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Measurement of coherent elastic neutrino nucleus scattering on germanium by COHERENT

M. Adhikari, M. Ahn, D. Amaya Matamoros, P. S. Barbeau, V. Belov, I. Bernardi, C. Bock, A. Bolozdynya, R. Bouabid, A. Bracho, J. Browning, B. Cabrera-Palmer, N. Cedarblade-Jones, S. Chen, A. I. Colón Rivera, V. da Silva, Y. Efremenko, S. R. Elliott, A. Erlandson, L. Fabris, S. Foster, A. Galindo-Uribarri, E. Granados Vazquez, M. P. Green, B. Hackett, J. Hakenmüller, M. Harada, M. R. Heath, S. Hedges, Y. Hino, H. Huang, W. Huang, H. Jeong, B. A. Johnson, T. Johnson, H. Jones, A. Khromov, D. Kim, L. Kong, A. Konovalov, Y. Koshio, E. Kozlova, A. Kumpan, O. Kyzylova, Y. Lee, S. M. Lee, G. Li, L. Li, Z. Li, J. M. Link, J. Liu, Q. Liu, X. Lu, M. Luxnat, A. Major, D. M. Markoff, J. Mattingly, H. McLaurin, K. McMichael, N. Meredith, Y. Nakajima, F. Nakanishi, J. Newby, N. Ogoi, J. O'Reilly, A. Orvedahl, D. S. Parno, D. Pérez-Loureiro, D. Pershey, C. G. Prior, J. Queen, R. Rapp, H. Ray, O. Razuvaeva, D. Reyna, D. Rudik, J. Runge, D. J. Salvat, J. Sander, K. Scholberg, H. Sekiya, A. Shakirov, G. Simakov, J. Skweres, W. M. Snow, V. Sosnovtsev, M. Stringer, C. Su, T. Subedi, B. Suh, B. Sur, R. Tayloe, Y. -T. Tsai, E. E. van Nieuwenhuizen, C. J. Virtue, G. Visser, K. Walkup, E. M. Ward, R. Wendell, T. Wongjirad, C. Yang, Y. Yang, J. Yoo, Y. Yu, A. Zaalishvili, Y. Zheng

Abstract

The COHERENT collaboration reports the most precise measurement of the coherent elastic neutrino-nucleus scattering cross section to date. This measurement was performed with COHERENT's germanium detector array, Ge-Mini, at the Spallation Neutron Source at Oak Ridge National Laboratory. A cumulative exposure of $4.68\times10^{22}$ protons on target yielded a total number of observed counts of $124^{+14}_{-12}$ and a flux-averaged cross section of $1.00 \pm 0.10 \mathrm{(statistical)} \pm 0.10 \mathrm{(systematic)}$ relative to the standard-model expectation of $5.9\times10^{-39} \mathrm{cm}^2$. The well-understood energy and timing distributions of the neutrino source allow for independent measurements of muon- and electron-neutrino scattering rates. This information is used to improve constraints on non-standard neutrino interactions mediated by heavy particles.

Measurement of coherent elastic neutrino nucleus scattering on germanium by COHERENT

Abstract

The COHERENT collaboration reports the most precise measurement of the coherent elastic neutrino-nucleus scattering cross section to date. This measurement was performed with COHERENT's germanium detector array, Ge-Mini, at the Spallation Neutron Source at Oak Ridge National Laboratory. A cumulative exposure of protons on target yielded a total number of observed counts of and a flux-averaged cross section of relative to the standard-model expectation of . The well-understood energy and timing distributions of the neutrino source allow for independent measurements of muon- and electron-neutrino scattering rates. This information is used to improve constraints on non-standard neutrino interactions mediated by heavy particles.
Paper Structure (9 sections, 4 figures, 1 table)

This paper contains 9 sections, 4 figures, 1 table.

Table of Contents

  1. Introduction.---
  2. Experiment.---
  3. Data taking.---
  4. Data analysis.---
  5. Backgrounds.---
  6. Signal Prediction.---
  7. Results.---
  8. Summary and outlook.---
  9. Acknowledgements.-

Figures (4)

  • Figure 1: Example waveforms from the Ge-Mini detectors: (a) a surface-like event and (b) a signal-like event. The raw pulse (black) is overlaid with the output of the matched triangle filter (red) used to determine the pulse onset and the output of the trapezoidal filter (blue) used to reconstruct the pulse energy; circles indicate the maxima of each filter. The pulse shape parameter, defined as the ratio of the triangle-filter maximum to the trapezoidal-filter maximum, is close to unity for signal-like events and smaller for slow-rise surface-background events.
  • Figure 2: Best-fit maximum likelihood estimates of the signal (orange) and background (blue) distributions projected in energy and time for both off-beam and on-beam data. The energy region of interest is from [0.5, 20] keV$_{\text{ee}}$, while the time region of interest is from [-4, 40] $\mu$s with respect to an external beam trigger such that the neutrino arrival is expected to begin at -160 ns. Calibration data, simultaneously fit to constrain the parametrization of the background, is not shown here.
  • Figure 3: Profile likelihood as a function of the ratio of observed to predicted event rates. The blue curve shows the likelihood curve from Ref. COHERENT:GePRL and green curve shows this work, while the orange curve corresponds to the combined result. The shaded band indicates the standard-model expectation and its associated 10.3% uncertainty.
  • Figure 4: 90% confidence intervals in the $(\epsilon_u^{ee}, \epsilon_u^{\mu \mu})$ plane for previous COHERENT results using the CsI COHERENT:CsIPRL and Ar COHERENT:2020ArPRL detectors in gray DeRomeri:2022twg, and this work in red. The vertical and horizontal lines are the standard model values.