The spectrum measurement technology of low energy photon for calibrating dosemeters and doserate meters

For calibrating dosemeters and doserate meters in the low energy X reference radiation field, the conversion coefficients from air kerma to dose equivalen have a strong dependence on the factors like the energy distribution and the incidence angle. Use the conversion coefficients given in IS04037 X and Gamma Reference Radiation for Calibrating Dosemeters and Doserate Meters and for Determining their Response as a Function of Photon Energy directly can produce a large uncertainty. Measuring the spectra is helpful for knowing about energy and fluence spectra, so a more exact conversion coefficient can be calculated from the spectra if necessary. In the paper, the basic principle and method of the spectrum measurement technology will be described. A soft X-ray ionization chamber of PTW was used for the test of characteristics data of the reference radiation field, the CdZnTe detectors was used for the spectra measurment, and the Monte Carlo method will be used for he unfolding of the pulse height spectrum. The largest deviation between the conversion coefficients calculated from the unfolding spectra results and the values given by PTB laboratory and the ISO standard Calibration of Area and Personal Dosemeters and Dosemeters and the Measurement of their Response as a Function of Photon Energy and Angle of Incidence are 8.9% and 18.2%. (authors)