Photon Detection System (PDS) and SN triggering Pierre Lasorak 1 - PowerPoint PPT Presentation

Photon Detection System (PDS) and SN triggering Pierre Lasorak 1

Introduction Outline • Introduction • Final aim: • What to expect from the PDS for SN triggering? • Can we motivate from SN/DAQ point of view? • Addition of reflective foil on the cathode • Use of ARAPUCA / higher efficiency/granularity PDS • Photon detection in LAr • PDS hit level information • Clustering • Results • Other info: • MCC10 SN samples and geometry: 
 snb_timedep_dune10kt_1x2x6_snb_timedep_bkg_reco • Using Jason’s photon backtracker after recent fix (28th June) Pierre Lasorak 2 24/07/2018

Introduction Photon detection in LAr • LAr scintillation, 2 components: e- Ar Ar 2 + 128 nm Recombination • Fast light from singlet Ar 2* state 35% 65% 7 ns Ar Ar Ar 2 * ar Ar+ • Slow light from triplet state (singlet) This photon signal e- event time t 0 for et 1.6 μs μ- reconstruction. 50% Ar 2 * Ar* The ratio of con 50% (triplet) s and from the two com Ar Self-Trapped th depends on βγ and can ai Exciton D. Whittington in particle identi Neutrino 2014 poster Fast Component τ ≈ 8 ns (29%) Intermediate Component τ ≈ 140 ns (8%) • Effect of HV, Slow Component τ ≈ 1.6 μ s (63%) Photoelectrons impurities can change (marginally?) the timing of the TallBo measurement different components. D. Whittington Neutrino 2014 poster Time [μs] Pierre Lasorak 3 24/07/2018

Event Displays (Time and Space) Timing Timing Other (not BT) SN ν 2.4 n Hits APA energy: 12.5 MeV nHit: 8 ν 2.2 CPA • LArSoft event (full drift 
 Ar39 2 X: 116.7 Y: -431.0 Z: 1198.2 Neutron window) 1.8 Krypton Polonium 1.6 Radon • Hit time distribution: 1.4 Ar42 AllBackground 1.2 • Arrow: true time of generation All 1 0.8 • Histogram: timing of the optical hits 0.6 0.4 0.2 0 − 4 − 2 0 2 4 6 8 10 • Hit spatial distribution: Time [ s] µ SN SN ν ν • Pink line: wire hits backtracked to SN 𝜉 800 Y Position [cm] N opt hits: 16 N wire hits: 6 4 600 • Overlaid histogram: optical hits in the PDS backtracked to 3.5 SN 𝜉 400 3 200 2.5 • 10 scintillation bars / APA 0 2 • Red cross: true neutrino interaction position 200 − 1.5 All All 800 Y Position [cm] 400 − N opt hits: 1293 N wire hits: 386 1 35 600 30 600 − 0.5 400 energy: 24.6 MeV X Position: 232 cm ν 25 … With all the hits: 200 20 − 800 0 0 200 400 600 800 1000 1200 0 Z Position [cm] 15 200 − 10 − 400 5 − 600 ν energy: 24.6 MeV X Position: 232 cm − 800 0 0 200 400 600 800 1000 1200 Z Position [cm] Pierre Lasorak 4 24/07/2018

Hit level Information • Full drift window Photon ~1k events Wire • OpHit • Unmatched hits: noise, 
 dark current Number of hits per drift window nEvent 3 10 2 10 Other (not BT) 10 SN ν APA CPA Ar39 Neutron Krypton 1 Polonium Radon Ar42 AllBackground All 1 − 10 3 1 2 − 10 1 10 10 10 nHit Pierre Lasorak 5 24/07/2018

Hit level information Signal features • Efficiency: 1 or more optical hits from SN / N events one or more hit collection efficiency nHit / Event Drops the further CPA CPA • 1 45 you get from the 40 0.9 35 APA 30 0.8 25 0.7 Number of hits 20 • 15 0.6 scales linearly 10 0.5 with E 𝜉 APA 5 0 0 5 10 15 20 25 30 35 40 − 400 − 300 − 200 − 100 0 100 200 300 400 Energy [MeV] ν X position [cm] h_timing_relat one or more hit collection efficiency Top N optical hits Bottom Entries 17332 1 First hit + other 
 Edge effect, • Mean 1.149 0.25 Std Dev 1.349 fast light hits photons escape 0.95 0.2 0.9 0.15 Other 
 0.85 0.1 slow light hits 0.8 0.05 0.75 0 600 400 200 0 200 400 600 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 − − − Y position [cm] Time [ µ s] Pierre Lasorak 6 24/07/2018

Clustering • I went ahead and clustered optical hits: Fraction of hits 1 • Reused the code from Alex Booth: • Timing: 800 ns (maybe too small wrt the simulations) 0.8 • Z position: 300 cm (1 APA) 0.6 • No Y clustering • Composition of the clusters: 0.4 • Biggest contributor of hit to tag as SN or not. 0.2 • Neutron is still the worst background • Background contributions are more evenly spread out → Pile up 0 0 1 2 3 4 5 6 7 8 9 10 is important! (Unlike for wire cluster where the main contributor Time [ s] µ is neutrons) average number of hits in cluster 10 signal optical clusters 1 background optical clusters − 1 10 Krypton AllBackground Other SNnu APA CPA Ar39 Neutron Polonium Radon Ar42 All Pierre Lasorak 7 24/07/2018

Cluster properties h_ncluster_sign_opti • Splitting the SN events! Events Entries 1874 3 10 Mean 1.231 Std Dev 0.7394 • First pass, still trying to get better at clustering time properly. 2 10 • Number of background clusters is large without cuts 10 signal optical clusters 1 background optical clusters − 1 10 2 3 1 10 10 10 n clusters nClusters / Drift Windows 12m clusters!! Something smarter ~ Size of the 1x2x6 has to be done for the time → not appropriate for these studies h_width_sign_opti h_ywidth_sign_opti 5 10 Clusters Clusters Clusters Entries 2306 Entries 2306 Mean 489.2 Mean 545.8 5 10 5 10 Std Dev 321.3 Std Dev 297.6 4 10 4 10 4 10 3 10 3 10 3 10 2 10 2 10 2 10 10 10 10 1 1 1 − 1 − 1 − 1 10 10 10 0 200 400 600 800 1000 1200 0 200 400 600 800 1000 1200 1400 0 1 2 3 4 5 6 7 8 9 10 Z Width [cm] Y Width [cm] Time Width [ s] µ Pierre Lasorak 8 24/07/2018

Clustering Efficiency • Clustering efficiency (no cut) 1 • Nhit (and n PEs) can be used to suppress 0.8 backgrounds 0.6 • Next: use 10, 12, 15, 17 hits as cut (still missing stats to go further) 0.4 0.2 0 h_nhit_sign_opti 5 10 15 20 25 30 Clusters E ν [MeV] Entries 2306 Mean 13.61 5 10 Std Dev 13.34 signal optical clusters h_npe_sign_opti 4 10 Clusters Entries 2307 5 10 Mean 10.17 Std Dev 6.979 3 background optical clusters 10 4 10 3 2 10 10 2 10 10 10 1 1 − 1 10 0 10 20 30 40 50 60 70 80 90 1 − 10 0 2 4 6 8 10 12 14 16 18 20 n Hits n PEs Pierre Lasorak 9 24/07/2018

Results Number of Clusters in Time Window Required to Trigger vs. Trigger Rate Individual Marley Eff & 10kt Bkgd Rate Trigger Rate, (Hz) 2 10 10 Optical Custers (nHit>= 10): - Eff: 0.57 & Bkgd rate: 100.05 Hz (5 s timing window) 1 − 1 10 Optical Custers (nHit>= 12): - Eff: 0.51 & Bkgd rate: 25.48 Hz (5 s timing window) − 2 10 − 3 10 Optical Custers (nHit>= 15): - Eff: 0.43 & Bkgd rate: 1.85 Hz (5 s timing window) − 4 10 1/Day 5 − 10 Optical Custers (nHit>= 17): - Eff: 0.38 & Bkgd rate: 0.93 Hz (5 s timing window) 1/Week − 6 10 1/Month − 7 10 Wire Clusters - Eff: 0.58 & Bkgd rate: 0.10 Hz (5 s timing window) − 8 10 − 9 10 Wire Clusters - Eff: 0.58 & Bkgd rate: 0.10 Hz (10 s timing window) 2 1 10 10 Number of Clusters/Time Window Galactic Neighbourhood Coverage, Fake Trigger Rate 1/Month Galactic Neighbourhood Coverage, Fake Trigger Rate 1/Month • Use a 5s timing window to count the number of − 1 10 Efficiency x SN Probability clusters • Can trigger on almost all of the milky way using only 2 − 10 PDS info! 3 − 10 • Trying to get to the LMC where you get 10-20 events. − 4 10 − 5 10 0 10 20 30 40 50 SN Distance, (kpc) Pierre Lasorak 10 24/07/2018

Conclusion Future work • First pass at using PDS for SN trigger • Basic simple clustering implemented (needs improvement) • Currently can trigger on Milky Way SN but not on the 20% of SN coming from LMC • 1x2x6 geometry is not really big enough to avoid bias in PDS (light leaks out sides) • Photons travel far → triggering cannot be done so efficiently on the APA level (few APAs at least). • The slow component of the light is important. • Future work • Motivate improved design for the PDS: • Consider the addition of reflective foil on the cathode • More granular/efficient detector can do better? • Combine PDS with wire information at the trigger level? Pierre Lasorak 11 24/07/2018