Laser oriented 36K for time reversal symmetry measurements

We have produced very large nuclear alignments in radioactive 36K (half-life 0.34 sec) through laser optical pumping techniques. The 36K was created through (p,n) reactions using a 50 nA, 22 MeV proton beam, and a 3.3 atmosphere 36Ar target. Measurements were made with the target cell at room temperature, when direct optical pumping produces nuclear orientation in the 36K, and at elevated temperatures 160 degree C and 180 degree C where the 36K is oriented through a combination of direct optical pumping and spin exchange. The fraction of the maximal nuclear alignment for the 180 degree C data was determined to be 0.46±0.07 stat±0.05 syst through measurements of the γ-ray anisotropy following positron decay. Roughly 105 or more decays of oriented 36K occurred each second. The application of the superallowed decay of 36K to measurements of time-reversal symmetry in β decay is discussed