Excited Levels inF20at 1.82 and 1.84 MeV

Abstract

Examination of the $\gamma$-ray spectrum from ${\mathrm{O}}^{18}({\mathrm{He}}^3, p\gamma ){\mathrm{F}}^{20}$ in the region near 1.85-MeV excitation has indicated the existence of a new level in addition to the one previously reported. With a magnetic spectrograph, this doublet structure has been confirmed, and the excitation energies of the two levels have been measured as 1824.4±2.1 and 1843.0±2.2 keV. The separation is 18.6±0.7 keV. Directional correlations of $\gamma$ rays from these levels have been studied in an axially symmetric arrangement. Based on these correlations, the spins of both levels are restricted to the values 1, 2, or 3; a probable assignment of spin 2 or 3 is made for the 1.84-MeV level. Branching ratios and multipole mixtures are reported.