Half-lives and Pn values are presented for 38 precursors among the low yield fission products. Pn values are based on a beta-neutron coincidence technique.

The independent isomer yield ratio for /sup 90/Rb from thermal neutron fission of /sup 235/U has been measured by use of a new technique involving a pulsed reactor and an on-line mass spectrometer facility. The apparent isomer yield ratio was measured for different ion collection time intervals and extrapolated to zero collection time to eliminate interference from /sup 90/Kr decay. The observed isomer yield ratio of 8.7 +- 1.0 is one of the largest ratios measured for a low energy fission process. However, a statistical model analysis shows that the average angular momentum ( = 4.5) deduced from this isomer yield ratio is consistent with average angular momentum for other products from low energy fission. 7 refs.