GRID and multiphonon states

Abstract

The development of the GRID technique for determining nuclear level lifetimes of excited low-spin states populated in thermal neutron capture reactions has resulted in the ability to perform detailed studies of proposed multiphonon excitations for the first time. This paper discusses the experimental evidence for multiphonon excitations determined using the GRID technique. In deformed nuclei several good examples of γγKπ = 4+ excitations have been established, whereas the experimental evidence gathered on Kπ= 0+ bands is contradictory, and any interpretations will likely involve the mixing of several different configurations. In vibrational nuclei the GRID technique has helped to establish the existence of multiple quadrupole phonon excitations in 114Cd, and an almost complete set of quadrupole-octupole coupled states in 144Nd.