Design and performance of a magnetic spectrometer for the study of πp → ππN reactions near threshold

Abstract A measurement of the cross sections of several π p → ππ N reaction channels in the region of incident pion momenta of 300 to 460 MeV/ c has been performed with Omicron, a multi-arm magnetic spectrometer of large solid angle. This paper describes the apparatus, the trigger, the readout and data-acquisition systems and the off-line analysis. Sample data illustrating the operation of the apparatus are also presented.