Decay studies of neutron-deficient nuclei near the Z=64 subshell: 141Dy, 141Tb, 141Gdg+m, and 141Eum.

Abstract

The {beta}/{gamma} and delayed proton decays of mass separated {ital A}=141 isotopes with {ital Z}=63--66 were investigated with an on-line mass separator. Branching ratios have been redetermined for the total {beta} decay of the 2.7(3) s, (11/2){sup {minus}} isomer {sup 141}Eu{sup {ital m}} at 96.5 keV (13{sub {minus}2}{sup +4}%), and for the direct {beta} feeding of the 1.58 keV (3/2){sup +} level of {sup 141}Sm in the decay of 40-s {sup 141}Eu{sup {ital g}} (73(5)%). Detailed decay schemes have been constructed for the decays of the (11/2){sup {minus}} isomer {sup 141}Gd{sup {ital m}} (11(2)% isomeric transition) and the (1/2){sup +} ground state, {sup 141}Gd{sup {ital g}}. Half-lives of 24.5(5) s and 14(4) s, respectively, have been determined for these isomers. A delayed proton branch of 0.03(1)% was identified in the decay of {sup 141}Gd{sup {ital g}}. A detailed decay scheme was also constructed for 3.5(2)-s {sup 141}Tb and a {ital J}{sup {pi}}=(5/2{sup {minus}} ) was assigned to its ground state, at variance with the systematics of heavier, odd-mass Tb isotopes. All {gamma}-ray assignments to the various isotopes are based on {ital x}{gamma} and {gamma}{gamma} coincidences and on half-life measurements. A 0.9(2)-s half-life for {sup 141}Dy was determined from its delayedmore » proton decay. All spin assignments proposed in this paper are discussed in terms of Nilsson level diagrams and nuclear shapes.« less