Nuclear level structure of⁹⁹Tc

Abstract

The gamma rays of⁹⁹Tc excited through negatron decay of⁹⁹Mo have been studied by internal conversion spectroscopy, using a high resolution double focusing beta-ray spectrometer. Conversion electrons were observed for all transitions reported before. In addition a new gamma ray of energy 989.37±1.02 keV could be identified and ascribed for the first time to the decay of⁹⁹Mo. Gamma-ray energies have been determined with high precision. Multipolarity data, obtained from the measurements of absolute or ratio of conversion coefficients of gamma rays, were utilized for assigning possible spins and parities to the levels of⁹⁹Tc.

From our present data combined with other studies spins and parities; 7/2+, 1/2−, 5/2+, 3/2−, 3/2+ and 5/2− have been given to the 140, 142, 181, 514, 922 and 1131 keV levels respectively. The experimental level scheme is discussed in terms of theoretical predictions.