Properties ofP30Levels from theSi29(p, γ)P30Reaction. I

Abstract

$\ensuremath{\gamma}$-ray decay schemes of seven resonances in the ${\mathrm{Si}}^{29}(p, \ensuremath{\gamma}){\mathrm{P}}^{30}$ reaction in the range ${E}_{p}=700\ensuremath{-}1750$ keV have been studied in order to gain additional information on properties of resonant and bound levels of ${\mathrm{P}}^{30}$. The results also provide necessary information for the analysis of $\ensuremath{\gamma}$-ray angular-correlation and polarization measurements, which are in progress. Singles and coincidence spectra were obtained at each of the resonances at ${E}_{p}=730, 917, 1302, 1470, 1505, 1686, \mathrm{and} 1748$ keV (all\ifmmode\pm\else\textpm\fi{}2 keV) using large-volume NaI (Tl) detectors and a Ge(Li) detector. The resonance strengths were measured relative to the strength of the resonance at ${E}_{p}=416$ keV in the same reaction, which is known from previous work. Consistent resonance decay schemes were derived, along with decay schemes of lower-lying bound states which, in many cases, differ considerably from previously available information. New results, or results significantly different from earlier reports, were obtained for the decay properties of the 3.02-, 3.74-, 3.93-, 4.14-, 4.18-, 4.23-, 4.43-, 4.50-, 4.62-, and 4.92-MeV levels of ${\mathrm{P}}^{30}$. The existence of a weak transition from the ${4}^{\ensuremath{-}}$, 4.23-MeV level to the ${1}^{+}$ ground state is shown. Another unusual transition found is one from the ${3}^{\ensuremath{-}}$, 4.92-MeV level to the ${1}^{+}$, 0.709-MeV level. The energies of 17 bound levels of ${\mathrm{P}}^{30}$ were determined from the Ge(Li) data to a greater accuracy than heretofore available. Evidence is found for a previously unreported level at 4.468\ifmmode\pm\else\textpm\fi{}0.003 MeV, which is proposed to be the $J=0$, $T=1$ analog of the 3.79-MeV level of ${\mathrm{Si}}^{30}$. The decay schemes of the ${E}_{p}=730\ensuremath{-}, 917\ensuremath{-}, \mathrm{and} 1302$-keV resonances indicate they are quite pure $T=0$ levels. The new value $Q=5.597\ifmmode\pm\else\textpm\fi{}0.003$ MeV for the ${\mathrm{Si}}^{29}(p, \ensuremath{\gamma}){\mathrm{P}}^{30}$ reaction was derived from the Ge(Li) spectra.