PION ABSORPTION ON HE-3 AND HE-4 WITH EMISSION OF 3 ENERGETIC PROTONS

Results from a 4 pi solid angle measurement of the reactions He-3(pi(),ppp) and He-4(pi(+),ppp)n at incident pion energies of Tpi+ = 70, 11 8, 162, 239, and 330 MeV are presented. For He-3 the total absorption cross sections and their decomposition into two-proton and three-proto n components are evaluated; for He-4 the three-proton absorption cross sections are given. The differential distributions of the three-proto n multinucleon absorption mode of both nuclei are analyzed and compare d to each other by making use of a complete set of variables. The data are investigated for signatures of initial and final state interactio ns: it is found that more than half of the three-proton yield cannot b e accounted for by cascade mechanisms. The remaining strength shows de pendence on the incident pion angular momentum, but also structures th at are not explained by simple semiclassical models.