Astrophysical Reaction Rates of the ^8Li（p, τ）^9Beg.s. Direct Capture Reaction

Based on the angular distribution of the ^8Li（d, n）^9Beg.s, reaction at Ec.m. = 8.0 MeV and distorted wave Born approximation analysis, the single particle spectroscopic factor S1,3/2 for the ground state of ^9Be = ^8Li×p is derived to be 0.64 ± 0.21. In addition, we deduce the astrophysical S-factors and rates of the ^8Li（p, γ）^9Beg.s. direct capture reaction at energies of astrophysical interests.     

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

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 ^9Be（^6He,^7 Li）^8Li. 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 ^7Li and ^8Li.     

试用特洛伊木马方法研究天体核反应9Be（p，α）6Li

为克服低能带电粒子核反应截面直接测量中所遇到的库仑位垒和电子屏蔽效应带来的困难，试用基于准自由反应机制的特洛伊木马方法，在意大利南部国家核物理实验室的15MV串列加速器上，通过^2H（^9Be，α^6Li）n核反应对^9Be（p，α）^6Li在低能区（Ecm=0-1000kev）的裸核反应截面做了间接测量，并将测量结果与直接测量数据进行了比较。The beryllium abundance acts as a key role for understanding the inhomogeneous Big Bang nucleosynthesis. In order to measure the ^9Be（p, α）^6Li bare nucleus cross section and S（E） factor at astrophysical energies, the Trojan Horse Method （THM） can be applied. The main feature of the method is that it allows to extract the energy dependence for the astrophysical S（E） factor of bare nuclei at very low energies without any extrapolation, by measuring the cross section of an appropriate three body process. Thus the ^9Be （p,α）^6Li has been studied by means of the THM applied to the ^2H（^9Be,α^6Li）n at INFN-LNS, Catania, Italy. The two body reaction cross section has been studied in the energy range of Ecm=0-1 000 keV. Preliminary results are discussed and a comparison with direct data is made.     

Measurement of Angular Distribution for the ^8Li（p,d）^7Li Reaction

The ^8Li（p, d）^7 Li reaction plays an important role in the inhomogeneous Big Bang nucleosynthesis and in the seed-nuclide production phase for the r-process. For the first time, its angular distribution at backward angles was measured in inverse kinematics at Ec.m.=4.0 MeV by using an ^8Li secondary beam. The result of measurement includes the contributions of ^8Li（p, d0）^7Li and ^8Li（p, d1）^7Li^＊. The ^8Li（p, d0）^7Li component is estimated to be 40%-58% in the mixture angular distribution by analysing the measured result.     

Asymptotic Normalization Coefficient of ^27P → ^26Si ＋ p and Radius of ^27P Halo

The asymptotic normalization coefficient of the virtual decay ^27P → ^26Si ＋ p is extracted to be 1840 ± 240 fm^-1 from the peripheral ^26Mg（d,p）^27Mg reaction using charge symmetry of mirror pair, for the first time. It is then used to derive the rms radius of the valence proton in the ground state of ^27P. We obtain the rms radius （γ^2〉^1/2 = 4.57 ± 0.36 fm, significantly larger than the matter radius of ^27P. The probability of the valence proton outside the matter radius of ^27P is found to be 73%. The present work supports the conclusion that the ^27p ground state has a proton halo structure.     

Neutron Spectroscopic Factors of ^7Li and Astrophysical ^6Li（n,γ）^7Li Reaction Rates

Angular distributions of the ^7Li（^6Li, ^6Li）^7Li elastic scattering and the ^7Li（^6Li, ^7Lig.s.）^6Li, ^7Li（^6Li, ^7Li0.48）^6Li transfer reactions at Ec.m. = 23.7 MeV are measured with the Q3D magnetic spectrograph. The optical potential of ^6Li ＋ ^7Li is obtained by fitting the elastic scattering differential cross sections. Based on the distorted wave Born approximation （DWBA） analysis, spectroscopic factors of ^7Li =^6Li n are determined to be 0.73 ± 0.05 and 0.90 ± 0.09 for the ground and first exited states in ^7Li, respectively. Using the spectroscopic factors, the cross sections of the ^6 Li（n, γ0,1）^7 Li direct neutron capture reactions and the astrophysical ^6Li（n, γ）^7 Li reaction rates are derived.     

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

Neutron beam optimization for accelerator-based Boron Neutron Capture Therapy（BNCT） is investigated using a ^7Li（p,n）^7Be reaction. Design and optimization have been carried out for the target, cooling system,moderator, filter, reflector, and collimator to achieve a high flux of epithermal neutron and satisfy the IAEA criteria.Also, the performance of the designed beam in tissue is assessed by using a simulated Snyder head phantom. The results show that the optimization of the collimator and reflector is critical to finding the best neutron beam based on the ^7Li（p,n）^7Be reaction. Our designed beam has 2.49×109n/cm^2 s epithermal neutron flux and is suitable for BNCT of deep-seated brain tumors.     

Search for the Halo Effect in the ^1H（^6He,^6Li）n Reaction

The angular distributions of the charge exchange reaction ^1H(^6He,^6Li)n were measured in reverse kinematics with a secondary ^6He beam at the energy of 4.17 A MeV.The data were analysed in the context of a microscopic calculation.It is shown that both the ground state of ^6He and the second excited state of ^6Li(3.563MeV,0^ ) have a halo structure.     

Radius of ^9C from the Asymptotic Normalization Coefficient

The asymptotic normalization coefficient (ANC) of^9C=^8B p deduced from S Li(d, p)^9 Li reaction is used to obtain the root-mean-square (rms) radius of the loosely bound proton in the ^9C ground state. We obtain (r^2)1/2 = 3.61 fm for the valence proton, which is significantly larger than the matter radius of ^9C. The probability of the valence proton outside the matter radius of ^9C is greater than 60%. The present work supports the conclusion that ^9C has a proton halo structure.     

Halo Structure of Nucleus ^23Al

The recently measured reaction cross section of ^23Al is analysed in the Glauber model with an optical limit or few-body approach.It is found that the conventional fixed core-plus-nucleon model for halo nuclei is unable to explain the observed abnormally large reaction cross section of ^23Al by any selection of the halo nucleon configurations.The reaction cross section of ^23Al can be described when the core size is enlarged,although the Coulomb barrier lagely hinders the formation of a halo sturcture for proton-rich nuclei.This is consistent with the case in s-d shell neutron-rich nuclei,where an enlarged core was proposed to explain both the reaction cross section and longitudinal momentum distribution data.     

The Main Path to C, N, O Elements in Big Bang Nucleosynthesis

The production of C, N, O elements in a standard big bang nucleosynthesis scenario is investigated. Using the up-to-date data of nuclear reactions in BBN, in particular the ^8Li （n,γ） ^9Li which has been measured in China Institute of Atomic Energy, a full nucleosynthesis network calculation of BBN is carried out. Our calculation results show that the abundance of 12 C is increased for an order of magnitude after addition of the reaction chain ^8Li（n,γ） ^9Li（α,n） ^12B（β） ^12C, which was neglected in previous studies. We find that this sequence provides the main channel to convert the light elements into C, N, O in standard BBN.     

Deuteron inelastic scattering on 6Li and 7Li nuclei within the three-body cluster model

The problem of the deuteron interaction with lithium nuclei,treated as a system of two coupled pointlike clusters,is formulated to calculate the cross sections of the d+Li reaction.The d+Li reaction mechanism is described using the Faddeev theory for the three-body problem of deuteron-nucleus interaction.This theory is slightly extended for calculation of the stripping processes ^6Li(d,p)^7Li,^7Li(d,p)^8 ,^6Li(d,n)^7 Be,and ^7Li(d,n)^8 Be,as well as fragmentation reactions yielding tritium,a-particles,and continuous neutrons and protons in the initial deuteron kineticenergy region Ed=0.5-20 MeV.The phase shifts found for d+^6Li and d+^7Li elastic scattering,as part of the simple optic model with a complex central potential,were used to find the cross sections for the 6^Li(d,yM)^8 and ^7Li(d,yE1)^9 Be radiation captures.The three-body dynamics role is also summarized to demonstrate its significant influence within the d+^7Li system.     

Isospin effect of the in-medium nucleon-nucleon cross section in excited nuclear reactions

Using relativistic mean field theory, the neutron and the proton density distribution of 56Ni nuclei could be obtained in the ground state and the excited state. Based on the framework of the quantum molecular dynamics model, the 56Ni nuclei have been simulated in ground state and in the neutron or proton excited state. We then used the three different states of 56Ni to collide with the 56Ni in the ground state. To discuss the evolution of the nuclear stopping in different reactions, two kinds of different excited nuclear reactions were studied at different reaction energies and at different impact parameters. Studies have shown that the nuclear stopping of an excited nuclear reaction is sensitive to the isospin-dependent in-medium nucleon-nucleon cross section, compared with the response value of the ground state nuclear reaction. So, it is better for the excited nuclei to extract the isospin dependence of nucleon-nucleon cross section information.     

Influence of D-state in 4He on S Factor for the 2H（d, γ）^4He Reaction

We employ a direct capture method to study the influence of D-state in ^4He on S factor for the ^2H（d,γ）^4He reaction, in which the D-state component of the colliding deuterons and D-state component in ^4He ground state are considered. The parameters of Woods-Saxon （WS） potentials are obtained by reproducing the binding energy of d-d （i.e. ^2H-^2H） system, and d-d elastic scattering phase shifts calculated by the resonating group method. The theoretical results are in good agreement with the experimental data at Ec.m〈 3 MeV. The impact of the D state probability in ^4He on the extrapolated value of the astrophysical S factor for ^2H（d, γ）^4He reaction is discussed.     

Description of ^178Hf^m2 in the Constrained Relativistic Mean Field Theory

Properties of the ground state of ^178Hf and the isomeric state ^178Hf^m2 are studied within the adiabatic and diabatie constrained relativistic mean field （RMF） approaches. The RMF calculations reproduce well the binding energy and the deformation for the ground state of ^178Hf. Using the ground state single-particle eigenvalues obtained in the present eaiculation, the lowest excitation configuration with K^π = 16^＋ is found to be v（7/2^-[514]）^-1（9/2^＋ [624]）^1 π（7/2^＋ [404]）^-1 （9/2^-[514]）^1. Its excitation energy caiculated by the RMF theory with time-odd fields taken into account is equal to 2.801 MeV, i.e., close to the ^178Hf^m2 experimentai excitation energy 2.446 MeV. The self-consistent procedure accounting for the time-odd component of the meson fields is the most important aspect of the present calculation.     

Theoretical Analysis of Neutron Double-Differential Cross Sections of n ＋^9Be Reactions

By using the nuclear reaction model for light nuclei, the calculations of the double-differential cross sections of outgoing neutrons from n ＋^9Be reactions are performed. The total outgoing neutrons are only come from the （n, 2n）2a reaction channel. The （n, 2n）2a reaction channel is achieved through six different reaction approach, which are illustrated in this paper. The calculated results agree very well with the measured data at En = 7.1, 8.09, 8.17, 9.09, 9.97 and 10.26 MeV, because the updated level schemes related to the n ＋ ^9Be reactions have been employed in this calculations.     

Stereodynamics of the O（^3p） with H： （D2） （v = O,j =O） reaction

Quasi-classical trajectory theory is used to study the reaction of O（3p） with H2 （D2） based on the ground 3A″ potential energy surface （PES）. The reaction cross section of the reaction O＋H2→＋OH＋H is in excellent agreement with the previous result. Vector correlations, product rotational alignment parameters （P2（j′. k）） and several polarizeddependent differential cross sections are further calculated for the reaction. The product polarization distribution exhibits different characteristics that can be ascribed to different motion paths on the PES, arising from various collision energies or mass factors.     

Isospin effect of the in-medium nucleon-nucleon cross section in excited nuclear reactions

Using relativistic mean field theory, the neutron and the proton density distribution of ⁵⁶Ni nuclei could be obtained in the ground state and the excited state. Based on the framework of the quantum molecular dynamics model, the ⁵⁶Ni nuclei have been simulated in ground state and in the neutron or proton excited state. We then used the three different states of ⁵⁶Ni to collide with the ⁵⁶Ni in the ground state. To discuss the evolution of the nuclear stopping in different reactions, two kinds of different excited nuclear reactions were studied at different reaction energies and at different impact parameters. Studies have shown that the nuclear stopping of an excited nuclear reaction is sensitive to the isospin-dependent in-medium nucleon-nucleon cross section, compared with the response value of the ground state nuclear reaction. So, it is better for the excited nuclei to extract the isospin dependence of nucleon-nucleon cross section information.     

^106,110Pd （p,nγ）^106,110 Ag reactions at Ep = 6.0 - 7.7 MeV

This paper reports that the experimental excitation functions of reaction （p,n） are measured for ^106pd and ^110pd at proton energy Ep = 6.1 - 7.5 MeV and Ep = 6.0 - 7.7 MeV respectively. The off-resonance excitation functions were compared with calculation values of the statistical model. A new formula used to estimate the peak cross section of isobaric analogue resonance was tested and it was found that calculation values agree reasonably well with the present data within experimental error, which confirms that the excitation strength of isobaric analogue state in （p,n） reaction not only depends on its spin, but also proportionally increases with the projectile proton spatial transmission Tp and the spectroscopic factor S for reaction （d,p） on the same target.     

Spin polarization effect for Os2 molecule

Density functional Theory （DFT） （B3p86） of Gaussian03 has been used to optimize the structure of Os2 molecule. The result shows that the ground state for Os2 molecule is 9-multiple state and its electronic configuration is ^9∑^＋g, which shows spin polarization effect of Os2 molecule of transition metal elements for the first time. Meanwhile, we have not found any spin pollution because the wavefunction of the ground state does not mingle with wavefunctions with higher energy states. So, the fact that the ground state for Os2 molecule is a 9-multiple state is indicative of spin polarization effect of Os2 molecule of transition metal elements. That is, there exist 8 parallel spin electrons. The non-conjugated electron is greatest in number. These electrons occupy different spacious tracks, so that the energy of Os2 molecule is minimized. It can be concluded that the effect of parallel spin of Os2 molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell-Sorbie potential functions with the parameters for the ground state ^9∑^＋g and other states of Os2 molecule are derived. Dissociation energy De for the ground state of Os2 molecule is 3.3971eV, equilibrium bond length Re is 0.2403nm, vibration frequency ωe is 235.32cm^-1. Its force constants f2, f3, and f4 are 3.1032×10^2aJ·nm^-2, -14.3425×10^3aJ·nm^-3 and 50.5792×10^4aJ·nm^-4 respectively. The other spectroscopic data for the ground state of Os2 molecule ωexe, Be and ae are 0.4277cm^- 1, 0.0307cm^- 1 and 0.6491 × 10^-4cm^-1 respectively.