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Demonstration of Sub-Percent Energy Resolution in the NEXT-100 Detector

NEXT Collaboration, M. Pérez Maneiro, M. Martínez-Vara, S. Torelli, G. Martínez-Lema, P. Novella, J. A. Hernando Morata, J. J. Gómez-Cadenas, C. Adams, H. Almazán, V. Álvarez, A. I. Aranburu, L. Arazi, I. J. Arnquist, F. Auria-Luna, S. Ayet, Y. Ayyad, C. D. R. Azevedo, K. Bailey, F. Ballester, J. E. Barcelon, M. del Barrio-Torregrosa, A. Bayo, J. M. Benlloch-Rodríguez, F. I. G. M. Borges, A. Brodoline, N. Byrnes, A. Castillo, E. Church, L. Cid, M. Cid, X. Cid, C. A. N. Conde, C. Cortes-Parra, F. P. Cossío, R. Coupe, E. Dey, P. Dietz, C. Echeverria, M. Elorza, R. Esteve, R. Felkai, L. M. P. Fernandes, P. Ferrario, F. W. Foss, Z. Freixa, J. García-Barrena, J. W. R. Grocott, R. Guenette, J. Hauptman, C. A. O. Henriques, P. Herrero-Gómez, V. Herrero, C. Hervés Carrete, Y. Ifergan, A. F. B. Isabel, B. J. P. Jones, F. Kellerer, L. Larizgoitia, A. Larumbe, P. Lebrun, F. Lopez, N. López-March, R. Madigan, R. D. P. Mano, A. Marauri, A. P. Marques, J. Martín-Albo, A. Martínez, R. L. Miller, K. Mistry, J. Molina-Canteras, F. Monrabal, C. M. B. Monteiro, F. J. Mora, K. E. Navarro, D. R. Nygren, E. Oblak, J. Palacio, B. Palmeiro, A. Para, I. Parmaksiz, A. Pazos, J. Pelegrin, M. Querol, J. Renner, I. Rivilla, C. Rogero, L. Rogers, B. Romeo, C. Romo-Luque, E. Ruiz-Chóliz, P. Saharia, F. P. Santos, J. M. F. dos Santos, M. Seemann, I. Shomroni, A. L. M. Silva, P. A. O. C. Silva, A. Simón, S. R. Soleti, M. Sorel, J. Soto-Oton, J. M. R. Teixeira, S. Teruel-Pardo, J. F. Toledo, C. Tonnelé, J. Torrent, A. Trettin, P. R. G. Valle, M. Vanga, P. Vázquez Cabaleiro, J. F. C. A. Veloso, J. D. Villamil, J. Waiton, A. Yubero-Navarro

TL;DR

NEXT-100 demonstrates sub-percent energy resolution near the Xe-136 double-beta decay $Q$-value using a high-pressure xenon electroluminescent TPC. The study conducts a Th-228 high-energy calibration and Kr-83m mapping to achieve a linear response and an energy resolution of $R(Q_{\beta\beta})=(0.93 \pm 0.02)\%$ FWHM$, extrapolated from $R(2615~\mathrm{keV})=(0.90 \pm 0.02)\%$ FWHM. Through geometry and lifetime corrections, 3D light-response mapping, and a single-track selection, the authors refine the energy measurement to the same sub-percent precision at $Q_{\beta\beta}$, surpassing the design goal. These results validate NEXT-100's capability for precision energy measurements in $\beta\beta0\nu$ searches and bolster its scientific reach.

Abstract

NEXT-100 is a high-pressure xenon time projection chamber with electroluminescent amplification, designed to operate with up to approximately 70.5 kg at 13.5 bar. It is the most recent detector developed by the NEXT collaboration to search for the neutrinoless double-beta decay ($ββ0ν$) of Xe-136. The NEXT gas TPC technology offers the best energy resolution near the Q-value of the decay ($Q_{ββ}$ = 2458 keV) among xenon detectors, which is set by design to be <1% FWHM. We report here the high-energy calibration of the detector using a Th-228 source, demonstrating linear response and an energy resolution of $(0.90 \pm 0.02)$% FWHM at the Tl-208 photopeak (2615 keV). This performance extrapolates to a resolution at the double-beta decay end-point of $R(Q_{ββ})$ = $(0.93 \pm 0.02)$% FWHM, confirming the detector's capability for precision energy measurement in the search for $ββ0ν$.

Demonstration of Sub-Percent Energy Resolution in the NEXT-100 Detector

TL;DR

NEXT-100 demonstrates sub-percent energy resolution near the Xe-136 double-beta decay -value using a high-pressure xenon electroluminescent TPC. The study conducts a Th-228 high-energy calibration and Kr-83m mapping to achieve a linear response and an energy resolution of FWHMR(2615~\mathrm{keV})=(0.90 \pm 0.02)\%Q_{\beta\beta}\beta\beta0\nu$ searches and bolster its scientific reach.

Abstract

NEXT-100 is a high-pressure xenon time projection chamber with electroluminescent amplification, designed to operate with up to approximately 70.5 kg at 13.5 bar. It is the most recent detector developed by the NEXT collaboration to search for the neutrinoless double-beta decay () of Xe-136. The NEXT gas TPC technology offers the best energy resolution near the Q-value of the decay ( = 2458 keV) among xenon detectors, which is set by design to be <1% FWHM. We report here the high-energy calibration of the detector using a Th-228 source, demonstrating linear response and an energy resolution of % FWHM at the Tl-208 photopeak (2615 keV). This performance extrapolates to a resolution at the double-beta decay end-point of = % FWHM, confirming the detector's capability for precision energy measurement in the search for .

Paper Structure

This paper contains 12 sections, 7 equations, 8 figures, 1 table.

Table of Contents

  1. Introduction
  2. The NEXT-100 detector
  3. Detector description
  4. Operational conditions
  5. Detector response calibration
  6. Event selection
  7. Geometric and Temporal Light Variation Effects
  8. Calibration of the energy scale
  9. Energy resolution
  10. Measurement of the 2615 keV $\gamma$ Photopeak
  11. Measurement of the 2615 keV $\gamma$ Single-Escape Peak (SEP)
  12. Conclusions

Figures (8)

  • Figure 1: Principle of operation of the NEXT-100 detector.
  • Figure 2: Example of PMT waveforms associated to tracks in an event. Top: Sum of the PMT waveform for an event. The time axis corresponds to the raw time recorded by the DAQ system within its 2 ms acquisition window. Center/Bottom: y–z and x–z projections reconstructed from SiPM data; the time axis represents the drift time measured from the S1 signal.
  • Figure 3: Left/center: Distributions of the minimum and maximum value of the track drift times within the events. Right: distribution of the maximum radial distance of the tracks. The red lines represent the selection cut in the three distributions.
  • Figure 4: Left: Kr-calibrated energy as a function of the true energy. The data are fitted with a second-degree polynomial to account for the slight nonlinearity in the detector response. In the bottom panel, the residuals normalized to the error on the mean are shown. Right: Energy spectrum corrected for residual non-linearity, with all the peaks produced by the gammas emitted in the ${}^{228}{\rm Th}$ chain visible.
  • Figure 5: Energy distributions for the a) 511 keV, b) 583 keV, c) 727 keV, d) 860 keV, e) 1593 keV, and f) 2615 keV peaks, along with their corresponding fits. The legend reports the fit parameters and $\chi^2/\mathrm{ndof}$ values. Below each distribution, the residuals normalized to the standard deviation are displayed. For f) the legend explicitly displays all component functions used in the fit.
  • ...and 3 more figures