High resolution studies of short-lived nuclear isomers.

A versatile apparatus for studying short-lived nuclear isomers has been constructed. Using high resolution semi-conductor gamma-ray and conversion electron detectors, detailed studies of short-lived isomeric activities were undertaken. Improved data were obtained concerning a 90 micro-seconds isomer previously assigned to 121I . New information includes multipolarity determinations, relative intensity measurements, a revised assignment (to 122I), improved energy measurements, and the detection of at 1east one new transition (51.9 keV) and possibly two others. A new 293 micro-seconds M2 isomeric transition of 117 keV energy was assigned to 190Ir. New isomeric transitions, 166.5 keV (E2) and 47 keV (M2, or possib1y E2), were found in 189Pt (149 micro-seconds) and 191pt (100 micro-seconds), respectively; and two longer-lived transitions, 319.9 keV and 205 keV, were attributed to the decays of 189m-Au (5.0m) and 190m2-Ir (3.5 h), respectively. Tentative decay schemes are proposed which include these isomeric transitions