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Studying the GRAiNITA concept: first test beam results

Sergey Barsuk, Oleg Bezshyyko, Ianina Boiaryntseva, Andrey Boyarintsev, Dominique Breton, Herve Chanal, Alexander M. Dubovik, Larysa Golinka-Bezshyyko, Carlos Dominguez Goncalves, Yingrui Hou, Giulia Hull, Miktat Imre, Denys Klekots, Jacques Lefrancois, Jihane Maalmi, Magali Magne, Bernard Mathon, Stéphane Monteil, Sebastien Olmo, David Picard, Marie-Helene Schune, Irina Tupitsyna, Mykhailo Yeresko

TL;DR

This study tests the GRAiNITA calorimeter concept in a two-day beam run at CERN with a small ZnWO$_4$-grain prototype read out by wavelength-shifting fibres. It develops track-based methods, fibre-response homogenisation, and a dedicated pion-fitting model to quantify non-uniformity effects and extract the stochastic term of the energy resolution. The results indicate a stochastic term near $1\%/\sqrt{E}$ and a non-uniformity constant term of about $0.7$–$0.9\%$, well below $1\%$, validating the calorimetric viability of GRAiNITA and providing essential inputs for scaling to full detectors. Geant4-based modeling confirms the non-uniformity contribution and helps quantify its impact on energy resolution for future module designs.

Abstract

Data collected over a two-day period in June 2024 at the CERN SPS H9 test beam using a small-scale GRAiNITA prototype have been analyzed to characterize the detector's energy resolution performance. The measurements allow for a first estimate of the constant term associated with detector non-uniformity. Although the evaluation is limited by the small prototype size and the use of pion beams, the results indicate that the non-uniformity-related constant term is significantly below 1%. Furthermore, the test-beam data confirm that the contribution to the energy resolution arising from photo-electron statistics is approximately 1%/sqrt(E). These findings validate the expected calorimetric performance of the GRAiNITA concept and provide important input for the design and optimization of future full-scale detectors.

Studying the GRAiNITA concept: first test beam results

TL;DR

This study tests the GRAiNITA calorimeter concept in a two-day beam run at CERN with a small ZnWO-grain prototype read out by wavelength-shifting fibres. It develops track-based methods, fibre-response homogenisation, and a dedicated pion-fitting model to quantify non-uniformity effects and extract the stochastic term of the energy resolution. The results indicate a stochastic term near and a non-uniformity constant term of about –, well below , validating the calorimetric viability of GRAiNITA and providing essential inputs for scaling to full detectors. Geant4-based modeling confirms the non-uniformity contribution and helps quantify its impact on energy resolution for future module designs.

Abstract

Data collected over a two-day period in June 2024 at the CERN SPS H9 test beam using a small-scale GRAiNITA prototype have been analyzed to characterize the detector's energy resolution performance. The measurements allow for a first estimate of the constant term associated with detector non-uniformity. Although the evaluation is limited by the small prototype size and the use of pion beams, the results indicate that the non-uniformity-related constant term is significantly below 1%. Furthermore, the test-beam data confirm that the contribution to the energy resolution arising from photo-electron statistics is approximately 1%/sqrt(E). These findings validate the expected calorimetric performance of the GRAiNITA concept and provide important input for the design and optimization of future full-scale detectors.

Paper Structure

This paper contains 15 sections, 2 equations, 14 figures, 1 table.

Table of Contents

  1. Introduction
  2. Experimental setup
  3. Track reconstruction and checks
  4. Track reconstruction
  5. Preselection and first look at the data
  6. Light confinement
  7. Assessment of the stochastic term of the energy resolution
  8. Analysis framework
  9. Homogenisation of the fibres responses
  10. Design of the pion fitting model
  11. Measurement of the non-uniformity
  12. Design of the virtual units
  13. Determination of the uniformity maps
  14. Impact of the non-uniformity response on the constant term
  15. Conclusion

Figures (14)

  • Figure 1: The 16-channels GRAiNITA prototype (left:real, right:schematic).
  • Figure 2: Schematic view of the test beam setup (left) with a zoom on the DWC arrangement (right).
  • Figure 3: Mean number of photo-electrons par track for the sum of the 16 fibres.
  • Figure 4: Left: average number of photo-electrons for the four most central fibres. Right: evolution of the mean number of photo-electrons with the distance of the track from the fibre centre.
  • Figure 5: Sum of the number of photo-electrons registered on the 16 fibres for tracks in the four quadrants Q0-3 (see figure \ref{['fig:Homogen']}) from fibres 7, 4, 11 and 8. The curve is a Landau distribution convoluted with a Gaussian function. The left plot corresponds to the set-up filled with water and the right plot to the setup filled with the heavy liquid.
  • ...and 9 more figures