DECAY STUDIES OF THE NEUTRON-DEFICIENT ISOTOPES BA114-118

The very neutron-deficient isotopes (114)-Ba-118 were produced in Ni-5 8 induced reactions on Ni-58, Ni-60 or Cu-63 targets. By on-line mass separation of BaF molecules formed in the separator ion source, except ionally pure sources of these isotopes were available for spectroscopi c studies. The beta-decays of Ba-114 (T-1/2 = 0.43(-0.15)(+0.30) s), B a-115 (T-1/2 = 0.45 +/- 0.05 s), Ba-116 (T-1/2 = 1.3 +/- 0.2 s) and Ba -118 (T-1/2 = 5.2 +/- 0.2 s) were investigated for the first time, Ba- 114, Ba-115 and Ba-116 were identified as beta-delayed proton emitters and absolute branching ratios for this decay mode were determined to be 20 +/- 10%, >15%, and 3 +/- 1%, respectively. In the decay study of Ba-118 several gamma transitions were identified, New information was also obtained on the beta-delayed gamma radiation of Ba-117. The spec troscopic data were used to determine the production cross-sections fo r all these isotopes. Results of our half-life measurements and beta-d elayed proton studies are confronted with theoretical predictions. (C) 1997 Elsevier Science B.V.