PION INDUCED REACTIONS ON (4)He IN THE Delta RESONANCE ENERGY REGION

Measurement of the in-medium modifications of the $Delta$ resonance, signatures of the excitation of nuclear collective states and the first experimental evidence for a thermal emission of photons have been obtained from the analysis of new $\pi^{\pm}$ $^4$He data at $T_\pi$ =106 MeV at PAINUC experiment

Two-prong pi(-4) He interactions at 106 MeV

\u3c0-4He interactions at 106MeV, with two secondary charged particles in the final state, have been studied using a self-shunted streamer chamber in a 0.65T magnetic field and equipped with two CCD videocameras for obtaining digitized stereo-images of nuclear events occurring within the fiducial volume of the streamer chamber. Branching ratios for the various interaction channels are deduced. Evidence is presented for a reaction channel involving a \u3b3 produced in the final state, as well as for the first observation of direct \u394- -resonance production. Cross-section distributions for the elastic and quasi-elastic interaction channels are also reported