Fission dynamics with microscopic level densities

Research output: Chapter in Book/Report/Conference proceedingPaper in conference proceeding

Standard

Fission dynamics with microscopic level densities. / Randrup, Jørgen; Ward, Daniel; Carlsson, Gillis; Døssing, Thomas; Möller, Peter; Åberg, Sven.

Scientific Workshop on "Nuclear Fission and the Emission of Prompt Neutrons and Gamma Rays", THEORY 2017. Vol. 169 EDP Sciences, 2018. 00019.

Research output: Chapter in Book/Report/Conference proceedingPaper in conference proceeding

Harvard

Randrup, J, Ward, D, Carlsson, G, Døssing, T, Möller, P & Åberg, S 2018, Fission dynamics with microscopic level densities. in Scientific Workshop on "Nuclear Fission and the Emission of Prompt Neutrons and Gamma Rays", THEORY 2017. vol. 169, 00019, EDP Sciences, 4th Scientific Workshop on Nuclear Fission Dynamics and the Emission of Prompt Neutrons and Gamma Rays, THEORY 2017, Varna, Bulgaria, 2017/06/20. https://doi.org/10.1051/epjconf/201816900019

APA

Randrup, J., Ward, D., Carlsson, G., Døssing, T., Möller, P., & Åberg, S. (2018). Fission dynamics with microscopic level densities. In Scientific Workshop on "Nuclear Fission and the Emission of Prompt Neutrons and Gamma Rays", THEORY 2017 (Vol. 169). [00019] EDP Sciences. https://doi.org/10.1051/epjconf/201816900019

CBE

Randrup J, Ward D, Carlsson G, Døssing T, Möller P, Åberg S. 2018. Fission dynamics with microscopic level densities. In Scientific Workshop on "Nuclear Fission and the Emission of Prompt Neutrons and Gamma Rays", THEORY 2017. EDP Sciences. https://doi.org/10.1051/epjconf/201816900019

MLA

Randrup, Jørgen et al. "Fission dynamics with microscopic level densities". Scientific Workshop on "Nuclear Fission and the Emission of Prompt Neutrons and Gamma Rays", THEORY 2017. EDP Sciences. 2018. https://doi.org/10.1051/epjconf/201816900019

Vancouver

Randrup J, Ward D, Carlsson G, Døssing T, Möller P, Åberg S. Fission dynamics with microscopic level densities. In Scientific Workshop on "Nuclear Fission and the Emission of Prompt Neutrons and Gamma Rays", THEORY 2017. Vol. 169. EDP Sciences. 2018. 00019 https://doi.org/10.1051/epjconf/201816900019

Author

Randrup, Jørgen ; Ward, Daniel ; Carlsson, Gillis ; Døssing, Thomas ; Möller, Peter ; Åberg, Sven. / Fission dynamics with microscopic level densities. Scientific Workshop on "Nuclear Fission and the Emission of Prompt Neutrons and Gamma Rays", THEORY 2017. Vol. 169 EDP Sciences, 2018.

RIS

TY - GEN

T1 - Fission dynamics with microscopic level densities

AU - Randrup, Jørgen

AU - Ward, Daniel

AU - Carlsson, Gillis

AU - Døssing, Thomas

AU - Möller, Peter

AU - Åberg, Sven

PY - 2018/3/6

Y1 - 2018/3/6

N2 - Working within the Langevin framework of nuclear shape dynamics, we study the dependence of the evolution on the degree of excitation. As the excitation energy of the fissioning system is increased, the pairing correlations and the shell effects diminish and the effective potential-energy surface becomes ever more liquid-drop like. This feature can be included in the treatment in a formally well-founded manner by using the local level densities as a basis for the shape evolution. This is particularly easy to understand and implement in the Metropolis treatment where the evolution is simulated by means of a random walk on the five-dimensional lattice of shapes for which the potential energy has been tabulated. Because the individual steps between two neighboring lattice sites are decided on the basis of the ratio of the statistical weights, what is needed is the ratio of the local level densities for those shapes, evaluated at the associated local excitation energies. For this purpose, we adapt a recently developed combinatorial method for calculating level densities which employs the same single-particle levels as those that were used for the calculation of the pairing and shell contributions to the macroscopic-microscopic deformation-energy surface. For each nucleus under consideration, the level density (for a fixed total angular momentum) is calculated microscopically for each of the over five million shapes given in the three-quadratic-surface parametrization. This novel treatment, which introduces no new parameters, is illustrated for the fission fragment mass distributions for selected uranium and plutonium cases.

AB - Working within the Langevin framework of nuclear shape dynamics, we study the dependence of the evolution on the degree of excitation. As the excitation energy of the fissioning system is increased, the pairing correlations and the shell effects diminish and the effective potential-energy surface becomes ever more liquid-drop like. This feature can be included in the treatment in a formally well-founded manner by using the local level densities as a basis for the shape evolution. This is particularly easy to understand and implement in the Metropolis treatment where the evolution is simulated by means of a random walk on the five-dimensional lattice of shapes for which the potential energy has been tabulated. Because the individual steps between two neighboring lattice sites are decided on the basis of the ratio of the statistical weights, what is needed is the ratio of the local level densities for those shapes, evaluated at the associated local excitation energies. For this purpose, we adapt a recently developed combinatorial method for calculating level densities which employs the same single-particle levels as those that were used for the calculation of the pairing and shell contributions to the macroscopic-microscopic deformation-energy surface. For each nucleus under consideration, the level density (for a fixed total angular momentum) is calculated microscopically for each of the over five million shapes given in the three-quadratic-surface parametrization. This novel treatment, which introduces no new parameters, is illustrated for the fission fragment mass distributions for selected uranium and plutonium cases.

UR - http://www.scopus.com/inward/record.url?scp=85044003615&partnerID=8YFLogxK

U2 - 10.1051/epjconf/201816900019

DO - 10.1051/epjconf/201816900019

M3 - Paper in conference proceeding

VL - 169

BT - Scientific Workshop on "Nuclear Fission and the Emission of Prompt Neutrons and Gamma Rays", THEORY 2017

PB - EDP Sciences

ER -