Dissipation by transfer and its influence on fusion

¹ Heavy Ion Laboratory, University of Warsaw, Warszawa, Poland
² China Institute of Atomic Energy, Beijing, China

^* e-mail: colucci@slcj.uw.edu.pl
^** e-mail: agniecha@slcj.uw.edu.pl

Published online: 18 October 2024

Abstract

A new version of the CCQEL code has been developed by upgrading the method of coupling of transfer channels during fusion and backscattering processes. In particular, the number of transfer reactions included has been increased and the dependence of the strength of transfer coupling on the transferred particle and experimental Q-value distribution was introduced. The upgraded code was employed for the investigation of the influence of transfer on the smoothing of the measured quasielastic barrier distribution (D_qe) of the ²⁴Mg + ⁹²Zr and ²⁰Ne + ²⁰⁸Pb systems and found interesting discrepancies with respect to the standard approximations. The study with the upgraded code indicates the transfer responsible for generating strongly excited targets as the leading cause of the smearing of the barrier distribution, even in the case of negative ground state to ground state Q value (Q_gg). The smoothing observed in the barrier distribution is dominated rather by one neutron transfer, despite the negative Q_gg value for this reaction and the positive Q_gg value for two-neutron transfer. Of particular interest is the case of the ²⁰Ne + ²⁰⁸Pb, where the smoothing of the D_qe is mainly influenced by the one neutron pick-up at the beam energy above the barrier, while the one neutron pick-up and one proton stripping transfers are dominant for lower beam energy. These results highlight the importance of the transfer coupling dependence on the experimental Q-value distribution and, consequently, on the projectile kinetic energy.