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The LHCb Electromagnetic Calorimeter

The LHCb Electromagnetic Calorimeter. Ivan Belyaev, ITEP/Moscow. 45 institutes 14 countries. LHCb LHC is supposed to be the most prolific source of beauty hadrons s b = 500 m b ( s in =80 mb) The dedicated forward spectrometer at modest L 10 12 b-pairs / 10 7 s

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The LHCb Electromagnetic Calorimeter

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  1. The LHCb Electromagnetic Calorimeter Ivan Belyaev, ITEP/Moscow

  2. 45 institutes 14 countries Ivan Belyaev ITEP/Moscow "The LHCb Ecal"

  3. LHCb LHC is supposed to be the most prolific source of beauty hadrons sb = 500 mb (sin=80 mb) The dedicated forward spectrometer at modest L 1012 b-pairs / 107s Flexible trigger efficient for both leptonic and hadronic final states Particle ID Forward spectrometer ~10-300 mrad acceptance LHCb Experiment Ivan Belyaev ITEP/Moscow "The LHCb Ecal"

  4. LHCb Ecal Et of electrons for L0 B->J/yKS, enX, … Et of photons for L0 B->K*g Reconstruction of p0s and gs offline g/p0 and e/h separation LHCb Ecal • Overall dimensions • 6.3 m x 7.8 m • Transverse granularity • Varies with a function of occupancy • Radiation resistance • Readout within 1 BX (25ns) • 40 MHz electronics • Fast optical components • Resolution • 10% stochastic • 1.5 % constant Ivan Belyaev ITEP/Moscow "The LHCb Ecal"

  5. LHCb Ecal 3.3k modules 5.5k channels 3312 modules 3312 modules 3312 modules Total weight 0.1k tons Ivan Belyaev ITEP/Moscow "The LHCb Ecal"

  6. Shashlyk technology 66 layers: • 4 mm scintillator tile • 2 mm Pb absorber Length: 25 X0 Weight of one module ~28 kg Ivan Belyaev ITEP/Moscow "The LHCb Ecal"

  7. 3 types of modules Outer 2.7/2.7 k Middle 0.4/1.8 k Inner 0.2/1.5 k Ivan Belyaev ITEP/Moscow "The LHCb Ecal"

  8. For fixed cell size and volume ratio the constant term in energy resolution is determined by transverse and longitudinal non-uniformity of modules Transverse non-uniformity: light reflection efficiency from tile edge (global uniformity) position+density of fibres relative to ionising particle (local and global uniformity) Reduced fiber density Improve global uniformity Decrease the fiber bundle diameter Reduce the overall cost Decrease the light yield Decrease local uniformity The tile edge mating Increase the light yield Improve uniformity Non-uniformity of response Ivan Belyaev ITEP/Moscow "The LHCb Ecal"

  9. Tile edge mating Scan over the scintillator tile with radiative source Black: l.y. 128 Clean: l.y. 188 Aluminized:l.y. 342 Mated: l.y. 393 Ivan Belyaev ITEP/Moscow "The LHCb Ecal"

  10. Optimisation results: Outer module: 64 fibers Inner and Middle modules: 144 fiber Fiber density optimization Test beam: 50 GeV e Corrected for global non-uniformity Ivan Belyaev ITEP/Moscow "The LHCb Ecal"

  11. m-beam 100 GeV/c electron beam Transverse uniformity Ivan Belyaev ITEP/Moscow "The LHCb Ecal"

  12. Chemical DMA treatment of scintillator tile edges (mating) The light yield spread 1.7% for tiles with mated edges Scintillator tiles Light yield of tiles 1.7% 1.5% mated Non-mated Ivan Belyaev ITEP/Moscow "The LHCb Ecal"

  13. WLS fibers Kuraray Y11 fibers Multi-clad Decay time ~7ns 1.2 mm diameter Radiation resistant Fiber-to-fiber light yield spread: 1.7% Fiber loops Loop-to-loop light yield spread: 1.6% Loop “efficiency” > 94% Fibers Relative light yield of fibers Loop “efficiency” LY with loop LY w/o loop Ivan Belyaev ITEP/Moscow "The LHCb Ecal"

  14. Test beam: ~ 9% stochastic term ~ 1% constant term Monte Carlo for B-> p+p-p0 sp = 5.7 MeV/c2 sB = 35 MeV/c2 Energy Resolution MC Ivan Belyaev ITEP/Moscow "The LHCb Ecal"

  15. Expected dose: 2.5 Mrad/ 10 year (innermost modules at shower max) All components are tested up to 5Mrad Radiation hardness Tile Fiber inner module: 0.25 Mrad/y max sDEG/E (%) versus doze Ivan Belyaev ITEP/Moscow "The LHCb Ecal"

  16. 3.3k modules to be produced 120 tested on e/m beams Production rate 10 modules/day Conclusion: Modules in production 10 modules/day Light yield of modules (cosmic) Module-to-module spread <5% Ivan Belyaev ITEP/Moscow "The LHCb Ecal"

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