Identification ofMo91andMo91m

Abstract

The known 65-second activity in ${\mathrm{Mo}}^{91}$ is shown to have an intense 650±15 kev gamma ray. The 65-second activity is therefore assigned to a 650±15 kev isomeric level which decays by a gamma transition 70±10 percent of the time and by positron emission 30±10 percent of the time. There are at least two higher-energy gamma rays with energies 1.22±0.03 Mev and 1.55±0.03 Mev. Existent ($\gamma , n$) and ($n, 2n$) data are used to show that 65-sec., 650-kev ${\mathrm{Mo}}^{91m}$ is a $p_{\frac{1}{2}}$ state and that 15.5-min ${\mathrm{Mo}}^{91}$ is a $g_{\frac{9}{2}}$ state. This assignment implies that the neutron binding energy of ${\mathrm{Mo}}^{92}$ is 12.5 Mev.