Photon Detector Designs for the Deep Underground Neutrino Experiment 28 August, 2015
Denver Whittington Indiana University
Outline ➢
Light guides for a single-phase TPC ➢ ➢
Baseline design Alternatives
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Silicon photomultipliers
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Design testing in LAr at FNAL ➢ ➢
Data-simulation comparisons Preliminary results from recent test
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Scintillation structure analysis
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Xenon-doped LAr
D. Whittington - DUNE Photon Detection - LIDINE 2015
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Light Guides for Large-Area Photon Detection ➢
Large active-area UV-collecting light guides ➢
Acrylic or polystyrene imbued with wavelength-shifting compound ➢ ➢
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Based on design pioneered by MIT Dip-coating w/ TPB in solvent (after studying many different methods)
430 nm light propagated by total internal reflection to end
Si PM
Ar ra y
128 nm LAr scintillation light
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430 nm shifted light (in bar)
Embed PD paddles inside anode plane assembly behind collection wires ➢
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Large photosensitive area with small photocathode area Low-voltage SiPM bias Easily scalable
D. Whittington - DUNE Photon Detection - LIDINE 2015
t0
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Light Guides for Large-Area Photon Detection ➢
Multiple light guide designs under investigation ➢
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Alternative designs decouple UV wavelength shifter (WLS) from transport for improved attenuation Dip-coated acrylic bars ➢ ➢ ➢ ➢
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WLS panel (VUV → blue) + imbedded WLS fibers ➢ ➢
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Louisiana State U, center Two SiPMs (one at each end)
WLS radiator (VUV → blue) + WLS fibers (blue → green) ➢ ➢
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Baseline design Indiana U, right-most paddle Nine SiPMs (3 per bar) One MIT bar (new recipe, 2nd fill)
Colorado State U, left-most Six SiPMs at top
WLS Radiator (VUV → Blue) + WLS bar (blue → green) Indiana U, cartoon below Si PM
Ar ra y
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D. Whittington - DUNE Photon Detection - LIDINE 2015
128 nm LAr scintillation light
430 nm shifted light from plate ~490 nm shifted light (in bar)
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Silicon Photomultipliers ➢
Reverse-biased array of photodiodes ➢ ➢
Low noise (few Hz in cryo) Excellent charge resolution
SensL MicroFC-60035-SMT 6 × 6 mm package >19,000 microcells
Dark noise characteristics in LN2 at Vbias = 24.5 V
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SiPM Signal Processor (SSP) ➢
150 MHz waveform digitizer ➢
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Argonne Natl. Lab HEP Elec. Group
Resolve fine waveform details ➢ ➢
~3 ns timing resolution 13 μs waveform buffer
D. Whittington - DUNE Photon Detection - LIDINE 2015
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Design Tests in LAr at Fermilab ➢
“TallBo” facility at FNAL ➢
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Ultra-high purity liquid argon ➢ ➢
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Vacuum to remove residual atmosphere Condenser to maintain closed system
Multiple lightguide designs ➢ ➢ ➢ ➢
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84” LAr dewar
Dip-coated acrylic bars WLS fibers w/ TPB-coated acrylic radiator WLS fibers in TPB-coated acrylic panel WLS bar w/ TPB-coated radiator plates (Summer 2015)
Hodoscope (cosmic ray) trigger ➢
2 8x8 Arrays of PMTs + BaF2 crystals ➢
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CREST cosmic-ray balloon exp't.
2 scintillator paddle planes ➢
Allows shower rejection, reconstruction of single tracks
D. Whittington - DUNE Photon Detection - LIDINE 2015
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Technologies and Phase 1 vs Phase 2 ➢
Run divided into two LAr fills (“phase 1” and “phase 2”)
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Only tracks passing “in front” of the paddles selected ➢ ➢
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Simplify comparisons (several one-sided light guides in phase 2) Reject any tracks passing through a light guide
Data taken with hodoscopes positioned at two heights ➢
“high”
and
D. Whittington - DUNE Photon Detection - LIDINE 2015
“low”
track selections
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Preliminary Performance Results from Phase 1 Designs ➢
Ensemble of signals from “high” selection versus “low” selection WLS Fibers + TPB Radiator
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Minimal attenuation loss
WLS fibers in TPB-coated panel ➢
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TPB Dip-Coated Acrylic
WLS fibers + TPB radiator ➢
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WLS Fibers in TPB-Coated Panel
Minimal attenuation loss (sum of signal at both ends)
TPB dip-coated acrylic bars ➢ ➢
Brightest at readout end Most substantial attenuation loss
D. Whittington - DUNE Photon Detection - LIDINE 2015
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Baseline Design Comparisons (Phase 1 vs Phase 2) ➢
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Ensemble of signals from “high” selection versus “low” selection TPB Dip-Coated Acrylic (3 Bars)
TPB Dip-Coated Acrylic (1 Bar)
TPB Dip-Coated Acrylic (1 Bar)
3 bars – 9 SiPMs
1 bar – 3 SiPMs
1 bar – 3 SiPMs
Extrapolate mean response from phase 1 to phase 2 ➢ ➢ ➢
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Comparable track selections and contamination levels Expect ~25 PE mean response (in right two plots) Measure substantially less
Likely seeing variability in manufacturing results ➢ ➢
Known issue, experienced many times with this technique Identical procedures → wide range of performance
D. Whittington - DUNE Photon Detection - LIDINE 2015
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Preliminary Performance Results from Phase 2 Designs ➢
Three example double-sided designs (same track selections) WLS PVT + TPB Acrylic Plates
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WLS PS + TPB Acrylic Plates
Alternate design (WLS bar + TPB plates) improves on baseline design ➢ ➢ ➢
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Dip-Coated Acrylic (New MIT Recipe)
Factor of 2 better than baseline (phase 1) Factor of 8-10 better than baseline (phase 2) Substantially improved attenuation
New dip-coating recipe from MIT improves even further ➢ ➢
Almost a factor of 2 more sensitive than alternate Substantially improved attenuation
D. Whittington - DUNE Photon Detection - LIDINE 2015
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Efficiency from Data-Simulation Comparison (In Progress) ➢
Signals from example hodoscope trajectory (Fall 2014)
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Data: integrated charge in 10 us waveform [PE]
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Sim: number of incident photons from the line source (toy MC)
SiPM
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Estimated detector efficiency ➢
Ratio = [ Mean #γ Detected (data) ] / [ Mean #γ Incident (sim) ]
D. Whittington - DUNE Photon Detection - LIDINE 2015
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Scintillation Structure Analysis ➢
Time structure of signal at SiPM ➢
Deconvolve average waveform from cosmic rays using measured single-PE response (dark noise) SiPM Response to Cosmic Ray Signals SiPM Response to Dark Noise
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Deviation from simple double-exponential in intermediate (~100 ns) and late (> 7 μs) times
Deconvolved Signal at SiPM
Important to understand for timing resolution and pulseshape discrimination
D. Whittington - DUNE Photon Detection - LIDINE 2015
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Scintillation Structure Analysis ➢
Three- or four-component models capture all features ➢
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Consistent result for prompt singlet signal (~25%) and 1.5 μs “late light” Evidence for long (~7 μs) component in acrylic light guides (not present in polystyrene)
Alternative model treats intermediate and long components as instrumental ➢
Deconvolved Signal at SiPM w/ 4-Component Fit
Deconvolved Signal at SiPM w/ Alternate Model
e.g. non-exponential tail in emission from WLS+plastic Results still consistent among light guides Lifetimes unchanged Singlet signal 34-39% of total
Publication in preparation
D. Whittington - DUNE Photon Detection - LIDINE 2015
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Scintillation Signal from Xenon-Doped Liquid Argon ➢
Injected xenon into the liquid argon ➢ ➢ ➢
GXe mixed with GAr, heated, and injected into the liquid at ~150 psi Increments of 20 ppm (by volume) Time structure determined using same deconvolution procedure Time-dependent structure of the LAr+Xe signal
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Cumulative scintillation signal from LAr+Xe
Prompt signal diminished 1.5 μs tail replaced by broad signal at ~150 ns (20 ppmv) Broad signal becomes more prompt as concentration increases
D. Whittington - DUNE Photon Detection - LIDINE 2015
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Conclusions ➢
Lots of progress developing a light guide photon detector for the DUNE LAr TPC Variety of designs have been explored Successful performance comparison tests SiPM readout quite promising for LAr operation Several TPC+PD tests on the horizon
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Big effort with thanks to many folks ➢
Indiana U. ●
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Louisiana State U. ●
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Janet Conrad, Matt Toups, Taritree Wongjirad, Len Bugel
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Norm Buchanan, Dave Warner, Dylan Adams, Jay Jablonski, Tom Cummings, Forrest Craft, Andrea Shacklock
D. Whittington - DUNE Photon Detection - LIDINE 2015
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Gary Drake, Patrick De Lurgio, Andrew Kreps, Michael Oberling, John T. Anderson, Zelimir Djurcic, Himansu Sahoo, Victor Guarino
Fermilab ●
Colorado State U.
Thomas Kutter, Jonathan Insler
Argonne Natl. Lab
MIT ●
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Stuart Mufson, Jim Musser, Jon Urheim, Mark Gebhard, Brice Adams, Mike Lang, Brian Baugh, Paul Smith, Bryan Martin, Bruce Howard, Jonathon Lowery
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Brian Rebel, Stephen Pordes, Marvin Johnson, Ron Davis, Bill Miner, Michael Geynisman
(And many others!) 28 August 2015
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Backup
D. Whittington - DUNE Photon Detection - LIDINE 2015
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LAr Scintillation in a DUNE Single-Phase TPC
Scintillation from de-excitation of argon molecular state ➢
128 nm UV, two components ➢ ➢
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Prompt (singlet state) signal (τ ~ 6 ns) Slow (triplet state) signal (τ ~ 1.5 μs)
Photon signal gives t0 for transverse position determination ➢
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Calculate drift distance from time of arrival and known drift velocity in TPC E-field Resolution of < 100 ns easily attainable
14.4 m
12 m
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3.6 m 58 m Steel Steel Cryostat Cryostat
Important for non-beam events ➢ ➢ ➢ ➢
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Proton decay events Atmospheric neutrinos Supernova burst neutrinos Cosmic ray rejection
Electron energy resolution
SN burst neutrino spectrum
Resolution (%)
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Particle identification/discrimination ➢
Ratio of prompt to total light depends on ionization density of track
D. Whittington - DUNE Photon Detection - DPF 2015
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Continuing Photon Detector R&D ➢
DUNE Far Detector simulation development (ongoing)
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Current TallBo testing (summer 2015) ➢
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Direct comparisons of baseline design with all four alternatives
35-ton Phase 2 (winter 2015) ➢
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Estimate sensitivity of various photon detector system configurations to physics events (proton decay, SN, etc.)
Visibility
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First test of light guide photon detectors in APA coupled with single-phase TPC
CERN single-phase TPC prototype (2018) ➢ ➢ ➢
Down-selected photon detector design deployed in single-phase TPC New charged particle beam in CERN north area Comparisons to WA105 dual-phase TPC performance
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