New experimental results on the ππ interaction in nuclear matter

Single pion production A(π +, π + π ±) was investigated in nuclei (2H 12C, 40Ca, 208Pb) at an incident pion energy of T π+=280 MeV. Data were obtained at TRIUMF using the CHAOS spectrometer which detected the two final pions in coincidence. The results presented focus here on two aspects of the ππ reaction in nuclei: the reaction mechanism and the invariant mass behaviour above the 2m π threshold.