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Precision Light Yield and Crosstalk Characterization for the SuperFGD scintillator cubes

I. Alekseev, A. Chvirova, M. Danilov, S. Fedotov, A. Khotjantsev, M. Kolupanova, N. Kozlenko, A. Krapiva, Y. Kudenko, A. Mefodiev, O. Mineev, D. Novinsky, E. Samigullin, N. Skrobova, D. Svirida

TL;DR

This work provides a detailed, beam-tested characterization of a $5\times5\times5$ SuperFGD scintillator-cube prototype to quantify light yield, spatial uniformity, and inter-cube optical crosstalk. Using high-resolution tracking and 0.5~mm granularity, the authors map LY distributions per fiber, normalize to mitigate channel-to-channel variations, and construct average LY maps across 27 cubes. They report LY values on the order of $\sim$50~p.e./fiber per MIP, with up to $\sim$100~p.e. when combining two orthogonal fibers, and crosstalk in the 2–6% range that peaks near cube boundaries. A dedicated photon-level Monte Carlo reproduces the main experimental features, validating the optical model and enabling simulation-driven calibration and reconstruction for the ND280 upgrade.

Abstract

A detailed study of a $5\times5\times5$ cube prototype of the SuperFGD detector was performed using a 730 MeV/$c$ pion beam at the SC-1000 synchrocyclotron (PNPI, Gatchina, Russia). The detector, based on plastic scintillation cubes with orthogonal wavelength-shifting (WLS) fiber readout and silicon photomultipliers (SiPMs), was tested to evaluate its performance in terms of light yield, spatial uniformity, and optical crosstalk. Using high-resolution tracking, the spatial distribution of light yield was mapped with a granularity of 0.5 mm. An average light response map was obtained by combining data from 27 cubes. Optical crosstalk between adjacent cubes was also measured and characterized in four directions (left, right, up, down). Position-dependent crosstalk values ranged from 2% to 6%, with the highest levels observed near cube interfaces. These results confirm the excellent performance and scalability of the SuperFGD design, and provide valuable input for simulation tuning and reconstruction algorithms in the ND280 upgrade of the T2K experiment. The obtained result on the response uniformity and crosstalk are reasonably well described by simple MC model of the setup.

Precision Light Yield and Crosstalk Characterization for the SuperFGD scintillator cubes

TL;DR

This work provides a detailed, beam-tested characterization of a SuperFGD scintillator-cube prototype to quantify light yield, spatial uniformity, and inter-cube optical crosstalk. Using high-resolution tracking and 0.5~mm granularity, the authors map LY distributions per fiber, normalize to mitigate channel-to-channel variations, and construct average LY maps across 27 cubes. They report LY values on the order of 50~p.e./fiber per MIP, with up to 100~p.e. when combining two orthogonal fibers, and crosstalk in the 2–6% range that peaks near cube boundaries. A dedicated photon-level Monte Carlo reproduces the main experimental features, validating the optical model and enabling simulation-driven calibration and reconstruction for the ND280 upgrade.

Abstract

A detailed study of a cube prototype of the SuperFGD detector was performed using a 730 MeV/ pion beam at the SC-1000 synchrocyclotron (PNPI, Gatchina, Russia). The detector, based on plastic scintillation cubes with orthogonal wavelength-shifting (WLS) fiber readout and silicon photomultipliers (SiPMs), was tested to evaluate its performance in terms of light yield, spatial uniformity, and optical crosstalk. Using high-resolution tracking, the spatial distribution of light yield was mapped with a granularity of 0.5 mm. An average light response map was obtained by combining data from 27 cubes. Optical crosstalk between adjacent cubes was also measured and characterized in four directions (left, right, up, down). Position-dependent crosstalk values ranged from 2% to 6%, with the highest levels observed near cube interfaces. These results confirm the excellent performance and scalability of the SuperFGD design, and provide valuable input for simulation tuning and reconstruction algorithms in the ND280 upgrade of the T2K experiment. The obtained result on the response uniformity and crosstalk are reasonably well described by simple MC model of the setup.
Paper Structure (21 sections, 5 equations, 26 figures, 1 table)

This paper contains 21 sections, 5 equations, 26 figures, 1 table.

Table of Contents

  1. Introduction
  2. SuperFGD cubes
  3. Beam tests
  4. Experimental setup
  5. Signal waveform analysis
  6. SiPM calibration
  7. Calculating the position of scintillator cubes
  8. Light Yield from each fiber
  9. Light Yield Distribution Inside Scintillator Cubes
  10. Average Light Yield Distribution Across Multiple Cubes
  11. Consistency Check of Cube Alignment via Light Yield Maps
  12. Position-Dependent Optical Crosstalk Between Cubes
  13. Two-Dimensional Crosstalk Maps
  14. One-Dimensional Crosstalk Maps
  15. Monte Carlo Simulation and Comparison with Data
  16. ...and 6 more sections

Figures (26)

  • Figure 1: Left: readout of 27 WLS fibers by the digitizer; inactive fibers are not shown. Right: top view of the full test setup.
  • Figure 2: Test setup at the pion beam line 1 of the PNPI synchrocyclotron.
  • Figure 3: Examples of digitized SiPM signals. Left: clean single pulse. Right: waveform with afterpulsing or pile up with accidentals.
  • Figure 4: Left: Amplitude vs. integrated charge for calibration events. The diagonal band corresponds to clean single pulses. Right: Off-diagonal events are rejected.
  • Figure 5: Left: Amplitude vs. integrated charge for beam-triggered events. Right: A looser selection is applied.
  • ...and 21 more figures