Analysis of two-prong events inppinteractions at205 GeVc: Separation of elastic and inelastic events

Abstract

We present results of complete measurements of the two-prong events observed in a 50 000-picture exposure of the 30-in. hydrogen bubble chamber to a $205\ensuremath{-}\frac{\mathrm{GeV}}{c}$ proton beam at the National Accelerator Laboratory. Using kinematic fitting, elastic and inelastic events are separated and cross sections are obtained. The total two-prong cross section is measured to be 9.77 \ifmmode\pm\else\textpm\fi{} 0.40 mb, of which 2.85 \ifmmode\pm\else\textpm\fi{} 0.26 mb represents the inelastic contribution. The total elastic cross section is measured to be 6.92 \ifmmode\pm\else\textpm\fi{} 0.44 mb. Our data are consistent with the break in $\frac{d\ensuremath{\sigma}}{\mathrm{dt}}$ at $|t|\ensuremath{\sim}0.1\ensuremath{-}0.2 {(\frac{\mathrm{GeV}}{c})}^{2}$ observed at the CERN ISR. A prominent low-mass enhancement is observed in the distribution of missing mass squared from the slow proton for the inelastic events. An analysis based on the missing-mass spectrum and the particle rapidities shows that this low-mass enhancement accounts for about 77% of the total inelastic two-prong cross section. The diffractive cross section in the two-prong events is 2.20 \ifmmode\pm\else\textpm\fi{} 0.25 mb, in agreement with certain two-component models.