DOCSLIB.ORG

An Investigation of Backgrounds in the DEAP-3600 Dark Matter Direct Detection Experiment

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
An Investigation of Backgrounds in the DEAP-3600 Dark Matter Direct Detection Experiment An Investigation of Backgrounds in the DEAP-3600 Dark Matter Direct Detection Experiment by Laurelle Maria Veloce A thesis submitted to the Department of Physics, Engineering Physics & Astronomy in conformity with the requirements for the degree of Master of Science Queen's University Kingston, Ontario, Canada October 2013 Copyright c Laurelle Maria Veloce, 2013 Abstract Astronomical and cosmological observations reveal that the majority of the matter in our universe is made of an unknown, non-luminous substance called dark matter. Many experimental attempts are underway to directly detect particle dark matter, which is very difficult to measure due to the expected low interaction rate with normal matter. DEAP-3600 is a direct dark matter search experiment located two kilometres underground at SNOLAB, in Sudbury, Ontario. DEAP-3600 will make use of liquid argon as the detector material, which scintillates as charged particles pass through. The work presented here is an investigation of expected background sources in the DEAP detector. Because DEAP-3600 is a noble liquid-based experiment, a thin film of [1,1,4,4]- tetraphenyl-[1,3]-butadiene (TPB) is coated on the detector walls to shift the scin- tillation peak from the UV to visible regime for detection. However, alphas passing through TPB produce scintillation signals which can mimic recoil events. Because scintillation properties can change with temperature, we have conducted an investiga- tion of alpha-induced TPB scintillation at temperatures ranging from 300 K to 3.4 K. We were able to characterize the light yield and decay times, and demonstrated that these background events should be distinguishable from true recoil events in liquid argon, thus enabling DEAP-3600 to achieve higher dark matter sensitivity. i Additionally, we investigate the performance of the liquid argon purification sys- tems, specifically the activated charcoal used for radon filtration. Previous mea- surements with the DEAP prototype experiment have demonstrated the necessity of removing radon from the argon prior to filling the detector, due to the release of contaminates from the argon storage systems. Charcoal radon filters are extremely efficient, however, if the emanation rate of the charcoal is too high, there is the pos- sibility of re-contamination. We performed a measurement of the radon emanation rate of a charcoal sample using a radon emanation and extraction system at Queens University. We demonstrated that the emanation rate of the charcoal was consistent with zero. We also show that the number of residual radon atoms which reach the detector would not be an issue for DEAP-3600. ii Acknowledgments First and foremost, I must thank Dr. Tony Noble. It is no exaggeration to say that without his expertise, guidance, and support, this thesis would not have been possible. Thanks also to the DEAP collaboration for their help and advice, and of course for the opportunity to work on such an exciting project. Thank you especially to Marcin Kuzniak for his invaluable help with the TPB scintillation analysis (and with the painful process of debugging my Root macros), and also to Wolfgang Rau for his advice and guidance with the radon emanation process. Special thanks also to Tina Pollmann, Mark Ward, Mark Boulay, David Bearse, Rob Gagnon, and Bei Cai. My time at Queen's University was much more enjoyable thanks to the antics of my officemates: Kedar Page, Matt Walker, and Alvine Kamaha; and my fellow DEAP graduate students Corina Natais, Paradorn Pasuthip, and Ben Broerman. Finally, my sincerest thanks to my parents, grandparents, and family for always believing in me. And, of course, thank you to Alex for always being there! iii Contents Abstract i Acknowledgments iii Contents iv List of Tables vii List of Figures viii Glossary of Terms xi Chapter 1: Introduction 1 Chapter 2: Dark Matter: A Review 3 2.1 Evidence . 4 2.1.1 Galaxy Clusters . 4 2.1.2 Galactic Rotation Curves . 5 2.1.3 The Cosmic Microwave Background . 8 2.2 Dark Matter Candidates . 9 2.2.1 Dark Matter Detection . 13 2.3 Direct Detection . 15 2.3.1 Dark Matter Recoil Signal . 16 2.3.2 Velocity Distribution and Local Density . 19 2.3.3 Kinematics . 20 2.3.4 Cross Section and Nuclear Form Factors . 22 2.3.5 Detector Response . 24 2.4 Expected Dark Matter Signatures . 25 2.5 Experimental Considerations . 27 Chapter 3: Dark Matter Detection with DEAP-3600 33 3.1 Liquid Argon as a Target Material in Dark Matter Detectors . 34 iv 3.1.1 Pulse Shape Discrimination . 37 3.1.2 Photon Yield . 38 3.2 DEAP-1 . 41 3.3 DEAP-3600 . 44 3.3.1 Backgrounds in DEAP-3600 . 46 Chapter 4: Apha-Induced Scintillation Properties of Tetraphenyl Butadiene 51 4.1 Overview of Organic Scintillation Theory . 52 4.1.1 Radiative Excitation . 55 4.1.2 Radiative Relaxation . 55 4.1.3 Non-Radiative Relaxation . 55 4.2 The Tetraphenyl Butadiene Wavelength Shifter . 58 4.3 The TPB Sample . 60 4.4 Experimental Method . 63 4.5 Analysis and Results . 65 4.5.1 Data Reduction . 65 4.5.2 Single Photoelectron Charge . 72 4.5.3 Detected Light and Light Yield . 80 4.5.4 Pulse Shapes . 83 4.5.5 Prompt Fraction . 89 4.6 Consequences and Impact on DEAP-3600 . 91 4.6.1 Consequences of Light Yield Temperature Dependence . 91 4.6.2 Consequences of Time Constant and Fprompt Temperature De- pendence . 92 Chapter 5: Construction and Testing of the DEAP-3600 Radon Trap 95 5.1 Radon as a background in DEAP 1 . 96 5.2 Radon Filtration . 98 5.3 The DEAP-3600 Carbon Trap Radon Filter . 99 5.4 Emanation of Saratech R Charcoal at Queen's University . 104 5.4.1 The Emanation Apparatus . 104 5.4.2 Emanation and Extraction Procedures . 107 5.5 Emanation Results . 110 5.6 Expected 222Rn Contamination . 113 Chapter 6: Summary and Conclusions 115 Bibliography 119 Appendix A: Additional Cryostat Runs and Data Analysis 132 v A.1 Verification of TPB Sample Stability . 132 A.2 Blank Quartz Sample . 132 A.3 Baseline Effects . 133 A.4 Ringing . 135 A.5 A Deeper Look into Pulse Width . 138 A.5.1 Temperature . 138 A.5.2 Timing . 139 A.6 Systematic Uncertainties . 139 A.7 Correlations in the Pulse Shape Fits . 142 A.8 Additional Light Yield and Pulse Shape Plots . 143 vi List of Tables 2.1 Canonical values for galactic halo and velocity parameters . 20 3.1 Relevant parameters for liquid noble WIMP detection experiments . 36 3.2 Background budget for a DEAP-3600 three year run . 46 3.3 Summary of background leakage for DEAP-3600 . 48 4.1 Summary of organic scintillation processes and timescales . 58 4.2 Most probable values of light distributions at different temperatures . 82 4.3 Time constants at different temperatures . 86 5.1 DEAP-3600 radon trap specifications . 100 5.2 Emanation results of radon emanation for Saratech R activated charcoal111 A.1 Systematic errors for pulse shape fit parameters . 142 vii List of Figures 2.1.1 The Bullet Cluster . 5 2.1.2 Rotation curve of NGC 6503 . 6 2.1.3 Sky Map of the Planck satellite . 8 2.1.4 Power spectrum of the Planck satellite . 9 2.2.1 Dark matter detection pathways . 15 2.3.1 WIMP rate and energy threshold . 17 2.4.1 Annual modulation . 26 2.4.2 Diurnal modulation . 27 2.5.1 Dark matter detection experimental signals . 28 2.5.2 Nuclear vs. electronic recoil events . 30 2.5.3 Muon flux according to underground laboratory . 31 2.5.4 Sensitivities and Projected Sensitivities of key experiments . 32 3.1.1 Elastic scattering between DM particle and LAr nuclei . 35 3.1.2 Demonstration of pulse shape discrimination using Fprompt . 39 3.2.1 Schematic of the DEAP-1 detector . 42 3.3.1 Schematic of the DEAP-3600 detector . 45 3.3.2 Relevant decay chains . 47 3.3.3 Schematic of surface background events . 49 viii 4.1.1 Molecular structure of TPB . 53 4.1.2 Aromatic molecular energy levels and transitions . 54 4.2.1 Neutron recoil pulse shape from DEAP-1 vs. TPB alpha scintillation pulse shapes . 60 4.3.1 TPB evaporation system . 61 4.3.2 Depth of TPB sample . 62 4.4.1 Photograph of TPB sample . 64 4.4.2 Experimental set up schematic . 65 4.5.1 Detected light distribution at 87 K (for one PMT) prior to the imple- mentation of data-cleaning cuts. 66 4.5.2 Pulse Shape at 87 K prior to the implementation of data-cleaning cuts. 67 4.5.3 The first photon arrival time distributions at 87 K. 68 4.5.4 Difference in first photon arrival times between the two PMTs at 87 K. 69 4.5.5 The charged weighted mean event arrival time for channel 0, averaged over all photons at 87 K. ............................ 70 4.5.6 Detected light distribution for 87 K, after pile-up events were removed. 71 4.5.7 Pulse shape at 87 K, after pile-up events were removed. 71 4.5.8 Histogram of late integral charge . 74 4.5.9 Scatter plot of integral charge vs. arrival time . 75 4.5.10Late charge according to pulse width . 76 4.5.11Single photon distribution with different online thresholds . 77 4.5.12Pulse shapes according to threshold . 78 4.5.13Correct Single Photoelectron . 79 4.5.14Pulse Shape at 87 K divided by the singlePE . 80 ix 4.5.15Detected light distribution at 87 K . 81 4.5.16Detected light vs.
Load more

Recommended publications
  • SNOLAB Construction Status and Experimental Program
    M. Chen Queen’s University SNOLAB Construction Status and Experimental Program SNOLAB located 2 km underground in an active nickel mine near Sudbury, Canada it’s an expansion of the underground facility on the same level as the SNO experiment Surface Facility Excavation Status (Today) -Blasting for Phase I Excavation complete. - Shotcrete walls complete - Concrete floors almost finished. BLADDER ROOM BLADDER ROOM SHOWER ROOM SHOWER ROOM DOUBLE TRACKS DOUBLE TRACKS LADDER LABS LADDER LABS CUBE HALL CUBE HALL Phase I - Cube Hall (18x15x15 m) - Ladder Labs (~7mx~7mx60m) Utility Area - Chiller, generator, Lab Entrance water systems Existing SNO - Personnel Areas Facilities -Material Handling -SNO Cavern (30m x 22m dia) - Utility & Control Rms SNOLAB Workshop V, 21 August 2006 Phase II -Cryopit Phase I (15m x15m dia) - Cube Hall (18x15x15 m) - Ladder Labs (~7mx~7mx60m) Utility Area - Chiller, generator, Lab Entrance water systems Existing SNO - Personnel Areas Facilities -Material Handling -SNO Cavern (30m x 22m dia) - Utility & Control Rms Rectangular Hall Control Rm Utility Drift Staging Area Rectangular Hall 60’L x 50’W 50’ (shoulder) 65’ (back) SNOLAB Workshop IV, 15 Aug 2005 Ladder Labs Wide Drift Electrical, 20’x12’ AHUs (19’ to back) Wide Drift 25’x17’ (25’ to back) Access Drift 15’x10’ (15’ to back) Chemistry Lab SNOLAB Workshop IV, 15 Aug 2005 SNOLAB Experiments z Some 20 projects submitted Letters of Interest in locating at SNOLAB. Of these, 10 have been encouraged by the Experiment Advisory Committee as being both scientifically important and particularly suited to the SNOLAB location. z The experimental physics program includes − Neutrinos: Low energy solar neutrinos, geo-neutrinos, reactor neutrinos, supernova neutrino detection z Tests of neutrino properties, precision measurements of solar neutrinos, radiogenic heat generation in the earth, stellar evolution.
    [Show full text]
  • Recommended Conventions for Reporting Results from Direct Dark Matter Searches
    Recommended conventions for reporting results from direct dark matter searches D. Baxter1, I. M. Bloch2, E. Bodnia3, X. Chen4,5, J. Conrad6, P. Di Gangi7, J.E.Y. Dobson8, D. Durnford9, S. J. Haselschwardt10, A. Kaboth11,12, R. F. Lang13, Q. Lin14, W. H. Lippincott3, J. Liu4,5,15, A. Manalaysay10, C. McCabe16, K. D. Mor˚a17, D. Naim18, R. Neilson19, I. Olcina10,20, M.-C. Piro9, M. Selvi7, B. von Krosigk21, S. Westerdale22, Y. Yang4, and N. Zhou4 1Kavli Institute for Cosmological Physics and Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 USA 2School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel 3University of California, Santa Barbara, Department of Physics, Santa Barbara, CA 93106, USA 4INPAC and School of Physics and Astronomy, Shanghai Jiao Tong University, MOE Key Lab for Particle Physics, Astrophysics and Cosmology, Shanghai Key Laboratory for Particle Physics and Cosmology, Shanghai 200240, China 5Shanghai Jiao Tong University Sichuan Research Institute, Chengdu 610213, China 6Oskar Klein Centre, Department of Physics, Stockholm University, AlbaNova, Stockholm SE-10691, Sweden 7Department of Physics and Astronomy, University of Bologna and INFN-Bologna, 40126 Bologna, Italy 8University College London, Department of Physics and Astronomy, London WC1E 6BT, UK 9Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2R3, Canada 10Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA 94720, USA 11STFC Rutherford Appleton Laboratory (RAL), Didcot, OX11 0QX, UK 12Royal Holloway,
    [Show full text]
  • Ultra-Weak Gravitational Field Theory Daniel Korenblum
    Ultra-weak gravitational field theory Daniel Korenblum To cite this version: Daniel Korenblum. Ultra-weak gravitational field theory. 2018. hal-01888978 HAL Id: hal-01888978 https://hal.archives-ouvertes.fr/hal-01888978 Preprint submitted on 5 Oct 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Ultra-weak gravitational field theory Daniel KORENBLUM [email protected] April 2018 Abstract The standard model of the Big Bang cosmology model ΛCDM 1 considers that more than 95 % of the matter of the Universe consists of particles and energy of unknown forms. It is likely that General Relativity (GR)2, which is not a quantum theory of gravitation, needs to be revised in order to free the cosmological model of dark matter and dark energy. The purpose of this document, whose approach is to hypothesize the existence of the graviton, is to enrich the GR to make it consistent with astronomical observations and the hypothesis of a fully baryonic Universe while maintaining the formalism at the origin of its success. The proposed new model is based on the quantum character of the gravitational field. This non-intrusive approach offers a privileged theoretical framework for probing the properties of the regime of ultra-weak gravitational fields in which the large structures of the Universe are im- mersed.
    [Show full text]
  • Search for Dark Matter with Liquid Argon and Pulse Shape Discrimination: Results from DEAP-1 and Status of DEAP-3600
    Search for Dark Matter with Liquid Argon and Pulse Shape Discrimination: Results from DEAP-1 and Status of DEAP-3600 P. Gorel, for the DEAP Collaboration Centre for Particle Physics, University of Alberta, Edmonton, T6G2E1, CANADA In the last decade, Direct Dark Matter searches has become a very active research program, spawning dozens of projects world wide and leading to contradictory results. It is on this stage that the Dark matter Experiment with liquid Argon and Pulse shape discrimination (DEAP) is about to enter. With a 3600 kg liquid argon target and a 1000 kg fiducial mass, it is designed to run background free during 3 years, reaching an unprecedented sensitivity of 10−46 cm2 for a WIMP mass of 100 GeV. In order to achieve this impressive feat, the collaboration followed a two-pronged approach: a careful selection of every material entering the construction of the detector in order to suppress the backgrounds, and optimum use of the pulse shape discrimination (PSD) technique to separate the nuclear recoils from the electronic recoils. Using the experience acquired ffrom the 7 kg-prototype DEAP-1, a 3600 kg detector is being completed at SNOLAB (Sudbury, CANADA) and is expected to start taking data in mid-2014. 1 Dark matter detection using liquid argon For decades, liquid argon (LAr) has been a candidate of choice for large scintillating detectors. It is easy to purify and boasts a high light yield, which makes it ideal for low background, low threshold experiments. The scintillating process involves the creation of excimer, either directly or through ionization/recombination.
    [Show full text]
  • PASAG Report
    Report of the HEPAP Particle Astrophysics Scientific Assessment Group (PASAG) 23 October 2009 Introduction and Executive Summary 1.1 Introduction The US is presently a leader in the exploration of the Cosmic Frontier. Compelling opportunities exist for dark matter search experiments, and for both ground-based and space-based dark energy investigations. In addition, two other cosmic frontier areas offer important scientific opportunities: the study of high- energy particles from space and the cosmic microwave background.” - P5 Report, 2008 May, page 4 Together with the Energy Frontier and the Intensity Frontier, the Cosmic Frontier is an essential element of the U.S. High Energy Physics (HEP) program. Scientific efforts at the Cosmic Frontier provide unique opportunities to discover physics beyond the Standard Model and directly address fundamental physics: the study of energy, matter, space, and time. Astrophysical observations strongly imply that most of the matter in the Universe is of a type that is very different from what composes us and everything we see in daily life. At the same time, well-motivated extensions to the Standard Model of particle physics, invented to solve very different sets of problems, also tend to predict the existence of relic particles from the early Universe that are excellent candidates for the mysterious dark matter. If true, the dark matter isn’t just “out there” but is also passing through us. The opportunity to detect dark matter interactions is both compelling and challenging. Investments from the previous decades have paid off: the capability is now within reach to detect directly the feeble signals of the passage of cosmic dark matter particles in ultra-low-noise underground laboratories, as well as the possibility to isolate for the first time the high-energy particle signals in the cosmos, particularly in gamma rays, that should occur when dark matter particles collide with each other in astronomical systems.
    [Show full text]
  • «Nucleus-2020»
    NRC «Kurchatov Institute» Saint Petersburg State University Joint Institute for Nuclear Research LXX INTERNATIONAL CONFERENCE «NUCLEUS-2020» NUCLEAR PHYSICS AND ELEMENTARY PARTICLE PHYSICS. NUCLEAR PHYSICS TECHNOLOGIES. BOOK OF ABSTRACTS Online part. 12 – 17 October 2020 Saint Petersburg НИЦ «Курчатовский институт» Санкт-Петербургский государственный университет Объединенный институт ядерных исследований LXX МЕЖДУНАРОДНАЯ КОНФЕРЕНЦИЯ «ЯДРО-2020» ЯДЕРНАЯ ФИЗИКА И ФИЗИКА ЭЛЕМЕНТАРНЫХ ЧАСТИЦ. ЯДЕРНО-ФИЗИЧЕСКИЕ ТЕХНОЛОГИИ. СБОРНИК ТЕЗИСОВ Онлайн часть. 12 – 17 октября 2020 Санкт-Петербург Organisers NRC «Kurchatov Institute» Saint Petersburg State University Joint Institute for Nuclear Research Chairs M. Kovalchuk (Chairman, NRC “Kurchatov Institute”) V. Zherebchevsky (Co-Chairman, SPbU) P. Forsh (Vice-Chairman, NRC “Kurchatov Institute”) Yu. Dyakova (Vice-Chairman, NRC “Kurchatov Institute”) A. Vlasnikov (Vice-Chairman, SPbU) S. Torilov (Scientific Secretary, SPbU) The contributions are reproduced directly from the originals. The responsibility for misprints in the report and paper texts is held by the authors of the reports. International Conference “NUCLEUS – 2020. Nuclear physics and elementary particle physics. Nuclear physics technologies” (LXX; 2020; Online part). LXX International conference “NUCLEUS – 2020. Nuclear physics and elementary particle physics. Nuclear physics technologies” (Saint Petersburg, Russia, 12–17 October 2020): Book of Abstracts /Ed. by V. N. Kovalenko and E. V. Andronov. – Saint Petersburg: VVM, 2020. – 324p. ISBN Международная Конференция «ЯДРО – 2020. Ядерная физика и физика элементарных частиц. Ядерно-физические технологии» (LXX; 2020; Онлайн часть). LXX Международная Конференция «ЯДРО – 2020. Ядерная физика и физика элементарных частиц. Ядерно-физические технологии» (Санкт-Петербург, Россия, 12–17 Октября 2020): Аннот. докл./под ред. В.Н. Коваленко, Е.В. Андронова. – Санкт-Петербург: ВВМ , 2020. – 324 c. ISBN 978-5-9651-0587-8 ISBN 978-5-9651-0587-8 ii Program Committee V.
    [Show full text]
  • Postdoctoral Position in the DEAP and Darkside-20K Experiments
    Postdoctoral position in the DEPARTMENT OF PHYSICS Physics, Engineering Physics, DEAP and DarkSide-20k experiments Astronomy Stirling Hall Queen’s University Kingston, Ontario, Canada K7L 3N6 Tel 613 533-2707 Job Summary Fax 613 533-6463 The experimental particle astrophysics group at Queen's University in Kingston, Canada, which is part of the McDonald Institute (https://mcdonaldinstitute.ca/), expects to hire a postdoc to work on the argon dark matter searches DEAP-3600 and DarkSide-20k with Professors Philippe Di Stefano, Art McDonald and Peter Skensved, and with scientists at the TRIUMF laboratory. The postdoc will be actively involved in the analysis of data from the upgraded DEAP-3600 experiment, and in the development of digital electronics and DAQ for the DarkSide-20k experiment at Gran Sasso with 20 tonnes fiducial of liquid argon extracted from an underground source. Construction of a 1-ton prototype detector will start in 2021. These experiments are a stepping-stone towards a 300-tonne fiducial detector, Argo, for which the preferential location is SNOLAB. Work will be carried out in conjunction with the TRIUMF laboratory in Vancouver, with CERN, and with Gran Sasso. Required Qualifications - Candidates must have obtained a PhD in physics or applied physics, with a specialization in particle physics, nuclear physics, or instrumentation. In exceptional circumstances, PhD candidates with a firm date of defense will be considered. - The ability to perform independent research and to communicate results verbally and in writing. - The ability to work in a team including both graduate and undergraduate students. Preferred Qualifications - Experience with particle detectors, including readout, and scintillators.
    [Show full text]
  • Prediction for the Neutrino Mass in the KATRIN Experiment from Lensing by the Galaxy Cluster A1689
    Prediction for the neutrino mass in the KATRIN experiment from lensing by the galaxy cluster A1689 Theo M. Nieuwenhuizen Center for Cosmology and Particle Physics, New York University, New York, NY 10003 On leave of: Institute for Theoretical Physics, University of Amsterdam, Science Park 904, P.O. Box 94485, 1090 GL Amsterdam, The Netherlands Andrea Morandi Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel [email protected]; [email protected] ABSTRACT The KATRIN experiment in Karlsruhe Germany will monitor the decay of tritium, which produces an electron-antineutrino. While the present upper bound for its mass is 2 eV/c2, KATRIN will search down to 0.2 eV=c2. If the dark matter of the galaxy cluster Abell 1689 is modeled as degenerate isothermal fermions, the strong and weak lensing data may be explained by degenerate neutrinos with mass of 1.5 eV=c2. Strong lensing data beyond 275 kpc put tension on the standard cold dark matter interpretation. In the most natural scenario, the electron antineutrino will have a mass of 1.5 eV/c2, a value that will be tested in KATRIN. Subject headings: Introduction, NFW profile for cold dark matter, Isothermal neutrino mass models, Applications of the NFW and isothermal neutrino models, Fit to the most recent data sets, Conclusion 1. Introduction arXiv:1103.6270v1 [astro-ph.CO] 31 Mar 2011 The neutrino sector of the Standard Model of elementary particles is one of today's most intense research fields (Kusenko, 2010; Altarelli and Feruglio 2010; Avignone et al.
    [Show full text]
  • 180312 DOE NSAC Njtsmith
    Community Report on 0!ββ-decay Nigel Smith, SNOLAB Thanks to community for (substantial) input and TAUP presenters, especially Stefan Schönert for contributions Overview of talk - Double Beta Decay - The physics payload - Characteristics of experimental challenges - Experimental techniques - Current/future experiment updates - Central messages: - Physics payload from 0!ββ is highly compelling - Much progress over last couple of years addressing challenge of scale- up to tonne-scale detectors; next step ready to go - Support infrastructure exists within underground labs US DOE NSAC Meeting N.J.T.Smith 12th March, 2018 Physics of 0!ββ - Neutrino-less double beta decay can occur if - Lepton number is not conserved - The neutrino is its own anti-particle (Majorana nature) - A heavy right-handed Majorana neutrino would provide a natural ‘see-saw’ mechanism for generating light neutrino masses - The matter - antimatter asymmetry in the Universe may be coupled to the weak sector - via CP-violating Majorana phases, ΔL ≠ 0 and leptogenesis US DOE NSAC Meeting N.J.T.Smith 12th March, 2018 Physics of 0!ββ - Provides a mechanism to determine neutrino mass and (potentially) hierarchy 2 ∑mi Uei ≡ mββ i Mixing matrix US DOE NSAC Meeting N.J.T.Smith 12th March, 2018 0!ββ Experimental challenge - Looking for full energy peak of electrons at the tail of the (expected and irremovable) two-neutrino beta decay - 0"ββ T1/2 ~ 1027- 1028 years - 2"ββ T1/2 ~ 1019 - 1021 years - Tonne scale detectors required to reach higher half-life - Need to remove/understand all backgrounds contributing to region of interest - including cosmogenic activation and c.r.
    [Show full text]
  • How Zwicky Already Ruled out Modified Gravity Theories Without Dark Matter
    How Zwicky already ruled out modified gravity theories without dark matter Theodorus Maria Nieuwenhuizen1,2 1Institute for Theoretical Physics, University of Amsterdam, Science Park 904, 1090 GL Amsterdam, The Netherlands 2International Institute of Physics, UFRG, Lagoa Nova, Natal - RN, 59064-741, Brazil Various theories, such as MOND, MOG, Emergent Gravity and f(R) theories avoid dark matter by assuming a change in General Relativity and/or in Newton’s law. Galactic rotation curves are typically described well. Here the application to galaxy clusters is considered, focussed on the good lensing and X-ray data for A1689. As a start, the no-dark-matter case is confirmed to work badly: the need for dark matter starts near the cluster centre, where Newton’s law is still supposed to be valid. This leads to the conundrum discovered by Zwicky, which is likely only solvable in his way, namely by assuming additional (dark) matter. Neutrinos with eV masses serve well without altering the successes in (dwarf) galaxies. Keywords: MOND, MOG, f(R), Emergent Gravity, galaxy cluster, Abell 1689, dark matter, neutrinos I. INTRODUCTION Niets is gewichtiger dan donkere materie52 Dark matter enters the light in 1922 when Jacobus Kapteyn employs this term in his First Attempt at a Theory of the Arrangement and Motion of the Sidereal System1. It took a decade for his student Jan Oort to work out the stellar motion perpendicular to the Galactic plane, and to conclude that invisible mass should exist to keep the stars bound to the plane2. Next year, in 1933, Fritz Zwicky applied the idea to the Coma galaxy cluster and concluded that it is held together by dark matter.
    [Show full text]
  • Development of a 50-Tonne Next-Generation Argon Detector at SNOLAB
    Development of a 50-Tonne Next-Generation Argon Detector at SNOLAB Scientific Merit Argon and xenon for DM searches Backgrounds Ultimate reach Project Overview DEAP-3600 Status Collaboration Funding Requirements Mark Boulay Schedule Queen’s University, Kingston Resource Request from SNOLAB SNOLAB Future Projects, Aug 21, 2013 Physics Context: Spin-independent DM Sensitivity (current best limit) Scientific Merit o Identification of Dark Matter remains one of the highest science priorities o Some “hints”: At low-energies either annual modulation signals (DAMA, CoGent) or excess events (CDMS, CRESST) look like low-mass WIMPs, but either low-statistics or alternate explanations; results in mutual tension. Low mass region should be fully covered shortly, since interaction cross-section relatively high. o At high-energies, astrophysical measurements (e+/e- fraction, etc.) could be interpreted as high-mass WIMPs, other explanations possible o Non-observation of Supersymmetry at LHC, combined with observed value for Higgs mass tends to “push” supersymmetry towards heavy WIMPs (> 350 GeV) for simplest remaining models (eg. cMSSM, NUHM; 5/6 parameters), although there is tension at 2-3 sigma levels in fits. o Current and planned future direct searches (LUX, DEAP-3600, XENON-1T) will explore some of the remaining parameter space, down to 2-3x10-45 cm2 SI at 1000-GeV WIMP mass, but significant space even in the simplest models remains out of reach. SD scattering remains out of reach in these models. o Detector with sensitivity of order 2x10-48 cm2 SI would be sensitive to full parameter space, capable of seeing or ruling out the simplest SUSY models DEAP-3600 will be sensitive to much of the remaining SUSY parameter space for the simplest cMSSM and NUHM models, similar sensitivity to XENON-1T for high-mass WIMPs, best-fit point for cMSSM remains out of reach for both.
    [Show full text]
  • A Data-Driven Method for Measuring Position Resolution in the DEAP-3600 Dark Matter Detector by Joseph James Willis
    A Data-Driven Method for Measuring Position Resolution in the DEAP-3600 Dark Matter Detector By Joseph James Willis A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science Department of Physics University of Alberta c Joseph James Willis, 2019 ABSTRACT DEAP-3600 is a single-phase liquid Argon dark matter detector operated at SNO- LAB in Ontario, Canada, searching for Weakly Interacting Massive Particles (WIMPs). It is well-established that astronomical and cosmological observations suggest the ex- istence of some form of unseen matter in the universe, with the WIMP as one of the primary candidates. DEAP-3600 has set the leading limit on the WIMP-nucleon spin- independent cross-section for Argon based experiments, at 3:9 × 10−45 cm2 (1:5 × 10−44 cm2) for a 100 GeV c−2 (1 TeV c−2) mass WIMP (90% C.L.). A key factor in mitigating one source of backgrounds is the removal of events caused by con- taminants on the inner surface of the acrylic vessel, achieved through means of position reconstruction and a fiducial cut on the reconstructed spherical radius. Understanding the precision of the reconstruction is therefore vital to knowing its effectiveness and so the goal of this project was to develop a method of measuring the position resolu- tion in data. Using a process of event splitting this goal was achieved, demonstrating resolutions between 30 and 45 mm at the fiduciary boundary and at the energy range considered for candidate WIMP events. ii PREFACE The hardware design and construction of the DEAP-3600 detector was done by members of the DEAP collaboration prior to my joining the experiment.
    [Show full text]