Neutron emission during fission and its impact on fission-fragment mass distribution studied by Langevin model

Fuente: arXiv
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Autori principali: Takagi, S., Harada, S., Aritomo, Y., Hirose, K., Nishio, K.
Natura: Preprint
Pubblicazione: 2025
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author Takagi, S.
Harada, S.
Aritomo, Y.
Hirose, K.
Nishio, K.
author_facet Takagi, S.
Harada, S.
Aritomo, Y.
Hirose, K.
Nishio, K.
contents Actinide nuclei exhibit mass-asymmetric fission at low energy due to shell structure. The fission-fragment mass distributions produced at high energy tend to have a symmetric shape due to smearing of shell effects. On the other hand, the distribution can be changed by neutron emission occurring before fission, as this decreases the excitation energy of the fissioning nucleus, and thus revives the shell structure. In so called multichance fission, neutron emission is considered prior to fission at the initial nuclear shape, and competition between fission and neutron emission is determined with the framework of the statistical model. In the present work, we describe fission in the Langevin equations, and neutron emission is treated throughout the fission process. The calculation reproduces experimentally observed mass distributions, and for a wide range of initial compound-nucleus excitation energy up to 60 MeV. The results show that, while neutron emission dominates at the ground-state shape, it occurs along the shape evolution path to the scission point.
format Preprint
id arxiv_https___arxiv_org_abs_2510_18205
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Neutron emission during fission and its impact on fission-fragment mass distribution studied by Langevin model
Takagi, S.
Harada, S.
Aritomo, Y.
Hirose, K.
Nishio, K.
Nuclear Theory
Actinide nuclei exhibit mass-asymmetric fission at low energy due to shell structure. The fission-fragment mass distributions produced at high energy tend to have a symmetric shape due to smearing of shell effects. On the other hand, the distribution can be changed by neutron emission occurring before fission, as this decreases the excitation energy of the fissioning nucleus, and thus revives the shell structure. In so called multichance fission, neutron emission is considered prior to fission at the initial nuclear shape, and competition between fission and neutron emission is determined with the framework of the statistical model. In the present work, we describe fission in the Langevin equations, and neutron emission is treated throughout the fission process. The calculation reproduces experimentally observed mass distributions, and for a wide range of initial compound-nucleus excitation energy up to 60 MeV. The results show that, while neutron emission dominates at the ground-state shape, it occurs along the shape evolution path to the scission point.
title Neutron emission during fission and its impact on fission-fragment mass distribution studied by Langevin model
topic Nuclear Theory
url https://arxiv.org/abs/2510.18205