Target effects in isobaric yield ratio differences between projectile fragmentation reactions

Abstract

Background: The isobaric yield ratio difference (IBD) between reactions is know to be sensitive to the density difference between projectiles in heavy-ion collisions around the Fermi energy.Purpose: The target effects in the isobaric yield ratio (IYR) and the IBD results have been studied.Methods: The amount of isotopes in the $140A$ MeV ${}^{48,40}\mathrm{Ca}+{}^{181}\mathrm{Ta}{/}^{9}\mathrm{Be}$ and ${}^{58,64}\mathrm{Ni}+{}^{181}\mathrm{Ta}{/}^{9}\mathrm{Be}$ reactions have been previously measured with high accuracy. The IYR and IBD results have been obtained from these reactions to study the effects of the light $^{9}\mathrm{Be}$ and heavy $^{181}\mathrm{Ta}$ targets. A ratio (${r}_{\ensuremath{\Delta}\ensuremath{\mu}}$) between the IBD results for the reactions with Ta and Be targets is defined to quantitatively show the target dependence of the IBD results. Results The IYRs for reactions with symmetric projectiles are more easily affected than those for reactions with neutron-rich projectiles. The IBD results are suppressed by using the $^{181}\mathrm{Ta}$ target to different degrees.Conclusions: The IYR and IBD results are influenced by the target used. The IBD for the $I=1$ isobaric chain is suggested as a probe to study the difference between the neutron and proton densities of the reaction systems.