Properties of Wide‐Gap Spark Chambers

The operation of spark chambers with gaps of up to 40 cm has been studied. By applying electric fields of the order of 10 kV/cm particle spark tracks suitable for accurate curvature measurements have been obtained. The uniformity of the electric field represents a very important factor in determining the limit of accuracy of curvature measurements. By comparing two 40‐cm chambers located in a magnetic field against each other, it is found that the momentum of a 1‐BeV/c cosmic ray can be measured to an accuracy of ±1.4% with one 40‐cm chamber located in a 13.3‐kG magnetic field. Sensitive times of 5 μsec are typical.