Effects of Neutron Skin Thickness in Peripheral Nuclear Reactions

Effects of neutron skin thickness in peripheral nuclear collisions are investigated using the statistical abrasion ablation (SAA) model. The reaction cross section, neutron (proton) removal cross section, one-neutron (proton) removal cross section as well as their ratios for nuclei with different neutron skin thickness are studied. It is demonstrated that there are good linear correlations between these observables and the neutron skin thickness for neutron-rich nuclei. The ratio between the (one-)neutron and proton removal cross section is found to be the most sensitive observable of neutron skin thickness. Analysis shows that the relative increase of this ratio could be used to determine the neutron skin size in neutron-rich nuclei.

Measurements of Total Reaction Cross Sections for Exotic Nuclei Close to the Proton Drip-line at Intermediate Energies and Observation of a Proton Halo in ^(27)P

Measurements of total reaction cross sections(σR)for some proton-rich nuclei(N=11-15 isotones)on carbon target at intermediate energies have been performed on the Radioactive Ion Beam Line of the Heavy Ion Research Facility in Lanzhou.A large enhancement ofσR for ^(27)P has been observed than for its neighbors.Evidence for a proton halo in ^(27)P has been revealed in the Glauber analysis of the total reaction cross sections in terms of the difference factor d.

The influence of Multi-Step Sequential Decay on Isoscaling and Fragment Isospin Distribution in GEMINI Simulation

Extensive calculations on isoscaling behavior with the sequential-decay model GEMINI are performed for the mediate-heavy nuclei in the mass range A=110 and at excitation energies of up to 3 MeV per nucleon.Isoscaling can still be observed after entire−step decays are considered for the light products as in the only first-step decay process case.Comparison between the products after the first-step decay and the ones after entire-step decay demonstrates that multi-step secondary sequential decay strongly influences the isoscaling parametersα,βas well as the fragment isospin distribution.After entire−step decays,the isoscaling parametersαandβare decreased and the fragment isospin distribution can better reproduce the isospin distribution shape as the experimental data.

Directed and Elliptic Flows in ^(112)Sn+^(112)Sn Collisions

The directed and elliptic flow in collisions of ^(112)Sn+^(112)Sn at energies from 35 to 90 MeV/nucleon are studied in an isospin-dependent quantum molecule dynamics model.With increasing incident energy,the directed flow rises from negative to positive.Its magnitude depends on the nuclear equation of state(EOS).However,the elliptic flow decreases with increasing incident energy and its magnitude is not very sensible to EOS.Systematic studies of the impact parameter dependence and the cluster mass dependence are also performed.The study of directed flow at intermediate energies thus provides a means of extracting the information on the nuclear equation of state.

Total Reaction Cross Section Measurements at Intermediate Energy for the Proton Halo Candidate ^(23)Al and Its Neighbours

Total reaction cross sections σR for some proton-rich isotones (N = 10) near ^(23)Al on a carbon target have been measured at intermediate energies in the experiment performed at the Radioactive Ion Beam Line of the Heavy Ion Research Facility in Lanzhou. The Z-dependence of σR shows a remarkable enhancement for ^(23)Al relative to its neighbours. The difference factor d has been deduced from the measured σR by using the Glauber or Boltzmann-Uehling-Uhlenbeck models. From the above analysis, a possible one-proton halo structure is suggested for ^(23)Al.

Production of Light Nuclei from ^(36)Ar and ^(40)Ar Fragmentation at About 60 MeV/Nucleon

Fragments produced in the reactions of 69 MeV/nucleon ^(36)Ar and ^(55)MeV/nucleon ^(40)Ar on a Be target have been measured experimentally.The isotopic distributions from fragmentation reaction for both projectiles are reproduced by using a modified statistical abrasion-ablation model.Strong isospin effect exhibits in the isotopic distributions produced in ^(36)Ar and ^(40)Ar fragmentation.Experimental evidence is seen for the disappearance of the isospin effect in fragmentation reaction.

Poissonian Reducibility and Thermal Scaling in Nuclear Dissociation

The emission of clusters in the nuclear dissociation was investigated within the framework of isospin dependent lattice gas model.As observed in the recent experimental data,it was found that the emission probability of individual cluster is Poissonian and thermal scaling was observed in the linear Arrhenius plots made from the average multiplicity of each cluster as a function of the inverse temperature.The‘emission barriers’were extracted from the slopes of the Arrhenius plots and mainly depends on the surface energy of the cluster.

Measurements of Total Reaction Cross Section for Light Nuclei and Evidence for the Anomalous Nuclear Structure in ^(15)C

Measurements of the total reaction cross section for^(12-16)C,^(14-17)N and^(16-18)O on carbon target at intermediate energies were performed on RIBLL of HIRFL.A larger enhancement ofσR for^(15)C was observed than that for its neighbors.The analysis of these data indicates possible existence of an anomalous nuclear structure in^(15)C.A new quantity was suggested as the criterion to distinguish anomalous structure nuclei from normal nuclei.

Isospin Effect of Fragmentation Reaction on the Isotopic Distribution Producedin Intermediate Energy Heavy Ion Collisions

Fragments produced in the reaction of 60 MeV/n^(18)O on Be have been measured experimentally.The isotopic distribution of fragmentation reaction is well reproduced by a modified statistical abrasion-ablation model It is predicted that the isotopic distribution shifts toward the neutron rich side for neutron rich projectile,but this isospin effect decreases with the increase of the atomic number difference Z-Z_(A)and disappears at last,where Z and Z_(A)are atomic numbers of the isotopic distribution and the projectile respectively.

Study on Excitation Function and Isospin Dependencies of Total Reaction Cross Section via the Boltzmann-Uehling-Uhlenbeck Model

The excitation function and isospin dependencies ofσR have been investigated by using the Boltzmann-Uehling-Uhlenbeck(BUU)model with a square-type density distribution.When the width parameter of the square distribution is obtained by fittingσR at relativistic energies,the BUU-model can reproduce the experimental data at intermediate energies better than Glauber model.The systematical underestimation ofσR at intermediate energy by Glauber model was removed out now by BUU calculation framework.It is also found thatσR is sensitive to nuclear equation of state andσin-NN medium.The difference factor d defined in text is sensitive to the nuclear structure such as neutron halo and neutron skin,etc.

Detector Calibration by Monte Carlo Simulation Based on the Energy-Range Relationship of Energetic Ions

The experimental measurement of the total interaction cross sections of N,C,B,and Be isotopes on 12C target at medium energies is described.A new formula that gives a good description of the energy-range relationship of energetic ions over a wide energy range is presented.The energy calibration of detectors is made by a Monte Carlo simulation method based on this new formula.

Isospin Effects of Critical Behavior in Lattice Gas Model

Isospin effects of the critical phenomena were studied via Xe isotopes in the frame of the lattice gas model.All the critical temperatures for four Xe isotopes are close to 5.5 MeV at the same freeze-out density of about 0.39ρ0.The critical values of power law parameter of mass distribution,mean multiplicity of intermediate mass fragments,information entropy and Campi's second moment show minor dependence on the isospin at the critical point.

Study of Giant Dipole Resonance of Super Heavy Compound System

A microscopic semi-classical approach,i.e.,the linearized Vlasov equation with a collision term treated by the relaxation time approximation,is simply described and is used to investigate the giant dipole resonance(GDR)from hot super heavy compound system.The possibility of such GDRγrays emission is described also according to the fission delay.For Au+Au system(A=392)and Xe+U system(A=374),the temperature dependence of strength distribution of GDRγrays and the deformation effect on GDRγrays are discussed in framework of this approach.