Classification of fission modes in 236U using a six-dimensional Langevin approach
Abstract
Thermal neutron-induced fission of 235U is studied using a six-dimensional Langevin approach based on the Cassini shape parametrization. Scission events are classified into Asymmetric 1 (AS1), Asymmetric 2 (AS2), and Superlong (SL) fission modes by applying the k-means algorithm to the fragment mass and the quadrupole deformations of both fragments. For each mode, proton and neutron single-particle levels are calculated for representative fragments to examine their shell structures. The AS1 heavy fragment exhibits proton gaps at Z=50 and 52 and neutron gaps at N=82 and 84, whereas well-developed gaps appear at Z=56 and N=88 in the AS2 heavy fragment. The mass splits of AS1 and AS2 are close to those of the conventional Standard I and Standard II modes, respectively. However, the average total kinetic energy is lower for AS1 than for AS2, opposite to the conventional ordering of Standard I and Standard II. This reversal reflects the more elongated shape of the AS1 light fragment. The SL mode is conventionally interpreted in terms of macroscopic liquid-drop effects, whereas the pronounced proton shell gap at Z=46 suggests that proton shell effects also contribute to the elongated symmetric configuration. The classification based on fragment mass and the quadrupole deformations of both fragments provides a basis for distinguishing fission modes and examining the corresponding fragment shell structures at scission.
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BibTeX
@misc{okada2026classification,
title = {{Classification of fission modes in $^236$U using a six-dimensional Langevin approach}},
author = {K Okada and K Nishio and T Wada and N Carjan},
howpublished = {HAL},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.11103},
eprint = {2609.11103},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05761988v1},
}
RIS
TY - UNPB
TI - Classification of fission modes in ^236U using a six-dimensional Langevin approach
AU - K Okada
AU - K Nishio
AU - T Wada
AU - N Carjan
PY - 2026
DA - 2026/09/10
PB - HAL
DO - 10.48550/arxiv.2609.11103
UR - https://hal.science/hal-05761988v1
AB - Thermal neutron-induced fission of ^235U is studied using a six-dimensional Langevin approach based on the Cassini shape parametrization. Scission events are classified into Asymmetric 1 (AS1), Asymmetric 2 (AS2), and Superlong (SL) fission modes by applying the k-means algorithm to the fragment mass and the quadrupole deformations of both fragments. For each mode, proton and neutron single-particle levels are calculated for representative fragments to examine their shell structures. The AS1 heavy fragment exhibits proton gaps at Z=50 and 52 and neutron gaps at N=82 and 84, whereas well-developed gaps appear at Z=56 and N=88 in the AS2 heavy fragment. The mass splits of AS1 and AS2 are close to those of the conventional Standard I and Standard II modes, respectively. However, the average total kinetic energy is lower for AS1 than for AS2, opposite to the conventional ordering of Standard I and Standard II. This reversal reflects the more elongated shape of the AS1 light fragment. The SL mode is conventionally interpreted in terms of macroscopic liquid-drop effects, whereas the pronounced proton shell gap at Z=46 suggests that proton shell effects also contribute to the elongated symmetric configuration. The classification based on fragment mass and the quadrupole deformations of both fragments provides a basis for distinguishing fission modes and examining the corresponding fragment shell structures at scission.
ER -