STRETCHED PROTON-NEUTRON CONFIGURATIONS IN FP-SHELL NUCLEI .1. EXPERIMENTAL RESULTS OF THE (ALPHA, D) REACTION

The (alpha, d) reaction has been investigated at bombarding energies a round 55 MeV on Ca-40,Ca-42,Ca-44,Ca-48, Cr-50,Cr-52,Cr-54, Fe-54,Fe-5 6,Fe-58, Ni-58,Ni-60,Ni-62,Ni-64, Zn-64,Zn-66 and Ge-70,Ge-72 targets. The angular distributions of prominent transitions were analyzed with the distorted-wave Born approximation and shown to correspond to unna tural-parity stretched proton-neutron configurations. Strong transitio ns of (g9/2)9+(2) and (p3/2, g9/2)6- character were identified in most final nuclei. Additionally, dominant transitions with (f7/2, g9/2)8- StruCture were observed for target nuclei with an open proton f7/2 she ll. These stretched high-spin states could be consistently described b y an average normalization constant N = 225 +/- 85 indicating their re latively pure two-nucleon structure. In the lower-mass Sc and Mn isoto pes, configurations built on g9/2 states are increasingly damped becau se of the strong fragmentation of the underlying single-particle stren gth.