Directional and polarization correlation studies in the decay of 5-hour Sb¹¹⁸

Abstract

Directional and polarization correlation measurements have been carried out on the gamma rays accompanying the decay of 5-hour Sb¹¹⁸. These measurements lead to the following spin and parity assignments for excited levels in Sn¹¹⁸: 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 Sn¹¹⁸. The level scheme is discussed in terms of various nuclear models.