Theoretical Investigation of the Angular-Momentum Dependence of the Mean Fission Lifetime of Excited Nuclei

Journal Article · Mon Nov 01 00:00:00 EST 2004 · Physics of Atomic Nuclei

DOI:https://doi.org/10.1134/1.1825533· OSTI ID:20692688

Gontchar, I I; Ponomarenko, N A; Turkin, V V; Litnevsky, L A ^[1]

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1. Omsk State Railway Transport University, pr. Marksa 35, Omsk, 644046 (Russian Federation)

Mean fission lifetimes of nuclei excited to energies of 80 to 400 MeV were recently measured at the GANIL accelerator by the crystal-blocking technique. Those experiments served as a motivation for us to perform systematic calculations of the time distributions of fission events and the mean fission lifetimes versus the angular momentum, the initial excitation energy, and the fissility of a primary excited nucleus. The mean fission lifetimes are given as a function of the angular momentum L. The calculations were performed within the refined version of the combined dynamical-statistical model. It turned out that, if the height of the fission barrier at L = 0 is sizably greater than the neutron binding energy, the L dependence of the mean fission lifetimes has a resonance character. Such behavior of the mean fission lifetimes <t{sub f}> is obtained both from statistical calculations and from a dynamical simulation of the fission process with allowance for friction. It is shown that the maximum in the L dependence of <t{sub f}> is due to the fission of nuclei that lost a considerable part of the initial excitation energy through the emission of neutrons. The majority of the calculations were performed for {sup 190}Pt at an initial excitation energy of 150 eV. It is shown that the resonance behavior disappears with increasing fissility, but that it survives over a broad range of initial excitation energies. Systematic experimental studies are required for confirming or disproving our theoretical predictions.

• OSTI ID: 20692688
• Journal Information: Physics of Atomic Nuclei, Vol. 67, Issue 11; Other Information: Translated from Yadernaya Fizika, ISSN 0044-0027, 67, 2101-2115 (No. 11, 2004); DOI: 10.1134/1.1825533; (c) 2004 MAIK ''Nauka / Interperiodica''; Country of input: International Atomic Energy Agency (IAEA); TN:; ISSN 1063-7788
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
22 GENERAL STUDIES OF NUCLEAR REACTORS
ANGULAR MOMENTUM
BINDING ENERGY
COMPUTERIZED SIMULATION
CONTROL SYSTEMS
EV RANGE
EXCITATION
EXCITED STATES
FISSION
FISSION BARRIER
GANIL CYCLOTRON
LIFETIME
MEV RANGE
NEUTRON DETECTION
NEUTRONS
PLATINUM 190
RESONANCE
STATISTICAL MODELS