Observation of Magnetic Rotational band in 131 Xe

In shears mechanism, the observed angular momenta along a band are generated by the gradual closing of the quasi proton and quasi neutron angular momentum blades i.e. gradual alignment towards the total angular momentum. This kind of alignment of angular momentum blades results bands consisting of dipole transitions. Such dipole bands are observed in the A ~ 100, 140 and 200 regions and described as Magnetic Rotational (MR) bands in the theoretical framework of shears mechanism [1-3]. Xe isotopes in mass 130 region can be considered as a candidate to exhibit magnetic rotational nature at moderately high spin. Available high-j orbital such as h11/2 for both proton particle and neutron holes can possibly act as two angular momentum blades in order to generate high spin states. Such dipole band at high spin was observed in 123 Xe (N=69) [4], and proposed to be magnetic rotational one involving h11/2 particles and h11/2 holes. As one approaches N=82 shell closure, the expected spherical shape of the nucleus makes it favorable to have shears mechanism. In this connection 131 Xe (N=77) is an ideal candidate to look for such magnetic rotational bands.