Investigation on the energy dependence of various types of survey meter in gamma and X-ray field

Kamwang, N.*; Kowatari, Munehiko; Yoshitomi, Hiroshi   

For proper implementation of the radiation monitoring, radiation monitoring instruments require to be ensured whether their characteristics meet the criteria for radiological protection uses. This is because the energy response to incident photons varies with energies, which is called "energy dependence". In this study, we focused on the energy dependence for hand-held type survey meters with wide energy range from 45 keV up to 7 MeV. The ionization chamber (IC) type, the geiger-mueller counter (GM) type and the plastic scintillation (PS) type survey meters were engaged. A series of measurement was performed with the narrow series X-ray field, radionuclides gamma-ray fields and the high energy gamma ray field by the 4 MV Van-de-Graaff accelerator. The results show that IC and PS type survey meters have almost uniform energy dependence with the whole energy range between 45 to 6,600 keV. On the other hand, the response of GM type survey meter was deviated to the unity, the responds seems reliable only at the energy between 250 and 1,250 keV.