Chemistry:Lead-Tungstate Crystals (PbWO4)
Lead-Tungstate (PbWO4) crystal is a scintillator which has been used as the detector material in several high energy physics devices, such as the CMS detector [1] at CERN. The crystal is distinguished by its fast decay time, high density and strong radiation hardness. So it may have an prominent application potential in medical devices. Because of its excellent optical properties and stable physical and chemical properties,it is popularly used as a photoelectric crystal in various photonics applications.
History
PbWO4 compound was investigated as erly as 1948 [2], but it represented limited interest as luminophore due to its low light yield at room temperature. In recent years, there has been a growing interest in lead tungstate crystals as detectors for high-energy particles. In particular, significant fraction of the light produced by the crystals is the result of Cherenkov radiation, rather than electronic de-excitation.
Physical Properties
Here is the list of typical properties of PbWO4:
- Density (g.cm-3): 8.28
- Radiation length (cm): 0.92
- Decay constant (ns): 6/30
- Emission peak (nm): 440/530
- Light yield (% that of NaI:Tl): 0.5
- Melting point (°C): 1123
- refractive Index: 2.16
- Hygroscopicity: none
- Cleavage: 101
References
- ↑ P. Lecoq et al, Lead tungstate (PbWO4) scintillators for LHC EM calorimetry, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Volume 365, Issues 2–3, 11 November 1995, Pages 291-298 https://www.sciencedirect.com/science/article/pii/0168900295005897
- ↑ P.Lecoq et al, CERN-PPE/94-225 https://cds.cern.ch/record/279798/files/ppe-94-225.pdf
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