Beta and gamma ray studies of /sup 144/Cs, /sup 144/Ba and /sup 144 /La

Abstract

These nuclides were obtained by thermal neutron fission in /sup 235/U, the neutrons coming from the R2-0 (Max. 1 MW) pool reactor. The energies and intensities of the gamma lines have been measured in the decay of /sup 144/Cs, /sup 144/Ba and /sup 144/La and the level schemes of /sup 144/Ba and /sup 144/Ce have been established using beta - gamma and gamma - gamma coincidence measurements with Ge(Li) detectors. 12 levels have been placed in /sup 144/Ba and 25 in /sup 144/Ce. The half-life of the first excited state at 199 keV in /sup 144/Ba has been measured: T/sub 1/2/=0.85+or-0.15 nsec. The results are discussed and compared with other recent studies of the neighbouring even masses, to provide evidence for the onset of substantial deformation in the transition neutron region of N=88. (19 refs)