The Angular Correlation of Two Successive Nuclear Radiations

A general formula is derived, using group-theoretic methods, which gives the correlation as series in Jacobi polynomials whose argument depends on the angle between the radiations. The coefficients factor into quantities depending on the separate nuclear transitions, and the factors are worked out explicitly for the directional correlation cases where one of the interfering radiation angular momenta is the lowest or next-lowest allowed by conservation of angular momentum. Correction factors are given for converting lowest multipole $\gamma -\gamma$ correlations into an extensive class of directional correlations.