Difference between revisions 2373487 and 2373490 on enwikiversity

[[Image:Detectors summary 3.png|thumb|right|250px|This tree diagram shows the relationship between types and classification of most common particle detectors. Credit: [[commons:User:Wdcf|Wdcf]].]]
'''Radiation detectors''' provide a signal that is converted to an electric current. The device is designed so that the current provided is proportional to the characteristics of the incident radiation.

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Coloradoite, a member of the coordination subclass of tellurides, is a covalent compound that is isostructural with sphalerite (ZnS).<ref name=Povarennykh>Povarennykh, A. S (1972). ''Crystal Chemical classification of minerals''. Vol I, pp. 120–121</ref>

The chemical formula for coloradoite is HgTe. Theoretically the composition (%) of HgTe is Hg 61.14, Te 38.86;<ref name=Vlasov
740-741>Vlasov, K. A. (1966) ''Geochemistry and Mineralogy of rare Elements and Genetic Types of Their Deposits''. Volume II ''Mineralogy of Rare Elements''. Israel Program for Scientific Translation. pp. 740–741</ref> The table 1 shows results from a chemical analyses  <reported by f name=Vlasov/> on samples collected from two different locations. Because it is found with other telluride ores, it carries some other metals like gold and silver.<ref>Wallace, J. P. (1908) ''A study of Ore Deposits for the Practical Miner with descriptions of Ore Minerals''.</ref> In its pure form, it has the composition mentioned above. A little hard to identify, petzite which is hazardous could be mistaken for coloradoite, on the other hand, petzite is anisotropic as opposed to coloradoite being an isotropic mineral.<ref name=Ramdohr>Ramdohr, P. (1980) ''The Ore minerals and their intergrowths''. Second edition. Volume II, Pergamon Press. p. 524. {{ISBN|0080238017}}.</ref> It is a binary compound with the general formula AX.

{| class="wikitable"
|-
!colspan="6"| '''Results of chemical analyses of coloradoite (%)'''<ref name=Vlasov740-741/>
|-
| colspan="1"|Components
|colspan="2"| Kalgoorlie, Western Australia
| Lakeshore, Ontario
|-
| Hg
| 60.95
(contracted; show full)d Nichols, Monte C. (1990) [http://rruff.geo.arizona.edu/doclib/hom/coloradoite.pdf "Coloradoite"] in ''Handbook of Mineralogy''. Volume I: Elements, Sulfides, Sulfosalts. Mineral Data Publishing. Tucson, Arizona. p. 105. {{ISBN|0962209708}}.</ref> It is a covalent compound with a high proportion of metallic bonding, due to its low valencies and even lower interatomic distances . It is also isotropic, meaning it has just one refractive index.<ref name=Povarennykh/>
⏎
⏎
Common Impurities: Pb.<ref name=Mindat>[http://www.mindat.org/min-1110.html Coloradoite]. Mindat.org</ref>

HgTe bonds are weak leading to low hardness values: 2.7×10<sup>7</sup> kg/m<sup>2</sup>.<ref name=Brice>Brice, J. and Capper, P. (eds.) (1987) ''Properties of mercury cadmium telluride'', EMIS datareview, INSPEC, IEE, London, UK.</ref><ref name=Capper>Capper, P. (ed.) (1994) ''Properties of Narrow-Gap Cadmium-Based Compounds''. INSPEC, IEE, London, UK. {{ISBN|0-85296-880-9}}</ref><ref name=Boctor>{{cite journal|title=Mercury selenide stoichiometry and phase relations in the mercury-selenium system|journal=Journal of Solid State Chemistry|volume=62|issue=2|pages=177|doi=10.1016/0022-4596(86)90229-X|year=1986|last1=Boctor|first1=N.Z.|last2=Kullerud|first2=G.|bibcode=1986JSSCh..62..177B}}</ref>

HgTe is naturally p-type due to mercury vacancies. P-type doping is also achieved by introducing zinc, copper, silver, or gold.<ref name=Brice/><ref name=Capper/>

Mercury-telluride quantum well shows a unique new state of matter—the "topological insulator": while the bulk is an insulator, current can be carried by electronic states confined close to the sample edges, unlike the quantum hall effect, here no magnetic field is required to create this unique behavior.<ref name=Konig/>

Oppositely directed edge states carry opposite spin projections.<ref name=Konig>{{Cite journal| doi = 10.1126/science.1148047 | volume = 318 | issue = 5851 | pages = 766–770 | pmid = 17885096 | title = Quantum Spin Hall Insulator State in HgTe Quantum Wells | journal = Science | date = 2007 |arxiv = 0710.0582 |bibcode = 2007Sci...318..766K | last1 = König | first1 = M | last2 = Wiedmann | first2 = S | last3 = Brüne | first3 = C | last4 = Roth | first4 = A | last5 = Buhmann | first5 = H | last6 = Molenkamp | first6 = L. W. | last7 = Qi | first7 = X. L. | last8 = Zhang | first8 = S. C. }}</ref>
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==Gadolinium oxysulfides==

Gadolinium oxysulfide ({{chem|Gd|2|O|2|S}}: Pr, Ce, F powder complex) based ceramics exhibit final densities of 99.7% to 99.99% of the theoretical density (7.32&nbsp;g/cm<sup>3</sup>) and an average grain size ranging from 5 micrometers to 50 micrometers in dependence with the fabrication procedure.<ref>Rossner, W., M. Ostertag, and F. Jermann. "Properties and Applications of Gadolinium Oxysulfide Based Ceramic Scintillators." Electroch(contracted; show full)<!-- footer templates -->
{{tlx|Radiation astronomy resources}}{{Principles of radiation astronomy}}{{Sisterlinks|Radiation detectors}}

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