Zhao Wei-Juan

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.

Proton induced X-ray emission (PIXE) analysis of sources of porcelain body of Ru Guan and Jun Guan porcelains

Abstract34 samples of Ru Guan porcelain body and 50 samples of Jun Guan porcelain body (both kinds being in different body colors) were selected with the purpose of finding out the source of raw materials and their classification relationship so as to search for ways of non-destructive discrimination. Proton induced X-ray emission (PIXE) has been applied to these samples to determine their chemical elements. The data of seven major chemical elements collected from these samples were further studied through fuzzy cluster analysis. Results indicate that the origin of raw materials of Jun Guan porcelain body samples is comparatively more concentrated in certain places, while that of Ru Guan porcelain body samples is scattered about. The places of origin of raw materials of the majority of Ru Guan and Jun Guan porcelain body samples have something in common, but some differences still exist. It might be an important way for non-destructive discrimination among Ru Guan and Jun Guan porcelains by combining PIXE with fuzzy cluster analysis.

Observation of a Possible New Isomer in 175 Ir

The neutron deficient nuclide 175Ir was produced by irradiation of 146Nd with 210 MeV 35Cl via a fusion-evaporation reaction channel. The reaction products were transported to a low-background location using a helium-jet recoil fast-moving tape-transport system for measurement. The experimental devices and data analysis method are introduced. Based on the decay-curve fitting of the β-delayed γ ray from 175Ir, realized by the least-square method, a new long-lived isomeric state of Ir is proposed and briefly discussed.

Production cross sections of the superheavy nucleus 117 based on the dinuclear system model

Within the framework of the dinuclear system model, the capture of two colliding nuclei, and the formation and de-excitation process of a compound nucleus are described by using an empirical coupled channel model, solving the master equation numerically and the statistical evaporation model, respectively. In the process of heavy-ion capture and fusion to synthesize superheavy nuclei, the barrier distribution function is introduced and averaging collision orientations are considered. Based on this model, the production cross sections of the cold fusion system 76–82Se+209Bi and the hot fusion systems 55Mn+238U, 51V+244Pu, 59Co+232Th,48Ca+247–249 Bk and 45Sc+246–248 Cm are calculated. The isotopic dependence of the largest production cross sections is analyzed briefly, and the optimal projectile-target combination and excitation energy of the 1n-4n evaporation channels are proposed. It is shown that the hot fusion systems 48Ca+247–249 Bk in the 3n evaporation channels and 45Sc+248Cm in the 2n-4n channels are optimal for synthesizing the superheavy element 117.

Investigation of add-back effects in a segmented Clover detector

The resolution and the summing characteristics of an EXOGAM segmented Clover germanium detector has been studied for use it in γ spectroscopic experiments. The measurements have been performed with standard radioactive sources of 152Eu, 133Ba and β-delayed γ-rays from 176Ir decay. The data analytic results, realized by software, are presented in this paper.

Main chemical ingredients of the celadon glaze from Qingliangsi kiln and Zhanggongxiang kiln

The proton induced X-ray emission (PIXE) is used to determine the chemical ingredients of seven main elements in the samples of Ru Guan porcelain glazes and Ru Civil porcelain from Qingliangsi kiln in Baofeng County and the samples of celadon glaze from Zhanggongxiang kiln in Ruzhou City. The PIXE data are then analyzed by scatter analysis and fuzzy cluster method for determining their classification and provenance. The results show that there are obvious differences between the ingredients of glaze material of Ru Guan porcelain and Ru Civil porcelain from Qingliangsi kiln, of which the former ingredients are stable and its source is localized, and that the sources and ingredients of the glaze of Ru Guan porcelain and those of celadon glaze from Zhanggongxiang kiln are not wholly the same, of which the latter sources are much scattering.

Systematic study of the heavy-ion fusion dynamics at near-barrier energies

In recent decades, the study of capture and fusion dynamics in heavy-ion collisions has been a subject of intense experimental and theoretical interests because the heavy-ion capture not only is of central importance for nucleosynthesis but also can reveal rich interplay between nuclear structure and reaction dynamics. Theoretically, the heavy-ion capture and fusion processes at energies near the Coulomb barrier can be treated as a multidimensional barrier penetration problem. The multidimensional barrier penetration process can be described by solving the coupled-channel equations, i.e., the coupled-channel (CC) model. However, for heavy reaction systems, it is necessary to take into account a large number of channels which is not easy to realize in the CC model. Moreover, the structure information of the interacting nuclei are needed as inputs. Therefore, full CC calculations become intractable in many cases including many fusion reactions leading to superheavy nuclei. On the other hand, in the eigenchannel framework, the couplings to other channels split the single potential barrier into a set of discrete barriers. Based on the concept of the barrier distribution, several empirical CC approaches have been developed. Recently, we have developed an empirical coupled-channel (ECC) model and performed a systematic study of capture excitation functions for 220 reaction systems. In this ECC model, an asymmetric Gaussian-form barrier distribution function was used to take effectively into account the effects of inelastic excitation couplings and neutron transfer coupling. Based on the interaction potential between the projectile and the target, empirical formulas were proposed for the parameters of the barrier distribution according to the static and dynamical deformations of the two colliding nuclei. For the vibrational coupling effect and the rotational coupling effect, the parameters of the empirical formulas were given, respectively. For spherical reaction systems (vibrational coupling effect), the width of the barrier distribution increases with the charge product of the reaction system, while for the deformed reaction systems (rotational coupling effect), besides the charge product of the reaction system, the width of the barrier distribution is also related to the static deformation parameters of the projectile and the target. For some reaction systems, the coupling effects of the positive Q -value neutron transfer (PQNT) channels are needed to explain the enhancement of sub-barrier capture cross sections. In this ECC model, the effects of PQNT are simulated by broadening the barrier distribution. Moreover, the positive Q value for one neutron pair transfer is used to broaden the barrier distribution in the present model. Among these 220 reaction systems, there are 89 systems with positive Q value for one neutron pair transfer channel. The calculated capture cross sections of most of these 89 reaction systems are in good agreement with the experimental values, which implies that the Q value for one neutron pair transfer is very important to understanding of the coupling to PQNT channels. Generally speaking, the ECC model together with the empirical formulas for parameters of the barrier distribution works quite well in the description of the capture cross sections at near-barrier energies. This model can provide useful information on capture dynamics and predictions of capture cross sections for the synthesis of superheavy nuclei. In the present paper, we will review this ECC model and its applications.

Astrophysical Rates for the 6He(p, γ)7Li Reaction

Angular distribution of the 6He(d,n)7Li reaction at Ec.m.=9.1 MeV is measured in inverse kinematics for the first time. The proton spectroscopic factors for the ground and first excited states of 7Li are derived by using the distorted wave Born approximation analysis. The astrophysical rates of 6He(p, ?)7Li reaction are then deduced and fitted with an expression of REACLIB.

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

Angular distribution of the 12C(6He, 7Li)11B transfer reaction is measured with a secondary 6He beam of 36.4 MeV for the first time. The experimental angular distribution is well reproduced by the distorted-wave Born approximation (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), Beijing.