Collective Excitation of Unlike Pair States in Heavier Nuclei

The neutron-hole-proton pair (n-p) correlations in heavier nuclei are studied on the basis of the j-j coupling shell model. It is shown that the even parity states as the coherent mixture of many unperturbed (n-p) states are pushed up by the (n-p) repulsive interactions with T=1. The isobaric state T-|Ψ0) can be interpreted as a coherent state with Jπ=0+. The coherent states with non-zero spin arise in the high excited energy region but not higher than that of the isobaric state. They may be strongly excited by the (p, n) reaction. The actual numerical calculations assuming zero-range forces are carried out for the Jπ=1+ states of the nucleus Bi208 which can be produced by the (p, n) reaction using the target nucleus Pb208. The transition strength due to the operator Y-=∑i τi-σi concentrates in the higher energy region, although the spin-orbit splitting plays an important part for distributing the transition strength over the wider energy region.