A discussion is made of the ways in which parity conservation in ordinary strongly interacting nuclear systems might be investigated. Three classes of experiment are proposed: in class I we look for violations of absolute selection rules based on strict parity conservation and are sensitive to ${\mathfrak{F}}^2$, the intensity of the irregular or parity-nonconserving part of the wave functions; in class II we look for longitudinal polarization of product heavy particles or circular polarization of gamma rays from initially unpolarized systems and are here sensitive directly to $\mathfrak{F}$; in class III we look for odd powers of $cos\theta$ in the angular distributions or correlations of radiations emitted from well-isolated nuclear states and are again sensitive to ${\mathfrak{F}}^2$.

An experiment of class I is presented, namely a search for the radiative capture ${\mathrm{He}}^4(d, \gamma ){\mathrm{Li}}^6$ through the 0+ state at 3.56 Mev. It is concluded that the heavy-particle width of this state is zero within a standard deviation of 0.2 ev and that this corresponds to ${\mathfrak{F}}^2\lesssim 1\times {10}^{-7\mathrm{}}$.

• Received 22 October 1957

DOI:https://doi.org/10.1103/PhysRev.109.1603