Richie Diurba, Rob Fine, Mandeep Gill, Harvey Newman, Kevin Pedro, Alexx Perloff, Breese Quinn, Louise Suter, Shawn Westerdale
This document has been prepared as a Snowmass contributed paper by the Public Policy \& Government Engagement topical group (CEF06) within the Community Engagement Frontier. The charge of CEF06 is to review all aspects of how the High Energy Physics (HEP) community engages with government at all levels and how public policy impacts members of the community and the community at large, and to assess and raise awareness within the community of direct community-driven engagement of the US federal government (\textit{i.e.} advocacy). The focus of this paper is the potential for HEP community advocacy on topics other than funding for basic research.
Azam Zabihi, Xinran Li, Alejandro Ramirez, Manuel D. Da Rocha Rolo, Davide Franco, Federico Gabriele, Cristiano Galbiati, Michela Lai, Daniel R. Marlow, Andrew Renshaw, Shawn Westerdale, Masayuki Wada
Objective: This paper introduces a novel PET imaging methodology called 3-dimensional positron imaging (3Dπ), which integrates total-body (TB) coverage, time-of-flight (TOF) technology, ultra-low dose imaging capabilities, and ultra-fast readout electronics inspired by emerging technology from the DarkSide collaboration. Approach: The study evaluates the performance of 3Dπ using Monte Carlo simulations based on NEMA NU 2-2018 protocols. The methodology employs a homogenous, monolithic scintillator composed of liquid argon (LAr) doped with xenon (Xe) with silicon photomultipliers (SiPM) operating at cryogenic temperatures. Main results: Significant enhancements in system performance are observed, with the 3Dπ system achieving a noise equivalent count rate (NECR) of 3.2 Mcps which is approximately two times higher than uEXPLORER's peak NECR (1.5 Mcps) at 17.3 (kBq/mL). Spatial resolution measurements show an average FWHM of 2.7 mm across both axial positions. The system exhibits superior sensitivity, with values reaching 373 kcps/MBq with a line source at the center of the field of view. Additionally, 3Dπ achieves a TOF resolution of 151 ps at 5.3 kBq/mL, highlighting its potential to produce high-quality images with reduced noise levels. Significance: The study underscores the potential of 3Dπ in improving PET imaging performance, offering the potential for shorter scan times and reduced radiation exposure for patients. The Xe-doped LAr offers advantages such as fast scintillation, enhanced light yield, and cost-effectiveness. Future research will focus on optimizing system geometry and further refining reconstruction algorithms to exploit the strengths of 3Dπ for clinical applications.
Jingke Xu, Chris Stanford, Shawn Westerdale, Frank Calaprice, Alexander Wright, Zhiming Shi
One major background in direct searches for weakly interacting massive particles (WIMPs) comes from the deposition of radon progeny on detector surfaces. The most dangerous surface background is the $^{206}$Pb recoils produced by $^{210}$Po decays. In this letter, we report the first characterization of this background in liquid argon. The scintillation signal of low energy Pb recoils is measured to be highly quenched in argon, and we estimate that the 103keV $^{206}$Pb recoil background will produce a signal equal to that of a ~5keV (30keV) electron recoil ($^{40}$Ar recoil). In addition, we demonstrate that this dangerous $^{210}$Po surface background can be suppressed by a factor of ~100 or higher using pulse shape discrimination methods, which can make argon dark matter detectors near background-free and enhance their potential for discovery of medium- and high-mass WIMPs. We also discuss the impact on other low background experiments.
Shawn Westerdale, Emily Shields, Frank Calaprice
Neutrons are a particularly dangerous background for direct WIMP dark matter searches; their nuclear recoils with the target nucleus are often indistinguishable from nuclear recoils produced by WIMP-nuclear collisions. In this study, we explore the concept of a liquid scintillator neutron veto detector that would allow direct dark matter detectors to potentially reject neutrons with greater than 99% efficiency. Here we outline the construction and testing of a small prototype detector and the potential implications of this technology for future dark matter detectors.
Daniel Carney, Nirmal Raj, Yang Bai, Joshua Berger, Carlos Blanco, Joseph Bramante, Christopher Cappiello, Maíra Dutra, Reza Ebadi, Kristi Engel, Edward Kolb, J. Patrick Harding, Jason Kumar, Gordan Krnjaic, Rafael F. Lang, Rebecca K. Leane, Benjamin V. Lehmann, Shengchao Li, Andrew J. Long, Gopolang Mohlabeng, Ibles Olcina, Elisa Pueschel, Nicholas L. Rodd, Carsten Rott, Dipan Sengupta, Bibhushan Shakya, Ronald L. Walsworth, Shawn Westerdale
We outline the unique opportunities and challenges in the search for "ultraheavy" dark matter candidates with masses between roughly $10~{\rm TeV}$ and the Planck scale $m_{\rm pl} \approx 10^{16}~{\rm TeV}$. This mass range presents a wide and relatively unexplored dark matter parameter space, with a rich space of possible models and cosmic histories. We emphasize that both current detectors and new, targeted search techniques, via both direct and indirect detection, are poised to contribute to searches for ultraheavy particle dark matter in the coming decade. We highlight the need for new developments in this space, including new analyses of current and imminent direct and indirect experiments targeting ultraheavy dark matter and development of new, ultra-sensitive detector technologies like next-generation liquid noble detectors, neutrino experiments, and specialized quantum sensing techniques.
Shawn Westerdale
As liquid argon (LAr) detectors are made at progressively larger sizes, accurate models of LAr optical properties become increasingly important for simulating light transport, understanding signals, and developing analyses. The refractive index, group velocity, and Rayleigh scattering length are particularly important for vacuum ultraviolet (VUV) and visible photons in detectors with diameters much greater than one meter. While optical measurements in the VUV are sparse, recent measurements of the group velocity of 128 nm photons in LAr provide valuable constraints on these parameters. These calculations are further complicated by the dependence of optical parameters on thermodynamic properties that might fluctuate or vary throughout the argon volume. This manuscript presents the model used by DEAP-3600, a dark matter direct detection experiment at SNOLAB using a 3.3 tonne LAr scintillation counter. Existing data and thermodynamic models are synthesized to estimate the wavelength-dependent refractive index, group velocity, and Rayleigh scattering length within the detector, and parameters' uncertainties are estimated. This model, along with in situ measurements of LAr scintillation properties, is benchmarked against data collected in DEAP-3600, providing a method for modeling optical properties in large LAr detectors and for propagating their uncertainties through downstream simulations. Updates are also presented of the Noble Element Simulation Technique (NEST) software, widely used to model scintillation and ionization signals in argon- and xenon-based detectors.
Shawn Westerdale, Jingke Xu, Emily Shields, Francis Froborg, Frank Calaprice, Thomas Alexander, Ani Aprahamian, Henning O. Back, Clark Casarella, Xiao Fang, Yogesh K. Gupta, Edward Lamere, Qian Liu, Stephanie Lyons, Mallory Smith, Wanpeng Tan
Organic liquid scintillators are used in a wide variety of applications in experimental nuclear and particle physics. Boron-loaded scintillators are particularly useful for detecting neutron captures, due to the high thermal neutron capture cross section of $^{10}$B. These scintillators are commonly used in neutron detectors, including the DarkSide-50 neutron veto, where the neutron may produce a signal when it scatters off protons in the scintillator or when it captures on $^{10}$B. Reconstructing the energy of these recoils is complicated by scintillation quenching. Understanding how nuclear recoils are quenched in these scintillators is an important and difficult problem. In this article, we present a set of measurements of neutron-induced proton recoils in a boron-loaded organic liquid scintillator at recoil energies ranging from 57--467 keV, and we compare these measurements to predictions from different quenching models. We find that a modified Birks' model whose denominator is quadratic in $dE/dx$ best describes the measurements, with $χ^2$/NDF$=1.6$. This result will help model nuclear recoil scintillation in similar detectors and can be used to improve their neutron tagging efficiency.
Daniel Baxter, Raymond Bunker, Sally Shaw, Shawn Westerdale, Isaac Arnquist, Daniel S. Akerib, Rob Calkins, Susana Cebrián, James B. Dent, Maria Laura di Vacri, Jim Dobson, Daniel Egana-Ugrinovic, Andrew Erlandson, Chamkaur Ghag, Carter Hall, Jeter Hall, Scott Haselschwardt, Eric Hoppe, Chris M. Jackson, Yonatan Kahn, Alvine Kamaha, Mike Kelsey, Alexander Kish, Noah Kurinsky, Matthias Laubenstein, Eric H. Miller, Eric Morrison, Brianna Mount, Jayden L. Newstead, Stefano Nisi, Ibles Olcina, John Orrell, Sergey Pereverzev, Emily Perry, Andreas Piepke, Sagar Sharma Poudel, Karthik Ramanathan, Juergen Reichenbacher, Tarek Saab, Richard Saldanha, Claudio Savarese, Richard Schnee, Silvia Scorza, Rajeev Singh, Kelly Stifter, Burkhant Suerfu, Matthew Szydagis, Dylan J. Temples, Anthony Villano, David Woodward, Jingke Xu
Future dark matter direct detection experiments will reach unprecedented levels of sensitivity. Achieving this sensitivity will require more precise models of signal and background rates in future detectors. Improving the precision of signal and background modeling goes hand-in-hand with novel calibration techniques that can probe rare processes and lower threshold detector response. The goal of this white paper is to outline community needs to meet the background and calibration requirements of next-generation dark matter direct detection experiments.
Mateus Carneiro, Richie Diurba, Rob Fine, Mandeep Gill, Ketino Kaadze, Harvey Newman, Kevin Pedro, Alexx Perloff, Louise Suter, Shawn Westerdale
This document has been prepared as a Snowmass contributed paper by the Public Policy \& Government Engagement topical group (CEF06) within the Community Engagement Frontier. The charge of CEF06 is to review all aspects of how the High Energy Physics (HEP) community engages with government at all levels and how public policy impacts members of the community and the community at large, and to assess and raise awareness within the community of direct community-driven engagement of the U.S. federal government (\textit{i.e.} advocacy). The focus of this paper is the advocacy undertaken by the HEP community that pertains directly to the funding of the field by the U.S. federal government.
Leo Weimer, Emma Ellingwood, Otis Fischer, Michela Lai, Shawn Westerdale
De-excitation $γ$ cascades from neutron captures form a dominant background to MeV-scale signals. The Geant4 Monte Carlo simulation toolkit is widely used to model backgrounds in nuclear and particle physics experiments. While its current modules for simulating (n, $γ$) signals, G4NDL and G4PhotoEvaporation, are excellent for many applications, they do not reproduce known gamma-ray lines and correlations relevant at 2-15 MeV. G4CASCADE is a new data-driven Geant4 module that simulates (n, $γ$) de-excitation pathways, with options for how to handle shortcomings in nuclear data. Benchmark comparisons to measured gamma-ray lines and level structures in the ENSDF database show significant improvements, with decreased residuals and full energy conservation. This manuscript describes the underlying calculations performed by G4CASCADE, its various usage options, and benchmark comparisons. G4CASCADE for Geant4-10 is available on GitHub at https://github.com/UCRDarkMatter/CASCADE
Jodi Cooley, Tongyan Lin, W. Hugh Lippincott, Tracy R. Slatyer, Tien-Tien Yu, Daniel S. Akerib, Tsuguo Aramaki, Daniel Baxter, Torsten Bringmann, Ray Bunker, Daniel Carney, Susana Cebrián, Thomas Y. Chen, Priscilla Cushman, C. E. Dahl, Rouven Essig, Alden Fan, Richard Gaitskell, Cristano Galbiati, Graciela B. Gelmini, Graham K. Giovanetti, Guillaume Giroux, Luca Grandi, J. Patrick Harding, Scott Haselschwardt, Lauren Hsu, Shunsaku Horiuchi, Yonatan Kahn, Doojin Kim, Geon-Bo Kim, Scott Kravitz, V. A. Kudryavtsev, Noah Kurinsky, Rafael F. Lang, Rebecca K. Leane, Benjamin V. Lehmann, Cecilia Levy, Shengchao Li, Ben Loer, Aaron Manalaysay, C. J Martoff, Gopolang Mohlabeng, M. E. Monzani, Alexander St J. Murphy, Russell Neilson, Harry N. Nelson, Ciaran A. J. O'Hare, K. J. Palladino, Aditya Parikh, Jong-Chul Park, Kerstin Perez, Stefano Profumo, Nirmal Raj, Brandon M. Roach, Tarek Saab, Maria Luísa Sarsa, Richard Schnee, Sally Shaw, Seodong Shin, Kuver Sinha, Kelly Stifter, Aritoki Suzuki, M. Szydagis, Tim M. P. Tait, Volodymyr Takhistov, Yu-Dai Tsai, S. E. Vahsen, Edoardo Vitagliano, Philip von Doetinchem, Gensheng Wang, Shawn Westerdale, David A. Williams, Xin Xiang, Liang Yang
This report summarizes the findings of the CF1 Topical Subgroup to Snowmass 2021, which was focused on particle dark matter. One of the most important scientific goals of the next decade is to reveal the nature of dark matter (DM). To accomplish this goal, we must delve deep, to cover high priority targets including weakly-interacting massive particles (WIMPs), and search wide, to explore as much motivated DM parameter space as possible. A diverse, continuous portfolio of experiments at large, medium, and small scales that includes both direct and indirect detection techniques maximizes the probability of discovering particle DM. Detailed calibrations and modeling of signal and background processes are required to make a convincing discovery. In the event that a candidate particle is found through different means, for example at a particle collider, the program described in this report is also essential to show that it is consistent with the actual cosmological DM. The US has a leading role in both direct and indirect detection dark matter experiments -- to maintain this leading role, it is imperative to continue funding major experiments and support a robust R\&D program.
Fabio Acerbi, Pushparaj Adhikari, Paolo Agnes, Iftikhar Ahmad, Sebastiano Albergo, Ivone F. M. Albuquerque, Thomas Olling Alexander, Andrew Knight Alton, Pierre-Andre Amaudruz, Gioacchino Alex Anastasi, Michele Angiolilli, Elena Aprile, David J. Auty, Maximo Ave Pernas, Oscar Azzolini, Henning Olling Back, Zoe Balmforth, Ana Isabel Barrado Olmedo, Pierre Barrillon, Giovanni Batignani, Swadheen Bharat, Pritindra Bhowmick, Sofia Blua, Valerio Bocci, Walter Bonivento, Bianca Bottino, Mark G. Boulay, Titanilla Braun, Andrzej Buchowicz, Severino Bussino, Jose Busto, Matteo Cadeddu, Mariano Cadoni, Roberta Calabrese, Vincenzo Camillo, Alessio Caminata, Nicola Canci, Andrea Capra, Mauro Caravati, Miguel Cardenas-Montes, Nicola Cargioli, Marco Carlini, Paolo Castello, Paolo Cavalcante, Susana Cebrian, Alexander Chepurnov, Sarthak Choudhary, Luisa Cifarelli, Yann Coadou, Ivan Coarasa, Valentina Cocco, Estefania Conde Vilda, Lucia Consiglio, Harrison Coombes, Andre Filipe Ventura Cortez, Barbara S. Costa, Milena Czubak, Saverio D'Auria, Manuel Dionisio Da Rocha Rolo, Alexander Dainty, Giovanni Darbo, Stefano Davini, Riccardo de Asmundis, Sandro De Cecco, Marzio De Napoli, Giulio Dellacasa, Alexander Derbin, Lea Di Noto, Philippe Di Stefano, Daniel Diaz Mairena, Carlo Dionisi, Grigory Dolganov, Francesca Dordei, Aaron Elersich, Emma Ellingwood, Tyler Erjavec, Niamh Fearon, Marta Fernandez Diaz, Luca Ferro, Andrea Ficorella, Giuliana Fiorillo, Dylon Fleming, Paolo Franchini, Davide Franco, Heriques Frandini Gatti, Federico Gabriele, Devidutta Gahan, Cristiano Galbiati, Grzegorz Galinski, Giacomo Gallina, Marco Garbini, Pablo Garcia Abia, Andrzej Gawdzik, Graham Kurt Giovanetti, Alberto Gola, Luca Grandi, Gianfrancesco Grauso, Giovanni Grilli di Cortona, Alexey Grobov, Maxim Gromov, Julian Guerrero Canovas, Marisa Gulino, Samuel Belayneh Habtemariam, Brianne Rae Hackett, Aksel Hallin, Malgorzata Haranczyk, Timothee Hessel, Celin Hidalgo, James Hollingham, Sosuke Horikawa, Jie Hu, Fabrice Hubaut, Daniel Huff, Theo Hugues, Andrea Ianni, Valerio Ippolito, Ako Jamil, Chris Jillings, Rijeesh Keloth, Nikolas Kemmerich, Ashlea Kemp, Kaori Kondo, George Korga, Lucy Kotsiopoulou, Seraphim Koulosousas, Pablo Kunze, Michael Kuss, Marcin Kuzniak, Maciej Kuzwa, Marco La Commara, Michela Lai, Emmanuel Le Guirriec, Elizabeth Leason, Alfiero Leoni, Lance Lidey, John D Lipp, Marcello Lissia, Ludovico Luzzi, Olga Lychagina, Oliver Macfadyen, Janna Machts, Igor Machulin, Szymon Manecki, Ioannis Manthos, Andrea Marasciulli, Stefano Maria Mari, Camillo Mariani, Jelena Maricic, Maria Martinez, Giuseppe Matteucci, Konstantinos Mavrokoridis, Arthur B. McDonald, Luo Meng, Stefano Merzi, Andrea Messina, Radovan Milincic, Graham Miller, Saverio Minutoli, Ankush Mitra, Jocelyn Monroe, Matteo Morrocchi, Abdulrahman Morsy, Valentina Muratova, Michael Murra, Carlo Muscas, Paolo Musico, Rosario Nania, Marzio Nessi, Grzegorz Nieradka, Konstantinos Nikolopoulos, Evangelia Nikoloudaki, Jaroslaw Nowak, Konstantin Olchanski, Andrey Oleinik, Paolo Organtini, Alfonso Ortiz de Solorzano, Anantha Padmanabhan, Marco Pallavicini, Luciano Pandola, Emilija Pantic, Eugenio Paoloni, Danial Papi, Byungju Park, Grzegorz Pastuszak, Giovanni Paternoster, Riccardo Pavarani, Alec Peck, Paolo Attilio Pegoraro, Krzysztof Pelczar, Ramon Perez, Vicente Pesudo, Stefano Piacentini, Noemi Pino, Guillaume Plante, Andrea Pietro Pocar, Stephen Pordes, Pascal Pralavorio, Elettra Preosti, Darren Price, George Prior, Manuel Pronesti, Sebastiana Puglia, Maria Cecilia Queiroga Bazetto, Fabrizio Raffaelli, Francesco Ragusa, Yorck Ramachers, Alejandro Ramirez, Sudikshan Ravinthiran, Marco Razeti, Andrew Lee Renshaw, Aras Repond, Marco Rescigno, Silvia Resconi, Fabrice Retiere, Ash Ritchie-Yates, Angelo Rivetti, Adam Roberts, Conner Roberts, Diego Rodriguez Rodas, Giovanni Rogers, Luciano Romero, Matteo Rossi, Dmitry Rudik, James Runge, Maria Adriana Sabia, Camilla Salerno, Paolo Salomone, Simone Sanfilippo, Daria Santone, Roberto Santorelli, Edivaldo M. Santos, Isobel Sargeant, Maria Luisa Sarsa, Claudio Savarese, Eugenio Scapparone, Fred Schuckman, Dmitriy Semenov, Carmen Seoane, Michela Sestu, Veronika Shalamova, Sanjay Sharma Poudel, Marino Simeone, Peter Skensved, Mikhail Skorokhvatov, Taisiia Smirnova, Ben Smith, Robert Smith, Franco Spadoni, Martin Spangenberg, Arianna Steri, Vincenzo Stornelli, Simone Stracka, Allan Sung, Clea Sunny, Yury Suvorov, Andrzej M Szelc, Oscar Taborda, Benjamin Tam, Roberto Tartaglia, Alan Taylor, Jonathan Taylor, Gemma Testera, Kevin Thieme, Angus Thompson, Sebastian Torres-Lara, Alessia Tricomi, Sara Tullio, Evgeniy Unzhakov, Marie Van Uffelen, Pedro Ventura, Guillermo Vera Diaz, Simon Viel, Alina Vishneva, Bruce Vogelaar, Joost Vossebeld, Bansari Vyas, Masayuki Wada, Marek Bohdan Walczak, Yi Wang, Shawn Westerdale, Laurie Williams, Marcin Marian Wojcik, Mariusz Wojcik, Changgen Yang, Jilong Yin, Azam Zabihi, Paul Zakhary, Andrea Zani, Haoxiang Zhan, Yongpeng Zhang, Antonino Zichichi, Grzegorz Zuzel
R. Ajaj, G. R. Araujo, M. Batygov, B. Beltran, C. E. Bina, M. G. Boulay, B. Broerman, J. F. Bueno, P. M. Burghardt, A. Butcher, M. Cárdenas-Montes, S. Cavuoti, M. Chen, Y. Chen, B. T. Cleveland, K. Dering, F. A. Duncan, M. Dunford, A. Erlandson, N. Fatemighomi, G. Fiorillo, A. Flower, R. J. Ford, D. Gallacher, P. García Abia, S. Garg, P. Giampa, D. Goeldi, V. V. Golovko, P. Gorel, K. Graham, D. R. Grant, A. L. Hallin, M. Hamstra, P. J. Harvey, C. Hearns, A. Joy, C. J. Jillings, O. Kamaev, G. Kaur, A. Kemp, I. Kochanek, M. Kuźniak, S. Langrock, F. La Zia, B. Lehnert, X. Li, O. Litvinov, J. Lock, G. Longo, P. Majewski, A. B. McDonald, T. McElroy, T. McGinn, J. B. McLaughlin, R. Mehdiyev, C. Mielnichuk, J. Monroe, P. Nadeau, C. Nantais, C. Ng, A. J. Noble, C. Ouellet, P. Pasuthip, S. J. M. Peeters, V. Pesudo, M. -C. Piro, T. R. Pollmann, E. T. Rand, C. Rethmeier, F. Retière, E. Sanchez García, R. Santorelli, N. Seeburn, P. Skensved, B. Smith, N. J. T. Smith, T. Sonley, R. Stainforth, C. Stone, V. Strickland, B. Sur, E. Vázquez-Jáuregui, L. Veloce, S. Viel, J. Walding, M. Waqar, M. Ward, S. Westerdale, J. Willis, A. Zuñiga-Reyes
The DEAP-3600 experiment is searching for WIMP dark matter with a 3.3 tonne single phase liquid argon (LAr) target, located 2.1 km underground at SNOLAB. The experimental signature of dark matter interactions is keV-scale $^{40}$Ar nuclear recoils (NR) producing 128 nm LAr scintillation photons observed by PMTs. The largest backgrounds in DEAP-3600 are electronic recoils (ER) induced by $β$ and $γ$-rays originating from internal and external radioactivity in the detector material. A background model of the ER interactions in DEAP-3600 was developed and is described in this work. The model is based on several components which are expected from radioisotopes in the LAr, from ex-situ material assay measurements, and from dedicated independent in-situ analyses. This prior information is used in a Bayesian fit of the ER components to a 247.2 d dataset to model the radioactivity in the surrounding detector materials. While excellent discrimination between ERs and NRs is reached with pulse shape discrimination, utilizing the large difference between fast and slow components of LAr scintillation light, detailed knowledge of the ER background and activity of detector components, sets valuable constraints on other key types of backgrounds in the detector: neutrons and alphas. In addition, the activity of $^{42}$Ar in LAr in DEAP-3600 is determined by measuring the daughter decay of $^{42}$K. This cosmogenically activated trace isotope is a relevant background at higher energies for other rare event searches using atmospheric argon e.g. DarkSide-20k, GERDA or LEGEND. The specific activity of $^{42}$Ar in the atmosphere is found to be $40.4 \pm 5.9$ $μ$Bq/kg of argon.
R. Ajaj, P. -A. Amaudruz, G. R. Araujo, M. Baldwin, M. Batygov, B. Beltran, C. E. Bina, J. Bonatt, M. G. Boulay, B. Broerman, J. F. Bueno, P. M. Burghardt, A. Butcher, B. Cai, S. Cavuoti, M. Chen, Y. Chen, B. T. Cleveland, D. Cranshaw, K. Dering, J. DiGioseffo, L. Doria, F. A. Duncan, M. Dunford, A. Erlandson, N. Fatemighomi, G. Fiorillo, S. Florian, A. Flower, R. J. Ford, R. Gagnon, D. Gallacher, E. A. Garcés, S. Garg, P. Giampa, D. Goeldi, V. V. Golovko, P. Gorel, K. Graham, D. R. Grant, A. L. Hallin, M. Hamstra, P. J. Harvey, C. Hearns, A. Joy, C. J. Jillings, O. Kamaev, G. Kaur, A. Kemp, I. Kochanek, M. Kuźniak, S. Langrock, F. La Zia, B. Lehnert, X. Li, J. Lidgard, T. Lindner, O. Litvinov, J. Lock, G. Longo, P. Majewski, A. B. McDonald, T. McElroy, T. McGinn, J. B. McLaughlin, R. Mehdiyev, C. Mielnichuk, J. Monroe, P. Nadeau, C. Nantais, C. Ng, A. J. Noble, E. O'Dwyer, C. Ouellet, P. Pasuthip, S. J. M. Peeters, M. -C. Piro, T. R. Pollmann, E. T. Rand, C. Rethmeier, F. Retière, N. Seeburn, K. Singhrao, P. Skensved, B. Smith, N. J. T. Smith, T. Sonley, J. Soukup, R. Stainforth, C. Stone, V. Strickland, B. Sur, J. Tang, E. Vázquez-Jáuregui, L. Veloce, S. Viel, J. Walding, M. Waqar, M. Ward, S. Westerdale, J. Willis, A. Zuñiga-Reyes
Feb 11, 2019·astro-ph.CO·PDF DEAP-3600 is a single-phase liquid argon (LAr) direct-detection dark matter experiment, operating 2 km underground at SNOLAB (Sudbury, Canada). The detector consists of 3279 kg of LAr contained in a spherical acrylic vessel. This paper reports on the analysis of a 758 tonne\cdot day exposure taken over a period of 231 live-days during the first year of operation. No candidate signal events are observed in the WIMP-search region of interest, which results in the leading limit on the WIMP-nucleon spin-independent cross section on a LAr target of $3.9\times10^{-45}$ cm$^{2}$ ($1.5\times10^{-44}$ cm$^{2}$) for a 100 GeV/c$^{2}$ (1 TeV/c$^{2}$) WIMP mass at 90\% C. L. In addition to a detailed background model, this analysis demonstrates the best pulse-shape discrimination in LAr at threshold, employs a Bayesian photoelectron-counting technique to improve the energy resolution and discrimination efficiency, and utilizes two position reconstruction algorithms based on PMT charge and photon arrival times.
P. Adhikari, R. Ajaj, M. Alpízar-Venegas, D. J. Auty, H. Benmansour, C. E. Bina, W. Bonivento, M. G. Boulay, M. Cadeddu, B. Cai, M. Cárdenas-Montes, S. Cavuoti, Y. Chen, B. T. Cleveland, J. M. Corning, S. Daugherty, P. DelGobbo, P. Di Stefano, L. Doria, M. Dunford, E. Ellingwood, A. Erlandson, S. S. Farahani, N. Fatemighomi, G. Fiorillo, D. Gallacher, P. García Abia, S. Garg, P. Giampa, D. Goeldi, P. Gorel, K. Graham, A. Grobov, A. L. Hallin, M. Hamstra, T. Hugues, A. Ilyasov, A. Joy, B. Jigmeddorj, C. J. Jillings, O. Kamaev, G. Kaur, A. Kemp, I. Kochanek, M. Ku{ź}niak, M. Lai, S. Langrock, B. Lehnert, A. Leonhardt, N. Levashko, X. Li, M. Lissia, O. Litvinov, J. Lock, G. Longo, I. Machulin, A. B. McDonald, T. McElroy, J. B. McLaughlin, C. Mielnichuk, L. Mirasola, J. Monroe, G. Oliviéro, S. Pal, S. J. M. Peeters, M. Perry, V. Pesudo, E. Picciau, M. -C. Piro, T. R. Pollmann, N. Raj, E. T. Rand, C. Rethmeier, F. Retière, I. Rodríguez-García, L. Roszkowski, J. B. Ruhland, E. Sanchez García, T. Sánchez-Pastor, R. Santorelli, S. Seth, D. Sinclair, P. Skensved, B. Smith, N. J. T. Smith, T. Sonley, R. Stainforth, M. Stringer, B. Sur, E. Vázquez-Jáuregui, S. Viel, J. Walding, M. Waqar, M. Ward, S. Westerdale, J. Willis, A. Zuñiga-Reyes
Aug 21, 2021·astro-ph.CO·PDF Dark matter particles with Planck-scale mass ($\simeq10^{19}\text{GeV}/c^2$) arise in well-motivated theories and could be produced by several cosmological mechanisms. Using a blind analysis of data collected over a 813 d live time with DEAP-3600, a 3.3 t single-phase liquid argon-based dark matter experiment at SNOLAB, a search for supermassive dark matter was performed, looking for multiple-scatter signals. No candidate signal events were observed, leading to the first direct detection constraints on Planck-scale mass dark matter. Leading limits constrain dark matter masses between $8.3\times10^{6}$ and $1.2\times10^{19} \text{GeV}/c^2$, and cross sections for scattering on $^{40}$Ar between $1.0\times10^{-23}$ and $2.4\times10^{-18} \text{cm}^2$. These are used to constrain two composite dark matter models.
L. M. Ramos, A. F. V. Cortez, M. Kuźniak, A. Gnat, M. Kuźwa, G. Nieradka, T. Sworobowicz, S. Westerdale
To enhance the ionization yield of liquid argon time projection chambers (LArTPC) used in dark matter and neutrino experiments it was proposed the use of dopants in LAr, with ionization energies below the scintillation threshold of Ar. While dual-phase LArTPCs have excellent sensitivity to single ionization electrons, their compatibility with photosensitive dopants is hindered by gas-phase electroluminescence photons ionizing the dopants, leading to a positive feedback loop. This can be addressed by optically decoupling the gaseous and liquid phases with a barrier that transmits electrons. A possible solution relies on the use of a pair of structures based on Gaseous Electron Multipliers(GEMs) with misaligned holes. Rather than amplifying electron signals in gas pockets within their holes, their holes will be filled with LAr and a low biasing voltage, so that incident drifting electrons are drawn into the holes but not amplified. Instead, amplification will occur in the gas phase above the structures. Its core element is a GEM-like structure machined from polyethylene naphthalate(PEN). Since PEN scintillates in the visible spectrum, the risk of increased radioactivity due to the larger mass compared to traditional wire grids is negated by the potential to veto its own radioactivity. As such, these structures may also be a useful alternative to wire grids. In this work, we report the newest developments on the production of GEM-like structures using laser-based techniques, namely the manufacture of the first batch PEN and PMMA-based GEM-like structures. This process allows low-cost, reproducible fabrication of a high volume of such structures. In addition to being a low radioactive technique, we expect that it will allow the scaling up of the production of these structures at a reduced cost. First tests indicate good electrical stability, while the performance assessment is still ongoing.
James W. Kingston, Jianyang Qi, Jingke Xu, Ethan P. Bernard, Adam D. Tidball, Alec W. Peck, Nathaniel S. Bowden, Mani Tripathi, Kaixuan Ni, Shawn Westerdale
Noble element detectors using argon or xenon as the detection medium are widely used in the searches for rare neutrino and dark matter interactions. Xenon doping in liquid argon can preserve attractive properties of an argon target while enhancing the detectable signals with properties of xenon. In this work, we deployed a dual-phase liquid argon detector with up to 4% xenon doping in the liquid and studied its gas electroluminescence properties as a function of xenon concentration. At $\sim$2% xenon doping in liquid argon, we measured $\sim$34 ppm of xenon in the gas and observed $\sim$2.5 times larger electroluminescence signals in the detector than those in pure argon. By analyzing signals recorded by photosensors of different wavelength sensitivities, we confirm that the argon gas electroluminescence process is strongly affected by the addition of xenon. We propose an analytical model to describe the underlying energy transfer mechanism in argon-xenon gas mixtures. Lastly, the implications of this measurement for low energy ionization signal detection will be discussed.
The DarkSide-50 Collaboration, :, P. Agnes, I. F. M. Albuquerque, T. Alexander, A. K. Alton, M. Ave, H. O. Back, G. Batignani, K. Biery, V. Bocci, W. M. Bonivento, B. Bottino, S. Bussino, M. Cadeddu, M. Cadoni, F. Calaprice, A. Caminata, N. Canci, M. Caravati, M. Cariello, M. Carlini, M. Carpinelli, S. Catalanotti, V. Cataudella, P. Cavalcante, S. Cavuoti, A. Chepurnov, C. Cicalo, A. G. Cocco, G. Covone, D. D'Angelo, S. Davini, A. De Candia, S. De Cecco, G. De Filippis, G. De Rosa, A. V. Derbin, A. Devoto, M. D'Incecco, C. Dionisi, F. Dordei, M. Downing, D. D'Urso, G. Fiorillo, D. Franco, F. Gabriele, C. Galbiati, C. Ghiano, C. Giganti, G. K. Giovanetti, O. Gorchakov, A. M. Goretti, A. Grobov, M. Gromov, M. Guan, Y. Guardincerri, M. Gulino, B. R. Hackett, K. Herner, B. Hosseini, F. Hubaut, E. V. Hungerford, An. Ianni, V. Ippolito, K. Keeter, C. L. Kendziora, I. Kochanek, D. Korablev, G. Korga, A. Kubankin, M. Kuss, M. La Commara, M. Lai, X. Li, M. Lissia, G. Longo, I. N. Machulin, L. P. Mapelli, S. M. Mari, J. Maricic, C. J. Martoff, A. Messina, P. D. Meyers, R. Milincic, M. Morrocchi, V. N. Muratova, P. Musico, A. Navrer Agasson, A. O. Nozdrina, A. Oleinik, F. Ortica, L. Pagani, M. Pallavicini, L. Pandola, E. Pantic, E. Paoloni, K. Pelczar, N. Pelliccia, E. Picciau, A. Pocar, S. Pordes, S. S. Poudel, P. Pralavorio, F. Ragusa, M. Razeti, A. Razeto, A. L. Renshaw, M. Rescigno, J. Rode, A. Romani, D. Sablone, O. Samoylov, W. Sands, S. Sanfilippo, C. Savarese, B. Schlitzer, D. A. Semenov, A. Shchagin, A. Sheshukov, M. D. Skorokhvatov, O. Smirnov, A. Sotnikov, S. Stracka, Y. Suvorov, R. Tartaglia, G. Testera, A. Tonazzo, E. V. Unzhakov, A. Vishneva, R. B. Vogelaar, M. Wada, H. Wang, Y. Wang, S. Westerdale, Ma. M. Wojcik, X. Xiao, C. Yang, G. Zuzel
Finding unequivocal evidence of dark matter interactions in a particle detector is a major objective of physics research. Liquid argon time projection chambers offer a path to probe Weakly Interacting Massive Particles scattering cross sections on nucleus down to the so-called neutrino floor, in a mass range from few GeV's to hundredths of TeV's. Based on the successful operation of the DarkSide-50 detector at LNGS, a new and more sensitive experiment, DarkSide-20k, has been designed and is now under construction. A thorough understanding of the DarkSide-50 detector response and, therefore, of all kind of observed events, is essential for an optimal design of the new experiment. In this paper, we report on a particular set of events, which were not used for dark matter searches. Namely, standard two-pulse scintillation-ionization signals accompanied by a small amplitude third pulse, originating from single or few electrons, in a time window of less than a maximum drift time. We compare our findings to those of a recent paper of the LUX Collaboration (D.S.Akerib et al. Phys.Rev.D 102, 092004). Indeed, both experiments observe events related to photoionization of the cathode. From the measured rate of these events, we estimate for the first time the quantum efficiency of the tetraphenyl butadiene deposited on the DarkSide-50 cathode at wavelengths around 128 nm, in liquid argon. Also, both experiments observe events likely related to photoionization of impurities in the liquid. The probability of photoelectron emission per unit length turns out to be one order of magnitude smaller in DarkSide-50 than in LUX. This result, together with the much larger measured electron lifetime, coherently hints toward a lower concentration of contaminants in DarkSide-50 than in LUX.
DEAP Collaboration, P. Adhikari, R. Ajaj, M. Alpízar-Venegas, P. -A. Amaudruz, J. Anstey, D. J. Auty, M. Batygov, B. Beltran, M. A. Bigentini, C. E. Bina, W. M. Bonivento, M. G. Boulay, J. F. Bueno, M. Cadeddu, B. Cai, M. Cárdenas-Montes, S. Cavuoti, Y. Chen, S. Choudhary, B. T. Cleveland, R. Crampton, S. Daugherty, P. DelGobbo, P. Di Stefano, G. Dolganov, L. Doria, F. A. Duncan, M. Dunford, E. Ellingwood, A. Erlandson, S. S. Farahani, N. Fatemighomi, G. Fiorillo, R. J. Ford, D. Gahan, D. Gallacher, A. Garai, P. García Abia, S. Garg, P. Giampa, A. Giménez-Alcázar, D. Goeldi, V. V. Golovko, P. Gorel, K. Graham, A. Grobov, A. L. Hallin, M. Hamstra, S. Haskins, J. Hu, J. Hucker, T. Hugues, A. Ilyasov, B. Jigmeddorj, C. J. Jillings, A. Joy, G. Kaur, A. Kemp, M. Khoshraftar Yazdi, M. Kuźniak, F. La Zia, M. Lai, S. Langrock, B. Lehnert, J. LePage-Bourbonnais, N. Levashko, M. Lissia, L. Luzzi, I. Machulin, A. Maru, J. Mason, A. B. McDonald, T. McElroy, J. B. McLaughlin, C. Mielnichuk, L. Mirasola, A. Moharana, J. Monroe, A. Murray, C. Ng, G. Oliviéro, M. Olszewski, S. Pal, D. Papi, B. Park, M. Perry, V. Pesudo, T. R. Pollmann, F. Rad, C. Rethmeier, F. Retière, I. Rodríguez García, L. Roszkowski, R. Santorelli, F. G. Schuckman, S. Seth, V. Shalamova, P. Skensved, T. Smirnova, K. Sobotkiewich, T. Sonley, J. Sosiak, J. Soukup, R. Stainforth, M. Stringer, J. Tang, R. Turcotte-Tardif, E. Vázquez-Jáuregui, S. Viel, B. Vyas, M. Walczak, J. Walding, M. Ward, S. Westerdale, R. Wormington, A. Zuñiga-Reyes
The half-life of $^{39}$Ar is measured using the DEAP-3600 detector located 2 km underground at SNOLAB. Between 2016 and 2020, DEAP-3600 used a target mass of (3269 $\pm$ 24) kg of liquid argon distilled from the atmosphere in a direct-detection dark matter search. Such an argon mass also enables direct measurements of argon isotope properties. The decay of $^{39}$Ar in DEAP-3600 is the dominant source of triggers by two orders of magnitude, ensuring high statistics and making DEAP-3600 well-suited for measuring this isotope's half-life. Use of the pulse-shape discrimination technique in DEAP-3600 allows powerful discrimination between nuclear recoils and electron recoils, resulting in the selection of a clean sample of $^{39}$Ar decays. Observing over a period of 3.4 years, the $^{39}$Ar half-life is measured to be $(302 \pm 8_{\rm stat} \pm 6_{\rm sys})$ years. This new direct measurement suggests that the half-life of $^{39}$Ar is significantly longer than the accepted value, with potential implications for measurements using this isotope's half-life as input.
P. Agnes, I. F. Albuquerque, T. Alexander, A. K. Alton, M. Ave, H. O. Back, G. Batignani, K. Biery, V. Bocci, W. M. Bonivento, B. Bottino, S. Bussino, M. Cadeddu, M. Cadoni, F. Calaprice, A. Caminata, M. D. Campos, N. Canci, M. Caravati, N. Cargioli, M. Cariello, M. Carlini, P. Cavalcante, S. Chashin, A. Chepurnov, D. D'Angelo, S. Davini, S. De Cecco, A. V. Derbin, M. D'Incecco, C. Dionisi, F. Dordei, M. Downing, M. Fairbairn, G. Fiorillo, D. Franco, F. Gabriele, C. Galbiati, C. Ghiano, C. Giganti, G. K. Giovanetti, V. Goicoechea Casanueva, A. M. Goretti, G. Grilli di Cortona, A. Grobov, M. Gromov, M. Guam, M. Gulino, B. R. Hackett, K. Herner, T. Hessel, F. Hubaut, E. V. Hungerford, A. Ianni, V. Ippolito, K. Keeter, C. L. Kendziora, M. Kimura, I. Kochanek, D. Korablev, G. Korga, A. Kubankin, J. Kumar, M. Kuss, M. La Commara, M. Lai, X. Li, M. Lissia, O. Lychagina, I. N. Machulin, L. P. Mapelli, S. M. Mari, J. Maricic, A. Messina, R. Milincic, J. Monroe, M. Morrocchi, V. N. Muratova, P. Musico, A. O. Nozdrina, A. Oleinik, F. Ortica, L. Pagani, M. Pallavicini, L. Pandola, E. Pantic, E. Paoloni, K. Pelczar, N. Pelliccia, S. Piacentini, A. Pocar, M. Poehlmann, S. Pordes, S. S. Poudel, P. Pralavorio, D. Price, F. Ragusa, M. Razeti, A. L. Renshaw, M. Rescigno, A. Romani, D. Sablone, O. Samoylov, S. Sanfilippo, C. Savarese, B. Schlitzer, D. A. Semenov, A. Shchagin, A. Sheshukov, M. D. Skorokhvatov, O. Smirnov, A. Sotnikov, S. Stracka, Y. Suvorov, R. Tartaglia, G. Testera, A. Tonazzo, E. V. Unzhakov, A. Vishneva, R. B. Vogelaar, M. Wada, H. Wang, Y. Wang, S. Westerdale, M. M. Wojcik, X. Xiao, C. Yang, G. Zuzel
We report the first search for nuclear ultra-heavy dark matter (UHDM) in a dual-phase liquid argon time projection chamber using the DarkSide-50 experiment. Unlike conventional weakly interacting massive particles (WIMPs), nuclear UHDM candidates may be composed of many dark nucleons and scatter numerous times while passing through the detector. Accounting for energy loss through the Earth's overburden, we apply selection criteria optimized for multi-scatter event topologies using the 532-day low-radiation campaign of the DarkSide-50 detector. Excluded limits on the UHDM-nucleon scattering cross section for dark nucleon masses of $m_χ= 10, 50, 100, 500 \, \mathrm{GeV/c^2}$ are presented.