Panoramic radiation detector having a multiplicity of isolated gas chambers

1,218,124. Ionization detectors. BAIRDATOMIC Inc. 9 Aug., 1968, No. 38272/68. Heading H1D. [Also in Division G1] A detector for investigating the radiation emanating from various points in an area comprises a planar array of a multiplicity of ionisation chambers which have electrically conducting walls, accommodate insulated pins, include an ionizable gas and are interconnected by ports for gas pressure equalization, the pins being connected to a matrix and a source of potential so that a chamber-pin discharge occurring due to incident radiation may be Indicated. The chamber may be formed from two sheets one having a multiplicity of blind holes or from three sheets comprising a coverplate of aluminium or a metallized plastic, a metal honeycomb, and an insulating plate carrying pins in registry with the centres of the honeycomb apertures. The gas may be static and under pressure, or circulating and the pulses developed during a discharge may be applied through graded " row " and "column " resistors and amplifiers to position the spot of a cathode-ray tube which may be photographed to integrate the coincident spots. The pulses may be counted in a magnetic store memory and the arrangement may include means for preventing interference between successive pulses. Specific reference is made to the use of the apparatus for examining a chromatographic paper containing dispersed concentrations of radioactivity associated with small sites of " tagged " chemical materials. The honeycomb may be of lead, aluminium, copper, brass or stainless steel and dimensions are exemplified.