SPECTROSCOPIC STUDIES IN A=90 MASS REGION .2. NEUTRON HOLE STATES IN N=49 NUCLEI

Single neutron hole states in N = 49 nuclei were investigated using the (3He, α) reaction on 88Sr, 89Y, 90Zr and 92Mo, at 18 MeV bombarding energy. The energy resolution was of the order of 60-70 keV. States corresponding to the shell-model orbitals 1g 9 2, 2p 1 2, 2p 3 2 and1f 5 2 have been observed in all residual nuclei. Absolute differential cross sections have been measured between 25° and 80° in 5 degree steps and analysed using the Oak Ridge DWBA code JULIE. The dependence of the DW cross section on several parameters entering in the calculation of the form factor is investigated. The presence of configuration mixing in the residual nuclei is suggested by the excitation of the more states than predicted by shell-model considerations. In 88Y the neutron states are weakly coupled to the old proton configuration up to 1 MeV excitation energy. At higher excitation the coupling picture is more complicated. © 1969.