| Popis: |
Mixing ratios of some gamma-ray transitions in ${\mathrm{O}}^{15}$, ${\mathrm{N}}^{14}$, and ${\mathrm{C}}^{13}$ have been studied by particle-gamma angular-correlation measurements for the reactions ${\mathrm{O}}^{16}({\mathrm{He}}^{3}, \ensuremath{\alpha}\ensuremath{\gamma}){\mathrm{O}}^{15}$, ${\mathrm{C}}^{12}({\mathrm{He}}^{3}, p\ensuremath{\gamma}){\mathrm{N}}^{14}$, and ${\mathrm{C}}^{12}(d, p\ensuremath{\gamma}){\mathrm{C}}^{13}$. The outgoing particles were detected close to 180\ifmmode^\circ\else\textdegree\fi{} in an annular counter. For the ${\mathrm{He}}^{3}$ beam energies available it was possible to study all the bound states of ${\mathrm{N}}^{14}$, but only the 5.18-5.24-MeV doublet (unresolved) and the 6.16-MeV level of ${\mathrm{O}}^{15}$ could be studied in detail. An attempt was also made to obtain the mixing ratio of the ground-state transition from the 3.85-MeV level of ${\mathrm{C}}^{13}$. Spin assignments were verified wherever possible and the spin of the 5 24-MeV level of ${\mathrm{O}}^{15}$ has been established as $\frac{5}{2}$ Gamma-ray branching ratios were determined for the levels of ${\mathrm{N}}^{14}$ and were generally in agreement with previous work. Strong evidence was found for a weak transition between the 5.10-MeV and 3.95-MeV states of ${\mathrm{N}}^{14}$, but the previously reported transition between 7.03 and 3.95-MeV states was not observed. Correlations for the ${\mathrm{C}}^{12}({\mathrm{He}}^{3}, p\ensuremath{\gamma}){\mathrm{N}}^{14}$ reaction were measured at four different energies, since they can vary with energy. It was found from the correlations that the ${\mathrm{N}}^{14}$ levels were strongly populated in the $m=0$ substate. This has been interpreted as due to a direct interaction, possibly heavy-particle stripping. |
