Measurement of spin-rotation parameters in elastic π + p scattering at a momentum of 1.62 GeV/ c and calibration of a carbon polarimeter

Experimental data on the spin-rotation parameters A and R in elastic π + p interaction were obtained for the first time at a momentum of p π = 1.62 GeV/ c . These data are necessary for unambiguously reconstructing the amplitude of pion-nucleon scattering and, hence, for deducing a correct spectrum of nonstrange baryon resonances. In order to obtain results for the polarization parameters A and R with the minimum possible systematic error, the carbon polarimeter used was preliminarily calibrated in a dedicated experiment; that is, the analyzing power was measured in proton-carbon scattering for incidentproton energies in the range T p =0.7–1.3 GeV. The experimental data reported in the present article were obtained by a collaboration of researchers from the Petersburg Nuclear Physics Institute and Institute of Theoretical and Experimental Physics (ITEP, Moscow) at the ITEP synchrotron.