Heavy-residue isoscaling as a probe of the process of N/Z equilibration

• Published in: Physics letters. B 2004-05, Vol.588 (1-2), p.35-42
• Main Authors: Souliotis, G.A., Veselsky, M., Shetty, D.V., Yennello, S.J.
• Format: Article
• Language: English
• Subjects: Deep-inelastic transfer; Exact sciences and technology; Fermi energy; Heavy residues; Isoscaling; Low and intermediate energy heavy-ion reactions; N/Z equilibration; Nuclear physics; Nuclear reactions; Nuclear reactions: specific reactions; Physics; Projectile and target fragmentation
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/j.physletb.2004.03.027

The isotopic and isobaric scaling behavior of the yield ratios of heavy projectile residues from the collisions of 25 MeV/nucleon 86Kr projectiles on 124Sn and 112Sn targets is investigated and shown to provide information on the process of N/Z equilibration occurring between the projectile and the target. The logarithmic slopes α and β′ of the residue yield ratios with respect to residue neutron number N and neutron excess N−Z are obtained as a function of the atomic number Z and mass number A, respectively, whereas excitation energies are deduced from velocities. The relation of the isoscaling parameters α and β′ with the N/Z of the primary (excited) projectile fragments is employed to gain access to the degree of N/Z equilibration prior to fragmentation as a function of excitation energy. A monotonic relation between the N/Z difference of fragmenting quasiprojectiles and their excitation energy is obtained indicating that N/Z equilibrium is approached at the highest observed excitation energies. Simulations with a deep-inelastic transfer model are in overall agreement with the isoscaling conclusions. The present residue isoscaling approach to N/Z equilibration offers an attractive tool of isospin and reaction dynamics studies in collisions involving beams of stable or rare isotopes.