CVD Diamond Applications as TL Radiation Dosimeters
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CVD Diamond Applications as TL Radiation Dosimeters M Barboza-Flores1, R Melendrez1, V Chernov1, M. Pedroza-Montero1, S Gastelum1, and E CruzZaragoza2 1 DIFUS, Universidad de Sonora, P. O. Box 5-088, Hermosillo, Sonora, México, 83190, Mexico 2 Instituto de Ciencias Nucleares, Universidad Autonoma de Mexico, A. P. 70-543, Mexico, DF, 04510, Mexico ABSTRACT The extraordinary characteristics of chemically vapor deposited (CVD) diamond such as tissue equivalence, radiation hardness, and lack of solubility in water; makes CVD diamond a very promising material for radiation dosimetry applications. Recent investigations have shown that CVD techniques allowed the growing of good quality diamond films in a diversity of substrates to be used in the form of ionization chambers, thermoluminescence (TL) detectors and dosimeters. In the present work, we report on the TL properties of MWCVD diamond exposed to gamma radiation in the 0.05 -10.0 kGy dose range and 43.5 and 81.11 Gy min−1 dose rates. The CVD diamond displays a linear dose behavior and 5% TL cycle reproducibility, without requiring any annealing or thermal treatment before using it as TL dosimeter. In spite of the significant results, some problems remain and a lot of research work is necessary to improve the synthetic material characteristics to optimize the TL radiation dosimeter properties.
INTRODUCTION Diamond is a wide band semiconductor with well-known optical and electronic properties. It is the hardest known material, chemically inert, wear resistant, electrically insulating and optically transparent in the UV and far infrared region. Material scientists consider it as a unique material because its broad range of applications as an engineering material. Many potential applications have been hampered by the scarcity of good quality natural diamond. However, the possibility of growing high quality polycrystalline synthetic diamond by chemically vapor deposition (CVD)
techniques has increased the interest and inspired novel applications like field emission displays, electrochemical sensors, particle and radiation detectors and dosimeters. On the other hand, the remarkable properties of CVD diamond as tissue equivalence, chemical stability, non-toxicity makes it suitable for application as passive thermoluminescent dosimeter (TLD). This is of outstanding importance in medical applications as in radiotherapy, which requires high-energetic photon and ions beams. In the last years a significant amount of data dealing with the TL performance of CVD diamond was obtained [1-11]. It is noticeable that any CVD diamond specimen examined showed quite distinctive TL properties and dose behavior, depending on the type of CVD reactor, deposition substrates, precursor gas composition, and the growth parameters. All these factors may produce defects and impurities concentration on the deposited diamond affecting the structure and morphology of the deposited diamond and its TL dosimetry performance. Recently, Krása et al. (2007), investigated the TL properties of h
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