1st Identification Of Dipole Excitations To A 2+Circle-Times-3-Circle-Times Particle Multiplet In An Odd-A Nucleus

A photon scattering experiment has been performed on the odd-A nucleus Nd-143. Strong dipole excitations have been detected in the energy region around 3.2 MeV. This is near the expected position of the two-phonon (2+ x 3-) multiplet in the even-even neighboring nucleus Nd-142. The summed dipole strength between 2.8 and 3.6 MeV in Nd-143 is in agreement with the sum rule for weak particle coupling to the core nucleus Nd-142. Model calculations in a harmonic approximation are in very good agreement with the experiment and they suggest a two-phonon (2+ x 3-) particle structure of the excitations in Nd-143.