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)