Television measuring projector for bubble chamber photographs

Abstract

An instrument employing closed-circuit television for the measurement of coordinates and bubble density of charged particle tracks in bubble chamber photographs is described. The instrument uses a Moiré fringe image plane digitizer. With the aid of servo-motors, a vidicon camera can be moved in the X and Y directions and can also be rotated. Once set on the proper track by the operator, the vidicon follows the track in a staggered motion. At each stop, the machine automatically punches out onto IBM cards the X and Y coordinates of the center of the track and also the total length of the gaps and the number of gaps in the segment. The least count in the image plane is 10 μm. Ionization measurement reproducibility checks gave a standard deviation of ±3%. In an actual experiment, the rms deviation of the measured ionization from that calculated from the kinematics was less than ±14%, and the measuring rate was 4 events/h.