Levels inP33ofEex<4.3MeV

Abstract

Bound states of ${\mathrm{P}}^{33}$ below 4.3-MeV excitation energy have been investigated via the ${\mathrm{P}}^{31}(t,p\gamma ){\mathrm{P}}^{33}$ reaction at triton bombarding energies of 2.45 and 3.10 MeV. Proton and $\gamma$-ray singles measurements, together with $p-\gamma$ coincidence measurements, have determined the principal $\gamma$-ray decay modes for the eight states previously reported below 4.3-MeV excitation energy in ${\mathrm{P}}^{33}$. Evidence is also obtained for the $\gamma$ decay of a previously unreported state at 4.19 MeV. Angular-correlation measurements, in conjunction with lifetime restrictions obtained from Ge(Li) studies of the $\gamma$-ray Doppler shifts, lead to the following determinations of spin parity for these levels [$\mathrm{MeV}\left(J^{\pi }\right)$] in ${\mathrm{P}}^{33}$: 0.0(${\mathrm{½}}^{+}$), $1.43\left({\frac{3}{2}}^{+}\right)$, $1.85\left({\frac{5}{2}}^{+}\right)$, $2.54\left({\frac{3}{2}}^{+}\right)$, $3.28(\frac{3}{2},\frac{5}{2})$, $3.49(\frac{3}{2} or \frac{1}{2})$, $3.63\left({\frac{7}{2}}^{+}\right)$, $4.05(\frac{3}{2},\frac{5}{2})$, $4.19(\frac{5}{2},\frac{7}{2})$, and $4.22\left({\frac{7}{2}}^{-}\right)$. These results serve in part to confirm the previously published assignments for the ground state and first three excited states, and establish new information for the higher-lying states. Restrictions on multipole mixing in the deexcitation transitions are summarized and compared with previous results. Finally, the experimental spectrum of ${\mathrm{P}}^{33}$ levels thus obtained is compared with applicable shell-model calculations for these low-lying levels.