Estimate of the proper scanning speed for a container inspector consisting of an rpc gamma-ray counter

Many customs inspection machines based on particle detector techniques have been researched and developed. An inspector with a proper scanning speed of an inspector will provide better efficiency. This report attempted to optimize the scanning parameters for container inspectors with segmented detectors for gamma rays from radioactive isotopes for custom inspections executed on higher-density objects hidden in imported iron containers. This calculation method provided good results for segmented detectors such as a resistive plate chamber (RPC), segmented photomultiplier tube (PMT), cathode stripe chamber (CSC), pixelized semiconductor detectors, etc. We estimate the proper scanning speed for the best combinations of the intensity of the gamma ray, the distance between the detector and the gamma ray source, the size of a pixel in the detector, the scanning speed, etc. to get a sufficient resolution. We used an RPC, whose pixel size is a few cm² and whose gamma-ray detection efficiency is 0.18, as a reference detector for our calculation. Also we used ⁶⁰Co emitting two kinds of gamma rays with kinetic energies of 1.17 MeV and 1.33 MeV, as a gamma ray source.