Elastic Proton-Proton Scattering at 90° and Structure within the Proton

Abstract

The differential cross section for proton-proton elastic scattering at 90\ifmmode^\circ\else\textdegree\fi{} in the center-of-mass system was measured at laboratory momenta ranging from 5.0 to 13.4 $\frac{\mathrm{GeV}}{c}$. Fifty-one measurements were made at momentum intervals of 100 or 200 $\frac{\mathrm{MeV}}{c}$. The extracted proton beam of the ZGS impiniged upon a C${\mathrm{H}}_{2}$ target. The two scattered protons were detected by two spectrometers consisting of magnets and scintillation counter telescopes in coincidence. The incident beam flux was measured by radiochemical analysis of the C${\mathrm{H}}_{2}$ targets. The experiment showed no evidence for any $S=0$, $T=1$ dibaryon resonances in the 3300-5200-MeV mass range. It also yielded some information about the validity of the statistical model and the analyticity of the scattering amplitude. The most interesting result of the experiment was a sharp break in the fixed-angle cross section. This may be evidence for the existence of two inner regions of the proton with radii 0.51\ifmmode\pm\else\textpm\fi{}.02 and 0.34\ifmmode\pm\else\textpm\fi{}.02 F.