Measurements of Differential Cross Sections and Polarization Effects in Pion-Proton Elastic Scattering in the Momentum Range 875 to 1579 MeV/c

In this paper we discuss some measurements that have been made at Nimrod of differential cross sections and polarization effects in πp elastic scattering. The principal aims of this work were to determine the spins and parities of the N*1/2 (1688) and the N*3/2 (1920) isobars and to examine the behaviour of the π+p elastic scattering cross section at momenta around 950MeV/c where a shoulder exists in the total cross sections. Table 1 gives the values of the momenta at which the measurements were made and figure 1 illustrates their relation to other work that has been done in or near this region. A schematic diagram of the experimental arrangement for measuring the differential cross sections is shown in figure 2. An array of scintillation counters, used in conjunction with a coincidence matrix detected particles scattered from a 4 in. long liquid hydrogen target. All events were accepted in which two and only two outgoing particles were detected in coincidence by any combination of two counters on opposite sides of the beam. The number of counts for each combination was stored in the magnetic core store of a 512 channel pulse height analyser