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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. 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.

  4. 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.

  5. 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.

  6. THE NEW DETECTIONS OF {sup 7}Li/{sup 6}Li ISOTOPIC RATIO IN THE INTERSTELLAR MEDIA

    SciTech Connect

    Kawanomoto, S.; Kajino, T.; Aoki, W.; Ando, H.; Noguchi, K.; Tanaka, W.; Bessell, M.; Suzuki, T. K.; Honda, S.; Izumiura, H.; Kambe, E.; Okita, K.; Watanabe, E.; Yoshida, M.; Sadakane, K.; Sato, B.; Tajitsu, A.; Takada-Hidai, M.

    2009-08-20

    We have determined the isotopic abundance ratio of {sup 7}Li/{sup 6}Li in the interstellar media (ISMs) along lines of sight to HD169454 and HD250290 using the High-Dispersion Spectrograph on the Subaru Telescope. We also observed {zeta} Oph for comparison with previous data. The observed abundance ratios were {sup 7}Li/{sup 6}Li = 8.1{sup +3.6} {sub -1.8} and 6.3{sup +3.0} {sub -1.7} for HD169454 and HD250290, respectively. These values are in reasonable agreement with those observed previously in the solar neighborhood ISMs within {+-}2{sigma} error bars and are also consistent with our measurement of {sup 7}Li/{sup 6}Li = 7.1{sup +2.9} {sub -1.6} for a cloud along the line of sight to {zeta} Oph. This is good evidence for homogeneous mixing and instantaneous recycling of the gas component in the Galactic disk. We also discuss several source compositions of {sup 7}Li, Galactic cosmic-ray interactions, stellar nucleosynthesis, and big bang nucleosynthesis.

  7. Measurement of the absolute and differential cross sections for 7Li(γ, n0)6Li

    SciTech Connect

    W.A. Wurtz, R.E. Pywell, B.E. Norum, S. Kucuker, B.D. Sawatzky, H.R. Weller, M.W. Ahmed, S. Stave

    2011-10-01

    We have measured the cross section of the photoneutron reaction channel {sup 7}Li+{gamma}{yields}{sup 6}Li(g.s.)+n where the progeny nucleus is the ground state of {sup 6}Li. We obtained the absolute cross section at photon energies 10, 11, 12, 13, 15, 20, 25, 30, and 35 MeV and also the dependence of the cross section on polar angle for all but the highest photon energy. For the energies 10 to 15 MeV we were able to use linearly polarized photons to obtain the dependence of the cross section on the photon polarization.

  8. Measuring the ratio of aqueous diffusion coefficients between 6Li +Cl - and 7Li +Cr - by osmometry

    NASA Astrophysics Data System (ADS)

    Fritz, Steven J.

    1992-10-01

    Osmotic equilibrium is a singular occurrence in the evolution of an osmotic cell because at this event the net solution flux is zero such that -J w · V¯w = J s · V¯s. At this juncture, the diffusion coefficient of the solute through the membrane (ω) equals the solute flux ( Js) divided by the osmotic pressure (ΔΠ). Because the solute permeability coefficient (ω) is related to the Fickian diffusion coefficient ( D) through the gas constant, temperature, and the membrane's thickness and tortuosity, the ratio of ω values for individual isotopic species equals the ratio of D values for the same isotopic components. A 0.9450 molal LiCl solution was placed within sealed dialysis tubing and osmoted against a kilogram of deionized water at 22°C. Osmotic equilibrium occurred at 164 ± 10 min. The ratio of ω6Li +Cl -/ω7Li +Cl - was measured to be 1.011 ± 0.003 - a value close to the square root of the mass ratio between 7LiCl and 6LiCl (= 1.012) as calculated by Graham's Law. The measured diffusion coefficient ratio was used to predict the degree of hyperfiltration-induced fractionation of Li isotopes as a function of membrane ideality. When a membrane's σ exceeds 0.95 (as is likely for low-porosity shales) the 6Li /7Li ratio on the high-pressure side of the membrane can theoretically vary by more than 0.0017.

  9. 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

    The 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 (228.2058 and 803.5581 MHz, respectively) 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 lifetimes, 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.

  10. 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.

  11. 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.

  12. Identification of lithium-sulfur battery discharge products through 6Li and 33S solid-state MAS and 7Li solution NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Huff, Laura A.; Rapp, Jennifer L.; Baughman, Jessi A.; Rinaldi, Peter L.; Gewirth, Andrew A.

    2015-01-01

    6Li and 33S solid-state magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy was used to identify the discharge products in lithium-sulfur (Li-S) battery cathodes. Cathodes were stopped at different potentials throughout battery discharge and measured ex-situ to obtain chemical shifts and T2 relaxation rates of the products formed. The chemical shifts in the spectra of both 6Li and 33S NMR demonstrate that long-chain, soluble lithium polysulfide species formed at the beginning of discharge are indistinguishable from each other (similar chemical shifts), while short-chain, insoluble polysulfide species that form at the end of discharge (presumably Li2S2 and Li2S) have a different chemical shift, thus distinguishing them from the soluble long-chain products. T2 relaxation measurements of discharged cathodes were also performed which resulted in two groupings of T2 rates that follow a trend and support the previous conclusions that long-chain polysulfide species are converted to shorter chain species during discharge. Through the complementary techniques of 1-D 6Li and 33S solid-state MAS NMR spectroscopy, solution 7Li and 1H NMR spectroscopy, and T2 relaxation rate measurements, structural information about the discharge products of Li-S batteries is obtained.

  13. Alpha spectroscopic factors for 6Li, 7Li, 9Be and 12C from the ( overlinep, pα) reaction at 296 MeV

    NASA Astrophysics Data System (ADS)

    Yoshimura, T.; Okihana, A.; Warner, R. E.; Chant, N. S.; Roos, P. G.; Samanta, C.; Kakigi, S.; Koori, N.; Fujiwara, M.; Matsuoka, N.; Tamura, K.; Kubo, E.; Ushiro, K.

    1998-10-01

    Three-body breakup cross sections and analyzing powers for the 6Li, 7Li, 9Be and 12C( overlinep,pα) reactions were measured at an incident energy of 296 MeV. Data were analyzed using the plane wave impulse approximation (PWIA) and the distorted wave impulse approximation (DWIA) and compared with previous studies. DWIA calculations reproduce shapes of projected spectra and analyzing power distributions fairly well with the exception of the 12C( overlinep,pα) 8Be reactions. Extracted spectroscopic factors for 6Li, 9Be and 12C are larger than those found in the previous studies. In contrast, extracted spectroscopic factors for 7Li agree with the previous work. This work suggests that the spectroscopic factor for 6Li is ˜ 0.8, independent of incident energies and reaction types.

  14. Prediction of {sup 2}D Rydberg energy levels of {sup 6}Li and {sup 7}Li based on very accurate quantum mechanical calculations performed with explicitly correlated Gaussian functions

    SciTech Connect

    Bubin, Sergiy; Sharkey, Keeper L.; Adamowicz, Ludwik

    2013-04-28

    Very accurate variational nonrelativistic finite-nuclear-mass calculations employing all-electron explicitly correlated Gaussian basis functions are carried out for six Rydberg {sup 2}D states (1s{sup 2}nd, n= 6, Horizontal-Ellipsis , 11) of the {sup 7}Li and {sup 6}Li isotopes. The exponential parameters of the Gaussian functions are optimized using the variational method with the aid of the analytical energy gradient determined with respect to these parameters. The experimental results for the lower states (n= 3, Horizontal-Ellipsis , 6) and the calculated results for the higher states (n= 7, Horizontal-Ellipsis , 11) fitted with quantum-defect-like formulas are used to predict the energies of {sup 2}D 1s{sup 2}nd states for {sup 7}Li and {sup 6}Li with n up to 30.

  15. Ground state hyperfine splitting in 6,7Li atoms and the nuclear structure.

    PubMed

    Puchalski, Mariusz; Pachucki, Krzysztof

    2013-12-13

    Relativistic and QED corrections are calculated for a hyperfine splitting of the 2S1/2 ground state in 6,7Li atoms with a numerically exact account for electronic correlations. The resulting theoretical predictions achieve such a precision level that, by comparison with experimental values, they enable determination of the nuclear properties. In particular, the obtained results show that the 7Li nucleus, having a charge radius smaller than 6Li, has about a 40% larger Zemach radius. Together with known differences in the electric quadrupole and magnetic dipole moments, this calls for a deeper understanding of the Li nuclear structure.

  16. 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)

  17. 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.

  18. THE RADIATIVE NEUTRON CAPTURE ON 2H, 6Li, 7Li, 12C AND 13C AT ASTROPHYSICAL ENERGIES

    NASA Astrophysics Data System (ADS)

    Dubovichenko, Sergey; Dzhazairov-Kakhramanov, Albert; Burkova, Natalia

    2013-05-01

    The continued interest in the study of radiative neutron capture on atomic nuclei is due, on the one hand, to the important role played by this process in the analysis of many fundamental properties of nuclei and nuclear reactions, and, on the other hand, to the wide use of the capture cross-section data in the various applications of nuclear physics and nuclear astrophysics, and, also, to the importance of the analysis of primordial nucleosynthesis in the Universe. This paper is devoted to the description of results for the processes of the radiative neutron capture on certain light atomic nuclei at thermal and astrophysical energies. The consideration of these processes is done within the framework of the potential cluster model (PCM), general description of which was given earlier. The methods of usage of the results obtained, based on the phase shift analysis intercluster potentials, are demonstrated in calculations of the radiative capture characteristics. The considered capture reactions are not part of stellar thermonuclear cycles, but involve in the basic reaction chain of primordial nucleosynthesis in the course of the Universe formation.

  19. Observations of 6Li in Galactic Stars

    NASA Astrophysics Data System (ADS)

    Hobbs, L. M.

    2000-05-01

    Several important goals have motivated observationally challenging attempts to measure 6Li/7Li isotopic ratios and, hence, 6Li abundances in stars. In particular, a general understanding, based on cosmic-ray spallation reactions, of the nucleosynthetic origins of the very low Galactic abundances of 6Li, Be, and B has followed from measurements of both the relative and the absolute abundances of these various, related isotopes. In the cases of Be and B, such data are currently available for 20 or more stars that span a wide range of metallicity, i.e. age. In contrast, nuclear burning of the very fragile 6Li nuclei during stellar contraction to the main sequence generally reduces the surface abundance of this lighter isotope below the observable limit. A few relatively nearby stars of low metallicity which are found close to the Population II main-sequence turnoff during later hydrogen burning seem to constitute the observable exceptions. Spectra of very high quality, typically with R > 100,000 and S/N > 400 at V > 9.0, are needed to reveal the small extra asymmetry and the small extra width that are introduced into the profile of the isotopically blended Li I 6707 A line by the small fractions of 6Li detected so far. Precise measurements of (or, in all but a few cases, uppper limits on) the 6Li/7Li ratio are now available for almost 30 stars. At a ratio 6Li/7Li = 0.06, the first positive detection of stellar 6Li was achieved in 1993 for the turnoff halo star HD 84937, by Smith, Lambert, & Nissen. Probable detections of the lighter isotope at generally similar isotopic ratios have since been reported for four additional metal-poor stars. The imminent availability of more telescopes in the 8m to 10m class promises a rewarding extension of this effort to a relatively large number of excellent, fainter 6Li candidates.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. {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.

  5. {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.

  6. 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.

  7. Nuclear microprobe analysis of 7Li profile induced in HfB 2 by a neutron irradiation

    NASA Astrophysics Data System (ADS)

    Simeone, D.; Deschanels, X.; Gosset, D.; Bonal, J. P.; Berthoumieux, E.

    2001-09-01

    HfB 2, a solid poor in boron, was irradiated by thermal neutrons in an experimental reactor. Using a nuclear microprobe, we have tracked lithium atoms produced by the 10B( n, α) 7Li reaction and compared the calculated and measured 7Li profiles in HfB 2 irradiated samples. This comparison shows that Li atoms do not diffuse during irradiation (323 K). The comparison of non-annealed and annealed irradiated HfB 2 plates clearly shows that lithium atoms do not migrate out of samples even at high temperatures (1273 K). These results associated to previous transmission electron microscopy (TEM) observations seem to show that lithium atoms are trapped by dislocation loops created by displacement cascades during neutron irradiation.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. Charge transfer in Li/CFx-silver vanadium oxide hybrid cathode batteries revealed by solid state 7Li and 19F nuclear magnetic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Sideris, Paul J.; Yew, Rowena; Nieves, Ian; Chen, Kaimin; Jain, Gaurav; Schmidt, Craig L.; Greenbaum, Steve G.

    2014-05-01

    Solid state 7Li and 19F magic angle spinning nuclear magnetic resonance (MAS NMR) experiments are conducted on several cathodes containing CFx-Silver vanadium oxide (CFx-Ag2V4O11) hybrid cathodes discharged to 50% depth of discharge (DoD) and stored at their open-circuit voltage for a period of one and three months. Three carbonaceous sources for the CFx phase are investigated: petroleum coke-based, fibrous, and mixed fibrous. For each hybrid cathode, a measurable increase in the relative amount of lithium fluoride is observed after a three month resting period in both the 7Li and 19F NMR spectra. These changes are attributed to lithium ion migration from the silver vanadium oxide to the CFx phase during the resting period, and help clarify the mechanism behind high power handling capability of this cathode.

  16. 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.

  17. Coulomb-nuclear interference with {sup 6}Li: Isospin character of the 2{sub 1}{sup +} excitation in {sup 70,72,74}Ge

    SciTech Connect

    Barbosa, M.D.L.; Borello-Lewin, T.; Horodynski-Matsushigue, L.B.; Duarte, J.L.M.; Rodrigues, C.L.; Rodrigues, M.R.D.; Ukita, G.M.

    2005-02-01

    Ratios of B(E2) to B(IS2), that is, of the reduced quadrupole transition probabilities related, respectively, to charge and mass were extracted through Coulomb-nuclear interference (CNI) for the excitation of the 2{sub 1}{sup +} states in {sup 70,72,74}Ge, with a relative accuracy of less than 4%. For this purpose, the CNI angular distributions associated with the inelastic scattering of 28-MeV incident {sup 6}Li ions accelerated by the Sao Paulo Pelletron, and momentum analyzed by the Enge magnetic spectrograph were interpreted within the DWBA-DOMP approach (distorted wave approximation for the scattering process and deformed optical model for the structure representation) with global {sup 6}Li optical parameters. The present CNI results demonstrate an abrupt change in the B(E2)/B(IS2) ratio for {sup 74}Ge: although for {sup 70,72}Ge, values of the order of 1.0 or slightly higher were obtained, this ratio is 0.66 (7) for {sup 74}Ge. The heavier Ge isotope is thus one of the few nuclei that, so far, have been shown to present clear mixed symmetry components in their ground-state band.

  18. 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.

  19. 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.

  20. 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.

  1. Cell killing, nuclear damage and apoptosis in Chinese hamster V79 cells after irradiation with heavy-ion beams of (16)O, (12)C and (7)Li.

    PubMed

    Pathak, Rupak; Dey, Subrata Kumar; Sarma, Asiti; Khuda-Bukhsh, Anisur Rahman

    2007-08-15

    Chinese hamster V79 cells were exposed to high LET (linear energy transfer) (16)O-beam (625keV/mum) radiation in the dose range of 0-9.83Gy. Cell survival, micronuclei (MN), chromosomal aberrations (CA) and induction of apoptosis were studied as a follow up of our earlier study on high LET radiations ((7)Li-beam of 60keV/mum and (12)C-beam of 295keV/mum) as well as (60)Co gamma-rays. Dose dependent decline in surviving fraction was noticed along with the increase of MN frequency, CA frequency as well as percentage of apoptosis as detected by nuclear fragmentation assay. The relative intensity of DNA ladder, which is a useful marker for the determination of the extent of apoptosis induction, was also increased in a dose dependent manner. Additionally, expression of tyrosine kinase lck-1 gene, which plays an important role in response to ionizing radiation induced apoptosis, was increased with the increase of radiation doses and also with incubation time. The present study showed that all the high LET radiations were generally more effective in cell killing and inflicting other cytogenetic damages than that of low LET gamma-rays. The dose response curves revealed that (7)Li-beam was most effective in cell killing as well as inducing other nuclear damages followed by (12)C, (16)O and (60)Co gamma-rays, in that order. The result of this study may have some application in biological dosimetry for assessment of genotoxicity in heavy ion exposed subjects and in determining suitable doses for radiotherapy in cancer patients where various species of heavy ions are now being generally used.

  2. Low-energy 7Li(t, α)6He cross sections

    NASA Astrophysics Data System (ADS)

    Cecil, F. E.; Fahlsing, R. F.; Jarmie, Nelson; Hardekopf, R. A.; Martinez, R.

    1983-01-01

    The thick target yield of the reaction 7Li(t, α) has been measured to the ground and first excited states of 6He for bombarding energies between 70 and 110 keV. These yields are used to deduce the reaction cross sections and astrophysical S factors at intermediate values of energy. The zero energy S factor S(0) for 7Li(t, α)6He*(1.81) is 14+/-2.5 MeVb. Applications of the measured values of the cross section for this reaction to the diagnostics of high temperature tritium plasmas are discussed. Efforts to detect alphas from induced reactions on other light targets 6Li, 9Be, 10B, and 11B are discussed. NUCLEAR REACTIONS 7Li(t, α)6He, 9Be(t, α)8Li, 11B(t, α)10Be Et=70-110 keV, θ=150°. Measured thick target yields. Deduced σ(θ, E), S(θ, E).

  3. 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.

  4. 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.

  5. A CBNM 6Li spike isotopic reference material CBNM-IRM-615

    NASA Astrophysics Data System (ADS)

    Lamberty, A.; Verbruggen, A.; Hendrickx, F.; de Bièvre, P.

    1992-04-01

    A 6Li spike isotopic reference material CBNM-IRM-615 has been prepared in the form of Li2CO3 in HCl. The lithium concentration, (4.001 ± 0.028) × 10-3 mol Li kg-1, was determined by isotope dilution mass spectrometry against NBS SRM 924 Li2CO3. CBNM-IRM-615 is certified for its isotopic composition: 95.610 ± 0.025 amount % 6Li; 4.390 ± 0.025 amount % 7Li; and for its 6Li concentration: 3.825 ± 0.027 × 10-3 mol 6Li kg-1 of solution. Uncertainties are 2s or the equivalent estimate thereof. The isotopic reference material is available in quartz ampoules containing approximately 5 g of solution. Using this spike isotopic reference material. 7Li or total Li concentrations in unknown samples can be determined by isotope dilution mass spectrometry via a measurement of the molar isotope dilution ratio RB = 6Li/7Li in the blend.

  6. 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.

  7. 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.

  8. 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.

  9. Analogs of the giant dipole and spin-dipole resonances in {sup 4}He and in {alpha} clusters of {sup 6,7}Li studied by the {sup 4}He,{sup 6,7}Li({sup 7}Li,{sup 7}Be{gamma}) reactions

    SciTech Connect

    Nakayama, S.; Matsumoto, E.; Fushimi, K.; Hayami, R.; Kawasuso, H.; Yasuda, K.; Yamagata, T.; Akimune, H.; Ikemizu, H.; Asaji, S.; Ishida, T.; Kudoh, T.; Sagara, K.; Fujiwara, M.; Hashimoto, H.; Kawase, K.; Nakanishi, K.; Oota, T.; Yosoi, M.; Greenfield, M. B.

    2008-07-15

    We studied analogs of the giant dipole resonance (GDR) and spin-dipole resonance (SDR) in {sup 4}He and in the {alpha} clusters of {sup 6,7}Li via the ({sup 7}Li,{sup 7}Be{gamma}) reactions on {sup 4}He, {sup 6}Li, and {sup 7}Li at an incident energy of 455 MeV and at a scattering angle of 0 deg. by measuring spin-nonflip and spin-flip spectra. The reaction Q-values for the analogs of the GDR and SDR in the {alpha} clusters of {sup 6,7}Li were found to be more negative than those in {sup 4}He by 2.0{+-}0.5 MeV. The ratios of the cross section for the analog of the GDR to that for the analog of the SDR in {sup 4}He and in the {alpha} clusters of {sup 6}Li and {sup 7}Li were found to be the same within errors, 0.5{+-}0.1. The cross sections for the analogs of the GDR as well as those for the analogs of the SDR in the {alpha} clusters of {sup 6,7}Li were 0.6{approx}0.8 times smaller than those in {sup 4}He. These results suggest that excitations of {alpha} clusters embedded in nuclei are suppressed as compared with excitations of free {alpha} particles.

  10. {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.

  11. 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.

  12. Relation between (e, e') sum rules in 6, 7Li and 4He nuclei: Experiment and cluster model

    NASA Astrophysics Data System (ADS)

    Efros, V. D.; Timchenko, I. S.; Buki, A. Yu.

    2016-09-01

    The sums over ( e, e') spectra of 6Li and 7Li nuclei which correspond to the longitudinal sum rule are studied. It is suggested that due to the cluster structure of the lithium isotopes these sums may approximately be expressed in terms of such a sum pertaining to the α-particle. Calculation of these sums is performed in the framework of cluster models with antisymmetrization done with respect to all the nucleons. At momentum transfers higher than 0.8 fm-1 the relations expressing the A = 6 or 7 sum in terms of the A = 4 sum prove to be valid with rather high accuracy. In the region of momentum transfers around 1 fm-1 the longitudinal correlation functions of 6Li and 7Li nuclei are found to be close to that of the α-particle. Basing on this, the difference between the q values at which the high- q limit of the inelastic sum rule is reached in the 6, 7Li cases and the 4He case is explained. The experimental longitudinal sums in the range between 0.450 and 1.625 fm-1 are employed to perform comparison with the theoretical sum rule calculated in the framework of cluster models. Out of the experimental sums, those in the range between 0.750 and 1.000 fm-1 in the 6Li case and between 0.750 and 1.125 fm-1 in the 7Li case are obtained in the present work. In the 6 Li case a complete agreement between experiment and the calculated sum rule is found while in the 7Li case an agreement only at a qualitative level is observed.

  13. 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

  14. High-pressure superconducting phase diagram of 6Li: isotope effects in dense lithium.

    PubMed

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

    2015-01-01

    We measured the superconducting transition temperature of (6)Li between 16 and 26 GPa, and report the lightest system to exhibit superconductivity to date. The superconducting phase diagram of (6)Li is compared with that of (7)Li through simultaneous measurement in a diamond anvil cell (DAC). Below 21 GPa, Li exhibits a direct (the superconducting coefficient, α, T(c) proportional 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.

  15. 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.

  16. 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.

  17. 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.

  18. Lattice dynamics in Bosonic 7 Li

    NASA Astrophysics Data System (ADS)

    Chen, Huiyao Y.; Jung, Minwoo; Rabinowitz, Jacob; Madjarov, Ivaylo S.; Cheung, Hil F. H.; Patil, Yogesh Sharad; Vengalattore, Mukund

    2016-05-01

    The light mass and strong spin-dependent interactions in 7 Li make it an attractive candidate to study Bosonic quantum magnetism and lattice dynamics in regimes where rapid dynamics is favored, e.g. percolative transport and entropy segregation. Such studies require large ensembles of quantum degenerate 7 Li atoms which has proved to be a technical challenge. We describe our ongoing efforts to overcome this challenge using Raman sideband cooling (RSC). In addition to enabling the rapid production of large degenerate gases, RSC is also a very powerful means of local control of lattice gas dynamics. Extending this to a spinful 7 Li Bose gas will also enable studies of transport and defect dynamics in F=1 lattice gases. This work is supported by the ARO MURI on non-equilibrium dynamics.

  19. Analyzing Powers of the ^58Ni(^6 Li,d)^62Zn Reaction at E(^6Li)=34 MeV and the D State of ^6Li.

    NASA Astrophysics Data System (ADS)

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

    1996-10-01

    We continue our studies of the D states of light nuclei with ^6Li, where the magnitude and sign of the ratio of the asymptotic normalization constants, η(^6Li), have not yet been determined.(A. M. Eiró et al.), Few Body Systems, Suppl. 8, 369 (1995). Calculations have shown that tensor analyzing powers of transfer reactions induced by polarized ^6Li ions show considerable sensitivity to the ^6Li D state.^2 Using the FSU polarized ^6Li beam and Si ΔE-E detector telescopes, we have measured cross section and vector and tensor analyzing powers (VAP and TAP) of the ^58Ni(^6 Li,d)^62Zn (0^+ g.s.) reaction at E(^6Li)=34 MeV for 10^circ<=θ_lab<= 40^circ. A DWBA analysis of cross section and VAP strongly suggests that the reaction proceeds via direct α transfer. In addition, an analysis including coupling to the 3^+ state in ^6Li is underway. Comparisons of these data with preliminary calculations and implications for η(^6Li) will be presented.

  20. 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

  1. 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.

  2. 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.

  3. Compounds of 6Li and natural Li for EPR dosimetry in photon/neutron mixed radiation fields.

    PubMed

    Lund, E; Gustafsson, H; Danilczuk, M; Sastry, M D; Lund, A

    2004-05-01

    Formates and dithionates of 6Li, enriched and 7Li in natural composition of Li offer a possibility to measure the absorbed dose from photons and thermal neutrons in a mixed radiation field for instance at a boron neutron capture therapy (BNCT) facility. Tests with formates and dithionates of enriched 6Li and lithium compounds with natural composition have been performed at the BNCT facility at Studsvik, Sweden. Irradiations have been performed at 3 cm depth in a Perspex phantom in a fluence rate of thermal neutrons 1.8 x 10(9) n cm(-2) s(-1). The compounds were also irradiated in a pure X-ray field from a 4MV linear accelerator at 5 cm depth in a phantom with accurately determined absorbed doses. The signal intensity and shape was investigated within 3 h after the irradiation. A single line spectrum attributed to the CO2- radical was observed after irradiation of lithium formate. An increase in line width occurring after neutron irradiation in comparison with photon irradiation of the 6Li sample was attributed to dipolar broadening between CO2- radicals trapped in the tracks of the alpha particles. A spectrum due to the SO3- radical anion was observed after irradiation of lithium dithionate. The signal amplitude increased using the 6Li in place of the Li with natural composition of isotopes, in studies with low energy X-ray irradiation. Due to the decreased line width, caused by the difference in g(N) and I between the isotopes, the sensitivity with 6Li dithionate may be enhanced by an order of magnitude compared to alanine dosimetry. After comprehensive examination of the different combinations of compounds with different amounts of 6Li and 7Li regarding dosimetry, radiation chemistry and EPR properties these dosimeter material might be used for dose determinations at BNCT treatments and for biomedical experiments. Interesting properties of the radical formation might be visible due to the large difference in ionization density of neutrons compared to photons.

  4. 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.

  5. 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

  6. 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.

  7. {alpha} resonance structure in {sup 11}B studied via resonant scattering of {sup 7}Li+{alpha}

    SciTech Connect

    Yamaguchi, H.; Hashimoto, T.; Hayakawa, S.; Binh, D. N.; Kahl, D.; Kubono, S.; Wakabayashi, Y.; Kawabata, T.; Teranishi, T.

    2011-03-15

    A new measurement of {alpha} resonant scattering on {sup 7}Li was performed over the excitation energy of 10.2-13.0 MeV in {sup 11}B at the low-energy RI beam facility CNS Radioactive Ion Beam separator (CRIB) of the Center for Nuclear Study (CNS), University of Tokyo. The excitation function of {sup 7}Li+{alpha} at 180 deg. in the center-of-mass system was successfully measured for the first time with the inverse kinematics method, providing important information on the {alpha} cluster structure in {sup 11}B and the reaction rate of {sup 7}Li({alpha},{gamma}), which is relevant to the {sup 11}B production in the {nu} process in core-collapse supernovae. The excitation function of the {sup 7}Li({alpha},p) reaction cross section for 11.7-13.1 MeV was also measured.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Method for determining fast-alpha-particle confinement in tokamak plasmas using resonant nuclear reactors

    SciTech Connect

    Cecil, F.E.; Zweben, S.J.; Medley, S.S.

    1986-03-01

    The resonant nuclear reactions D(..cap alpha..,..gamma..)/sup 6/Li, /sup 6/Li(..cap alpha..,..gamma..)/sup 10/B, and /sup 7/Li(..cap alpha..,..gamma..)/sup 11/B are examined as diagnostics of fast-alpha-particle confinement in tokamak plasmas. Gamma rays from these resonant reactions with energies from 2.1 MeV to 9.2 MeV may be used to infer the alpha-particle population between energies of 0.4 MeV and 2.6 MeV. The ratio of these alpha-burnup reactions to the reactions T(D,..gamma..)/sup 5/He and /sup 3/He(D,..gamma..)/sup 5/Li provides a technique for the measurement of alpha confinement.

  16. 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.

  17. An update on the big bang nucleosynthesis prediction for 7Li: the problem worsens

    NASA Astrophysics Data System (ADS)

    Cyburt, Richard H.; Fields, Brian D.; Olive, Keith A.

    2008-11-01

    The lithium problem arises from the significant discrepancy between the primordial 7Li 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 7Li/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 for3He(α,γ)7Be 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 predicts7Li/H = (5.24-0.67+0.71) × 10-10. The central value represents an increase by 23%, most of which is due to the upward shift in the3He(α,γ)7Be rate. More significant is the reduction in the7Li/H uncertainty by almost a factor of 2, tracking the reduction in the3He(α,γ)7Be error bar. These changes exacerbate the Li problem; the discrepancy is now a factor 2.4 or 4.2σ (from globular cluster stars) to 4.3 or 5.3σ (from halo field stars). Possible resolutions to the lithium problem are briefly reviewed, and key experimental and astronomical measurements highlighted.

  18. The influence of temperature and salinity on the Li/Ca and d7Li of inorganic and biogenic carbonates

    NASA Astrophysics Data System (ADS)

    Marriott, C.; Staubwasser, M.; Crompton, R.; Henderson, G.

    2003-04-01

    Lithium is the sixth most abundant metal in the ocean. It is conservative with a residence time of around 1Ma and has two stable isotopes ^7Li and ^6Li that are not actively involved in biological processes. Isotopic fractionation is observed during incorporation into calcium carbonate but no previous work has systematically examined the controls on this fractionation. We have investigated Li incorporation and isotopic fraction in both inorganically precipitated calcite and coralline aragonite (1). In both cases there is an inverse correlation of Li concentration with temperature and no significant variation in isotopic fractionation. A decrease in D Li/Ca from 0.0092 to 0.0030 is seen over a temperature range of 5--30^oC, whilst an offset of approximately -8.5 ppm is seen in the δ^7Li ratio relative to the growth solution. The temperature dependence of Li/Ca has an increased sensitivity at low temperatures and might therefore be useful in examining changes in bottom water temperature. We are now investigating Li/Ca and δ^7Li of foraminifera. Previous work (2) has suggested little variability in Li/Ca with temperature, although this was for samples from warmer water where Li/Ca is not sensitive. In this study, Uvigerina are examined in a series of core top samples from the Arabian Sea with a depth range of 95--1800m and corresponding temperature range of 5--20^oC. A series of inorganic calcite samples have also been precipitated in order to examine the effect of salinity on Li/Ca, δ^7Li and δ44Ca over a salinity range of 10--50 psu. The distribution coefficient of Li shows a positive correlation with salinity over this range. δ^7Li and δ44Ca measurements for these samples are presently being analysed. (1) Marriott et al., 2002, GCA, 66, A485 (2) Delaney et al., 1985, GCA, 49, 1327

  19. 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].

  20. Three-body parameter for Efimov states in 6Li

    NASA Astrophysics Data System (ADS)

    Huang, Bo; O'Hara, Kenneth M.; Grimm, Rudolf; Hutson, Jeremy M.; Petrov, Dmitry S.

    2014-10-01

    We present a state-of-the-art reanalysis of experimental results on Efimov resonances in the three-fermion system of 6Li. We discuss different definitions of the three-body parameter (3BP) for Efimov states and adopt a definition that excludes effects due to deviations from universal scaling for low-lying states. We develop a finite-temperature model for the case of three distinguishable fermions and apply it to the excited-state Efimov resonance to obtain the most accurate determination to date of the 3BP in an atomic three-body system. Our analysis of ground-state Efimov resonances in the same system yields values for the three-body parameter that are consistent with the excited-state result. Recent work has suggested that the reduced 3BP for atomic systems is a near-universal quantity, almost independent of the particular atom involved. However, the value of the 3BP obtained for 6Li is significantly (˜20 % ) different from that previously obtained from the excited-state resonance in Cs. The difference between these values poses a challenge for theory.

  1. 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 %.

  2. 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.

  3. Note: 6Li III light intensity observation for 6Li3+ ion beam operation at Hyper-Electron Cyclotron Resonance ion source.

    PubMed

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

    2014-12-01

    The light intensity of (6)Li III line spectrum at λ = 516.7 nm was observed during (6)Li(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, (6)Li III line intensity observation conducted in this study gives new insights into its simplification of this process. The light intensity of (6)Li III line spectrum from the ECR plasma was found to have a strong correlation with the extracted (6)Li(3+) beam intensity from the RIKEN Azimuthal Varying Field cyclotron. PMID:25554343

  4. 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.

  5. Observation of interspecies 6Li-133Cs Feshbach resonances

    NASA Astrophysics Data System (ADS)

    Repp, M.; Pires, R.; Ulmanis, J.; Heck, R.; Kuhnle, E. D.; Weidemüller, M.; Tiemann, E.

    2013-01-01

    We report on the observation of 19 interspecies Feshbach resonances in an optically trapped ultracold Bose-Fermi mixture of 133Cs and 6Li in the two energetically lowest spin states. We assign the resonances to s- and p-wave molecular channels by a coupled-channels calculation, resulting in an accurate determination of LiCs ground-state potentials. Fits of the resonance position based on the undressed asymptotic bound state model do not provide the same level of accuracy as the coupled-channels calculation. Several broad s-wave resonances provide prospects to create fermionic LiCs molecules with a large dipole moment via Feshbach association followed by stimulated Raman passage. Two of the s-wave resonances overlap with a zero crossing of the Cs scattering length, which offers prospects for the investigation of polarons in an ultracold Li-Cs mixture.

  6. Microscopic model analysis of the 6He, 6Li+28Si total reaction cross sections at the energy range 5-50 A MeV

    SciTech Connect

    Lukyanov, K. V.; Kukhtina, I. N.; Lukyanov, V. K.; Penionzhkevich, Yu. E.; Sobolev, Yu. G.; Zemlyanaya, E. V.

    2007-05-22

    The existing and some preliminary experimental data on the total cross sections of the 4,6He, 6,7Li+28Si reactions at energies E=5-50 A MeV are demonstrated. The data on 6Li,6He+28Si are analyzed in the framework of the microscopic optical potential with real and imaginary parts obtained with a help of the double-folding procedure and by using the current models of densities of the projectile nuclei. Besides, the microscopic double-folding Coulomb potential is calculated and its effect on cross sections is compared with that when one applies the traditional Coulomb potential of the uniform charge distribution. The semi-microscopic potentials are constructed from both the renormalized microscopic potentials and their derivatives to take into account collective motion effect and to improve an agreement with experimental data.

  7. 7Li NMR study of intercalated lithium in curved carbon lattices

    NASA Astrophysics Data System (ADS)

    Gerald, R. E.; Johnson, C. S.; Rathke, J. W.; Klingler, R. J.; Sandí, G.; Scanlon, L. G.

    A device was invented that permits nuclear magnetic resonance (NMR) analysis of the internal elements of a coin cell battery. The Coin Cell Battery Imager was used to record wideline 7Li NMR spectra of the lithium ions that were electrochemically intercalated into three different types of carbon-based materials. The samples included graphite, corannulene, and carbon derived from sepiolite clay. All samples were excised from 2032-size coin cells that were cycled multiple times and left in a discharged state (i.e., fully lithiated). A comparison of the 7Li NMR spectra recorded for the three carbons revealed that the curved carbon lattice derived from sepiolite affected the lithium resonances in a manner similar to that observed for the curved molecule corannulene, while both differed from the flat lattice of graphite. In addition, it was possible to observe lithium dendrites on the surface of a hard carbon electrode even in the presence of a large lithium counter electrode using NMR imaging techniques.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  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. Photoproduction of {pi}{pi} Pairs off {sup 7}Li

    SciTech Connect

    Maghrbi, Yasser

    2011-10-21

    This paper reports on the quasi-free photoproduction of {pi}{sup 0}{pi}{sup 0} and {pi}{sup 0}{pi}{sup +/-} pairs from {sup 7}Li in view of the in-medium properties of hadrons. Measurements have been done using the CB/TAPS detector setup and the Glasgow photon tagging spectrometer for incident photon energies up to 820 MeV. At small invariant masses, an enhancement of the neutral invariant mass distributions is seen compared to the mixed charged channel and could be explained either by an in-medium modification of the {pi}{pi} interaction in the I = J = 0 channel or by effects related to the final state interactions.

  15. {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)

  16. Extended optical model analyses of elastic scattering and fusion cross section data for the {sup 7}Li+{sup 208}Pb system at near-Coulomb-barrier energies using a folding potential

    SciTech Connect

    So, W. Y.; Udagawa, T.; Kim, K. S.; Hong, S. W.; Kim, B. T.

    2007-08-15

    Simultaneous {chi}{sup 2} analyses previously made for elastic scattering and fusion cross section data for the {sup 6}Li+{sup 208}Pb system are extended to the {sup 7}Li+{sup 208}Pb system at near-Coulomb-barrier energies based on the extended optical model approach, in which the polarization potential is decomposed into direct reaction (DR) and fusion parts. Use is made of the double folding potential as a bare potential. It is found that the experimental elastic scattering and fusion data are well reproduced without introducing any normalization factor for the double folding potential and that both the DR and fusion parts of the polarization potential determined from the {chi}{sup 2} analyses satisfy separately the dispersion relation. Further, we find that the real part of the fusion portion of the polarization potential is attractive while that of the DR part is repulsive except at energies far below the Coulomb barrier energy. A comparison is made of the present results with those obtained from the coupled discretized continuum channels calculations and a previous study based on the conventional optical model with a double folding potential. We also compare the present results for the {sup 7}Li+{sup 208}Pb system with the analysis previously made for the {sup 6}Li+{sup 208}Pb system.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Brain lithium measurements with (7)Li magnetic resonance spectroscopy (MRS): a literature review.

    PubMed

    Soares, J C; Boada, F; Keshavan, M S

    2000-05-01

    7Li magnetic resonance spectroscopy (MRS) has been successfully used in recent years as a new tool to measure brain tissue lithium concentrations in vivo. After demonstration of its feasibility in animal studies over a decade ago, human investigations have characterized the brain pharmacokinetics of lithium. Preliminary studies have investigated brain pharmacokinetic correlates of clinical response in the treatment of bipolar disorder patients, with indication of possible clinical relevance of 7Li MRS measures. In this paper we reviewed the accumulated literature in this area, and discuss possible directions for this research in the context of preliminary studies conducted by our group that demonstrated the feasibility of 7Li MRS at 3 T.

  2. "Hyperfine Splitting, Isotope Shift, and Level Energy of the 3S States of Li-6, Li-7."

    SciTech Connect

    Bushaw, Bruce A. ); Nortershauser, W.; Ewald, G; Dax, A ..; Drake, Gordon W. F.

    2003-07-25

    High-precision laser spectroscopy on lithium isotopes is of fundamental interest, experimentally as well as theoretically. The lithium atom has long served as a test system for the calculation of various atomic properties in few-electron atoms and significant advances have been made in the last decade[1-3]. Recently, calculations of transition energies for the 22S1/2 -> 32S1/2 and the 22S1/2 -> 22P1/2, 3/2 transitions and of the mass-dependant isotope shift (IS) in these transitions have been reported with a relative accuracy of better than 1 X 10-7 and 5 x 10-6, respectively[4, 5]. These calculations are the foundation for experimental efforts, currently underway at GSI Darmstadt, Germany, to determine the root-mean-square (rms) charge radius of the unstable lithium isotopes[6, 7]. The basic principle is that if all mass-dependent contributions to the IS can be calculated with sufficient accuracy, the residual discrepancy between the experimentally observed shift and the computational result is caused by the difference Rrms in the nuclear charge radii between the isotopes[8]. This approach has previously been used to determine the difference between the charge radii of 6,7Li from isotope shift measurements in the helium-like system Li+[9] and the rms charge radius of 3He[10]. In both cases, results were in agreement with nuclear scattering data but with substantially improved accuracy. Data on nuclear charge radii is of fundamental importance for nuclear physics, but for lithium it has been determined by electron scattering only for the stable isotopes 6,7Li. Among the unstable isotopes, the study of 11Li is of particular importance since it consists of a 9Li core surrounded with a halo formed by two loosely-bound neutrons[11]. The mass radius of 11Li has been determined from nuclear cross section measurements[12], but such experiments do not allow a nuclear-model independent determination of charge radius. Thus, the question whether the halo neutrons have any

  3. Nuclear Charge Radii of {sup 9,11}Li: The Influence of Halo Neutrons

    SciTech Connect

    Sanchez, R.; Ewald, G.; Dax, A.; Goette, S.; Kirchner, R.; Kluge, H.-J.; Kuehl, Th.; Wojtaszek, A.; Noertershaeuser, W.; Albers, D.; Behr, J.; Bricault, P.; Dilling, J.; Dombsky, M.; Lassen, J.; Levy, C.D.P.; Pearson, M.R.; Prime, E.J.; Ryjkov, V.; Bushaw, B.A.

    2006-01-27

    The nuclear charge radius of {sup 11}Li has been determined for the first time by high-precision laser spectroscopy. On-line measurements at TRIUMF-ISAC yielded a {sup 7}Li-{sup 11}Li isotope shift (IS) of 25 101.23(13) MHz for the Doppler-free 2s {sup 2}S{sub 1/2}{yields}3s {sup 2}S{sub 1/2} transition. IS accuracy for all other bound Li isotopes was also improved. Differences from calculated mass-based IS yield values for change in charge radius along the isotope chain. The charge radius decreases monotonically from {sup 6}Li to {sup 9}Li, and then increases from 2.217(35) to 2.467(37) fm for {sup 11}Li. This is compared to various models, and it is found that a combination of halo neutron correlation and intrinsic core excitation best reproduces the experimental results.

  4. Nuclear Charge Radii of 9,11Li: The Influence of Halo Neutrons

    SciTech Connect

    Sanchez, Rodolfo; Nortershauser, W.; Ewald, G; Albers, Daniel; Behr, John; Bricault, Pierre; Bushaw, Bruce A.; Dax, A; Dilling, Jens; Dombsky, Marik; Drake, Gordon W. F.; Gotte, S; Kirchner, R G.; Kluge, H J.; Lassen, J; Kuhl, T H.; Levy, C.D. P.; Pearson, Matthew; Prime, Erika; Ryjkov, Vladimir L.; Wojtaszek, A.; Yan, Z C.; Zimmerman, C.

    2006-01-27

    The nuclear charge radius of 11Li has been determined for the first time by high precision laser spectroscopy. On-line measurements at TRIUMF-ISAC yielded a 7Li ? 11Li isotope shift (IS) of 25 101.23(13) MHz for the Doppler-free 2s 2S1=2 ! 3s 2S1=2 transition. IS precision for all other bound Li isotopes was also improved. Differences from calculated mass-based IS yield values for change in charge radius along the isotope chain. The charge radius decreases monotonically from 6Li to 9Li, and then increases from 2.216(35) fm to 2.467(37) fm for 11Li. This is compared to various models, and it is found that a combination of halo neutron correlation and intrinsic core excitation best reproduces the experimental results.

  5. 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.

  6. 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.

  7. Effect of the breakup process on the direct reaction with a {sup 6}Li projectile

    SciTech Connect

    So, W. Y.; Lee, Su Youn; Kim, K. S.

    2011-06-15

    We investigate the effect of the breakup process on the direct reaction (DR) for {sup 6}Li. In order to study this effect, we introduce the experimental and semiexperimental ratio factors R{sup expt} and R{sup th} by using the semiexperimental and experimental {alpha}-production cross sections and DR cross sections. The average values of the ratio R{sup expt} (R{sup th}) for the {sup 6}Li+{sup 208}Pb and {sup 6}Li+{sup 209}Bi systems are 0.90 (0.91) and 0.86 (0.85), respectively. From these results, it can be seen that the {alpha}-production cross sections are the main contribution to the DR cross sections.

  8. 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.

  9. 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.

  10. 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

  11. New study of the astrophysical reaction 13C(a,n)16O via the 13C(7Li,t)17O transfer reaction

    NASA Astrophysics Data System (ADS)

    Pellegriti, Maria Grazia; Hammache, F.; Roussel, P.; Audouin, L.; Beaumel, D.; Fortier, S.; Gaudefroy, L.; Kiener, J.; Lefebvre-Schujl, A.; Stanoiu, M.; Tatischeff, V.; Vilmay, M.

    PoS(NIC-IX)161 , , [1] , L. Gaudefroy[2] , J. Kiener[3] , A. Lefebvre-Schuhl[3] , M. Stanoiu[4] , V. The cross section of the 13 C(α,n)16 O reaction is a key ingredient for the comprehension of the s-process (slow neutron captures) in stars. This reaction is considered as the main neutron source for the s-process in low-mass Asymptotic Giant Branch (AGB) stars (1-3 solar mass) [1, 2, 3]. At the α-13 C energies of astrophysical interest (Ecm around 190 keV, corresponding to a tem- perature of 108 K) the contribution of the 17 O α-decay subthreshold resonance at 6.356 MeV to the 13 C(α,n)16 O cross section should be taken into account. The effect of this resonance is controversial after the different analyses of the Kubono et al. measurement [4] of the 6.356 MeV α-spectroscopic factor (Sα ) via the transfer reaction 13 C(6 Li,d)17 O . In order to further investigate the contribution of the 6.356 MeV resonance to the 13 C(α,n)16 O cross section, we performed a new measurement of its Sα factor via a different α-transfer reac- tion, namely the 13 C(7 Li,t)17 O reaction. The experiment was performed at the Orsay Tandem by using a 7 Li beam of 28 and 34 MeV on a 13C target. The angular distribution for the transfer dif- ferential cross section was measured by detecting the tritons at the focal plane of the SPLITPOLE spectrometer. The analysis procedure used in order to extract the yield of the 6.356 MeV level will be described. Preliminary results of the angular distribution will be shown.

  12. Formation of η{^'(958) meson bound states by the 6Li(γ,d) reaction

    NASA Astrophysics Data System (ADS)

    Miyatani, M.; Ikeno, N.; Nagahiro, H.; Hirenzaki, S.

    2016-07-01

    We have investigated the 6Li( γ, d) reaction theoretically for the formation of the η^'(958) mesic nucleus close to the recoilless kinematics. We have developed the theoretical formula and reported the quantitative results of the formation spectra for various cases in this article. We have found that the formation cross sections are reduced by the effects of the fragile deuteron form factor.

  13. 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.

  14. 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.

  15. 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.

  16. Nuclear Charge Radius of Lithium-11

    SciTech Connect

    Sanchez, Rodolfo; Nortershauser, W.; Dax, A. ..; Ewald, G.; Gotte, S.; Kirchner, R. G.; Kluge, H. J.; Kuhl, T. H.; Wojtaszek, A.; Bushaw, Bruce A.; Drake, Gordon W. F.; Yan, Z. C.; Zimmermann, Claus; Albers, Daniel; Behr, John; Bricault, Pierre; Dilling, Jens; Dombsky, Marik; Lassen, J.; Levy, C.D. P.; Pearson, Matthew; Prime, Erika; Ryjkov, Vladimir L.

    2006-07-01

    We have determined the nuclear charge radius of 11Li by high-precision laser spectroscopy. The experiment was performed at the TRIUMF-ISAC facility where the 7Li-11Li isotope shift was measured in the 2s to 3s electronic transition using Doppler-free two-photon spectroscopy with a relative accuracy better than 10 5. The accuracy reached in previous experiments on the other lithium isotopes was improved. Most of the isotope shifts measured in the experiment are due to difference in the mass of the nuclei but small contributions are produced by the change in proton distribution, QED and relativistic effects have to be taken into account as well. By comparing the experimental results with sophisticated atomic calculations of the mass dependent effect the nuclear charge radii of the lithium isotopes are found to decrease monotonically from 6Li to 9Li while the nuclear charge radius of 11Li is about 11% larger than that of 9Li.

  17. Predicted isotopic variation in surface α clustering in Sn compared with (d ,6Li ) pickup yields

    NASA Astrophysics Data System (ADS)

    Cowley, A. A.

    2016-05-01

    Based on a generalized relativistic mean-field model, α clustering on the surface of Sn was recently predicted to vary systematically as a function of isotopic mass. Existing experimental information from (d ,6Li ) cluster pickup is now used to verify the predicted trend. The extent of the anticipated validity of such a comparison between the experimental results and the theoretical formulation is evaluated and discussed in the present paper.

  18. 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.

  19. 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.

  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. Quantum defects in Rydberg nD states of optically cooled 7Li atoms

    NASA Astrophysics Data System (ADS)

    Sautenkov, V. A.; Saakyan, S. A.; Vilshanskaya, E. V.; Murashkin, D. A.; Zelener, B. B.; Zelener, B. V.

    2016-11-01

    To observe Rydberg transitions we applied a spectroscopic technique based on the observation of the resonance fluorescence of cold atoms in a magneto-optical trap. By using this approach, we estimated the quantum defect in Rydberg nD states of 7Li atoms. The obtained results are in a good agreement with previously published data.

  2. 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.

  3. 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

  4. 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.

  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. 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

  7. Characterization of the silicon+6LiF thermal neutron detection technique

    NASA Astrophysics Data System (ADS)

    Pappalardo, A.; Barbagallo, M.; Cosentino, L.; Marchetta, C.; Musumarra, A.; Scirè, C.; Scirè, S.; Vecchio, G.; Finocchiaro, P.

    2016-02-01

    The worldwide need to replace 3He for neutron detection has triggered research and development on new technologies and methods. A promising one is based on commercial solid state silicon detectors coupled with thin neutron converter layers containing 6Li. After proving the feasibility of this technique, we characterized the behavior of such a detector with different converter layer thicknesses. In this paper we also disentangle other contributions to the overall spectrum shape observed with this kind of detector, proving that its detection efficiency can be made reasonably high and that the gamma/neutron discrimination capability is comparable to that of 3He tubes.

  8. 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.

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

    DOE PAGES

    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

  10. 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.

  11. 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.

  12. 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.

  13. Excitation function shape and neutron spectrum of the 7Li(p ,n )7Be reaction near threshold

    NASA Astrophysics Data System (ADS)

    Martín-Hernández, Guido; Mastinu, Pierfrancesco; Maggiore, Mario; Pranovi, Lorenzo; Prete, Gianfranco; Praena, Javier; Capote-Noy, Roberto; Gramegna, Fabiana; Lombardi, Augusto; Maran, Luca; Scian, Carlo; Munaron, Enrico

    2016-09-01

    The forward-emitted low energy tail of the neutron spectrum generated by the 7Li(p ,n )7Be reaction on a thick target at a proton energy of 1893.6 keV was measured by time-of-flight spectroscopy. The measurement was performed at BELINA (Beam Line for Nuclear Astrophysics) of the Laboratori Nazionali di Legnaro. Using the reaction kinematics and the proton on lithium stopping power the shape of the excitation function is calculated from the measured neutron spectrum. Good agreement with two reported measurements was found. Our data, along with the previous measurements, are well reproduced by the Breit-Wigner single-resonance formula for s -wave particles. The differential yield of the reaction is calculated and the widely used neutron spectrum at a proton energy of 1912 keV was reproduced. Possible causes regarding part of the 6.5% discrepancy between the 197Au(n ,γ ) cross section measured at this energy by Ratynski and Kappeler [Phys. Rev. C 37, 595 (1988), 10.1103/PhysRevC.37.595] and the one obtained using the Evaluated Nuclear Data File version B-VII.1 are given.

  14. Optimizing ZnS/6LiF scintillators for wavelength-shifting-fiber neutron detectors

    SciTech Connect

    Crow, Lowell; Funk, Loren L; Hannan, Bruce W; Hodges, Jason P; Riedel, Richard A; Wang, Cai-Lin

    2016-01-01

    In this paper we compare the performance of grooved and flat ZnS/6LiF scintillators in a wavelength shifting-fiber (WLSF) detector. Flat ZnS/6LiF scintillators with the thickness L=0.2-0.8 mm were characterized using photon counting and pulse-height analysis and compared to a grooved scintillator of approximately 0.8 mm thick. While a grooved scintillator considerably increases the apparent thickness of the scintillator to neutrons for a given coating thickness, we find that the flat scintillators perform better than the grooved scintillators in terms of both light yield and neutron detection efficiency. The flat 0.8-mm-thick scintillator has the highest light output, and it is 52% higher compared with a grooved scintillator of same thickness. The lower light output of the grooved scintillator as compared to the flat scintillator is consistent with the greater scintillator-WLSF separation and the much larger average emission angle of the grooved scintillator. We also find that the average light cone width, or photon travel-length as measured using time-of-flight powder diffraction of diamond and vanadium, decreases with increasing L in the range of L=0.6-0.8 mm. This result contrasts with the traditional Swank diffusion model for micro-composite scintillators, and could be explained by a decrease in photon diffusion-coefficient or an increase in micro-particle content in the flat scintillator matrix for the thicker scintillators.

  15. Exploring an ultracold Fermi-Fermi mixture: interspecies Feshbach resonances of ^6Li-^40K

    NASA Astrophysics Data System (ADS)

    Schreck, Florian

    2008-03-01

    We report on the observation of interspecies Feshbach resonances in an ultracold mixture of two fermionic species, ^6Li and ^40K. Interpretation of the data unambiguously assigns molecular bound states to the various resonances and fully characterizes the ground-state scattering properties in any combination of spin states. Using this knowledge we hope to be able to produce ^6Li-^40K molecules, cool them to quantum degeneracy, and study their BEC-BCS crossover. In collaboration with: F. Schreck, Institut fuer Quantenoptik und Quanteninformation, Oesterreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria; E. Wille, Institut fuer Quantenoptik und Quanteninformation, Oesterreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria and Institut fuer Experimentalphysik und Forschungszentrum fuer Quantenphysik, Universitaet Innsbruck, 6020 Innsbruck, Austria; F.M. Spiegelhalder, G. Kerner, D. Naik, A. Trenkwalder, G. Hendl, Institut fuer Quantenoptik und Quanteninformation, Oesterreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria; R. Grimm, Institut fuer Quantenoptik und Quanteninformation, Oesterreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria and Institut fuer Experimentalphysik und Forschungszentrum fuer Quantenphysik, Universitaet Innsbruck, 6020 Innsbruck, Austria; T.G. Tiecke, J.T.M. Walraven,Van der Waals-Zeeman Institute of the University of Amsterdam, 1018 XE, The Netherlands; S.J.J.M.F. Kokkelmans, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands; E. Tiesinga, P.S. Julienne, Joint Quantum Institute, National Institute of Standards and Technology and University of Maryland, Gaithersburg, Maryland 20899-8423, USA

  16. 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

  17. 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.

  18. Angular Dependency and Kinematics of Light Atom Nuclear Reactions with Positive Q Values

    NASA Astrophysics Data System (ADS)

    Pacheco, Jose; Naab, Fabian; Marble, Daniel; Duggan, Jerome

    2006-10-01

    Einstein's relationship, E=mĉ2 implies that energy can be changed into mass and vice versa. Using nuclear reaction analysis, the interchange of mass into energy can be used to analyze trace elements in a material since each given element has a set of nuclear reactions that are unique to it. These nuclear reactions have positive Q values, which show up as excess energy in the emitted particle spectrum. However accurate interpretation of these spectra for materials analysis can be complicated as knowledge of both the angular dependency of the reaction and the geometry of the detection setup is required. The angular dependence is usually easily taken into account provided the reaction is well known and there are no nuclear interferences. In this experiment, a 1 MeV proton beam from a 2.5 MeV Van De Graff was applied to targets made up of light atoms, mainly 7Li, 6Li, and 19F. The results demonstrate the importance of accurately knowing the detection configuration, geometry, and the effect of detection system resolution when doing NRA. For instance, our system failed to give any information about the nuclear reaction for angles less than 30 degrees from the incoming beam due to its resolution.

  19. 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.

  20. 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.

  1. 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.

  2. Dynamic polarization potential due to 6Li breakup on 12C

    NASA Astrophysics Data System (ADS)

    Pang, D. Y.; Mackintosh, R. S.

    2011-12-01

    For 6Li scattering from 12C at five laboratory energies from 90 to 318 MeV, we study the dynamic polarization potential, DPP, due to the breakup of the projectile. The breakup is evaluated using standard continuum discretized coupled-channels formalism applied to a two-body cluster model of the projectile. The DPP is evaluated over a wide radial range using both direct S-matrix-to-potential inversion and trivially equivalent local potential methods which yield substantially and systematically different results. The radius at which the real DPP changes from external repulsion to interior attraction varies systematically with energy. This should be experimentally testable because, according to notch tests, this crossover radius is within a radial range to which elastic scattering should be sensitive. The imaginary DPP has an emissive (generative) region at the lower energies; this may be associated with counterintuitive properties of |SL|.

  3. 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

  4. 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.

  5. 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

  6. 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

    2016-06-02

    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.

  7. Resonances in transfer-triggered breakup of 7Li in near-barrier collisions

    NASA Astrophysics Data System (ADS)

    Simpson, E. C.; Cook, K. J.; Dasgupta, M.; Kalkal, S.; Luong, D. H.; Carter, I. P.; Hinde, D. J.; Williams, E.

    2016-09-01

    Above-barrier complete fusion cross sections of weakly-bound 6,7Li and 9Be are known to be suppressed with respect to single-barrier penetration model calculations. Breakup of the projectile — either via direct excitation of continuum states, or by transfer of nucleons — is thought to be the cause, preventing complete capture of the projectile charge. Using the example of 7Li→8Be→ α + α we show how the contributions to breakup from different resonances in 8Be can be identified, and discuss their likely influence on fusion.

  8. Experimental investigation of fusion of {sup 7}Li+{sup 28}Si above the Coulomb barrier

    SciTech Connect

    Sinha, Mandira; Majumdar, H.; Basu, P.; Roy, Subinit; Biswas, M.; Palit, R.; Mazumdar, I.; Joshi, P. K.; Jain, H. C.; Kailas, S.

    2007-08-15

    Excitation functions for the above-barrier fusion cross sections are measured for the first time for the {sup 7}Li+{sup 28}Si system by two methods--the characteristic {gamma}-ray method and the evaporation {alpha} measurement method--in the energy range E{sub lab}=11.5-26 MeV. Experimental results are consistent and agree with each other, and the one-dimensional Barrier Penetration Model (BPM) predictions describe the data well up to twice the Coulomb barrier, but they overestimate the data by about 15-20% at higher energies.

  9. Sub-barrier fusion excitation for the system {sup 7}Li + {sup 28}Si

    SciTech Connect

    Sinha, Mandira; Majumdar, H.; Basu, P.; Roy, Subinit; Biswas, M.; Pradhan, M. K.; Kailas, S.

    2008-08-15

    The sub-barrier fusion excitation functions are measured for the first time for the system {sup 7}Li+ {sup 28}Si by the characteristic {gamma}-ray method in the energy range E{sub lab}=7-11.5 MeV. The results show an enhancement, below the barrier, by about a factor of two when compared with the one-dimensional barrier penetration (1D BPM) model. Introduction of coupling with the rotational 2{sup +} state (1.779 MeV) of the target improves the fit somewhat, but still an enhancement of about 25-40% remains.

  10. 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.

  11. Revisiting the (7)Li(p,n)(7)Be reaction near threshold.

    PubMed

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

    2014-06-01

    In this work we review all the available experimental neutron data for the (7)Li(p,n) reaction near threshold which is necessary to obtain an accurate source model for Monte Carlo simulations in Boron Neutron Capture Therapy. Scattered published experimental results such as cross sections, differential neutron yields and total yields were collected and analyzed, exploring the sensitivity of the fitting parameters to the different possible variables and deriving a consistent working set of parameters to evaluate the neutron source near threshold.

  12. 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

  13. Non-monotonic potentials and vector analyzing powers of 6,7Li scattering by 12C, 26Mg, 58Ni, and 120Sn

    NASA Astrophysics Data System (ADS)

    Basak, A. K.; Billah, M. M.; Kobra, M. J.; Sarkar, M. K.; Mizanur Rahman, M.; Das, Pretam K.; Hossain, S.; Abdullah, M. N. A.; Tariq, A. S. B.; Uddin, M. A.; Bhattacharjee, S.; Reichstein, I.; Malik, F. B.

    2011-06-01

    The data on the elastic scattering cross-section (CS) and vector analyzing power (VAP) of 6,7Li incident on 12C , 26Mg, 58Ni and 120Sn nuclei are analyzed in terms of an optical model (OM) potential, the real part of which is generated from a realistic two-nucleon interaction using the energy-density functional (EDF) formalism. The EDF-generated real part of the potential is non-monotonic (NM) in nature. This NM real potential part, without any renormalization, along with an empirically determined imaginary part and spin-orbit potential, embodying the underlying physics of projectile excitation, can successfully account for both CS and VAP data in all four cases. This investigation, for the first time, using the simple OM analysis accounts well for the opposite signs of the VAP data of elastically scattered 6,7Li by 58Ni at Elab≈20 MeV and by 120Sn at Elab=44 MeV. The ramification of successfully describing the data by the EDF-generated potential to the equation of state of nuclear matter is discussed.

  14. Modifications in TL characteristics of K2Ca2(SO4)3 : Eu by 7Li MeV ion beam

    NASA Astrophysics Data System (ADS)

    Sahare, P. D.; Salah, Numan; Lochab, S. P.; Mohanty, T.; Kanjilal, D.

    2005-11-01

    Highly sensitive K2Ca2(SO4)3 : Eu thermoluminescence detector phosphor was irradiated at room temperature by 7Li ion beams at 24 and 48 MeV for different ion fluences in the range 109-1012 ions/cm2 using a 16 MV Tandem Van de Graff Type Electrostatic Pelletron Accelerator at the Nuclear Science Centre, New Delhi, India. The samples from the same batch were also irradiated with γ-rays from a Cs137 source for comparative studies. Glow curves of the ion beam irradiated samples mainly consist of two prominent peaks at around 392 and 411 K while the γ-rays irradiated samples show only one peak at around 411 K. The appearance of the new peak (392 K peak) may be attributed to the defects/trapping centres due to 7Li ions that have been implanted deep inside during irradiation and act as a source of emission of thermoluminescence (TL). This was confirmed from the glow curve structure of Eu, Li ion co-doped samples.

  15. 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}.

  16. 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).

  17. 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.

  18. Multi-elemental characterization of organic liquid samples by use of a 13 MeV 6Li 3+ beam

    NASA Astrophysics Data System (ADS)

    Liendo, J. A.; Bernal, M. A.; González, A. C.; Caussyn, D. D.; Fletcher, N. R.; Momotyuk, O. A.; Muruganathan, R. M.; Roeder, B. T.; Wiedenhöver, I.; Fischer, T.; Kemper, K. W.; Barber, P.; Sajo-Bohus, L.

    2009-10-01

    Evaporated amniotic fluid (AF) targets have been bombarded with a 13 MeV 6Li 3+ beam. Forward angle data have served to identify the 1H( 6Li, 1H) 6Li reaction as an alternative for hydrogen characterization of such organic samples. Detected 6Li ions elastically scattered from C, N, O, Na and Cl can also be used to determine the concentrations of these elements in AF. The analyzed AF samples have been diluted with distilled water. The effect of sample dilution on the improvement of spectrum energy resolution has been observed, confirming previous reports. The hydrogen concentration determined in the studied AF targets is shown to vary linearly with sample dilution. Two detector arrangements have been used to find out which detection scheme is the most convenient. The combination of a counter telescope and a single detector, set up at the same polar angle on the opposite side of the beam, seems to be the best choice to have a reliable particle identification and an adequate energy resolution simultaneously.

  19. 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.

  20. {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.}

  1. High accuracy ab initio studies of Li6+, Li6-, and three isomers of Li6

    NASA Astrophysics Data System (ADS)

    Temelso, Berhane; Sherrill, C. David

    2005-02-01

    The structures and energetics of Li6+, Li6- and three isomers of Li6 are investigated using the coupled-cluster singles, doubles and perturbative triples [CCSD(T)] method with valence and core-valence correlation consistent basis sets of double- to quadruple-ζ quality (cc-pVXZ and cc-pCVXZ, where X =D-Q). These results are compared with qualitatively different predictions by less reliable methods. Our results conclusively show that the D4h isomer is the global minimum structure for Li6. It is energetically favored over the C5v and D3h structures by about 5.1 and 7.1kcalmol-1, respectively, after the inclusion of the zero-point vibrational energy (ZPVE) correction. Our most accurate total atomization energies are 123.2, 117.6, and 115.7kcalmol-1 for the D4h, C5v, and D3h isomers, respectively. Comparison of experimental optical absorption spectra with our computed electronic spectra also indicate that the D4h isomer is indeed the most stable structure. The cation, anion, and some higher spin states are investigated using the less expensive cc-pCVDZ basis set. Adiabatic ionization energies and electron affinities are reported and compared with experimental values. Predictions of molecular properties are found to be sensitive to the basis set used and to the treatment of electron correlation.

  2. Lifetime of 6 Li40 K dimers near a Feshbach resonance

    NASA Astrophysics Data System (ADS)

    Jag, Michael; Cetina, Marko; Lous, Rianne; Levinsen, Jesper; Petrov, Dmitry; Grimm, Rudolf

    2016-05-01

    We investigate the lifetime of bosonic dimers formed in a Fermi- Fermi mixture of 6 Li and 40 K atoms near a Feshbach resonance. Pure dimer samples are created from a Li-K mixture by ramping a magnetic field across the resonance and removing unbound atoms. We then perform lifetime measurements using both trapped high-density as well as expanding low-density samples after release from the trap. These measurements discriminate between the spontaneous and the collisional dimer decay. We further determine the dimer decay due to Li-LiK collisions in an atom-dimer mixture. Our measurements reveal a more than three-fold (five-fold) decrease in decay due to dimer-dimer (atom-dimer) collisions as the Feshbach resonance is approached. This observation is in good agreement with a theoretical prediction, which relates the decay rate to the probability of finding the colliding atoms within a short distance, and can mostly be explained by the increased fermionic character of the halo-dimer state together with Pauli blocking. We apply our model to combinations of other fermionic species to predict the dimer lifetime, which is an important parameter for their prospect towards realizing novel quantum phases. SFB FoQuS.

  3. 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.

  4. The effect of fast electronic relaxation times on the 1H and 7Li magnetic relaxation dispersion modulated by the translational encounter of cation/cation pairs

    NASA Astrophysics Data System (ADS)

    Dinesen, T. R. J.; Bryant, R. G.

    1999-04-01

    1H and 7Li magnetic relaxation dispersion data are presented, showing the field dependence of the spin-lattice relaxation rates of (H 3C) 4N + and Li(H 2O) n+ in Gd(III) and Mn(II) solutions. The limit of short electronic relaxation time is observed for Gd(III) up to about 7 T, in contrast to Mn(II) solutions wherein the intermolecular contribution to nuclear relaxation is dominated by relative translational diffusion. These results contradict the assumption made by Fries et al. (Chem. Phys. Lett. 286 (1998) 93) that the electron relaxation times may be neglected in the analysis of tetramethylammonium proton relaxation rates in Gd(III) solutions.

  5. 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.

  6. 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.

  7. Ab initio calculations of nuclear reactions important for astrophysics

    NASA Astrophysics Data System (ADS)

    Navratil, Petr; Dohet-Eraly, Jeremy; Calci, Angelo; Horiuchi, Wataru; Hupin, Guillaume; Quaglioni, Sofia

    2016-09-01

    In recent years, significant progress has been made in ab initio nuclear structure and reaction calculations based on input from QCD employing Hamiltonians constructed within chiral effective field theory. One of the newly developed approaches is the No-Core Shell Model with Continuum (NCSMC), capable of describing both bound and scattering states in light nuclei simultaneously. We will present NCSMC results for reactions important for astrophysics that are difficult to measure at relevant low energies, such as 3He(α,γ)7Be and 3H(α,γ)7Li and 11C(p,γ)12N radiative capture, as well as the 3H(d,n)4He fusion. We will also address prospects of calculating the 2H(α,γ)6Li capture reaction within the NCSMC formalism. Prepared in part by LLNL under Contract DE-AC52-07NA27344. Supported by the U.S. DOE, OS, NP, under Work Proposal No. SCW1158, and by the NSERC Grant No. SAPIN-2016-00033. TRIUMF receives funding from the NRC Canada.

  8. 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.

  9. Dynamic polarization potential effects on vector analyzing powers of 6Li- 28Si elastic scattering from non-monotonic potentials

    NASA Astrophysics Data System (ADS)

    Basak, A. K.; Roy, P. K.; Hossain, S.; Abdullah, M. N. A.; Tariq, A. S. B.; Uddin, M. A.; Reichstein, I.; Malik, F. B.

    2010-08-01

    Experimental cross section (CS) and vector analyzing power (VAP) data of the 6Li-28Si elastic scattering at 22.8 MeV are analyzed in the coupled-channels (CC) and coupled discretized continuum channels (CDCC) methods. Non-monotonic (NM) 6Li and α potentials of microscopic origin are employed, respectively, in the CC calculations and to generate folding potentials for the CDCC calculations. The study demonstrates that the use of central NM potentials can generate an appropriate dynamic polarization potential (DPP) required to describe both the CS and VAP data without the necessity of renormalization. This also produces an effective spin-orbit (SO) potential to account for the iT11 data without the requirement of an additional static SO potential at the incident energy considered.

  10. Li 2TiO 3 pebbles reprocessing, recovery of 6Li as Li 2CO 3

    NASA Astrophysics Data System (ADS)

    Alvani, C.; Casadio, S.; Contini, V.; Di Bartolomeo, A.; Lulewicz, J. D.; Roux, N.

    2002-12-01

    A process for obtaining Li 2CO 3 from Li 2TiO 3 powder by wet chemistry was developed. This is considered useful in view of the recovery of the 6Li isotope from lithium titanate breeder burned to its end of life in a fusion reactor. The process was optimized with respect to the chemical attack of titanate and the precipitation of carbonate from aqueous solutions to get a powder with chemical and morphological characteristics suitable for its reexploitation in the fabrication of Li 2TiO 3 pebbles. Reprocessing was also planned to adjust the 6Li concentration to the desired value and to obtain a homogeneous distribution in the powder batch. Further development concerning reprocessing of sintered Li 2TiO 3 pebbles is in progress exploiting the results obtained with lithium titanate powders.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Equilibrium and Kinetic Isotopic Fractionation Processes Recorded in δ7Li Values of Highly Evolved Granitic Pegmatites

    NASA Astrophysics Data System (ADS)

    Barnes, E. M.; Weis, D. A.; Groat, L. A.

    2010-12-01

    In geologic settings, Li isotopes are significantly influenced by both equilibrium and kinetic fractionation mechanisms. This has the potential to make δ7Li values valuable in identifying geological processes or tracing source rocks. Lithium isotopic analysis is becoming an increasingly popular geochemical tool, however, a better understanding of the mechanisms involved in Li isotopic fractionation is necessary if this method is to achieve its full potential. This study combined δ7Li values, trace element geochemistry, mineralogy and primary textural evidence from rock-forming minerals (quartz, albite, spodumene and mica) and whole rock samples taken from a coeval swarm of rare element pegmatite dikes, to look at the extent and mechanisms of Li isotopic fractionation during pegmatite formation. Pegmatite crystallization can be extremely rapid, potentially on a similar timescale to Li diffusion, as a result the influence of variable, non-equilibrium conditions during consolidation was assessed. Rock-forming minerals (given above) from the Little Nahanni Pegmatite Group (Northwest Territories, Canada) display δ7Li values that correlate with textural evidence supporting consolidation of the dikes under non-equilibrium conditions. Two examples of spodumene from different pegmatite samples have comparable δ7Li values of +3.5 and +3.7‰. In contrast, the δ7Li value of mineral separates from co-precipitated mineral assemblages varies from sample to sample. Very uniform δ7Li values for co-precipitated minerals from one sample (muscovite at +7.9‰, plagioclase at +7.9‰ and quartz at +8.7‰), contrast with very different δ7Li values for the same mineral assemblage from a different sample (muscovite at +2.2‰, plagioclase at +3.4‰ and quartz at +15.7‰). Whole rock samples from the same outcrops suggest strong Li isotope fractionation in peraluminous magma is associated with F build up in the late stages of magmatic differentiation. Pegmatites derived from the

  19. Superconducting properties of hole doped Ba(0.6)Li(0.4)Fe2As2 single crystal.

    PubMed

    Ahmad, D; Min, B H; Ko, M J; Seo, Y L; Choi, W J; Lee, J H; Kim, G C; Kim, Y C; Kwon, Y S

    2014-04-30

    We report the emergence of superconductivity in Li doped Ba-122 single crystals grown by the Bridgman method. The superconducting transition temperature Tc,onset is around 19 K. The specific heat capacity C/T shows a weak anomaly near Tc. The value of ΔC/γnTc is smaller than the value predicted in BCS theory indicating a multigap nature of the sample. The magnetic measurements show that the lower critical field Hc1(T) exhibits a linear temperature dependence, with a pronounced change of the Hc1(T) curvature around 0.4Tc and Hc1(0) ≈ 430 Oe in the Ba0.6Li0.4Fe2As2 single crystal. Furthermore, temperature dependence of the penetration depth λ(T) follows a power law (~T(n)) below 0.4Tc which predicts possible S±-wave pairing in a Ba0.6Li0.4Fe2As2 superconductor. Over a wide range of temperatures, the Jc(H) exhibits a relation J(c)[proportionality] H(-α) with α = 0.5 ~ 0.6 for H || c and H || ab which indicates random defects in the sample. We found that the temperature dependence of the critical current density Jc(T) can be fitted well with the δl-type pinning model, whose origin is attributed to spatial variations of charge carrier mean free path l. We suggest that the large mismatch in the ionic radius of Ba and Li can affect the irreversible magnetic properties of the Ba0.6Li0.4Fe2As2 single crystal without any structural transition. PMID:24721709

  20. Characterization of a 6Li-loaded liquid organic scintillator for fast neutron spectrometry and thermal neutron detection.

    PubMed

    Bass, C D; Beise, E J; Breuer, H; Heimbach, C R; Langford, T J; Nico, J S

    2013-07-01

    The characterization of a liquid scintillator incorporating an aqueous solution of enriched lithium chloride to produce a scintillator with 0.40% (6)Li is presented, including the performance of the scintillator in terms of its optical properties and neutron response. The scintillator was incorporated into a fast neutron spectrometer, and the light output spectra from 2.5 MeV, 14.1 MeV, and (252)Cf neutrons were measured using capture-gated coincidence techniques. The spectrometer was operated without coincidence to perform thermal neutron measurements. Possible improvements in spectrometer performance are discussed.

  1. Structures in 20O from the 14C(7Li, p) reaction at 44 MeV

    NASA Astrophysics Data System (ADS)

    Bohlen, H. G.; von Oertzen, W.; Milin, M.; Dorsch, T.; Krücken, R.; Faestermann, T.; Hertenberger, R.; Kokalova, Tz.; Mahgoub, M.; Wheldon, C.; Wirth, H.-F.

    2011-03-01

    We have studied the multi-nucleon transfer reaction 14 C(7 Li, p) at E Lab(7 Li) = 44 MeV populating states of the neutron-rich oxygen isotope 20O . The experiments have been performed at the Munich Tandem accelerator using the high-resolution Q3D magnetic spectrometer, with an overall energy resolution of 45keV. States were populated up to 20MeV excitation energy -65 states have been identified in the analysis, among which 42 are new. Rotational bands are proposed in terms of underlying intrinsic reflection-asymmetric cluster and prolate molecular structures (namely ensuremath ^{14}C⊗2n⊗α as parity doublet bands. A rectangular oblate structure is suggested for some very narrow states at high excitation energies.

  2. Experimental probe for the production of 97Ru from the 7Li+93Nb reaction: A study of precompound emissions

    NASA Astrophysics Data System (ADS)

    Kumar, Deepak; Maiti, Moumita; Lahiri, Susanta

    2016-10-01

    Background: Interaction of weakly bound heavy ions with an intermediate or heavy target is not yet understood completely due to the scarcity of experimental data. In order to develop a clear understanding of breakup fusion or preequilibrium emission even in the low energy range, 3-10 MeV/nucleon, more experimental investigations are necessary. Purpose: We aim to study the reaction mechanisms involved in the weakly bound heavy-ion induced reaction 7Li+93Nb at low energies by measuring the production cross sections of the residual radionuclides. Method: Natural niobium (93Nb) foil, backed by an aluminum (Al) catcher, arranged in a stack was bombarded by 7Li ions of 20-45 MeV energy. Activity of the residues produced in each 93Nb target was measured by off line γ -ray spectrometry after the end of bombardment (EOB) and cross sections were calculated. Experimental cross sections were compared with those computed using compound and precompound models. Results: In general, measured excitation functions of all residues produced in the 7Li+93Nb reaction showed good agreement with the model calculations based on the Hauser-Feshbach formalism and the exciton model for compound and precompound processes, respectively. Significant preequilibrium emission of neutrons was observed at the relatively high energy tail of the excitation function of 97Ru. Conclusions: Preequilibrium processes played an important role in the enhancement of the cross section in the x n reaction channel over the compound reaction mechanism at higher energies for the 7Li+93Nb reaction. Additionally, indirect evidence of incomplete or breakup fusion was also perceived.

  3. Matrix-dependent modulation of anisotropic effects on NMR spectra from 7Li+ and 23Na+ encapsulated in cryptands.

    PubMed

    Naumann, Christoph; Kuchel, Philip W

    2013-01-01

    (7)Li and (23)Na NMR spectra of the respective cations in gelatin and ι-carrageenan gels containing cryptand-[2.1.1] (for Li(+)) or cryptand-[2.2.2] (for Na(+)) displayed two transitions: the one at higher frequency corresponded to the cation surrounded by gel, the other to cation inside its appropriately sized cryptand. While binding to cryptands yielded much broader lines and shorter T (1) relaxation times, anisotropic splitting in first order (7)Li or (23)Na NMR spectra was not detected. Stretching the gels resulted in increasing the anisotropic electric field gradient tensor; thus, the NMR transitions of the cation in the gel were split (removal of degeneracy) to display its characteristic 3:4:3 triplet for spin = 3/2 nuclei. The transitions of the cryptand-bound cations (Li(+)-cryptand-[2.1.1] and Na(+)-cryptand-[2.2.2]) showed different extents of interaction with the electric field gradient tensor depending on the composition of the gel matrix. The NMR signal for (7)Li(+)-cryptand-[2.1.1] in stretched gelatin gel showed a five-fold increased splitting as compared to the (7)Li(+) signal in the reference gel. In stretched ι-carrageenan gels, no anisotropic splitting from the cryptand-bound Li(+) was recorded. Steady-state irradiation envelopes or z-spectra showed evidence of Li(+) exchange between isotropic (cryptand) and anisotropic (gel) sites only at higher temperatures (55 °C). For Na(+) bound to the cryptand-[2.2.2], anisotropic splitting (three-fold smaller compared with the (23)Na signal in the reference gel) was only recorded in stretched ι-carrageenan gels, whereas gelatin gels showed only anisotropic splitting for the (23)Na signal in the reference gel.

  4. Optimization parameters for BDE in BNCT using near threshold 7Li(p,n)7Be direct neutrons.

    PubMed

    Bengua, Gerard; Kobayashi, Tooru; Tanaka, Kenichi; Nakagawa, Yoshinobu

    2004-11-01

    The dose contribution of (10)B(n,alpha)(7)Li reaction in BNCT using near threshold (7)Li(p,n)(7)Be direct neutrons can be increased through the use of materials referred to as boron-dose enhancers (BDE). In this paper, possible BDE optimization criteria were determined from the characteristics of candidate BDE materials namely (C(2)H(4))(n), (C(2)H(3)F)(n), (C(2)H(2)F(2))(n), (C(2)HF(3))(n), (C(2)D(4))(n), (C(2)F(4))(n), beryllium metal, graphite, D(2)O and (7)LiF. The treatable protocol depth (TPD) was used as the assessment index for evaluating the effect of these materials on the dose distribution in a medium undergoing BNCT using near threshold (7)Li(p,n)(7)Be direct neutrons. The maximum TPD (TPD(max)) did not exhibit an explicit dependence on material type as evidenced by its small range and arbitrary variations. The dependence of TPD on BDE thickness was influenced by the BDE material used as indicated by the sharply peaked TPD versus BDE thickness curves for materials with hydrogen compared to the broader curves obtained for those without hydrogen. The BDE thickness required to achieve TPD(max) (BDE(TPD(max))) were also found to be thinner for materials with hydrogen. The TPD(max), the dependence of TPD on BDE thickness, and the BDE(TPD(max)) were established as appropriate BDE optimization parameters. Based on these criteria and other practical considerations, the suitable choice as BDE among the candidate materials considered in this study for treatments involving tumors located at shallow depths would be (C(2)H(4))(n) while beryllium metal was judged as more appropriate for treatment of deep-seated tumors.

  5. Prediction of a weakly bound excited state of Efimov character in a 7LiHe42 system

    NASA Astrophysics Data System (ADS)

    Wu, Meng-Shan; Han, Hui-Li; Li, Cheng-Bin; Shi, Ting-Yun

    2014-12-01

    We carry out calculations on the van der Waals trimer 7LiHe42 using the mapping method within the frame of hyperspherical coordinates, which allows us to give accurate binding energies and wave functions for both the ground and excited state of the system. When the realistic two-body potentials are adopted, the system presents an excited state which shows Efimov character. We study the range of the interaction strength in which the excited state could exist and find that the state persists within the experiment error band for binding energy of LiHe molecule. We also study the three-body parameter (3BP) of 7LiHe42 system and its relationship with the background scattering length aHeHe. Our calculations demonstrate that the 3BP of 7LiHe42 system is dependent on the value of the scattering length aHeHe, independent of the short-range details of the He-He interaction. The results confirm the prediction of Wang et al. [Phys. Rev. Lett. 109, 243201 (2012), 10.1103/PhysRevLett.109.243201] that the 3BP for a heteronuclear atomic system is universally determined from the van der Waals lengths and the homonuclear scattering length.

  6. 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.

  7. 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

  8. Applications of (n, p) and (n, α) reactions and a backscattering technique to fusion reactor materials, archeometry, and nuclear spectroscopy

    NASA Astrophysics Data System (ADS)

    Fink, D.; Biersack, J. P.; Grawe, H.; Riederer, J.; Müller, K.; Henkelmann, R.

    1980-01-01

    Depth profiles of He, Li and B are determined by 3He(n, p)T, 6Li(n, α)T and 10B(n, α) 7Li reactions with thermal neutrons at the high flux reactor of the ILL, Grenoble. The behaviour of Li in Be is examined with respect to future fusion reactors. Range profiles of 70-300 keV Li + are measured and found to agree with theory based on Lindhard-Scharff electronic stopping and Molière potential. Li becomes mobile in Be above 100°C. Further, B and Li distributions in glaze of ancient pottery are examined for studying ancient production techniques. It is found that all examined samples (of Islamic, Thai and North American provenience) show Li and B concentrations which are enriched relative to the original material. Li is mostly depleted in a surface layer of 0.1-1.6 μm half-width due to various burning conditions. In experimental nuclear physics, gas cells are now often replaced by thin foils with implanted gas. In many cases the knowledge of the concentration profile is required, and is presently evaluated for the case of 3He in Ni and Au with the (n, p) reaction. This is compared to results obtained by a special Rutherford backscattering technique yielding good agreement.

  9. 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.

  10. 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.

  11. Ion hopping in crystalline and glassy spodumene LiAl Si2 O6 : 7Li spin-lattice relaxation and 7Li echo NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Qi, F.; Rier, C.; Böhmer, R.; Franke, W.; Heitjans, P.

    2005-09-01

    Nuclear magnetic resonance spectroscopy was used to study polycrystalline β -spodumene (β-LiAlSi2O6) as well as glassy specimens with the same chemical composition. Li7 spin-lattice relaxation measurements were carried out in a broad temperature range and for several Larmor frequencies. In addition to a pronounced rate maximum at high temperatures, stemming from the long-range Li motion in these aluminosilicates, we found a weak maximum in the crystalline modification near 120K . The latter result confirms the existence of a local double-well structure in which the Li ions reside. The ionic motion was also monitored by solid- and stimulated-echo spectra as well as by the decay of the Jeener-Broekaert echo. Under conditions which are discussed in detail, the latter is a direct measure of the hopping correlation function. For the glass this function was found to decay faster and more stretched than that of the crystal at a given temperature. Furthermore, the relevant barriers against the high-temperature long-range Li motion are larger in the crystal as compared to the glass.

  12. 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.

  13. The Bare Astrophysical S(E) Factor of the 7Li(p, α)α Reaction

    NASA Astrophysics Data System (ADS)

    Lattuada, M.; Pizzone, R. G.; Typel, S.; Figuera, P.; Miljanić, Đ.; Musumarra, A.; Pellegriti, M. G.; Rolfs, C.; Spitaleri, C.; Wolter, H. H.

    2001-12-01

    The astrophysically important 7Li(p, α)α reaction has been studied via the Trojan horse method in the energy range E=10-400 keV. A new theoretical description, based on the distorted-wave Born approximation approach, allows one to extract information on the bare astrophysical S-factor, Sb(E), with Sb(0)=55+/-3 keV barns. The results are compared with direct experimental data leading to a model-independent value of the electron screening potential energy, Ue=330+/-40 eV, much higher than the adiabatic limit Uad=175 eV.

  14. 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.

  15. A TPD and AR based comparison of accelerator neutron irradiation fields between (7)Li and W targets for BNCT.

    PubMed

    Tanaka, Kenichi; Endo, Satoru; Yonai, Shunsuke; Baba, Mamoru; Hoshi, Masaharu

    2014-06-01

    The characteristics of moderator assembly dimension was investigated for the usage of (7)Li(p,n) neutrons by 2.3-2.8MeV protons and W(p,n) neutrons by 50MeV protons. The indexes were the treatable protocol depth (TPD) and advantage depth (AD). Consequently, a configuration for W target with the Fe filter, Fluental moderator, Pb reflector showed the TPD of 5.8cm and AD of 9.3cm. Comparable indexes were found for the Li target in a geometry with the MgF2 moderator and Teflon reflector.

  16. 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.

  17. Absolute frequencies of the {sup 6,7}Li 2S {sup 2}S{sub 1/2}{yields}3S {sup 2}S{sub 1/2} transitions

    SciTech Connect

    Lien, Yu-Hung; Lo, Kuan-Ju; Chen, Jun-Ren; Liu, Yi-Wei; Chen, Hsuan-Chen; Tian, Jyun-Yu; Shy, Jow-Tsong

    2011-10-15

    The measurement of the absolute frequencies of the 2S{yields}3S of atomic lithium is reported. To reduce systematic effects, we employed a frequency-comb-stabilized excitation laser, a weakly collimated atomic beam, and the cascading 2P{yields}2S 670 nm fluorescence as the signal. The transition frequencies, including two isotopes ({sup 6,7}Li), were measured to an accuracy of < 330 kHz. In comparison with the previous GSI Group experiment, the frequency of the 2S{sub 1/2}{yields}3S{sub 1/2} transition of {sup 7}Li is 815 618 181.45(9) MHz, which is improved by a factor of 2. The resultant hyperfine constants of the 3S state and the deduced difference of the nuclear charge radii {delta} from the isotope shift are in good agreement with previous results. Since a more straightforward methodology is adopted, our measurement is less model dependent and serves as an independent investigation of the reported transitions.

  18. 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.

  19. Measuring the ratio of aqueous diffusion coefficients between [sup 6]Li[sup +]Cl[sup [minus

    SciTech Connect

    Fritz, S.J. )

    1992-10-01

    Osmotic equilibrium is a singular occurrence in the evolution of an osmotic cell because at this event the net solution flux is zero such that [minus]J[sub w] [center dot] [bar V][sub w] = J[sub s] [center dot] [bar V][sub s]. At this juncture, the diffusion coefficient of the solute through the membrane ([omega]) equals the solute flux (J[sub s]) divided by the osmotic pressure ([delta]II). Because the solute permeability coefficient ([omega]) is related to the Fickian diffusion coefficient (D) through the gas constant, temperature, and the membrane's thickness and tortuosity, the ratio of [omega] values for individual isotopic species equals the ratio of D values for the same isotopic components. A 0.9450 molal LiCl solution was placed within sealed dialysis tubing and osmoted against a kilogram of deionized water at 22C. Osmotic equilibrium occurred at 164 [plus minus] 10 min. The ratio of [omega][sub [sup 6]Li[sup +]Cl[sup [minus

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

    DOE PAGES

    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

  1. 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

  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. Development of wide area detector for the 2012 model of the 6 Li time analyzer neutron detector system

    NASA Astrophysics Data System (ADS)

    Satoh, S.

    2016-11-01

    A 2012 model 6 Li time analyzer neutron detector (LiTA12) system has been developed as a high-count-rate neutron detector. An exclusive function with a center-of-gravity calculation, which not only prevents over-counting due to cross-talk, but also obtains a fine position resolution, has been included. As a high-count-rate detector, this device can detect neutrons with a 3mm position resolution in a detection area of 5×5 cm2 and is arranged as a 16×16 matrix with a detection efficiency of approximately 40% of that of a 3 He detector. A maximum count rate of 50 million counts per second (Mcps) is obtained. Using the exclusive function, the center-of-gravity pixel size obtained is 0.4mm, although the actual pixel size is 3mm. Furthermore, this function also enables a wide area detector in an area of 10×10 cm2 using four multi-anode (8×8 matrix) photomultiplier tubes. In this case, the pixel size is 0.8mm, although the actual pixel size is 6mm.

  4. Development of neutron-monitor detector using liquid organic scintillator coupled with 6Li + ZnS(Ag) Sheet.

    PubMed

    Sato, Tatsuhiko; Endo, Akira; Yamaguchi, Yasuhiro; Takahashi, Fumiaki

    2004-01-01

    A phoswitch-type detector has been developed for monitoring neutron doses in high-energy accelerator facilities. The detector is composed of a liquid organic scintillator (BC501A) coupled with ZnS(Ag) sheets doped with 6Li. The dose from neutrons with energies above 1 MeV is evaluated from the light output spectrum of the BC501A by applying the G-function, which relates the spectrum to the neutron dose directly. The dose from lower energy neutrons, on the other hand, is estimated from the number of scintillations emitted from the ZnS(Ag) sheets. Characteristics of the phoswitch-type detector were studied experimentally in some neutron fields. It was found from the experiments that the detector has an excellent property of pulse-shape discrimination between the scintillations of BC501A and the ZnS(Ag) sheets. The experimental results also indicate that the detector is capable of reproducing doses from thermal neutrons as well as neutrons with energies from one to several tens of megaelectronvolts (MeV).

  5. A {sup 11}B and {sup 7}Li MAS-NMR study of sol-gel lithium triborate glass subjected to thermal densification

    SciTech Connect

    Mustarelli, P.; Quartarone, E.; Benevelli, F.

    1997-06-01

    The effects of thermal densification on a sol-gel lithium triborate glass have been studied by {sup 11}B and {sup 7}Li NMR both static and at the magic angle (MAS). {sup 11}B spectra show that the boron average coordination is similar in sol-gel and melt-quenched samples and it does not change upon annealing. {sup 7}Li T{sub 1} is shorter ({approximately}8.5 s) in sol-gel glass as prepared than in its melt-quenched counterpart ({approximately}13 s) due to dipolar-dipolar Li-H interaction. {sup 7}Li longitudinal relaxation behavior captures a part of a complex devitrification process which is driven by the loss of both residual solvent and moisture.

  6. 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

  7. 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.

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

    PubMed

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

    2013-05-15

    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, (7)Li 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 × 10(5) 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.

  9. Fusion cross sections for {sup 6,7}Li + {sup 24}Mg reactions at energies below and above the barrier

    SciTech Connect

    Ray, M.; Mukherjee, A.; Pradhan, M. K.; Kshetri, Ritesh; Sarkar, M. Saha; Dasmahapatra, B.

    2008-12-15

    Measurement of fusion cross sections for the {sup 6,7}Li + {sup 24}Mg reactions by the characteristic {gamma}-ray method has been done at energies from below to well above the respective Coulomb barriers. The fusion cross sections obtained from these {gamma}-ray cross sections for the two systems are found to agree well with the total reaction cross sections at low energies. The relatively large difference between total cross sections and measured fusion cross sections at higher energies is consistent with the fact that other channels, in particular breakup, open up with an increase of bombarding energy. The breakup channel, however, appears not to have any influence on fusion cross sections. The critical angular momenta (l{sub cr}) deduced from the fusion cross sections are found to have an energy dependence similar to other Li-induced reactions.

  10. Review: biological effectiveness of thermal neutrons and 10B(n,alpha)7Li reaction on cultured cells.

    PubMed

    Fukuda, H; Ichihashi, M; Kobayashi, T; Matsuzawa, D; Kanda, K; Mishima, Y

    1989-01-01

    There are only a few reports on the relative biological effectiveness (RBE) of thermal neutrons and 10B(n,alpha)7Li reactions either in vitro or in vivo. The data in this paper summarize almost all previously published in vitro data. Because only a few reactors are available for biomedical purposes, it is difficult to make a comparison of data from experiments using the same kind of radiation, and also to make a comparison of data from experiments using the different kinds of radiations. However, it is indispensable for boron neutron capture therapy to make a radiobiological analysis. More intensive study, including repair process and oxygen effect, is necessary for establishing the fundamental basis of the clinical application of boron neutron capture therapy.

  11. Hyperfine fields at the Li site in LiFePO(4)-type olivine materials for lithium rechargeable batteries: a (7)Li MAS NMR and SQUID study.

    PubMed

    Tucker, Michael C; Doeff, Marca M; Richardson, Thomas J; Fiñones, Rita; Cairns, Elton J; Reimer, Jeffrey A

    2002-04-17

    The (7)Li NMR isotropic shift for olivine LiMPO(4) (M = Fe, Mn, Co, Ni) is assigned to hyperfine coupling between the (7)Li nucleus and the transition metal unpaired electrons on the basis of the Curie-Weiss temperature dependence of the shift. The hyperfine shift arises from a linear combination of Li-O-M through-bond interactions wherein the unpaired A' electrons contribute a negative shift and the unpaired A' ' electrons contribute a positive shift. The hyperfine coupling constant is determined for each composition.

  12. Variations in lithium target thickness and proton energy stability for the near-threshold 7Li(p,n)7Be accelerator-based BNCT.

    PubMed

    Kobayashi, Tooru; Bengua, Gerard; Tanaka, Kenichi; Nakagawa, Yoshinobu

    2007-02-01

    The usable range of thickness for the solid lithium target in the accelerator-based neutron production for BNCT via the near-threshold (7)Li(p,n)(7)Be reaction was investigated. While the feasibility of using a (7)Li-target with thickness equal to that which is required to slow down a mono-energetic 1.900 MeV incident proton to the 1.881 MeV threshold of the (7)Li(p,n)(7)Be reaction (i.e., t(min) = 2.33 microm) has already been demonstrated, dosimetric properties of neutron fields from targets greater than t(min) were assessed as thicker targets would last longer and offer more stable neutron production. Additionally, the characteristics of neutron fields generated by (7)Li(p,n)(7)Be for Gaussian incident protons with mean energy of 1.900 MeV were evaluated at a (7)Li-target thickness t(min). The main evaluation index applied in this study was the treatable protocol depth (TPD) which corresponds to the depth in an irradiated medium that satisfies the requirements of the adapted dose protocol. A maximum TPD (TPD(max)) was obtained for each irradiation condition from the relationship between the TPD and the thickness of boron dose enhancer (BDE) used. For a mono-energetic 1.900 MeV proton beam, the deepest TPD(max) of 3.88 cm was attained at the (7)Li-target thickness of t(min) and a polyethylene BDE of 1.10 cm. When the intended TPD for a BNCT clinical treatment is shallower than the deepest TPD(max), the usable (7)Li-target thickness would be between t(min) and an upper limit t(upper) whose value depends on the BDE thickness used. In terms of the effect of stability of the incident proton energy, Gaussian incident proton energies stable to within +/-10 keV of 1.900 MeV were found to be feasible for the neutron production via the near-threshold (7)Li(p,n)(7)Be reaction for BNCT provided that a suitable BDE is used.

  13. 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.

  14. 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.

  15. Study of the 3He(α,γ)7Be and 3H(α,γ)7Li reactions at astrophysical energies

    NASA Astrophysics Data System (ADS)

    Sadeghi, H.; Ghasemi, R.

    2014-06-01

    We have studied the important astrophysical 3He(α,γ)7Be and 3H(α,γ)7Li reactions in the framework of a potential model. 3He(α,γ)7Be and 3H(α,γ)7Li processes are key reactions in both bigbang nucleosynthesis and the p-p chain of hydrogen-burning in stars. The stellar 3He(α,γ)7Be and 3H(α,γ)7Li reactions were analyzed at low energies on the basis of a direct radiative capture mechanism. The astrophysical S-factors near zero energy were calculated without using the effective expansion of the S-factor or the asymptotic wave functions. In this paper, 3He(α,γ)7Be and 3H(α,γ)7Li radiative capture reactions at very low energies are taken as a case study. Using the M3Y potential, we have calculated the astrophysical S-factors for the E1 transition. In comparison with other theoretical methods and available experimental data, excellent agreement is achieved for the astrophysical S-factors of these processes.

  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. 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.

  18. Radiative capture of polarized deuterons by [sup 6]Li and the D-state of [sup 8]Be

    SciTech Connect

    Williams, J.Z. Jr.

    1992-01-01

    Measurements of angular distributions of the cross section, [sigma]([theta]), and vector and tensor analyzing powers have been obtained at E[sub d] (lab) = 9.0 MeV and E[sub d] (lab) = 2.0 MeV for the [sup 6]Li([rvec d],[gamma])[sup 8]Be reaction. The measured analyzing powers include A[sub yy]([theta]) and A[sub y]([theta]) at E[sub d] (lab) = 2.0 MeV and A[sub yy] ([theta]), A[sub y] ([theta]) and T[sub 20]([theta]) at E[sub d] (lab) = 9.0 MeV. Energy excitation functions of the differential cross section, [sigma]([theta]) at [theta] = 130[degrees] were measured from E[sub d] (lab) = 7.0 MeV to E[sub d] (lab) = 14.0 MeV. Transition matrix element analyses of the angular distributions at E[sub d] (lab) = 9.0 MeV and E[sub d] (lab) = 2.0 MeV were performed. The results show the presence of 13% to 21% E1 radiation in addition to the dominant E2 radiation at E[sub d] (lab) = 9.0 MeV and a dominant E1 radiation contribution, instead of dominant E2 radiation, of 57% at E[sub d] (lab) = 2.0 MeV. The largest E1 component at both energies is the isospin forbidden E1 transition comprising 10% of the cross section at E[sub d] (lab) = 9.0 MeV and 40% of the cross section at E[sub d] (lab) = 2.0 MeV. The angular distributions at E[sub d] (lab) = 9.0 MeV were compared to a simple direct capture (DC) calculation. The dominant E2 direct capture calculation gave a reasonable description of the tensor analyzing power A[sub yy] ([theta]) but failed to reproduce the cross section [sigma]([theta]) and the vector analyzing power A[sub y]([theta]). This model leads to a D-state probability of P[sub D] = 0.5% for the ground state of [sup 8]Be. A multichannel resonating group model (MCRGM) calculation was also performed. This calculation provided a fairly good representation of the data and predicts a D-state probability of P[sub D] = 0.3% for the ground state of [sup 8]Be.

  19. 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.

  20. 7Li Spin-Lattice Relaxation at Low Temperatures in a Superionic Conductor β-LiGa

    NASA Astrophysics Data System (ADS)

    Endou, Shigeki; Ohno, Takashi; Kishimoto, Yutaka; Nishioka, Daisuke; Michihiro, Yoshitaka; Kawasaki, Yu; Ideta, Yukiichi; Kuriyama, Kazuo; Hamanaka, Hiromi; Yahagi, Masahito

    2009-10-01

    In order to investigate the Li+ ionic diffusion and the electronic states in a mixed conductor β-LiGa with high Li+ ionic diffusibility and electron/hole conductivity, 7Li NMR linewidth and spin-lattice relaxation measurements have been performed in 44.0, 47.0, and 50.0 at. % Li β-LiGa samples at 10.03 MHz in the temperature range between 10 and 320 K. The onset temperature TMN=70 K of the motional narrowing in 50.0 at. % sample has been determined from the temperature dependence of the linewidth. The Li+ ionic diffusion is found to contribute to the spin-lattice relaxation rate 1/T1 down to ˜0.5 TMN even below TMN where the motional narrowing does not occur. The high diffusibility of Li+ ions has been proved from a microscopic point of view. At low temperatures, the relations 1/T1T=3.5× 10-4, 3.8× 10-4, and 5.1× 10-4 s-1 K-1 are observed in 44.0, 47.0, and 50.0 at. % Li samples, respectively. The density of states of conduction electrons at the Fermi level in these compounds becomes higher with increasing Li content, which is consistent with the predictions by band calculations.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Cross-section measurements for 239Pu(n,f) and 6Li(n, α) with a lead slowing-down spectrometer

    NASA Astrophysics Data System (ADS)

    Rochman, D.; Haight, R. C.; O'Donnell, J. M.; Wender, S. A.; Vieira, D. J.; Bond, E. M.; Bredeweg, T. A.; Wilhelmy, J. B.; Granier, T.; Ethvignot, T.; Petit, M.; Danon, Y.; Romano, C.

    2006-08-01

    We present fission cross-section measurements with ˜10 ng of 239Pu performed using the LANSCE Lead Slowing-Down Spectrometer. Results of Li6(n,α) measurements with a sample size of 760 ng of 6Li are also reported. This technical achievement demonstrates the feasibility of measuring neutron-induced fission cross-section on samples with 10 ng of fissile actinides that are available on ultra-small quantities. Furthermore, results on neutron-induced alpha emission show that measurements for astrophysics purposes are feasible with the LSDS.

  8. Experimental study of the p+{sup 6}Li{yields}{eta}+{sup 7}Be reaction 11.3 MeV above threshold

    SciTech Connect

    Budzanowski, A.; Kliczewski, S.; Siudak, R.; Chatterjee, A.; Jha, V.; Roy, B. J.; Hawranek, P.; Magiera, A.; Jahn, R.; Kilian, K.; Maier, R.; Protic, D.; Ritman, J.; Rossen, P. von; Kirillov, Da.; Machner, H.; Kirillov, Di.; Piskunov, N.; Sitnik, I.; Kolev, D.

    2010-10-15

    The cross section for the reaction p+{sup 6}Li{yields}{eta}+{sup 7}Be was measured at an excess energy of 11.28 MeV above threshold by detecting the recoiling {sup 7}Be nuclei. A dedicated set of focal plane detectors was built for the magnetic spectrograph Big Karl and was used for identification and four-momentum measurement of {sup 7}Be. A differential cross section of nb/(d{sigma}/d{Omega})=[0.69{+-}0.20(stat.){+-}0.20(syst.)] sr for the ground state plus 1/2{sup -} was measured. The result is compared to model calculations.

  9. 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.

  10. 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.

  11. 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‰.

  12. 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.

  13. 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.

  14. Indirect study of the {sup 13}C({alpha},n){sup 16}O reaction via the {sup 13}C({sup 7}Li,t){sup 17}O transfer reaction

    SciTech Connect

    Pellegriti, M. G.; Hammache, F.; Roussel, P.; Audouin, L.; Beaumel, D.; Fortier, S.; Vilmay, M.; Descouvemont, P.; Gaudefroy, L.; Kiener, J.; Lefebvre-Schuhl, A.; Tatischeff, V.; Stanoiu, M.

    2008-04-15

    The {sup 13}C({alpha},n){sup 16}O reaction is considered the main neutron source for the s process in low mass asymptotic giant branch (AGB) stars. In the Gamow peak, the cross section sensitively depends on the 1/2{sup +} subthreshold state of {sup 17}O (E{sub x}=6.356 MeV). In this work, we determined the astrophysical S factor through an evaluation of the {alpha} spectroscopic factor and the corresponding asymptotic normalization factor (ANC) of the 6.356 MeV state using the transfer reaction {sup 13}C({sup 7}Li,t){sup 17}O at two different incident energies. Our result confirms that the contribution of the 1/2{sup +} state is dominant at astrophysical energies. Our reaction rate at T=0.09 GK is slightly lower than the value adopted in the Nuclear Astrophysics Compilation of REaction rates (NACRE), but two times larger than the one obtained in a recent ANC measurement.

  15. Highly enriched 7Be in the ejecta of Nova Sagittarii 2015 No. 2 (V5668 Sgr) and the Galactic 7Li origin

    NASA Astrophysics Data System (ADS)

    Molaro, P.; Izzo, L.; Mason, E.; Bonifacio, P.; Della Valle, M.

    2016-11-01

    We report on the evidence of highly blue-shifted resonance lines of the singly ionised isotope of 7BeII in high resolution UVES spectra of Nova Sagittarii 2015 No. 2 (V5668 Sgr). The resonance doublet lines 7BeII at lambda 313.0583, 313.1228 nm are clearly detected in several non saturated and partially resolved high velocity components during the evolution of the outburst. The total absorption identified with Beryllium has an equivalent width much larger than all other elements and comparable to hydrogen. We estimate an atomic fraction N(7Be)/N(Ca) ~ 53-69 from unsaturated and resolved absorption components. The detection of 7Be in several high velocity components shows that it has been freshly created in a thermonuclear runaway via the reaction 3He}(alpha,gamma) 7Be during the Nova explosion, as postulated by Arnould and Norgaard (1975) , however in much larger amounts than predicted by current models. 7Be decays to 7Li with a half-life of 53.22 days, comparable to the temporal span covered by the observations. The non detection of LiI requires that LiII remains ionised throughout our observations. The massive 7Be ejecta result into a 7Li production that is about 4.7-4.9 dex above the meteoritic abundance. If such a high production is common even in a small fraction (~5%) of Novae, they can make all the "stellar" 7Li of the Milky Way.

  16. Cluster structures of 18O and 20O up to 20 MeV excitation energy from the (7Li, p)-reaction

    NASA Astrophysics Data System (ADS)

    Dorsch, T.; Bohlen, H. G.; von Oertzen, W.; Krücken, R.; Faestermann, T.; Mahgoub, M.; Kokalova, T.; Wheldon, C.; Milin, M.; Wirth, H.; Hertenberger, R.

    2008-05-01

    We studied the band structure of 18O and 20O using the (7Li, p)-reaction at an incident energy of 44 MeV on 12C and 14C targets. Spectra have been measured from the ground state up to 20 MeV excitation energy. We found 27 and 38 new states for 18O and 20O, respectively. The even-parity bands have been analysed up to now, i.e., some bands were extended by further members. The 0+ band head of the molecular band in 18O at 7.796(5) MeV was identified for the first time.

  17. 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.

  18. (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.

  19. 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.

  20. 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}.

  1. Isotope shift in the electron affinity of lithium.

    PubMed

    Bubin, Sergiy; Komasa, Jacek; Stanke, Monika; Adamowicz, Ludwik

    2009-12-21

    Very accurate electron affinity (EA) calculations of (6)Li and (7)Li (and (infinity)Li) 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 (7)Li and (6)Li EAs are 4984.9842(30) and 4984.9015(30) cm(-1), respectively, and of the (7)Li/(6)Li EA isotope shift is 0.0827 cm(-1).

  2. Ab initio and kinetic Monte Carlo study of lithium diffusion in LiSi, Li12Si7, Li13Si5 and Li15Si4

    NASA Astrophysics Data System (ADS)

    Moon, Janghyuk; Lee, Byeongchan; Cho, Maenghyo; Cho, Kyeongjae

    2016-10-01

    The kinetics of lithium atoms in various Li-Si binary compounds are investigated using density functional theory calculations and kinetic Monte Carlo calculations. The values of the Li migration energy barriers are identified by NEB calculations with vacancy-mediated, interstitial and exchange migration mechanisms in crystalline LiSi, Li12Si7, Li13Si4, and Li15Si4. A comparison of these NEB results shows that the vacancy-mediated Li migration is identified as the dominant diffusion mechanisms in Li-Si compounds. The diffusion coefficients of Li in Li-Si compounds at room temperature are determined by KMC simulation. From the KMC results, the recalculated migration energy barriers in LiSi, Li12Si7, Li13Si4, and Li15Si4 correspond to 0.306, 0.301, 0.367 and 0.320 eV, respectively. Compared to the Li migration energy barrier of 0.6 eV in crystalline Si, the drastic reduction in the Li migration energy barriers in the lithiated silicon indicates that the initial lithiation of the Si anode is the rate-limiting step. Furthermore, it is also found that Si migration is possible in Li-rich configurations. On the basis of these findings, the underlying mechanisms of kinetics on the atomic scale details are elucidated.

  3. 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.

  4. Thermoluminescence of Ba 0.97Ca 0.03SO 4:Eu irradiated with 48 MeV 7Li ion beam

    NASA Astrophysics Data System (ADS)

    Lochab, S. P.; Salah, Numan; Sahare, P. D.; Chauhan, R. S.; Ranjan, Ranju

    2007-01-01

    Thermoluminescence (TL) of Ba0.97Ca0.03SO4:Eu phosphor, irradiated with 48 MeV 7Li ions at different fluences in the range 1 × 109-1 × 1012 ions/cm2, has been studied. The phosphor was prepared by the chemical co-precipitation technique. Its pellets were irradiated using a 16 MV Tandem Van de-Graff type Electrostatic Pelletron Accelerator at Inter-University Accelerator Centre, New Delhi, India. The samples from the same batch were also irradiated with γ-rays from a Cs137 source for comparative studies. It has been found that the TL glow peak at 460 K, seen prominently in γ-irradiated sample, appeared as a small shoulder at around 465 K in 7Li3+ ion irradiated sample, while that observed as a shoulder in the former at 430 K, dominantly appeared in the latter at around 435 K. Trapping parameters of both, ion beam and γ-irradiated materials, were also obtained after the deconvolution of the glow curves and discussed in the paper. The TL response curve of the ion beam irradiated samples has a linear ion beam fluence response over the range 1 × 109-1 × 1010 ions/cm2. This property along with its low fading and simple glow curve structure makes Ba0.97Ca0.03SO4:Eu phosphor a suitable dosimeter for heavy charged particles (HCP).

  5. Evaluation of the characteristics of boron-dose enhancer (BDE) materials for BNCT using near threshold 7Li(p,n)7Be direct neutrons.

    PubMed

    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.

  6. TPD-based evaluation of near threshold mono-energetic proton energies for the (7)Li(p,n)(7)Be production of neutrons for BNCT.

    PubMed

    Bengua, Gerard; Kobayashi, Tooru; Tanaka, Kenichi; Nakagawa, Yoshinobu; Unesaki, Hironobu

    2006-08-21

    An evaluation of mono-energetic proton energies ranging from 1.885 MeV to 1.920 MeV was carried out to determine the viability of these near threshold energies in producing neutrons for BNCT via the (7)Li(p,n)(7)Be reaction. Neutron fields generated at these proton energies were assessed using the treatable protocol depth (TPD) and the maximum TPD (TPD(max)) as evaluation indices. The heavy charged particle (HCP) dose rate to tumour was likewise applied as a figure of merit in order to account for irradiation time and required proton current. Incident proton energies closer to the reaction threshold generated deeper TPDs compared to higher energy protons when no boron dose enhancers (BDE) were placed in the irradiation field. Introducing a BDE resulted in improved TPDs for high proton energies but their achievable TPD(max) were comparatively lower than that obtained for lower proton energies. In terms of the HCP dose rate to tumour, higher proton energies generated neutron fields that yielded higher dose rates both at TPD(max) and at fixed depths of comparison. This infers that higher currents are required to deliver the prescribed treatment dose to tumours for proton beams with energies closer to the (7)Li(p,n)(7)Be reaction threshold and more achievable proton currents of around 10 mA or less for proton energies from 1.900 MeV and above. The dependence on incident proton energy of the TPD, TPD(max) and the HCP dose rate to tumour with respect to the (10)B concentration in tumour and healthy tissues were also clarified in this study. Increasing the (10)B concentration in tumour while maintaining a constant T/N ratio resulted in deeper TPD(max) where a greater change in TPD(max) was obtained for proton energies closer to the (7)Li(p,n)(7)Be reaction threshold. The HCP dose rates to tumour for all proton energies also went up, with the higher proton energies benefiting more from the increased (10)B concentration.

  7. 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.

  8. 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.

  9. 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

  10. On the ^7^Be^*^ and ^7^Li^*^ de-excitation lines as a possible explanation of the gamma-ray feature observed in Nova Muscae1991.

    NASA Astrophysics Data System (ADS)

    Durouchoux, P.; Viaud, P.; Wallyn, P.; Mahoney, W. A.

    1996-12-01

    We consider two different models to explain the gamma-ray feature detected on Nova Muscae 1991: a thermal electron-positron plasma and α-α reactions. In the first case, a direct fit to the data using the detailed model spectrum developed by Svensson (1983ApJ...270..300S) gives a redshifted line (z=0.048^+0.017^_-0.027_) coming from a relatively low temperature pair plasma (T~4x10^7^K). In the second case, a Monte Carlo simulation of ^7^Be^*^-^7^Li^*^ de-excitation lines following Ramaty et al. (1979ApJS...40..487R) (RKL79 hereafter), gives a best fit model with monoenergetic and isotropic α particles of ~10-25 MeV/nucleon or power-law distributions of isotropic α particles with index of ~2 to 3.

  11. 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.

  12. Measurements of neutron energy spectra from 7Li(p,n)7Be reaction with Bonner sphere spectrometer, Nested Neutron Spectrometer and ROSPEC.

    PubMed

    Atanackovic, J; Matysiak, W; Witharana, S; Dubeau, J; Waker, A J

    2014-10-01

    Neutron spectrometry measurements were carried out at the McMaster Accelerator Laboratory (MAL), which is equipped with a 3-MV Van de Graaff-type accelerator. Protons were accelerated onto a thick natural lithium target inducing the (7)Li(p,n)(7)Be threshold reaction. Depending on the proton energy, slightly different poly-energetic neutron fields were produced. Neutron spectra were measured at two incident proton energies: 2.15 and 2.24 MeV, which produced poly-energetic neutrons with maximum kinetic energies of 401 and 511 keV, respectively. Measurements were performed at a distance of 1.5 m from the target in the forward direction with three different instruments: Bonner sphere spectrometer, Nested Neutron Spectrometer and ROtational proton recoil SPECtrometer.

  13. Precise measurement of hyperfine structure in the 2P{sub 1/2} state of {sup 7}Li using saturated-absorption spectroscopy

    SciTech Connect

    Singh, Alok K.; Muanzuala, Lal; Natarajan, Vasant

    2010-10-15

    We report a precise measurement of the hyperfine interval in the 2P{sub 1/2} state of {sup 7}Li. The transition from the ground state (D{sub 1} line) is accessed using a diode laser and the technique of saturated-absorption spectroscopy in hot Li vapor. The interval is measured by locking an acousto-optic modulator to the frequency difference between the two hyperfine peaks. The measured interval of 92.040(6) MHz is consistent with an earlier measurement reported by us using an atomic-beam spectrometer [Das and Natarajan, J. Phys. B 41, 035001 (2008)]. The interval yields the magnetic dipole constant in the P{sub 1/2} state as A=46.047(3), which is discrepant from theoretical calculations by >80 kHz.

  14. Viscosity and carbon dioxide solubility for LiPF6, LiTFSI, and LiFAP in alkyl carbonates: lithium salt nature and concentration effect.

    PubMed

    Dougassa, Yvon Rodrigue; Jacquemin, Johan; El Ouatani, Loubna; Tessier, Cécile; Anouti, Mérièm

    2014-04-10

    In this paper, we have reported the CO2 solubility in different pure alkyl carbonate solvents (EC, DMC, EMC, DEC) and their binary mixtures as EC/DMC, EC/EMC, and EC/DEC and for electrolytes [solvent + lithium salt] LiX (X = LiPF6, LiTFSI, or LiFAP) as a function of the temperature and salt concentration. To understand the parameters that influence the structure of the solvents and their ability to dissolve CO2, through the addition of a salt, we first analyzed the viscosities of EC/DMC + LiX mixtures by means of a modified Jones-Dole equation. The results were discussed considering the order or disorder introduced by the salt into the solvent organization and ion solvation sphere by calculating the effective solute ion radius, rs. On the basis of these results, the analysis of the CO2 solubility variations with the salt addition was then evaluated and discussed by determining specific ion parameters Hi by using the Setchenov coefficients in solution. This study showed that the CO2 solubility has been affected by the shape, charge density, and size of the ions, which influence the structuring of the solvents through the addition of a salt and the type of solvation of the ions.

  15. 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.

  16. 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.

  17. The influence of high-energy 7Li ions on the TL response and glow curve structure of CaSO4 : Dy

    NASA Astrophysics Data System (ADS)

    Salah, Numan; Sahare, P. D.

    2006-07-01

    Thermoluminescence (TL) of CaSO4 : Dy phosphor, irradiated by 48 MeV 7Li ions with different fluences in the range 1 × 109-5 × 1011 ions cm-2 has been studied. The samples from the same batch were also exposed to γ-rays from a Co60 source for comparative studies. The TL glow curve of the material, irradiated with the ion beam has a simple structure with a prominent peak at around 494 K along with three small shoulders at around 424, 592 and 662 K. The TL saturation has been observed at around the fluence 1 × 1011 ions cm-2. As the fluence is increased from 1 × 109 to 5 × 1011 ions cm-2, a shift in the peak positions towards the lower temperature side, by around 7 K was observed. However, with increasing fluence, the TL glow curve structure remains invariant with no change in the relative intensities between the 494 and 424 K peaks, while in the case of γ-irradiated samples, in contrast, the intensity ratios of these peaks increase exponentially with exposures. Theoretical analysis of the glow curves of the ion beam and γ-irradiated samples was done by the glow curve deconvolution method. The efficiency of CaSO4 : Dy to 48 MeV 7Li ions has been measured relative to γ-rays of Co60 and found to be 0.81. This result, along with the observed good linearity over a large span of fluences, shows that this phosphor is quite suitable as a dosimeter for heavy charged particles.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. Experimental facility for reactor experiments on study of spectral-luminescent characteristics of nuclear-excited plasma

    NASA Astrophysics Data System (ADS)

    Gordienko, Yu N.; Batyrbekov, E. G.; Skakov, M. K.; Ponkratov, Yu V.; Khasenov, M. U.; Zaurbekova, Zh A.; Barsukov, N. I.; Kulsartov, T. V.; Tulubayev, Ye Yu

    2016-09-01

    The description of experimental facility and reactor ampoule device for carrying out the experiments on study of spectral-luminescent characteristics of nuclear-excited plasma formed by products of 6Li(n,α)T nuclear reaction under conditions of neutron irradiation is given in paper.

  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. Ab Initio Structure Search and in Situ 7Li NMR Studies of Discharge Products in the Li–S Battery System

    PubMed Central

    2014-01-01

    The high theoretical gravimetric capacity of the Li–S battery system makes it an attractive candidate for numerous energy storage applications. In practice, cell performance is plagued by low practical capacity and poor cycling. In an effort to explore the mechanism of the discharge with the goal of better understanding performance, we examine the Li–S phase diagram using computational techniques and complement this with an in situ 7Li NMR study of the cell during discharge. Both the computational and experimental studies are consistent with the suggestion that the only solid product formed in the cell is Li2S, formed soon after cell discharge is initiated. In situ NMR spectroscopy also allows the direct observation of soluble Li+-species during cell discharge; species that are known to be highly detrimental to capacity retention. We suggest that during the first discharge plateau, S is reduced to soluble polysulfide species concurrently with the formation of a solid component (Li2S) which forms near the beginning of the first plateau, in the cell configuration studied here. The NMR data suggest that the second plateau is defined by the reduction of the residual soluble species to solid product (Li2S). A ternary diagram is presented to rationalize the phases observed with NMR during the discharge pathway and provide thermodynamic underpinnings for the shape of the discharge profile as a function of cell composition. PMID:25384082

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Experimental differential cross sections, level densities, and spin cutoffs as a testing ground for nuclear reaction codes

    DOE PAGES

    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. The effectiveness of the high-LET radiations from the boron neutron capture [10B(n,α) 7Li] reaction determined for induction of chromosome aberrations and apoptosis in lymphocytes of human blood samples.

    PubMed

    Schmid, T E; Canella, L; Kudejova, P; Wagner, F M; Röhrmoser, A; Schmid, E

    2015-03-01

    Provided that a selective accumulation of (10)B-containing compounds is introduced in tumor cells, following irradiation by thermal neutrons produces high-LET alpha-particles ((4)He) and recoiling lithium-7 ((7)Li) nuclei emitted during the capture of thermalized neutrons (0.025 eV) from (10)B. To estimate the biological effectiveness of this boron neutron capture [(10)B(n,α)(7)Li] reaction, the chromosome aberration assay and the flow cytometry apoptosis assay were applied. At the presence of the clinically used compounds BSH (sodium borocaptate) and BPA (p-boronophenylalanine), human lymphocytes were irradiated by sub-thermal neutrons. For analyzing chromosome aberrations, human lymphocytes were exposed to thermally equivalent neutron fluences of 1.82 × 10(11) cm(-2) or 7.30 × 10(11) cm(-2) (corresponding to thermal neutron doses of 0.062 and 0.248 Gy, respectively) in the presence of 0, 10, 20, and 30 ppm of BSH or BPA. Since the kerma coefficient of blood increased by 0.864 × 10(-12) Gy cm(2) per 10 ppm of (10)B, the kerma coefficients in blood increase from 0.34 × 10(-12) cm(2) (blood without BSH or BPA) up to 2.93 × 10(-12) Gy cm(2) in the presence of 30 ppm of (10)B. For the (10)B(n, α)(7)Li reaction, linear dose-response relations for dicentrics with coefficients α = 0.0546 ± 0.0081 Gy(-1) for BSH and α = 0.0654 ± 0.0075 Gy(-1) for BPA were obtained at 0.062 Gy as well as α = 0.0985 ± 0.0284 Gy(-1) for BSH and α = 0.1293 ± 0.0419 Gy(-1) for BPA at 0.248 Gy. At both doses, the corresponding (10)B(n, α)(7)Li reactions from BSH and BPA are not significantly different. A linear dose-response relation for dicentrics also was obtained for the induction of apoptosis by the (10)B(n, α)(7)Li reaction at 0.248 Gy. The linear coefficients α = 0.0249 ± 0.0119 Gy(-1) for BSH and α = 0.0334 ± 0.0064 Gy(-1) for BPA are not significantly different. Independently of the applied thermal neutron doses of

  15. Nuclear Astrophysics and Structure Studies Using Low-energy RI Beams at CRIB

    SciTech Connect

    Yamaguchi, H.; Hashimoto, T.; Hayakawa, S.; Binh, D. N.; Kahl, D.; Kubono, S.

    2010-05-12

    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, (alpha,p) reactions, and others were peformed in recent years, mainly for studying astrophysical reactions and exotic nuclear structure. Among them, the results on the {sup 7}Be+p and {sup 7}Li+alpha resonance scatterings are presented.

  16. 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.

  17. Measurements of the neutron yields from 7Li(p,n)7Be reaction (thick target) with incident energies from 1.885 to 2.0 MeV.

    PubMed

    Yu, W; Yue, G; Han, X; Chen, J; Tian, B

    1998-07-01

    Accelerator-based neutron source have been considered to be practical for boron neutron capture therapy (BNCT). Based on experience with a parameters of the Brookhaven National Laboratory BMRR reactor neutron source, which has been used in treatment experiments, the future accelerator-based neutron source for BNCT should have the properties of low energy distribution (< 100 keV) and high flux (about 10(9) neutrons per second per square centimeter) in the patient zone. Using protons to bombard thick 7Li targets, generating neutrons via the 7Li(p,n)7Be reaction, is one of the optimal choices for this kind of neutron source. Neutron yield data versus incident energy are necessary in order to select the proper incident energy and for estimating how high the incident proton current should be. The required proton beam current intensity is one of the key parameters for an accelerator useful for BNCT. In the present work, neutron yields of the 7Li(p,n)7Be reaction with a thick lithium target and incident energies of 1.885 and 1.9 MeV were measured at 0 degree with respect to the incident beam direction. The results are (3.08 +/- 0.17) x 10(12) and (5.71 +/- 0.32) x 10(12) neutrons/C sr, respectively. Neutron yield angular distribution measurements at 2 MeV incident energy were also performed. The proton beams were generated by the Peking University 4.5 MV electrostatic accelerator. The emitted neutrons from these reactions have the advantages of low energy distribution and forward angular distribution, which are requirements for a BNCT neutron source. The data obtained in this work can be used as a reference to study the accelerator-based neutron sources for BNCT.

  18. 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.

  19. Neutron spectrometer for fast nuclear reactors

    NASA Astrophysics Data System (ADS)

    Osipenko, M.; Ripani, M.; Ricco, G.; Caiffi, B.; Pompili, F.; Pillon, M.; Angelone, M.; Verona-Rinati, G.; Cardarelli, R.; Mila, G.; Argiro, S.

    2015-11-01

    In this paper we describe the development and first tests of a neutron spectrometer designed for high flux environments, such as the ones found in fast nuclear reactors. The spectrometer is based on the conversion of neutrons impinging on 6Li into α and t whose total energy comprises the initial neutron energy and the reaction Q-value. The 6LiF layer is sandwiched between two CVD diamond detectors, which measure the two reaction products in coincidence. The spectrometer was calibrated at two neutron energies in well known thermal and 3 MeV neutron fluxes. The measured neutron detection efficiency varies from 4.2 ×10-4 to 3.5 ×10-8 for thermal and 3 MeV neutrons, respectively. These values are in agreement with Geant4 simulations and close to simple estimates based on the knowledge of the 6Li(n,α)t cross-section. The energy resolution of the spectrometer was found to be better than 100 keV when using 2.5 or 5 m cables between the detector and the preamplifiers.

  20. Extended optical model analyses of elastic scattering and fusion cross sections for the {sup 6}Li+{sup 208}Pb system at near-Coulomb-barrier energies using a folding potential

    SciTech Connect

    So, W. Y.; Udagawa, T.; Kim, K. S.; Hong, S. W.; Kim, B. T.

    2007-02-15

    Based on the extended optical model approach in which the polarization potential is decomposed into direct reaction (DR) and fusion parts, simultaneous {chi}{sup 2} analyses are performed for elastic scattering and fusion cross section data for the {sup 6}Li+{sup 208}Pb system at near-Coulomb-barrier energies. A folding potential is used as the bare potential. It is found that the real part of the resultant DR part of the polarization potential is repulsive, which is consistent with the results from the continuum discretized coupled channel (CDCC) calculations and the normalization factors needed for the folding potentials. Further, it is found that both DR and fusion parts of the polarization potential satisfy separately the dispersion relation.

  1. 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.

  2. 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.

  3. 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.

  4. 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)

  5. Electrochemical performance and 7Li NMR studies on an inverse spinel LiNi 1/3Co 1/3Mn 1/3VO 4 for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Fey, George Ting-Kuo; Muralidharan, P.; Cho, Yung-Da; Chang, Pai-Ching; Kao, Hsien-Ming

    A new inverse spinel LiNi 1/3Co 1/3Mn 1/3VO 4 cathode material was synthesized through a citric acid assisted polyethylene glycol (CA:PEG; 3:1, 3:0.5 and 3:0) polymeric method, followed by calcination at 723 K for 5 h in air. The synthesized compound was characterized by TG/DTGA, XRD, FTIR, TEM, and 7Li NMR techniques. TG/DTGA curves showed that the formation of LiNi 1/3Co 1/3Mn 1/3VO 4 occurred between 523 and 673 K and the phase pure crystalline formed at 723 K, as also confirmed by XRD analysis which showed that the crystalline phase peaks formed when heated at 723 K for 5 h in air. TEM images revealed that nanosized particles ranged ∼170-190 nm. FTIR spectra showed that all organic residues were removed and LiNi 1/3Co 1/3Mn 1/3VO 4 formed. The 7Li MAS NMR spectrum of the LiNi 1/3Co 1/3Mn 1/3VO 4 sample revealed that the paramagnetic effect is small and small side band manifolds were observed. The galvanostatic cycling study suggests that the cycle stability and capacity retention were enhanced for LiNi 1/3Co 1/3Mn 1/3VO 4 prepared with a CA:PEG molar ratio of 3:1 when it was cycled between 2.8 and 4.9 V (versus Li) at a 0.15 C rate. The electrochemical impedance behavior suggested that a passive layer was formed on the surface of the cathode materials during continuous cycling.

  6. 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.

  7. 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

  8. 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.

  9. Effect of nuclear-reaction mechanisms on the population of excited nuclear states and isomeric ratios

    NASA Astrophysics Data System (ADS)

    Skobelev, N. K.

    2016-07-01

    Experimental data on the cross sections for channels of fusion and transfer reactions induced by beams of radioactive halo nuclei and clustered and stable loosely bound nuclei were analyzed, and the results of this analysis were summarized. The interplay of the excitation of single-particle states in reaction-product nuclei and direct reaction channels was established for transfer reactions. Respective experiments were performed in stable (6Li) and radioactive (6He) beams of the DRIBs accelerator complex at the Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, and in deuteron and 3He beams of the U-120M cyclotron at the Nuclear Physics Institute, Academy Sciences of Czech Republic (Řež and Prague, Czech Republic). Data on subbarrier and near-barrier fusion reactions involving clustered and loosely bound light nuclei (6Li and 3He) can be described quite reliably within simple evaporation models with allowance for different reaction Q-values and couple channels. In reactions involving halo nuclei, their structure manifests itself most strongly in the region of energies below the Coulomb barrier. Neutron transfer occurs with a high probability in the interactions of all loosely bound nuclei with light and heavy stable nuclei at positive Q-values. The cross sections for such reactions and the respective isomeric ratios differ drastically for nucleon stripping and nucleon pickup mechanisms. This is due to the difference in the population probabilities for excited single-particle states.

  10. 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.

  11. Production of 93mMo through natY(7Li, 3n) reaction and subsequent studies on separation and extraction behaviour of no-carrier-added 93mMo from an yttrium target.

    PubMed

    Nayak, Dalia; Lahiri, Susanta

    2008-12-01

    The present work reports heavy-ion-assisted production of (93m)Mo from a natural yttrium target using the (89)Y((7)Li, 3n)(93m)Mo reaction. Three different methodologies based on liquid-liquid extraction (LLX), aqueous biphasic extraction and precipitation, have been developed for separation and extraction of no-carrier-added (nca) (93m)Mo (T(1/2)=6.85h) radionuclide from bulk yttrium target. Complete separation of nca Mo from the target Y has been achieved by employing LLX technique with 0.1M trioctylamine (TOA) dissolved in cyclohexane and 8M HCl. Quantitative separation of (93m)Mo from the yttrium target is also possible by precipitating bulk yttrium with 1M oxalic acid. However, for this particular case, studies have shown that the aqueous biphasic extraction is not the method of choice for separation of nca Mo. Nevertheless, the extraction pattern is important in the context of simulation experiments for studying the behaviour of (106)Sg. Similarity or dissimilarity between the extraction patterns in various analytical systems will be helpful to decisively place Sg in the right position in the periodic table.

  12. Relaxation times of spin states of all ranks and orders of quadrupolar nuclei estimated from NMR z-spectra: Markov chain Monte Carlo analysis applied to 7Li+ and 23Na+ in stretched hydrogels.

    PubMed

    Kuchel, Philip W; Naumann, Christoph; Puckeridge, Max; Chapman, Bogdan E; Szekely, David

    2011-09-01

    The NMR z-spectra of 7Li+ and 23Na+ in stretched hydrogels contain five minima, or critical values, with a sharp "dagger" on the central dip. The mathematical representation of such z-spectra from spin-3/2 nuclei contains nine distinct (the total is 15 but there is redundancy of the ±order-numbers) relaxation rate constants that are unique for each of the spin states, up to rank 3, order 3. We present an approach to multiple-parameter-value estimation that exploits the high level of separability of the effects of each of the relaxation rate constants on the features of the z-spectrum. The Markov chain Monte Carlo (MCMC) method is computationally demanding but it yielded statistically robust estimates (low coefficients of variation) of the parameter values. We describe the implementation of the MCMC analysis (in the present context) and posit that it can obviate the need for using multiple-quantum filtered RF-pulse sequences to estimate all relaxation rate constants/times under experimentally favorable, but readily achievable, circumstances.

  13. 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.

  14. 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.

  15. 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.

  16. A Comparitive Study of the Experimental Features of the Bose-Einstein Condensates of 7Li, 23Na, 41K, 85Rb, 87Rb and 133Cs via a Linearly Perturbed Harmonic Oscillator Potential

    NASA Astrophysics Data System (ADS)

    Malik, G. P.; Varma, V. S.

    2013-05-01

    We show that the observed features of the above-named Bose-Einstein condensates can be understood via an effective confining potential of the form of: $V(r, T) = (1)/(2)mω 2[r^2+2(√ {(kT)/(mω ^2)})br ], \\quad (r = \\vertr \\vert) where T denotes the temperature, m the mass of an atom of the trapped gas, ω the geometric mean of the three frequencies used for confinement, k the Boltzmann constant and b a dimensionless perturbation parameter. Such an exercise is undertaken because Tcs calculated via earlier treatments based solely on an r2-potential lead to a mismatch with the experimental values. We fix b by substituting the density of states corresponding to V(r, T) into the equation for the number of excited atoms N} exc(T) and appealing to the experimental data at T = Tc. The values of b thus found are: 1.3426 (7Li), 1.8420 (23Na), 0.4998 (41K), 0.3486 (85Rb), 1.5332 (87Rb) and 1.2430 (133Cs). While these are used to calculate Nexc(T) for each of the condensates at T = Tc/2 and Tc/10, we also report on: (a) the variation of b for each condensate for some selected values of the pair (N} exc, Tc) and (b) the possibility of realizing the state (Nexc, pTc; p (a number) ≫1) for all of these condensates with a unique value of b, even though the parameter-sets {m, ω, Nexc, Tc} characterizing them differ widely. Attention is drawn to diverse fields where T-dependent Hamiltonians have found useful application.

  17. Characterization of moderator assembly dimension for accelerator boron neutron capture therapy of brain tumors using 7Li(p, n) neutrons at proton energy of 2.5 MeV.

    PubMed

    Tanaka, Kenichi; Kobayashi, Tooru; Bengua, Gerard; Nakagawa, Yoshinobu; Endo, Satoru; Hoshi, Masaharu

    2006-06-01

    The characteristics of moderator assembly dimension are investigated for the usage of 7Li(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 D2O 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. PMID:16872076

  18. 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.

  19. 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.

  20. 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

  1. Natural variations of lithium isotopes in a mammalian model.

    PubMed

    Balter, Vincent; Vigier, Nathalie

    2014-03-01

    Despite lithium's extensive clinical applications, the cellular and molecular basis for the therapeutic effects remains to be elucidated. The large difference in mass between the two lithium isotopes ((6)Li and (7)Li) has prompted biochemists to explore the metabolism of Li by using pure (6)Li and (7)Li labeled drugs. However, experiments were carried out at very high Li concentrations, which did not reflect natural conditions. In the present study, we consider, for the first time, the natural variations of the (7)Li/(6)Li ratio in the organs and body fluids of an animal model, sheep. Each organ seems to be characterized by a specific Li isotope composition. So far, the range of the (7)Li/(6)Li ratio in the sheep body, expressed as δ permil variations relative to the L-SVEC standard (δ(7)Li), is about 40‰, between muscles (∼40‰) and kidney (∼0‰). Relative to a dietary δ(7)Li value of ∼+17‰, serum, red blood cells, muscle, liver, brain and kidney have a (7)Li enrichment of -12‰, -14‰, +22‰, +5‰, -3‰ and -15‰, respectively. The Li isotope composition is likely to be fractionated during intestinal absorption, with a greater absorption of (6)Li relative to (7)Li. According to previous conclusions obtained with (6)Li and (7)Li labeled chemicals, (6)Li appears to diffuse into erythrocytes faster than does (7)Li. However, this does not hold for myocytes and hepatocytes, because these two tissues have a higher δ(7)Li level than serum. Purely diffusive isotopic fractionation would leave all organs (7)Li-depleted relative to the serum, which is not the case, suggesting that active, molecule-specific, isotopic fractionation occurs in the body. Our preliminary results suggest that natural Li isotope variations can shed light on its regulation in the body, being active or passive.

  2. 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).

  3. 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.

  4. 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.

  5. Nuclear Charge Radii of Li-8,Li-9 Determined by Laser Spectroscopy

    SciTech Connect

    Ewald, G; Nortershauser, W.; Dax, A ..; Gotte, S; Kirchner, Rolf; Kluge, H J.; Kuhl, T H.; Sanchez, R J.; Wojtasek, Alesia S.; Bushaw, Bruce A.; Drake, Gordon W. F.; Yan, Z C.; Zimmerman, Colin H.

    2004-09-09

    The 2S ' 3S transition of 6,7,8,9 Li was studied by high-resolution laser spectroscopy using two-photon Doppler-free excitation and resonance-ionization detection. The hyperfine structure splitting and the isotope shift were determined with precision at the 100 kHz level. Combined with recent theoretical work, the changes in nuclear charge radii of 8,9Li were determined. These are now the lightest short-lived isotopes for which the charge radii have been measured. It is found that the charge radii monotonically decrease with increasing neutron number from 6Li to 9Li.

  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. 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°.

  9. 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%.

  10. 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

  11. 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.

  12. Physical interpretation of astrophysical factor S(E) for stellar energies from the WKB approximation.

    NASA Astrophysics Data System (ADS)

    Beaumevieille, H.; Bouchemha, A.; Boudouma, Y.; Boughrara, A.; Ouichaoui, S.; Tsan, U. C.

    1999-02-01

    For "non-resonant" reactions, a physical interpretation of the astrophysical factor S(E) in terms of the Coulomb barrier penetration factor and an intrinsic nuclear factor is proposed. Using the WKB (Wentzel, Kramers, Brillouin) approximation to evaluate the penetrabilities at stellar energies, the authors point out a drastic difference between the absolute values if S(0) according to wether s or p waves dominate the reaction. The variation with energy of S(E) to first order can also sign the nature of the wave. An application for the 6Li(d,α)4He and 7Li(p,α)4He reactions is presented.

  13. 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.

  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. 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.

  16. 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.

  17. Tritium speciation in nuclear reactor bioshield concrete and its impact on accurate analysis.

    PubMed

    Kim, Dae Ji; E Warwick, Phillip; Croudace, Ian W

    2008-07-15

    Tritium ((3)H) is produced in nuclear reactors via several neutron-induced reactions [(2)H(n, gamma)(3)H, (6)Li(n, alpha)(3)H, (10)B(n, 2alpha)(3)H, (14)N(n, (3)H)(12)C, and ternary fission (fission yield <0.01%)]. Typically, (3)H is present as tritiated water (HTO) and can become adsorbed into structural concrete from the surface inward where it will be held in a weakly bound form. However, a systematic analysis of a sequence of subsamples taken from a reactor bioshield using combustion and liquid scintillation analysis has identified two forms of (3)H, one weakly bound and one strongly bound. The strongly bound tritium, which originates from neutron capture on trace lithium ((6)Li) within mineral phases, requires temperatures in excess of 350 degrees C to achieve quantitative recovery. The weakly bound form of tritium can be liberated at significantly lower temperatures (100 degrees C) as HTO and is associated with dehydration of hydrous mineral components. Without an appreciation that two forms of tritium can exist in reactor bioshields, the (3)H content of samples may be severely underestimated using conventional analytical approaches. These findings exemplify the need to develop robust radioactive waste characterization procedures in support of nuclear decommissioning programs. PMID:18543953

  18. Tritium speciation in nuclear reactor bioshield concrete and its impact on accurate analysis.

    PubMed

    Kim, Dae Ji; E Warwick, Phillip; Croudace, Ian W

    2008-07-15

    Tritium ((3)H) is produced in nuclear reactors via several neutron-induced reactions [(2)H(n, gamma)(3)H, (6)Li(n, alpha)(3)H, (10)B(n, 2alpha)(3)H, (14)N(n, (3)H)(12)C, and ternary fission (fission yield <0.01%)]. Typically, (3)H is present as tritiated water (HTO) and can become adsorbed into structural concrete from the surface inward where it will be held in a weakly bound form. However, a systematic analysis of a sequence of subsamples taken from a reactor bioshield using combustion and liquid scintillation analysis has identified two forms of (3)H, one weakly bound and one strongly bound. The strongly bound tritium, which originates from neutron capture on trace lithium ((6)Li) within mineral phases, requires temperatures in excess of 350 degrees C to achieve quantitative recovery. The weakly bound form of tritium can be liberated at significantly lower temperatures (100 degrees C) as HTO and is associated with dehydration of hydrous mineral components. Without an appreciation that two forms of tritium can exist in reactor bioshields, the (3)H content of samples may be severely underestimated using conventional analytical approaches. These findings exemplify the need to develop robust radioactive waste characterization procedures in support of nuclear decommissioning programs.

  19. 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.

  20. Isotope shift of the 32S 1/2 -22S 1/2 transition in lithium and the nuclear polarizability.

    PubMed

    Puchalski, M; Moro, A M; Pachucki, K

    2006-09-29

    High precision calculation of the isotope shift of the 3(2)S(1/2)-2(2)S(1/2) transition in lithium is presented. The wave function and matrix elements of relativistic operators are obtained by using recursion relations. Apart from the relativistic contribution, we obtain the nuclear polarizability correction for 11Li. The resulting difference of the squared charge radii 11Li-7Li based on the measurements of Sánchez et al. [Phys. Rev. Lett. 96, 033002 (2006)10.1103/PhysRevLett.96.033002] is deltar(ch)(2)=0.157(81) fm(2), which significantly differs from the previous evaluation.

  1. Crystal structure of a new variety of lead dodecaborate Pb{sub 6}(Li{sub 0.65}Na{sub 0.19})[B{sub 12}O{sub 24}]I{sub 0.84} {center_dot} 0.168H{sub 2}O and its comparison with beryl and cordierite

    SciTech Connect

    Belokoneva, E. L. Derkach, I. K.; Dimitrova, O. V.

    2013-05-15

    Crystals of a new representative of ring-radical dodecaborates Pb{sub 6}(Li{sub 0.65}Na{sub 0.19})[B{sub 12}O{sub 24}]I{sub 0.84} {center_dot} 0.168H{sub 2}O, space group R3bar m , are obtained under hydrothermal conditions. The structure is determined with-out preliminary knowledge of the chemical formula. It is close to that of the Pb{sub 6}[B{sub 12}O{sub 24}] {center_dot} H{sub 2}O dodecaborate studied earlier, but unlike the latter structure it contains admixtures of iodide anion, lithium cation, and water molecule, which incompletely populate positions in channels. The formation of the second variety, which brings to light ion-exchange properties of the crystals, is due to mineralizing ions available in the concen-trated solution in the course of crystallization. The new compound is compared with beryl and cordierite, which have close structures with channels capable of capturing various groups. Structures of synthetic Na and Ag dodecaborates with analogous but distorted ring dodecaborate radicals are discussed.

  2. Airy minima in the scattering of weakly bound light heavy ions

    NASA Astrophysics Data System (ADS)

    Michel, F.; Ohkubo, S.

    2005-11-01

    We reanalyze the existing 6Li + 12C elastic scattering angular distributions for incident energies ranging from a few MeV to 318 MeV within the frame of the optical model. Despite the important breakup effects expected in the scattering of such a fragile projectile, the system is found to display a surprising transparency. Indeed the barrier-wave/internal-wave decomposition of the elastic scattering amplitude reveals that a substantial part of the incident flux that penetrates the nuclear interior reemerges in the elastic channel, and typical refractive effects, like Airy minima, are clearly identified in the angular distributions. Coupled channel calculations performed on 12C(6Li,6Li')12C*(Jπ=2+,Ex=4.44 MeV) angular distributions extending through the whole angular range confirm the existence of an important internal-wave contribution in the backward hemisphere. A similar transparency is observed in other systems of this mass region, such as 7Li + 12C or 6Li + 16O. Finally, we examine recent 6He + 12C elastic scattering data obtained at 18 MeV by Milin et al. [Nucl. Phys. A730, 285 (2004)] and extending up to θc.m.≃85°, and we suggest additional measurements that could ascertain whether some transparency persists in the scattering of this radioactive projectile.

  3. 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.

  4. Nuclear Spectroscopy with HELIOS

    NASA Astrophysics Data System (ADS)

    Hoffman, Calem

    2013-04-01

    Direct reaction studies have been instrumental in achieving our current understanding of nuclear structure through the measurement of angular distributions, the extraction of spectroscopic factors, and the determination of single-particle centroids. Traditionally, these experiments were carried out using a beam of light particles impinging on a heavy stable target. Over the last decade this important technique has been used with short-lived radioactive ion beams requiring these types of reactions to be carried out in inverse kinematics. There are numerous challenges to this approach, not least is the typical Q-value resolution being up to an order of magnitude worse than traditional measurements due mainly to the so-called kinematic compression. The Helical Orbit Spectrometer (HELIOS) is a detection system developed for the specific purpose of improving the Q value resolution for inverse direct reaction measurements, while also maintaining flexibility and high efficiency. The novel feature of HELIOS is use of a 3 Tesla solenoid inside which the reactions take place. This allows for light particles of interest to be measured at fixed longitudinal distances from the target as opposed to fixed laboratory angles. The subtle mapping from laboratory angle to longitudinal position removes the aforementioned kinematic compression effect improving the Q-value resolution by as much as a factor of five without out sacrificing detection efficiency. In addition, HELIOS provides a natural way to identify particles of interest, independent of energy, through their measured cyclotron period. The design and implementation of HELIOS at the Argonne Tandem Linear Accelerator System (ATLAS) on the site of Argonne National Laboratory will be presented. The device has been extremely successful as numerous early measurements have been conducted spanning masses A=11 to 136, using varying reactions such as (d,p), (d,^3He), and (^6LI,d), as well as a range of beam energies. Physics

  5. 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.

  6. 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.

  7. Nuclear ventriculography

    MedlinePlus

    ... ventriculography (RNV); Multiple gate acquisition scan (MUGA); Nuclear cardiology; Cardiomyopathy - nuclear ventriculography ... 56. Udelson JE, Dilsizian V, Bonow RO. Nuclear cardiology. In: Bonow RO, Mann DL, Zipes DP, Libby ...

  8. 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)

  9. 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.

  10. 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].

  11. 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.

  12. Nuclear Theory - Nuclear Power

    NASA Astrophysics Data System (ADS)

    Svenne, J. P.; Canton, L.; Kozier, K. S.

    2008-01-01

    The results from modern nuclear theory are accurate and reliable enough to be used for practical applications, in particular for scattering that involves few-nucleon systems of importance to nuclear power. Using well-established nucleon-nucleon (NN) interactions that fit well the NN scattering data, and the AGS form of the three-body theory, we have performed precise calculations of low-energy neutron-deuteron (n+d) scattering. We show that three-nucleon force effects that have impact on the low-energy vector analyzing powers have no practical effects on the angular distribution of the n+d cross-section. There appear to be problems for this scattering in the evaluated nuclear data file (ENDF) libraries, at the incident neutron energies less than 3.2 MeV. Supporting experimental data in this energy region are rather old (>25 years), sparse and often inconsistent. Our three-body results at low energies, 50 keV to 10.0 MeV, are compared to the ENDF/B-VII.0 and JENDL (Japanese Evaluated Nuclear Data Library) -3.3 evaluated angular distributions. The impact of these results on the calculated reactivity for various critical systems involving heavy water is shown.

  13. 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.

  14. Nuclear choices

    SciTech Connect

    Wolfson, R.

    1991-01-01

    This book contains part of the series New Liberal Arts, which is intended to make science and technology more accessible to students of the liberal arts. Volume in hand provides a comprehensive, multifaceted examination of nuclear energy, in nontechnical terms. Wolfson explains the basics of nuclear energy and radiation, nuclear power..., and nuclear weapons..., and he invites readers to make their own judgments on controversial nuclear issues. Illustrated with photos and diagrams. Each chapter contains suggestions for additional reading and a glossary. For policy, science, and general collections in all libraries. (ES) Topics contained include Atoms and nuclei. Effects and uses of radiation. Energy and People. Reactor safety. Nuclear strategy. Defense in the nuclear age. Nuclear power, nuclear weapons, and nuclear futures.

  15. Dose and dose averaged LET comparison of {sup 1}H, {sup 4}He, {sup 6}Li, {sup 8}Be, {sup 10}B, {sup 12}C, {sup 14}N, and {sup 16}O ion beams forming a spread-out Bragg peak

    SciTech Connect

    Kantemiris, I.; Karaiskos, P.; Papagiannis, P.; Angelopoulos, A.

    2011-12-15

    Purpose: Modern clinical accelerators are capable of producing ion beams from protons up to neon. This work compares the depth dose distribution and corresponding dose averaged linear energy transfer (LET) distribution, which is related to the biological effectiveness, for different ion beams ({sup 1}H, {sup 4}He, {sup 6}Li, {sup 8}Be, {sup 10}B, {sup 12}C, {sup 14}N, and {sup 16}O) using multi-energetic spectra in order to configure spread-out Bragg peaks (SOBP). Methods: Monte Carlo simulations were performed in order to configure a 5 cm SOBP at 8 cm depth in water for all the different ion beams. Physical dose and dose averaged LET distributions as a function of depth were then calculated and compared. The superposition of dose distribution of all ions is also presented for a two opposing fields configuration. Additional simulations were performed for {sup 12}C beams to investigate the dependence of dose and dose averaged LET distributions on target depth and size, as well as beam configuration. These included simulations for a 3 cm SOBP at 7, 10, and 13 cm depth in water, a 6 cm SOBP at 7 depth in water, and two opposing fields of 6 cm SOBP. Results: Alpha particles and protons present superior physical depth dose distributions relative to the rest of the beams studied. Dose averaged LET distributions results suggest higher biological effectiveness in the target volume for carbon, nitrogen and oxygen ions. This is coupled, however, with relatively high LET values--especially for the last two ion species--outside the SOBP where healthy tissue would be located. Dose averaged LET distributions for {sup 8}Be and {sup 10}B beams show that they could be attractive alternatives to {sup 12}C for the treatment of small, not deeply seated lesions. The potential therapeutic effect of different ion beams studied in this work depends on target volume and position, as well as the number of beams used. Conclusions: The optimization of beam modality for specific tumor cites

  16. Boundaries for martensitic transition of 7Li under pressure

    DOE PAGES

    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

  17. 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

  18. 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

  19. New lithium copper borates with BO3 triangles: Li6CuB4O10, Li3CuB3O7, Li8Cu7B14O32, and Li2Cu9B12O28.

    PubMed

    Kuratieva, N V; Bànki, M; Tsirlin, A A; Eckert, J; Ehrenberg, H; Mikhailova, D

    2013-12-16

    Crystal structures of three new lithium copper borates, Li3CuB3O7, Li8Cu7B14O32, and Li2Cu9B12O28, and a new Li6CuB4O10 polymorph were solved by single-crystal X-ray diffraction. In all of the structures, the boron cations form BO3 triangles, which are connected with each other and with copper polyhedra only via corners in Li6CuB4O10 and Li3CuB3O7 and via both corners and edges in Li8Cu7B14O32 and Li2Cu9B12O28. The Li3CuB3O7 and Li8Cu7B14O32 compounds were synthesized as pure samples with only trace amounts of impurities; hence, their magnetic properties could be investigated and analyzed in terms of underlying magnetic couplings. Other compositions always represented multiphase mixtures. Li3CuB3O7 features infinite Cu,O chains formed by Cu2O6 units consisting of edge-shared CuO4 squares. Together with two apical oxygen atoms with long interatomic Cu-O distances of 2.7-2.8 Å, the Cu2O6 units form chains extended along the a axis. These pseudochains are responsible for strong anisotropic thermal expansion behavior. The temperature dependence of the magnetization between 4 and 380 K for Li3CuB3O7 could be fit well by a spin-dimer model. The magnetic susceptibility of Li8Cu7B14O32 showed a more complex temperature dependence, with two different Curie-Weiss regimes in the temperature range of 2-380 K. PMID:24266792

  20. 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

  1. 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)

  2. 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)

  3. 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 ...

  4. 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)

  5. 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.``

  6. 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

  7. Nuclear mortality

    SciTech Connect

    Krauthammer, C.

    1983-10-01

    The author notes that the anti-nuclear movement is shifting its focus from bodily harm to concern for the impact on our souls from building and threatening the use of nuclear weapons. Two aspects of nuclear deterrence receiving the most public attention are the freeze effort to halt weapons modernization and the no-first-use effort to take down the nuclear umbrella. Opponents attack both the countervalue and the counterforce approach, but the arguments of the Catholic bishops, Jonathan Schell, and others stop short of unilateral disarmament, which would be the greatest threat to our survival. Mr. Krauthammer observes that nuclear deterrence has worked, however, and will continue to be useful only if potential adversaries believe we have the will to use nuclear weapons. 2 references. (DCK)

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. Nuclear Astrophysics

    NASA Astrophysics Data System (ADS)

    Drago, Alessandro

    2005-04-01

    The activity of the Italian nuclear physicists community in the field of Nuclear Astrophysics is reported. The researches here described have been performed within the project "Fisica teorica del nucleo e dei sistemi a multi corpi", supported by the Ministero dell'Istruzione, dell'Università e della Ricerca.

  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. 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)

  15. Nuclear hostages

    SciTech Connect

    O'Keefe, B.J.

    1983-01-01

    Classical physics since Roentgen's discovery of X-rays led quickly to work on atomic structure and the Nuclear Age. The author traces the history of decisions to pursue nuclear fission, the organization of the Manhattan Project, the compromises of the 1963 test ban treaty, and the dilemma of nuclear weapons development and deployment that now hold mankind hostage. He reviews the rationale for limited nuclear war, first strike, massive retaliation, non-proliferation, and the Strategic Arms Limitation Talks (SALT) treaties. He argues that the concepts of mobile MX weapons, fratricide, and population dispersal for civil defense are unworkable, suggesting a program of unilaterally withdrawing tactical nuclear weapons from Europe and strengthening intelligence and law-enforcement powers to withstand terrorist activity. Economic cooperation and political reconciliation may take a generation to achieve, but should be our national goal.

  16. 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.

  17. 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.

  18. 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

  19. Nuclear Astrophysics

    NASA Astrophysics Data System (ADS)

    Bombaci, Ignazio

    2003-04-01

    In this report I will try to illustrate some of the main research themes and "hot topics" in nuclear astrophysics. The particular aim of the present report is to briefly illustrate the research activities, in the field of nuclear astrophysics, performed by the Italian nuclear physicist community within the "Programma di Interesse Nazionale su Fisica Teorica del Nucleo e dei Sistemi a Molti Corpi" (National Research Program on Theoretical Physics of Nuclei and Many Body Systems) supported by the "Ministero dell'Istruzione dell'Università e della Ricerca".

  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. 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.

  3. Nuclear Disarmament.

    ERIC Educational Resources Information Center

    Johnson, Christopher

    1982-01-01

    Material about nuclear disarmament and the arms race should be included in secondary school curricula. Teachers can present this technical, controversial, and frightening material in a balanced and comprehensible way. Resources for instructional materials are listed. (PP)

  4. 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.

  5. 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)

  6. 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.

  7. 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.

  8. Nuclear Structure

    NASA Astrophysics Data System (ADS)

    Gargano, Angela

    2003-04-01

    An account of recent studies in the field of theoretical nuclear structure is reported. These studies concern essentially research activities performed under the Italian project "Fisica Teorica del Nucleo e dei Sistemi a Molti Corpi". Special attention is addressed to results obtained during the last two years as regards the development of new many-body techniques as well as the interpretation of new experimental aspects of nuclear structure.

  9. Nuclear astrophysics

    NASA Astrophysics Data System (ADS)

    Arnould, M.; Takahashi, K.

    1999-03-01

    Nuclear astrophysics is that branch of astrophysics which helps understanding of the Universe, or at least some of its many faces, through the knowledge of the microcosm of the atomic nucleus. It attempts to find as many nuclear physics imprints as possible in the macrocosm, and to decipher what those messages are telling us about the varied constituent objects in the Universe at present and in the past. In the last decades much advance has been made in nuclear astrophysics thanks to the sometimes spectacular progress made in the modelling of the structure and evolution of the stars, in the quality and diversity of the astronomical observations, as well as in the experimental and theoretical understanding of the atomic nucleus and of its spontaneous or induced transformations. Developments in other subfields of physics and chemistry have also contributed to that advance. Notwithstanding the accomplishment, many long-standing problems remain to be solved, and the theoretical understanding of a large variety of observational facts needs to be put on safer grounds. In addition, new questions are continuously emerging, and new facts endangering old ideas. This review shows that astrophysics has been, and still is, highly demanding to nuclear physics in both its experimental and theoretical components. On top of the fact that large varieties of nuclei have to be dealt with, these nuclei are immersed in highly unusual environments which may have a significant impact on their static properties, the diversity of their transmutation modes, and on the probabilities of these modes. In order to have a chance of solving some of the problems nuclear astrophysics is facing, the astrophysicists and nuclear physicists are obviously bound to put their competence in common, and have sometimes to benefit from the help of other fields of physics, like particle physics, plasma physics or solid-state physics. Given the highly varied and complex aspects, we pick here some specific nuclear

  10. Nuclear telemedicine

    NASA Astrophysics Data System (ADS)

    Morrison, R. T.; Szasz, I. J.

    1990-06-01

    Diagnostic nuclear medicine patient images have been transniitted for 8 years from a regional conununity hospital to a university teaching hospital 700 kiloinetres away employing slow scan TV and telephone. Transruission and interpretation were done at the end of each working day or as circumstances required in cases of emergencies. Referring physicians received the nuclear medicine procedure report at the end of the completion day or within few minutes of completion in case of emergency procedures. To date more than 25 patient studies have been transmitted for interpretation. Blinded reinterpretation of the original hard copy data of 350 patient studies resulted in 100 agreement with the interpretation of transmitted data. This technique provides high quality diagnostic and therapeutic nuclear medicine services in remote hospitals where the services of an on-site nuclear physician is not available. 2. HISTORY Eight years ago when the nuclear medicine physician at Trail Regional Hospital left the Trail area and an other could not be recruited we examined the feasibility of image transmission by phone for interpretation since closing the department would have imposed unacceptable physical and financial hardship and medical constraints on the patient population the nearest nuclear medicine facility was at some 8 hours drive away. In hospital patients would have to be treated either based purely on physical findings or flown to Vancouver at considerable cost to the health care system (estimated cost $1500.

  11. Above-ground Antineutrino Detection for Nuclear Reactor Monitoring

    DOE PAGES

    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

  12. 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.

  13. Quantum defects and specific-isotopic-shift measurements in ns and np highly excited states of lithium: Exchange effects between Rydberg and core electrons

    SciTech Connect

    Goy, P.; Liang, J.; Gross, M.; Haroche, S.

    1986-10-01

    By high-resolution double-resonance spectroscopy experiments in the millimeter-wavelength domain, we have determined precise values of the quantum defects in the s and p Rydberg levels of /sup 6/Li and /sup 7/Li (principal quantum number n ranging from 18 to 40). A detailed comparison of the /sup 6/Li and /sup 7/Li data has yielded the value of the specific isotopic shift in the np series, which is the first evidence to our knowledge of an exchange effect between a tightly bound core electron and a very weakly bound Rydberg electron in an alkali-metal atom.

  14. Nuclear waste

    SciTech Connect

    Not Available

    1988-05-01

    This paper discusses how, as part of the Department of Energy's implementation of the Nuclear Waste Policy Act of 1982, DOE is required to investigate a site at Yucca Mountain, Nevada and, if it determines that the site is suitable, recommend to the President its selection for a nuclear waste repository. The Nuclear Regulatory Commission, in considering development of the plan, issued five objections, one of which is DOE's failure to recognize the range of alternative conceptual models of the Yucca Mountain site that can be supported by the limited existing technical data. At the end of the quarter DOE directed its project offices in Washington and Texas to begin orderly phase-out of all site-specific repository activities. Costs for this phase-out are $53 million for the Deaf Smith site and $85 million for the Hanford site.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Applied nuclear data research and development. Progress report, January 1-March 31, 1981

    SciTech Connect

    Baxman, C.I.; Young, P.G.

    1981-07-01

    Activities of the Los Alamos Nuclear Data Group for January 1 through March 31, 1981, are described. Topics include: (1) peripheral effects in R-matrix theory; (2) Coulomb corrections in light nuclei; (3) new R-matrix analysis of reactions in the /sup 7/Li system; (4) variance-covariance analysis of n + Li reactions; (5) calculated charged-particle emission in the mass-90 region; (6) determination of deformed optical model parameters for neutron reactions on /sup 235/U and /sup 239/Pu; (7) calculation of excited state cross sections for actinide nuclei; (8) calculation of the prompt neutron spectrum and ..nu../sub p/ for the spontaneous fission of /sup 252/Cf; (9) international nuclear model codes comparison study; (10) an improved calculation of heating and radiation damage from neutron capture; (11) LMFBR cross-section production with MAX; (12) TRANSX development; (13) THOR calculations; (14) covariance processing; (15) analysis of charges for use of central computing facility; (16) S/sub n/ calculations for D/sub 2/O sphere; (17) integral data testing of ENDF/B fission-product data; (18) decay power comparisons using ENDF/B-IV and -V data in CINDER-10; (19) ENDF/B-V data testing and summary data; (20) SPEC5: code to produce multigroup spectra; and (21) calculation of H. B. Robinson-2 fuel isotopics and comparison with measurements. (WHK)

  1. Nonthermal nuclear reactions induced by fast α particles in the solar core

    NASA Astrophysics Data System (ADS)

    Voronchev, Victor T.

    2015-02-01

    Nonthermal nuclear effects triggered in the solar carbon-nitrogen-oxygen (CNO) cycle by fast α particles—products of the p p chain reactions—are examined. The main attention is paid to 8.674-MeV α particles generated in the 7Li(p ,α ) α reaction. Nonthermal characteristics of these α particles and their influence on some nuclear processes are determined. It is found that the α -particle effective temperature is at a level of 1.1 MeV and exceeds the solar core temperature by 3 orders of magnitude. These fast particles are able to significantly enhance some endoergic (α ,p ) reactions neglected in standard solar model calculations. In particular, they can substantially affect the balance of the p +17O⇄α +14N reactions due to an appreciable increase of the reverse reaction rate. It is shown that in the region R =0.08 -0.25 R⊙ the reverse α +14N reaction can block the forward p +17O reaction, thus preventing closing of the CNO-II cycle, and increase the 17O abundance by a factor of 2-155 depending on R . This indicates that the fast α particles produced in the p p cycle can distort running of the CNO cycle, making it essentially different in the inner and outer core regions.

  2. 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.

  3. 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).

  4. NUCLEAR REACTOR

    DOEpatents

    Treshow, M.

    1961-09-01

    A boiling-water nuclear reactor is described wherein control is effected by varying the moderator-to-fuel ratio in the reactor core. This is accomplished by providing control tubes containing a liquid control moderator in the reactor core and providing means for varying the amount of control moderatcr within the control tubes.

  5. 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…

  6. 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)

  7. Nuclear explosions

    SciTech Connect

    Broyles, A.A.

    1982-07-01

    A summary of the physics of a nuclear bomb explosion and its effects on human beings is presented at the level of a sophomore general physics course without calculus. It is designed to supplement a standard text for such a course and problems are included.

  8. 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.

  9. 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.

  10. Nuclear politics

    NASA Astrophysics Data System (ADS)

    Ranson, John

    2009-04-01

    The sentiments expressed by Sidney Drell in his forum article "The nuclear threat: a new start" (February pp16-17) are laudable, but it was disappointing to find this almost entirely political story in isolation. The article, which outlined the prospects for reducing weapons stockpiles under the new US administration, would have been more pertinent as an introduction to a series describing the technology used in detecting nuclear-testing activity. It would have been interesting to discuss the specific equipment and methods used, together with the analysis and correlation techniques - along with an indication of how sensitive and reliable they are (if the information is not classified). It is far easier to detect an explosive event than it is to detect and quantify weapons stores, which is a key factor for any negotiated solution. Apart from deductions based on actual inspection and satellite surveillance, are there other techniques that can be applied to this issue?

  11. 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.

  12. 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)

  13. Nuclear Chirality

    SciTech Connect

    Starosta, Krzysztof

    2005-04-05

    Nuclear chirality is a novel manifestation of spontaneous symmetry breaking resulting from an orthogonal coupling of angular momentum vectors in triaxial nuclei. Three perpendicular angular momenta can form two systems of opposite handedness; the time reversal operator, which reverses orientation of each of the angular momentum components, relates these two systems. The status of current experimental searches for chiral doubling of states, as well as recent progress on the theoretical side is reviewed.

  14. 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.

  15. Nuclear terrorism.

    PubMed

    Hogan, David E; Kellison, Ted

    2002-06-01

    Recent events have heightened awareness of the potential for terrorist attacks employing nonconventional weaponry such as biological agents and radiation. Historically, the philosophy of nuclear risk has focused on global or strategic nuclear exchanges and the resulting damage from large-scale releases. Currently, nuclear accidents or terrorist attacks involving low-level or regional release of radiation are considered the most likely events. Thus far, there have been several regional radiation incidents exposing hundreds of thousands of people to radiation, but there have been only a limited number of significant contaminations resulting in death. There are several different types of radioactive particles that differ in mass, extent of radiation emitted, and the degree to which tissue penetration occurs. Radiation affects its toxicity on biological systems by ionization, which creates tissue damage by the generation of free radicals, disruption of chemical bonds, and directly damaging cellular DNA and enzymes. The extent of damage depends on the type of radioisotope and the radiation dose. Radiation doses exceeding 2 to 10 Gy are considered lethal. Optimal management of radiation casualties requires knowledge of the type and dose of radiation received, a recognition of the manifestations of radiation sickness, and the use of standard medical care, decontamination, and decorporation techniques. PMID:12074488

  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 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

  18. Nuclear photonics

    NASA Astrophysics Data System (ADS)

    Habs, D.; Günther, M. M.; Jentschel, M.; Thirolf, P. G.

    2012-07-01

    With the planned new γ-beam facilities like MEGa-ray at LLNL (USA) or ELI-NP at Bucharest (Romania) with 1013 γ/s and a band width of ΔEγ/Eγ≈10-3, a new era of γ beams with energies up to 20MeV comes into operation, compared to the present world-leading HIγS facility at Duke University (USA) with 108 γ/s and ΔEγ/Eγ≈3ṡ10-2. In the long run even a seeded quantum FEL for γ beams may become possible, with much higher brilliance and spectral flux. At the same time new exciting possibilities open up for focused γ beams. Here we describe a new experiment at the γ beam of the ILL reactor (Grenoble, France), where we observed for the first time that the index of refraction for γ beams is determined by virtual pair creation. Using a combination of refractive and reflective optics, efficient monochromators for γ beams are being developed. Thus, we have to optimize the total system: the γ-beam facility, the γ-beam optics and γ detectors. We can trade γ intensity for band width, going down to ΔEγ/Eγ≈10-6 and address individual nuclear levels. The term "nuclear photonics" stresses the importance of nuclear applications. We can address with γ-beams individual nuclear isotopes and not just elements like with X-ray beams. Compared to X rays, γ 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 μm 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 applications. We find many new applications in biomedicine, green energy, radioactive waste management or homeland security. Also more brilliant secondary beams of neutrons and positrons can be produced.

  19. 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)

  20. The nuclear arsenals and nuclear disarmament.

    PubMed

    Barnaby, F

    1998-01-01

    Current world stockpiles of nuclear weapons and the status of treaties for nuclear disarmament and the ultimate elimination of nuclear weapons are summarised. The need for including stockpiles of civil plutonium in a programme for ending production and disposing of fissile materials is emphasized, and the ultimate difficulty of disposing of the last few nuclear weapons discussed.

  1. The Nuclear Power/Nuclear Weapons Connection.

    ERIC Educational Resources Information Center

    Totten, Sam; Totten, Martha Wescoat

    1985-01-01

    Once they have nuclear power, most countries will divert nuclear materials from commercial to military programs. In excerpts from the book "Facing the Danger" (by Totten, S. and M. W., Crossing Press, 1984), five anti-nuclear activists explain how and why they have been addressing the nuclear connection. (RM)

  2. Nuclear security

    SciTech Connect

    Dingell, J.D.

    1991-02-01

    The Department of Energy's (DOE) Lawrence Livermore National Laboratory, located in Livermore, California, generates and controls large numbers of classified documents associated with the research and testing of nuclear weapons. Concern has been raised about the potential for espionage at the laboratory and the national security implications of classified documents being stolen. This paper determines the extent of missing classified documents at the laboratory and assesses the adequacy of accountability over classified documents in the laboratory's custody. Audit coverage was limited to the approximately 600,000 secret documents in the laboratory's custody. The adequacy of DOE's oversight of the laboratory's secret document control program was also assessed.

  3. NUCLEAR REACTOR

    DOEpatents

    Young, G.

    1963-01-01

    This patent covers a power-producing nuclear reactor in which fuel rods of slightly enriched U are moderated by heavy water and cooled by liquid metal. The fuel rods arranged parallel to one another in a circle are contained in a large outer closed-end conduit that extends into a tank containing the heavy water. Liquid metal is introduced into the large conduit by a small inner conduit that extends within the circle of fuel rods to a point near the lower closed end of the outer conduit. (AEC) Production Reactors

  4. Nuclear energy.

    PubMed

    Grandin, Karl; Jagers, Peter; Kullander, Sven

    2010-01-01

    Nuclear energy can play a role in carbon free production of electrical energy, thus making it interesting for tomorrow's energy mix. However, several issues have to be addressed. In fission technology, the design of so-called fourth generation reactors show great promise, in particular in addressing materials efficiency and safety issues. If successfully developed, such reactors may have an important and sustainable part in future energy production. Working fusion reactors may be even more materials efficient and environmental friendly, but also need more development and research. The roadmap for development of fourth generation fission and fusion reactors, therefore, asks for attention and research in these fields must be strengthened.

  5. Nuclear energy.

    PubMed

    Grandin, Karl; Jagers, Peter; Kullander, Sven

    2010-01-01

    Nuclear energy can play a role in carbon free production of electrical energy, thus making it interesting for tomorrow's energy mix. However, several issues have to be addressed. In fission technology, the design of so-called fourth generation reactors show great promise, in particular in addressing materials efficiency and safety issues. If successfully developed, such reactors may have an important and sustainable part in future energy production. Working fusion reactors may be even more materials efficient and environmental friendly, but also need more development and research. The roadmap for development of fourth generation fission and fusion reactors, therefore, asks for attention and research in these fields must be strengthened. PMID:20873683

  6. NUCLEAR REACTORS

    DOEpatents

    Long, E.; Ashley, J.W.

    1958-12-16

    A graphite moderator structure is described for a gas-cooled nuclear reactor having a vertical orlentation wherein the structure is physically stable with regard to dlmensional changes due to Wigner growth properties of the graphite, and leakage of coolant gas along spaces in the structure is reduced. The structure is comprised of stacks of unlform right prismatic graphite blocks positioned in layers extending in the direction of the lengths of the blocks, the adjacent end faces of the blocks being separated by pairs of tiles. The blocks and tiles have central bores which are in alignment when assembled and are provided with cooperatlng keys and keyways for physical stability.

  7. 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.

  8. Dictionary of nuclear engineering

    SciTech Connect

    Sube, R.

    1985-01-01

    Ralf Sube, an experienced compiler of three wellknown four-language reference works has now prepared this glossary of nuclear engineering terms in English, German, French and Russian. Based on the proven lexicography of the Technik-Worterbuch series, it comprises about 30,000 terms in each language covering the following: Nuclear and Atomic Physics; Nuclear Radiation and Isotopes; Nuclear Materials; Nuclear Facilties; Nuclear Power Industry; Nuclear Weapons.

  9. 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.

  10. Nuclear "waffles"

    NASA Astrophysics Data System (ADS)

    Schneider, A. S.; Berry, D. K.; Briggs, C. M.; Caplan, M. E.; Horowitz, C. J.

    2014-11-01

    Background: The dense neutron-rich matter found in supernovae and inside neutron stars is expected to form complex nonuniform phases, often referred to as nuclear pasta. The pasta shapes depend on density, temperature and proton fraction and determine many transport properties in supernovae and neutron star crusts. Purpose: To characterize the topology and compute two observables, the radial distribution function (RDF) g (r ) and the structure factor S (q ) , for systems with proton fractions Yp=0.10 ,0.20 ,0.30 , and 0.40 at about one-third of nuclear saturation density, n =0.050 fm-3 , and temperatures near k T =1 MeV . Methods: We use two recently developed hybrid CPU/GPU codes to perform large scale molecular dynamics (MD) simulations with 51 200 and 409 600 nucleons. From the output of the MD simulations we obtain the two desired observables. Results: We compute and discuss the differences in topology and observables for each simulation. We observe that the two lowest proton fraction systems simulated, Yp=0.10 and 0.20 , equilibrate quickly and form liquidlike structures. Meanwhile, the two higher proton fraction systems, Yp=0.30 and 0.40 , take a longer time to equilibrate and organize themselves in solidlike periodic structures. Furthermore, the Yp=0.40 system is made up of slabs, lasagna phase, interconnected by defects while the Yp=0.30 systems consist of a stack of perforated plates, the nuclear waffle phase. Conclusions: The periodic configurations observed in our MD simulations for proton fractions Yp≥0.30 have important consequences for the structure factors S (q ) of protons and neutrons, which relate to many transport properties of supernovae and neutron star crust. A detailed study of the waffle phase and how its structure depends on temperature, size of the simulation, and the screening length showed that finite-size effects appear to be under control and, also, that the plates in the waffle phase merge at temperatures slightly above 1.0 MeV and

  11. Diode laser absorption spectroscopy of lithium isotopes

    NASA Astrophysics Data System (ADS)

    Olivares, Ignacio E.; González, Iván A.

    2016-10-01

    We study Doppler-limited laser intensity absorption, in a thermal lithium vapor containing 7Li and 6Li atoms in a 9 to 1 ratio, using a narrow-linewidth single-longitudinal-mode tunable external cavity diode laser at the wavelength of 670.8 nm. The lithium vapor was embedded in helium or argon buffer gas. The spectral lineshapes were rigorously predicted for D_1 and D_2 for the lithium 6 and 7 isotope lines using reduced optical Bloch equations, specifically derived, from a density matrix analysis. Here, a detailed comparison is provided of the predicted lineshapes with the measured 7Li-D_2, 7Li-D_1, 6Li-D_2 and 6Li-D_1 lines, in the case of high vapor density and with intensity above the saturation intensity. To our knowledge, this is the first time that such detailed comparison is reported in the open literature. The calculations were also extended to saturated absorption spectra and compared to measured Doppler-free 7Li-D_2 and 6Li-D_2 hyperfine lines.

  12. Nuclear Fusion

    NASA Astrophysics Data System (ADS)

    Veres, G.

    This chapter is devoted to the fundamental concepts of nuclear fusion. To be more precise, it is devoted to the theoretical basics of fusion reactions between light nuclei such as hydrogen, helium, boron, and lithium. The discussion is limited because our purpose is to focus on laboratory-scale fusion experiments that aim at gaining energy from the fusion process. After discussing the methods of calculating the fusion cross section, it will be shown that sustained fusion reactions with energy gain must happen in a thermal medium because, in beam-target experiments, the energy of the beam is randomized faster than the fusion rate. Following a brief introduction to the elements of plasma physics, the chapter is concluded with the introduction of the most prominent fusion reactions ongoing in the Sun.

  13. NUCLEAR REACTOR

    DOEpatents

    Grebe, J.J.

    1959-12-15

    A reactor which is particularly adapted tu serve as a heat source for a nuclear powered alrcraft or rocket is described. The core of this reactor consists of a porous refractory modera;or body which is impregnated with fissionable nuclei. The core is designed so that its surface forms tapered inlet and outlet ducts which are separated by the porous moderator body. In operation a gaseous working fluid is circulated through the inlet ducts to the surface of the moderator, enters and passes through the porous body, and is heated therein. The hot gas emerges into the outlet ducts and is available to provide thrust. The principle advantage is that tremendous quantities of gas can be quickly heated without suffering an excessive pressure drop.

  14. NUCLEAR REACTOR

    DOEpatents

    Christy, R.F.

    1958-07-15

    A nuclear reactor of the homogeneous liquid fuel type is described wherein the fissionable isotope is suspended or dissolved in a liquid moderator such as water. The reactor core is comprised essentially of a spherical vessel for containing the reactive composition surrounded by a reflector, preferably of beryllium oxide. The reactive composition may be an ordinary water solution of a soluble salt of uranium, the quantity of fissionable isotope in solution being sufficient to provide a critical mass in the vessel. The liquid fuel is stored in a tank of non-crtttcal geometry below the reactor vessel and outside of the reflector and is passed from the tank to the vessel through a pipe connecting the two by air pressure means. Neutron absorbing control and safety rods are operated within slots in the reflector adjacent to the vessel.

  15. NUCLEAR REACTOR

    DOEpatents

    Miller, H.I.; Smith, R.C.

    1958-01-21

    This patent relates to nuclear reactors of the type which use a liquid fuel, such as a solution of uranyl sulfate in ordinary water which acts as the moderator. The reactor is comprised of a spherical vessel having a diameter of about 12 inches substantially surrounded by a reflector of beryllium oxide. Conventionnl control rods and safety rods are operated in slots in the reflector outside the vessel to control the operation of the reactor. An additional means for increasing the safety factor of the reactor by raising the ratio of delayed neutrons to prompt neutrons, is provided and consists of a soluble sulfate salt of beryllium dissolved in the liquid fuel in the proper proportion to obtain the result desired.

  16. Nuclear reactor

    DOEpatents

    Wade, Elman E.

    1979-01-01

    A nuclear reactor including two rotatable plugs and a positive top core holddown structure. The top core holddown structure is divided into two parts: a small core cover, and a large core cover. The small core cover, and the upper internals associated therewith, are attached to the small rotating plug, and the large core cover, with its associated upper internals, is attached to the large rotating plug. By so splitting the core holddown structures, under-the-plug refueling is accomplished without the necessity of enlarging the reactor pressure vessel to provide a storage space for the core holddown structure during refueling. Additionally, the small and large rotating plugs, and their associated core covers, are arranged such that the separation of the two core covers to permit rotation is accomplished without the installation of complex lifting mechanisms.

  17. Nuclear exoticism

    NASA Astrophysics Data System (ADS)

    Penionzhkevich, Yu. E.

    2016-07-01

    Extreme states of nuclearmatter (such that feature high spins, large deformations, high density and temperature, or a large excess of neutrons and protons) play an important role in studying fundamental properties of nuclei and are helpful in solving the problem of constructing the equation of state for nuclear matter. The synthesis of neutron-rich nuclei near the nucleon drip lines and investigation of their properties permit drawing conclusions about the positions of these boundaries and deducing information about unusual states of such nuclei and about their decays. At the present time, experimental investigations along these lines can only be performed via the cooperation of leading research centers that possess powerful heavy-ion accelerators, such as the Large Hadron Collider (LHC) at CERN and the heavy-ion cyclotrons at the Joint Institute for Nuclear Research (JINR, Dubna), where respective experiments are being conducted by physicists from about 20 JINR member countries. The present article gives a survey of the most recent results in the realms of super neutron-rich nuclei. Implications of the change in the structure of such nuclei near the nucleon drip lines are discussed. Information about the results obtained by measuring the masses (binding energies) of exotic nuclei, the nucleon-distribution radii (neutron halo) and momentum distributions in them, and their deformations and quantum properties is presented. It is shown that the properties of nuclei lying near the stability boundaries differ strongly from the properties of other nuclei. The problem of the stability of nuclei that is associated with the magic numbers of 20 and 28 is discussed along with the effect of new magic numbers.

  18. 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.

  19. 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

  20. 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

  1. 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).

  2. Nuclear war: Opposing viewpoints

    SciTech Connect

    Szumski, B.

    1985-01-01

    This book presents opposing viewpoints on nuclear war. Topics discussed include: how nuclear would begin; would humanity survive; would civil defense work; will an arms agreement work; and can space weapons reduce the risk of nuclear war.

  3. Nuclear analytical chemistry

    SciTech Connect

    Brune, D.; Forkman, B.; Persson, B.

    1984-01-01

    This book covers the general theories and techniques of nuclear chemical analysis, directed at applications in analytical chemistry, nuclear medicine, radiophysics, agriculture, environmental sciences, geological exploration, industrial process control, etc. The main principles of nuclear physics and nuclear detection on which the analysis is based are briefly outlined. An attempt is made to emphasise the fundamentals of activation analysis, detection and activation methods, as well as their applications. The book provides guidance in analytical chemistry, agriculture, environmental and biomedical sciences, etc. The contents include: the nuclear periodic system; nuclear decay; nuclear reactions; nuclear radiation sources; interaction of radiation with matter; principles of radiation detectors; nuclear electronics; statistical methods and spectral analysis; methods of radiation detection; neutron activation analysis; charged particle activation analysis; photon activation analysis; sample preparation and chemical separation; nuclear chemical analysis in biological and medical research; the use of nuclear chemical analysis in the field of criminology; nuclear chemical analysis in environmental sciences, geology and mineral exploration; and radiation protection.

  4. Nuclear Quadrupole Moments and Nuclear Shell Structure

    DOE R&D Accomplishments Database

    Townes, C. H.; Foley, H. M.; Low, W.

    1950-06-23

    Describes a simple model, based on nuclear shell considerations, which leads to the proper behavior of known nuclear quadrupole moments, although predictions of the magnitudes of some quadrupole moments are seriously in error.

  5. Nuclear thermal/nuclear electric hybrids

    NASA Technical Reports Server (NTRS)

    Reid, B. D.

    1991-01-01

    A description is given of the nuclear thermal and nuclear electric hybrid. The specifications are described along with its mission performance. Next, the technical status, development requirements, and some cost estimates are provided.

  6. Nuclear Fuel Cycle & Vulnerabilities

    SciTech Connect

    Boyer, Brian D.

    2012-06-18

    The objective of safeguards is the timely detection of diversion of significant quantities of nuclear material from peaceful nuclear activities to the manufacture of nuclear weapons or of other nuclear explosive devices or for purposes unknown, and deterrence of such diversion by the risk of early detection. The safeguards system should be designed to provide credible assurances that there has been no diversion of declared nuclear material and no undeclared nuclear material and activities.

  7. Nuclear weapons modernizations

    NASA Astrophysics Data System (ADS)

    Kristensen, Hans M.

    2014-05-01

    This article reviews the nuclear weapons modernization programs underway in the world's nine nuclear weapons states. It concludes that despite significant reductions in overall weapons inventories since the end of the Cold War, the pace of reductions is slowing - four of the nuclear weapons states are even increasing their arsenals, and all the nuclear weapons states are busy modernizing their remaining arsenals in what appears to be a dynamic and counterproductive nuclear competition. The author questions whether perpetual modernization combined with no specific plan for the elimination of nuclear weapons is consistent with the nuclear Non-Proliferation Treaty and concludes that new limits on nuclear modernizations are needed.

  8. Nuclear weapons modernizations

    SciTech Connect

    Kristensen, Hans M.

    2014-05-09

    This article reviews the nuclear weapons modernization programs underway in the world's nine nuclear weapons states. It concludes that despite significant reductions in overall weapons inventories since the end of the Cold War, the pace of reductions is slowing - four of the nuclear weapons states are even increasing their arsenals, and all the nuclear weapons states are busy modernizing their remaining arsenals in what appears to be a dynamic and counterproductive nuclear competition. The author questions whether perpetual modernization combined with no specific plan for the elimination of nuclear weapons is consistent with the nuclear Non-Proliferation Treaty and concludes that new limits on nuclear modernizations are needed.

  9. Nuclear target development

    SciTech Connect

    Greene, J.P.; Thomas, G.E.

    1995-08-01

    The Physics Division operates a target development laboratory that produces thin foil targets needed for experiments performed at the ATLAS and Dynamitron accelerators. Targets are not only produced for the Physics Division but also for other divisions and occasionally for other laboratories and universities. In the past year, numerous targets were fabricated by vacuum evaporation either as self-supporting foils or on various substrates. Targets produced included Ag, Au, {sup 10,11}B, {sup 138}Ba, Be, {sup 12}C, {sup 40}Ca, {sup 116}Cd, {sup 155,160}Gd, {sup 76}Ge, In, LID, {sup 6}LiH, Melamine, Mg, {sup 142,150}Nd, {sup 58}Ni, {sup 206,208}Pb, {sup 194}Pt, {sup 28}Si, {sup 144,148}Sm, {sup 120,122,124}Sn, Ta, {sup 130}Te, ThF{sub 4}, {sup 46,50}Ti, TiH, U, UF{sub 4}, {sup 182}W and {sup 170}Yb. Polypropylene and aluminized polypropylene, along with metallized Mylar were produced for experiments at ATLAS. A number of targets of {sup 11}B of various thickness were made for the DEP 2-MeV Van de Graff accelerator. An increased output of foils fabricated using our small rolling mill included targets of Au, C, {sup 50}Cr, Cu, {sup 155,160}Gd, Mg, {sup 58}Ni, {sup 208}Pb, {sup 105,110}Pd. Sc, Ti, and {sup 64,66}Zn.

  10. Nuclear reactor

    DOEpatents

    Thomson, Wallace B.

    2004-03-16

    A nuclear reactor comprising a cylindrical pressure vessel, an elongated annular core centrally disposed within and spaced from the pressure vessel, and a plurality of ducts disposed longitudinally of the pressure vessel about the periphery thereof, said core comprising an annular active portion, an annular reflector just inside the active portion, and an annular reflector just outside the active a portion, said annular active portion comprising rectangular slab, porous fuel elements radially disposed around the inner reflector and extending the length of the active portion, wedge-shaped, porous moderator elements disposed adjacent one face of each fuel element and extending the length of the fuel element, the fuel and moderator elements being oriented so that the fuel elements face each other and the moderator elements do likewise, adjacent moderator elements being spaced to provide air inlet channels, and adjacent fuel elements being spaced to provide air outlet channels which communicate with the interior of the peripheral ducts, and means for introducing air into the air inlet channels which passes through the porous moderator elements and porous fuel elements to the outlet channel.

  11. The Arabidopsis Nuclear Pore and Nuclear Envelope

    PubMed Central

    Meier, Iris; Brkljacic, Jelena

    2010-01-01

    The nuclear envelope is a double membrane structure that separates the eukaryotic cytoplasm from the nucleoplasm. The nuclear pores embedded in the nuclear envelope are the sole gateways for macromolecular trafficking in and out of the nucleus. The nuclear pore complexes assembled at the nuclear pores are large protein conglomerates composed of multiple units of about 30 different nucleoporins. Proteins and RNAs traffic through the nuclear pore complexes, enabled by the interacting activities of nuclear transport receptors, nucleoporins, and elements of the Ran GTPase cycle. In addition to directional and possibly selective protein and RNA nuclear import and export, the nuclear pore gains increasing prominence as a spatial organizer of cellular processes, such as sumoylation and desumoylation. Individual nucleoporins and whole nuclear pore subcomplexes traffic to specific mitotic locations and have mitotic functions, for example at the kinetochores, in spindle assembly, and in conjunction with the checkpoints. Mutants of nucleoporin genes and genes of nuclear transport components lead to a wide array of defects from human diseases to compromised plant defense responses. The nuclear envelope acts as a repository of calcium, and its inner membrane is populated by functionally unique proteins connected to both chromatin and—through the nuclear envelope lumen—the cytoplasmic cytoskeleton. Plant nuclear pore and nuclear envelope research—predominantly focusing on Arabidopsis as a model—is discovering both similarities and surprisingly unique aspects compared to the more mature model systems. This chapter gives an overview of our current knowledge in the field and of exciting areas awaiting further exploration. PMID:22303264

  12. Nuclear reactor

    DOEpatents

    Pennell, William E.; Rowan, William J.

    1977-01-01

    A nuclear reactor in which the core components, including fuel-rod assemblies, control-rod assemblies, fertile rod-assemblies, and removable shielding assemblies, are supported by a plurality of separate inlet modular units. These units are referred to as inlet module units to distinguish them from the modules of the upper internals of the reactor. The modular units are supported, each removable independently of the others, in liners in the supporting structure for the lower internals of the reactor. The core assemblies are removably supported in integral receptacles or sockets of the modular units. The liners, units, sockets and assmblies have inlet openings for entry of the fluid. The modular units are each removably mounted in the liners with fluid seals interposed between the opening in the liner and inlet module into which the fluid enters and the upper and lower portion of the liner. Each assembly is similarly mounted in a corresponding receptacle with fluid seals interposed between the openings where the fluid enters and the lower portion of the receptacle or fitting closely in these regions. As fluid flows along each core assembly a pressure drop is produced along the fluid so that the fluid which emerges from each core assembly is at a lower pressure than the fluid which enters the core assembly. However because of the seals interposed in the mountings of the units and assemblies the pressures above and below the units and assemblies are balanced and the units are held in the liners and the assemblies are held in the receptacles by their weights as they have a higher specific gravity than the fluid. The low-pressure spaces between each module and its liner and between each core assembly and its module is vented to the low-pressure regions of the vessel to assure that fluid which leaks through the seals does not accumulate and destroy the hydraulic balance.

  13. Nuclear reactor

    DOEpatents

    Yant, Howard W.; Stinebiser, Karl W.; Anzur, Gregory C.

    1977-01-01

    A nuclear reactor, particularly a liquid-metal breeder reactor, whose upper internals include outlet modules for channeling the liquid-metal coolant from selected areas of the outlet of the core vertically to the outlet plenum. The modules are composed of a highly-refractory, high corrosion-resistant alloy, for example, INCONEL-718. Each module is disposed to confine and channel generally vertically the coolant emitted from a subplurality of core-component assemblies. Each module has a grid with openings, each opening disposed to receive the coolant from an assembly of the subplurality. The grid in addition serves as a holdown for the assemblies of the corresponding subplurality preventing their excessive ejection upwardly from the core. In the region directly over the core the outlet modules are of such peripheral form that they nest forming a continuum over the core-component assemblies whose outlet coolant they confine. Each subassembly includes a chimney which confines the coolant emitted by its corresponding subassemblies to generally vertical flow between the outlet of the core and the outlet plenum. Each subplurality of assemblies whose emitted coolant is confined by an outlet module includes assemblies which emit lower-temperature coolant, for example, a control-rod assembly, or fertile assemblies, and assemblies which emit coolant of substantially higher temperature, for example, fuel-rod assemblies. The coolants of different temperatures are mixed in the chimneys reducing the effect of stripping (hot-cold temperature fluctuations) on the remainder of the upper internals which are composed typically of AISI-304 or AISI-316 stainless steel.

  14. Applications of two-dimensional solid state nuclear magnetic resonance in silicates

    NASA Astrophysics Data System (ADS)

    Xu, Zhi

    1998-10-01

    Nuclear magnetic resonance (NMR) is a powerful technique and has been routinely applied in many fields. In this study, we have used high resolution two-dimensional (2D) solid state NMR techniques to study the dynamic process of Li diffusion, the kinetic process of oxygen isotope exchange, and the structural characterization of hydrous and anhydrous silicate glasses at atomic level. In the Li diffusion study, we first established the correlation between the sp6Li chemical shifts and the lithium coordination environments in lithium containing silicates. Then, we assigned the sp6Li magic angle spinning (MAS) spectrum and applied 1D, 2D variable temperature exchange NMR to observe Lisp+ diffusion in lithium orthosilicate. For the first time, our result revealed a detailed picture of the hopping rates of Lisp+ ions among structurally distinct sites and helped to define the diffusion pathway. We have shown that Lisp+ ions hopping rates and activation energies depend on site geometry. NMR measurements on Li ionic hopping frequencies was used to accurately predict the bulk conductivity. In the site-specific oxygen isotope exchange study, we first developed a method to obtain quantitative sp{17}O NMR spectra. Then, we applied the method to stilbite, a natural zeolite. We have shown for the first time that framework oxygens in Al-O-Si sites react faster with oxygens in the channel water than oxygens in Si-O-Si sites. Such an observation has partially proved the quantum ab initio calculation on water adsorption onto silicates. Our measured kinetics results agreed well with bulk isotopic measurements. Water dissolution mechanism in silicates glasses, especially aluminosilicate glasses, has been a long-standing controversy. We have used the sp{17}O spectra for hydrous and anhydrous sodium tetrasilicate glasses and albite glasses to study the structural role of hydrogen-containing species. For the first time, we have observed the oxygen peak for SiOH in hydrous sodium

  15. The New Nuclear Nations.

    ERIC Educational Resources Information Center

    Spector, Leonard S.

    1990-01-01

    Explores the issue of nuclear proliferation, noting that the countries with nuclear capability now include Israel, South Africa, India, and Pakistan. Describes the role and problems of the United States in halting nuclearization. Supplies charts, maps, and information concerning the state of nuclear capability in each country. (NL)

  16. Nuclear medicine annual, 1984

    SciTech Connect

    Freeman, L.M.; Weissmann, H.S.

    1984-01-01

    The following topics are reviewed in this work: nuclear physicians role in planning for and handling radiation accidents; the role of nuclear medicine in evaluating the hypertensive patient; studies of the heart with radionuclides; role of radionuclide imaging in the patient undergoing chemotherapy; hematologic nuclear medicine; the role of nuclear medicine in sports related injuries; radionuclide evaluation of hepatic function with emphasis on cholestatis.

  17. Terrorists and Nuclear Technology

    ERIC Educational Resources Information Center

    Krieger, David

    1975-01-01

    This essay explores the ways terrorist groups may gain possession of nuclear materials; the way in which they may use nuclear weapons and other nuclear technologies to their benefit; and various courses of action designed to minimize the possibilities of terrorists utilizing nuclear technology to their benefit and society's detriment. (BT)

  18. Nuclear Reaction Data Centers

    SciTech Connect

    McLane, V.; Nordborg, C.; Lemmel, H.D.; Manokhin, V.N.

    1988-01-01

    The cooperating Nuclear Reaction Data Centers are involved in the compilation and exchange of nuclear reaction data for incident neutrons, charged particles and photons. Individual centers may also have services in other areas, e.g., evaluated data, nuclear structure and decay data, reactor physics, nuclear safety; some of this information may also be exchanged between interested centers. 20 refs., 1 tab.

  19. Nuclear air cushion vehicles

    NASA Technical Reports Server (NTRS)

    Anderson, J. L.

    1973-01-01

    The state-of-the-art of the still-conceptual nuclear air cushion vehicle, particularly the nuclear powerplant is identified. Using mission studies and cost estimates, some of the advantages of nuclear power for large air cushion vehicles are described. The technology studies on mobile nuclear powerplants and conceptual ACV systems/missions studies are summarized.

  20. Frontiers of Nuclear Structure

    SciTech Connect

    Nazarewicz, Witold

    1997-12-31

    Current developments in nuclear structure at the `limits` are discussed. The studies of nuclear behavior at extreme conditions provide us with invaluable information about the nature of the nuclear interaction and nucleonic correlations at various energy-distance scales. In this talk frontiers of nuclear structure are briefly reviewed from a theoretical perspective, mainly concentrating on medium-mass and heavy nuclei.

  1. [Chilean nuclear policy].

    PubMed

    Bobadilla, E

    1996-06-01

    This official document is statement of the President of the Chilean Nuclear Energy Commission, Dr. Eduardo Bobadilla, about the nuclear policy of the Chilean State, Thanks to the international policy adopted by presidents Aylwin (1990-1994) and his successor Frei Ruiz Tagle (1994-), a nuclear development plan, protected by the Chilean entrance to the nuclear weapons non proliferation treaty and Tlatelolco Denuclearization treaty, has started. Chile will be able to develop without interference, an autonomous nuclear electrical system and other pacific uses of nuclear energy. Chile also supports a new international treaty to ban nuclear weapon tests.

  2. 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

  3. Intergenerational issues regarding nuclear power, nuclear waste, and nuclear weapons.

    PubMed

    Ahearne, J F

    2000-12-01

    Nuclear power, nuclear waste, and nuclear weapons raise substantial public concern in many countries. While new support for nuclear power can be found in arguments concerning greenhouse gases and global warming, the long-term existence of radioactive waste has led to requirements for 10,000-year isolation. Some of the support for such requirements is based on intergenerational equity arguments. This, however, places a very high value on lives far in the future. An alternative is to use discounting, as is applied to other resource applications. Nuclear weapons, even though being dismantled by the major nations, are growing in number due to the increase in the number of countries possessing these weapons of mass destruction. This is an unfortunate legacy for future generations. PMID:11314726

  4. Nuclear Structure Aspects in Nuclear Astrophysics

    SciTech Connect

    Smith, Michael Scott

    2006-12-01

    Nuclear Astrophysics as a broad and diverse field of study can be viewed as a magnifier of the impact of microscopic processes on the evolution of macroscopic events. One of the primary goals in Nuclear Astrophysics is the understanding of the nucleosynthesis processes that take place in the cosmos and the simulation of the correlated stellar and explosive burning scenarios. These simulations are strongly dependent on the input from Nuclear Physics which sets the time scale for all stellar dynamic processes--from giga-years of stellar evolution to milliseconds of stellar explosions--and provides the basis for most of the signatures that we have for the interpretation of these events--from stellar luminosities, elemental and isotopic abundances to neutrino flux from distant supernovae. The Nuclear Physics input comes through nuclear structure, low energy reaction rates, nuclear masses, and decay rates. There is a common perception that low energy reaction rates are the most important component of the required nuclear physics input; however, in this article we take a broader approach and present an overview of the close correlation between various nuclear structure aspects and their impact on nuclear astrophysics. We discuss the interplay between the weak and the strong forces on stellar time scales due to the limitations they provide for the evolution of slow and rapid burning processes. The effects of shell structure in nuclei on stellar burning processes as well as the impact of clustering in nuclei is outlined. Furthermore we illustrate the effects of the various nuclear structure aspects on the major nucleosynthesis processes that have been identified in the last few decades. We summarize and provide a coherent overview of the impact of all aspects of nuclear structure on nuclear astrophysics.

  5. 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.

  6. Structure of the polymer electrolyte poly(ethylene oxide)6:LiAsF6

    NASA Astrophysics Data System (ADS)

    Macglashan, Graham S.; Andreev, Yuri G.; Bruce, Peter G.

    1999-04-01

    Polymer electrolytes-salts (such as LiCF3SO3) dissolved in solid, high-molar-mass polymers (for example, poly(ethylene oxide), PEO),,-hold the key to the development of all-solid-state rechargeable lithium batteries. They also represent an unusual class of coordination compounds in the solid state. Conductivities of up to 10-4Scm-1 may be obtained, but higher levels are needed for applications in batteries,,. To achieve such levels requires a better understanding of the conduction mechanism, and crucial to this is a knowledge of polymer-electrolyte structure. Crystalline forms of polymer electrolytes are obtained at only a few discrete compositions. The structures of 3:1 and 4:1 complexes (denoting the ratio of ether oxygens to cations) have been determined,,. But the 6:1 complex is of greater interest as the conductivity of polymer electrolytes increases significantly on raising the polymer content from 3:1 to 6:1 (refs 10, 11). Furthermore, many highly conducting polymer-electrolyte systems form crystalline 6:1 complexes whereas those with lower conductivities do not. Here we report the structure of the PEO:LiAsF6 complex with a 6:1 composition. Determination of the structure was carried out abinitio by employing a method for flexible molecular structures, involving full profile fitting to the X-ray powder diffraction data by simulated annealing. Whereas in the 3:1 complexes the polymer chains form helices, those in the 6:1 complex form double non-helical chains which interlock to form a cylinder. The lithium ions reside inside these cylinders and, in contrast to other complexes, are not coordinated by the anions.

  7. Biogenesis of nuclear bodies.

    PubMed

    Dundr, Miroslav; Misteli, Tom

    2010-12-01

    The nucleus is unique amongst cellular organelles in that it contains a myriad of discrete suborganelles. These nuclear bodies are morphologically and molecularly distinct entities, and they host specific nuclear processes. Although the mode of biogenesis appears to differ widely between individual nuclear bodies, several common design principles are emerging, particularly, the ability of nuclear bodies to form de novo, a role of RNA as a structural element and self-organization as a mode of formation. The controlled biogenesis of nuclear bodies is essential for faithful maintenance of nuclear architecture during the cell cycle and is an important part of cellular responses to intra- and extracellular events.

  8. Nuclear Waste Disposal

    SciTech Connect

    Gee, Glendon W.; Meyer, Philip D.; Ward, Andy L.

    2005-01-12

    Nuclear wastes are by-products of nuclear weapons production and nuclear power generation, plus residuals of radioactive materials used by industry, medicine, agriculture, and academia. Their distinctive nature and potential hazard make nuclear wastes not only the most dangerous waste ever created by mankind, but also one of the most controversial and regulated with respect to disposal. Nuclear waste issues, related to uncertainties in geologic disposal and long-term protection, combined with potential misuse by terrorist groups, have created uneasiness and fear in the general public and remain stumbling blocks for further development of a nuclear industry in a world that may soon be facing a global energy crisis.

  9. Nuclear magnetic resonance investigation of dynamics in poly(ethylene oxide)-based lithium polyether-ester-sulfonate ionomers

    DOE PAGES

    Roach, David J.; Dou, Shichen; Colby, Ralph H.; Mueller, Karl T.

    2012-01-06

    Nuclear magnetic resonance (NMR) spectroscopy has been utilized to investigate the dynamics of poly(ethylene oxide)-based lithium sulfonate ionomer samples that have low glass transition temperatures. 1H and 7Li spin-lattice relaxation times (T1) of the bulk polymer and lithium ions, respectively, were measured and analyzed in samples with a range of ion contents. The temperature dependence of T1 values along with the presence of minima in T1 as a function of temperature enabled correlation times and activation energies to be obtained for both the segmental motion of the polymer backbone and the hopping motion of lithium cations. Similar activation energies formore » motion of both the polymer and lithium ions in the samples with lower ion content indicate that the polymer segmental motion and lithium ion hopping motion are correlated in these samples, even though their respective correlation times differ significantly. A divergent trend is observed for correlation times and activation energies of the highest ion content sample with 100% lithium sulfonation due to the presence of ionic aggregation. Details of the polymer and cation dynamics on the nanosecond timescale are discussed and complement the findings of X-ray scattering and Quasi Elastic Neutron Scattering experiments.« less

  10. Nuclear Security for Floating Nuclear Power Plants

    SciTech Connect

    Skiba, James M.; Scherer, Carolynn P.

    2015-10-13

    Recently there has been a lot of interest in small modular reactors. A specific type of these small modular reactors (SMR,) are marine based power plants called floating nuclear power plants (FNPP). These FNPPs are typically built by countries with extensive knowledge of nuclear energy, such as Russia, France, China and the US. These FNPPs are built in one country and then sent to countries in need of power and/or seawater desalination. Fifteen countries have expressed interest in acquiring such power stations. Some designs for such power stations are briefly summarized. Several different avenues for cooperation in FNPP technology are proposed, including IAEA nuclear security (i.e. safeguards), multilateral or bilateral agreements, and working with Russian design that incorporates nuclear safeguards for IAEA inspections in non-nuclear weapons states

  11. Nuclear fear revisited

    NASA Astrophysics Data System (ADS)

    Crease, Robert P.

    2010-10-01

    In 1988 the science historian Spencer Weart published a groundbreaking book called Nuclear Fear: A History of Images, which examined visions of radiation damage and nuclear disaster in newspapers, television, film, literature, advertisements and popular culture.

  12. Nuclear disarmament verification

    SciTech Connect

    DeVolpi, A.

    1993-12-31

    Arms control treaties, unilateral actions, and cooperative activities -- reflecting the defusing of East-West tensions -- are causing nuclear weapons to be disarmed and dismantled worldwide. In order to provide for future reductions and to build confidence in the permanency of this disarmament, verification procedures and technologies would play an important role. This paper outlines arms-control objectives, treaty organization, and actions that could be undertaken. For the purposes of this Workshop on Verification, nuclear disarmament has been divided into five topical subareas: Converting nuclear-weapons production complexes, Eliminating and monitoring nuclear-weapons delivery systems, Disabling and destroying nuclear warheads, Demilitarizing or non-military utilization of special nuclear materials, and Inhibiting nuclear arms in non-nuclear-weapons states. This paper concludes with an overview of potential methods for verification.

  13. Nuclear Thermal Propulsion (NTP)

    NASA Video Gallery

    NASA's history with nuclear thermal propulsion (NTP) technology goes back to the earliest days of the Agency. The Manned Lunar Rover Vehicle and the Nuclear Engine for Rocket Vehicle Applications p...

  14. Triangle Universities Nuclear Laboratory

    SciTech Connect

    Not Available

    1991-01-01

    This report contains brief papers that discusses the following topics: Fundamental Symmetries in the Nucleus; Internucleon Interactions; Dynamics of Very Light Nuclei; Facets of the Nuclear Many-Body Problem; and Nuclear Instruments and Methods.

  15. Fundamentals in Nuclear Physics

    NASA Astrophysics Data System (ADS)

    Basdevant, Jean-Louis, Rich, James, Spiro, Michael

    This course on nuclear physics leads the reader to the exploration of the field from nuclei to astrophysical issues. Much nuclear phenomenology can be understood from simple arguments such as those based on the Pauli principle and the Coulomb barrier. This book is concerned with extrapolating from such arguments and illustrating nuclear systematics with experimental data. Starting with the basic concepts in nuclear physics, nuclear models, and reactions, the book covers nuclear decays and the fundamental electro-weak interactions, radioactivity, and nuclear energy. After the discussions of fission and fusion leading into nuclear astrophysics, there is a presentation of the latest ideas about cosmology. As a primer this course will lay the foundations for more specialized subjects. This book emerged from a series of topical courses the authors delivered at the Ecole Polytechnique and will be useful for graduate students and for scientists in a variety of fields.

  16. RBC nuclear scan

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/003835.htm RBC nuclear scan To use the sharing features on this page, please enable JavaScript. An RBC nuclear scan uses small amounts of radioactive material to ...

  17. Teaching "The Nuclear Predicament."

    ERIC Educational Resources Information Center

    Carman, Philip; Kneeshaw, Stephen

    1987-01-01

    Contends that courses on nuclear war must help students examine the political, social, religious, philosophical, economic, and moral assumptions which characterized the dilemma of nuclear armament/disarmament. Describes the upper level undergraduate course taught by the authors. (JDH)

  18. Nuclear radiation actuated valve

    DOEpatents

    Christiansen, David W.; Schively, Dixon P.

    1985-01-01

    A nuclear radiation actuated valve for a nuclear reactor. The valve has a valve first part (such as a valve rod with piston) and a valve second part (such as a valve tube surrounding the valve rod, with the valve tube having side slots surrounding the piston). Both valve parts have known nuclear radiation swelling characteristics. The valve's first part is positioned to receive nuclear radiation from the nuclear reactor's fuel region. The valve's second part is positioned so that its nuclear radiation induced swelling is different from that of the valve's first part. The valve's second part also is positioned so that the valve's first and second parts create a valve orifice which changes in size due to the different nuclear radiation caused swelling of the valve's first part compared to the valve's second part. The valve may be used in a nuclear reactor's core coolant system.

  19. Nuclear power browning out

    SciTech Connect

    Flavin, C.; Lenssen, N.

    1996-05-01

    When the sad history of nuclear power is written, April 26, 1986, will be recorded as the day the dream died. The explosion at the Chernobyl plant was a terrible human tragedy- and it delivered a stark verdict on the hope that nuclear power will one day replace fossil fuel-based energy systems. Nuclear advocates may soldier on, but a decade after Chernobyl it is clear that nuclear power is no longer a viable energy option for the twenty-first century.

  20. Nuclear air cushion vehicles.

    NASA Technical Reports Server (NTRS)

    Anderson, J. L.

    1973-01-01

    This paper serves several functions. It identifies the 'state-of-the-art' of the still-conceptual nuclear air cushion vehicle, particularly the nuclear powerplant. Using mission studies and cost estimates, the report describes some of the advantages of nuclear power for large air cushion vehicles. The paper also summarizes the technology studies on mobile nuclear powerplants and conceptual ACV systems/missions studies that have been performed at NASA Lewis Research Center.

  1. Nuclear fact book

    SciTech Connect

    Hill, O. F.; Platt, A. M.; Robinson, J. V.

    1983-05-01

    This reference provides significant highlights and summary facts in the following areas: general energy; nuclear energy; nuclear fuel cycle; uranium supply and enrichment; nuclear reactors; spent fuel and advanced repacking concepts; reprocessing; high-level waste; gaseous waste; transuranic waste; low-level waste; remedial action; transportation; disposal; radiation information; environment; legislation; socio-political aspects; conversion factors; and a glossary. (GHT)

  2. Nuclear energy technology

    NASA Technical Reports Server (NTRS)

    Buden, David

    1992-01-01

    An overview of space nuclear energy technologies is presented. The development and characteristics of radioisotope thermoelectric generators (RTG's) and space nuclear power reactors are discussed. In addition, the policy and issues related to public safety and the use of nuclear power sources in space are addressed.

  3. NUCLEAR REACTOR CONTROL SYSTEM

    DOEpatents

    Epler, E.P.; Hanauer, S.H.; Oakes, L.C.

    1959-11-01

    A control system is described for a nuclear reactor using enriched uranium fuel of the type of the swimming pool and other heterogeneous nuclear reactors. Circuits are included for automatically removing and inserting the control rods during the course of normal operation. Appropriate safety circuits close down the nuclear reactor in the event of emergency.

  4. Revitalizing Nuclear Safety Research.

    ERIC Educational Resources Information Center

    National Academy of Sciences - National Research Council, Washington, DC.

    This report covers the general issues involved in nuclear safety research and points out the areas needing detailed consideration. Topics included are: (1) "Principles of Nuclear Safety Research" (examining who should fund, who should conduct, and who should set the agenda for nuclear safety research); (2) "Elements of a Future Agenda for Nuclear…

  5. Basic Nuclear Physics.

    ERIC Educational Resources Information Center

    Bureau of Naval Personnel, Washington, DC.

    Basic concepts of nuclear structures, radiation, nuclear reactions, and health physics are presented in this text, prepared for naval officers. Applications to the area of nuclear power are described in connection with pressurized water reactors, experimental boiling water reactors, homogeneous reactor experiments, and experimental breeder…

  6. Effects of Nuclear Weapons.

    ERIC Educational Resources Information Center

    Sartori, Leo

    1983-01-01

    Fundamental principles governing nuclear explosions and their effects are discussed, including three components of a nuclear explosion (thermal radiation, shock wave, nuclear radiation). Describes how effects of these components depend on the weapon's yield, its height of burst, and distance of detonation point. Includes effects of three…

  7. Teaching Nuclear History.

    ERIC Educational Resources Information Center

    Holl, Jack M.; Convis, Sheila C.

    1991-01-01

    Presents results of a survey of the teaching about nuclear history at U.S. colleges and universities. Reports the existence of a well-established and extensive literature, a focus on nuclear weapons or warfare, and a concentration on nuclear citizenship, therapy, or eschatology for courses outside of history departments. Discusses individual…

  8. Low-temperature lithium diffusion in simulated high-level boroaluminosilicate nuclear waste glasses

    SciTech Connect

    Neeway, James J.; Kerisit, Sebastien N.; Gin, Stephane; Wang, Zhaoying; Zhu, Zihua; Ryan, Joseph V.

    2014-12-01

    Ion exchange is recognized as an integral, if underrepresented, mechanism influencing glass corrosion. However, due to the formation of various alteration layers in the presence of water, it is difficult to conclusively deconvolute the mechanisms of ion exchange from other processes occurring simultaneously during corrosion. In this work, an operationally inert non-aqueous solution was used as an alkali source material to isolate ion exchange and study the solid-state diffusion of lithium. Specifically, the experiments involved contacting glass coupons relevant to the immobilization of high-level nuclear waste, SON68 and CJ-6, which contained Li in natural isotope abundance, with a non-aqueous solution of 6LiCl dissolved in dimethyl sulfoxide at 90 °C for various time periods. The depth profiles of major elements in the glass coupons were measured using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Lithium interdiffusion coefficients, DLi, were then calculated based on the measured depth profiles. The results indicate that the penetration of 6Li is rapid in both glasses with the simplified CJ-6 glass (D6Li ≈ 4.0-8.0 × 10-21 m2/s) exhibiting faster exchange than the more complex SON68 glass (DLi ≈ 2.0-4.0 × 10-21 m2/s). Additionally, sodium ions present in the glass were observed to participate in ion exchange reactions; however, different diffusion coefficients were necessary to fit the diffusion profiles of the two alkali ions. Implications of the diffusion coefficients obtained in the absence of alteration layers to the long-term performance of nuclear waste glasses in a geological repository system are also discussed.

  9. Commercial nuclear power 1990

    SciTech Connect

    Not Available

    1990-09-28

    This report presents the status at the end of 1989 and the outlook for commercial nuclear capacity and generation for all countries in the world with free market economies (FME). The report provides documentation of the US nuclear capacity and generation projections through 2030. The long-term projections of US nuclear capacity and generation are provided to the US Department of Energy's (DOE) Office of Civilian Radioactive Waste Management (OCRWM) for use in estimating nuclear waste fund revenues and to aid in planning the disposal of nuclear waste. These projections also support the Energy Information Administration's annual report, Domestic Uranium Mining and Milling Industry: Viability Assessment, and are provided to the Organization for Economic Cooperation and Development. The foreign nuclear capacity projections are used by the DOE uranium enrichment program in assessing potential markets for future enrichment contracts. The two major sections of this report discuss US and foreign commercial nuclear power. The US section (Chapters 2 and 3) deals with (1) the status of nuclear power as of the end of 1989; (2) projections of nuclear capacity and generation at 5-year intervals from 1990 through 2030; and (3) a discussion of institutional and technical issues that affect nuclear power. The nuclear capacity projections are discussed in terms of two projection periods: the intermediate term through 2010 and the long term through 2030. A No New Orders case is presented for each of the projection periods, as well as Lower Reference and Upper Reference cases. 5 figs., 30 tabs.

  10. History of Nuclear India

    NASA Astrophysics Data System (ADS)

    Chaturvedi, Ram

    2000-04-01

    India emerged as a free and democratic country in 1947, and entered into the nuclear age in 1948 by establishing the Atomic Energy Commission (AEC), with Homi Bhabha as the chairman. Later on the Department of Atomic Energy (DAE) was created under the Office of the Prime Minister Jawahar Lal Nehru. Initially the AEC and DAE received international cooperation, and by 1963 India had two research reactors and four nuclear power reactors. In spite of the humiliating defeat in the border war by China in 1962 and China's nuclear testing in 1964, India continued to adhere to the peaceful uses of nuclear energy. On May 18, 1974 India performed a 15 kt Peaceful Nuclear Explosion (PNE). The western powers considered it nuclear weapons proliferation and cut off all financial and technical help, even for the production of nuclear power. However, India used existing infrastructure to build nuclear power reactors and exploded both fission and fusion devices on May 11 and 13, 1998. The international community viewed the later activity as a serious road block for the Non-Proliferation Treaty and the Comprehensive Test Ban Treaty; both deemed essential to stop the spread of nuclear weapons. India considers these treaties favoring nuclear states and is prepared to sign if genuine nuclear disarmament is included as an integral part of these treaties.

  11. Thermodynamics of nuclear transport

    NASA Astrophysics Data System (ADS)

    Wang, Ching-Hao; Mehta, Pankaj; Elbaum, Michael

    Molecular transport across the nuclear envelope is important for eukaryotes for gene expression and signaling. Experimental studies have revealed that nuclear transport is inherently a nonequilibrium process and actively consumes energy. In this work we present a thermodynamics theory of nuclear transport for a major class of nuclear transporters that are mediated by the small GTPase Ran. We identify the molecular elements responsible for powering nuclear transport, which we term the ``Ran battery'' and find that the efficiency of transport, measured by the cargo nuclear localization ratio, is limited by competition between cargo molecules and RanGTP to bind transport receptors, as well as the amount of NTF2 (i.e. RanGDP carrier) available to circulate the energy flow. This picture complements our current understanding of nuclear transport by providing a comprehensive thermodynamics framework to decipher the underlying biochemical machinery. Pm and CHW were supported by a Simons Investigator in the Mathematical Modeling in Living Systems grant (to PM).

  12. Overview of nuclear data

    SciTech Connect

    Firestone, R.B.

    2003-06-30

    For many years, nuclear structure and decay data have been compiled and disseminated by an International Network of Nuclear Structure and Decay Data (NSDD) evaluators under the auspices of the International Nuclear Data Committee (INDC) of the International Atomic Energy Agency (IAEA). In this lecture I will discuss the kinds of data that are available and describe various ways to obtain this information. We will learn about some of the publications that are available and Internet sources of nuclear data. You will be introduced to Isotope Explorer software for retrieving and displaying nuclear structure and radioactive decay data. The on-line resources Table of Radioactive Isotopes, PGAA Database Viewer, Nuclear Science Reference Search, Table of Isotopes Educational Website, and other information sources will be discussed. Exercises will be provided to increase your ability to understand, access, and use nuclear data.

  13. Environmental consequences of nuclear war

    SciTech Connect

    Harwell, M.A.; Hutchinson, T.C.; Cropper, W.P. Jr.; Harwell, C.C.; Grover, H.D.

    1989-01-01

    This book addresses the ecological, agricultural, and human effects of nuclear war. The topics covered include: Ecological principles relevant to nuclear war; Vulnerability of ecological systems to climatic effects on nuclear war; Additional potential effects of nuclear war on ecological systems; Potential effects of nuclear war on agricultural productivity; Food availability after nuclear war; and Experiences and extrapolations from Hiroshima and Nagasaki.

  14. Nuclear Reactor Physics

    NASA Astrophysics Data System (ADS)

    Stacey, Weston M.

    2001-02-01

    An authoritative textbook and up-to-date professional's guide to basic and advanced principles and practices Nuclear reactors now account for a significant portion of the electrical power generated worldwide. At the same time, the past few decades have seen an ever-increasing number of industrial, medical, military, and research applications for nuclear reactors. Nuclear reactor physics is the core discipline of nuclear engineering, and as the first comprehensive textbook and reference on basic and advanced nuclear reactor physics to appear in a quarter century, this book fills a large gap in the professional literature. Nuclear Reactor Physics is a textbook for students new to the subject, for others who need a basic understanding of how nuclear reactors work, as well as for those who are, or wish to become, specialists in nuclear reactor physics and reactor physics computations. It is also a valuable resource for engineers responsible for the operation of nuclear reactors. Dr. Weston Stacey begins with clear presentations of the basic physical principles, nuclear data, and computational methodology needed to understand both the static and dynamic behaviors of nuclear reactors. This is followed by in-depth discussions of advanced concepts, including extensive treatment of neutron transport computational methods. As an aid to comprehension and quick mastery of computational skills, he provides numerous examples illustrating step-by-step procedures for performing the calculations described and chapter-end problems. Nuclear Reactor Physics is a useful textbook and working reference. It is an excellent self-teaching guide for research scientists, engineers, and technicians involved in industrial, research, and military applications of nuclear reactors, as well as government regulators who wish to increase their understanding of nuclear reactors.

  15. Studies of nuclear reactions relevant to stellar or Big-Bang Nucleosynthesis using ICF plasmas at OMEGA

    NASA Astrophysics Data System (ADS)

    Zylstra, Alex; Herrmann, Hans; Kim, Yongho; Hale, Gerry; Paris, Mark; McEvoy, Aaron; Gatu Johnson, Maria; Frenje, Johan; Li, Chikang; Seguin, Fredrick; Sio, Hong; Petrasso, Richard; McNabb, Dennis; Sayre, Dan; Pino, Jesse; Brune, Carl; Bacher, Andy; Forrest, Chad; Glebov, Vladimir; Stoeckl, Christian; Janezic, Roger; Sangster, Craig

    2015-10-01

    The 3He+3He, T+3He, and p + D reactions directly relevant to Stellar or Big-Bang Nucleosynthesis (BBN) have been studied at the OMEGA laser facility using high-temperature low-density `exploding pusher' implosions. The advantage of using these plasmas is that they better mimic astrophysical systems than cold-target accelerator experiments. Measured proton spectra from the 3He3He reaction are used to constrain nuclear R-matrix modeling. The resulting T+3He gamma-ray data rule out an anomalously-high 6Li production during the Big Bang as an explanation to the high observed values in metal poor first generation stars. The proton spectrum from the T+3He reaction is also being used to constrain the R-matrix model. Recent experiments have probed the p + D reaction for the first time in a plasma; this reaction is relevant to energy production in protostars, brown dwarfs and at higher CM energies to BBN. This work was partially supported by the US DOE, NLUF, LLE, and GA.

  16. Studies of nuclear reactions relevant to stellar or Big-Bang Nucleosynthesis using ICF plasmas at OMEGA

    NASA Astrophysics Data System (ADS)

    Zylstra, Alex; Herrmann, Hans; Kim, Yongho; Hale, Gerry; Paris, Mark; McEvoy, Aaron; Gatu Johnson, Maria; Frenje, Johan; Li, Chikang; Seguin, Fredrick; Sio, Hong; Petrasso, Richard; McNabb, Dennis; Sayre, Dan; Pino, Jesse; Brune, Carl; Bacher, Andy; Forrest, Chad; Glebov, Vladimir; Stoeckl, Christian; Janezic, Roger; Sangster, Craig

    2015-11-01

    The 3He+3He, T+3He, and p +D reactions directly relevant to Stellar or Big-Bang Nucleosynthesis (BBN) have been studied at the OMEGA laser facility using high-temperature low-density `exploding pusher' implosions. The advantage of using these plasmas is that they better mimic astrophysical systems than cold-target accelerator experiments. Measured proton spectra from the 3He3He reaction are used to constrain nuclear R-matrix modeling. The resulting T+3He gamma-ray data rule out an anomalously-high 6Li production during the Big Bang as an explanation to the high observed values in metal poor first generation stars. The proton spectrum from the T+3He reaction is also being used to constrain the R-matrix model. Recent experiments have probed the p +D reaction for the first time in a plasma; this reaction is relevant to energy production in protostars, brown dwarfs and at higher CM energies to BBN. This work was partially supported by the US DOE, NLUF, LLE, and GA.

  17. Big bang nucleosynthesis: Present status

    NASA Astrophysics Data System (ADS)

    Cyburt, Richard H.; Fields, Brian D.; Olive, Keith A.; Yeh, Tsung-Han

    2016-01-01

    Big bang nucleosynthesis (BBN) describes the production of the lightest nuclides via a dynamic interplay among the four fundamental forces during the first seconds of cosmic time. A brief overview of the essentials of this physics is given, and new calculations presented of light-element abundances through 6Li and 7Li, with updated nuclear reactions and uncertainties including those in the neutron lifetime. Fits are provided for these results as a function of baryon density and of the number of neutrino flavors Nν. Recent developments are reviewed in BBN, particularly new, precision Planck cosmic microwave background (CMB) measurements that now probe the baryon density, helium content, and the effective number of degrees of freedom Neff. These measurements allow for a tight test of BBN and cosmology using CMB data alone. Our likelihood analysis convolves the 2015 Planck data chains with our BBN output and observational data. Adding astronomical measurements of light elements strengthens the power of BBN. A new determination of the primordial helium abundance is included in our likelihood analysis. New D/H observations are now more precise than the corresponding theoretical predictions and are consistent with the standard model and the Planck baryon density. Moreover, D/H now provides a tight measurement of Nν when combined with the CMB baryon density and provides a 2 σ upper limit Nν<3.2 . The new precision of the CMB and D/H observations together leaves D/H predictions as the largest source of uncertainties. Future improvement in BBN calculations will therefore rely on improved nuclear cross-section data. In contrast with D/H and 4He, 7Li predictions continue to disagree with observations, perhaps pointing to new physics. This paper concludes with a look at future directions including key nuclear reactions, astronomical observations, and theoretical issues.

  18. British nuclear policymaking

    SciTech Connect

    Bowie, C.J.; Platt, A.

    1984-01-01

    This study analyzes the domestic political, economic, and bureaucratic factors that affect the nuclear policymaking process in Great Britain. Its major conclusion is that, although there have been changes in that process in recent years (notably the current involvement of a segment of the British public in the debate about the deployment of intermediate-range nuclear forces), future British nuclear policymaking will remain much what it has been in the past. Three ideas are central to understanding British thinking on the subject: (1) Britain's long-standing resolve to have her own national nuclear force is largely traceable to her desire to maintain first-rank standing among the nations of the world in spite of loss of empire. (2) Financial considerations have always been important--so much so that they have usually dominated issues of nuclear policy. (3) The executive branch of government dominates the nuclear policymaking process but does not always present a united front. The United States heavily influences British nuclear policy through having supplied Britain since the late 1950s with nuclear data and components of nuclear weapon systems such as Polaris and Trident. The relationship works both ways since the U.S. depends on Britain as a base for deployment of both conventional and nuclear systems.

  19. NUCLEAR DATABASES FOR REACTOR APPLICATIONS.

    SciTech Connect

    PRITYCHENKO, B.; ARCILLA, R.; BURROWS, T.; HERMAN, M.W.; MUGHABGHAB, S.; OBLOZINSKY, P.; ROCHMAN, D.; SONZOGNI, A.A.; TULI, J.; WINCHELL, D.F.

    2006-06-05

    The National Nuclear Data Center (NNDC): An overview of nuclear databases, related products, nuclear data Web services and publications. The NNDC collects, evaluates, and disseminates nuclear physics data for basic research and applied nuclear technologies. The NNDC maintains and contributes to the nuclear reaction (ENDF, CSISRS) and nuclear structure databases along with several others databases (CapGam, MIRD, IRDF-2002) and provides coordination for the Cross Section Evaluation Working Group (CSEWG) and the US Nuclear Data Program (USNDP). The Center produces several publications and codes such as Atlas of Neutron Resonances, Nuclear Wallet Cards booklets and develops codes, such as nuclear reaction model code Empire.

  20. Nuclear Science References Database

    SciTech Connect

    Pritychenko, B.; Běták, E.; Singh, B.; Totans, J.

    2014-06-15

    The Nuclear Science References (NSR) database together with its associated Web interface, is the world's only comprehensive source of easily accessible low- and intermediate-energy nuclear physics bibliographic information for more than 210,000 articles since the beginning of nuclear science. The weekly-updated NSR database provides essential support for nuclear data evaluation, compilation and research activities. The principles of the database and Web application development and maintenance are described. Examples of nuclear structure, reaction and decay applications are specifically included. The complete NSR database is freely available at the websites of the National Nuclear Data Center (http://www.nndc.bnl.gov/nsr) and the International Atomic Energy Agency (http://www-nds.iaea.org/nsr)

  1. Ongoing Space Nuclear Activities

    NASA Technical Reports Server (NTRS)

    Houts, Michael G.

    2007-01-01

    Most ongoing US activities related to space nuclear power and propulsion are sponsored by NASA. NASA-spons0red space nuclear work is currently focused on evaluating potential fission surface power (FSP) systems and on radioisotope power systems (RPS). In addition, significant efforts related to nuclear thermal propulsion (NTP) systems have been completed and will provide a starting point for potential future NTP work.

  2. Assessing the nuclear age

    SciTech Connect

    Ackland, L.; McGuire, S.

    1986-01-01

    This book presents papers on nuclear weapons and arms control. Topics considered include historical aspects, the arms race, nuclear power, flaws in the non-proliferation treaty, North-South issues, East-West confrontation, Soviet decision making with regard to national defense, US and Soviet perspectives on national security, ballistic missile defense (''Star Wars''), political aspects, nuclear winter, stockpiles, US foreign policy, and military strategy.

  3. Nuclear power in space

    SciTech Connect

    Aftergood, S. ); Hafemeister, D.W. ); Prilutsky, O.F.; Rodionov, S.N. ); Primack, J.R. )

    1991-06-01

    Nuclear reactors have provided energy for satellites-with nearly disastrous results. Now the US government is proposing to build nuclear-powered boosters to launch Star Wars defenses. These authors represent scientific groups that are opposed to the use of nuclear power in near space. The authors feel that the best course for space-borne reactors is to ban them from Earth orbit and use them in deep space.

  4. Nuclear power in space

    NASA Astrophysics Data System (ADS)

    Written and verbal testimony presented before the House Subcommittee on Energy Research and Development is documented. Current research efforts related to space nuclear power are discussed including the SP-100 Space Reactor Program, development of radioisotope thermoelectric generators, and the Advanced Nuclear Systems Program. Funding, research and test facilities, specific space mission requirements, and the comparison of solar and nuclear power systems are addressed. Witnesses included representatives from DOD, NASA, DOE, universities, and private industry.

  5. Nuclear Proliferation Challenges

    SciTech Connect

    Professor William Potter

    2005-11-28

    William C. Potter, Director of the Center for Non Proliferation Studies and the Center for Russian and Eurasian Studies at the Monterey Institute of International Studies, will present nuclear proliferation challenges following the 2005 Nuclear Non-Proliferation Treaty (NPT) Review Conference. In addition to elucidating reasons for, and implications of, the conference’s failure, Dr. Potter will discuss common ground between nuclear proliferation and terrorism issues and whether corrective action can be taken.

  6. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  7. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  8. Nuclear Fabrication Consortium

    SciTech Connect

    Levesque, Stephen

    2013-04-05

    This report summarizes the activities undertaken by EWI while under contract from the Department of Energy (DOE) Office of Nuclear Energy (NE) for the management and operation of the Nuclear Fabrication Consortium (NFC). The NFC was established by EWI to independently develop, evaluate, and deploy fabrication approaches and data that support the re-establishment of the U.S. nuclear industry: ensuring that the supply chain will be competitive on a global stage, enabling more cost-effective and reliable nuclear power in a carbon constrained environment. The NFC provided a forum for member original equipment manufactures (OEM), fabricators, manufacturers, and materials suppliers to effectively engage with each other and rebuild the capacity of this supply chain by : Identifying and removing impediments to the implementation of new construction and fabrication techniques and approaches for nuclear equipment, including system components and nuclear plants. Providing and facilitating detailed scientific-based studies on new approaches and technologies that will have positive impacts on the cost of building of nuclear plants. Analyzing and disseminating information about future nuclear fabrication technologies and how they could impact the North American and the International Nuclear Marketplace. Facilitating dialog and initiate alignment among fabricators, owners, trade associations, and government agencies. Supporting industry in helping to create a larger qualified nuclear supplier network. Acting as an unbiased technology resource to evaluate, develop, and demonstrate new manufacturing technologies. Creating welder and inspector training programs to help enable the necessary workforce for the upcoming construction work. Serving as a focal point for technology, policy, and politically interested parties to share ideas and concepts associated with fabrication across the nuclear industry. The report the objectives and summaries of the Nuclear Fabrication Consortium

  9. Nuclear free zone

    SciTech Connect

    Christoffel, T.

    1987-07-01

    Health professionals have played a leading role in alerting and educating the public regarding the danger of nuclear war which has been described as the last epidemic our civilization will know. Having convinced most people that the use of nuclear weapons would mean intolerable consequences, groups such as Physicians for Social Responsibility have focused on the second critical question how likely is it that these weapons will be used. The oultlook is grim. This article describes the nuclear free zone movement, explores relevant legal questions, and shows how the political potential of nuclear free zones threatens to open a deep rift in the American constitutional system.

  10. Nuclear reactor apparatus

    DOEpatents

    Wade, Elman E.

    1978-01-01

    A lifting, rotating and sealing apparatus for nuclear reactors utilizing rotating plugs above the nuclear reactor core. This apparatus permits rotation of the plugs to provide under the plug refueling of a nuclear core. It also provides a means by which positive top core holddown can be utilized. Both of these operations are accomplished by means of the apparatus lifting the top core holddown structure off the nuclear core while stationary, and maintaining this structure in its elevated position during plug rotation. During both of these operations, the interface between the rotating member and its supporting member is sealingly maintained.

  11. Technologists for Nuclear Medicine

    ERIC Educational Resources Information Center

    Barnett, Huey D.

    1974-01-01

    Physicians need support personnel for work with radioisotopes in diagnosing dangerous diseases. The Nuclear Medicine Technology (NMT) Program at Hillsborough Community College in Tampa, Florida, is described. (MW)

  12. 7Li MRI of Li batteries reveals location of microstructural lithium

    NASA Astrophysics Data System (ADS)

    Chandrashekar, S.; Trease, Nicole M.; Chang, Hee Jung; Du, Lin-Shu; Grey, Clare P.; Jerschow, Alexej

    2012-04-01

    There is an ever-increasing need for advanced batteries for portable electronics, to power electric vehicles and to facilitate the distribution and storage of energy derived from renewable energy sources. The increasing demands on batteries and other electrochemical devices have spurred research into the development of new electrode materials that could lead to better performance and lower cost (increased capacity, stability and cycle life, and safety). These developments have, in turn, given rise to a vigorous search for the development of robust and reliable diagnostic tools to monitor and analyse battery performance, where possible, in situ. Yet, a proven, convenient and non-invasive technology, with an ability to image in three dimensions the chemical changes that occur inside a full battery as it cycles, has yet to emerge. Here we demonstrate techniques based on magnetic resonance imaging, which enable a completely non-invasive visualization and characterization of the changes that occur on battery electrodes and in the electrolyte. The current application focuses on lithium-metal batteries and the observation of electrode microstructure build-up as a result of charging. The methods developed here will be highly valuable in the quest for enhanced battery performance and in the evaluation of other electrochemical devices.

  13. Reactions induced by {sup 7}Li beam and optimization of silicon detector telescope

    SciTech Connect

    Uroic, M.; Milin, M.; Di Pietro, A.; Figuera, P.; Fisichella, M.; Lattuada, M.; Martel, I.; Miljanic, D.; Pellegriti, M. G.; Prepolec, L.; Sanchez Benitez, A. M.; Scuderi, V.; Soic, N.; Strano, E.; Torresi, D.

    2012-10-20

    Focus of this article is put on a method of compensating for non-uniformity of 50{mu}m thin silicon detectors, rather than measurement results. The same high sensitivity of particle identification on thin-detector thickness enables to accurately model thickness variation using the measurement data, rather than measuring the thickness separately.

  14. 7Li MR measures of blood lithium--correlation with chemical analysis data.

    PubMed

    Pierson, Emily; Luterbach, Katie; Rzepka, Elzbieta; Ramaprasad, Subbaraya

    2004-01-01

    Lithium is used in the treatment and prophylaxis of manic-depressive illness. A narrow therapeutic range of lithium (0.4-1.2 meq/l) requires constant monitoring of these levels to avoid neurotoxicity and overdose. It is general practice to measure plasma lithium levels as a guide to monitor the therapy. Efforts to predict the concentration of Li at its active sites in the brain have led to the use of red blood cells (RBCs) because they are similar to neuronal cells. Thus RBC lithium is a very relevant clinical parameter for monitoring therapy and to observe the changes at intracellular levels under varying treatment conditions. A measure of both plasma and RBC lithium may be of significant value to physicians and researchers as lithium profile for RBCs correlate more closely with the brain lithium than plasma lithium. Although methods to measure lithium in blood such as atomic absorption or flame photometry exist, a complete quantitation of both plasma and RBC lithium requires a tedious physical separation of the two components prior to chemical analysis. On the other hand, lithium MR technique, via the use of shift reagents, can provide both plasma and RBC lithium in a single study. Here we have performed a correlation study of lithium results obtained from MR with the vitros dry-slide method on blood samples from rats treated with lithium. The results show a high degree of correlation between the two methods. Additionally, the MR measurements made on dilute samples of blood indicate that small blood samples with lithium concentration in the neighborhood of 0.08 meq/l can be measured with high accuracy and reproducibility needed for clinical purposes.

  15. Nuclear Energy and the Environment.

    ERIC Educational Resources Information Center

    International Atomic Energy Agency, Vienna (Austria).

    "Nuclear Energy and the Environment" is a pocket folder of removable leaflets concerned with two major topics: Nuclear energy and Nuclear Techniques. Under Nuclear Energy, leaflets concerning the topics of "Radiation--A Fact of Life,""The Impact of a Fact: 1963 Test Ban Treaty,""Energy Needs and Nuclear Power,""Power Reactor Safety,""Transport,"…

  16. Gordon Conference on Nuclear Research

    SciTech Connect

    Austin, S.M.

    1983-09-01

    Session topics were: quarks and nuclear physics; anomalons and anti-protons; the independent particle structure of nuclei; relativistic descriptions of nuclear structure and scattering; nuclear structure at high excitation; advances in nuclear astrophysics; properties of nuclear material; the earliest moments of the universe; and pions and spin excitations in nuclei.

  17. Nuclear-Powered Debate.

    ERIC Educational Resources Information Center

    Arce, Gary

    1992-01-01

    Describes an exercise to develop interest and understanding about nuclear energy in which students make presentations regarding a proposal to build a hypothetical nuclear power plant. Students spend two weeks researching the topic; give testimony before a "Senate Energy Committee"; and vote on the proposal. Background information is provided. (MDH)

  18. Exotic nuclear matter

    NASA Astrophysics Data System (ADS)

    Lenske, H.; Dhar, M.; Tsoneva, N.; Wilhelm, J.

    2016-01-01

    Recent developments of nuclear structure theory for exotic nuclei are addressed. The inclusion of hyperons and nucleon resonances is discussed. Nuclear multipole response functions, hyperon interactions in infinite matter and in neutron stars and theoretical aspects of excitations of nucleon resonances in nuclei are discussed.

  19. Nuclear Taskforce Summation.

    ERIC Educational Resources Information Center

    1979

    At the end of 1978, there were approximately 230 nuclear-fueled electric generating plants around the world; 72 of these were in the United States. Each plant requires an operations-and-maintenance workforce of 92 people, and attrition occurs at a rate of 8% per year. Requirements for a nuclear taskforce and job training, in view of current…

  20. High energy nuclear structures

    SciTech Connect

    Boguta, J.; Kunz, J.

    1984-03-09

    In conventional nuclear physics the nucleus is described as a non-relativistic many-body system, which is governed by the Schroedinger equation. Nucleons interact in this framework via static two-body potentials, mesonic degrees of freedom are neglected. An alternative description of nuclear physics in terms of a relativistic field theory has been developed by Walecka. The model Lagrangian containing baryons, sigma-mesons and ..omega..-mesons was subsequently extended to include also ..pi..-mesons and rho-mesons. An essential feature of such a nuclear Lagrangian is its renormalizability. In addition to the description of known nuclear structure the field theoretical approach may reveal entirely new nuclear phenomena, based on the explicit treatment of mesonic degrees of freedom. The existence of such abnormal nuclear states was proposed by Lee and Wick employing the sigma-model Lagrangian. There the non-linearity of the meson field equations allows for soliton solutions in the presence of nucleons, in particular the sigma-field may exhibit a kink. Different types of soliton solutions occur in gauge theories with hidden symmetries. In the phenomenological Lagrangian the rho-meson is described by a non-abelian gauge field, that acquires its mass spontaneously due to the non-vanishing vacuum expectation value of a Higgs field. A general ansatz for soliton solutions of such a gauge theory was given by Dashen et al. A specific solution and its possible implications for nuclear physics like anomalous nuclear states were discussed by Boguta.