Showing 1–50 of 89 results for author: Schulte, D

Comparative evaluation of future collider options

Authors: G. Arduini, M. Benedikt, F. Gianotti, K. Jakobs, M. Lamont, R. Losito, M. Meddahi, J. Mnich, N. Mounet, D. Schulte, F. Sonnemann, S. Stapnes, F. Zimmermann

Abstract: In anticipation of the completion of the High-Luminosity Large Hadron Collider (HL-LHC) programme by the end of 2041, CERN is preparing to launch a new major facility in the mid-2040s. According to the 2020 update of the European Strategy for Particle Physics (ESPP), the highest-priority next collider is an electron-positron Higgs factory, followed in the longer term by a hadron-hadron collider at… ▽ More In anticipation of the completion of the High-Luminosity Large Hadron Collider (HL-LHC) programme by the end of 2041, CERN is preparing to launch a new major facility in the mid-2040s. According to the 2020 update of the European Strategy for Particle Physics (ESPP), the highest-priority next collider is an electron-positron Higgs factory, followed in the longer term by a hadron-hadron collider at the highest achievable energy. The CERN directorate established a Future Colliders Comparative Evaluation working group in June 2023. This group brings together project leaders and domain experts to conduct a consistent evaluation of the Future Circular Collider (FCC) and alternative scenarios based on shared assumptions and standardized criteria. This report presents a comparative evaluation of proposed future collider projects submitted as input for the Update of the European Strategy for Particle Physics. These proposals are compared considering main performance parameters, environmental impact and sustainability, technical maturity, cost of construction and operation, required human resources, and realistic implementation timelines. An overview of the international collider projects within a similar timeframe, notably the CEPC in China and the ILC in Japan is also presented, as well as a short review of the status and prospects of new accelerator techniques. △ Less

Submitted 20 January, 2026; v1 submitted 25 November, 2025; originally announced November 2025.

Comments: 83 pages, 10 figures. Report from the Future Colliders Comparative Evaluation Working Group. Input to the European Strategy for Particle Physics (2026 Update), ID 281 - see https://indico.cern.ch/event/1439855/contributions/6542430/

Report number: CERN-2025-011

Journal ref: Comparative evaluation of future collider options, Future Colliders Comparative Evaluation Working Group. CERN Yellow Reports: Monographs, CERN-2025-011 (CERN, Geneva, 2025)

MuCol Milestone Report No. 7: Consolidated Parameters

Authors: Rebecca Taylor, Antoine Chancé, Dario Augusto Giove, Natalia Milas, Roberto Losito, Donatella Lucchesi, Chris Rogers, Lucio Rossi, Daniel Schulte, Carlotta Accettura, Simon Adrian, Rohit Agarwal, Claudia Ahdida, Chiara Aime, Avni Aksoy, Gian Luigi Alberghi, Simon Albright, Siobhan Alden, Luca Alfonso, Muhammad Ali, Anna Rita Altamura, Nicola Amapane, Kathleen Amm, David Amorim, Paolo Andreetto , et al. (437 additional authors not shown)

Abstract: This document is comprised of a collection of consolidated parameters for the key parts of the muon collider. These consolidated parameters follow on from the October 2024 Preliminary Parameters Report. Attention has been given to a high-level consistent set of baseline parameters throughout all systems of the complex, following a 10 TeV center-of-mass design. Additional details of the designs con… ▽ More This document is comprised of a collection of consolidated parameters for the key parts of the muon collider. These consolidated parameters follow on from the October 2024 Preliminary Parameters Report. Attention has been given to a high-level consistent set of baseline parameters throughout all systems of the complex, following a 10 TeV center-of-mass design. Additional details of the designs contributing to this baseline design are featured in the appendix. Likewise, explorative variations from this baseline set can be found in the appendix. The data is collected from a collaborative spreadsheet and transferred to overleaf. △ Less

Submitted 31 October, 2025; originally announced October 2025.

Future Circular Collider Feasibility Study Report: Volume 2, Accelerators, Technical Infrastructure and Safety

Authors: M. Benedikt, F. Zimmermann, B. Auchmann, W. Bartmann, J. P. Burnet, C. Carli, A. Chancé, P. Craievich, M. Giovannozzi, C. Grojean, J. Gutleber, K. Hanke, A. Henriques, P. Janot, C. Lourenço, M. Mangano, T. Otto, J. Poole, S. Rajagopalan, T. Raubenheimer, E. Todesco, L. Ulrici, T. Watson, G. Wilkinson, A. Abada , et al. (1439 additional authors not shown)

Abstract: In response to the 2020 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) Feasibility Study was launched as an international collaboration hosted by CERN. This report describes the FCC integrated programme, which consists of two stages: an electron-positron collider (FCC-ee) in the first phase, serving as a high-luminosity Higgs, top, and electroweak factory;… ▽ More In response to the 2020 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) Feasibility Study was launched as an international collaboration hosted by CERN. This report describes the FCC integrated programme, which consists of two stages: an electron-positron collider (FCC-ee) in the first phase, serving as a high-luminosity Higgs, top, and electroweak factory; followed by a proton-proton collider (FCC-hh) at the energy frontier in the second phase. FCC-ee is designed to operate at four key centre-of-mass energies: the Z pole, the WW production threshold, the ZH production peak, and the top/anti-top production threshold - delivering the highest possible luminosities to four experiments. Over 15 years of operation, FCC-ee will produce more than 6 trillion Z bosons, 200 million WW pairs, nearly 3 million Higgs bosons, and 2 million top anti-top pairs. Precise energy calibration at the Z pole and WW threshold will be achieved through frequent resonant depolarisation of pilot bunches. The sequence of operation modes remains flexible. FCC-hh will operate at a centre-of-mass energy of approximately 85 TeV - nearly an order of magnitude higher than the LHC - and is designed to deliver 5 to 10 times the integrated luminosity of the HL-LHC. Its mass reach for direct discovery extends to several tens of TeV. In addition to proton-proton collisions, FCC-hh is capable of supporting ion-ion, ion-proton, and lepton-hadron collision modes. This second volume of the Feasibility Study Report presents the complete design of the FCC-ee collider, its operation and staging strategy, the full-energy booster and injector complex, required accelerator technologies, safety concepts, and technical infrastructure. It also includes the design of the FCC-hh hadron collider, development of high-field magnets, hadron injector options, and key technical systems for FCC-hh. △ Less

Submitted 25 April, 2025; originally announced May 2025.

Comments: 627 pages. Please address any comment or request to fcc.secretariat@cern.ch

Report number: CERN-FCC-ACC-2025-0004

Future Circular Collider Feasibility Study Report: Volume 3, Civil Engineering, Implementation and Sustainability

Authors: M. Benedikt, F. Zimmermann, B. Auchmann, W. Bartmann, J. P. Burnet, C. Carli, A. Chancé, P. Craievich, M. Giovannozzi, C. Grojean, J. Gutleber, K. Hanke, A. Henriques, P. Janot, C. Lourenço, M. Mangano, T. Otto, J. Poole, S. Rajagopalan, T. Raubenheimer, E. Todesco, L. Ulrici, T. Watson, G. Wilkinson, P. Azzi , et al. (1439 additional authors not shown)

Abstract: Volume 3 of the FCC Feasibility Report presents studies related to civil engineering, the development of a project implementation scenario, and environmental and sustainability aspects. The report details the iterative improvements made to the civil engineering concepts since 2018, taking into account subsurface conditions, accelerator and experiment requirements, and territorial considerations. I… ▽ More Volume 3 of the FCC Feasibility Report presents studies related to civil engineering, the development of a project implementation scenario, and environmental and sustainability aspects. The report details the iterative improvements made to the civil engineering concepts since 2018, taking into account subsurface conditions, accelerator and experiment requirements, and territorial considerations. It outlines a technically feasible and economically viable civil engineering configuration that serves as the baseline for detailed subsurface investigations, construction design, cost estimation, and project implementation planning. Additionally, the report highlights ongoing subsurface investigations in key areas to support the development of an improved 3D subsurface model of the region. The report describes development of the project scenario based on the 'avoid-reduce-compensate' iterative optimisation approach. The reference scenario balances optimal physics performance with territorial compatibility, implementation risks, and costs. Environmental field investigations covering almost 600 hectares of terrain - including numerous urban, economic, social, and technical aspects - confirmed the project's technical feasibility and contributed to the preparation of essential input documents for the formal project authorisation phase. The summary also highlights the initiation of public dialogue as part of the authorisation process. The results of a comprehensive socio-economic impact assessment, which included significant environmental effects, are presented. Even under the most conservative and stringent conditions, a positive benefit-cost ratio for the FCC-ee is obtained. Finally, the report provides a concise summary of the studies conducted to document the current state of the environment. △ Less

Submitted 25 April, 2025; originally announced May 2025.

Comments: 357 pages. Please address any comment or request to fcc.secretariat@cern.ch

Report number: CERN-FCC-ACC-2025-0003

Future Circular Collider Feasibility Study Report: Volume 1, Physics, Experiments, Detectors

Authors: M. Benedikt, F. Zimmermann, B. Auchmann, W. Bartmann, J. P. Burnet, C. Carli, A. Chancé, P. Craievich, M. Giovannozzi, C. Grojean, J. Gutleber, K. Hanke, A. Henriques, P. Janot, C. Lourenço, M. Mangano, T. Otto, J. Poole, S. Rajagopalan, T. Raubenheimer, E. Todesco, L. Ulrici, T. Watson, G. Wilkinson, P. Azzi , et al. (1439 additional authors not shown)

Abstract: Volume 1 of the FCC Feasibility Report presents an overview of the physics case, experimental programme, and detector concepts for the Future Circular Collider (FCC). This volume outlines how FCC would address some of the most profound open questions in particle physics, from precision studies of the Higgs and EW bosons and of the top quark, to the exploration of physics beyond the Standard Model.… ▽ More Volume 1 of the FCC Feasibility Report presents an overview of the physics case, experimental programme, and detector concepts for the Future Circular Collider (FCC). This volume outlines how FCC would address some of the most profound open questions in particle physics, from precision studies of the Higgs and EW bosons and of the top quark, to the exploration of physics beyond the Standard Model. The report reviews the experimental opportunities offered by the staged implementation of FCC, beginning with an electron-positron collider (FCC-ee), operating at several centre-of-mass energies, followed by a hadron collider (FCC-hh). Benchmark examples are given of the expected physics performance, in terms of precision and sensitivity to new phenomena, of each collider stage. Detector requirements and conceptual designs for FCC-ee experiments are discussed, as are the specific demands that the physics programme imposes on the accelerator in the domains of the calibration of the collision energy, and the interface region between the accelerator and the detector. The report also highlights advances in detector, software and computing technologies, as well as the theoretical tools /reconstruction techniques that will enable the precision measurements and discovery potential of the FCC experimental programme. This volume reflects the outcome of a global collaborative effort involving hundreds of scientists and institutions, aided by a dedicated community-building coordination, and provides a targeted assessment of the scientific opportunities and experimental foundations of the FCC programme. △ Less

Submitted 25 April, 2025; originally announced May 2025.

Comments: 290 pages. Please address any comment or request to fcc.secretariat@cern.ch

Report number: CERN-FCC-PHYS-2025-0002

The Muon Collider

Authors: Carlotta Accettura, Simon Adrian, Rohit Agarwal, Claudia Ahdida, Chiara Aime', Avni Aksoy, Gian Luigi Alberghi, Siobhan Alden, Luca Alfonso, Muhammad Ali, Anna Rita Altamura, Nicola Amapane, Kathleen Amm, David Amorim, Paolo Andreetto, Fabio Anulli, Ludovica Aperio Bella, Rob Appleby, Artur Apresyan, Pouya Asadi, Mohammed Attia Mahmoud, Bernhard Auchmann, John Back, Anthony Badea, Kyu Jung Bae , et al. (433 additional authors not shown)

Abstract: Muons offer a unique opportunity to build a compact high-energy electroweak collider at the 10 TeV scale. A Muon Collider enables direct access to the underlying simplicity of the Standard Model and unparalleled reach beyond it. It will be a paradigm-shifting tool for particle physics representing the first collider to combine the high-energy reach of a proton collider and the high precision of an… ▽ More Muons offer a unique opportunity to build a compact high-energy electroweak collider at the 10 TeV scale. A Muon Collider enables direct access to the underlying simplicity of the Standard Model and unparalleled reach beyond it. It will be a paradigm-shifting tool for particle physics representing the first collider to combine the high-energy reach of a proton collider and the high precision of an electron-positron collider, yielding a physics potential significantly greater than the sum of its individual parts. A high-energy muon collider is the natural next step in the exploration of fundamental physics after the HL-LHC and a natural complement to a future low-energy Higgs factory. Such a facility would significantly broaden the scope of particle colliders, engaging the many frontiers of the high energy community. The last European Strategy for Particle Physics Update and later the Particle Physics Project Prioritisation Panel in the US requested a study of the muon collider, which is being carried on by the International Muon Collider Collaboration. In this comprehensive document we present the physics case, the state of the work on accelerator design and technology, and propose an R\&D project that can make the muon collider a reality. △ Less

Submitted 30 April, 2025; originally announced April 2025.

Comments: 406 pages, supplementary report to the European Strategy for Particle Physics - 2026 update

The Compact Linear e$^+$e$^-$ Collider (CLIC)

Authors: Erik Adli, Gerardo D'Auria, Nuria Catalan Lasheras, Vera Cilento, Roberto Corsini, Dominik Dannheim, Steffen Doebert, Mick Draper, Angeles Faus-Golfe, Edward Fraser Mactavish, Alexej Grudiev, Andrea Latina, Lucie Linssen, John Andrew Osborne, Yannis Papaphilippou, Philipp Roloff, Aidan Robson, Carlo Rossi, Andre Sailer, Daniel Schulte, Eva Sicking, Steinar Stapnes, Igor Syratchev, Rogelio Tomas Garcia, Walter Wuensch

Abstract: The Compact Linear Collider (CLIC) is a TeV-scale high-luminosity linear e$^+$e$^-$ collider studied by the international CLIC and CLICdp collaborations. CLIC uses a two-beam acceleration scheme, in which normal-conducting high-gradient 12 GHz accelerating structures are powered via a high-current drive beam. CLIC is foreseen to be built and operated in stages. The initial 380 GeV stage, with a si… ▽ More The Compact Linear Collider (CLIC) is a TeV-scale high-luminosity linear e$^+$e$^-$ collider studied by the international CLIC and CLICdp collaborations. CLIC uses a two-beam acceleration scheme, in which normal-conducting high-gradient 12 GHz accelerating structures are powered via a high-current drive beam. CLIC is foreseen to be built and operated in stages. The initial 380 GeV stage, with a site length of 11 km, optimally combines the exploration of Higgs and top-quark physics, including a top threshold scan near 350 GeV. A higher-energy stage, still using the initial single drive-beam complex, can be optimised for any energy up to 2 TeV. Parameters are presented in detail for a 1.5 TeV stage, with a site length of 29 km. Since the 2018 ESPPU reporting, significant effort was invested in CLIC accelerator optimisation, technology developments and system tests, including collaboration with new-generation light sources and free-electron lasers. CLIC implementation aspects at CERN have covered detailed studies of civil engineering, electrical networks, cooling and ventilation, scheduling, and costing. The CLIC baseline at 380 GeV is now 100 Hz operation, with a luminosity of 4.5$\times 10^{34}$ cm$^{-2}$s$^{-1}$ and a power consumption of 166 MW. Compared to the 2018 design, this gives three times higher luminosity-per-power. The new baseline has two beam-delivery systems, allowing for two detectors operating in parallel. The cost estimate of the 380 GeV baseline is approximately 7.2 billion CHF. The construction of the first CLIC energy stage could start as early as ~2034/35 with first beams following a decade later. This report summarises the CLIC project, its implementation and running scenarios, with emphasis on new developments and recent progress. It concludes with an update on the CLIC detector studies and on the physics potential in light of the improved accelerator performance. △ Less

Submitted 3 September, 2025; v1 submitted 31 March, 2025; originally announced March 2025.

Radon Removal in XENONnT down to the Solar Neutrino Level

Authors: E. Aprile, J. Aalbers, K. Abe, S. Ahmed Maouloud, L. Althueser, B. Andrieu, E. Angelino, D. Antón Martin, F. Arneodo, L. Baudis, M. Bazyk, L. Bellagamba, R. Biondi, A. Bismark, K. Boese, A. Brown, G. Bruno, R. Budnik, C. Cai, C. Capelli, J. M. R. Cardoso, A. P. Cimental Chávez, A. P. Colijn, J. Conrad, J. J. Cuenca-García , et al. (147 additional authors not shown)

Abstract: The XENONnT experiment has achieved an exceptionally low $^\text{222}$Rn activity concentration within its inner 5.9$\,$tonne liquid xenon detector of (0.90$\,\pm\,$0.01$\,$stat.$\,\pm\,$0.07 sys.)$\,μ$Bq/kg, equivalent to about 430 $^\text{222}$Rn atoms per tonne of xenon. This was achieved by active online radon removal via cryogenic distillation after stringent material selection. The achieved… ▽ More The XENONnT experiment has achieved an exceptionally low $^\text{222}$Rn activity concentration within its inner 5.9$\,$tonne liquid xenon detector of (0.90$\,\pm\,$0.01$\,$stat.$\,\pm\,$0.07 sys.)$\,μ$Bq/kg, equivalent to about 430 $^\text{222}$Rn atoms per tonne of xenon. This was achieved by active online radon removal via cryogenic distillation after stringent material selection. The achieved $^\text{222}$Rn activity concentration is five times lower than that in other currently operational multi-tonne liquid xenon detectors engaged in dark matter searches. This breakthrough enables the pursuit of various rare event searches that lie beyond the confines of the standard model of particle physics, with world-leading sensitivity. The ultra-low $^\text{222}$Rn levels have diminished the radon-induced background rate in the detector to a point where it is for the first time comparable to the solar neutrino-induced background, which is poised to become the primary irreducible background in liquid xenon-based detectors. △ Less

Submitted 25 April, 2025; v1 submitted 6 February, 2025; originally announced February 2025.

MuCol Milestone Report No. 5: Preliminary Parameters

Authors: Carlotta Accettura, Simon Adrian, Rohit Agarwal, Claudia Ahdida, Chiara Aimé, Avni Aksoy, Gian Luigi Alberghi, Siobhan Alden, Luca Alfonso, Nicola Amapane, David Amorim, Paolo Andreetto, Fabio Anulli, Rob Appleby, Artur Apresyan, Pouya Asadi, Mohammed Attia Mahmoud, Bernhard Auchmann, John Back, Anthony Badea, Kyu Jung Bae, E. J. Bahng, Lorenzo Balconi, Fabrice Balli, Laura Bandiera , et al. (369 additional authors not shown)

Abstract: This document is comprised of a collection of updated preliminary parameters for the key parts of the muon collider. The updated preliminary parameters follow on from the October 2023 Tentative Parameters Report. Particular attention has been given to regions of the facility that are believed to hold greater technical uncertainty in their design and that have a strong impact on the cost and power… ▽ More This document is comprised of a collection of updated preliminary parameters for the key parts of the muon collider. The updated preliminary parameters follow on from the October 2023 Tentative Parameters Report. Particular attention has been given to regions of the facility that are believed to hold greater technical uncertainty in their design and that have a strong impact on the cost and power consumption of the facility. The data is collected from a collaborative spreadsheet and transferred to overleaf. △ Less

Submitted 5 November, 2024; originally announced November 2024.

XENONnT Analysis: Signal Reconstruction, Calibration and Event Selection

Authors: XENON Collaboration, E. Aprile, J. Aalbers, K. Abe, S. Ahmed Maouloud, L. Althueser, B. Andrieu, E. Angelino, J. R. Angevaare, D. Antón Martin, F. Arneodo, L. Baudis, M. Bazyk, L. Bellagamba, R. Biondi, A. Bismark, K. Boese, A. Brown, G. Bruno, R. Budnik, J. M. R. Cardoso, A. P. Cimental Chávez, A. P. Colijn, J. Conrad, J. J. Cuenca-García , et al. (143 additional authors not shown)

Abstract: The XENONnT experiment, located at the INFN Laboratori Nazionali del Gran Sasso, Italy, features a 5.9 tonne liquid xenon time projection chamber surrounded by an instrumented neutron veto, all of which is housed within a muon veto water tank. Due to extensive shielding and advanced purification to mitigate natural radioactivity, an exceptionally low background level of (15.8 $\pm$ 1.3) events/(to… ▽ More The XENONnT experiment, located at the INFN Laboratori Nazionali del Gran Sasso, Italy, features a 5.9 tonne liquid xenon time projection chamber surrounded by an instrumented neutron veto, all of which is housed within a muon veto water tank. Due to extensive shielding and advanced purification to mitigate natural radioactivity, an exceptionally low background level of (15.8 $\pm$ 1.3) events/(tonne$\cdot$year$\cdot$keV) in the (1, 30) keV region is reached in the inner part of the TPC. XENONnT is thus sensitive to a wide range of rare phenomena related to Dark Matter and Neutrino interactions, both within and beyond the Standard Model of particle physics, with a focus on the direct detection of Dark Matter in the form of weakly interacting massive particles (WIMPs). From May 2021 to December 2021, XENONnT accumulated data in rare-event search mode with a total exposure of one tonne $\cdot$ year. This paper provides a detailed description of the signal reconstruction methods, event selection procedure, and detector response calibration, as well as an overview of the detector performance in this time frame. This work establishes the foundational framework for the `blind analysis' methodology we are using when reporting XENONnT physics results. △ Less

Submitted 13 September, 2024; originally announced September 2024.

Comments: 27 pages, 23 figures

Interim report for the International Muon Collider Collaboration (IMCC)

Authors: C. Accettura, S. Adrian, R. Agarwal, C. Ahdida, C. Aimé, A. Aksoy, G. L. Alberghi, S. Alden, N. Amapane, D. Amorim, P. Andreetto, F. Anulli, R. Appleby, A. Apresyan, P. Asadi, M. Attia Mahmoud, B. Auchmann, J. Back, A. Badea, K. J. Bae, E. J. Bahng, L. Balconi, F. Balli, L. Bandiera, C. Barbagallo , et al. (362 additional authors not shown)

Abstract: The International Muon Collider Collaboration (IMCC) [1] was established in 2020 following the recommendations of the European Strategy for Particle Physics (ESPP) and the implementation of the European Strategy for Particle Physics-Accelerator R&D Roadmap by the Laboratory Directors Group [2], hereinafter referred to as the the European LDG roadmap. The Muon Collider Study (MuC) covers the accele… ▽ More The International Muon Collider Collaboration (IMCC) [1] was established in 2020 following the recommendations of the European Strategy for Particle Physics (ESPP) and the implementation of the European Strategy for Particle Physics-Accelerator R&D Roadmap by the Laboratory Directors Group [2], hereinafter referred to as the the European LDG roadmap. The Muon Collider Study (MuC) covers the accelerator complex, detectors and physics for a future muon collider. In 2023, European Commission support was obtained for a design study of a muon collider (MuCol) [3]. This project started on 1st March 2023, with work-packages aligned with the overall muon collider studies. In preparation of and during the 2021-22 U.S. Snowmass process, the muon collider project parameters, technical studies and physics performance studies were performed and presented in great detail. Recently, the P5 panel [4] in the U.S. recommended a muon collider R&D, proposed to join the IMCC and envisages that the U.S. should prepare to host a muon collider, calling this their "muon shot". In the past, the U.S. Muon Accelerator Programme (MAP) [5] has been instrumental in studies of concepts and technologies for a muon collider. △ Less

Submitted 28 January, 2025; v1 submitted 17 July, 2024; originally announced July 2024.

Comments: This document summarises the International Muon Collider Collaboration (IMCC) progress and status of the Muon Collider R&D programme

XENONnT WIMP Search: Signal & Background Modeling and Statistical Inference

Authors: XENON Collaboration, E. Aprile, J. Aalbers, K. Abe, S. Ahmed Maouloud, L. Althueser, B. Andrieu, E. Angelino, D. Antón Martin, F. Arneodo, L. Baudis, M. Bazyk, L. Bellagamba, R. Biondi, A. Bismark, K. Boese, A. Brown, G. Bruno, R. Budnik, J. M. R. Cardoso, A. P. Cimental Chávez, A. P. Colijn, J. Conrad, J. J. Cuenca-García, V. D'Andrea , et al. (139 additional authors not shown)

Abstract: The XENONnT experiment searches for weakly-interacting massive particle (WIMP) dark matter scattering off a xenon nucleus. In particular, XENONnT uses a dual-phase time projection chamber with a 5.9-tonne liquid xenon target, detecting both scintillation and ionization signals to reconstruct the energy, position, and type of recoil. A blind search for nuclear recoil WIMPs with an exposure of 1.1 t… ▽ More The XENONnT experiment searches for weakly-interacting massive particle (WIMP) dark matter scattering off a xenon nucleus. In particular, XENONnT uses a dual-phase time projection chamber with a 5.9-tonne liquid xenon target, detecting both scintillation and ionization signals to reconstruct the energy, position, and type of recoil. A blind search for nuclear recoil WIMPs with an exposure of 1.1 tonne-years (4.18 t fiducial mass) yielded no signal excess over background expectations, from which competitive exclusion limits were derived on WIMP-nucleon elastic scatter cross sections, for WIMP masses ranging from 6 GeV/$c^2$ up to the TeV/$c^2$ scale. This work details the modeling and statistical methods employed in this search. By means of calibration data, we model the detector response, which is then used to derive background and signal models. The construction and validation of these models is discussed, alongside additional purely data-driven backgrounds. We also describe the statistical inference framework, including the definition of the likelihood function and the construction of confidence intervals. △ Less

Submitted 3 June, 2025; v1 submitted 19 June, 2024; originally announced June 2024.

Comments: 21 pages, 11 figures

Offline tagging of radon-induced backgrounds in XENON1T and applicability to other liquid xenon detectors

Authors: E. Aprile, J. Aalbers, K. Abe, S. Ahmed Maouloud, L. Althueser, B. Andrieu, E. Angelino, J. R. Angevaare, D. Antón Martin, F. Arneodo, L. Baudis, A. L. Baxter, M. Bazyk, L. Bellagamba, R. Biondi, A. Bismark, E. J. Brookes, A. Brown, G. Bruno, R. Budnik, T. K. Bui, J. M. R. Cardoso, A. P. Cimental Chavez, A. P. Colijn, J. Conrad , et al. (142 additional authors not shown)

Abstract: This paper details the first application of a software tagging algorithm to reduce radon-induced backgrounds in liquid noble element time projection chambers, such as XENON1T and XENONnT. The convection velocity field in XENON1T was mapped out using $^{222}\text{Rn}$ and $^{218}\text{Po}$ events, and the root-mean-square convection speed was measured to be $0.30 \pm 0.01$ cm/s. Given this velocity… ▽ More This paper details the first application of a software tagging algorithm to reduce radon-induced backgrounds in liquid noble element time projection chambers, such as XENON1T and XENONnT. The convection velocity field in XENON1T was mapped out using $^{222}\text{Rn}$ and $^{218}\text{Po}$ events, and the root-mean-square convection speed was measured to be $0.30 \pm 0.01$ cm/s. Given this velocity field, $^{214}\text{Pb}$ background events can be tagged when they are followed by $^{214}\text{Bi}$ and $^{214}\text{Po}$ decays, or preceded by $^{218}\text{Po}$ decays. This was achieved by evolving a point cloud in the direction of a measured convection velocity field, and searching for $^{214}\text{Bi}$ and $^{214}\text{Po}$ decays or $^{218}\text{Po}$ decays within a volume defined by the point cloud. In XENON1T, this tagging system achieved a $^{214}\text{Pb}$ background reduction of $6.2^{+0.4}_{-0.9}\%$ with an exposure loss of $1.8\pm 0.2 \%$, despite the timescales of convection being smaller than the relevant decay times. We show that the performance can be improved in XENONnT, and that the performance of such a software-tagging approach can be expected to be further improved in a diffusion-limited scenario. Finally, a similar method might be useful to tag the cosmogenic $^{137}\text{Xe}$ background, which is relevant to the search for neutrinoless double-beta decay. △ Less

Submitted 19 June, 2024; v1 submitted 21 March, 2024; originally announced March 2024.

Comments: 17 pages, 19 figures

Journal ref: Phys.Rev.D 110 (2024) 012011

The XENONnT Dark Matter Experiment

Authors: XENON Collaboration, E. Aprile, J. Aalbers, K. Abe, S. Ahmed Maouloud, L. Althueser, B. Andrieu, E. Angelino, J. R. Angevaare, V. C. Antochi, D. Antón Martin, F. Arneodo, M. Balata, L. Baudis, A. L. Baxter, M. Bazyk, L. Bellagamba, R. Biondi, A. Bismark, E. J. Brookes, A. Brown, S. Bruenner, G. Bruno, R. Budnik, T. K. Bui , et al. (170 additional authors not shown)

Abstract: The multi-staged XENON program at INFN Laboratori Nazionali del Gran Sasso aims to detect dark matter with two-phase liquid xenon time projection chambers of increasing size and sensitivity. The XENONnT experiment is the latest detector in the program, planned to be an upgrade of its predecessor XENON1T. It features an active target of 5.9 tonnes of cryogenic liquid xenon (8.5 tonnes total mass in… ▽ More The multi-staged XENON program at INFN Laboratori Nazionali del Gran Sasso aims to detect dark matter with two-phase liquid xenon time projection chambers of increasing size and sensitivity. The XENONnT experiment is the latest detector in the program, planned to be an upgrade of its predecessor XENON1T. It features an active target of 5.9 tonnes of cryogenic liquid xenon (8.5 tonnes total mass in cryostat). The experiment is expected to extend the sensitivity to WIMP dark matter by more than an order of magnitude compared to XENON1T, thanks to the larger active mass and the significantly reduced background, improved by novel systems such as a radon removal plant and a neutron veto. This article describes the XENONnT experiment and its sub-systems in detail and reports on the detector performance during the first science run. △ Less

Submitted 13 August, 2025; v1 submitted 15 February, 2024; originally announced February 2024.

Comments: 32 pages, 20 figures; matches published version

Journal ref: Eur.Phys.J.C 84 (2024) 8, 784

Design and performance of the field cage for the XENONnT experiment

Authors: E. Aprile, K. Abe, S. Ahmed Maouloud, L. Althueser, B. Andrieu, E. Angelino, J. R. Angevaare, V. C. Antochi, D. Antón Martin, F. Arneodo, L. Baudis, A. L. Baxter, M. Bazyk, L. Bellagamba, R. Biondi, A. Bismark, E. J. Brookes, A. Brown, S. Bruenner, G. Bruno, R. Budnik, T. K. Bui, C. Cai, J. M. R. Cardoso, D. Cichon , et al. (139 additional authors not shown)

Abstract: The precision in reconstructing events detected in a dual-phase time projection chamber depends on an homogeneous and well understood electric field within the liquid target. In the XENONnT TPC the field homogeneity is achieved through a double-array field cage, consisting of two nested arrays of field shaping rings connected by an easily accessible resistor chain. Rather than being connected to t… ▽ More The precision in reconstructing events detected in a dual-phase time projection chamber depends on an homogeneous and well understood electric field within the liquid target. In the XENONnT TPC the field homogeneity is achieved through a double-array field cage, consisting of two nested arrays of field shaping rings connected by an easily accessible resistor chain. Rather than being connected to the gate electrode, the topmost field shaping ring is independently biased, adding a degree of freedom to tune the electric field during operation. Two-dimensional finite element simulations were used to optimize the field cage, as well as its operation. Simulation results were compared to ${}^{83m}\mathrm{Kr}$ calibration data. This comparison indicates an accumulation of charge on the panels of the TPC which is constant over time, as no evolution of the reconstructed position distribution of events is observed. The simulated electric field was then used to correct the charge signal for the field dependence of the charge yield. This correction resolves the inconsistent measurement of the drift electron lifetime when using different calibrations sources and different field cage tuning voltages. △ Less

Submitted 21 September, 2023; originally announced September 2023.

Journal ref: Eur. Phys. J. C 84, 138 (2024)

Search for events in XENON1T associated with Gravitational Waves

Authors: XENON Collaboration, E. Aprile, K. Abe, S. Ahmed Maouloud, L. Althueser, B. Andrieu, E. Angelino, J. R. Angevaare, V. C. Antochi, D. Antoń Martin, F. Arneodo, L. Baudis, A. L. Baxter, M. Bazyk, L. Bellagamba, R. Biondi, A. Bismark, E. J. Brookes, A. Brown, S. Bruenner, G. Bruno, R. Budnik, T. K. Bui, C. Cai, J. M. R. Cardoso , et al. (138 additional authors not shown)

Abstract: We perform a blind search for particle signals in the XENON1T dark matter detector that occur close in time to gravitational wave signals in the LIGO and Virgo observatories. No particle signal is observed in the nuclear recoil, electronic recoil, CE$ν$NS, and S2-only channels within $\pm$ 500 seconds of observations of the gravitational wave signals GW170104, GW170729, GW170817, GW170818, and GW1… ▽ More We perform a blind search for particle signals in the XENON1T dark matter detector that occur close in time to gravitational wave signals in the LIGO and Virgo observatories. No particle signal is observed in the nuclear recoil, electronic recoil, CE$ν$NS, and S2-only channels within $\pm$ 500 seconds of observations of the gravitational wave signals GW170104, GW170729, GW170817, GW170818, and GW170823. We use this null result to constrain mono-energetic neutrinos and Beyond Standard Model particles emitted in the closest coalescence GW170817, a binary neutron star merger. We set new upper limits on the fluence (time-integrated flux) of coincident neutrinos down to 17 keV at 90% confidence level. Furthermore, we constrain the product of coincident fluence and cross section of Beyond Standard Model particles to be less than $10^{-29}$ cm$^2$/cm$^2$ in the [5.5-210] keV energy range at 90% confidence level. △ Less

Submitted 27 October, 2023; v1 submitted 20 June, 2023; originally announced June 2023.

Searching for Heavy Dark Matter near the Planck Mass with XENON1T

Authors: E. Aprile, K. Abe, S. Ahmed Maouloud, L. Althueser, B. Andrieu, E. Angelino, J. R. Angevaare, V. C. Antochi, D. Antón Martin, F. Arneodo, L. Baudis, A. L. Baxter, M. Bazyk, L. Bellagamba, R. Biondi, A. Bismark, E. J. Brookes, A. Brown, S. Bruenner, G. Bruno, R. Budnik, T. K. Bui, C. Cai, J. M. R. Cardoso, D. Cichon , et al. (142 additional authors not shown)

Abstract: Multiple viable theoretical models predict heavy dark matter particles with a mass close to the Planck mass, a range relatively unexplored by current experimental measurements. We use 219.4 days of data collected with the XENON1T experiment to conduct a blind search for signals from Multiply-Interacting Massive Particles (MIMPs). Their unique track signature allows a targeted analysis with only 0.… ▽ More Multiple viable theoretical models predict heavy dark matter particles with a mass close to the Planck mass, a range relatively unexplored by current experimental measurements. We use 219.4 days of data collected with the XENON1T experiment to conduct a blind search for signals from Multiply-Interacting Massive Particles (MIMPs). Their unique track signature allows a targeted analysis with only 0.05 expected background events from muons. Following unblinding, we observe no signal candidate events. This work places strong constraints on spin-independent interactions of dark matter particles with a mass between 1$\times$10$^{12}\,$GeV/c$^2$ and 2$\times$10$^{17}\,$GeV/c$^2$. In addition, we present the first exclusion limits on spin-dependent MIMP-neutron and MIMP-proton cross-sections for dark matter particles with masses close to the Planck scale. △ Less

Submitted 21 April, 2023; originally announced April 2023.

Comments: 7 pages, 6 figures

Journal ref: Phys. Rev. Lett. 130, 261002 (2023)

First Dark Matter Search with Nuclear Recoils from the XENONnT Experiment

Authors: XENON Collaboration, E. Aprile, K. Abe, F. Agostini, S. Ahmed Maouloud, L. Althueser, B. Andrieu, E. Angelino, J. R. Angevaare, V. C. Antochi, D. Antón Martin, F. Arneodo, L. Baudis, A. L. Baxter, M. Bazyk, L. Bellagamba, R. Biondi, A. Bismark, E. J. Brookes, A. Brown, S. Bruenner, G. Bruno, R. Budnik, T. K. Bui, C. Cai , et al. (141 additional authors not shown)

Abstract: We report on the first search for nuclear recoils from dark matter in the form of weakly interacting massive particles (WIMPs) with the XENONnT experiment which is based on a two-phase time projection chamber with a sensitive liquid xenon mass of $5.9$ t. During the approximately 1.1 tonne-year exposure used for this search, the intrinsic $^{85}$Kr and $^{222}$Rn concentrations in the liquid targe… ▽ More We report on the first search for nuclear recoils from dark matter in the form of weakly interacting massive particles (WIMPs) with the XENONnT experiment which is based on a two-phase time projection chamber with a sensitive liquid xenon mass of $5.9$ t. During the approximately 1.1 tonne-year exposure used for this search, the intrinsic $^{85}$Kr and $^{222}$Rn concentrations in the liquid target were reduced to unprecedentedly low levels, giving an electronic recoil background rate of $(15.8\pm1.3)~\mathrm{events}/(\mathrm{t\cdot y \cdot keV})$ in the region of interest. A blind analysis of nuclear recoil events with energies between $3.3$ keV and $60.5$ keV finds no significant excess. This leads to a minimum upper limit on the spin-independent WIMP-nucleon cross section of $2.58\times 10^{-47}~\mathrm{cm}^2$ for a WIMP mass of $28~\mathrm{GeV}/c^2$ at $90\%$ confidence level. Limits for spin-dependent interactions are also provided. Both the limit and the sensitivity for the full range of WIMP masses analyzed here improve on previous results obtained with the XENON1T experiment for the same exposure. △ Less

Submitted 5 August, 2023; v1 submitted 26 March, 2023; originally announced March 2023.

Comments: Limit points are included in the submission file

Journal ref: Phys. Rev. Lett. 131, 041003 (2023)

Towards a Muon Collider

Authors: Carlotta Accettura, Dean Adams, Rohit Agarwal, Claudia Ahdida, Chiara Aimè, Nicola Amapane, David Amorim, Paolo Andreetto, Fabio Anulli, Robert Appleby, Artur Apresyan, Aram Apyan, Sergey Arsenyev, Pouya Asadi, Mohammed Attia Mahmoud, Aleksandr Azatov, John Back, Lorenzo Balconi, Laura Bandiera, Roger Barlow, Nazar Bartosik, Emanuela Barzi, Fabian Batsch, Matteo Bauce, J. Scott Berg , et al. (272 additional authors not shown)

Abstract: A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders desi… ▽ More A muon collider would enable the big jump ahead in energy reach that is needed for a fruitful exploration of fundamental interactions. The challenges of producing muon collisions at high luminosity and 10 TeV centre of mass energy are being investigated by the recently-formed International Muon Collider Collaboration. This Review summarises the status and the recent advances on muon colliders design, physics and detector studies. The aim is to provide a global perspective of the field and to outline directions for future work. △ Less

Submitted 27 November, 2023; v1 submitted 15 March, 2023; originally announced March 2023.

Comments: 118 pages, 103 figures

The Triggerless Data Acquisition System of the XENONnT Experiment

Authors: E. Aprile, J. Aalbers, K. Abe, F. Agostini, S. Ahmed Maouloud, L. Althueser, B. Andrieu, E. Angelino, J. R. Angevaare, V. C. Antochi, D. Antón Martin, F. Arneodo, L. Baudis, A. L. Baxter, L. Bellagamba, R. Biondi, A. Bismark, E. J. Brookes, A. Brown, S. Bruenner, G. Bruno, R. Budnik, T. K. Bui, C. Cai, J. M. R. Cardoso , et al. (140 additional authors not shown)

Abstract: The XENONnT detector uses the latest and largest liquid xenon-based time projection chamber (TPC) operated by the XENON Collaboration, aimed at detecting Weakly Interacting Massive Particles and conducting other rare event searches. The XENONnT data acquisition (DAQ) system constitutes an upgraded and expanded version of the XENON1T DAQ system. For its operation, it relies predominantly on commerc… ▽ More The XENONnT detector uses the latest and largest liquid xenon-based time projection chamber (TPC) operated by the XENON Collaboration, aimed at detecting Weakly Interacting Massive Particles and conducting other rare event searches. The XENONnT data acquisition (DAQ) system constitutes an upgraded and expanded version of the XENON1T DAQ system. For its operation, it relies predominantly on commercially available hardware accompanied by open-source and custom-developed software. The three constituent subsystems of the XENONnT detector, the TPC (main detector), muon veto, and the newly introduced neutron veto, are integrated into a single DAQ, and can be operated both independently and as a unified system. In total, the DAQ digitizes the signals of 698 photomultiplier tubes (PMTs), of which 253 from the top PMT array of the TPC are digitized twice, at $\times10$ and $\times0.5$ gain. The DAQ for the most part is a triggerless system, reading out and storing every signal that exceeds the digitization thresholds. Custom-developed software is used to process the acquired data, making it available within $\mathcal{O}\left(10\text{ s}\right)$ for live data quality monitoring and online analyses. The entire system with all the three subsystems was successfully commissioned and has been operating continuously, comfortably withstanding readout rates that exceed $\sim500$ MB/s during calibration. Livetime during normal operation exceeds $99\%$ and is $\sim90\%$ during most high-rate calibrations. The combined DAQ system has collected more than 2 PB of both calibration and science data during the commissioning of XENONnT and the first science run. △ Less

Submitted 21 December, 2022; originally announced December 2022.

Low-energy Calibration of XENON1T with an Internal $^{37}$Ar Source

Authors: E. Aprile, K. Abe, F. Agostini, S. Ahmed Maouloud, M. Alfonsi, L. Althueser, B. Andrieu, E. Angelino, J. R. Angevaare, V. C. Antochi, D. Antón Martin, F. Arneodo, L. Baudis, A. L. Baxter, L. Bellagamba, R. Biondi, A. Bismark, A. Brown, S. Bruenner, G. Bruno, R. Budnik, T. K. Bui, C. Cai, C. Capelli, J. M. R. Cardoso , et al. (139 additional authors not shown)

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, respecti… ▽ More 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$0.5) electrons/keV, respectively, in agreement with other measurements and with NEST predictions. The electron yield at 0.27 keV is also measured and it is (68.0$^{+6.3}_{-3.7}$) 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. △ Less

Submitted 21 March, 2023; v1 submitted 25 November, 2022; originally announced November 2022.

An approximate likelihood for nuclear recoil searches with XENON1T data

Authors: E. Aprile, K. Abe, F. Agostini, S. Ahmed Maouloud, M. Alfonsi, L. Althueser, B. Andrieu, E. Angelino, J. R. Angevaare, V. C. Antochi, D. Antón Martin, F. Arneodo, L. Baudis, A. L. Baxter, L. Bellagamba, R. Biondi, A. Bismark, A. Brown, S. Bruenner, G. Bruno, R. Budnik, C. Capelli, J. M. R. Cardoso, D. Cichon, B. Cimmino , et al. (129 additional authors not shown)

Abstract: The XENON collaboration has published stringent limits on specific dark matter -nucleon recoil spectra from dark matter recoiling on the liquid xenon detector target. In this paper, we present an approximate likelihood for the XENON1T 1 tonne-year nuclear recoil search applicable to any nuclear recoil spectrum. Alongside this paper, we publish data and code to compute upper limits using the method… ▽ More The XENON collaboration has published stringent limits on specific dark matter -nucleon recoil spectra from dark matter recoiling on the liquid xenon detector target. In this paper, we present an approximate likelihood for the XENON1T 1 tonne-year nuclear recoil search applicable to any nuclear recoil spectrum. Alongside this paper, we publish data and code to compute upper limits using the method we present. The approximate likelihood is constructed in bins of reconstructed energy, profiled along the signal expectation in each bin. This approach can be used to compute an approximate likelihood and therefore most statistical results for any nuclear recoil spectrum. Computing approximate results with this method is approximately three orders of magnitude faster than the likelihood used in the original publications of XENON1T, where limits were set for specific families of recoil spectra. Using this same method, we include toy Monte Carlo simulation-derived binwise likelihoods for the upcoming XENONnT experiment that can similarly be used to assess the sensitivity to arbitrary nuclear recoil signatures in its eventual 20 tonne-year exposure. △ Less

Submitted 13 October, 2022; originally announced October 2022.

Comments: Accepted by European Physical Journal C

Design, construction and commissioning of a high-flow radon removal system for XENONnT

Authors: M. Murra, D. Schulte, C. Huhmann, C. Weinheimer

Abstract: A high-flow radon removal system based on cryogenic distillation was developed and constructed to reduce radon-induced backgrounds in liquid xenon detectors for rare event searches such as XENONnT. A continuous purification of the XENONnT liquid xenon inventory of 8.4 tonnes at process flows up to 71 kg/h (200 slpm) is required to achieve a radon reduction by a factor two for radon sources inside… ▽ More A high-flow radon removal system based on cryogenic distillation was developed and constructed to reduce radon-induced backgrounds in liquid xenon detectors for rare event searches such as XENONnT. A continuous purification of the XENONnT liquid xenon inventory of 8.4 tonnes at process flows up to 71 kg/h (200 slpm) is required to achieve a radon reduction by a factor two for radon sources inside the detector. To reach such high flows, the distillation column's design features liquid xenon inlet and outlets along with novel custom-made bath-type heat exchangers with high liquefaction capabilities. The distillation process was designed using a modification of the McCabe-Thiele approach without a bottom product extraction. The thermodynamic concept is based on a Clausius-Rankine cooling cycle with phase-changing medium, in this case the xenon itself. To drastically reduce the external cooling power requirements, an energy efficient heat pump concept was developed applying a custom-made four cylinder magnetically-coupled piston pump as compressor. The distillation system was operated at thermodynamically stable conditions at a process flow of (91$\pm$2) kg/h ((258$\pm$6) slpm), 30 % over design. With this flow, a $^{222}$Rn activity concentration <1 $μ$Bq/kg is expected inside the XENONnT detector given the measured radon source distribution. △ Less

Submitted 23 May, 2022; originally announced May 2022.

A Work Proposal for a Collaborative Study of Magnet Technology for a Future Muon Collider

Authors: L. Bottura, D. Aguglia, B. Auchmann, T. Arndt, J. Beard, A. Bersani, F. Boattini, M. Breschi, B. Caiffi, X. Chaud, M. Dam, F. Debray, H. De Gersem, E. De Matteis, A. Dudarev, S. Farinon, A. Kario, R. Losito, S. Mariotto, M. Mentink, R. Musenich, T. Ogitsu, M. Prioli, L. Quettier, L. Rossi , et al. (8 additional authors not shown)

Abstract: In this paper we elaborate on the nature and challenges for the magnet systems of a muon collider as presently considered within the scope of the International Muon Collider Collaboration (IMCC). We outline the structure of the work proposed over the coming period of five years to study and demonstrate relevant magnet technology. The proposal, which is part of the overall work planned to establish… ▽ More In this paper we elaborate on the nature and challenges for the magnet systems of a muon collider as presently considered within the scope of the International Muon Collider Collaboration (IMCC). We outline the structure of the work proposed over the coming period of five years to study and demonstrate relevant magnet technology. The proposal, which is part of the overall work planned to establish feasibility of a muon collider, is in direct response to the recent recommendations received from the Laboratories Directors Group (LDG). The plan is to profit from joint activities, within the scope of the IMCC and beyond, implemented through direct and EU-funded contributions. △ Less

Submitted 29 March, 2022; v1 submitted 26 March, 2022; originally announced March 2022.

Comments: contribution to Snowmass 2021

The CLIC project

Authors: O. Brunner, P. N. Burrows, S. Calatroni, N. Catalan Lasheras, R. Corsini, G. D'Auria, S. Doebert, A. Faus-Golfe, A. Grudiev, A. Latina, T. Lefevre, G. Mcmonagle, J. Osborne, Y. Papaphilippou, A. Robson, C. Rossi, R. Ruber, D. Schulte, S. Stapnes, I. Syratchev, W. Wuensch

Abstract: The Compact Linear Collider (CLIC) is a multi-TeV high-luminosity linear e$^+$e$^-$-collider under development by the CLIC accelerator collaboration, hosted by CERN. The CLIC accelerator has been optimised for three energy stages at centre-of-mass energies 380 GeV, 1.5 TeV and 3 TeV. CLIC uses a novel two-beam acceleration technique, with normal-conducting accelerating structures operating in the… ▽ More The Compact Linear Collider (CLIC) is a multi-TeV high-luminosity linear e$^+$e$^-$-collider under development by the CLIC accelerator collaboration, hosted by CERN. The CLIC accelerator has been optimised for three energy stages at centre-of-mass energies 380 GeV, 1.5 TeV and 3 TeV. CLIC uses a novel two-beam acceleration technique, with normal-conducting accelerating structures operating in the range of 70-100 MV/m. The report describes recent achievements in accelerator design, technology development and prototyping, system tests and beam tests. Large-scale CLIC-specific beam tests have taken place, for example, at the CLIC Test Facility CTF3 at CERN, at the Accelerator Test Facility ATF2 at KEK, at the FACET facility at SLAC and at the FERMI facility in Trieste. Together, they demonstrate that all implications of the CLIC design parameters are well understood and reproducible in beam tests and prove that the CLIC performance goals are realistic. The implementation of CLIC near CERN has been investigated. Focusing on a staged approach starting at 380 GeV, this includes civil engineering aspects, electrical networks, cooling and ventilation and installation scheduling, transport. All CLIC studies have put emphasis on optimising cost and energy efficiency, and the resulting power and cost estimates are reported. The report follows very closely the accelerator project description in the CLIC Summary Report for the European Particle Physics Strategy update 2018-19. Detailed studies of the physics potential and detector for CLIC, and R&D on detector technologies, have been carried out by the CLIC detector and physics (CLICdp) collaboration. CLIC provides excellent sensitivity to Beyond Standard Model physics, through direct searches and via a broad set of precision measurements of Standard Model processes, particularly in the Higgs and top-quark sectors. △ Less

Submitted 18 April, 2022; v1 submitted 17 March, 2022; originally announced March 2022.

Comments: arXiv admin note: substantial text overlap with arXiv:1812.06018, arXiv:1903.08655

A Muon Collider Facility for Physics Discovery

Authors: D. Stratakis, N. Mokhov, M. Palmer, N. Pastrone, T. Raubenheimer, C. Rogers, D. Schulte, V. Shiltsev, J. Tang, A. Yamamoto, C. Aimè, M. A. Mahmoud, N. Bartosik, E. Barzi, A. Bersani, A. Bertolin, M. Bonesini, B. Caiffi, M. Casarsa, M. G. Catanesi, A. Cerri, C. Curatolo, M. Dam, H. Damerau, E. De Matteis , et al. (44 additional authors not shown)

Abstract: Muon colliders provide a unique route to deliver high energy collisions that enable discovery searches and precision measurements to extend our understanding of the fundamental laws of physics. The muon collider design aims to deliver physics reach at the highest energies with costs, power consumption and on a time scale that may prove favorable relative to other proposed facilities. In this conte… ▽ More Muon colliders provide a unique route to deliver high energy collisions that enable discovery searches and precision measurements to extend our understanding of the fundamental laws of physics. The muon collider design aims to deliver physics reach at the highest energies with costs, power consumption and on a time scale that may prove favorable relative to other proposed facilities. In this context, a new international collaboration has formed to further extend the design concepts and performance studies of such a machine. This effort is focused on delivering the elements of a $\sim$10 TeV center of mass (CM) energy design to explore the physics energy frontier. The path to such a machine may pass through lower energy options. Currently a 3 TeV CM stage is considered. Other energy stages could also be explored, e.g. an s-channel Higgs Factory operating at 125 GeV CM. We describe the status of the R&D and design effort towards such a machine and lay out a plan to bring these concepts to maturity as a tool for the high energy physics community. △ Less

Submitted 15 March, 2022; originally announced March 2022.

Comments: 23 pages, 3 figures. arXiv admin note: text overlap with arXiv:2201.07895

Future Circular Hadron Collider FCC-hh: Overview and Status

Authors: M. Benedikt, A. Chance, B. Dalena, D. Denisov, M. Giovannozzi, J. Gutleber, R. Losito, M. Mangano, T. Raubenheimer, W. Riegler, V. Shiltsev, D. Schulte, D. Tommasini, F. Zimmermann

Abstract: The Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. Its goal is to push the field to the next energy frontier beyond LHC, increasing by an order of magnitude the mass of particles that could be directly produced, and decreasing by an order of magnitude the subatomic distances to be studied. The FCC study covers two accelerators, namely,… ▽ More The Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. Its goal is to push the field to the next energy frontier beyond LHC, increasing by an order of magnitude the mass of particles that could be directly produced, and decreasing by an order of magnitude the subatomic distances to be studied. The FCC study covers two accelerators, namely, an energy-frontier hadron collider (FCC-hh) and a highest luminosity, high-energy lepton collider (FCC-ee). Both rings are hosted in the same 100 km tunnel infrastructure, replicating the CERN strategy for LEP and LHC, i.e. developing a lepton and a hadron ring sharing the same tunnel. This paper is devoted to the FCC-hh and summarizes the key features of the FCC-hh accelerator design, performance reach, and underlying technologies. The material presented in this paper builds on the conceptual design report published in 2019, and extends it, including also the progress made and the results achieved since then. △ Less

Submitted 15 March, 2022; originally announced March 2022.

Comments: Contribution to Snowmass 2021

Promising Technologies and R&D Directions for the Future Muon Collider Detectors

Authors: Sergo Jindariani, Federico Meloni, Nadia Pastrone, Chiara Aimè, Nazar Bartosik, Emanuela Barzi, Alessandro Bertolin, Alessandro Braghieri, Laura Buonincontri, Simone Calzaferri, Massimo Casarsa, Maria Gabriella Catanesi, Alessandro Cerri, Grigorios Chachamis, Anna Colaleo, Camilla Curatolo, Giacomo Da Molin, Jean-Pierre Delahaye, Biagio Di Micco, Tommaso Dorigo, Filippo Errico, Davide Fiorina, Alessio Gianelle, Carlo Giraldin, John Hauptman , et al. (36 additional authors not shown)

Abstract: Among the post-LHC generation of particle accelerators, the muon collider represents a unique machine with capability to provide very high energy leptonic collisions and to open the path to a vast and mostly unexplored physics programme. However, on the experimental side, such great physics potential is accompanied by unprecedented technological challenges, due to the fact that muons are unstable… ▽ More Among the post-LHC generation of particle accelerators, the muon collider represents a unique machine with capability to provide very high energy leptonic collisions and to open the path to a vast and mostly unexplored physics programme. However, on the experimental side, such great physics potential is accompanied by unprecedented technological challenges, due to the fact that muons are unstable particles. Their decay products interact with the machine elements and produce an intense flux of background particles that eventually reach the detector and may degrade its performance. In this paper, we present technologies that have a potential to match the challenging specifications of a muon collider detector and outline a path forward for the future R&D efforts. △ Less

Submitted 14 March, 2022; originally announced March 2022.

Comments: Contribution to Snowmass 2021, 27 pages, 15 figures

A Next-Generation Liquid Xenon Observatory for Dark Matter and Neutrino Physics

Authors: J. Aalbers, K. Abe, V. Aerne, F. Agostini, S. Ahmed Maouloud, D. S. Akerib, D. Yu. Akimov, J. Akshat, A. K. Al Musalhi, F. Alder, S. K. Alsum, L. Althueser, C. S. Amarasinghe, F. D. Amaro, A. Ames, T. J. Anderson, B. Andrieu, N. Angelides, E. Angelino, J. Angevaare, V. C. Antochi, D. Antón Martin, B. Antunovic, E. Aprile, H. M. Araújo , et al. (572 additional authors not shown)

Abstract: The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for Weakly Interacting Massive Particles (WIMPs), while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neut… ▽ More The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for Weakly Interacting Massive Particles (WIMPs), while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector. △ Less

Submitted 4 March, 2022; originally announced March 2022.

Comments: 77 pages, 40 figures, 1262 references

Report number: INT-PUB-22-003

Journal ref: J. Phys. G: Nucl. Part. Phys. 50 (2023) 013001

Cryogenic bath-type heat exchangers for ultra-pure noble gas applications

Authors: M. Murra, D. Schulte, I. Cristescu, J. -M. Disdier, C. Huhmann, D. Tatananni, C. Weinheimer

Abstract: Two cryogenic bath-type heat exchangers for ultra-pure noble gas applications were developed with particular emphasis on noble gas liquefaction in cryogenic distillation systems. The main objective was to construct heat exchangers for xenon from materials that do not emanate radon and that fulfill ultra-high vacuum standards. Therefore, only high-quality copper and stainless steel materials were u… ▽ More Two cryogenic bath-type heat exchangers for ultra-pure noble gas applications were developed with particular emphasis on noble gas liquefaction in cryogenic distillation systems. The main objective was to construct heat exchangers for xenon from materials that do not emanate radon and that fulfill ultra-high vacuum standards. Therefore, only high-quality copper and stainless steel materials were used. Especially, large-area oxygen-free copper fins with high conductivity in a new design ensure efficient heat transfer. One bath-type Xe-Xe heat exchanger was designed with a diameter of 50 cm to achieve a xenon condensing capacity of at least 100 kg/h. In order to guarantee the necessary heat transfer between the two xenon reservoirs, this heat exchanger features a specially manufactured stainless steel flange with a copper plate welded inside. We first tested our concept on a dedicated bath-type heat exchanger with a reduced diameter of 30 cm using liquid nitrogen to liquefy the xenon. A model based on conservative assumptions such as film boiling on the nitrogen side and film condensation on the xenon side was developed and applied to caluclate the expected heat transfer for our design. We were able to demonstrate an adjustable xenon liquefaction rate of up to 113 kg/h limited only by our measurement procedure at a cooling efficiency of $(0.98\pm 0.03)$ for the LN$_2$-Xe heat exchanger. △ Less

Submitted 2 March, 2022; originally announced March 2022.

Journal ref: 2022 JINST 17 P05037

European Strategy for Particle Physics -- Accelerator R&D Roadmap

Authors: C. Adolphsen, D. Angal-Kalinin, T. Arndt, M. Arnold, R. Assmann, B. Auchmann, K. Aulenbacher, A. Ballarino, B. Baudouy, P. Baudrenghien, M. Benedikt, S. Bentvelsen, A. Blondel, A. Bogacz, F. Bossi, L. Bottura, S. Bousson, O. Brüning, R. Brinkmann, M. Bruker, O. Brunner, P. N. Burrows, G. Burt, S. Calatroni, K. Cassou , et al. (111 additional authors not shown)

Abstract: The 2020 update of the European Strategy for Particle Physics emphasised the importance of an intensified and well-coordinated programme of accelerator R&D, supporting the design and delivery of future particle accelerators in a timely, affordable and sustainable way. This report sets out a roadmap for European accelerator R&D for the next five to ten years, covering five topical areas identified… ▽ More The 2020 update of the European Strategy for Particle Physics emphasised the importance of an intensified and well-coordinated programme of accelerator R&D, supporting the design and delivery of future particle accelerators in a timely, affordable and sustainable way. This report sets out a roadmap for European accelerator R&D for the next five to ten years, covering five topical areas identified in the Strategy update. The R&D objectives include: improvement of the performance and cost-performance of magnet and radio-frequency acceleration systems; investigations of the potential of laser / plasma acceleration and energy-recovery linac techniques; and development of new concepts for muon beams and muon colliders. The goal of the roadmap is to document the collective view of the field on the next steps for the R&D programme, and to provide the evidence base to support subsequent decisions on prioritisation, resourcing and implementation. △ Less

Submitted 30 March, 2022; v1 submitted 19 January, 2022; originally announced January 2022.

Comments: 270 pages, 58 figures. Editor: N. Mounet. LDG chair: D. Newbold. Panel chairs: P. Védrine (HFM), S. Bousson (RF), R. Assmann (plasma), D. Schulte (muon), M. Klein (ERL). Panel editors: B. Baudouy (HFM), L. Bottura (HFM), S. Bousson (RF), G. Burt (RF), R. Assmann (plasma), E. Gschwendtner (plasma), R. Ischebeck (plasma), C. Rogers (muon), D. Schulte (muon), M. Klein (ERL)

Report number: CERN-2022-001

Journal ref: European Strategy for Particle Physics - Accelerator R&D Roadmap, N. Mounet (ed.), CERN Yellow Reports: Monographs, CERN-2022-001 (CERN, Geneva, 2022)

Application and modeling of an online distillation method to reduce krypton and argon in XENON1T

Authors: E. Aprile, K. Abe, F. Agostini, S. Ahmed Maouloud, M. Alfonsi, L. Althueser, E. Angelino, J. R. Angevaare, V. C. Antochi, D. Antón Martin, F. Arneodo, L. Baudis, A. L. Baxter, L. Bellagamba, A. Bernard, R. Biondi, A. Bismark, A. Brown, S. Bruenner, G. Bruno, R. Budnik, C. Capelli, J. M. R. Cardoso, D. Cichon, B. Cimmino , et al. (129 additional authors not shown)

Abstract: A novel online distillation technique was developed for the XENON1T dark matter experiment to reduce intrinsic background components more volatile than xenon, such as krypton or argon, while the detector was operating. The method is based on a continuous purification of the gaseous volume of the detector system using the XENON1T cryogenic distillation column. A krypton-in-xenon concentration of… ▽ More A novel online distillation technique was developed for the XENON1T dark matter experiment to reduce intrinsic background components more volatile than xenon, such as krypton or argon, while the detector was operating. The method is based on a continuous purification of the gaseous volume of the detector system using the XENON1T cryogenic distillation column. A krypton-in-xenon concentration of $(360 \pm 60)$ ppq was achieved. It is the lowest concentration measured in the fiducial volume of an operating dark matter detector to date. A model was developed and fit to the data to describe the krypton evolution in the liquid and gas volumes of the detector system for several operation modes over the time span of 550 days, including the commissioning and science runs of XENON1T. The online distillation was also successfully applied to remove Ar-37 after its injection for a low energy calibration in XENON1T. This makes the usage of Ar-37 as a regular calibration source possible in the future. The online distillation can be applied to next-generation experiments to remove krypton prior to, or during, any science run. The model developed here allows further optimization of the distillation strategy for future large scale detectors. △ Less

Submitted 14 June, 2022; v1 submitted 22 December, 2021; originally announced December 2021.

Journal ref: Prog Theor Exp Phys (2022)

Emission of Single and Few Electrons in XENON1T and Limits on Light Dark Matter

Authors: E. Aprile, K. Abe, F. Agostini, S. Ahmed Maouloud, M. Alfonsi, L. Althueser, E. Angelino, J. R. Angevaare, V. C. Antochi, D. Antón Martin, F. Arneodo, L. Baudis, A. L. Baxter, L. Bellagamba, A. Bernard, R. Biondi, A. Bismark, A. Brown, S. Bruenner, G. Bruno, R. Budnik, C. Capelli, J. M. R. Cardoso, D. Cichon, B. Cimmino , et al. (130 additional authors not shown)

Abstract: Delayed single- and few-electron emissions plague dual-phase time projection chambers, limiting their potential to search for light-mass dark matter. This paper examines the origins of these events in the XENON1T experiment. Characterization of the intensity of delayed electron backgrounds shows that the resulting emissions are correlated, in time and position, with high-energy events and can effe… ▽ More Delayed single- and few-electron emissions plague dual-phase time projection chambers, limiting their potential to search for light-mass dark matter. This paper examines the origins of these events in the XENON1T experiment. Characterization of the intensity of delayed electron backgrounds shows that the resulting emissions are correlated, in time and position, with high-energy events and can effectively be vetoed. In this work we extend previous S2-only analyses down to a single electron. From this analysis, after removing the correlated backgrounds, we observe rates < 30 events/(electron*kg*day) in the region of interest spanning 1 to 5 electrons. We derive 90% confidence upper limits for dark matter-electron scattering, first direct limits on the electric dipole, magnetic dipole, and anapole interactions, and bosonic dark matter models, where we exclude new parameter space for dark photons and solar dark photons. △ Less

Submitted 2 September, 2024; v1 submitted 22 December, 2021; originally announced December 2021.

Comments: 20 pages, 17 figures, Updated to correct published Solar Dark Photon limit

Journal ref: Phys. Rev. D 106, 022001 (2022)

Material radiopurity control in the XENONnT experiment

Authors: E. Aprile, K. Abe, F. Agostini, S. Ahmed Maouloud, M. Alfonsi, L. Althueser, E. Angelino, J. R. Angevaare, V. C. Antochi, D. Antón Martin, F. Arneodo, L. Baudis, A. L. Baxter, L. Bellagamba, R. Biondi, A. Bismark, A. Brown, S. Bruenner, G. Bruno, R. Budnik, C. Capelli, J. M. R. Cardoso, D. Cichon, B. Cimmino, M. Clark , et al. (128 additional authors not shown)

Abstract: The selection of low-radioactive construction materials is of the utmost importance for rare-event searches and thus critical to the XENONnT experiment. Results of an extensive radioassay program are reported, in which material samples have been screened with gamma-ray spectroscopy, mass spectrometry, and $^{222}$Rn emanation measurements. Furthermore, the cleanliness procedures applied to remove… ▽ More The selection of low-radioactive construction materials is of the utmost importance for rare-event searches and thus critical to the XENONnT experiment. Results of an extensive radioassay program are reported, in which material samples have been screened with gamma-ray spectroscopy, mass spectrometry, and $^{222}$Rn emanation measurements. Furthermore, the cleanliness procedures applied to remove or mitigate surface contamination of detector materials are described. Screening results, used as inputs for a XENONnT Monte Carlo simulation, predict a reduction of materials background ($\sim$17%) with respect to its predecessor XENON1T. Through radon emanation measurements, the expected $^{222}$Rn activity concentration in XENONnT is determined to be 4.2$\,(^{+0.5}_{-0.7})\,μ$Bq/kg, a factor three lower with respect to XENON1T. This radon concentration will be further suppressed by means of the novel radon distillation system. △ Less

Submitted 26 January, 2023; v1 submitted 10 December, 2021; originally announced December 2021.

Ultra-clean radon-free four cylinder magnetically-coupled piston pump

Authors: D. Schulte, M. Murra, P. Schulte, C. Huhmann, C. Weinheimer

Abstract: A high performance gas displacement pump based on four individual cylinders was developed. The magnetically-coupled pistons and the hermetically-sealed housings as well as the special cleanliness in terms of out-gassing and radio-purity make the four cylinder pump interesting for the usage in low background experiments dealing with noble gases as target. An optimized inner flow path as well as red… ▽ More A high performance gas displacement pump based on four individual cylinders was developed. The magnetically-coupled pistons and the hermetically-sealed housings as well as the special cleanliness in terms of out-gassing and radio-purity make the four cylinder pump interesting for the usage in low background experiments dealing with noble gases as target. An optimized inner flow path as well as reduced dead volume with respect to the prototype single cylinder pump of the XENON1T experiment combined with advanced polymer piston gaskets and a piston coupling force of (3177 $\pm$ 162) N ensures a high and reliable performance. Furthermore, a phase-shifted synchronization of the pistons' movement creates an additional performance boost as well as minimizes fluctuations of flow and compression. The pump is able to generate xenon flows of 474 slpm at a pressure difference of 1.80 bar. △ Less

Submitted 19 August, 2021; v1 submitted 1 July, 2021; originally announced July 2021.

Journal ref: 2021 JINST 16 P09011

Reflectivity of VUV-sensitive Silicon Photomultipliers in Liquid Xenon

Authors: M. Wagenpfeil, T. Ziegler, J. Schneider, A. Fieguth, M. Murra, D. Schulte, L. Althueser, C. Huhmann, C. Weinheimer, T. Michel, G. Anton, G. Adhikari, S. Al Kharusi, E. Angelico, I. J. Arnquist, I. Badhrees, J. Bane, D. Beck, V. Belov, T. Bhatta, A. Bolotnikov, P. A. Breur, J. P. Brodsky, E. Brown, T. Brunner , et al. (118 additional authors not shown)

Abstract: Silicon photomultipliers are regarded as a very promising technology for next-generation, cutting-edge detectors for low-background experiments in particle physics. This work presents systematic reflectivity studies of Silicon Photomultipliers (SiPM) and other samples in liquid xenon at vacuum ultraviolet (VUV) wavelengths. A dedicated setup at the University of Münster has been used that allows t… ▽ More Silicon photomultipliers are regarded as a very promising technology for next-generation, cutting-edge detectors for low-background experiments in particle physics. This work presents systematic reflectivity studies of Silicon Photomultipliers (SiPM) and other samples in liquid xenon at vacuum ultraviolet (VUV) wavelengths. A dedicated setup at the University of Münster has been used that allows to acquire angle-resolved reflection measurements of various samples immersed in liquid xenon with 0.45° angular resolution. Four samples are investigated in this work: one Hamamatsu VUV4 SiPM, one FBK VUV-HD SiPM, one FBK wafer sample and one Large-Area Avalanche Photodiode (LA-APD) from EXO-200. The reflectivity is determined to be 25-36% at an angle of incidence of 20° for the four samples and increases to up to 65% at 70° for the LA-APD and the FBK samples. The Hamamatsu VUV4 SiPM shows a decline with increasing angle of incidence. The reflectivity results will be incorporated in upcoming light response simulations of the nEXO detector. △ Less

Submitted 26 May, 2021; v1 submitted 16 April, 2021; originally announced April 2021.

Comments: 18 pages, 11 figures

$γγ$ Beam-beam Parameter Study for a 3 TeV PWFA Linear Collider

Authors: Jian Bin Ben Chen, Daniel Schulte, Erik Adli

Abstract: Our beam-beam parameter study using beam-beam simulations and PWFA (particle-driven plasma acceleration) beam parameters indicates that at 3 TeV, for examined electron beam lengths ${2~μ\mathrm{m}\leqσ_z\leq 10~μ\mathrm{m}}$, the total luminosity, as well as the sharpness of the luminosity spectrum for a $γγ$ collider are independent of the beam length of the electron beams used to scatter the pho… ▽ More Our beam-beam parameter study using beam-beam simulations and PWFA (particle-driven plasma acceleration) beam parameters indicates that at 3 TeV, for examined electron beam lengths ${2~μ\mathrm{m}\leqσ_z\leq 10~μ\mathrm{m}}$, the total luminosity, as well as the sharpness of the luminosity spectrum for a $γγ$ collider are independent of the beam length of the electron beams used to scatter the photons, given that the hourglass effect is avoided. The total luminosity can consequently be maximised by minimising the horizontal and vertical beta functions $β_{x,y}^*$ at the interaction point. Furthermore, we performed background studies in GUINEA-PIG where we considered the smallest currently achievable $β_{x,y}^*$ combined with PWFA beam parameters. Simulations results show that our proposed parameter set for a 3 TeV PWFA $γγ$ collider is able to deliver a total luminosity significantly higher than a $γγ$ collider based on CLIC parameters, but gives rise to more background particles. △ Less

Submitted 1 October, 2020; originally announced October 2020.

$^{222}$Rn emanation measurements for the XENON1T experiment

Authors: E. Aprile, J. Aalbers, F. Agostini, M. Alfonsi, L. Althueser, F. D. Amaro, V. C. Antochi, E. Angelino, J. R. Angevaare, F. Arneodo, D. Barge, L. Baudis, B. Bauermeister, L. Bellagamba, M. L. Benabderrahmane, T. Berger, P. A. Breur, A. Brown, E. Brown, S. Bruenner, G. Bruno, R. Budnik, C. Capelli, J. M. R. Cardoso, D. Cichon , et al. (118 additional authors not shown)

Abstract: The selection of low-radioactive construction materials is of utmost importance for the success of low-energy rare event search experiments. Besides radioactive contaminants in the bulk, the emanation of radioactive radon atoms from material surfaces attains increasing relevance in the effort to further reduce the background of such experiments. In this work, we present the $^{222}$Rn emanation me… ▽ More The selection of low-radioactive construction materials is of utmost importance for the success of low-energy rare event search experiments. Besides radioactive contaminants in the bulk, the emanation of radioactive radon atoms from material surfaces attains increasing relevance in the effort to further reduce the background of such experiments. In this work, we present the $^{222}$Rn emanation measurements performed for the XENON1T dark matter experiment. Together with the bulk impurity screening campaign, the results enabled us to select the radio-purest construction materials, targeting a $^{222}$Rn activity concentration of 10 $μ$Bq/kg in 3.2 t of xenon. The knowledge of the distribution of the $^{222}$Rn sources allowed us to selectively eliminate critical components in the course of the experiment. The predictions from the emanation measurements were compared to data of the $^{222}$Rn activity concentration in XENON1T. The final $^{222}$Rn activity concentration of (4.5 $\pm$ 0.1) $μ$Bq/kg in the target of XENON1T is the lowest ever achieved in a xenon dark matter experiment. △ Less

Submitted 25 November, 2020; v1 submitted 29 September, 2020; originally announced September 2020.

Comments: 14 pages, 3 figures

Journal ref: Eur. Phys. J. C 81, 337 (2021)

$\mathrm{e}^+$$\mathrm{e}^-$ Beam-beam Parameter Study for a TeV-scale PWFA Linear Collider

Authors: Jian Bin Ben Chen, Daniel Schulte, Erik Adli

Abstract: We perform a beam-beam parameter study for a TeV-scale PWFA (particle-driven plasma wakefield acceleration) $\mathrm{e}^+$$\mathrm{e}^-$ linear collider using GUINEA-PIG simulations. The study shows that the total luminosity follows the $1/\sqrt{σ_z}$-scaling predicted by beamstrahlung theory, where $σ_z$ is the rms beam length, which is advantageous for PWFA, as short beam lengths are preferred.… ▽ More We perform a beam-beam parameter study for a TeV-scale PWFA (particle-driven plasma wakefield acceleration) $\mathrm{e}^+$$\mathrm{e}^-$ linear collider using GUINEA-PIG simulations. The study shows that the total luminosity follows the $1/\sqrt{σ_z}$-scaling predicted by beamstrahlung theory, where $σ_z$ is the rms beam length, which is advantageous for PWFA, as short beam lengths are preferred. We also derive a parameter set for a 3 TeV PWFA linear collider with main beam parameters optimised for luminosity and luminosity spread introduced by beamstrahlung. Lastly, the study also compare the performance for scenarios with reduced positron beam charge at 3 TeV and 14 TeV with CLIC parameters. △ Less

Submitted 9 February, 2021; v1 submitted 28 September, 2020; originally announced September 2020.

A primary electron beam facility at CERN -- eSPS Conceptual design report

Authors: M. Aicheler, T. Akesson, F. Antoniou, A. Arnalich, P. A. Arrutia Sota, P. Bettencourt Moniz Cabral, D. Bozzini, M. Brugger, O. Brunner, P. N. Burrows, R. Calaga, M. J. Capstick, R. Corsini, S. Doebert, L. A. Dougherty, Y. Dutheil, L. A. Dyks, O. Etisken, L. Evans, A. Farricker, R. Fernandez Ortega, M. A. Fraser, J. Gall, S. J. Gessner, B. Goddard , et al. (30 additional authors not shown)

Abstract: The design of a primary electron beam facility at CERN is described. The study has been carried out within the framework of the wider Physics Beyond Colliders study. It re-enables the Super Proton Synchrotron (SPS) as an electron accelerator, and leverages the development invested in Compact Linear Collider (CLIC) technology for its injector and as an accelerator research and development infrastru… ▽ More The design of a primary electron beam facility at CERN is described. The study has been carried out within the framework of the wider Physics Beyond Colliders study. It re-enables the Super Proton Synchrotron (SPS) as an electron accelerator, and leverages the development invested in Compact Linear Collider (CLIC) technology for its injector and as an accelerator research and development infrastructure. The facility would be relevant for several of the key priorities in the 2020 update of the European Strategy for Particle Physics, such as an electron-positron Higgs factory, accelerator R\&D, dark sector physics, and neutrino physics. In addition, it could serve experiments in nuclear physics. The electron beam delivered by this facility would provide access to light dark matter production significantly beyond the targets predicted by a thermal dark matter origin, and for natures of dark matter particles that are not accessible by direct detection experiments. It would also enable electro-nuclear measurements crucial for precise modelling the energy dependence of neutrino-nucleus interactions, which is needed to precisely measure neutrino oscillations as a function of energy. The implementation of the facility is the natural next step in the development of X-band high-gradient acceleration technology, a key technology for compact and cost-effective electron/positron linacs. It would also become the only facility with multi-GeV drive bunches and truly independent electron witness bunches for plasma wakefield acceleration. A second phase capable to deliver positron witness bunches would make it a complete facility for plasma wakefield collider studies. [...] △ Less

Submitted 21 December, 2020; v1 submitted 15 September, 2020; originally announced September 2020.

Surrogate Modeling of the CLIC Final-Focus System using Artificial Neural Networks

Authors: J. Ogren, C. Gohil, D. Schulte

Abstract: Artificial neural networks can be used for creating surrogate models that can replace computationally expensive simulations. In this paper, a surrogate model was created for a subset of the Compact Linear Collider (CLIC) final-focus system. By training on simulation data, we created a model that maps sextupole offsets to luminosity and beam sizes, thus replacing computationally intensive tracking… ▽ More Artificial neural networks can be used for creating surrogate models that can replace computationally expensive simulations. In this paper, a surrogate model was created for a subset of the Compact Linear Collider (CLIC) final-focus system. By training on simulation data, we created a model that maps sextupole offsets to luminosity and beam sizes, thus replacing computationally intensive tracking and beam-beam simulations. This model was then used for optimizing the parameters of a random walk procedure for sextupole alignment. △ Less

Submitted 23 February, 2021; v1 submitted 14 September, 2020; originally announced September 2020.

Comments: 18 pages, 10 figures

Measurements and modelling of stray magnetic fields and the simulation of their impact on the Compact Linear Collider at 380 GeV

Authors: C. Gohil, P. N. Burrows, N. Blaskovic Kraljevic, D. Schulte, B. Heilig

Abstract: The Compact Linear Collider (CLIC) targets a nanometre beam size at the collision point. Realising this beam size requires the generation and transport of ultra-low emittance beams. Dynamic imperfections can deflect the colliding beams, leading to a collision with a relative offset. They can also degrade the emittance of each beam. Both of these effects can significantly impact the luminosity of C… ▽ More The Compact Linear Collider (CLIC) targets a nanometre beam size at the collision point. Realising this beam size requires the generation and transport of ultra-low emittance beams. Dynamic imperfections can deflect the colliding beams, leading to a collision with a relative offset. They can also degrade the emittance of each beam. Both of these effects can significantly impact the luminosity of CLIC. In this paper, we examine a newly considered dynamic imperfection: stray magnetic fields. Measurements of stray magnetic fields in the Large Hadron Collider tunnel are presented and used to develop a statistical model that can be used to realistically generate stray magnetic fields in simulations. The model is used in integrated simulations of CLIC at 380GeV including mitigation systems for stray magnetic fields to evaluate their impact on luminosity. △ Less

Submitted 11 December, 2020; v1 submitted 3 September, 2020; originally announced September 2020.

Journal ref: Phys. Rev. Accel. Beams 24, 011001 (2021)

Measurements of sub-nT dynamic magnetic field shielding with soft iron and mu-metal for use in linear colliders

Authors: C. Gohil, P. N. Burrows, N. Blaskovic Kraljevic, D. Schulte, B. Heilig

Abstract: There is an increasing need to shield beams and accelerator elements from stray magnetic fields. The application of magnetic shielding in linear colliders is discussed. The shielding performance of soft iron and mu-metal is measured for magnetic fields of varying amplitude and frequency. Special attention is given to characterise the shielding performance for very small-amplitude magnetic fields. There is an increasing need to shield beams and accelerator elements from stray magnetic fields. The application of magnetic shielding in linear colliders is discussed. The shielding performance of soft iron and mu-metal is measured for magnetic fields of varying amplitude and frequency. Special attention is given to characterise the shielding performance for very small-amplitude magnetic fields. △ Less

Submitted 11 December, 2020; v1 submitted 3 September, 2020; originally announced September 2020.

Luminosity Performance of the Compact Linear Collider at 380 GeV with Static and Dynamic Imperfections

Authors: C. Gohil, P. N. Burrows, N. Blaskovic Kraljevic, A. Latina, J. Ögren, D. Schulte

Abstract: The Compact Linear Collider is one of the two main European options for a collider in a post Large Hadron Collider era. This is a linear $e^+e^-$ collider with three centre-of-mass energy stages: 380 GeV, 1.5 TeV and 3 TeV. The luminosity performance of the first stage at 380 GeV is presented including the impact of static and dynamic imperfections. These calculations are performed with fully real… ▽ More The Compact Linear Collider is one of the two main European options for a collider in a post Large Hadron Collider era. This is a linear $e^+e^-$ collider with three centre-of-mass energy stages: 380 GeV, 1.5 TeV and 3 TeV. The luminosity performance of the first stage at 380 GeV is presented including the impact of static and dynamic imperfections. These calculations are performed with fully realistic tracking simulations from the exit of the damping rings to the interaction point and including beam-beam effects in the collisions. A luminosity of $4.3\times10^{34}\,\text{cm}^{-2}\text{s}^{-1}$ can be achieved with a perfect collider, which is almost three times the nominal luminosity target of $1.5\times10^{34}\,\text{cm}^{-2}\text{s}^{-1}$. In simulations with static imperfections, a luminosity of $2.35\times10^{34}\,\text{cm}^{-2}\text{s}^{-1}$ or greater is achieved by 90% of randomly misaligned colliders. Expressed as a percentage of the nominal luminosity target, this is a surplus of approximately 57%. Including the impact of ground motion, a luminosity surplus of 53% or greater can be expected for 90% of colliders. The average expected luminosity is $2.8\times10^{34}~\text{cm}^{-2}\text{s}^{-1}$, which is almost twice the nominal luminosity target. △ Less

Submitted 2 September, 2020; originally announced September 2020.

Journal ref: Phys. Rev. Accel. Beams 23, 101001 (2020)

Muon Colliders: Opening New Horizons for Particle Physics

Authors: Kenneth Long, Donatella Lucchesi, Mark Palmer, Nadia Pastrone, Daniel Schulte, Vladimir Shiltsev

Abstract: Particle colliders have arguably been the most important instruments for particle physics over the past 50 years. As they became more powerful, they were used to push the frontier of our knowledge into previously uncharted territory. The LHC, the highest energy collider to date, at which the Higgs boson was discovered, is a prime example. To continue along the road into the Terra Promissa beyond t… ▽ More Particle colliders have arguably been the most important instruments for particle physics over the past 50 years. As they became more powerful, they were used to push the frontier of our knowledge into previously uncharted territory. The LHC, the highest energy collider to date, at which the Higgs boson was discovered, is a prime example. To continue along the road into the Terra Promissa beyond the Standard Model requires colliders with energy reach even greater than that of the LHC. Beams of muons offer enormous potential for the exploration of the energy frontier. Since the muon is a fundamental particle, its full energy is available in collisions in contrast to protons which are composed of quarks and gluons. However, muon beams decay rapidly, which presents a special challenge for a collider. Recent research indicates that the technologies required to overcome this challenge are within our grasp and may offer a cost-effective and energy-efficient option to continue our explorations. A new international collaboration is forming to bring together the diverse expertise and complementary capabilities from around the world to realize the muon collider as the next-generation energy-frontier discovery machine. △ Less

Submitted 30 July, 2020; originally announced July 2020.

Comments: 12 pages, 5 figures

Journal ref: Nature Physics, v.17, p.289, 2021

FCC-hh Experimental Insertion Region Design

Authors: Jose L. Abelleira, Robert B. Appleby, Sergey Arsenyev, Javier Barranco, Michael Benedikt, Maria Ilaria Besana, Oscar Blanco Garcia, Manuela Boscolo, David Boutin, Xavier Buffat, Helmut Burkhardt, Francesco Cerutti, Antoine Chance, Francesco Collamati, Emilia Cruz-Alaniz, Barbara Dalena, Michael Hofer, Barbara L. Humann, Angelo Infantino, Jacqueline Keintzel, Andy Langner, Marian Luckhof, Roman Martin, Tatiana Pieloni, Haroon Rafique , et al. (7 additional authors not shown)

Abstract: The Future Circular Collider study is exploring possible designs of circular colliders for the post-LHC era, as recommended by the European Strategy Group for High Energy Physics. One such option is FCC-hh, a proton-proton collider with a centre-of-mass energy of 100 TeV. The experimental insertion regions are key areas defining the performance of the collider. This paper presents the first insert… ▽ More The Future Circular Collider study is exploring possible designs of circular colliders for the post-LHC era, as recommended by the European Strategy Group for High Energy Physics. One such option is FCC-hh, a proton-proton collider with a centre-of-mass energy of 100 TeV. The experimental insertion regions are key areas defining the performance of the collider. This paper presents the first insertion region designs with a complete assessment of the main challenges, as collision debris with two orders of magnitude larger power than current colliders, beam-beam interactions in long insertions, dynamic aperture for optics with peak $β$ functions one order of magnitude above current colliders, photon background from synchrotron radiation and cross talk between the insertion regions. An alternative design avoiding the use of crab cavities with a small impact on performance is also presented. △ Less

Submitted 23 July, 2020; originally announced July 2020.

Comments: 74 pages

Projected WIMP Sensitivity of the XENONnT Dark Matter Experiment

Authors: The XENON collaboration, E. Aprile, J. Aalbers, F. Agostini, M. Alfonsi, L. Althueser, F. D. Amaro, V. C. Antochi, E. Angelino, J. R. Angevaare, F. Arneodo, D. Barge, L. Baudis, B. Bauermeister, L. Bellagamba, M. L. Benabderrahmane, T. Berger, A. Brown, E. Brown, S. Bruenner, G. Bruno, R. Budnik, C. Capelli, J. M. R. Cardoso, D. Cichon , et al. (115 additional authors not shown)

Abstract: XENONnT is a dark matter direct detection experiment, utilizing 5.9 t of instrumented liquid xenon, located at the INFN Laboratori Nazionali del Gran Sasso. In this work, we predict the experimental background and project the sensitivity of XENONnT to the detection of weakly interacting massive particles (WIMPs). The expected average differential background rate in the energy region of interest, c… ▽ More XENONnT is a dark matter direct detection experiment, utilizing 5.9 t of instrumented liquid xenon, located at the INFN Laboratori Nazionali del Gran Sasso. In this work, we predict the experimental background and project the sensitivity of XENONnT to the detection of weakly interacting massive particles (WIMPs). The expected average differential background rate in the energy region of interest, corresponding to (1, 13) keV and (4, 50) keV for electronic and nuclear recoils, amounts to $12.3 \pm 0.6$ (keV t y)$^{-1}$ and $(2.2\pm 0.5)\times 10^{-3}$ (keV t y)$^{-1}$, respectively, in a 4 t fiducial mass. We compute unified confidence intervals using the profile construction method, in order to ensure proper coverage. With the exposure goal of 20 t$\,$y, the expected sensitivity to spin-independent WIMP-nucleon interactions reaches a cross-section of $1.4\times10^{-48}$ cm$^2$ for a 50 GeV/c$^2$ mass WIMP at 90% confidence level, more than one order of magnitude beyond the current best limit, set by XENON1T. In addition, we show that for a 50 GeV/c$^2$ WIMP with cross-sections above $2.6\times10^{-48}$ cm$^2$ ($5.0\times10^{-48}$ cm$^2$) the median XENONnT discovery significance exceeds 3$σ$ (5$σ$). The expected sensitivity to the spin-dependent WIMP coupling to neutrons (protons) reaches $2.2\times10^{-43}$ cm$^2$ ($6.0\times10^{-42}$ cm$^2$). △ Less

Submitted 17 November, 2020; v1 submitted 17 July, 2020; originally announced July 2020.

Journal ref: JCAP11(2020)031

Solar Neutrino Detection Sensitivity in DARWIN via Electron Scattering

Authors: J. Aalbers, F. Agostini, S. E. M. Ahmed Maouloud, M. Alfonsi, L. Althueser, F. Amaro, J. Angevaare, V. C. Antochi, B. Antunovic, E. Aprile, L. Arazi, F. Arneodo, M. Balzer, L. Baudis, D. Baur, M. L. Benabderrahmane, Y. Biondi, A. Bismark, C. Bourgeois, A. Breskin, P. A. Breur, A. Brown, E. Brown, S. Brünner, G. Bruno , et al. (141 additional authors not shown)

Abstract: We detail the sensitivity of the liquid xenon (LXe) DARWIN observatory to solar neutrinos via elastic electron scattering. We find that DARWIN will have the potential to measure the fluxes of five solar neutrino components: $pp$, $^7$Be, $^{13}$N, $^{15}$O and $pep$. The precision of the $^{13}$N, $^{15}$O and $pep$ components is hindered by the double-beta decay of $^{136}$Xe and, thus, would ben… ▽ More We detail the sensitivity of the liquid xenon (LXe) DARWIN observatory to solar neutrinos via elastic electron scattering. We find that DARWIN will have the potential to measure the fluxes of five solar neutrino components: $pp$, $^7$Be, $^{13}$N, $^{15}$O and $pep$. The precision of the $^{13}$N, $^{15}$O and $pep$ components is hindered by the double-beta decay of $^{136}$Xe and, thus, would benefit from a depleted target. A high-statistics observation of $pp$ neutrinos would allow us to infer the values of the weak mixing angle, $\sin^2θ_w$, and the electron-type neutrino survival probability, $P_e$, in the electron recoil energy region from a few keV up to 200 keV for the first time, with relative precision of 5% and 4%, respectively, at an exposure of 300 ty. An observation of $pp$ and $^7$Be neutrinos would constrain the neutrino-inferred solar luminosity down to 0.2%. A combination of all flux measurements would distinguish between the high (GS98) and low metallicity (AGS09) solar models with 2.1-2.5$σ$ significance, independent of external measurements from other experiments or a measurement of $^8$B neutrinos through coherent elastic neutrino-nucleus scattering in DARWIN. Finally, we demonstrate that with a depleted target DARWIN may be sensitive to the neutrino capture process of $^{131}$Xe. △ Less

Submitted 20 December, 2020; v1 submitted 4 June, 2020; originally announced June 2020.

Comments: 9 pages, 4 figures; for associated data files, see https://github.com/Physik-Institut-UZH/DARWIN-Sensitivity-Studies/tree/master/solar_neutrinos_electron_scattering

Sensitivity of the DARWIN observatory to the neutrinoless double beta decay of $^{136}$Xe

Authors: F. Agostini, S. E. M. Ahmed Maouloud, L. Althueser, F. Amaro, B. Antunovic, E. Aprile, L. Baudis, D. Baur, Y. Biondi, A. Bismark, P. A. Breur, A. Brown, G. Bruno, R. Budnik, C. Capelli, J. Cardoso, D. Cichon, M. Clark, A. P. Colijn, J. J. Cuenca-García, J. P. Cussonneau, M. P. Decowski, A. Depoian, J. Dierle, P. Di Gangi , et al. (70 additional authors not shown)

Abstract: The DARWIN observatory is a proposed next-generation experiment to search for particle dark matter and for the neutrinoless double beta decay of $^{136}$Xe. Out of its 50$\,$t total natural xenon inventory, 40$\,$t will be the active target of a time projection chamber which thus contains about 3.6 t of $^{136}$Xe. Here, we show that its projected half-life sensitivity is $2.4\times10^{27}\,$yr, u… ▽ More The DARWIN observatory is a proposed next-generation experiment to search for particle dark matter and for the neutrinoless double beta decay of $^{136}$Xe. Out of its 50$\,$t total natural xenon inventory, 40$\,$t will be the active target of a time projection chamber which thus contains about 3.6 t of $^{136}$Xe. Here, we show that its projected half-life sensitivity is $2.4\times10^{27}\,$yr, using a fiducial volume of 5t of natural xenon and 10$\,$yr of operation with a background rate of less than 0.2$~$events/(t$\cdot$yr) in the energy region of interest. This sensitivity is based on a detailed Monte Carlo simulation study of the background and event topologies in the large, homogeneous target. DARWIN will be comparable in its science reach to dedicated double beta decay experiments using xenon enriched in $^{136}$Xe. △ Less

Submitted 7 September, 2020; v1 submitted 25 March, 2020; originally announced March 2020.

Comments: 12 pages, 9 figures

Journal ref: Eur. Phys. J. C 80, 808 (2020)

Energy resolution and linearity of XENON1T in the MeV energy range

Authors: E. Aprile, J. Aalbers, F. Agostini, M. Alfonsi, L. Althueser, F. D. Amaro, V. C. Antochi, E. Angelino, J. Angevaare, F. Arneodo, D. Barge, L. Baudis, B. Bauermeister, L. Bellagamba, M. L. Benabderrahmane, T. Berger, P. A. Breur, A. Brown, E. Brown, S. Bruenner, G. Bruno, R. Budnik, C. Capelli, J. M. R. Cardoso, D. Cichon , et al. (113 additional authors not shown)

Abstract: Xenon dual-phase time projection chambers designed to search for Weakly Interacting Massive Particles have so far shown a relative energy resolution which degrades with energy above $\sim$200 keV due to the saturation effects. This has limited their sensitivity in the search for rare events like the neutrinoless double-beta decay of $^{136}$Xe at its $Q$-value, $Q_{ββ}\simeq$ 2.46 MeV. For the XEN… ▽ More Xenon dual-phase time projection chambers designed to search for Weakly Interacting Massive Particles have so far shown a relative energy resolution which degrades with energy above $\sim$200 keV due to the saturation effects. This has limited their sensitivity in the search for rare events like the neutrinoless double-beta decay of $^{136}$Xe at its $Q$-value, $Q_{ββ}\simeq$ 2.46 MeV. For the XENON1T dual-phase time projection chamber, we demonstrate that the relative energy resolution at 1 $σ/μ$ is as low as (0.80$\pm$0.02) % in its one-ton fiducial mass, and for single-site interactions at $Q_{ββ}$. We also present a new signal correction method to rectify the saturation effects of the signal readout system, resulting in more accurate position reconstruction and indirectly improving the energy resolution. The very good result achieved in XENON1T opens up new windows for the xenon dual-phase dark matter detectors to simultaneously search for other rare events. △ Less

Submitted 9 September, 2020; v1 submitted 8 March, 2020; originally announced March 2020.

Comments: 9 pages, 7 figures

Journal ref: Eur. Phys. J. C 80, 785 (2020)