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Influence of the entrance channel asymmetry on the fission properties of excited $^{180}$Hg nuclei
K.A. Kulkov$^{1,2}$, E.M. Kozulin$^{1,2}$, A.A. Bogachev$^1$, G.N. Knyazheva$^{1,2}$, I.M. Itkis$^1$, K.V. Novikov$^{1,2}$, I.V. Vorobiev$^1$
$^1$Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research (JINR), Dubna, Moscow oblast, 141980 Russia
$^2$Dubna State University, Dubna, Moscow oblast, 141982 Russia
E-mail: kulkov@jinr.ru
Fission of the pre-actinide nuclei is characterized as predominantly symmetrical even at low excitation energies. Recently, in experiments on the β$^+$-delayed fission of the $^{180}$Tl nucleus [1], an asymmetric mass distribution of the fission fragments of its daughter nucleus $^{180}$Hg with an excitation energy
E$^*$<10.8 MeV was found. Note that the formation of two fragments – semimagic nuclei $^{90}$Zr (N = 50, Z = 40) – should be expected in the symmetric fission of this strongly neutron-deficient nucleus. However, the formation of a light fragment with a mass of 80 u and a heavy one of 100 u was found in the fission of $^{180}$Hg. Therefore, the study of the fission properties of pre-actinide nuclei is extremely important.
Thus, we propose to study reactions $^{36}$Ar+$^{144}$Sm and
$^{90}$Zr+$^{90}$Zr, leading to the formation of the compound nucleus 180Hg in the wide range of excitation energies. In the $^{36}$Ar+$^{144}$Sm reaction fusion-fission and fast fission are observed. Special M-TKE matrix subtraction procedure [2] allowed to separate these two processes. The reaction $^{90}$Zr+$^{90}$Zr was measured in wide energy range. The mass asymmetry of the entrance channel in this reaction is equal to 0. At high incident energies all three possible reaction mechanisms - fusion-fission, quasifission and fast fission - contribute to the M-TKE distributions of the fissionlike reaction products. The separation of the two-dimensional M-TKE distributions of binary fragments corresponding to different reaction mechanisms allowed to obtain the main characteristics of each process. Double-arm time-of-flight spectrometer CORSET was used to measure M-TKE distributions.
1. A.N. Andreyev, J. Elseviers, M. Huyse et al., Phys. Rev. Lett. 105, 252502 (2010).
2. E.M. Kozulin et al., Phys. Lett. B 819 (2021) 136442.
| The speaker is a student or young scientist | Yes |
|---|---|
| Section | 2. Experimental and theoretical studies of nuclear reactions |
