Detector Physics with MicroBooNE Yifan Chen University of Bern TAUP, Toyama, 10th September 2019 For MicroBooNE collaboration
Short-Baseline Neutrino Oscillation Program (SBN) Booster Neutrino Beam 8 GeV proton ICARUS MicroBooNE SBND ν μ , few ν e ν μ 110 m Few ν e Fewer ν μ ? 470 m More ν e ? Fewer ν μ ? 600 m More ν e ? Aim to understand MiniBooNE e-like low energy excess • Excellent e/ γ separation Liquid Argon • Excellent position and energy resolution Time Projection Chambers • Fairly low detection threshold for neutrino events (LAr TPCs) Detector physics with MicroBooNE Yifan Chen, University of Bern � 2
Working Principles of LAr TPCs 1. Charge particles ionising LAr 2. Ionised electrons drift to the anode plane along the electric field (E-field) 3D topology 2D from read-out plane 1D from time projection 3D calorimetry Charge deposition in the read-out wires Ar Particle identification by both electron drift velocity topology and calorimetry E-field JINST 12 (2017) P02017 Detector physics with MicroBooNE Yifan Chen, University of Bern � 3
The MicroBooNE Detector • A comprehensive LAr TPC with ‣ Three wire read-out planes: one collection Y plane (wires: vertical) two induction U, V planes (wires: ±60°) ‣ 32 photomultipliers(PMT) for light readout ‣ UV laser system for E-field calibration ‣ Cosmic ray tagger e o d t h C a d e n o A • Active mass of LAr 85 t m 2 2 . 3 Y : Total mass of LAr 170 t • 70 kV on the cathode ‣ 273 V/cm E-field ‣ 1.098 mm/ μ s drift speed • Operating on the surface m 6 0 . 3 1 Z : • Data taking since autumn 2015 • mm-scale spatial resolution m 6 2 . 5 X : • 4 π angular coverage JINST 12 (2017) P02017 • 300 MeV momentum detection threshold for proton Detector physics with MicroBooNE Yifan Chen, University of Bern � 4
LAr Scintillation and Light Collection in MicroBooNE • Bright LAr scintillation light O(10k photons/ MeV) • 128 nm UV photons release at de-excitation of LAr excimer • LAr is transparent to its own scintillation Self-trapped exciton luminescence Illustrated by Ben Jones Radioactive Recombination luminescence decay • 32 PMTs (8-inch) covered by TPB-coated acrylic plates ‣ TPB shift the wavelength of LAr scintillation to 430 nm (in PMT sensitive region) • PMT readout window is ~ms around neutrino beam spill Detector physics with MicroBooNE Yifan Chen, University of Bern � 5
Use of Light Signal in MicroBooNE Trigger • Require PMT activity in time with beam trigger ‣ Suppress empty beam triggered events with cosmic only activity ‣ The trigger rate drops by a factor of 20 Flash-matching (match the TPC energy deposit to the light signal) • Optical flash requirement: The integration of all PMT signals exceed a background level • Light hypothesis: The consistency of reconstructed light signals from the PMTs and the modelled light signal corresponding to a cluster of charge deposition Physics result using flash-matching! ν μ CC inclusive cross-section measurement arXiv:1905.09694, accepted by PRL Detector physics with MicroBooNE Yifan Chen, University of Bern � 6
Cosmic Ray Tagger (CRT) Wavelength Shifting Fibers Protection Mylar Tape CRT is essential 1.75 m wide for MicroBooNE 16 Scintillating • To gain more information about Strips cosmics Scintillating strips SIPM on the other side so to use them as calibration source and for cosmic flux study Instruments 1 (2017) JINST 14, P04004 (2019) • To remove cosmic background • To gain precise time information (~ ns resolution) for CRT matched tracks in the TPC (cosmic- or neutrino- induced) • To gain an unbiased sample for trigger efficiency study Detector physics with MicroBooNE Yifan Chen, University of Bern � 7
Particle Identification by Topology and Calorimetry photon Showers shower electron dE/dx shower ~ 2 M.I.P gap MicroBooNE is an excellent imaging detector and calorimeter, which is powerful in particle identification 4 protons e/ γ shower separation Tracks • The distance in between the shower start and the neutrino vertex • dE/dx at the beginning of the shower muon Muon, proton and pion separation • Calorimetry profile of dE/dx, especially of their Bragg peaks Detector physics with MicroBooNE Yifan Chen, University of Bern � 8
Charge dQ/dx and Energy dE/dx W ion Cathode dE/dx Ionisation dQ/dx (a) initial Recombination dQ/dx (b) after recombination Lifetime (charge attenuation) Charge di ff usion by electro-negative impurities dQ/dx (c) after di ff usion and impurities Anode Readout dQ/dx (d) from readout Detector physics with MicroBooNE Yifan Chen, University of Bern � 9
Dynamic Induced Current and 2D Deconvolution • Dynamic induced current (DIC): drifting electrons induce the current on nearby wires • MicroBooNE is the first to simulate DIC in LArTPC • Vital for various track orientations • Improvement shows in data / MC agreement U plane bipolar unipolar JINST 13, P07006 (2018) 2D deconvolution in signal processing time (conventional 1D) and wires Detector physics with MicroBooNE Yifan Chen, University of Bern � 10
<latexit sha1_base64="r29naiqgA5KuEz2uBy5VzxOoQCY=">ACInicbVDLSgMxFM3UV62vUZdugkVoQepMFdSFUOzGZQv2AW0tmUymDc1MhiQjtkO/xY2/4saFoq4EP8a0nYW2HgczjmXm3uckFGpLOvLSC0tr6yupdczG5tb2zvm7l5d8khgUsOcdF0kCSMBqSmqGKkGQqCfIeRhjMoT/zGPRGS8uBWDUPS8VEvoB7FSGmpa16Wc8PjUR5ewbYnEI5zbvXEfcjfxT3GHcTG4ziXSDoHR3ntMI4nRtfMWgVrCrhI7IRkQYJK1/xouxHPgkUZkjKlm2FqhMjoShmZJxpR5KECA9Qj7Q0DZBPZCenjiGR1pxoceFfoGCU/X3RIx8KYe+o5M+Un05703E/7xWpLyLTkyDMFIkwLNFXsSg4nDSF3SpIFixoSYIC6r/CnEf6aqUbjWjS7DnT14k9WLBPi0Uq2fZ0nVSRxocgEOQAzY4ByVwAyqgBjB4BM/gFbwZT8aL8W58zqIpI5nZB39gfP8ABXeiLA=</latexit> Charge Uniformity Charge uniformity correction is needed mainly due to readout channel response (gain factor) We use anode piercing tracks arXiv:1907.11736, submitted to JINST ( dQ/dx ) global (c) C ( y, z ) = (( dQ/dx )( y, z )) local (d) Detector physics with MicroBooNE Yifan Chen, University of Bern � 11
<latexit sha1_base64="qbAY5fpJsDUIUGTM4uKnx/JeaI=">ACKXicbVDLSgMxFM34tr6qLt0Ei1AX1hkVdCMU3bhUsA9oa8lk7mgwkxmSO2IZ5nfc+CtuFBR164+YPsDngcDhnHPJvcdPpDoum/O2PjE5NT0zGxhbn5hcam4vFI3cao51HgsY930mQEpFNRQoIRmoFvoSGf3c9xs3oI2I1Tn2EuhE7FKJUHCGVuoWq+1QM56Vg7Pt4HbzImMqDiDPvwQbvBpI9JDCbVLewm4WaBFivt1Glm52iyW34g5A/xJvREpkhNu8akdxDyNQCGXzJiW5ybYyZhGwSXkhXZqIGH8ml1Cy1LFIjCdbHBpTjesEtAw1vYpAP1+0TGImN6kW+TkV3c/Pb64n9eK8XwoJMJlaQIig8/ClNJMab92mgNHCUPUsY18LuSvkVs9WhLbdgS/B+n/yX1Hcq3m5l52yvVD0a1TFD1sg6KROP7JMqOSGnpEY4uSMP5Jm8OPfOo/PqvA+jY85oZpX8gPxCX0RpsU=</latexit> Electron Lifetime • LAr in MicroBooNE has high purity most of the time High purity • For high purity period, charge attenuation is negligible • For low purity period, charge Low purity attenuation follows exponential. (electrons can be removed by electro-negative impurities) anode • We use anode-cathode piercing tracks to determine electron lifetime τ ( dQ/dx ) anode (c) ( dQ/dx ) cathode = exp ( − t drift / τ ) cathode (b) arXiv:1907.11736, submitted to JINST Detector physics with MicroBooNE Yifan Chen, University of Bern � 12
Charge Recombination and Energy Deposition • Neutrino-induced proton sample arXiv:1907.11736, submitted to JINST • Use modified box model • dE/dx from ranged-based method (b) NIM A 523 2004) 275 Modified box model Energy deposition Detector physics with MicroBooNE Yifan Chen, University of Bern � 13
Importance of E-field in LArTPC E-field dependent E-field dependent Calorimetry Tracking Cathode Ar Ionisation dQ/dx (a) initial Recombination dQ/dx (b) after recombination e - Charge Lifetime (charge attenuation) di ff usion by electro-negative impurities dQ/dx (c) after di ff usion and impurities Readout dQ/dx (d) electron drift Anode from readout velocity E-field Detector physics with MicroBooNE Yifan Chen, University of Bern � 14
UV Laser for Independent E-field Measurement > 10 m 2 UV laser sub-system • one upstream, one downstream Both are steerable and can be remotely • controlled (first time in LAr TPCs) UV laser (266 nm) can generate • reproducible, long, straight tracks, with no delta rays, with no Multiple Coulomb Scattering in LAr TPC Feedthrough Provide true track position independent • of TPC readout from laser M3 box Cathode Feedthrough MICROBOONE-NOTE-1055-PUB cold Top View mirror TPC Cryostat Anode Detector physics with MicroBooNE Yifan Chen, University of Bern � 15
Measurement of Spatial Displacement Cathode • Track Iteration: map the reconstructed True Reco tracks to true tracks D(backward) • Boundary Condition: no spatial distortion at the anode D(forward) • Interpolation to form regular grid X or Y TPC r i r i d i L exit t i t i L entry Anode Read-out Z MICROBOONE-NOTE-1055-PUB MicroBooNE Laser Data X - X [cm] @ Z = 518 cm Y - Y [cm] @ Z = 518 cm Z - Z [cm] @ Z = 518 cm reco true reco true reco true 1 Y [cm] Y [cm] Y [cm] 15 100 100 100 0.8 4 10 0.6 3 50 50 50 0.4 5 0.2 2 0 0 0 0 0 0.2 − 1 5 − 0.4 50 50 50 − − − − 0 0.6 − 10 − 0.8 − 100 100 100 − − − 1 − 15 − 1 − 0 50 100 150 200 250 0 50 100 150 200 250 0 50 100 150 200 250 X [cm] X [cm] X [cm] Detector physics with MicroBooNE Yifan Chen, University of Bern � 16
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