Fission barriers and other characteristics of nuclei from the uranium region
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CLEI Theory
Fission Barriers and Other Characteristics of Nuclei from the Uranium Region S. V. Tolokonnikov1), 2) , I. N. Borzov1), 3) , Yu. S. Lutostansky1), I. V. Panov1), 4) , and E. E. Saperstein1), 5)* Received December 26, 2016
Abstract—Fission barriers in nuclei belonging to the uranium region and their other characteristics are calculated on the basis of the FaNDF0 energy density functional. In particular, the neutron-separation energies Sn and S2n , the proton-separation energies Sp , and the beta-transition energies Qβ are calculated for uranium, neptunium, and plutonium isotopes. In addition, the deformation energies and parameters of these nuclei are presented along with their radii. A comparison with the predictions of the Skyrme– Hartree–Fock method implemented with several versions of the Skyrme energy density functionals is performed. The role of the octupole deformation β3 is studied for the 238 U nucleus. It is shown that this (1) deformation does not have any significant effect on the first-barrier height Bf or ground-state properties. (2)
At the same time, the second-barrier height Bf decreases by a factor of about two upon taking into account β3 . A phase transition at A 260 is found for the three isotopic chains being considered: this (1) (2) point is a bifurcation point at which Bf (A) forks into two curves. Of these, the curve Bf (A) splits from (1)
(1)
it, prolonging the former curve for Bf (A) almost continuously, whereas the curve for Bf (A) itself goes down sharply. DOI: 10.1134/S1063778817040275
1. INTRODUCTION Important phenomena that nuclear astrophysics should explain include the existence of heavy and superheavy elements in nature and their abundances. The development of models of the ultimate stages of massive-star evolution [1] suggests several possible scenarios of the emergence of conditions for the neutron-induced nucleosynthesis of heavy nuclei in the r-process. In the case of the collapse of a star, promising scenarios include classical collapse models featuring a delayed explosion mechanism and neutrino-transport and equation-of-state models, which are still being refined [2], and scenarios of an explosion driven by the magnetorotational 1)
National Research Center Kurchatov Institute, pl. Akademika Kurchatova 1, Moscow, 123182 Russia. 2) Moscow Institute of Physics and Technology (State University), Institutskii per. 9, Dolgoprudnyi, Moscow oblast, 141700 Russia. 3) Joint Institute for Nuclear Research, ul. Joliot-Curie 6, Dubna, Moscow oblast, 141980 Russia. 4) Institute for Theoretical and Experimental Physics, National Research Center Kurchatov Institute, Bol’shaya Cheremushkinskaya ul. 25, Moscow, 117218 Russia. 5) National Research Nuclear University MEPhI, Kashirskoe sh. 31, Moscow, 115409 Russia. * E-mail: [email protected]
instability [3] and of a collapse triggered by a quark– hadron phase transition [4]. The scenario of a hot wind from a core that undergoes a collapse to a neutron star (protoneutron star) [5] is being continuously developed. Within this sce
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