Isospin observables from fragment energy spectra

Abstract

The energy spectra of light charged particles and intermediate mass fragments from ${}^{112}\mathrm{Sn}+{}^{112}\mathrm{Sn}$ and ${}^{124}\mathrm{Sn}+{}^{124}\mathrm{Sn}$ collisions at an incident energy of $E/A=50$ MeV have been measured with a large array of silicon strip detectors. We used charged-particle multiplicities detected in an array with nearly 4$\ensuremath{\pi}$ coverage to select data from the central collision events. We study isospin observables analogous to ratios of neutron and proton spectra, including double ratios and yield ratios of triton/${}^{3}$He and of asymmetries constructed from fragments with $Z=3$--8. Using the energy spectra, we can construct these observables as functions of kinetic energy. Most of the fragment asymmetry observables have a large sensitivity to sequential decays.