The application of thin-plate spark chambers to high-energy π-p experiments

Abstract

Experiments on elastic pion-proton scattering and peripheral production of pions are described as illustrations of techniques involved in use of spark chambers. Features specifically pointed out include the following: use of thin- plate spark chambers spaced by some distance to sample two portions of a track in order to determine the angle of a track to a high precision; folding of the images of the several spark chambers and their stereoscopic views using a number of mirrors in order to present all the chamber data on a single 35-mm film frame; a method of aligning mirrors accurately based on the auto-collimation principle; a method of eliminating stereo ambiguity in cases where two tracks completely traverse a chamber without taking a third view. In general, use of spark chambers in these experiments corresponds to a sampling of particie trajectories in contrast to applications where an entire event is recorded as continuous tracks. (A.G.W.)