Measurement of Proton-Proton Triple Scattering at 430 MeV

The polarization parameters P, D, R, A, and A^' have been measured at 7 scattering angles between 30^∘{} and 120^∘{} in the center-of-mass system with an incident energy of 430 MeV. A 56% polarized beam was prepared by scattering on an internal beryllium target in the Chicago synchrocyclotron. A liquid-hydrogen target was used for the p-p scattering and the outgoing polarization was analyzed with a third scattering in the carbon plates of a spark chamber. The scattering asymmetry ε was determined by fitting the data to a distribution 1+εcosθ by the maximum-likelihood method. The analyzing power of the spark chamber as a function of energy was measured in beams of known polarization. The beam polarization before and after the p-p scattering was manipulated with a solenoid and two bending magnets. During a 5-week run, 1.4×{}10⁶ pictures were taken. The pictures were scanned and measured on angular encoding machines with a least count of 1/3 deg. The measurements are compared with the extrapolations of several phase-shift and resonance analyses of experimental data at higher and lower energies.