A dynamical study of fusion hindrance with the Nakajima–Zwanzig projection method

Yasuhisa Abe , David Boilley (1, 2) , Quentin Hourdillé (1, 2) , Caiwan Shen

1 GANIL - Grand Accélérateur National d'Ions Lourds
2 UNICAEN - Université de Caen Normandie

A new framework is proposed for the study of collisions between very heavy ions which lead to the synthesis of Super-Heavy Elements (SHE), to address the fusion hindrance phenomenon. The dynamics of the reaction is studied in terms of collective degrees of freedom undergoing relaxation processes with different time scales. The Nakajima–Zwanzig projection operator method is employed to eliminate fast variables and derive a dynamical equation for the reduced system with only slow variables. There, the time evolution operator is renormalised and an inhomogeneous term appears, which represents a propagation of the given initial distribution. The term results in a slip to the initial values of the slow variables. We expect that gives a dynamical origin for the so-called “injection point |$s$|” introduced by Swiatecki et al. in order to reproduce absolute values of measured cross sections for SHE. A formula for the slip is given in terms of physical parameters of the system, which confirms the results recently obtained with a Langevin equation, and permits us to compare various incident channels.

Domaines: Physique Nucléaire Théorique [nucl-th]

Yasuhisa Abe, David Boilley, Quentin Hourdillé, Caiwan Shen. A dynamical study of fusion hindrance with the Nakajima–Zwanzig projection method. PTEP, 2021, 2021 (2), pp.021D01. ⟨10.1093/ptep/ptab005⟩. ⟨hal-03070591⟩