title: A search for novel thermoluminescent radiation dosimeter media.
abstract: We describe two example pilot efforts to help define new thermoluminescent dosimeter media. The first concerns ZnS:Mn nanophosphors, prepared by chemical precipitation using zinc and sodium sulfate, doped with manganese sulfate at concentrations varying from 1 to 3mol. The second concerns chemical vapor deposited diamond, produced as a thin film or as amorphous carbon on a single-crystal silicon substrate, each deposited under the same conditions, use being made of the hot filament-chemical vapor deposition (HFCVD) technique. The gas concentrations used were 1% CH4 in 99% H2 and 25% CH4 in 75% H2. Characterization of formations used FESEM, XRD and EDX. The nanophosphors consisted of particles of sizes in the range 85-150nm, the thermoluminescence (TL)-based radiation detection medium giving rise to a single peaked glow curve of maximum yield at a temperature of 250°C at a heating rate of 5°C/s. The TL response increased linearly with radiation dose, ZnS doped to 2mol of Mn being found the most sensitive. Regarding chemical vapor deposited (CVD) carbon, inappreciable TL was found for the resultant ball-like amorphous carbon films, graphite, and the silicon substrate, whereas CVD diamond films showed a promising degree of linearity with dose. For both the ZnS and diamond samples, TL signal fading was appreciable, being some 40% per day for ZnS and>50% per day for CVD films even under storage in the dark at room temperature, making it apparent that there is need to adjust parameters such as the size of nanoparticles.
authors: Department of Physics, University of Malaya, 50603 Kuala Lumpur, Malaysia. Electronic address: yusoffmohdamin@um.edu.my.
authors: Khalid H
authors: KH
authors: Al-Hinai
authors: Nadjima
authors: N
authors: Benkara Mohd
authors: Nurul
authors: N
authors: Rozullyah Zulkepely
authors: Roslan
authors: R
authors: Md Nor
authors: Yusoff
authors: Y
authors: Mohd Amin
authors: D A
authors: DA
authors: Bradley
mesh_terms: D018130:Diamond; D005720:Gamma Rays; D006801:Humans; D008345:Manganese; D053768:Metal Nanoparticles / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D010865:Pilot Projects; D012825:Silicon; D013440:Sulfides; D013819:Thermoluminescent Dosimetry / Q000379:methods*; D014961:X-Ray Diffraction; D017967:Zinc Compounds
chemical_list: D013440:Sulfides; D017967:Zinc Compounds; D008345:Manganese; D018130:Diamond; C031238:zinc sulfide; D012825:Silicon
keywords: Diamond; Radiation detectors; Thermoluminescence dosimetry; ZnS:Mn nanophosphors