Segmented-Crystal Electromagnetic Precision Calorimeter (S-CEPCal) - PowerPoint PPT Presentation

Segmented-Crystal Electromagnetic Precision Calorimeter (S-CEPCal) 12 March 2019 Calorimetry Workshop, IHEP, Beijing, China Sarah Eno (University of Maryland, College Park) Marco Lucchini (Princeton), Chris Tully (Princeton)

Performance Goals for Electromagnetic Precision Calorimeter } Put Z à ee on equal footing with Z à µµ µµ recoil x3 improvement on electron Brem. energy measurement } } Improve PFA EM shower imaging and separation x100 increase on EM shower sampling fraction (1/300 à ~1) } } Incorporate Precision Time-of-Flight System ~20ps MIP/photon timing with high granularity (~3mm) } } Include Dual-Readout capabilities for hadrons Dual wavelength filters for Cherenkov/Scint discr. } } Extend Physics Program w/ EM Res. and Timing Neutrino counting ( Z à nng / Z à µµ g ), Long-lived Particles, } Cosmics/Out-of-time background reduction for Emiss } Cost-effective solution Segmented crystals with SiPM readout } 2

nTracks Electron Bremsstrahlung in Tracker ● primary electron likely showers ● counting number of tracks at the entrance of the timing layer (e+, e-, gamma) 0.5 GeV 1 GeV 10 GeV 45 GeV Tracker Material Increasing Count Tracks counting tracks and (e+,e-, photons) measuring momentum here Crossing Here (in front of T1) 3 6-Layer Silicon Tracker S-CEPCal

Electron should be done well at e + e - Collider } Muons } Electrons Muon Track Electron Track Δ p/p ~0.3% Δ p/p tail ~1-2% (two tracks) Not yet there w/ CDR reference design (needs Brem. recovery w/ EM res.) ~1-2% @ 5%/ √ E loss à ~<0.3% in quadrature 4

Three Regimes of EM Resolution } For EM showers in a sampling calorimeter, the energy resolution is dominated by the sampling fluctuations: * Si-W ( 100µ m - HGC) * Si-W ( 300µ m - HGC) ( s E / E ) EM * √ E [%] X 0 (Si)/X 0 (W)=27 (Courtesy of R. Wigmans) Homogeneous crystals 5

Segmented Crystal Calorimeter Module 1 layer: 30 ps Timing layer: ● 2 layers: 20 ps + tracking LYSO:Ce crystals ○ SiPMs ○ 3x3x54 mm ³ active cell ○ ○ 3x3 mm ² SiPMs (15-25 um) < 5%/sqrt(E) (+) 1% ~ 30 ps timing achieved for p T >40GeV ● ECAL layer: ○ PbWO crystals ○ front segment 5 cm (~5.4X 0 ) rear segment for core shower ○ (15 cm ~16.3X 0 ) ○ 10x10x200 mm ³ of crystal ○ ○ 5x5 mm ² SiPMs (10-15 um) Front segment with SiPM in front and 6 rear segment with SiPM on back à Avoids dead material at shower max 6

Electron Energy Resolution (no Dead Material) Geant4 Simulation: Segmented Crystal Calorimeter - Electrons 2 (E) / E [%] 10 total energy resolution σ ⊕ (E)/E = 5.0% / E 0.5% eff shower containment fluctuations photostatistics eff σ 10 1 − 1 2 10 1 10 10 Beam energy [GeV] 7

Dead Material between Layers Impact of dead material between layers T1+T2 E1 E2 ● Services required: 0.8X 0 5X 0 15X 0 ○ FE/ASIC for read-out → PCB material ○ Cooling plate ○ Cables ● Space allocated: ○ 5 cm in front of crystal timing layer T1 (for T1 read-out) Negligible degradation up to 10 mm Al Effect more pronounced below 1 GeV ○ 10 cm in front of crystal ECAL E1 ■ 5 cm for T2 and 5 cm for E1 → cooling plate may be shared ○ 5 cm in front of crystal ECAL E2 (for E2 read-out) rear ● Material budget: ○ Realistic cooling plate ~ 3 mm Al → 0.035 X 0 ○ PCB ~ 2 mm, + cables, etc ○ total: 0.056 X 0 (5 mm Al equivalent) for each layer ○ Scan up to 0.5X 0 / layer 8

Impact of Dead Material between Layers Contribution from dead material <4%/sqrt(E) Shower fluctuations only Total (including photostat.) Stochastic term vs dead material 9

Dead Material including Tracker Layout overview Tracker Segmented Crystal ECAL + Timing HCAL T1+T2 E1 E2 1.2 m, 0.1-0.7 X 0 , Si 0.8X 0 5X 0 15X 0 Fe Fe Fe Solenoid Al 84 84 84 mm mm mm 130 mm 0.5 λ 0 4.5 X 0 0.5λ 0 0.5λ 0 0.5λ 0 0.3λ 0 4.8X 0 4.8X 0 4.8X 0 5 cm spacing 5 mm Al 0.056 X 0 (cooling, services) 1λ 0 1λ 0 1λ 0 5λ 0 2 layers 2 layers 4 layers 11 layers 10

Additional Views Geant4 views 11

Impact of Tracker Material Impact of tracker material budget T1+T2 1.2 m, 0.1-0.7 X 0 , Si ● Study impact of tracker material budget in front of 0.8X 0 SC-E(P)CAL ● Material budget: ○ Realistic material budget ~0.3X 0 ? ○ Scan up to 0.7X 0 ● Negligible impact on energy resolution 12

Imaging Capabilities of Silicon (~1/300) One event Fluctuations driven by CO 2 (-35 C) Low Sampling Fraction(~1/300) Cooling plate High SF à one shower looks like many e rd 13 Several thousand events

S-CEPCal Single EM Shower (High Stat) Shower imaging - “many events” T1+T2 E1 E2 electron 14

Shower imaging - “many events” (log scale) S-CEPCal Single EM Shower (High Stat- Log) 15

Shower separation - “many events” S-CEPCal Pair of EM Showers (High Stat) 16

Shower separation - “many events” (log scale) S-CEPCal Pair of EM Showers (High Stat - Log) 17

Shower separation - “single event” S-CEPCal Pair of EM Showers (Single Event) 18

Shower separation - “single event” (log scale) S-CEPCal Pair of EM Showers (Single Event - Log) 19

Electron/ p ± Discrimination 120 GeV pion 120 GeV electron Counts Counts 1 st Timing: total energy Timing: total energy 2 2 1 st 10 10 Timing: first layer Timing: first layer 2 nd Timing: second layer Timing: second layer 2 nd 1+2 Timing Layers Timing Layers 1+2 p ± electron 10 10 1 1 0 0.01 0.02 0.03 0.04 0.05 0 0.002 0.004 0.006 0.008 0.01 Energy deposit [GeV] Energy deposit [GeV] 120 GeV pion 120 GeV electron Counts Counts Front Total ECAL: total energy ECAL: total energy ECAL: front segment Rear ECAL: front segment 2 10 ECAL: rear segment Rear ECAL: rear segment Front 2 Total Calo Layers 10 p ± Calo Layers electron 10 10 1 1 0 20 40 60 80 100 120 0 0.2 0.4 0.6 0.8 1 20 Energy deposit [GeV] Energy deposit [GeV]

Electron/ p ± Discrimination 45 GeV 1 12 Ratio ECAL front / ECAL rear non-converting pions 10 electrons 8 1 − 10 6 converting pions 4 2 − 10 2 0 − 1 2 10 1 10 10 Total energy deposit in ECAL [GeV] 21

Energy Resolution and Dynamic Range ● 5%/sqrt(E) → LO>400 phe/GeV → LO>0.4 phe/MeV at LCE~2.5%, PDE ~ 20% → LY>80 ph/MeV ○ Ok for PWO (~100 ph/MeV) ○ ● Maximum energy deposit in single crystal for 120 GeV e.m. shower ~60% ~ 35000-70000 phe for ~72 GeV (at PDE~20-40% resp.) ○ ● SiPM 5x5 mm ² on a 10x10 mm ² crystal is sufficient LCE~2.5% ○ if cell size: 15 um → cells / SiPM ~110,000 and PDE up to 40% ○ if cell size: 10 um → cells / SiPM ~250,000 and PDE up to 25% ○ ● Sensitivity for 0.1 GeV particles 40 phe signal ○ Noise from SiPM within 30 ns integration gate negligible ○ (DCR<10MHz → noise<1 phe) 22

Photostatistics Photostatistics ● 5%/sqrt(E) → LO>0.4 phe/MeV ○ for LCE~2.5% (9 mm² SiPM), PDE ~ 20% → The crystal must have a LY>80 ph/MeV ● SiPM 3x3 mm² on a 10x10 mm² crystal is sufficient ○ with SiPM area = crystal end face → LCE~30% 23

Small Crystal Geometries for Timing Detectors } Tiles and Bars (few mm thick w/ area of ~1cm 2 ) } CMS MTD: Single layer ~330,000 channels } Stereo readout for bars (L/R) ~25ps timing resolution Non-wrapped crystal bar with 2 SiPMs attached at each end 3x3x50mm 3 crystal incoming particles Option A for CMS MIP Timing Detector TDR Basic Module Crystal Scintillator (eg. BGO, LYSO…) Low occupancy timing layer timing for ~1 X0 1x1x40cm ³ Transverse orientation w/ stereo readout Photodetectors (eg. FPMT, SiPM…) Similar study at IHEP Basic Unit by Yuexin Wang 24

Time-of-Flight Particle ID (R=1.2m) Single Layer (30 ps) Improves by 1/ √ 2 w/Dble Layer 25

Dual-Readout Capability Dual readout calorimetry in ECAL ● PWO - excellent Cherenkov radiator (transparency cut off at 350 nm) ● Exploit Cherenkov photons above PWO emission spectrum Good PDE at 600 nm ● 2 SiPMs, one with optical filter > 600 nm, another <600 nm optical filter 26

Dual-Readout ECAL+HCAL Compatibility Layout overview Tracker Segmented Crystal ECAL + Timing HCAL T1+T2 E1 E2 1.2 m, 0.1-0.7 X 0 , Si 0.8X 0 5X 0 15X 0 Projective or Muon Fe Fe Fe Projective Sc/C Solenoid Planar Sc/C System Al 84 84 84 mm mm mm 130 mm 0.5 λ 0 Fiber Bundles? Tiles/Fiber Plastic 4.5 X 0 0.5λ 0 0.5λ 0 0.5λ 0 0.3λ 0 Bundles? or Gas? 4.8X 0 4.8X 0 4.8X 0 5 cm spacing 5 mm Al 0.056 X 0 (cooling, services) 1λ 0 1λ 0 1λ 0 5λ 0 2 layers 2 layers 4 layers 11 layers Scint.fibers SiPM Solenoid Inner Radius Ch.fibers Outside ECAL and ECAL/HCAL Sc/C filters Sc/C filters SiPM Interface? 2x SiPM 2x SiPM 27

EM Resolution and Photon Counting } EM Resolution also improves angular measurements and resolves N 𝛅 counting } Recoil photons (~8% of full √ s collision rate) } New Physics Searches and Neutrino Counting L3 L3 10 400 Data N ν = 4 Improved Syst. N ν = 3 (A. Blondel) 1 300 N ν = 2 Events / 4 GeV _ ( γ ) e + e − → νν σ (nb) -1 200 10 N ν = 4 _ γ ( γ ) e + e − → νν -2 100 10 N ν = 2 0 100 120 140 160 180 200 0 50 100 150 200  (GeV) √ s Recoil Mass (GeV) E. Bartos et al ., “2 γ and 3 γ annihilation as calibration processes for high energy e+e − colliders,” 28 https://arxiv.org/abs/0801.1592