First-forbidden non-unique -transitions and mirror comparisons in light nuclei Academic Article uri icon


  • Shape factors and longitudinal polarisations are calculated for first-forbidden non-unique -decays between spin- 1 2 states in masses A = 15 and A = 17. The nuclear matrix elements are evaluated using particle-hole models. Core-polarisation corrections are included to first order in perturbation theory. A characteristic hindrance becomes evident, which reduces all nuclear matrix elements in magnitude with the electric-dipole matrix element being particularly retarded. A consequence is that the energy spectrum has very nearly the allowed shape, contrary to expectations for high-energy decays in light nuclei. It is argued, however, that nuclear matrix elements may be determined from experimental shape factors and in particular that improved accuracy results from the comparison of mirror transitions under the assumptions of strict mirror symmetry. On the other hand, longitudinal polarisations are shown to be very insensitive to matrix elements in high-energy, light-nuclei situations. 1972.

published proceedings

  • Nuclear Physics A

author list (cited authors)

  • Towner, I. S., & Hardy, J. C.

citation count

  • 24

complete list of authors

  • Towner, IS||Hardy, JC

publication date

  • January 1972