Chemical Property of Colliding Sources in 124,136Xe and 112,124Sn Induced Collisions in Isobaric Ratio Difference and Isoscaling Methods

The isoscaling and isobaric ratio difference (IBD) methods are used to study the $\Delta\mu/T$ ($\Delta\mu$ being the difference between the chemical potentials of neutron and proton, and $T$ being the temperature) in the measured 1$A$ GeV $^{124}$Sn + $^{124}$Sn, $^{112}$Sn + $^{112}$Sn, $^{136}$Xe + Pb and $^{124}$Xe + Pb reactions. The isoscaling phenomena in the $^{124}$Sn/$^{112}$Sn and the $^{136}$Xe/$^{124}$Xe reactions pairs are investigated, and the isoscaling parameter $\alpha$ and $\beta$ are obtained. The $\Delta\mu/T$ determined by the isoscaling method (IS--$\Delta\mu/T$) and IBD method (IB--$\Delta\mu/T$) in the measured Sn and Xe reactions are compared. It is shown that in most of fragments, the IS-- and IB-- $\Delta\mu/T$ are consistent in the Xe reactions, while the IS-- and IB-- $\Delta\mu/T$ are only similar in the less neutron-rich fragments in the Sn reactions. The shell effects in IB--$\Delta\mu/T$ are also discussed.