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05.05.2014 Julius Eckhard 1
Cherenkov radiation
Spent fuel pool HESS telescopesfr-online.de mpg.de
05.05.2014 Julius Eckhard 2
Contents
Historical events Creation
Spectrum Applications
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Introduction
● Cherenkov effect:
– Radiation appears, when fast charged particles fly through a medium
– ED analogy to the supersonic flight in Hydrodynamics
Wikipedia
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Historical events
● First experimentally discovered and described in 1934 by Pavel Cherenkov and his supervisor Sergei Wawilow
● Theoretical descripition by Ilja Frank and Igor Tamm in 1937
● All historical papers unfortunately in russian
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Historical events
Nobel prize in 1958 for Tamm, Cherenkov and Frank „for the discovery and interpretation of the Cherenkov effect.“
sm.evg-rumjantsev.ru
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Creation
● Charged particles cross a medium
Important quantities:● Particle velocity β● Index of refraction n2=ε
r
● Phase velocity of light cn=n-1
● Cherenkov radiation can only be observed at
β > cn
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Creation
● Every charged particle polarizes the medium● Excited medium radiates spherical waves
Relaxation of the elementary waves and no wavefront
Elementary waves build up to form a wavefront
β < cn
β > cn
Left:
Right:
hep.uni-freiburg.de
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Creation
Cherenkov angle θC:
lhc-facts.ch
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Spectrum
Frank-Tamm formula
# of Cherenkov photonscharge of the particlepermeabilityCherenkov angle
N:q:μ:θ
c:
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Index of refraction n
● Optical material property● Describes phase velocity of light● Frequency dependent (dispersion)● For high frequencies (x-ray): n<1
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Spectrum
Final Cherenkov spectrum:
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Applications
● Gamma-ray astronomy
– First programs in 1989– HESS Project (Namibia)– γ-rays create charged
secondary particles– Cherenkov-light is
detected
thphys.uni-heidelberg.de
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Applications
● Neutrino research
– Same idea as before– ν react with water/ice and produce muons– IceCube in Antarctica uses 1 km3 of ice– Kamiokande in Japan with 50.000 t water
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Applications
● Spent fuel pools
– Spent nuclear fuel is stored in water pools– Characteristic blue shining due to Cherenkov– Intensity proportional to nuclear decay
spentfuelpool.com
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Sources
● Bolotovskii, Frenkel: „I. Tamm Selected Papers“
– Tamm, Frank:
„Coherent Visible Radiation of fast Electrons Passing Through Matter“
● Landau, Lifschitz: Elektrodynamik der Kontinua● Jackson: Klassische Elektrodynamik● Wikipedia.org
Thank you for your attention!
