Inelastic Proton-Proton Scattering at 1.35, 2.1, and 2.9 BeV

Absolute measurements have been made of the momentum spectrum of protons inelastically scattered from protons at incident kinetic energies of 1.35, 2.1, and 2.9 BeV, and at angles from 2° to 17° in the laboratory system. Peaks in these spectra were found at momenta corresponding to excitation of the resonances occurring in $\pi -p$ scattering at 180-, 600-, and 900-MeV laboratory kinetic energies. A simple calculation of the inelastic spectra based on the one-pion-exchange (OPE) model is presented, and found to be in general agreement with the experimental data for values of the square of the invariant four-momentum transfer, ${\Delta }^2$, less than $6{m_{\pi }}^2$. For larger values of ${\Delta }^2$ the theory overestimates. When values of the differential cross section at the position of the $J=T=\frac{3}{2}$ resonance are compared with predictions of the OPE calculation, the ratio is found to be a smooth function of ${\Delta }^2$ out to a value of $55{m_{\pi }}^2$, the limit reached in this experiment. To within 20% this ratio appears to be independent of incident proton energy for our range of observation. The differential cross sections at the peaks corresponding to the $T=\frac{1}{2}$ resonances are closer to the theoretical values than for the $T=\frac{3}{2}$ resonance, for the same value of ${\Delta }^2$.