1. G. Sullivan – Quarknet, July 2003 Calorimeters in Particle Physics What do they do? –Measure the ENERGY of particles Electromagnetic Energy –Electrons, positrons, photons Hadronic Energy –Charged pions, protons –Particle ID Distinguish between different particles –Sometimes in combination with tracking etc… Why? –Measure particles coming out of Interaction Reconstruct what happened –Remember the first lab on Monday & particle search

2. G. Sullivan – Quarknet, July 2003 Calorimeters versus Tracking Tracking makes precision measurement of position of CHARGED particle trajectory –Reconstruct displaced vertex Particle ID like in b-quark tagging –Measure momentum & charge in combination with magnetic field Radius of curvature Calorimeters measure amount of electromagnetic and hadronic ENERGY –Measure of E,P are complimentary e.g. No track.AND. EM energy  photon

3. G. Sullivan – Quarknet, July 2003 The life of a particle in a detector e    Tracking precisionnormalParticle ID Calorimeters electromagnetichadronic Muon Tracking vertexmomentumIDem energyh energyMuon ID,p

4. G. Sullivan – Quarknet, July 2003 Calorimeters are after tracking Tracking measures particles as the traverse the medium (e.g. gas, thin silicon) without “disturbing” the particle. Calorimeters “destroy” (i.e.stop) the particle to measure their energy - some exceptions are neutrinos and muons.

5. G. Sullivan – Quarknet, July 2003

7. Real top-quark event

8. G. Sullivan – Quarknet, July 2003 Electromagnetic Calorimeter

9. G. Sullivan – Quarknet, July 2003

10. Electromagnetic Shower

11. G. Sullivan – Quarknet, July 2003 Longitudinal Profile

12. G. Sullivan – Quarknet, July 2003 How to build a good em calorimeter Large number X 0 with small chance of hadron interacting –Want to stop em particles NOT hadrons small “radiation length” (X 0 ) Large “interaction length” ( h ) –Want to get good sampling of particles in shower to get good statistical sampling of energy. Stacked plates of High z absorber (e.g. Pb, U, Fe) and detectors (e.g. scintillator, Liquid Argon) Certain crystals (e.g. Pb, CsI)

13. G. Sullivan – Quarknet, July 2003 Examples

14. G. Sullivan – Quarknet, July 2003

18. Energy Resolution

19. G. Sullivan – Quarknet, July 2003 Energy Resolution

20. G. Sullivan – Quarknet, July 2003

21. Reconstruct particles  0  

22. G. Sullivan – Quarknet, July 2003 Reconstructed Z Boson Mass

23. G. Sullivan – Quarknet, July 2003 Reconstruct the event