Cadmium tungstate (CdWO4 or CWO), the cadmiumsalt of tungstic acid, is a dense, chemically inert solid which is used as a scintillation crystal to detect gamma rays. It has density of 7.9 g/cm3 and melting point of 1325 °C. It is toxic if inhaled or swallowed. Its crystals are transparent, colorless, with slight yellow tint. It is odorless. Its CAS number is 7790-85-4. It is not hygroscopic.
The crystal is transparent and emits light when it is hit by gamma rays and x-rays, making it useful as a detector of ionizing radiation. Its peak scintillation wavelength is 480 nm (with emission range between 380-660 nm),[2] and efficiency of 13000 photons/MeV. It has a relatively high light yield, its light output is about 40% of NaI(Tl), but the time of scintillation is quite long (12−15 μs).[2] It is often used in computed tomography. Combining the scintillator crystal with externally applied piece of boron carbide allows[citation needed] construction of compact detectors of gamma rays and neutron radiation.
Cadmium tungstate was used as a replacement of calcium tungstate in some fluoroscopes since the 1940s.[3][4] Very high radiopurity allows use of this scintillator as a detector of rare nuclear processes (double beta decay, other rare alpha and beta decays) in low-background applications.[5] For example, the first indication of the natural alpha activity of tungsten (alpha decay of 180W) had been found in 2003 with CWO detectors.[6] Due to different time of light emission for different types of ionizing particles, the alpha-beta discrimination technique has been developed for CWO scintillators.[7]
Cadmium tungstate films can be deposited by sol-gel technology. Cadmium tungstate nanorods can be synthesized by a hydrothermal process.[8]
^Kroeger, F. A. (1948). Some Aspects of the Luminescence of Solids. Elsevier.
^Bardelli L.; et al. (2006). "Further study of CdWO4 crystal scintillators as detectors for high sensitivity 2β experiments: Scintillation properties and pulse-shape discrimination". Nucl. Instrum. Methods Phys. Res. A. 569 (3): 743–753. arXiv:nucl-ex/0608004. doi:10.1016/j.nima.2006.09.094. S2CID 7311888.
^Danevich F. A.; et al. (2003). "α activity of natural tungsten isotopes". Phys. Rev. C. 67 (1): 014310. arXiv:nucl-ex/0211013. doi:10.1103/PhysRevC.67.014310. S2CID 6733875.
^Fazzini T.; et al. (1998). "Pulse-shape discrimination with CdWO4 crystal scintillators". Nucl. Instrum. Methods Phys. Res. A. 410 (2): 213–219. doi:10.1016/S0168-9002(98)00179-X.
^Wang Y, Ma J, Tao J, Zhu X, Zhou J, Zhao Z, Xie L, Tian H (September 2006). "Hydrothermal synthesis and characterization of CdWO4 nanorods". Journal of the American Ceramic Society. 89 (9): 2980–2982. doi:10.1111/j.1551-2916.2006.01171.x.
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Scintillator materials
January 20, 2023
cadmium, tungstate, cdwo4, cadmium, salt, tungstic, acid, dense, chemically, inert, solid, which, used, scintillation, crystal, detect, gamma, rays, density, melting, point, 1325, toxic, inhaled, swallowed, crystals, transparent, colorless, with, slight, yello. Cadmium tungstate CdWO4 or CWO the cadmium salt of tungstic acid is a dense chemically inert solid which is used as a scintillation crystal to detect gamma rays It has density of 7 9 g cm3 and melting point of 1325 C It is toxic if inhaled or swallowed Its crystals are transparent colorless with slight yellow tint It is odorless Its CAS number is 7790 85 4 It is not hygroscopic Cadmium tungstate NamesIUPAC name Cadmium II tungstateIdentifiersCAS Number 7790 85 4 Y3D model JSmol Interactive imageChemSpider 10636623ECHA InfoCard 100 029 297EC Number 232 226 2PubChem CID 3080645UNII ZNL5ZHP0Q7InChI InChI 1S Cd 4O W q 2 2 1 Key OUMLAYUZCYYIOD UHFFFAOYSA NSMILES O W O O O Cd 2 PropertiesChemical formula CdWO4Molar mass 360 25 g mol 1Appearance colorless crystals with a yellow tintDensity 7 9 g cm3 solidMelting point 1 325 C 2 417 F 1 598 K Solubility in water 0 04642 g 100 mL 20 C HazardsGHS labelling PictogramsSignal word WarningHazard statements H302 H312 H332 H410Precautionary statements P261 P264 P270 P271 P273 P280 P301 P312 P302 P352 P304 P312 P304 P340 P312 P322 P330 P363 P391 P501NIOSH US health exposure limits PEL Permissible 1910 1027 TWA 0 005 mg m3 as Cd 1 REL Recommended Ca 1 IDLH Immediate danger Ca 9 mg m3 as Cd 1 Except where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa Y verify what is Y N Infobox references The crystal is transparent and emits light when it is hit by gamma rays and x rays making it useful as a detector of ionizing radiation Its peak scintillation wavelength is 480 nm with emission range between 380 660 nm 2 and efficiency of 13000 photons MeV It has a relatively high light yield its light output is about 40 of NaI Tl but the time of scintillation is quite long 12 15 ms 2 It is often used in computed tomography Combining the scintillator crystal with externally applied piece of boron carbide allows citation needed construction of compact detectors of gamma rays and neutron radiation Cadmium tungstate was used as a replacement of calcium tungstate in some fluoroscopes since the 1940s 3 4 Very high radiopurity allows use of this scintillator as a detector of rare nuclear processes double beta decay other rare alpha and beta decays in low background applications 5 For example the first indication of the natural alpha activity of tungsten alpha decay of 180W had been found in 2003 with CWO detectors 6 Due to different time of light emission for different types of ionizing particles the alpha beta discrimination technique has been developed for CWO scintillators 7 Cadmium tungstate films can be deposited by sol gel technology Cadmium tungstate nanorods can be synthesized by a hydrothermal process 8 Similar materials are calcium tungstate scheelite and zinc tungstate It is toxic as are all cadmium compounds References Edit a b c NIOSH Pocket Guide to Chemical Hazards 0087 National Institute for Occupational Safety and Health NIOSH a b Burachas S F et al 1996 Large volume CdWO4 crystal scintillators Nucl Instrum Methods Phys Res A 369 1 164 168 doi 10 1016 0168 9002 95 00675 3 Patterson Hand Held Fluoroscope ca 1940s Oak Ridge Associated Universities 2021 Retrieved 2021 10 12 Kroeger F A 1948 Some Aspects of the Luminescence of Solids Elsevier Bardelli L et al 2006 Further study of CdWO4 crystal scintillators as detectors for high sensitivity 2b experiments Scintillation properties and pulse shape discrimination Nucl Instrum Methods Phys Res A 569 3 743 753 arXiv nucl ex 0608004 doi 10 1016 j nima 2006 09 094 S2CID 7311888 Danevich F A et al 2003 a activity of natural tungsten isotopes Phys Rev C 67 1 014310 arXiv nucl ex 0211013 doi 10 1103 PhysRevC 67 014310 S2CID 6733875 Fazzini T et al 1998 Pulse shape discrimination with CdWO4 crystal scintillators Nucl Instrum Methods Phys Res A 410 2 213 219 doi 10 1016 S0168 9002 98 00179 X Wang Y Ma J Tao J Zhu X Zhou J Zhao Z Xie L Tian H September 2006 Hydrothermal synthesis and characterization of CdWO4 nanorods Journal of the American Ceramic Society 89 9 2980 2982 doi 10 1111 j 1551 2916 2006 01171 x External links EditScintillator materials Retrieved from https en wikipedia org w index php title Cadmium tungstate amp oldid 1049552126, wikipedia, wiki, book, books, library,
