Angular Correlations in Nuclear Disintegration

In 1969 we feit that the subject of angular correlations in nuclear disintegrat ion had received little special attention at international conferences. It is true that perturbed angular correlations had been discussed at a smalI, highly - specialised meeting at Uppsala in 1963 and that in 1967 certain aspects of perturbed angular correlations had been considered at a conference on hyperfine structure at Asilomar. However, both conferences were very limited in scope from the point of view of a low - energy nuclear physicist. Besides, since these conferences were being held, the field of perturbed ?ngular correlations had received new impetus from the still ex panding application of the implantation of radioactive isotopes in suitable environ ments, from the construction of large superconductive magnets, etc. Meanwhile, the technique of measuring correlations between beta particles and circularly polarized gamma rays had been developed to such a degree that they lent themselves to the in vestigation of beta decay, nuclear structure and charge dependence of nuclear forces. The systematic study of heavy elements had increased the import an ce of alpha-gamma angular correlations which present their own specific problems. Theoretical internal conversion data had become available to such an extent that electron -gamma direct ional correlations became an important tool in the investigation of nuclear structure: in a large number of cases it is more advantageous to study electron -gamma corre lations instead of the commonly measured gamma -gamma directional correlations.