1. 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

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 will then get the Fermi relation for dE/dX with the density effect. If | 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

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

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

5. cos(  ) = 1/  n m = p/   m/m = [(  p/p) 2 + (  2  tg  ) 2 ] ½ 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

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 :

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

8. The Cherenkov radiator Q  The particle The light cone

9. http://banzai.msi.umn.edu/leonardo/

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?!?

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°

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

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

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  <1 no real photon can be emitted for an infinite long radiator. Due to diffraction broadening, sub-threshold emission of real photons in thin radiators.  0 2 =plasma frequency 2  (electron density) If  

15. If  p2 >  p1 then  max   -1 Total radiated power S  10 -2  (eV)  which is a small number All this for a small number?

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.

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