Range of charged particles (E. Segrè, Nuclei and particles)
Alpha-particles in air (discovery of the proton)
(E. Segrè, Die großen Physiker...)
Bragg curves (E. Segrè, Nuclei and particles)
Range of charged particles(aus: C. Grupen, Teilchendetektoren)
Muons in rock: Electrons in various materials:
Bethe – Bloch formula:
Energy loss of charged particles due to ionisation
Energy loss of various charged particles in air
(C. Grupen, Teilchendetektoren)
Energy loss of minimum ionising particles
-1 -1 2
min min
-3
Absorber MeVcm MeVg cm( )
Water 2.03 2.03
Xenon (gaseous) 7.3 10
dE dEdx d x
1.24Iron 11.7 1.48Lead 12.8 1.13
Hy -4drogen (gaseous) 3.7 10 4.12
Contributions to the energy loss of muons in iron (C. Grupen, Teilchendetektoren)
Multiple scattering of electrons(W.R. Leo, Techniques...)
Beam broadening:
Backscattering:
Books on particle detection:
G. Knoll: Radiation detection (Addison Wesley)
W.R. Leo: Techniques for nuclear and particle physics experiments, a how-to approach(Springer)
C. Grupen: Teilchendetektoren (B.I. Wissenschaftsverlag)
Cherenkov - Effect
Cherenkov-radiators
Material 1 -min -min
solid Sodium 3.22 0.24 1.029Diamond 2.91 0.26
n
1.034Flintglas 0.92 0.52 1.17Water 0.33 0.75 1.52Aerogel 0.025
-3
-4
- 0.075 0.93 - 0.976 4.5 - 2.7
Pentane 1.7 10 0.9983 17.2
Air 2.93 10 0.9997 41.1
Helium
5 3.3 10 0.99997 123
RICH1Ring Imaging Cherenkov
•80 m3 (3 m C4F10)•116 VUV mirrors (3.3 m focal length)
•5.3 m2 VUV detectors– MWPC CsI photon-
sensitive cathodes– 8x8 mm2 pads
•84k channels of analog read-out
m irro rwa ll
p ho to nd e te c to rts
b e a m
3.3 m
5.3 m
6 .6 m
RICH-1 an event froman event fromon-line on-line displaydisplay
VUV mirror VUV mirror wall, 21 mwall, 21 m22,,116 mirrors116 mirrors
Photon detectors Photon detectors (PD) : (PD) : MWPCs with MWPCs with CsI photocathodesCsI photocathodes (5.3 m(5.3 m22), ), 84,000 84,000 analog read-out ch.sanalog read-out ch.s
2 hadrons
Hadron reconstruction without and with
RICH
Decay: N K+ K-
one or two Kaons identified in RICH
both Kaons identified in RICH
Kaon identification efficiency from N-decay~35%
4. Particle interaction with condensed matter, particle
detection
4.1 Charged particles4.1.1 Basic terms4.1.2 Bethe-Bloch formula4.1.3 Cherenkov effect
4.2 Photons4.3 Neutrons4.4 Some practical devices
Photons in lead (C. Grupen, Teilchendetektoren)
Neutrons
Energy range named Detection
100 MeV high energy neutrons particle reactions100 keV - 10 MeV fast neutrons nE
nuclear recoil0.1 eV - 100 keV epithermal neutrons moderation nuclear reactions
= 25 meV thermal neutrons nuclear reactions< 25meV nE
cold neutrons nuclear reactions< 250 neV ultra-cold neutrons nuclear reactions
Ionisation chamber(Grupen, Teilchendetektoren)
1 electron – ion pair per w 30eV
: 2.35 , 0.2FwEnergy resolution R FE
Yield of ions in a gas detector(Leo, Techniques...)
Multiwire chamber (Charpak) position sensitivity(Grupen, Teilchendetektoren)
Gas Electron Multiplier foils
(Sauli 1995)
50 m
(two dimensional)
2 dimensional read-out
Organic Scintillator(Leo, Techniques...)
Very rapid fluorescence signal (a few ns) timingProduction of light requires 100 eV per photon (NaI: 25 eV)
< 10 ps
ns
Scintillator – light guide – photomultiplier(Leo, Techniques...)
Measurement of time-of-flight(Grupen, Teilchendetektoren)
e.g. also as a veto detector
Photomultiplier tube(Grupen, Teilchendetektoren)
Quantum efficiency of the photocathode: 10 – 30 %Amplification: up to 107
Multichannel plate (Application: light amplifiers)(Leo, Techniques...)
Channel width: 10 – 100 mAmplification: 103 – 104 per plate
Energy resolution NaI-Scintillator – Germanium (Leo, Techniques...)
NaI: 8% (25 eV per photon)Ge: 0.15% (3 eV per photon)
Bubble chamber (Glaser 1952)
- liquid at 5 – 20 atmospheres- bubbles form along the path of ionisation at relaxation – take photo- magnetic field for deviation of charged particles
Hadronic Cascade(Grupen, Teilchendetektoren)