Difference between revisions 2373246 and 2373249 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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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==

[[Image:HgCdTe Eg vs x.PNG|thumb|right|260px|Energy gap is a function of cadmium composition. Credit: [[c:user:Jaraalbe|Jaraalbe]].{{tlx|free media}}]]
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.

The intrinsic carrier concentration is given by <ref>{{cite journal|last=Schmidt|author2=Hansen|title=Calculation of intrinsic carrier concentration in HgCdTe|journal=Journal of Applied Physics|year=1983|volume=54|doi=10.1063/1.332153 }}</ref>

<math>n_{i}(t,x) = (5.585 - 3.82x + (1.753\cdot 10^{-3})t - 1.364\cdot 10^{-3}t\cdot x)\cdot 10^{14}\cdot E_{g}(t,x)^{0.75}\cdot t^{1.5} \cdot e^{\frac{-E_{g}(t,x)\cdot q}{2\cdot k\cdot t}}</math>

where ''k'' is Boltzmann's constant, ''q'' is the elementary electric charge, ''t'' is the material temperature, ''x'' is the percentage of cadmium concentration, and ''E''<sub>g</sub> is the bandgap given by <ref>{{cite journal|last=Hansen|title=Energy gap versus alloy composition and temperature in HgCdTe|journal=Journal of Applied Physics|year=1982|volume=53|doi=10.1063/1.330018 }}</ref>

{{multiple image
 | footer = Relationship between bandgap and cutoff wavelength
 | image1 = Hgcdte bandgap x t.png
 | caption1 = HgCdTe Bandgap in electron volts as a function of x composition and temperature
 | image2 = Hgcdte cutoff wavelength x t.png
 | caption2 = HgCdTe cutoff wavelength in µm as function of x composition and temperature.
}}

<math>E_{g}(t,x) = -0.302 + 1.93\cdot x+(5.35\cdot 10^{-4})\cdot t\cdot (1-2\cdot x)-0.81\cdot x^{2}+0.832\cdot x^{3}</math>

Using the relationship <math>\lambda _{p} = \frac{1.24}{E_{g}}</math>, where λ is in µm and ''E''<sub>g</sub>. is in electron volts, one can also obtain the cutoff wavelength as a function of ''x'' and ''t'':

<math>\lambda _{p} = (-0.244 + 1.556\cdot x + (4.31\cdot 10^{-4})\cdot t\cdot (1-2\cdot x) - 0.65\cdot x^{2} + 0.671\cdot x^{3})^{-1}</math>
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==Entities==
{{main|Radiation astronomy/Entities}}
'''Def.''' "the fraction of photoelectric events which end up in the photopeak of the measured energy spectrum"<ref name="Krawczynski">{{cite book
|author=Henric S. Krawczynski
|author2=Ira Jung
|author3=Jeremy S. Perkins
|author4=Arnold Burger
|author5=Michael Groza
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{{tlx|Radiation astronomy resources}}{{Principles of radiation astronomy}}{{Sisterlinks|Radiation detectors}}

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