Difference between revisions 2373220 and 2373246 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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Similar to the way that a terrestrial gyrocompass uses a pendulum to sense local gravity and force its gyro into alignment with earth's spin vector, and therefore point north, an ''orbital gyrocompass'' uses a horizon sensor to sense the direction to earth's center, and a gyro to sense rotation about an axis normal to the orbit plane. Thus, the horizon sensor provides pitch and roll measurements, and the gyro provides yaw. See Tait-Bryan angles.

==Detector materials==


==Gadolinium oxysulfide is a promising luminescent host material, because of its high density (7.32 g/cm<sup>3</sup>) and high effective atomic number of Gd. These characteristics lead to a high stopping power for X-ray radiation.s==

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." Electrochemical Society Prceeedings, 98, 187-94.</ref> There are two main disadvantages to this scintillator; one being the hexagonal crystal structure, which emits only optical translucency and low external light collection at the photodiode and the other is the high X-ray damage to the sample.<ref name= Greskovich >{{cite journal|doi=10.1146/annurev.matsci.27.1.69|title=Ceramic Scintillators|date=1997|last1=Greskovich|first1=C.|last2=Duclos|first2=S.|journal=Annual Review of Materials Science|volume=27|pages=69–88|bibcode=1997AnRMS..27...69G }}</ref>

The {{chem|Gd|2|O|2|S}} structure is a sulfur layer with double layers of gadolinium and oxygen in between.<ref name=Rossner>Rossner, W., M. Ostertag, and F. Jermann. "Properties and Applications of Gadolinium Oxysulfide Based Ceramic Scintillators." Electrochemical Society Prceeedings, 98, 187-94.</ref>

Terbium-activated gadolinium oxysulfide is frequently used as a scintillator for x-ray imaging that emits wavelengths between 382-622&nbsp;nm, though the primary emission peak is at 545&nbsp;nm and is used as a green phosphor in projection cathode ray tubes, though its drawback is marked lowering of efficiency at higher temperatures.<ref>[http://www.freepatentsonline.com/5115306.html]</ref>

When Gadolinium oxysulfide comes in contact with mineral acids, hydrogen sulfide can be produced.<ref>Gadolinium Oxysulfide; MSDS [online]; R.H. Mangels: Hackettstown, NJ, March 15, 1997. http://www.nonius.nl/manualspdf/msdsGadolinumOxysulfide.pdf (accessed October 17, 2011)</ref>

==Cadmium tellurides==

Cadmium telluride (CdTe) doped with chlorine is used as a radiation detector for [X-rays], gamma rays, beta particles and alpha particles. CdTe can operate at room temperature allowing the construction of compact detectors for a wide variety of applications in nuclear spectroscopy.<ref name="Capper">{{cite book
|title= Properties of Narrow-Gap Cadmium-Based Compounds
| author = P. Capper
| publisher = INSPEC, IEE
| location= London, UK
| date = 1994
| {{isbn=|0-85296-880-9}} }}</ref> The properties that make CdTe superior for the realization of high performance gamma- and x-ray detectors are high atomic number, large bandgap and high electron mobility ~1100&nbsp;cm<sup>2</sup>/V·s, which result in high intrinsic μτ (mobility-lifetime) product and therefore high degree of charge collection and excellent spectral resolution.

==Entities==
{{main|Radiation astronomy/Entities}}
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{{tlx|Radiation astronomy resources}}{{Principles of radiation astronomy}}{{Sisterlinks|Radiation detectors}}

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