Chen Jin-Hui

Isoscaling of projectile-like fragments

In this paper, the isotopic and isotonic distributions of projectile fragmentation products have been simulated by a modified statistical abrasion–ablation model and the isoscaling behaviour of projectile-like fragments has been discussed. The isoscaling parameters α and β have been extracted respectively, for hot fragments before evaporation and cold fragments after evaporation. It looks that the evaporation has stronger effect on α than β. For cold fragments, a monotonic increase of α and |β| with the increase of Z and N is observed. The relation between isoscaling parameter and the change of isospin content is discussed.

Isoscaling Behaviour in the Isospin-Dependent Quantum Molecular Dynamics Model

The isoscaling behaviour is investigated in a frame of isospin-dependent quantum molecular dynamics models. The isotopic yields ratio Y2/Y1 for reactions 48Ca+48Ca and 40Ca+40Ca at different entrance channels are simulated and presented, the relationship between the isoscaling parameter and the entrance channel is analysed, the results show that α and β reduce with the rise of incident energies and increase with the impact parameter b, which can be attributed to the temperature varying of the pre-fragments in different entrance channels. The relation of α and symmetry-term coefficient Csym reveals that the chemical potential difference Δμ is sensitive to the symmetry-term coefficient Csym, and raises with the increasing Csym.

Hypertriton and light nuclei production at Λ-production subthreshold energy in heavy-ion collisions

High-energy heavy-ion collisions produce abundant hyperons and nucleons. A dynamical coalescence model coupled with the ART model is employed to study the production probabilities of light clusters, deuteron (d), triton (t), helion ((3)He), and hypertriton ((3)(A)H) at subthreshold energy of A production (approximate to 1 GeV per nucleon). We study the dependence on the reaction system size of the coalescence penalty factor per additional nucleon and entropy per nucleon. The Strangeness Population Factor (S(3) =(3)(A)H/((3)He x A/p)) shows an extra suppression of hypertriton comparing to light clusters of the same mass number. This model predicts a hypertriton production cross-section of a few mu b in (36)Ar+(36)Ar, (40)Ca+(40)Ca and (56)Ni+(56)Ni in 1 A GeV reactions. The production rate is as high as a few hypertritons per million collisions, which shows that the fixed-target heavy-ion collisions at CSR (Lanzhou/China) at A subthreshold energy are suitable for breaking new ground in hypernuclear physics.

One-Proton Halo Structure in 23Al

The Glauber theory is used to investigate the reaction cross section of proton-rich nucleus 23Al. A core plus a proton structure is assumed for 23Al. HO-type density distribution is used for the core while the density distribution for the valence proton is calculated by solving the eigenvalue problem of Woods–Saxon potential. The transparency function in an analytical expression is obtained by adopting multi-Gaussian expansion for the density distribution. Coulomb correction and finite-range interaction are introduced. This modified Glauber model is suitable for halo nuclei. A dominate s-wave is suggested for the last proton in 23Al from our analysis which is possible in the calculation of relativistic mean-field theory.

The Chinese High-Energy Photon Source and its R&D Project

Synchrotron radiation facilities are indispensable in numerous forefront areas. Until now, the electron energies of all photon sources in China have been in the medium- and low-energy regions. However, research related to national security and industrial innovation has demonstrated the urgent need for high-performance sources with high electron energy. For this purpose, a complex for advanced photon sciences in northern China has been planned since 2009 [1]. The complex is planned in three phases. In the first phase, a storage-ring-based, high-energy photon source (HEPS) with a beam energy of 5 GeV and emittance less than 1.0 nm•rad will be constructed, which can provide high-brilliance hard X-rays to several tens of experimental stations. In the second phase, a superconducting linac will be constructed to drive an X-ray free electron laser (XFEL), serving as an extension and compliment to the HEPS. In the third phase, as one possible performance upgrade scheme, the ring and the superconducting linac will be connected to form an energy recovery linac (ERL) system. The schematic drawing of the proposed photon science complex, including the three phases, is shown in Figure 1.

Strangeness by Thermal Model Simulation at RHIC

The local temperature effect on strangeness enhancement in relativistic heavy ion collisions is discussed in the framework of the thermal model in which the K+/h+ ratio becomes smaller with increasing freeze-out temperature. Considering that most strangeness particles of final-state particles are from the kaon meson, the temperature effect may play a role in strangeness production in hot dense matter where a slightly different temperature distribution in different areas could be produced by jet energy loss. This phenomenon is predicted by thermal model calculation at RHIC energy. The Ξ−/ ratio in central Au+Au collisions at 200 GeV from the thermal model depends on the freeze-out temperature obviously when γS is different. It should be one of the reasons why strangeness enhancements of Ξ and are different though they include two strange quarks. These results indicate that thermodynamics is an important factor for strangeness production and the strangeness enhancement phenomenon.

Investigation on the deformation of Ne and Mg isotope chains within relativistic mean-field model

Ne and Mg isotope chains are investigated based on constrained calculations in the framework of a deformed relativistic mean-field (RMF) model with the NL075 parameter set. The calculated quadrupole deformation and binding energy are compared with other theoretical results as well as the available experimental data. It shows that the calculated deformations of Ne and Mg with the NL075 are more accurate than those obtained with the NL-SH. It is predicted that 19,29,32Ne and 20,31Mg maybe have a triaxial deformation and 25−28Ne and 27−30Mg exhibit a shape coexistence probably. The closure effect of neutron number N=8 for 20Mg is predicted to be very weak.

Investigation of exotic structure of the largely deformed nucleus Al-23 in the relativistic-mean-field model

A candidate for proton halo nucleus 23Al is investigated based on the constrained calculations in the framework of the deformed relativistic mean field (RMF) model with the NL075 parameter set. It is shown by the constrained calculations that the ground state of 23Al has a large deformation that corresponds to the prolate shape. With that large deformation, the non-constrained RMF calculation predicts that there appears an inversion between the 2s1/2 [211] and 1d5/2 [202] shells. The valence proton of 23Al is weakly bound and occupies 2s1/2 [211] and 1d5/2 [202] with the weights of 56% and 29%, respectively. The calculated RMS radius for matter is in agreement with the experimental one. It is also predicted that the difference between the proton RMS radius and the neutron one is very large. This suggests that there exists a proton halo in 23Al.