ABSTRACT
In late 1956, experiments at the National Bureau of Standards demonstrated that the quantum mechanical law of conservation of parity does not hold in the beta decay of 60Co nuclei. This result, reported in the paper An experimental test of parity conservation in beta decay, together with ensuing experiments on parity conservation in µ-meson decay at Columbia University, shattered a fundamental concept of nuclear physics that had been universally accepted for the previous 30 years. Polarization of the nuclei was achieved by cooling a paramagnetic crystal containing 60Co to within 0.003 K and subjecting it to a magnetic field. Basically, parity conservation in quantum mechanics means that two physical systems, one of which is a mirror image of the other, must behave in identical fashion. In other words, parity conservation implies that Nature is symmetrical and makes no distinction between right- and left-handed rotations, or between opposite sides of a subatomic particle.
