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Title: Fission dynamics of Pu 240 from saddle to scission and beyond

Abstract

Calculations are presented for the time evolution of 240Pu from the proximity of the outer saddle point until the fission fragments are well separated, using the time-dependent density functional theory extended to superfluid systems. We have tested three families of nuclear energy density functionals and found that all functionals exhibit a similar dynamics: The collective motion is highly dissipative and with little trace of inertial dynamics, due to the one-body dissipation mechanism alone. This finding justifies the validity of using the overdamped collective motion approach and to some extent the main assumptions in statistical models of fission. This conclusion is robust with respect to the nuclear energy density functional used. The configurations and interactions left out of the present theory framework only increase the role of the dissipative couplings. An unexpected finding is varying the pairing strength within a quite large range has only minor effects on the dynamics. Furthermore, we find notable differences in the excitation energy sharing between the fission fragments in the cases of spontaneous and induced fission. With increasing initial excitation energy of the fissioning nucleus, more excitation energy is deposited in the heavy fragment, in agreement with experimental data on average neutron multiplicities.

Authors:
ORCiD logo [1];  [1];  [2];  [3]; ORCiD logo [4]
  1. Univ. of Washington, Seattle, WA (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Univ. of Washington, Seattle, WA (United States)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1570633
Alternate Identifier(s):
OSTI ID: 1562742
Report Number(s):
LA-UR-18-23917
Journal ID: ISSN 2469-9985; PRVCAN
Grant/Contract Number:  
89233218CNA000001; FG02-97ER41014; AC05-00OR22725; AC02-05CH11231; AC52-07NA27344; NA0003841
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review C
Additional Journal Information:
Journal Volume: 100; Journal Issue: 3; Journal ID: ISSN 2469-9985
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Citation Formats

Bulgac, Aurel, Jin, Shi, Roche, Kenneth J., Schunck, Nicolas, and Stetcu, Ionel. Fission dynamics of Pu240 from saddle to scission and beyond. United States: N. p., 2019. Web. doi:10.1103/PhysRevC.100.034615.
Bulgac, Aurel, Jin, Shi, Roche, Kenneth J., Schunck, Nicolas, & Stetcu, Ionel. Fission dynamics of Pu240 from saddle to scission and beyond. United States. doi:10.1103/PhysRevC.100.034615.
Bulgac, Aurel, Jin, Shi, Roche, Kenneth J., Schunck, Nicolas, and Stetcu, Ionel. Thu . "Fission dynamics of Pu240 from saddle to scission and beyond". United States. doi:10.1103/PhysRevC.100.034615.
@article{osti_1570633,
title = {Fission dynamics of Pu240 from saddle to scission and beyond},
author = {Bulgac, Aurel and Jin, Shi and Roche, Kenneth J. and Schunck, Nicolas and Stetcu, Ionel},
abstractNote = {Calculations are presented for the time evolution of 240Pu from the proximity of the outer saddle point until the fission fragments are well separated, using the time-dependent density functional theory extended to superfluid systems. We have tested three families of nuclear energy density functionals and found that all functionals exhibit a similar dynamics: The collective motion is highly dissipative and with little trace of inertial dynamics, due to the one-body dissipation mechanism alone. This finding justifies the validity of using the overdamped collective motion approach and to some extent the main assumptions in statistical models of fission. This conclusion is robust with respect to the nuclear energy density functional used. The configurations and interactions left out of the present theory framework only increase the role of the dissipative couplings. An unexpected finding is varying the pairing strength within a quite large range has only minor effects on the dynamics. Furthermore, we find notable differences in the excitation energy sharing between the fission fragments in the cases of spontaneous and induced fission. With increasing initial excitation energy of the fissioning nucleus, more excitation energy is deposited in the heavy fragment, in agreement with experimental data on average neutron multiplicities.},
doi = {10.1103/PhysRevC.100.034615},
journal = {Physical Review C},
number = 3,
volume = 100,
place = {United States},
year = {2019},
month = {9}
}

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