Selected Citation

Further Experiments on β Decay of Polarized Nuclei

Authors(s):E. AMBLER, R. W. HAYWARD, D. D. HOPPE, R. P. HUDSON, AND C. S. WU Publication:Physical Review Publication Date:June 15, 1957 Publisher: American Physical Society Citation:/PhysRev.106.1361 Link:

In a previous communication we reported that we observed a large asymmetry in the angular distribution of electrons from polarized Co60 nuclei. It was concluded that unequivocal proof was thereby established of the nonconservation of parity as well as of noninvariance under charge conjugation in beta decay. It was also pointed out that according to Lee, Oehme, and Yang, invariance under time reversal could also be investigated by studying the momentum dependence of the asymmetry parameter ß. Since then we have made further measurements and checks. In particular we have carried out similar experiments' with Co58 and observed an asymmetry in the positron emission with a coefficient opposite in sign and roughly one third of that from Co60.

Unfortunately this term for Co60 is rather small, the upper limit for its contribution to ß being only 2X (28/137) X (1/√3) =0.24. [This statement is footnoted to Rustad-Ruby (1953).]