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Sample records for 6li 7li 9be

  1. Contribution to the study of 6Li + 6Li et 6Li + 9Be reactions

    This research thesis reports measurements of coincidence between γ rays and particles charged in 6Li + 6Li and 6Li + 9Be reactions. These measurements have been repeated with some technical improvements which are described: discrimination between protons and alphas of 7Li* + 4He + p, simultaneous recording of fortuitous coincidences, assessment of the proportion of charged particles at a final state beyond the detection threshold. 'alpha-alpha' coincidences of the 6Li + 6Li → 3α reaction have also been recorded in conditions which better suited the rough study of the middle of the Dalitz diagram than the precise study of the burst into two energetic alphas. Some information have been obtained from 'alpha-p' coincidences of 7Li* + 4He + p and 7Li* + 4He + p. For these measurements, a multi-parametric installation has been developed for the recording of angular correlations at several simultaneous angles

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

    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. Reactions 7Li(e,6He) pe' and 7Li(e,6Li) ne' at intermediate excitation energies

    The reactions 7Li(e,6He) pe' and 7Li(e,6Li) ne' have been studied at intermediate excitation energies. Angular distributions as well as energy distributions are presented. The experimental cross sections are compared to the results obtained from a simple model

  4. Global optical model potentials for symmetrical lithium systems: 6Li+6Li, 7Li+7Li at Elab = 5-40 MeV

    Angular distributions of 6Li+6Li elastic scattering were measured for Elab=5-40 MeV. An optical model analysis of these data together with older data of 7Li+7Li elastic scattering taken at Elab = 8-17 MeV was performed with the aim to search for a ''global'' OM potential which describes elastic scattering in both Li-Li systems in a broad energy range. Both surface and volume absorbing potentials can be found which fulfill this requirement if a linear energy dependence is assumed of the depths of the real as well as the imaginary potential. These depths, if fitted to individual angular distributions, are found to vary in a correlated manner with the beam energy. This is taken as indication of strong coupling between elastic, inelastic, and reaction channels. This is corroborated by the existence of resonances in reaction channels at these energies where the potential depths are most pronouncedly changing. (orig.)

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

    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.

  6. Study of the reactions 6Li(pα)3He, 6Li(dα)4He, 6Li(dp0)7Li and 6Li(dp1)7Li* from 300 keV to 1000 keV

    Experimental results are presented for the four reactions 6Li (pα)3He, 6Li (dα)4He, 6Li (dp0)7Li and 6Li (dp1)7Li* between 300 keV and 1000 keV. The angular distributions, the excitation curves and the total cross-section curves are presented in absolute values. (authors)

  7. Study of the reactions 9Be (d, a0) 7Li, 9Be (d, a1) 7Li*, 9Be (dt)8Be and 9Be (dp0) 10Be from 300 to 1000 keV

    We present the excitation curves, the angular distributions and the total cross-sections for the reactions: 9Be (d α0)7Li, 9Be (d α1)7Li, 9Be (d, t)8Be, 9Be (dp0)10Be, in the energy range from 300 keV to 1 MeV. Our results are in good agreement with the few studies already carried out. In order that the results be presented in absolute values, we have normalized them with those of BIGGERSTAFF. (author)

  8. THE NEW DETECTIONS OF 7Li/6Li ISOTOPIC RATIO IN THE INTERSTELLAR MEDIA

    We have determined the isotopic abundance ratio of 7Li/6Li 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 ζ Oph for comparison with previous data. The observed abundance ratios were 7Li/6Li = 8.1+3.6-1.8 and 6.3+3.0-1.7 for HD169454 and HD250290, respectively. These values are in reasonable agreement with those observed previously in the solar neighborhood ISMs within ±2σ error bars and are also consistent with our measurement of 7Li/6Li = 7.1+2.9-1.6 for a cloud along the line of sight to ζ 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 7Li, Galactic cosmic-ray interactions, stellar nucleosynthesis, and big bang nucleosynthesis.

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

    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.

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

    Bouchelaghem, F; Bouledroua, M

    2014-02-01

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

  11. 7Li(3He,p)9Be reaction and primordial nucleosynthesis

    The differential cross section for the 7Li(3He, p)9Be reaction has been measured in 50 keV intervals at 8 angles (15deg-160deg) in the energy range from Ec.m.=0.5 to 2.0 MeV, and total cross sections were determined from these data. Since this reaction has been noted as being of possible importance in primordial nucleosynthesis, its astrophysical S-factor was calculated from the data. In addition, the S-factor for the 7Li(3H, n)9Be reaction, also of importance in primordial nucleosynthesis, was estimated from the 7Li(3He, p)9Be data and its thermonuclear reaction rate was calculated. (orig.)

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

    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 (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.

  13. Tensor polarization of 6Li*(2.186 MeV, 3+) in the 9Be(p,α)6Li reaction at 40 MeV

    Tensor moments tkq have been determined for the 6Li*(2.186 MeV, 3+) state produced in the 9Be(p,α1)6Li reaction at 40 MeV. Angular correlation measurements were made between α1 and the α-particle or deuteron fragment from the breakup of 6Li*. Comparison of the tkq are made with the predictions of a model that includes direct and exchange processes. Angular distributions of the differential cross sections for the 9Be(p,α)6Li reaction for the g.s. and first two excited states are presented. (orig.)

  14. On the hyperfine structures of the ground state(s) in the ${}^{6}$Li and ${}^{7}$Li atoms

    Frolov, Alexei M

    2016-01-01

    Hyperfine structure of the ground $2^{2}S-$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) $2^{2}S-$state(s) in the ${}^{6}$Li and ${}^{7}$Li atoms.

  15. Space distributions and decay probability for excited state of 7Li*(7,45 MeV) in reaction 7Li(alpha, alpha6Li)n

    Differential cross-sections of excitation and decay of 7Li*(7,45 MeV) resonance into 6Li + n channel in three particle reaction 7Li(alpha, alpha6Li)n at alpha-particle energy of 27,2 MeV have been determined in kinematically complete and incomplete experiments. Usage of position sensitive detector made it possible to obtain the data on space distributions of decay events for full range of possible angles and to determine the total probability of this process, which value essentially differs from the data for binary reactions. This result is agreed with previously obtained [1] and confirms the theoretical calculations [2] of decay branching ratio for short lived near-threshold resonances in three particle reactions

  16. Resonances excited by the 9Be(6Li,d)13C reaction

    Alpha resonant states in 13C up to 15 MeV were excited by the 9Be(6Li,d)13C reaction. The data were taken at a bombarding energy of 25.5 MeV employing the Sao Paulo-Pelletron-Enge Split Pole facility and the nuclear emulsion technique. The resolution of 50 keV allowed for the separation of the resonant contributions to the known 7/2- and (5/2-) states near the 9Be + α threshold both associated with an L = 4 transfer. Several narrow alpha resonant states not previously measured were detected, in particular the one at the 3α + n threshold populated by an L = 2 transfer, revealing a 9Be + α component for the 1/2- cluster state candidate at this threshold. (author)

  17. Gamow shell model description of radiative capture reactions $^6$Li$(p,\\gamma)$$^7$Be and $^6$Li$(n,\\gamma)$$^7$Li

    Dong, G X; Fossez, K; Płoszajczak, M; Jaganathen, Y; Betan, R M Id

    2016-01-01

    According to standard stellar evolution, lithium abundance is believed to be a useful indicator of the stellar age. However, many evolved stars like red giants show huge fluctuations around expected theoretical abundances that are not yet fully understood. The better knowledge of nuclear reactions that contribute to the creation and destruction of lithium can help to solve this puzzle. In this work we apply the Gamow shell model (GSM) formulated in the coupled-channel representation (GSM-CC) to investigate the mirror radiative capture reactions $^6$Li$(p,\\gamma)$$^7$Be and $^6$Li$(n,\\gamma)$$^7$Li. The cross-sections are calculated using a translationally invariant Hamiltonian with the finite-range interaction which is adjusted to reproduce spectra, binding energies and one-nucleon separation energies in $^{6-7}$Li, $^7$Be. All relevant $E1$, $M1$, and $E2$ transitions from the initial continuum states to the final bound states $J={3/2}_1^-$ and $J={1/2}^-$ of $^7$Li and $^7$Be are included. We demonstrate th...

  18. Alpha Resonances in 13C Excited by the 9Be (6Li,d) Reaction

    The 9Be(6Li,d)13C reaction was used to investigate alpha resonant states in 13C 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- at 10.753 MeV and (5/2-) at 10.818 MeV 13C states. The alpha resonance seen at the (3α+n) threshold was not previously reported. The experimental angular distributions are presented in comparison with DWBA predictions.

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

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

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

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

    2014-09-01

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

  1. Study of the reactions 9Be(p, α)6Li, 9Be(p,d)8Be from 300 keV to 900 keV

    The experimental results concerning the two reactions 9Be(p,α)6Li and 9Be(p,d)8Be from 300 to 900 keV are presented. The angular distribution, excitation and total cross-section curves are expressed in absolute values after a normalization carried out using results given by Weber, Davis and Marion. (authors)

  2. Role of neutron transfer processes on the 6Li+120Sn and 7Li+119Sn fusion reactions

    Fisichella M.

    2015-01-01

    Full Text Available The results concerning the study of 6Li+120Sn and 7Li+119Sn systems are presented. These two sistems are characterised by very similar structures of the interacting nuclei and by different Q-value for one-and two- neutron transfer. Our aim is to disentangle the possible effects due to the different n-transfer Q-values, at sub-barriers energies, by comparing the two fusion excitation function. In these experiments the fusion cross section has been measured by using a stack activation technique. No particular differences in the two fusion excitation functions have been observed.

  3. The 9Be(p,α)6Li and 9Be(p,d)8Be cross sections at low energies

    Data for the 9Be(p,α)6Li and 9Be(p,d)8Be reactions with proton energies up to 700 keV are fitted using R-matrix formulae. The data include values of the astrophysical S factors and of the angular-distribution and analysing-power coefficients. A reasonable fit is obtained with two 1- and two 2+ levels of 10B, and one each of 2-, 1+ and 3+ levels. All represent levels outside the energy range fitted except for a 1- level at 6.87 MeV and a 2+ level at 6.95 MeV

  4. Rate of 3H(7Li,n0)9Be and big-bang nucleosynthesis

    The differential cross sections for the 3H(7Li,n0)9Be reaction measured at 5 angles in the energy range E(c.m.)=0.2-0.9 MeV using a pulsed 7Li beam and time-of-flight technique. Absolute values of the cross section were obtained by comparison with the well-known cross section of 3H(d,n)4He at Ed=1.0 MeV. The resulting reaction rates are obtained at temperatures relevant to big-bang nucleosynthesis, and consequences for primordial 9Be abundances are discussed. (orig.)

  5. Study of the {sup 9}Be(p,{alpha}){sup 6}Li reaction via the Trojan Horse Method

    Romano, S.; Lamia, L.; Spitaleri, C.; Cherubini, S.; Gulino, M.; La Cognata, M.; Tumino, A. [INFN, Laboratori Nazionali del Sud, Catania (Italy); Universita di Catania, Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Catania (Italy); Li, C.; Pizzone, R.G. [INFN, Laboratori Nazionali del Sud, Catania (Italy)

    2006-03-15

    The Trojan Horse Method has been applied to the {sup 2}H({sup 9}Be,{sup 6}Li{alpha})n three-body reaction in order to investigate the {sup 9}Be(p,{alpha}){sup 6}Li two-body reaction, which is involved in the study of light element abundances (lithium, beryllium and boron). A coincidence measurement was performed in order to identify the presence of the quasi-free mechanism in the three-body reaction, needed for the application of the method. The astrophysical S(E)-factor was extracted and compared to direct data. No information about electron screening effects can be extracted due to the poor resolution of the indirect data. (orig.)

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

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

    1999-03-01

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

  7. Investigation of the antiprotonic X-ray spectrum of the lithium isotopes 6Li and 7Li

    Antiprotons of the low-energy separated anti p-beam K23 at CERN in Geneva have been stopped in thin (0.6 g/cm2) targets of the Lithium isotopes 6Li and 7Li. The characteristic X-rays of the formed antiprotonic atoms were measured with four identical high-resolution Si (Li) detectors. Three lines of the N- series, four lines of the M-series and the 3d-2p transition of the Balmer series were observed. The measured relative intensities of the M- and N-series transitions are well described by the simple cascade model of Eisenberg and Kessler. The 3d-2p transition is considerably influenced by the strong interaction between antiproton and nucleus and thus drastically reduced in intensity. The analysis of this transition yields the shift and width of the 2p level, whereas the width of the 3d level is deduced from intensity considerations. (orig./HSI)

  8. HOTSPUR progress report: neutron source spectrum characterization, and 6Li(n,xα) and 7Li(n,xα) cross section determination

    As a prerequisite to high accuracy measurements involving the bulk configuration of 6LiD we must have a good grasp of the details of the RTNS-I neutron source energy spectrum. Experiments to this end involving neutron yield vs deuteron energy, ratios of foil activation of selected elements, and pulse height distributions of a Si surface barrier detector are described. With this knowledge, the 4He-production cross sections for 6Li and 7Li are found experimentally to be 0.512b and 0.336b, respectively, at anti E/sub N/ = 15.0 MeV in free-field geometry. 14 references

  9. Trojan horse particle invariance studied with the 6Li(d,α)4He and 7Li(p,α)4He reactions

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

  10. Excitation and decay of 7Li*(4.63) → α + t in the 7Li(αα1)7Li(4.63) and 9Be(dα1)7Li(4.63) reactions in close kinematic conditions

    Angular correlation function (ACF) of alpha particles and tritons from 7Li* (4.63) decay in the d+9Be → α1+7Li*(4.63) → α1+t+α reaction at deuteron energy Ed=13.6 MeV for escape angles Θαlab=45 and 67 deg has been measured. Results of investigation into the α+7Li → α1+7Li*(4.63) → α1+t+d reaction at Eα=27.2 MeV, Θα1lab=30 deg have been used as well. Kinematic conditions for outlet channels of both reactions are identical. An analytical expression for ACF has been derived. The analysis shows that different mechanisms of the first stage of the d+9Be and α+7Li reactions result in differential phase shifts and limits of summing in the formula for ACF and, therefore, in different ACF form

  11. Measurements of double-differential neutron emission cross sections of {sup 6}Li and {sup 7}Li for 18 MeV neutrons

    Ibaraki, Masanobu; Baba, Mamoru; Matsuyama, Shigeo; Sanami, Toshiya; Win, T.; Miura, Takako; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan). Faculty of Engineering

    1997-03-01

    Double-differential neutron emission cross sections of {sup 6}Li and {sup 7}Li were measured for 18 MeV neutrons at Tohoku University 4.5 MV Dynamitron facility. Neutron emission spectra were obtained down to 1 MeV at 13 angles with energy resolution good enough to separate discrete levels. A care was taken to eliminate the sample-dependent background due to parasitic neutrons. Experimental results were in fair agreement with the JENDL-3.2 data and a simple model considering a three-body breakup process and discrete level excitations. (author)

  12. Lithium isotope separation by 6Li/7Li countercurrent exchange between lithium-amalgam and aqueous LiOH in a spray column

    Lithium isotope separation by 6Li/7Li exchange between lithium-amalgam and aqueous LiOH has been investigated by using a column consisting of a vertical Pyrex glass tube in which aqueous LiOH flows up and a fine spray of lithium-amalgam falls down. As the number of theoretical plates, a value of 48 was obtained on a single column while the amalgam stability was η = 0.74, where η is the ratio between Li concentration in amalgam at the column bottom and that at the column top. That is, a large separation may be obtained in a single column in spite of amalgam decomposition which takes place as a side reaction. (author)

  13. Investigation of 7Li+d cluster channel at the photodisintegration of 9Be nucleus presented by 2αn-model

    In present work the process 9Be(γ, d)7Li has been investigated within the energy range of Eγ from the threshold up to 40 MeV. In the framework of cluster approach method of analysis of differential cross sections resonance structure has been developed. Wave functions of 7Lid cluster channel were obtained analytically by projecting of 2αn wave functions of 9Be nucleus. (author)

  14. The {sup 9}Be(p,p{sub 0}){sup 9}Be, {sup 9}Be(p,d{sub 0}){sup 8}Be, and {sup 9}Be(p,α{sub 0}){sup 6}Li cross-sections for analytical purposes

    Krat, S. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe Road 31, Moscow 115409 (Russian Federation); Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); Mayer, M. [Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); Porosnicu, C. [National Institute for Laser, Plasma and Radiation Physics, Atomistilor 409, Magurele, Jud Ilfov, 077125 Bucharest (Romania)

    2015-09-01

    The cross-sections for the {sup 9}Be(p,d{sub 0}){sup 8}Be nuclear reaction and for {sup 9}Be(p,p{sub 0}){sup 9}Be backscattering were measured at a laboratory scattering angle of 165° in the energy range from 400 to 4150 keV, the cross-section for the {sup 9}Be(p,α{sub 0}){sup 6}Li nuclear reaction was determined in the energy range from 400 to 1300 keV. The cross-sections were determined using thin films. The absolute accuracies are about 4.4–8.6% for the backscattering, 4.6–24% for the {sup 9}Be(p,d{sub 0}){sup 8}Be nuclear reaction, and 4.5–5% for the {sup 9}Be(p,α{sub 0}){sup 6}Li nuclear reaction cross-section. The derived cross-section data were benchmarked in the energy range 1100–4100 keV by comparison to measured spectra from bulk beryllium. The cross-section data are presented in graphical and tabular forms.

  15. Production cross section of At radionuclides from $^{7}$Li+$^{\\textrm{nat}}$Pb and $^{9}$Be+$^{\\textrm{nat}}$Tl reactions

    Maiti, Moumita

    2011-01-01

    Earlier we reported theoretical studies on the probable production of astatine radionuclides from $^{6,7}$Li and $^{9}$Be-induced reactions on natural lead and thalliun targets, respectively. For the first time, in this report, production of astatine radionuclides has been investigated experimentally with two heavy ion induced reactions: $^{9}$Be+$^{\\textrm{nat}}$Tl and $^{7}$Li+$^{\\textrm{nat}}$Pb. Formation cross sections of the evaporation residues, $^{207,208,209,210}$At, produced in (HI, xn) channel, have been measured by the stacked-foil technique followed by the off-line $\\gamma$-spectrometry at the low incident energies ($<$50 MeV). Measured excitation functions have been explained in terms of compound nuclear reaction mechanism using Weisskopf-Ewing and Hauser-Feshbach model. Absolute cross section values are lower than the respective theoretical predictions.

  16. TL response of pairs of 6LiF:Mg,Cu,Si/7LiF:Mg,Cu,Si and TLD-600/TLD-700 to 0.1–12 MeV neutrons

    Neutron dosimetery continues to remain an important and a challenging aspect of radiation protection due to the higher biological effectiveness of neutrons than that of gamma rays and the intricacy in the responses of the detectors. The need for personal dosimetry in mixed fields of neutrons and gamma rays has considerably increased due to the rising number of nuclear facilities, nuclear power plants, medical therapy equipment, accelerators and so on. The most widely used technique for personal dosimetry has been the albedo technique employing pairs of neutron sensitive 6LiF:Mg,Ti (TLD-600) and neutron insensitive 7LiF:Mg,Ti (TLD-700) thermoluminescent dosimeters (TLDs). Off late, LiF:Mg,Cu,Si has emerged as one of the most promising TLD material, having the advantages of high sensitivity, near tissue equivalence to gamma rays, negligible fading on pre and post-irradiation storage, thermal stability for readout and negligible residual signal after the readout. In this study, neutron energy response of indigenously developed 6LiF:Mg,Cu,Si and 7LiF:Mg,Cu,Si TLD pairs was evaluated to neutrons of energy from thermal to 11.6 MeV and was compared with the response of TLD-600 and TLD-700 pairs. The net TL per unit neutron dose for the 6LiF:Mg,Cu,Si/7LiF:Mg,Cu,Si TLD pair was found to be about 10 times of that of the TLD-600/TLD-700 pair. Unlike, TLD-600 and TLD-700, the glow curve structure of 6LiF:Mg,Cu,Si and 7LiF:Mg,Cu,Si remained almost the same for all the irradiations. Thus, 6LiF:Mg,Cu,Si and 7LiF:Mg,Cu,Si TLDs provided a better alternate to TLD-600 and TLD-700 for the dosimetry of mixed fields of neutrons and gamma rays. -- Highlights: ► High sensitivity 6Li and 7Li enriched LiF:Mg,Cu,Si TLDs have been developed at KAERI, Korea. ► Main TL glow peak remains unchanged for 6Li and 7Li enrichment and radiation type. ► Net TL/mSv is about 10 times of that of TLD-600/TLD-700 pairs

  17. 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

    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°.

  18. Levels in 148Tb excited by the (6Li,2n), (7Li,3n) and (10B,4n) reactions

    High spin states in 148Tb have been excited by means of 144Sm(6Li,2n), 144Sm(7Li,3n), and 142Nd(10B,4n) reactions and studied by γ-ray and electron measurements. Gamma-ray singles, excitation functions, angular distributions, internal conversion coefficients, and γ-γ coincidence measurements have been made. A seven-fold gamma-gamma cascade feeding the 9+ isomeric state in 148Tb and originating in a level 4137keV above that state is strongly excited. The spin and parity assignments are made on the basis of angular distribution and internal conversion coefficients. On the basis of these measurements, the 1006keV transition is E3 in character; the half-life of the 1006keV(12-) level is established to be 25 +- 2ns. These experiments also confirm the existence of a number of high spin states in 148Gd seen by earlier workers. (author)

  19. Astrophysical Impact of the Updated 9Be(p,α)6Li and 10B(p,α)7Be Reaction Rates As Deduced By THM

    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.

  20. Effects on distortion on the inter cluster motion in 2H, 3He, 6Li and 9Be on Trojan Horse applications

    Deuteron induced quasi-free scattering and reactions have been extensively investigated in the past few decades as well as 6Li, 3H, 3He and 9Be induced ones. This was done not only for nuclear structure and reaction mechanisms investigation but also for important astrophysical implications (Trojan Horse Method)[1]. In particular the width and the shape of the spectator momentum distribution inside several nuclei which have been used as Trojan Horse ones have been obtained as a function of the transferred momentum for all these nuclei. The behaviour of the width of the spectator momentum distribution as a function of the transferred momentum will be discussed extensively. This work is the continuation of what has been done for Li6 in [2]. Moreover a complete study on Trojan Horse method applications will also be given because the momentum distribution of the spectator particle inside the Trojan horse nucleus is a necessary input for the application of this method. This will give hints on distortion effects at low energies as well as implications for nuclear astrophysics.(author)

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

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

    2016-05-26

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

  2. The use of enriched 6Li and 7Li LiF: Mg, Cu, P glass-rod thermoluminescent dosemeters for linear accelerator out-of-field radiation dose measurements

    6Li:Mg, Cu, P and 7Li:Mg, Cu, P glass-rod thermoluminescent dosemeters (TLDs) were used for measurements of out-of-field photon and neutron doses produced by Varian iX linear accelerator. Both TLDs were calibrated using 18-MV X-ray beam to investigate their dose-response sensitivity and linearity. CR-39 etch-track detectors (Luxel+, Landauer) were employed to provide neutron dose data to calibrate 6Li:Mg, Cu, P TLDs at various distances from the iso-centre. With cadmium filters employed, slow neutrons (< 0.5 eV) were distinguished from fast neutrons. The average in-air photon dose equivalents per monitor unit (MU) ranged from 1.5±0.4 to 215.5±94.6 uμSv at 100 and 15 cm from the iso-centre, respectively. Based on the cross-calibration factors obtained with CR-39 etch-track detectors, the average in-air fast neutron dose equivalents per MU range from 10.6±3.8 to 59.1±49.9 uμSv at 100 and 15 cm from the iso-centre, respectively. Contribution of thermal neutrons to total neutron dose equivalent was small: 3.1±7.2 uμSv per MU at 15 cm from the iso-centre. (authors)

  3. The use of enriched 6Li and 7Li Lif:Mg,Cu,P glass-rod thermoluminescent dosemeters for linear accelerator out-of-field radiation dose measurements.

    Takam, R; Bezak, E; Liu, G; Marcu, L

    2012-06-01

    (6)LiF:Mg,Cu,P and (7)LiF:Mg,Cu,P glass-rod thermoluminescent dosemeters (TLDs) were used for measurements of out-of-field photon and neutron doses produced by Varian iX linear accelerator. Both TLDs were calibrated using 18-MV X-ray beam to investigate their dose-response sensitivity and linearity. CR-39 etch-track detectors (Luxel+, Landauer) were employed to provide neutron dose data to calibrate (6)LiF:Mg,Cu,P TLDs at various distances from the isocentre. With cadmium filters employed, slow neutrons (calibration factors obtained with CR-39 etch-track detectors, the average in-air fast neutron dose equivalents per MU range from 10.6±3.8 to 59.1±49.9 μSv at 100 and 15 cm from the isocentre, respectively. Contribution of thermal neutrons to total neutron dose equivalent was small: 3.1±7.2 μSv per MU at 15 cm from the isocentre. PMID:21873634

  4. 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

    Lonski, P; Kron, T [Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); RMIT University, Melbourne, Victoria (Australia); Franich, R; Keehan, S [RMIT University, Melbourne, Victoria (Australia); Siva, S [Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria (Australia); Taylor, M [Australian Federal Police, Canberra, ACT (Australia)

    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.

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

    Olimov, K., E-mail: olimov@uzsci.net [Uzbek Academy of Sciences, Physical-Technical Institute, Fizika-Solntse Research and Production Association (Uzbekistan); Glagolev, V. V. [Joint Institute for Nuclear Research (Russian Federation); Gulamov, K. G.; Lutpullaev, S. L.; Kurbanov, A. R.; Olimov, A. K.; Petrov, V. I.; Yuldashev, A. A. [Uzbek Academy of Sciences, Physical-Technical Institute, Fizika-Solntse Research and Production Association (Uzbekistan)

    2013-07-15

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

  6. Evidence of Cluster Structure of $^9$Be from $^3$He+$^9$Be Reaction

    Lukyanov, S M; Naumenko, M A; Xu, Yi; Trzaska, W H; Burjan, V; Kroha, V; Mrazek, J; Glagolev, V; Piskoř, Š; Voskoboynik, E I; Khlebnikov, S V; Penionzhkevich, Yu E; Skobelev, N K; Sobolev, Yu G; Tyurin, G P; Kuterbekov, K; Tuleushev, Yu

    2015-01-01

    The study of inelastic scattering and multi-nucleon transfer reactions was performed by bombarding a $^{9}$Be target with a $^3$He beam at an incident energy of 30 MeV. Angular distributions for $^9$Be($^3$He,$^3$He)$^{9}$Be, $^9$Be($^3$He,$^4$He)$^{8}$Be, $^9$Be($^3$He,$^5$He)$^{7}$Be, $^9$Be($^3$He,$^6$Li)$^6$Li and $^9$Be($^3$He,$^5$Li)$^7$Li reaction channels were measured. Experimental angular distributions for the corresponding ground states (g.s.) were analysed within the framework of the optical model, the coupled-channel approach and the distorted-wave Born approximation. Cross sections for channels leading to unbound $^5$He$_{g.s.}$, $^5$Li$_{g.s.}$ and $^8$Be systems were obtained from singles measurements where the relationship between the energy and the scattering angle of the observed stable ejectile is constrained by two-body kinematics. Information on the cluster structure of $^{9}$Be was obtained from the transfer channels. It was concluded that cluster transfer is an important mechanism in t...

  7. Angular correlations and decay branching ratio for excited state of 7Li*(7,45 MeV) in reactions 7Li(alpha, alpha)7Li*

    Measurements of differential cross-sections of alpha-particle inelastic scattering by 7Li nuclei and 7Li(alpha, alpha 6Li)n, 7Li(alpha, alpha alpha)t reactions have been performed at the energy Ea = 27,2 MeV. Probability of 7Li*(7,45 MeV) decay into 6Li + n channel has been determined from the ratio of cross-sections measured in kinematically complete and incomplete experiments. The large discrepancy of this value (P 0,49 ± 0,06) and of those obtained at the study of 7Li*(7,45 MeV) decay in binary reactions can be explained by the influence of Coulomb field of accompanied alpha-particle on the decay of near-threshold resonances in three-particle reactions

  8. X particle effect for 6Li reaction rates calculations

    The inferred primordial 6Li-7Li abundances are different from standard big bang nucleosynthesis results, 6Li is 1000 times larger and 7Li is 3 times smaller than the big bang prediction. In big bang nucleosynthesis, negatively charged massive X particles a possible solution to explain this primordial Li abundances problem [1]. In this study, we consider only X particle effect for nuclear reactions to obtain S-factor and reaction rates for Li. All S-factors calculated within the Optical Model framework for d(α,γ)6Li system. We showed that the enhancement effect of massive negatively charged X particle for 6Li system reaction rate.(author)

  9. Elastic scattering of vector polarized 7LiON58Ni

    The elastic scattering of vector polarized 7Li on 58Ni at 20.3 MeV exhibits vector analyzing powers of approximate the same size but of opposite sign as the ones observed for elastic 6Li-58Ni scattering. Present versions of the folding model predict that vector analyzing powers for 7Li should have the same much smaller magnitude than for 6Li scattering. The physical reasons of this observed effect are presently not known. (orig.)

  10. 6^Li in the atmosphere of GJ 117 Revisited

    Christian, D J; Jevremovic, D

    2008-01-01

    Detection of 6^Li has been shown for energetic solar events, one chromospherically active binary, and several dwarf halo stars. We had previously found a 6^Li/7^Li = 0.03+/-0.01 for active K dwarf GJ 117 using VLT UVES observations. Here we present high signal-to-noise (>1000) high spectral resolution observations taken with the McDonald Observatory's 2.7m and echelle spectrometer of GJ 117. We have used the solar spectrum and template stars to eliminate possible blends, such as Ti I, in the 6^Li spectral region. Our new analysis, using an updated PHOENIX model atmosphere finds 6^Li/7^Li = 0.05+/-0.02. Additionally, bisector analysis showed no significant red asymmetries that would affect the lithium line profile. No changes above the statistical uncertainties are found between the VLT and McDonald data. The amount of 6^Li derived for GJ 117 is consistent with creation in spallation reactions on the stellar surface, but we caution that uncertainties in the continuum level may cause additional uncertainty in t...

  11. Systematic model-dependent behaviour of fusion involving weakly bound projectiles 6,7Li

    Many measurements on complete fusion (CF) cross section at above barrier energies involving weakly bound stable projectiles (e.g., 6Li, 7Li and 9Be) show suppression by various degrees compared to theoretical estimates as well as experimental CF cross sections of reactions involving strongly bound projectiles. However, there is no concrete picture at sub-barrier energies. The conclusions based on coupled-channels (CC) calculations using different codes (e.g., FRESCO or CCFULL) may differ as the theoretical models used to calculate fusion are not same. In a recent paper on complete fusion in 7Li+152Sm system, the fusion cross sections calculated by CCFULL and FRESCO have been shown to be different despite using same bare potential. It was observed that with the inclusion of only inelastic couplings, the results of FRESCO were much closer to the experimental data in the above barrier region, while the CCFULL results overpredict the data over the entire range. To explore the above observation in different systems involving 6,7Li as projectile, in the present work, a systematic and detailed study has been carried out by means of CC calculations using both FRESCO and CCFULL. The aim is to analyze the differences between the two models of calculations

  12. THE 2H(alpha, gamma6LI REACTION AT LUNA AND BIG BANG NUCLEOSYNTHETIS

    Carlo Gustavino

    2013-12-01

    Full Text Available The 2H(α, γ6Li reaction is the leading process for the production of 6Li in standard Big Bang Nucleosynthesis. Recent observations of lithium abundance in metal-poor halo stars suggest that there might be a 6Li plateau, similar to the well-known Spite plateau of 7Li. This calls for a re-investigation of the standard production channel for 6Li. As the 2H(α, γ6Li cross section drops steeply at low energy, it has never before been studied directly at Big Bang energies. For the first time the reaction has been studied directly at Big Bang energies at the LUNA accelerator. The preliminary data and their implications for Big Bang nucleosynthesis and the purported 6Li problem will be shown.

  13. Pion electroproduction from 6Li

    The pion electroproduction cross section from 6Li is calculated assuming the 6He nucleus is detected. The wave functions used in this calculation are those which gave the best agreement with the 6Li(γ, π+)6He data. The electroproduction experiment will provide a useful check of these wave functions. (Auth.)

  14. 6Li detection in metal-poor stars: can 3D model atmospheres solve the second lithium problem?

    Steffen, M; Caffau, E; Bonifacio, P; Ludwig, H -G; Spite, M

    2012-01-01

    The presence of 6Li in the atmospheres of metal-poor halo stars is usually inferred from the detection of a subtle extra depression in the red wing of the 7Li doublet line at 670.8 nm. However, the intrinsic line asymmetry caused by convective flows in the photospheres of cool stars is almost indistinguishable from the asymmetry produced by a weak 6Li blend on a (presumed) symmetric 7Li profile. Previous determinations of the 6Li/ 7Li isotopic ratio based on 1D model atmospheres, ignoring the convection-induced line asymmetry, must therefore be considered as upper limits. By comparing synthetic 1D LTE and 3D non-LTE line profiles of the Li 670.8 nm feature, we quantify the differential effect of the convective line asymmetry on the derived 6Li abundance as a function of effective temperature, gravity, and metallicity. As expected, we find that the asymmetry effect systematically reduces the resulting 6Li/7Li ratios. Depending on the stellar parameters, the 3D-1D offset in 6Li/7Li ranges between -0.005 and -0....

  15. The 7Li(γ,N) and 7Li(e,N) reactions at intermediate photon energies

    Cross sections for single-photonucleon emissions from 7Li have been measured for photon energies in the range 60-120 MeV by detecting the recoiling residual nuclei following excitation with bremsstrahlung radiation of end-point energies 140 and 155 MeV. Measurements of the 7Li(e,6Li)e'p and 7Li(e,6He)e'n cross sections were also made at the same electron energies. A significant difference between the ratio of electron- and bremsstrahlung-induced yields for proton and neutron emission is observed. The results are compared to a modified quasi-deuteron model and a simple direct-knockout model in which recoil terms are included. (orig.)

  16. Electric dipolarizability of 7Li

    Sudhir R Jain; Arun K Jain; S Kailas

    2008-12-01

    We calculate the electric dipolarizability of 7Li nucleus within the cluster model and estimate a value of about 0.0188 fm3. We also discuss the possibility of observing this in the scattering of 7Li from a 208Pb target at energies about 30 MeV.

  17. Deformation Effects in 6Li

    The asymptotic D - to S -state ratio η for the 6Li> bound-state overlap is determined from measurements of the tensor analyzing powers for (6Li,d ) reactions on medium-heavy targets. The reactions are described by the distorted-wave Born approximation assuming a direct α -particle transfer reaction mechanism. The calculations provide good agreement with cross section and vector analyzing power data. A best fit to the tensor analyzing power data results in a new value of η=+0.0003±0.0009 , much smaller than previous experimental and theoretical determinations. copyright 1998 The American Physical Society

  18. Global optical-model potentials for the elastic scattering of sup(6,7)Li projectiles

    Simultaneous fits have been made to 44 6Li data sets covering the mass range 24-208 and the energy range 13-156 MeV in order to determine an average ('global') optical-model potential for 6Li scattering. A similar study has been made for 25 7Li data sets over the same mass range and an energy range of 28-88 MeV to find an average 7Li potential. With Saxon-Woods factors, constant values may be used for all parameters except for the depth of the imaginary potential which decreases in magnitude with increasing mass. The necessity of energy dependence, Coulomb correction and (for 7Li) a symmetry term is investigated. The variation of the integral properties of the potentials is discussed, and also a comparison is made for the two projectiles. Application of the global potentials is made to inelastic scattering and single-nucleon transfer reactions. (orig.)

  19. Lines in the spectrum of 7LiH (4728--5298 A)

    The emission spectra of the A1Σ+--X1Σ+ bands of 7LiH were photographed in the 4728A - 5298 A region with a 3.4 meter Ebert Spectrograph of theoretical resolution of about 0.07 cm-1. High purity 7LiH crystals were obtained from Oak Ridge National Laboratory. The atomic percent of 7Li in 7LiH and 7LiD was 99.93 percent. The discharge source was a demountable stainless steel hollow cathode lamp. The lithium hydride crystals were packed into the cathode. Pressure in the discharge tube was about 10 to 20 torr of H2. The discharge was run at about 600 volts and 1.25 to 1.75 amperes. Acceptable spectra were obtained with exposure time of 6 hours. A Westinghouse iron hollow cathode was used to produce the iron spectrum for calibration. The plates were measured on the Gaertner photoplate comparator with an encoder system and on-line computer service at Argonne National Laboratory. The measured lines in the spectra of 7LiH are given in this repot 9COO-2326-19). Similar spectra for 6LiH and 6LiD are given in companion reports (COO-2326-17) and (COO-2326-18), respectively. The relative intensities of the lines are applicable only to short regions and do not extend over the whole spectrum

  20. Fission fragment mass and angular distribution in 6,7Li+235,238U reactions

    Fission fragment (FF) angular distributions for 6,7Li+235,238U reactions and mass distributions for 6,7Li+ 238U reactions have been measured at energies near and above the Coulomb barrier. The angle integrated fission cross sections for 6Li induced reactions at sub-barrier energies are found to be higher than 7Li induced reactions possibly due to larger contribution of breakup induced fission in case of the former compared to the latter. The FF anisotropy for 6,7Li+235U was found to be smaller than 6,7Li+238U, manifesting the effect of target ground state spin. The statistical saddle point (SSP) model predictions were found to be consistent with the measured FF anisotropy for 6,7Li+235U, however they were under-estimated for 6,7Li+238U particularly at lower energies. Observation of larger FWHM of FF folding angle distribution and sharp increase in peak to valley ratio for FF mass distribution with the decrease in bombarding energy in 6,7Li+238U reactions confirms the presence of breakup induced fission. (authors)

  1. Fission fragment mass and angular distribution in 6,7Li+235,238U reactions

    Santra S.

    2013-12-01

    Full Text Available Fission fragment (FF angular distributions for 6,7Li+235,238U reactions and mass distributions for 6,7Li+238U reactions have been measured at energies near and above the Coulomb barrier. The angle integrated fission cross sections for 6Li induced reactions at sub-barrier energies are found to be higher than 7Li induced reactions possibly due to larger contribution of breakup induced fission in case of the former compared to the latter. The FF anisotropy for 6,7Li+235U was found to be smaller than 6,7Li+238U, manifesting the effect of target ground state spin. The statistical saddle point (SSP model predictions were found to be consistent with the measured FF anisotropy for 6,7Li+235U, however they were under-estimated for 6,7Li+238U particularly at lower energies. Observation of larger FWHM of FF folding angle distribution and sharp increase in peak to valley ratio for FF mass distribution with the decrease in bombarding energy in 6,7Li+238U reactions confirms the presence of breakup induced fission.

  2. Lamb shifts and hyperfine structure in 6Li+ and 7Li+: Theory and experiment

    Riis, E.; Sinclair, A. G.; Poulsen, Ove;

    1994-01-01

    level. Second, the isotope shifts in the full transition frequencies are used to deduce the difference in rms nuclear radii. The result is R(rms)(Li-6) - R(rms)(Li-7) = 0.15 +/- 0.01 fm, in agreement With nuclear scattering data, but with substantially improved accuracy. Third, high...

  3. Lines in the spectrum of 6LiH (2985--5158 A)

    The emission spectra of the A1Σ+--X1Σ+ bands of 6LiH were photographed in the 2985 - 5158 A region with a 3.4 meter Ebert Spectrograph of theoretical resolution of about 0.07 cm-1. High-purity 6LiH crystals were obtained from Oak Ridge National Laboratory. The atomic percent of 6Li in 6LiH was 95.58 percent. The discharge source was a demountable stainless steel hollow cathode lamp. The lithium hydride crystals were packed into the cathode. Pressure in the discharge tube was about 10 to 20 torr of H2. The disharge was run at about 600 volts and 1.25 to 1.75 amperes. Acceptable spectra were obtained with exposure time of 6 hours. A Westinghouse iron hollow cathode was used to produce the iron spectrum for calibration. The plates were measured on the Gaertner photoplate comparator with an encoder system and on-line computer service at Argonne National Laboratory. The measured lines in the spectra of 6LiH are given in this report (COO-2326-17). Similar spectra for 6LiD and 7LiH are given in companion reports (COO-2326-18) and (COO-2326-19), respectively. The relative intensities of the lines are applicable only to short regions and do not extend over the whole spectrum

  4. Lines in the spectrum of 6LiD (3086--5156 A)

    The emission spectra of A1Σ+--X1Σ+ bands of 6LiD were photographed in the 3086 A - 5156 A region with a 3.4 meter Ebert Spectrograph of theoretical resolution of about 0.07 cm-1. High-purity 6LiD crystals were obtained from Oak Ridge National Laboratory. The atomic percent of 6Li in 6LiD was 95.58 percent. The discharge source is a demountable stainless steel hollow cathode lamp. The lithium deuteride crystals were packed into the cathode. Pressure in the discharge tube was about 10 to 20 torr of D2. The discharge was run at about 600 volts and 1.25 to 1.75 amperes. Acceptable spectra were obtained with exposure time of 6 hours. A Westinghouse iron hollow cathode was used to produce the iron spectrum for calibration. The plates were measured on the Gaertner photoplate comparator with an encoder system and on-line computer service at Argonne National Laboratory. The measured lines in the spectra of 6LiD are given in this report (COO-2326-18). Similar spectra for 6LiH and 7LiH are given in companion reports (COO-2326-17) and (COO-2326-19), respectively. The relative intensities of the lines are applicable only to short regions and do not extend over the whole spectrum

  5. Tritium production in a sphere of 6LiD irradiated by 14-MeV neutrons

    The specific production of tritium in samples of 6LiH and 7LiH embedded in a 600-mm-diam sphere of 6LiD irradiated by a central source of 14-MeV neutrons was determined by measuring the activity of the hydrogen evolved from the samples of each isotope at each of five different radii in the 6LiD assembly. The entire process of decomposing the LiH, transferring the evolved gas into counters, and determining the decay rate was standardized by processing LiH samples irradiated by thermal neutrons for which the 6Li(n,α) cross section is well known. The specific production of tritium in 6LiH and 7LiH (embedded samples) and the activation of radiochemical detector foils of 45Sc, 89Y, 90Zr, 169Tm, 191Ir 373, 193Ir 627, 197Au, 235U, and 238U placed at various positions in the 6LiD sphere were calculated and compared with the experimental data. One- and three-dimensional Monte Carlo and S/sub n/ neutron-transport calculations were performed. The most reliable (three-dimensional Monte Carlo) calculation is in reasonable agreement with both the tritium-production and the radiochemical-activation data. The existing discrepancies between calculation and experiment appear largely attributable to uncertainties in some tritium-production and radiochemical-activation cross sections. 15 references

  6. Analysis of tritium production in concentric spheres of oralloy and 6LiD irradiated by 14-MeV neutrons

    Tritium production and activation of radiochemical detector foils in a sphere of 6LiD with an oralloy core irradiated by a central source of 14-MeV neutrons have been calculated and compared with experimental measurements. The experimental assembly consisted of an oralloy sphere surrounded by three solid 6LiD concentric shells with ampules of 6LiH and 7LiH and activation foils located in several positions throughout the assembly. The Los Alamos Monte Carlo Neutron Photon Transport Code (MCNP) was used to calculate neutron transport throughout the system, tritium production in the ampules, and foil activation. The overall experimentally observed-to-calculated ratios of tritium production were 0.996 +- 2.5% in 6Li ampules and 0.903 +- 5.2% in 7Li ampules. Observed-to-calculated ratios for foil activation are also presented. 11 refs., 4 figs., 7 tabs

  7. Multibody final states of the 6Li+6Li reaction at 97 MeV

    Absolute coincidence cross sections were measured for the reactions 6Li+6Li->3α, 6Li(6Li, 2α), and 6Li(6Li, 2d), where the latter two represent N-body (N >= 4) final states. Broad peaks from the 6Li(6Li, 2α) reaction are well described by a double spectator pole (DSP) model utilizing a Hulthen wave function, whereas near 40 MeV the DSP peaks are much narrower than predicted. A broad peak in the 3α final-state spectrum attributed to a single-spectator pole (SSP) process, is well described with the same wave function. The SSP is the principal mechanism for the 3α reaction, in contrast to data near 40 MeV which show that sequential decay from 8Be levels is dominant. (orig.)

  8. Study of fusion in 6,7Li+197Au near barrier energies

    Excitation functions are measured for complete fusion and transfer reactions of 6Li and 7Li with 197Au at energies around the Coulomb barrier. Coupled channel calculations including the couplings to both target and projectile excited states have been performed and are found to explain the data at energies below the barrier. At above barrier energies the complete fusion cross sections are found to be suppressed compared to the coupled channel calculations for both the systems. A systematic comparison of fusion cross-section for halo nuclei 6,8He and weakly bound stable nuclei 6,7Li on 197Au target is also presented. Large neutron transfer cross-sections are observed for 6,7Li as compared to tightly bound projectiles 12C,16O. (authors)

  9. Reanalysis of tritium production in a sphere of 6LiD irradiated by 14-MeV neutrons

    Tritium production and activation of radiochemical detector foils in a sphere of 6LiD irradiated by a central source of 14-MeV neutrons has been reanalyzed. The 6LiD sphere consisted of 10 solid hemispherical nested shells with ampules of 6LiH, 7LiH, and activation foils located 2.2, 5, 7.7, 12.6, 20, and 30 cm from the center. The Los Alamos Monte Carlo Neutron Photon Transport Code (MCNP) was used to calculate neutron transport through the 6LiD, tritium production in the ampules, and foil activation. The MCNP input model was three-dimensional and employed ENDF/B-V cross sections for transport, tritium production, and (where available) foil activation. The reanalyzed experimentally observed-to-calculated values of tritium production were 1.053 +- 2.1% in 6LiH and 0.999 +- 2.1% in 7LiH. The recalculated foil activation observed-to-calculated ratios were not generally improved over those reported in the original analysis

  10. Exploring contributions from incomplete fusion in $^{6,7}$Li+$^{209}$Bi and $^{6,7}$Li+$^{198}$Pt reactions

    Parkar, V V; Kailas, S

    2016-01-01

    We use the breakup absorption model to simultaneously describe the measured cross-sections of the Complete fusion (CF), Incomplete fusion (ICF), and Total fusion (TF) in nuclear reactions induced by weakly bound nuclei $^{6,7}$Li on $^{209}$Bi and $^{198}$Pt targets. The absorption cross-sections are calculated using the Continuum Discretized Coupled Channels (CDCC) method with different choices of short range imaginary potentials to get the ICF, CF and TF cross-sections. It is observed that the cross-sections for deuteron-ICF/deuteron-capture are of similar magnitude as the $\\alpha$-ICF/$\\alpha$-capture, in case of $^{6}$Li projectile, while the cross-sections for triton-ICF/triton-capture is more dominant than $\\alpha$-ICF/$\\alpha$-capture in case of $^{7}$Li projectile. Both these observations are also corroborated by the experimental data. The ratio of ICF to TF cross-sections, which defines the value of fusion suppression factor is found to be in agreement with the data available from the literature. The...

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

    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

  12. Mechanisms of emission of particles charged in 6Li + 6Li and 6Li + 10B reactions at low energies

    The lithium 6 nucleus is a projectile of interest to study nuclear reactions at low energy due to the possibility to obtain high heats of reaction, and to its structure which can play an important role in the projectile-target interaction. This research thesis focused on the study of two low-energy reactions provoked by lithium projectiles. These reactions are studied within the framework of the theoretical model of aggregates. The first part presents the experimental conditions of both reactions, reports the development and analysis of nuclear plates, and the transformation of a given type of particle histogram into a spectrum in the mass centre system. The next parts report the study of the 6Li + 6Li reaction (previous results, kinematic analysis, spectrum of secondary particles, theoretical analysis of results) and of the 6Li + 10B reaction (previous results, experimental results, study of the continuous spectrum of alpha particle, reaction mechanisms)

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

    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 lithium problem.

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

    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.

  15. Inelastic scattering and multinucleon transfer in 3,4He + 9Be reactions

    A study of inelastic scattering and multinucleon transfer reactions was performed by α and 3He beams on a 9Be target at energy about 50 MeV. Angular distributions of the differential cross sections for the 9Be(α, α)9Be*, 9Be(α, 3He)10Be, 9Be(α, t)10B, 9Be(3He, 6Li)6Li, and 9Be(3He, 6Be)6He reactions were measured. Experimental angular distributions of the differential cross sections for the ground state and a few low-lying states were analyzed in the framework of the optical model, coupled channels, and distorted-wave Born approximation. The information on the cluster structure of the reaction products was obtained. The analysis of the obtained spectroscopic factors was performed

  16. Feshbach resonances in fermionic 6Li

    Feshbach resonances in 6Li were experimentally studied and theoretically analyzed. In addition to two previously known s-wave resonances, three p-wave resonances were found. Four of these resonances are narrow and yield a precise value of the singlet scattering length. The position of the broad s-wave resonance near 83 mT is mostly sensitive to the triplet potential. It was previously determined in a molecule-dissociation experiment for which we, here, discuss systematic shifts

  17. Single-Proton Pickup Reaction of the Halo Nucleus 6He on a 9Be Target at 25 MeV/nucleon

    PANG Dan-Yang; LOU Jian-Ling; LU Fei; FAN Feng-Ying; A. Ozawa; Y. Yamaguchi; R. Kanungo; D. Fang; I. Tanihata; YE Yan-Lin; JIANG Dong-Xing; ZHENG Tao; LI Zhi-Huan; LI Xiang-Qing; GE Yu-Cheng; HUA Hui; WU Cui-E

    2007-01-01

    The inclusive differential cross sections of the 7 Li nucleus in a reaction induced by 6He on a 9Be target are measured at an incident energy of 25 MeV/nucleon. Finite-range distorted-wave Born approximation calculations suggest that these 7 Li particles are formed in a direct single-proton pickup reaction 9 Be(6 He, 7 Li)8 Li. The experimental data can be well reproduced by taking into account of the contributions of both the ground states and the first excited states of 7 Li and 8 Li.

  18. 6Li foil thermal neutron detector

    Ianakiev, Kiril D [Los Alamos National Laboratory; Swinhoe, Martyn T [Los Alamos National Laboratory; Favalli, Andrea [Los Alamos National Laboratory; Chung, Kiwhan [Los Alamos National Laboratory; Macarthur, Duncan W [Los Alamos National Laboratory

    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.

  19. A new mass value for 7Li

    Nagy, Sz; Suhonen, M; Schuch, R; Blaum, K; Björkhage, M; Bergström, I; 10.1103/PhysRevLett.96.163004

    2012-01-01

    A high-accuracy mass measurement of 7Li was performed with the Smiletrap Penning trap mass spectrometer via a cyclotron frequency comparison of Li3+ and H2+. A new atomic mass value of 7Li has been determined to be 7.016,003,425,6,(45)u with a relative uncertainty of 0.63 ppb. It has uncovered a discrepancy as large as 14 sigma (1.1 micro u) deviation relative to the literature value given in the Atomic-Mass Evaluation AME 2003. The importance of the improved and revised 7Li mass value, for calibration purposes in nuclear-charge radii and atomic mass measurements of the neutron halos 9Li and 11Li, is discussed.

  20. Enhanced cosmological 6Li abundance as a potential signature of residual dark matter annihilations

    Residual late-time dark matter particle annihilations during and after big-bang nucleosynthesis may alter the predicted cosmological abundances of the light elements. Within the constrained minimal supersymmetric extension of the standard model with a neutralino as the lightest supersymmetric particle, we find negligible effects on the abundances of deuterium, 3He, 4He, and 7Li predicted by homogeneous big-bang nucleosynthesis, but potentially a large enhancement in the predicted abundance of 6Li. This enhancement may be as much as 2 orders of magnitude in the focus-point WMAP strip and in the coannihilation and funnel regions for large tanβ for small m1/2, and the effect is still significant at large m1/2. However, the potential 6Li enhancement is negligible in the part of the coannihilation strip for tanβ=10 that survives the latest LHC constraints. A similar enhancement of the 6Li abundance may also be found in a model with common, nonuniversal Higgs masses (the NUHM1).

  1. Total kinetic energy distribution of fission fragments in 6,7Li + 238U reactions

    The shape and width of fission-fragment (FF) mass and kinetic energy distribution provides a lot of information on the fission reaction mechanism and the structure of the compound nucleus (CN), the fragments as well as the interacting nuclei. The shape of the mass distribution of the fission fragments for the actinides induced by the proton or neutron is known to change with the incident energy. At low energies, it shows a double humped distribution which changes slowly to a single humped distribution as energy increases. However, for a reaction involving a weakly bound projectile (i.e., 6Li + 232Th), a sharp change in the shape of the mass distribution with energy was observed. The sharp increase in the peak to valley ratio (P:V) in the fission-fragment mass distribution in 6Li + 232Th reaction by Itkis et al. and in 6,7Li + 238U reactions by Santra et al. was concluded to be due to the reduced energy transfer to the composite system caused by incomplete fusion (ICF) of alpha or deuteron/triton followed by fissions. Total Kinetic Energy (TKE) distribution of fission fragments is another important observable on which the effect of projectile breakup is not explored yet. In this contribution, the study of breakup/transfer effect on average TKE distribution for 6,7Li + 238U reactions is presented

  2. Reaction mechanism study of 7Li(7Li, 6He) reaction at above Coulomb barrier energies

    V V Parkar; V Jha; S Santra; B J Roy; K Ramachandran; A Shrivastava; K Mahata; A Chatterjee; S Kailas

    2009-02-01

    The elastic scattering and the 6He angular distributions were measured in 7Li + 7Li reaction at two energies, lab = 20 and 25 MeV. FRDWBA calculations have been performed to explain the measured 6He data. The calculations were very sensitive to the choice of the optical model potentials in entrance and exit channels. The one-step proton transfer was found to be the dominant reaction mechanism in 6He production.

  3. Resonances in the proton-6Li scattering

    The differential cross section and the analyzing power of the p+6Li scattering were measured in the laboratory energy range from 1.6 respectively 2.8 MeV to 10 MeV at 45 respectively 40 energies in full angular distributions. The data were subjected both to an analysis in the optical model which yielded already hints to resonance effects and to a comphrehensive scattering-phase analysis for L=0, 1, and 2 under inclusion of channel spin and orbital angular momentum mixings. The consistent description of all data required the assumption of broad resonance structures. An approximate parametrization by a Breit-Wigner formula allowed the estimation of the resonance parameters. (orig./HSI)

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

    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. (author)

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

    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.

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

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

    2016-01-01

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

  7. 3He(3H,γ)6Li

    The authors have calculated the 3He(3H,γ)6Li reaction rate at big bang temperatures based on a microscopic study in the framework of the Generator Coordinate Method. It is discussed whether 6Li could be made by 3He + 3H fusion in the early epoch of our universe

  8. $^{7}$Li abundances in halo stars testing stellar evolution models and the primordial $^{7}$Li abundance

    Chaboyer, B; Brian Chaboyer

    1994-01-01

    A large number of stellar evolution models with [Fe/H] = -2.3 and -3.3 have been calculated in order to determine the primordial .sup(7)Li abundance and to test current stellar evolution models by a comparison to the extensive database of Li abundances in extremely metal poor halo stars observed by Thorburn (1994). Standard models do a good job of fitting the observed Li abundances in stars hotter than 5600 K. They predict a primordial ^7Li abundance of log N(Li) = 2.24\\pm 0.03. Models which include microscopic diffusion predict a downward curvature in the .sup(7)Li destruction isochrones at hot temperatures which is not present in the observations. Thus, the observations clearly rule out models which include uninhibited microscopic diffusion of .sup(7)Li from the surface of the star. The [Fe/H] = -2.3 stellar models which include both diffusion and rotational mixing provide an excellent match to the observations. Both the plateau stars and the heavily depleted cool stars are well fit by these models. The rot...

  9. The evaluation of cross sections for n + 6Li reaction

    Neutron nuclear data of 6Li are important for fusion neutronics calculation. Therefore, the cross sections for n + 6Li reaction are evaluated in the energy range from 10-5 eV to 20 MeV. In the evaluation, 6Li(n, d+n)4He and 6Li(n, n+d)4He reactions are included. It is concluded that there is really only the second excited level (3.562 MeV) in the inelastic scattering, no assumed levels were taken into account. The evaluated data describe the real process of n + 6Li reactions and improve the existing evaluated libraries such as ENDF/B-6 and JENDL-3

  10. sup 3 He( sub 3 H,. gamma. ) sup 6 Li; Source of sup 6 Li production in the big bang

    Funck, C.; Langanke, K. (Inst. fur Theoretisch Physik I, Univ. Munster, D-4400 Munster (DE))

    1990-01-10

    The authors have calculated the {sup 3}He({sup 3}H,{gamma}){sup 6}Li reaction rate at big bang temperatures based on a microscopic study in the framework of the Generator Coordinate Method. It is discussed whether {sup 6}Li could be made by {sup 3}He + {sup 3}H fusion in the early epoch of our universe.

  11. Studies of the D state of 6Li using the FSU polarized 6Li Beam

    One way to quantify the D-state component of the wave function of a nucleus is by the quantity η, the ratio of the D- and S-state asymptotic normalization constants. Analyses of the analyzing powers from transfer reactions induced by polarized ions have been useful for the determination of η in the A=2-4 systems. In an effort to determine η for the d+α relative motion in 6Li we have measured analyzing powers for (6L rvec i,d) reactions on 58Ni and 40Ca at E(6Li)=34 and h;MeV. The experiments were performed at Florida State University using the Optically Pumped Polarized Lithium Ion Source. We compared the data with the results of well-constrained DWBA calculations assuming a direct α-particle transfer mechanism. With η the only free parameter in the calculations, a best fit to the tensor analyzing power data results in an average value of η=+0.0003±0.0009, much smaller than previous determinations. copyright 1999 American Institute of Physics

  12. Line shapes of prompt γ-ray from 7*Li produced in 10B(n,α)7*Li reaction

    Prompt γ-ray spectra of recoil 7*Li produced in the 10B(n,α)7*Li reaction were measured using neutron beam. The observed Doppler broadening energy spectra were satisfactorily reproduced by a simulation where the velocity degradation of 7*Li within its lifetime of 1.05x10-13 s was estimated using the LSS theory. Our successful line-shape analysis was applied to non-destructive state analysis of trace amounts of boron. (author)

  13. Effect of target deformation and projectile breakup in complete fusion of 6Li + 152Sm

    Nuclear reaction induced by weakly bound (stable or radioactive) nuclei is a subject of current experimental and theoretical interest. Measurements of fusion cross section involving loosely bound projectile 6Li and 9Be exist with different conclusion about the enhancement or suppression of fusion cross section. Recently we have measured the fusion cross section for 6Li + 144Sm, where it has been found that there is an enhancement of fusion cross section below the barrier in comparison with single BPM calculation, where as there is an overall suppression in fusion cross section as compared to CCFULL calculation in the entire energy range measured. With this motivation, we chose a deformed target, 152Sm, with β2 = 0.24 to compare with the results of 144Sm which is a spherical target. It will also be interesting to see effect of target deformation (enhancement) versus projectile breakup (suppression) specially at subbarrier energy

  14. Enhancement of the CP-odd effect in the nuclear electric dipole moment of $^6$Li

    Yamanaka, Nodoka

    2015-01-01

    We calculate for the first time the electric dipole moment (EDM) of the $^6$Li nucleus within the alpha + p + n three-body cluster model using the Gaussian expansion method, assuming the one meson exchange P, CP-odd nuclear forces. It is found that the EDM of the $^6$Li is 2 times more sensitive on the isovector pion exchange P, CP-odd nuclear force than the deuteron EDM, due to the CP-odd interaction between the nucleons and the alpha cluster. The $^9$Be EDM is also calculated in the same framework as an alpha + alpha + n three-body system. We also test the ab initio calculation of the EDM of the deuteron, $^3$H and $^3$He nuclei using the realistic Argonne $v18$ nuclear force. In the ab initio calculations, good agreements with previous studies are obtained. We finally discuss the prospects for the new physics beyond the standard model.

  15. Energy levels in (7Li) nucleus

    The energies of the normal-parity states and positive parity states in (7Li) nucleus are calculated, using many-particle nuclear shell-model, and the harmonic oscillator-wave-functions, over the residual interaction of the Gaussian from the Serber force. Spin-orbit interactions are neglected. The kinetic energy is introduced as a variant quantity, through the variation of the harmonic oscillator parameter (r0) (r02=h/mw). Finally, we separate the ''spurious'' states (one quantum excitations of the center of mass of the nucleus) by the effect of the operator (R-i), for the coordinate of the center of mass on the different wave-functions of the ground state-configurations. The calculations show that the energy of the positive-parity states, separated into two groups; the first in the energy region (10-20 Mev) and described by the symmetries (43), (421); and the second group in the energy region (26-46 Mev) and described by the symmetries (31), (3211). 9 tabs.; 3 figs.; 64 refs

  16. Prospective conceptual qualification of hybrid centrifugation/distillatory for {sup 6}LI nuclear fusion technology scaled supply demands; Calificacion conceptual prospectiva de centrifugador/destilador hibrido para produccion de {sup 6}Li a demanda de la tecnologia Nuclear Fusion

    Sedano, L.; Herranz, J. L.; Casado, J. L.; Castro, P.; Xiberta, J.

    2013-07-01

    The change in the demand for exploitation of lithium as a resource appears during the last decade, related to the development of the ion-Li batteries market and with the requirements of Nuclear Fusion fuels (deuterium and lithium) as coming energy option. A prospective analysis of synergistic demands of both markets, in its technical and in its economic aspects appears of prospective interest. The civil market {sup 6}Li/{sup 7}Li enrichment demand is analyzed. Specific technological developments permitting on-line production according to demand is discussed. A [centrifugation /thermal diffusion / combined distillation] technique is selected and qualified as technologically viable option for scaled production of litiated-forms. A conceptual design of a production plant is finally proposed according to the new technical capability.

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

    Efros, V D; Buki, A Yu

    2016-01-01

    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 alpha-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 alpha-particle. The experimental longitudinal sums in the range between 0.450 and 1.625 fm^{-1} are employed to perform comparison with those calculated in the framework of cluster models. Out of the mentioned experimental sums, those in the range between 0.750 and 1.000 fm^{-1} in the 6Li case ...

  18. Fusion around the barrier for 7Li + 12C

    A Mukherjee; M Dasgupta; D J Hinde; C R Morton; A C Berriman; R D Butt; J O Newton; H Timmers

    2001-07-01

    Fusion cross-sections for the 7Li + 12C reaction have been measured at energies above the Coulomb barrier by the direct detection of evaporation residues. The heavy evaporation residues with energies below 3 MeV could not be separated out from the -particles in the spectrum and hence their contribution was estimated using statistical model calculations. The present work indicates that suppression of fusion cross-sections due to the breakup of 7Li may not be significant for 7Li + 12C reaction at energies around the barrier.

  19. Contribution to the study of 8Be energy levels obtained during the reaction 6Li(d,α)α

    The reaction 6Li(d,α) is interpreted using the theory of Humblet and Rosenfeld. This theory is briefly reviewed and compared with that of Wigner. The intervention of the 4+ level, indicated in the study of the reaction 7Li(p,α), is suggested. A good fit to the experimental data is obtained assuming the level scheme (0+ 22.64 MeV), (4+ 22.82 MeV), (2+ 24.97 MeV). However the scheme proposed by Mani (22.5 MeV 2+; 24.0 MeV 0+; 25.2 MeV 2+) on the basis of the Wigner theory, cannot be rejected. (author)

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

    Devlin, Matthew J [Los Alamos National Laboratory; Taddeucci, Terence N [Los Alamos National Laboratory; Hale, Gerald M [Los Alamos National Laboratory; Haight, Robert C [Los Alamos National Laboratory; O' Donnell, Johhn M [Los Alamos National Laboratory

    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.

  1. Static and dynamic moments of the 7Li nucleus

    The data of Weller et al. (1985) on the tensor analysing powers for elastic and inelastic Coulomb scattering of aligned 7Li ions have been reanalyzed in order to obtain information on the values of the four 7Li moments Q, B(E2)↑, τ11 and τ12. It is shown that a single set of values, chosen primarily to be consistent with the value of Q measured by molecular techniques and the values of B(E2)↑ and τ12. required to fit unpolarized 7Li data, and also with the theoretical constraint τ11≅-[τ12], gives a good fit to the aligned 7Li data. 19 refs., 6 figs

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

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

  3. 6Li-doped silicate glass for thermal neutron shielding

    Glass formulations are described that contain high concentrations of 6Li and are suitable for use as thermal neutron shielding. One formulation contained 31 mol% of 6Li2O and 69 mol% of SiO2. Studies were performed on a second formulation that contained as much as 37 mol% of 6Li2O and 59 mol% of SiO2, with 4 mol% Al2O3 added to prevent crystallization at such high 6Li2O concentrations. These lithium silicate glasses can be formed into a variety of shapes using conventional glass fabrication techniques. Examples include flat plates, disks, hollow cylinders, and other more complex geometries. Both in-beam and in-core experiments have been performed to study the use and durability of Li silicate glasses. In-core experiments show the glass can withstand the intense radiation fields near the core of a reactor. The neutron attenuation of the glasses used in these studies was 90%/mm. In-beam studies show that the glass is effective for reducing the gamma-ray and neutron fields near experiments. ((orig.))

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

    Pandey Bhawna

    2015-01-01

    Full Text Available 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, d56Fe*] 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, p55Mn reaction by surrogate method.

  5. 7Li NMR studies of lithium transport in human erythrocytes

    Lithium transport in human erythrocytes was investigated by 7Li NMR spectroscopy. The intra- and extracellular pools of Li+ were distinguished by the addition to the red cell suspension of a cell-impermeable shift reagent, dysprosium(III) triphosphate. It was found that, for therapeutic levels of lithium used in the US (where the typical plasma (Li+) concentration range is 0.5-1.2 mM), a shift reagent concentration of 3 mM is sufficient to achieve clear chemical shift separation between the two 7Li+ NMR resonances. Despite competition between Li+ and other mono- and divalent cations for the shift reagent, the intra and extracellular 7Li+ NMR signals are clearly separated (approximately 3 ppM) even in the presence of physiologically relevant concentrations of Na+, K+, Mg2+, and Ca2+. Addition of an ionophore, monesin, to a K+-only RBC (red blood cell) suspension induces passive Li+ transport, which can be monitored by following the relative intensities of the two 7Li+ resonances. It is concluded that the 7Li NMR method is suitable for the noninvasive study of Li+ transport in human erythrocytes and that it shows great promise as a tool for the investigation of the bioinorganic chemistry of lithium. 24 references, 3 figures, 1 table

  6. Unusual Threshold Anomaly in the 6Li+208Pb System

    ZHANG Chun-Lei; JIA Hui-Ming; WU Zhen-Dong; XU Xin-Xing; BAI Chun-Lin; ZHANG Huan-Qiao; LIN Cheng-Jian; RUAN Ming; LIU Zu-Hua; YANG Feng; WU Xiu-Kun; ZHOU Ping; AN Guang-Peng

    2006-01-01

    @@ The angular distributions of elastic scattering for the 6Li +208Pb system have been measured at several energies around the Coulomb barrier. The parameters of optical potential are extracted by means of a phenomenological optical model analysis. It is found that the real and imaginal potentials show a pronounced energy dependence.The behaviour of the potential at the nearly especially sub-barrier energies in the 6Li+208Pb system is quite different from the results of some previous reports observed in other systems, such as 19 F +208 Pb and 16 O+208 Pb.This unusual threshold phenomenon indicates that breakup channel is strongly coupled with the elastic channel and has obvious effects on optical potential.

  7. Lowest excitation energy of 9Be.

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

    2007-07-27

    Variational calculations employing explicitly correlated Gaussian functions and explicitly including the nuclear motion [i.e., without assuming the Born-Oppenheimer (BO) approximation] have been performed to determine the lowest singlet transition energy in the 9Be atom. The non-BO wave functions were used to calculate the alpha2 relativistic corrections (alpha=1/137.035,999,679). With those corrections and with the alpha3 and alpha4 QED corrections determined previously by others, we obtained 54,677.35 cm(-1) for the 3(1)S-->2(1)S transition energy. This result falls within the error bracket for the experimental transition of 54,677.26(10) cm(-1). This is the first time an electronic transition of Be has been calculated from first principles with the experimental accuracy. PMID:17678358

  8. Study of the {sup 6}He+{sup 9}Be elastic scattering at low energies

    Pires, K.C.C.; Lichtenthaeler, R.; Lepine-Szily, A.; Guimaraes, V.; Faria, P.N.; Crema, E.; Barioni, A.; Mendes Junior, V.; Morcelle, V.; Morais, M.C.; Pampa Condori, R.; Huiza, J.F.P. [Universidade de Sao Paulo (IF/USP), SP (Brazil). lnst. de Fisica. Dept. de Fisica Nuclear; Moro, A.M.; Rodriguez-Gallardo, M. [University of Seville (Sri Lanka). Dept. of Atomic, Molecular and Nuclear Physics; Assuncao, M. [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil); Shorto, J.M.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP) Sao Paulo, SP (Brazil); Mukherjee, S. [University of Baroda, Vadodara (India). Faculty of Science. Dept. of Physics

    2011-07-01

    New data of the {sup 6}He+{sup 9}Be elastic scattering at E{sub lab}=16.2MeV and 21.3MeV have been measured. A very large reaction cross section has been previously observed in the collision of {sup 6}He with medium and heavy mass targets, which has been attributed to high 6He breakup probability in the strong Coulomb + nuclear interaction. More recently the importance of neutron transfer reactions between projectile and target has been pointed out. The main goal of the present experiment is to investigate the halo nature of the {sup 6}He nucleus by its interaction with a light target. The experiment has been performed at the Pelletron Laboratory of the Institute of Physics of the University of Sao Paulo, Brazil, using the RIBRAS facility. The RIBRAS system consists of two superconducting solenoids used to focus and select the radioactive secondary beam. The {sup 6}He secondary beam was produced by the {sup 9}Be({sup 7}Li,{sup 6}He) reaction with a {sup 7}Li primary beam of 200nA. The detection system consisted of four {Delta}E-E Silicon telescopes, with 20{mu}m and 1000{mu}m thickness respectively, which allow to separate the {sup 6}He particles from the {sup 7}Li, {sup 4}He, and light particles contaminants. The {sup 6}He+{sup 9}Be angular distributions have been analyzed with optical model, Coupled Channels (CC) and Continuum Discretized Coupled Channels (CDCC) calculations. The comparison between the experimental data and the CDCC calculations allow us to conclude that the breakup of the projectile via the coupling to the {sup 6}He 2{sup +} resonance is very important to reproduce the data. In addition, we studied the effect of excitation of the {sup 9}Be target explicitly by a CC calculation, using a collective model to describe the excitation of the first low lying states of {sup 9}Be. We found that the coupling to these states significantly affects the elastic scattering. From this analysis it was possible to obtain the total reaction cross section which was

  9. Feshbach resonances in mixtures of 6Li and 40K

    We report on the measurement of Feshbach resonances in Fermi-Fermi mixtures. For this purpose we have created an ultracold mixture of the fermionic alkali isotopes 6Li and 40K in an optical dipole trap. In the same trap we have realized a three-component degenerate spin mixture of 40K -atoms at T 0.3TF. To create the mixture we start by loading a two-species magneto-optical trap (MOT) from two separate 2D-MOT sources. We realized for the first time a 2D-MOT source for lithium, yielding a large cold flux of up to 109 s-1. The mixture is then captured in an optically-plugged magnetic quadrupole trap. After sympathetic cooling of 6Li by 40K to T∝10μK the mixture is loaded into optical tweezers. The mixture is optically transported over a distance of 21.5 cm into a science cell where we measure Feshbach resonances using magnetic field coils designed for high homogeneity. We report on our progress measuring the width of Feshbach resonances in 6Li -40K mixtures and locating resonances in mixtures of 40K.

  10. 9Be(d,n)10B-based neutron sources for BNCT

    In the frame of accelerator-based BNCT, the 9Be(d,n)10B reaction was investigated as a possible source of epithermal neutrons. In order to determine the configuration in terms of bombarding energy, target thickness and Beam Shaping Assembly (BSA) design that results in the best possible beam quality, a systematic optimization study was carried out. From this study, the optimal configuration resulted in tumor doses ≥40 Gy-Eq, with a maximum value of 51 Gy-Eq at a depth of about 2.7 cm, in a 60 min treatment. The optimal configuration was considered for the treatment planning assessment of a real Glioblastoma Multiforme case. From this, the resulted dose performances were comparable to those obtained with an optimized 7Li(p,n)-based neutron source, under identical conditions and subjected to the same clinical protocol. - Highlights: • Study of the 9Be(d,n)10B reaction as a source of epithermal neutrons for BNCT. • Evaluation of the optimal configuration of target thickness, deuteron energy and BSA design. • Computational dose assessment for brain tumor treatments using the MCNP code. • Treatment planning assessment of a particular clinical Glioblastoma Multiforme case. • Dose performances were comparable to those obtained with an optimized 7Li(p,n)-based source

  11. Investigation of α-cluster states in 13C via the (6Li,d) reaction

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

    2010-01-01

    The 9Be(6Li,d)13C reaction was used to investigate possible α-cluster states in 13C. The reaction was measured at 25.5 MeV incident energy, employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion detection technique. Ten out of sixteen known levels of 13C, up to 11 MeV of excitation, were observed and, due to the much improved energy resolution of 50 keV, at least three doublets could be resolved. This work presents a preliminary analysis of five of the most intensely populated states, also in comparison with the results of former transfer studies.

  12. Resonant and nonresonant Coulomb break up of 6Li

    The resonant and nonresonant cross section for break up of 6Li in the Coulomb field of a heavy nucleus is theoretically studied on the basis of a DWBA approach and analysed in view of a possible experimental access to electromagnetic transition matrix elements between the ground state of the projectile and α+d continuum states at small relative energies. The calculation explicitly uses some simplifications appearing in the particular case of quadrupole transitions which dominate the considered case. Various sensitivities of the cross sections are discussed. (orig.)

  13. Alpha resonances excited in13C and 16O by the (6Li,d) reaction

    The investigation of a cluster correlations is the main purpose of the research program in progress, focusing on xα and xα + ν nuclei. The reactions 9Be(6Li,d)13C and 12C(6Li,d)16O measured at the bombarding energy of 25.5 MeV, employing the São Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion technique, were used to enhance a resonant states in 13C and 16O. An energy resolution of 20-40 keV was obtained and up to 15.5 MeV of excitation, in both nuclei, several resonances not previously measured, revealing a quasi-bound behavior, were detected. Focusing on 13C, the experimental angular distributions associated with the resonances just above the 9Be + α and 3α + ν thresholds[2] were compared with DWBA predictions. Seen at the 9Be + α threshold, a pure L = 4 transfer is indicated for each transition to the known 7/2- and (5/2-) states instead of L = 2 obtained in the former fit[3] to the integrated contribution. The narrow resonance detected at 12.3 MeV of excitation, close to the 3α + ν threshold and populated by an L = 2 transfer, reveals a 9Be(G.S.) + α component for the 1/2- cluster state candidate, 12C(Hoyle) + ν, at this threshold. Considering the 16O, states were revealed around the 4α threshold (14.44 MeV) and the upper limit resonant widths were obtained. The resonance at 14.670 MeV was reached by an L = 5 direct transfer in agreement with the 5- attribution. The upper limit width obtained, near the experimental resolution, is inconsistent with the usual experimental[4,5] and theoretical[6-7] interpretations of the 5- state revealed as a broad resonance in the same excitation energy region and considered to be a member of the Kπ = 0- band with the 12C(G.S.) + α structure. In the same excitation energy range, a narrow 5- resonance decaying to 12C(2+ 1), was predicted by Suzuki using a comprehensive semi-microscopic alpha cluster calculation, in agreement with the present findings. Haigh et al., in the investigation of the 12C

  14. Spontaneous Lithium Transportation via LiMn2O4/Electrolyte Interface Studied by 6/7Li Solid-State Nuclear Magnetic Resonance

    Highlights: • Spontaneous Li+ exchange between LiMn2O4 and LiPF6-based electrolyte was studied. • 6/7Li solid-state NMR techniques were developed to examine the exchange. • The exchange occurs for stoichiometric LiMn2O4 but not in Li-excess LiMn2O4. • The exchange was approximated by the 1st-order reaction with the rate of 0.024 min-1. • The suppression in Li-excess LiMn2O4 was ascribed to excess amount of Mn4+. - Abstract: Lithium transportation across the interface of LiMn2O4/LiPF6-based electrolyte was studied by 6/7Li solid-state NMR with 6Li-enriched LiPF6. For almost stoichiometric LiMn2O4, we show that exchange of lithium ions occurs across an electrolyte/electrode interface just by immersing LiMn2O4 powder into LiPF6-based electrolyte, while such transportation is suppressed in Li-excess LiMn2O4. The exchange was approximated by the 1st-order reaction, and the rate was estimated from the 6Li/7Li intensities to be 0.024 min−1 at room temperature. The lithium ions penetrated into the surface of a LiMn2O4 particle reach to the core with a time scale of a few hours at room temperature. The suppression of the exchange in Li-excess LiMn2O4 was ascribed to the presence of excess amount of Mn4+

  15. Measurement of multinucleon transfer cross-sections in 58Ni,56Fe(12C, ); : 13,11C, 11,10B, 10,9,7Be, 8Be.s. and 7,6Li at (12C) = 60 MeV

    B J Roy; A Parmar; T Nandi; Biraja Mohanty; M Oswal; Sunil Kumar; A Jhingan; V Jha; D C Biswas

    2016-01-01

    Cross-sections for one- and multinucleon transfer reactions, namely, 58Ni(12C, 13C), 58Ni(12C, 11C), 58Ni(12C, 11B), 58Ni(12C, 10B), 58Ni(12C, 10Be), 58Ni(12C, 9Be), 58Ni(12C, 8Be.s.), 58Ni(12C, 7Be), 58Ni(12C, 7Li) and 58Ni(12C, 6Li) have been measured at an incident energy of 60 MeV. The reaction cross-section for the corresponding transfer channels in the system 12C+56Fe have also been measured under the same kinematical conditions. Angular distribution of the elastic scattering cross-section is measured at 60 MeV. The measured elastic scattering angular distributions for these two systems have been analysed using the optical model search code SFRESCO and the potential parameters are extracted. The multinucleon transfer data are analysed to obtain cross-section dependence on the number of nucleons transferred and on the ground state -values. The transfer probabilities for multinucleon stripping are extracted. A detailed comparison in the multiparticle stripping and elastic scattering cross-sections between these two systems are made to understand the mechanism of multinucleon transfer and possible role of two extra protons in 58Ni target nucleus as compared to the 56Fe core.

  16. Ab initio no-core solutions for $^6$Li

    Shin, Ik Jae; Maris, Pieter; Vary, James P; Forssén, Christian; Rotureau, Jimmy; Michel, Nicolas

    2016-01-01

    We solve for properties of $^6$Li in the ab initio No-Core Full Configuration approach and we separately solve for its ground state and $J^{\\pi}=2_{2}^{+}$ resonance with the Gamow Shell Model in the Berggren basis. We employ both the JISP16 and chiral NNLO$_{opt}$ realistic nucleon-nucleon interactions and investigate the ground state energy, excitation energies, point proton root-mean-square radius and a suite of electroweak observables. We also extend and test methods to extrapolate the ground state energy, point proton root-mean-square radius, and electric quadrupole moment. We attain improved estimates of these observables in the No-Core Full Configuration approach by using basis spaces up through N$_{max}$=18 that enable more definitive comparisons with experiment. Using the Density Matrix Renormalization Group approach with the JISP16 interaction, we find that we can significantly improve the convergence of the Gamow Shell Model treatment of the $^6$Li ground state and $J^{\\pi}=2_{2}^{+}$ resonance by ...

  17. Photoassociative creation of ultracold heteronuclear 6Li40K* molecules

    Ridinger, Armin; Salez, Thomas; Fernandes, Diogo Rio; Bouloufa, Nadia; Dulieu, Olivier; Salomon, Christophe; Chevy, Frederic

    2011-01-01

    We investigate the formation of weakly bound, electronically excited, heteronuclear 6Li40K* molecules by single-photon photoassociation in a magneto-optical trap. We performed trap loss spectroscopy within a range of 325 GHz below the Li(2S_(1/2))+K(4P_(3/2)) and Li(2S_(1/2))+K(4P_(1/2)) asymptotic states and observed more than 60 resonances, which we identify as rovibrational levels of 7 of 8 attractive long-range molecular potentials. The long-range dispersion coefficients and rotational constants are derived. We find large molecule formation rates of up to ~3.5x10^7s^(-1), which are shown to be comparable to those for homonuclear 40K_2*. Using a theoretical model we infer decay rates to the deeply bound electronic ground-state vibrational level X^1\\Sigma^+(v'=3) of ~5x10^4s^(-1). Our results pave the way for the production of ultracold bosonic ground-state 6Li40K molecules which exhibit a large intrinsic permanent electric dipole moment.

  18. ZnS/6Li scintillation material as an alternative to 6Li-glass scintillators for neutron detection in time focusing geometry

    As an alternative of using 6Li-glass scintillators for neutron detection in time focusing geometry the effects of ZnS/6Li scintillation material on the measuring efficiency will be discussed on example of the high resolution RTOF device FSS at GKSS Geesthacht, Germany. ((orig.))

  19. Creation of $^{7}$Li and destruction of $^{3}$He, $^{9}$Be, $^{10}$B and $^{11}$B in low mass red giants, due to deep circulation

    Boothroyd, A I

    1999-01-01

    It has been demonstrated that Li-7 can be created in low mass red giant stars, via extra deep mixing and the associated "cool bottom processing" (CBP) (namely, via the same process which is usually invoked on the red giant branch [RGB] to explain the observed anomalous C-13 enhancements, beyond that resulting from first dredge-up). This Li-7 production can account for the recent discovery of surprisingly high lithium abundances in some low mass red giants. Lithium is created via the Cameron-Fowler mechanism; the amount of Li-7 produced depends critically on the details of the extra mixing mechanism (mixing speeds, geometry, episodicity), but is independent of the previous Li-7 history of the star. If the deep circulation is a long-lived, continuous process, lithium-rich RGB stars should be completely devoid of beryllium and boron. If it occurs in short-lived episodes, higher Li-7 abundances might result, and beryllium and boron might be only partially destroyed. On the asymptotic giant branch, CBP in low mass...

  20. Neutron-induced background by an {alpha}-beam incident on a deuterium gas target and its implications for the study of the {sup 2}H({alpha},{gamma}){sup 6}Li reaction at LUNA

    Anders, M.; Bemmerer, D.; Elekes, Z.; Marta, M. [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden (Germany); Trezzi, D.; Mazzocchi, C. [INFN, Sezione di Milano, Milano (Italy); Bellini, A.; Costantini, H.; Corvisiero, P.; Lemut, A.; Prati, P. [Universita di Genova (Italy); INFN, Sezione di Genova, Dipartimento di Fisica, Genova (Italy); Aliotta, M.; Davinson, T.; Scott, D. [University of Edinburgh, SUPA, School of Physics and Astronomy, Edinburgh (United Kingdom); Broggini, C.; Caciolli, A.; Erhard, M.; Menegazzo, R.; Rossi Alvarez, C. [INFN, Sezione di Padova, Padova (Italy); Formicola, A.; Junker, M. [Laboratori Nazionali del Gran Sasso, INFN, Assergi (Italy); Fueloep, Zs.; Gyuerky, G.; Somorjai, E.; Szuecs, T. [Institute of Nuclear Research (ATOMKI), Debrecen (Hungary); Gervino, G. [Universita di Torino (Italy); INFN, Dipartimento di Fisica Sperimentale, Torino (Italy); Guglielmetti, A. [INFN, Sezione di Milano, Milano (Italy); Universita degli Studi di Milano, Milano (Italy); Gustavino, C. [INFN, Sezione di Roma ' ' La Sapienza' ' , Roma (Italy); Straniero, O. [INFN, Sezione di Napoli, Napoli (Italy); Osservatorio Astronomico di Collurania, Teramo (Italy); Collaboration: LUNA Collaboration

    2013-02-15

    The production of the stable isotope {sup 6}Li in standard Big Bang nucleosynthesis has recently attracted much interest. Recent observations in metal-poor stars suggest that a cosmological {sup 6}Li plateau may exist. If true, this plateau would come in addition to the well-known Spite plateau of {sup 7}Li abundances and would point to a predominantly primordial origin of {sup 6}Li, contrary to the results of standard Big Bang nucleosynthesis calculations. Therefore, the nuclear physics underlying Big Bang {sup 6}Li production must be revisited. The main production channel for {sup 6}Li in the Big Bang is the {sup 2}H({alpha},{gamma}){sup 6}Li 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 {alpha}-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 {sup 2}H(d,n){sup 3}He reaction. Due to the ultra-low laboratory neutron background at LUNA, the effect of this weak flux of 2-3 MeV neutrons on well-shielded high-purity germanium detectors has been studied in detail. Data have been taken at 280 and 400keV {alpha}-beam energy and for comparison also using an americium-beryllium neutron source. (orig.)

  1. Neutron spectrum measurements in CFRMF by 6Li spectrometry

    The neutron energy spectrum of the Couples Fast Reactivity Measurements Facility (CFRMF) has been measured by the 6Li(n,α)t spectrometry technique between the energies of 10 keV and 8 MeV. These measurements were made in order to improve the knowledge of this benchmark neutron field as related to dosimetry and other integral cross sections. Energy spectra of both the α + t and t responses were obtained simultaneously using two-parameter multichannel pulse height analysis. Spectrometers of different design and resolution characteristics were applied. The data were reduced using recently evaluated cross section information. The results are compared with the neutron spectrum calculated using recently evaluated cross section information. (author)

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

    Armstrong, Jeremy; Sakharuk, Alexander; Zelevinsky, Vladimir

    2007-10-01

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

  3. 6Li electromagnetic form factors and phenomenological cluster models

    The longitudinal form factors of the ground and 2.18 MeV (3+, T = 0) states, and the transverse form factors of the 3.56 MeV (0+, T = 1) and 5.37 MeV (2+, T = 1) states of 6Li are compared with the predictions based on fully antisymmetrized α-d and t-tau cluster models. The longitudinal form factors are adequately described by the α-d model, but the transverse form factors seem to be more consistent with a t-tau model which is close to the shell-model limit. Estimates are made for the ground state t and α spectroscopic factors. The 3.56 MeV M1 transition current density is calculated for both models and compared with experiment. (Auth.)

  4. Classical and potential descriptions of 9Be + 28Si and 9Be + 40Ca elastic scattering cross sections at E(9Be) = 45 and 60 MeV

    The elastic scattering angular distributions for 9Be + 28Si and 9Be + 40 0 Ca have been measured at 9Be bombarding energies of 45 and 60 over an angular range in which sigma/sigmasub(R) varied from 1 (i.e. Rutherford scattering) to values 9Be appears to exhibit somewhat different behaviour from both the lighter projectiles such as p and α and from its heavier neighbours such as 12C and 16O

  5. Spectator invariance test in the study of the Trojan Horse Method 6,7Li fusion reactions via the Trojan Horse Method

    Li C.

    2011-10-01

    Full Text Available Fusion reactions play a crucial role for several astrophysical scenarios. At the low energies typical of such environments direct measurements of reaction cross sections are very difficult, and even sometimes impossible. In such cases the use of indirect methods can give a substantial help. The Trojan Horse Method (THM is based on the quasi-free break-up of a nucleus, which can be described in terms of a cluster structure. In such applications the independence of THM results with different break-up schemes, was tested using the quasi free3 He(6Li,ααH and 3He(7Li,αα2H reactions. Results were then compared with the direct behaviours obtained from available data as well as with the cross sections extracted from previous indirect investigations of the same binary reactions using a different nuclide as a Trojan Horse nucleus.

  6. Towards 6Li-40K ground state molecules

    The production of a quantum gas with strong long - range dipolar interactions is a major scientific goal in the research field of ultracold gases. In their ro - vibrational ground state Li-K dimers possess a large permanent dipole moment, which could possibly be exploited for the realization of such a quantum gas. A production of these molecules can be achieved by the association of Li and K at a Feshbach resonance, followed by a coherent state transfer. In this thesis, detailed theoretical an experimental preparations to achieve state transfer by means of Stimulated Raman Adiabatic Passage (STIRAP) are described. The theoretical preparations focus on the selection of an electronically excited molecular state that is suitable for STIRAP transfer. In this context, molecular transition dipole moments for both transitions involved in STIRAP transfer are predicted for the first time. This is achieved by the calculation of Franck-Condon factors and a determination of the state in which the 6Li-40K Feshbach molecules are produced. The calculations show that state transfer by use of a single STIRAP sequence is experimentally very well feasible. Further, the optical wavelengths that are needed to address the selected states are calculated. The high accuracy of the data will allow to carry out the molecular spectroscopy in a fast and efficient manner. Further, only a comparatively narrow wavelength tuneability of the spectroscopy lasers is needed. The most suitable Feshbach resonance for the production of 6Li-40K molecules at experimentally manageable magnetic field strengths is occurring at 155 G. Experimentally, this resonance is investigated by means of cross-dimensional relaxation. The application of the technique at various magnetic field strengths in the vicinity of the 155 G Feshbach resonance allows a determination of the resonance position and width with so far unreached precision. This reveals the production of molecules on the atomic side of the resonance

  7. Spectator invariance test in the study of the 6,7Li fusion reactions via the Trojan Horse Method

    Fusion reactions play a crucial role for several astrophysical scenarios. At the low energies typical of such environments direct measurements of reaction cross sections are very difficult, and even sometimes impossible. In such cases the use of indirect methods can give a substantial help. The Trojan Horse Method (THM) is based on the quasi-free break-up of a nucleus, which can be described in terms of a cluster structure. In such applications the independence of THM results with different break-up schemes, was tested using the quasi free 3He(6Li,αα)H and 3He(7Li,αα)2H reactions. Results were then compared with the direct behaviours obtained from available data as well as with the cross sections extracted from previous indirect investigations of the same binary reactions using a different nuclide as a Trojan Horse nucleus. We conclude that the PWIA (Plane Wave Impulse Approximation) is valid in both cases and that the use of a different spectator particle does not influence the THM result

  8. Detection of the inverse pion electroproduction on 7Li nuclei

    The inverse pion electroproduction process on 7Li nucleus, π++7Li→e++e-+X, at the pion kinetic energy of 380 MeV has been detected. The missing mass distribution of the process events is described well assuming that approximately one half of the detected events belongs to the reaction channel producing 7Be nucleus either in the ground state (7Be) or in the excited state (7Be*): π++7Li→e++e-+7Be(7Be*). For this reaction the differential cross section for the electron and positron energies above 70 MeV, for the particles emitted under an angle of about 65 deg in l. s., is d2σ/dΩ2=(1.3+-0.3)x10-32 cm2/sr2

  9. Development of {sup 6}LiF thermal neutron shield for PGNAA

    Kim, M. S.; Park, J. H.; Hong, K. W.; Jun, B. J. [KAERI, Taejon (Korea, Republic of); Bun, S. H.; Choi, H. D. [Seoul National Univ., Seoul (Korea, Republic of)

    2001-05-01

    The {sup 6}LiF tile which will be utilized as the neutron shield of the gamma ray detector at the prompt gamma neutron activation analysis facility of KAERI-HANARO is developed. The {sup 6}LiF powder is obtained by the reaction of hydrofluoric acid with the {sup 6}Li{sub 2}CO{sub 3} powder, and the yield of the {sup 6}LiF is 86% of the theoretical value. In order to fabricate the stable tile from toxic and irritant LiF powder, the optimum sintering procedure is developed using the LiF powder with naturally abundant {sup 6}Li. The sintering temperature is 720 .deg. C, and the heating rate is 120 .deg. C/h. The preliminary heating process at 500 .deg. C is added in fabricating the {sup 6}LiF tile. The density of fabricated LiF tile is 2.4{approx}2.5 g/cm{sup 3}, and it is above 90% of theoretical density. The density of fabricated {sup 6}LiF tile is 2.25 g/cm{sup 3}, and the neutron transmission rate is below 10{sup -8}, so the thermal neutron transmission is negligible. Therefore, the tile is confirmed to be useful for PGNAA facility.

  10. Measurement of tritium production rates in a multi-layer breeding blanket mock-up with 6Li-enriched Li2TiO3 and D-T neutrons

    Experiments with breeding blanket mock-ups composed of layers of beryllium, ferritic steel F82H and 6Li enriched lithium titanate, Li2TiO3, are currently under investigation at Fusion Neutronics Source (FNS) of JAERI. Pellets of Li2TiO3 and Li2CO3 enriched to the proper 6Li concentration were used as detectors inside the tritium breeding layer. Additional detectors containing 32S and 35C1 were applied to estimate the tritium production due to 6Li and 7Li experimentally. After irradiation, the pellets were dissolved and the tritium activity in the sample solution was measured by liquid scintillation counting. A method for measuring the tritium production directly in lithium titanate was developed. The experimental values were compared with calculations based on the Monte Carlo code MCNP-4C, the continuous transport library fsxlb33 derived from the new neutron cross section evaluation JENDL-3.3 and the actx1 dosimetry file from FENDL-2. The calculations tend to overestimate the TPR similar to previous integral experiments with clean beryllium assemblies

  11. Measurement of cross section ratios of anti sigmasub(na)(sup(10)B)/ssigmasub(f)(sup(235)U) and anti sigmasub(n,a)(sup(6)Li)sup(235)U in fast neutron spectrum

    The method of measurements of cross section ratios of (n, d) reactions on 10B and 6Li isotopes and cross section of 235U fission in fast neutron spectrum with the help of solid state track detectors is proposed. The method is based on detection of d-particles produced in the reaction H1 H0B(N]7Li and 6Li(n, d)3H with the help of track detectors while artificial mica-fluorophlogopit has served as the detector of fission fragments. The conducted investigations have shown that the meanings of anti σsub(n, a) (6Li)/σsub(f)(sup(235U) and σsub(n5)) (sup(10)B/σsub(f) (sup(235)U) in the cells of fast reactors can be measured by the present methods with approximately 3% error. The attenuators of d-particle energy are needed to increase the accuracy of σsub(n, d)(Li)/σsub(f)(sup(235)U) measurement. The attenuators are placed between the source and the detector to shift the a-particle energy to the side of lower energies in the range where the efficiency of d-particle detection retains constant meaning

  12. Electroexcitation of the 0+ (3.562 MeV) level of 6Li and its application to the reaction 6Li(γ,π+)6He

    The M1 form factor for the 0+ (3.562 MeV, T=1) level in 6Li has been measured in the momentum transfer range q=0.26-1.15 fm-1. The radiative width is found to be GAMMAsub(γ0)=8.16+-0.19eV by extrapolation to the photon point. Phenomenological configuration amplitudes have been obtained for the ground and 3.562 MeV level, and it is shown that the 1p harmonic oscillator radial wave functions do not give a good description of the inelastic form factor. The results have been applied to the reaction 6Li(γ,π+)6He near threshold. The theoretical cross section is 24% higher than the data. The muon capture rate in 6Li and Fsub(A)(0) are also evaluated. (Auth.)

  13. Characterization of {sup 6}LiF:Mg,Cu,P (TLD-600 H) estimate of E, b and s parameters

    Andres, P. A., E-mail: andresp@cab.cnea.gov.ar [Centro Atomico Bariloche, Division Proteccion Radiologica / CNEA, Av. E. Bustillo Km 9.5, R8402AGP San Carlos de Bariloche (Argentina)

    2015-10-15

    LiF:Mg,Cu,P dosemeters are useful for low-dose measurements because of its high sensitivity compared to the LiF:Mg,Ti dosemeters. {sup 7}LiF:Mg,Cu,P have been used for environmental dosimetry in Bariloche Atomic Centre for almost a decade. Since {sup 6}LiF:Mg,Cu,P dosemeters were intended to be used for X ray diagnosis dosimetry in neonatology, they had to be characterized first. The main goal of measuring and analyzing Tl glow curves is the extraction of some parameters that can be used to describe the Tl process in the material. This job focused on the estimation of the activation energy E for the Tl traps, the frequency factor s and the order of kinetics b of the Tl process. Furthermore, the most appropriate time-temperature profile (Ttp) was determined as well as the annealing temperature and time, which resulted being 240 degrees C for 10 minutes. The Ttp used was 140 degrees C for 10 seconds, a heating rate of 20/s until 240 degrees C, remaining at this temperature for 20 seconds, and then an exponential cooling until 50 degrees C. After applying the whole glow-peak method for different orders of kinetic, and the Kitis equation assuming a first order kinetics, the values obtained were: E = (1.066 ± 0.025) eV, as a weighted average of both methods, and a frequency factor s = (3.57 ± 1.56) E-10 s{sup -1} again as a weighted average of both methods. In both cases a first order kinetics (b = 1) was assumed. The dosemeters were irradiated with a calibrated {sup 137}Cs source and read with a Harshaw TLD{sup TM} Model 3500 reader resulting in a minimum detectable dose of about 20 μGy. (Author)

  14. Direct measurement of the spin-dependent capture and scattering of slow neutrons by 6Li

    The spin-dependent capture cross section sigma/sup c//sub +/-sigma/sup c//sub -/ of slow neutrons (lambda = 1.074 A) by 6Li has been determined from the flipping ratio of a transmitted polarized neutron beam as a function of 6Li polarization. We used two methods, one of which also enabled us to measure the spin-dependent scattering length b/sub +/-b/sub -/ of 6Li. We find sigma/sub +//sup c/-sigma/sub -//sup c/ = -1170 +- 50 b and b/sub +/-b/sub -/ = (-0.38 +- 0.05) x 10-12 cm

  15. Effect of the breakup process on the direct reaction with a 6Li projectile

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

  16. Spin-dipole excitations of 6Li in charged pion photoproduction

    In the framework of bound shell model the photoproduction cross sections of charged pions on 6Li are calculated when spin-isospin dipole resonance is excited. It is shown that the transition strenqth concentrates in several energy regions. Such a gross-structure of the excitation spectrum is gaverned by the confiqurational splittinq of the resonance. The excitation spectrum in 6Li(γ, π)-reaction is compared with the 6Li(π, γ), (e, e') and (n, p) reaction spe;tra where spin-isospin transitions are dominating too

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

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

    Naqvi, A A; Nagadi, M M

    2005-03-01

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

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

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

  20. Study of fusion barrier distribution from quasielastic scattering for 6,7Li + 197Au systems

    Earlier we have reported breakup and fusion excitation function measurements in 6,7Li + 197Au systems. In this paper we present the fusion barrier distribution from QEL at backward angles for the same systems, namely, 6,7Li + 197Au

  1. Determination of nuclear reduced transition probabilities by 7Li ion induced Coulomb excitation

    Recently the authors observed that the first excited state of 7Li nucleus was excited in 7Li ion-Cu collision in the energy range 4.9 to 11.9 MeV, and the excitation process was via Coulomb excitation. By using the well known B (E2; g.s. 3-/2 - 478 keV, 1-/2) value of 7Li nucleus and the 7Li induced Coulomb excitation yields of both 7Li projectile and targets, the authors determined the reduced transition probabilities for low-lying states of some medium weight nuclei. The reduced transition probabilities determined this way are free from uncertainties due to target thickness and incident particle collection

  2. Diffraction proton scattering on 6Li nucleus and its cluster structure

    Elastic and inelastic scattering of 600 and 1040 MeV protons on 6Li nucleus without suggesting equality of pp-and pn-amplitudes of elastic scattering are investigated within the frames of diffraction approximation. Parameters of 6Li nucleus wave functions, parameters of amplitude of elastic NN scattering at given proton energies are given, differential cross sections of elastic and inelastic proton scattering with excitation of 3+ level for four types of 6Li wave functions are presented graphically. It is obvious from the given calculations that none of the simplest 6Li wave functions can explain the present experimental data. The whole complex of experimental data on elastic and inelastic proton scattering cannot be explained within the frames of a simple αd cluster model using known at present sets of parameters of elastic NN scattering amplitude

  3. Effects of nuclear breakup channel on fusion of 6Li+64Zn system around barrier energies

    We have studied the effects of breakup, occurring due to the nuclear interaction between weakly bound 6Li and tightly bound 64Zn isotopes, on the fusion reaction at near barrier energies within the framework of dynamic polarization potential (DPP) approach. When the nuclear induced dynamic polarization potential is taken into account sub barrier enhancement and above barrier suppression have been found which improves the matching between the fusion excitation function data and predictions for 6Li+64Zn system significantly. (author)

  4. Multi-particle correlation effect at intermediate-energy proton scattering by 6Li

    In the framework of the Glauber-Sitenko theory study is made of the elastic proton scattering by 6Li at the energy of 0.6 and 1.04 GeV using the realistic phenomenological wave functions for different sets of parameters of the elastic scattering NN-amplitudes. An essential cross-sections on a form of the 6Li wave function is shown

  5. Study of reactions induced by 6He on 9Be

    Pires K.C.C.

    2014-03-01

    Full Text Available We present the results of experiments using a 6He beam on a 9Be target at energies 7 − 9 times the Coulomb barrier. Angular distributions of the elastic, inelastic scattering (target breakup and the a-particle production in the 6He+9Be collision have been analysed. Total reaction cross sections were obtained from the elastic scatteringanalyses and a considerable enhancement has been observed by comparing to stable systems.

  6. Electroexcitation of 6Li with application to the reactions 6Li(π-,γ)/sub 1s/ 6He(0+,2+)

    The transverse form factor for the 5.37 MeV(2+,T=1) level of 6Li is analyzed in terms of a phenomenological model to give the configuration amplitudes and transition density. Radiative pion capture rates for the 1s atomic orbital of 6Li leading to the two lowest states of 6He are estimated using the phenomenological functions. The radiative pion capture rate to 6He(g.s.) agrees with experiment, but the rate to 6He(2+,1.8 MeV) is larger than the measured value. It is shown that if the longitudinal form factor is small at q approx. = m/sub π/, the transverse 5.37 MeV form factor gives the radiative pion capture matrix elements directly. As part of this study, the C2 form factor was measured near q=m/sub π/, and its implications on the wave functions are considered

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

    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 7Li(n,n't)4He cross section. The tritium extraction facility used for all these experiments has now been calibrated by measuring the 6Li(n,t)4He/197Au/n,γ)198Au 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

  8. Importance of the tensor interaction in the (/sup 7/Li, /sup 7/Be) reaction

    Dodd, A.C.; Clarke, N.M.; Coopersmith, J.; Griffiths, R.J.; Pearce, K.I.; Stanley, B.; Cook, J.

    1985-09-01

    Data for the /sup 28/Si(/sup 7/Li, /sup 7/Be)/sup 28/Al reaction at 72 MeV and for the /sup 26/Mg(/sup 7/Li, /sup 7/Be)/sup 26/Na reaction at 88 MeV are presented together with one-step DWBA calculations using microscopic form factors. The tensor interaction is shown to be important to explain the structureless nature of the angular distributions.

  9. The importance of the tensor interaction in the (7Li, 7Be) reaction

    Data for the 28Si(7Li, 7Be)28Al reaction at 72 MeV and for the 26Mg(7Li, 7Be)26Na reaction at 88 MeV are presented together with one-step DWBA calculations using microscopic form factors. The tensor interaction is shown to be important to explain the structureless nature of the angular distributions. (author)

  10. Investigation of 7Li(n, γ)8Li reaction by law energy

    The wave functions and main spectroscopic characteristics of the 8Li nucleus as well as the interaction potential in the 7Li+n channel are calculated within the frames of the three-body αtn-potential cluster model. The complete cross sections and reaction velocities of the 7Li(n, γ)8Li are determined along with the above values in the area of the energy up to 1 MeV

  11. Study of direct and sequential break-up reactions in 6Li+ 112Sn system

    The 6Li projectile while moving in the field of a target nucleus can not only dissociate into α+d but it can also first exchange a few nucleon with the target and then break up into two fragments. Identification of all these processes is important to understand the break-up mechanism of 6Li projectile and also to find the origin of the high yield of alpha particle production in such a reaction. In this paper, we present the exclusive measurement of breakup cross sections in 6Li+112Sn reaction exploring the above possibilities. Cross sections for both sequential as well as direct breakup are measured and compared with the theoretical calculations. The measured elastic scattering angular distributions were used as a constraint to the potential parameters that were used in the calculations to explain both elastic scattering and the breakup processes simultaneously

  12. Effect of nucleon momentum inside cluster nuclei 6Li and 6He

    6Li and 6He are cluster nuclei including a tightly bound alpha (4He) core surrounded by two loosely bound nucleons. The One-Nucleon Exchange (ONE) process in p(6He, 4He+n)d and p(6Li, 4He+p)d reactions has been measured for the first time in inverse kinematics to study nucleon-nucleon correlations at rather short range of two nucleon system in 6He and 6Li. In frame of this work we are concentrated in analyzing the effect of Fermi nucleon momentum inside two these nuclei on kinematics of the ONE reaction mentioned above via calculation and measurement for angular distribution of the emitted alpha particles with respect to the beam direction. (author)

  13. Determining the 6Li Doped Side of a Glass Scintillator for Ultra Cold Neutrons

    Jamieson, Blair

    2015-01-01

    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 Li 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 alpha and triton energies of neutron capture on 6Li when the enriched side is facing the Si surface barrier detector.

  14. Tagging fast neutrons from an (241)Am/(9)Be source.

    Scherzinger, J; Annand, J R M; Davatz, G; Fissum, K G; Gendotti, U; Hall-Wilton, R; Håkansson, E; Jebali, R; Kanaki, K; Lundin, M; Nilsson, B; Rosborge, A; Svensson, H

    2015-04-01

    Shielding, coincidence, and time-of-flight measurement techniques are employed to tag fast neutrons emitted from an (241)Am/(9)Be source resulting in a continuous polychromatic energy-tagged beam of neutrons with energies up to 7MeV. The measured energy structure of the beam agrees qualitatively with both previous measurements and theoretical calculations. PMID:25644080

  15. The In Situ Polymerization and Characterization of PA6/LiCl Composites

    Dandan Sun

    2013-01-01

    Full Text Available PA6/LiCl composites were synthesized by in situ anionic polymerization based on the interaction between the inorganic salts and PA6. Sodium hydroxide as initiator and N-acetylcaprolactam as activator were used in the preparation of PA6/LiCl composites with variety of LiCl content. X-ray diffraction (XRD and differential scanning calorimeter (DSC testing results showed that both of degree of crystallinity and melting temperature of the composites were decreased under the influence of LiCl. And the γ crystal phase proportion increased with increasing the LiCl content to appropriate amount.

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

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

    2016-03-01

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

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

    Maris P.

    2016-01-01

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

  18. Scattering of polarized tritons by 9Be and 12C

    The differential cross section and the analyzing power A/sub y/ for 9Be(t,t)9Be and 12C(t,t)12C elastic scattering have been measured at 15 and 17 MeV over the angular range theta/sub lab/ = 17.5--165.00. The data in the forward hemisphere have been analyzed with a standard optical model. A large depth and conventional geometry parameters for the spin-orbit potential have been found. The results of the present analysis are in general agreement with previous work involving polarized tritons scattered from heavy target nuclei and show important differences from investigations of the scattering of polarized helions on light nuclei

  19. Role of projectile breakup in {sup 6}He and {sup 6}Li induced fusion reactions around barrier energies

    Kumari, Anju; Kharab, Rajesh, E-mail: kharabrajesh@rediffmail.com

    2015-09-15

    The influence of projectile breakup on fusion cross section for {sup 6}He + {sup 209}Bi, {sup 6}He + {sup 64}Zn, {sup 6}Li + {sup 209}Bi and {sup 6}Li + {sup 64}Zn reactions at near barrier energies is studied within the framework of quantum diffusion approach. The breakup does not affect the fusion induced by {sup 6}He, whereas a significant suppression for {sup 6}Li induced reaction is observed in below barrier energy region.

  20. Study of 9 Be + 29 Si system nuclear fusion

    Fusion cross sections for the 9 Be + 29 Si system have been measured in the energy range between 17 and 38 MeV (lab) by detecting the evaporation residues with the time of flight technique. Angular distributions have been measured from 7.50 C to 350 C in the laboratory frame at E(9 Be) = 26 and 38 MeV. The measured fusion cross sections are significantly smaller than the total reaction cross sections obtained from fits to the elastic scattering data in the same energy range. Comparison with existing data for compound systems with A= 38 shows that this effect can not be understood in terms of the statistical yrast line of the formed compound nucleus. A systematic analysis of the energy dependence of the ratio between the fusion cross section and the total reaction cross section, for the system 9 Be + 29 Si and many other available in the literature has been performed. The saturation value can be associated to the nucleon or cluster separation energy of the light nuclei participant in the collision, leading to an hindrance of the fusion cross section. (author)

  1. Faddeev calculations for the Λ9Be spectrum

    Vlahovic B.

    2010-04-01

    Full Text Available An α-cluster model is applied to study low-lying spectrum of the Λ9Be hypernicleus. The ααΛ three-body problem is numerically solved by the Faddeev equations in configuration space using phenomenological pair potentials. Found is a set of the potentials that reproduces experimental data for the ground state (1+/2 binding energy and excitation energy of the 5+/2 and 3+/2 states, simultaneously. This set includes the Ali-Bodmer potential of version “e” for αα and modified Tang-Herndon potential for αΛ interactions. The spin-orbit αΛ interaction is given by modified Scheerbaum potential. Low-lying energy levels are evaluated applying a variant of the analytical continuation method in coupling constant, and the experimental data for excitation energies are well reproduced by our calculations. This result improves previous α-cluster calculations. It is shown that the spectral properties of Λ9Be can be classified as an analog of 9Be spectrum with the exception of several “genuine hypernuclear states”, which agrees qualitatively with previous studies. The energy splitting of spin-flip doublet (9+/2 , 7+/2 is predicted.

  2. Basic technology for {sup 6}Li enrichment using an ionic-liquid impregnated organic membrane

    Hoshino, Tsuyoshi, E-mail: hoshino.tsuyoshi@jaea.go.jp [Blanket Irradiation and Analysis Group, Fusion Research and Development Directorate, Japan Atomic Energy Agency, 4002, Narita-cho, Oarai-machi, Higashi Ibaraki-gun, Ibaraki 311-1393 (Japan); Terai, Takayuki [The Institute of Engineering Innovation and Department of Nuclear Engineering and Management School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2011-10-01

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

  3. Optical model studies of 6Li elastic scattering at 156 MeV

    Differential cross sections for 6Li elastic scattering at 156 MeV from 12C, 40Ca 90Zr and 208Pb are presented. The sensitivity to various potential forms is established by using Saxon Woods, Saxon-Woods-squred, density independent and density dependent folded potentials. The extent to which the experimental data determine the potentials and related quantities is discussed. (orig.)

  4. Reactions (d,7Li) and (d,7Be) in 19F nuclei

    Differential cross sections have been measured for the reactions 19F(d,7Li)14N, 19F(d,7Li(/sub 0.478/)14N, 19F(d,7Be)14C, and 19F(d,7Be(/sub 0.429/)14C in a cyclotron beam of deuterons with energy 13.6 MeV. The experimental data were analyzed by the distorted-wave method with inclusion of the finite interaction range and recoil. It is shown that the reactiuns 19F(d,7Li)14N and 19F(d,7Li(/sub 0.478/)14N occur mainly by direct transfer of a 5He cluster from the 4P/sub 1/2/ state of the 19F nucleus to the 1D/sub 3/2/ state of the 7Li nucleus. The differential cross sections for the reactions 19F(d,7Be)14C and 19F(d,7Be(/sub 0.429/)14C could not be explained in terms of the theory of direct transfer of a 5Li cluster

  5. Nuclear reactions of the system {sup 6} Li on {sup 58} Ni near the Coulomb barrier; Reacciones nucleares del sistema {sup 6} Li sobre {sup 58} Ni cerca de la barrera de Coulomb

    Lizcano, D.; Aguilera, E.F.; Garcia M, H.; Martinez Q, E. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2004-07-01

    Protons, alpha particles and deuterons coming from the reactions {sup 6} Li + {sup 58} Ni are detected to three different energy around the Coulomb barrier. The possible effects of the weakly bound character of the projectile are studied and the results are compared with previous data for the system {sup 6} Li + {sup 59} Co. (Author)

  6. Study on the differential cross sections of the (d, 7Li)-reactions on 13C nuclei

    Differential cross sections of 13C(d, 7Li)8Be and 13C(d, sup(7)Li*sub(0.478))sup(8)Be on 13.6 MeV deuteron cyclotron beam using the ΔExE technique to identify reaction products, in which silicon ΔE detectors, of approximately 5 mk thickness were applied, have been measured. Experimental data have been analyzed according to the Hauser- Feshbach statistical theory and in the approximation of distorted waves with account for finitude of interaction and recoil radius. It is shown that angular distributions of 7Li and sup(7)Li*sub(0.478) ions are described most satisfactorily in the approximation of direct transfer of 5He quasicluster from 2Dsub(1/2) state of 13C nucleus into 2Ssub(3/2) state of 7Li, sup(7)Li*sub(0.478) nuclei

  7. Breakup mechanisms for 7Li + 197Au, 204Pb systems at sub-barrier energies

    Luong D.H.

    2013-12-01

    Full Text Available Coincidence measurements of breakup fragments were carried out for the 7Li + 197Au and 204Pb systems at sub-barrier energies. The mechanisms triggering breakup, and time-scales of each process, were identified through the reaction Q-values and the relative energy of the breakup fragments. Binary breakup of 7Li were found to be predominantly triggered by nucleon transfer, with p-pickup leading to 8Be → α + α decay being the preferred breakup mode. From the time-scales of each process, the coincidence yields were separated into prompt and delayed components, allowing the identification of breakup process important in the suppression of complete fusion of 7Li at above-barrier energies.

  8. Extremely slow cation exchange processes in Li4SiO4 probed directly by two-time 7Li stimulated-echo nuclear magnetic resonance spectroscopy

    Lithium self-diffusion in the low-temperature modification of polycrystalline lithium ortho-silicate Li4SiO4 is investigated by 7Li two-time stimulated echo NMR spectroscopy. Extremely slow Li exchange processes were directly monitored between 300 and 433 K by recording spin-alignment echoes as a function of mixing time varying over six decades from 10-5 to 10 s. In the investigated temperature range the hopping correlation functions show biexponential behaviour. Whereas the first decay step reflects directly Li jumps between electrically different sites, the second one is simply induced by the decay of alignment order due to quadrupolar relaxation. The echo decay rates τ-1 (101 s-1≤τ-1≤104 s-1), which can be identified with Li jump rates, show Arrhenius behaviour with an activation energy of 0.53(1) eV. The directly measured jump rates are in good agreement with those obtained recently by one- and two-dimensional 6Li exchange MAS NMR reported in the literature

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

    Hu, Jian Zhi [Pacific Northwest National Laboratory

    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.

  10. Search for higher excited states of $^{8}$Be* to study the cosmological $^{7}$Li problem

    We would like to study the unresolved $^{7}$Li abundance anomaly by carrying out experiments that destroy the rare isotope $^{7}$Be, the main source of $^{7}$Li. Utilizing a 35 MeV $^{7}$Be beam from HIE-ISOLDE, we would like to measure the (d,p) and (d,d) reactions with T-REX. The higher beam energy, for the first time, would allow us to measure higher excitation energies in $^{8}$Be up to about 20 MeV. With a wider angular coverage, we can make improved average cross-section measurement without assuming isotropy done in earlier works.

  11. Search for a resonant enhancement of the 7Be + d reaction and primordial 7Li abundances

    Big Bang nucleosynthesis calculations, constrained by the Wilkinson Microwave Anisotropy Probe results, produce 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.

  12. Determination of degradation constants of energetic 7*Li ion in liquid media using a thin boron film on silicon wafer

    A novel method to determine degradation constants has been developed for energetic 7*Li ions produced from the 10B (n, α) 7*Li reaction, moving in liquid media. The energetic 7*Li generated in a thin boron film on silicon wafer plunged into a liquid sample in which the wafer was immersed. The degradation constants were determined by analyzing the Doppler-broadened lineshapes of prompt γ-ray at 478 keV emitted from 7*Li. For comparison, degradation constants were also measured for solutions of boron compounds. Values obtained by the two methods gave fair agreement. (author)

  13. First direct measurement of the 2H(α,γ)6Li cross section at Big Bang energies at LUNA

    The amount of 6Li produced during the Big Bang Nucleosynthesis (BBN) era can be theoretically estimated on the basis of cosmological and nuclear astrophysics knowledge. The latter strongly depends on the measurement of the nuclear cross section of the processes involved in the production and destruction of 6Li during the first stages of the Universe. Whereas the destruction process cross sections are well known, the reaction that dominates the 6Li production, the 2H(α,γ)6Li, has never been directly measured in the BBN energy range and only upper limits coming from indirect measurements are available till now. Here we report the first direct measurement of the 2H(α,γ)6Li cross section at BBN energies obtained at LUNA (Laboratory for Underground Nuclear Astrophysics, LNGS, Italy). (author)

  14. Measurement of the 1H(6He,6Li)n reaction in inverse kinematics

    The 1H(6He,6Li)n reaction was studied at 0 degree with the NSCL A1200 fragment separator in the energy loss mode. A 6He secondary beam at E/A=93 MeV was used to measure the Gamow-Teller and Fermi strengths between the ground state of 6He and the ground and excited states of 6Li, in inverse kinematics. At 0 degree the ground-state cross section is measured to be dσGS/(dΩ)=43±16 mb/sr, which is dominated by systematic error in the secondary beam flux. The ratio of Gamow-Teller to Fermi strength is not sensitive to this error and is found to be (87±6)% of that expected from (p,n) systematics and β decay. Angular distributions have been measured between 0 degree and 10 degree in the center of mass. copyright 1996 The American Physical Society

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

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

    2016-03-01

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

  16. Thermal neutron detection using a silicon pad detector and 6LiF removable converters

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

  17. Neutron assay in mixed radiation fields with a 6Li-loaded plastic scintillator

    A novel technique for assay of thermal and fast neutrons in a 6Li-loaded plastic scintillator is presented. Existing capture-gated thermal neutron detection techniques were evaluated with the 6Li-loaded plastic scintillator studied in this work. Using simulations and experimental work, shortcomings in its performance were highlighted. As a result, it was proposed that by separating the combined fast and thermal neutron events from gamma events, using established pulse shape discrimination techniques, the thermal neutron events could then be assayed. Experiments were conducted at the National Physical Laboratory, Teddington, performing neutron assays with seven different neutron fields using the proposed technique. For each field, thermal and fast neutron content was estimated and were shown to corroborate with the seven synthesised fields

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

    Dytrych, T; Launey, K D; Draayer, J P; Maris, P; Vary, J P; Langr, D; Oberhuber, T

    2015-01-01

    We present an ab initio symmetry-adapted no-core shell-model description for $^{6}$Li. We study the structure of the ground state of $^{6}$Li and the impact of the symmetry-guided space selection on the charge density components for this state in momentum space, including the effect of higher shells. We accomplish this by investigating the electron scattering charge form factor for momentum transfers up to $q \\sim 4$ fm$^{-1}$. We demonstrate that this symmetry-adapted framework can achieve significantly reduced dimensions for equivalent large shell-model spaces while retaining the accuracy of the form factor for any momentum transfer. These new results confirm the previous outcomes for selected spectroscopy observables in light nuclei, such as binding energies, excitation energies, electromagnetic moments, E2 and M1 reduced transition probabilities, as well as point-nucleon matter rms radii.

  19. Development of a mini high efficiency neutron detector based on 6LiI (Eu) scintillator

    A mini neutron detector with the dimension of φ25 mm ×20 mm is developed based on a 6LiI( Eu) scintillator with a Hamamatsu S3590-08 photodiode. The detector was used to detect thermal neutrons from a paraffin shielded 252Cf neutron source and the detect efficiency to thermal neutron was calculated to be 95% with a resolution of thermal neutron peak about 16%. (authors)

  20. The 6Li(γ,p) reaction at intermediate photon energies

    The 6Li(γ,p) reaction was measured at average tagged photon energies of left angle Eγ right angle =59 and 75 MeV. Protons were detected at 5 different angles between 30 circle and 150 circle. Most of the observed strength is apparently due to the three-body breakup channels. In particular the semi-inclusive (γ,p(n)) and (γ,p(t)) channels are discussed. ((orig.))

  1. Fusion and nonfusion phenomena in the 6Li+40Ca reaction at 156 MeV

    Reaction products from 6Li-induced reactions on 40Ca at 156 MeV have been studied using the dE x E identification as well as the inclusive γ-ray method. The complete fusion cross-section has been found to be σsub(f)=(77 +- 11)mb. The Z distribution of fusion evaporation residues is compared with statistical model predictions. The Z spectrum of reaction products shows a maximum at 156Li break-up. (author)

  2. Investigation of the selection of the selectively heated ions of 6Li isotope from lithium plasma

    Results of experiments on preparation of enriched lithium by means of plasma isotope separation method using ion cyclotron resonance (ICR) are presented. Two types of collectors were compared: cylindrical and plane ones. Both collectors were placed just as in homogeneous magnetic field immediately after the zone of selective ICR heating, so in diverging weakened one, closer to solenoid end. In cylindrical collector higher lithium enrichment by 6Li (up to 83 %) is observed. That corresponds to distribution coefficient ≅60

  3. Measurement of interaction energy near a Feshbach resonance in a 6Li Fermi gas

    Bourdel, T; Cubizolles, J.; Khaykovich, L.; Magalhaes, K. M. F.; Kokkelmans, S. J. J. M. F.; G. V. Shlyapnikov; Salomon, C

    2003-01-01

    We investigate the strongly interacting regime in an optically trapped $^6$Li Fermi mixture near a Feshbach resonance. The resonance is found at $800(40) $G in good agreement with theory. Anisotropic expansion of the gas is interpreted by collisional hydrodynamics. We observe an unexpected and large shift ($80 $G) between the resonance peak and both the maximum of atom loss and the change of sign of the interaction energy.

  4. Formation of eta'(958) Meson Bound States by the 6Li(gamma,d) reaction

    Miyatani, M; Nagahiro, H; Hirenzaki, S

    2016-01-01

    We have investigated the 6Li(gamma,d) reaction theoretically for the formation of the eta'(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.

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

    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 work is supported by the Austrian Science Fund FWF within the collaborative research grant FoQuS.

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

    Moin Shaikh, Md.; Roy, Subinit

    2016-07-01

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

  7. Isovector giant resonances in sup 6 He, sup 1 sup 2 B, sup 9 sup 0 Y, sup 1 sup 2 sup 0 In, and sup 2 sup 0 sup 8 Tl observed in the ( sup 7 Li, sup 7 Be) charge-exchange reaction

    Annakkage, T; Winfield, J S; Berg, G P A; Brown, J A; Crawley, G; Danczyk, S; Fujiwara, M; Mercer, D J; Pham, K; Roberts, D A; Stasko, J T; Yoo, G H

    1999-01-01

    The ( sup 7 Li, sup 7 Be) and ( sup 7 Li, sup 7 Be gamma) reactions have been studied at bombarding energies of 50 A MeV on targets of sup 6 Li, sup 1 sup 2 C, sup 9 sup 0 Zr, sup 1 sup 2 sup 0 Sn, sup 2 sup 0 sup 8 Pb, and polystyrene. The detection of Doppler-shifted gamma-rays from excited sup 7 Be permits the identification of the spinflip and non-spinflip characteristics. Transitions to over 20 discrete states and resonances have been observed. Angular distributions for sup 6 Li and sup 1 sup 2 C are well described by microscopic one-step distorted-waves calculations with shell-model transition amplitudes. The transitions to the ground states of sup 6 He and sup 1 sup 2 C exhibit significant Gamow-Teller strength, but approx 7% and approx 17%, respectively, of the calculated cross sections at theta approx 0 deg. arise from the tensor interaction. A broad resonance at approx 5.6 MeV in the halo nucleus sup 6 He with J suppi = (2 sup + , 1 sup - , 0 sup +) seems to correspond to a structure predicted at th...

  8. Design of a 7Li rotating target for neutron production using a Van de Graaff accelerator

    We present a rotating target used for the production of monokinetic neutron fluxes. The neutrons are produced from the 7Li(p,n)7Be reaction for fast neutron elastic and inelastic scattering experiments. This target has been operated with a proton beam current of 8 to 10 μA during six consecutive weeks and has given entire satisfaction

  9. Constraints on Ωb from nucleosynthesis of 7Li in the standard big bang model

    We update standard big bang nucleosynthesis (SBBN) calculations on the basis of recent nuclear physics compilations (NACRE in particular), experimental and theoretical works. By a Monte Carlo technique, we calculate the uncertainties on the light element yields (4He, D, 3He and 7Li) related to nuclear reactions. The results are compared to observations that are thought to be representative of the corresponding primordial abundances. It is found that 7Li could lead to more stringent constraints on the baryonic density of the universe (Ωbh2) than deuterium, because of much higher observation statistics and an easier extrapolation to primordial values. The confrontation of SBBN results with 7Li observations is of special interest since other independent approaches have also recently provided Ωbh2 values: (i) the anisotropies of the cosmic microwave background by the BOOMERANG, CBI, DASI and MAXIMA experiments and (ii) the Lyman-α forest at high redshift. A comparison between these results obtained by different methods provides a test of their consistency and could provide a better determination of the baryonic density in the universe. However, the agreement between Ωbh2 values deduced from SBBN calculation and 7Li observation on the one hand and CMB observations on the other hand is only marginal

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

    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

  11. Elastic break-up of 156 MeV 6Li projectiles with large asymptotic relative momenta of the fragments

    The triple differential cross sections for elastic break-up of 156 MeV 6Li projectiles by the reactions 208Pb (6Li, ad) 208Pbg.s., and 12C (6Li, ad) 12Cg.s. have been measured with large asymptotic relative momenta of the outgoing fragments. The data exhibit rather unfamiliar shapes of the energy spectra, often replacing the usual bell-shape distributions by double-peaked structures and varying rapidly with the relative emission angles. The origin of these features has been explored and the cross sections have been analysed on the basis of a diffractive disintegration approach. (orig.)

  12. Triple-differential cross section of the 208Pb(6Li, αd)208 Pb Coulomb breakup and astrophysical S-factor of the d(α,γ)6 Li reaction at extremely low energies

    A method of calculation of the triple-differential cross section of the 208Pb(6Li, αd)208Pb Coulomb breakup at astrophysically relevant energies E of the relative motion of the breakup fragments, taking into account the three-body (α - d - 208Pb) Coulomb effects and the contributions from the E1- and E2- multipoles, including their interference, has been proposed. The new results for the astrophysical S-factor of the direct radiative capture d(α, γ)6 Li reaction at E ≤ 250 keV have been obtained. It is shown that the experimental triple-differential cross section of the 208Pb(6Li, αd)208Pb Coulomb breakup can also be used to give information about the value of the modulus squared of the nuclear vertex constant for the virtual 6Li → α + d. (author)

  13. Evaluation of d + 6,7Li data for deuteron incident energies up to 50 MeV

    A new evaluation of the nuclear data for a particle transport calculations was performed for d + 6,7Li interactions in the energy region from 4 to 50 MeV incident energy. Use was made of the available new optical model potential for d + Li interactions. For the description of a neutron emission a new optical model potential for n + 9Be was elaborated for the neutron energies from 0.1 to 22 MeV. Global optical model potentials were used for the neutrons above 22 MeV and for protons, tritons, He-3 and alphas - in the whole energy range. The following nuclear processes were accounted for: particle evaporation and preequilibrium emission, stripping of the proton from the deuteron and direct interactions of deuterons with lithium nuclei. GNASH and ECIS96 codes were applied for the first two process descriptions, the Serber model was utilised for stripping processes and the DWUCK4 code was used for direct reaction processes modelling. Total neutron emission spectra were calculated as a sum of the spectra in all these processes. A complete transport file was finally prepared in ENDF-6 format covering the deuteron incident energies up to 50 MeV. The newly evaluated data are in good agreement with experimental data for neutron emission spectra. The evaluated data files were successfully tested with a modified version of the MCNP computer code

  14. Big Bang nucleosynthesis and the results of the 2H(α,γ)6Li experiment at LUNA

    Observations of the 6Li abundance in very metal-poor stars, if confirmed, show a level of 6Li that is several orders of magnitude larger than the production of this nuclide in standard Big Bang nucleosynthesis. The 2H(α,γ)6Li nuclear reaction is believed to dominate 6Li production in the Big Bang, but there are no directly measured data at relevant energies yet. The reaction has been studied at the LUNA 0.4 MV accelerator, deep underground in the Gran Sasso laboratory in Italy, using an intensive He+ beam and a windowless deuterium gas target. The conclusions from the final data analysis of the experiment are presented.

  15. Comparison of Thermal Neutron Detection Efficiency of $^{6}$Li Scintillation Glass and $^{3}$He Gas Proportional Tube

    Xu, Ming; Tang, Zhi-Cheng; Chen, Guo-Ming; Tao, Jun-Quan

    2013-01-01

    We report on a comparison study of the $^{3}$He gas proportional tube and the $^{6}$Li incorporated scintillation glasses on thermal neutron detection efficiency. Both $^{3}$He and $^{6}$Li are used commonly for thermal neutron detection because of their high neutron capture absorption coefficient. By using a neutron source $^{252}$Cf and a paraffin moderator in an alignment system, we can get a small beam of thermal neutrons. A flash ADC is used to measure the thermal neutron spectrum of eac...

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

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

  17. Model Calculation of n + 6Li Reactions Below 20 MeV

    ZHANG Jing-Shang; HAN Yin-Lu

    2001-01-01

    Based on the unified Hauser-Feshbach and exciton model for light nuclei, the calculations of reaction cross sections and the double-differential cross sections for n + 6Li are performed. Since all of the first-particle emissions are from the compound nucleus to the discrete levels, the angular momentum coupling effect in pre-equilibrium mechanism must be taken into account. The fitting of the measured data indicates that the three-body break-up process needs to be involved, and the pre-equilibrium reaction mechanism dominates the reaction processes. In light nucleus reactions the recoil effect must be taken into account.``

  18. Study of the 6Li + p → 3He + 4He reaction in inverse kinematics

    Angular distribution measurements were performed for the 6Li + p → 3He + 4He reaction in inverse kinematics at incident energies of 2.7, 3.3, 4.2 and 4.8 MeV/u. The detection of both recoils (3He and 4He) over the laboratory angle range θlab = 16 circle to 34 circle allowed the determination of the angular distribution over a wide angular range in the center-of-mass frame (θc.m. ∝ 40 circle to 140 circle). The results clarify inconsistencies between existing data sets and are consistent with compound nucleus model calculations. (orig.)

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

    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

  20. 16O resonances near 4α threshold through 12C(6Li,d) reaction

    Several narrow alpha resonant 16O states were detected through the 12C(6Li,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)

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

    Soukeras, V.; Pakou, A.; Sgouros, O. [Department of Physics and HINP, The University of Ioannina, 45110 Ioannina (Greece); Cappuzzello, F.; Bondi, M.; Nicolosi, D. [INFN Laboratory Nazionali del Sud, via S. Sofia 62, 95125, Catania, Italy and Dipartimento di Fisica e Astronomia, Universita di Catania, via S. Sofia 64, 95125, Catania (Italy); Acosta, L.; Marquinez-Duran, G.; Martel, I. [Departamento di Fisica Aplicada, Universidad de Huelva, E-21071, Huelva (Spain); Agodi, C.; Carbone, D.; Cavallaro, M.; Cunsolo, A.; Di Pietro, A.; Fernández-García, J. P.; Figuera, P.; Fisichella, M. [INFN Laboratory Nazionali del Sud, via S. Sofia 62, 95125, Catania (Italy); Alamanos, N. [CEA-Saclay, DAPNIA-SPhN, 91191, Gif-sur-Yvette (France); De Napoli, M. [INFN - Sezione di Catania, via S. Sofia 64, 95125, Catania (Italy); Foti, A. [Dipartimento di Fisica e Astronomia, Universita di Catania, via S. Sofia 64, 95125, Catania, Italy and INFN - Sezione di Catania, via S. Sofia 64, 95125, Catania (Italy); 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.

  2. The scattering of 136 MeV protons from 6Li

    Differential cross sections have been measured for the elastic scattering of 136 MeV protons from 6Li, and for inelastic scattering to the first two excited states. The optical model fit to the elastic scattering differential cross section gave parameters which were retained for the analysis of the two inelastic transitions. The latter differential cross sections were fairly well fitted in shape, but in both cases there is a discrepancy in absolute magnitude of a factor between 1.5 and 4

  3. Nuclear Reaction 6Li(n,4He)T as Radiation Source

    Our investigation was based on the reaction 6Li(n,4He)T, most convenient for the generation of high intensity flow of tritons by the use of thermal neutron flux in atomic reactor. This reaction has high cross section (sigma=953 b), practically no threshold, is rather exothermic (Q=4.78 MeV) and kinetic energy of charged particles (Et=2,74 MeV) is sufficient for the penetration through potential barrier of light elements with Z11C, 13N, 18F, 28Mg, 34mCI and more long lived 3H for medical purposes

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

    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

  5. A 7Li and 27Al NMR study of interaction of lithium hydride with aluminium

    Lithium hydride interaction with metal aluminium is studied using 7Li and 27Al NMR method within 100-700 deg C temperature interval. It is detected, that at temperatures exceeding 420 deg C a number of α', α'', β, γ, δ and δ' phases based on intermetallic LiAl9, LiAl3, LiAl, Li3Al2 and Li9Al4 compounds (IC) are produced in LiH-Al system, their concentrations and rates of production being dependent on the molar ratio of initial components r =[LiH]:[Al]. Production of a stable αphase of [Al] and two methastable α' and α''-phases based on LiAl3 and LiAl9, which are decayed at 530 deg C, is detected under minor molar lithium content. Values of 7Li and 27Al NMR shifts in IC are determined. (author)

  6. Probing transfer to unbound states of the ejectile with weakly bound 7Li on 93Nb

    Pandit, S K; Mahata, K; Keeley, N; Parkar, V V; Rout, P C; Martel, I; Palshetkar, C S; Kumar, A; Ramachandran, K; Patale, P; Chatterjee, A; Kailas, S

    2016-01-01

    The two-step process of transfer followed by breakup is explored by measuring a rather complete set of exclusive data for reaction channels populating states in the ejectile continua of the $^7$Li+$^{93}$Nb system at energies close to the Coulomb barrier. The cross sections for $\\alpha+\\alpha$ events from one proton pickup were found to be smaller than those for $\\alpha+d$ events from one neutron stripping and $\\alpha+t$ events from direct breakup of $^7$Li. Coupled channels Born approximation and continuum discretized coupled channels calculations describe the data well and support the conclusion that the $\\alpha+d$ and $\\alpha+\\alpha$ events are produced by direct transfer to unbound states of the ejectile.

  7. Role of the cluster structure of 7Li in the dynamics of fragment capture

    Exclusive measurements of prompt γ-rays from the heavy-residues with various light charged particles in the 7Li + 198Pt system, at an energy near the Coulomb barrier (E/Vb∼1.6) are reported. Recent dynamic classical trajectory calculations, constrained by the measured fusion, α- and t-capture cross-sections have been used to explain the excitation energy dependence of the residue cross-sections. These calculations distinctly illustrate a two-step process, breakup followed by fusion, in case of the capture of t and α clusters; whereas for 6He+p and 5He+d configurations, massive transfer is inferred to be the dominant mechanism. The present work clearly demonstrates the role played by the cluster structures of 7Li in understanding the reaction dynamics at energies around the Coulomb barrier.

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

    In this work we review all the available experimental neutron data for the 7Li(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. - Highlights: • We review neutron experimental data for the 7Li(p,n) reaction near threshold. • A new computational method was used to study all the available published data. • A consistent description of the neutron source was derived fitting the available data. • We found that the neutron yield at 0° studied by Kononov is the most sensitive curve. • A consistent set of parameters to parametrize the Breit–Wigner formula is presented

  9. Excitation of continuum states in sup 7 Li and their decay by quantum tunneling

    Utsunomiya, H; Yamagata, T; Ohta, M; Aoki, Y; Hirota, K; Ieki, K; Iwata, Y; Katori, K; Hamada, S; Lui, Y W; Schmitt, R P; Typel, S; Baur, G

    1999-01-01

    Strong forward-backward asymmetries were found in the recent alpha-t coincidence measurement of Coulomb breakup of 42 MeV- sup 7 Li via continuum states. The competition between E1 and E2 multipolarities and higher order effects in Coulomb excitation were investigated by solving the time-dependent Schroedinger equation. It is shown that higher order effects are an essential ingredient to the observed large asymmetries. The relevant reaction mechanism is discussed.

  10. Exploring Light Neutron Rich Nuclei via the (7Li,7Be) Reaction

    A systematic study of the nuclei that can be described as an integer number of α particles plus three neutrons via the (7Li,7Be) 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.

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

    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

  12. 7Li neutron-induced elastic scattering cross section measurement using a slowing-down spectrometer

    Heusch M.; Ghetta V.; Chabod S.; Brissot R.; Billebaud A.; Méplan O.; Kessedjian G.; Liatard E.

    2010-01-01

    A new integral measurement of the 7Li neutron induced elastic scattering cross section was determined in a wide neutron energy range. The measurement was performed on the LPSC-PEREN experimental facility using a heterogeneous graphite-LiF slowing-down time spectrometer coupled with an intense pulsed neutron generator (GENEPI-2). This method allows the measurement of the integral elastic scattering cross section in a slowing-down neutron spectrum. A Bayesian approach coupled to Monte Carlo cal...

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

    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.

  14. The 3H(α,γ)7Li reaction at low energies

    The 3H(α,γ) reaction, and its mirror 3He(α,γ) are responsible for 7Li production in the big bang. Discrepancies between experimental data sets, as well as differences between the experimental and theoretical energy dependences, cause the 3H(α,γ)7Li cross section to be uncertain by as much as a factor of two at the relevant astrophysical energies (Ec.m. ∼ 100 keV). The authors report new measurements for 50 c.m. 3H targets and an 85% high-purity germanium detector. Angular distributions were measured at nine energies between 115 and 1200 kev. The astrophysical S-factor is observed to increase moderately with decreasing energy to S(0) ∼ 0.10 keV-b. The branching ratio for captures to the first excited state and ground state of 7Li is found to be ∼0.44, independent of energy. The results are compared to previous experiments and theoretical calculations

  15. In-beam PET measurement of $^{7}Li^{3+}$ irradiation induced $\\beta^+}$-activity

    Priegnitz, M; Parodi, K; Sommerer, F; Fiedler, F; Enghardt, W

    2008-01-01

    At present positron emission tomography (PET) is the only feasible method of an in situ and non-invasive monitoring of patient irradiation with ions. At the experimental carbon ion treatment facility of the Gesellschaft für Schwerionenforschung (GSI) Darmstadt an in-beam PET scanner has been integrated into the treatment site and lead to a considerable quality improvement of the therapy. Since ions other than carbon are expected to come into operation in future patient treatment facilities, it is highly desirable to extend in-beam PET also to other therapeutic relevant ions, e.g. 7Li. Therefore, by means of the in-beam PET scanner at GSI the β+-activity induced by 7Li3+ ions has been investigated for the first time. Targets of PMMA, water, graphite and polyethylene were irradiated with monoenergetic, pencil-like beams of 7Li3+ with energies between 129.1 A MeV and 205.3 A MeV and intensities ranging from 3.0 × 107 to 1.9 × 108 ions s−1. This paper presents the measured β+-activity profiles as well as d...

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

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

    2007-10-01

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

  17. Impact of alternate fusion fuels on fusion reactor technology: an initial assessment study. [Catalyzed D, D-/sup 3/He, p-/sup 6/Li, p-/sup 7/Li, D-/sup 6/Li, p-/sup 11/B, /sup 3/He-/sup 3/He

    Baker, C.C.; Bolon, A.; Clemmer, R.

    1979-11-01

    The initial results of a study carried out to assess some of the technology implications of non-D-T fusion fuel cycles are presented. The primary emphasis in this report is on D-D, catalyzed-D and D-/sup 3/He fuel cycles. Tokamaks and field-reversed mirrors have been selected as sample confinement concepts. A new technique of employing neutronic computer codes to study the transport of cyclotron radiation for cases of non-uniform density and temperature profiles is described. The technology areas considered include first wall design considerations, shielding requirements, fuel cycle requirements and some safety and environmental considerations. Conclusions resulting from the study are also presented.

  18. Detection efficiency simulation and measurement of 6LiI/natLiI scintillation detector

    Background: Being of very high detection efficiency and small size, Lithium iodide (LiI) scintillator detector is used extensively in neutron measurement and environmental monitoring. Purpose: Using thermal reactor, neutron detectors will be tested and calibrated. And a new neutron detector device will be designed and studied. Methods: The relationship between the size and detection efficiency of the thermal neutron detector 6LiI/natLil was studied using Monte Carlo code GEANT4 and MCNP5 package, and the thermal neutron efficiency of detector was calibrated by reactor neutrons. Results: The theoretical simulation shows that the thermal neutron detection efficiency of detector of 10-mm thickness is relatively high, the enriched 6Lil is up to 98% and the nature natLiI 65%. The thermal neutron efficiency of detector is calibrated by reactor thermal neutrons. Considering the neutron scattering by the lead brick, high density polythene and environment neutron contribution, the detection efficiency of 6LiI detector is about 90% and natLiI detector 70%. Conclusion: The detector efficiency can reach the efficiency value of theoretical calculations. (authors)

  19. Measuring the absorption mean cross section in 6Li relative to 235U fission

    Due to the fact that the neutron absorption cross section in 6Li is used as one of standards for determinaton of neutron-physical characteristics of fast reactors the ratio of mean cross sections for absorption by 6Li (A6) and 235U fission F25 are experimentalli investigated. The measurements have been performed in the KBR-8, KBR-10,BFS/39/1 bfs-44, BFS/45a-1 and BFS-46 critical assemblies which are characterized by various neutron spectra by means of a lithium counter with semiconductor detectors. Ratios A6/F25 for investigated assemblies constituted respectively 0.605+-0.009; 0.604+-0.004; 0.581+-0.009; 0.590+-0.574+-0.005. The values of 235U diffusion mean cross sections obtained on the base of these fata and calculated using the CRAB-1 program (given in brackets) are equal respectively 1.53+-0.005 (1.51) 2.38+-0.08 (2.42); 1.935+-0.060 (1.95); 1.89+-0.08 (1.95); 1.780+-0.11 (1.69); 1.90+-0.06 (1.89)

  20. Moderator type neutron spectrometer using 6LiF thermoluminescence dosimeter (TLD)

    For epithermal neutron spectroscopy, one of the important problems in neutron and health physics, a few methods have been considered, but each has difficulties, respectively. To overcome these difficulties and obtain the simple and stable detector operation, a moderator type simultaneous multi-detector has been developed, which has 15 6LiF TLD's embedded in polyethylene moderator. (It is called Filter Transmission Detector (FTD) by the author.) This gives 15 simultaneous data, different in moderating filter sensitivity. Also, the dynamic range of measurement can be large, and the perturbation in the moderator by the detectors can be made small. The paper first describes on the characteristics of 6LiF TLD, then gives the specifications of FTD and reports on the calculated results of response function. In the measurement using a 252Cf neutron source, the spatial distribution of reactivity composed from the response functions and neutron spectra comparatively well agreed with the experimental values. The results of verification in actual neutron field (after transmitted in the fast column and concrete of the reactor ''Yayoi'') showed relatively good agreement with other spectrometrical results in the energy range of tens of keV to MeV. (Wakatsuki, Y.)

  1. Measurement of 6Li(n,α)3H reaction cross section

    The 6Li(n,α)3H reaction cross section was measured at 12 discrete neutron energies between 80 KeV and 470 KeV by using the Oak Ridge Linear Acelerator (ORELA) as a pulsed neutron source. The neutron beam was filtered through 20 cm or 30 cm of Armco iron which produces several monoenergetic energies groups (iron windows) between 20 KeV and 1000 KeV about 2 KeV wide. The (n,α) events were detected by a 1 mm thick Li-glass scintillator and the neutron flux was measured with a NE110 plastic scintillator 6,6 cm thick and 10 cm in diameter. Multiple scattering corrections in the Li-glass and the NE110 scintillator efficiency were determined theoretically by using Monte Carlo technique. The 6Li content in the Li-glasses was determined by transmission measurements with low energy neutrons. A theoretical fit was applied to the results by the R-matrix theory. (Author)

  2. Alpha cluster states in light nuclei populated through the (6Li,d) reaction

    Full text: The alpha cluster correlation is an important concept in the nuclear physics of light nuclei. The main purpose of the research program in progress is the investigation of the alpha clustering phenomenon in (xα) and(xα+ν) nuclei through the (6Li,d) alpha transfer reaction. In fact, there is scarce experimental information on the subject, in particular associated with resonant states predicted near (xα) and (xα+ν) thresholds. Measurements of the 12,13C(6Li,d) 16,17O reactions, at an incident energy of 25.5 MeV, have been performed employing the Sao Paulo Pelletron-Enge Split-Pole facility and the nuclear emulsion detection technique. The work is under way and an experimental energy resolution of 30 keV was obtained. Near the (4α) breakup threshold in 16O, three narrow alpha resonances, not previously measured, were detected, revealing important α + 12C(G.S.) components. One of these resonances corresponds to the known 0+ state at 15.1 MeV[5] of excitation that has probably, according to Funaki et al., the gas like configuration of the 4α condensate state, with a very dilute density and a large component of α + 12C(Hoyle) configuration. As was already mentioned, our experimental information points to the necessity of including the α + 12C(G.S.) component in the wave function. (author)

  3. Sequence variations of in vitro pUC18 plasmid DNA induced by high energy 7Li ion beams implantation

    High energy heavy ion beams is a new mutagen for crop mutation breeding, but limited data are available on the molecular level induced by this mutagen. The in vitro pUC18 plasmid DNA was implanted by 7Li ion beams by doses of 0, 20, 40, 60, 80 and 100Gy, respectively, with the energy of 42.3Mev. The results showed that the damage effects induced by 7Li ion beams implantation was different from low LET rays, even low doses of 7Li ion beam could induce high damage on hydrogen bonds. Percentage of damages on hydrogen bonds of in vitro DNA induced by 7Li ion beams implantation increased with dosage increase up to 40Gy, then reduced with dosage increase, and higher than those of gamma rays in the same dosage. The relationship of dosage and damage percentage was different from that of gamma rays which was positive-linear correlation. Mutation frequency of 7Li ion beam implantation was 1.6 to 4.3 times to that of spontaneous mutation. The relationship of mutation frequency and dosage was similar with that of damage effects on hydrogen bonds, and showed a peak at 40Gy. The above results were identical with biological effects of wheat implanted by 7Li ion beams. Ten mutants were used for sequence analysis, which indicated that the types of base changes included base transversion, transition and deletion. Among all base changes detected, the frequency of bases transition (60%) was higher than that of bases transversion (30%) and bases deletion (10%). It seemed that thymine was more sensitive to the implantation than any other bases and base changes were mainly T→C and C→T. Bases between T and C were seemed to be easily induced by 7Li ion beams. The high percentage of DNA sequence variations could explain primarily the biological effects caused by 7Li ion beams in the M1 generation of crops. (author)

  4. Use of {sup 7}Li(p,n) reaction as a neutron source in a PGNAA setup

    Naqvi, A.A. [Department of Physics, King Fahd University of Petroleum and Minerals, Box No. 1815, Dhahran 31261 (Saudi Arabia)]. E-mail: aanaqvi@kfupm.edu.sa; Nagadi, M.M. [Department of Physics, King Fahd University of Petroleum and Minerals, Box No. 1815, Dhahran 31261 (Saudi Arabia)

    2005-03-01

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

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

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

    2013-05-01

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

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

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

    2015-06-01

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

  7. MeV Neutron Production from Thermal Neutron Capture in {6}^Li Simulated with Geant4

    Santoro, Valentina; Bentley, Phillip M

    2015-01-01

    Various Li compounds are commonly used at neutron facilities as neutron absorbers. These compounds provide one of the highest ratios of neutron attenuation to $\\gamma$-ray production. Unfortunately, the usage of these compounds can also give rise to fast neutron emission with energies up to almost 16 MeV. Historically, some details in this fast neutron production mechanism can be absent from some modeling packages under some optimization scenarios. In this work, we tested Geant4 to assess the performance of this simulation toolkit for the fast neutron generation mechanism. We compare the results of simulations performed with Geant4 to available measurements. The outcome of our study shows that results of the Geant4 simulations are in good agreement with the available measurements for $^6$Li fast neutron production, and suitable for neutron instrument background evaluation at spallation neutron sources.

  8. Nuclear shell-model calculations for 6Li and 14N with different NN potentials

    Two ''phase-shift equivalent'' local NN potentials with different parametrizations, Reid93 and NijmII, which were found to give nearly identical results for the triton by Friar et al., are shown to yield remarkably similar results for 6Li and 14N in a (0+2)ℎΩ no-core space shell-model calculation. The results are compared with those for the widely used Hamada-Johnson hard-core and the original Reid soft-core potentials, which have larger deuteron D-state percentages. The strong correlation between the tensor strength and the nuclear binding energy is confirmed. However, many nuclear structure properties seem to be rather insensitive to the details of the NN potential and, therefore, cannot be used to test various NN potentials

  9. Study of reaction products of d + 6Li at 0,18 MeV

    The study of continuous spectra of low energy particles, and more particularly of their shape and intensity allows a better understanding and knowledge of the structure of nuclei as they interact when encountering. As previous studies performed in Saclay had been interpreted by introducing the new notions of nuclear molecule or activated complex followed by a dissymmetric breaking, and in order to better understand the formation of these molecules, this research thesis reports the study of the d + 6Li reaction at 0,18 MeV. After a description of the experimental installation and of the processing of nuclear emulsions, the author presents and discusses the obtained results and calculations resulting from the fact that the different particles cannot be discriminated in the continuum. Theoretical results for the continuous spectrum are compared with experimental results, and the author reports angular distributions of alpha particles and p0 and p1 protons

  10. Implanted $^{7}$Be Targets For The Study of Neutron Interactions With $^{7}$Be : (The "Primordial $^{7}$Li Problem")

    The disagreement of the predicted abundance of primordial $^{7}$Li with the observed abundance is a longstanding problem in Big Bang Nucleosynthesis (BBN) theory (“Primordial $^{7}$Li problem”). While BBN theory correctly predicts the relative abundances of $^{2}$H/$^{1}$H, $^{3}$He/$^{1}$H and $^{4}$He/$^{1}$H (that vary over four orders of magnitudes), but it over-predicts the relative abundance of primordial $^{7}$Li/$^{1}$H by a factor of approximately 3-4 larger than observed (approximately 4-5$\\sigma$ discrepancy). Primordial $^{7}$Li is destroyed during the first 15 minutes primarily via the $^{7}$Li(p,$\\alpha$) reaction. Hence most of the primordial $^7$Li is predicted as the result of the (later when atoms are formed) electron capture $\\beta$-decay of the primordial $^{7}$Be that is produced primarily in the $^{3}$He($\\alpha$,$\\gamma$) )$^{7}$Be reaction. We propose to investigate the direct destruction of $^{7}$Be during (the first 15 minutes of) BBN via the $^{7}$Be(n,$\\alpha$) reaction to ch...

  11. Portable gamma and thermal neutron probe using a {sup 6}LiI(Eu) crystal

    Carneiro, Clemente J.G.; Araujo, Geraldo P.; Milian, Felix M.; Barbosa, Jurandir C.; Garcia, Fermin [Universidade Estadual de Santa Cruz (UESC), Ilheus, BA (Brazil). Centro de Pesquisas em Ciencias e Tecnologias das Radiacoes (CPqCTR); Oliveira, Arno H.; Silva, Mario R.S.; Penna, Rodrigo [Universidade Federal de Minas Gerais (DEN-UFMG), Belo Horizonte, MG (Brazil). Dept. de Engenharia Nuclear

    2011-07-01

    Europium-activated lithium-6 iodide is a scintillator used for gamma and neutron counting. A portable detection system was built based on this scintillator. This system has three modules: the scintillator, a 10 m liquid light guide, and a Hamamatsu photon counting head H9319 used as a light pulse digitizer. Data transfer, measurement time and other necessary adjustment can be controlled by software from the PC through the RS-232C interface. The scintillator, a crystal of {sup 6}LiI(Eu), is a small cylinder with 3 mm diameter and 40 mm length completely sealed in an aluminum tube coupled to the light guide. The small size of the scintillator increases the neutron/gamma count ratio, since 2 to 3 mm of thickness of this crystal absorbs all thermal neutrons. Intensities of X and gamma rays, and thermal neutrons can be recorded for time intervals of 10 ms to 1 s storing up to 10000 countings. The system was calibrated for measuring radiation doses for validating numerical models in dosimetry. Two characteristic reinforce this application, measurements can be done at several meters away from the radiation source and also inside of water. In addition, it was used to build nuclear probes based on Compton scattering or neutron moderation in porous media by attaching an AmBe source to the top of the aluminum tube. Tests were done to determine the reproducibility of counting rates. Background counting was measured at several temperatures to verify the influence of dark current of PMT. Sealed AmBe, low activity Am, and X rays sources were used for studies of radiation counting statistics. X rays apparatus was used to correlate counting rates measured with the {sup 6}LiI(Eu) detection system and doses measured with an ionization chamber at several distances from the X ray source. (author)

  12. Alpha cluster states in light nuclei populated through the (6Li,d) reaction

    Borello-Lewin, Thereza; Rodrigues, M.R.D.; Horodynski-Matsushigue, L.B.; Duarte, J.L.M.; Rodrigues, C.L.; Souza, M.A. [Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica; Cunsolo, A.; Cappuzzello, F. [Universita di Catania (Italy). Istituto Nazionale di Fisica Nucleare. Lab. Nazionali del Sud; Ukita, Gilberto Mitsuo [Universidade de Santo Amaro (UNISA), Sao Paulo, SP (Brazil). Fac. de Psicologia

    2011-07-01

    Full text: The alpha cluster correlation is an important concept in the nuclear physics of light nuclei. The main purpose of the research program in progress is the investigation of the alpha clustering phenomenon in (x{alpha}) and(x{alpha}+{nu}) nuclei through the ({sup 6}Li,d) alpha transfer reaction. In fact, there is scarce experimental information on the subject, in particular associated with resonant states predicted near (x{alpha}) and (x{alpha}+{nu}) thresholds. Measurements of the {sup 12},{sup 13}C({sup 6}Li,d) {sup 16},{sup 17}O reactions, at an incident energy of 25.5 MeV, have been performed employing the Sao Paulo Pelletron-Enge Split-Pole facility and the nuclear emulsion detection technique. The work is under way and an experimental energy resolution of 30 keV was obtained. Near the (4{alpha}) breakup threshold in {sup 16}O, three narrow alpha resonances, not previously measured, were detected, revealing important {alpha} + {sup 12}C(G.S.) components. One of these resonances corresponds to the known 0{sup +} state at 15.1 MeV[5] of excitation that has probably, according to Funaki et al., the gas like configuration of the 4{alpha} condensate state, with a very dilute density and a large component of {alpha} + {sup 12}C(Hoyle) configuration. As was already mentioned, our experimental information points to the necessity of including the {alpha} + {sup 12}C(G.S.) component in the wave function. (author)

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

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

    2015-08-01

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

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

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

    2015-05-01

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

  15. Double-folding analysis of the 6Li + 58Ni reaction using the ab initio density distribution

    The elastic scattering angular distributions of the 6 Li + 58 Ni reaction are reanalyzed by using the double-folding model (DFM) within the framework of the optical model (OM) at energies near the Coulomb barrier, ELab = 9.9, 11.2, 12.1, 13.0 and 14.0 MeV. With this goal, for the first time, the no-core full configuration (NCFC) density distribution (DD) of the 6 Li nucleus is used in order to obtain the real potentials. Also, in order to see the validity of NCFC DD, another density distribution (Gaussian shape) of the 6 Li nucleus is used to obtain the real potentials in DF calculations. The results with NCFC DD are compared with Gaussian shape (GS) DD as well as the experimental data. It has been seen that the NCFC DD results are in agreement with the experimental data, giving better results than GS DD. (orig.)

  16. The Astrophysical S-factor for the 2H(, )6Li Nuclear Reaction at Low-Energies

    H. Sadeghi; A. Moghadasi; M. Ghamary

    2014-12-01

    The alpha radiative capture reactions are the key to understand about primordial nucleosynthesis and the observed abundance of light nucleus in stars. The astrophysical S-factor for the process 2H(, )6Li has been calculated at the low-energies relevant to big-bang nucleosynthesis and in comparison with laboratory data. On the basis of the model, the alpha radiative capture process is studied by using the two-and three-body electromagnetic currents. The bound and resonance states of 6Li are calculated via an inverse process, deuteron- photodisintegration of a 6Li nucleus. In comparison with other theoretical approaches and available laboratory data, excellent agreement is achieved for the astrophysical S-factor of this process.

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

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

    2010-11-01

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

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

    Kiff, Scott D.; Reyna, David; Monahan, James (Drexel University, Philadelphia, PA); Bowden, Nathaniel S. (Lawrence Livermore National Laboratory, Livermore, CA)

    2010-10-01

    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.

  19. Angular Distribution of the 12C(6He, 7Li)11B Reaction

    LI Er-Tao; LI Zhi-Hong; LI Yun-Ju; YAN Sheng-Quan; BAI Xi-Xiang; GUO Bing; SU Jun; WANG You-Bao; WANG Bao-Xiang; LIAN Gang; ZENG Sheng; FANG Xiao; ZHAO Wei-Juan; LIU Wei-Ping

    2009-01-01

    Angular distribution of the 12C(6He, 7Li)11B transfer reaction is measured with a secondary 6He beam of 36.4 Me V for the first time. The experimental angular distribution is well reproduced by the distorted-wave Born approxima-tion (DWBA) calculation. The success of the present experiment shows that it is feasible to measure one-nucleon transfer reaction on a light nucleus target with the secondary beam facility of the HI-13 tandem accelerator at China Institute of Atomic Energy (CIAE), Beifing.

  20. Phenomenological and microscopic optical potentials for 88 MeV 7Li scattering

    The elastic scattering cross sections for 88 MeV 7Li ions have been measured for targets of 2426Mg and 4048Ca. Analyses using both phenomenological and microscopic optical potentials provide information on the energy dependence of optical parameters, and the extent to which the potentials are determined for these light ions. The use of a double-folding microscopic model demonstrates the need for normalisation of the real potential by a factor of 0.5 in contrast to measurements at lower energies. The contribution of exchange effects, density dependence and break-up are discussed. (author)

  1. Energy loss of high velocity 6Li2+ ions in carbon foils in charge state non-equilibrium region

    Mean energy losses of high velocity H-like Li ions in thin carbon foils were measured in the charge state non-equilibrium region. Owing to the screening effect of the bound electron, the fixed-charge stopping power for 6Li2+ was smaller than that for 6Li3+. The projectile atomic number dependence of the fixed-charge stopping powers for H-like ions is discussed including our previous data of He, C and O ions with the same velocity. The present result is also compared with the theoretical prediction. (orig.)

  2. Monte Carlo modelling of a TLD device containing 7LiF:Mg,Cu,P detectors

    The Monte Carlo code MCNP-4C2 is used to design a new personal thermoluminescence dosemeter that assesses both Hp(10) and Hp(0.07) in mixed photon/electron fields. The new dosemeter utilizes two 7LiF:Mg,Cu,P elements contained within a Harshaw TLD-700H card, itself inside a polypropylene holder with walls 2 mm thick. Several potential designs of holder are considered; the best incorporates a polytetrafluoroethylene cylinder of diameter 18 mm and thickness 4.3 mm that acts as a filter to provide the correct electron cut-off and an acceptably flat Hp(10) relative response to photons, with an open hole in front of the Hp(0.07) element. Response characteristics for both detectors in this final design are presented for irradiation from a variety of angles of interest, with source energies between 16 and 6174 keV used. Comparison is made between modelled and measured data at normal incidence; the relative responses generally agree well. A new estimate for the relative light conversion efficiency relevant to the 7LiF:Mg,Cu,P is also derived and presented

  3. Corrosion barriers processed by Al electroplating and their resistance against flowing Pb–15.7Li

    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

  4. Corrosion barriers processed by Al electroplating and their resistance against flowing Pb–15.7Li

    Krauss, Wolfgang, E-mail: wolfgang.krauss@kit.edu; Konys, Jürgen; Wulf, Sven-Erik

    2014-12-15

    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.

  5. Quasi-bound alpha resonant states populated by the 12C(6Li, d) reaction

    Full text: The alpha cluster phenomenon in the light nuclei structure has been the subject of a long time investigation since the proposal of the Ikeda diagrams [1]. The main purpose of the research program in progress is the investigation of this phenomenon in (xα) and (xα+n) nuclei through the (6Li, d) alpha transfer reaction [2-4]. Alpha resonant states around the (4α) threshold in the nucleus 16O are the focus of the present contribution. In fact, the importance of these resonances at the elements production in stars is recognized, as primarily pointed out by Hoyle in 12C [6]. The existence of a rotational band with the α +12 C (Hoyle) cluster state structure was recently demonstrated by Ohkubo and Hirabayashi [6]. In order to explore this region of interest, measurements of the 12C(6Li, d)16O reaction up to 17 MeV of excitation at an incident energy of 25.5 MeV, have been performed employing the Sao Paulo Pelletron-Enge Split-Pole facility and the nuclear emulsion detection technique (plates Fuji G6B, 50 μm thick). Spectra associated with six scattering angles, from 5 deg to 29 deg in the laboratory frame, each one 50 cm along the focal surface, were measured. Several narrow resonances with a quasi-bound behavior embedded in the continuum were detected and the resolution of 25 keV allowed for the separation of doublets not resolved before [7,8]. The absolute cross sections and the respective deuteron angular distributions were determined and the analysis is in progress. [1] K. Ikeda et al., Prog. Theor. Phys. Suppl. E 68, 464 (1968); H. Horiuchi, K. Ikeda, and Y. Suzuki, ibid. 44, 225 (1978). [2] M.R.D.Rodrigues et al., in12th International Conference on Nuclear Reaction Mechanism, Varenna, Italy, edited by F. Cerutti and A. Ferrari , CERN Proceedings, 2010-2, pp. 331- 335. [3] T. Borello-Lewin et al., Proceedings of SOTANCP2, Brussels, Belgium 2010, edited by P. Descouvemount et al., Int. J. Mod. Mod. Phys E 20, 1018-1021 (2011). [4] T. Borello-Lewin et

  6. Multi-elemental characterization of organic liquid samples by use of a 13 MeV 6Li3+ beam

    Evaporated amniotic fluid (AF) targets have been bombarded with a 13 MeV 6Li3+ 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.

  7. Evaluation of repulsive core parameters in heavy ion interactions from an analysis of the 6Li+28Si elastic scattering

    An attempt has been made to evaluate short-range repulsive core parameters in the potential of 6Li and 28Si nuclei interaction. The required data are obtained as a result of simultaneous analysis of experimental angular distributions of 6Li+28Si elastic scattering at the collision energy Esub(Li)=30 and 154 MeV. The evaluation calculations for Esub(Li)=5.8-154 MeV are performed. The relation of the repulsive core with the equation of nuclear matter state is discussed. From the analysis of experimental data on elastic scattering of 6Li+28Si at Esub(Li)=30 and 154 MeV an optical potential describing elastic scattering 30 MeV of 6Li+28Si in a wide angle range THETA <= 172 deg is obtained. The most specific peculiarity of the potential obtained is the presence of strong repulsion at short distances (r <= 3.5 f) between nuclei mass centres. It is shown that the parameters of the repulsive core obtained can be roughly evaluated using the equations of state of nuclear matter while the depth of the potential real part (approximately 30 MeV) is in qualitative agreement with some other approaches in which ion-ion interaction is calculated theoretically

  8. Direct measurements of the absorption and spin-dependent scattering of thermal neutrons by 6Li

    To describe the interaction of slow neutrons (s waves) with nuclei of non-zero spin I it is necessary to introduce four parameters: b+, b- (scattering length for bound nuclei) and sigma+sub(c), sigma-sub(c) (capture cross section), the indices + and - referring respectively to the two possible channels for the interaction: I+1/2 and I-1/2. Having introduced the formalism of slow neutron scattering by a polarized target it is shown how B=(b+-b-)/(2I+1) and (sigma+sub(c)-sigma-sub(c)) may be determined by two kinds of experiments: analysis of the transmission of a polarized neutron beam as a function of the target polarization, and the pseudo-magnetism measurements. The notions of spin temperature, thermodynamics spin reservoirs and phenomena of nuclear relaxation and dynamic polarization in solids are reviewed and the experimental equipment is described briefly. The methods are applied to the measurement of capture and spin-dependent scattering amplitude for 6Li nuclei on a polycrystalline metallic sample and a monocrystalline lithium fluoride sample. The values found are: b+-b-=(0.38+-0.05) 10-12cm and sigma+sub(c)-sigma-sub(c)=(-1190+-40w) barn

  9. Neutron total and scattering cross sections of 6Li in the few MeV region

    Neutron total cross sections of 6Li are measured from approx. 0.5 to approx. 4.8 MeV at intervals of 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;α)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

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

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

    2016-06-01

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