Atomic antiproton states in 16O, 18O, 32S, 40Ca, 44Ca and 122Sn

An exploratory study of antiproton-nucleus scattering

“…Indeed, essentially these data only determine [6] certain moments. Consequently, it has been customary [1,2] in phenomenological analyses to make the simplest assumption that the potential follows the shape of the density distribution of the target nucleus, leaving the real and imaginary strengths as two adjustable parameters.…”

“…repulsive), W= 150 MeV at E= 175 MeV; these we call the GW potentials. More recently, Niskanen and Green [6] have calculated/7 scattering by potentials explicitly constructed for positive energies, but without medium effects. The real parts of these potentials rapidly become attractive as the energy increases so, for example, that for /7+ 160 at 130 MeV is about 130 MeV deep at r=0.…”

“…Green and Wycech [6] use multiple scattering theory with the Dover-Richard NN-interaction [10]. In the low-density limit their optical potential is repulsive.…”

“…Two groups [6,8] have recently constructed optical potentials appropriate for low-energy antiprotons (such as the bound states of/7-atoms), based upon two-body interactions that reproduce NN scattering. Green and Wycech [6] use multiple scattering theory with the Dover-Richard NN-interaction [10].…”

“…Differential cross sections for elastic scattering are required, and these should soon be available from the LEAR facility at CERN. In anticipation, we have made an exploratory study, taking several representative optical potentials either derived from analyses [2] of/5-atomic data or suggested by those constructed theoretically [6][7][8]. These potentials vary quite widely in their characteristics, with real parts ranging in depth from almost zero (or even repulsive) to over 600 MeV, and with absorptive parts that vary in strength by an order of magnitude.…”