Dynamical scission model

• Published in: Nuclear physics. A Vol. 909; pp. 50 - 68
• Main Authors: Rizea, M., Carjan, N.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2013; North-Holland ; Elsevier [1967-....]
• Subjects: Bi-dimensional time-dependent Schrödinger equation; Low-energy nuclear fission; Nuclear Theory; Partition of the excitation energy between the fission fragments; Physics; Probability and current densities of the scission neutrons; Scission properties; Time-dependent potential; Scission properties; Partition of the excitation energy between the fission fragments; Time-dependent potential; Probability and current densities of the scission neutrons; Low-energy nuclear fission; Bi-dimensional time-dependent Schrödinger equation
• ISSN: 0375-9474; 1873-1554
• DOI: 10.1016/j.nuclphysa.2013.04.014

A time-dependent microscopic approach to the scission process, i.e., the transition from two fragments connected by a thin neck (αi) to two separated fragments (αf), which takes place in a short time interval ΔT, is presented. We follow the evolution from αi to αf of all occupied neutron states by solving numerically the two-dimensional time-dependent Schrödinger equation with time-dependent potential. Calculations are performed for mass divisions from AL=70 to AL=118 (AL being the light-fragment mass). The duration of the neck rupture ΔT is taken as parameter having values from 0.25×10−22 to 6×10−22 s. The resulting scission-neutron multiplicities νsc and primary fragment excitation energies Esc⁎ are compared with those obtained in the frame of the sudden approximation (ΔT=0). As expected, the sudden approximation is an upper limit. For ΔT=10−22 s, which is a realistic value, the time-dependent results are 15% to 20% below this limit. For transition times longer than 6×10−22 s the adiabatic limit is reached. The probability and current densities of the unbound neutrons at scission are also calculated. They provide a detailed picture of the emission mechanism and a hint for the angular distribution of the scission neutrons with respect to the fission axis.