G -factor and quadrupole moment of the212−isomeric state in 131 La: Signature for a weakly-deformed magnetic rotational band head

Abstract

Abstract The g-factor and the static quadrupole moment of a magnetic rotational band head 21 2 − at 2121 keV in 131La have been determined by means of the time-differential perturbed angular distribution technique. The measured value of the g-factor, + 1.060 ( 4 ) , is in agreement with the theoretical value for a three quasi-proton, π 3 { 11 2 − [ 505 ] ⊗ 5 2 + [ 422 ] ⊗ 5 2 + [ 413 ] } Nilsson configuration assignment. The observed spectroscopic quadrupole moment ratio, Q s ( 21 2 − , 131 La ) Q s ( 19 2 − , 137 La ) = 0.457 ( 4 ) , supports the collective oblate shape ( γ ∼ − 60 ° ) with quadrupole deformation β 2 0.07 . The half-life of the 21 2 − state, 37.2(1) ns, is re-measured with better accuracy.