Investigation of level properties of 139La

Abstract

The excited states of 139La up to 1800 keV were studied by means of Coulomb excitation of 139La with protons varying in energy from 4.0 to 5.5 eV. The gamma-ray yields and angular distributions were measured with a Ge(Li) detector. The levels at 1715.0 and 1767.2 keV were Coulomb excited newly. The results of gamma-ray angular distribution measurements establish spin values of 3/2+, 9/2+, 7/2+, 5/2+, and 3/2+ for the 830, 1219.1, 1536.3, 1715.0, and 1767.2 keV levels, respectively. The reduced E2 and M1 transition probabilities were obtained for 11 transitions. The results were compared with the available theoretical calculations.