High spin spectroscopy of 137La

We have studied the high spin states in the N = 80 La-137 nucleus by in-beam gamma-spectroscopic techniques following the reaction Te-130(B-11, 4n)La-137 at E-beam = 52 MeV using an array, consisting of 8 Compton-suppressed Clover germanium detectors. Forty five new gamma rays have been assigned to La-137 on the basis of gamma ray singles, gamma gamma doubles and gamma gamma gamma triples coincidence data. Thirty eight new levels have been proposed and the level scheme of La-137 has been extended above the known 360 ns 19/2(-) isomer up to an excitation energy of similar to 6 MeV and spin 39/2 h. 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 El transitions. An attempt has been made to understand these interesting structure by a modest shell model calculation. (c) 2006 Elsevier B.V. All rights reserved.