Eur. Phys. J. C (2025) 85: 1192
https://doi.org/10.1140/epjc/s10052-025-14810-w

Regular Article - Experimental Physics

The XLZD Design Book: towards the next-generation liquid xenon observatory for dark matter and neutrino physics

¹ Nikhef and the University of Groningen, Van Swinderen Institute, 9747 AG, Groningen, Netherlands
² Kamioka Observatory, Institute for Cosmic Ray Research, and Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, Higashi-Mozumi, Kamioka, 506-1205, Hida, Gifu, Japan
³ Physik-Institut, University of Zürich, 8057, Zürich, Switzerland
⁴ LPNHE, CNRS/IN2P3, Sorbonne Université, 75005, Paris, France
⁵ SLAC National Accelerator Laboratory, 94025-7015, Menlo Park, CA, USA
⁶ Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 94305-4085, Stanford, CA, USA
⁷ Department of Physics and Astronomy, University College London (UCL), WC1E 6BT, London, UK
⁸ Institute for Nuclear Physics, University of Münster, 48149, Münster, Germany
⁹ Department of Physics and Astronomy, Rice University, 77005, Houston, TX, USA
¹⁰ Department of Physics, University of California, Santa Barbara, 93106-9530, Santa Barbara, CA, USA
¹¹ Blackett Laboratory, Department of Physics, Imperial College London, SW7 2AZ, London, UK
¹² INAF-Astrophysical Observatory of Torino, Department of Physics, University of Torino and INFN-Torino, 10125, Turin, Italy
¹³ INFN-Laboratori Nazionali del Gran Sasso and Gran Sasso Science Institute, 67100, L’Aquila, Italy
¹⁴ Vinca Institute of Nuclear Science, University of Belgrade, Mihajla Petrovica Alasa 12-14, Belgrade, Serbia
¹⁵ Physics Department, Columbia University, NY 10027, New York, USA
¹⁶ Department of Physics, University of Maryland, College Park, 20742-4111, MD, USA
¹⁷ Department of Physics and Astronomy, University of Alabama, 34587-0324, Tuscaloosa, AL, USA
¹⁸ Department of Physics, King’s College London, WC2R 2LS, London, UK
¹⁹ Institute for Data Processing and Electronics, Karlsruhe Institute of Technology, 76021, Karlsruhe, Germany
²⁰ Department of Physics, Brown University, 02912-9037, Providence, RI, USA
²¹ ARC Centre of Excellence for Dark Matter Particle Physics, School of Physics, The University of Melbourne, 3010, Melbourne, VIC, Australia
²² SUBATECH, IMT Atlantique, CNRS/IN2P3, Nantes Université, 44307, Nantes, France
²³ Lawrence Berkeley National Laboratory (LBNL), 94720-8099, Berkeley, CA, USA
²⁴ Department of Physics and Astronomy, University of Bologna and INFN-Bologna, 40126, Bologna, Italy
²⁵ Physical Sciences Laboratory, University of Wisconsin-Madison, 53589-3034, Madison, WI, USA
²⁶ Max-Planck-Institut für Kernphysik, 69117, Heidelberg, Germany
²⁷ Institute for Astroparticle Physics, Karlsruhe Institute of Technology, 76021, Karlsruhe, Germany
²⁸ SUPA, School of Physics and Astronomy, University of Edinburgh, EH9 3FD, Edinburgh, UK
²⁹ School of Physics, The University of Sydney, Camperdown, 2006, Sydney, NSW, Australia
³⁰ Brookhaven National Laboratory (BNL), 11973-5000, Upton, NY, USA
³¹ Laboratório de Instrumentação e Física Experimental de Partículas (LIP), University of Coimbra, 3004 516, Coimbra, Portugal
³² Department of Particle Physics and Astrophysics, Weizmann Institute of Science, 7610001, Rehovot, Israel
³³ STFC Rutherford Appleton Laboratory (RAL), OX11 0QX, Didcot, UK
³⁴ Institute of Experimental Particle Physics, Karlsruhe Institute of Technology, 76021, Karlsruhe, Germany
³⁵ Physikalisches Institut, Universität Freiburg, 79104, Freiburg, Germany
³⁶ School of Mathematical and Physical Sciences, University of Sheffield, S3 7RH, Sheffield, UK
³⁷ Department of Physics, University of Liverpool, L69 7ZE, Liverpool, UK
³⁸ Department of Physics and Center for High Energy Physics, Tsinghua University, 100084, Beijing, People’s Republic of China
³⁹ Department of Physics, Pennsylvania State University, 16802-6300, University Park, PA, USA
⁴⁰ Physikalisches Institut, Universität Heidelberg, Heidelberg, Germany
⁴¹ Department of Physics, Royal Holloway, University of London, TW20 0EX, Egham, UK
⁴² South Dakota School of Mines and Technology, 57701-3901, Rapid City, SD, USA
⁴³ H.H. Wills Physics Laboratory, University of Bristol, BS8 1TL, Bristol, UK
⁴⁴ Nikhef and The University of Amsterdam, Science Park, 1098XG, Amsterdam, Netherlands
⁴⁵ Department of Physics, Oskar Klein Centre, Stockholm University, AlbaNova, 10691, Stockholm, Sweden
⁴⁶ Department of Physics and Astronomy, University of Rochester, 14627-0171, Rochester, NY, USA
⁴⁷ South Dakota Science and Technology Authority (SDSTA), Sanford Underground Research Facility, 57754-1700, Lead, SD, USA
⁴⁸ Institut für Physik & Exzellenzcluster PRISMA+, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany
⁴⁹ Department of Physics, University of Oxford, OX1 3RH, Oxford, UK
⁵⁰ Department of Physics and Chemistry, University of L’Aquila, 67100, L’Aquila, Italy
⁵¹ Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, and Institute for Space-Earth Environmental Research, Nagoya University, Furo-cho, Chikusa-ku, 464-8602, Nagoya, Aichi, Japan
⁵² Department of Physics and Astronomy, Purdue University, 47907, West Lafayette, IN, USA
⁵³ Department of Physics “Ettore Pancini”, University of Napoli and INFN-Napoli, 80126, Naples, Italy
⁵⁴ Department of Physics, University of California, Berkeley, 94720-7300, Berkeley, CA, USA
⁵⁵ Department of Physics, Enrico Fermi Institute & Kavli Institute for Cosmological Physics, University of Chicago, 60637, Chicago, IL, USA
⁵⁶ Randall Laboratory of Physics, University of Michigan, 48109-1040, Ann Arbor, MI, USA
⁵⁷ Department of Physics, University of Massachusetts, 01003-9337, Amherst, MA, USA
⁵⁸ Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Sidlerstrasse 5, 3012, Bern, Switzerland
⁵⁹ Department of Physics, University of California San Diego, 92093, La Jolla, CA, USA
⁶⁰ Department of Physics and Astronomy, University of California, Los Angeles, 90095-1547, Los Angeles, CA, USA
⁶¹ Department of Physics and Astronomy, Bucknell University, Lewisburg, PA, USA
⁶² Department of Physics, University of Texas at Austin, 78712-1192, Austin, TX, USA
⁶³ Kirchhoff-Institut für Physik, Universität Heidelberg, Heidelberg, Germany
⁶⁴ IBS Center for Underground Physics (CUP), Yuseong-gu, Daejeon, Korea
⁶⁵ Institut für Kern und Teilchenphysik, Technische Universität Dresden, 01069, Dresden, Germany
⁶⁶ Department of Physics, School of Science, Westlake University, 310030, Hangzhou, People’s Republic of China
⁶⁷ School of Science and Engineering, The Chinese University of Hong Kong (Shenzhen), 518172, Shenzhen, Guangdong, People’s Republic of China
⁶⁸ LIBPhys, Department of Physics, University of Coimbra, 3004-516, Coimbra, Portugal
⁶⁹ Lawrence Livermore National Laboratory (LLNL), 94550-9698, Livermore, CA, USA
⁷⁰ Departament de Física Quàntica i Astrofísica and Institut de Ciències del Cosmos, Universitat de Barcelona, 08028, Barcelona, Spain
⁷¹ Department of Physics, Kobe University, 657-8501, Hyogo, Japan
⁷² Vatican Observatory, Castel Gandolfo, 00120, Vatican City, Italy
⁷³ School of Natural Sciences, Black Hills State University, 57799-0002, Spearfish, SD, USA
⁷⁴ Theoretical and Scientific Data Science, Scuola Internazionale Superiore di Studi Avanzati (SISSA), 34136, Trieste, Italy
⁷⁵ Department of Physics, Technische Universität Darmstadt, 64289, Darmstadt, Germany
⁷⁶ Department of Physics, University of California, Davis, 95616-5270, Davis, CA, USA
⁷⁷ INFN-Ferrara and Dip. di Fisica e Scienze della Terra, Università di Ferrara, 44122, Ferrara, Italy
⁷⁸ University of Banja Luka, 78000, Banja Luka, Bosnia and Herzegovina
⁷⁹ INFN-Roma Tre, 00146, Rome, Italy
⁸⁰ Coimbra Polytechnic-ISEC, 3030-199, Coimbra, Portugal
⁸¹ University of Grenada, Granada, Spain

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Received: 14 April 2025
Accepted: 18 September 2025
Published online: 23 October 2025

Abstract

This report describes the experimental strategy and technologies for XLZD, the next-generation xenon observatory sensitive to dark matter and neutrino physics. In the baseline design, the detector will have an active liquid xenon target of 60 tonnes, which could be increased to 80 tonnes if the market conditions for xenon are favorable. It is based on the mature liquid xenon time projection chamber technology used in current-generation experiments, LZ and XENONnT. The report discusses the baseline design and opportunities for further optimization of the individual detector components. The experiment envisaged here has the capability to explore parameter space for Weakly Interacting Massive Particle (WIMP) dark matter down to the neutrino fog, with a 3$\sigma$ evidence potential for WIMP-nucleon cross sections as low as $3\times {10}^{-49}c{m}^2$ (at 40 GeV/c$_{}^2$ WIMP mass). The observatory will also have leading sensitivity to a wide range of alternative dark matter models. It is projected to have a 3$\sigma$ observation potential of neutrinoless double beta decay of $_{}^{136}$Xe at a half-life of up to $5.7\times {10}^{27}$ years. Additionally, it is sensitive to astrophysical neutrinos from the sun and galactic supernovae.