The scission-point configuration of fissioning nuclei
Ivanyuk
Institute for Nuclear Research, Kiev, Ukraine
日時：2016年12月05日（月） 16:00-
場所：理学研究科合同B棟721号室
The shape of nuclear surface is a basic notion of many theoretical models used in nuclear physics. In [1] V. Strutinsky has proposed a method to specify the optimal shape of nuclear surface which does not rely on any shape parameterization. In this approach the shape of an axial, left-right symmetric nucleus was defined by looking for the minimum of its liquid-drop energy under restriction that the volume and elon-gation of the drop are fixed. Recently the method was further developed [2-4] by in-corporating the axial and left-right asymmetry and the neck degree of freedom. The important result of Strutinsky procedure [1] is the possibility to define in a for-mal way the scission point as the maximal elongation above which the solution for the compact drop does not exist. Having at one’s disposal the shape and the defor-mation energy at the scission point one can evaluate the measurable quantities of the fission experiments, like mass distribution, total kinetic and excitation energy of fission fragments, the multiplicity of prompt neutrons. The difference of energies just before the scission and immediately after the scis-sion contributes to the excitation en-ergy of fission fragments which can be taken away by prompt neutrons or gamma-rays. The liquid-drop part of the excitation energy should be cor-rected by the account of shell effects and extra deformation energy. The calculated deformation and ex-citation energies at the scission point were used in [5] to estimate the total kinetic and excitation energy of fission fragments and the total number of prompt neutrons emitted in fission of 232Th, 235U, 239Pu and 245Cm by thermal neutrons. The calculated results de-scribe rather well the experimental data on the position of the peaks in the mass distribution of fission fragments, the total ki-netic and excitation energy of fission fragments. The sawtooth structure of the neu-tron multiplicity is also qualitatively reproduced.
[1] V.M. Strutinsky, N.Ya. Lyashchenko, N.A. Popov, Nucl. Phys. 46, 659 (1963).
[2] F.A. Ivanyuk, Int. J. Mod. Phys. E 18, 130 (2009).
[3] F.A. Ivanyuk and K. Pomorski, Phys. Rev. C 79, 054327 (2009).
[4] F.A. Ivanyuk, Physica Scripta, 89, 0540012 (2014).
[5] F.A. Ivanyuk, S. Chiba and Y. Aritomo, Phys. Rev. C 90, 054607 (2014).