Pion emission in 2H, 12C, 27Al, gamma pi+ reactions at threshold

Golubev, P.; Avdeichikov, V.; Fissum, K. G.; Jakobsson, B.; Pshenichnov, I. A.; Briscoe, W. J.; O'Rielly, G. V.; Annand, J.; Hansen, K.; Isaksson, L.; Jaederstrom, H.; Karlsson, M.; Lundin, M.; Schroeder, B.; Westerberg, L.

Pion emission in 2H, 12C, 27Al, gamma pi+ reactions at threshold

Authors

Description

The first data from MAX-lab in Lund, Sweden on pion production in photonuclear reactions at threshold energies, is presented. The decrease of the total yield of pi+ in gamma + 12C, 27Al reactions below 200 MeV as well as differential, dsigma/dOmega, cross sections follow essentially predictions from an intranuclear cascade model with an attractive potential for pion-nucleus interaction in its simplest form. Double differential, d2sigma/dOmegadT, cross sections at 176 MeV show, however, deviations from the model, which call for refinements of nuclear and Coulomb potentials and possibly also for coherent pion production mechanisms.
19 pages, 7 figures