Study of Low-Lying States ofS33

Abstract

The low-lying states of ${\mathrm{S}}^{33}$ at 0.84, 1.97, 2.31, 2.94, and 3.22 MeV have been studied using the charged-particle-gamma-ray angular-correlation method of Litherland and Ferguson. The ${\mathrm{S}}^{32}\mathrm{}(d,p)\mathrm{}{\mathrm{S}}^{33}$ reaction was used to populate the levels of ${\mathrm{S}}^{33}$, with an incident deuteron energy of 3.20 MeV. Charged particles were detected near 180° with respect to the incident beam direction using an annular solid-state counter, and gamma radiation was detected in a 10.2-cm×10.2-cm NaI(Tl) crystal at angles between 0° and 90° relative to the beam direction. Coincident data were stored in a 64×64-channel 2-parameter pulse-height analyzer. Gamma-ray branching ratios are presented for the levels mentioned above, and also the 2.87-MeV level of ${\mathrm{S}}^{33}$. Spin assignments of $\frac{5}{2}$, $\frac{3}{2}$, $\frac{7}{2}$, and ($\frac{3}{2}$) were established for the levels of ${\mathrm{S}}^{33}$ at 1.97, 2.31, 2.94, and 3.22 MeV, respectively, as well as a most probable assignment of positive parity for the 1.97-MeV level. Some gamma-ray mixing ratios are also presented. An upper limit for the mean lifetime of these latter states as well as the 0.84-MeV level of ${\tau }_m\le {10}^{-8\mathrm{}}$ sec has been obtained. These results, combined with the results of previous investigations, lead to spin-parity assignments of ${\frac{3}{2}}^{+}$, ${\frac{1}{2}}^{+}$, ${\frac{5}{2}}^{\mathrm{}(+)\mathrm{}}$, ${\frac{3}{2}}^{+}$, and ${\frac{7}{2}}^{-}$ for the ${\mathrm{S}}^{33}$ levels at 0, 0.84, 1.97, 2.31, and 2.94 MeV, and support the $J=\frac{3}{2}$ assignment for the 3.22-MeV level. No evidence was obtained for the existence of a level in ${\mathrm{S}}^{33}$ near 1.4-MeV excitation energy.