Cherenkov Radiation (and other shocking waves). Perhaps also
the ones of the fish?
http://www.newscientist.com/lastword/answers/lwa674bubbles.html
http://www.pbs.org/wgbh/nova/barrier/ Shock Waves May Confuse Birds
Internal Compass
Slide 2
The density effect in the energy loss is intimately connected
to the coherent response of a medium to the passage of a
relativistic particle that causes the emission of Cherenkov
radiation. Calculate the electromagnetic energy flow in a cylinder
of radius a around the track of the particle. Define If a is in the
order of atomic dimension and | a|1, we get ( after some steps ):
If has a positive real part the integrand will vanish rapidly at
large distances all energy is deposited near the track If is purely
imaginary the integrand is independent of a some energy escapes at
infinite as radiation Cherenkov radiation and or and a subscript 1
: along particle velocity 2, 3 : perpendicular to we assume real as
from now on
Slide 3
Let us consider a particle that interacts with the medium The
behavior of a photon in a medium is described by the dispersion
relation Conservation of energy and momentum W.W.M. Allison and
P.R.S. Wright RD/606-2000-January 1984 Argon at normal density
Slide 4
2 eV345 A particle with velocity v/c in a medium with
refractive index nn=n( ) may emit light along a conical wave front.
The angle of emission is given by and the number of photons by
Slide 5
cos( ) = 1/ n m = p/ m/m = [( p/p) 2 + ( 2 tg ) 2 ] set : n1.28
(C 6 F 14 ) p/p 2 5 10 -4 15 mrad L 1 cm 1/ 1 -1/ 2 = 1/2200 -
1/1800 ( in A) with Q=20% p K max = 38.6 o min =.78
Slide 6
Threshold Cherenkov Counter Flat mirror Photon detector
Particle with charge q velocity Spherical mirror Cherenkov gas To
get a better particle identification, use more than one radiator. A
radiator : n=1.0024 B radiator : n=1.0003 Positive particle
identification :
Slide 7
Directional Isochronous Selfcollimating Cherenkov (DISC)
Cherenkov radiator n=f(photon energy) r=f( n) (r)=f(resolution)
More general for an Imaging Detector Transformation Function 200nm
150 N photons N=f( ) (n-1)*10 6
Slide 8
The Cherenkov radiator Q The particle The light cone
Slide 9
http://banzai.msi.umn.edu/leonardo/
Slide 10
Cherenkov media Focusing Mirror Detector e-e+ E Proportional
Chamber Quartz Plate Photon to Electron conversion gap e e e Hey!
Did I mention TMAE to you?! Did I?!?
Slide 11
Particle Identification in DELPHI at LEP I and LEP II 2
radiators + 1 photodetector n = 1.28 C 6 F 14 liquid n = 1.0018 C 5
F 12 gas /K /K/p K/p /h /K/p K/p 0.7 p 45 GeV/c 15 165
Slide 12
Particle Identification with the DELPHI RICHes Liquid RICH Gas
RICH p (GeV) Cherenkov angle (mrad) From data p from K from D *
from K o http://delphiwww.cern.ch/delfigs/export/pubdet4.html
DELPHI, NIM A: 378(1996)57
Slide 13
Yoko Ono 1994 FRANKLIN SUMMER SERIES, ID#27 I forbindelse med
utstillingen i BERGEN KUNSTMUSEUM, 1999 ABB.com More beautiful
pictures (which has next to nothing to do with) Cherenkov
radiation
Slide 14
An exact calculation of Transition Radiation is complicated J.
D. Jackson ( bless him ) and he continues: A charged particle in
uniform motion in a straight line in free space does not radiate A
charged particle moving with constant velocity can radiate if it is
in a material medium and is moving with a velocity greater than the
phase velocity of light in that medium (Cherenkov radiation) There
is another type of radiation, transition radiation, that is emitted
when a charged particle passes suddenly from one medium to another.
If
If p2 > p1 then max -1 Total radiated power S 10 -2 (eV)
which is a small number All this for a small number?
Slide 16
Coherent addition in point P (-1) k : The field amplitude for
successive interfaces alternate in sign A( k ) : Amplitude k =
(R/c-t) : phase factor = 2 10 4 l 1 = 25 m l 2 = 0.2 mm
polypropylene - air Egorytchev, V ; Saveliev, V V ;Monte Carlo
simulation of transition radiation and electron identification for
HERA-B ITEP-99-11. - Moscow : ITEP, 17 May 1999. Periodic radiator
for Transition Radiation.
Slide 17
Production with multi foils Absorption in foils Conversion
t=0t=T Pulse Height -electron MIP X radiation Threshold 10 keV M.L.
Cerry et al., Phys. Rev. 10(1974)3594 + saturation effect due to
multi layer