부산대학교 도서관

The 111.sup.Tc nucleus, populated in the spontaneous fission of 248.sup.Cm, was studied by means of prompt I3-ray spectroscopy using the EUROGAM2 array. Excited states in 111.sup.Tc were observed for the first time. Systematics of energy levels in odd-A Tc isotopes, obtained in our study of 107.sup.Tc and 109.sup.Tc provide a reliable spin and parity assignment I = 5/2.sup.+ to the head of the new band in 111.sup.Tc, interpreted as the [pi]5/2.sup.+[422] orbital originating from the proton g.sub.9/2 shell. This level is most likely the ground state. Therefore, the (9/2.sup.+,7/2.sup.+) spin-parity assignment to the ground state of 111.sup.Tc, reported previously, is unlikely. Properties of the yrast band in 111.sup.Tc suggest prolate deformation of this band. There are hints that the deformation of 111.sup.Tc is larger than that of 109.sup.Tc, possibly due to admixtures of oblate-deformed configurations, which lower their excitation energy with increasing neutron number.