Measuring Hadronic Showers in a Totally Active Dual-Readout Crystal - PowerPoint PPT Presentation

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides Measuring Hadronic Showers in a Totally Active Dual-Readout Crystal Calorimeter A simulation study of single hadron showers in lead tungstate ( PbWO 4 ) Alexander Conway 1 , 2 1 University of Chicago 2 Fermi National Accelerator Laboratory America’s Workshop on Linear Colliders, May 2014 A. Conway UofC and FNAL AWLC’14 1 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides Table of Contents Dual-Readout Correction 3 Introduction 1 Energy Resolution 4 Time and Energy Cuts 2 Conclusions 5 A. Conway UofC and FNAL AWLC’14 2 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides Motivation Our dual-readout calorimeter concept and simulation was developed for future lepton colliders. Need excellent hadronic energy resolution in high-background environment. One benchmark is distinguishing W and Z bosons in hadronic decay mode. Requires di-jet energy resolution better than 3%, or √ � σ/ E ∼ 20 − 30% / E ( GeV ), depending on ˆ s . Fast timing, energy cuts essential for background suppression. New technology needed! A. Conway UofC and FNAL AWLC’14 3 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides Motivation Hadron energy resolution limited by: Fluctuations in nuclear binding energy loss. → Dual-readout. Sampling fluctuations from sharing energy between active and passive materials. → Homogeneous and totally active. Fluctuations in leakage (neutrinos, muons, shower tails). → High density contains showers, reduces leakage. Non-Gaussian energy response with non-linear resolution. → Dual-readout correction gives linear, Gaussian response. Prompt Cerenkov light allows for fast timing. A. Conway UofC and FNAL AWLC’14 4 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides Motivation Goals: Develop tools for full, efficient simulation and analysis of dual-readout calorimetry. Develop understanding of dual-readout hadron calorimetry. Demonstrate energy resolution and background suppression that can be achieved. A. Conway UofC and FNAL AWLC’14 5 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides The Detector: mcdrcal01 mcdrcal01 viewed in HepRApp Data Browser. White: EM calorimeter. Gray: Hadron calorimeter. Black: Muon system. Figure: Beam view. Developed for Higgs factory Muon Collider. Large cone (15 ◦ ) required for shielding. Idealistic: no magnet coil, no instrumentation. Highly segmented EM and Hadron calorimeters. Homogenous and fully active. 5 Tesla field. Figure: Side view. A. Conway UofC and FNAL AWLC’14 6 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides The Detector: mcdrcal01 mcdrcal01 viewed in ROOT GDML browser. A. Conway UofC and FNAL AWLC’14 7 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides The Detector: mcdrcal01 EM Hadron Muon Material PbWO 4 PbWO 4 Iron Density ( g / cm 3 ) 8.28 8.28 7.87 Rad. Length ( cm ) 0.93 0.93 1.76 IA Length ( cm ) 20.3 20.3 16.8 Moli` ere Rad. ( cm ) 1.96 1.96 1.72 Inner Radius ( cm ) 131.0 152.0 303.0 Inner z ( cm ) 200.1 220.2 370.3 Cell Size ( ℓ × w × d , cm ) 1 × 1 × 2 2 × 2 × 5 10 × 10 × 10 Layers 10 30 22 Depth ( cm ) 20 150 220 Num IA Lengths 0.99 7.4 13.1 A. Conway UofC and FNAL AWLC’14 8 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides Sample Event Display √ Figure: h → b ¯ b event at Higgs Factory Muon Collider, s = 125 GeV , ˆ 10 MeV cut. A. Conway UofC and FNAL AWLC’14 9 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides What is ‘Dual-Readout’? Dual-readout calorimetry measures photons from two separate physical processes; scintillation and Cerenkov radiation. Scintillation Cerenkov Number of photons Prompt process. proportional to deposited Can use Cerenkov signal to energy. select calorimeter cells to Decay time ∼ 10’s ns read out scintillation (simulation is instant!). (hypothetical, not tested here). Cerenkov and scintillation sensitive to different parts of a hadron shower. Dual-Readout Correction: correction to energy readout on event-by event basis using correlation between (C)erenkov and (S)cintillation. A. Conway UofC and FNAL AWLC’14 10 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides Software Used ALCPG Framework: Simulation and reconstruction framework developed by the American Linear Collider Physics Group. SLIC (Simulator for the Linear Collider) Geant4-based simulation package. Generation of particles and simulation in detector. .slcio ouptut. LCDD (Linear Collider Detector Description) XML format for detector description (convert from compact.xml to .lcdd with GeomConverter). Note: LCDD was updated to provide efficient Cerenkov simulation for dual-readout calorimetry; see extra slides. LCSim (Linear Collider Simulation) Java reconstruction and analysis framework. XML interface for batch processing. A. Conway UofC and FNAL AWLC’14 11 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides Time Cuts Fast timing will be essential for background suppression at a muon collider. We use a time-of-flight correction to create a moving time window for time cuts. Subtract the time taken for light to travel from IP to calorimeter cell from the time of the deposit. [More detail...] A. Conway UofC and FNAL AWLC’14 12 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides Time Cuts – MuC Example Muon Collider Backgrounds: Machine backgrounds from muon beam decay. Mostly photons and neutrons. Background not normalized. Signal in HCal, bkg in ECal. Time Cuts: Majority of signal in first ns. Cuts should be in 3–10ns range. 3ns cut eliminates 92% of Histograms weighted by energy. background, 5% of proton log 10 t time axis. signal compared to 10ns cut. A. Conway UofC and FNAL AWLC’14 13 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides Energy Cuts Scintillation Cuts: 25 GeV Proton: MIP deposits Scintillation response: dE / dx = 10 . 1 MeV / cm , or ∼ 20 MeV/cell in EM cal, 50 MeV/cell in Had cal. Cuts based on fraction of MIP (1/50, 1/10, 1/2). (a) No cut (b) 25 MeV cut Cerenkov response: Cerenkov Cuts: Using 500 γ/ cm as basis. 1/10 MIP cut means 2 (5) MeV and 100 (250) γ cuts in EM (hadronic) (a) No cut (b) 1250 γ cut calorimeter. A. Conway UofC and FNAL AWLC’14 14 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides Cerenkov Calibration Using Electrons Convert number of Cerenkov photons to an energy. Use electrons with range of energies. Fit Cerenkov response at each energy with Gaussian. Fit electron energy to Cerenkov responses with line. Slope gives conversion factor for number of photons to energy. Slope: 1 . 9 × 10 − 5 GeV / photon Also do this with ∼ 53 , 000 photons / GeV scintillation. → A. Conway UofC and FNAL AWLC’14 15 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides DR Correction With Protons Plot (S)cintillation response fraction vs. (C)erenkov/(S)cintillation. Figure: C/S histogram and fit for 25 GeV proton, 3ns, 1/10 MIP cuts. Fit to 4 th order polynomial in C/S. Use polynomial to obtain correction: E corr = S / Poly ( C / S ). A. Conway UofC and FNAL AWLC’14 16 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides Energy and Cut Dependence Correction function has energy dependence. Steeper with sharper cuts. Correct with nearest-energy curve (or weighted mean). A. Conway UofC and FNAL AWLC’14 17 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides DR Corrected Energies (a) σ/ E : SR: 19.6%, DR: 16.3% (a) σ/ E : SR: 13.2%, DR: 7.6% (b) σ/ E : SR: 9.8%, DR: 3.8% (b) σ/ E : SR: 9.0%, DR: 2.8% Cuts: 3 ns , 1/10 MIP. Suppressed zeros on plots. A. Conway UofC and FNAL AWLC’14 18 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides DR Corrected Energies — Linearity DR has good linearity. A. Conway UofC and FNAL AWLC’14 19 / 31

Introduction Time and Energy Cuts Dual-Readout Correction Energy Resolution Conclusions Extra Slides Resolution Curves We parameterize energy resolution as: σ α + β + γ E = (1) √ E E Where α = Stochastic term - Dominant at low energies. β = Constant term - Dominant at high energies. γ = Noise term - Taken as 0 in this simulation � Plot σ/ E vs. 1 / E ( GeV ) and fit with line. Slope gives α , intercept gives β . Empirical fit. Errors not added in quadrature. A. Conway UofC and FNAL AWLC’14 20 / 31