LASER ORIENTED K-36 FOR TIME-REVERSAL SYMMETRY MEASUREMENTS

We have produced very large nuclear alignments in radioactive K-36 (ha lf-life 0.34 sec) through laser optical pumping techniques. The K-36 w as created through (p,n) reactions using a 50 nA, 22 MeV proton beam, and a 3.3 atmosphere Ar-36 target. Measurements were made with the tar get cell at room temperature, when direct optical pumping produces nuc lear orientation in the K-36, and at elevated temperatures 160 degrees C and 180 degrees C) where the K-36 is oriented through a combination of direct optical pumping and spin exchange. The fraction of the maxi mal nuclear alignment for the 180 degrees C data was determined to be 0.46+/-0.07 stat+/-0.05 syst through measurements of the gamma-ray ani sotropy following positron decay. Roughly 10(5) or more decays of orie nted K-36 occurred each second. The application of the superallowed de cay of K-36 to measurements of time-reversal symmetry in beta decay is discussed.