Eur. Phys. J. C (2023) 83: 542
https://doi.org/10.1140/epjc/s10052-023-11512-z

Regular Article - Experimental Physics

Low-energy calibration of XENON1T with an internal ${}^{\mathbf{37}}$Ar source

¹ Physics Department, Columbia University, 10027, New York, NY, USA
² Kamioka Observatory, Institute for Cosmic Ray Research, Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, Higashi-Mozumi, Kamioka, 506-1205, Hida, Gifu, Japan
³ Department of Physics and Astronomy, University of Bologna and INFN-Bologna, 40126, Bologna, Italy
⁴ LPNHE, Sorbonne Université, CNRS/IN2P3, 75005, Paris, France
⁵ Institut für Physik & Exzellenzcluster PRISMA+, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany
⁶ Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, 48149, Münster, Germany
⁷ INAF-Astrophysical Observatory of Torino, Department of Physics, University of Torino and INFN-Torino, 10125, Turin, Italy
⁸ Nikhef and the University of Amsterdam, Science Park, 1098 XG, Amsterdam, The Netherlands
⁹ Department of Physics, Oskar Klein Centre, Stockholm University, AlbaNova, SE-10691, Stockholm, Sweden
¹⁰ Department of Physics, Kavli Institute for Cosmological Physics, University of Chicago, 60637, Chicago, IL, USA
¹¹ New York University Abu Dhabi, Center for Astro, Particle and Planetary Physics, Abu Dhabi, United Arab Emirates
¹² Physik-Institut, University of Zürich, 8057, Zurich, Switzerland
¹³ Department of Physics and Astronomy, Purdue University, 47907, West Lafayette, IN, USA
¹⁴ INFN-Laboratori Nazionali del Gran Sasso and Gran Sasso Science Institute, 67100, L’Aquila, Italy
¹⁵ Physikalisches Institut, Universität Freiburg, 79104, Freiburg, Germany
¹⁶ SUBATECH, IMT Atlantique, CNRS/IN2P3, Université de Nantes, 44307, Nantes, France
¹⁷ Department of Particle Physics and Astrophysics, Weizmann Institute of Science, 7610001, Rehovot, Israel
¹⁸ Department of Physics, Center for High Energy Physics, Tsinghua University, 100084, Beijing, China
¹⁹ LIBPhys, Department of Physics, University of Coimbra, 3004-516, Coimbra, Portugal
²⁰ Max-Planck-Institut für Kernphysik, 69117, Heidelberg, Germany
²¹ Institute for Astroparticle Physics, Karlsruhe Institute of Technology, 76021, Karlsruhe, Germany
²² Department of Physics and Chemistry, University of L’Aquila, 67100, L’Aquila, Italy
²³ Department of Physics and Astronomy, Rice University, 77005, Houston, TX, USA
²⁴ Department of Physics “Ettore Pancini”, University of Napoli and INFN-Napoli, 80126, Naples, Italy
²⁵ Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Institute for Space-Earth Environmental Research, Nagoya University, Furo-cho, Chikusa-ku, 464-8602, Nagoya, Aichi, Japan
²⁶ Department of Physics, University of California San Diego, 92093, La Jolla, CA, USA
²⁷ Department of Physics, Kobe University, 657-8501, Kobe, Hyogo, Japan
²⁸ Forschungsreaktor TRIGA Mainz, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany
²⁹ Coimbra Polytechnic - ISEC, 3030-199, Coimbra, Portugal
³⁰ Physikalisches Institut, Universität Heidelberg, Heidelberg, Germany
³¹ INFN, Sez. di Ferrara and Dip. di Fisica e Scienze della Terra, Università di Ferrara, via G. Saragat 1, Edificio C, I-44122, Ferrara (FE), Italy

^h emanuele.angelino@to.infn.it
^bh chils@uni-mainz.de
^df amolinar@to.infn.it
^ew shockley.evan@gmail.com

Received: 25 November 2022
Accepted: 14 April 2023
Published online: 27 June 2023

Abstract

A low-energy electronic recoil calibration of XENON1T, a dual-phase xenon time projection chamber, with an internal ${}^{37}$Ar source was performed. This calibration source features a 35-day half-life and provides two mono-energetic lines at 2.82 keV and 0.27 keV. The photon yield and electron yield at 2.82 keV are measured to be ($32.3\pm 0.3$) photons/keV and ($40.6\pm 0.5$) electrons/keV, respectively, in agreement with other measurements and with NEST predictions. The electron yield at 0.27 keV is also measured and it is ($68.0_{-3.7}^{+6.3}$) electrons/keV. The ${}^{37}$Ar calibration confirms that the detector is well-understood in the energy region close to the detection threshold, with the 2.82 keV line reconstructed at ($2.83\pm 0.02$) keV, which further validates the model used to interpret the low-energy electronic recoil excess previously reported by XENON1T. The ability to efficiently remove argon with cryogenic distillation after the calibration proves that ${}^{37}$Ar can be considered as a regular calibration source for multi-tonne xenon detectors.