CALCULATION OF SPECTRUM TO DOSE CONVERSION FACTORS FOR A HPGE SPECTROMETER

Spectrum to dose conversion factors for a HPGe spectrometer were calcu lated by use of a response matrix constructed by combining the respons e functions for gamma-ray energies up to 3 MeV. The response functions of the HPGe spectrometer were obtained by performing simulations with our own Monte Carlo code developed for photon and electron transport. The calculated conversion factors, namely, conversion of a spectrum t o an exposure, a spectrum to an air kerma, and a spectrum to a dose eq uivalent, were applied to evaluate the dose from the terrestrial gamma -ray spectra obtained by means of in-situ RPGe spectrometry. The evalu ated exposure rates were compared with those measured by a pressurized ion chamber. The air kerma and dose equivalent rates were also compar ed with the values obtained by other existing methods. It was confirme d that, in dose assessment of the low-level photon field from the gamm a-ray spectra measured using a RPGe spectrometer, the calculated conve rsion factors give us an accuracy comparable to or better than those g iven by the pressurized ion chamber.