Fission decay ofCr48atECN*≊60 MeV
| Autor: | A. T. Hasan, A. K. Dummer, M. Freer, Stephen Sanders, Y. Liang, D. J. Henderson, R.M. Freeman, S. Cavallaro, M. P. Carpenter, R. R. Betts, C. Beck, D. T. Nisius, T. L. Khoo, B. B. Back, Ian Gardner Bearden, T. Lauritsen, A. Szanto de Toledo, R. V. F. Janssens, F. W. Prosser, A. H. Wuosmaa, K. A. Farrar, B. Crowell |
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| Rok vydání: | 1996 |
| Předmět: | |
| Zdroj: | Physical Review C. 54:1249-1261 |
| ISSN: | 1089-490X 0556-2813 |
| DOI: | 10.1103/physrevc.54.1249 |
| Popis: | The fully energy-damped yields for the {sup 36}Ar + {sup 12}C and {sup 20}Ne + {sup 28}Si reactions at 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 E{sub CN}*=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 reproduced by statistical-model 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 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, though, that the peaks arise from any special configuration of the compound system. Instead, anmore » analysis of the {gamma}-ray data and the results of statistical-model calculations support the conclusion 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. For the first time, we are able to deduce the nature of the competition between the resonance and statistical-fission mechanisms in this mass region.« less |
| Databáze: | OpenAIRE |
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