Level Structure and Transition Probabilities in¹⁶⁵Tm and¹⁶⁷Tm

Abstract

Transitions in 165Tm and 167Tm have been studied by means of the (p,nγ) and (p,2nγ) reactions. Singles gamma-ray spectra, gamma-gamma coincidences and conversion electron spectra have been recorded. The level schemes of both isotopes have partly been verified and new members of the 1/2-[541] band have been found in 167Tm. The halflives of three levels in the ground state bands have been measured using an electron-electron coincidence spectrometer: T 1/2 = 322 ± 20 ps for the I = 7/2 level in 165Tm, T 1/2 = 343 ± 15 ps for the I = 7/2 level in 167Tm and T 1/2 = 66 ± 7 ps for the I = 5/2 level in 167Tm. The electric and magnetic moments have been compared for the odd thulium isotopes. It was also shown that the quadrupole deformation ϵ2 is constant and that the systematics of the single particle states in these isotopes only may be explained by variations of the hexadecapole deformation, ϵ4 of the nuclear shape.