The LHCb Electromagnetic Calorimeter Ivan Belyaev, ITEP/Moscow

5 March'2k+2 Ivan Belyaev ITEP/Moscow "The LHCb Ecal" 2 45 institutes 14 countries

5 March'2k+2 Ivan Belyaev ITEP/Moscow "The LHCb Ecal" 3 LHCb Experiment LHCb LHCb LHC is supposed to be the most prolific source of beauty hadrons LHC is supposed to be the most prolific source of beauty hadrons  b = 500  b (  in =80 mb) The dedicated forward spectrometer at modest L The dedicated forward spectrometer at modest L b-pairs / 10 7 s Flexible trigger efficient for both leptonic and hadronic final states Flexible trigger efficient for both leptonic and hadronic final states Particle ID Particle ID Forward spectrometer Forward spectrometer ~ mrad acceptance ~ mrad acceptance

5 March'2k+2 Ivan Belyaev ITEP/Moscow "The LHCb Ecal" 4 LHCb Ecal Et of electrons for L0 Et of electrons for L0 B->J/  K S, e X, … Et of photons for L0 Et of photons for L0 B->K *  Reconstruction of  0 s and  s offline Reconstruction of  0 s and  s offline  /  0 and e/h separation  /  0 and e/h separation Overall dimensions Overall dimensions 6.3 m x 7.8 m 6.3 m x 7.8 m Transverse granularity Transverse granularity Varies with a function of occupancy Varies with a function of occupancy Radiation resistance Radiation resistance Readout within 1 BX (25ns) Readout within 1 BX (25ns) 40 MHz electronics 40 MHz electronics Fast optical components Fast optical components Resolution Resolution 10% stochastic 10% stochastic 1.5 % constant 1.5 % constant

5 March'2k+2 Ivan Belyaev ITEP/Moscow "The LHCb Ecal" 5 LHCb Ecal Total weight 0.1k tons 3312 modules 3.3k modules 5.5k channels

5 March'2k+2 Ivan Belyaev ITEP/Moscow "The LHCb Ecal" 6 Shashlyk technology Length: 25 X 0 Weight of one module ~28 kg 66 layers: 4 mm scintillator tile 2 mm Pb absorber

5 March'2k+2 Ivan Belyaev ITEP/Moscow "The LHCb Ecal" 7 3 types of modules Outer 2.7/2.7 k Inner 0.2/1.5 k Middle 0.4/1.8 k

5 March'2k+2 Ivan Belyaev ITEP/Moscow "The LHCb Ecal" 8 Non-uniformity of response For fixed cell size and volume ratio the constant term in energy resolution is determined by transverse and longitudinal non-uniformity of modules 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 Improve global uniformity Decrease the fiber bundle diameter Decrease the fiber bundle diameter Reduce the overall cost Reduce the overall cost Decrease the light yield Decrease the light yield Decrease local uniformity Decrease local uniformity The tile edge mating Increase the light yield Increase the light yield Improve uniformity Improve uniformity

5 March'2k+2 Ivan Belyaev ITEP/Moscow "The LHCb Ecal" 9 Tile edge mating Black: l.y. 128 Mated: l.y. 393 Aluminized:l.y. 342 Clean: l.y. 188 Scan over the scintillator tile with radiative source

5 March'2k+2 Ivan Belyaev ITEP/Moscow "The LHCb Ecal" 10 Fiber density optimization Optimisation results: Outer module: 64 fibers Inner and Middle modules: 144 fiber Test beam: 50 GeV e Corrected for global non-uniformity

5 March'2k+2 Ivan Belyaev ITEP/Moscow "The LHCb Ecal" 11 Transverse uniformity  -beam  -beam 100 GeV/c electron beam 100 GeV/c electron beam

5 March'2k+2 Ivan Belyaev ITEP/Moscow "The LHCb Ecal" 12 Scintillator tiles Chemical DMA treatment of scintillator tile edges (mating) The light yield spread The light yield spread 1.7% for tiles with mated edges Light yield of tiles 1.5% 1.7% mated Non-mated

5 March'2k+2 Ivan Belyaev ITEP/Moscow "The LHCb Ecal" 13 Fibers WLS fibers Kuraray Y11 fibers Kuraray Y11 fibers Multi-clad Multi-clad Decay time ~7ns Decay time ~7ns 1.2 mm diameter 1.2 mm diameter Radiation resistant Radiation resistant Fiber-to-fiber light yield spread: 1.7% Fiber-to-fiber light yield spread: 1.7% Fiber loops Fiber loops Loop-to-loop light yield spread: 1.6% Loop-to-loop light yield spread: 1.6% Loop “efficiency” > 94% Loop “efficiency” > 94% Relative light yield of fibers Loop “efficiency” LY with loop LY w/o loop

5 March'2k+2 Ivan Belyaev ITEP/Moscow "The LHCb Ecal" 14 Energy Resolution Test beam: ~ 9% stochastic term ~ 9% stochastic term ~ 1% constant term ~ 1% constant term Monte Carlo for B->  +  -  0 Monte Carlo for B->  +  -  0   = 5.7 MeV/c2   = 5.7 MeV/c2  B = 35 MeV/c2  B = 35 MeV/c2 MC

5 March'2k+2 Ivan Belyaev ITEP/Moscow "The LHCb Ecal" 15 Radiation hardness Expected dose: 2.5 Mrad/ 10 year (innermost modules at shower max) Expected dose: 2.5 Mrad/ 10 year (innermost modules at shower max) All components are tested up to 5Mrad All components are tested up to 5Mrad inner module: 0.25 Mrad/y max TileFiber  DEG /E (%) versus doze

5 March'2k+2 Ivan Belyaev ITEP/Moscow "The LHCb Ecal" 16 Conclusion: Modules in production 3.3k modules to be produced 3.3k modules to be produced 120 tested on e/  beams 120 tested on e/  beams Production rate Production rate 10 modules/day 10 modules/day Light yield of modules (cosmic) Module-to-module spread <5% 10 modules/day