Radioactive Decay of 65-HourSb122

Abstract
65-hour Sb122 was investigated by using Sb121 (97.7 percent-99.4 percent) that had been bombarded with thermal neutrons for 70 hours. Spectrometer measurements show three beta groups with end-point energies: 1.987, 1.423, and 0.734 Mev; and logft values: 8.6 [logft(w2mc2)=10.0, p2+q2 shape], 7.6 (allowed shape), and 7.7; and four gamma rays with energies: 0.563, 0.693, 1.152, and 1.256 Mev; and intensities: 73 percent, 3.6 percent, 0.75 percent and 0.8 percent. From gamma-gamma and beta-gamma coincidences the excited states of Te122 were found at 0.563 and 1.256 Mev. X-gamma coincidences and x-ray critical absorption showed 2.2 percent and 0.8 percent K-capture transitions to the ground state and to a 1.152-Mev level in Sn122. The ft values for the transitions to Sn122 are 13 times smaller than the corresponding transitions to Te122. Annihilation radiation was not observed setting an upper limit of 0.005 percent for positrons. The directional correlation of the 0.693- and the 0.563-Mev gamma rays indicated a 2-2-0 cascade, with the 2-2 transition 91+5 percent quadrupole. The first excited state in Te122 was also shown to be 2+ from a measurement of the K conversion coefficient of the 0.563-Mev gamma ray. We conclude therefore that the ground state of Sb122 is 2- (g72, h112), the first two excited states of Te122 are 2+, and the first excited state of Sn122 may also be 2+.

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