Polarization degrees of freedom in photoinduced two-nucleon knockout from finite nuclei

Abstract

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 photonenergies ranging from 100 up to 500 MeV. It is investigated to which degree the two-nucleon emission reaction is dominated by photoabsorption on ${}^3{S}_1(T=0)$ proton-neutron and ${}^1{S}_0(T=1)$ 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.

Comments: 27 pages, REVTeX 3.0 with epsf.sty, 11 figures in EPS format