Fission decay of {sup 48}Cr at {ital E}{sub CN}{sup {asterisk}}{approx_equal}60MeV

Journal Article · Sun Sep 01 00:00:00 EDT 1996 · Physical Review, C

DOI:https://doi.org/10.1103/PhysRevC.54.1249· OSTI ID:390375

Farrar, K A; Sanders, S J; Dummer, A K; Hasan, A T; Prosser, F W ^[1]; Back, B B; Bearden, I G; Betts, R R; Carpenter, M P; Crowell, B; Freer, M; Henderson, D J; Janssens, R V; Khoo, T L; Lauritsen, T; Liang, Y; Nisius, D; Wuosmaa, A H ^[2]; Beck, C; Freeman, R M ^[3] ; Cavallaro, S ^[4]; Szanto de Toledo, A ^[5]

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1. The University of Kansas, Department of Physics and Astronomy, Lawrence, Kansas 66045 (United States)
2. Argonne National Laboratory, Argonne, Illinois 60439 (United States)
3. Centre de Recherches Nucleaires, IN2P3-CNRS/Universite Louis Pasteur, B.P. 28, F-67037 Strasbourg Cedex 2 (France)
4. Dipartimento di fisica dell`Universita di Catania, I-95129 Catania (Italy)
5. Departamento de Fisica Nuclear, Instituto de Fisica da Universidade de Sao Paulo, Caixa Postal 20516-01498-970 Sao Paulo, S.P. (Brazil)

The fully energy-damped yields for the {sup 36}Ar + {sup 12}C and {sup 20}Ne + {sup 28}Si reactions at {ital E}{sub c.m.}=47.0 MeV and 45.5 MeV, respectively, are explored using particle-particle-{gamma} coincidence data. These reactions reach a similar excitation energy of {ital E}{sub CN}{sup *}=59.5 MeV in the {sup 48}Cr compound nucleus as was obtained in an earlier particle-particle coincidence study of the {sup 24}Mg + {sup 24}Mg reaction. The overall mass and total kinetic energy distributions of the fission fragments are found to be well modeled by statistical calculations. These calculations are also found to reproduce structure seen in the excitation-energy spectra for the {sup 20}Ne + {sup 28}Si and {sup 24}Mg + {sup 24}Mg exit channels for all three reactions. In previous excitation-function measurements, strong heavy-ion resonance behavior has been observed in elastic and inelastic cross sections for the {sup 24}Mg + {sup 24}Mg system. There has been speculation that peaks observed in the corresponding excitation-energy spectra at more negative {ital Q} values may also be a consequence of this resonance phenomenon. The observation of very similar behavior with the asymmetric-mass entrance channels makes it less likely that the peaks arise from any special configuration of the compound system. An analysis of the {gamma}-ray data and the results of statistical-model calculations indicate that most of the observed high-lying structure can be accounted for in terms of statistical fission from a fully energy- and shape-equilibrated compound nucleus. For the {sup 24}Mg + {sup 24}Mg entrance channel, however, comparisons with the statistical model indicate a reduction of high-angular-momentum partial cross sections, leading to the {sup 24}Mg + {sup 24}Mg fission channel. We are able to deduce the nature of the competition between the resonance and statistical-fission mechanisms in this mass region. {copyright} {ital 1996 The American Physical Society.}

• DOE Contract Number: FG02-89ER40506; W-31109-ENG-38
• OSTI ID: 390375
• Journal Information: Physical Review, C, Vol. 54, Issue 3; Other Information: PBD: Sep 1996
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
CARBON 12 TARGET
ARGON 36 REACTIONS
CHROMIUM 48
SILICON 28 TARGET
NEON 20 REACTIONS
FISSION
MAGNESIUM 24 TARGET
MAGNESIUM 24 REACTIONS
MEV RANGE 10-100
COINCIDENCE METHODS
EXCITATION
COMPOUND NUCLEI
KINETIC ENERGY
DISTRIBUTION
FISSION FRAGMENTS
STATISTICAL MODELS
ELASTIC SCATTERING
INELASTIC SCATTERING
Q-VALUE
RESONANCE
ANGULAR MOMENTUM