The reactions ('16)O(('16)O,(alpha)(,0,1))('28)Si* and ('16)O(('16)O,('8)Be(,0,1))('24)Mg* are studied in the energy region from E(,c.m.) (DBLTURN) 12 to 20 MeV. Excitation functions for these reactions leading to the residual 0('+) ground states and 2('+) first excited states are measured in ('(TURN))50 keV steps at (')(THETA)(,c.m.) (DBLTURN) 6.1(DEGREES) for the (alpha)-particle exit channels and at (')(THETA)(,c.m.) (DBLTURN) 1.5(DEGREES) and (DBLTURN)5.7(DEGREES) for the ('8)Be channels. Angular distributions are measured at selected energies and include differential cross sections at 28 angles in the range (THETA)(,c.m.) (DBLTURN) 6(DEGREES) to 91(DEGREES) for the (alpha)(,0,1) exit channels and at 13 angles from (THETA)(,c.m. )(DBLTURN) 12(DEGREES) to 61(DEGREES) for the ('8)Be(,0,1) channels. / A high density of narrow, resonancelike structures ((rho) ('(TURN))3/MeV, (GAMMA) < 100 to ('(TURN))200keV) is observed in the small-angle data. No system- atic variations of the structure width and density with either energy or exit channel are apparent. Distribution-of-maxima statistical tests, applied to the small-angle data, give no evidence for nonstatistical structure in the four exit channels examined. / Energy correlations in angle-summed cross sections reveal several structures which satisfy conventional resonance criteria. Resonant J('(pi)) values are assigned whenever possible based on the energy dependences of coefficients in either linear Legendre expan- sions or interfering angular momentum pair parameterizations of angular distributions of the spin-zero (alpha)(,0) and ('8)Be exit channels. / Statistical-model calculations are used to predict the magnitudes and angular momentum dependences of the compound-nucleus components in the (alpha)(,0,1) and ('8)Be(,0,1) channels. Synthetic excitation functions and angular distributions are generated to determine whether fluctuations resulting from the population and decay of overlapping compound-nucleus levels can produce resonancelike structure similar to that observed in the data. The results of this investigation suggest a fluctuation origin for the intermediate width structure observed in the data including those structures which are found to satisfy conventional resonance criteria. / Source: Dissertation Abstracts International, Volume: 47-06, Section: B, page: 2488. / Thesis (Ph.D.)--The Florida State University, 1986.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_75845 |
| Contributors | GAY, DENNIS L., Florida State University |
| Source Sets | Florida State University |
| Detected Language | English |
| Type | Text |
| Format | 254 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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