Neutron density distributions of neutron-rich nuclei studied with the isobaric yield ratio difference

Abstract

The isobaric yield ratio difference (IBD) between two reactions of similar experimental setups is found to be sensitive to nuclear density differences between projectiles. In this article, the IBD probe is used to study the density variation in neutron-rich 48 Ca. By adjusting diffuseness in the neutron density distribution, three different neutron density distributions of 48 Ca are obtained. The yields of fragments in the 80A MeV 40,48 Ca + 12 C reactions are calculated by using a modified statistical abrasion-ablation model. It is found that the IBD results obtained from the prefragments are sensitive to the density distribution of the projectile, while the IBD results from the final fragments are less sensitive to the density distribution of the projectile.PACS. 21.65.Cd Asymmetric matter, neutron matter -21.65.Ef Symmetry energy -25.70.Mn Projectile and target fragmentation

Isobaric yield ratio difference between the140AMeVNi58+BeQiao1, Wei2, Ma3 et al. 2015Phys. Rev. C12070View full textAdd to dashboardCite

“…Considering two reactions where the measurement situations are the same (where the temperature of the reactions can be assumed as the same), the IYR difference between the reactions, i.e., IBD, is defined as [3][4][5][6],…”

“…∆µ/T is related to the density difference between neutrons and protons of the reaction systems [5,6]. Although the IBD probe is deduced from the canonical ensemble theory, the modified Fisher model can yield the same form of the IBD probe [8,30,31].…”

“…The isobaric yield ratio difference (IBD) method, which is similar to the isoscaling method [1,2], has been developed to study chemical potentials of neutrons and protons [3,4] or the nuclear density [5][6][7] in heavy-ion collisions. Based on the isobaric yield ratio (IYR), the IBD method provides cancellation of both the system dependence parameters [8][9][10][11], the free energies of isobars [3], and the terms contributing to the free energy of fragments [8,[12][13][14][15][16] in the formula determining the cross sections of fragment.…”

“…In a typical IBD distribution, there is a plateau part plus a changing (increasing or decreasing) part as the function of the mass numbers A of fragments [3][4][5][6]. The plateau part is explained as denoting the region where the chemical potential (or the density) difference of neutrons and protons changes very little.…”

“…The plateau part is explained as denoting the region where the chemical potential (or the density) difference of neutrons and protons changes very little. The modified statistical abrasion-ablation (SAA) model [25] was used to * Email: machunwang@126.com study the IBD and the nuclear density difference of neutrons and protons between the calcium-isotope-induced reactions [5,6], which suggests that the IBD is sensitive to the nuclear density extracted from the prefragments, but the sensitivity is weakened in the results for the final fragments. Because the SAA calculation cannot reproduce some of the IYR distributions, the IBD results by SAA cannot well explain the measured data [5].…”