Outline 1. Overview of LArIAT 2. The LArIAT Light Collection System - PowerPoint PPT Presentation

Light Collection in LArIAT � DUNE Photon Detection System Meeting � December 17 th , 2015 � � � William Foreman � UChicago � � �

Outline � 1. Overview of LArIAT � 2. The LArIAT Light Collection System � 3. Select ongoing analyses � § LAr purity estimation � § Michel electrons � 4. Perspectives for larger LArTPCs � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 2 �

LArIAT (Liquid Argon In A Testbeam) � § 170L LArTPC (refurbished from ArgoNeuT) in a test beam at Fermilab for R&D, calibration, and physics � 40cm � § Tunable spectrum of particles ( π , p, μ , e) in momentum range relevant to neutrino exp’s � 90cm � § Run 1 data collected Apr 30–July 3, 2015 � 47cm � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 3 �

Fermilab Test Beam Facility LArIAT Tertiary Beamline Linac � Booster � Main Injector � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 4 �

LArIAT’s light collection system (Run I) � SensL MicroFB-60035 
 ETL PMT � SiPM channel w/preamp � D757KFL 
 (2” diameter) � § Side flange on ArgoNeuT cryostat was instrumented to accommodate photodetectors 2-3cm behind wires � § Signals digitized by CAEN Hamamatsu PMT R-11065 (3” diameter) � V1751 (1 GHz sampling) � 2 Hamamatsu S11828-3344M 
 4x4 SiPM arrays, w/preamp � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 5 �

What makes LArIAT unique… � Reflector-based solution 
 Standard LArTPC approach 
 (LArIAT) � (ie, ICARUS, MicroBooNE) � � � TPB-coated plate � γ 
 (128nm) � γ 
 (~430nm) � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 6 �

The reflective foils � § 200 μ g/cm 2 TPB film deposited by vacuum evaporation onto Vikuiti ESR, highly reflective and non- metallic foil (65 μ m thick) made by multilayer polymer technology � § ~95% reflectance to visible light � § ~100% efficiency for VUV wavelength shifting in TPB layer � Reflective foil 
 TPB-coated foils on LArIAT TPC walls � (before TPB evaporative coating) � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 7 �

Benefits of reflector-based approach � Fractional visibility map from MC 
 § Technique adopted from (top-down view of LArIAT TPC) � dark matter experiments � TPB-coated PMT scenario (seeing “direct” light) � § Improved light yield for same X [m] � # of PMTs � § Better uniformity � Z [m] � Bare PMTs, TPB foils on walls (seeing “reflected” light) � X [m] � **actual LArIAT setup** � Z [m] � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 8 �

Ongoing analysis � § Several analyses underway on light signals from LArIAT’s Run I � § Purity estimation � § Michel electron studies � § Calorimetry enhancement � § Particle identification using pulse shape discrimination � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 9 �

Estimating purity from slow scintillation lifetime � Preliminary � WArP Collabora+on arXiv:0804.1217 § Purity of LAr changes lifetime of triplet component in scintillation light � § Average waveform fitted to exponential à resulting lifetime compared with nitrogen sensor � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 10 �

Estimating purity from slow scintillation lifetime � P. Kryczynski � LArIAT data � WArP data- � driven model � § This was done for early data shortly after initial fill while residual N2 was flushed out by continued LAr top-offs (every 4 hours) � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 11 �

Triggering on Michels in LArIAT � § Light system in LArIAT allows for real-time triggering on Michel e’s from stopping cosmic μ ’s � § In LArIAT, ~1Hz rate in cosmic gate (24s following beam spill) � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 12 �

Collected data � § For this analysis, using events obtained during a 
 12-day period � § Optimal trigger configuration � § 14842 subruns 
 (3.8 cumulative days trigger was active) � § ~330k Michel triggers recorded in this timespan � ETL PMT � § ~70k analyzable Michels 
 D757KFL 
 � (2” diameter) � § Analysis presented here uses only ETL PMT � § 20% of total system LY � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 13 �

Waveform reconstruction and integration � Preliminary � 0 � 10 � 28 � 20 � Preliminary � Time [ μ s] � Optical hit finding and integration of 2 nd ( e -candidate) pulses in MICHEL-triggered waveforms � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 14 �

Which bump looks like Michels? � “Decay-like” � LArIAT Raw data � time tick (128ns/pixel) � LArIAT Raw Data � time tick (128ns/pixel) � Scanning by eye… � wires � wires � time tick (128ns/pixel) � LArIAT Raw Data � “Clean” sample: � time tick (128ns/pixel) � LArIAT Raw Data � 80% Michel-like � wires � wires � LArIAT Raw Data � time tick (128ns/pixel) � BG sample: � LArIAT Raw Data � time tick (128ns/pixel) � 13% Michel-like � wires � wires � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 15 �

Muon decay curves � § Quality cuts: � § Michel PE 100ns > 25pe � § μ PE 100ns < 150pe � § τ c = 918 ± 109 ns � § μ - capture fraction ~71% � § Agreement with theory prediction for LAr of 851 ns � § Working to optimize cuts and determine/reduce systematics (result preliminary) � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 16 �

LY estimation using Michel PE spectrum � § Require reconstructed μ -like track that stops in central 15cm-radius sphere � § Using simplified toy MC to predict detected distribution � § LY = 2.8 pe/MeV (for probed region) 
 � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 17 �

Summary � § LArIAT’s Run I successfully demonstrated dark- matter-inspired reflector method for VUV wavelength shifting in a LArTPC � § Analyses of light signals underway � § A standalone toy MC simulation used for preliminary comparisons while fully detailed (G4/ LArSoft-based) simulation being developed � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 18 �

Perspectives from LArIAT � § Reflector-based system offers several potential benefits to larger LArTPCs � § Uniformity of light yield (useful for calorimetry + rare event triggering) � § Improved time resolution � § Also some potential drawbacks… � § Light-based localization not as straight-forward � § Pros and cons need to be systematically studied at MC level (underway in SBND) � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 19 �

Light yield uniformity � § Scintillation essential for triggering on rare or low- Toy simulation in energy events in LarTPCs SBND-sized (supernova ν ’s, proton decay) � LArTPC, 80 3” PMTs � § Uniformity especially 
 important in large, underground detectors � SN neutrino energies � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 20 �

Timing � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 21 �

Localization concerns � How well could a system match an array of photodetector signals to an actual 3D scintillation point or track? (“Flash-finding”) � How does this change in a reflector-based system ? � “Direct” VUV photon � Some preliminary studies using toy MC were done to get “Reflected a better understanding of this.. � visible photon � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 22 �

Photoelectron distribution across sense plane 
 (for point-like scintillation at varying heights ) � 1 � TPC � 1 2 � 2 3 3 � PMT array on this plane � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 23 �

Photoelectron distribution across sense plane 
 (for point-like scintillation at varying heights ) � 1 � TPC � 1 2 � 2 3 3 � PMT array on this plane � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 24 �

Photoelectron distribution on sense plane 
 (for cosmic muon track ) � As seen by VUV-sensitive As seen by visible- (TPB-coated) PMTs sensitive PMTs with 5- w/no reflectors (12.5% QE) wall reflectors (25% QE) TPC � TPB-coated PMTs + reflectors PMT array on this plane � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 25 �

Sampling this distribution with PMTs… � As seen by VUV-sensitive (TPB-coated) PMTs w/no reflectors (12.5% QE) As seen by visible- sensitive PMTs with 5- wall reflectors (25% QE) 12/17/2015 � W. Foreman | DUNE PDS Mtg � 26 �

Sampling this distribution with PMTs… � TPB-coated PMTs + reflectors So is localization still possible? 
 Maybe, but likely with less precision... � Can flash-finding adapt to system that 
 sees both direct/reflected light? � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 27 �

Thank you! � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 28 �

Backup � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 29 �

Improvements for Run II � § Replace HMM PMT (faulty base) � ETL PMT � Hamamatsu PMT 
 D757KFL 
 R-11065 
 § Coincidence of two PMTs will allow a 
 (2” radius) � (3” radius) � more robust trigger � § Configure PMTs for positive polarity (common cathode) � § Additional trigger using a μ “telescope” using existing cosmic paddles � § Catch both through-going and stopping μ without biasing toward Michel decays � μ � μ � Cosmic μ paddle � TPC � 12/17/2015 � W. Foreman | DUNE PDS Mtg � 30 �