Highly Granular ECAL Studies in a HP-TPC Context Lorenz Emberger, - PowerPoint PPT Presentation

Highly Granular ECAL Studies in a HP-TPC Context Lorenz Emberger, Frank Simon Max-Planck-Institute for Physics DUNE Near Detector Workshop, Fermilab, March 2018

Outline • A case for high granularity in the ECAL • Straw man ECAL concept for a HP TPC • Preliminary simulation results: • Energy resolution • Angular resolution • Scaling behavior with geometry changes • Neutral pions • Real-world considerations: Channel count • Possibilities: Timing ND ECAL Update 2 Frank Simon (fsimon@mpp.mpg.de) DUNE ND Workshop, Fermilab, March 2018

A Case for Higher Granularity? • An area where the ECAL can go beyond initial plans would be the capability to associated π 0 s to neutrino interaction vertices in the tracking detector • Generally useful - but particularly interesting in combination with a HP TPC, since the conversion probability in the TPC gas is too low to enable e ffi cient π 0 reconstruction ND ECAL Update 3 Frank Simon (fsimon@mpp.mpg.de) DUNE ND Workshop, Fermilab, March 2018

Straw Man Concept for HP TPC ECAL • Space inside pressure vessel is “premium real estate” ➫ Cannot accommodate full calorimeter (depth ~ 80 cm) inside the vessel ➫ Split the calorimeter into two sections, separated by the pressure vessel ND ECAL Update 4 Frank Simon (fsimon@mpp.mpg.de) DUNE ND Workshop, Fermilab, March 2018

Straw Man Concept for HP TPC ECAL 50 layers 30 layers ~ 400 mm ~ 250 mm inner ECAL outer ECAL pressure vessel ~ 6 X 0 ~ 10 X 0 N.B. Not yet fully optimised - in particular outer segment! 14 - 20 mm • A two-component detector, separated by the pressure vessel • Default configuration: 1 mm Pb absorber, 5 mm plastic scintillator per layer • Other absorber configurations also studied ND ECAL Update 5 Frank Simon (fsimon@mpp.mpg.de) DUNE ND Workshop, Fermilab, March 2018

Straw Man Concept for HP TPC ECAL 20 - 30 mm 1 mm 5 mm 1 mm signal / power routing Pb absorber plastic scintillator SiPM • First design & simulations: assume a granularity of 
 20 x 20 - 30 x 30 mm 2 ND ECAL Update 6 Frank Simon (fsimon@mpp.mpg.de) DUNE ND Workshop, Fermilab, March 2018

Simulations - Present Status • GEANT4 - based detector simulations • Default detector geometry: 1 layer implemented as • 1 mm lead • 5 mm plastic scintillator • 1 mm air (assuming low-density layer for signal routing - may be made more realistic) • Default granularity: 20 x 20 mm 2 inside pressure vessel, 40 x 40 mm 2 outside • Simplified digitization • amplitude smearing to account for electronic noise, photon statistics (~ 20% of a MIP signal as σ ) • amplitude cut on each cell - 0.15 x MPV of a MIP • Still missing: Electronics at back end of inner ECAL: Will add material! ND ECAL Update 7 Frank Simon (fsimon@mpp.mpg.de) DUNE ND Workshop, Fermilab, March 2018

Simulations: Reconstruction • For energy resolution: Take visible energy in calorimeter (with smearing, cell-level cuts applied); no clustering • For direction of photons: A simple two-step approach: • principal component analysis of all detector hits 
 to determine first estimate of shower axis • 3D line fit through layer-wise center of gravity 
 using PCA as input to further improve estimate Fits (energy & angular resolution): v ! 2 u ◆ 2 ✓ A B u Resolution = + + C 2 t p E [ MeV ] E [ MeV ] N.B.: to get stochastic term in units of 
 1/Sqrt(GeV) divide A by 32 ND ECAL Update 8 Frank Simon (fsimon@mpp.mpg.de) DUNE ND Workshop, Fermilab, March 2018

Single Photon Performance Metrics • Energy resolution given by σ /mean mean Entries 900 0.22 Mean 208.2 0.2 ± /E 1.527 0.01451 A ± 800 σ 0.2 Sigma 14.58 0.21 0.2364 0.9716 ± B ± 700 C 0.03679 0.001736 0.18 ± E γ 650 MeV 600 0.16 stoch. term: 4.8%/sqrt(E[GeV]) 500 0.14 400 0.12 300 0.1 ~ 6% @ 1GeV 0.08 200 0.06 100 0.04 0 0 50 100 150 200 250 300 350 400 0 200 400 600 800 1000 1200 1400 1600 Visible Energy[MeV] Energy[MeV] Note: Over-optimistic - not all detector e ff ects simulated! ND ECAL Update 9 Frank Simon (fsimon@mpp.mpg.de) DUNE ND Workshop, Fermilab, March 2018

Single Photon Performance Metrics • Energy resolution given by σ /mean mean Entries 900 0.22 Mean 208.2 0.2 ± /E 1.527 0.01451 A ± 800 σ 0.2 Sigma 14.58 0.21 0.2364 0.9716 ± B ± 700 C 0.03679 0.001736 0.18 ± E γ 650 MeV 600 0.16 stoch. term: 4.8%/sqrt(E[GeV]) 500 0.14 400 0.12 300 0.1 ~ 6% @ 1GeV 0.08 200 0.06 100 0.04 0 0 50 100 150 200 250 300 350 400 0 200 400 600 800 1000 1200 1400 1600 Visible Energy[MeV] Energy[MeV] • Angular resolution given by 68%ile Note: Over-optimistic - not all detector e ff ects simulated! AngularResolution[rad] Entries 250 0.45 68% ≙ 0.089rad A 1.694 0.02459 ± 0.4 B 18.31 0.6835 ± C 1.488e 05 0.07023 − ± 200 0.35 0.3 150 0.25 stoch. term: 0.053/sqrt(E[GeV]) E γ 450 MeV 0.2 100 0.15 0.1 50 0.05 0 0 200 400 600 800 1000 1200 1400 1600 0 0.1 0.2 0.3 0.4 Energy[MeV] Angle[rad] ND ECAL Update 9 Frank Simon (fsimon@mpp.mpg.de) DUNE ND Workshop, Fermilab, March 2018

The Parameter Studies • Absorber: • di ff erent thickness: 1mm, 2mm • di ff erent materials: lead, copper ‣ Changes sampling fraction and Moliere radius (size of shower) • Active elements: • di ff erent cell sizes: 5mm - 40mm ‣ Changes “image resolution”and channel count First goal: Understand scaling behavior of detector performance for configuration changes ND ECAL Update 10 Frank Simon (fsimon@mpp.mpg.de) DUNE ND Workshop, Fermilab, March 2018

The Parameter Studies Inner ECal 𝜹 1 Outer ECal v µ Beam axis 𝜹 2 Pressure Vessel TPC Volume ~25cm ~40cm • Considering di ff erent granularities in di ff erent ECAL sections • Also: changing granularity in inner ECAL [not shown…] First goal: Understand scaling behavior of detector performance for configuration changes ND ECAL Update 11 Frank Simon (fsimon@mpp.mpg.de) DUNE ND Workshop, Fermilab, March 2018

Single Photons: Impact of Pressure Vessel • ECAL configuration: 1 mm Pb, inner granularity 20 mm, outer granularity 40 mm Angular Resolution Energy Resolution Angular Resolution[rad] mean 0.45 NO Pressure Vessel 0.22 NO Pressure Vessel A: 1.649 B: 18.56 C: 0.000 /E A: 1.405 B: 1.109 C: 0.017 0.4 0.2 14mm Titan Vessel 14mm Titan Vessel σ A: 1.694 B: 18.31 C: 0.000 A: 1.526 B: 0.236 C: 0.036 0.35 0.18 20mm Steel Vessel 20mm Steel Vessel A: 1.750 B: 17.43 C: 0.000 A: 1.503 B: 0.081 C: 0.079 0.16 0.3 0.14 0.25 0.12 0.2 0.1 0.15 0.08 0.1 0.06 0.05 0.04 0 200 400 600 800 1000 1200 1400 0 200 400 600 800 1000 1200 1400 Energy[MeV] Energy[MeV] ND ECAL Update 12 Frank Simon (fsimon@mpp.mpg.de) DUNE ND Workshop, Fermilab, March 2018

Single Photons: Impact of Pressure Vessel • ECAL configuration: 1 mm Pb, inner granularity 20 mm, outer granularity 40 mm Angular Resolution Energy Resolution 1.2 relative EnergyResolution relative AngularResolution 2.2 NO Pressure Vessel NO Pressure Vessel 14mm Titan Vessel 14mm Titan Vessel 1.15 20mm Steel Vessel 20mm Steel Vessel 2 1.1 1.8 1.6 1.05 1.4 1 1.2 0.95 1 0.9 0 200 400 600 800 1000 1200 1400 1600 0 200 400 600 800 1000 1200 1400 1600 Energy[MeV] Energy[MeV] ➫ Very mild impact on angular resolution: few % ➫ Substantial impact on energy resolution - thick steel vessel up to x2 deterioration, with titanium only ~ 30% loss compared to no vessel In the following: Always assume titanium vessel ND ECAL Update 13 Frank Simon (fsimon@mpp.mpg.de) DUNE ND Workshop, Fermilab, March 2018

Scaling of Energy Resolution with Absorber • Looking at four scenarios: 1 mm & 2 mm absorber plates, Pb & Cu • always: Ti pressure vessel smaller sampling fraction for 2 mm Pb: 
 mean 0.35 larger stochastic term 1mm Lead Absorber /E A: 1.526 B: 0.236 C: 0.036 σ 2mm Lead Absorber 0.3 substantial energy leakage for 1 mm Cu: 
 A: 2.392 B: 4.112 C: 0.015 1mm Copper Absorber not enough X 0 in calorimeter! 0.25 A: 1.178 B: 0.253 C: 0.080 2mm Copper Absorber A: 1.630 B: 3.289 C: 0.038 0.2 2 relative EnergyResolution 1mm Lead Absorber 2mm Lead Absorber 0.15 1mm Copper Absorber 1.8 2mm Copper Absorber 0.1 1.6 0.05 1.4 0 200 400 600 800 1000 1200 1400 Energy[MeV] 1.2 • Best performance for 1 mm Pb, only slight 1 performance loss when using 2 mm Cu 0.8 0 200 400 600 800 1000 1200 1400 1600 Energy[MeV] ND ECAL Update 14 Frank Simon (fsimon@mpp.mpg.de) DUNE ND Workshop, Fermilab, March 2018

Scaling of Angular Resolution with Absorber • Looking at four scenarios: 1 mm & 2 mm absorber plates, Pb & Cu • always: Ti pressure vessel, 20 x 20 mm 2 scintillator tiles in inner ECAL Angular Resolution[rad] 0.5 1mm Lead Absorber 0.45 A: 1.694 B: 18.31 C: 0.000 2mm Lead Absorber 0.4 A: 2.127 B: 19.46 C: 0.000 1mm Copper Absorber 0.35 A: 1.395 B: 15.81 C: 0.000 2mm Copper Absorber 0.3 A: 1.393 B: 16.32 C: 0.000 0.25 1.6 relative AngularResolution 1mm Lead Absorber 0.2 1.5 2mm Lead Absorber 1mm Copper Absorber 0.15 1.4 2mm Copper Absorber 0.1 1.3 0.05 1.2 0 200 400 600 800 1000 1200 1400 1.1 Energy[MeV] 1 0.9 0.8 0.7 0.6 0 200 400 600 800 1000 1200 1400 1600 Energy[MeV] ND ECAL Update 15 Frank Simon (fsimon@mpp.mpg.de) DUNE ND Workshop, Fermilab, March 2018