View source for Detection of internally reflected Cherenkov light

{{No footnotes|date=August 2010}}

In [[particle detector]]s a '''detection of internally reflected Cherenkov light''' (DIRC) detector measures the [[velocity]] of [[charged particle]]s and is used for [[particle identification]]. It is a design of a [[ring imaging Cherenkov detector]] where [[Cherenkov radiation|Cherenkov light]] that is contained by [[total internal reflection]] inside the solid radiator has its angular information preserved until it reaches the light sensors at the detector perimeter.

[[File:DIRC Schema01 2009-08-13.svg|thumb|right|The Cherenkov light is following a zigzag path between parallel surfaces. The light detectors would be positioned to the right.]]

A charged particle travelling through a material (for instance [[Fused quartz|fused silica]]) with a speed greater than c/n (n  [[refractive index]], c [[speed of light|vacuum speed of light]]) emits Cherenkov radiation. If the light angle on the surface is sufficiently shallow, this radiation is contained inside and transmitted through internal reflections to an expansion volume, coupled to [[photomultiplier]]s (or other types of photon detectors), to measure the angle. Preserving the angle requires a precise planar and rectangular cross section of the radiator. Knowledge of the angle at which the radiation was produced, combined with the track angle and the particle's momentum (measured in a tracking detector like a [[drift chamber]]) may be used to calculate the particle's mass.

A DIRC was first proposed by [[Blair Ratcliff]] as a tool for particle identification at a [[B-Factory]], and the design was first used by the [[BaBar experiment|BaBar]] collaboration at [[SLAC]]. Since the successful operation in the BaBar experiment next-generation DIRC-type detectors have been designed for several new particle physics experiments, including [[Belle II Detector|Belle-II]], [[PANDA experiment|PANDA]], and [[GlueX]]. The DIRC differs from earlier [[ring-imaging Cherenkov detector|RICH]] and [[CRID (detector)|CRID]] Cherenkov light detectors in that the quartz bars used as radiators also transmit the light.  
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provided that <math>n \beta > 1</math> (where ''n'' is the [[index of refraction]] in the quartz 
and <math>\beta = v/c</math> is the particle's velocity measured in c)
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== See also ==
* [http://www.slac.stanford.edu/BFROOT/www/Detector/DIRC/PID.html BaBar DIRC homepage] {{Webarchive|url=https://web.archive.org/web/20060827224527/http://www.slac.stanford.edu/BFROOT/www/Detector/DIRC/PID.html |date=2006-08-27 }}
*{{cite journal
 |year=2003
 |title=Imaging rings in Ring Imaging Cherenkov counters
 |journal=[[Nuclear Instruments and Methods in Physics Research A]]
 |volume=502 |issue=1
 |pages=211–221
 |doi=10.1016/S0168-9002(03)00276-6
 |last1=Ratcliff
 |first1=B
|bibcode = 2003NIMPA.502..211R |osti=808694
 |url=https://www.slac.stanford.edu/cgi-bin/getdoc/slac-pub-9508.pdf
 }}
* {{cite journal|author1= C Lu |author2=  D Marlow |author3=  C Mindas |year=1996|title= Detection of internally reflected Cherenkov light, results from the BELLE DIRC prototype |journal= Proceedings of the Second International Workshop on Ring Imaging Cherenkov Detectors | volume=371|issue=  1–2 |pages= 82–86 |doi=10.1016/0168-9002(95)01256-7|bibcode = 1996NIMPA.371...82L }}
* {{cite journal|author1= P. Coyle |author2=  H. Kawahara |author3=  A. Lu |year=1994 |title= The DIRC counter: a new type of particle identification device for B factories | volume=343|issue=  1 |pages= 292–299|doi=10.1016/0168-9002(94)90568-1|bibcode = 1994NIMPA.343..292C |journal=Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment|citeseerx=  10.1.1.382.2452 }}
* {{cite journal| author1= H. Salazar|author2=  E. Moreno |author3=  T. Murrieta |s2cid= 54665079 |title= Detection of Cherenkov Photons with Multi-Anode Photomultipliers|doi=10.1063/1.2359247|journal=AIP Conference Proceedings|volume=  857 |pages=  113–120 |year=  2006 |bibcode= 2006AIPC..857..113S }}

{{DEFAULTSORT:Detection Of Internally Reflected Cherenkov Light}}
[[Category:Particle detectors]]