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Calorimeters/Calorimetry in Particle and Nuclear Physics

Roman Pöschl LAL Orsay

ILC School on Calorimetry Beijing/China April 2009

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Curriculum of the Lecture

1) General Introduction on Calorimeters

2) Interactions of Electrons

3) Interactions of Photons

4) Electromagnetic Showers

5) Hadronic Showers

6) Signal Generation/Response of Calorimeters

7) Readout Devices

8) Layout of Calorimeters

9) Energy, Spatial Resolution Fluctuations and all that ...

10) Calibration of Calorimeters

11) Overview of recent Calorimeters employed in experiments

Appendix A: Atom in a Radiation Field - The Photoeletric Effect

Calorimeters Chapter 1 - XVIII Heidelberger Graduiertentage

Literature used for the Lecture

R. Wigmans: CalorimetryD. Wegener: Detektoren in der Teilchenphysik - Lecture Uni Dortmund W.R. Leo: Techniques for Nuclear and Particle Phyisics ExperimentC. Grupen: TeilchendetektorenSitar et al.: Ionization measuremens in High Energy Physics+Lots of Material ‘stolen’ from presentations,articles found in theWeb.

If you find that I have used your material without a citation pleasewrite me and I will include the reference

Thanks to Hengne Li from LAL for producing several figures forthis lecture

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Chapter 1

General Introduction on Calorimeters

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Calorimetric techniques do have their origin in thermodynamics- Evaporation heat of a liquid- Specific heat of a substance- Heating of environment by radioactive substances

Heat

Fachhochschule Flensburg - Institut für Physik

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Typical Scales in Thermodynamics and (Sub-)Atomic Physics

Unit in Thermodynamics: 1 J/1 Calorie

It takes 1 Calorie (=4.18 Joule) to heat up 1g of water from 14.5 oC to 15.5 oC

Unit in (Sub-)Atomic Physics: 1 eV = 1.6 10-19 J

(Nowadays) Typical Energies in Nuclear and Particle Physics:

106 – 1012 eV = MeV - TeV

Even the highest energetic particles would deposit only

~ 10-12 J in a given quantity of Water (Need lots of water to absorb such a particle, see later)

T 0

High Energetic

Particle

Thermodynamic methods are not suited for our purposes !!!! Macroscopic observables O(1023) particles involved What else ???

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How to detect the presence of a small particle???

(Charged) Particlescreate (visible) lightwhen passing through material

Ionization (Here)Excitation (more important)

Light is emitted whenexcited atoms fall backinto ground state

Amount of light~Energy of primary particle

... and there was light!!!

Ion beam passing through air

Adapt measurement technique to microscopic size of particles to be detected Light creation is a quantum, i.e. microscopic phenomenon

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What kind of particles do we want to measure ?

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De-excitation of a Nucleus: Detect radiated photon

Nucleus A* Nucleus A Photon

High energetic collision in Particle Physics Experiment

Calorimeters

Plethora ofparticles in final state:

Subject to

a)electromagnetic interaction, e

b) strong interactioncharged neutral h

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Energy Range to be covered by Calorimetric MeasurementsNuclear Decays:

Energy range gouverned by typicalnuclear potential (e.g. Schwabl, p.299)

KeV

a-V0

V0 ~ (ma2)-1 40 MeVfor m=mproton

and a=1 fm = 5 GeV-1 r

V(r)

Probing the Proton Structure

60Co Decay Spectrumwith two prominent linesat 1.1 and 1.3 MeV

Scattered Electron inDeep Inelastic ep Reaction

Proton Radius 5 GeV-1

RQ 1

Need O(10-100) GeV for deep insight into the proton

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Energy Range to be covered by Calorimetric Measurements – cnt'd

Smashing particles – High energetic final state in Collider Experiments Energy of final state particles only limited by power of accelerator

ppat Tevatron

Several hundreds of GeV Energy depositionExpect O(TeV) at the LHC

Higgs Production in e+e- Collisionsat the ILC

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Dimensions of Calorimeters

4 'Germanium Ball' of AGATA Experiment

1m

ATLAS TileCal Barrel Calorimeter

~10m

Calorimeters are employed in 'table top' experimentsand in huge experimental apparatuus