A CCD-based gamma-ray dosimeter

This paper investigates the use of charged coupled devices (CCDs) for perso nal gamma -ray dosimetry. Personal dosimeters require high sensitivity to t he photon energies likely to be encountered and a sensitivity response acro ss a wide dose rate range, particularly at low dose rates. The principal ad vantages of CCDs for this application are two-fold: sensitivity at low dose rates due to low-noise operation and a wide dynamic range. Preliminary exp erimental measurements have been performed on a standard buried channel CCD using a range of isotope sources. One half of the sensor was coated with a 100 mum thick layer of caesium iodide. It is proposed that the differing p roperties of the two halves of the sensor increases its range for personal dosimetry. Deposition of scintillator coatings of various thicknesses acros s the surface of the sensor should provide sensitivity to a wide energy ran ge. The results demonstrated that the device has potential for this application . A linear dose rate response was observed over the dose rate range 0.08-35 mu Sv h(-1). It was found that the uncoated side of the sensor demonstrate d better response at low dose rates and a better energy response. Whereas t he scintillator coated side would improve the detection efficiency at energ ies beyond 60keV. (C) 2001 Elsevier Science B.V. All rights reserved.