Download or read book Nucleon-nucleon Correlations Detected Via Pion Double-charge-exchange Reactions written by and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Double-charge-exchange reactions induced by pions are shown to furnish a direct means of detecting nucleon-nucleon correlations in nuclei. For the particular case of double isobaric analog transitions the effect of correlations is easily isolated and quite strong. Examination of the properties of the position correlations implicit in the nuclear shell model provides an explanation of several experimentally observed features of double-charge-exchange reactions, including in particular, their dependence on the number of valence neutrons present. An explicit demonstration of the role played by nucleon-nucleon correlations is presented for the double-charge-exchange cross-sections of 42Ca, 44Ca and 48Ca, recently measured at LAMPF. Our analysis explains why the cross section for the double-charge-exchange reaction on 48Ca, in which 28 neutron pairs participate, is comparable and indeed smaller than the corresponding cross-section for 42Ca with its single valence neutron pair. It also predicts the variation of angular distributions over the family of isotopes. 13 refs., 3 figs.