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

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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

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SLIDE 1

Light Collection in LArIAT

DUNE Photon Detection System Meeting December 17th, 2015

  • William Foreman

UChicago

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SLIDE 2

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

2 12/17/2015

  • W. Foreman | DUNE PDS Mtg
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SLIDE 3

LArIAT (Liquid Argon In A Testbeam)

§ 170L LArTPC (refurbished from ArgoNeuT) in a test beam at Fermilab for R&D, calibration, and physics § Tunable spectrum of particles (π, p, μ, e) in momentum range relevant to neutrino exp’s § Run 1 data collected Apr 30–July 3, 2015

47cm 40cm 90cm

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SLIDE 4

4 Linac Booster

Main Injector

Fermilab Test Beam Facility LArIAT Tertiary Beamline

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  • W. Foreman | DUNE PDS Mtg
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SLIDE 5

LArIAT’s light collection system (Run I)

Hamamatsu PMT R-11065 (3” diameter) ETL PMT D757KFL 
 (2” diameter) 2 Hamamatsu S11828-3344M 
 4x4 SiPM arrays, w/preamp SensL MicroFB-60035 
 SiPM channel w/preamp

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§ Side flange on ArgoNeuT cryostat was instrumented to accommodate photodetectors 2-3cm behind wires § Signals digitized by CAEN V1751 (1 GHz sampling)

12/17/2015

  • W. Foreman | DUNE PDS Mtg
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SLIDE 6

What makes LArIAT unique…

Standard LArTPC approach 
 (ie, ICARUS, MicroBooNE)

  • γ 


(128nm) γ 
 (~430nm)

TPB-coated plate

Reflector-based solution 
 (LArIAT)

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SLIDE 7

The reflective foils

§ 200 μg/cm2 TPB film deposited by vacuum evaporation onto Vikuiti ESR, highly reflective and non- metallic foil (65 μm thick) made by multilayer polymer technology

§ ~95% reflectance to visible light § ~100% efficiency for VUV wavelength shifting in TPB layer

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Reflective foil
 (before TPB evaporative coating) TPB-coated foils on LArIAT TPC walls

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  • W. Foreman | DUNE PDS Mtg
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SLIDE 8

Benefits of reflector-based approach

§ Technique adopted from dark matter experiments

§ Improved light yield for same # of PMTs § Better uniformity

Fractional visibility map from MC 
 (top-down view of LArIAT TPC)

TPB-coated PMT scenario (seeing “direct” light) Bare PMTs, TPB foils on walls (seeing “reflected” light) X [m] X [m] Z [m] Z [m]

**actual LArIAT setup**

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  • W. Foreman | DUNE PDS Mtg
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SLIDE 9

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

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SLIDE 10

Estimating purity from slow scintillation lifetime

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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

Preliminary

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SLIDE 11

Estimating purity from slow scintillation lifetime

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§ This was done for early data shortly after initial fill while residual N2 was flushed out by continued LAr top-offs (every 4 hours)

WArP data- driven model LArIAT data

  • P. Kryczynski

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  • W. Foreman | DUNE PDS Mtg
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SLIDE 12

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)

  • W. Foreman | DUNE PDS Mtg

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SLIDE 13

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

§ ~70k analyzable Michels


  • § Analysis presented here

uses only ETL PMT

§ 20% of total system LY

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ETL PMT D757KFL 
 (2” diameter)

12/17/2015

  • W. Foreman | DUNE PDS Mtg
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SLIDE 14

Optical hit finding and integration of 2nd (e-candidate) pulses in MICHEL-triggered waveforms

Waveform reconstruction and integration

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10 20 28 Time [μs]

Preliminary Preliminary

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SLIDE 15

Which bump looks like Michels?

Scanning by eye… BG sample: 13% Michel-like “Clean” sample: 80% Michel-like

wires time tick (128ns/pixel) wires time tick (128ns/pixel) wires time tick (128ns/pixel) wires time tick (128ns/pixel) wires time tick (128ns/pixel) wires time tick (128ns/pixel)

LArIAT Raw data LArIAT Raw Data LArIAT Raw Data LArIAT Raw Data LArIAT Raw Data LArIAT Raw Data

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“Decay-like”

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  • W. Foreman | DUNE PDS Mtg
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SLIDE 16

Muon decay curves

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§ Quality cuts:

§ Michel PE100ns > 25pe § μ PE100ns < 150pe

§ τc = 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)

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  • W. Foreman | DUNE PDS Mtg
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SLIDE 17

LY estimation using Michel PE spectrum

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§ 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
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SLIDE 18

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

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SLIDE 19

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)

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  • W. Foreman | DUNE PDS Mtg
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SLIDE 20

SN neutrino energies

Light yield uniformity

§ Scintillation essential for triggering on rare or low- energy events in LarTPCs (supernova ν’s, proton decay) § Uniformity especially
 important in large, underground detectors

  • W. Foreman | DUNE PDS Mtg

Toy simulation in SBND-sized LArTPC, 80 3” PMTs

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SLIDE 21

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Timing

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  • W. Foreman | DUNE PDS Mtg
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SLIDE 22

Localization concerns

How well could a system match an array of photodetector signals to an actual 3D scintillation point or track? (“Flash-finding”)

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How does this change in a reflector-based system? Some preliminary studies using toy MC were done to get a better understanding of this..

“Direct” VUV photon “Reflected visible photon

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  • W. Foreman | DUNE PDS Mtg
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SLIDE 23

Photoelectron distribution across sense plane 
 (for point-like scintillation at varying heights)

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TPC PMT array on this plane 1 2 3 1 2 3

12/17/2015

  • W. Foreman | DUNE PDS Mtg
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SLIDE 24

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Photoelectron distribution across sense plane 
 (for point-like scintillation at varying heights)

1 2 3 TPC PMT array on this plane 1 2 3

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  • W. Foreman | DUNE PDS Mtg
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SLIDE 25

Photoelectron distribution on sense plane 
 (for cosmic muon track)

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TPC PMT array on this plane

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)

TPB-coated PMTs + reflectors

12/17/2015

  • W. Foreman | DUNE PDS Mtg
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SLIDE 26

Sampling this distribution with PMTs…

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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
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SLIDE 27

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So is localization still possible? 
 Maybe, but likely with less precision... Can flash-finding adapt to system that 
 sees both direct/reflected light?

TPB-coated PMTs + reflectors

Sampling this distribution with PMTs…

12/17/2015

  • W. Foreman | DUNE PDS Mtg
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SLIDE 28

Thank you!

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  • W. Foreman | DUNE PDS Mtg
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SLIDE 29

Backup

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SLIDE 30

Improvements for Run II

§ Replace HMM PMT (faulty base)

§ Coincidence of two PMTs will allow a 
 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

30 Hamamatsu PMT
 R-11065
 (3” radius) ETL PMT D757KFL 
 (2” radius)

TPC Cosmic μ paddle μ μ

12/17/2015

  • W. Foreman | DUNE PDS Mtg
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SLIDE 31

The LArIAT light collection components (Run I)

Hamamatsu PMT
 R-11065
 (3” radius) ETL PMT D757KFL 
 (2” radius) SensL MicroFB-60035 
 w/preamp Hamamatsu S11828-3344M, 4x4 array, w/preamp

Two cryogenic PMTs

  • Three silicon

photomultipliers (SiPMs) on custom preamp boards.

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SLIDE 32

Charge distributions at sense plane (track-like, varying depths)

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20cm from PMTs 100cm from PMTs 180cm from PMTs

  • W. Foreman | DUNE PDS Mtg