Abstract
The fully energy-damped yields for the 36Ar + 12C and 20Ne + 28Si reactions at Ec.m. = 47.0 MeV and 45.5 MeV, respectively, are explored using particle-particle-γ coincidence data. These reactions reach a similar excitation energy of E*CN= 59.5 MeV in the 48Cr compound nucleus as was obtained in an earlier particle-particle coincidence study of the 24Mg + 24Mg 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 20Ne + 28Si and 24Mg + 24Mg 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 24Mg - 24Mg 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, an analysis of the γ-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 24Mg + 24Mg entrance channel, however, comparisons with the statistical model indicate a reduction of high-angular-momentum partial cross sections, leading to the 24Mg + 24Mg 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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1249-1261 |
| Number of pages | 13 |
| Journal | Physical Review C |
| Volume | 54 |
| Issue number | 3 |
| DOIs | |
| State | Published - Sep 1996 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Physics and Astronomy(all)
- Nuclear and High Energy Physics
Cite this
Fission decay of 48Cr at E*CN≈60 MeV. / Farrar, K. A.; Sanders, S. J.; Dummer, A. K.; Hasan, A. T.; Prosser, F. W.; Back, B. B.; Bearden, I. G.; Betts, R. R.; Carpenter, M. P.; Crowell, B.; Freer, M.; Henderson, D. J.; Janssens, R. V F; Khoo, T. L.; Lauritsen, T.; Liang, Yun; Nisius, D.; Wuosmaa, A. H.; Beck, C.; Freeman, R. M.; Cavallaro, Sl; Szanto De Toledo, A.
In: Physical Review C, Vol. 54, No. 3, 09.1996, p. 1249-1261.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Fission decay of 48Cr at E*CN≈60 MeV
AU - Farrar, K. A.
AU - Sanders, S. J.
AU - Dummer, A. K.
AU - Hasan, A. T.
AU - Prosser, F. W.
AU - Back, B. B.
AU - Bearden, I. G.
AU - Betts, R. R.
AU - Carpenter, M. P.
AU - Crowell, B.
AU - Freer, M.
AU - Henderson, D. J.
AU - Janssens, R. V F
AU - Khoo, T. L.
AU - Lauritsen, T.
AU - Liang, Yun
AU - Nisius, D.
AU - Wuosmaa, A. H.
AU - Beck, C.
AU - Freeman, R. M.
AU - Cavallaro, Sl
AU - Szanto De Toledo, A.
PY - 1996/9
Y1 - 1996/9
N2 - The fully energy-damped yields for the 36Ar + 12C and 20Ne + 28Si reactions at Ec.m. = 47.0 MeV and 45.5 MeV, respectively, are explored using particle-particle-γ coincidence data. These reactions reach a similar excitation energy of E*CN= 59.5 MeV in the 48Cr compound nucleus as was obtained in an earlier particle-particle coincidence study of the 24Mg + 24Mg 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 20Ne + 28Si and 24Mg + 24Mg 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 24Mg - 24Mg 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, an analysis of the γ-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 24Mg + 24Mg entrance channel, however, comparisons with the statistical model indicate a reduction of high-angular-momentum partial cross sections, leading to the 24Mg + 24Mg 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.
AB - The fully energy-damped yields for the 36Ar + 12C and 20Ne + 28Si reactions at Ec.m. = 47.0 MeV and 45.5 MeV, respectively, are explored using particle-particle-γ coincidence data. These reactions reach a similar excitation energy of E*CN= 59.5 MeV in the 48Cr compound nucleus as was obtained in an earlier particle-particle coincidence study of the 24Mg + 24Mg 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 20Ne + 28Si and 24Mg + 24Mg 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 24Mg - 24Mg 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, an analysis of the γ-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 24Mg + 24Mg entrance channel, however, comparisons with the statistical model indicate a reduction of high-angular-momentum partial cross sections, leading to the 24Mg + 24Mg 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.
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U2 - 10.1103/PhysRevC.54.1249
DO - 10.1103/PhysRevC.54.1249
M3 - Article
VL - 54
SP - 1249
EP - 1261
JO - Physical Review C - Nuclear Physics
JF - Physical Review C - Nuclear Physics
SN - 0556-2813
IS - 3
ER -