Spectrometry of pulsed photon radiation

The energy distribution (spectrum) of pulsed photon radiation can hardly be measured using active devices, therefore, a thermoluminescence detector (TLD)-based few channel spectrometer is used in combination with a Bayesian data analysis to help resolve this problem. The spectrometer consists of 30 TLD layers interspaced by absorbers made of plastics and metals with increasing atomic numbers and thickness. Thus, the main idea behind the device is the deeper the radiation penetrates - the higher the radiation’s energy when the radiation impinges perpendicular to the front of the spectrometer. From the doses measured in the TLD layers and from further prior available information, the photon spectrum is deduced using a Bayesian data analysis leading to absolute spectra and doses including their uncertainties and coverage intervals. This spectrometer was successfully used in two different scenarios, i.e., for the spectrometry of the radiation field two different industrial type open beam pulsed X ray generators and secondly in three different radiation fields of a medical accelerator.

Dose Reassessment by Using PTTL Method in Ge-Doped SiO2 Optical Fiber Thermoluminescence Dosimetry

In this paper we report, the characteristics of PTTL after irradiation with 60Co gamma rays as a function UV light exposure wavelength, gamma irradiation dose, and UV light exposure time were determined for Ge-doped SiO2 optical fibers. The efficiency of dose reassessment for this fiber was compared to standard thermoluminescence detector, TLD100. Experiments show that the method works well with the UV lamp of 254 nm within region of doses between 3 to 50 Gy, but could be applied for higher and lower doses as well. The effect of exposure time of UV radiation on the PTTL signal was studied from 5 to 120 minutes to determine the highest sensitivity and the limit of the dose. The efficiency of dose reassessment with 10 Gy of gamma irradiation expose to UV light for 15 minutes relative to PTTL values of about 27.0% and 2.3% for Ge-doped SiO2 optical fiber and TLD100.