Optical pumping and laser induced nuclear orientation of a microsecond isomeric level in 134Ba

Using optical pumping techniques, on and off-line experiments were performed on a microsecond nuclear isomer (/sup 134m/Ba[10+]). Shifts in atomic resonances detected by changes in the angular distribution of characteristic nuclear radiations (expressed as changes in shape and size) yield information on changes in nuclear structure. The 10+ isomeric state was produced using a 49 MeV pulsed beam of 13C on an isotopically enriched 124Sn target. The reaction products recoil out of the target and are slowed to thermal velocities in 10 torr of xenon in a region illuminated with circularly polarized light (553.5 nm) from a Coherent 699-21 dye laser. Nuclear parameters measured were the lifetime (3.8(2) μs) and g-factor (g = -0.20(1)) of the 10+ state. Atomic parameters measured for barium were the depolarization cross sections of the 1P1 atomic level (6.0(6) nm2) in xenon, the quenching cross section for hydrogen (0.042(4) nm2), and the branching ratio of the metastable (/sup 1,3/D/sub 1,2,3/) atomic states (0.011(1)). A possible anisotropy signal and the cumulative results (no measurable anisotropy) are presented. Difficulties encountered were insufficient neutralization, and unexpectedly large spatial distribution, and trapping in metastable atomic states