CHARACTERISTICS OF A 85Kr BETA-PARTICLE SOURCE APPLIED IN SERIES 1 REFERENCE IRRADIATIONS OF TMDIS-1 DIRECT ION STORAGE DOSEMETERS

Characteristics necessary to specify an ISO 6980 Series 1 reference radiation field were determined for a commercially available 85 Kr beta-particle source, using a BEAM EGS4 Monte Carlo code. The characteristics include residual maximum beta energy, E res , and the uniformity of the dose rate over the calibration area. The E res and the uniformity were also determined experimentally, using an extrapolation ionization chamber (EC) and a 0.2 cm 3 parallel plate ionization chamber, respectively. The depth-dose curve measured with the EC gave a value 0.62 MeV for the E res . Series 2 90 Sr + 90 Y and Series 1 85 Kr beta-particle sources calibrated for H p (0.07) at the secondary standard dosimetry laboratory (SSDL) of STUK were used to determine the energy and angular responses of TM DIS-1 direct ion storage dosemeters. The averaged zero angle H p (0.07) responses to the 90 Sr + 90 Y and 85 Kr reference radiations were 135 and 80%, respectively. The responses were normalized to 100%, H p (0.07) response to 137 Cs photon radiation.