The proton resonant properties in 18Ne, which determine the reaction rate of the key stellar 14O(α,p)17F reaction, have been studied by using a technique of proton resonant elastic scattering of 17F+p. A 4.22 MeV/nucleon 17F radioactive ion (RI) beam was produced via a projectile-fragmentation reaction, and separated by a Radioactive Ion Beam Line in Lanzhou (RIBLL). By bombarding a thick (CH2)n target, the energy spectra of the recoiled protons were measured by two ΔE-E silicon telescopes at the center-of-mass scattering angles of θc.m.≈175°±5°, θc.m.≈152°±8°, respectively. Several proton resonances in 18Ne were ob served clearly. A further R-matrix analysis of the experimental data is under way to determine the resonant parameters. The present work reports the preliminary results briefly.
HE JianJun1, HU Jun1,2, XU ShiWei1, CHEN ZhiQiang1, ZHANG XueYing1, WANG JianSong1, YU XiangQing1, ZHANG LiYong1,2, LI Long1,2, YANG YanYun1,2, MA Peng1,2, ZHANG XueHeng1, HU ZhengGuo1, GUO ZhongYan1, XU Xing1,2, YUAN XiaoHua1, LU Wan1,2, YU YuHong1, ZANG YongDong1,2, TANG ShuWen1,2, YE RuiPing1,2, CHEN JinDa1,2, JIN ShiLun1,2, DU ChengMing1,2, WANG ShiTao1,2, MA JunBing1,2, LIU LongXiang1,2, BAI Zhen1,2, LEI XiangGuo1, SUN ZhiYu1, ZHANG YuHu1, ZHOU XiaoHong1, XU HuShan1, SU Jun3, LI ErTao3, WANG HongWei4, TIAN WenDong4 & LI XiangQing5 1 Institute of Modern Physics (IMP), Chinese Academy of Sciences, Lanzhou 730000, China
Lithium isotopes have attracted an intense interest because the abundance of both 6Li and 6Li from big bang nucleosynthesis (BBN) is one of the puzzles in nuclear astrophysics. Many investigations of both astrophysical observation and nucleosynthesis calculation have been carried out to solve the puzzle, but it is not solved yet. Several nuclear reactions involving lithium have been indirectly measured at China Institute of Atomic Energy, Beijing. The Standard BBN (SBBN) network calculations are then performed to investigate the primordial Lithium abundance. The result shows that these nuclear reactions have minimal effect on the SBBN abundances of 6Li and 7Li.
LI ZhiHong1, LI ErTao1, SU Jun1, LI YunJu1, BAI XiXiang1, GUO Bing1, WANG YouBao1, CHEN YongShou1, HOU SuQing1, ZENG Sheng1, LIAN Gang1, SHI JianRong2 & LIU WeiPing1 1 China Institute of Atomic Energy, Beijing 102413, China
Relativistic corrections to the reaction kinematic parameters were made for elastic scattering of6Li,12C and40Ar from40Ca,90Zr and208Pb targets at incident energies between 20 and 100 MeV/nucleon.The results of optical model calculations show that the efects of such corrections are important when describing the angular distributions of elastic scattering cross sections for heavy ion scattering at incident energies as low as around40 MeV/nucleon.The efects on the total reaction cross sections on the other hand,were found to be small within the energy range studied when the optical model potential is fixed.
The post-AGB star J004441 is the first and the only one CEMP-r/s star found in SMC.Herein,we investigate the observed abundance pattern of the heavy elements using our parametric model.A consistent fitting results was obtained for the sample star.Based on the low r=0.08,the s-process nucleosynthesis occurred in the interior is supposed to belong to the single neutron-exposure event.The median value ofτ0=0.44(T90.348)1/2mbarn-1supports a higher efficiency of the s-process nucleosynthesis relative to J004441 than that of the solar system,however,the value is not sufficiently high to favor the formation of a lead star.Thus,J004441does not belong to lead star group.The large Csvalue of J004441 supports the intrinsic characteristic of the s-enrichment.The Crvalue is similar with that found in halo CEMP-r/s stars,which indicates that the r-process contributions is critical during heavy element enrichment.This star has a metallicity of[Fe/H]=-1.34,which is larger than that of Galaxy halo CEMP-r/s stars.The reason may be because of the different history of metallicity enrichment between the SMC and the Galaxy halo.
The projected total energy surface(PTES)approach has been developed based on the triaxial projected shell model(TPSM)hybridized with the macroscopic–microscopic method.The total energy of an atomic nucleus is decomposed into macroscopic,microscopic and rotational terms.The macroscopic and microscopic components are described with the liquid drop model and Strutinsky method,respectively,and the rotational energy is given by the TPSM,the term beyond the mean field.To test theory,the PTES calculations have been carried out for the yrast states of the well deformed rare earth nucleus172W,and the theoretical results are in good agreement with the experimental data.By using the equilibrium quardrupole deformations(ε2andγ)determined by the PTES,the calculation of the transition quardrupole moment(Qt)in function of spin also reproduces the experimental data.A comparison between the PTES and TRS methods has been made for theoretical and application uses.
The 13C(α,n)16O reaction is believed to be the main neutron source reaction for the s-process in asymptotic giant branch (AGB) stars. The astrophysical S-factors of this reaction have been determined based on an evaluation of the α spectroscopic factor of the 1/2+ subthreshold state in 17O (Ex=6.356 MeV) by using the 13C(11B,7Li)17O α transfer reaction. Our result confirms that the 1/2+ subthreshold resonance is dominant for the 13C(α,n)16O reaction at low energies of astrophysical interest.
The angular distribution of 1 H( 6 He,p) 6 He elastic scattering has been measured at E c.m. = 4.3 MeV by using a thick-target inverse kinematic method. The experimental differential cross sections are reproduced by the distorted-wave Born approximation calculation utilizing the CH89 global optical potential parameter set. The real part of CH89 is reduced comparing with other potentials, which may be attributed to the couplings necessary for the weakly bound nuclei.
Fusion reactions play a very important role for the creation of heavier elements in the quiescent and explosive burning phases in stars.Fusion processes also generate the energy in the Sun that created and maintain life in our earth[1].
