Measurement of Proton-Proton Triple Scattering at 430 MeV

The polarization parameters $P$, $D$, $R$, $A$, and $A^{\prime }$ 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 $\epsilon$ was determined by fitting the data to a distribution $1+\epsilon cos\theta$ 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×${10}^6$ pictures were taken. The pictures were scanned and measured on angular encoding machines with a least count of $\frac{1}{3}$ deg. The measurements are compared with the extrapolations of several phase-shift and resonance analyses of experimental data at higher and lower energies.