Properties of high-spin states in 95Tc from 93Nb(α,2n)95Tc* (γ) reaction spectrometry: A test of the cluster-core coupling model

The structure and properties of the high angular momentum states in 95Tc up to 5605 keV of excitation have been investigated via measurements of excitation functions of γ ray singles and γγ coincidences following the 93Nb(α,2n)95TC*(γ) reaction with α-particle energies between 17 and 30 MeV. From these experiments and from high-resolution singles energy, angular-distribution, and Doppler-shift attenuation measurements, the position and the decay properties of many high angular momentum state in 95Tc have been determined. Eleven levels with J/sup π/ values were confirmed, and 14 new levels with J/sup π/ values are proposed. Other possible levels are also suggested. The measured angular distributions provided (i) branching ratios, (ii) J/sup π/ assignments corroborated by deduced angular-distribution attenuation coefficients, level excitation functions and side-feeding yields, and (iii) multipole mixing ratios delta (E2/M1). Lifetimes for nine high-spin levels and limits for four additional ones were obtained by the Doppler-shift attenuation method from measurements with the 93Nb(α,2n)95Tc* (γ) reaction at 18.5, 20.6, 23.6 and 26.7 MeV. The lifetimes were extracted from singles spectra taken 00 and 900 by examining the dependence on E/sub α/ of the effective level lifetime. For many transitions B(E2) and B(M1) values were obtained. The present results are compared with calculations based on the coupling of three-quasiparticle (g9/2)3 configurations to the quadrupole vibrations of the core, and remarkable agreement is observed for states up to only 19/2+1. This model fails to explain the properties of the higher-spin states with J/sup π/ greater than or equal to 21/2+