Role of the shell and pairing effects in nuclear fission

Krzysztof Pomorski, Bożena Nerlo-Pomorska

Abstract


The description of spontaneous fission of actinides by the macroscopic-microscopic method consisting of the Lublin Strasbourg Drop model and the two deformed Nilsson wells or the Yukawa folded single-particle potential is presented. The microscopic shell corrections are obtained by the Strutinsky method, while the pairing correlations are taken into account within the BCS theory. It was shown that the pairing strength should grow with increasing deformation of fissioning nucleus in order to obtain right estimates of the pairing field in the fission fragments. The fission barrier heights are estimated using the topographical theorem of Swiatecki.

Keywords


nuclear fission; scission point; barrier heights; shell and pairing effects

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References


Bardeen, J., Cooper, L. N., Schrieffer, J. R., 1957. Theory of Superconductivity, Physical Review 108, 1175–1204.

Bartel, J., Nerlo-Pomorska, B., Pomorski, K., Schmitt, C., 2014. The potential energy surface of 240Pu around scission, Physica Scripta 89, 054003,1–5.

Bohr, N., Wheeler, J. A., 1939. The Mechanism of Nuclear Fission, Physical Review 56, 426–450.

Bolsterli, M., Fiset, E. O., Nix, J. R., Norton, L., 1972. New Calculation of Fission Barrier for Heavy and Superheavy nuclei, Physical Review C 5, 1050–1078.

Gogny, D., 1975. in “Nuclear Self Consistent Fields”, Ripka G. and Porneuf M. (Eds.), North Holland, Amsterdam, p. 333.

Hahn, O., Straßmann, F., 1939. Über den Nachweis und Verhalten der bei der Bestrahlung des Urans mittels Neutronen entstehenden Erdalkalimetale, Naturwissenschaften 27, 11–15.

Krappe, H. J., Nix, J. R., Sierk, A. J., 1979. Unified nuclear potential for heavy-ion elastic scattering, fusion, fission, and ground-state masses and deformations, Physical Review C 20, 992–1013.

Krieger, S. J., Bonche, P., Flocard, H., Quentin, P., and Weiss, M., 1990. An improved pairing interaction for mean field calculations using Skyrme potentials, Nuclear Physics A517, 275-284.

Meitner, L., Frisch, O. R., 1939. Disintegration of Uranium by Neutrons: a New Type of Nuclear Reaction, Nature 143, 239–240.

Möller, P., Myers, W. D., Swiatecki, W. J., Treiner, J., 1988. Nuclear mass formula within a finite-range droplet model and folded-Yukawa single-particle potential, Atomic Data and Nuclear Data Tables 39, 225.

Möller, P., Nix, J. R., 1992. Nuclear pairing model, Nuclear Physics A536, 20–60.

Myers, W. D., Swiatecki, W. J., 1966, Nuclear Masses and Deformations, Nuclear Physics 81, 1–60.

Myers, W. D., Swiatecki, W. J., 1969. Average Nuclear Properties, Annals of Physics 55, 395–505; ibid. 1974. Nuclear Droplet Model for Arbitrary Shapes, Annals of Physics 84, 186–210.

Myers, W. D., Swiatecki, W. J., 1996. Nuclear properties according to the Thomas-Fermi model, Nuclear Physics A601, 141–167.

Myers, W. D., Swiatecki, W. J., 1997. The congruence energy: a contribution to nuclear masses, deformation energies and fission barriers, Nuclear Physics A612, 249–261.

Nilsson, S. G., 1955. Binding states of individual nucleons in strongly deformed nuclei, Det Kongelige Danske Videnskabernes Selskab Matematisk-fysiske Meddelelser 29, no. 16, 1–70.

Nilsson, S. G., Tsang, C. F., Sobiczewski, A., Szymanski, Z., Wycech, S., Gustafson, C., Lamm, I. L., Möller, P., and Nilsson, B., 1969. On the nuclear structure and stability of heavy and superheavy elements, Nuclear Physics A131, 1–66.

Pomorski, K., Dudek, J., 2003. Nuclear liquid-drop model and surface-curvature effects, Physical Review C 67, 044316, 1–13.

Pomorski, K., 2004. Particle number conserving shell-correction method, Physical Review C 70, 044306, 1–10.

Pomorski, K., Ivanyuk, F., 2009. Pairing correlations and fission barrier heights, Int. Journal Modern Physics E18, 900–906.

Strutinsky, V. M., 1967. Shell effects in nuclear masses and deformation energies , Nuclear Physics, A95, 420–442 ; 1968. Shells in deformed nuclei, Nuclear Physics A122, 1–33.

Woods, R. D., Saxon, D. S., 1954. Diffuse Surface Optical Model for Nucleon-Nuclei Scattering Physical Review 95, 577–578.




DOI: http://dx.doi.org/10.17951/aaa.2015.70.%25p
Date of publication: 2016-04-29 12:28:28
Date of submission: 2016-01-15 16:21:21


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