Decay of Nb 94 and Nb 94m

Abstract

Gamma rays in Mo 94 following the decay of Nb 94 have been studied using coincidence and directional correlation measurements. The 700 keV transition was found to be in coincidence with the 873 keV gamma ray. The intensity of the crossover transition of 1573 keV was found to be less than 0.1 % of the 873 keV gamma ray intensity. The directional correlation of the 700 keV – 873 keV cascade was measured and the corrected expansion coefficients were found to be A 2 = 0.0965 ± 0.0076 and A 4 = 0.019 ± 0.011. These data indicate spins of 4 and 2 for the 1573 keV and 873 keV levels, respectively. Gamma rays following the decay of Nb 94m were studied with proportional and scintillation counters. The conversion coefficient α K of the 42 keV gamma ray in the decay of 6.6 min Nb 94m was measured to be 1600 ± 350 and the branching ratio of the transition from Nb 94m to the 873 keV level of Mo 94 was found to be 0.19 ± 0.03 %. The intensity ratio of the 600 keV beta ray to the 1.3 MeV beta ray in the decay of Nb 94m was determined to be 3.0 ± 0.6 %. These measurements support a spin and parity of 3- for the isomeric state.