Yb Wei

Measurement of reaction cross section for proton-rich nuclei ( A< 30) at intermediate energies

Radioactive ion beams were produced through the projectile fragmentation induced by 69 MeV/nucleon Ar-36 primary beam on a Be-9\ target. Measurements of reaction cross sections (sigma(R)s) for 44 nuclei with A < 30 (mostly proton-rich), on carbon were performed on RIBLL (Radioactive Ion Beam Line in Lanzhou) of HIRFL (Heavy Ion Research Facility in Lanzhou) at intermediate energies around 30 MeV/nucleon by a transmission method. The experimental sigma(R) values for Al-23 and P-27 are abnormally large compared with their neighboring nuclei. Together with the previous experimental facts such as the binding energy and ground state data, it suggests anomalously large matter root-mean-square radii and proton halo structure in Al-23 and in P-27. There is an enhancement for the sigma(R) of F-17 + C-12 compared with the neighboring isotopes. Considering that the ground state of F-17 is 1d(5/2), this can indicate that there is a proton skin in F-17. The calculation of relativistic density-dependent Hartree model (RDDH) shows that the nuclei Al-23 and P-27 may have proton-halo structure and F-17 may have proton-skin structure. The significance of these measurements is discussed

Surveying the nucleon-nucleon momentum correlation function in the framework of quantum molecular dynamics model

Momentum correlation functions of nucleon-nucleon pairs are presented for reactions with C isotopes bombardinga 12 Ctargetwithintheframeworkoftheisospin-dependentquantummolecular dynamics model.The binding-energy dependence of the momentum correlation functions is also explored, and other factors that have an influence on momentum correlation functions are investigated. These factors include momentum-dependent nuclear equations of state, in-medium nucleon-nucleon cross sections, impact parameters, total pair momenta, and beam energy. In particular, the rise and the fall of the strength of momentum correlation functions at lower relative momentum are shown with an increase in beam energy.

Isoscaling behavior in fission dynamics

The fission processes of 112 Sn + 112 Sn and 116 Sn + 116 Sn are simulated with the combination of the Langevin equation and the statistical decay model. The masses of two fission fragments are given by assuming the process of symmetric fission or asymmetric fission by the Monte Carlo sampling with the Gaussian probability distribution. From the analysis to the isotopic/isotonic ratios of the fission fragments from both reactions, the isoscaling behavior has been observed and investigated

Exploring binding energy and separation energy dependences of HBT strength

Abstract Hanbury Brown–Twiss (HBT) results of the nucleon–nucleon correlation function have been presented for the nuclear reactions with neutron-rich projectiles (Be isotopes) using an event-generator, the Isospin-Dependent Quantum Molecular Dynamics model. We explore that the relationship between the binding energy per nucleon of the projectiles and the strength of the neutron–proton HBT at small relative momentum. Moreover, we reveal the relationship between the single neutron separation energy and the strength of the halo neutron–proton HBT. Results show that neutron–proton HBT results are sensitive to binding energy or separation energy.

Directed and elliptic flows in heavy ion collisions at intermediate energies

A theoretical investigation of directed and elliptic flows for different light particles and fragments in collisions of 40Ca + 40Ca and 112Sn + 112Sn is conducted below 100 MeV/nucleon in the isospin-dependent quantum molecular dynamics model. With increasing incident energy, the directed flow rises from negative to positive, while the elliptic flow decreases with the increasing incident energies. The directed flow for 40Ca + 40Ca system is not sensitive to the nuclear equation of states (EOS), but the directed flow for 112Sn + 112Sn system is sensitive to the EOS. However, the elliptic flows for both 40Ca + 40Ca and 112Sn + 112Sn systems are not sensitive to EOS. A study of the dependence of directed and elliptic flows on fragment charge (mass) is also performed. The information on EOS can be extracted by investigating the directed flow at intermediate energies when the combined mass is large or small.

Investigations on light proton-rich nuclei with exotic structure

Abstract One of the proton halo candidates 23Al and its isotopes are systematically investigated in the nonlinear Relativistic Mean-Field and Skyrme Hartree-Fock approaches. It is shown that there exists the energy inversion of ( 5 2 ) + (202) and ( 1 2 ) + (211) orbitals in 23Al nucleus and which may produce the large enhancement of reaction cross section comparing with its neighboring nuclei. Meanwhile, it is obvious to see that the isospin effect of the pairing correlation plays a great role to the separation energy when the Al isotopes approach to the proton drip line. In addition, the ground state and excited state of 9B, 13N are also investigated in the RMF model. There may exist the halo structure in 13N when the last proton of 13N occupies in the first excited state.

Nucleon-nucleon momentum correlation function for light nuclei

Nucleon-nucleon momentum correlation function have been presented for nuclear reactions with neutron-rich or proton-rich projectiles using a nuclear transport theory, namely Isospin-Dependent Quantum Molecular Dynamics model. The relationship between the binding energy of projectiles and the strength of proton-neutron correlation function at small relative momentum has been explored, while proton-proton correlation function shows its sensitivity to the proton density distribution. Those results show that nucleon-nucleon correlation function is useful to reflect some features of the neutron- or proton-halo nuclei and therefore provide a potential tool for the studies of radioactive beam physics.

Systematic studies of binding energy dependence of neutron-proton momentum correlation function

Hanbury Brown–Twiss (HBT) results of the neutron–proton correlation function have been systematically investigated for a series of nuclear reactions with light projectiles with the help of the isospin-dependent quantum molecular dynamics model. The relationship between the binding energy per nucleon of the projectiles and the strength of the neutron–proton HBT at small relative momentum has been obtained. Results show that neutron–proton HBT results are sensitive to the binding energy per nucleon.

Study of incident energy and isospin dependencies of total reaction cross section via the BUU model

The incident energy and isospin dependencies of total reaction cross sections sigma(R) have been researched by using the Boltzmann-Uehling-Uhlenbeck (BUU) model. When the width parameter of square-type or 140-type density distribution is obtained by fitting the sigma(R) at relativistic energies, the calculated result with BUU-model can reproduce the experimental data at intermediate energies better than that with Glauber-model of optical limit approximation. The systematical underestimation of sigma(R) at intermediate energy was removed out by BUU calculation framework. It is found that sigma(R) is sensitive to nuclear equation of state (EOS). It is also found that the difference factor (d) defined in text is sensitive to the nuclear structure such as neutron halo and neutron skin, etc

Δ-scaling and heat capacity in relativistic ion collisions

The Δ-scaling method has been applied to the total multiplicity distribution of the relativistic ion collisions of p+p, C+C and Pb+Pb which were simulated by a Monte Carlo package, LUCIAE 3.0. It is found that the Δ-scaling parameter decreases with increasing system size. Moreover, the heat capacities of different mesons and baryons have been extracted from the event-by-event temperature fluctuation in the region of low transverse mass and they shows the dropping trend with increasing impact parameter.