An experimental study of large-angle elastic scattering of charged mesons and antiprotons on protons at 20 and 30 GeV/c incident momenta

A description is given of an experiment to study elastic scattering of π ±, K ± and p on protons at c.m. scattering angles from 45° to 100° at incident laboratory momenta 20 GeV/ c and 30 GeV/ c. The corresponding t range is from −6.2 (GeV/ c) 2 to −28 (GeV/ c) 2. There are no previous observations for these reactions in this t range. High intensity and large geometrical acceptance were required in order to measure the low cross sections. The experiment used a double-arm spectrometer. MWPCs were used for reconstruction, and threshold and differential Čerenkov counters for identification. Scintillation counters, Čerenkov counters and a hadron calorimeter were used in the trigger. The trigger logic utilized specially designed matrices and a hard wired microprocessor. The π −p elastic scattering cross sections follow approximately the dimensional counting rule from 3.5 GeV/ c.and up to 30 GeV/ c. The cross sections decrease by seven orders of magnitude in this energy range. The data is compared to quark models. None of these models give a comprehensive description of the results. However, some modifications to these models improve their consistency with the data.