Characterization of Radiophotoluminescence Dosimeters Under X-Ray Irradiation at High Doses

A characterization of radiophotoluminescence (RPL) dosimeters at high doses of X-ray radiation for applications in high-radiation areas is presented. Commercial FD-7 silver-doped phosphate glasses (
$1.5\times 8.5$
mm) in use at CERN for passive dosimetry are irradiated using commercial X-ray tubes. A 1.5-mm-thick aluminum filter is used to harden the X-ray spectrum and improve dose homogeneity. Two irradiation campaigns are presented, targeting doses ranging from about 1.3 kGy to 0.46 MGy and dose rates from about 0.6 to 6.3 kGy/h, respectively. Monte Carlo (MC) simulations performed with PHITS allowed the determination of a factor to convert the dose to water, into the average absorbed dose to RPL material. The found conversion factor is validated by the achieved measurements. The results evidence a satisfactory agreement between the absorbed doses delivered with X-rays and the readout results, based on Co-60 gamma calibration.