Decay of 56 min 69gZn, 14 h 69mZn and 39 h 69Ge to levels of 69Ga

Abstract The decay of 69m Zn was found to have weak β-branches to the 574 (0.032±0.005%) and 872 keV (0.004±0.002%) levels of 69 Ga in addition to the prominent (>99.9%) 439 keV isometric transition to 69g Zn. Decay of the latter includes a weak (0.0015±0.0005%) β-branch to the 318 keV level of 69 Ga. Ten of the 36 γ-rays assigned to the decay of 69 Ge in this work had not previously been observed. Levels are established in 69 Ga at 318, 574, 872, 1106, 1336, 1487, 1525, 1723, 1891, 1923, 2022 and 2043 keV. The recent level predictions by Kisslinger and Kumar are in better agreement with the observed levels of 69 Ga than previous calculations although discrepancies in levels positions are still rather large. As the energies of the excited states of even nuclei in the vicinity of 69 Ga do not vary smoothly with N and Z , it is doubtful that a generalized type of calculation (e.g. Kisslinger-Kumar) can provide a very good fit to levels in the region. The log ft value of 8.6 for the β − transition from 1 2 − 69g Zn to the 1 2 − level at 318 keV in 69 Ga is among the largest known for allowed transitions. The half-lives of the species studied were determined to be 69g Zn, 55.6±1.6 min; 69m Zn, 14.4±0.1 h and 69 Ge, 39.05±0.10 h. A value of 0.102±0.004 was obtained for the isomer-yield ratio 69m Zn/ 69g Zn in the 68 Zn(n,γ) 69 Zn reaction.