Aluminum oxide is a crystalline material used for which of these radiation-monitoring devices?

• A. Thermoluminescent Dosimeter (TLD)
• B. Scintillation detector
• C. Semiconductor detector
• D. Optically Stimulated Luminescent Dosimeter (OSL)

Answer: (D)

Optically stimulated luminescence relies on a crystalline material that can trap energy from ionizing radiation and then release it as light when stimulated by a light source. Aluminum oxide crystals (Al2O3), often doped to enhance sensitivity (Al2O3:C), have the right trap structure and strong luminescent response, so after irradiation they store energy and emit light when blue light is shone on them. The emitted light is proportional to the absorbed dose, which is why this material is used in optically stimulated luminescent dosimeters. Other devices rely on different mechanisms or materials—thermoluminescent dosimeters use heat to release stored energy, scintillation detectors emit light directly under irradiation, and semiconductor detectors measure charge in a solid-state sensor—so aluminum oxide is the specific fit for the OSL approach.