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Particle Detectors for Colliders Calorimeters

Particle Detectors for Colliders Calorimeters. Robert S. Orr University of Toronto. Generic Detector. Layers of Detector Systems around Collision Point. R.S. Orr 2009 TRIUMF Summer Institute. Scintillators. charged particle. photons. atom molecule lattice.

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Particle Detectors for Colliders Calorimeters

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  1. Particle Detectors for CollidersCalorimeters Robert S. Orr University of Toronto

  2. Generic Detector • Layers of Detector Systems around Collision Point R.S. Orr 2009 TRIUMF Summer Institute

  3. Scintillators charged particle photons • atom • molecule • lattice • Charged particle passing through matter distorts • Relaxation of distortion – light emitted Successive excitation & emission – different λphotons • Emitted photon may – excite another molecule eachstep whole chain • Very fast – good timing resolution

  4. Can be extremely efficient ~ 100 photoelectrons per cm. • Spatial resolution ~ size of scintillator ~10s cm Scintillating fibres R.S. Orr 2009 TRIUMF Summer Institute

  5. Why are scintillators transparent to emitted light? • Stokes shift R.S. Orr 2009 TRIUMF Summer Institute

  6. Wavelength Shifting R.S. Orr 2009 TRIUMF Summer Institute

  7. Photomultiplier number of stages • Fast • Low noise • High gain R.S. Orr 2009 TRIUMF Summer Institute

  8. PM Sensitivity R.S. Orr 2009 TRIUMF Summer Institute

  9. Modern Photodetectors • Micro-channel plates • Multi-anode pm • Hybrid pm • Visible light photon counters R.S. Orr 2009 TRIUMF Summer Institute

  10. Electromagnetic Showers Number of particles after Average energy At the critical energy assume this is max depth incident Converts to 2 electrons shower grows as ln E linear energy measurement Each electrons will have emitted a brems photon of energy resolution improves with energy Now have 4 particles energy R.S. Orr 2009 TRIUMF Summer Institute

  11. Monte Carlo Simulation of an EM Shower Calc Put b=0.5 Get a from R.S. Orr 2009 TRIUMF Summer Institute

  12. “b” is sort of material independent R.S. Orr 2009 TRIUMF Summer Institute

  13. Transverse Shower Profile • Shower Broadens as it develops • Pair • Brems • Compton • Multiple Coulomb • Shower Broadens as it develops • dense central core • spreading with depth • Moliére Radius • Like radiation length, Moliére radius scales for different materials • In terms of Moliére radius, shower width is roughly independent of material - 90% of energy in R.S. Orr 2009 TRIUMF Summer Institute

  14. Comparison of Hadronic & Electromagnetic Showers R.S. Orr 2009 TRIUMF Summer Institute

  15. Hadronic Calorimeters • Strong (nuclear) interaction cascade • Similar to EM shower hadronic interaction length • Energy Resolution • shower fluctuations • leakage of energy hadronic calorimeter nearly always sampling calorimeters • invisible energy loss mechanisms • Shower length R.S. Orr 2009 TRIUMF Summer Institute

  16. Sampling Calorimeter R.S. Orr 2009 TRIUMF Summer Institute

  17. Hadronic Lateral Shower Profile • Hadronic shower much broader than EM Fe • Mean hadronic versus MCS Fe R.S. Orr 2009 TRIUMF Summer Institute

  18. Hadronic Shower Longitudinal Development ZEUS Uranium/Scint R.S. Orr 2009 TRIUMF Summer Institute

  19. Lateral Scaling with Material 90% containment does not scale core scales R.S. Orr 2009 TRIUMF Summer Institute

  20. Calorimeter Energy Resolution sampling and shower fluctuations energy number of samples energy deposited in a sampling step stochastic term R.S. Orr 2009 TRIUMF Summer Institute

  21. Calorimeter Energy Resolution e.g. # of photo-electrons in PM, ion pairs in liquid argon counting statics in sensor system mean # of photo-electrons in PM per unit of incident energy this term is usually negligible shower leakage fluctuations – make calorimeter as deep as $$ allow R.S. Orr 2009 TRIUMF Summer Institute

  22. Calorimeter Energy Resolution • important for low level signal • liquid argon electronics • detector capacitance noise - detector or electronics N channels with some intrinsic noise noise (energy) deposited energy behaviour increases with number of channels summed over R.S. Orr 2009 TRIUMF Summer Institute

  23. Calorimeter Energy Resolution • constant in E inter - calibration uncertainty of channels • fractional channel to channel gain uncertainty • spatial in-homogeneity of detector energy response • dead space • temperature variation • radiation damage • all these influence spatial variation of effective energy response constant R.S. Orr 2009 TRIUMF Summer Institute

  24. Calorimeter non-uniformity R.S. Orr 2009 TRIUMF Summer Institute

  25. Generic Detector • Layers of Detector Systems around Collision Point R.S. Orr 2009 TRIUMF Summer Institute

  26. Semi-empirical model of hadron shower development hadronic part electromagnetic part radiation length interaction length - significant amount of material in front of calorimeter (magnet coil etc.) R.S. Orr 2009 TRIUMF Summer Institute

  27. More Rules of Thumb for the Hobbyist • Mixtures in sampling calorimeters • Shower maximum active + passive material • 95% Longitudinal containment • 95% Lateral containment R.S. Orr 2009 TRIUMF Summer Institute

  28. Typical Calorimeter Resolutions • Homogeneous EM (crystal, glass) CLEO, Crystal Ball, Belle, CMS..... • Sampling EM (Pb/Scint, Pb/LAr) CDF, ZEUS, ALEPH, ATLAS..... • Non-compensating HAD (Fe/Scint, Fe/LAr) CDF,ATLAS,H1, LEP = everyone • Compensating HAD (DU/Scint) ZEUS, HELIOS R.S. Orr 2009 TRIUMF Summer Institute

  29. Invisible Energy in Hadronic Showers R.S. Orr 2009 TRIUMF Summer Institute

  30. Difference in Response to Electrons and Hadrons R.S. Orr 2009 TRIUMF Summer Institute

  31. Effect of e/h on Energy Resolution Resolution tail Fe/Scint DU/Scint R.S. Orr 2009 TRIUMF Summer Institute

  32. Effect of e/h on Linearity Fe/Scint DU/Scint R.S. Orr 2009 TRIUMF Summer Institute

  33. R.S. Orr 2009 TRIUMF Summer Institute

  34. Weighting to Correct for e/h Energy resolution does not improve Weight down EM part of shower tune R.S. Orr 2009 TRIUMF Summer Institute

  35. Jet Energy Resolution Jet-jet Mass Resolution Fluctuations between EM and Hadronic component in jets will degrade the energy resolution for jets Effects other than e/h dominate the 2-jet mass resoluton R.S. Orr 2009 TRIUMF Summer Institute

  36. Jet-Jet Mass Resolutions R.S. Orr 2009 TRIUMF Summer Institute

  37. Conceptual Readout Schemes R.S. Orr 2009 TRIUMF Summer Institute

  38. ZEUS Forward Calorimeter R.S. Orr 2009 TRIUMF Summer Institute

  39. R.S. Orr 2009 TRIUMF Summer Institute

  40. Generic Detector • Layers of Detector Systems around Collision Point R.S. Orr 2009 TRIUMF Summer Institute

  41. LArCalorimetry • Five different detector technologies • Calorimetry coverage to SM Higgs Discovery Potential EM Calorimeter Hadronic & Forward Calorimeters EM Calorimeter WW Fusion Tag jets in Forward Cal

  42. LAr Calorimeter Technology Overview • Design Goals Technology • EM Calorimeters ( ) and Presampler ( ) • Hadronic Endcap ( ) • Forward Calorimeter ( ) Lead/Copper-Kapton/Liquid Argon Accordion Structure Copper/Copper-Kapton/Liquid Argon Plate Structure Tungsten/Copper/Liquid Argon Paraxial RodStructure

  43. LAr and Tile Calorimeters Tile barrel Tile extended barrel LAr hadronic end-cap (HEC) LAr EM end-cap (EMEC) LAr EM barrel LAr forward calorimeter (FCAL)

  44. Electromagnetic Barrel Barrel Module Schematic with presampler Half Barrel Assembly • 2x16 modules • I.R/O.R 1470/2000 mm • 22 - 33 • 3 longitudinal samples • presampler • 64 gaps /module • 2.1 mm gap • 2x3100 mm long R.S. Orr 2009 TRIUMF Summer Institute

  45. Electromagnetic Endcap • 2x8 modules • Diam. 4000 mm • 22 - 37 • 3 longitudinal samples • Front sampling of 6 • for ,  - strips. • 96 gaps /module outer wheel • 32 gaps/module inner wheel • 2.8 - 0.9 mm gap outer • 3.1-1.8 mm inner R.S. Orr 2009 TRIUMF Summer Institute

  46. AccordionStructure Pb Absorber • Honeycomb spacer • & • Cu/Kapton electrode R.S. Orr 2009 TRIUMF Summer Institute

  47. Prototype of EM endcap Detail of Kaptons R.S. Orr 2009 TRIUMF Summer Institute

  48. ATLAS FCAL R.S. Orr 2009 TRIUMF Summer Institute

  49. Pictures of assembly process

  50. LAr Forward Calorimeters • FCAL C assembly into tube – Fall 2003

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