Pion absorption on<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow/><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>He and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow/><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>He with emission of three energetic protons

Results from a 4$\ensuremath{\pi}$ solid angle measurement of the reactions ${}^{3}$He$({\ensuremath{\pi}}^{+},ppp)$ and ${}^{4}$He$({\ensuremath{\pi}}^{+},ppp)$$n$ at incident pion energies of ${T}_{{\ensuremath{\pi}}^{+}}=$70, 118, 162, 239, and 330 MeV are presented. For ${}^{3}$He the total absorption cross sections and their decomposition into two-proton and three-proton components are evaluated; for ${}^{4}$He the three-proton absorption cross sections are given. The differential distributions of the three-proton multinucleon absorption mode of both nuclei are analyzed and compared to each other by making use of a complete set of variables. The data are investigated for signatures of initial and final state interactions: it is found that more than half of the three-proton yield cannot be accounted for by cascade mechanisms. The remaining strength shows dependence on the incident pion angular momentum, but also structures that are not explained by simple semiclassical models.