Isoscaling in Peripheral Nuclear Collisions around the Fermi Energy and a Signal of Chemical Separation from its Excitation Energy Dependence

摘要

The isoscaling is investigated using the fragment yield data from fullyreconstructed quasi-projectiles observed in peripheral collisions of 28Si with124,112Sn at projectile energies 30 and 50 MeV/nucleon. The excitation energydependence of the isoscaling parameter beta_prime is observed which isindependent of beam energy. For a given quasi-projectile produced in reactionswith different targets no isoscaling is observed. The isoscaling thus reflectsthe level of N/Z-equilibration in reactions with different targets representedby the initial quasi-projectile samples. The excitation energy dependence ofthe isoscaling parameter beta_prime, corrected for the trivial 1/T temperaturedependence, does not follow the trend of the homogeneous system above 4MeV/nucleon thus possibly signaling the onset of separation into isospinasymmetric dilute and isospin symmetric dense phase.