Near-yrast, medium-spin structure of the Tc-109 nucleus

作者：Urban W^*; Pinston J A; Rzaca Urban T; Kurpeta J; Smith A G; Ahmad I

来源：Physical Review C, 2010, 82(6): 064308.

DOI：10.1103/PhysRevC.82.064308

Excited levels in the Tc-109 nucleus, populated in the spontaneous fission of Cm-248, have been studied using the EUROGAM2 array. In Tc-109 we have found a new band corresponding to the pi 5/2 [303] configuration and a three-quasiparticle band with I-pi = (15/2(-)) band-head level at 1749.5 keV. The structure of the 1749.5-keV level probably involves the {pi 5/2(+)[422]nu(5/2(-)[532], 5/2(+)[413])}(15/2-) prolate configuration. The quasiparticle-rotor model calculations performed in this work show that the odd-proton configurations observed in Tc-107 and Tc-109 are consistent with the scheme of proton excitations in a prolate triaxial potential. Significant differences between the degree of triaxiality observed for positive- and negative-parity excitations may be due to blocking of the triaxial shape by the odd proton populating negative-parity orbitals. The properties of the new 494.5-, 1440.7-, and 1748.8-keV levels found in Tc-109 may indicate a change toward an oblate shape in this nucleus.

• 出版日期2010-12-13