Arthur Roberts

Development of the Spark Chamber: A Review

A survey of the development of the spark chamber from the spark counter is given. An effort has been made to clarify the early history of the device. Some unpublished recent Russian work on spark chambers is summarized. A consistent terminology for the various times relevant to spark chamber operation is suggested.

Use of Spark Chambers in Magnetic Fields

The use of parallel-plate spark chambers for obtaining tracks of particles throughout the entire plane normal to - the magnetic field is discussed. For example, a 50-gap spark chamber in a 13-kgauss field observed the tracks of particles at all angles with the plates. The chamber operates in a combined track-sampling and track-delineating mode; a series of streamers delineates the path of a particle moving parallel to the plates, or nearly so. Illustrations are given showing slow electrons and delta rays produced in soft showers. An efficiency per gap of about 95% (if only a single track is present) is obtained by flowing through the chambers a gas mixture of 30% helium and 70% argon by volume, where about 1% of the mixture is bubbled through ethyl alcohol. (N.W.R.)

Some Problems in High-Energy Particle Detection and Analysis

1. The kinematic analysis of high-energy events requires, in general, particle momentum measurements with an absolute error of ±50-100 MeV/c, independent of momentum. Corresponding errors are 0.05% at 100 GeV/c, less at higher momenta. To minimize the cost of magnetic deflection of high-energy particles, improvements in angular precision, hence, in particle location accuracy, are desirable. The present analysis indicates that improving location accuracy from ±1/3 mm to ±0.1 mm is both desirable and feasible. The usefulness of still higher precision must await data on detailed systems performance. 2. For complex events, it appears likely that vidicon digitization can compete favorably in cost, convenience, and flexibility with large wire-array systems. 3. Neutral particle detectors that furnish accurate data on the location and direction of neutral particles (gamma rays, neutral hadrons) are likely to be important.