The polarization degrees of freedom in photoinduced two-nucleon knockout from finite nuclei are studied. It is pointed out that they open good perspectives to study the dynamics of dinucleons in the medium in detail. The $(\gamma ,pp)$ and $(\gamma ,pn)$ angular cross sections, photon asymmetries, and outgoing nucleon polarizations are calculated for the target nuclei ${}^{16}$O and ${}^{12}$C and photon energies ranging from 100 up to 500 MeV. It is investigated to which degree the two-nucleon emission reaction is dominated by photoabsorption on ${}^3{S}_1\mathrm{}(T=0\mathrm{})\mathrm{}$ proton-neutron and ${}^1{S}_0\mathrm{}(T=1\mathrm{})\mathrm{}$ proton-proton pairs in the nuclear medium. The calculations demonstrate that dominance of $S$-wave photoabsorption in the $(\gamma ,pn)$ channel does not necessarily imply that the reaction mechanism is similar to what is observed in deuteron photodisintegration.

• Received 1 October 1997

DOI:https://doi.org/10.1103/PhysRevC.57.1319