Later versions used gaps of up to forty centimeters and gathered additional data with audio transducers.  
This instrument is the basis for the "pair telescope" used on Cosmic Ray Satellite B and the Energetic Gamma Ray Experiment.  It produces an image based on the activity of the thyratron circuit, which activates based on the signal sent through the discriminator and coincidence circuit by the photomultiplier tube.  Later versions used gaps of up to forty centimeters and gathered additional data with audio transducers.  FTP, name this type of detector consisting of several parallel plates of metal within an inert gas, which responds to an electric field by discharging energy along a particle's track.
This instrument is the basis for the "pair telescope" used on Cosmic Ray Satellite B and the Energetic Gamma Ray Experiment.  
spark chamber