Level structure of 97Tc from the decay of 2.9 d 97Ru

Abstract

Abstract The level structure of 97Tc has been investigated from the decay of 2.9 d 97Ru. Singles γ-ray energy and intensity measurements were taken with a 42 cm3 high-resolution Ge(Li) detector in an anti-Compton arrangement which employed a large Na(Tl) annular detector. The following new very weak γ-ray transitions were observed in the decay of 97Ru: 114.34±0.07, 477.7±0.6, 850.1±0.4 and 898.19±0.15 keV. From the γγ coincidence relationships established in this work via extensive experiments employing two Ge(Li) detectors it was concluded that levels at 96.5, 215.71, 324.49, 656.82, 785.05, 855.45, 969.79 and 994.69 keV in 97Tc are populated in the decay of 97Ru. The population of two additional levels at 574.2 and 946.5 keV is discussed. Precision measurements of the K-shell conversion coefficients for eight transitions in 97Tc were made with the aid of a Si(Li)Ge(Li) conversion coefficient spectrometer. From the αK value determined in this work for the 216 keV transition its multipolarity is found to be M1 with (10±4 %) admixture. From log t and αK values determined in this work and from γ-ray branching ratio information Jπ assignments were made for eight levels and limits placed for two remaining levels. The αK value for the 336 keV transition in 95Tc following 95Ru decay was also measured and found to be (10.4±0.5) × 10−3, which is consistent with an M1 transition with (11±9) % E2 admixture. The level structure and trends in 97Tc and 99Tc isotopes are examined and discussed in relation to recently published results on calculated levels in these isotopes on the basis of an extend quasiparticle-phonon coupling model for the nucleus; only moderate qualitative agreement is found.