LEVEL STRUCTURE OF LOW-LYING EXCITED STATES OF GA66 POPULATED BY DECAY OF 2.2-H GE66

The decay of 2.2-h Ge66 to levels in Ga66 has been investigated by the use of both singles and coincidence γ-ray spectroscopic techniques that made exclusive use of high-resolution Ge(Li) detectors. The internal-conversion electron spectrum was also studied. A total of 23 transitions was observed in this decay; these were incorporated in a complete and unambiguous level scheme that differs markedly from those previously proposed. The excitation energies of the states in Ga66 found to be populated in this decay are 43.8, 108.9, 234.0, 290.9, 381.8, 514.6, 536.6, and 706.0 keV. The half-life of the Ge66 activity was redetermined to be be 2.23±0.10 h. The half-life of the first excited state was measured by delayed-coincidence techniques to be 21±2 nsec. The multipolarities of many of the transitions were determined. Spin and parity assignments of many of the excited states were inferred, and severe limitations could be imposed on the spin assignments of the remainder of the levels. The logft values of all β branches were established, and limits on the amount of isobaric-spin impurity present in the ground state of Ge66 were set. The level characteristics were found to be consistent with expectations derived from theoretical considerations. © 1969 The American Physical Society.