Multiple magnetic rotational bands based on proton alignment inEu143

Abstract

High-spin dipole structures in $^{143}\mathrm{Eu}$ have been studied via the fusion-evaporation $^{116}\mathrm{Cd}$ $(^{31}\mathrm{P}$, $4n)$ reaction at a beam energy of 148 MeV using a clover detector array (Indian National Gamma Array). The parity of the two observed dipole bands has been firmly established from linear polarization measurements. Level lifetimes of these bands have been measured using the Doppler shift attenuation method. The drop in $B(M1)$ values with spin exhibits a clear signature of the magnetic rotational character of these two bands. Configurations were assigned to the bands in the framework of the shears mechanism with the principal axis cranking model calculation. Alignment of an additional proton in the ${h}_{11/2}$ orbital gives rise to the unique observation of a large increase in the $B(M1)$ values for the higher-lying band.