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Excitation energy partition in fission

Albertsson, M. LU ; Carlsson, B. G. LU ; Døssing, T. LU ; Möller, P. LU ; Randrup, J. LU and Åberg, S. LU (2020) In Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 803.
Abstract

The transformation of an atomic nucleus into two excited fission fragments is modeled as a strongly damped evolution of the nuclear shape. As in previous studies, it is assumed that the division of mass and charge is frozen in at a critical neck radius of c0=2.5fm. In order to also determine the energetics, we follow the system further until scission occurs at a smaller neck radius, at which point the shapes of the proto-fragments are extracted. The statistical energy available at scission is then divided on the basis of the respective microscopic level densities. This approach takes account of important (and energy-dependent) finite-size effects. After the fragments have been fully accelerated and their shapes have relaxed... (More)

The transformation of an atomic nucleus into two excited fission fragments is modeled as a strongly damped evolution of the nuclear shape. As in previous studies, it is assumed that the division of mass and charge is frozen in at a critical neck radius of c0=2.5fm. In order to also determine the energetics, we follow the system further until scission occurs at a smaller neck radius, at which point the shapes of the proto-fragments are extracted. The statistical energy available at scission is then divided on the basis of the respective microscopic level densities. This approach takes account of important (and energy-dependent) finite-size effects. After the fragments have been fully accelerated and their shapes have relaxed to their equilibrium forms, they undergo sequential neutron evaporation. The dependence of the resulting mean neutron multiplicity on the fragment mass, ν¯(A), including the dependence on the initial excitation energy of the fissioning compound nucleus, agrees reasonably well with observations, as demonstrated here for 235U(n, f), and the sawtooth appearance of ν¯(A) can be understood from shell-structure effects in the level densities.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Brownian shape evolution method, Fission, Microscopic level densities
in
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
volume
803
article number
135276
publisher
Elsevier
external identifiers
  • scopus:85079190033
ISSN
0370-2693
DOI
10.1016/j.physletb.2020.135276
language
English
LU publication?
yes
id
7f0a6424-15bf-4030-afb1-dc7865573363
date added to LUP
2020-02-20 11:25:11
date last changed
2020-12-29 02:59:43
@article{7f0a6424-15bf-4030-afb1-dc7865573363,
  abstract     = {<p>The transformation of an atomic nucleus into two excited fission fragments is modeled as a strongly damped evolution of the nuclear shape. As in previous studies, it is assumed that the division of mass and charge is frozen in at a critical neck radius of c<sub>0</sub>=2.5fm. In order to also determine the energetics, we follow the system further until scission occurs at a smaller neck radius, at which point the shapes of the proto-fragments are extracted. The statistical energy available at scission is then divided on the basis of the respective microscopic level densities. This approach takes account of important (and energy-dependent) finite-size effects. After the fragments have been fully accelerated and their shapes have relaxed to their equilibrium forms, they undergo sequential neutron evaporation. The dependence of the resulting mean neutron multiplicity on the fragment mass, ν¯(A), including the dependence on the initial excitation energy of the fissioning compound nucleus, agrees reasonably well with observations, as demonstrated here for <sup>235</sup>U(n, f), and the sawtooth appearance of ν¯(A) can be understood from shell-structure effects in the level densities.</p>},
  author       = {Albertsson, M. and Carlsson, B. G. and Døssing, T. and Möller, P. and Randrup, J. and Åberg, S.},
  issn         = {0370-2693},
  language     = {eng},
  month        = {04},
  publisher    = {Elsevier},
  series       = {Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics},
  title        = {Excitation energy partition in fission},
  url          = {http://dx.doi.org/10.1016/j.physletb.2020.135276},
  doi          = {10.1016/j.physletb.2020.135276},
  volume       = {803},
  year         = {2020},
}