The level structure and lifetimes of excited states in $\sp{81}$Sr were investigated using the techniques of inbeam $\gamma$ ray spectroscopy. The reactions $\sp{56}$Fe($\sp{28}$Si,2pn)$\sp{81}$Sr and $\sp{55}$Mn($\sp{29}$Si,p2n)$\sp{81}$Sr were used at beam energies of 103.6 and 95.2 MeV, respectively. The targets consisted of 0.1 mm thick natural Fe (92% $\sp{56}$Fe abundance) and $\simeq$ 2 mg/cm$\sp2$ $\sp{55}$Mn evaporated on a thick lead backing. / The previously known level scheme was confirmed and a total of 15 new levels were placed in $\sp{81}$Sr. Tentative spin assignments were based on level systematics, directional correlations between $\gamma$ rays and effective level lifetimes. / The mean lifetimes of 12 states were measured and lifetime limits were assigned for 10 others using the Doppler shift attenuation method. The deformation properties of states in $\sp{81}$Sr were determined from the lifetimes and compared to the deformations inferred from level energies. / The four rotational band structures in $\sp{81}$Sr were found to have differing deformations which persist to high spins. The magnitude of this deformation ranges from $\beta$ $\simeq$ 0.2 to $\simeq$ 0.4. Band crossings in the moderately deformed g$\sb{9/2}$ yrast and K = 5/2$\sp-$ bands were observed and a very deformed K = 1/2$\sp{(+)}$ band was seen up to a tentative spin of 31/2$\hbar$. / The experimental results were compared to theoretical projected and deformed shell model calculations. The crossing observed in the yrast band has been attributed to the alignment of two g$\sb{9/2}$ protons. The properties of the K = 1/2$\sp{(+)}$ band are shown to be consistent with a configuration based on a d$\sb{5/2}$ "intruder" orbital. This is the first nucleus in the mass 80 region to exhibit such a strongly deformed band based on this configuration. / Source: Dissertation Abstracts International, Volume: 49-03, Section: B, page: 0805. / Major Professor: Samuel L. Tabor. / Thesis (Ph.D.)--The Florida State University, 1988.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_76266 |
| Contributors | Moore, Eugene Franklin., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 279 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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