High spin spectroscopy of 137La Original Research Article

We have studied the high spin states in the N=80137La nucleus by in-beam γ-spectroscopic techniques following the reaction 130Te(11B, 4n)137La at Ebeam=52 MeV using an array, consisting of 8 Compton-suppressed Clover germanium detectors. Forty five new γ rays have been assigned to 137La on the basis of γ ray singles, γγ doubles and γγγ triples coincidence data. Thirty eight new levels have been proposed and the level scheme of 137La has been extended above the known 360 ns View the MathML source isomer up to an excitation energy of View the MathML source and spin View the MathML source. The spin-parity assignments for most of the newly proposed levels have been made using the deduced directional correlation orientation and polarisation information for the de-exciting transitions. The new scheme consists, among others, two decay sequences having states with alternating parity connected by E1 transitions. An attempt has been made to understand these interesting structure by a modest shell model calculation.