The Fragmentation Of The F-P Neutron-Hole Strength In Mo-91 Below 6 Mev Excitation-Energy

The nucleus 91Mo has been investigated in the excitation energy region between 2.2 and 6.2 MeV by means of the 92Mo (3He, alpha ) reaction at 25 MeV incident energy. Forty-three levels have been observed with 25-30 keV energy resolution and angular distributions were measured between 5 degrees and 50 degrees . DWBA analysis has led to unambiguous l assignments for most levels. Fifteen previously unknown l=3 levels are observed around 4 MeV. These levels could be interpreted as components of the f7/2 neutron-hole strength, but the summed spectroscopic factors are much lower than the shell-model sum-rule limit. In addition, 14 l=1 levels were observed between 3 and 6 MeV excitation energy.