The reactions, $\rm\sp{12}C(\sp7Li,\alpha)\sp{15}N$ and $\rm\sp7Li(\sp{12}C,\sp{15}N\to\alpha$ + $\sp{11}B)\alpha$ at E$\sb{\rm cm}$ = 33.2 MeV, are used to measure the alpha-particle decay branching ratio, $\Gamma\sb\alpha/\Gamma,$ of states in $\sp{15}$N produced at several excitation energies, $\rm E\sb{x}(\sp{15}N).$ Resonant Particle Decay Spectroscopy is applied to the sequential reaction to identify $\sp{15}$N states and construct their alpha-particle angular correlations from the kinematic reconstruction of the relative kinetic energy of the $\sp{15}$N break-up products $(\alpha$ and $\sp{11}$B) detected in coincidence by use of two position sensitive detectors. It is shown that the symmetry observed in these correlations implies azimuthal isotropy, so that integration can be accomplished to yield $\Gamma\sb\alpha/\Gamma$ in conjunction with the measured $\sp{15}$N production cross sections. For excited states at $\rm E\sb{x}(\sp{15}N)$ = 11.44, 12.56, 13.01, 13.18, 13.83 and 14.11 MeV, the measured values of $\Gamma\sb\alpha/\Gamma$ are 0.07 $\pm$ 0.01, 0.60 $\pm$ 0.04, 0.84 $\pm$ 0.09, 0.34 $\pm$ 0.04, 0.37 $\pm$ 0.09 and 0.31 $\pm$ 0.06 respectively (absolute uncertainty is $\sim$15%). Reduced widths of some of these states are calculated under limiting approximations. / Spectral analysis also yields: (a) New excited states at $\rm E\sb{x}(\sp{15}N)$ = 12.67, 12.83, 15.15 and 22.58 MeV, (b) confirmation of previously questioned states at $\rm E\sb{x}(\sp{15}N)$ = 15.87 and 21.37 MeV, (c) previously unknown alpha-particle decays for 17 excited states and (d) correction of previously reported energy widths for states at $\rm E\sb{x}(\sp{15}N)$ = 16.20, 16.46, 17.12, and 20.95 MeV. Probable spin-parity values are proposed for several $\sp{15}$N states based on a DWBA analysis carried out for the angular distributions of the $\rm\sp{12}C(\sp7Li,\alpha)\sp{15}N$ reaction and the best theoretical descriptions of the alpha-particle angular correlations of the sequential reaction. / Source: Dissertation Abstracts International, Volume: 54-03, Section: B, page: 1462. / Major Professor: Neil R. Fletcher. / Thesis (Ph.D.)--The Florida State University, 1993.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_76896 |
| Contributors | Liendo, Jacinto Alberto., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 249 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
Page generated in 0.0024 seconds