BETA DECAY OF B-13

The decay of B13 has been studied by means of plastic and NaI (Tl) scintillation detectors. The activity was formed in the B11(t,p)B13 reaction using a mechanically chopped beam of 3.0-MeV tritons from a Van de Graaff accelerator.Coincidence measurements have confirmed a previously reported branch to the 3.68-MeV second excited state of C13. By means of a neutron time-of-flight method, branches to neutron-emitting levels of C13 at 7.5 and 8.86 MeV have been observed. The C13 levels in MeV, B13 branches to these levels in percent, and the corresponding logft values are ground, 92.1±0.8, 4.02±0.02; 3.68, 7.6±0.8, 4.47±0.05; 7.5, 0.094±0.020, 5.37±0.09; and 8.86, 0.16±0.03, 4.63±0.08. The present results are consistent with recent assignments of 52- and 12- to the 7.55- and 8.86-MeV C13 levels, respectively. It is suggested that the 7.55-MeV member of the 7.50-7.55-7.68 C13 triplet is the one populated in B13 decay. The experimental logft values agree well with theoretical calculations by Cohen and Kurath. © 1969 The American Physical Society.