Level scheme and electromagnetic transition strengths in 177Lu

Abstract

In the 176 Lu(n th ,γ) 177 Lu reaction, γ-ray and conversion electron spectra were measured using the bent crystal spectrometers GAMS and the spectrometer BILL, respectively. An extension of the low-lying level scheme of 177 Lu is achieved. Further, γγ delayed-coincidence lifetime measurements were performed and the following half-lives of excited states in 177 Lu were determined for the first time: T 1 2 (811.543 keV ) = 1.0(1) ns , T 1 2 (1356.930 keV ) = 11(2) ns and T 1 2 (1544.277 keV ) = 0.8 −0.1 +0.2 ns . The strengths of the observed M1, E2 and E1 transitions are compared to rotor-plus-quasiparticle calculations. The enhancement of the newly established K -forbidden E1 transitions linking the 5 2 + [402] and 9 2 − [514] bands may be explained by the influence of the octupole modes. The quadrupole deformation associated with the 1 2 − [541] band is deduced from the measured B( E2 , 9 2 − 1 2 → 5 2 − 1 2 transition strength and found to be larger than that of the ground state. The intrinsic configurations of isomeric three-quasiparticle states are discussed.