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Demonstration of CRAB-Optical TPC at 10 bar Gas Xenon

(Nov 29 2022)

İlker Parmaksiz

University of Texas at Arlington

Supervisors:

  • Dr. Benjamin Jones
  • Dr. Jonathan Asaadi
  • Dr. David Nygren

Contributors:

  • Nicholas Byrnes (Graduate ) (UTA)
  • Dr. Leslie Rogers (ANL)
  • Jackie Baeza Rubio (Undergraduate) (UTA)
  • Ivana Moya (Undergraduate) (UTA)
  • Philip Oyedele (Master) (UTEP)
  • Dr. Corey Adams (ANL)

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Overview

  • Introduction
  • S1/S2 Light Yield Estimation Results
  • Direct Track Observation.
  • Conclusion and summary

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Neutrinoless Double Beta Decay

  • Observing this radioactive decay very crucial because
  • Proves Majorana nature of neutrinos
  • First violation of lepton number conservation.
  • Could Help to measure neutrino mass

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The Concept of NexT

  • Neutrinoless Double Be
  • High Pressure Xenon
  • Optical TPC with an electroluminescent region that converts Ionization electrons into photons with wavelength of 172 nm
  • Has energy reconstruction and tracking capabilities.

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CRAB0 Detector Layout

  • Hamamatsu imagem X2 EMCCD
  • Image Intensifier
  • Optical TPC
  • Hamamatsu UV Sensitive PMT
  • 2 Lens
    • Objective Lens (LENS 1)
    • MgF2 Lens (UV Sensitive) (LENS2)

EMCCD

II

MgF2 LENS

MgF Window

PMT

Optical TPC

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Hamamatsu imagem X2 EMCCD Camera

  • Electron-Multiplying CCDs
    • Photoelectric effect
    • Silicon Pixel Arrays
    • Charge Accumulated in each pixel
    • This charge further amplified by Impact Ionization
  • Single Photon Sensitivity
  • 1076 frames/s (max)
  • 90% QE
  • 2D Tracking

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Photonics Image Intensifier

  • Photoelectric effect
  • Electron drifts to Dual-MCP and collides�with chevron shaped dynodes result in�secondary electrons.
  • Multiplied Photo electrons�strikes the phosphor screen�and emits light at 520 nm.
  • Gain of 10^6
    • Vis-Photons / UV-Photons
  • 25% to 30 % QE

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Photonics UV- Sensitive II

Working Principle Of Image Intensifier

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Optical TPC

  • About 27 cm long
  • Aluminum Field Shaping Rings
    • 8.6 cm diameter
  • ½ inch PEEK Rod Spacers.
  • 1G Ohm Ohmite Resistors
  • 7mm EL-Gap

COMSOL: Optical TPC Electrical Potential

Optical TPC

Voltages

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How Detector Works

  • Charged Particles that pass through high pressure xenon both ionize and excites the medium.
  • Initial interaction results in ionization electrons and scintillation,S1 light to be produced
  • Ionization Electrons drift to EL-region and gain enough energy to excite Xenon atoms and results in S2 with a gain of 648 photons / electron at 10 bar and with a EL-gap of 0.7 cm.

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Light Yield Characterization Setup

  • Estimating light yields on cathode and anode windows.
  • Used Pb-210 Needle Source
  • Replaced Image Intensifier with UV Sensitive PMT.
  • 2 UV Sensitive PMTs
    • The one closer to the EL-Region (Anode Window)
    • The on other one farther away from EL-Region (Cathode Window)
  • 2 Sets of Data Collected
    • Before Purification
    • After Purification
    • 3 runs of 5 min data collected for each set using Multi Stage Trigger which assumes existence of S1 and S2 signals on both PMTs.

Pb-210 Decay Chain

Light Yield Characterization Setup

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Light Yield Estimation

  • Select an Integration Window Region
  • Get the DC offset by obtaining the mean outside of this window region
  • Subtract this mean from each point �In the integration window
  • Integrate and histogram
  • Repeat it for S2 and S1 pulses.

Results

Single Pulse Analysis

Integration Window

DC Offset Estimation

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GEANT4

  • NEXUS based GEANT4 Simulation
  • Simple CRAB-0 geometry is constructed.
    • Cylindrical Stainless Steel Geometry
    • No Field Shaping rings.
    • No Mesh.
    • Pb-210 Needle Source.
      • Assumed cylindrical geometry.
    • Two PMTs Added.
  • 20% surface reflection on metal surfaces.
  • Ionization Electron Clustering, Drift, and Electroluminescence tools are used from NEXUS
  • EL-Yield
    • 648 photons / electron at 10 bar with 7 mm gap

CRAB0

MgF2 Window

Needle Source

Optical Photons

Alphas

Ionization Electrons

PMT

PMT

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GEANT4 Simulation Results

  • Absorbed Photons are obtained from each photocathode
    • Photons from 5.3 MeV Alphas
    • Photons from 1.1 MeV Betas
  • Hamamatsu suggested QEs applied
  • Estimated S1 and S2 Light yields are compared to Simulated GEANT4 results

GEANT4 and Data Comparison

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Track Image Capturing

  • Collimated Pb-210 Needle Source.
  • Images collected for tracks and background
  • Captured images
    • Before Purification
    • After Purification

Track Imaging Setup

Raw Track Images

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Generalized Wiener Filter

  • Data Driven Filter
  • Reduces the common background noise.
  • Power Spectrum is obtained by taking the FFT, then taking absolute value of the FFT and squaring it.
  • S_ij is signal background power spectrum
  • B_ij is the background power spectrum
  • Constructed two wiener filters
    • 2D Wiener filter
    • 1D Wiener filter

Wiener Filter

Observed Track Power Spectrum

For one image each

For All the Images

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Constructing 2D Wiener Filter

  • Average Power Spectrum for track and background images computed.
  • Due to offset between background and signal. We normalized the background by taking the mean of the circular regions in the data and background, and obtaining ratio of them. Then multiply it with background.
  • Using the equation from previous background. We constructed wiener filter.
  • In 2D illustration of the wiener filter , darker regions are suppressed.
  • Apply filter by
    • Taking the FFT of observed image
    • Perform element wise multiplication with Wiener filter.
    • Take the inverse FFT of the result.
    • Keep the real values, and image it.

Average Signal and Background Images

Demonstration of 2D Wiener filter.

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1D Wiener Filter

  • Using the 2D background and�signal power spectrum , 1D power spectrum is computed by �a method called radial averaging
    • By obtaining the mean of the data points between, two concentric circles with radius k, and k+1
    • Then k incremented by 1 until N/2
    • Results in 1D array.
  • Radially distribute the filter in to �a similar layout of the observed �images.
    • This results in multidimensional array �With wiener 1D wiener filter information.
  • Apply the filter the same way of 2D �Wiener filter.

1D Power Spectrum 1D Wiener Filter

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Beta Track

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Alpha Track

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GEANT4 Simulated Alpa Track

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GEANT4 Simulated Beta Track

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Conclusion and Summary

  • Detecting neutrinoless double beta decay will open up more clues in the journey of understanding universe.
  • CRAB-0 successfully demonstrated that directly imaging scintillation light is possible with UV sensitive imaging Intensifier in High Pressure Xenon.

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Final Remarks

  • CRAB-0 paper will be published this month.
  • More exciting measurements are on the way such as diffusion measurements.
  • Next CRAB is getting ready to take observe 3D tracks using TimePix3 Camera.

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Thank you for your attention!

Any Questions?

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Backup Slides

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TimePix3 Camera

  • An optical sensor bump bonded to �a TimePix3 ASIC with a SPIDR readout�Board.
    • 256x256 pixels
    • 55umx55um pixel size
    • 90 % QE at 420 nm
    • Single Photon Sensitivity
  • Asynchronous hit based data driven readout
    • Adjustable threshold
    • 80 MHits/s
    • External Time Stamps with 200ps resolution.
    • 3D Raw Data
      • X and Y position of pixels
      • Time of Arrival (TOA)
        • 1.6 ns time resolution
    • Time Over Threshold (TOT) (Calorimetry)
      • 10 bit resolution
        • 2^10=1024 ADU (Max)
      • The length of time for which the charge remained over threshold.

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