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Examining the exotic structure of the proton-rich nucleus {sup 23}Al

The longitudinal momentum distribution (P{sub //}) of fragments after one-proton removal from {sup 23}Al and reaction cross sections ({sigma}{sub R}) for {sup 23,24}Al on a carbon target at 74A MeV have been measured. The {sup 23,24}Al ions were produced through projectile fragmentation of 135A MeV {sup 28}Si primary beam using the RIPS fragment separator at RIKEN. P{sub parallel} is measured by a direct time-of-flight (TOF) technique, while {sigma}{sub R} is determined using a transmission method. An enhancement in {sigma}{sub R} is observed for {sup 23}Al compared with {sup 24}Al. The P{sub parallel} for {sup 22}Mg fragments from {sup 23}Al breakup has been obtained for the first time. FWHM of the distributions has been determined to be 232 {+-} 28 MeV/c. The experimental data are discussed by using the Few-Body Glauber model. Analysis of P{sub //} demonstrates a dominant d-wave configuration for the valence proton in ground state of {sup 23}Al, indicating that {sup 23}Al is not a proton halo nucleus.

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

Systematic study of isoscaling behavior in projectile fragmentation by the statistical abrasion–ablation model

The isospin effect and isoscaling behavior in projectile fragmentation have been systematically investigated by a modified statistical abrasion–ablation (SAA) model. The normalized peak differences and reduced isoscaling parameters are found to decrease with (Zproj − Z)/Zproj or the excitation energy per nucleon and have no significant dependence on the size of reaction systems. Assuming a Fermi-gas behavior, the excitation energy dependence of the symmetry energy coefficients is tentatively extracted from α and β which looks consistent with the experimental data. It is pointed out that the reduced isoscaling parameters can be used as an observable to study excitation extent of system and asymmetric nuclear equation of state in heavy ion collisions.

Scaling of anisotropy flows in intermediate energy heavy ion collisions

Anisotropic flows ( v 1 , v 2 and v 4 ) of light nuclear clusters are studied by a nucleonic transport model in intermediate energy heavy ion collisions. The number-of-nucleon scalings of the directed flow ( v 1 ) and elliptic flow ( v 2 ) are demonstrated for light nuclear clusters. Moreover, the ratios of v 4 / v 2 2 of nuclear clusters show a constant value of 1/2 regardless of the transverse momentum. The above phenomena can be understood by the coalescence mechanism in nucleonic level and are worthy to be explored in experiments.

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.

ISOSPIN EFFECT AND ISOSCALING PHENOMENON IN PROJECTILE FRAGMENTATION

We have studied the isospin effect and isoscaling behavior in projectile fragmentation using a modified statistical abrasion-ablation (SAA) model. The relationship between neutron skin thickness (δnp) and neutron abrasion cross section (σnabr) has also been investigated. We find the normalized peak differences and reduced isoscaling parameters decrease with (Zproj - Z)/Zproj or the excitation energy per nucleon and have no significant dependence on the size of the reaction systems. The excitation energy dependence of the symmetry energy coefficients are tentatively extracted from α and β. Assuming Fermi-type density distributions for proton and neutron and introducing a parameter to adjust the diffuseness of the neutron density distribution for neutron-rich nucleus, δnp and σnabr for neutron-rich nucleus were found to have a linear correlation. It is suggested that σnabr could be used as an observable to extract the neutron skin thickness for neutron-rich nucleus.

DYNAMICAL AND SEQUENTIAL DECAY EFFECTS ON ISOSCALING AND DENSITY DEPENDENCE OF THE SYMMETRY ENERGY

Isoscaling properties of the primary and final products are studied via isospin dependent quantum molecular dynamics (IQMD) model and the followed sequential decay model GEMINI, respectively. Both primary and final products isoscaling parameter α keeps no significant change for light fragments, but increases with the mass for intermediate and heavy products. The dynamical effect on isoscaling is reflected on the α decreasing a little with the evolution time of the system, and opposite trend for the heavy products. The secondary decay effect on isoscaling is reflected on the increasing of the α value for the final products which experienced secondary decay process. Furthermore the density dependence of the symmetry energy has also been explored for the primary and secondary products, the symmetry energy coefficient can be expressed by the form of Csym(ρ) ~ C0(ρ/ρ0)γ, C0 and γ extracted from the primary products are consistent with the input parameters, but C0 and γ extracted from the final products deviate the input values. In the paper we also suggest that it might be more reasonable to describe the density dependence of the symmetry energy coefficient by the Csym(ρ/ρ0) ≈ C1(ρ/ρ0)γsoft + C2(ρ/ρ0)γstiff with γsoft ≤ 1, γstiff ≥ 1 and C1, C2 constant parameters.

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.

Measurements of reaction cross section and fragment momentum distribution for N=10 proton-rich isotones

The longitudinal momentum (p//) distributions of fragments after one-proton removal and reaction cross sections (σR) for several N = 10 isotones at intermediate energy (~ 70A MeV) have been measured simultaneously at the RIken Projectile fragment Separator (RIPS). p// was measured using a direct time-of-flight (TOF) technique, while σR was determined using a transmission method. An enhanced σR is observed for 23Al comparing with its neighbors. The p// distribution for 22Mg fragments from 23Al one-proton removal reaction has been obtained for the first time. The experimental data are discussed within a Few Body Glauber (FBG) framework. Analysis of p// indicates a dominant d-wave component in the ground state of 23Al. This agrees with recent experimental results. We also suggest the possibility of an enlarged 22Mg core for proton-rich nucleus 23Al.