Intercomparison of Dose Equivalent Meters Based on Microdosimetric Techniques

Different prototypes of dose equivalent meter for area monitoring, which have been developed on the basis of tissue-equivalent proportional counters by several groups in Europe during the past several years, were intercompared in various reference neutron and photon fields of the PTB in Braunschweig. The instruments are able simultaneously to measure ambient dose equivalent due to neutrons and photons and to determine a mean quality factor of the radiation. The energy dependence of the response to neutrons was investigated for neutron energies between 73 keV and 5 MeV. While the responses of the systems generally decrease with decreasing neutron energy, significant differences are also observed. These differences can be attributed to variations in the detector wall thicknesses and the simulated cavity diameters. The results are further discussed with respect to the detector calibration procedures used and the uncertainty of measurements caused by statistical fluctuations of the count rates and the lineal energy distributions.