmelo; Pappalardo, Alfio; Scire, Carlotta; Scire, Sergio; Schillaci, Maria; Vecchio, Gianfranco; Finocchiaro, Paolo; Forcina, Vittorio; Peerani, Paolo; Vaccaro, Stefano

    2013-03-15

    A semiconductor detector coupled with a neutron converter is a good candidate for neutron detection, especially for its compactness and reliability if compared with other devices, such as {sup 3}He tubes, even though its intrinsic efficiency is rather lower. In this paper we show a neutron detector design consisting of a 3 cm Multiplication-Sign 3 cm silicon pad detector coupled with one or two external {sup 6}LiF layers, enriched in {sup 6}Li at 95%, placed in contact with the Si active surfaces. This prototype, first characterized and tested at INFN Laboratori Nazionali del Sud and then at JRC Ispra, was successfully shown to detect thermal neutrons with the expected efficiency and an outstanding gamma rejection capability.

  13. Deuteron scattering on {sup 6}Li at an energy of 25 MeV

    SciTech Connect

    Burtebayev, N.; Artemov, S. V.; Duisebayev, B. A.; Kerimkulov, Zh. K.; Kuranov, S. B.; Sakuta, S. B.

    2010-05-15

    At an energy of 25 MeV and in the angular range 7{sup o}-175{sup o} in the laboratory frame, angular distributions were measured for elastic deuteron scattering on {sup 6}Li nuclei and for the respective inelastic-scattering processes accompanied by the transitions to the ground state (1+) of the {sup 6}Li nucleus and to its excited state at E{sub x} = 2.186 MeV (J{sup {pi}} = 3{sup +}). The resulting data were analyzed on the basis of the optical model of the nucleus and the coupled-reaction-channel method with allowance for the mechanism of alpha-particle-cluster exchange. It is shown that only upon including, in the analysis, channel coupling and the exchange mechanism can the experimental cross sections for elastic and inelastic scattering be reproduced over the entire range of angles.

  14. First Tests of 6Li Doped Glass Scintillators for Ultracold Neutron Detection

    PubMed Central

    Ban, G.; Fléchard, X.; Labalme, M.; Lefort, T.; Liénard, E.; Naviliat-Cuncic, O.; Fierlinger, P.; Kirch, K.; Bodek, K.; Geltenbort, P.

    2005-01-01

    We report the results of test measurements aimed at determining the performances of 6Li doped glass scintillators for the detection of ultra-cold neutrons. Four types of scintillators, GS1, GS3, GS10 and GS20, which differ by their 6Li concentrations, have been tested. The signal to background separation is fully acceptable. The relative detection efficiencies have been determined as a function of the neutron velocity. We find that GS10 has a higher efficiency than the others for the detection of neutrons with velocities below 7 m/s. Two pieces of scintillators have been irradiated with a high flux of cold neutrons to test the radiation hardness of the glasses. No reduction in the pulse height has been observed up to an absorbed neutron dose of 1 × 1013 cm−3. PMID:27308137

  15. Electron-scattering form factors for 6Li in the ab initio symmetry-guided framework

    NASA Astrophysics Data System (ADS)

    Dytrych, T.; Hayes, A. C.; Launey, K. D.; Draayer, J. P.; Maris, P.; Vary, J. P.; Langr, D.; Oberhuber, T.

    2015-02-01

    We present an ab initio symmetry-adapted no-core shell-model description for 6Li. We study the structure of the ground state of 6Li and the impact of the symmetry-guided space selection on the charge density components for this state in momentum space, including the effect of higher shells. We accomplish this by investigating the electron scattering charge form factor for momentum transfers up to q ˜4 fm-1 . We demonstrate that this symmetry-adapted framework can achieve significantly reduced dimensions for equivalent large shell-model spaces while retaining the accuracy of the form factor for any momentum transfer. These new results confirm the previous outcomes for selected spectroscopy observables in light nuclei, such as binding energies, excitation energies, electromagnetic moments, E 2 and M 1 reduced transition probabilities, as well as point-nucleon matter rms radii.

  16. Understanding the effect of channel coupling on fusion of 6Li+64Ni

    NASA Astrophysics Data System (ADS)

    Moin Shaikh, Md.; Roy, Subinit

    2016-07-01

    The effect of inelastic excitation and single particle transfer reactions on fusion have been investigated for the system 6Li+64Ni at near barrier energies. The calculations show that a simultaneous coupling to the inelastic excitation of projectile and target along with positive Q-value 1n- and 1p-stripping channels, describes the experimental CF cross sections reasonably well in the below barrier region.

  17. ( sup 6 Li, sup 6 He) reaction and Gamow-Teller. beta. decay

    SciTech Connect

    Moosburger, M.; Aschenauer, E.; Dennert, H.; Eyrich, W.; Lehmann, A.; Rudeloff, R.; Schloesser, H.; Wirth, H. ); Gils, H.J.; Rebel, H.; Zagromski, S. )

    1990-06-01

    The ({sup 6}Li,{sup 6}He) reaction was studied on targets of {sup 12}C, {sup 18}O, {sup 26}Mg, and {sup 42}Ca at a beam energy of 156 MeV. Zero degree measurements of all systems are presented. The evaluated cross sections for Gamow-Teller transitions at {theta}=0{degree} and the corresponding strengths of analogous beta decays are compared.

  18. Data for the neutron interactions with /sup 6/Li and /sup 10/B

    SciTech Connect

    Poenitz, W.P.

    1984-01-01

    The /sup 10/B(n,..cap alpha..), /sup 10/B(n,..cap alpha../sub 1/) and, increasingly in more recent measurement, the /sup 6/Li(n,..cap alpha..) cross sections are the major references used in low energy experiments. Many data from modern measurements are available for the neutron interaction with /sup 6/Li, including total, scattering, and absolute and relative (n,..cap alpha..) cross sections. A consensus has been reached with these new /sup 6/Li + n data. In contrast, the data base for the /sup 10/B neutron interaction cross sections is unfortunately poor. This is even the case for the total cross section which is supposed to be the easiest quantity to be measured. The most serious deficiency is the absence of data from absolute measurements of the /sup 10/B(n,..cap alpha..) and /sup 10/B(n,..cap alpha../sub 1/) cross sections in the last 10 to 15 years. The available cross section data which were used for the ENDF/B-VI evaluation will be discussed. 43 references.

  19. BEC of 41 K in a Fermi sea of 6 Li

    NASA Astrophysics Data System (ADS)

    Lous, Rianne S.; Fritsche, Isabella; Huang, Bo; Jag, Michael; Cetina, Marko; Walraven, Jook T. M.; Grimm, Rudolf

    2016-05-01

    We report on the production of a 41 K Bose-Einstein condensate (BEC) immersed in a degenerate two-component 6 Li Fermi sea. After evaporation in an optical dipole trap, we obtain 1 . 2 ×104 41 K atoms with a 55% BEC fraction and a Fermi sea with T /TF < 0 . 1 , consisting of 1 . 8 ×105 6 Li atoms in each of the lowest two spin states. This opens the way to study the collective behavior of a mass-imbalanced mixture of two coupled superfluids. The double-degenerate Fermi-Bose mixture also enables the study of interacting bosonic impurities in a Fermi sea. Using loss spectroscopy, we observe the 335 . 8G Feshbach resonance, which is comparable to the one between 6 Li and the fermionic 40 K isotope exploited in our previous studies on the quantum many-body dynamics of fermionic impurities in a Fermi sea. Investigating the interacting bosonic impurities enables the direct comparison of the role of quantum statistics for fermionic and bosonic impurities. This work is supported by the Austrian Science Fund FWF within the collaborative research grant FoQuS.

  20. Barrier distributions for the {sup 7}Li+{sup 27}Al reaction

    SciTech Connect

    Cardenas, W. H. Z.

    2010-08-04

    Barrier distributions can be obtained from the first derivative of the elastic and quasielastic (QEL) backward angle excitation functions [1]. In this work we present a study of the barrier distribution for the {sup 7}Li+{sup 27}Al reaction from a Coupled-Channels Born Approximation (CCBA) calculations using the code FRESCO [2].

  1. Unified description of ^{6}Li structure and deuterium-^{4}He dynamics with chiral two- and three-nucleon forces.

    PubMed

    Hupin, Guillaume; Quaglioni, Sofia; Navrátil, Petr

    2015-05-29

    We provide a unified ab initio description of the ^{6}Li ground state and elastic scattering of deuterium (d) on ^{4}He (α) using two- and three-nucleon forces from chiral effective field theory. We analyze the influence of the three-nucleon force and reveal the role of continuum degrees of freedom in shaping the low-lying spectrum of ^{6}Li. The calculation reproduces the empirical binding energy of ^{6}Li, yielding an asymptotic D- to S-state ratio of the ^{6}Li wave function in the d+α configuration of -0.027, in agreement with a determination from ^{6}Li-^{4}He elastic scattering, but overestimates the excitation energy of the 3^{+} state by 350 keV. The bulk of the computed differential cross section is in good agreement with data. These results endorse the application of the present approach to the evaluation of the ^{2}H(α,γ)^{6}Li radiative capture, responsible for the big-bang nucleosynthesis of ^{6}Li. PMID:26066431

  2. Pole approximation validation in the study of the {sup 6}Li(d,{alpha}){sup 4}He reaction

    SciTech Connect

    Pizzone, R. G.; Kiss, G. G.; Spitaleri, C.; Lamia, L.; Cherubini, S.; La Cognata, M.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Burjan, V.; Hons, Z.; Kroha, V.; Mrazek, J.; Piskor, S.; Li, C.; Tumino, A.

    2010-11-24

    The Trojan Horse Method (THM) was applied to the {sup 3}He+{sup 6}Li interaction in order to investigate the quasi-free {sup 6}Li(d,{alpha}){sup 4}He reaction. The experiment was performed at 17 MeV at the Cyclotron Institute of the Czech Academy of Science. The extracted {sup 6}Li(d,{alpha}){sup 4}He quasi-free cross-section was compared with the behavior of direct data. A good agreement between data sets shows up throughout the energy range investigated, providing a very important validity test of the pole approximation for the THM above the Coulomb barrier.

  3. Astrophysical S factor for the radiative-capture reaction p{sup 6}Li {yields} {sup 7}Be{gamma}

    SciTech Connect

    Dubovichenko, S. B.; Burtebaev, N. Zazulin, D. M.; Kerimkulov, Zh. K.; Amar, A. S. A.

    2011-07-15

    A new measurement of differential cross sections for elastic p{sup 6}Li scattering in the energy range 0.35-1.2 MeV was performed. A partial-wave analysis of the data obtained in this way was carried out, and potentials simulating the p{sup 6}Li interaction were constructed. Various experiments devoted to studying elastic p{sup 6}Li scattering over the broad energy range of 0.5-50 MeV were analyzed on the basis of the optical model. By using the potentials obtained from the partial-wave analysis, the possibility of describing the astrophysical S factor for radiative proton capture on {sup 6}Li at low energies was considered within the potential cluster model involving forbidden states.

  4. High-resolution photoassociation spectroscopy of the 6Li2 13Σg+ state

    NASA Astrophysics Data System (ADS)

    Semczuk, Mariusz; Li, Xuan; Gunton, Will; Haw, Magnus; Dattani, Nikesh S.; Witz, Julien; Mills, Arthur K.; Jones, David J.; Madison, Kirk W.

    2013-05-01

    We present experimental observations of seven vibrational levels, v'=20-26, of the 13Σg+ excited state of Li2 molecules by the photoassociation (PA) of a degenerate Fermi gas of 6Li atoms. For each vibrational level, we resolve the rotational structure using a Feshbach resonance to enhance the PA rates from p-wave collisions. We also determine the spin-spin and spin-rotation interaction constants for this state. The absolute uncertainty of our measurements is ±0.00002 cm-1 (±600 kHz). We use this data to further refine an analytic potential for this state.

  5. Elastic scattering for the system {sup 6}Li+p at near barrier energies with MAGNEX

    SciTech Connect

    Soukeras, V.; Pakou, A.; Sgouros, O.; Cappuzzello, F.; Bondi, M.; Nicolosi, D.; Acosta, L.; Marquinez-Duran, G.; Martel, I.; Agodi, C.; Carbone, D.; Cavallaro, M.; Cunsolo, A.; Di Pietro, A.; Fernández-García, J. P.; Figuera, P.; Fisichella, M.; Alamanos, N.; De Napoli, M.; Foti, A.; and others

    2015-02-24

    Elastic scattering measurements have been performed for the {sup 6}Li+p system in inverse kinematics at the energies of 16, 20, 25 and 29 MeV. The heavy ejectile was detected by the large acceptance MAGNEX spectrometer at the Laboratori Nazionali del Sud (LNS) in Catania, in the angular range between ∼2{sup 0} and 12{sup 0} in the laboratory system, giving us the possibility to span almost a full angular range in the center of mass system. Results will be presented and discussed for one of the energies.

  6. Comparative analysis of pulse shape discrimination methods in a 6Li loaded plastic scintillator

    NASA Astrophysics Data System (ADS)

    Balmer, Matthew J. I.; Gamage, Kelum A. A.; Taylor, Graeme C.

    2015-07-01

    Three algorithms for discriminating between fast neutrons, thermal neutrons and gamma rays in a 6Li loaded plastic scintillator have been compared. Following a literature review of existing pulse shape discrimination techniques, the performance of the charge comparison method, triangular filtering and frequency gradient analysis were investigated in this work. The scintillator was exposed to three different mixed gamma/neutron radiation fields. The figure of merit of neutron/gamma separation was investigated over a broad energy range, as well as for the neutron capture energy region. After optimisation, all three methods were found to perform similarly in terms of neutron/gamma separation.

  7. Neutron detector based on Particles of 6Li glass scintillator dispersed in organic lightguide matrix

    NASA Astrophysics Data System (ADS)

    Ianakiev, K. D.; Hehlen, M. P.; Swinhoe, M. T.; Favalli, A.; Iliev, M. L.; Lin, T. C.; Bennett, B. L.; Barker, M. T.

    2015-06-01

    Most 3He replacement neutron detector technologies today have overlapping neutron-gamma pulse-height distributions, which limits their usefulness and performance. Different techniques are used to mitigate this shortcoming, including Pulse Shape Discrimination (PSD) or threshold settings that suppress all gammas as well as much of the neutrons. As a result, count rates are limited and dead times are high when PSD is used, and the detection efficiency for neutron events is reduced due to the high threshold. This is a problem in most applications where the neutron-gamma separation of 3He detectors had been essential. This challenge is especially severe for neutron coincidence and multiplicity measurements that have numerous conflicting requirements such as high detection efficiency, short die-away time, short dead time, and high stability. 6Li-glass scintillators have excellent light output and a single peak distribution, but they are difficult to implement because of their gamma sensitivity. The idea of reducing the gamma sensitivity of 6Li-glass scintillators by embedding small glass particles in an organic light-guide medium was first presented by L.M. Bollinger in the early 60s but, to the best of our knowledge, has never been reduced to practice. We present a proof of principle detector design and experimental data that develop this concept to a large-area neutron detector. This is achieved by using a multi-component optical medium (6Li glass particles attached to a glass supporting structure and a mineral oil light guide) which matches the indices of refraction and minimizes the absorption of the 395 nm scintillator light. The detector design comprises a 10 in. long tube with dual end readout with about 3% volume density of 6Li glass particles installed. The presented experimental data with various neutron and gamma sources show the desired wide gap between the neutron and gamma pulse height distributions, resulting in a true plateau in the counting

  8. Excitation of giant monopole resonance in {sup 24}Mg using {sup 6}Li scattering

    SciTech Connect

    Dennert, H.; Aschenauer, E.; Eyrich, W.; Lehmann, A.; Moosburger, M.; Scholz, N.; Wirth, H.; Gils, H.J.; Rebel, H.; Zagromski, S.

    1995-12-01

    The isoscalar giant monopole resonance in the nucleus {sup 24}Mg was investigated by inelastic {sup 6}Li scattering at {ital E}{sub Li}=156 MeV. At extreme forward angles fragmented {ital E}0 strength was observed up to {ital E}{sub {ital x}}=23 MeV. The extracted strength centered at 18.3{plus_minus}0.5 MeV excitation energy with a width of {Gamma}=4.8{plus_minus}0.5 MeV corresponds to 97.3%{plus_minus}15% of the {ital E}0 energy weighted sum rule.

  9. Three-Body Recombination of {sup 6}Li Atoms with Large Negative Scattering Lengths

    SciTech Connect

    Braaten, Eric; Kang, Daekyoung; Platter, Lucas; Hammer, H.-W.

    2009-08-14

    The three-body recombination rate at threshold for distinguishable atoms with large negative pair scattering lengths is calculated in the zero-range approximation. The only parameters in this limit are the 3 scattering lengths and the Efimov parameter, which can be complex-valued. We provide semianalytic expressions for the cases of 2 or 3 equal scattering lengths, and we obtain numerical results for the general case of 3 different scattering lengths. Our general result is applied to the three lowest hyperfine states of {sup 6}Li atoms. Comparisons with recent experiments provide indications of loss features associated with Efimov trimers near the 3-atom threshold.

  10. Breakup threshold anomaly in the elastic scattering of {sup 6}Li on {sup 27}Al

    SciTech Connect

    Figueira, J. M.; Niello, J. O. Fernandez; Abriola, D.; Arazi, A.; Capurro, O. A.; Barbara, E. de; Marti, G. V.; Heimann, D. Martinez; Negri, A. E.; Pacheco, A. J.; Padron, I.; Gomes, P. R. S.; Lubian, J.; Correa, T.; Paes, B.

    2007-01-15

    Elastic scattering of the weakly bound {sup 6}Li on {sup 27}Al was measured at near-barrier energies. The data analysis was performed using a Woods-Saxon shape optical potential and also using the double-folding Sao Paulo potential. The results show the presence of the breakup threshold anomaly (BTA), an anomalous behavior when compared with the scattering of tightly bound nuclei. This behavior is attributed to a repulsive polarization potential produced by the coupling to the continuum breakup states.

  11. Unified description of 6Li structure and deuterium-4He dynamics with chiral two- and three-nucleon forces

    DOE PAGESBeta

    Hupin, Guillaume; Quaglioni, Sofia; Navratil, Petr

    2015-05-29

    Here, we provide a unified ab initio description of the 6Li ground state and elastic scattering of deuterium (d) on 4He (α) using two- and three-nucleon forces from chiral effective field theory. We analyze the influence of the three-nucleon force and reveal the role of continuum degrees of freedom in shaping the low-lying spectrum of 6Li. The calculation reproduces the empirical binding energy of 6Li, yielding an asymptotic D- to S-state ratio of the 6Li wave function in the d+α configuration of –0.027, in agreement with a determination from 6Li–4He elastic scattering, but overestimates the excitation energy of the 3+more » state by 350 keV. The bulk of the computed differential cross section is in good agreement with data. These results endorse the application of the present approach to the evaluation of the 2H(α,γ)6Li radiative capture, responsible for the big-bang nucleosynthesis of 6Li.« less

  12. Neutron total and scattering cross sections of /sup 6/Li in the few MeV region

    SciTech Connect

    Smith, A.; Guenther, P.; Whalen, J.

    1980-02-01

    Neutron total cross sections of /sup 6/Li are measured from approx. 0.5 to approx. 4.8 MeV at intervals of approx.< 10 keV. Neutron differential elastic-scattering cross sections are measured from 1.5 to 4.0 MeV at approx.> 10 scattering angles and at incident-neutron intervals of approx.< 100 keV. Neutron differential inelastic-scattering cross sections are measured in the incident-energy range 3.5 to 4.0 MeV. The experimental results are extended to lower energies using measured neutron total cross sections recently reported elsewhere by the authors. The composite experimental data (total cross sections from 0.1 to 4.8 MeV and scattering cross sections from 0.22 to 4.0 MeV) are interpreted in terms of a simple two-level R-matrix model which describes the observed cross sections and implies the reaction cross section in unobserved channels; notably the (n;..cap alpha..)t reaction (Q = 4.783 MeV). The experimental and calculational results are compared with previously reported results as summarized in the ENDF/B-V evaluated nuclear data file.

  13. Experimental signatures for distinguishing breakup fusion and transfer in {sup 7}Li+{sup 165}Ho

    SciTech Connect

    Tripathi, V.; Navin, A.; Mahata, K.; Ramachandran, K.; Shrivastava, A.; Chatterjee, A.; Kailas, S.; Nanal, V.; Pillay, R.G.

    2005-07-01

    Reactions involving weakly bound nuclei of {sup 7}Li show large yields of {alpha} particles that have their origin in elastic breakup, breakup followed by fusion, or triton transfer. The latter two processes, breakup fusion and transfer, have similar characteristics and produce the same residual fragments. We report here results of exclusive measurements of charged particles and characteristic {gamma} rays from the heavy residues in the {sup 7}Li+{sup 165}Ho system at 42 MeV (E/V{sub b}{approx_equal}1.6) to look for experimental signatures to differentiate between transfer and breakup fusion. Such a distinction is essential for a better theoretical understanding of both the fusion process and direct reactions involving weakly bound stable and unstable beams.

  14. Coupled channel effect in elastic scattering and fusion for 6,7Li+28Si

    NASA Astrophysics Data System (ADS)

    Sinha, Mandira; Roy, Subinit; Basu, P.; Majumdar, H.; Santra, S.; Parkar, V. V.; Golda, K. S.; Kailas, S.

    2011-10-01

    The fusion excitation and elastic angular distribution were measured for 6,7Li+28Si from below to above Coulomb barrier (≤ 3Vb) energies. The barrier distribution derived from the fusion data was found to be broad and asymmetric at the sub-barrier region, compared to 1D BPM estimation. Effect of rotational coupling on fusion was found to be not so dominant. Phenomenological optical potential parameters, with surface and volume type imaginary potentials, were obtained from f tting of elastic scattering data and energy dependence of real and imaginary surface strengths were investigated around the barrier. CDCC calculations considering only breakup of projectile were performed for 6,7Li+28Si with the elastic scattering data, using the code FRESCO. The effects of breakup of projectile on elastic cross section do not agree with the energy dependence of real and imaginary strength with volume type imaginary potential around the barrier.

  15. New measurement of the 10B(n,α)7 Li through the Trojan Horse Method

    NASA Astrophysics Data System (ADS)

    Spartá, Roberta

    2016-04-01

    B(n,α) Li reaction cross section has been measured using the Trojan Horse method, with the specific aim to separate the α1 contribution (coming from the first Li excited level) by the αo (related to the Li ground state), using a very thin target. Preliminary results are shown of the three-body B(d,α7 Li)H cross section.

  16. Exploring Light Neutron Rich Nuclei via the ({sup 7}Li,{sup 7}Be) Reaction

    SciTech Connect

    Cavallaro, M.; Cappuzzello, F.; Cunsolo, A.; Foti, A.; Orrigo, S. E. A.; Rodrigues, M. R. D.; Borello-Lewin, T.; Lenske, H.; Petrascu, H.; Winfield, J. S.

    2008-11-11

    A systematic study of the nuclei that can be described as an integer number of {alpha} particles plus three neutrons via the ({sup 7}Li,{sup 7}Be) reaction at about 8 MeV/u has shown the presence of Bound States Embedded in the Continuum in the energy spectra. These are experimental signatures of the dynamical correlations of an easily polarizable core with a single-particle state of the valence neutron.

  17. ^7Li BEC in a millimeter-scale Ioffe-Pritchard trap

    NASA Astrophysics Data System (ADS)

    Liu, Mingchang; Wang, Ruquan; Minardi, Francesco; Kasevich, Mark

    2006-05-01

    A millimeter-scale Ioffe-Pritchard type magnetic trap with excellent optical access has been used to demonstrate Bose-Einstein condensation in^ 7Li. The trap utilizes a novel combination of free space and substrate patterned current carrying elements to produce the required fields. Substrate electrodes are fabricated with using the direct-bond copper (DBC) process on a ceramic substrate. DBC fabrication enables excellent thermal dissipation together with high current capacity vias and surface conductors. With 100A trapping current, which dissipates less than 10W the trap provides 400G/Cm magnetic gradient in the radial direction, 50Hz trapping frequency in axial direction and 80G trap depth for ^7Li. With conventional water cooling, lifetime for the trap is over 1 minute and BEC regime is reached after 35s forced evaporation. The demonstrated performance for ^7Li is expected to scale well to other alkalis and this compact configuration may serve as an excellent platform for mobile ultra-cold atom sensors.

  18. 4T 7Li 3D MRSI in the brains of bipolar disorder subjects

    PubMed Central

    Lee, Jing-Huei; Adler, Caleb; Norris, Matthew; Chu, Wen-Jang; Fugate, Elizabeth M; Strakowski, Stephen M.; Komoroski, Richard A.

    2012-01-01

    This work demonstrates the first whole brain “high spatial resolution” 7Li MRSI in bipolar disorder subjects. The in vivo quantification is validated by a phantom containing 5 mM lithium salt using the identical RF sequence and imaging protocol. This study is the first demonstration of the 7Li distribution in the brain of bipolar disorder patients on lithium therapy using a 3D MRSI approach. The results show that brain lithium level is strongly correlated with serum lithium concentration. The brain-to-serum lithium ratio for the average brain and the local maximum were 0.39 ± 0.08 (r = 0.93) and 0.92 ± 0.16 (r= 0.90), respectively. The lithium distribution is found to be non-uniform throughout the brain for all patients, which is somewhat unexpected and highly intriguing. This uneven distribution is more evident in subjects at a higher therapeutic serum lithium level. This finding may suggest that lithium targets specific brain tissues and/or certain enzymatic and macromolecular sites that are associated with therapeutic effect. Further investigations of bipolar disorder patients on lithium therapy using 3D 7Li MRSI are warranted. PMID:22692991

  19. Limits to T/TF and progress towards ultracold ^6Li-^87Rb mixtures

    NASA Astrophysics Data System (ADS)

    Brown-Hayes, Michael; Wei, Qun; Kim, Woo-Joong; Presilla, Carlo; Onofrio, Roberto

    2007-03-01

    Ultracold dilute atomic gases are providing a new window into quantum physics, with particular regard to the first-principle study of superfluid phenomena. Fermionic degeneracy (measured by T/TF) achieved with current apparata using sympathetic cooling techniques seems to be limited by the heat capacity matching between the Fermi and Bose species and by Fermi-hole heating. We will discuss these factors and report on the development of an apparatus for simultaneous trapping and cooling of ^6Li and ^87Rb, using a light-assisted magnetic trap. The ^6Li and ^87Rb species combination, in conjunction with the improvement in heat capacity matching, should allow for an improved lower limit to attainable temperatures in Fermi-Bose mixtures. We also report on seemingly opposite approaches to reaching a lower T/TF and suggest the differences are due to two distinct measures of cooling efficiency. M. Brown-Hayes and R. Onofrio, Phys. Rev. A 70, 063614 (2004). R. Côt'e, R. Onofrio, E. Timmermans, Phys. Rev. A 72, 041605(R) (2005).

  20. Probing the cluster structure of 7Li via elastic scattering on protons and deuterons in inverse kinematics

    NASA Astrophysics Data System (ADS)

    Pakou, A.; Soukeras, V.; Cappuzzello, F.; Acosta, L.; Agodi, C.; Aslanoglou, X.; Calabrese, S.; Carbone, D.; Cavallaro, M.; Foti, A.; Keeley, N.; Marquinez-Duran, G.; Martel, I.; Mazzocco, M.; Parascandolo, C.; Pierroutsakou, D.; Rusek, K.; Sgouros, O.; Strano, E.; Zagatto, V. A. B.

    2016-07-01

    Elastic scattering measurements were performed for the 7Li+p system in inverse kinematics at energies of 16, 25, 35, and 38.1 MeV and for the 7Li+d system at 38.1 MeV. The heavy ejectiles were detected by the large acceptance MAGNEX spectrometer at the Laboratori Nazionali del Sud in Catania, Italy. The results are analyzed using the Jeukenne-Lejeune-Mahaux and continuum discretized coupled channel frameworks. In the latter case the cluster structure of 7Li proves to be critical for the theoretical interpretation of the experimental results.

  1. Effects of distortion of the intercluster motion in {sup 2}H, {sup 3}He, {sup 3}H, {sup 6}Li, and {sup 9}Be on Trojan horse applications

    SciTech Connect

    Pizzone, R. G.; Spitaleri, C.; La Cognata, M.; Lamia, L.; Romano, S.; Mukhamedzhanov, A. M.; Blokhintsev, L. D.; Bertulani, C. A.; Irgaziev, B. F.

    2009-08-15

    Deuteron induced quasifree scattering and reactions have been extensively investigated in the past few decades as well as {sup 6}Li, {sup 3}H, {sup 3}He, and {sup 9}Be induced reactions. This was done not only for the investigation of nuclear structure and reaction mechanisms but also for important astrophysical applications (Trojan horse method). In particular the widths of the spectator momentum distributions in several nuclei, which have been used as Trojan horses, have been obtained as a function of the transferred momentum. Applications of Trojan horse method will also be discussed because the momentum distribution of the spectator particle inside the nucleus is a important input for this method. This gives hints on distortion effects at low energies important for nuclear astrophysics.

  2. Study the Effects of Mechanical Activation on Li-N-H Systems With 1H and 6Li Solid-State NMR

    SciTech Connect

    Lu, Chun; Hu, Jian Zhi; Kwak, Ja Hun; Yang, Z Gary; Ren, Ruiming; Markmaitree, Tippawan; Shaw, Leonard D.

    2007-07-10

    To gain insight into the effects of mechanical activation (MA) on the hydrogen desorption of the lithium amide (LiNH2) and lithium hydride (LiH) mixture, LiNH2 and LiH+LiNH2 were mechanically activated by high-energy ball milling. The formed products were studied with in situ 1H and 6Li nuclear magic angle spinning (MAS) magnetic resonance (NMR) spectroscopy from ambient temperature to 180 degrees C. Up-field chemical shift was observed in 6Li MAS NMR spectra with increased milling time, indicating that average local electronic structure around Li nuclei was modified during MA. 1H MAS NMR was used to dynamically probe ammonia release from the activated LiNH2 at temperature as low as 50 degrees C. In the case of activated LiH+LiNH2 mixtures, the 1H MAS NMR results implied that MA enhanced the dehydrogenation reaction of LiNH2+LiH=Li2NH+H2 and suppressed ammonia generation as well.

  3. Study the effects of mechanical activation on Li-N-H systems with 1H and 6Li solid-state NMR

    NASA Astrophysics Data System (ADS)

    Lu, Chun; Hu, Jianzhi; Kwak, Ja Hun; Yang, Zhenguo; Ren, Ruiming; Markmaitree, Tippawan; Shaw, Leon L.

    To gain insight into the effects of mechanical activation (MA) on the hydrogen desorption of the lithium amide (LiNH 2) and lithium hydride (LiH) mixture, LiNH 2 and LiH + LiNH 2 were mechanically activated by high-energy ball milling. The formed products were studied with in situ 1H and 6Li nuclear magic angle spinning (MAS) magnetic resonance (NMR) spectroscopy from ambient temperature to 180 °C. Up-field chemical shift was observed in 6Li MAS NMR spectra with increased milling time, indicating that average local electronic structure around Li nuclei was modified during MA. 1H MAS NMR was used to dynamically probe ammonia release from the activated LiNH 2 at temperature as low as 50 °C. In the case of activated LiH + LiNH 2 mixtures, the 1H MAS NMR results implied that MA enhanced the dehydrogenation reaction of LiNH 2 + LiH = Li 2NH + H 2.

  4. What can d7Li tell us about sources and flow pathes of river water (Western Pamir, Tajikistan)?

    NASA Astrophysics Data System (ADS)

    Meier, Christiane; Knoche, Malte; Osenbrück, Karsten; Seitz, Hans-Michael; Weise, Stephan M.

    2015-04-01

    The high alpine regions in Central Asia are the headwaters for big river systems such as the Amu Darya, which is intensively used for agricultural purposes. For the local water resources management it is important to understand the key factors and processes of runoff generation. It is assumed, that the dominant factors for runoff generation are glacier and snow melt in the Pamir Mountains. However the influence of ground water to river water is also an important factor but still not well understood. We investigated the River Gunt catchment as an exemplary catchment for the Pamir Mountains to identify the origin and to quantify the portion of ground water. Thereby we analyzed water samples of river water, subsurface water, thermal water and glacier water for 7Li. We detected a wide range of 7Li values (from +7‰ to +30‰), whereas the highest values were measured in the glacier melt water at the glacier snout (7Li = +28.8‰) which are similar to the 7Li value of sea water, the lowest values were found in the samples of thermal water and springs in solid rock (7Li between +8‰ and +11‰), the samples of river water are more or less placed on a mixing line in between. We assume that tributaries showing an isotope signature similar to the glacier ones are mainly controlled by melt water while water samples with 7Li values comparable to the 7Li values of subsurface water samples pass through the underground or have a strong interaction between river water and river bed. The water samples of the main stream Gunt also show low 7Li values so we assume a strong contribution of subsurface water to the total runoff or an intensive water-rock-interaction in its riverbed.

  5. Novel 4π Detection System for the Measurement of the 6Li(n,α)3H Reaction Cross Section

    NASA Astrophysics Data System (ADS)

    Giorginis, Georgios; Bencardino, Raffaele

    2011-12-01

    A dedicated one-dimensional Time Projection Chamber (1D-TPC) was designed and produced at IRMM to determine the 6Li(n,α)3H cross section in the 0.4-2.8 MeV energy range, aiming at 5% accuracy. The basic TPC components were a twin gridded ionisation chamber (GIC) with interwired electrodes and fast digitisation of the anode and cathode signals. The energy of both reaction products emitted from a thin 6LiF sample at the common TPC cathode was measured. A Kr(97%)CO2(3%) mixture was used as the detector gas at a pressure up to 3.5 bar. A 238U sample mounted on the cathode of an ionisation chamber without grid was used as the neutron flux monitor. Special care was taken to reduce the experimental sources of uncertainty. The beam-monitor 238U sample was characterised at IRMM by low-geometry α-counting with an accuracy of 0.1%. A 6Li sample was produced at IRMM by vacuum evaporation of 6LiF onto transparent aluminium backing. The number of 6Li atoms will be measured via Thermal Neutron Depth Profiling with an expected accuracy of 2% with respect to an IRMM Standard Reference Material. First test measurements were performed using a monoenergetic neutron beam produced by the T(p,n)3He reaction at the IRMM 7 MV Van de Graaff accelerator. The experimental method and preliminary results are presented.

  6. An Updated 6Li(p, α)3He Reaction Rate at Astrophysical Energies with the Trojan Horse Method

    NASA Astrophysics Data System (ADS)

    Lamia, L.; Spitaleri, C.; Pizzone, R. G.; Tognelli, E.; Tumino, A.; Degl'Innocenti, S.; Prada Moroni, P. G.; La Cognata, M.; Pappalardo, L.; Sergi, M. L.

    2013-05-01

    The lithium problem influencing primordial and stellar nucleosynthesis is one of the most interesting unsolved issues in astrophysics. 6Li is the most fragile of lithium's stable isotopes and is largely destroyed in most stars during the pre-main-sequence (PMS) phase. For these stars, the convective envelope easily reaches, at least at its bottom, the relatively low 6Li ignition temperature. Thus, gaining an understanding of 6Li depletion also gives hints about the extent of convective regions. For this reason, charged-particle-induced reactions in lithium have been the subject of several studies. Low-energy extrapolations of these studies provide information about both the zero-energy astrophysical S(E) factor and the electron screening potential, Ue . Thanks to recent direct measurements, new estimates of the 6Li(p, α)3He bare-nucleus S(E) factor and the corresponding Ue value have been obtained by applying the Trojan Horse method to the 2H(6Li, α 3He)n reaction in quasi-free kinematics. The calculated reaction rate covers the temperature window 0.01 to 2T 9 and its impact on the surface lithium depletion in PMS models with different masses and metallicities has been evaluated in detail by adopting an updated version of the FRANEC evolutionary code.

  7. Time-of-flight calibration of a 6Li glass epithermal neutron detector

    PubMed

    Livingston; Saleh; Block; Brand

    2000-10-01

    The curing of Portland cement concrete involves the conversion of water from a free to a bound state. The process can be monitored nondestructively by measuring the shift in the neutron energy spectrum in the epithermal range (0.025-1 eV). A tuned array of 6Li glass detectors has been constructed with varying efficiencies over the epithermal energy range. To determine the efficiency of each detector as a function of neutron energy, it is necessary to calibrate it against a reference neutron spectrum. This was accomplished using a time-of-flight approach with a pulsed neutron beam produced at the Gaerttner LINAC Laboratory at Rensselaer Polytechnic Institute. With a neutron flight path of 25 m it was possible to determine the neutron detector efficiencies to an energy resolution of 11 microeV. The data showed good agreement with the detector design calculations. PMID:11003519

  8. Thermal neutron detection by entrapping 6LiF nanocrystals in siloxane scintillators

    NASA Astrophysics Data System (ADS)

    Carturan, S. M.; Marchi, T.; Maggioni, G.; Gramegna, F.; Degerlier, M.; Cinausero, M.; Dalla Palma, M.; Quaranta, A.

    2015-06-01

    Exploiting the long experience in design and production of scintillating mixtures based on siloxane matrices with combinations of primary dye and waveshifter, a first set of 6LiF loaded scintillator disks has been produced. The synthesis is herein described and reported, as well as preliminary results on their light response towards thermal neutrons. The preservation of transparency and mechanical integrity of the scintillator material is challenging when introducing the inorganic salt LiF which is a "foreign body" to the organic polysiloxane host matrix Different strategies such as synthesis of nanoparticles and surface functionalization have been pursued to succeed in the entrapment of the neutron converter whilst maintaining moderate light output, optical transparency and flexibility of the base scintillator.

  9. Efimov physics in atom-dimer scattering of {sup 6}Li atoms

    SciTech Connect

    Hammer, H.-W.; Kang, Daekyoung; Platter, Lucas

    2010-08-15

    {sup 6}Li atoms in the three lowest hyperfine states display universal properties when the S-wave scattering length between each pair of states is large. Recent experiments reported four pronounced features arising from Efimov physics in the atom-dimer relaxation rate, namely two resonances and two local minima. We use the universal effective-field theory to calculate the atom-dimer relaxation rate at zero temperature. Our results describe the four features qualitatively and imply there is a hidden local minimum. In the vicinity of the resonance at 685 G, we perform a finite temperature calculation which improves the agreement of theory and experiment. We conclude that finite temperature effects cannot be neglected in the analysis of the experimental data.

  10. Refractive versus resonant diffraction scattering of loosely bound 6Li nuclei

    NASA Astrophysics Data System (ADS)

    Carstoiu, Florin; Trache, Livius

    2012-05-01

    We present a complete analysis of 6Li+16O elastic scattering at 4 and 5 MeV/nucleon. Using either traditional Woods-Saxon or a range of semimicroscopic folding form factors we find that the data require deep, highly transparent potentials. Physically relevant solutions are selected according to the dispersion relation. The intermediate angle structures and the oscillatory increase of the cross section at large angles are interpreted either as a pre-rainbow oscillation resulting from the interference of the barrier and internal barrier far-side scattering subamplitudes or, equally well, as a resonant diffraction arising from two Regge poles located in peripheral waves. Both semiclassical and Regge pole approaches allow a dynamical separation of the resonant component of the S matrix.

  11. Central nervous system radiation syndrome in mice from preferential 10B(n, alpha)7Li irradiation of brain vasculature.

    PubMed

    Slatkin, D N; Stoner, R D; Rosander, K M; Kalef-Ezra, J A; Laissue, J A

    1988-06-01

    Ionizing radiations were directed at the heads of anesthetized mice in doses that evoked the acute central nervous system (CNS) radiation syndrome. Irradiations were done using either a predominantly thermal neutron field at a nuclear reactor after intraperitoneal injection of 10B-enriched boric acid or 250-kilovolt-peak x-rays with and without previous intraperitoneal injection of equivalent unenriched boric acid. Since 10B concentrations were approximately equal to 3-fold higher in blood than in cerebral parenchyma during the reactor irradiations, more radiation from alpha and 7Li particles was absorbed by brain endothelial cells than by brain parenchymal cells. Comparison of the LD50 dose for CNS radiation lethality from the reactor experiments with the LD50 dose from the x-ray experiments gives results compatible with morphologic evidence that endothelial cell damage is a major determinant of acute lethality from the CNS radiation syndrome. It was also observed that boric acid is a low linear energy transfer radiation-enhancement agent in vivo. PMID:3375251

  12. Central nervous system radiation syndrome in mice from preferential 10B(n, alpha)7Li irradiation of brain vasculature.

    PubMed Central

    Slatkin, D N; Stoner, R D; Rosander, K M; Kalef-Ezra, J A; Laissue, J A

    1988-01-01

    Ionizing radiations were directed at the heads of anesthetized mice in doses that evoked the acute central nervous system (CNS) radiation syndrome. Irradiations were done using either a predominantly thermal neutron field at a nuclear reactor after intraperitoneal injection of 10B-enriched boric acid or 250-kilovolt-peak x-rays with and without previous intraperitoneal injection of equivalent unenriched boric acid. Since 10B concentrations were approximately equal to 3-fold higher in blood than in cerebral parenchyma during the reactor irradiations, more radiation from alpha and 7Li particles was absorbed by brain endothelial cells than by brain parenchymal cells. Comparison of the LD50 dose for CNS radiation lethality from the reactor experiments with the LD50 dose from the x-ray experiments gives results compatible with morphologic evidence that endothelial cell damage is a major determinant of acute lethality from the CNS radiation syndrome. It was also observed that boric acid is a low linear energy transfer radiation-enhancement agent in vivo. Images PMID:3375251

  13. {sup 7}Li NMR study of poly(p-phenylene) electrochemically doped with lithium

    SciTech Connect

    Shteinberg, V.G.; Shumm, B.A.; Zueva, A.F.

    1994-09-01

    Lithium ions in electrochemically doped poly(p-phenylene) (PPP) were studied by {sup 7}Li NMR. Two types of lithium cations exhibiting different mobility are found to exist. The fraction of more mobile cations increases with temperature but does not exceed 0.5. In the PPP{sup -}-Li{sup +} system, ion mobility is considerably lower than that found in the previously studied PPP{sup +}-AsF{sub 6}{sup -} (BF{sub 4}{sup -}) system, and up to 400 K no chemical reactions of polymer destruction occur.

  14. Beam shaping assembly optimization for (7)Li(p,n)(7)Be accelerator based BNCT.

    PubMed

    Minsky, D M; Kreiner, A J

    2014-06-01

    Within the framework of accelerator-based BNCT, a project to develop a folded Tandem-ElectroStatic-Quadrupole accelerator is under way at the Atomic Energy Commission of Argentina. The proposed accelerator is conceived to deliver a proton beam of 30mA at about 2.5MeV. In this work we explore a Beam Shaping Assembly (BSA) design based on the (7)Li(p,n)(7)Be neutron production reaction to obtain neutron beams to treat deep seated tumors. PMID:24345525

  15. Li mobility in Nasicon-type materials LiM2(PO4)3, M = Ge, Ti, Sn, Zr and Hf, followed by 7Li NMR spectroscopy.

    PubMed

    Arbi, K; París, M A; Sanz, J

    2011-10-21

    Lithium mobility in LiM(2)(PO(4))(3) compounds, M = Ge and Sn, has been investigated by (7)Li Nuclear Magnetic Resonance (NMR) spectroscopy, and deduced information compared with that reported previously in Ti, Zr and Hf members of the series in the temperature range 100-500 K. From the analysis of (7)Li NMR quadrupole interactions (C(Q) and η parameters), spin-spin T(2)(-1) and spin-lattice T(1)(-1) relaxation rates, structural sites occupancy and mobility of lithium have been deduced. Below 250 K, Li ions are preferentially located at M(1) sites in rhombohedral phases, but occupy intermediate M(12) sites between M(1) and M(2) sites in triclinic ones. In high-temperature rhombohedral phases, a superionic state is achieved when residence times at M(1) and M(12) sites become similar and correlation effects on Li motion decrease. This state can be obtained by large order-disorder transformations in rhombohedral phases or by sharp first order transitions in triclinic ones. The presence of two relaxation mechanisms in T(1)(-1) plots of rhombohedral phases has been associated with departures of conductivity from the Arrhenius behavior. Long term mobility of lithium is discussed in terms of the cation vacancy distribution along conduction paths. PMID:21897945

  16. A novel laser-collider used to produce monoenergetic 13.3 MeV 7Li (d, n) neutrons

    NASA Astrophysics Data System (ADS)

    Zhao, J. R.; Zhang, X. P.; Yuan, D. W.; Li, Y. T.; Li, D. Z.; Rhee, Y. J.; Zhang, Z.; Li, F.; Zhu, B. J.; Li, Yan F.; Han, B.; Liu, C.; Ma, Y.; Li, Yi F.; Tao, M. Z.; Li, M. H.; Guo, X.; Huang, X. G.; Fu, S. Z.; Zhu, J. Q.; Zhao, G.; Chen, L. M.; Fu, C. B.; Zhang, J.

    2016-06-01

    Neutron energy is directly correlated with the energy of the incident ions in experiments involving laser-driven nuclear reactions. Using high-energy incident ions reduces the energy concentration of the generated neutrons. A novel “laser-collider” method was used at the Shenguang II laser facility to produce monoenergetic neutrons via 7Li (d, n) nuclear reactions. The specially designed K-shaped target significantly increased the numbers of incident d and Li ions at the keV level. Ultimately, 13.3 MeV neutrons were obtained. Considering the time resolution of the neutron detector, we demonstrated that the produced neutrons were monoenergetic. Interferometry and a Multi hydro-dynamics simulation confirmed the monoenergetic nature of these neutrons.

  17. A novel laser-collider used to produce monoenergetic 13.3 MeV 7Li (d, n) neutrons

    PubMed Central

    Zhao, J. R.; Zhang, X. P.; Yuan, D. W.; Li, Y. T.; Li, D. Z.; Rhee, Y. J.; Zhang, Z.; Li, F.; Zhu, B. J.; Li, Yan F.; Han, B.; Liu, C.; Ma, Y.; Li, Yi F.; Tao, M. Z.; Li, M. H.; Guo, X.; Huang, X. G.; Fu, S. Z.; Zhu, J. Q.; Zhao, G.; Chen, L. M.; Fu, C. B.; Zhang, J.

    2016-01-01

    Neutron energy is directly correlated with the energy of the incident ions in experiments involving laser-driven nuclear reactions. Using high-energy incident ions reduces the energy concentration of the generated neutrons. A novel “laser-collider” method was used at the Shenguang II laser facility to produce monoenergetic neutrons via 7Li (d, n) nuclear reactions. The specially designed K-shaped target significantly increased the numbers of incident d and Li ions at the keV level. Ultimately, 13.3 MeV neutrons were obtained. Considering the time resolution of the neutron detector, we demonstrated that the produced neutrons were monoenergetic. Interferometry and a Multi hydro-dynamics simulation confirmed the monoenergetic nature of these neutrons. PMID:27250660

  18. A novel laser-collider used to produce monoenergetic 13.3 MeV (7)Li (d, n) neutrons.

    PubMed

    Zhao, J R; Zhang, X P; Yuan, D W; Li, Y T; Li, D Z; Rhee, Y J; Zhang, Z; Li, F; Zhu, B J; Li, Yan F; Han, B; Liu, C; Ma, Y; Li, Yi F; Tao, M Z; Li, M H; Guo, X; Huang, X G; Fu, S Z; Zhu, J Q; Zhao, G; Chen, L M; Fu, C B; Zhang, J

    2016-01-01

    Neutron energy is directly correlated with the energy of the incident ions in experiments involving laser-driven nuclear reactions. Using high-energy incident ions reduces the energy concentration of the generated neutrons. A novel "laser-collider" method was used at the Shenguang II laser facility to produce monoenergetic neutrons via (7)Li (d, n) nuclear reactions. The specially designed K-shaped target significantly increased the numbers of incident d and Li ions at the keV level. Ultimately, 13.3 MeV neutrons were obtained. Considering the time resolution of the neutron detector, we demonstrated that the produced neutrons were monoenergetic. Interferometry and a Multi hydro-dynamics simulation confirmed the monoenergetic nature of these neutrons. PMID:27250660

  19. Measurement of the parity-violating triton emission asymmetry in the reaction {sup 6}Li(n,{alpha}){sup 3}H with polarized cold neutrons

    SciTech Connect

    Vesna, V. A.; Shulgina, E. V.; Gledenov, Yu. M.; Sedyshev, P. V.; Nesvizhevsky, V. V.; Petoukhov, A. K.; Soldner, T.; Zimmer, O.

    2008-03-15

    We describe measurements of the parity-violating (P-odd) triton emission asymmetry coefficient a{sub P-odd} in the {sup 6}Li(n,{alpha}){sup 3}H reaction with polarized cold neutrons. Experiments were carried out at the Petersburg Nuclear Physics Institute (Gatchina, Russia) and at the Institut Laue-Langevin (Grenoble, France). We employed an ionisation chamber in a configuration allowing us to suppress the left-right asymmetry well below 10{sup -8}. An additional test for a false asymmetry due to eventual target impurities (''zero test'') resulted in a{sub 0-test}=(0.0{+-}0.5)x10{sup -8}. As final result of this series of experiments we obtained a{sub P-odd}=(-8.8{+-}2.1)x10{sup -8}.

  20. (7)Li in situ 1D NMR imaging of a lithium ion battery.

    PubMed

    Klamor, S; Zick, K; Oerther, T; Schappacher, F M; Winter, M; Brunklaus, G

    2015-02-14

    The spatial distribution of charge carriers in lithium ion batteries during current flow is of fundamental interest for a detailed understanding of transport properties and the development of strategies for future improvements of the electrolyte-electrode interface behaviour. In this work we explored the potential of (7)Li 1D in situ NMR imaging for the identification of concentration gradients under constant current load in a battery cell. An electrochemical cell based on PTFE body and a stack of glass microfiber discs that are soaked with a technically relevant electrolyte suitable for high-temperature application and squeezed between a Li metal and a nano-Si-graphite composite electrode was assembled to acquire (7)Li 1D in situ NMR profiles with an improved NMR pulse sequence as function of time and state of charge, thereby visualizing the course of ion concentration during charge and discharge. Surface localized changes of Li concentration were attributed to processes such as solid electrolyte interphase formation or full lithiation of the composite electrode. The method allows the extraction of lithium ion transport properties. PMID:25578436

  1. Corrosion barriers processed by Al electroplating and their resistance against flowing Pb-15.7Li

    NASA Astrophysics Data System (ADS)

    Krauss, Wolfgang; Konys, Jürgen; Wulf, Sven-Erik

    2014-12-01

    In the HCLL blanket design, ferritic-martensitic steels are in direct contact with the flowing liquid breeder Pb-15.7Li and have to withstand severe corrosion attack. Beyond corrosion, T-permeation from the breeder into the RAFM-steels is also an important issue and has to be reduced significantly. Earlier work showed that Al-based coatings can act as barriers for both, however, applied processes e.g. HDA or VPS exhibited strong drawbacks in the past. Meanwhile new industrial relevant coating processes, using electroplating technology are under development and called ECA (electrochemical aluminization) and ECX (electrochemical deposition from ionic liquids) process. In this study electrochemically Al-coated and heat-treated Eurofer samples were tested in PICOLO loop for exposure times up to 12,000 h (ECA) and 2000 h (first results ECX) respectively to determine corrosion properties in flowing Pb-15.7Li (550 °C, 0.1 m/s). Cross section analysis afterward corrosion testing proved the ability of thin Al-based barriers made by electrochemical techniques to protect the bare Eurofer from corrosion attack even at exposure times of 12,000 h. Determined radial corrosion rates lay between 10 and 20 μm/a. First results for ECX coated samples (2000 h) revealed more homogeneous corrosion behavior of the barrier layer itself compared to ECA.

  2. Astrophysical S factors for radiative proton capture by {sup 3}H and {sup 7}Li nuclei

    SciTech Connect

    Dubovichenko, S. B.

    2011-03-15

    Within the potential cluster model where orbital states are classified according to Young diagrams and isospin, astrophysical S factors are considered for radiative proton capture by {sup 3}H and {sup 7}Li nuclei at energies of up to 1 and 10 keV, respectively. It is shown that the approach used, which takes into account only the E1 transition for the p{sup 3}H capture process, makes it possible to describe well the most recent experimental data at c.m. energies in the range from 50 keV to 5MeV. In the case of proton capture by {sup 7}Li nuclei, an M1 processwas taken into account in addition to the E1 transition, and a general behavior and the magnitude of the experimental S factor could be correctly reproduced owing to this at astrophysical energies, including the region around the resonance at 0.441 MeV (in the laboratory frame).

  3. Studies of nuclear reaction at very low energies

    SciTech Connect

    Cecil, F.E.

    1992-01-15

    The deuteron radiative capture reactions on {sup 2}H, {sup 6}Li and {sup 10}B have been measured between center of mass energies of 20 and 140 keV. Of note is the observation that the gamma ray-to-charged particle branching ratio for the DD reaction appears independent of energy down to a center of mass energy of 20 keV, consistent with some and contrary to other theoretical models. We have investigated the ratio of the reactions D(d,p)T and D(d,n){sup 3}He down to c.m. energies of 3 keV and the ratio of the reactions 6Li(d,p){sup 7}Li and {sup 6}LI(d,{alpha}){sup 4}He down to a c.m. energy of 19 keV. The DD reaction ratio is independent of energy while the (d,p) branch of the D-{sup 6}Li evinces a significant enhancement at the lowest measured energies. We have continued our investigation of charged particle production from deuterium-metal systems at a modest level of activity. Noteworthy in this investigation is the observation of 3 MeV protons from deuteron beam loaded Ti and LiD targets subjected to extreme thermal disequilibria. Significant facility improvements were realized during the most recent contract period. Specifically the downstream magnetic analysis system proposed to eliminate beam induced contaminants has been installed and thoroughly tested. This improvement should allow the D(a,{gamma}){sup 6}Li reaction to be measured in the coming contract period. A scattering chamber required for the measurement of the {sup 7}Li({sup 3}He,p){sup 9}Be reaction has been designed, fabricated and installed on the accelerator. A CAMAC based charged particle identification system has been assembled also for use in our proposed measurement of the {sup 7}Li({sup 3}He, p){sup 9}Be.

  4. T sub 20 in the inclusive breakup of 4. 5 GeV polarized sup 6 Li

    SciTech Connect

    Punjabi, V. ); Perdrisat, C.F.; Cheung, E. ); Yonnet, J.; Boivin, M.; Tomasi-Gustafsson, E. ); Siebert, R.; Frascaria, R.; Warde, E. ); Belostotsky, S.; Miklucho, O.; Sulimov, V. ); Abegg, R. ); Lehman, D.R. )

    1992-09-01

    The analyzing power {ital T}{sub 20} in the inclusive {sup 1}H({sup 6}Li,{ital d} or {alpha} or {ital t}){ital X} reaction with 4.5 GeV tensor polarized {sup 6}Li nuclei has been measured at an angle of 0.8{degree}. The kinematics chosen favor the detection of spectator fragments; in the impulse approximation the laboratory momentum of such a fragment is then the Lorentz boosted internal momentum. Nonzero {ital T}{sub 20} values have been observed, in agreement with the known nonsphericity of {sup 6}Li indicated by its quadrupole moment. The sign of {ital T}{sub 20} in the {ital d} channel suggests that near {ital q}=0 the {ital D} state in {sup 6}Li has the same sign as in the deuteron; an abrupt change of sign near {ital q}=0.12 GeV/{ital c} is in agreement with theoretical expectation of a node in the {alpha}{ital d} position wave function. The {alpha}-channel data show larger {ital T}{sub 20} values than the {ital d} channel; in this case the small-{ital q}-region has not been explored enough to establish a similar node. A few data points in the {ital t} channel might suggest that {ital T}{sub 20} becomes positive above {ital q}=0.4 GeV/{ital c} in this case.

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

    SciTech Connect

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

    1996-09-01

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

  6. Deviation from Universality in Collisions of Ultracold 6Li2 Molecules

    NASA Astrophysics Data System (ADS)

    Wang, Tout; Heo, Myoung-Sun; Rvachov, Timur; Cotta, Dylan; Ketterle, Wolfgang

    2013-05-01

    Collisions of 6Li2 molecules reveal a striking deviation from universal predictions based on long-range van der Waals interactions. Li2 closed-channel molecules are formed in the highest vibrational state near a narrow Feshbach resonance, and decay via two-body collisions with Li2, Li, and Na. For Li2+Li2 and Li2+Na, the decay rates agree with the universal predictions of the quantum Langevin model. In contrast, the rate for Li2+Li is exceptionally small, with an upper bound ten times smaller than the universal prediction. This can be explained by the low density of available decay states in systems of light atoms [G. Quéméner, J.-M. Launay, and P. Honvault, Phys. Rev. A 75, 050701 (2007)], for which such collisions have not been studied before. Financial support from an AFOSR MURI on Ultracold Molecules, an ARO MURI on Quantum Control of Chemical Reactions, the NSF and the ONR, ARO Grant No. W911NF-07-1-0493, with funds from the DARPA Optical Lattice Emulator program, and NSERC.

  7. Crystal growth and characterization of 6LiInSe2 neutron detector

    NASA Astrophysics Data System (ADS)

    Cui, Yunlong; Bhattacharya, Pijush; Groza, Michael; Tupitysn, Eugene; Rowe, Emmanuel; Buliga, Vladimir; Matei, Liviu; Wiggins, Brenden; Johnstone, Daniel; Stowe, Ashley; Burger, Arnold

    2014-03-01

    6LiInSe2 is a promising thermal neutron semiconductor detector material. The performance of the detector is affected by the carrier mobility-lifetime product. Therefore, defects that function as carrier recombination center need to be identified. In the presentation, the crystals were grown from melt by the vertical Bridgman method, and characterized by photo-induced current transient spectroscopy (PICTS), low-temperature photoluminescence (LTPL) and detector performance measurement. PICTS measurements revealed electron-related defects located at 0.22, 0.36 and 0.55 eV and hole-related defects at 0.19, 0.30, and 0.73 eV. The defect values are consistent with those measured from LTPL donor-acceptor pair emissions. The carrier mobility-lifetime products were extracted from DC photocurrent and alpha-particle response measurements. This work was partial supported by the Y-12 National Security Complex Plant Directed Research and Development Program No. 630001269, DOE Grant No. 1089091, and the Army Grant No. W911NF-11-0196.

  8. Observation of a ferromagnetic instability in repulsively interacting Fermi gases of 6 Li

    NASA Astrophysics Data System (ADS)

    Scazza, Francesco; Valtolina, Giacomo; Amico, Andrea; Burchianti, Alessia; Fort, Chiara; Zaccanti, Matteo; Inguscio, Massimo; Roati, Giacomo

    2016-05-01

    The fine control of interaction strengths and optical trapping potentials in ultracold atomic ensembles provide unique opportunities to explore strongly correlated fermion phenomena, such as superfluidity and magnetism. In our setup, we produce 6 Li quantum gases in the vicinity of a broad Feshbach resonance and we subsequently superimpose to the samples a thin optical barrier to engineer either a Josephson weak link or a ferromagnetic domain wall. This technique recently enabled the experimental study of the Josephson dynamics of superfluid Fermi gases flowing through an insulating barrier, spanning a wide range of interaction strengths across the BEC-BCS crossover. On the other hand, by preparing adjacent and fully spin-polarized domains, we are able to experimentally address the upper branch of a repulsively interacting Fermi gas and its magnetic properties. Here, we report on the investigation of the onset and the stability of the ferromagnetic state. Measurements of spin diffusion dynamics in the system reveal a total suppression of spin conductance above a critical interaction strength, accompanied by a softening of the collective spin-dipole mode, indicating the existence of a ferromagnetic instability.

  9. Vector analyzing power of {pi}{sup +7}Li scattering in the region of the {delta}{sub 33} resonance

    SciTech Connect

    Ibraeva, E. T.; Zhusupov, M. A.; Zaykin, A. Yu.; Imambekov, O.

    2006-04-15

    Within Glauber diffraction theory, the vector analyzing power iT{sub 11} is calculated at three energies of positively charged pions, 134, 164, and 194 MeV, incident to {sup 7}Li nuclei. These energy values lie in the region of the {delta}{sub 33} resonance in {pi}{sup {+-}}N interaction, the resonance maximum being at 180 MeV. The calculation of iT{sub 11} was performed with several model {sup 7}Li wave functions, including the {alpha}t-cluster and shell-model ones. The properties of {pi}{sup +7}Li scattering are found to be sensitive to the structural features of the target nucleus. A comparison of the results of the calculations with experimental data shows that the wave functions in question and the potentials used to calculate them are quite appropriate.

  10. Analysis of deuteron breakup reactions on {sup 7}Li for energies up to 100 MeV

    SciTech Connect

    Ye, Tao; Watanabe, Yukinobu; Ogata, Kazuyuki

    2009-07-15

    Inclusive nucleon spectra from deuteron breakup reactions on {sup 7}Li are analyzed in terms of the continuum discretized coupled channels theory for the elastic breakup process and the Glauber model for the nucleon stripping process. Both theoretical models use the same phenomenological nucleon optical potential of {sup 7}Li and have no other free parameters. The calculations reproduce well a prominent bump observed around half the incident energy in experimental inclusive spectra of 40-MeV (d,xn) and 100-MeV (d,xp) reactions at forward angles. The analysis shows that the stripping process is more important than the elastic breakup process in deuteron breakup reactions on {sup 7}Li.

  11. A Comprehensive Theoretical Analysis of 6,7Li + 64Zn Elastic Scattering in a Wide Angular Range Around the Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Ibraheem, Awad A.; Aygun, M.

    2016-06-01

    In this paper, the elastic scattering angular distributions of 6,7Li on 64Zn have been investigated by using various nuclear potentials. For this, we use the phenomenological Woods-Saxon potential, the real double folding potential with the density-independent M3Y effective interaction supplemented with an imaginary part in Woods-Saxon form and the double folding potentials multiplied with a normalization factor of the real and imaginary parts via the density-independent and CDM3Y6 density-dependent versions of the M3Y effective interaction have been used. The results have been compared with each other as well as with the experimental data. It has been observed that the agreement between the theoretical results and earlier reported data is perfect. Finally, the change of the total reaction cross sections with energy has been investigated.

  12. A Comprehensive Theoretical Analysis of 6,7Li + 64Zn Elastic Scattering in a Wide Angular Range Around the Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Ibraheem, Awad A.; Aygun, M.

    2016-08-01

    In this paper, the elastic scattering angular distributions of 6,7Li on 64Zn have been investigated by using various nuclear potentials. For this, we use the phenomenological Woods-Saxon potential, the real double folding potential with the density-independent M3Y effective interaction supplemented with an imaginary part in Woods-Saxon form and the double folding potentials multiplied with a normalization factor of the real and imaginary parts via the density-independent and CDM3Y6 density-dependent versions of the M3Y effective interaction have been used. The results have been compared with each other as well as with the experimental data. It has been observed that the agreement between the theoretical results and earlier reported data is perfect. Finally, the change of the total reaction cross sections with energy has been investigated.

  13. FIGARO : detecting nuclear materials using high-energy gamma rays for oxygen.

    SciTech Connect

    Michlich, B. J.; Smith, D. L.; Massey, T. N.; Ingram, D.; Fessler, A.

    2000-10-10

    Potential diversion of nuclear materials is a major international concern. Fissile (e.g., U, Pu) and other nuclear materials (e.g., D, Be) can be detected using 6-7 MeV gamma rays produced in the {sup 19}F(p,{alpha}{gamma}){sup 16}O reaction. These gamma rays will induce neutron emission via the photoneutron and photofission processes in nuclear materials. However, they are not energetic enough to generate significant numbers of neutrons from most common benign materials, thereby reducing the false alarm rate. Neutrons are counted using an array of BF3 counters in a polyethylene moderator. Experiments have shown a strong increase in neutron count rates for depleted uranium, Be, D{sub 2}O, and {sup 6}Li, and little or no increase for other materials (e.g., H{sub 2}O, SS, Cu, Al, C, {sup 7}Li). Gamma source measurements using solid targets of CaF{sub 2} and MgF{sub 2} and a SF{sub 6} gas target show that proton accelerator of 3 MeV and 10-100 microampere average current could lead to acceptable detection sensitivity.

  14. Measurement of fusion excitation function for 7Li+64Ni near the barrier

    NASA Astrophysics Data System (ADS)

    Moin Shaikh, Md.; Roy, Subinit; Rajbanshi, S.; Mukherjee, A.; Pradhan, M. K.; Basu, P.; Pal, S.; Nanal, V.; Shrivastava, A.; Saha, S.; Pillay, R. G.

    2016-05-01

    Total fusion (TF) excitation function has been measured for the system 7Li + 64Ni at the energies near the Coulomb barrier of the system. The evaporation residue (ER) cross sections have been estimated through the online detection of characteristic γ-rays of the ERs. The summed ER cross sections yielding the experimental TF cross section have been compared with the theoretical one dimensional barrier penetration model (1DBPM) prediction. The measured and the model cross sections are very close to each other at above barrier energies. However, an enhancement of the experimental TF cross section with respect to the 1DBPM prediction is observed at below barrier energies. Coupled channels (CC) calculation with inelastic excitations alone could not explain the enhancement. The origin of the enhancement is identified as due to the enhanced population of the αxn channels.

  15. New method to evaluate the 7Li(p, n)7Be reaction near threshold

    NASA Astrophysics Data System (ADS)

    Herrera, María S.; Moreno, Gustavo A.; Kreiner, Andrés J.

    2015-04-01

    In this work a complete description of the 7Li(p, n)7Be reaction near threshold is given using center-of-mass and relative coordinates. It is shown that this standard approach, not used before in this context, leads to a simple mathematical representation which gives easy access to all relevant quantities in the reaction and allows a precise numerical implementation. It also allows in a simple way to include proton beam-energy spread affects. The method, implemented as a C++ code, was validated both with numerical and experimental data finding a good agreement. This tool is also used here to analyze scattered published measurements such as (p, n) cross sections, differential and total neutron yields for thick targets. Using these data we derive a consistent set of parameters to evaluate neutron production near threshold. Sensitivity of the results to data uncertainty and the possibility of incorporating new measurements are also discussed.

  16. Optimization of the {sup 7}Li(p,n) proton beam energy for BNCT applications

    SciTech Connect

    Bleuel, D.L.; Donahue, R.J.

    1996-02-01

    The reaction {sup 7}Li(p,n){sup 7} Be has been proposed as an accelerator-based source of neutrons for Boron Neutron Capture Therapy (BNCT). This reaction has a large steep resonance for proton energies of about 2.3 MeV which ends at about 2.5 MeV. It has generally been accepted that one should use 2.5 MeV protons to get the highest yield of neutrons for BNCT. This paper suggests that for BNCT the optimum proton energy may be about 2.3 MeV and that a proton energy of about 2.2 MeV will provide the same useful neutron fluence outside a thinner moderator as the neutron fluence from a 2.5 MeV proton beam with a thicker moderator.

  17. Magnetic fluctuations and possible formation of a spin-singlet cluster under pressure in the heavy-fermion spinel LiV2O4 probed by 7Li and 51V NMR

    NASA Astrophysics Data System (ADS)

    Takeda, Hikaru; Kato, Yusuke; Yoshimura, Masahiro; Shimizu, Yasuhiro; Itoh, Masayuki; Niitaka, Seiji; Takagi, Hidenori

    2015-07-01

    7Li and 51V NMR measurements up to 9.8 GPa have been made to elucidate local magnetic properties of a heavy-fermion spinel oxide LiV2O4 which undergoes a metal-insulator transition above ˜7 GPa. The temperature T and pressure P dependences of the 7Li and 51V Knight shifts and the nuclear spin-lattice relaxation rates 1 /T1 show that in the metallic phase, there is a crossover from a high-T region with weak ferromagnetic fluctuations to a low-T one with antiferromagnetic (AFM) fluctuations. The AFM fluctuations are enhanced below 20 K and 1.5 GPa, where a heavy Fermi-liquid state with the modified Korringa relation is formed. The evolution of the magnetic fluctuations is discussed from the aspect of the competition among several magnetic interactions. Above PMI˜6.7 GPa, we find the coexistence of metallic and insulating phases due to the first-order metal-insulator transition. The 7Li and 51V NMR spectra coming from the insulating phase have T -independent small Knight shifts and 7(1 /T1 ) with the thermally activated T dependence, indicating the formation of a spin-singlet cluster. We propose a model of a spin-singlet tetramer as discussed in geometrically frustrated materials.

  18. Quasi-Elastic Barrier Distribution for the {sup 7}Li+{sup 144}Sm Weakly Bound System

    SciTech Connect

    Otomar, D. R.; Gomes, P. R. S.; Lubian, J.; Monteiro, D. S.

    2009-06-03

    We have measured the excitation function of quasielastic and elastic scattering, at backward angles, for a range of energies from below to above the Coulomb barrier, for the {sup 7}Li+{sup 144}Sm system. Barrier distributions were exctracted from these excitation functions by a numerical method. From the theoretical analysis one concluded that the quadrupole and octupole excitations of {sup 144}Sm and the one-neutron transfer (stripping) channel are important reaction processes. Nevertheless, the agreement with the experimental results is poor. The discrepancy is attributed to the {sup 7}Li break-up channel that was not taken into account in the coupling scheme.

  19. Response of an FBX dosimeter to high LET 7Li and 12C ions

    NASA Astrophysics Data System (ADS)

    Bhat, N. N.; Choudhary, D.; Sarma, A.; Gupta, B. L.; Siddappa, K.

    2003-12-01

    We have carried out systematic studies on the response of ferrous sulphate-benzoic acid-xylenol orange (FBX)—a highly sensitive chemical dosimeter in liquid form to accelerated charged particles of different LET. Dosimeters were exposed in the form of thin layers to graded fluence of 7Li ion beam with three different energies Viz, 46, 38 and 27 MeV corresponding to average LETs of 6.3, 7.5 and 11 eV Å -1 and 12C ion beam with energy 45.6 MeV corresponding to average LET of 52.5 eV Å -1. From the investigations, the corresponding G(Fe +3) values were found to be (51.7±1.3)×10 -7, (35.4±0.7)×10 -7, (19.3±0.6)×10 -7 and (8.4±0.1)×10 -7 mol J -1, respectively. For gamma radiation, with estimated LET of 0.02 eV Å -1, G(Fe +3) value was observed to be (56.1±0.4)×10 -7 mol J -1. Clearly, G(Fe +3) values were found to decrease with increasing LET of the particle beam. However, the dosimeter showed no dependence on LET up to about 6 eV Å -1 unlike the Fricke dosimeter. The results confirm the response of FBX dosimeter is non-linear for doses exceeding 5 Gy for 60Co gamma rays. More importantly, the present study using 7Li and 12C ions clearly shows that response of the FBX dosimeter is linear for high LET radiations at low as well as high doses.

  20. Astrophysical S-factor for 6Li(ρ, γ)7Be in the coupled-channel Gamow shell model

    NASA Astrophysics Data System (ADS)

    Dong, G. X.; Fossez, K.; Michel, N.; Płoszajczak, M.

    2016-02-01

    We have applied the Gamow shell model (GSM) in the coupled-channel representation to study the astrophysical S-factor for the proton radiative capture reaction of 6Li. Reaction channels are built by coupling the proton wave function expanded in different partial waves with the GSM wave functions of the ground state (1+) and the excited states (31+, 01+ and 21+) of 6Li. All relevant E1, M1, and E2 transitions from the initial continuum states in 7Be to the final bound states (3/21- and 1/21-) are included. It is found that the calculated total astrophysical S factor for this reaction agrees well with the experimental data.

  1. Mechanisms of the sup 64 Zn(d, sup 6 Li) sup 60 Ni reaction at E sub lab = 16. 4 MeV

    SciTech Connect

    Bowsher, J.E.

    1989-01-01

    Cross-sections, A{sub y}, A{sub yy}, and A{sub xx} for the {sup 64}Zn(d, {sup 6}Li) reaction forming the ground and first excited states of {sup 60}Ni were measured in 5{degree} steps from {theta}{sub lab} = 25{degree} to 80{degree} using an E{sub lab} = 16.4 MeV beam of vector and tensor polarized deuterons. These data include the first measurement of A{sub xx} and A{sub yy} for the (d, {sup 6}Li) reaction on a medium to heavy target nucleus. The A{sub y} measurement is also among the first for (d,{sup 6}Li) reactions. Also measured were excitation functions of d{sigma}/d{Omega}, A{sub y}, A{sub yy}, and A{sub xx} for {sup 64}Zn(d,d) scattering at E{sub lab} = 16.4 MeV. The {sup 6}Li ground state and seven other wave functions, each representing {sup 6}Li continuum states of a given spin, I, and internal orbital angular momentum, l, l {le} 2, were included in coupled-channels (CC) calculations of {sup 60}Ni({sup 6}Li, {sup 6}Li) elastic scattering and finite-range, coupled channel Born approximation (CCBA) calculations for the {sup 64}Zn(d,{sup 6}Li) reaction forming the {sup 60}Ni ground state. This analysis is the first to consider the influence of {sup 6}Li continuum states on the (d, {sup 6}Li) reaction. The {sup 6}Li-{sup 60}Ni interactions were generated using a cluster folding model. Both the folding model and the CC and CCBA calculations were performed by the code FRESCO. For the {sup 64}Zn(d, {sup 6}Li) reaction, CCBA calculations demonstrated that {alpha} transfers forming the 3{sup +} state of {sup 6}Li affect d{sigma}/d{Omega} and A{sub y} very strongly.

  2. Measurement of the 6Li(n,α) neutron standard cross-section at the GELINA facility

    NASA Astrophysics Data System (ADS)

    Jansson, Kaj; Al-Adili, Ali; Bevilacqua, Riccardo; Gustavsson, Cecilia; Hambsch, Franz-Josef; Pomp, Stephan; Vidali, Marzio

    2016-06-01

    The 6Li(n,α) reaction cross-section is commonly used as a reference cross section. However, it is only considered a neutron standard up to 1MeV. For higher energies, there are discrepancies of several per cents between recent measurements and evaluated data files. In order to extend and establish 6Li(n,α) as a neutron standard above 1MeV these discrepancies must be resolved. Our measurement at the GELINA facility at JRC-IRMM in Geel, Belgium is ongoing. We are using a double twin Frisch-grid setup to detect both α-particles from two 6Li targets and fission products from two 235U reference targets. Our targets have thick backings but are employed in pairs, one forward facing and one backward facing. In this way we still cover, in principle, a solid angle of 4π. We present some preliminary results showing that the existing cross-section data is well reproduced around the resonance at 240 keV. The final data taking will start in the beginning of 2016, when the GELINA facility goes online again after a few months of shut down.

  3. Channel coupling and exchange of an alpha-particle cluster in deuteron scattering on {sup 6}Li nuclei

    SciTech Connect

    Sakuta, S. B.; Burtebaev, N.; Artemov, S. V.; Yarmukhamedov, R.

    2012-07-15

    Existing experimental data on elastic and inelastic deuteron scattering on {sup 6}Li nuclei in the energy range from 8 to 50 MeV were analyzed within the approach of coupled reaction channels. The coupling of elastic scattering and inelastic scattering accompanied by the transition to the 3{sup +} state at E{sub x} 2.186 MeV and the mechanism involving the exchange of an alpha-particle cluster were taken into account in respective calculations. The phenomenological potentials obtained from the present analysis describe well experimental angular distributions at all energies and in full angular ranges. The depths of the real and imaginary parts of the potentials in question depend smoothly on energy at fixed values of the remaining parameters. The energy dependence of relevant volume integrals agrees well with similar data for the p + {sup 6}Li, {alpha} + {sup 6}Li, and {sup 12}C + {sup 12}C systems and with the predictions of a microscopic theory.

  4. Theoretical study of the α +d →6Li +γ astrophysical capture process in a three-body model

    NASA Astrophysics Data System (ADS)

    Tursunov, E. M.; Kadyrov, A. S.; Turakulov, S. A.; Bray, I.

    2016-07-01

    The astrophysical capture process α +d →6Li is studied in a three-body model. The initial state is factorized into the deuteron bound state and the (α +d )-scattering state. The final nucleus 6Li (1+) is described as a three-body bound state α +n +p in the hyperspherical Lagrange-mesh method. The contribution of the E 1 -transition operator from the initial isosinglet states to the isotriplet components of the final state is estimated to be negligible. An estimation of the forbidden E 1 transition to the isosinglet components of the final state is comparable with the corresponding results of the two-body model. However, the contribution of the E 2 -transition operator is found to be much smaller than the corresponding estimations of the two-body model. The three-body model perfectly matches the new experimental data of the LUNA Collaboration with the spectroscopic factor of 2.586 estimated from the bound-state wave functions of 6Li and a deuteron.

  5. Trojan horse method applied to {sup 9}Be(p,{alpha}){sup 6}Li at astrophysical energies

    SciTech Connect

    Wen Qungang; Li Chengbo; Zhou Shuhua; Meng Qiuying; Zhou Jing; Li Xiaomei; Hu Shouyang; Fu Yuanyong; Spitaleri, C.; Tumino, A.; Pizzone, R. G.; Rapisarda, G. G.

    2008-09-15

    The low-energy bare-nucleus cross section for {sup 9}Be(p,{alpha}){sup 6}Li has been extracted by means of the Trojan horse method (THM) applied to the {sup 2}H({sup 9}Be, {alpha},{sup 6}Li)n reaction at a beam energy of {sup 9}Be of 22.35 MeV. For the first time, we assume an intermediate process, {sup 9}Be+{sup 2}H{yields}{sup 9}Be+p+n, and considered this process as one criterion of the quasifree condition. Accordingly, sequential decay processes were eliminated. The derived astrophysical S(E) factor for the two-body process {sup 9}Be(p,{alpha}){sup 6}Li is compared with that obtained from direct experiments. We have found good agreement between the two results, leading to an improved determination of the S(E) with S(0)=21.0{+-}0.8 MeV b. Furthermore, the electron screening potential energy U{sub e}=676{+-}86 eV has also been extracted in a model-independent way by comparing the direct and THM data. The value is significantly higher than that predicted by current theoretical models, whereas it is lower than Ue{approx_equal}830 eV, which was extracted from direct measurements with inclusion of the E{sub c.m.}=-23 keV subthreshold resonance.

  6. Studies of nuclear reaction at very low energies. Technical progress report

    SciTech Connect

    Cecil, F.E.

    1992-01-15

    The deuteron radiative capture reactions on {sup 2}H, {sup 6}Li and {sup 10}B have been measured between center of mass energies of 20 and 140 keV. Of note is the observation that the gamma ray-to-charged particle branching ratio for the DD reaction appears independent of energy down to a center of mass energy of 20 keV, consistent with some and contrary to other theoretical models. We have investigated the ratio of the reactions D(d,p)T and D(d,n){sup 3}He down to c.m. energies of 3 keV and the ratio of the reactions 6Li(d,p){sup 7}Li and {sup 6}LI(d,{alpha}){sup 4}He down to a c.m. energy of 19 keV. The DD reaction ratio is independent of energy while the (d,p) branch of the D-{sup 6}Li evinces a significant enhancement at the lowest measured energies. We have continued our investigation of charged particle production from deuterium-metal systems at a modest level of activity. Noteworthy in this investigation is the observation of 3 MeV protons from deuteron beam loaded Ti and LiD targets subjected to extreme thermal disequilibria. Significant facility improvements were realized during the most recent contract period. Specifically the downstream magnetic analysis system proposed to eliminate beam induced contaminants has been installed and thoroughly tested. This improvement should allow the D(a,{gamma}){sup 6}Li reaction to be measured in the coming contract period. A scattering chamber required for the measurement of the {sup 7}Li({sup 3}He,p){sup 9}Be reaction has been designed, fabricated and installed on the accelerator. A CAMAC based charged particle identification system has been assembled also for use in our proposed measurement of the {sup 7}Li({sup 3}He, p){sup 9}Be.

  7. Measurements of the Coulomb dissociation cross section of 156 MeV sup 6 Li projectiles at extremely low relative fragment energies of astrophysical interest

    SciTech Connect

    Kiener, J.; Gils, H.J.; Rebel, H.; Zagromski, S.; Gsottschneider, G.; Heide, N.; Jelitto, H.; Wentz, J. ); Baur, G. )

    1991-11-01

    Coulomb dissociation of light nuclear projectiles in the electric field of heavy target nuclei has been experimentally investigated as an alternative access to radiative capture cross sections at low relative energies of the fragments, which are of astrophysical interest. As a pilot experiment the breakup of 156 MeV {sup 6}Li projectiles at {sup 208}Pb with small emission angles of the {alpha} particle and deuteron fragments has been studied. Both fragments were coincidentally detected in the focal plane of a magnetic spectrograph at several reaction angles well below the grazing angle and with relative angles between the fragments of 0{degree}--2{degree}. The experimental cross sections have been analyzed on the basis of the Coulomb breakup theory. The results for the resonant breakup give evidence for the strong dominance of the Coulomb dissociation mechanism and the absence of nuclear distortions, while the cross section for the nonresonant breakup follows theoretical predictions of the astrophysical {ital S} factor and extrapolations of corresponding radiative capture reaction cross section to very low c.m. energies of the {alpha} particle and deuteron. Various implications of the approach are discussed.

  8. Neutron Interactions With 7Be and the Primordial 7Li Problem

    NASA Astrophysics Data System (ADS)

    Kading, Emily E.; Gai, Moshe; Kahn, Merav; Lee, Morit; Tessler, Moshe; Paul, Michael; Weiss, Aryeh; Berkovitz, Dan; Halfon, Shlomi; Kijel, Danny; Kreisel, Arik; Shor, Asher; Silverman, Ido; Weissman, Leonid; Hass, Michael; Mukul, Ish; Maugeri, Emilio A.; Dressler, Rugard; Schumann, Dorothea; Heinitz, Stephan; Stora, Thierry; Ticehurst, David; Howell, Calvin R.

    2015-10-01

    We study the interaction of neutrons with 7Be to estimate the direct destruction of 7Be during BBN; i.e. the predicted primordial 7Li. We plan to use a 7Be target (15 GBq) prepared by electro-deposition at PSI. The intense neutron flux of up to 5×1010 n/sec/cm2 are produced with proton beams and a high power liquid-lithium target (LiLiT) from the SARAF (phase I) facility in Israel. The outgoing particles will be measured using CR-39 plates that were tested to be insensitive to the large neutron flux and were calibrated with protons and alpha-particles from the TUNL. In a separate stage implanted 7Be target will be prepared at the ISOLDE facility of CERN. The results of the calibration of the CR-39 plates and the test experiment at SARAF with 10B target as well as a very low activity 7Be test target prepared at PSI, will be presented. Supported in part by the US-Israel Binational Science Foundation Proposal No. 2012098, the USDOE Grants No. DE-FG02-94ER40870, DE-FG02-97ER41033, and the Pazi Foundation, Israel.

  9. Visualizing skin effects in conductors with MRI: (7)Li MRI experiments and calculations.

    PubMed

    Ilott, Andrew J; Chandrashekar, S; Klöckner, Andreas; Chang, Hee Jung; Trease, Nicole M; Grey, Clare P; Greengard, Leslie; Jerschow, Alexej

    2014-08-01

    While experiments on metals have been performed since the early days of NMR (and DNP), the use of bulk metal is normally avoided. Instead, often powders have been used in combination with low fields, so that skin depth effects could be neglected. Another complicating factor of acquiring NMR spectra or MRI images of bulk metal is the strong signal dependence on the orientation between the sample and the radio frequency (rf) coil, leading to non-intuitive image distortions and inaccurate quantification. Such factors are particularly important for NMR and MRI of batteries and other electrochemical devices. Here, we show results from a systematic study combining rf field calculations with experimental MRI of (7)Li metal to visualize skin depth effects directly and to analyze the rf field orientation effect on MRI of bulk metal. It is shown that a certain degree of selectivity can be achieved for particular faces of the metal, simply based on the orientation of the sample. By combining rf field calculations with bulk magnetic susceptibility calculations accurate NMR spectra can be obtained from first principles. Such analyses will become valuable in many applications involving battery systems, but also metals, in general. PMID:25036296

  10. Interaction of loosely bound radioactive 7Be and stable 7Li with 9Be

    NASA Astrophysics Data System (ADS)

    Verma, S.; Das, J. J.; Jhingan, A.; Kalita, K.; Barua, S.; Golda, K. S.; Madhavan, N.; Sugathan, P.; Nath, S.; Varughese, T.; Gehlot, J.; Mandal, S.; Ranjit; Sahu, P. K.; John, B.; Nayak, B. K.; Jha, V.; Saxena, A.; Datta, S. K.; Singh, R.

    2010-06-01

    Quasielastic scattering angular distributions have been measured for the 7Be + 9Be system at E lab = 17 , 19 and 21MeV in the angular range θ_{{cm}}^{} = 24° - 57° . An optical model (OM) analysis of these data has been carried out in order to extract optical potential parameters and reaction cross-sections. One-proton stripping cross-sections were also measured for this system at E lab = 19 and 21MeV. These transfer angular-distribution data were compared with the finite-range distorted-wave Born approximation (FRDWBA) calculations. For the 7Li + 9Be system quasielastic scattering angular distributions were measured and emitted light charged particles were detected at E lab = 15.75 , 24.00 and 30.00MeV in the angular range θ_{{cm}}^{} = 7° - 70° . Fusion cross-sections were obtained by reproducing the measured α -evaporation spectra from the compound nucleus at backward angles with the statistical model calculations. The ratios of the experimental fusion cross-sections to the total reaction cross-sections (obtained from OM analysis) were found to be small. This result suggests that the break-up process has a strong influence on the fusion process leading to a reduction in the fusion cross-section.

  11. Optimization of the {sup 7}Li(p,n) proton beam energy for BNCT applications

    SciTech Connect

    Bleuel, B.L.; Donahue, R.J.

    1996-05-01

    The reaction {sup 7}Li(p,n){sup 7} Be has been proposed as an accelerator-based source of neutrons for Boron Neutron Capture Therapy (BNCT). This reaction has a large steep resonance for proton energies of about 2.3 MeV which ends at about 2.5 MeV. It has generally been accepted that one should use 2.5 MeV protons to get the highest yield of neutrons for BNCT. This paper suggests that for BNCT the optimum proton energy may be about 2.3 MeV and that a proton energy of about 2.2 MeV will provide the same useful neutron flux outside a thinner moderator as the neutron flux from a 2.5 MeV proton beam with a, thicker moderator. These results are based on optimization of the useful neutron spectrum in air at the point of irradiation, not on depth-dose profiles in tissue/tumor.

  12. Investigations of Li-containing SiCN(O) ceramics via 7Li MAS NMR.

    PubMed

    Gumann, Sina; Nestle, Nikolaus; Liebau-Kunzmann, Verena; Riedel, Ralf

    2007-04-01

    Lithium-containing silicon (oxy)carbonitride ceramics (SiCN(O):Li) were synthesized via precursor-to-ceramic-transformation of Li-containing (poly)silazanes. The precursors were obtained by lithiation of 2,4,6-trimethyl-2,4,6-trivinylcyclotrisilazane with n-butyllithium and by reaction of a commercial poly(organosilazane) VL20 with metallic lithium. The annealing treatment was carried out at temperatures between 200 and 1400 degrees C in argon (DeltaT=200 degrees C) and yielded Li-containing silicon (oxy)carbonitride. X-ray powder diffraction revealed that the resulting SiCN(O):Li ceramics were basically amorphous up to temperatures of 1000 degrees C and formed LiSi(2)N(3), graphite and silicon carbide as crystalline phases at higher temperatures. (7)Li MAS NMR spectroscopy was carried out to investigate the structure of the Li-containing phases and to study the reaction path of metallic Li with polysilazane. Based on the NMR spectra, there is almost no difference found in the chemical shift of the SiCN(O):Li ceramics obtained at different temperatures. Accordingly, Li is assigned to be mainly coordinated to N and O present as contaminant element. Relaxation time measurements showed that the most mobile Li(+) species seems to be present in the product obtained in the pyrolysis temperature range between 600 and 1000 degrees C. PMID:17418540

  13. Comparison of corrosion behavior of EUROFER and CLAM steels in flowing Pb-15.7Li

    NASA Astrophysics Data System (ADS)

    Konys, J.; Krauss, W.; Zhu, Z.; Huang, Q.

    2014-12-01

    Ferritic martensitic steels are envisaged to be applied as structural materials in HCLL blanket systems. Their compatibility with the liquid breeder, which is in direct contact with the structural alloy, will be essential for reliable and safe operation of the designed blankets. Formerly performed corrosion tests of RAFM steels in PICOLO loop of KIT were mainly done at high flow velocities, e.g., 0.22 m/s and delivered severe attack with material loss rates above 400 μm/yr at 823 K. Meanwhile, flow velocities for corrosion testing have been reduced into the 'cm range' to be near fusion relevant conditions. Among the international ITER-partners, many varieties of RAFM steels have been developed and manufactured within the last decade, e.g., the so-called Chinese Low Activation Martensitic steel (CLAM). In this paper, the long term corrosion behavior of EUROFER and CLAM steel in flowing Pb-15.7Li will be presented at a flow velocity of about 0.10 m/s and compared with earlier obtained results of RAFM steels exposed at other operation parameters of PICOLO loop. The observed corrosion attack is near 220 μm/yr and fits well to predictions made by MATLIM-modeling for low flow velocities in the turbulent flow regime.

  14. Visualizing skin effects in conductors with MRI: 7Li MRI experiments and calculations

    NASA Astrophysics Data System (ADS)

    Ilott, Andrew J.; Chandrashekar, S.; Klöckner, Andreas; Chang, Hee Jung; Trease, Nicole M.; Grey, Clare P.; Greengard, Leslie; Jerschow, Alexej

    2014-08-01

    While experiments on metals have been performed since the early days of NMR (and DNP), the use of bulk metal is normally avoided. Instead, often powders have been used in combination with low fields, so that skin depth effects could be neglected. Another complicating factor of acquiring NMR spectra or MRI images of bulk metal is the strong signal dependence on the orientation between the sample and the radio frequency (rf) coil, leading to non-intuitive image distortions and inaccurate quantification. Such factors are particularly important for NMR and MRI of batteries and other electrochemical devices. Here, we show results from a systematic study combining rf field calculations with experimental MRI of 7Li metal to visualize skin depth effects directly and to analyze the rf field orientation effect on MRI of bulk metal. It is shown that a certain degree of selectivity can be achieved for particular faces of the metal, simply based on the orientation of the sample. By combining rf field calculations with bulk magnetic susceptibility calculations accurate NMR spectra can be obtained from first principles. Such analyses will become valuable in many applications involving battery systems, but also metals, in general.

  15. Cross-section measurements of 7Be + d --> p + α + α and 7Li + d --> n + α + α with ANASEN and their implication in the Standard Big Bang Nucleosynthesis(SBBN)

    NASA Astrophysics Data System (ADS)

    Rijal, Nabin; Wiedenhover, Ingo; Baby, L. T.; Belarge, J.; Kuvin, S.; Blackmon, J. C.; Macon, K. T.; Santiago-Gonzalez, D.; Koshchiy, E.; Rogachev, G.

    2016-03-01

    Astrophysically observed 7Li is 3-4 times less than predicted by current models of SBBN. The nuclear reaction 7Be + d at energies relevant to SBBN, has been discussed as a possible means to destroy mass-7 nuclei. We investigate the 7Be + d reaction at SBBN energies using a radioactive 7Be beam and deuterium gas target inside ANASEN (Array for Nuclear Astrophysics Studies with Exotic Nuclei). ANASEN is an active target detector system which tracks the charged particles using a position sensitive proportional counter and 24-SX3 and 4-QQQ position sensitive Silicon detectors, all backed up by CsI detectors. The experiment measures a continuous excitation function by slowing down the beam in the target gas down to zero energy. Our set-up provides a high detection efficiency for all relevant reaction channels. We also performed an experiment for the mirror nuclear reaction 7Li + d with ANASEN in solid target mode as well as in gas target mode. The preliminary results of these experiments along with details of ANASEN will be presented. This work is supported by the US NSF MRI program, Grant No. PHY-0821308 and NSF Grant PHY-1401574.

  16. The 10B(n,α0)7Li and 10B(n,αlγ)7Li alpha-particle angular distributions, branching ratios and cross-sections measurements for En < 3 MeV

    NASA Astrophysics Data System (ADS)

    Hambsch, F. J.; Ruskov, I.; Vidali, M.

    2010-01-01

    The 10B(n,α0)7Li and 10B(n,αiγ)7Li angular distributions have been measured at the GELINA time-of-flight spectrometer in the incident neutron energy range from 0.1 keV to 1 MeV by means of a twin Frisch-grid ionization chamber. With this type of detector it is possible to measure the angular distribution of the charged reaction fragments in a close to 2×2π solid angle with ~100% efficiency and a clear separation of both reaction channels: emission to the 7Li ground state (α0) or to its first excited state (α1). A strong angular anisotropy was observed at ~ 520 keV. In order to extend the energy range up to 2.5-3 MeV and to measure, also, the reaction cross sections, a double twin Frisch-grid ionization chamber was constructed. It is loaded with two very thin 94% 10B-enriched samples, mounted back-to-back with 235U samples on the common cathodes. New data acquisition, visualization and analysis software is used in a new set of long-term measurements, which are still going on.

  17. Elastic and inelastic scattering of polarized [sup 6]Li by [sup 26]Mg at 60 MeV

    SciTech Connect

    Ward, R.P.; Clarke, N.M. School of Physics and Space Research, University of Birmingham, Edgbaston, Birmingham B152TT ); Pearce, K.I.; Pinder, C.N. ); Blyth, C.O.; Choi, H.D.; Dee, P.R.; Roman, S.; Tungate, G. ); Davis, N.J. )

    1994-08-01

    Angular distributions of differential cross section and vector analyzing power have been measured for the elastic and inelastic scattering of polarized [sup 6]Li by [sup 26]Mg at 60 MeV bombarding energy. The data have been compared with the results of coupled-channels calculations using phenomenological potentials and coupling strengths derived from inelastic scattering cross-section data and [ital B]([ital E]2) values. The data are reproduced by calculations including couplings between the ground and excited states of the projectile.

  18. Microanalytical techniques for boron analysis using the 10B(n,alpha)7Li reaction.

    PubMed

    Fairchild, R G; Gabel, D; Laster, B H; Greenberg, D; Kiszenick, W; Micca, P L

    1986-01-01

    In order to predict the efficacy of boronated compounds for neutron capture therapy (NCT), it is mandatory that the boron concentration in tissues be known. Various techniques for measurement of trace amounts of boron (1-100 ppm) are available, including chemical and physical procedures. Experience has shown that, with the polyhedral boranes and carboranes in particular, the usual colorimetric and spark emission spectroscopic methods are not reliable. Although these compounds may be traced with additional radiolabels, direct physical detection of boron by nondestructive methods is clearly preferable. Boron analysis via detection of the prompt-gamma ray from the 10B(n, alpha)7Li reaction has been shown to be a reliable technique. Two prompt-gamma facilities developed at Brookhaven National Laboratory are described. One, at the 60-MW high flux beam reactor, uses sophisticated beam extraction techniques to enhance thermal neutron intensity and reduce fast neutron and gamma contamination. The other was constructed at Brookhaven's 5-MW medical research reactor and uses conventional shielding and electronics to provide an "on-line" boron analysis facility adjacent to beams designed for NCT, thus satisfying one of the requisites for clinical application of this procedure. Technical restrictions attendant upon the synthesis and testing of boronated biomolecules often require the measurement of trace amounts of boron in extremely small (mg) samples. A track-etching technique capable of detecting ng amounts of boron in mg liquid or cell samples is described. Thus it is possible to measure the boron content in small amounts (mg samples) of antibodies, or boron uptake in cells grown in tissue culture. PMID:3951409

  19. Development of a new fast neutron spectrometer using 6Li-depleted Cs2LiYCl6 scintillators

    NASA Astrophysics Data System (ADS)

    D'Olympia, Nathan W.

    A unique alternative to traditional methods of fast neutron spectroscopy was explored in this work using 6Li-depleted Cs 2LiYCl6:Ce (CLYC) scintillators. These inorganic scintillators were found to provide spectroscopic information on fast neutrons via the 35Cl(n,p)35S and 35Cl(n,alpha) 32P reactions and exhibit neutron/gamma pulse-shape discrimination. In additional to detailed characterizations of the material's response function, an array of 16 6Li-depleted CLYC detectors (C7LYC) was designed, constructed, and tested for future applications in neutron spectroscopy. Measurements of mono-energetic neutrons up to 20 MeV were carried out at the University of Kentucky and used to characterize the detector's response. Monte Carlo simulations of the response were carried out with MCNPX to investigate the various reaction mechanisms involved in the total response. Measurements of a continuous spallation neutron source with energies up to 700 MeV were carried out at the Los Alamos Neutron Science Center (LANSCE) using the time-of-flight method to measure the light output as a function of incident neutron energy and generate a detector response matrix. Spectral unfolding of C7LYC's response was investigated using the Maximum Likelihood Expectation Maximization method. The performance of the 16-detector array, SCANS, was studied to determine rate and energy dependent properties of the detectors, such as resolution, and pulse-shape discrimination, when exposed to fast neutrons and gamma-rays.

  20. The effect of breakup of 6Li on elastic scattering and fusion with 28Si at near barrier energies

    NASA Astrophysics Data System (ADS)

    Sinha, Mandira; Roy, Subinit; Basu, P.; Majumdar, H.

    2016-01-01

    Elastic scattering angular distributions for 6Li+28Si system were measured at Elab = 16, 21MeV and analyzed along with the existing data from the previous measurements in the energy range of Elab = 7.5 - 27MeV. The measured cross-sections and the existing data, forming a set of angular distributions over a range of E/Vb = 0.9 - 3.23, were analyzed using the phenomenological optical model potential (OMP). Three different sets of potential parameters were used. The energy dependence of the real and the imaginary potential strengths were, subsequently, extracted at the radius of sensitivity (Rav) for the system. Continuum Discretized Coupled Channel (CDCC) calculation was performed to explore the contribution of projectile break-up (BU) on the observed energy dependence of the effective potential for elastic scattering of 6Li from 28Si. The energy variation of the strength of the real potential with continuum coupling was found to agree with the energy dependence of the same extracted from the (OMP) analysis at energies around the barrier. But the behavior of the imaginary strength appeared to be different. The calculated fusion cross-sections, including the effect of BU, clearly overestimated the measured fusion excitation function data in the below and near barrier energies but compared well with the data at higher energies.

  1. Resonance and non-resonance effect of continuum states of 6Li on elastic scattering angular distributions

    NASA Astrophysics Data System (ADS)

    Gómez Camacho, A.

    2016-07-01

    CDCC calculations of elastic scattering angular distributions for reactions of the weakly bound projectile 6Li with targets 28Si and 58Ni at energies around the Coulomb barrier are presented. Special emphasis is given to account for the effect of couplings from 6Li resonance states l = 2, J π = 3+, 2+, 1+. Similarly, the effect produced by non-resonant state couplings is studied. The convergent calculations are carried out with global α-target and d-target interactions. The calculated elastic scattering angular distributions are in general in good agreement with the measurements for the systems considered in this work. It is found that the calculations with only resonance states are very similar to that with all couplings (resonance+non-resonance). So, the absence of these states have a strong effect on elastic scattering (non-resonance states calculation). It is shown that the effects increase as the collision energy increases. An interpretation of the strength of the different effects is given in terms of the polarization potentials that emerge from the different couplings.

  2. Localization of vacancies and mobility of lithium ions in Li2ZrO3 as obtained by 6,7Li NMR

    NASA Astrophysics Data System (ADS)

    Baklanova, Ya. V.; Arapova, I. Yu.; Buzlukov, A. L.; Gerashenko, A. P.; Verkhovskii, S. V.; Mikhalev, K. N.; Denisova, Т. А.; Shein, I. R.; Maksimova, L. G.

    2013-12-01

    The 6,7Li NMR spectra and the 7Li spin-lattice relaxation rate were measured on polycrystalline samples of Li2ZrO3, synthesized at 1050 K and 1300 K. The 7Li NMR lines were attributed to corresponding structural positions of lithium Li1 and Li2 by comparing the EFG components with those obtained in the first-principles calculations of the charge density in Li2ZrO3. For both samples the line width of the central 7Li transition and the spin-lattice relaxation time decrease abruptly at the temperature increasing above ~500 K, whereas the EFG parameters are averaged (<νQ>=42 (5) kHz) owing to thermally activated diffusion of lithium ions.

  3. Improved information on the 7Li+p{yields}{alpha}+{alpha} reaction via the Trojan Horse Method applied to the 3He break-up

    SciTech Connect

    Tumino, A.; Spitaleri, C.; Sergi, M. L.; Cherubini, S.; La Cognata, M.; Lamia, L.; Pizzone, R. G.; Romano, S.; Tudisco, S.; Kroha, V.; Burjan, V.; Novac, J.; Vincour, J.; Fulop, S.; Somorjai, E.

    2006-04-26

    The astrophysically relevant 7Li+p{yields}{alpha}+{alpha} reaction was investigated via the THM by selecting the quasi-free contribution to the measured 3He+7Li{yields}{alpha}+{alpha}+d three-body process. This investigation is mainly aimed at testing the validity of the pole approximation in the THM against the bound structure of the Trojan-horse nucleus. The three-body experiment was performed at 33 MeV, corresponding to a 7Li-p relative energy ranging from 0.2 to 7 MeV. The quasi-free 7Li+p cross-section was compared with the free reaction cross-section as well as with indirect data from a previous THM experiment. The good agreement between data sets throughout the energy range investigated provided a very important validity test of the pole approximation for the THM.

  4. Irradiation characteristics of BNCT using near-threshold 7Li(p, n)7Be direct neutrons: application to intra-operative BNCT for malignant brain tumours.

    PubMed

    Tanaka, Kenichi; Kobayashi, Tooru; Sakurai, Yoshinori; Nakagawa, Yoshinobu; Ishikawa, Masayori; Hoshi, Masaharu

    2002-08-21

    A calculation method for the dosage of neutrons by near-threshold 7Li(p, n)7Be and gamma rays by 7Li(p, p'gamma)7Li was validated through experiments with variable distance between the Li target and the phantom, focusing on large angular dependence. The production of neutrons and gamma rays in the Li target was calculated by Lee's method and their transport in the phantom was calculated using the MCNP-4B code. The dosage in intra-operative boron neutron capture therapy (BNCT) using near-threshold 7Li(p, n)7Be direct neutrons was evaluated using the validated calculation method. The effectiveness of the usage of the direct neutrons was confirmed from the existence of the region satisfying the requirements of the protocol utilized in intra-operative BNCT for brain tumours in Japan. The boron-dose enhancer (BDE) introduced in this paper to increase the contribution of the 10B(n, alpha)7Li dose in the living body was effective. The void utilized to increase the dose in deep regions was also effective with BDE. For the investigation of 1.900 MeV proton beams, for example, it was found that intraoperative BNCT using near-threshold 7Li(p, n)7Be direct neutrons is feasible. PMID:12222863

  5. Localization of vacancies and mobility of lithium ions in Li{sub 2}ZrO{sub 3} as obtained by {sup 6,7}Li NMR

    SciTech Connect

    Baklanova, Ya. V.; Arapova, I. Yu.; Buzlukov, A.L.; Gerashenko, A.P.; Verkhovskii, S.V.; Mikhalev, K.N.; Denisova, T.A.; Shein, I.R.; Maksimova, L.G.

    2013-12-15

    The {sup 6,7}Li NMR spectra and the {sup 7}Li spin–lattice relaxation rate were measured on polycrystalline samples of Li{sub 2}ZrO{sub 3}, synthesized at 1050 K and 1300 K. The {sup 7}Li NMR lines were attributed to corresponding structural positions of lithium Li1 and Li2 by comparing the EFG components with those obtained in the first-principles calculations of the charge density in Li{sub 2}ZrO{sub 3}. For both samples the line width of the central {sup 7}Li transition and the spin–lattice relaxation time decrease abruptly at the temperature increasing above ∼500 K, whereas the EFG parameters are averaged (〈ν{sub Q}〉=42 (5) kHz) owing to thermally activated diffusion of lithium ions. - Graphical abstract: Path of lithium ion hopping in lithium zirconate Li{sub 2}ZrO{sub 3}. - Highlights: • Polycrystalline samples Li{sub 2}ZrO{sub 3} with monoclinic crystal structure synthesized at different temperatures were investigated by {sup 6,7}Li NMR spectroscopy. • Two {sup 6,7}Li NMR lines were attributed to the specific structural positions Li1 and Li2. • The distribution of vacancies was clarified for both lithium sites. • The activation energy and pathways of lithium diffusion in Li{sub 2}ZrO{sub 3} were defined.

  6. AN UPDATED {sup 6}Li(p, {alpha}){sup 3}He REACTION RATE AT ASTROPHYSICAL ENERGIES WITH THE TROJAN HORSE METHOD

    SciTech Connect

    Lamia, L.; Spitaleri, C.; Sergi, M. L.; Pizzone, R. G.; Tumino, A.; La Cognata, M.; Tognelli, E.; Degl'Innocenti, S.; Prada Moroni, P. G.; Pappalardo, L.

    2013-05-01

    The lithium problem influencing primordial and stellar nucleosynthesis is one of the most interesting unsolved issues in astrophysics. {sup 6}Li is the most fragile of lithium's stable isotopes and is largely destroyed in most stars during the pre-main-sequence (PMS) phase. For these stars, the convective envelope easily reaches, at least at its bottom, the relatively low {sup 6}Li ignition temperature. Thus, gaining an understanding of {sup 6}Li depletion also gives hints about the extent of convective regions. For this reason, charged-particle-induced reactions in lithium have been the subject of several studies. Low-energy extrapolations of these studies provide information about both the zero-energy astrophysical S(E) factor and the electron screening potential, U{sub e} . Thanks to recent direct measurements, new estimates of the {sup 6}Li(p, {alpha}){sup 3}He bare-nucleus S(E) factor and the corresponding U{sub e} value have been obtained by applying the Trojan Horse method to the {sup 2}H({sup 6}Li, {alpha} {sup 3}He)n reaction in quasi-free kinematics. The calculated reaction rate covers the temperature window 0.01 to 2T{sub 9} and its impact on the surface lithium depletion in PMS models with different masses and metallicities has been evaluated in detail by adopting an updated version of the FRANEC evolutionary code.

  7. Role of channel coupling and deuteron-exchange mechanisms in anomalous alpha-particle scattering on {sup 6}Li

    SciTech Connect

    Sakuta, S. B.; Artemov, S.V.; Burtebaev, N.; Kerimkulov, Zh.; Novatsky, B. G.; Stepanov, D.N.; Yarmukhamedov, R.

    2009-12-15

    A unified description of existing experimental data on alpha-particle scattering by {sup 6}Li over the broad energy range from 18 to 166 MeV was obtained with allowance for channel-coupling effects and mechanisms involving the exchange of a deuteron cluster. Angular distributions were analyzed on the basis of the optical model and the coupled reaction channels method. It was shown that the inclusion of channel coupling and the contributions from one- and two-step exchangemechanismsmakes it possible to describe special features of the behavior of differential cross sections for both elastic and inelastic scattering in a full energy range. Optimum values found for the parameters of optical potentials agree with the parameters of the global potential proposed previously for nuclei in the mass region A > 12.

  8. One-neutron stripping processes to excited states of the 6Li+96Zr reaction at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Hu, S. P.; Zhang, G. L.; Yang, J. C.; Zhang, H. Q.; Gomes, P. R. S.; Lubian, J.; Ferreira, J. L.; Wu, X. G.; Zhong, J.; He, C. Y.; Zheng, Y.; Li, C. B.; Li, G. S.; Qu, W. W.; Wang, F.; Zheng, L.; Yu, L.; Chen, Q. M.; Luo, P. W.; Li, H. W.; Wu, Y. H.; Zhou, W. K.; Zhu, B. J.; Sun, H. B.

    2016-01-01

    We report the measurement of one-neutron stripping to excited-state cross sections from the weakly bound projectile 6Li to the 96Zr target at near-barrier energies by the online γ -ray spectroscopy method. Transitions of the 97Zr nucleus were clearly identified by γ -γ coincidences. This cross section was found to be much smaller than the previously reported complete-fusion cross section for this system at energies above the barrier, whereas it becomes of the same magnitude around the Coulomb-barrier energy. No evidence of two-neutron transfer was found. We also performed coupled reaction channel calculations for the one-neutron stripping process. The calculation results are discussed.

  9. Low-energy R -matrix fits for the 6Li(d ,α ) 4HeS factor

    NASA Astrophysics Data System (ADS)

    Grineviciute, J.; Lamia, L.; Mukhamedzhanov, A. M.; Spitaleri, C.; La Cognata, M.

    2015-01-01

    Background: Information about the 6Li(d ,α ) 4He reaction rates of astrophysical interest can be obtained by extrapolating direct data to lower energies, or by indirect methods. The indirect Trojan horse method, as well as various R -matrix and polynomial fits to direct data, estimate electron screening energies much larger than the adiabatic limit. Calculations that include the subthreshold resonance estimate smaller screening energies. Purpose: Obtain the 6Li(d,α ) 4He reaction R -matrix parameters and the bare astrophysical S factor for energies relevant to the stellar plasmas by fitting R -matrix formulas for the subthreshold resonances to the S -factor data above 60 keV. Methods: The bare S factor is calculated using the single- and the two-level R -matrix formulas for the closest to the threshold 0+ and 2+ subthreshold states at 22.2 ,20.2 , and 20.1 MeV. The electron screening potential U e is then obtained by fitting it as a single parameter to the low-energy data. The calculations are also done by fitting U e simultaneously with other parameters. Results: The low-energy S factor is dominated by the 2+ subthreshold resonance at 22.2 MeV. The influence of the other two subthreshold states is small. The resultant electron screening is smaller than the adiabatic value. The fits that neglect the electron screening above 60 keV produce a significantly smaller electron screening potential. The calculations show a large ambiguity associated with a choice of the initial channel radius. Conclusions: The R -matrix fits do not show a significantly larger Ue than predicted by the atomic physics models. The R -matrix best fit provides U e=149.5 eV and Sb(0 ) =21.7 MeV b.

  10. Microscopic Calculation of Astrophysical S-factor and Branching Ratio for the 3H(α, γ)7Li Reaction

    NASA Astrophysics Data System (ADS)

    Solovyev, Alexander S.; Igashov, Sergey Yu.; Tchuvill'sky, Yury M.

    2015-01-01

    In the present work the radiative capture reaction 3H(α, γ)7Li has been investigated. The astrophysical S-factor and the branching ratio of the reaction have been calculated within a microscopic approach - the algebraic version of the resonating-group model. The lowest compatible with the Pauli exclusion principle wave functions of the translation-invariant oscillator shell model are adopted as the internal wave functions of the colliding clusters. The modified Hasegawa-Nagata NN-potential was employed in the calculations. The results are in good agreement with the experimental data.

  11. R-matrix Analysis for the 8Be System and Features in the p+7Li Reaction Over Resonance Region

    NASA Astrophysics Data System (ADS)

    Kunieda, Satoshi

    2016-06-01

    A comprehensive R-matrix analysis is currently underway for the 8Be compound system toward a consistent evaluation of the p+7Li reaction cross-sections over the resonance energy region. In this analysis, the energy eigenvalues are fixed to the level energies given in ENSDF, and we searched for values of the boundary condition parameters as well as the reduced-width amplitudes. It is found that some additional levels are necessary to fit the resonant shape of experimental cross-sections. Besides, the channel radii obtained may be consistent with well-known physical pictures of the atomic nucleus.

  12. Epithermal neutron beams from the 7 Li(p,n) reaction near the threshold for neutron capture therapy

    NASA Astrophysics Data System (ADS)

    Porras, I.; Praena, J.; Arias de Saavedra, F.; Pedrosa, M.; Esquinas, P.; L. Jiménez-Bonilla, P.

    2016-11-01

    Two applications for neutron capture therapy of epithermal neutron beams calculated from the 7Li ( p , n reaction are discussed. In particular, i) for a proton beam of 1920 keV of a 30 mA, a neutron beam of adequate features for BNCT is found at an angle of 80° from the forward direction; and ii) for a proton beam of 1910 keV, a neutron beam is obtained at the forward direction suitable for performing radiobiology experiments for the determination of the biological weighting factors of the fast dose component in neutron capture therapy.

  13. Elastic Scattering Of {sup 6,7}Li+{sup 80}Se At Near And Above Barrier Energies

    SciTech Connect

    Fimiani, L.; Marti, G. V.; Capurro, O. A.; Barbara, E. de; Testoni, J. E.; Zalazar, L.; Arazi, A.; Cardona, M. A.; Carnelli, P.; Figueira, J. M.; Hojman, D.; Martinez Heimann, D.; Negri, A. E.; Pacheco, A. J.; Fernandez Niello, J. O.

    2010-08-04

    In this work we propose to study the elastic scattering of the weakly bound projectiles {sup 6,7}Li on an intermediate mass target {sup 80}Se. From the experimental results presented here, precise angular distributions at energies below, around and above the nominal Coulomb barriers of the systems were obtained. The final goal of our work is to determine the characteristic parameters of the optical potential and use them to address the question of whether the usual threshold anomaly or the breakup threshold anomaly are present or not in these systems.

  14. Quasi-elastic Scattering Measurements in the {sup 6,7}Li+{sup 144}Sm Systems

    SciTech Connect

    Capurro, O. A.; Arazi, A.; Fernandez Niello, J. O.; Figueira, J. M.; Marti, G. V.; Martinez Heimann, D.; Negri, A. E.; Pacheco, A. J.; Monteiro, D. S.; Otomar, D. R.; Gomes, P. R. S.

    2009-06-03

    In the present work, results of measurements of quasi-elastic scattering cross sections using a silicon-telescope detector at backward angles are reported. They allowed us to deduce fusion barrier distributions from the first derivative of the corresponding excitation function (-d(d{sigma}{sub qes}/d{sigma}{sub Rut})/dE). We report data for the systems {sup 6,7}Li on {sup 144}Sm which are characterized by loosely bound projectiles onto a closed neutron shell target. The experimental excitation functions and the associated barrier distributions are compared for both systems.

  15. Calorimetria nucleare in collisioni tra ioni pesanti ad energie intermedie

    NASA Astrophysics Data System (ADS)

    Spezzi, L.

    2002-07-01

    Nel presente lavoro di tesi ci si e' occupati di uno studio sistematico di misure di temperatura ed energia di eccitazione in sistemi nucleari formati in reazioni tra ioni pesanti ad energie intermedie. La temperatura a stata misurata tramite due diversi metodi: rapporto tra le rese di isotopi che differiscono di uno stesso numero di nucleoni ( d/t-3He/4He , 3He/4He -6Li/7Li) - temperatura isotopica -, e rapporto tra le popolazioni degli stati eccitati in frammenti instabili (5Li e 6Li) che decadono in particelle leggere in coincidenza - temperatura di emissione. Le misure in esame sono state effettuate presso i Laboratori Nazionali del Sud per i sistemi 93Nb+93Nb, 93Nb+116,124Sn, 116,120Sn+116,124Sn e 116Sn+93Nb ad energie comprese tra 17 e 40 A MeV. L'apparato di rivelazione era costituito da un odoscopio ad alta granularite (96 telescopi Si (50micron)-Si(300micron)-CsI(Tl) ) e basse soglie di rivelazione, utilizzato sia per identificare risonanze in frammenti eccitati che per misure di rese di isotopi di frammenti con 2<=Z<=6, e dal multirivelatore FIASCO che, grazie alla misura contemporanea di posizione e tempo di volo dei frammenti provenienti dal proiettile (PLF - Projectile Like Fragments) e dal bersaglio (TLF - Target Like Fragment), e' stato utilizzato per misurare direttamente l'energia di eccitazione del sistema in studio. Analisi precedenti, condotte nell'ambito di varie collaborazioni, hanno messo in evidenza la possible esistenza di una transizione di fase liquido-gas del primo ordine nella materia nucleare. In tale contesto, ci siamo occupati di una verifica della curva calorica nucleare, ovvero della correlazione esistente fra temperatura ed energia di eccitazione del sistema, indagando, nel contempo, sulla sua dipendenza dalla massa del sistema che si frammenta. Si e' effettuato, inoltre, un confronto fra i due diversi metodi di misura della temperatura (temperatura isotopica e di emissione): l'andamento plateau-like della curva calorica e' stato

  16. Complete and Incomplete Fusion of {sup 6}He and {sup 6}Li Projectiles with Medium Mass Targets at Energy {approx}10 AMeV

    SciTech Connect

    Krupko, S. A.; Daniel, A. V.; Fomichev, A. S.; Golovkov, M. S.; Gorshkov, V. A.; Oganessian, Yu. Ts.; Popeko, G. S.; Sidorchuk, S. I.; Ter-Akopian, G. M.; Slepnev, R. S.; Chudoba, V.; Standylo, L.; Chepigin, V. I.; Katrasev, D. E.; Malyshev, O. N.; Svirikhin, A. I.; Yeremin, A. V.; Wolski, R.; Briancon, Ch.; Hauschild, K.

    2009-03-04

    Complete fusion (CF) and incomplete fusion (ICF) reactions were studied with the beams of loosely bound {sup 6}He and {sup 6}Li bombarding {sup 166}Er and {sup 165}Ho targets. Experiments were carried out to test an approach exploiting the measured intensities of {gamma} rays emitted at the transitions between the yrast-band levels of reaction products formed after the termination of neutron evaporation. Partial waves feeding the CF [{sup 165}Ho({sup 6}Li,5n){sup 166}Yb, {sup 166}Er({sup 6}He,6n){sup 166}Yb] and ICF [{sup 165}Ho({sup 6}Li,{alpha}3n){sup 164}Er, and {sup 166}Er({sup 6}He,{alpha}4n){sup 164}Er] reaction channels were revealed from the obtained {gamma}-ray data.

  17. Using the Doppler broadened γ line of the 10B(n,αγ)7Li reaction for thermal neutron detection

    NASA Astrophysics Data System (ADS)

    Ben-Galim, Y.; Wengrowicz, U.; Moreh, R.; Orion, I.; Raveh, A.

    2016-02-01

    When a thermal neutron is absorbed by 10B in the 10B(n,α)7Li reaction, there is a chance of 94% that a 478 keV photon be emitted by an excited 7Li nucleus. This reaction is exothermic with a Q-value of 2.31 MeV and the nuclei are emitted with kinetic energies of E(α)=1.47 MeV and E(7Li*)=0.84 MeV. This implies that the 478 keV γ line is emitted by a moving 7Li nucleus and hence is expected to be Doppler broadened. In the present work we suggest to use this broadening of the γ line as a fingerprint for the detection of thermal neutrons using a high resolution gamma spectrometer. We thus developed a Monte Carlo program using a MATLAB code based on a High Purity Germanium (HPGe) detector coupled with a Boron Carbide (B4C) sheet to calculate the γ line broadening. Our simulation shows that the FWHM width of the resulting γ line is 12.6 keV, in good agreement with our measurement. Hence the broadened γ line emitted by the 10B(n,αγ)7Li reaction and detected by a HPGe detector shows that this method is an effective tool for neutron detection while maintaining good gamma discrimination.

  18. Improved neutron-gamma discrimination for a 6Li-glass neutron detector using digital signal analysis methods

    DOE PAGESBeta

    Wang, Cai -Lin; Riedel, Richard A.

    2016-01-14

    A 6Li-glass scintillator (GS20) based neutron Anger camera was developed for time-of-flight single-crystal diffraction instruments at SNS. Traditional pulse-height analysis (PHA) for neutron-gamma discrimination (NGD) resulted in the neutron-gamma efficiency ratio (defined as NGD ratio) on the order of 104. The NGD ratios of Anger cameras need to be improved for broader applications including neutron reflectometers. For this purpose, five digital signal analysis methods of individual waveforms from PMTs were proposed using: i). pulse-amplitude histogram; ii). power spectrum analysis combined with the maximum pulse amplitude; iii). two event parameters (a1, b0) obtained from Wiener filter; iv). an effective amplitude (m)more » obtained from an adaptive least-mean-square (LMS) filter; and v). a cross-correlation (CC) coefficient between an individual waveform and a reference. The NGD ratios can be 1-102 times those from traditional PHA method. A brighter scintillator GS2 has better NGD ratio than GS20, but lower neutron detection efficiency. The ultimate NGD ratio is related to the ambient, high-energy background events. Moreover, our results indicate the NGD capability of neutron Anger cameras can be improved using digital signal analysis methods and brighter neutron scintillators.« less

  19. Hypernuclear production cross section in the reaction of 6Li + 12C at 2 A GeV

    NASA Astrophysics Data System (ADS)

    Rappold, C.; Saito, T. R.; Bertini, O.; Bianchin, S.; Bozkurt, V.; Kim, E.; Kavatsyuk, M.; Ma, Y.; Maas, F.; Minami, S.; Nakajima, D.; Özel-Tashenov, B.; Yoshida, K.; Achenbach, P.; Ajimura, S.; Aumann, T.; Ayerbe Gayoso, C.; Bhang, H. C.; Caesar, C.; Erturk, S.; Fukuda, T.; Göküzüm, B.; Guliev, E.; Hoffmann, J.; Ickert, G.; Ketenci, Z. S.; Khaneft, D.; Kim, M.; Kim, S.; Koch, K.; Kurz, N.; Le Fèvre, A.; Mizoi, Y.; Nungesser, L.; Ott, W.; Pochodzalla, J.; Sakaguchi, A.; Schmidt, C. J.; Sekimoto, M.; Simon, H.; Takahashi, T.; Tambave, G. J.; Tamura, H.; Trautmann, W.; Voltz, S.; Yoon, C. J.

    2015-07-01

    Hypernuclear production cross sections have been deduced for the first time with induced reaction of heavy ion beam on fixed target and by means of the invariant mass method by the HypHI Collaboration exploiting the reaction of 6Li + 12C at 2 A GeV or √{sNN} = 2.70 GeV. A production cross section of 3.9 ± 1.4 μb for 3ΛH and of 3.1 ± 1.0 μb for 4ΛH respectively in the projectile rapidity region was inferred as well as the total production cross section of the Λ hyperon was measured and found to be equal to 1.7 ± 0.8 mb. A global fit based on a Bayesian approach was performed in order to include and propagate statistical and systematic uncertainties. Production ratios of 3ΛH/4ΛH, 3ΛH/Λ and 4ΛH/Λ were included in the inference procedure. The strangeness population factors S3 and S4 of 3ΛH and 4ΛH respectively were extracted. In addition, the multiplicities of the Λ hyperon, 3ΛH, and 4ΛH together with the rapidity and transversal momentum density distributions of the observed hypernuclei were extracted and reported.

  20. Determination of the ground-state potential energy curve of 6LiH up to dissociation

    NASA Astrophysics Data System (ADS)

    Verma, K. K.; Stwalley, W. C.

    1982-09-01

    An ultraviolet argon ion laser (3336 Å) has been used to excite the A 1Σ+-X1Σ+ system of the 6LiH molecule. A long progression of R-P doublets is observed in the range 0⩽v''⩽21. This is the first time ground-state levels above v''=12 have been observed for the lithium hydride molecule. Based upon these results, we have constructed a Rydberg-Klein-Rees (RKR) potential energy curve which corresponds to over 99% of the ground state potential well. This experimental curve is compared with theoretical ab initio calculations for the X 1Σ+ state of LiH. We find that Docken and Hinze's X state potential energy curve [J. Chem. Phys. 57, 4928 (1972)] is probably the most accurate among the published ab initio calculations in the region of curve crossing of the zero order curves representing the ionic and covalent configurations of LiH, although some more recent calculations are of comparable accuracy.

  1. Ionic conductivity in the crystalline polymer electrolytes PEO6:LiXF6, X = P, As, Sb.

    PubMed

    Stoeva, Zlatka; Martin-Litas, Isabelle; Staunton, Edward; Andreev, Yuri G; Bruce, Peter G

    2003-04-16

    Ionically conducting polymers (salts dissolved in a polymer matrix) are of great interest because they uniquely exhibit ionic conductivity in a soft but solid membrane. As such, they are critical to the development of devices such as all-solid-state lithium batteries. The established view of ionic conductivity in polymer electrolytes is that this occurs in amorphous materials above their glass transition temperature and that crystalline polymer electrolytes are insulators. In contrast, we show that three crystalline polymer electrolytes, poly(ethylene oxide)(6):LiXF(6), X = P, As, Sb, not only conduct but do so better than the analogous amorphous phases! It is also shown that the conductivities of all three 6:1 complexes are similar, consistent with the dimension of the bottlenecks to conduction derived from their crystal structures. An increase in ionic conductivity with reduction of molecular weight of the crystalline polymer electrolyte (from 2000 to 1000) is reported and shown to relate to the increase in crystallite size on reducing molecular weight. PMID:12683834

  2. Improved neutron-gamma discrimination for a 6Li-glass neutron detector using digital signal analysis methods

    NASA Astrophysics Data System (ADS)

    Wang, C. L.; Riedel, R. A.

    2016-01-01

    A 6Li-glass scintillator (GS20) based neutron Anger camera was developed for time-of-flight single-crystal diffraction instruments at Spallation Neutron Source. Traditional Pulse-Height Analysis (PHA) for Neutron-Gamma Discrimination (NGD) resulted in the neutron-gamma efficiency ratio (defined as NGD ratio) on the order of 104. The NGD ratios of Anger cameras need to be improved for broader applications including neutron reflectometers. For this purpose, six digital signal analysis methods of individual waveforms acquired from photomultiplier tubes were proposed using (i) charge integration, (ii) pulse-amplitude histograms, (iii) power spectrum analysis combined with the maximum pulse-amplitude, (iv) two event parameters (a1, b0) obtained from a Wiener filter, (v) an effective amplitude (m) obtained from an adaptive least-mean-square filter, and (vi) a cross-correlation coefficient between individual and reference waveforms. The NGD ratios are about 70 times those from the traditional PHA method. Our results indicate the NGD capabilities of neutron Anger cameras based on GS20 scintillators can be significantly improved with digital signal analysis methods.

  3. Improved neutron-gamma discrimination for a (6)Li-glass neutron detector using digital signal analysis methods.

    PubMed

    Wang, C L; Riedel, R A

    2016-01-01

    A (6)Li-glass scintillator (GS20) based neutron Anger camera was developed for time-of-flight single-crystal diffraction instruments at Spallation Neutron Source. Traditional Pulse-Height Analysis (PHA) for Neutron-Gamma Discrimination (NGD) resulted in the neutron-gamma efficiency ratio (defined as NGD ratio) on the order of 10(4). The NGD ratios of Anger cameras need to be improved for broader applications including neutron reflectometers. For this purpose, six digital signal analysis methods of individual waveforms acquired from photomultiplier tubes were proposed using (i) charge integration, (ii) pulse-amplitude histograms, (iii) power spectrum analysis combined with the maximum pulse-amplitude, (iv) two event parameters (a1, b0) obtained from a Wiener filter, (v) an effective amplitude (m) obtained from an adaptive least-mean-square filter, and (vi) a cross-correlation coefficient between individual and reference waveforms. The NGD ratios are about 70 times those from the traditional PHA method. Our results indicate the NGD capabilities of neutron Anger cameras based on GS20 scintillators can be significantly improved with digital signal analysis methods. PMID:26827314

  4. Novel 4{pi} Detection System for the Measurement of the {sup 6}Li(n,{alpha}){sup 3}H Reaction Cross Section

    SciTech Connect

    Giorginis, Georgios; Bencardino, Raffaele

    2011-12-13

    A dedicated one-dimensional Time Projection Chamber (1D-TPC) was designed and produced at IRMM to determine the {sup 6}Li(n,{alpha}){sup 3}H cross section in the 0.4-2.8 MeV energy range, aiming at 5% accuracy. The basic TPC components were a twin gridded ionisation chamber (GIC) with interwired electrodes and fast digitisation of the anode and cathode signals. The energy of both reaction products emitted from a thin {sup 6}LiF sample at the common TPC cathode was measured. A Kr(97%)CO{sub 2}(3%) mixture was used as the detector gas at a pressure up to 3.5 bar. A {sup 238}U sample mounted on the cathode of an ionisation chamber without grid was used as the neutron flux monitor. Special care was taken to reduce the experimental sources of uncertainty. The beam-monitor {sup 238}U sample was characterised at IRMM by low-geometry {alpha}-counting with an accuracy of 0.1%. A {sup 6}Li sample was produced at IRMM by vacuum evaporation of {sup 6}LiF onto transparent aluminium backing. The number of {sup 6}Li atoms will be measured via Thermal Neutron Depth Profiling with an expected accuracy of 2% with respect to an IRMM Standard Reference Material. First test measurements were performed using a monoenergetic neutron beam produced by the T(p,n){sup 3}He reaction at the IRMM 7 MV Van de Graaff accelerator. The experimental method and preliminary results are presented.

  5. Functions of MgH2 in hydrogen storage reactions of the 6LiBH4-CaH2 reactive hydride composite.

    PubMed

    Zhou, Yifan; Liu, Yongfeng; Zhang, Yu; Gao, Mingxia; Pan, Hongge

    2012-08-28

    A significant improvement of hydrogen storage properties was achieved by introducing MgH(2) into the 6LiBH(4)-CaH(2) system. It was found that ~8.0 wt% of hydrogen could be reversibly stored in a 6LiBH(4)-CaH(2)-3MgH(2) composite below 400 °C and 100 bar of hydrogen pressure with a stepwise reaction, which is superior to the pristine 6LiBH(4)-CaH(2) and LiBH(4) samples. Upon dehydriding, MgH(2) first decomposed to convert to Mg and liberate hydrogen with an on-set temperature of ~290 °C. Subsequently, LiBH(4) reacted with CaH(2) to form CaB(6) and LiH in addition to further hydrogen release. Hydrogen desorption from the 6LiBH(4)-CaH(2)-3MgH(2) composite finished at ~430 °C in non-isothermal model, a 160 °C reduction relative to the 6LiBH(4)-CaH(2) sample. JMA analyses revealed that hydrogen desorption was a diffusion-controlled reaction rather than an interface reaction-controlled process. The newly produced Mg of the first-step dehydrogenation possibly acts as the heterogeneous nucleation center of the resultant products of the second-step dehydrogenation, which diminishes the energy barrier and facilitates nucleation and growth, consequently reducing the operating temperature and improving the kinetics of hydrogen storage. PMID:22842399

  6. Elastic recoil detection analysis of hydrogen with 7Li ions using a polyimide foil as a thick hydrogen reference

    NASA Astrophysics Data System (ADS)

    Pelicon, Primož; Razpet, Alenka; Markelj, Sabina; Čadež, Iztok; Budnar, Miloš

    2005-01-01

    Elastic recoil detection analysis (ERDA) with an absorber foil using a 4.2 MeV 7Li2+ beam was utilized for evaluation of hydrogen depth profiles. Since recoil cross-sections when using Li ions as projectiles are not well known, the energy dependent ratio between the experimental yield and the yield calculated using the Rutherford recoil cross-section was obtained from an ERDA spectrum of a thick polyimide (Kapton) sample. It was estimated that this ratio does not significantly depend on sample composition. Therefore it was used for correction of measured spectra analyzed by existing simulation and evaluation programs in which the Rutherford recoil cross-sections were applied. The correction procedure has been verified in round-robin measurements of well-characterized Si:H thin layers. Application of the method for determination of a hydrogen depth concentration profile in hydrogen-containing graphite samples is presented.

  7. Three-body effects in the /sup 7/Li (/ital d/,. cap alpha cap alpha. /ital n/) reaction

    SciTech Connect

    Arena, N.; Cavallaro, S.; Fazio, G.; Giardina, G.; Italiano, A.; Herman, M.; Bruno, M.; Cannata, F.; D'Agostino, M.

    1989-07-01

    Measurements of the differential cross sections for the/sup 7/Li(/ital d/,..cap alpha cap alpha..n) reaction have been performed at deuteron incident energy /ital E/(/ital d/)=6.8 MeV. The kinematical configurations were chosen so as to optimize the population of the /sup 5/He/sup **/ 3/2/sup +/ state with 16.76 MeV excitation energy. The parameters of this resonance are deduced from the experimental data; deviations from the standard values indicate the relevance of three-body effects and/or rescattering. Some phenomenological considerations give a qualitative explanation of the results obtained. In particular, as far as the width is concerned, we observe a broadening with respect to the standard value, which may be related to the presence of a shadow pole.

  8. On optimizing the {sup 7}Li(p,n) proton beam energy and moderator material for BNCT

    SciTech Connect

    Bleuel, D.L.; Donahue, R.J.; Ludewigt, B.A.

    1996-09-01

    The reaction {sup 7}Li(p,n){sup 7}Be has been proposed as an accelerator-based source of neutrons for Boron Neutron Capture Therapy (BNCT). This reaction has a large steep resonance for proton energies around 2.3 MeV which ends at approximately 2.5 MeV. It is generally accepted that the use of 2.5 MeV protons produces the highest yield of neutrons for BNCT. This paper suggests that for BNCT the optimum proton energy may be as low as 2.2-2.3 MeV. The evaluation of the clinical usefulness of the epithermal neutron beams investigated here has been based on depth-dose distributions in a head phantom.

  9. 7Li double quantum filtered NMR and multinuclear relaxation rates of clay suspensions: the effect of clay concentration and nonionic surfactants

    PubMed

    Grandjean; Robert

    1999-05-01

    7Li double quantum NMR spectra were used to investigate ordering process of synthetic Li+-saponites dispersed in water. Synthetic clays suspended in aqueous solutions of poly(ethylene glycol) monoalkyl ethers were also studied by 7Li, 23Na, and 13C NMR techniques. The strongest surfactant-Li+-saponite interaction occurs with the lowest charged clay. Laponite interacts more strongly with organic molecules than does a similarly charged saponite. The number of oxyethylene units rather than the chain length seems to govern the solid-surfactant interaction. Copyright 1999 Academic Press. PMID:10329224

  10. Two-dimensional diffusion in Li0.7NbS2 as directly probed by frequency-dependent 7Li NMR

    NASA Astrophysics Data System (ADS)

    Epp, V.; Nakhal, S.; Lerch, M.; Wilkening, M.

    2013-05-01

    Li ion diffusion in layer-structured Li0.7NbS2 has been complementary investigated by nuclear magnetic resonance (NMR) spectroscopy from an atomic scale point of view. In the present case, 7Li NMR spin-lattice relaxation (SLR) rates R1ρ probed in the rotating frame of reference proved very informative in characterizing the Li self-diffusion process in the van der Waals gap between the NbS2 layers. While temperature-variable SLRρ measurements were used to determine dynamic parameters such as jump rates (τ-1) and the activation energy (Ea), frequency-dependent measurements were used to specify the dimensionality of the diffusion process. In particular, the effect of annealing, i.e., the distribution of Li ions between the layers, on overall Li dynamics has been studied. When plotted in an Arrhenius diagram, the R1ρ rates of an annealed sample, which were recorded at a locking frequency of 20 kHz, pass through a diffusion-induced relaxation peak whose maximum shows up at 320 K. Employing an appropriate diffusion model and appropriately accounting for a non-diffusive background relaxation, a Li jump rate τ-1(300 K) ≈ 1.3 × 105 s-1 and an activation energy Ea of 0.43(2) eV can be deduced. Most importantly, in the high-T limit of the diffusion-induced rate peak, i.e., when ω1τ ≪ 1 holds, the rates follow a logarithmic frequency dependence. This points to a diffusion process of low dimensionality and is in good agreement with predictions of relaxation models developed for 2D diffusion.

  11. Measurement of neutron energy spectra and neutron dose rates from 7Li(p,n)7Be reaction induced on thin LiF target

    NASA Astrophysics Data System (ADS)

    Atanackovic, Jovica; Matysiak, Witold; Dubeau, Jacques; Witharana, Sampath; Waker, Anthony

    2015-02-01

    The measurements of neutron energy spectra and neutron dose rates were performed using the KN Van de Graaff accelerator, located at the McMaster University Accelerator Laboratory (MAL). Protons were accelerated on the thin lithium fluoride (LiF) target and produced mono-energetic neutrons which were measured using three different spectrometers: Bonner Sphere Spectrometer (BSS), Nested Neutron Spectrometer (NNS), and Rotational Proton Recoil Spectrometer (ROSPEC). The purpose of this work is (1) measurement and quantification of low energy accelerator neutron fields in terms of neutron fluence and dose, (2) comparison of results obtained by three different instruments, (3) comparison of measurements with Monte Carlo simulations based on theoretical neutron yields from 7Li(p,n)7Be nuclear reaction, and (4) comparison of results obtained using different neutron spectral unfolding methods. The nominal thickness of the LiF target used in the experiment was 50 μg /cm2, which corresponds to the linear thickness of 0.19 μm and results in approximately 6 keV energy loss for the proton energies used in the experiment (2.2, 2.3, 2.4 and 2.5 MeV). For each of the proton energies, neutron fluence per incident proton charge was measured and several dosimetric quantities of interest in radiation protection were derived. In addition, theoretical neutron yield calculations together with the results of Monte Carlo (MCNP) modeling of the neutron spectra are reported. Consistent neutron fluence spectra were obtained with three detectors and good agreement was observed between theoretically calculated and measured neutron fluences and derived dosimetric quantities for investigated proton energies at 2.3, 2.4 and 2.5 MeV. In the case of 2.2 MeV, some plausibly explainable discrepancies were observed.

  12. Solid-state 23Na and 7Li NMR investigations of sodium- and lithium-reduced mesoporous titanium oxides.

    PubMed

    Lo, Andy Y H; Schurko, Robert W; Vettraino, Melissa; Skadtchenko, Boris O; Trudeau, Michel; Antonelli, David M

    2006-02-20

    Mesoporous titanium oxide synthesized using a dodecylamine template was treated with 0.2, 0.6, and 1.0 equiv of Li- or Na-naphthalene. The composite materials were characterized by nitrogen adsorption, powder X-ray diffraction, X-ray photoelectron spectroscopy, elemental analysis, thermogravimetric analysis, and solid-state 23Na and 7Li NMR spectroscopy. In all cases the wormhole mesoporosity was retained as evidenced by BET surface areas from 400 to 700 m(2)/g, Horvath-Kawazoe pore sizes in the 20 Angstroms range, and a lack of hysteresis in the nitrogen adsorption isotherms. Variable-temperature conductivity studies show that the Li-reduced materials are semiconductors, with conductivity values 3 orders of magnitude higher than those of the Na-reduced materials. Electrochemical measurements demonstrate reversible intercalation/deintercalation of Li+ ions into pristine mesoporous Ti oxides with good cycling capacity. Solid-state 23Na NMR reveals two distinct Na environments: one corresponding to sodium ions in the mesoporous channels and the other corresponding to sodium ions intercalated into the metal framework. 23Na NMR spectra also indicate that the relative population of the framework site increases with increased reduction levels. Solid-state 7Li NMR spectra display a single broad resonance, which increases in breadth with increased reduction levels, though individual resonances inferring the presence of channel and framework Li species are not resolved. Comparisons of the lithium chemical shifts with published values suggests an "anatase-like structure" with no long-range order in the least-reduced samples but a "lithium titanate-like structure" with no long-range order in the higher reduced materials. PMID:16472000

  13. Elastic scattering and fusion cross sections for {sup 7}Be,{sup 7}Li+{sup 27}Al systems

    SciTech Connect

    Kalita, K.; Verma, S.; Singh, R.; Das, J.J.; Jhingan, A.; Madhavan, N.; Nath, S.; Varughese, T.; Sugathan, P.; Parkar, V.V.; Mahata, K.; Ramachandran, K.; Shrivastava, A.; Chatterjee, A.; Kailas, S.; Barua, S.; Basu, P.; Majumdar, H.; Sinha, M.; Bhattacharya, R.

    2006-02-15

    Quasi-elastic-scattering and transfer reaction cross-section measurements were made for the {sup 7}Be+{sup 27}Al system at E{sub lab}=17, 19, and 21 MeV in the angular range {theta}{sub c.m.}=12 deg. An optical model (OM) analysis of the quasi-elastic scattering data was carried out. The fusion cross sections were derived at these energies by subtraction of the integrated transfer cross sections from the reaction cross sections obtained from the fits to quasi-elastic-scattering data. These fusion cross sections were found to be consistent with those obtained from the coupled-channels calculations. Elastic scattering and fusion cross sections were measured for the {sup 7}Li+{sup 27}Al system at E{sub lab}=10, 13, 16, 19, and 24 MeV. For elastic scattering the angular coverages were in the {theta}{sub lab}=12 deg. - 72 deg. range and for fusion the {alpha}-evaporation spectra from the compound nucleus were measured in the angular range {theta}{sub lab}=52 deg. - 132 deg. (142 deg. at 10 MeV). The elastic-scattering angular distributions were subjected to OM analysis. The {alpha}-evaporation spectra were reproduced with the statistical model calculations, and the fusion cross sections were extracted from them. The fusion cross sections were also extracted by subtraction of the integrated inelastic-scattering cross sections from the reaction cross sections obtained from the OM fits to the elastic-scattering data, and these fusion data were found to be consistent. The CCDEF calculations describe these data quite well. A comparison of the fusion data for the {sup 7}Be+{sup 27}Al and {sup 7}Li+{sup 27}Al systems shows a similar and consistent behavior.

  14. Comparison of the effects of couplings to breakup channels in reactions induced by {sup 6}Li and {sup 6}He on the same {sup 64}Zn target

    SciTech Connect

    Fernández-García, J. P. Di Pietro, A.; Figuera, P.; Fisichella, M.; Lattuada, M.; Musumarra, A.; Pellegriti, M. G.; Scuderi, V.; Torresi, D.; Moro, A. M.; Zadro, M.

    2015-10-15

    The experimental elastic scattering angular distributions for the weakly bound nuclei {sup 6,7}Li and for the halo nucleus {sup 6}He on the same {sup 64}Zn target at several energies around the Coulomb barrier were measured at the Laboratori Nazionali del Sud (LNS, Italy) and at the Cyclotron Research Center, Louvain La Neuve (Belgium), respectively. The measured elastic scattering angular distributions of these three systems at the same center of mass energy have been compared. The experimental data of the {sup 6,7}Li+ {sup 64}Zn systems have been analyzed within the CDCC method, while the {sup 6}He+{sup 64}Zn data have been compared with both both CDCC and CRC calculations.

  15. Cross-section measurement for the /sup 7/Li(n,n't)/sup 4/He reaction at 14. 74 MeV

    SciTech Connect

    Smith, D.L.; Meadows, J.W.; Bretscher, M.M.; Cox, S.A.

    1984-09-01

    The cross section for the /sup 7/Li(n,n't)/sup 4/He reaction is measured at an average neutron energy of 14.74 MeV, with a resolution of 0.324 MeV, relative to the /sup 238/U neutron-fission cross section. Tritium activities for the irradiated lithium-metal samples (enriched to 99.95% in /sup 7/Li) are deduced using a liquid-scintillation counting method which relies upon the tritiated-water standard from the US National Bureau of Standards. The measured cross section ratio of /sup 7/Li(n,n't)/sup 4/He to /sup 238/U neutron fission is 0.2523 (+- 2.2%). The derived /sup 7/Li(n,n't)/sup 4/He reaction cross section is 0.301 (+- 5.3%) barn, based on the ENDF/B-V value of 1.193 (+- 4.8%) barn for the /sup 238/U neutron-fission cross section. 59 references.

  16. Vector analyzing power measurement of pion scattering from polarized [sup 7]Li in the region of the [Delta][sub 33] resonance

    SciTech Connect

    Meier, R.; Boschitz, E.; Brinkmoeller, B.; Buehler, J.; Ritt, S.; Wessler, M. ); Konter, J.A.; Mango, S.; van den Brandt, B. ); Efimovykh, V.A.; Kovalev, A.I.; Prokofiev, A.N.; Polyakov, V.V. ); Chaumette, P.; Deregel, J.; Durand, G.; Fabre, J. ); Mach, R. ); Tacik, R. )

    1994-01-01

    The inclusive vector analyzing power [ital iT][sub 11] of [pi][sup +][r arrow][sup 7]Li elastic scattering and inelastic scattering to the 0.47 MeV excited state was measured at several angles for [ital T][sub [pi

  17. Isospin transport effects in nuclear reactions at 25 MeV/nucleon

    SciTech Connect

    Lombardo, I.; Cavallaro, S.; Porto, F.; Rizzo, F.; Russotto, P.; Agodi, C.; Alba, R.; Amorini, F.; Anzalone, A.; Di Pietro, A.; Figuera, P.; Han, J.; Maiolino, C.; Santonocito, D.; Berceanu, I.; Pop, A.; Cardella, G.; De Filippo, E.; Pagano, A.; Papa, M.

    2010-07-15

    Isotopic effects are studied in reactions induced by {sup 40}Ca projectiles at 25 MeV/nucleon on {sup 40}Ca, {sup 48}Ca , and {sup 46}Ti targets. The N/Z contents of projectilelike and midvelocity (MV) sources are probed by means of isotopic ({sup 7}Li/{sup 6}Li and {sup 9}Be/{sup 7}Be) and isobaric ({sup 7}Li/{sup 7}Be) yield ratios, for semiperipheral events. In particular, information about isospin transport phenomena will be discussed. Isospin diffusion processes involving nuclei, which have noticeable differences in N/Z have been investigated. Signals of isospin drift, which are related to the gradient of density in the participant region, have also been observed for fragments emitted at MV.

  18. Analytic continuation of the effective-range expansion as a method for determining the features of bound states: Application to the 6Li nucleus

    NASA Astrophysics Data System (ADS)

    Blokhintsev, L. D.; Savin, D. A.

    2014-03-01

    The scattering function (effective-range function) for the two-channel elastic scattering of charged particles is used to analyze dα scattering at low energies. In order to construct this function, use is made of various sets of phase shifts and mixing parameter, both those that were obtained by solving Faddeev equations in the three-body ( n, p, α) model and those that were deduced from available phaseshift analyses. By means of an analytic continuation of the scattering function to the point of the pole corresponding to the bound state of the 6Li nucleus, the values of the vertex constants and asymptotic normalization coefficients are found for the process 6Li → α + d. Possible means for refining these results are discussed.

  19. High-power electron beam tests of a liquid-lithium target and characterization study of (7)Li(p,n) near-threshold neutrons for accelerator-based boron neutron capture therapy.

    PubMed

    Halfon, S; Paul, M; Arenshtam, A; Berkovits, D; Cohen, D; Eliyahu, I; Kijel, D; Mardor, I; Silverman, I

    2014-06-01

    A compact Liquid-Lithium Target (LiLiT) was built and tested with a high-power electron gun at Soreq Nuclear Research Center (SNRC). The target is intended to demonstrate liquid-lithium target capabilities to constitute an accelerator-based intense neutron source for Boron Neutron Capture Therapy (BNCT) in hospitals. The lithium target will produce neutrons through the (7)Li(p,n)(7)Be reaction and it will overcome the major problem of removing the thermal power >5kW generated by high-intensity proton beams, necessary for sufficient therapeutic neutron flux. In preliminary experiments liquid lithium was flown through the target loop and generated a stable jet on the concave supporting wall. Electron beam irradiation demonstrated that the liquid-lithium target can dissipate electron power densities of more than 4kW/cm(2) and volumetric power density around 2MW/cm(3) at a lithium flow of ~4m/s, while maintaining stable temperature and vacuum conditions. These power densities correspond to a narrow (σ=~2mm) 1.91MeV, 3mA proton beam. A high-intensity proton beam irradiation (1.91-2.5MeV, 2mA) is being commissioned at the SARAF (Soreq Applied Research Accelerator Facility) superconducting linear accelerator. In order to determine the conditions of LiLiT proton irradiation for BNCT and to tailor the neutron energy spectrum, a characterization of near threshold (~1.91MeV) (7)Li(p,n) neutrons is in progress based on Monte-Carlo (MCNP and Geant4) simulation and on low-intensity experiments with solid LiF targets. In-phantom dosimetry measurements are performed using special designed dosimeters based on CR-39 track detectors. PMID:24387907

  20. Non-Destructive Monitoring of Charge-Discharge Cycles on Lithium Ion Batteries using 7Li Stray-Field Imaging

    PubMed Central

    Tang, Joel A.; Dugar, Sneha; Zhong, Guiming; Dalal, Naresh S.; Zheng, Jim P.; Yang, Yong; Fu, Riqiang

    2013-01-01

    Magnetic resonance imaging provides a noninvasive method for in situ monitoring of electrochemical processes involved in charge/discharge cycling of batteries. Determining how the electrochemical processes become irreversible, ultimately resulting in degraded battery performance, will aid in developing new battery materials and designing better batteries. Here we introduce the use of an alternative in situ diagnostic tool to monitor the electrochemical processes. Utilizing a very large field-gradient in the fringe field of a magnet, stray-field-imaging (STRAFI) technique significantly improves the image resolution. These STRAFI images enable the real time monitoring of the electrodes at a micron level. It is demonstrated by two prototype half-cells, graphite∥Li and LiFePO4∥Li, that the high-resolution 7Li STRAFI profiles allow one to visualize in situ Li-ions transfer between the electrodes during charge/discharge cyclings as well as the formation and changes of irreversible microstructures of the Li components, and particularly reveal a non-uniform Li-ion distribution in the graphite. PMID:24005580

  1. 7Li NMR spectroscopy and ion conduction mechanism in mesoporous silica (SBA-15) composite poly(ethylene oxide) electrolyte

    NASA Astrophysics Data System (ADS)

    Reddy, M. Jaipal; Chu, Peter P.

    A composite of mesoporous silica (SBA-15) with a polyethylene oxide (PEO) polymer electrolyte is examined for use in various electrochemical devices. Incorporation of SBA-15 in a PEO:LiClO 4 polymer electrolyte facilitates salt dissociation, enhances ion conductivity, and improves miscibility between organic and inorganic moieties. Optimized conductivity is found at 10 wt.% SBA-15 composition, above this concentration the conductivity is reduced due to aggregation of a SBA-15:Li rich phase. Heating above melt temperature of PEO allows more of the polymer segments to interact with SBA-15. This results in a greater degree of disorder upon cooling, and the ion conductivity is enhanced. A 7Li MAS NMR study reveals three types of lithium-ion coordination. Two major types of conduction mechanism can be identified: one through conventional amorphous PEO; a second via hopping in a sequential manner by replacing the nearby vacancies ('holes') on the surface (both interior and exterior) of the SBA-15 channels.

  2. Lanthanide complexes of aminophosphonates as shift reagents for 7Li and 23Na NMR studies in biological systems.

    PubMed

    Ramasamy, R; Castro, M M; de Freitas, D M; Geraldes, C F

    1992-01-01

    A systematic NMR characterization of various Dy(III) complexes of linear and macrocyclic aminophosphonates as 7Li and 23Na NMR shift reagents for biological systems was undertaken. Their efficacy as shift reagents (SR) was tested under constant aqueous solution ionic strength conditions at pH 7.5 as a function of rho = [SR]/[M+]. Further characterization of the two best SRs, Dy(PcPcP)2(7-) and Dy(DOTP)5-, led to the conclusion that, although quite sensitive to solution pH and the presence of alkali metal ions and Mg2+ and Ca2+, these complexes were stable towards hydrolysis by phosphatases. The lack of precipitation of its solutions in the presence of Ca2+, allowed the choice of Dy(DOTP)5- as the best overall SR for biological studies. Other SRs, like Dy(TTHA)3-, although less sensitive to pH and to divalent ions, require significantly higher concentrations to yield the same shifts, leading to large bulk susceptibility artifacts in perfused tissues and organs. PMID:1467337

  3. Cross-section measurement for the 10B(n, alpha)7Li reaction at 4.0 and 5.0 MeV.

    PubMed

    Zhang, Guohui; Guo, Li'an; Cao, Rongtai; Zhang, Jiaguo; Chen, Jinxiang

    2008-10-01

    Cross-sections of the (10)B(n, alpha)(7)Li reaction were measured at En=4.0 and 5.0 MeV. A gridded ionization chamber (GIC) was used as charged particle detector. Neutrons were produced through the D(d, n)(3)He reaction with a deuterium gas target. Experiments were performed at the 4.5 MV Van de Graaff accelerator of Peking University. Cross-section data of the (238)U(n, f) reaction were employed as standard. The measured cross-sections of the (10)B(n, alpha)(7)Li reaction at 4.0 and 5.0 MeV are 211+/-17 and 169+/-14 mb, respectively, and they are compared with existing results of measurements and evaluations. PMID:18387305

  4. 3He (α , γ)7Be and 3H (α , γ)7Li astrophysical S factors from the no-core shell model with continuum

    NASA Astrophysics Data System (ADS)

    Dohet-Eraly, Jérémy; Navrátil, Petr; Quaglioni, Sofia; Horiuchi, Wataru; Hupin, Guillaume; Raimondi, Francesco

    2016-06-01

    The 3He(α , γ)7Be and 3H(α , γ)7Li astrophysical S factors are calculated within the no-core shell model with continuum using a renormalized chiral nucleon-nucleon interaction. The 3He(α , γ)7Be astrophysical S factors agree reasonably well with the experimental data while the 3H(α , γ)7Li ones are overestimated. The seven-nucleon bound and resonance states and the α + 3He/3H elastic scattering are also studied and compared with experiment. The low-lying resonance properties are rather well reproduced by our approach. At low energies, the s-wave phase shift, which is non-resonant, is overestimated.

  5. Simulation of the neutron spectrum from the 7Li(p,n) reaction with a liquid-lithium target at Soreq Applied Research Accelerator Facility

    NASA Astrophysics Data System (ADS)

    Friedman, M.; Cohen, D.; Paul, M.; Berkovits, D.; Eisen, Y.; Feinberg, G.; Giorginis, G.; Halfon, S.; Krása, A.; Plompen, A. J. M.; Shor, A.

    2013-01-01

    The 7Li(p,n)7Be reaction has been used for the last 25 years to produce quasi-Maxwellian neutrons in order to measure Maxwellian-Averaged Cross-Sections in the relevant temperatures for stellar nucleosynthesis. A liquid-lithium target at the Soreq Applied Research Accelerator Facility is expected to allow us to perform such measurements at higher neutron intensities. Here we describe a Monte Carlo tool, SimLiT, developed to evaluate neutron spectra, intensities and angular distributions resulting from this reaction. We also demonstrate the feasibility to couple SimLiT with an advanced transport code, resulting in a powerful tool for planning and analysis of experiments using the 7Li(p,n) reaction as a neutron source.

  6. Neutron beam optimization based on a 7Li(p,n)7Be reaction for treatment of deep-seated brain tumors by BNCT

    NASA Astrophysics Data System (ADS)

    Zahra Ahmadi, Ganjeh; S. Farhad, Masoudi

    2014-10-01

    Neutron beam optimization for accelerator-based Boron Neutron Capture Therapy (BNCT) is investigated using a 7Li(p,n)7Be reaction. Design and optimization have been carried out for the target, cooling system, moderator, filter, reflector, and collimator to achieve a high flux of epithermal neutron and satisfy the IAEA criteria. Also, the performance of the designed beam in tissue is assessed by using a simulated Snyder head phantom. The results show that the optimization of the collimator and reflector is critical to finding the best neutron beam based on the 7Li(p,n)7Be reaction. Our designed beam has 2.49×109n/cm2s epithermal neutron flux and is suitable for BNCT of deep-seated brain tumors.

  7. A new measurement of the 7Li(d,p)8Li cross section and consequences for 7Be(p,γ)8B

    NASA Astrophysics Data System (ADS)

    Weissman, L.; Broude, C.; Goldring, G.; Hadar, R.; Hass, M.; Schwamm, F.; Shaanan, M.

    1998-02-01

    A novel scheme for measuring the cross section of the 7Be(p,γ)8B reaction, the major source of high energy neutrinos from the sun, is presented. The scheme involves a strictly uniform particle beam and overcomes some of the recognized experimental uncertainties of previous measurements. A new measurement of σ[7Li(d,p)8Li] has been carried out using this setup, and the present value of σ[7Li(d,p)8Li] = 155(8) mb at the top of the Ed(lab.) = 776 keV resonance is compared with previous measurements. A new issue regarding both the (d,p) and (p,γ) reactions has been examined: reaction-product nuclei which are backscattered out of the target. Measurements and simulations carried out in the course of this investigation are presented and discussed in the context of possible effects on the measured cross sections of these reactions.

  8. Stopping powers of MeV-energy ions 7LI, 12C, 16O and 28Si in some common target materials

    NASA Astrophysics Data System (ADS)

    Lin, E. K.; Sun, H. L.; Yu, Y. C.; Wang, C. W.; Liu, T. Y.; Chiou, J. W.; Lee, C. S.

    1997-02-01

    Stopping powers for 0.4-8.5 MeV 7Li-ions, 0.4-10 MeV 12C-ions, 0.3-14 MeV 16O-ions and 0.5-11.5 MeV 28Si ions in four commonly used materials (Al, Cu, Ag and Au) have been determined by using the backscattering method. Elastic backscattering spectra were measured at a laboratory detection angle 170° using a passivated implanted planar Si (PIPS) detector. Energy dependence of stopping powers were obtained and compared to the semiempirical model (TRIM-91 and SRIM-96) predictions. The SRIM-96 calculations generally reproduce the experimental data more closely and lead to a significant improvement of the agreement of the 7Li data when compared to TRIM-91.

  9. Characteristics of BDE dependent on 10B concentration for accelerator-based BNCT using near-threshold 7Li(p,n)7Be direct neutrons.

    PubMed

    Tanaka, K; Kobayashi, T; Bengua, G; Nakagawa, Y; Endo, S; Hoshi, M

    2004-11-01

    The characteristics boron-dose enhancer (BDE) was evaluated as to the dependence on the (10)B concentration for BNCT using near-threshold (7)Li(p,n)(7)Be direct neutrons. The treatable protocol depth (TPD) was utilized as an evaluation index. MCNP-4B calculations were performed for near-threshold (7)Li(p,n)(7)Be at a proton energy of 1.900MeV and for a polyethylene BDE. Consequently, the TPD was increased by increasing T/N ratio, i.e., the ratio of the (10)B concentration in the tumor ((10)B(Tumor)) to that in the normal tissue ((10)B(Normal)), and by increasing (10)B(Tumor) and (10)B(Normal) for constant T/N ratio. It has been found that the BDE becomes unnecessary from the viewpoint of increasing the TPD, when (10)B(Tumor) is over a certain level. PMID:15308161

  10. Fast Li ion dynamics in the solid electrolyte Li7 P3 S11 as probed by (6,7) Li NMR spin-lattice relaxation.

    PubMed

    Wohlmuth, Dominik; Epp, Viktor; Wilkening, Martin

    2015-08-24

    The development of safe and long-lasting all-solid-state batteries with high energy density requires a thorough characterization of ion dynamics in solid electrolytes. Commonly, conductivity spectroscopy is used to study ion transport; much less frequently, however, atomic-scale methods such as nuclear magnetic resonance (NMR) are employed. Here, we studied long-range as well as short-range Li ion dynamics in the glass-ceramic Li7 P3 S11 . Li(+) diffusivity was probed by using a combination of different NMR techniques; the results are compared with those obtained from electrical conductivity measurements. Our NMR relaxometry data clearly reveal a very high Li(+) diffusivity, which is reflected in a so-called diffusion-induced (6) Li NMR spin-lattice relaxation peak showing up at temperatures as low as 313 K. At this temperature, the mean residence time between two successful Li jumps is in the order of 3×10(8) s(-1) , which corresponds to a Li(+) ion conductivity in the order of 10(-4) to 10(-3) S cm(-1) . Such a value is in perfect agreement with expectations for the crystalline but metastable glass ceramic Li7 P3 S11 . In contrast to conductivity measurements, NMR analysis reveals a range of activation energies with values ranging from 0.17 to 0.26 eV, characterizing Li diffusivity in the bulk. In our case, through-going Li ion transport, when probed by using macroscopic conductivity spectroscopy, however, seems to be influenced by blocking grain boundaries including, for example, amorphous regions surrounding the Li7 P3 S11 crystallites. As a result of this, long-range ion transport as seen by impedance spectroscopy is governed by an activation energy of approximately 0.38 eV. The findings emphasize how surface and grain boundary effects can drastically affect long-range ionic conduction. If we are to succeed in solid-state battery technology, such effects have to be brought under control by, for example, sophisticated densification or through the preparation

  11. Nuclear fusion of deuterons with light nuclei driven by Coulomb explosion of nanodroplets

    SciTech Connect

    Ron, Shlomo; Last, Isidore; Jortner, Joshua

    2012-11-15

    Theoretical-computational studies of table-top laser-driven nuclear fusion of high energy (up to 15 MeV) deuterons with {sup 7}Li, {sup 6}Li, T, and D demonstrate the attainment of high fusion yields. The reaction design constitutes a source of Coulomb exploding deuterium nanodroplets driven by an ultraintense, near-infrared, femtosecond Gaussian laser pulse (peak intensity 2 Multiplication-Sign 10{sup 18}-5 Multiplication-Sign 10{sup 19} W cm{sup -2}) and a solid, hollow cylindrical target containing the second reagent. The exploding nanodroplets source is characterized by the deuteron kinetic energies, their number, and the laser energy absorbed by a nanodroplet. These were computed by scaled electron and ion dynamics simulations, which account for intra-nanodroplet laser intensity attenuation and relativistic effects. The fusion yields Y are determined by the number of the source deuterons and by the reaction probability. When laser intensity attenuation is weak within a single nanodroplet and throughout the nanodroplets assembly, Y exhibits a power law increase with increasing the nanodroplet size. Y is maximized for the nanodroplet size and laser intensity corresponding to the 'transition' between the weak and the strong intensity attenuation domains. The dependence of Y on the laser pulse energy W scales as W{sup 2} for weak assembly intensity attenuation, and as W for strong assembly intensity attenuation. This reaction design attains the highest table-top fusion efficiencies (up to 4 Multiplication-Sign 10{sup 9} J{sup -1} per laser pulse) obtained up to date.

  12. /sup 7/Be(n,p)/sup 7/Li total cross section from 25 meV to 13. 5 keV

    SciTech Connect

    Koehler, P.E.; Bowman, C.D.; Steinkruger, F.J.; Moody, D.C.; Hale, G.M.; Starner, J.W.; Wender, S.A.; Haight, R.C.; Lisowski, P.W.; Talbert, W.L.

    1988-03-01

    The total /sup 7/Be(n,p)/sup 7/Li cross section has been measured from 25 meV to 13.5 keV. These energies correspond to temperatures of T = 2.9 x 10/sup -7/ to 0.16 GK. For thermal neutrons the cross sections to the ground state (p/sub 0/) and the first excited state (p/sub 1/) of /sup 7/BLi are 38 400 +- 800 b and 420 +- 120 b, respectively. This result for the total /sup 7/Be(n,p)/sup 7/Li thermal cross section is about 25% lower, and is approximately a factor of 10 more precise than previous published measurements. For energies above 100 eV, a significant departure from a 1v shape for the total cross section is observed. The data were analyzed using a single-level approximation, and were also analyzed together with other data using multilevel-multichannel R-matrix theory. Results are presented for the properties of the 2/sup -/ threshold state and for a possible nearby 2/sup -/ state. The astrophysical reaction rate, N/sub A/<..sigma..v>, was calculated from the measured cross sections for the combined p/sub 0/ and p/sub 1/ transitions. The resulting reaction rate is approximately 60--80 % of the rate currently in use. This reduction in the /sup 7/Be(n,p)/sup 7/Li reaction rate could result in a calculated increase in the production of /sup 7/Li during the big bang by as much as 20%

  13. Au, Bi, Co and Nb cross-section measured by quasimonoenergetic neutrons from p + 7Li reaction in the energy range of 18-36 MeV

    NASA Astrophysics Data System (ADS)

    Majerle, M.; Bém, P.; Novák, J.; Šimečková, E.; Štefánik, M.

    2016-09-01

    Au, Bi, Co and Nb samples were irradiated several times with quasi-monoenergetic neutrons from p + 7Li reaction in the energy range of 18-36 MeV. The activities of the samples were measured with the HPGe detector and the reaction rates were calculated. The cross-sections were extracted using the SAND-II method with the reference cross-sections from the EAF-2010 database. The uncertainties of the final results are discussed.

  14. Exchange Effects in the Radiative Capture Reactions 3H(α, γ)7Li and 3He(α, γ)7Be

    NASA Astrophysics Data System (ADS)

    Solovyev, A. S.; Igashov, S. Yu.; Tchuvil'sky, Yu. M.

    2016-05-01

    The mirror 3H(α, γ)7Li and 3He(α, γ)7Be reactions have been considered using the algebraic versions of the resonating group model and of the orthogonality conditions model. Exchange effects in interaction of the colliding nuclei and influence of the corresponding exchange terms in matrix elements of the interaction potential on calculated astrophysical S-factors for the reactions have been studied.

  15. Synthesis and optical characterization of LiKB4O7, Li2B6O10, and LiCsB6O10 glasses

    SciTech Connect

    Adamiv, V.; Teslyuk, I.; Dyachok, Ya.; Romanyuk, G.; Krupych, O.; Mys, O.; Martynyuk-Lototska, I.; Burak, Ya.; Vlokh, R.

    2010-10-01

    In the current work we report on the synthesis of LiKB4O7, Li2B6O10, and LiCsB6O10 borate glasses. The results for their piezo-optic, acousto-optic, acoustic, elastic, refractive, optical transmission, and optical resistance properties are also presented. It is shown that some of these glasses represent efficient acousto-optic materials that are transparent down to the vacuum ultraviolet range and highly resistant to laser radiation.

  16. /sup 12/C(/sup 6/Li,d)/sup 16/O. -->. cap alpha. +/sup 12/C reaction mechanism by means of angular correlation measurements

    SciTech Connect

    Cunsolo, A.; Foti, A.; Imme, G.; Pappalardo, G.; Raciti, G.; Saunier, N.

    1980-06-01

    The particle-particle angular correlation method is applied to the reaction /sup 12/C(/sup 6/Li,d)/sup 16/O ..-->.. ..cap alpha..+/sup 12/C. Deuterons were detected at theta/sup lab//sub d/=10/sup 0/. Information on the reaction mechanism is obtained by analyzing the shape and the angular shift of the experimental data. A dominant direct transfer mechanism is found for the primary reaction. The ratios GAMMA..cap alpha../sub 0//GAMMA and the ..cap alpha..-reduced widths ..gamma cap alpha../sub 0/ are deduced.

  17. Digital signal processing for a thermal neutron detector using ZnS(Ag):6LiF scintillating layers read out with WLS fibers and SiPMs

    NASA Astrophysics Data System (ADS)

    Mosset, J.-B.; Stoykov, A.; Greuter, U.; Hildebrandt, M.; Schlumpf, N.

    2016-07-01

    We present a digital signal processing system based on a photon counting approach which we developed for a thermal neutron detector consisting of ZnS(Ag):6LiF scintillating layers read out with WLS fibers and SiPMs. Three digital filters have been evaluated: a moving sum, a moving sum after differentiation and a digital CR-RC4 filter. The performances of the detector with these filters are presented. A full analog signal processing using a CR-RC4 filter has been emulated digitally. The detector performance obtained with this analog approach is compared with the one obtained with the best performing digital approach.

  18. Partial diagenetic overprint of Late Jurassic belemnites from New Zealand: Implications for the preservation potential of δ7Li values in calcite fossils

    NASA Astrophysics Data System (ADS)

    Ullmann, Clemens V.; Campbell, Hamish J.; Frei, Robert; Hesselbo, Stephen P.; Pogge von Strandmann, Philip A. E.; Korte, Christoph

    2013-11-01

    The preservation potential and trends of alteration of many isotopic systems (e.g. Li, Mg, Ca) that are measured in fossil carbonates are little explored, yet extensive paleoenvironmental interpretations have been made on the basis of these records. Here we present a geochemical dataset for a Late Jurassic (˜153 Ma) belemnite (Belemnopsis sp.) from New Zealand that has been partially overprinted by alteration. We report the physical pathways and settings of alteration, the resulting elemental and isotopic trends including δ7Li values and Li/Ca ratios, and assess whether remnants of the primary shell composition have been preserved or can be extrapolated from the measured values. The δ18O and δ13C values as well as Sr/Ca and Mn/Ca ratios were analysed along two profiles. In addition, 6 samples were analysed for 87Sr/86Sr, Sr/Ca and Mn/Ca ratios. Five samples from the same specimen and 2 from the surrounding sediment were analysed for δ7Li values, Li/Ca, Sr/Ca and Mn/Ca ratios and are compared to results for 6 other Late Jurassic belemnite rostra (Belemnopsis sp. andHibolithes sp.) from the same region. The 87Sr/86Sr ratios are lower (less radiogenic) in the most altered part of the rostrum, whereas δ7Li values become more positive with progressive alteration. The direction and magnitude of the trends in the geochemical record indicate that one main phase of alteration that occurred in the Late Cretaceous caused most of the diagenetic signature in the calcite. Despite relatively deep burial, down to 4 km, and thus elevated temperatures, this diagenetic signature has subsequently been preserved even for the highly mobile element lithium, suggesting that primary lithium-isotope values can be maintained over geological timescales, at least in thick macrofossil shells. Our best δ7Li estimate for pristine Late Jurassic (˜155-148 Ma) belemnites is +27 ± 1‰, which points to a Late Jurassic seawater δ7Li of ˜29-32‰, compatible with the modern value of 31‰.

  19. Evaluation of {sup 235}U, {sup 238}U, {sup 6}Li, and {sup 27}Al Cross Sections

    SciTech Connect

    Chandler, J.R.

    2001-05-17

    Good nuclear data are essential for accurate prediction of reactor parameters. Several cross section libraries are currently available for use with GLASS physics calculations. In recent Mark 15 and Mark 22 studies, cross section data were developed to provide more accurate buckling calculations for Mark 15 and Mark 22 charges. This report documents evaluation of these new data for universal application.

  20. Theoretical analysis of the astrophysical S-factor for the capture reaction α + d → {sup 6}Li + γ in the two-body model

    SciTech Connect

    Tursunov, E. M. Turakulov, S. A.; Descouvemont, P.

    2015-03-15

    Theoretical estimates for the astrophysical S-factor and the rate of the reaction d(α, γ){sup 6}Li were obtained on the basis of the two-body model involving an α−d potential that has a simple Gaussian form and which describes correctly S-, P-, and D-wave phase shifts, the binding energy, and the asymptotic normalization coefficient for the S-wave bound state. The wave functions for the bound and continuum channels were calculated with the aid of the highly precise Numerov algorithm. The results for the contributions of the E1 and E2 transition components reveal a good convergence as the upper limit in the effective integrals increases up to 40 fm. The results obtained for the astrophysical S-factor and the rate of the reaction d(α, γ){sup 6}Li in the temperature range of 10{sup 6}K ≤ T ≤ 10{sup 10} K agree well with the results of the calculations performed by A.M. Mukhamedzhanov and his coauthors [Phys. Rev. C 83, 055805 (2011)] by using the known asymptotic form of the wave function at low energies and a complicated two-body potential at higher energies.

  1. Natural abundance 17O, 6Li NMR and molecular modeling studies of the solvation structures of lithium bis(fluorosulfonyl)imide/1,2-dimethoxyethane liquid electrolytes

    NASA Astrophysics Data System (ADS)

    Wan, Chuan; Hu, Mary Y.; Borodin, Oleg; Qian, Jiangfeng; Qin, Zhaohai; Zhang, Ji-Guang; Hu, Jian Zhi

    2016-03-01

    Natural abundance 17O and 6Li NMR experiments, quantum chemistry and molecular dynamics studies were employed to investigate the solvation structures of Li+ at various concentrations of LiFSI in DME electrolytes. It was found that the chemical shifts of both 17O and 6Li changed with the concentration of LiFSI, indicating the changes of solvation structures with concentration. For the quantum chemistry calculations, the coordinated cluster LiFSI(DME)2 forms at first, and its relative ratio increases with increasing LiFSI concentration to 1 M. Then the solvation structure LiFSI(DME) become the dominant component. As a result, the coordination of forming contact ion pairs between Li+ and FSI- ion increases, but the association between Li+ and DME molecule decreases. Furthermore, at LiFSI concentration of 4 M the solvation structures associated with Li+(FSI-)2(DME), Li+2(FSI-)(DME)4 and (LiFSI)2(DME)3 become the dominant components. For the molecular dynamics simulation, with increasing concentration, the association between DME and Li+ decreases, and the coordinated number of FSI- increases, which is in perfect accord with the DFT results.

  2. Simultaneous sub-Doppler laser cooling of fermionic 6Li and 40K on the D1 line: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Sievers, Franz; Kretzschmar, Norman; Fernandes, Diogo Rio; Suchet, Daniel; Rabinovic, Michael; Wu, Saijun; Parker, Colin V.; Khaykovich, Lev; Salomon, Christophe; Chevy, Frédéric

    2015-02-01

    We report on simultaneous sub-Doppler laser cooling of fermionic 6Li and 40K using the D1 optical transitions. We compare experimental results to a numerical simulation of the cooling process applying a semiclassical Monte Carlo wave-function method. The simulation takes into account the three-dimensional optical molasses setup and the dipole interaction between atoms and the bichromatic light field driving the D1 transitions. We discuss the physical mechanisms at play, identify the important role of coherences between the ground-state hyperfine levels, and compare D1 and D2 sub-Doppler cooling. In 5 ms, the D1 molasses phase greatly reduces the temperature for both 6Li and 40K at the same time, with final temperatures of 44 and 11 μ K , respectively. For both species this leads to a phase-space density close to 10-4. These conditions are well suited to direct loading of an optical or magnetic trap for efficient evaporative cooling to quantum degeneracy.

  3. Effect of breakup and transfer on complete and incomplete fusion in 6Li+209Bi reaction in multi-body classical molecular dynamics calculation

    NASA Astrophysics Data System (ADS)

    Morker, Mitul R.; Godre, Subodh S.

    2016-05-01

    The effect of breakup and transfer in 6Li+209Bi reaction is studied in a multi-body classical molecular dynamics approach in which the weakly-bound projectile 6Li is constructed as a 2-body cluster of 4He and 2H in a configuration corresponding to the observed breakup energy. This 3-body system with their individual nucleon configuration in their ground state is dynamically evolved with given initial conditions using Classical Rigid Body Dynamics (CRBD) approach up to distances close to the barrier when the rigid-body constraint on the target, inter-fragment distance, and 2H itself are relaxed, allowing for possible breakup of 2H which may result in incomplete fusion following the transfer of the n or p. Relative probabilities of the possible events such as scattering with and without breakup, DCF, SCF, ICF(x) where x may be 4He, 2H, 4He+n, 4He+p, n, p are calculated. Comparison of the calculated event-probabilities, complete, and incomplete fusion cross sections with the calculation in which 2H is kept rigid demonstrates the effect of the transfer reactions on complete and incomplete fusion in the 4-body reaction. Events ICF(4He+n) corresponding to nstripping followed by breakup of the resultant 5Li to 4He+p are found to contribute significantly in the fusion process in agreement with a recent experimental observation of direct reaction processes in breakup of weakly-bound projectiles.

  4. Equilibrium and pre-equilibrium processes in the {sup 55}Mn({sup 6}Li,xp) and {sup 57}Fe({alpha},xp) reactions

    SciTech Connect

    Voinov, A. V.; Grimes, S. M.; Brune, C. R.; Massey, T. N.; Buerger, A.; Goergen, A.; Guttormsen, M.; Larsen, A. C.; Siem, S.; Kalbach, C.

    2011-05-15

    Spectra of outgoing neutrons and protons from the {sup 6}Li + {sup 55}Mn reaction and protons from the {alpha} + {sup 57}Fe reaction have been measured with beams of 15-MeV {sup 6}Li ions and 30-MeV {alpha} particles. These reactions proceed through the same {sup 61}Ni nucleus at the same excitation energy, thus allowing the difference in reaction mechanisms to be studied. It is shown that spectra from the first reaction measured at backward angles are due to emission from a traditional compound nucleus reaction, in which the intermediate nucleus has reached statistical equilibrium; the spectra from the second reaction contain a significant fraction of pre-equilibrium emission at all angles. Level density parameters of the residual nucleus {sup 60}Co have been obtained from the first reaction. Both emission spectra and angular distributions have been measured for the second reaction. It was found that the pre-equilibrium component exhibits a forward-peaked angular distribution, as expected, but with a steeper slope than predicted and with an unusual slight rise at angles above 120 deg. The backward-angle rise is explained qualitatively by the dominance of the multistep compound mechanism at backward angles.

  5. Coupled channels description of single and mutual excitation in the scattering of 7Li from 12C and 24, 26Mg

    NASA Astrophysics Data System (ADS)

    Cook, J.; Clarice, N. M.; Coopersmith, J.; Griffiths, R. J.

    1982-09-01

    Coupled channels calculations have been made for the scattering of 7Li from 12C at 63 and 79 MeV and from 24,26Mg at 88 MeV. The calculations describe, simultaneously, the elastic scattering, excitation of 7Li to the 478 keV {1}/{2}- state, excitation of the target to its first 2 + state, and the mutual excitation of both projectile and target to their {1}/{2}- and 2 + states respectively. The potentials have been calculated by a double folding model using the M3Y effective interaction for the real part, and a gaussian effective interaction for the imaginary part. Realistic densities have been used for the ground states of 7Li, 12C and 24, 26Mg and also the transition densities to the excited states using a microscopic plus macroscopic prescription. For the mutual excitation, both one-step processes with l = 0, 2 and 4 and two-step processes were included. The calculations show that the two-step processes are the dominant contribution to the mutual excitation, but at forward angles, the oscillations in the data are only reproduced with the coherent addition of the one-step processes, which are dominated by the l = 4 contribution. Even when coupling to all single and mutual excitations are included the real potential still requires a normalization of about 0.6. The addition of the quadrupole re-orientation matrix element for the ground state does not significantly change this value. These calculations confirm that the coupling to the first excited inelastic levels of target and ejectile is not the source of the anomalous M3Y normalization, and that the dominant mode for mutual excitation is a two-step process. However, direct one-step mutual excitation is important for small angles (θ ≲ 20°).

  6. Synthesis and optical characterization of LiKB4O7, Li2B6O10, and LiCsB6O10 glasses.

    PubMed

    Adamiv, V; Teslyuk, I; Dyachok, Ya; Romanyuk, G; Krupych, O; Mys, O; Martynyuk-Lototska, I; Burak, Ya; Vlokh, R

    2010-10-01

    In the current work we report on the synthesis of LiKB(4)O(7), Li(2)B(6)O(10), and LiCsB(6)O(10) borate glasses. The results for their piezo-optic, acousto-optic, acoustic, elastic, refractive, optical transmission, and optical resistance properties are also presented. It is shown that some of these glasses represent efficient acousto-optic materials that are transparent down to the vacuum ultraviolet range and highly resistant to laser radiation. PMID:20885472

  7. Fusion and direct reactions around the barrier for the systems {sup 7,9}Be,{sup 7}Li+{sup 238}U

    SciTech Connect

    Raabe, R.; Angulo, C.; Charvet, J. L.; Jouanne, C.; Nalpas, L.; Figuera, P.; Pierroutsakou, D.; Romoli, M.; Sida, J. L.

    2006-10-15

    We present new cross section data for the complete fusion of the weakly bound systems {sup 7,9}Be and {sup 7}Li on {sup 238}U at energies around the Coulomb barrier. In the same measurement, yields for direct processes and incomplete fusion are detected. For all systems, a suppression of the complete fusion cross section around and above the barrier is observed. At energies below the barrier, the fusion of the {sup 7}Be+{sup 238}U system shows no enhancement with respect to simple model predictions.

  8. Breakup coupling effects on near-barrier quasi-elastic scattering of {sup 6,7}Li on {sup 144}Sm

    SciTech Connect

    Otomar, D. R.; Lubian, J.; Gomes, P. R. S.; Monteiro, D. S.; Niello, J. O. Fernandez; Guimaraes, V.; Chamon, L. C.

    2009-09-15

    Excitation functions of quasi-elastic scattering at backward angles have been measured for the {sup 6,7}Li+{sup 144}Sm systems at near-barrier energies, and fusion barrier distributions have been extracted from the first derivatives of the experimental cross sections with respect to the bombarding energies. The data have been analyzed in the framework of continuum discretized coupled-channel calculations, and the results have been obtained in terms of the influence exerted by the inclusion of different reaction channels, with emphasis on the role played by the projectile breakup.

  9. Study of the {sup 19}O states via the ({sup 7}Li,{sup 7}Be) reaction at 52 MeV

    SciTech Connect

    Cavallaro, M.; Cappuzzello, F.; Cunsolo, A.; Carbone, D.; Foti, A.; Lenske, H.

    2010-04-30

    The {sup 19}F({sup 7}Li,{sup 7}Be){sup 19}O reaction at 52 MeV incident energy has been performed at INFN-LNS in Catania using the MAGNEX large acceptance spectrometer. The use of an algebraic ray-reconstruction technique has allowed to extract the {sup 19}O excitation energy spectrum and the experimental angular distributions. A theoretical analysis based on the Quasi-particle Random Phase Approximation has described the transitions to the 1p-1h states of the {sup 19}O, in close agreement with the experimental cross sections without using any scaling factor.

  10. Elimination of the Stark shift from the vibrational transition frequency of optically trapped {sup 174}Yb{sup 6}Li molecules

    SciTech Connect

    Kajita, Masatoshi; Gopakumar, Geetha; Abe, Minori; Hada, Masahiko

    2011-08-15

    Transition frequencies of cold molecules must be accurately evaluated to test the variance in the proton-to-electron mass ratio. Measuring the X {sup 2}{Sigma}(v,N)=(0,0){yields}(1,0) transition frequency of optically trapped {sup 174}Yb{sup 6}Li molecules is a promising method for achieving this goal. The Stark shifts induced by trap and probe (for the Raman transition) lasers are eliminated by choosing appropriate frequencies (magic frequencies) during the construction of the optical lattice. In the far-off resonance region, the Stark shift is found to be less than 10{sup -16} even when the laser frequencies are detuned from the magic frequencies by {approx}1 MHz.

  11. (sup 6)Li and (sup 7)MAS NMR and In Situ X-Ray Diffraction Studies of Lithium Manganate Cathode Materials

    SciTech Connect

    Lee, Young Joo; Wang, Francis; Grey, Clare P.; Mukerjee, Sanjeev; McBreen, James

    1998-11-30

    {sup 6}Li MAS NMR spectra of lithium manganese oxides with differing manganese oxidation states (LiMn{sub 2}O{sub 4}, Li{sub 4}Mn{sub 5}O{sub 12}, Li{sub 2}Mn{sub 4}O{sub 9}, and Li{sub 2}Mn{sub 2}O{sub 4}) are presented. Improved understanding of the lithium NMR spectra of these model compounds is used to interpret the local structure of the Li{sub x}Mn{sub 2}O{sub 4} cathode materials following electrochemical Li{sup +} deintercalation to various charging levels. In situ x-ray diffraction patterns of the same material during charging are also reported for comparison. Evidence for two-phase behavior for x <0.4 (Li{sub x}Mn{sub 2}O{sub 4}) is seen by both NMR and diffraction.

  12. Experimental study of the halo nucleus {sup 6}He using the {sup 6}Li({gamma},{pi}{sup +}){sup 6}He reaction

    SciTech Connect

    Harrington, N. P.; Branford, D.; Foehl, K.; Roche, E.; Annand, J. R. M.; Livingston, K.; McGreorge, J. C.; MacGregor, I. J. D.; Monstad, K.; Waddell, S.; Watts, D. P.; Beck, R.; Hornidge, D.; Reiter, A.; Grabmayr, P.; Hehl, T.; Martin, I.; Moschini, F.; Young, S.

    2007-04-15

    The reaction {sup 6}Li({gamma},{pi}{sup +}){sup 6}He was studied over the angular range {theta}{sub {pi}}=40-150 degree sign with the aim of investigating the halo structure of {sup 6}He. Photons from a bremsstrahlung beam were tagged in the energy range E{sub {gamma}}=170-220 MeV at a resolution of {delta}E{sub {gamma}}=630 keV, and positively charged pions detected using high resolution stacked HpGe detectors. The measured angular distributions for the resolved {sup 6}He ground and 1.80 MeV excited states are compared to previous measurements and theoretical calculations based on the impulse approximation. It is deduced that the ground state rms radius of the {sup 6}He nucleus may be larger than previously thought and that the first excited 1.80 MeV state may also be a halo state.

  13. Production of antimatter 5,6Li nuclei in central Au+Au collisions at √{sNN} = 200 GeV

    NASA Astrophysics Data System (ADS)

    Sun, Kai-Jia; Chen, Lie-Wen

    2015-12-01

    Combining the covariant coalescence model and a blast-wave-like analytical parametrization for (anti-)nucleon phase-space freezeout configuration, we explore light (anti-)nucleus production in central Au+Au collisions at √{sNN} = 200 GeV. Using the nucleon freezeout configuration (denoted by FO1) determined from the measured spectra of protons (p), deutrons (d) and 3He, we find the predicted yield of 4He is significantly smaller than the experimental data. We show this disagreement can be removed by using a nucleon freezeout configuration (denoted by FO2) in which the nucleons are assumed to freeze out earlier than those in FO1 to effectively consider the effect of large binding energy value of 4He. Assuming the binding energy effect also exists for the production of 5Li, Li5‾, 6Li and Li6‾ due to their similar binding energy values as 4He, we find the yields of these heavier (anti-)nuclei can be enhanced by a factor of about one order, implying that although the stable (anti-)6Li nucleus is unlikely to be observed, the unstable (anti-)5Li nucleus could be produced in observable abundance in Au+Au collisions at √{sNN} = 200 GeV where it may be identified through the p-4He (p ‾-He4‾) invariant mass spectrum. The future experimental measurement on (anti-)5Li would be very useful to understand the production mechanism of heavier antimatter.

  14. Isotope shift in the electron affinity of lithium

    SciTech Connect

    Bubin, Sergiy; Komasa, Jacek; Stanke, Monika; Adamowicz, Ludwik

    2009-12-21

    Very accurate electron affinity (EA) calculations of {sup 6}Li and {sup 7}Li (and {sup {infinity}L}i) have been performed using explicitly correlated Gaussian functions and a variational approach that explicitly includes the nuclear motion in the calculations (i.e., the approach that does not assume the Born-Oppenheimer approximation). The leading relativistic and quantum electrodynamics corrections to the electron affinities were also calculated. The results are the most accurate theoretical values obtained for the studied systems to date. Our best estimates of the {sup 7}Li and {sup 6}Li EAs are 4984.9842(30) and 4984.9015(30) cm{sup -1}, respectively, and of the {sup 7}Li/{sup 6}Li EA isotope shift is 0.0827 cm{sup -1}.

  15. Evaluation of the /sup 7/Li(n,n't)/sup 4/He cross section for ENDF/B-VI and application to uncertainty analysis

    SciTech Connect

    Young, P.G.; Davidson, J.W.; Muir, D.W.

    1988-01-01

    A new covariance analysis of n+/sup 7/Li cross section data has been completed for Version VI of ENDF/B. The analysis updates our 1981 work for ENDF/B-V.2 to include new data that has become available since that time and to incorporate cross correlations between different experiments. The bulk of the new measured data consists of some 10 new (or newly revised) tritium-production measurements involving about 70 new data points. The new analysis results in only small changes in the previous evaluation of the tritium-production cross section but significantly reduces the magnitudes of uncertainties due to the more extensive and accurate data base that was used. A two-dimensional sensitivity and uncertainty analysis of the Lithium Blanket Module experiments at the LOTUS facility was performed in order to assess the effects of the new /sup 7/Li cross sections on tritium breeding uncertainty in a realistic system. 4 refs., 6 figs., 3 tabs.

  16. Coupling of Li motion and structural distortions in olivine LiMnPO4 from 7Li and 31P NMR

    NASA Astrophysics Data System (ADS)

    Rudisch, Christian; Grafe, Hans-Joachim; Geck, Jochen; Partzsch, Sven; Zimmermann, M. v.; Wizent, Nadja; Klingeler, Rüdiger; Büchner, Bernd

    2013-08-01

    We present a detailed 7Li- and 31P-NMR study on single crystalline LiMnPO4 in the paramagnetic and antiferromagnetic phase (AFM, TN˜34 K). This allows us to determine the spin directions in the field-induced spin-flop phase. In addition, the anisotropic dipolar hyperfine coupling tensor of the 7Li and 31P nuclei is also fully determined by orientation and temperature-dependent NMR experiments and compared to the calculated values from crystal structure data. Deviations of the experimental values from the theoretical ones are discussed in terms of Mn disorder which is induced by Li disorder. In fact, the disorder in the Mn sublattice is directly revealed by diffuse x-ray scattering data. The present results provide experimental evidence for the Li diffusion strongly coupling to structural distortions within the MnPO4 host, which is expected to significantly affect the Li mobility as well as the performance of batteries based on this material.

  17. Measurement of 10B content in thin-film 10B samples.

    PubMed

    Zhang, Guohui; Liu, Jiaming; Xue, Zhihua; Wu, Hao; Liu, Yuxiao; Yuan, Xi; Liu, Xiang

    2011-06-01

    Two thin-film (10)B samples on tantalum backings were made for measurement of cross sections of the (10)B(n,α)(7)Li reaction in the MeV neutron energy region. The number of (10)B atoms in the samples was determined using the relative comparison method by detecting alpha and triton particles from thermal neutron induced nuclear reactions of (10)B(n(th),α)(7)Li and (6)Li(n(th),t)(4)He with a (6)LiF sample as the reference. A twin gridded ionization chamber was used as the detector of charged particles. PMID:21353786

  18. Nuclear chemistry progress report

    SciTech Connect

    Viola, V.E. Jr.

    1981-08-01

    The following were studied: charge and mass variances in /sup 56/Fe-induced reactions; /sup 40/Ca + /sup 37/Cl and /sup 209/Bi + /sup 37/Cl reactions at 270 MeV; production of exotic nuclei in /sup 56/Fe-induced reactions; the /sup 165/Ho + /sup 56/Fe reaction at 462 MeV; pre-equilibrium emission of light ions in the reaction /sup 16/O + /sup 238/U at 20 MeV/u; prompt light-ion emission in the /sup 235/U + /sup 4/He reaction at 20- and 40-MeV/u; studies of the total reaction cross section in bombardments at /sup 27/Al with 30 to 50 MeV/u /sup 4/He ions; reaction mechanisms of alpha-particle-induced reactions on /sup 12/C, /sup 14/N and /sup 16/O at 60 to 160 MeV; production of /sup 6/He, /sup 6/Li, /sup 7/Li, and /sup 7/Be in the ..cap alpha.. + ..cap alpha.. reaction between 60 to 160 MeV; search for asymmetric mass division in light fissioning systems; systematics of fission total kinetic energy release; and nucleosynthesis of the light elements Li, Be, and B.

  19. Evaluation of the characteristics of boron-dose enhancer (BDE) materials for BNCT using near threshold 7Li(p,n)7Be direct neutrons

    NASA Astrophysics Data System (ADS)

    Bengua, Gerard; Kobayashi, Tooru; Tanaka, Kenichi; Nakagawa, Yoshinobu

    2004-03-01

    The characteristics of a number of candidate boron-dose enhancer (BDE) materials for boron neutron capture therapy (BNCT) using near threshold 7Li(p,n)7Be direct neutrons were evaluated based on the treatable protocol depth (TPD), defined in this paper. Simulation calculations were carried out by means of MCNP-4B transport code for candidate BDE materials, namely, (C2H4)n, (C2H3F)n, (C2H2F2)n, (C2HF3)n, (C2D4)n, (C2F4)n, beryllium metal, graphite, D2O and 7LiF. Dose protocols applied were those used for intra-operative BNCT treatment for brain tumour currently used in Japan. The maximum TPD (TPDmax) for each BDE material was found to be between 4 cm and 5 cm in the order of (C2H4)n < (C2H3F)n < (C2H2F2)n < (C2HF3)n < beryllium metal < (C2D4)n < graphite < (C2F4)n < D2O < 7LiF. Based on the small and arbitrary variations in the TPDmax for these materials, an explicit advantage of a candidate BDE material could not be established from the TPDmax alone. The dependence of TPD on BDE thickness was found to be influenced by the type of BDE material. For materials with hydrogen, sharp variations in TPD were observed, while those without hydrogen exhibited more moderate fluctuations in TPD as the BDE thickness was varied. The BDE thickness corresponding to TPDmax (BDE(TPDmax)) was also found to depend on the type of BDE material used. Thicker BDE(TPDmax), obtained mostly for BDE materials without hydrogen, significantly reduced the dose rates within the phantom. The TPDmax, the dependence of TPD on BDE thickness and the BDE (TPDmax) were ascertained as appropriate optimization criteria in choosing suitable BDE materials for BNCT. Among the candidate BDE materials considered in this study, (C2H4)n was judged as the suitable material for near-surface tumours and beryllium metal for deeper tumours based on these optimization criteria and other practical considerations.

  20. Ultracold Collisions Involving Heteronuclear Alkali Metal Dimers

    SciTech Connect

    Cvitas, Marko T.; Soldan, Pavel; Hutson, Jeremy M.; Honvault, Pascal; Launay, Jean-Michel

    2005-05-27

    We carry out the first quantum dynamics calculations on ultracold atom-diatom collisions in isotopic mixtures. The systems studied are spin-polarized {sup 7}Li+{sup 6}Li{sup 7}Li, {sup 7}Li+{sup 6}Li{sub 2}, {sup 6}Li+{sup 6}Li{sup 7}Li, and {sup 6}Li+{sup 7}Li{sub 2}. Reactive scattering can occur for the first two systems even when the molecules are in their ground rovibrational states, but is slower than vibrational relaxation in homonuclear systems. Implications for sympathetic cooling of heteronuclear molecules are discussed.

  1. Structure and reactivity of lithium amides. /sup 6/Li, /sup 13/C, and /sup 15/N NMR spectroscopic studies and colligative measurements of lithium diphenylamide and lithium diphenylamide-lithium bromide complex solvated by tetrahydrofuran

    SciTech Connect

    DePue, J.S.; Collum, D.B.

    1988-08-03

    /sup 6/Li, /sup 13/C, and /sup 15/N NMR spectroscopic studies of lithium diphenylamide in THF/hydrocarbon solutions (THF = tetrahydrofuran) detected two different species. /sup 6/Li and /sup 15/N NMR spectroscopic studies of (/sup 6/Li, /sup 15/N)lithium diphenylamide showed the species observed at low THF concentrations to be a cyclic oligomer. Structural analogies provided strong support for a dimer while colligative measurements at 0/degrees/C indicated the dimer to be di- or trisolvated. On the basis of the observed mass action effects, the species appearing at intermediate THF concentrations is assigned as a contact or solvent-separated ion-paired monomer. Lithium diphenylamide forms a 1:1 adduct with lithium bromide at low THF concentrations. A combination of /sup 6/Li-/sup 15/N double labeling studies and colligative measurements supports a trisolvated cyclic mixed dimer structure. Although detailed spectroscopic studies at elevated THF concentrations were precluded by high fluctionality, the similarity of the /sup 13/C chemical shifts of lithium diphenylamide in the presence and absence of lithium bromide provide indirect evidence that the mixed dimer undergoes a THF concentration dependent dissociation to the monomeric amide and free lithium bromide. 24 references, 9 figures, 2 tables.

  2. Properties of Products Originating from the Interaction of 35-MeV/nucleon {sup 7}Li Ions with Pb Nuclei

    SciTech Connect

    Demekhina, N.A.; Karapetyan, G.S.; Lukyanov, S.M.; Penionzhkevich, Yu.E.; Skobelev, N.K.; Yakushev, A.B.

    2005-01-01

    The results are presented that were obtained by measuring and analyzing the yields and kinematical features of radioactive products of the reactions initiated in a lead target by lithium ions accelerated to an energy of 35 MeV per nucleon. The cross sections, charge and mass distributions, and kinematical and energy features of various reaction products associated with the fission and the evaporation channels of the decay of excited nuclei are determined. Quantities that are calculated in the present study include the momenta and kinetic energies of residual nuclei, as well as the momentum transfer and the excitation energy of intermediate nuclear systems formed upon complete and incomplete fusion. On the basis of an analysis of data obtained in our experiment, the total cross section for nuclear interaction and partial widths with respect to various channels of the decay of intermediate compound nuclei are determined in the energy range being investigated.

  3. Identification of Li-Ion Battery SEI Compounds through (7)Li and (13)C Solid-State MAS NMR Spectroscopy and MALDI-TOF Mass Spectrometry.

    PubMed

    Huff, Laura A; Tavassol, Hadi; Esbenshade, Jennifer L; Xing, Wenting; Chiang, Yet-Ming; Gewirth, Andrew A

    2016-01-13

    Solid-state (7)Li and (13)C MAS NMR spectra of cycled graphitic Li-ion anodes demonstrate SEI compound formation upon lithiation that is followed by changes in the SEI upon delithiation. Solid-state (13)C DPMAS NMR shows changes in peaks associated with organic solvent compounds (ethylene carbonate and dimethyl carbonate, EC/DMC) upon electrochemical cycling due to the formation of and subsequent changes in the SEI compounds. Solid-state (13)C NMR spin-lattice (T1) relaxation time measurements of lithiated Li-ion anodes and reference poly(ethylene oxide) (PEO) powders, along with MALDI-TOF mass spectrometry results, indicate that large-molecular-weight polymers are formed in the SEI layers of the discharged anodes. MALDI-TOF MS and NMR spectroscopy results additionally indicate that delithiated anodes exhibit a larger number of SEI products than is found in lithiated anodes. PMID:26653886

  4. Radiative neutron capture by {sup 2}H, {sup 7}Li, {sup 14}C, and {sup 14}N nuclei at astrophysical energies

    SciTech Connect

    Dubovichenko, S. B.

    2013-07-15

    The possibility of describing experimental data on the total cross sections for the n{sup 2}H, n{sup 7}Li, n{sup 14}C, and n{sup 14}N radiative-capture processes within the potential cluster model involving forbidden states and their classification according to Young's tableaux is considered. It is shown that this model and the methods used here to construct potentials make it possible to describe correctly the behavior of the experimental cross sections at energies between 5 to 10 meV (5 Multiplication-Sign 10{sup -3}-10 Multiplication-Sign 10{sup -3} eV) and 1 to 15MeV.

  5. Measurement of the 477.6-keV γ -ray production cross section following inelastic neutron scattering by 7Li

    NASA Astrophysics Data System (ADS)

    Nyman, M.; Belloni, F.; Ichinkhorloo, D.; Pirovano, E.; Plompen, A. J. M.; Rouki, C.

    2016-02-01

    The γ -ray production cross section for the 477.6-keV 1 /2-→3 /2g.s . - transition in 7Li following inelastic neutron scattering has been measured from the reaction threshold up to 18 MeV. This cross section is interesting as a possible standard for other γ -ray production cross-section measurements. The experiment was conducted at the GELINA pulsed white neutron source with the GAINS spectrometer consisting of 12 high-purity germanium detectors. The time-of-flight method was used for neutron energy determination. The sample was an optical-quality lithium fluoride disk and the neutron flux was monitored using a 235U fission chamber. Previous measurements of this cross section are reviewed and compared with our results. Recently, the examined cross section has been calculated using the continuum-discretized coupled-channels method. The results are found to be in reasonable agreement with the experimental data.

  6. On uncertainty quantification of lithium-ion batteries: Application to an LiC6/LiCoO2 cell

    NASA Astrophysics Data System (ADS)

    Hadigol, Mohammad; Maute, Kurt; Doostan, Alireza

    2015-12-01

    In this work, a stochastic, physics-based model for Lithium-ion batteries (LIBs) is presented in order to study the effects of parametric model uncertainties on the cell capacity, voltage, and concentrations. To this end, the proposed uncertainty quantification (UQ) approach, based on sparse polynomial chaos expansions, relies on a small number of battery simulations. Within this UQ framework, the identification of most important uncertainty sources is achieved by performing a global sensitivity analysis via computing the so-called Sobol' indices. Such information aids in designing more efficient and targeted quality control procedures, which consequently may result in reducing the LIB production cost. An LiC6/LiCoO2 cell with 19 uncertain parameters discharged at 0.25C, 1C and 4C rates is considered to study the performance and accuracy of the proposed UQ approach. The results suggest that, for the considered cell, the battery discharge rate is a key factor affecting not only the performance variability of the cell, but also the determination of most important random inputs.

  7. Design and feasibility of a multi-detector neutron spectrometer for radiation protection applications based on thermoluminescent 6LiF:Ti,Mg (TLD-600) detectors

    NASA Astrophysics Data System (ADS)

    Lis, M.; Gómez-Ros, J. M.; Bedogni, R.; Delgado, A.

    2008-01-01

    The design of a neutron detector with spectrometric capability based on thermoluminescent (TL) 6LiF:Ti,Mg (TLD-600) dosimeters located along three perpendicular axis within a single polyethylene (PE) sphere has been analyzed. The neutron response functions have been calculated in the energy range from 10 -8 to 100 MeV with the Monte Carlo (MC) code MCNPX 2.5 and their shape and behaviour have been used to discuss a suitable configuration for an actual instrument. The feasibility of such a device has been preliminary evaluated by the simulation of exposure to 241Am-Be, bare 252Cf and Fe-PE moderated 252Cf sources. The expected accuracy in the evaluation of energy quantities has been evaluated using the unfolding code FRUIT. The obtained results together with additional calculations performed using MAXED and GRAVEL codes show the spectrometric capability of the proposed design for radiation protection applications, especially in the range 1 keV-20 MeV.

  8. Decay of {sup 6}Be populated in the {sup 6}Li({sup 3}He,{sup 3}H) charge-exchange reaction

    SciTech Connect

    Papka, P.; Nemulodi, F.; Bark, R. A.; Kheswa, N. Y.; Lawrie, E. A.; Lawrie, J. J.; Lieder, E. O.; Lieder, R. M.; Madiba, T. E.; Mullins, S. M.; Newman, R. T.; Shirinda, O.; Singo, T. D.; Alvarez-Rodriguez, R.; Fox, S. P.; Gal, J.; Kalinka, G.; Molnar, J.; Nyako, B. M.; Timar, J.

    2010-05-15

    A complete kinematic measurement of the {sup 6}Li({sup 3}He,{sup 3}H)alphapp reaction is performed at E{sub lab}=50 MeV, to investigate the cluster structure of {sup 6}Be. The energy and angular distributions of the breakup particles, emitted from the ground and first excited states of {sup 6}Be, are compared to three-body resonance and two-body sequential decay calculations. The results indicate a rather pure three-body configuration of the 2{sup +} state of {sup 6}Be but they are not conclusive regarding the decay mode of the 0{sup +} state. No branching ratio between sequential and three-body decay paths could be extracted. Excitations above the 2{sup +} state were populated at E{sub x}=1.67-23 MeV. Decay through {sup 5}Li-p and {sup 2}He-{sup 4}He channels is identified in the continuum of {sup 6}Be, and the reaction mechanism is discussed.

  9. Astrophysical Impact of the Updated 9Be(p,α)6Li and 10B(p,α)7Be Reaction Rates As Deduced By THM

    NASA Astrophysics Data System (ADS)

    Lamia, L.; Spitaleri, C.; Tognelli, E.; Degl'Innocenti, S.; Pizzone, R. G.; Prada Moroni, P. G.

    2015-10-01

    The complete understanding of the stellar abundances of lithium, beryllium, and boron represents one of the most interesting open problems in astrophysics. These elements are largely used to probe stellar structure and mixing phenomena in different astrophysical scenarios, such as pre-main-sequence or main-sequence stars. Their different fragility against (p,α) burning reactions allows one to investigate different depths of the stellar interior. Such fusion mechanisms are triggered at temperatures between T ≈ (2-5) × {10}6 K, thus defining a corresponding Gamow energy between ≈ 3-10 keV, where S(E)-factor measurements need to be performed to get reliable reaction rate evaluations. The Trojan Horse Method is a well defined procedure to measure cross sections at Gamow energies overcoming the uncertainties due to low-energy S(E)-factor extrapolation as well as electron screening effects. Taking advantage of the {\\mathtt{THM}} measure of the 9Be(p,α)6Li and 10B(p,α)7Be cross sections, the corresponding reaction rates have been calculated and compared with the evaluations by the NACRE collaboration, widely used in the literature. The impact on surface abundances of the updated 9Be and 10B (p,α) burning rates is discussed for pre-MS stars.

  10. Detection of thermal neutrons using ZnS(Ag):6LiF neutron scintillator read out with WLS fibers and SiPMs

    NASA Astrophysics Data System (ADS)

    Hildebrandt, M.; Stoykov, A.; Mosset, J.-B.; Greuter, U.; Schlumpf, N.

    2016-07-01

    In this paper we present the development of a one-dimensional multi-channel thermal neutron detection system for the application in neutron scattering instrumentation, e.g. strain-scanning diffractometers. The detection system is based on ZnS(Ag):6LiF neutron scintillator with embedded WLS fibers which are read out with a SiPM. A dedicated signal processing system allows us to suppress the SiPM dark counts and to extract the signals from the neutron absorption events. For a single-channel detection unit which represents the elementary building block of this detection system we achieved a neutron detection efficiency of ~65% at 1.2 Å, a background count rate <10-3 Hz and a gamma-sensitivity <10-6 (measured with a 60Co source), while the dead time is ~20 μs and the multi-count ratio is < 1 %. This performance was achieved even for SiPM dark count rates of up to ~2 MHz.

  11. Astrophysical SE2 factor of the 12C(α, γ)16O reaction through the 12C(11B, 7Li)16O transfer reaction

    NASA Astrophysics Data System (ADS)

    Guo, B.; Du, X. C.; Li, Z. H.; Li, Y. J.; Pang, D. Y.; Su, J.; Yan, S. Q.; Fan, Q. W.; Gan, L.; Han, Z. Y.; Li, E. T.; Li, X. Y.; Lian, G.; Liu, J. C.; Pei, C. J.; Qiao, L. H.; Shen, Y. P.; Su, Y.; Wang, Y. B.; Zeng, S.; Zhou, Y.; Liu, W. P.

    2016-02-01

    The 12C(α, γ)16O reaction plays a key role in the evolution of stars with masses of M > 0.55 M⊙. At the Gamow peak (Ec.m. = 300 ke V, T9 = 0.2), the cross section of the 12C(α, γ)16O reaction is so small (about 10-17 barn) that the direct measurement in ground laboratory is not feasible with the existing technology. Up to now, the cross sections at lower energies can only be extrapolated from the data at higher energies. However, two subthreshold resonances, locating at Ex = 7.117 MeV and Ex = 6.917 MeV, make this extrapolation more complicated. In this work the 6.917 MeV subthreshold resonance in the 12C(α, γ)16O reaction was investigated via the 12C(11B, 7Li)16O reaction. The experiment was performed using the Q3D magnetic spectrograph at HI-13 tandem accelerator. We measured the angular distribution of the 12C(11B, 7Li)16O transfer reaction leading to the 6.917 MeV state. Based on DWBA analysis, we derived the square of ANC of the 6.917 MeV level in 16O to be (2.45± 0.28) ×1010 fm-1, with which the reduced-α width can be computed. Finally, we calculated the astrophysical SE2 factor of the 6.917 MeV resonance to be 67.6 ± 7.7 ke V b.

  12. Diffraction dissociation of {sup 7}Li and {sup 7}Be relativistic nuclei on proton targets through the {sup 3}H({sup 3}He)+{sup 4}He channels

    SciTech Connect

    Fetisov, V. N.

    2015-07-15

    For the fragmentation of {sup 7}Li and {sup 7}Be relativistic nuclei (with momenta of, respectively, P = 3 GeV/c and P = 1.6 GeV/c per nucleon) on proton targets through the {sup 3}H({sup 3}He) + {sup 4}He channels, the differential cross sections with respect to the momentum transfer Q to the fragments were calculated on the basis of the cluster version of Akhiezer–Glauber–Sitenko diffraction theory by employing the twobody cluster model for the {sup 7}Li ({sup 3}H + {sup 4}He) and {sup 7}Be ({sup 3}He + {sup 4}He) nuclei. These calculations, performed in the impulse approximation in the interaction of intranuclear clusters with the target nucleus, explained a strong suppression of the cross sections for reactions on protons at Q lower than 100 MeV/c and higher than 350 MeV/c and the observed irregularities in the behavior off the cross section for {sup 7}Li fragmentation on complex track-emulsion nuclei. Cross-section values close to their experimental counterparts were obtained upon setting the coefficient of two-body clustering in the {sup 7}Li and {sup 7}Be nuclei to k ≃ 0.7.

  13. Computational, electrochemical and {sup 7}Li NMR studies of lithiated disordered carbons electrodes in lithium ion cells.

    SciTech Connect

    Sandi, G.; Gerald, R., II; Scanlon, L. G.; Carrado, K. A.; Winans, R. E.

    1998-01-07

    Disordered carbons that deliver high reversible capacity in electrochemical cells have been synthesized by using inorganic clays as templates to control the pore size and the surface area. The capacities obtained were much higher than those calculated if the resultant carbon had a graphitic-like structure. Computational chemistry was used to investigate the nature of lithium bonding in a carbon lattice unlike graphite. The lithium intercalated fullerene Li{sub n}-C{sub 60} was used as a model for our (non-graphitic) disordered carbon lattice. A dilithium-C{sub 60} system with a charge and multiplicity of (0,1) and a trilithium-C{sub 60} system with a charge and multiplicity of (0,4) were investigated. The spatial distribution of lithium ions in an electrochemical cell containing this novel disordered carbon material was investigated in situ by Li-7 NMR using an electrochemical cell that was incorporated into a toroid cavity nuclear magnetic resonance (NMR) imager. The concentration of solvated Li{sup +} ions in the carbon anode appears to be larger than in the bulk electrolyte, is substantially lower near the copper/carbon interface, and does not change with cell charging.

  14. Lithium motion in the anode material LiC6 as seen via time-domain 7Li NMR

    NASA Astrophysics Data System (ADS)

    Langer, J.; Epp, V.; Heitjans, P.; Mautner, F. A.; Wilkening, M.

    2013-09-01

    Since the commercialization of rechargeable lithium-ion energy storage systems in the early 1990s, graphite intercalation compounds (GICs) have served as the number one negative electrode material in most of today's batteries. During charging the performance of a battery is closely tied with facile Li insertion into the graphite host structure. So far, only occasionally time-domain nuclear magnetic resonance (NMR) measurements have been reported to study Li self-diffusion parameters in GICs. Here, we used several NMR techniques to enlighten Li hopping motions from an atomic-scale point of view. Li self-diffusion in the stage-1 GIC LiC6 has been studied comparatively by temperature-variable spin-spin relaxation NMR as well as (rotating frame) spin-lattice relaxation NMR. The data collected yield information on both the relevant activation energies and jump rates, which can directly be transformed into Li self-diffusion coefficients. At room temperature the Li self-diffusion coefficient turns out to be 10-15m2s-1, thus, slightly lower than that for layer-structured cathode materials such as Lix≈0.7TiS2.

  15. Optimization of a neutron production target and a beam shaping assembly based on the 7Li( p, n) 7Be reaction for BNCT

    NASA Astrophysics Data System (ADS)

    Burlon, A. A.; Kreiner, A. J.; Valda, A. A.; Minsky, D. M.; Somacal, H. R.; Debray, M. E.; Stoliar, P.

    2005-02-01

    In this work a thick LiF target was studied through the 7Li( p, n) 7Be reaction as a neutron source for Accelerator-Based Boron Neutron Capture Therapy (AB-BNCT) to provide a testing ground for numerical simulations aimed at producing an optimized neutron production target and beam shaping assembly design. Proton beams in the 1.88-2.0 MeV energy range were produced with the tandem accelerator TANDAR ( TANDem ARgentino) at the Comisión Nacional de Energía Atómica (CNEA) in Buenos Aires, Argentina. A cylindrical water-filled head-phantom, containing a boric acid sample, was irradiated to study the resulting neutron flux. The dose deposited in the boric acid sample was inferred through the Compton-suppressed detection of the gamma radiation produced from the 10B( n, αγ) 7Li capture reaction. The thermal neutron flux was evaluated using bare and Cd-covered activation gold foils. In all cases, Monte Carlo simulations have been done showing good agreement with the experimental results. Extensive MCNP simulation trials have then been performed after the preliminary calculation tool validation in order to optimize a neutron beam shaping assembly. These simulations include a thick Li metal target (instead of LiF), a whole-body phantom, two different moderator-reflector assemblies (Al/AlF 3/LiF, Fluental ®, as moderator and lead as reflector and a combination of Al, PTFE (polytetrafluoroethylene) and LiF as moderator and lead as reflector) and the treatment room. The doses were evaluated for proton bombarding energies of 1.92 MeV (near to the threshold of the reaction), 2.0 MeV, 2.3 MeV (near the reaction resonance) and 2.5 MeV, and for three Fluental ® and Al/PTFE/LiF moderator thicknesses (18, 26 and 34 cm). In a later instance, the effect of the specific skin radiosensitivity (an RBE of 2.5 for the 10B( n, α) 7Li reaction) and a 10B uptake 50% greater than the healthy tissue one, was considered for the scalp. To evaluate the doses in the phantom, a comparison of

  16. Particle Leaking, Cross-Section Ratio 10B(n,{alpha})/238U(n,fission), and Excitation Function of the Reaction 10B(n,{alpha})7Li at MeV Energies

    SciTech Connect

    Giorginis, Georgios; Khryachkov, Vitali

    2005-05-24

    The 10B(n,{alpha})7Li reaction was studied in the energy range between 1.5 MeV and 5.6 MeV at the 7-MV Van de Graaff accelerator of IRMM by using a gridded ionisation chamber, signal digitisation, and an intrinsic 238U neutron monitor. The aim was to obtain accurate data for the IAEA Coordinated Research Project (CRP) on the improvement of standard cross sections for light elements. The effect of particle leaking was discovered and its implications investigated. The determination of the cross section {sigma}({alpha}0+{alpha}1) strongly benefits from it but measurements of angular distributions, individual cross sections {sigma}({alpha}0) and {sigma}({alpha}1), and the branching ratio {alpha}0/{alpha}1 are negatively affected. The correct number of reaction events was obtained by identification of unknown particle signatures in the energy spectra as 10B(n,{alpha})7Li events in the form of quasi 7Li+{alpha} particles created by particle leaking. The cross-section ratio 10B(n,{alpha})7Li/238U(n,fission) was measured and the excitation function of 10B(n,{alpha})7Li determined by simultaneously detecting the charged particles from the boron disintegration in the forward hemisphere and the 238U fission fragments in the backward hemisphere. The IRMM cross sections are compared to experimental data of other groups and to predictions of the ENDF/B-VI.8, JENDL-3.3, and JEF-2.2 evaluations.

  17. Probing the nuclear medium with the K{sup +} meson

    SciTech Connect

    Chrien, R.E.

    1995-12-31

    Elastic differential cross sections for K{sup +} mesons scattered from targets of carbon and {sup 6}Li have been measured at an incident momentum of 715 MeV/c. The ratios of scattering cross sections from these targets are not predicted by theory, and are consistent with earlier suggestions that the K{sup +}-nucleon interaction is modified in the nuclear medium.

  18. Observation of breakup transfer process for the bound states of {sup 16}O populated from {sup 12}C({sup 6}Li,d) reaction at 20 MeV

    SciTech Connect

    Adhikari, S.; Basu, C.; Thompson, I. J.; Sugathan, P.; Jhinghan, A.; Golda, K. S.; Babu, A.; Singh, D.; Ray, S.; Mitra, A. K.

    2012-10-20

    The deuteron angular distribution for the {sup 12}C({sup 6}Li,d){sup 16}O* has been measured at 20 MeV populating bound and unbound states of {sup 16}O. Analysis shows a dominance of breakup induced alpha transfer in comparison to a direct alpha transfer process for the bound states. The effect increases as the excitation energy of {sup 16}O decreases, maximizing at the ground state.

  19. 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.

  20. 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.

  1. Mechanical Property and Intergranular Corrosion Sensitivity of Zn-Free and Zn-Microalloyed Al-2.7Cu-1.7Li-0.3Mg Alloys

    NASA Astrophysics Data System (ADS)

    Li, Jin-feng; Xu, Long; Cai, Chao; Chen, Yong-lai; Zhang, Xu-hu; Zheng, Zi-qiao

    2014-11-01

    The influence of 0.72 pct Zn addition on the tensile properties of Al-2.7Cu-1.7Li-0.3Mg alloys was investigated. Their intergranular corrosion (IGC) dependence on aging [T6 type at 423 K (150 °C) and 448 K (175 °C) and T8 type at 423 K (150 °C)] time was studied. An IGC diagram associated with aging process was established. The addition of 0.72 pct Zn enhanced the strength of the Al-Li alloy with T6 type aging at 448 K (175 °C). With aging process, the corrosion mode of the T6-aged Al-Li alloys was changed in the following order: pitting and local IGC (initial aging stage), general IGC (underaging stage), local IGC (near peak-aging stage), and pitting (overaging stage) again. The IGC depth was increased first and then decreased with aging time extension. The corrosion potential change of grains and the microstructure variation were used to explain the IGC sensitivity of the Al-Li alloy with different tempers. Meanwhile, 0.72 pct Zn addition decreased the IGC sensitivity of the Al-Li alloy, especially the T6-aged Al-Li alloy.

  2. Mechanical Property and Intergranular Corrosion Sensitivity of Zn-Free and Zn-Microalloyed Al-2.7Cu-1.7Li-0.3Mg Alloys

    NASA Astrophysics Data System (ADS)

    Li, Jin-feng; Xu, Long; Cai, Chao; Chen, Yong-lai; Zhang, Xu-hu; Zheng, Zi-qiao

    2014-09-01

    The influence of 0.72 pct Zn addition on the tensile properties of Al-2.7Cu-1.7Li-0.3Mg alloys was investigated. Their intergranular corrosion (IGC) dependence on aging [T6 type at 423 K (150 °C) and 448 K (175 °C) and T8 type at 423 K (150 °C)] time was studied. An IGC diagram associated with aging process was established. The addition of 0.72 pct Zn enhanced the strength of the Al-Li alloy with T6 type aging at 448 K (175 °C). With aging process, the corrosion mode of the T6-aged Al-Li alloys was changed in the following order: pitting and local IGC (initial aging stage), general IGC (underaging stage), local IGC (near peak-aging stage), and pitting (overaging stage) again. The IGC depth was increased first and then decreased with aging time extension. The corrosion potential change of grains and the microstructure variation were used to explain the IGC sensitivity of the Al-Li alloy with different tempers. Meanwhile, 0.72 pct Zn addition decreased the IGC sensitivity of the Al-Li alloy, especially the T6-aged Al-Li alloy.

  3. Ab initio calculations of accurate dissociation energy and analytic potential energy function for the second excited state B1Π of 7LiH

    NASA Astrophysics Data System (ADS)

    Shi, De-Heng; Liu, Yu-Fang; Sun, Jin-Feng; Zhu, Zun-Lue; Yang, Xiang-Dong

    2006-12-01

    The reasonable dissociation limit of the second excited singlet state B1Π of 7LiH molecule is obtained. The accurate dissociation energy and equilibrium geometry of the B1Π state are calculated using a symmetry-adapted-cluster configuration-interaction method in full active space. The whole potential energy curve for the B1Π state is obtained over the internuclear distance ranging from about 0.10 nm to 0.54 nm, and has a least-square fit to the analytic Murrell-Sorbie function form. The vertical excitation energy is calculated from the ground state to the B1Π state and compared with previous theoretical results. The equilibrium internuclear distance obtained by geometry optimization is found to be quite different from that obtained by single-point energy scanning under the same calculation condition. Based on the analytic potential energy function, the harmonic frequency value of the B1Π state is estimated. A comparison of the theoretical calculations of dissociation energies, equilibrium interatomic distances and the analytic potential energy function with those obtained by previous theoretical results clearly shows that the present work is more comprehensive and in better agreement with experiments than previous theories, thus it is an improvement on previous theories.

  4. Development of liquid-lithium film jet-flow for the target of (7)Li(p,n)(7)Be reactions for BNCT.

    PubMed

    Kobayashi, Tooru; Miura, Kuniaki; Hayashizaki, Noriyosu; Aritomi, Masanori

    2014-06-01

    A feasibility study on liquid lithium target in the form of a flowing film was performed to evaluate its potential use as a neutron generation target of (7)Li(p,n)(7)Be reaction in BNCT. The target is a windowless-type flowing film on a concave wall. Its configuration was adapted for a proton beam which is 30mm in diameter and with energy and current of up to 3MeV and 20mA, respectively. The flowing film of liquid lithium was 0.6mm in thickness, 50mm in width and 50mm in length. The shapes of the nozzle and concave back wall, which create a stable flowing film jet, were decided based on water experiments. A lithium hydrodynamic experiment was performed to observe the stability of liquid lithium flow behavior. The flowing film of liquid lithium was found to be feasible at temperatures below the liquid lithium boiling saturation of 342°C at the surface pressure of 1×10(-3)Pa. Using a proto-type liquid lithium-circulating loop for BNCT, the stability of the film flow was confirmed for velocities up to 30m/s at 220°C and 250°C in vacuum at a pressure lower than 10(-3) Pa. It is expected that for practical use, a flowing liquid lithium target of a windowless type can solve the problem of radiation damage and target cooling. PMID:24412425

  5. Li(+) Local Structure in Li-Tetraglyme Solvate Ionic Liquid Revealed by Neutron Total Scattering Experiments with the (6/7)Li Isotopic Substitution Technique.

    PubMed

    Saito, Soshi; Watanabe, Hikari; Hayashi, Yutaka; Matsugami, Masaru; Tsuzuki, Seiji; Seki, Shiro; Canongia Lopes, José N; Atkin, Rob; Ueno, Kazuhide; Dokko, Kaoru; Watanabe, Masayoshi; Kameda, Yasuo; Umebayashi, Yasuhiro

    2016-07-21

    Equimolar mixtures of lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) and tetraglyme (G4: CH3O-(CH2CH2O)4-CH3) yield the solvate (or chelate) ionic liquid [Li(G4)][TFSA], which is a homogeneous transparent solution at room temperature. Solvate ionic liquids (SILs) are currently attracting increasing research interest, especially as new electrolytes for Li-sulfur batteries. Here, we performed neutron total scattering experiments with (6/7)Li isotopic substitution to reveal the Li(+) solvation/local structure in [Li(G4)][TFSA] SILs. The experimental interference function and radial distribution function around Li(+) agree well with predictions from ab initio calculations and MD simulations. The model solvation/local structure was optimized with nonlinear least-squares analysis to yield structural parameters. The refined Li(+) solvation/local structure in the [Li(G4)][TFSA] SIL shows that lithium cations are not coordinated to all five oxygen atoms of the G4 molecule (deficient five-coordination) but only to four of them (actual four-coordination). The solvate cation is thus considerably distorted, which can be ascribed to the limited phase space of the ethylene oxide chain and competition for coordination sites from the TFSA anion. PMID:27388117

  6. Formation of ultracold (7)Li(85)Rb molecules in the lowest triplet electronic state by photoassociation and their detection by ionization spectroscopy.

    PubMed

    Altaf, Adeel; Dutta, Sourav; Lorenz, John; Pérez-Ríos, Jesús; Chen, Yong P; Elliott, D S

    2015-03-21

    We report the formation of ultracold (7)Li(85)Rb molecules in the a(3)Σ(+) electronic state by photoassociation (PA) and their detection via resonantly enhanced multiphoton ionization (REMPI). With our dual-species Li and Rb magneto-optical trap apparatus, we detect PA resonances with binding energies up to ∼62 cm(-1) below the (7)Li 2s (2)S1/2 + (85)Rb 5p (2)P1/2 asymptote. In addition, we use REMPI spectroscopy to probe the a(3)Σ(+) state and excited electronic 3(3)Π and 4(3)Σ(+) states and identify a(3)Σ(+) (v″ = 7-13), 3(3)Π (vΠ' = 0-10), and 4(3)Σ(+) (vΣ' = 0-5) vibrational levels. Our line assignments agree well with ab initio calculations. These preliminary spectroscopic studies on previously unobserved electronic states are crucial to discovering transition pathways for transferring ultracold LiRb molecules created via PA to deeply bound rovibrational levels of the electronic ground state. PMID:25796252

  7. Formation of ultracold {sup 7}Li{sup 85}Rb molecules in the lowest triplet electronic state by photoassociation and their detection by ionization spectroscopy

    SciTech Connect

    Altaf, Adeel Dutta, Sourav; Lorenz, John; Pérez-Ríos, Jesús; Chen, Yong P.; Elliott, D. S.

    2015-03-21

    We report the formation of ultracold {sup 7}Li{sup 85}Rb molecules in the a{sup 3}Σ{sup +} electronic state by photoassociation (PA) and their detection via resonantly enhanced multiphoton ionization (REMPI). With our dual-species Li and Rb magneto-optical trap apparatus, we detect PA resonances with binding energies up to ∼62 cm{sup −1} below the {sup 7}Li 2s {sup 2}S{sub 1/2} + {sup 85}Rb 5p {sup 2}P{sub 1/2} asymptote. In addition, we use REMPI spectroscopy to probe the a{sup 3}Σ{sup +} state and excited electronic 3{sup 3}Π and 4{sup 3}Σ{sup +} states and identify a{sup 3}Σ{sup +} (v″ = 7–13), 3{sup 3}Π (v{sub Π}′ = 0–10), and 4{sup 3}Σ{sup +} (v{sub Σ}′ = 0–5) vibrational levels. Our line assignments agree well with ab initio calculations. These preliminary spectroscopic studies on previously unobserved electronic states are crucial to discovering transition pathways for transferring ultracold LiRb molecules created via PA to deeply bound rovibrational levels of the electronic ground state.

  8. Ab initio calculation of accurate dissociation energy, potential energy curve and dipole moment function for the A1Σ+ state 7LiH molecule

    NASA Astrophysics Data System (ADS)

    Shi, De-Heng; Liu, Yu-Fang; Sun, Jin-Feng; Yang, Xiang-Dong; Zhu, Zun-Lue

    2006-05-01

    The reasonable dissociation limit of the A1Σ+ state 7LiH molecule is obtained. The accurate dissociation energy and the equilibrium geometry of this state are calculated using a symmetry-adapted-cluster configuration-interaction method in complete active space for the first time. The whole potential energy curve and the dipole moment function for the A1Σ+ state are calculated over a wide internuclear separation range from about 0.1 to 1.4 nm. The calculated equilibrium geometry and dissociation energy of this potential energy curve are of Re=0.2487 nm and De=1.064 eV, respectively. The unusual negative values of the anharmonicity constant and the vibration-rotational coupling constant are of ωeχe=-4.7158cm-1 and αe=-0.08649cm-1, respectively. The vertical excitation energy from the ground to the A1Σ+ state is calculated and the value is of 3.613 eV at 0.15875 nm (the equilibrium position of the ground state). The highly anomalous shape of this potential energy curve, which is exceptionally flat over a wide radial range around the equilibrium position, is discussed in detail. The harmonic frequency value of 502.47cm-1 about this state is approximately estimated. Careful comparison of the theoretical determinations with those obtained by previous theories about the A1Σ+ state dissociation energy clearly shows that the present calculations are much closer to the experiments than previous theories, thus represents an improvement.

  9. Near-threshold (7)Li(p,n)(7)Be neutrons on the practical conditions using thick Li-target and Gaussian proton energies for BNCT.

    PubMed

    Kobayashi, Tooru; Hayashizaki, Noriyosu; Katabuchi, Tatsuya; Tanaka, Kenichi; Bengua, Gerard; Nakao, Noriaki; Kosako, Kazuaki

    2014-06-01

    The near threshold (7)Li(p,n)(7)Be neutrons generated by incident proton energy having Gaussian distribution with mean energies from 1.85 to 1.95MeV, were studied as a practical neutron source for BNCT wherein an RFQ accelerator and a thick Li-target are used. Gaussian energy distributions with the standard deviation of 0, 10, 20 and 40keV for mean proton energies from 1.85 to 1.95MeV were surveyed in 0.01MeV increments. A thick liquid Li-target whose dimensions were established in our previous experiments (i.e., 1mm-thick with 50mm width and 50mm length) was considered in this study. The suitable incident proton energy and physical dimensions of Pb layer which serves as a gamma absorber and a Polyethylene layer which is used as a BDE were surveyed by means of the concepts of TPD. Dose distribution were calculated by using MCNP5. A proton beam with mean energy of 1.92MeV and a Gaussian energy distribution with a standard deviation of 20keV at a current of 10mA was selected from the viewpoint of irradiation time and practically achievable proton current. The suitable thicknesses of Pb gamma absorber was estimated to be about 3cm. The estimated thickness of the polyethylene BDE was about 24mm for an ideal proton current of 13mA, and was 18mm for a practical proton current of 10mA. PMID:24491682

  10. Present Status of Nuclear Data for Nuclear Nonproliferation

    NASA Astrophysics Data System (ADS)

    Igashira, M.

    2015-10-01

    The present status of nuclear data was reviewed from the viewpoint of the research and development of non-destructive inspection methods for international controlled materials such as 235U, 239Pu, 241Pu, D2O, 6LiD, and 9Be. The nuclear characteristics of these materials were discussed, and neutron- and photon-reaction cross section data were reviewed. It was found that the accuracy of neutron data was enough for the research and development but that of photon data was not enough.

  11. Nuclear excitations at constant temperature

    SciTech Connect

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

    2009-03-15

    Neutron and proton evaporation spectra from the {sup 6}Li+{sup 55}Mn and d+{sup 59}Co reactions have been analyzed with the Hauser-Feshbach approach using different input models for nuclear level densities of {sup 60}Ni and {sup 60}Co nuclei. It has been found that models with a Fermi-gas like temperature dependence fail to reproduce particle spectra from both reactions simultaneously. We obtained the surprising result that the only way to describe our data is to assume the independence of the nuclear temperature on the excitation energy up to about the 20 MeV energy range.

  12. Investigation of spin-isospin strength in sup 48 Ca r arrow sup 48 Sc and sup 90 Zr r arrow sup 90 Nb using the ( sup 6 Li, sup 6 He) reaction

    SciTech Connect

    Wirth, H.; Aschenauer, E.; Eyrich, W.; Lehmann, A.; Moosburger, M.; Schloesser, H. ); Gils, H.J.; Rebel, H.; Zagromski, S. )

    1990-06-01

    The ({sup 6}Li,{sup 6}He) reaction was studied on the target nuclei {sup 48}Ca and {sup 90}Zr at {ital E}{sub Li}=156 MeV at extreme forward reaction angles. From the zero degree spectra Gamow-Teller strength was extracted for excitation energies 0{le}{ital E}{sub {ital x}}{approx lt}20 MeV. The results are compared with distorted-wave Born approximation calculations and ({ital p},{ital n}) data.

  13. Experimental differential cross sections, level densities, and spin cutoffs as a testing ground for nuclear reaction codes

    DOE PAGESBeta

    Voinov, Alexander V.; Grimes, Steven M.; Brune, Carl R.; Burger, Alexander; Gorgen, Andreas; Guttormsen, Magne; Larsen, Ann -Cecilie; Massey, Thomas N.; Siem, Sunniva

    2013-11-08

    Proton double-differential cross sections from 59Co(α,p)62Ni, 57Fe(α,p)60Co, 56Fe(7Li,p)62Ni, and 55Mn(6Li,p)60Co reactions have been measured with 21-MeV α and 15-MeV lithium beams. Cross sections have been compared against calculations with the empire reaction code. Different input level density models have been tested. It was found that the Gilbert and Cameron [A. Gilbert and A. G. W. Cameron, Can. J. Phys. 43, 1446 (1965)] level density model is best to reproduce experimental data. Level densities and spin cutoff parameters for 62Ni and 60Co above the excitation energy range of discrete levels (in continuum) have been obtained with a Monte Carlo technique. Furthermore,more » excitation energy dependencies were found to be inconsistent with the Fermi-gas model.« less

  14. Experimental differential cross sections, level densities, and spin cutoffs as a testing ground for nuclear reaction codes

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    Proton double-differential cross sections from 59Co(α,p)62Ni, 57Fe(α,p)60Co, 56Fe(7Li,p)62Ni, and 55Mn(6Li,p)60Co reactions have been measured with 21-MeV α and 15-MeV lithium beams. Cross sections have been compared against calculations with the empire reaction code. Different input level density models have been tested. It was found that the Gilbert and Cameron [A. Gilbert and A. G. W. Cameron, Can. J. Phys.0008-420410.1139/p65-139 43, 1446 (1965)] level density model is best to reproduce experimental data. Level densities and spin cutoff parameters for 62Ni and 60Co above the excitation energy range of discrete levels (in continuum) have been obtained with a Monte Carlo technique. Excitation energy dependencies were found to be inconsistent with the Fermi-gas model.

  15. Competition between Na + and Li + for Unsealed and Cytoskeleton-Depleted Human Red Blood Cell Membrane: A 23Na Multiple Quantum Filtered and 7Li NMR Relaxation Study

    NASA Astrophysics Data System (ADS)

    Srinivasan, Chandra; Minadeo, Nicole; Toon, Jason; Graham, Daniel; Mota de Freitas, Duarte; Geraldes, Carlos F. G. C.

    1999-09-01

    Evidence for competition between Li+ and Na+ for binding sites of human unsealed and cytoskeleton-depleted human red blood cell (csdRBC) membranes was obtained from the effect of added Li+ upon the 23Na double quantum filtered (DQF) and triple quantum filtered (TQF) NMR signals of Na+-containing red blood cell (RBC) membrane suspensions. We found that, at low ionic strength, the observed quenching effect of Li+ on the 23Na TQF and DQF signal intensity probed Li+/Na+ competition for isotropic binding sites only. Membrane cytoskeleton depletion significantly decreased the isotropic signal intensity, strongly affecting the binding of Na+ to isotropic membrane sites, but had no effect on Li+/Na+ competition for those sites. Through the observed 23Na DQF NMR spectra, which allow probing of both isotropic and anisotropic Na+ motion, we found anisotropic membrane binding sites for Na+ when the total ionic strength was higher than 40 mM. This is a consequence of ionic strength effects on the conformation of the cytoskeleton, in particular on the dimer-tetramer equilibrium of spectrin. The determinant involvement of the cytoskeleton in the anisotropy of Na+ motion at the membrane surface was demonstrated by the isotropy of the DQF spectra of csdRBC membranes even at high ionic strength. Li+ addition initially quenched the isotropic signal the most, indicating preferential Li+/Na+ competition for the isotropic membrane sites. High ionic strength also increased the intensity of the anisotropic signal, due to its effect on the restructuring of the membrane cytoskeleton. Further Li+ addition competed with Na+ for those sites, quenching the anisotropic signal. 7Li T1 relaxation data for Li+-containing suspensions of unsealed and csdRBC membranes, in the absence and presence of Na+ at low ionic strength, showed that cytoskeleton depletion does not affect the affinity of Na+ for the RBC membrane, but increases the affinity of Li+ by 50%. This clearly indicates that cytoskeleton

  16. Ca(AlH4)2, CaAlH5, and CaH2+6LiBH4: Calculated dehydrogenation enthalpy, including zero point energy, and the structure of the phonon spectra.

    PubMed

    Marashdeh, Ali; Frankcombe, Terry J

    2008-06-21

    The dehydrogenation enthalpies of Ca(AlH(4))(2), CaAlH(5), and CaH(2)+6LiBH(4) have been calculated using density functional theory calculations at the generalized gradient approximation level. Harmonic phonon zero point energy (ZPE) corrections have been included using Parlinski's direct method. The dehydrogenation of Ca(AlH(4))(2) is exothermic, indicating a metastable hydride. Calculations for CaAlH(5) including ZPE effects indicate that it is not stable enough for a hydrogen storage system operating near ambient conditions. The destabilized combination of LiBH(4) with CaH(2) is a promising system after ZPE-corrected enthalpy calculations. The calculations confirm that including ZPE effects in the harmonic approximation for the dehydrogenation of Ca(AlH(4))(2), CaAlH(5), and CaH(2)+6LiBH(4) has a significant effect on the calculated reaction enthalpy. The contribution of ZPE to the dehydrogenation enthalpies of Ca(AlH(4))(2) and CaAlH(5) calculated by the direct method phonon analysis was compared to that calculated by the frozen-phonon method. The crystal structure of CaAlH(5) is presented in the more useful standard setting of P2(1)c symmetry and the phonon density of states of CaAlH(5), significantly different to other common complex metal hydrides, is rationalized. PMID:18570508

  17. Investigation of Local Structure and Cation Ordering in Dielectric Oxide Microwave Ceramics with stoichiometry A(Lix(Nb,Ta)y) O3 Using 7Li and 93Nb solid-state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Kalfarisi, Rony

    The local structure and cation ordering in dielectric oxide microwave ceramics with stoichiometry A(Lix(Nb,Ta)y) O3 are investigated using 7Li and 93Nb solid-state NMR spectroscopy. For all samples, 7Li MAS NMR spectra show one strong and sharp resonance peak indicating one unique environment which corresponds to local lithium environment of nearest B-site neighbor (nBn) surrounded by 4 LiO6 octahedra and 2 NbO6 octahedra (TaO6 in some samples). In addition to this, 7Li MAS NMR spectrum of (Ca2/3La1/3) (Li1/3Nb2/3) O3 show one additional weak and broad resonance peak which can be assigned to nBn of 3 LiO6 octahedra and 3 NbO6 octahedra. 93Nb MAS NMR spectra of samples with niobium content, show a resonance peak with tail toward the low frequency limit, an evidence to the existence of chemical shifts and quadrupole couplings distributions. Both (Sr2/3La1/3) (Li1/3Nb2/3) O3 and Ca(Li1/4Nb3/4) O3 spectra show one broad resonance peak, which can be interpreted as one NbO6 octahedron nBn with many slight variations through out the sample. While (Ca2/3La1/3) (Li1/3Nb2/3) O3 spectra show four peaks correspond to four distinct NbO6 octahedra local nBn environments with the nBn configuration as: (i) 3 LiO6 and 3 NbO6; (ii) 2 LiO6 and 4 NbO6; (iii) 1 LiO6 and 5 NbO6; (iv) all 6 NbO6

  18. An algorithm for quantum mechanical finite-nuclear-mass variational calculations of atoms with L = 3 using all-electron explicitly correlated Gaussian basis functions.

    PubMed

    Sharkey, Keeper L; Kirnosov, Nikita; Adamowicz, Ludwik

    2013-03-14

    A new algorithm for quantum-mechanical nonrelativistic calculation of the Hamiltonian matrix elements with all-electron explicitly correlated Gaussian functions for atoms with an arbitrary number of s electrons and with three p electrons, or one p electron and one d electron, or one f electron is developed and implemented. In particular the implementation concerns atomic states with L = 3 and M = 0. The Hamiltonian used in the approach is obtained by rigorously separating the center-of-mass motion from the laboratory-frame all particle Hamiltonian, and thus it explicitly depends on the finite mass of the nucleus. The approach is employed to perform test calculations on the lowest (2)F state of the two main isotopes of the lithium atom, (7)Li and (6)Li. PMID:23514465

  19. Nuclear Astrophysics and Structure Studies Using Low-energy RI Beams at CRIB

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Hashimoto, T.; Hayakawa, S.; Binh, D. N.; Kahl, D.; Kubono, S.

    2010-05-01

    CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Using the RI beams at CRIB, Many measurements on proton and alpha resonance scatterings, (α,p) reactions, and others were peformed in recent years, mainly for studying astrophysical reactions and exotic nuclear structure. Among them, the results on the 7Be+p and 7Li+α resonance scatterings are presented.

  20. Polarization observables in [pi][sup +] [sup 6]Li scattering: Analyzing powers [ital iT][sub 11] and [tau][sub 22

    SciTech Connect

    Ritt, S.; Boschitz, E.; Brinkmoeller, B.; Buehler, J.; Meier, R.; Wessler, M. ); Konter, J.A.; Mango, S.; van den Brandt, B. ); Kamalov, S.S. ); Eramzhyan, R.A. ); Ryzhikh, G.G. )

    1994-06-01

    The vector analyzing power [ital iT][sub 11] and the tensor analyzing power [tau][sub 22]=[ital T][sub 22]+[ital T][sub 20]/ [radical]6 have been measured for [pi][sup +][r arrow][sup 6]L[rvec i] elastic and inelastic scattering (to the 3[sup +]0, 2.19 MeV state) at incident pion energies of 120, 150, 180, and 194 MeV. These data and earlier ones from our group are compared with new coupled channels calculations. Within the coupled channels model, the influence of different nuclear wave functions, the strength of the coupling of the ground and first excited states, and the effects of the phenomenological second-order potential were investigated. It was found that the calculated vector analyzing power [ital iT][sub 11] depends strongly on the transverse form factor whichever nuclear wave function is chosen. In the angular region where the [ital iT][sub 11] data were taken the coupling of the ground to the first excited state has a minor effect on the theoretical predictions. Reasonable agreement with the data can be obtained for a large energy and angular region with the first-order potential only.

  1. Study of the excitation region 45--57 MeV of the /sup 7/Be nucleus in the reaction /sup 6/Li(p,. cap alpha. )/sup 3/He

    SciTech Connect

    Nemets, O.F.; Ostashko, V.V.; Povoroznik, O.M.; Urin, V.N.; Yasnogorodskii, A.M.; Barit, I.Y.; Zuev, S.V.

    1984-07-01

    To investigate the excitation region 45--57 MeV of the /sup 7/Be nucleus we have studied the reaction /sup 6/Li(p,..cap alpha..)/sup 3/He at proton energies E/sub p/ = 47.8--62.5 MeV. The measurements were made in the U-240 isochronous cyclotron at our institute. The energy dependences obtained for the angular distributions have been analyzed by parametrization in terms of expansions in Legendre polynomials. A departure of the expansion coefficients from a monotonic dependence is observed in the proton-energy region near 55 MeV, which corresponds to a /sup 7/Be excitation energy of about 50 MeV.

  2. Comment on ``Three-body resonances in {sup 6}He, {sup 6}Li, and {sup 6}Be, and the soft dipole mode problem of neutron halo nuclei``

    SciTech Connect

    Hayes, A.C.; Sterbenz, S.M.

    1995-11-01

    In a recent publication Csoto suggests that the sequential decay of {sup 11}Li through resonances in {sup 10}Li could explain the peak seen at 1.2 MeV of excitation in the {sup 11}B({pi}{sup {minus}},{pi}{sup +}) reaction. We point out that this is in conflict with widely accepted notions of probe and target interactions in the measurement of inclusive excitation functions via nuclear reactions ranging from inelastic scattering and heavy-ion transfer reactions to pion double-charge exchange. We also show that the suggested mechanism leads to incorrect predictions in other nuclei, and so we conclude that the apparent success of the mechanism in explaining the observed energy of excited states in the {sup 11}Li and {sup 6}He systems is accidental.

  3. Characteristics of boron-dose enhancer dependent on dose protocol and 10B concentration for BNCT using near-threshold 7Li(p,n)7Be direct neutrons

    NASA Astrophysics Data System (ADS)

    Tanaka, Kenichi; Kobayashi, Tooru; Bengua, Gerard; Nakagawa, Yoshinobu; Endo, Satoru; Hoshi, Masaharu

    2005-01-01

    The dependence of boron-dose enhancer (BDE) characteristics on dose protocol and 10B concentration was evaluated for BNCT using near-threshold 7Li(p,n)7Be direct neutrons. The treatable protocol depth (TPD) was utilized as an evaluation index. MCNP calculations were performed for near-threshold 7Li(p,n)7Be at a proton energy of 1.900 MeV and for a polyethylene BDE. The effect of dose protocol on BDE characteristics was reflected in terms of the optimum BDE thickness needed for maximum TPD which was found to be independent of the treatable dose but was observed to vary for different combinations of the tolerance doses for heavy charged particles and gamma rays. For the 10B concentration dependence, the TPD was increased by increasing the T/N ratio, i.e., the ratio of the 10B concentration in the tumour (10BTumour) to that in the normal tissue (10BNormal), and by increasing 10BTumour and 10BNormal at constant T/N ratio. It was found that the use of BDE becomes unnecessary from the viewpoint of increasing the TPD, when 10BTumour is over a certain level which is decided by the conditions of the dose protocol.

  4. Characteristics of boron-dose enhancer dependent on dose protocol and 10B concentration for BNCT using near-threshold 7Li(p,n)7Be direct neutrons.

    PubMed

    Tanaka, Kenichi; Kobayashi, Tooru; Bengua, Gerard; Nakagawa, Yoshinobu; Endo, Satoru; Hoshi, Masaharu

    2005-01-01

    The dependence of boron-dose enhancer (BDE) characteristics on dose protocol and 10B concentration was evaluated for BNCT using near-threshold 7Li(p,n)7Be direct neutrons. The treatable protocol depth (TPD) was utilized as an evaluation index. MCNP calculations were performed for near-threshold 7Li(p,n)7Be at a proton energy of 1.900 MeV and for a polyethylene BDE. The effect of dose protocol on BDE characteristics was reflected in terms of the optimum BDE thickness needed for maximum TPD which was found to be independent of the treatable dose but was observed to vary for different combinations of the tolerance doses for heavy charged particles and gamma rays. For the 10B concentration dependence, the TPD was increased by increasing the T/N ratio, i.e., the ratio of the 10B concentration in the tumour (10B(Tumour)) to that in the normal tissue (10B(Normal)), and by increasing 10B(Tumour) and 10B(Normal) at constant T/N ratio. It was found that the use of BDE becomes unnecessary from the viewpoint of increasing the TPD, when 10B(Tumour) is over a certain level which is decided by the conditions of the dose protocol. PMID:15715430

  5. Dose distributions in a human head phantom for neutron capture therapy using moderated neutrons from the 2.5 MeV proton-7Li reaction or from fission of 235U

    NASA Astrophysics Data System (ADS)

    Tanaka, Kenichi; Kobayashi, Tooru; Sakurai, Yoshinori; Nakagawa, Yoshinobu; Endo, Satoru; Hoshi, Masaharu

    2001-10-01

    The feasibility of neutron capture therapy (NCT) using an accelerator-based neutron source of the 7Li(p,n) reaction produced by 2.5 MeV protons was investigated by comparing the neutron beam tailored by both the Hiroshima University radiological research accelerator (HIRRAC) and the heavy water neutron irradiation facility in the Kyoto University reactor (KUR-HWNIF) from the viewpoint of the contamination dose ratios of the fast neutrons and the gamma rays. These contamination ratios to the boron dose were estimated in a water phantom of 20 cm diameter and 20 cm length to simulate a human head, with experiments by the same techniques for NCT in KUR-HWNIF and/or the simulation calculations by the Monte Carlo N-particle transport code system version 4B (MCNP-4B). It was found that the 7Li(p,n) neutrons produced by 2.5 MeV protons combined with 20, 25 or 30 cm thick D2O moderators of 20 cm diameter could make irradiation fields for NCT with depth-dose characteristics similar to those from the epithermal neutron beam at the KUR-HWNIF.

  6. Big-Bang Nucleosynthesis: lithium problems and scalar-tensor theories of gravity

    NASA Astrophysics Data System (ADS)

    Coc, Alain

    2006-07-01

    The observations of the anisotropies of the Cosmic Microwave Background (CMB) radiation, by the WMAP satellite, has provided a determination of the baryonic density of the Universe (Ωbh2) with an unprecedented precision. Using this value, the primordial abundances of the light elements can be calculated in the framework of the Standard Big-Bang Nucleosynthesis model (SBBN). While the agreement is excellent for D and good for 4He, there is a difference of a factor of ~3 for 7Li. In addition, in a few halo stars, 6Li has also been observed at a level well above SBBN predictions. To enable a more reliable calculation of these 7Li and 6Li yields, two nuclear reactions important for the nucleosynthesis of 7Li and 6Li have been studied experimentally: D(α, γ)6Li and 7Be(d,p)2α. Even though, the lithium primordial production is not well understood, BBN can be used to constrain theories beyond the standard model, for instance, scalar-tensor theories of gravity.

  7. Study of structure of nuclei with neutrons and nuclear data measurements for MFE. Progress report, September 1, 1979-August 31, 1980

    SciTech Connect

    Lane, R. O.

    1980-01-01

    Measurements of neutron differential elastic and inelastic scattering cross sections have been made for /sup 6/Li, /sup 7/Li, /sup 11/B and /sup 13/C. For /sup 7/Li + n, a multichannel R-matrix analysis has been completed, providing much new structure information for the compound /sup 8/Li system. These results are in very good agreement with recent theoretical model calculations, so that together the two provide considerable advancement in the state of our knowledge of /sup 8/Li. R-matrix analyses of /sup 11/B + n and /sup 13/C + n elastic scattering data have also been completed. For /sup 13/C + n theoretical model calculations have also been carried out and comparisons of these theoretical results with the R-matrix analysis are made. The triplet quadrupole spectrometer (TQS) is now fully operational. Development of new detectors, techniques, data analysis codes and theoretical model codes for use with the TQS system is complete. Measurements of (n,z) cross sections for fusion reactor structural materials e.g. /sup 58/Ni are currently underway. Construction of the long-flight-path tunnel for the swinger magnet facility has begun and development for this facility will continue in the coming year.

  8. Quadrupolar transients, cosine correlation functions, and two-dimensional exchange spectra of non-selectively excited spin-3/2 nuclei: A 7Li NMR study of the superionic conductor lithium indium phosphate

    NASA Astrophysics Data System (ADS)

    Storek, M.; Böhmer, R.

    2015-11-01

    Cos-cos stimulated echoes of non-selectively excited spin-3/2 nuclei were not exploited in studies of slow motional processes in solids and solid-like samples, so far. Based on a theoretical analysis of the quadrupolar transients which hitherto obviously precluded the application of such echoes, their utility is demonstrated for the example of 7Li NMR on the polycrystalline fast ion conductor lithium indium phosphate. Quadrupolar transients can adversely affect the shape of two- and three-pulse echo spectra and strategies are successfully tested that mitigate their impact. Furthermore, by means of suitably adapted cos-cos echo sequences an effective suppression of central-line contributions to the NMR spectra is achieved. By combining cos-cos and sin-sin datasets static two-dimensional exchange spectra were recorded that display quadrupolarly modulated off-diagonal intensity indicative of ionic motion.

  9. Electrochemical lithiation/delithiation of SnP2O7 observed by in situ XRD and ex situ(7)Li/(31)P NMR, and (119)Sn Mössbauer spectroscopy.

    PubMed

    Bezza, Ilham; Kaus, Maximilian; Riekehr, Lars; Pfaffmann, Lukas; Doyle, Stephen; Indris, Sylvio; Ehrenberg, Helmut; Solhy, Abderrahim; Saadoune, Ismael

    2016-04-21

    SnP2O7 was prepared by a sol-gel route. The structural changes of tin pyrophosphate during the electrochemical lithiation were followed by using in situ XRD measurements that reveal the existence of a crystalline phase at the beginning of the discharge process. Nevertheless, it becomes amorphous after the full discharge as a result of a conversion reaction leading to the formation of LixSny alloys. The electrochemical tests show a high capacity with high retention upon cycling. To better understand the reaction mechanism of SnP2O7 with Li, several techniques were applied, such as ex situ(119)Sn Mössbauer and ex situ(7)Li and (31)P NMR spectroscopies with which we can follow the changes in the local environment of each element during cycling. PMID:27029601

  10. Lithium glass scintillator neutron detector as an improved alternative to the standard 3 he proportional counter

    SciTech Connect

    Vladimir Popov, Pavel Degtiarenko

    2011-06-01

    Lithium glass scintillator made from 6Li-enriched substrate is a well known for its neutron detection capability. In spite of neutron interaction, cross section of 6Li happens to be lower than that of 3He. However, the neutron detection efficiency could be higher due to higher volume content of 6Li nuclear in the solid scintillator vs. gas filled proportional counter. At the same time, as lithium glass is sensitive to gamma and charge particle radiation, non-neutron radiation discrimination is required. Our detector is composed of two equal-size cylindrical Li(Ce) glass scintillators. The first one is high-sensitive to thermal neutrons GS-20 (6Li doped), the second one is GS-30 (7Li doped) type Scint-Gobain made lithium glass scintillator. Each of scintillators is coupled with R7400U Hamamatsu subminiature photomultiplier tube, and all assembly is fitted into NP100H 3He tube size. 6Li absorbs thermal neutrons releasing alpha particles and triton with 4.8 MeV total energy deposit inside the scintillator (equivalent to about ~1.3 MeV gamma energy depositions). Because 7Li isotope does not absorb thermal neutrons, and the physical properties of the two scintillators are virtually identical, the difference between these two scintillators could be used to provide neutron dose rate information. Results of study of neutron detector assembled of two Li(Ce) scintillators and NP100H moderator are presented

  11. Correlations between lithium local structure and electrochemistry of layered LiCo(1-2x)Ni(x)Mn(x)O2 oxides: 7Li MAS NMR and EPR studies.

    PubMed

    Stoyanova, Radostina; Ivanova, Svetlana; Zhecheva, Ekaterina; Samoson, Ago; Simova, Svetlana; Tzvetkova, Pavleta; Barra, Anne-Laure

    2014-02-14

    Advanced (7)Li MAS NMR technologies and high frequency EPR are combined to identify structural motifs and their relation to electrochemical properties of layered lithium-cobalt-nickel-manganese oxides LiCo1-2xNixMnxO2 (0 < x ≤ 0.5) used as cathode materials in lithium ion batteries. Structural-chemical shift regularities were established by systematic variation of the ratio of diamagnetic Co(3+) to paramagnetic Ni/Mn ions with variable valences. While EPR allows identifying the oxidation state of transition metal ions inside the layers, (7)Li NMR probes the local structure of Li with respect to transition metal ions located in two adjacent layers. For assignment of the lithium chemical shifts, we examine first magnetically diluted LiCo1-2xNixMnxO2 with x = 0.02, where paramagnetic ions are stabilized only in Mn(4+) and Ni(3+) form. Then the studies are extended towards the intermediate compositions with x = 0.10 and 0.33, containing simultaneously paramagnetic Mn(4+), Ni(3+) and Ni(2+) ions and diamagnetic Co(3+) ions. The benefit of using NMR with ultrafast spinning rates is demonstrated for the end composition LiNi0.5Mn0.5O2 having only paramagnetic Ni(2+) and Mn(2+) ions. The local structure of Li is quantified in respect of the number of Ni(2+) and Mn(4+) neighbors. It has been demonstrated that Ni(2+) and Mn(4+) are non-randomly distributed around Li and their distribution depends on the method of synthesis. The extent of local cationic order and its effect on the electrochemical properties of LiNi0.5Mn0.5O2 are discussed. PMID:24356075

  12. Explosive Nuclear Burning in the pp-Chain Region and the Breakout Processes

    NASA Astrophysics Data System (ADS)

    Kubono, S.; Yamaguchi, H.; Hayakawa, S.; Hou, S. Q.; He, J. J.

    2016-02-01

    The nuclear reactions in the pp-chain region and on the breakout process from the pp-chain region under very high temperature conditions are reviewed, and some possibilities for experimental investigation are discussed. The reactions discussed could play an important role typically for the primordial nucleosynthesis and supernova nucleosynthesis. Specifically, I discuss here the reactions starting from the two key nuclei, 7Be and 7Li. The 7Be(n,α) reaction, which destroys 7Be, is considered to have a large impact to the primordial 7Li problem. Our recent estimate of the reaction rate indicates that the reaction rate can be about one order of magnitude smaller than the rate currently adopted, suggesting this channel has a minor effect for the 7Li problem. Under a proton-rich environment at high temperature like the νp-process, the 7Be(α,γ)11C(α,p)14N pathway is expected to play a majpr role for heavy element synthesis, comparable to the triple alpha process. These two reactions on the pathway were investigated by using low-energy, high-intensity RI beams of 7Be and 11C. The results support the theoretical prediction of heavy nucleus production at around mass 90-100 by the νp-process, where the anomalously abundant p-nuclei exist. The reactions on the breakout sequence of 7Li(n,γ)8Li(α,n)11B are also discussed which could paly a crucial role in nuetron-rich envirnments, like in the primirdial universe as well as the early stage of the r-process. The cross sections of the first step reaction 7Li(n,γ)8Li seems well confirmed, but the second step reaction 8Li(α,n)11B still is not well known yet, whose status of the study is discussed.

  13. Theoretical nuclear physics

    SciTech Connect

    Kunz, P.D.

    1990-10-01

    This report contains small papers on the following topics: ground state correlations of nuclei in relativistic random phase approximation; instability of infinite nuclear matter in the relativistic hartree approximation; charge density differences for nuclei near {sup 208}Pb in relativistic models; meson exchange current corrections to magnetic moments in quantum hadro-dynamics; analysis of the O{sup +} {yields} O{sup {minus}} reaction at intermediate energies; contributions of reaction channels to the {sup 6}Li(p,{gamma}){sup 7}Be Reaction; deformed chiral nucleons; vacuum polarization in a finite system; second order processes in the (e,e{prime}d) reaction; sea contributions in Dirac RPA for finite nuclei; and momentum cutoffs in the sea.

  14. Report to the DOE Nuclear Data Committee, 1985

    SciTech Connect

    White, R.M.; Lanier, R.G.

    1985-02-01

    Progress is reported on the following measurements: the leakage multiplication from hollow beryllium spheres; /sup 6/Li and /sup 7/Li neutron-induced tritium production cross sections at 15 MeV; fast neutron fission yields; /sup 238/U(t,X) cross sections; neutron capture cross sections for /sup 86/ /sup 87/Sr at stellar temperatures; influence of realistic single particle spacings on precompound decay spectra; spontaneous fissions from a source of /sup 260/Md; and excitation functions from proton and deutron bombardment of natural Ti. Progress on the following calculations are reported: using modeled discrete levels; modeling level structures of odd-odd deformed nuclei; test of a phenomenological model of odd-odd deformed nuclei (an ARC study of /sup 176/Lu); absolute dipole gamma-ray strength functions for /sup 176/Lu; Gamow-Teller matrix elements for the /sup 11/B(p,n)/sup 11/C reaction at Ep = 26 MeV; K-distribution for neutron fission of /sup 232/Th; shell model study of the /sup 71/Ga(nu, anti e)/sup 71/Ge neutrino detector; and extension of microscopic models for neutron and proton scattering to inelastic scattering and charge-exchange reactions. Also, the status of the re-evaluation of the /sup 9/Be(n, 2n) reaction is given. (WHK)

  15. Search for rare nuclear decays with HPGe detectors at the STELLA facility of the LNGS

    SciTech Connect

    Belli, P.; Di Marco, A.; Bernabei, R.; D'Angelo, S.; Cappella, F.; D'Angelo, A.; Incicchitti, A.; Cerulli, R.; Di Vacri, M. L.; Laubenstein, M.; Nisi, S.; Danevich, F. A.; Kobychev, V. V.; Poda, D. V.; Tretyak, V. I.; Kovtun, G. P.; Kovtun, N. G.; Shcherban, A. P.; Solopikhin, D. A.; Polischuk, O. G.; and others

    2013-12-30

    Results on the search for rare nuclear decays with the ultra low background facility STELLA at the LNGS using gamma ray spectrometry are presented. In particular, the best T{sub 1/2} limits were obtained for double beta processes in {sup 96}Ru and {sup 104}Ru. Several isotopes, which potentially decay through different 2β channels, including also possible resonant double electron captures, were investigated for the first time ({sup 156}Dy, {sup 158}Dy, {sup 184}Os, {sup 192}Os, {sup 190}Pt, {sup 198}Pt). Search for resonant absorption of solar {sup 7}Li axions in a LiF crystal gave the best limit for the mass of {sup 7}Li axions (< 8.6 keV). Rare alpha decay of {sup 190}Pt to the first excited level of {sup 186}Os(E{sub exc} = 137.2keV) was observed for the first time.

  16. Difference between nuclear spin relaxation and ionic conductivity relaxation in superionic glasses

    NASA Astrophysics Data System (ADS)

    Ngai, K. L.

    1993-04-01

    Tatsumisago, Angell, and Martin [J. Chem. Phys. 97, 6968 (1992)] have compared conductivity relaxation data and 7Li nuclear spin lattice relaxation (SLR) data measured on a lithium chloroborate glass and found pronounced differences in the most probable relaxation times. The electrical conductivity relaxation (ECR) time, τ*σ, at some temperature occurs on a time scale shorter by some two orders of magnitude than the 7Li spin lattice relaxation correlation time, τ*s, and has a significantly lower activation energy. SLR and ECR monitor the motions of ions through different dynamic variables and correlation functions. Using this fact and the coupling model, I am able to explain quantitatively all aspects of the difference between SLR and ECR, and to establish relations between their different relaxation characteristics. The large difference between the observed activation energies of SLR and ECR alone should have implications on the validity of any proposed theory of the dynamics of ionic transport.

  17. PRODUCTION OF {sup 9}Be THROUGH THE {alpha}-FUSION REACTION OF METAL-POOR COSMIC RAYS AND STELLAR FLARES

    SciTech Connect

    Kusakabe, Motohiko; Kawasaki, Masahiro E-mail: kawasaki@icrr.u-tokyo.ac.jp

    2013-04-10

    Spectroscopic observations of metal-poor stars have indicated possible {sup 6}Li abundances that are much larger than the primordial abundance predicted in the standard big bang nucleosynthesis model. Possible mechanisms of {sup 6}Li production in metal-poor stars include pregalactic and cosmological cosmic-ray (CR) nucleosynthesis and nucleosynthesis by flare-accelerated nuclides. We study {sup 9}Be production via two-step {alpha}-fusion reactions of CR or flare-accelerated {sup 3,4}He through {sup 6}He and {sup 6,7}Li, in pregalactic structure, intergalactic medium, and stellar surfaces. We solve transfer equations of CR or flare particles and calculate nuclear yields of {sup 6}He, {sup 6,7}Li, and {sup 9}Be taking account of probabilities of processing {sup 6}He and {sup 6,7}Li into {sup 9}Be via fusions with {alpha} particles. Yield ratios, i.e., {sup 9}Be/{sup 6}Li, are then calculated for the CR and flare nucleosynthesis models. We suggest that the future observations of {sup 9}Be in metal-poor stars may find enhanced abundances originating from metal-poor CR or flare activities.

  18. Bound-state effects on light-element abundances in gravitino dark matter scenarios

    NASA Astrophysics Data System (ADS)

    Cyburt, Richard H.; Ellis, John; Fields, Brian D.; Olive, Keith A.; Spanos, Vassilis C.

    2006-11-01

    If the gravitino is the lightest supersymmetric particle and the long-lived next-to-lightest sparticle (NSP) is the stau, the charged partner of the tau lepton, it may be metastable and form bound states with several nuclei. These bound states may affect the cosmological abundances of 6Li and 7Li by enhancing nuclear rates that would otherwise be strongly suppressed. We consider the effects of these enhanced rates on the final abundances produced in Big-Bang nucleosynthesis (BBN), including injections of both electromagnetic and hadronic energy during and after BBN. We calculate the dominant two- and three-body decays of both neutralino and stau NSPs, and model the electromagnetic and hadronic decay products using the PYTHIA event generator and a cascade equation. Generically, the introduction of bound states drives light element abundances further from their observed values; however, for small regions of parameter space bound-state effects can bring lithium abundances in particular into better accord with observations. We show that in regions where the stau is the NSP with a lifetime longer than 103 104 s, the abundances of 6Li and 7Li are far in excess of those allowed by observations. For shorter lifetimes of order 1000 s, we comment on the possibility in minimal supersymmetric and supergravity models that stau decays could reduce the 7Li abundance from standard BBN values while at the same time enhancing the 6Li abundance.

  19. Cluster form factor calculation in the ab initio no-core shell model

    SciTech Connect

    Navratil, Petr

    2004-11-01

    We derive expressions for cluster overlap integrals or channel cluster form factors for ab initio no-core shell model (NCSM) wave functions. These are used to obtain the spectroscopic factors and can serve as a starting point for the description of low-energy nuclear reactions. We consider the composite system and the target nucleus to be described in the Slater determinant (SD) harmonic oscillator (HO) basis while the projectile eigenstate to be expanded in the Jacobi coordinate HO basis. This is the most practical case. The spurious center of mass components present in the SD bases are removed exactly. The calculated cluster overlap integrals are translationally invariant. As an illustration, we present results of cluster form factor calculations for <{sup 5}He vertical bar{sup 4}He+n>, <{sup 5}He vertical bar{sup 3}H+d>, <{sup 6}Li vertical bar{sup 4}He+d>, <{sup 6}Be vertical bar{sup 3}He+{sup 3}He>, <{sup 7}Li vertical bar{sup 4}He+{sup 3}H>, <{sup 7}Li vertical bar{sup 6}Li+n>, <{sup 8}Be vertical bar{sup 6}Li+d>, <{sup 8}Be vertical bar{sup 7}Li+p>, <{sup 9}Li vertical bar{sup 8}Li+n>, and <{sup 13}C vertical bar{sup 12}C+n>, with all the nuclei described by multi-({Dirac_h}/2{pi}){omega} NCSM wave functions.

  20. Indirect measurement of nuclear reactions of astrophysical interest

    SciTech Connect

    Liu, W. P.; Li, Z. H.; Bai, X. X.; Wang, Y. B.; Guo, B.; Lian, G.; Su, J.; Zeng, S.; Wang, B. X.; Yan, S. Q.; Li, Y. J.; Li, E. T.; Jin, S. J.

    2010-05-12

    Systematic indirect measurements of nuclear astrophysical reactions using the unstable ion beam facility GIRAFFE in CIAE were performed. We have measured the angular distributions of transfer reactions, such as {sup 8}Li(d,p){sup 9}Li, {sup 8}Li(d,n){sup 9}Be and {sup 8}Li(p,d){sup 7}Li in inverse kinematics, and derived the astrophysical S-factors or reaction rates for {sup 8}Li(n,gamma){sup 9}Li and {sup 8}Li(p,gamma){sup 9}Be by using asymptotic normalization coefficient (ANC) or spectroscopic factor methods.

  1. Characterization of moderator assembly dimension for accelerator boron neutron capture therapy of brain tumors using {sup 7}Li(p,n) neutrons at proton energy of 2.5 MeV

    SciTech Connect

    Tanaka, Kenichi; Kobayashi, Tooru; Bengua, Gerard; Nakagawa, Yoshinobu; Endo, Satoru; Hoshi, Masaharu

    2006-06-15

    The characteristics of moderator assembly dimension are investigated for the usage of {sup 7}Li(p,n) neutrons by 2.5 MeV protons in boron newtron capture therapy (BNCT) of brain tumors in the present study. The indexes checked are treatable protocol depth (TPD), which is the greatest depth of the region satisfying the dose requirements in BNCT protocol, proton current necessary to complete BNCT by 1 h irradiation, and the heat flux deposited in the Li target which should be removed. Assumed materials are D{sub 2}O for moderator, and mixture of polyethylene and LiF with 50 wt % for collimator. Dose distributions have been computed with MCNP 4B and 4C codes. Consequently, realized TPD does not show a monotonical tendency for the Li target diameter. However, the necessary proton current and heat flux in the Li target decreases as the Li target diameter increases, while this trend reverses at around 10 cm of the Li target diameter for the necessary proton current in the condition of this study. As to the moderator diameter, TPD does not exhibit an apparent dependence. On the other hand, necessary proton current and heat flux decrease as the moderator diameter increases, and this tendency saturates at around 60 cm of the moderator diameter in this study. As to the collimator, increase in inner diameter is suitable from the viewpoint of increasing TPD and decreasing necessary proton current and heat flux, while these indexes do not show apparent difference for collimator inner diameters over 14 cm for the parameters treated here. The practical viewpoint in selecting the parameters of moderator assembly dimension is to increase TPD, within the technically possible condition of accelerated proton current and heat removal from the Li target. In this process, the values for which the resultant characteristics mentioned above saturate or reverse would be important factors.

  2. Irradiation of nuclear track emulsions with thermal neutrons, heavy ions, and muons

    SciTech Connect

    Artemenkov, D. A. Bradnova, V.; Zaitsev, A. A.; Zarubin, P. I.; Zarubina, I. G.; Kattabekov, R. R.; Mamatkulov, K. Z.; Rusakova, V. V.

    2015-07-15

    Exposures of test samples of nuclear track emulsion were analyzed. Angular and energy correlations of products originating from the thermal-neutron-induced reaction n{sub th} +{sup 10} B → {sup 7} Li + (γ)+ α were studied in nuclear track emulsions enriched in boron. Nuclear track emulsions were also irradiated with {sup 86}Kr{sup +17} and {sup 124}Xe{sup +26} ions of energy about 1.2 MeV per nucleon. Measurements of ranges of heavy ions in nuclear track emulsionsmade it possible to determine their energies on the basis of the SRIM model. The formation of high-multiplicity nuclear stars was observed upon irradiating nuclear track emulsions with ultrarelativistic muons. Kinematical features studied in this exposure of nuclear track emulsions for events of the muon-induced splitting of carbon nuclei to three alpha particles are indicative of the nucleardiffraction interaction mechanism.

  3. Irradiation of nuclear track emulsions with thermal neutrons, heavy ions, and muons

    NASA Astrophysics Data System (ADS)

    Artemenkov, D. A.; Bradnova, V.; Zaitsev, A. A.; Zarubin, P. I.; Zarubina, I. G.; Kattabekov, R. R.; Mamatkulov, K. Z.; Rusakova, V. V.

    2015-07-01

    Exposures of test samples of nuclear track emulsion were analyzed. Angular and energy correlations of products originating from the thermal-neutron-induced reaction n th +10 B → 7 Li + (γ)+ α were studied in nuclear track emulsions enriched in boron. Nuclear track emulsions were also irradiated with 86Kr+17 and 124Xe+26 ions of energy about 1.2 MeV per nucleon. Measurements of ranges of heavy ions in nuclear track emulsionsmade it possible to determine their energies on the basis of the SRIM model. The formation of high-multiplicity nuclear stars was observed upon irradiating nuclear track emulsions with ultrarelativistic muons. Kinematical features studied in this exposure of nuclear track emulsions for events of the muon-induced splitting of carbon nuclei to three alpha particles are indicative of the nucleardiffraction interaction mechanism.

  4. Nuclear-Spin-Independent Short-Range Three-Body Physics in Ultracold Atoms

    SciTech Connect

    Gross, Noam; Shotan, Zav; Khaykovich, Lev; Kokkelmans, Servaas

    2010-09-03

    We investigate three-body recombination loss across a Feshbach resonance in a gas of ultracold {sup 7}Li atoms prepared in the absolute ground state and perform a comparison with previously reported results of a different nuclear-spin state [N. Gross et al., Phys. Rev. Lett. 103, 163202 (2009)]. We extend the previously reported universality in three-body recombination loss across a Feshbach resonance to the absolute ground state. We show that the positions and widths of recombination minima and Efimov resonances are identical for both states which indicates that the short-range physics is nuclear-spin independent.

  5. Low-energy nuclear reaction studies with RI beams in nuclear astrophysics

    NASA Astrophysics Data System (ADS)

    Kubono, S.; Teranishi, T.; Kato, S.

    2003-07-01

    After a brief discussion on the recent development in nuclear astrophysics, two reaction studies of typical astrophysical reactions at low energies where nuclear reactions play the main contributions to the nucleosynthesis in the universe, are discussed. One is the proton capture reaction, 11C(p, γ)12N, studied by the direct method using a 11C beam produced with a new low-energy RIB separator CRIB at CNS, Japan. The second one is the 13C(α, n)16O rearrangement reaction, which is believed to be the main neutron source for the s-process at low temperatures, investigated by an indirect method using the direct α-transfer reaction 13C(6Li, d)17O. Detailed investigations are suggested on the nuclear reactions relevant.

  6. Laser inertial fusion-based energy: Neutronic design aspects of a hybrid fusion-fission nuclear energy system

    NASA Astrophysics Data System (ADS)

    Kramer, Kevin James

    the same radial flibe flow that travels through perforated ODS walls to the reflector blanket. This reflector blanket is 75 cm thick comprised of 2 cm diameter graphite pebbles cooled by flibe. The flibe extraction plenum surrounds the reflector bed. Detailed neutronics designs studies are performed to arrive at the described design. The LFFH engine thermal power is controlled using a technique of adjusting the 6Li/7Li enrichment in the primary and secondary coolants. The enrichment adjusts system thermal power in the design by increasing tritium production while reducing fission. To perform the simulations and design of the LFFH engine, a new software program named LFFH Nuclear Control (LNC) was developed in C++ to extend the functionality of existing neutron transport and depletion software programs. Neutron transport calculations are performed with MCNP5. Depletion calculations are performed using Monteburns 2.0, which utilizes ORIGEN 2.0 and MCNP5 to perform a burnup calculation. LNC supports many design parameters and is capable of performing a full 3D system simulation from initial startup to full burnup. It is able to iteratively search for coolant 6Li enrichments and resulting material compositions that meet user defined performance criteria. LNC is utilized throughout this study for time dependent simulation of the LFFH engine. Two additional methods were developed to improve the computation efficiency of LNC calculations. These methods, termed adaptive time stepping and adaptive mesh refinement were incorporated into a separate stand alone C++ library name the Adaptive Burnup Library (ABL). The ABL allows for other client codes to call and utilize its functionality. Adaptive time stepping is useful for automatically maximizing the size of the depletion time step while maintaining a desired level of accuracy. Adaptive meshing allows for analysis of fixed fuel configurations that would normally require a computationally burdensome number of depletion zones

  7. Nuclear Clusters and Covalent Molecules on the femto-scale

    SciTech Connect

    Oertzen, Wolfram von

    2010-04-30

    Nuclear clusters like alpha-particles light N = Z nuclei are the building blocks of nuclear molecules. With additional 'valence' neutrons, which find there place in quantum mechanical two-center orbits a variety of covalently bound states in nuclei have been established in the last decade: in isotopes of {sup 9-12}Be, {sup 13-14}C and {sup 21}Ne. More recently we have studied molecular states in {sup 18,19,20}O-isotopes using the ({sup 7}Li,p) reaction on {sup 12,13,14}C targets at E{sub lab}({sup 7}Li) = 44 MeV. The systematics of the energies and cross sections show rotational bands with high moments of inertia. These are characteristic of large deformations or molecular structures where the clusters are well separated. Generally the large scale shell model calculations are unable to reproduce these cluster bands. With two clusters of different size (e.g. ({sup 14}C x {sup 4}He), or ({sup 16}O x {sup 4}He)) intrinsically reflection asymmetric shapes arise. The molecular structures appear as rotational bands split into parity inversion doublets.

  8. Nuclear weak interactions, supernova nucleosynthesis and neutrino oscillation

    NASA Astrophysics Data System (ADS)

    Kajino, Toshitaka

    2013-07-01

    We study the nuclear weak response in light-to-heavy mass nuclei and calculate neutrino-nucleus cross sections. We apply these cross sections to the explosive nucleosynthesis in core-collapse supernovae and find that several isotopes of rare elements 7Li, 11B, 138La, 180Ta and several others are predominantly produced by the neutrino-process nucleosynthesis. We discuss how to determine the suitable neutrino spectra of three different flavors and their anti-particles in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. Light-mass nuclei like 7Li and 11B, which are produced in outer He-layer, are strongly affected by the neutrino flavor oscillation due to the MSW (Mikheyev-Smirnov-Wolfenstein) effect, while heavy-mass nuclei like 138La, 180Ta and r-process elements, which are produced in the inner O-Ne-Mg layer or the atmosphere of proto-neutron star, are likely to be free from the MSW effect. Using such a different nature of the neutrino-process nucleosynthesis, we study the neutrino oscillation effects on their abundances, and propose a new novel method to determine the unknown neutrino oscillation parameters, θ13 and mass hierarchy, simultaneously. There is recent evidence that some SiC X grains from the Murchison meteorite may contain supernova-produced neutrino-process 11B and 7Li encapsulated in the grains. Combining the recent experimental constraints on θ13, we show that although the uncertainties are still large, our method hints at a marginal preference for an inverted neutrino mass hierarchy for the first time.

  9. Theoretical study of the elastic breakup of weakly bound nuclei at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Otomar, D. R.; Gomes, P. R. S.; Lubian, J.; Canto, L. F.; Hussein, M. S.

    2015-12-01

    We have performed continuum discretized coupled channel (CDCC) calculations for collisions of 7Li projectiles on 59Co,144Sm, and 208Pb targets at near-barrier energies, to assess the importance of the Coulomb and the nuclear couplings in the breakup of 7Li, as well as the Coulomb-nuclear interference. We have also investigated scaling laws, expressing the dependence of the cross sections on the charge and the mass of the target. This work is complementary to that previously reported by us on the breakup of 6Li. Here we explore the similarities and differences between the results for the two lithium isotopes. The relevance of the Coulomb dipole and quadrupole strengths at low energy for the two-cluster projectile is investigated in detail.

  10. Refined scenario of standard Big Bang nucleosynthesis allowing for nonthermal nuclear reactions in the primordial plasma

    SciTech Connect

    Voronchev, Victor T.; Nakao, Yasuyuki; Nakamura, Makoto; Tsukida, Kazuki

    2012-11-12

    The standard scenario of big bang nucleosynthesis (BBN) is generalized to take into account nonthermal nuclear reactions in the primordial plasma. These reactions are naturally triggered in the BBN epoch by fast particles generated in various exoergic processes. It is found that, although such particles can appreciably enhance the rates of some individual reactions, their influence on the whole process of element production is not significant. The nonthermal corrections to element abundances are obtained to be 0.1% ({sup 3}H), -0.03% ({sup 7}Li), and 0.34 %-0.63% (CNO group).

  11. Nuclear magnetic resonance study of sulfate reorientations in LiNaSO4.

    PubMed

    Shakhovoy, R A; Rakhmatullin, A; Deschamps, M; Sarou-Kanian, V; Bessada, C

    2016-05-01

    A nuclear magnetic resonance study of the sulfate ion reorientations in β-LiNaSO4 has been carried out. The influence of the SO4 reorientational jumps on the quadrupolar interactions of (7)Li nuclei was investigated by a jump reorientational model, which has not previously been applied to sulfates. The activation energy required for the SO4 reorientations was found to be 0.19 eV. It was also revealed that the SO4 reorientational disorder should be associated with a small anomaly of a heat capacity at around 600 K, which was previously observed experimentally. PMID:27028697

  12. Nuclear clusters studied with alpha resonant scatterings using RI beams at CRIB

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Kahl, D.; Nakao, T.; Wakabayashi, Y.; Hashimoto, T.; Hayakawa, S.; Kawabata, T.; Teranishi, T.; Kwon, Y. K.; Binh, D. N.; Khiem, L. H.; Duy, N. N.; Kubono, S.; Suhara, T.; Kanada-En'yo, Y.; Moon, J. Y.; Kim, A.; Iwasa, N.; Lee, P. S.; Chae, K. Y.; Cha, S. M.; Gwak, M. S.; Kim, D. H.; Milman, E.

    2014-12-01

    Alpha resonant scattering is a simple and promising method to study α-cluster structure in nuclei. It has several good features which enable us to perform measurements with short-lived and relatively low-intense RI beams. Several measurements on alpha resonant scattering have been carried out at CRIB (CNS Radioactive Ion Beam separator), which is a low-energy RI beam separator at Center for Nuclear Study (CNS) of the University of Tokyo. Recent α resonant scattering studies at CRIB, using 7Li, 7Be and 10Be beams with a helium gas target, are discussed.

  13. Nuclear magnetic resonance study of sulfate reorientations in LiNaSO4

    NASA Astrophysics Data System (ADS)

    Shakhovoy, R. A.; Rakhmatullin, A.; Deschamps, M.; Sarou-Kanian, V.; Bessada, C.

    2016-05-01

    A nuclear magnetic resonance study of the sulfate ion reorientations in β-LiNaSO4 has been carried out. The influence of the SO4 reorientational jumps on the quadrupolar interactions of 7Li nuclei was investigated by a jump reorientational model, which has not previously been applied to sulfates. The activation energy required for the SO4 reorientations was found to be 0.19 eV. It was also revealed that the SO4 reorientational disorder should be associated with a small anomaly of a heat capacity at around 600 K, which was previously observed experimentally.

  14. Light elements synthesized in the He-layer and the H-rich envelope of a type II supernova -- Influence of the adopted neutrino emission model

    NASA Astrophysics Data System (ADS)

    Yoshida, T.; Emori, H.; Nakazawa, K.

    2000-03-01

    In order to establish a suitable manner for finding presolar grains of supernova origin, we simulated the explosive nucleosynthesis of light elements, i.e., CNO-elements and X-elements (Li, Be, and B), in the He-layer and the H-rich envelope of a 16.2 M⊙ supernova and calculated their final abundances and abundance ratios using the nuclear reaction network. We also investigated the response of the synthesized abundances of light elements to the change of strength and duration of the neutrino emission, about which we have not a precise knowledge. The obtained results are as follows. The amounts of 6Li and 9Be produced during the supernova explosion are quite small. The ratios of 6Li/7Li and 9Be/7Li are less than 2 × 10-4, which are much smaller than the corresponding solar-system values. The other X-elements and CNO-elements (except 12C and 16O) are synthesized, more or less, and their abundances depend strongly on the internal mass coordinate as well as the adopted neutrino emission model. However, 11B/7Li ratio and isotopic ratios of CNO-elements are confined within one order of magnitude or so. On the basis of the above results, we finally proposed useful diagrams between two isotopic (elemental) ratios, which would help us to find presolar grains of supernova origin.

  15. Determination of 9Be(p,p0)9Be, 9Be(p,d0)8Be and 9Be(p,α0)6Li cross sections at 150° in the energy range 0.5-2.35 MeV

    NASA Astrophysics Data System (ADS)

    Catarino, N.; Barradas, N. P.; Alves, E.

    2016-03-01

    Beryllium and Tungsten have been chosen as the new "plasma facing materials" for fusion reactors. Understanding plasma wall interactions and their effects such as erosion and redeposition leading to the formation of alloys from the different materials present in the reactor chamber, is critical to model the retention of hydrogen isotopes by the wall materials. Determining the amount and the depth profile of Be and other elements deposited in the walls is a mandatory requirement in fusion reactors, making the knowledge of the relevant cross sections essential for IBA analysis. In this work we measured the 9Be(p,p0)9Be, 9Be(p,d0)8Be and 9Be(p,α0)6Li cross sections in the energy range 0.5-2.35 MeV, at an angle of 150°.

  16. Fabrication and electrochemical performance of 0.6Li2MnO3-0.4Li(Ni1/3Co1/3Mn1/3)O2 microspheres by two-step spray-drying process

    NASA Astrophysics Data System (ADS)

    Son, Mun Yeong; Lee, Jung-Kul; Kang, Yun Chan

    2014-08-01

    0.6Li2MnO3-0.4Li(Ni1/3Co1/3Mn1/3)O2 composite microspheres with dense structures are prepared by a two-step spray-drying process. Precursor powders with hollow and porous structures prepared by the spray-drying process are post-treated at a low temperature of 400°C and then wet-milled to obtain a slurry with high stability. The slurry of the mixture of metal oxides is spray-dried to prepare precursor aggregate powders several microns in size. Post-treatment of these powders at high temperatures (>700°C) produces 0.6Li2MnO3-0.4Li(Ni1/3Co1/3Mn1/3)O2 composite microspheres with dense structures and high crystallinity. The mean size and geometric standard deviation of the composite microspheres post-treated at 900°C are 4 μm and 1.38, respectively. Further, the initial charge capacities of the aggregated microspheres post-treated at 700, 800, 900, and 1000°C are 336, 349, 383, and 128 mA h g-1, respectively, and the corresponding discharge capacities are 286, 280, 302, and 77 mA h g-1, respectively. The discharge capacity of the composite microspheres post-treated at an optimum temperature of 900°C after 100 cycles is 242 mA h g-1, and the corresponding capacity retention is 80%.

  17. Fabrication and electrochemical performance of 0.6Li2MnO3-0.4Li(Ni1/3Co1/3Mn1/3)O2 microspheres by two-step spray-drying process

    PubMed Central

    Son, Mun Yeong; Lee, Jung-Kul; Kang, Yun Chan

    2014-01-01

    0.6Li2MnO3–0.4Li(Ni1/3Co1/3Mn1/3)O2 composite microspheres with dense structures are prepared by a two-step spray-drying process. Precursor powders with hollow and porous structures prepared by the spray-drying process are post-treated at a low temperature of 400°C and then wet-milled to obtain a slurry with high stability. The slurry of the mixture of metal oxides is spray-dried to prepare precursor aggregate powders several microns in size. Post-treatment of these powders at high temperatures (>700°C) produces 0.6Li2MnO3–0.4Li(Ni1/3Co1/3Mn1/3)O2 composite microspheres with dense structures and high crystallinity. The mean size and geometric standard deviation of the composite microspheres post-treated at 900°C are 4 μm and 1.38, respectively. Further, the initial charge capacities of the aggregated microspheres post-treated at 700, 800, 900, and 1000°C are 336, 349, 383, and 128 mA h g−1, respectively, and the corresponding discharge capacities are 286, 280, 302, and 77 mA h g−1, respectively. The discharge capacity of the composite microspheres post-treated at an optimum temperature of 900°C after 100 cycles is 242 mA h g−1, and the corresponding capacity retention is 80%. PMID:25168912

  18. Magnetic-field effects in transitions of X Li molecules (X: even isotopes of group II atoms)

    SciTech Connect

    Gopakumar, Geetha; Abe, Minori; Hada, Masahiko; Kajita, Masatoshi

    2011-10-15

    We analyze the Zeeman shift in the (v,N)=(0,0){yields}(1,0) transition frequency of X Li molecules (X: even isotopes of group II atoms), which is of interest in metrology. The Zeeman shift in the transition frequency between stretching states is found to be less than 1 mHz with a magnetic field of 1 G. X {sup 6}Li molecules are more advantageous than X {sup 7}Li molecules for measuring the transition frequency without the Zeeman shift because of the smaller g factor of the Li nuclear spin.

  19. Recent Advances in Nuclear Reaction Theories for Weakly Bound Nuclei: Reexamining the Problem of Inclusive Breakup

    NASA Astrophysics Data System (ADS)

    Moro, Antonio M.; Lei, Jin

    2016-05-01

    The problem of the calculation of inclusive breakup cross sections in nuclear reactions is reexamined. For that purpose, the theory proposed by Ichimura et al. (Phys Rev C 32:431, 1985) is revisited, both in its prior and post representations. We briefly outline the connection of this theory with that proposed by Udagawa and Tamura (Phys Rev C 24:1348, 1981) and apply both theories to the inclusive breakup of ^6Li on ^{209}Bi at near-barrier energies, comparing also with available data. The relative importance of elastic versus non-elastic breakup, as a function of the incident energy and of the projectile separation energy, is also investigated.

  20. Structure of {sup 7}He by proton removal from {sup 8}Li with the (d,{sup 3}He) reaction.

    SciTech Connect

    Wuosmaa, A. H.; Schiffer, J. P.; Rehm, K. E.; Greene, J. P.; Henderson, D. J.; Janssens, R. V. F.; Jiang, C. L.; Jisonna, L.; Lighthall, J. C.; Marley, S. T.; Moore, E. F.; Pardo, R. C.; Patel, N.; Paul, M.; Peterson, D.; Pieper, S. C.; Savard, G.; Segel, R. E.; Siemssen, R. H.; Tang, X. D.; Wiringa, R. B.; Physics; Western Michigan Univ.; Northwestern Univ.; Colorado School of Mines; Hebrew Univ.; Kernfysich Versneller Inst.

    2008-01-01

    We report on a study of the structure of the unbound nucleus {sup 7}He utilizing the proton-removal reaction {sup 2}H({sup 8}Li,{sup 3}He){sup 7}He. Combining the present results with those of our prior measurements of the neutron-adding reaction {sup 2}H({sup 6}He,p){sup 7}He, a consistent picture emerges for the low-lying excitations in {sup 7}He. Specifically, the negative-parity sequence of resonances, in order of excitation energies, is consistent with 3/2{sup -},1/2{sup -}, and 5/2{sup -}. The stable-beam reactions {sup 2}H({sup 7}Li,t){sup 6}Li and {sup 2}H({sup 7}Li,{sup 3}He){sup 6}He were also measured. The results are compared with the predictions of nuclear structure models, including those of ab initio quantum Monte Carlo calculations.

  1. Structure of {sup 7}He by proton removal from {sup 8}Li with the (dm {sup 3}He) reaction.

    SciTech Connect

    Wuosmaa, A. H.; Schiffer, J. P.; Rehm, K. E.; Greene, J. P.; Henderson, D. J.; Janssens, R. V. F.; Jiang, C. L.; Jisonna, L.; Lighthall, J. C.; Marley, S. T.; Moore, E. F.; Pardo, R. C.; Patel, N.; Paul, M.; Peterson, D.; Pieper, S. C.; Savard, G.; Segel, R. E.; Siemssen, R. H.; Tang, X. D.; Wiringa, R. B.; Physics; Western Michigan Univ.; Northwestern Univ.; Colorado School of Mines; Hebrew Univ.; KVI Groningen

    2008-01-01

    We report on a study of the structure of the unbound nucleus {sup 7}He utilizing the proton-removal reaction {sup 2}H({sup 8}Li,{sup 3}He){sup 7}He. Combining the present results with those of our prior measurements of the neutron-adding reaction {sup 2}H({sup 6}He,p){sup 7}He, a consistent picture emerges for the low-lying excitations in {sup 7}He. Specifically, the negative-parity sequence of resonances, in order of excitation energies, is consistent with 3/2{sup -},1/2{sup -}, and 5/2{sup -}. The stable-beam reactions {sup 2}H({sup 7}Li,t){sup 6}Li and {sup 2}H({sup 7}Li,{sup 3}He){sup 6}He were also measured. The results are compared with the predictions of nuclear structure models, including those of ab initio quantum Monte Carlo calculations.

  2. Structure of {sup 7}He by proton removal from {sup 8}Li with the (d,{sup 3}He) reaction

    SciTech Connect

    Wuosmaa, A. H.; Lighthall, J. C.; Marley, S. T.; Schiffer, J. P.; Rehm, K. E.; Greene, J. P.; Henderson, D. J.; Janssens, R. V. F.; Jiang, C. L.; Moore, E. F.; Pardo, R. C.; Peterson, D.; Pieper, Steven C.; Savard, G.; Tang, X. D.; Wiringa, R. B.; Jisonna, L.; Segel, R. E.; Patel, N.; Paul, M.

    2008-10-15

    We report on a study of the structure of the unbound nucleus {sup 7}He utilizing the proton-removal reaction {sup 2}H({sup 8}Li,{sup 3}He){sup 7}He. Combining the present results with those of our prior measurements of the neutron-adding reaction {sup 2}H({sup 6}He,p){sup 7}He, a consistent picture emerges for the low-lying excitations in {sup 7}He. Specifically, the negative-parity sequence of resonances, in order of excitation energies, is consistent with 3/2{sup -},1/2{sup -}, and 5/2{sup -}. The stable-beam reactions {sup 2}H({sup 7}Li,t){sup 6}Li and {sup 2}H({sup 7}Li,{sup 3}He){sup 6}He were also measured. The results are compared with the predictions of nuclear structure models, including those of ab initio quantum Monte Carlo calculations.

  3. Determination of lithium isotopes at natural abundance levels by atomic absorption spectrometry

    USGS Publications Warehouse

    Meier, A.L.

    1982-01-01

    The relationships of the absorption of 6Li and 7Li hollow cathode lamp emissions are used to determine lithium isotopic composition in the natural abundance range of geologic materials. Absorption was found to have a nonlinear dependence upon total lithium concentration and isotopic composition. A method using nonlinear equations to describe the relationship of the absorption of 6Li and 7Li lamp radiation is proposed as a means of calculating isotopic composition that is independent of total lithium concentration.

  4. New results on catalyzed big bang nucleosynthesis with a long-lived negatively charged massive particle

    SciTech Connect

    Kusakabe, Motohiko; Kajino, Toshitaka; Yoshida, Takashi; Mathews, Grant J.

    2010-04-15

    It has been proposed that the apparent discrepancies between the inferred primordial abundances of {sup 6}Li and {sup 7}Li and the predictions of big bang nucleosynthesis (BBN) can be resolved by the existence of a negatively charged massive unstable supersymmetric particle (X{sup -}) during the BBN epoch. Here, we present new BBN calculations with an X{sup -} particle utilizing an improved nuclear reaction network including captures of nuclei by the particle, nuclear reactions and {beta} decays of normal nuclei and nuclei bound to the X{sup -} particles (X nuclei), and new reaction rates derived from recent rigorous quantum many-body dynamical calculations. We find that this is still a viable model to explain the observed {sup 6}Li and {sup 7}Li abundances. We also show that with the new rates the production of heavier nuclei is suppressed and there is no signature on abundances of nuclei heavier than Be in the X{sup -}-particle catalyzed BBN model as has been previously proposed. We also consider the version of this model whereby the X{sup -} particle decays into the present cold dark matter. We analyze this paradigm in light of the recent constraints on the dark-matter mass deduced from the possible detected events in the CDMS-II experiment. We conclude that based upon the inferred range for the dark-matter mass, only X{sup -} decay via the weak interaction can achieve the desired {sup 7}Li destruction while also reproducing the observed {sup 6}Li abundance.

  5. Trojan horse particle invariance: The impact on nuclear astrophysics

    NASA Astrophysics Data System (ADS)

    Pizzone, R. G.; Spitaleri, C.; Bertulani, C. A.; Mukhamedzhanov, A. M.; Blokhintsev, L. D.; La Cognata, M.; Lamia, L.; Spartá, R.; Tumino, A.

    2014-05-01

    In the current picture of nuclear astrophysics indirect methods and, in particular, the Trojan Horse Method cover a crucial role for the measurement of charged particle induced reactions cross sections of astrophysical interest, in the energy range required by the astrophysical scenarios. To better understand its cornerstones and its applications to physical cases many tests were performed to verify all its properties and the possible future perspectives. The key to the method is the quasi-free break-up and some of its properties will be investigated in the present work. In particular, the Trojan Horse nucleus invariance will be studied and previous studies will be extended to the cases of the binary d(d, p)t and 6Li(d,α)4He reactions, which were tested using different quasi-free break-up's, namely 6Li and 3He. The astrophysical S(E)-factor were then extracted with the Trojan Horse formalism applied to the two different break-up schemes and compared with direct data as well as with previous indirect investigations. The very good agreement confirms the independence of binary indirect cross section on the chosen spectator particle also for these reactions.

  6. Colorado School of Mines low energy nuclear physics project

    SciTech Connect

    Cecil, F.E.

    1991-01-02

    A major accomplishment of this project in the past year is the completion of a fairly comprehensive paper describing the survey of radiative capture reactions of protons on light nuclei at low energies. In addition we have completed a preliminary set of measurements of (d,p)/(d,{alpha}) cross section ratios on the charge symmetric nuclei {sup 6}Li and {sup 10}B as a test of the Oppenheimer-Phillips effect. While the {sup 6}Li data remain inconclusive, the {sup 10}B data show solid evidence for the Oppenheimer-Phillips enhancement of the (d,p) reaction relative to the (d,{alpha}) reaction for deuteron bombarding energies below about 100 keV. We have continued our investigation of fusion reaction products from deuterium-metal systems at room temperatures with the startling observation of intense burst of energetic charged particles from deuterium gas loaded thin titaium foils subject to non-equilibrium thermal and electrical conditions. We have completed two projects involving the application of the low energy particle accelerator to material science problems; firstly a study of the transformation of crystalline to amorphous Fe-Zr systems by proton irradiation and secondly the effects of ion bombardment on the critical temperature of YBCO high-temperature superconductors. Finally we have made progress in several instrumentation projects which will be used in some of the up-coming measurements of nuclear cross sections at very low energies.

  7. Trojan horse particle invariance: The impact on nuclear astrophysics

    SciTech Connect

    Pizzone, R. G.; La Cognata, M.; Spitaleri, C.; Bertulani, C. A.; Mukhamedzhanov, A. M.; Blokhintsev, L. D.; Lamia, L.; Spartá, R.; Tumino, A.

    2014-05-02

    In the current picture of nuclear astrophysics indirect methods and, in particular, the Trojan Horse Method cover a crucial role for the measurement of charged particle induced reactions cross sections of astrophysical interest, in the energy range required by the astrophysical scenarios. To better understand its cornerstones and its applications to physical cases many tests were performed to verify all its properties and the possible future perspectives. The key to the method is the quasi-free break-up and some of its properties will be investigated in the present work. In particular, the Trojan Horse nucleus invariance will be studied and previous studies will be extended to the cases of the binary d(d, p)t and {sup 6}Li(d,α){sup 4}He reactions, which were tested using different quasi-free break-up's, namely {sup 6}Li and {sup 3}He. The astrophysical S(E)-factor were then extracted with the Trojan Horse formalism applied to the two different break-up schemes and compared with direct data as well as with previous indirect investigations. The very good agreement confirms the independence of binary indirect cross section on the chosen spectator particle also for these reactions.

  8. Hyperfiltration-induced fractionation of lithium isotopes in geologic systems. Progress report, April 1, 1991--December 1, 1991

    SciTech Connect

    Fritz, S.J.

    1992-01-01

    Effective modeling of hyperfiltration-induced fractionation of lithium isotopes is hindered by a lack of data on aqueous diffusion coefficients of {sup 6}Li{sup +} and {sup 7}Li{sup +}. Several experiments were conducted this past year on yielded a value for the ratio of diffusion coefficients between {sup D6}Li+Cl{minus}/{sup D7}Li+Cl{minus}. A 0.9450 M LiCl solution was placed within sealed dialysis tubing and osmoted against a kilogram of deionized water at 22C. Osmotic equilibrium occurred at 143 minutes, and the ratio of {omega}{sup 6}Li{sup +}Cl{minus}/{omega}{sup 7}Li+Cl{minus} was measured to be 1.011. Because this experimental value is close to the square root of the mass ratio between {sup 7}LiCl and {sup 6}LiCl (1.012), Graham`s Law may be a convenient way to calculate such ratios for aqueous diffusion coefficients of individual isotopic components. In evolution of this closed-system osmotic cell as a function of time, Li isotopic ratios of beaker and bag solutions exhibit a minimum and a maximum before the {sup 6}Li/{sup 7}Li ratios of both solutions assume the inevitable asymptotic approach toward isotopic equilibrium. Max difference in {sup 6}Li/{sup 7}Li ratio between beaker and bag solution was 0.00156 {plus_minus} 0.00015.

  9. Passive sensor systems for nuclear material monitoring

    SciTech Connect

    Simpson, M.L.; Boatner, L.A.; Holcomb, D.E.; McElhaney, S.A.; Mihalczo, J.T.; Muhs, J.D.; Roberts, M.R.; Hill, N.W.

    1993-09-01

    Passive fiber optic sensor systems capable of confirming the presence of special nuclear materials in storage or process facilities are being developed at Oak Ridge National Laboratory (ORNL). These sensors provide completely passive, remote measurement capability. No power supplies, amplifiers, or other active components that could degrade system reliability are required at the sensor location. ORNL, through its research programs in scintillator materials, has developed a variety of materials for use in alpha-, beta-, gamma-, and neutron-sensitive scintillator detectors. In addition to sensors for measuring radiation flux, new sensor materials have been developed which are capable of measuring weight, temperature, and source location. An example of a passive sensor for temperature measurement is the combination of a thermophosphor (e.g., rare-earth activated Y{sub 2}O{sub 3}) with {sup 6}LiF (95% {sup 6}Li). This combination results in a new class of scintillators for thermal neutrons that absorb energy from the radiation particles and remit the energy as a light pulse, the decay rate of which, over a specified temperature range, is temperature dependent. Other passive sensors being developed include pressure-sensitive triboluminescent materials, weight-sensitive silicone rubber fibers, scintillating fibers, and other materials for gamma and neutron detection. The light from the scintillator materials of each sensor would be sent through optical fibers to a monitoring station, where the attribute quantity could be measured and compared with previously recorded emission levels. Confirmatory measurement applications of these technologies are being evaluated to reduce the effort, costs, and employee exposures associated with inventorying stockpiles of highly enriched uranium at the Oak Ridge Y-12 Plant.

  10. Nuclear reaction uncertainties, massive gravitino decays and the cosmological lithium problem

    SciTech Connect

    Cyburt, Richard H.; Ellis, John; Fields, Brian D.; Luo, Feng; Olive, Keith A.; Spanos, Vassilis C. E-mail: john.ellis@cern.ch E-mail: fluo@physics.umn.edu E-mail: spanos@physics.umn.edu

    2010-10-01

    We consider the effects of uncertainties in nuclear reaction rates on the cosmological constraints on the decays of unstable particles during or after Big-Bang nucleosynthesis (BBN). We identify the nuclear reactions due to non-thermal hadrons that are the most important in perturbing standard BBN, then quantify the uncertainties in these reactions and in the resulting light-element abundances. These results also indicate the key nuclear processes for which improved cross section data would allow different light-element abundances to be determined more accurately, thereby making possible more precise probes of BBN and evaluations of the cosmological constraints on unstable particles. Applying this analysis to models with unstable gravitinos decaying into neutralinos, we calculate the likelihood function for the light-element abundances measured currently, taking into account the current experimental errors in the determinations of the relevant nuclear reaction rates. We find a region of the gravitino mass and abundance in which the abundances of deuterium, {sup 4}He and {sup 7}Li may be fit with χ{sup 2} = 5.5, compared with χ{sup 2} = 31.7 if the effects of gravitino decays are unimportant. The best-fit solution is improved to χ{sup 2} ∼ 2.0 when the lithium abundance is taken from globular cluster data. Some such re-evaluation of the observed light-element abundances and/or nuclear reaction rates would be needed if this region of gravitino parameters is to provide a complete solution to the cosmological {sup 7}Li problem.

  11. R-matrix Analysis of Reactions in the {sup 9}B Compound System

    SciTech Connect

    Paris, M. Hale, G.; Hayes-Sterbenz, A.; Jungman, G.

    2014-06-15

    Recent activity in solving the ‘lithium problem’ in big bang nucleosynthesis has focused on the role that putative resonances may play in resonance-enhanced destruction of {sup 7}Li. Particular attention has been paid to the reactions involving the {sup 9}B compound nuclear system, d+{sup 7}Be→{sup 9}B. These reactions are analyzed via the multichannel, two-body unitary R-matrix method using the code EDA developed by Hale and collaborators. We employ much of the known elastic and reaction data, in a four-channel treatment. The data include elastic {sup 3}He+{sup 6}Li differential cross sections from 0.7 to 2.0 MeV, integrated reaction cross sections for energies from 0.7 to 5.0 MeV for {sup 6}Li({sup 3}He,p){sup 8}Be{sup *} and from 0.4 to 5.0 MeV for the {sup 6}Li({sup 3}He,d){sup 7}Be reaction. Capture data have been added to an earlier analysis with integrated cross section measurements from 0.7 to 0.825 MeV for {sup 6}Li({sup 3}He,γ){sup 9}B. The resulting resonance parameters are compared with tabulated values, and previously unidentified resonances are noted. Our results show that there are no near d+{sup 7}Be threshold resonances with widths that are 10's of keV and reduce the likelihood that a resonance-enhanced mass-7 destruction mechanism, as suggested in recently published work, can explain the {sup 7}Li problem.

  12. R-matrix Analysis of Reactions in the 9B Compound System

    NASA Astrophysics Data System (ADS)

    Paris, M.; Hale, G.; Hayes-Sterbenz, A.; Jungman, G.

    2014-06-01

    Recent activity in solving the 'lithium problem' in big bang nucleosynthesis has focused on the role that putative resonances may play in resonance-enhanced destruction of 7Li. Particular attention has been paid to the reactions involving the 9B compound nuclear system, d+7Be→9B. These reactions are analyzed via the multichannel, two-body unitary R-matrix method using the code EDA developed by Hale and collaborators. We employ much of the known elastic and reaction data, in a four-channel treatment. The data include elastic 3He+6Li differential cross sections from 0.7 to 2.0 MeV, integrated reaction cross sections for energies from 0.7 to 5.0 MeV for 6Li(3He,p)8Be* and from 0.4 to 5.0 MeV for the 6Li(3He,d)7Be reaction. Capture data have been added to an earlier analysis with integrated cross section measurements from 0.7 to 0.825 MeV for 6Li(3He,γ)9B. The resulting resonance parameters are compared with tabulated values, and previously unidentified resonances are noted. Our results show that there are no near d+7Be threshold resonances with widths that are 10's of keV and reduce the likelihood that a resonance-enhanced mass-7 destruction mechanism, as suggested in recently published work, can explain the 7Li problem.

  13. Roles of Nuclear Weak Processes in Stars

    NASA Astrophysics Data System (ADS)

    Suzuki, Toshio; Kajino, Toshitaka; Honma, Michio; Toki, Hiroshi; Nomoto, Ken'ichi

    2015-11-01

    The roles of nuclear weak processes in stars are discussed. Neutrino-nucleus reactions on 12C, 56Fe and 40Ar are studied with new shell-model Hamiltonians. New cross sections, which give good account of experimental data, are applied to nucleosynthesis of light elements in supernova explosions. Effects of ν-oscillations are investigated, and the abundance ratio of 7Li/11B is pointed out to be sensitive to the ν mass hierarchy. Then, e-capture and β-decay rates in sd-shell nuclei are evaluated at stellar environments, and applied to study cooling of O-Ne-Mg core stars by nuclear URCA processes. The fate of 8-10 M❿ stars is sensitive to the cooling of the core. Finally, β-decay half-lives of r-process waiting-point nuclei with N=126 are evaluated by shell-model calculations taking into account both the Gamow-Teller and first-forbidden transitions. The half-lives obtained are short compared with standard FRDM values.

  14. Nuclear Medicine

    MedlinePlus

    ... Parents/Teachers Resource Links for Students Glossary Nuclear Medicine What is nuclear medicine? What are radioactive tracers? ... funded researchers advancing nuclear medicine? What is nuclear medicine? Nuclear medicine is a medical specialty that uses ...

  15. The Amblygonite (LiAlPO{sub 4}F)-Montebrasite (LiAlPO{sub 4}OH) Solid Solution: A Combined powder and single-crystal neutron diffraction and solid-state {sup 6}Li MAS, CP MAS, and REDOR NMR study

    SciTech Connect

    Groat, Lee A.; Chakoumakos, Bryan C.; Brouwer, Darren H.; Hoffman, Christina M.; Fyfe, Colin A.; Morell, Heiko; Schultz, Arthur J.

    2003-01-01

    The amblygonite-montebrasite series of minerals, common constituents of granitic pegmatites and topaz-bearing granites, show complete solid solution with ideal composition LiAlPO{sub 4}(F, OH). These compounds are ideal for studying F {leftrightarrow} OH solid solution in minerals because natural members of the series generally show little deviation from the ideal composition. In this study, we used powder and single-crystal neutron diffraction and solid-state {sup 6}Li MAS, CP MAS, and REDOR NMR techniques to study the effect of F {leftrightarrow} OH substitution on the series. Lattice parameters refined from single-crystal neutron diffraction data show increasing b and decreasing a, c, and V with increasing F/(F + OH). The volume is highest for the OH end-member because of the presence of an additional atom (H). The a and c parameters decrease with increasing F/(F + OH) because the O-H vector is close to the a-c plane and the Al-OH/F vectors are approximately parallel to c. Lattice parameters refined from neutron powder diffraction patterns collected at lower T show that thermal contraction increases with F/(F + OH), presumably because the F anion takes up less space than the OH molecule. The results show that the OH/F position is always fully occupied. The H displacement ellipsoid shows little change with occupancy, which obviously corresponds negatively with increasing F/(F + OH). However, the Li displacement ellipsoid becomes extremely large and anisotropic with increasing F fraction. Most of the distortion is associated with the U{sub 3} eigenvalue, which lies between the c and c* directions. U{sub eq} values corresponding to the Li atom show a greater reduction with decreasing temperature than the other atoms. The temperature dependence of Li is the same regardless of F content. Even when extrapolated to absolute zero the Li displacement ellipsoid is very large, which implies a large static disorder.

  16. Mixtures of Charged Bosons Confined in Harmonic Traps and Bose-Einstein Condensation Mechanism for Low-Energy Nuclear Reactions and Transmutation Processes in Condensed Matters

    NASA Astrophysics Data System (ADS)

    Kim, Yeong E.; Zubarev, Alexander L.

    2006-02-01

    A mixture of two different species of positively charged bosons in harmonic traps is considered in the mean-field approximation. It is shown that depending on the ratio of parameters, the two components may coexist in same regions of space, in spite of the Coulomb repulsion between the two species. Application of this result is discussed for the generalization of the Bose-Einstein condensation mechanism for low-energy nuclear reaction (LENR) and transmutation processes in condensed matters. For the case of deutron-lithium (d + Li) LENR, the result indicates that (d + 6Li) reactions may dominate over (d + d) reactions in LENR experiments.

  17. Transverse Isotropy: Disappearance of Mott oscillations in sub-barrier elastic scattering of identical heavy ions and the nuclear ineraction

    NASA Astrophysics Data System (ADS)

    Hussein, Mahir; Canto, L. Felipe; Donangelo, Raul

    2015-04-01

    It is found that at a certain critical value of the Sommerfeld parameter the Mott oscillations usually present in the scattering of identical heavy ions, disappear and the cross section becomes quite flat. We call this effect Transverse Isotropy (TI) (L. F. Canto, R. Donangelo and M. S. Hussein, Mod. Phys. Lett. A, 16), 1027 (2001). The critical value of the Sommerfeld parameter at which TI sets in is found to be ηc =√{ 3 s + 2 } , where s is the spin of the nuclei participating in the scattering. No TI is found in the Mott scattering of identical Fermionic nuclei. The critical center of mass energy corresponding to ηc is found to be Ec = 0.40 MeV for α + α (s = 0), and 1.2 MeV for 6 Li + 6 LI (s = 1). We further found that the inclusion of the nuclear interaction induces a significant modification in the TI. This can be verified by calculating the second derivative of the cross section at θ =90° . We suggest measurements at these sub-barrier energies for the purpose of extracting useful information about the nuclear interaction between light heavy ions. Supported by CNPq, FAPESP, FAPERJ, CAPES/ITA.

  18. TENDL-2011: TALYS-based Evaluated Nuclear Data Library

    SciTech Connect

    Rochman, D.; Koning, A. J.

    2012-07-01

    The 4. release of the TENDL library, TENDL-2011 (TALYS-based Evaluated Nuclear Data Library) is described. This library consists of a complete set of nuclear reaction data for incident neutrons, photons, protons, deuterons, tritons, helions and alpha particles, from 10-5 eV up to 200 MeV, for all isotopes from {sup 6}Li to {sup 281}Ds that are either stable of have a half-life longer than 1 second. All data are completely and consistently evaluated using a software system consisting of the TALYS-1.2 nuclear reaction code, and other programs to handle resonance data, experimental data, data from existing evaluations, and to provide the final ENDF-6 formatting. The result is a nuclear data library with mutually consistent reaction information for all isotopes and a quality that increases with yearly updates. To produce this library, TALYS input parameters are adjusted for many nuclides so that calculated cross sections agree with experimental data, while for important nuclides experimental data are directly included. All information is available on www.talys.eu and www.talys.eu/TENDL-2011. (authors)

  19. Above-ground antineutrino detection for nuclear reactor monitoring

    NASA Astrophysics Data System (ADS)

    Sweany, M.; Brennan, J.; Cabrera-Palmer, B.; Kiff, S.; Reyna, D.; Throckmorton, D.

    2015-01-01

    Antineutrino monitoring of nuclear reactors has been demonstrated many times (Klimov et al., 1994 [1]; Bowden et al., 2009 [2]; Oguri et al., 2014 [3]), however the technique has not as of yet been developed into a useful capability for treaty verification purposes. The most notable drawback is the current requirement that detectors be deployed underground, with at least several meters-water-equivalent of shielding from cosmic radiation. In addition, the deployment of liquid-based detection media presents a challenge in reactor facilities. We are currently developing a detector system that has the potential to operate above ground and circumvent deployment problems associated with a liquid detection media: the system is composed of segments of plastic scintillator surrounded by 6LiF/ZnS:Ag. ZnS:Ag is a radio-luminescent phosphor used to detect the neutron capture products of 6Li. Because of its long decay time compared to standard plastic scintillators, pulse-shape discrimination can be used to distinguish positron and neutron interactions resulting from the inverse beta decay (IBD) of antineutrinos within the detector volume, reducing both accidental and correlated backgrounds. Segmentation further reduces backgrounds by identifying the positron's annihilation gammas, a signature that is absent for most correlated and uncorrelated backgrounds. This work explores different configurations in order to maximize the size of the detector segments without reducing the intrinsic neutron detection efficiency. We believe that this technology will ultimately be applicable to potential safeguards scenarios such as those recently described by Huber et al. (2014) [4,5].

  20. Boundaries for martensitic transition of 7Li under pressure

    DOE PAGESBeta

    Schaeffer, Anne Marie; Cai, Weizhao; Olejnik, Ella; Molaison, Jamie J.; Sinogeikin, Stanislav; dos Santos, Antonio M.; Deemyad, Shanti

    2015-08-14

    We report that physical properties of lithium under extreme pressures continuously reveal unexpected features. These include a sequence of structural transitions to lower symmetry phases, metal-insulator-metal transition, superconductivity with one of the highest elemental transition temperatures, and a maximum followed by a minimum in its melting line. The instability of the bcc structure of lithium is well established by the presence of a temperature-driven martensitic phase transition. The boundaries of this phase, however, have not been previously explored above 3 GPa. All higher pressure phase boundaries are either extrapolations or inferred based on indirect evidence. Here we explore the pressuremore » dependence of the martensitic transition of lithium up to 7 GPa using a combination of neutron and X-ray scattering. We find a rather unexpected deviation from the extrapolated boundaries of the hR3 phase of lithium. Furthermore, there is evidence that, above ~3 GPa, once in fcc phase, lithium does not undergo a martensitic transition.« less

  1. Boundaries for martensitic transition of 7Li under pressure

    PubMed Central

    Schaeffer, Anne Marie; Cai, Weizhao; Olejnik, Ella; Molaison, Jamie J.; Sinogeikin, Stanislav; dos Santos, Antonio M.; Deemyad, Shanti

    2015-01-01

    Physical properties of lithium under extreme pressures continuously reveal unexpected features. These include a sequence of structural transitions to lower symmetry phases, metal-insulator-metal transition, superconductivity with one of the highest elemental transition temperatures, and a maximum followed by a minimum in its melting line. The instability of the bcc structure of lithium is well established by the presence of a temperature-driven martensitic phase transition. The boundaries of this phase, however, have not been previously explored above 3 GPa. All higher pressure phase boundaries are either extrapolations or inferred based on indirect evidence. Here we explore the pressure dependence of the martensitic transition of lithium up to 7 GPa using a combination of neutron and X-ray scattering. We find a rather unexpected deviation from the extrapolated boundaries of the hR3 phase of lithium. Furthermore, there is evidence that, above ∼3 GPa, once in fcc phase, lithium does not undergo a martensitic transition. PMID:26271453

  2. Nuclear power and nuclear weapons

    SciTech Connect

    Vaughen, V.C.A.

    1983-01-01

    The proliferation of nuclear weapons and the expanded use of nuclear energy for the production of electricity and other peaceful uses are compared. The difference in technologies associated with nuclear weapons and nuclear power plants are described.

  3. Nuclear quadrupole interaction and nonlinear optical property of some borate crystals^*

    NASA Astrophysics Data System (ADS)

    Choh, S. H.; Kim, I. G.; Shin, H. W.; Park, I.-W.

    2003-03-01

    Borate crystals, like Li_2B_4O_7, LiB_3O_5, and BaB_2O_4, consist of 4-coordinated and/or 3-coordinated boron-oxygen bonds. As reported [1], the principal Z-axis of the electric field gradient (EFG) around the boron in 3-coordinated bonds is perpendicular to the plane containing the boron-oxygen bonds. We calculated the principal Z-direction of the EFG-tensor by employing the simple point charge model for the arbitrary planar triangle configurations, and the results are consistent with experimental ones. Moreover, a strong correlation between the nonlinear optical coefficient and the nuclear quadrupole interactions, such as the quadrupole coupling constant and the asymmetry parameter, was empirically found for these compounds. Details will be presented. * Supported by the National Research Laboratory Program(MOST). [1] I. G. Kim and S. H. Choh, J. Phys.: Condens. Matter, b11, 8283 (1999).

  4. Nuclear rights - nuclear wrongs

    SciTech Connect

    Paul, E.F.; Miller, F.D.; Paul, J.; Ahrens, J.

    1986-01-01

    This book contains 11 selections. The titles are: Three Ways to Kill Innocent Bystanders: Some Conundrums Concerning the Morality of War; The International Defense of Liberty; Two Concepts of Deterrence; Nuclear Deterrence and Arms Control; Ethical Issues for the 1980s; The Moral Status of Nuclear Deterrent Threats; Optimal Deterrence; Morality and Paradoxical Deterrence; Immoral Risks: A Deontological Critique of Nuclear Deterrence; No War Without Dictatorship, No Peace Without Democracy: Foreign Policy as Domestic Politics; Marxism-Leninism and its Strategic Implications for the United States; Tocqueveille War.

  5. Nuclear Threshold States: Yesterday, Today, Tomorrow

    SciTech Connect

    Ogloblin, A. A.; Danilov, A. N.; Demyanova, A. S.; Belyaeva, T. L.; Goncharov, S. A.

    2010-04-30

    50 years ago exotic nuclear states with abnormally large radii located close to the thresholds of emission of nucleons or clusters were predicted. Recently a hypothesis of possible existence of alpha-particle Bose condensation was proposed. The 0{sup +}{sub 2}(7.65 MeV) state of {sup 12}C(so-called Hoyle state) is considered to be the prototype of such condensed state and have a dilute structure. We propose two methods for searching the alpha-condensate signatures in the Hoyle state and some other ones near the alpha-thresholds by using inelastic diffractive and rainbow scattering. Inelastic scattering of {sup 2}H, {sup 3}He, {sup 4}He, {sup 6}Li, and {sup 12}C on {sup 12}C was studied and the enhancement of the {sup 12}C radius in the Hoyle state relatively the ground state radius by a factor of 1.2 was demonstrated. Another signature of the condensate structure, 70% probability of all three alpha-particles to be in the s-state, was observed for the Hoyle state by studying the {sup 8}Be transfer reaction. The analogs of the Hoyle state with enhanced radii were identified in {sup 11}B and {sup 13}C. The proposed methods of measuring the nuclear radii allowed observation of neutron halos in the excited states of {sup 9}Be and {sup 13}C. The conception of abnormal dimensions of the threshold states finds its confirmation in many nuclear phenomena both well-known and new ones. One of the perspective domains of its manifestation are the nuclei heavier than {sup 100}Sn with N = Z, which are able to emit several alpha particles.

  6. Nuclear Medicine.

    ERIC Educational Resources Information Center

    Badawi, Ramsey D.

    2001-01-01

    Describes the use of nuclear medicine techniques in diagnosis and therapy. Describes instrumentation in diagnostic nuclear medicine and predicts future trends in nuclear medicine imaging technology. (Author/MM)

  7. Nuclear data for nuclear transmutation

    SciTech Connect

    Harada, Hideo

    2009-05-04

    Current status on nuclear data for the study of nuclear transmutation of radioactive wastes is reviewed, mainly focusing on neutron capture reactions. It is stressed that the highest-precision frontier research in nuclear data measurements should be a key to satisfy the target accuracies on the nuclear data requested for realizing the nuclear transmutation.

  8. Nuclear weapons and nuclear war

    SciTech Connect

    Cassel, C.; McCally, M.; Abraham, H.

    1984-01-01

    This book examines the potential radiation hazards and environmental impacts of nuclear weapons. Topics considered include medical responsibility and thermonuclear war, the threat of nuclear war, nuclear weaponry, biological effects, radiation injury, decontamination, long-term effects, ecological effects, psychological aspects, the economic implications of nuclear weapons and war, ethics, civil defense, arms control, nuclear winter, and long-term biological consequences of nuclear war.

  9. ENDF/B-VII.0: Next Generation Evaluated Nuclear Data Library for Nuclear Science and Technology

    SciTech Connect

    Chadwick, M B; Oblozinsky, P; Herman, M; Greene, N M; McKnight, R D; Smith, D L; Young, P G; MacFarlane, R E; Hale, G M; Haight, R C; Frankle, S; Kahler, A C; Kawano, T; Little, R C; Madland, D G; Moller, P; Mosteller, R; Page, P; Talou, P; Trellue, H; White, M; Wilson, W B; Arcilla, R; Dunford, C L; Mughabghab, S F; Pritychenko, B; Rochman, D; Sonzogni, A A; Lubitz, C; Trumbull, T H; Weinman, J; Brown, D; Cullen, D E; Heinrichs, D; McNabb, D; Derrien, H; Dunn, M; Larson, N M; Leal, L C; Carlson, A D; Block, R C; Briggs, B; Cheng, E; Huria, H; Kozier, K; Courcelle, A; Pronyaev, V; der Marck, S

    2006-10-02

    We describe the next generation general purpose Evaluated Nuclear Data File, ENDF/B-VII.0, of recommended nuclear data for advanced nuclear science and technology applications. The library, released by the U.S. Cross Section Evaluation Working Group (CSEWG) in December 2006, contains data primarily for reactions with incident neutrons, protons, and photons on almost 400 isotopes. The new evaluations are based on both experimental data and nuclear reaction theory predictions. The principal advances over the previous ENDF/B-VI library are the following: (1) New cross sections for U, Pu, Th, Np and Am actinide isotopes, with improved performance in integral validation criticality and neutron transmission benchmark tests; (2) More precise standard cross sections for neutron reactions on H, {sup 6}Li, {sup 10}B, Au and for {sup 235,238}U fission, developed by a collaboration with the IAEA and the OECD/NEA Working Party on Evaluation Cooperation (WPEC); (3) Improved thermal neutron scattering; (4) An extensive set of neutron cross sections on fission products developed through a WPEC collaboration; (5) A large suite of photonuclear reactions; (6) Extension of many neutron- and proton-induced reactions up to an energy of 150 MeV; (7) Many new light nucleus neutron and proton reactions; (8) Post-fission beta-delayed photon decay spectra; (9) New radioactive decay data; and (10) New methods developed to provide uncertainties and covariances, together with covariance evaluations for some sample cases. The paper provides an overview of this library, consisting of 14 sublibraries in the same, ENDF-6 format, as the earlier ENDF/B-VI library. We describe each of the 14 sublibraries, focusing on neutron reactions. Extensive validation, using radiation transport codes to simulate measured critical assemblies, show major improvements: (a) The long-standing underprediction of low enriched U thermal assemblies is removed; (b) The {sup 238}U, {sup 208}Pb, and {sup 9}Be reflector

  10. Current Status of Nuclear Physics Research

    NASA Astrophysics Data System (ADS)

    Bertulani, Carlos A.; Hussein, Mahir S.

    2015-12-01

    In this review, we discuss the current status of research in nuclear physics which is being carried out in different centers in the world. For this purpose, we supply a short account of the development in the area which evolved over the last nine decades, since the discovery of the neutron. The evolution of the physics of the atomic nucleus went through many stages as more data became available. We briefly discuss models introduced to discern the physics behind the experimental discoveries, such as the shell model, the collective model, the statistical model, the interacting boson model, etc., some of these models may be seemingly in conflict with each other, but this was shown to be only apparent. The richness of the ideas and abundance of theoretical models attests to the important fact that the nucleus is a really singular system in the sense that it evolves from two-body bound states such as the deuteron, to few-body bound states, such as 4He, 7Li, 9Be, etc. and up the ladder to heavier bound nuclei containing up to more than 200 nucleons. Clearly, statistical mechanics, usually employed in systems with very large number of particles, would seemingly not work for such finite systems as the nuclei, neither do other theories which are applicable to condensed matter. The richness of nuclear physics stems from these restrictions. New theories and models are presently being developed. Theories of the structure and reactions of neutron-rich and proton-rich nuclei, called exotic nuclei, halo nuclei, or Borromean nuclei, deal with the wealth of experimental data that became available in the last 35 years. Furthermore, nuclear astrophysics and stellar and Big Bang nucleosynthesis have become a more mature subject. Due to limited space, this review only covers a few selected topics, mainly those with which the authors have worked on. Our aimed potential readers of this review are nuclear physicists and physicists in other areas, as well as graduate students interested in

  11. Enhanced Cooling of Hydrogen Atoms by Lithium Atoms

    SciTech Connect

    Cote, R.; Jamieson, M. J.; Yan, Z-C.; Geum, N.; Jeung, G.-H.; Dalgarno, A.

    2000-03-27

    We present calculated scattering lengths for collisions between various isotopic forms of lithium and hydrogen atoms interacting via singlet and triplet molecular states of LiH. We demonstrate that one bound triplet level is supported for each isotopomer {sup 7}LiH , {sup 6}LiH , {sup 7}LiD , and {sup 6}LiD . We obtain large calculated triplet scattering lengths that are stable against uncertainties in the potential. We present elastic and momentum transfer cross sections, and the corresponding rate coefficients, for hydrogen atoms colliding with {sup 7}Li atoms. We suggest that enhanced cooling of trapped atomic hydrogen by {sup 7}Li atoms is feasible. (c) 2000 The American Physical Society.

  12. ENDF/B-VII.0: Next Generation Evaluated Nuclear Data Library for Nuclear Science and Technology

    NASA Astrophysics Data System (ADS)

    Chadwick, M. B.; Obložinský, P.; Herman, M.; Greene, N. M.; McKnight, R. D.; Smith, D. L.; Young, P. G.; MacFarlane, R. E.; Hale, G. M.; Frankle, S. C.; Kahler, A. C.; Kawano, T.; Little, R. C.; Madland, D. G.; Moller, P.; Mosteller, R. D.; Page, P. R.; Talou, P.; Trellue, H.; White, M. C.; Wilson, W. B.; Arcilla, R.; Dunford, C. L.; Mughabghab, S. F.; Pritychenko, B.; Rochman, D.; Sonzogni, A. A.; Lubitz, C. R.; Trumbull, T. H.; Weinman, J. P.; Brown, D. A.; Cullen, D. E.; Heinrichs, D. P.; McNabb, D. P.; Derrien, H.; Dunn, M. E.; Larson, N. M.; Leal, L. C.; Carlson, A. D.; Block, R. C.; Briggs, J. B.; Cheng, E. T.; Huria, H. C.; Zerkle, M. L.; Kozier, K. S.; Courcelle, A.; Pronyaev, V.; van der Marck, S. C.

    2006-12-01

    We describe the next generation general purpose Evaluated Nuclear Data File, ENDF/B-VII.0, of recommended nuclear data for advanced nuclear science and technology applications. The library, released by the U.S. Cross Section Evaluation Working Group (CSEWG) in December 2006, contains data primarily for reactions with incident neutrons, protons, and photons on almost 400 isotopes, based on experimental data and theory predictions. The principal advances over the previous ENDF/B-VI library are the following: (1) New cross sections for U, Pu, Th, Np and Am actinide isotopes, with improved performance in integral validation criticality and neutron transmission benchmark tests; (2) More precise standard cross sections for neutron reactions on H, 6Li, 10B, Au and for 235,238U fission, developed by a collaboration with the IAEA and the OECD/NEA Working Party on Evaluation Cooperation (WPEC); (3) Improved thermal neutron scattering; (4) An extensive set of neutron cross sections on fission products developed through a WPEC collaboration; (5) A large suite of photonuclear reactions; (6) Extension of many neutron- and proton-induced evaluations up to 150 MeV; (7) Many new light nucleus neutron and proton reactions; (8) Post-fission beta-delayed photon decay spectra; (9) New radioactive decay data; (10) New methods for uncertainties and covariances, together with covariance evaluations for some sample cases; and (11) New actinide fission energy deposition. The paper provides an overview of this library, consisting of 14 sublibraries in the same ENDF-6 format as the earlier ENDF/B-VI library. We describe each of the 14 sublibraries, focusing on neutron reactions. Extensive validation, using radiation transport codes to simulate measured critical assemblies, show major improvements: (a) The long-standing underprediction of low enriched uranium thermal assemblies is removed; (b) The 238U and 208Pb reflector biases in fast systems are largely removed; (c) ENDF/B-VI.8 good

  13. Non-thermal processes in standard big bang nucleosynthesis: I. In-flight nuclear reactions induced by energetic protons

    NASA Astrophysics Data System (ADS)

    Voronchev, V. T.; Nakao, Y.; Nakamura, M.

    2008-05-01

    The standard model of big bang nucleosynthesis (BBN) relies on a nuclear reaction network operating with thermal reactivities for Maxwellian plasma. In the primordial plasma, however, a number of non-thermal processes triggered by energetic particles of various origins can take place. In the present work we examine in-flight nuclear reactions induced in the plasma by MeV protons generated in D(d, p)T and 3He(d, p)4He fusions. We particularly focus on several low threshold endoergic processes. These are reactions omitted in the standard network—proton-induced break-ups of loosely bound D, 7Li, 7Be nuclei—and the 3H(p, n)3He charge-exchange reaction important for the interconversion of A = 3 nuclei in the early universe. It is found that the break-up processes in the plasma take the form of Maxwellian processes at temperatures T>70 keV, while in the lower temperature range they proceed as non-thermal reactions. It is shown that at T<70 keV the in-flight reaction channels can enhance the break-up reactivities by several orders of magnitude. The levels of these reactivities however remain insufficiently high to affect BBN kinetics and change the standard prediction of light element abundances. The abundances are found to be: Yp = 0.2457, D/H = 2.542 × 10-5, 3He/H = 1.004 × 10-5, 7Li/H = 4.444 × 10-10. Future steps in the study of non-thermal processes in the primordial plasma are briefly discussed.

  14. Activation analysis study on Li-ion batteries for nuclear forensic applications

    NASA Astrophysics Data System (ADS)

    Johnson, Erik B.; Whitney, Chad; Holbert, Keith E.; Zhang, Taipeng; Stannard, Tyler; Christie, Anthony; Harper, Peter; Anderson, Blake; Christian, James F.

    2015-06-01

    The nuclear materials environment has been increasing significantly in complexity over the past couple of decades. The prevention of attacks from nuclear weapons is becoming more difficult, and nuclear forensics is a deterrent by providing detailed information on any type of nuclear event for proper attribution. One component of the nuclear forensic analysis is a measurement of the neutron spectrum. As an example, the neutron component provides information on the composition of the weapons, whether boosting is involved or the mechanisms used in creating a supercritical state. As 6Li has a large cross-section for thermal neutrons, the lithium battery is a primary candidate for assessing the neutron spectrum after detonation. The absorption process for 6Li yields tritium, which can be measured at a later point after the nuclear event, as long as the battery can be processed in a manner to successfully extract the tritium content. In addition, measuring the activated constituents after exposure provides a means to reconstruct the incident neutron spectrum. The battery consists of a spiral or folded layers of material that have unique, energy dependent interactions associated with the incident neutron flux. A detailed analysis on the batteries included a pre-irradiated mass spectrometry analysis to be used as input for neutron spectrum reconstruction. A set of batteries were exposed to a hard neutron spectrum delivered by the University of Massachusetts, Lowell research reactor Fast Neutron Irradiator (FNI). The gamma spectra were measured from the batteries within a few days and within a week after the exposure to obtain sufficient data on the activated materials in the batteries. The activity was calculated for a number of select isotopes, indicating the number of associated neutron interactions. The results from tritium extraction are marginal. A measurable increase in detected particles (gammas and betas) below 50 keV not self-attenuated by the battery was observed

  15. Third-order RKR procedure

    NASA Astrophysics Data System (ADS)

    Pardo, A.; Camacho, J. J.; Poyato, J. M. L.; Fernandez-Alonso, J. I.

    1986-03-01

    Potential energy curves for the X 1Σ +state of 6LiH, 7LiH and 6LiD, 7LiD molecules have been calculated by the third-order RKR inversion procedure by including the Kaise correction. The results are in agreement with previously obtained curves by other authors using differents methods. As a check, the exact vibrational eigenfunctions, appropriate to these potentials, are obtained by direct numerical solutions of the radical Schrödinger equation.

  16. Nuclear Scans

    MedlinePlus

    Nuclear scans use radioactive substances to see structures and functions inside your body. They use a special ... images. Most scans take 20 to 45 minutes. Nuclear scans can help doctors diagnose many conditions, including ...

  17. Nuclear Chemistry.

    ERIC Educational Resources Information Center

    Chemical and Engineering News, 1979

    1979-01-01

    Provides a brief review of the latest developments in nuclear chemistry. Nuclear research today is directed toward increased activity in radiopharmaceuticals and formation of new isotopes by high-energy, heavy-ion collisions. (Author/BB)

  18. Nuclear Winter.

    ERIC Educational Resources Information Center

    Ehrlich, Anne

    1984-01-01

    "Nuclear Winter" was recently coined to describe the climatic and biological effects of a nuclear war. These effects are discussed based on models, simulations, scenarios, and projections. Effects on human populations are also considered. (JN)

  19. Report to the DOE Nuclear Data Committee, 1984

    SciTech Connect

    Wong, C.; Haight, R.C.; Struble, G.L.

    1984-02-01

    Experimental results are discussed for: /sup 6/ /sup 7/Li(n,/sup 4/He) cross sections at 14 MeV, neutron elastic and inelastic scattering from carbon near 14 MeV, neutron capture cross sections for /sup 46/Ca and /sup 48/Ca at stellar temperatures, revised neutron cross sections for /sup 142/ /sup 143/ /sup 144/Nd, fragment angular distribution for neutron fission of /sup 232/Th, neutron differential scattering measurements in the actinide region, nuclear structure of /sup 244/Am, conversion coefficients of the M4 transition in /sup 193m/Ir, gamma-ray and conversion-electron decay of the /sup 238/U shape isomer, and levels of /sup 244/Cm populated by the beta decay of 10-hr /sup 244g/Am and 26-minute /sup 244m/Am. Calculations described include tests of microscopic optical models for neutron and proton scattering on light nuclei in the range 14 to 45 MeV, a new dynamic model for fission, and the necessity of discrete-level modeling in isomer ratio calculations for neutron-induced reactions on deformed nuclei. Also, a reevaluation for ENDL of sigma(n,f) and anti nu p for /sup 235/U and /sup 239/Pu from 100 keV to 20 MeV is described. 31 references. (WHK)

  20. Nuclear Fuels.

    ERIC Educational Resources Information Center

    Nash, J. Thomas

    1983-01-01

    Trends in and factors related to the nuclear industry and nuclear fuel production are discussed. Topics addressed include nuclear reactors, survival of the U.S. uranium industry, production costs, budget cuts by the Department of Energy and U.S. Geological survey for resource studies, mining, and research/development activities. (JN)

  1. Nuclear weapons, nuclear effects, nuclear war

    SciTech Connect

    Bing, G.F.

    1991-08-20

    This paper provides a brief and mostly non-technical description of the militarily important features of nuclear weapons, of the physical phenomena associated with individual explosions, and of the expected or possible results of the use of many weapons in a nuclear war. Most emphasis is on the effects of so-called ``strategic exchanges.``

  2. STANDARD BIG BANG NUCLEOSYNTHESIS UP TO CNO WITH AN IMPROVED EXTENDED NUCLEAR NETWORK

    SciTech Connect

    Coc, Alain; Saimpert, Matthias; Vangioni, Elisabeth

    2012-01-10

    Primordial or big bang nucleosynthesis (BBN) is one of the three strong pieces of evidence for the big bang model together with the expansion of the universe and cosmic microwave background radiation. In this study, we improve the standard BBN calculations taking into account new nuclear physics analyses and enlarge the nuclear network up to sodium. This is, in particular, important to evaluate the primitive value of CNO mass fraction that could affect Population III stellar evolution. For the first time we list the complete network of more than 400 reactions with references to the origin of the rates, including Almost-Equal-To 270 reaction rates calculated using the TALYS code. Together with the cosmological light elements, we calculate the primordial beryllium, boron, carbon, nitrogen, and oxygen nuclei. We performed a sensitivity study to identify the important reactions for CNO, {sup 9}Be, and boron nucleosynthesis. We re-evaluated those important reaction rates using experimental data and/or theoretical evaluations. The results are compared with precedent calculations: a primordial beryllium abundance increase by a factor of four compared to its previous evaluation, but we note a stability for B/H and for the CNO/H abundance ratio that remains close to its previous value of 0.7 Multiplication-Sign 10{sup -15}. On the other hand, the extension of the nuclear network has not changed the {sup 7}Li value, so its abundance is still 3-4 times greater than its observed spectroscopic value.

  3. Standard Big Bang Nucleosynthesis up to CNO with an Improved Extended Nuclear Network

    NASA Astrophysics Data System (ADS)

    Coc, Alain; Goriely, Stéphane; Xu, Yi; Saimpert, Matthias; Vangioni, Elisabeth

    2012-01-01

    Primordial or big bang nucleosynthesis (BBN) is one of the three strong pieces of evidence for the big bang model together with the expansion of the universe and cosmic microwave background radiation. In this study, we improve the standard BBN calculations taking into account new nuclear physics analyses and enlarge the nuclear network up to sodium. This is, in particular, important to evaluate the primitive value of CNO mass fraction that could affect Population III stellar evolution. For the first time we list the complete network of more than 400 reactions with references to the origin of the rates, including ≈270 reaction rates calculated using the TALYS code. Together with the cosmological light elements, we calculate the primordial beryllium, boron, carbon, nitrogen, and oxygen nuclei. We performed a sensitivity study to identify the important reactions for CNO, 9Be, and boron nucleosynthesis. We re-evaluated those important reaction rates using experimental data and/or theoretical evaluations. The results are compared with precedent calculations: a primordial beryllium abundance increase by a factor of four compared to its previous evaluation, but we note a stability for B/H and for the CNO/H abundance ratio that remains close to its previous value of 0.7 × 10-15. On the other hand, the extension of the nuclear network has not changed the 7Li value, so its abundance is still 3-4 times greater than its observed spectroscopic value.

  4. The nuclear magnetic shielding as a function of internuclear separation

    NASA Astrophysics Data System (ADS)

    Jameson, Cynthia J.; de Dios, Angel C.

    1993-02-01

    Ab initio calculations of nuclear magnetic shielding surfaces for 23Na in the NaH molecule, 39Ar in ArNe, 21Ne in NeHe, and 39Ar in Ar...NaH are carried out over a wide range of internuclear separations, using a local origin method (LORG) which damps out the long-range errors due to incomplete basis sets. The R dependence of the intermolecular shielding in the attractive region of the potential in these systems and in Ar...Ar and Ar...Na+ are consistent with the long-range limiting forms associated with the shielding hyperpolarizability in conjunction with a mean square electric field approximation. The Cl and F shieldings over the range of nuclear displacements spanning the classical turning points of the ground vibrational states of ClF and F2 are found to be remarkably superposable upon scaling by the factors ṡRe. This holds as well for ClH compared with FH. The shielding of 23Na and 7Li in NaH and LiH molecules are almost superposable. These and the scaling of the intermolecular shielding in rare gas pairs indicate some general similarities of shielding surfaces. The systematic variation in the signs and magnitudes of the first derivative of X nuclear shielding at the equilibrium geometry in XHn molecules of the first and second row of the Periodic Table are shown to be consistent with a general shape for the shielding function σ(R), which we have found in rare gas pairs and for 23Na in NaH.

  5. Structural reinvestigation of Li3FeN2: Evidence of cationic disorder through XRD, solid-state NMR and Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Panabière, E.; Emery, N.; Lorthioir, C.; Sougrati, M. T.; Jumas, J.-C.; Bach, S.; Pereira-Ramos, J.-P.; Smith, R. I.; Willmann, P.

    2016-08-01

    A significant cationic disorder is evidenced on Li3FeN2 prepared through solid-state reaction under controlled atmosphere. This derivative anti fluorite type structure (orthorhombic, space group Ibam, a=4.870(1) Å, b=9.652(1) Å and c=4.789(1) Å), solved first through single crystal X-ray diffraction [7], is usually described by Li+ and Fe+3 ordered distribution in tetrahedral sites formed by the nitrogen network, leading to [FeN4/2]3- edge-sharing tetrahedral chains. From 7Li/6Li Nuclear Magnetic Resonance spectroscopy, 57Fe Mössbauer spectroscopy and powder X-ray and neutron diffraction, we demonstrate that about 4% of lithium sites are filled by iron and about 11% of iron sites are occupied by Li, which can explain the discrepancy within the Gudat's model observed on larger scale solid-state synthesis samples.

  6. Nuclear physics reactions of astrophysical importance

    NASA Astrophysics Data System (ADS)

    O'Malley, Patrick D.

    2012-05-01

    Understanding the origin of elements in the universe is one of the main goals of nuclear science and astrophysics today. Achieving this goal involves determining how the elements and their isotopes formed and being able to predict their abundances. At the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL), an experimental program has been established to use transfer reactions (such as (p,d) or (d,p)) to study the properties of many nuclei important to understanding the origins of various elements. Three measurements were done to aid in the determination of the origins of different light isotopes. Big Bang Nucleosynthesis calculations, constrained by the Wilkinson Microwave Anisotropy Probe results, produce primordial 7Li abundances almost a factor of four larger than those extrapolated from observations. Since primordial 7Li is believed to be mostly produced by the beta decay of 7Be, one proposed solution to this discrepancy is a resonant enhancement of the 7Be(d, p)2α reaction rate through the 5/2+ 16.7-MeV state in 9B. The 2H(7Be,d) 7Be reaction was used to search for such a resonance; none was observed. An upper limit on the width of the proposed resonance was deduced. 19F is believed to have formed in Asymptotic Giant Branch stars, but current models cannot reproduce the observed abundances of this nucleus. One of the key reactions responsible for the creation of 19F is 15N(α,γ). Therefore, it is important to understand reactions that might destroy 15N, such as 15N(n,γ). The magnitude of the 15N( n,γ) reaction rate depends directly on the neutron spectroscopic factors of low-lying 16N levels. Currently the measured spectroscopic factors differ from those expected from theory by a factor of 2. A study has been done to resolve this discrepancy using the d( 15N,p) reaction. The spectroscopic factors were all found to be

  7. Cation Ordering in Li[NixMnxCo(1-2x)]O2-Layered Cathode Materials: A Nuclear Magnetic Resonance (NMR), Pair Distribution Function, X-ray Absorption Spectroscopy, and Electrochemical Study

    SciTech Connect

    Zeng,D.; Cabana, J.; Breger, J.; Yoon, W.; Grey, C.

    2007-01-01

    Several members of the compositional series Li[NixMnxCo(1-2x)]O2 (0.01 = x = 1/3) were synthesized and characterized. X-ray diffraction results confirm the presence of the layered a-NaFeO2-type structure, while X-ray absorption near-edge spectroscopy experiments verify the presence of Ni2+, Mn4+, and Co3+. Their local environment and short-range ordering were investigated by using a combination of 6Li magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy and neutron pair distribution function (PDF) analysis, associated with reverse Monte Carlo (RMC) calculations. The 6Li MAS NMR spectra of compounds with low Ni/Mn contents (x = 0.10) show several well-resolved resonances, which start to merge when the amount of Ni and Mn increases, finally forming a broad resonance at high Ni/Mn contents. Analysis of the 6Li MAS NMR 6Li[Ni0.02Mn0.02Co0.96]O2 spectrum, is consistent with the formation of Ni2+ and Mn4+ clusters within the transition-metal layers, even at these low-doping levels. The oxidation state of Ni in this high Co content sample strongly depends upon the Li/transition metal ratio of the starting materials. Neutron PDF analysis of the highest Ni/Mn content sample Li[Ni1/3Mn1/3Co1/3]O2 shows a tendency for Ni cations to be close to Mn cations in the first coordination shell; however, the Co3+ ions are randomly distributed. Analysis of the intensity of the 'LiCoO2' resonance, arising from Li surrounded by Co3+ in its first two cation coordination shells, for the whole series provides further evidence for a nonrandom distribution of the transition-metal cations. The presence of the insulator-to-metal transition seen in the electrochemical profiles of these materials upon charging correlates strongly with the concentration of the 'LiCoO2' resonance.

  8. Above-ground Antineutrino Detection for Nuclear Reactor Monitoring

    DOE PAGESBeta

    Sweany, Melinda; Brennan, James S.; Cabrera-Palmer, Belkis; Kiff, Scott D.; Reyna, David; Throckmorton, Daniel J.

    2014-08-01

    Antineutrino monitoring of nuclear reactors has been demonstrated many times, however the technique has not as of yet been developed into a useful capability for treaty verification purposes. The most notable drawback is the current requirement that detectors be deployed underground, with at least several meters-water-equivalent of shielding from cosmic radiation. In addition, the deployment of liquid-based detector media presents a challenge in reactor facilities. We are currently developing a detector system that has the potential to operate above ground and circumvent deployment problems associated with a liquid detection media: the system is composed of segments of plastic scintillator surroundedmore » by 6LiF/ZnS:Ag. ZnS:Ag is a radio-luminescent phosphor used to detect the neutron capture products of lithium-6. Because of its long decay time compared to standard plastic scintillators, pulse-shape discrimination can be used to distinguish positron and neutron interactions resulting from the inverse beta decay (IBD) of antineutrinos within the detector volume, reducing both accidental and correlated backgrounds. Segmentation further reduces backgrounds by identifying the positron’s annihilation gammas, which are absent for most correlated and uncorrelated backgrounds. This work explores different configurations in order to maximize the size of the detector segments without reducing the intrinsic neutron detection efficiency. We believe this technology will ultimately be applicable to potential safeguards scenarios such as those recently described.« less

  9. Parameter Study of the LIFE Engine Nuclear Design

    SciTech Connect

    Kramer, K J; Meier, W R; Latkowski, J F; Abbott, R P

    2009-07-10

    LLNL is developing the nuclear fusion based Laser Inertial Fusion Energy (LIFE) power plant concept. The baseline design uses a depleted uranium (DU) fission fuel blanket with a flowing molten salt coolant (flibe) that also breeds the tritium needed to sustain the fusion energy source. Indirect drive targets, similar to those that will be demonstrated on the National Ignition Facility (NIF), are ignited at {approx}13 Hz providing a 500 MW fusion source. The DU is in the form of a uranium oxycarbide kernel in modified TRISO-like fuel particles distributed in a carbon matrix forming 2-cm-diameter pebbles. The thermal power is held at 2000 MW by continuously varying the 6Li enrichment in the coolants. There are many options to be considered in the engine design including target yield, U-to-C ratio in the fuel, fission blanket thickness, etc. Here we report results of design variations and compare them in terms of various figures of merit such as time to reach a desired burnup, full-power years of operation, time and maximum burnup at power ramp down and the overall balance of plant utilization.

  10. Nuclear astrophysics

    SciTech Connect

    Haxton, W.C.

    1992-12-31

    The problem of core-collapse supernovae is used to illustrate the many connections between nuclear astrophysics and the problems nuclear physicists study in terrestrial laboratories. Efforts to better understand the collapse and mantle ejection are also motivated by a variety of interdisciplinary issues in nuclear, particle, and astrophysics, including galactic chemical evolution, neutrino masses and mixing, and stellar cooling by the emission of new particles. The current status of theory and observations is summarized.

  11. Nuclear astrophysics

    SciTech Connect

    Haxton, W.C.

    1992-01-01

    The problem of core-collapse supernovae is used to illustrate the many connections between nuclear astrophysics and the problems nuclear physicists study in terrestrial laboratories. Efforts to better understand the collapse and mantle ejection are also motivated by a variety of interdisciplinary issues in nuclear, particle, and astrophysics, including galactic chemical evolution, neutrino masses and mixing, and stellar cooling by the emission of new particles. The current status of theory and observations is summarized.

  12. Nuclear APC.

    PubMed

    Neufeld, Kristi L

    2009-01-01

    Mutational inactivation of the tumor suppressor gene APC (Adenomatous polyposis coli) is thought to be an initiating step in the progression of the vast majority ofcolorectal cancers. Attempts to understand APC function have revealed more than a dozen binding partners as well as several subcellular localizations including at cell-cell junctions, associated with microtubules at the leading edge of migrating cells, at the apical membrane, in the cytoplasm and in the nucleus. The present chapter focuses on APC localization and functions in the nucleus. APC contains two classical nuclear localization signals, with a third domain that can enhance nuclear import. Along with two sets of nuclear export signals, the nuclear localization signals enable the large APC protein to shuttle between the nucleus and cytoplasm. Nuclear APC can oppose beta-catenin-mediated transcription. This down-regulation of nuclear beta-catenin activity by APC most likely involves nuclear sequestration of beta-catenin from the transcription complex as well as interaction of APC with transcription corepressor CtBP. Additional nuclear binding partners for APC include transcription factor activator protein AP-2alpha, nuclear export factor Crm1, protein tyrosine phosphatase PTP-BL and perhaps DNA itself. Interaction of APC with polymerase beta and PCNA, suggests a role for APC in DNA repair. The observation that increases in the cytoplasmic distribution of APC correlate with colon cancer progression suggests that disruption of these nuclear functions of APC plays an important role in cancer progression. APC prevalence in the cytoplasm of quiescent cells points to a potential function for nuclear APC in control of cell proliferation. Clear definition of APC's nuclear function(s) will expand the possibilities for early colorectal cancer diagnostics and therapeutics targeted to APC. PMID:19928349

  13. Nuclear safety

    NASA Technical Reports Server (NTRS)

    Buden, D.

    1991-01-01

    Topics dealing with nuclear safety are addressed which include the following: general safety requirements; safety design requirements; terrestrial safety; SP-100 Flight System key safety requirements; potential mission accidents and hazards; key safety features; ground operations; launch operations; flight operations; disposal; safety concerns; licensing; the nuclear engine for rocket vehicle application (NERVA) design philosophy; the NERVA flight safety program; and the NERVA safety plan.

  14. Nuclear stress test

    MedlinePlus

    ... Persantine stress test; Thallium stress test; Stress test - nuclear; Adenosine stress test; Regadenoson stress test; CAD - nuclear stress; Coronary artery disease - nuclear stress; Angina - nuclear ...

  15. Precision measurement of quenching factors for low-energy nuclear recoils at TUNL

    NASA Astrophysics Data System (ADS)

    Rich, Grayson; Barbeau, Phil; Howell, Calvin; Karwowski, Hugon

    2014-03-01

    With detector technologies becoming increasingly sensitive to exotic events, a thorough understanding of signal yield as a function of deposited energy is required for appropriate interpretation of results from cutting edge detector systems. Elastic neutron scattering is a probe which has been used to mimic the nuclear recoils which may be produced in detection media by light-WIMP interactions or coherent neutrino-nucleus scattering (CNS). We have built at the Triangle Universities Nuclear Laboratory (TUNL) a facility which produces pulsed, collimated, low-energy, quasi-monoenergetic neutron beams using the 7Li(p,n) reaction, resulting in fluxes of ~ 1 neutrons / (s . cm2) at ~90 cm from the neutron-production target. The first precision results from this facility are reported for ultra-low-energy recoils in NaI(Tl) and CsI(Na) and future plans are outlined, including measurements on candidate materials for a CNS detector that can potentially be fielded at the Spallation Neutron Source of Oak Ridge National Laboratory as a part the Coherent Scatter Initiative (CSI). We discuss the implications of new, precise measurements of quenching factors on neutrino detectors and on current- and next-generation light-WIMP searches, particularly the DAMA experiment.

  16. Proton enhanced scattering and nuclear reaction analysis microcharacterization of ternary graphite-lithium-calcium intercalation compounds

    NASA Astrophysics Data System (ADS)

    Berger, P.; Pruvost, S.; Hérold, C.; Lagrange, P.

    2004-06-01

    Intercalation of lithium into graphite is of great interest, due to its largely expanded use as negative electrode material in the Li-ion batteries, especially the LiC 6 compound. Recently, the first ternary intercalation compounds associating lithium with a second metallic element were synthesized by immersing pyrographite platelet in a molten Ca-Li alloy. Photonic and neutronic diffractions on these graphite-lithium-calcium compounds reveal that lithium and calcium layers are intercalated between graphene sheets. However, the precise elemental composition still lacks. Chemical analysis gives an average composition but carbon is not measured in the same sample as calcium and lithium. Electron microprobe, SEM and TEM do not allow to determine lithium concentration and its distribution in these compounds. This paper reports the first elemental characterization of carbon-calcium-lithium intercalation compounds by means of nuclear microprobe. Using a 3.1 MeV proton beam, both lithium, calcium and carbon can be determined within a single measurement, from the 7Li(p,α) 4He nuclear reaction and from elastic scattering for calcium and carbon respectively. In the graphite-lithium-calcium system, three different intercalation compounds were synthesized, containing low to high lithium content. The mapping of the samples reveals lateral and also mainly in depth heterogeneity (along the c axis).

  17. Characterization of borate glasses by W-band pulse electron-nuclear double resonance spectroscopy

    SciTech Connect

    Kordas, George; Goldfarb, Daniella

    2008-10-21

    (100-x) mol % B{sub 2}O{sub 3} x mol %Me{sub 2}O (Me=Li,Na,K) glasses, exposed to {gamma}-{sup 60}Co irradiation to produce paramagnetic states, were characterized by W-band (95 GHz) pulse electron-nuclear double resonance (ENDOR) spectroscopy in order to characterize local structures occurring in the range of compositions between x=16 and x=25 at which the 'boron oxide' anomaly occurs. The high resolution of nuclear frequencies allowed resolving the {sup 7}Li and {sup 11}B ENDOR lines. In the samples with x=16 and x=20 glasses, {sup 11}B hyperfine couplings of 16, 24, and 36 MHz were observed and attributed to the tetraborate, triborate, and boron oxygen hole center (BOHC) structures, respectively. The x=25 samples showed hyperfine couplings of 15 MHz for the tetraborate and 36 MHz for BOHC. Density functional theory (DFT) calculations predicted for these structures negative hyperfine couplings, which were confirmed by W-band ENDOR. This suggests that a spin polarization mechanism accounts for the negative hyperfine structure splitting.

  18. Characterization of borate glasses by W-band pulse electron-nuclear double resonance spectroscopy.

    PubMed

    Kordas, George; Goldfarb, Daniella

    2008-10-21

    (100-x) mol % B(2)O(3) x mol % Me(2)O (Me = Li,Na,K) glasses, exposed to gamma-(60)Co irradiation to produce paramagnetic states, were characterized by W-band (95 GHz) pulse electron-nuclear double resonance (ENDOR) spectroscopy in order to characterize local structures occurring in the range of compositions between x=16 and x=25 at which the "boron oxide" anomaly occurs. The high resolution of nuclear frequencies allowed resolving the (7)Li and (11)B ENDOR lines. In the samples with x=16 and x=20 glasses, (11)B hyperfine couplings of 16, 24, and 36 MHz were observed and attributed to the tetraborate, triborate, and boron oxygen hole center (BOHC) structures, respectively. The x=25 samples showed hyperfine couplings of 15 MHz for the tetraborate and 36 MHz for BOHC. Density functional theory (DFT) calculations predicted for these structures negative hyperfine couplings, which were confirmed by W-band ENDOR. This suggests that a spin polarization mechanism accounts for the negative hyperfine structure splitting. PMID:19045204

  19. Neutron Transport and Nuclear Burnup Analysis for the Laser Inertial Confinement Fusion-Fission Energy (LIFE) Engine

    SciTech Connect

    Kramer, K J; Latkowski, J F; Abbott, R P; Boyd, J K; Powers, J J; Seifried, J E

    2008-10-24

    Lawrence Livermore National Laboratory is currently developing a hybrid fusion-fission nuclear energy system, called LIFE, to generate power and burn nuclear waste. We utilize inertial confinement fusion to drive a subcritical fission blanket surrounding the fusion chamber. It is composed of TRISO-based fuel cooled by the molten salt flibe. Low-yield (37.5 MJ) targets and a repetition rate of 13.3 Hz produce a 500 MW fusion source that is coupled to the subcritical blanket, which provides an additional gain of 4-8, depending on the fuel. In the present work, we describe the neutron transport and nuclear burnup analysis. We utilize standard analysis tools including, the Monte Carlo N-Particle (MCNP) transport code, ORIGEN2 and Monteburns to perform the nuclear design. These analyses focus primarily on a fuel composed of depleted uranium not requiring chemical reprocessing or enrichment. However, other fuels such as weapons grade plutonium and highly-enriched uranium are also under consideration. In addition, we have developed a methodology using {sup 6}Li as a burnable poison to replace the tritium burned in the fusion targets and to maintain constant power over the lifetime of the engine. The results from depleted uranium analyses suggest up to 99% burnup of actinides is attainable while maintaining full power at 2GW for more than five decades.

  20. Nuclear Speckles

    PubMed Central

    Spector, David L.; Lamond, Angus I.

    2011-01-01

    Nuclear speckles, also known as interchromatin granule clusters, are nuclear domains enriched in pre-mRNA splicing factors, located in the interchromatin regions of the nucleoplasm of mammalian cells. When observed by immunofluorescence microscopy, they usually appear as 20–50 irregularly shaped structures that vary in size. Speckles are dynamic structures, and their constituents can exchange continuously with the nucleoplasm and other nuclear locations, including active transcription sites. Studies on the composition, structure, and dynamics of speckles have provided an important paradigm for understanding the functional organization of the nucleus and the dynamics of the gene expression machinery. PMID:20926517

  1. (Nuclear theory). [Research in nuclear physics

    SciTech Connect

    Haxton, W.

    1990-01-01

    This report discusses research in nuclear physics. Topics covered in this paper are: symmetry principles; nuclear astrophysics; nuclear structure; quark-gluon plasma; quantum chromodynamics; symmetry breaking; nuclear deformation; and cold fusion. (LSP)

  2. A search for the {Delta}{sup {minus}} wave-function component in light nuclei

    SciTech Connect

    Morris, C.L.; Zumbro, J.D.; Boudrie, R.L.

    1996-10-01

    We have studied the ({pi}{sup +}, {pi}{sup {+-}}p) reactions on {sup 3}He, {sup 4}He, {sup 6}Li, and {sup 7}Li at incident energy 500 MeV in quasi-free kinematics. A signature attributable to pre-existing {Delta} components of the ground state wave function is observed.

  3. Investigation of the lithium 670.7 nm wavelength range in the solar spectrum

    NASA Astrophysics Data System (ADS)

    Caffau, Elisabetta; Mott, Alessandro; Harutyunyan, Gohar; Malherbe, Jean-Marie; Steffen, Matthias

    2016-07-01

    Lithium is a key chemical element, with a chemical evolution that is different from that of most other elements. It is also very fragile, as it is destroyed by nuclear reactions with protons at temperatures higher than about 2.5 million K. According to standard Big Bang nucleosynthesis, only the isotope 7Li is produced in significant amounts, while the primordial abundance of the lighter isotope 6Li is negligible. Lithium is not produced by nucleosynthesis in normal stars, except in peculiar phases of stellar evolution (e.g. in AGB stars and Novae). Lithium may also be formed as a result of flares in the atmospheres of young, active stars. To investigate the history of Li production and depletion in the Galaxy, it is necessary to analyse stars of all ages, including those at solar metallicity. In this case, the spectroscopic determination of the Li abundance is complicated by the presence of other spectral lines overlapping with the Li doublet at 670.7 nm. The correct identification and knowledge of the atomic parameters of these blend lines is critical, especially if the 6LI/7Li isotopic ratio is to be derived. In this investigation, we consider several line lists of the blending components available in the literature and use them to compute synthetic spectra, performing the line formation computations both for the classical 1D Holweger-Mueller model and a CO5BOLD 3D hydrodynamical simulation of the solar atmosphere. The synthetic spectra are then compared to the solar spectrum observed at different limb angles. This allows us to check the quality of existing line lists, to find potentially misidentified blend lines, and to construct an optimized line list for solar-type stars.

  4. Inclusive Pion Double Charge Exchange in Light P - Nuclei at Intermediate Energies.

    NASA Astrophysics Data System (ADS)

    Fong, Wilson

    Inclusive measurements of the doubly differential cross section for the reaction pion double charge exchange (DCX) reaction were made on ^6Li, ^7Li, ^9Be and ^{12}C. The experiments were performed at the Los Alamos Physics Facility (LAMPF) using the "Little Yellow Spectrometer", LYS. The measurements were made for both pi^+ and pi^- at T_ pi = 120, 180, and 240 MeV for three to five angles between 25^circ and 130^circ. The outgoing pion kinetic energy range was observed. These are the only known measurements of inclusive DCX cross sections on the ^6Li, ^7Li and ^9Be nuclei. The DCX reaction requires at least two nucleons to be involved in order to conserve charge. The simplest reaction model for DCX is the sequential single charge exchange model, SSCX. The measurements aimed to examine the evolution of the double peaked structure seen at high incident pion energy at forward angles as the nuclear mass, A, increases. The double peaked structure is believed to be a direct consequence of the dominant p-wave nature of the SCX reaction in the Delta -region and the two step process of SSCX. Furthermore, an examination of the effects of introducing an additional neutron into an N = Z system is made. When the additional neutron is not involved in the DCX process, it functions to draw flux away from the DCX channel, thereby reducing the DCX cross section. Calculations based on theoretical models of Oset and Kinney have been performed and a comparison made with the measured DCX cross sections. The comparison between experiment and theory shows the need for further theoretical work in inclusive DCX reactions. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.).

  5. Nuclear forces

    SciTech Connect

    Machleidt, R.

    2013-06-10

    These lectures present an introduction into the theory of nuclear forces. We focus mainly on the modern approach, in which the forces between nucleons emerge from low-energy QCD via chiral effective field theory.

  6. NUCLEAR REACTOR

    DOEpatents

    Sherman, J.; Sharbaugh, J.E.; Fauth, W.L. Jr.; Palladino, N.J.; DeHuff, P.G.

    1962-10-23

    A nuclear reactor incorporating seed and blanket assemblies is designed. Means are provided for obtaining samples of the coolant from the blanket assemblies and for varying the flow of coolant through the blanket assemblies. (AEC)

  7. Nuclear battlefields

    SciTech Connect

    Arkin, W.M.; Fieldhouse, R.W.

    1985-01-01

    This book provides complete data on the nuclear operations and research facilities in the U.S.A., the U.S.S.R., France, China and the U.K. It describes detailed estimates on the U.S.S.R.'s nuclear stockpile for over 500 locations. It shows how non-nuclear countries cooperate with the world-wide war machine. And it maps the U.S. nuclear facilities from Little America, WY, and Charleston, SC, to the battleships patroling the world's oceans and subs stalking under the sea. The data were gathered from unclassified sources through the Freedom of Information Act, from data supplied to military installations, and from weapons source books. It provides guidance for policymakers, government and corporate officials.

  8. Nuclear Data

    SciTech Connect

    White, Morgan C.

    2014-01-23

    PowerPoint presentation targeted for educational use. Nuclear data comes from a variety of sources and in many flavors. Understanding where the data you use comes from and what flavor it is can be essential to understand and interpret your results. This talk will discuss the nuclear data pipeline with particular emphasis on providing links to additional resources that can be used to explore the issues you will encounter.

  9. Nuclear Nonproliferation

    SciTech Connect

    Atkins-Duffin, C E

    2008-12-10

    With an explosion equivalent of about 20kT of TNT, the Trinity test was the first demonstration of a nuclear weapon. Conducted on July 16, 1945 in Alamogordo, NM this site is now a Registered National Historic Landmark. The concept and applicability of nuclear power was demonstrated on December 20, 1951 with the Experimental Breeder Reactor Number One (EBR-1) lit four light bulbs. This reactor is now a Registered National Historic Landmark, located near Arco, ID. From that moment forward it had been clearly demonstrated that nuclear energy has both peaceful and military applications and that the civilian and military fuel cycles can overlap. For the more than fifty years since the Atoms for Peace program, a key objective of nuclear policy has been to enable the wider peaceful use of nuclear energy while preventing the spread of nuclear weapons. Volumes have been written on the impact of these two actions on the world by advocates and critics; pundits and practioners; politicians and technologists. The nations of the world have woven together a delicate balance of treaties, agreements, frameworks and handshakes that are representative of the timeframe in which they were constructed and how they have evolved in time. Collectively these vehicles attempt to keep political will, nuclear materials and technology in check. This paper captures only the briefest abstract of the more significant aspects on the Nonproliferation Regime. Of particular relevance to this discussion is the special nonproliferation sensitivity associated with the uranium isotope separation and spent fuel reprocessing aspects of the nuclear fuel cycle.

  10. Neutron dosimetric measurements in shuttle and MIR.

    PubMed

    Reitz, G

    2001-06-01

    Detector packages consisting of thermoluminescence detectors (TLD), nuclear emulsions and plastic track detectors were exposed at identical positions inside MIR space station and on shuttle flights inside Spacelab and Spacehab during different phases of the solar cycle. The objectives of the investigations are to provide data on charge and energy spectra of heavy ions, and the contribution of events with low-energy deposit (protons, electrons, gamma, etc.) to the dose, as well as the contribution of secondaries, such as nuclear disintegration stars and neutrons. For neutron dosimetry 6LiF (TLD600) and 7LiF (TLD700) chips were used both of which have almost the same response to gamma rays but different response to neutrons. Neutrons in space are produced mainly in evaporation and knock-on processes with energies mainly of 1-10 MeV and up to several 100 MeV, respectively. The energy spectrum undergoes continuous changes toward greater depth in the attenuating material until an equilibrium is reached. In equilibrium, the spectrum is a wide continuum extending down to thermal energies to which the 6LiF is sensitive. Based on the difference of absorbed doses in the 6LiF and 7LiF chips, thermal neutron fluxes from 1 to 2.3 cm-2 s-1 are calculated using the assumption that the maximum induced dose in TLD600 for 1 neutron cm-2 is 1.6 x 10(-10) Gy (Horowitz and Freeman, Nucl. Instr. and Meth. 157 (1978) 393). It is assumed that the flux of high-energy neutrons is at least of that quantity. Tissue doses were calculated taking as a mean ambient absorbed dose per neutron 6 x10(-12) Gy cm2 (for a10 MeV neutron). The neutron equivalent doses for the above-mentioned fluxes are 52 micro Gy d-1 and 120 micro Gy d-1. In recent experiments, a personal neutron dosimeter was integrated into the dosimeter packages. First results of this dosimeter which is based on nuclear track detectors with converter foils are reported. For future measurements, a scintillator counter with

  11. High power linear accelerators for tritium production and transmutation of nuclear waste

    SciTech Connect

    Lawrence, G.P.

    1990-01-01

    Proton linacs driving high-flux spallation neutron sources are being considered for transmutation of nuclear waste and production of tritium. Advances in high-current linac technology have provided a basis for the development of credible designs for the required accelerator, which has a nominal 1.6-GeV energy, and a 250-mA cw current. A beam with these parameters incident on a liquid lead-bismuth (Pb-Bi) target can generate a thermal neutron flux of up to 5 {times} 10{sup 16} n/cm{sup 2}-s in a cylindrical blanket surrounding the spallation source. This high flux can produce tritium through the {sup 6}Li(n,{alpha})T or {sup 3}He(n,{gamma})T reactions, or can burn long-lived actinides and fission products from nuclear waste through capture and fission processes. In some system scenarios, waste actinides and/or other fissile materials in the blanket can produce sufficient fission energy to power the accelerator.

  12. 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.

  13. Nuclear magnetic resonance study of Li and H diffusion in the high-temperature solid phase of LiBH{sub 4}

    SciTech Connect

    Soloninin, A.V.; Skripov, A.V.; Buzlukov, A.L.; Stepanov, A.P.

    2009-09-15

    In order to study the atomic jump motions in the high-temperature solid phase of LiBH{sub 4}, we have measured the {sup 1}H and {sup 11}B nuclear magnetic resonance (NMR) spectra and the {sup 1}H, {sup 7}Li and {sup 11}B spin-lattice relaxation rates in this compound over the resonance frequency range of 14-34.4 MHz. In the temperature range 384-500 K, all the spin-lattice relaxation data are satisfactorily described in terms of a thermally activated jump motion of Li ions with the pre-exponential factor tau{sub 0}=1.1x10{sup -15} s and the activation energy E{sub a}=0.56 eV. The observed frequency dependences of the spin-lattice relaxation rates in this temperature range exclude a presence of any distributions of the Li jump rate or any other jump processes on the frequency scale of 10{sup 7}-10{sup 10} s{sup -1}. The strong narrowing of the {sup 1}H and {sup 11}B NMR lines above 440 K is consistent with the onset of diffusive motion of the BH{sub 4} tetrahedra. - Graphical abstract: The measured spin-lattice relaxation rates of {sup 1}H (a), {sup 7}Li (b) and {sup 11}B (c) as functions of the inverse temperature for the high-temperature solid phase of LiBH{sub 4}. The curves show the simultaneous Bloembergen-Purcell-Pound fits to the data with the fixed parameters of Li diffusion (the pre-exponential factor tau{sub 0}=1.1x10{sup -15} s and the activation energy E{sub a}=0.56 eV). This plot indicates that all the relaxation data for different nuclei and at different resonance frequencies are governed by a single Li jump process. Display Omitted

  14. Towards a beyond 1 GHz solid-state nuclear magnetic resonance: External lock operation in an external current mode for a 500 MHz nuclear magnetic resonance

    SciTech Connect

    Takahashi, Masato; Maeda, Hideaki; Ebisawa, Yusuke; Tennmei, Konosuke; Yanagisawa, Yoshinori; Nakagome, Hideki; Hosono, Masami; Takasugi, Kenji; Hase, Takashi; Miyazaki, Takayoshi; Fujito, Teruaki; Kiyoshi, Tsukasa; Yamazaki, Toshio

    2012-10-15

    Achieving a higher magnetic field is important for solid-state nuclear magnetic resonance (NMR). But a conventional low temperature superconducting (LTS) magnet cannot exceed 1 GHz (23.5 T) due to the critical magnetic field. Thus, we started a project to replace the Nb{sub 3}Sn innermost coil of an existing 920 MHz NMR (21.6 T) with a Bi-2223 high temperature superconducting (HTS) innermost coil. Unfortunately, the HTS magnet cannot be operated in persistent current mode; an external dc power supply is required to operate the NMR magnet, causing magnetic field fluctuations. These fluctuations can be stabilized by a field-frequency lock system based on an external NMR detection coil. We demonstrate here such a field-frequency lock system in a 500 MHz LTS NMR magnet operated in an external current mode. The system uses a {sup 7}Li sample in a microcoil as external NMR detection system. The required field compensation is calculated from the frequency of the FID as measured with a frequency counter. The system detects the FID signal, determining the FID frequency, and calculates the required compensation coil current to stabilize the sample magnetic field. The magnetic field was stabilized at 0.05 ppm/3 h for magnetic field fluctuations of around 10 ppm. This method is especially effective for a magnet with large magnetic field fluctuations. The magnetic field of the compensation coil is relatively inhomogeneous in these cases and the inhomogeneity of the compensation coil can be taken into account.

  15. Nuclear risk

    SciTech Connect

    Levenson, M.

    1989-01-01

    The title of our session, Nuclear Risk Versus Other Power Options, is provocative. It is also a title with different meanings to different people. To the utility chief executive officer, nuclear power is a high-risk financial undertaking because of political and economic barriers to cost recovery. To the utility dispatcher, it is a high-risk future power source since plant completion and start-up dates can be delayed for very long times due to uncertain legal and political issues. To the environmentalist, concerned about global effects such as greenhouse and acid rain, nuclear power is a relatively low risk energy source. To the financial people, nuclear power is a cash cow turned sour because of uncertainties as to what new plants will cost and whether they will even be allowed to operate. The statistics on risk are known and the results of probability risk assessment calculations of risks are known. The challenge is not to make nuclear power safer, it is already one of the safest, if not the safest, source of power currently available. The challenge is to find a way to communicate this to the public.

  16. An ultra-high-resolution survey of the interstellar lithium-7 to lithium-6 isotope ratio in the solar neighborhood

    NASA Astrophysics Data System (ADS)

    Knauth, David C.

    Previous studies on the interstellar 7Li/6Li ratio show variations in its value. In an effort to probe the extent of these variations, ultra-high-resolution (R ˜ 360,000), high signal-to-noise spectra of stars in the Perseus OB2 and Scorpius OB2 Associations were obtained. These observations confirm my earlier findings of an interstellar 7Li/6Li ratio of about 2 toward o Per, the value predicted from models of GCR spallation reactions. However, observations of the other nearby stars yield isotopic ratios closer to that seen in carbonaceous chondrite meteorites (7Li/6Li = 12.3). My results suggest that the 7Li/6Li ratio has not changed significantly during the last 4.5 billion years (Gyr) and that a ratio ˜12 represents most gas in the solar neighborhood. Some directions reveal the presence of interesting processes taking place. If the Solar System value of about 12 originally represented the gas toward o Per, then an increase in the Li abundance by an order of magnitude is expected, but is not seen. The elemental K/Li ratio is not unusual, although Li and K are formed via different nucleosynthetic pathways. Fractionation cannot account for the low 7Li/6Li ratio; the abundance of LiH is too low. In attempt to explain the low ratio toward o Per, the role of stellar flares from young stars in IC 348 was investigated, but the amount of 6Li created in stellar flares is negligible. Another interesting result is evidence for enhanced depletion toward X Per, since both the Li and K abundances are lower by a factor of 4 when compared to other sight lines. Moreover, enhanced destruction of Li relative to H and K is suggested by my measurements of 20 Aql. A possible cause is the proximity of the line of sight toward 20 Aql to the supernova remnant, Radio Loop I, but a simple calculation for Li destruction indicates timescales much longer than the estimated age of the remnant. From knowledge of the interstellar 7Li/6Li ratio, the amount of 7Li from stellar sources needed to

  17. An Ultra-High-Resolution Survey of the Interstellar Lithium-7 to Lithium-6 Isotope Ratio in the Solar Neighborhood

    NASA Astrophysics Data System (ADS)

    Knauth, D. C.

    2002-04-01

    Previous studies on the interstellar 7Li/6Li ratio show variations in its value. In an effort to probe the extent of these variations, ultra-high-resolution (R ˜ 360,000), high signal-to-noise spectra of stars in the Perseus OB2 and Scorpius OB2 Associations were obtained. These observations confirm my earlier findings of an interstellar 7Li/6Li ratio of about 2 toward o Per, the value predicted from models of GCR spallation reactions. However, observations of the other nearby stars yield isotopic ratios closer to that seen in carbonaceous chondrite meteorites (7Li/6Li = 12.3). My results suggest that the 7Li/6Li ratio has not changed significantly during the last 4.5 billion years (Gyr) and that a ratio ˜12 represents most gas in the solar neighborhood. Some directions reveal the presence of interesting processes taking place. If the Solar System value of about 12 originally represented the gas toward o Per, then an increase in the Li abundance by an order of magnitude is expected, but is not seen. The elemental K/Li ratio is not unusual, although Li and K are formed via different nucleosynthetic pathways. Fractionation cannot account for the low 7Li/6Li ratio; the abundance of LiH is too low. In attempt to explain the low ratio toward o Per, the role of stellar flares from young stars in IC 348 was investigated, but the amount of 6Li created in stellar flares is negligible. Another interesting result is evidence for enhanced depletion toward X Per, since both the Li and K abundances are lower by a factor of 4 when compared to other sight lines. Moreover, enhanced destruction of Li relative to H and K is suggested by my measurements of 20 Aql. A possible cause is the proximity of the line of sight toward 20 Aql to the supernova remnant, Radio Loop I, but a simple calculation for Li destruction indicates timescales much longer than the estimated age of the remnant. From knowledge of the interstellar 7Li/6Li ratio, the amount of 7Li from stellar sources needed to

  18. Nuclear astrophysics

    NASA Astrophysics Data System (ADS)

    Penionzhkevich, Yu. E.

    2010-08-01

    The International Year of Astronomy 2009 (IYA2009) was declared by the 62nd General Assembly of the United Nations and was also endorsed by UNESCO. Investigations in the realms of particle and nuclear physicsmake a large contribution in the development of our ideas of the properties of the Universe. The present article discusses some problems of the evolution of the Universe, nucleosyntheses, and cosmochronology from the point of view of nuclear and particle physics. Processes occurring in the Universe are compared with the mechanisms of the production and decay of nuclei, as well as with the mechanisms of their interaction at high energies. Examples that demonstrate the potential of nuclearphysics methods for studying cosmic objects and the properties of the Universe are given. The results that come from investigations into nuclear reactions induced by beams of radioactive nuclei and which make it possible to take a fresh look at the nucleosynthesis scenario in the range at light nuclei are presented.

  19. Nuclear scales

    SciTech Connect

    Friar, J.L.

    1998-12-01

    Nuclear scales are discussed from the nuclear physics viewpoint. The conventional nuclear potential is characterized as a black box that interpolates nucleon-nucleon (NN) data, while being constrained by the best possible theoretical input. The latter consists of the longer-range parts of the NN force (e.g., OPEP, TPEP, the {pi}-{gamma} force), which can be calculated using chiral perturbation theory and gauged using modern phase-shift analyses. The shorter-range parts of the force are effectively parameterized by moments of the interaction that are independent of the details of the force model, in analogy to chiral perturbation theory. Results of GFMC calculations in light nuclei are interpreted in terms of fundamental scales, which are in good agreement with expectations from chiral effective field theories. Problems with spin-orbit-type observables are noted.

  20. Nuclear pursuits

    SciTech Connect

    Not Available

    1993-05-01

    This table lists quantities of warheads (in stockpile, peak number per year, total number built, number of known test explosions), weapon development milestones (developers of the atomic bomb and hydrogen bomb, date of first operational ICBM, first nuclear-powered naval SSN in service, first MIRVed missile deployed), and testing milestones (first fission test, type of boosted fission weapon, multistage thermonuclear test, number of months from fission bomb to multistage thermonuclear bomb, etc.), and nuclear infrastructure (assembly plants, plutonium production reactors, uranium enrichment plants, etc.). Countries included in the tally are the United States, Soviet Union, Britain, France, and China.

  1. Nuclear power: Fourth edition

    SciTech Connect

    Deutsch, R.W.

    1986-01-01

    This book describes the basics of nuclear power generation, explaining both the benefits and the real and imagined risks of nuclear power. It includes a discussion of the Three Mile Island accident and its effects. Nuclear Power has been used in the public information programs of more than 100 utilities. The contents discussed are: Nuclear Power and People; Why Nuclear Power. Electricity produced by coal; Electricity produced by nuclear fuel; Nuclear plant sites in the United States; Short History of Commercial Nuclear Power; U.S. nuclear submarines, Regulation of Nuclear Power Plants; Licensing process, Nuclear Power Plant Operator Training; Nuclear power plant simulator, Are Nuclear Plants Safe.; Containment structure, Nuclear Power Plant Insurance; Is Radiation Dangerous.; Man-made radiation, What is Nuclear Fuel.; Fuel cycle for commercial nuclear power plants; Warm Water Discharge; Cooling tower; Protection of Radioactive Materials; Plutonium and Proliferation; Disposal of Radioactive Wastes; Are Alternate Energy Sources Available.; Nuclear Opposition; and Nuclear Power in the Future.

  2. Dependence of nuclear binding on hadronic mass variation

    SciTech Connect

    Flambaum, V. V.; Wiringa, R. B.

    2007-11-15

    We examine how the binding of light (A{<=}8) nuclei depends on possible variations of hadronic masses, including meson, nucleon, and nucleon-resonance masses. Small variations in hadronic masses may have occurred over time; the present results can help evaluate the consequences for big bang nucleosynthesis. Larger variations may be relevant to current attempts to extrapolate properties of nucleon-nucleon interactions from lattice QCD calculations. Results are presented as derivatives of the energy with respect to the different masses so they can be combined with different predictions of the hadronic mass-dependence on the underlying current-quark mass m{sub q}. As an example, we employ a particular set of relations obtained from a study of hadron masses and sigma terms based on Dyson-Schwinger equations and a Poincare-covariant Faddeev equation for confined quarks and diquarks. We find that nuclear binding decreases moderately rapidly as the quark mass increases, with the deuteron becoming unbound when the pion mass is increased by {approx}60% (corresponding to an increase in X{sub q}=m{sub q}/{lambda}{sub QCD} of 2.5). In the other direction, the dineutron becomes bound if the pion mass is decreased by {approx}15% (corresponding to a reduction of X{sub q} by {approx}30%). If we interpret the disagreement between big bang nucleosynthesis calculations and measurements to be the result of variation in X{sub q}, we obtain an estimate {delta}X{sub q}/X{sub q}=K{center_dot}(0.013{+-}0.002) where K{approx}1 (the expected accuracy in K is about a factor of 2). The result is dominated by {sup 7}Li data.

  3. Photodisintegration of Lithium Isotopes

    NASA Astrophysics Data System (ADS)

    Wurtz, Ward Andrew

    We have performed a measurement of the photodisintegration of the lithium isotopes, 6Li and 7Li, using a monochromatic, polarised photon beam and a segmented neutron detector array which covers approximately ¼ of 4pi srad. Using time-of-flight and scintillator light-output spectra we separate the data into individual reaction channels. This work is motivated by the need to compare with recent theoretical predictions and to provide data for future theoretical work. For the photodisintegration of 6Li we took data at 12 photon energies between 8 and 35 MeV. We describe the data using a model consisting of two-body reaction channels and obtain angular distributions and absolute cross sections for many of these reaction channels. We compare our results with a recent Lorentz integral transform calculation (Bacca et al. Phys. Rev. C 69, 057001 (2004)). Our results are in reasonable agreement with the calculation, in contradiction with previous experimental results. For the photodisintegration of 7Li, we took data at 9 photon energies between 10 and 35 MeV. We obtain cross sections for the reaction channel 7Li + gamma → n + 6 Li(g.s.) at all photon energies with angular distributions at all but the highest energy. We obtain angular distributions and total cross sections for reaction channels involving excited states of the daughter nucleus, 6Li, at select energies. We hope that these measurements will provide incentive for new theoretical calculations. We observe neutrons that can only be described by the reaction channel 7Li + gamma → n + 6Li(10.0) which necessitates an excited state of 6Li with excitation energy Ex = 10.0 +/- 0.5 MeV that is not in the standard tables of excited states. ii

  4. Nuclear Terrorism.

    SciTech Connect

    Hecker, Siegfried S.

    2001-01-01

    As pointed out by several speakers, the level of violence and destruction in terrorist attacks has increased significantly during the past decade. Fortunately, few have involved weapons of mass destruction, and none have achieved mass casualties. The Aum Shinrikyo release of lethal nerve agent, sarin, in the Tokyo subway on March 20, 1995 clearly broke new ground by crossing the threshold in attempting mass casualties with chemical weapons. However, of all weapons of mass destruction, nuclear weapons still represent the most frightening threat to humankind. Nuclear weapons possess an enormous destructive force. The immediacy and scale of destruction are unmatched. In addition to destruction, terrorism also aims to create fear among the public and governments. Here also, nuclear weapons are unmatched. The public's fear of nuclear weapons or, for that matter, of all radioactivity is intense. To some extent, this fear arises from a sense of unlimited vulnerability. That is, radioactivity is seen as unbounded in three dimensions - distance, it is viewed as having unlimited reach; quantity, it is viewed as having deadly consequences in the smallest doses (the public is often told - incorrectly, of course - that one atom of plutonium will kill); and time, if it does not kill you immediately, then it will cause cancer decades hence.

  5. Nuclear medicine

    SciTech Connect

    Wagner, H.N. Jr.

    1986-10-17

    In 1985 and 1986 nuclear medicine became more and more oriented toward in vov chemistry, chiefly as a result of advances in positron emission tomography (PET). The most important trend was the extension of PET technology into the care of patients with brain tumors, epilepsy, and heart disease. A second trend was the increasing use of single-photon emission computed tomography (SPECT).

  6. Nuclear energy.

    PubMed

    Wilson, Peter D

    2010-01-01

    The technical principles and practices of the civil nuclear industry are described with particular reference to fission and its products, natural and artificial radioactivity elements principally concerned and their relationships, main types of reactor, safety issues, the fuel cycle, waste management, issues related to weapon proliferation, environmental considerations and possible future developments. PMID:21180342

  7. Nuclear Science.

    ERIC Educational Resources Information Center

    Pennsylvania State Dept. of Education, Harrisburg. Bureau of Curriculum Services.

    This document is a report on a course in nuclear science for the high school curriculum. The course is designed to provide a basic but comprehensive understanding of the atom in the light of modern knowledge, and to show how people attempt to harness the tremendous energy liberated through fission and fusion reactions. The course crosses what are…

  8. Nuclear Misinformation

    ERIC Educational Resources Information Center

    Ford, Daniel F.; Kendall, Henry W.

    1975-01-01

    Many scientists feel that research into nuclear safety has been diverted or distorted, and the results of the research concealed or inaccurately reported on a large number of occasions. Of particular concern have been the emergency cooling systems which have not, as yet, been adequately tested. (Author/MA)

  9. Studies of K-absorption on light nuclei and the search for bound nuclear kaonic states

    NASA Astrophysics Data System (ADS)

    Filippi, Alessandra; Piano, Stefano

    2011-09-01

    The available experimental data on K-absorption on nuclei are rather old and scarce: they are not enough to understand the possible formation of aggregates of nucleons bound together by a kaon, known as "Bound Kaonic Nuclear States". The existence of such structures, suggested by a few theoretical models, has not been experimentally ascertained yet. To be observed, their width should be less than their binding energy. A possible decay channel for such states is the non mesonic one, leading to hyperon-nucleon (or light nuclei) final states. Therefore, experimental investigations of possible signatures are mainly based on the analysis of hyperon-nucleon(s) correlations (for instance, of Λp(d,t) pairs) and of invariant mass spectra. Complementary information may also be gathered from missing mass distributions. Recent experiments revived, with much larger statistics, the study of K-A absorption in light nuclei: namely, KEK-E549 studied the K-interactions on 4He, while FINUDA at DAΦNE collected a large statistics on K-6,7Li, K-9Be and K-12C. The experimental results obtained so far by the various experiments studying the K-absorption in nuclei are here summarized.

  10. Generation of neutronic thermal data in support of space nuclear propulsion

    SciTech Connect

    Mughabghab, S.; Schmidt, E.; Ludewig, H.

    1993-05-01

    The scattering kernel data for {sup 7}LiH have been generated for the first time in the temperature range 50--1000 K. This is based on a phonon distribution function derived from both experimental data and theoretical calculations. A detailed study of the variation of the moderator temperature coefficient {alpha}{sub m}(T) with temperature, T, is carried out for a typical space nuclear reactor of the particle bed type. It is established that the moderator temperature coefficient due to chemical binding effects follows the relationship {alpha}{sub m}(T) = C F{sub v}(H){sup 1.6} where F{sub v}(H) is the volume fraction of bound solid hydrogen and C is a normalization constant which depends on the moderator capture thermal cross section. The value 1.65 is to be compared with 1.54 {plus_minus} 0.06 derived in a previous study where water scattering kernels are applied. For control and safety reasons, a minimization of this positive component temperature coefficient can be most effective by operating the moderator at high temperatures. Advantages of this approach are outlined. In addition, suggestions are made to render the overall temperature coefficient negative.

  11. Generation of neutronic thermal data in support of space nuclear propulsion

    SciTech Connect

    Mughabghab, S.; Schmidt, E.; Ludewig, H.

    1993-01-01

    The scattering kernel data for [sup 7]LiH have been generated for the first time in the temperature range 50--1000 K. This is based on a phonon distribution function derived from both experimental data and theoretical calculations. A detailed study of the variation of the moderator temperature coefficient [alpha][sub m](T) with temperature, T, is carried out for a typical space nuclear reactor of the particle bed type. It is established that the moderator temperature coefficient due to chemical binding effects follows the relationship [alpha][sub m](T) = C F[sub v](H)[sup 1.6] where F[sub v](H) is the volume fraction of bound solid hydrogen and C is a normalization constant which depends on the moderator capture thermal cross section. The value 1.65 is to be compared with 1.54 [plus minus] 0.06 derived in a previous study where water scattering kernels are applied. For control and safety reasons, a minimization of this positive component temperature coefficient can be most effective by operating the moderator at high temperatures. Advantages of this approach are outlined. In addition, suggestions are made to render the overall temperature coefficient negative.

  12. Active Detection and Imaging of Nuclear Materials with High-Brightness Gamma Rays

    SciTech Connect

    Barty, C J; Gibson, D J; Albert, F; Anderson, S G; Anderson, G G; Betts, S M; Berry, R D; Fisher, S E; Hagmann, C A; Johnson, M S; Messerly, M J; Phan, H H; Semenov, V A; Shverdin, M Y; Tremaine, A M; Hartemann, F V; Siders, C W; McNabb, D P

    2009-02-26

    A Compton scattering {gamma}-ray source, capable of producing photons with energies ranging from 0.1 MeV to 0.9 MeV has been commissioned and characterized, and then used to perform nuclear resonance fluorescence (NRF) experiments. The performances of the two laser systems (one for electron production, one for scattering), the electron photoinjector, and the linear accelerator are also detailed, and {gamma}-ray results are presented. The key source parameters are the size (0.01 mm{sup 2}), horizontal and vertical divergence (6 x 10 mrad{sup 2}), duration (10 ps), spectrum and intensity (10{sup 5} photons/shot). These parameters are summarized by the peak brightness, 1.5 x 10{sup 15} photons/mm{sup 2}/mrad{sup 2}/s/0.1% bandwidth, measured at 478 keV. Additional measurements of the flux as a function of the timing difference between the drive laser pulse and the relativistic photo-electron bunch, {gamma}-ray beam profile, and background evaluations are presented. These results are systematically compared to theoretical models and computer simulations. NRF measurements performed on {sup 7}Li in LiH demonstrate the potential of Compton scattering photon sources to accurately detect isotopes in situ.

  13. NUCLEAR REACTOR

    DOEpatents

    Anderson, C.R.

    1962-07-24

    A fluidized bed nuclear reactor and a method of operating such a reactor are described. In the design means are provided for flowing a liquid moderator upwardly through the center of a bed of pellets of a nentron-fissionable material at such a rate as to obtain particulate fluidization while constraining the lower pontion of the bed into a conical shape. A smooth circulation of particles rising in the center and falling at the outside of the bed is thereby established. (AEC)

  14. NUCLEAR REACTORS

    DOEpatents

    Long, E.; Ashby, J.W.

    1958-09-16

    ABS>A graphite moderator structure is presented for a nuclear reactor compriscd of an assembly of similarly orientated prismatic graphite blocks arranged on spaced longitudinal axes lying in common planes wherein the planes of the walls of the blocks are positioned so as to be twisted reintive to the planes of said axes so thatthe unlmpeded dtrect paths in direction wholly across the walls of the blocks are limited to the width of the blocks plus spacing between the blocks.

  15. Precision X-Band Linac Technologies for Nuclear Photonics Gamma-Ray Sources

    SciTech Connect

    Hartemann, F V; Albert, F; Anderson, S G; Bayramian, A J; Cross, R R; Ebbers, C A; Gibson, D J; Houck, T L; Marsh, R A; Messerly, M J; Siders, C W; McNabb, D P; Barty, C J; Adolphsen, C E; Chu, T S; Jongewaard, E N; Tantawi, S G; Vlieks, A E; Wang, F; Wang, J W; Raubenheimer, T O; Ighigeanu, D; Toma, M; Cutoiu, D

    2011-08-31

    Nuclear photonics is an emerging field of research requiring new tools, including high spectral brightness, tunable gamma-ray sources; high photon energy, ultrahigh-resolution crystal spectrometers; and novel detectors. This presentation focuses on the precision linac technology required for Compton scattering gamma-ray light sources, and on the optimization of the laser and electron beam pulse format to achieve unprecedented spectral brightness. Within this context, high-gradient X-band technology will be shown to offer optimal performance in a compact package, when used in conjunction with the appropriate pulse format, and photocathode illumination and interaction laser technologies. The nascent field of nuclear photonics is enabled by the recent maturation of new technologies, including high-gradient X-band electron acceleration, robust fiber laser systems, and hyper-dispersion CPA. Recent work has been performed at LLNL to demonstrate isotope-specific detection of shielded materials via NRF using a tunable, quasi-monochromatic Compton scattering gamma-ray source operating between 0.2 MeV and 0.9 MeV photon energy. This technique is called Fluorescence Imaging in the Nuclear Domain with Energetic Radiation (or FINDER). This work has, among other things, demonstrated the detection of {sup 7}Li shielded by Pb, utilizing gamma rays generated by a linac-driven, laser-based Compton scattering gamma-ray source developed at LLNL. Within this context, a new facility is currently under construction at LLNL, with the goal of generating tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range, at a repetition rate of 120 Hz, and with a peak brightness in the 10{sup 20} photons/(s x mm{sup 2} x mrad{sup 2} x 0.1% bw).

  16. NUCLEAR REACTOR

    DOEpatents

    Grebe, J.J.

    1959-07-14

    High temperature reactors which are uniquely adapted to serve as the heat source for nuclear pcwered rockets are described. The reactor is comprised essentially of an outer tubular heat resistant casing which provides the main coolant passageway to and away from the reactor core within the casing and in which the working fluid is preferably hydrogen or helium gas which is permitted to vaporize from a liquid storage tank. The reactor core has a generally spherical shape formed entirely of an active material comprised of fissile material and a moderator material which serves as a diluent. The active material is fabricated as a gas permeable porous material and is interlaced in a random manner with very small inter-connecting bores or capillary tubes through which the coolant gas may flow. The entire reactor is divided into successive sections along the direction of the temperature gradient or coolant flow, each section utilizing materials of construction which are most advantageous from a nuclear standpoint and which at the same time can withstand the operating temperature of that particular zone. This design results in a nuclear reactor characterized simultaneously by a minimum critiral size and mass and by the ability to heat a working fluid to an extremely high temperature.

  17. Nuclear waste

    SciTech Connect

    Not Available

    1991-09-01

    Radioactive waste is mounting at U.S. nuclear power plants at a rate of more than 2,000 metric tons a year. Pursuant to statute and anticipating that a geologic repository would be available in 1998, the Department of Energy (DOE) entered into disposal contracts with nuclear utilities. Now, however, DOE does not expect the repository to be ready before 2010. For this reason, DOE does not want to develop a facility for monitored retrievable storage (MRS) by 1998. This book is concerned about how best to store the waste until a repository is available, congressional requesters asked GAO to review the alternatives of continued storage at utilities' reactor sites or transferring waste to an MRS facility, GAO assessed the likelihood of an MRSA facility operating by 1998, legal implications if DOE is not able to take delivery of wastes in 1998, propriety of using the Nuclear Waste Fund-from which DOE's waste program costs are paid-to pay utilities for on-site storage capacity added after 1998, ability of utilities to store their waste on-site until a repository is operating, and relative costs and safety of the two storage alternatives.

  18. Nuclear photonics

    SciTech Connect

    Habs, D.; Guenther, M. M.; Jentschel, M.; Thirolf, P. G.

    2012-07-09

    With the planned new {gamma}-beam facilities like MEGa-ray at LLNL (USA) or ELI-NP at Bucharest (Romania) with 10{sup 13}{gamma}/s and a band width of {Delta}E{gamma}/E{gamma} Almost-Equal-To 10{sup -3}, a new era of {gamma} beams with energies up to 20MeV comes into operation, compared to the present world-leading HI{gamma}S facility at Duke University (USA) with 10{sup 8}{gamma}/s and {Delta}E{gamma}/E{gamma} Almost-Equal-To 3 Dot-Operator 10{sup -2}. In the long run even a seeded quantum FEL for {gamma} beams may become possible, with much higher brilliance and spectral flux. At the same time new exciting possibilities open up for focused {gamma} beams. Here we describe a new experiment at the {gamma} beam of the ILL reactor (Grenoble, France), where we observed for the first time that the index of refraction for {gamma} beams is determined by virtual pair creation. Using a combination of refractive and reflective optics, efficient monochromators for {gamma} beams are being developed. Thus, we have to optimize the total system: the {gamma}-beam facility, the {gamma}-beam optics and {gamma} detectors. We can trade {gamma} intensity for band width, going down to {Delta}E{gamma}/E{gamma} Almost-Equal-To 10{sup -6} and address individual nuclear levels. The term 'nuclear photonics' stresses the importance of nuclear applications. We can address with {gamma}-beams individual nuclear isotopes and not just elements like with X-ray beams. Compared to X rays, {gamma} beams can penetrate much deeper into big samples like radioactive waste barrels, motors or batteries. We can perform tomography and microscopy studies by focusing down to {mu}m resolution using Nuclear Resonance Fluorescence (NRF) for detection with eV resolution and high spatial resolution at the same time. We discuss the dominating M1 and E1 excitations like the scissors mode, two-phonon quadrupole octupole excitations, pygmy dipole excitations or giant dipole excitations under the new facet of

  19. Proton calibration of low energy neutron detectors containing (6)LiF

    NASA Technical Reports Server (NTRS)

    Benton, E. V.; Frank, A. L.

    1995-01-01

    The purpose of the present calibrations is to measure the proton response of the detectors with accelerated beams having energies within the region of maximum intensities in the trapped proton spectrum encountered in near-Earth orbit. This response is compared with the responses of the spaceflight detectors when related to proton exposures. All of the spaceflight neutron measurements have been accompanied by TLD absorbed doses measurements in close proximity within the spacecraft. For purposes of comparison, the spaceflight TLD doses are assumed to be proton doses.

  20. The Nuclear Power and Nuclear Weapons Connection.

    ERIC Educational Resources Information Center

    Leventhal, Paul

    1990-01-01

    Explains problems enforcing the Nuclear Non-Proliferation Treaty (NPT) of 1968. Provides factual charts and details concerning the production of nuclear energy and arms, the processing and disposal of waste products, and outlines the nuclear fuel cycle. Discusses safeguards, the risk of nuclear terrorism, and ways to deal with these problems. (NL)