Chronology of Milestone Events in Particle Physics - WU 1957
Chronology of Milestone Events in Particle Physics

WU 1957

Wu, C.S.; Ambler, E.; Hayward, R.W.; Hoppes, D.D.; Hudson, R.P.;
Experimental Test of Parity Conservation in Beta Decay
Phys. Rev. 105 (1957) 1413;

Reprinted in
R. N. Cahn and G. Goldhaber, The Experimental Foundations of Particle Physics, Cambridge Univ. Press (1991) 171.
The Physical Review - the First Hundred Years, AIP Press (1995) 361.

Motivation
In a recent paper on the question of parity in weak interactions, Lee and Yang critically surveyed the experimental information concerning this question and reached the conclusion that there is no existing evidence either to support or to refute parity conservation in weak interactions. They proposed a number of experiments on beta decays and hyperon and meson decays which would provide the necessary evidence for parity conservation or nonconservation. In beta decay, one could measure the angular distribution of the electrons coming from beta decays of polarized nuclei. If an asymmetry in the distribution between and 180 - (where is the angle between the orientation of the parent nuclei and the momentum of the electrons) is observed, it provides unequivocal proof that parity is not conserved in beta decay. This asymmetry effect has been observed in the case of oriented 60Co. (Extracted from the introductory part of the paper.).

Accelerator SOURCE Detectors CNTR

Related references
More (later) information appears in
T. D. Lee, R. Oehme, and C. N. Yang, Phys. Rev. 106 (1957) 340;
See also
T. D. Lee and C. N. Yang, Phys. Rev. 104 (1956) 254;
E. Ambler et al., Phil. Mag. 44 (1953) 216;

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  60Co 60Ni e e asym

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First evidence for parity nonconservation in weak decays.
    
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