2-PHONON CHARACTER OF THE LOWEST ELECTRIC-DIPOLE EXCITATION IN ND-142AND IN OTHER NUCLEI NEAR SHELL CLOSURES

A resonant inelastic proton scattering experiment was carried out to i nvestigate the gamma decay of the lowest lying 1(-) state in the N = 8 2 nucleus Nd-142. A very high sensitivity for the detection of the gam ma rays was achieved by combining the Osiris Cube array with a Eurobal l Cluster detector. The observed gamma decay of the dipole excitation is a direct proof of the dominant two-phonon character of the lowest 1 (-) state in this nucleus. A survey of the branching ratios in the mag ic neutron number N=82 region and the energy systematics of candidates for two phonon 1(-) states in other nuclei in the vicinity of various shell closures point to a high degree of harmonicity of the (2(+)X3(- )) coupling.