Li Zhi-Hong

A program for SAXS data processing and analysis

A computer program for small angle X-ray scattering (SAXS) data processing and analysis named S.exe written in Intel Visual Fortran has been developed. This paper briefly introduces its main theory and function.A computer program for small angle X-ray scattering (SAXS) data processing and analysis named S.exe written in Intel Visual Fortran has been developed. This paper briefly introduces its main theory and function.

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

The 8Li(p, d)7Li 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.

Levels in 13N examined by 12C+p elastic resonance scattering with thick target*

The elastic resonance scattering of 12C+p has been studied in inverse kinematics via a novel thick target method at GIRAFFE facility of HI-13 tandem accelerator laboratory, Beijing. The recoil protons were measured by a ΔE-E counter telescope based on a large area double-sided silicon strip detector at laboratory angles around θ0 = 15°. The excitation function for 12C(p,p) elastic scattering has been obtained over a wide energy range of Ec.m.=0.31–3.45 MeV, which was explained quite well by the R-matrix calculation with known resonance parameters of the first three levels in 13N nucleus. Thus it is demonstrated that the present setup can be directly applied to the study of elastic resonance scattering with secondary radioactive beams.

Enhancement of β+-Decay Rate of 22Na in Metal Pd at Low Temperature

Temperature dependence of nuclear decays in metallic environments is a controversial issue. We measured the temperature dependence of the β+-decay half-life of22Na implanted into the metal host of palladium. It is found that the β+ -decay half-life of22Na in the metal Pd cooled to T = 15 K is shorter by 0.46(14)% than that at room temperature. The result is consistent in sign with, but clearly smaller than, the estimated one by the Debye model.

New Measurement of Proton Transfer Reactions and Elastic Scattering for 7Li + 13C at 34 MeV

The 13C(7Li, 6He)14N reaction is measured at E(7Li) = 34 MeV with the Q3D magnetic spectrometer of HI-13 tandem accelerator. Angular distributions at forward angles for proton transfer to the ground and the first excited states in 14N are obtained. In addition, angular distribution for 7Li + 13C elastic scattering is also measured. The optical potential parameters for the entrance and exit channels of the transfer reactions are derived by fitting the 7Li + 13C and 6Li + 14N elastic scattering experimental data, and their angular distributions are well reproduced by the distorted wave Born approximation calculations. A phase shift of about 2° between the calculations and the experiment data has been found in the earlier (7Li, 6He) study, whereas no such phase shift is observed in the present work.

Calculation of astrophysical reaction rate of82Ge(n,γ)83Ge

The neutron capture reaction on a neutron-rich near closed-shell nucleus 82Ge may play an important role in the r-process following the fallout from nuclear statistical equilibrium in core-collapse supernovae. By carrying out a DWBA analysis for the experimental angular distribution of 82Ge(d, p)83Ge reaction we obtain the single particle spectroscopic factors, S2,5/2 and S0,1/2 for the ground and first excited states of 83Ge = 82Ge?n, respectively. And then these spectroscopic factors are used to calculate the direct capture cross sections for the 82Ge(n, ?)83Ge reaction at energies of astrophysical interest. The optical potential for neutron scattering on unstable nucleus 82Ge is not known experimentally. We employed a real folding potential which was calculated by using the proper 82Ge density distribution and an effective nucleon-nucleon force DDM3Y. The neutron capture reactions on neutron-rich closed-shell nuclei are expected to be dominated by the direct capture to bound states. We will show that the direct capture rates on these nuclei are sensitive to the structure of the low-lying states.

Simulation and analysis of 13N+p elastic resonance scattering

The 13 N+p elastic resonance scattering has been studied at the secondary radioactive beam facility of CIAE in inverse kinematics via a thick-target method. The excitation function for the 13 N(p,p) scattering was obtained in the energy interval of Ecm 0.5|3.2 MeV with a 13 N secondary beam of (47:8 1:5) MeV. Careful analysis of the secondary beam components and extensive Monte-Carlo simulations enable the resolution of the experimental proton spectra. The resonance parameters for v e low-lying levels in 14 O were deduced by R- matrix tting calculations with MULTI7 and SAMMY-M6-BETA. The present results show general agreement with those from a recent similar work, and thus conrm the observation of a new 0 level at 5.7 MeV in 14 O with an improved width of 400(45) keV.

Determination of Astrophysical 13N(p,γ)14O S-factors from the Asymptotic Normalization Coefficient of 14C → 13C + n

The angular distribution of the 13C(d,p)14C reaction is reanalysed using the Johnson–Soper approach. The squared asymptotic normalization coefficient (ANC) of virtual decay 14C → 13C + n is then derived to be 21.4±5.0 fm−1. The squared ANC and spectroscopic factor (SF) of 14O → 13N + p are extracted to be 30.4±7.1 fm−1 and 1.94±0.45, respectively. The astrophysical S-factors and reaction rates of 13N(p,γ)14O are determined from the ANC of 14O → 13N + p using the R-matrix approach.

Determination of the Astrophysical S(E) Factors or Rates for Radiative Capture Reaction with One Nucleon Transfer Reaction

The radiative capture reaction plays an important role in nuclear astrophysics. We have indirectly measured the astrophysical S(E) factors for some proton capture reactions and reaction rates for several neutron capture reactions with one nucleon transfer reactions at HI-13 tandem accelerator in recent years. Some of them are compiled into IAEA EXFOR database and JINA REACLIB project, and used in the network calculations of Big Bang nucleosynthesis and type-I X-ray bursts.

Indirect Measurement of Astrophysical 13C(α, n)16O S-Factors

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.