New states in the positive parity yrast bands of $\sp{74}$Se and $\sp{77}$Kr have been observed with the reactions $\sp{52}$Cr($\sp{28}$Si,$\alpha$2p)$\sp{74}$Se and $\sp{52}$Cr($\sp{28}$Si,2pn)$\sp{77}$Kr at 98 MeV. The target consisted of approximately 1 mg/cm$\sp2$ natural chromium (84% $\sp{52}$Cr abundance) evaporated on a thick lead backing. / The new states extend the known level scheme of $\sp{74}$Se up to I$\sp{\pi}$ = (22$\sp+$) and most of the transitions in the other previously reported bands have been seen. For the states I$\sp{\pi}$ $\geq$ 6$\sp+$ the spectrum shows a relatively constant moment of inertia parameter $(\hbar\sp2$/2$\Theta)$ = 27.8 $\pm$ 0.5 keV. / Excited positive parity states up to spin (41/2) have been observed in $\sp{77}$Kr. $\Delta$I = 1 transitions have been identified throughout the positive parity band. The energies, mixing ratios and B(M1) transition rates for these transitions alternate in size as the spin increases. A cranked shell model analysis was performed along with Strutinsky-Bogolyubov cranking calculations. The observed decrease in the signature splitting of the $\nu$g$\sb{9/2}$ band has been attributed to a band crossing due to an aligning pair of g$\sb{9/2}$ protons. Prolate quadrupole deformations of $\beta\sb2$ = 0.34 for the ground band and $\beta\sb2$ = 0.26 for the first excited band are predicted. This band crossing is associated with a shape change caused by the polarization effect of aligned quasiparticles. / Source: Dissertation Abstracts International, Volume: 49-03, Section: B, page: 0803. / Major Professor: Samuel L. Tabor. / Thesis (Ph.D.)--The Florida State University, 1987.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_76255 |
| Contributors | Gross, Carl J., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 150 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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