Isoscaling of fragments with Z=1-17 from reconstructed quasiprojectiles

In heavy-ion collisions, isoscaling provides a method for studying the evolution of nuclear symmetry energy as a function of excitation energy. One challenge in using isoscaling is to accurately determine the neutron-to-proton ratio (N/Z) of the fragmenting source. Isoscaling results are presented for the reactions of Kr-86,Kr-78+Ni-64,Ni-58 at 35 MeV/nucleon taken on the NIMROD-ISiS array at Texas A&M University. The N/Z of the source was calculated from the isotopically identified fragments and experimentally measured neutrons emitted from reconstructed quasiprojectiles. These data exhibit isoscaling for elements with Z=1-17 over a broad range of isotopes. The isoscaling parameter alpha is shown to increase with increasing difference in the neutron composition (Delta) of the compared sources. For a selected Delta, the ratio alpha/Delta is also shown to decrease with increasing excitation energy. This may reflect a corresponding decrease in the nuclear symmetry energy.</p>.