Evidence for an i13/2 neutron band in¹³³Sm

A rotational band of nine ?-rays has been observed in133Sm. The moment of inertia of the band indicates that it has a higher deformation than expected for states in nuclei in this region. The properties are such that it can be interpreted as being due to the odd neutron occupying the ? i2/13 nn intruder orbital. This is the first evidence for the occupation of this orbital in nuclei with neutron number N<73.