Directional and Polarization Correlation Studies in the Decay of 5-hourSb118

Directional and polarization correlation measurements have been carried out on the gamma rays accompanying the decay of 5-hour ${\mathrm{Sb}}^{118}$. These measurements lead to the following spin and parity assignments for excited levels in ${\mathrm{Sn}}^{118}$: 1.22 Mev ($2^{+}$), 2.25 Mev ($4^{+}$), and 2.51 Mev ($5^{-}$). A search for positrons was made, and an upper limit on positron emission was set at 0.2% of the 1.22-Mev decays, giving a lower limit of 2500 hours for the partial half-life of positron emission to any of the excited levels in ${\mathrm{Sn}}^{118}$. The level scheme is discussed in terms of various nuclear models.