Ultraviolet response of CaSO4:Dy

Area of Science:

• Materials Science
• Radiation Detection
• Dosimetry

Background:

• Thermoluminescence (TL) offers a sensitive method for radiation detection.
• Calcium sulfate doped with dysprosium (CaSO4:Dy) is a known dosimeter for gamma radiation.
• Accurate measurement of ultraviolet (UV) exposure is crucial in various applications.

Purpose of the Study:

• To develop and characterize a simple method for measuring ultraviolet exposure using CaSO4:Dy.
• To evaluate the suitability of specific thermoluminescent peaks for UV dosimetry.
• To determine the dosimetric characteristics of CaSO4:Dy for UV radiation.

Main Methods:

• Irradiation of virgin CaSO4:Dy phosphor with ultraviolet radiation.
• Analysis of thermoluminescent glow curves to identify and select dosimetric peaks.
• Calibration of the phosphor using a standard quartz pen-ray lamp.
• Investigation of linearity, supralinearity, photon energy dependence, and fading characteristics.

Main Results:

• Three TL peaks were observed at 145°C, 215°C, and 365°C upon UV irradiation.
• The 215°C peak showed minimal fading and was chosen for UV dosimetry.
• A linear response was observed from 400 erg mm⁻² to 4 x 10⁴ erg mm⁻², with supralinearity at higher exposures.
• TL sensitivity demonstrated a strong dependence on photon energy, increasing significantly below 250 nm.

Conclusions:

• CaSO4:Dy phosphor is a viable material for measuring ultraviolet exposure.
• The 215°C thermoluminescent peak provides a reliable dosimetric signal for UV radiation.
• The method exhibits good linearity and sensitivity across a range of UV exposures.