Scintillation Counting in Experiments on Parity Conservation

The scintillation counter has played a key role in many of the recent experiments pertaining to the conservation of parity and other symmetry principles in weak interactions. Although in many instances the development of the techniques of scintillation counting, per se, has been limited, the applications to which these techniques have been put are sufficiently novel to warrant a general review of these applications to the measurement of certain dynamical quantities in weak interactions. These quantities include the momentum and angular distribution of emission with respect to nuclear polarization direction of beta particles from polarized nuclei, the longitudinal polarization of these beta particles, the circular polarization and angular distribution of gamma rays following the beta decay process, and any correlations of these quantities with one another or with the nuclear recoil. Particular emphasis is placed on the scintillation spectroscopy of beta particles performed within the vacuum space of a cryostat where the temperature of the detector is of the order of 1°K and that of the source is below 0.01°K and where high magnetic fields are present.