Prepared for submission to JINST The SNO+ Experiment SNO+ collaboration M. R. Anderson,a S. Andringa,b E. Arushanova,c S. Asahi,a M. Askins,d;e; f D. J. Auty,g A. R. Back,c;h Z. Barnard,i N. Barros,b; j;k;l D. Bartlett,a F. Barão,b;m R. Bayes,i E. W. Beier,k A. Bialek,n;i;g S. D. Biller,o E. Blucher,p R. Bonventre,d;e;k M. Boulay,a D. Braid,i E. Caden,n;i;a E. J. Callaghan,d;e J. Caravaca,d;e J. Carvalho,q L. Cavalli,o D. Chauhan,n;i;b;a M. Chen,a O. Chkvorets,i K. J. Clark,o;a;h B. Cleveland,n;i D. Cookman,o C. Connors,i I. T. Coulter,o;k M. A. Cox,r;b D. Cressy,i X. Dai,a C. Darrach,i B. Davis-Purcell,s M. M. Depatie,i F. Descamps,d;e J. Dittmer,l F. Di Lodovico,c;t N. Duhaime,i F. Duncan,n;i J. Dunger,o A. D. Earle,h E. Falk,h A. Farruglia,i N. Fatemighomi,n;a V. Fischer,f E. Fletcher,a R. Ford,n;i K. Frankiewicz,u N. Gagnon,n A. Gaur,g K. Gilje,g O. I. González-Reina,ab D. Gooding,u P. Gorel,g K. Graham,a C. Grant,u; f J. Grove,i S. Grullon,k E. Guillian,a A. L. Hallin,g D. Hallman,i S. Hans,v J. Hartnell,h P. Harvey,a M. Hedayatipour,g W. J. Heintzelman,k J. Heise,a R. L. Helmer,s D. Horne,a B. Hreljac,a;i J. Hu,g A. S. M. Hussain,i T. Iida,a A. S. Inácio,b; j C. M. Jackson,d;e N. A. Jelley,o C. J. Jillings,n;i C. Jones,o P. G. Jones,o;c K. Kamdin,d;e T. Kaptanoglu,d;e;k J. Kaspar,w K. Keeter,x C. Kefelian,d;e P. Khaghani,i L. Kippenbrock,w J. R. Klein,k R. Knapik,y;k J. Kofron,w L. L. Kormos,z S. Korte,i B. Krar,a C. Kraus,i;a C. B. Krauss,g T. Kroupova,o;k K. Labe,p I. Lam,a C. Lan,a B. J. Land,k;d;e R. Lane,c S. Langrock,c A. LaTorre,p I. Lawson,n;i L. Lebanowski,k G. M. Lefeuvre,h E. J. Leming,o;h A. Li,u J. Lidgard,o B. Liggins,c Y. H. Lin,n X. Liu,a Y. Liu,a V. Lozza,b; j;l M. Luo,k S. Maguire,v A. Maio,b; j K. Majumdar,o S. Manecki,n;a J. Maneira,b; j R. D. Martin,a E. Marzec,k A. Mastbaum,p;k N. McCauley,r A. B. McDonald,a P. Mekarski,g M. Meyer,l C. Miller,a C. Mills,h M. Mlejnek,h E. Mony,a I. Morton-Blake,o M. J. Mottram,c;h S. Nae,b; j M. Nirkko,h L. J. Nolan,c V. M. Novikov,a H. M. O’Keeffe,z;a E. O’Sullivan,a G. D. Orebi Gann,d;e;k M. J. Parnell,z J. Paton,o S. J. M. Peeters,h T. Pershing,f Z. Petriw,g J. Petzoldt,l L. Pickard,f D. Pracsovics,i G. Prior,b J. C. Prouty,d;e S. Quirk,a A. Reichold,o S. Riccetto,a R. Richardson,i M. Rigan,h A. Robertson,r B. C. Robertson,a J. Rose,r R. Rosero,v P. M. Rost,i J. Rumleskie,i M. A. Schumaker,i M. H. Schwendener,i D. Scislowski,w J. Secrest,aa;k M. Seddighin,a L. Segui,o S. Seibert,k I. Semenec,a;i F. Shaker,g T. Shantz,i M. K. Sharma,g T. M. Shokair,k L. Sibley,g J. R. Sinclair,h K. Singh,g P. Skensved,a M. Smiley,d;e T. Sonley,a R. Stainforth,r M. Strait,p M. I. Stringer,c;h R. Svoboda,f A. Sörensen,l B. Tam,a J. Tatar,w L. Tian,a N. Tolich,w J. Tseng,o H. W. C. Tseung,w E. Turner,o R. Van Berg,k J. G. C. Veinot,g C. J. Virtue,i B. von Krosigk,l E. Vázquez-Jáuregui,ab;n;i J. M. G. Walker,r M. Walker,a S. C. Walton,i J. Wang,o M. Ward,a O. Wasalski,s J. Waterfield,h J. J. Weigand,l R. F. White,h J. R. Wilson,c;t T. J. Winchester,w P. Woosaree,i A. Wright,a J. P. Yanez,g M. Yeh,v S. Yu,i T. Zhang,f Y. Zhang,g T. Zhao,a K. Zuber,l;ac A. Zummo,k aQueen’s University, Department of Physics, Engineering Physics & Astronomy, Kingston, ON K7L 3N6, Canada bLaboratório de Instrumentação e Física Experimental de Partículas (b), Av. Prof. Gama Pinto, 2, 1649-003, Lisboa, Portugal cQueen Mary, University of London, School of Physics and Astronomy, 327 Mile End Road, London, E1 4NS, UK dUniversity of California, Berkeley, Department of Physics, CA 94720, Berkeley, USA eLawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720-8153, USA f University of California, Davis, 1 Shields Avenue, Davis, CA 95616, USA gUniversity of Alberta, Department of Physics, 4-181 CCIS, Edmonton, AB T6G 2E1, Canada hUniversity of Sussex, Physics & Astronomy, Pevensey II, Falmer, Brighton, BN1 9QH, UK iLaurentian University, Department of Physics, 935 Ramsey Lake Road, Sudbury, ON P3E 2C6, Canada k University of Pennsylvania, Department of Physics & Astronomy, 209 South 33rd Street, Philadelphia, PA 19104-6396, USA j Universidade de Lisboa, Faculdade de Ciências (FCUL), Departamento de Física, Campo Grande, Edifício C8, 1749-016 Lisboa, Portugal lTechnische Universität Dresden, Institut für Kern und Teilchenphysik, Zellescher Weg 19, Dresden, 01069, Germany mUniversidade de Lisboa, Instituto Superior Técnico (IST), Departamento de Física, Av. Rovisco Pais, 1049-001 Lisboa, Portugal nSNOLAB, Creighton Mine #9, 1039 Regional Road 24, Sudbury, ON P3Y 1N2, Canada oUniversity of Oxford, The Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH, UK pThe Enrico Fermi Institute and Department of Physics, The University of Chicago, Chicago, IL 60637, USA qUniversidade de Coimbra, Departamento de Física and Laboratório de Instrumentação e Física Experi- mental de Partículas (LIP), 3004-516, Coimbra, Portugal r University of Liverpool, Department of Physics, Liverpool, L69 3BX, UK sTRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3, Canada t King’s College London, Department of Physics, Strand Building, Strand, London, WC2R 2LS, UK uBoston University, Department of Physics, 590 Commonwealth Avenue, Boston, MA 02215, USA vBrookhaven National Laboratory, Chemistry Department, Building 555, P.O. Box 5000, Upton, NY 11973- 500, USA wUniversity of Washington, Center for Experimental Nuclear Physics and Astrophysics, and Department of Physics, Seattle, WA 98195, USA xIdaho State University, 921 S. 8th Ave, Mail Stop 8106, Pocatello, ID 83209-8106 yNorwich University, 158 Harmon Drive, Northfield, VT 05663, USA zLancaster University, Physics Department, Lancaster, LA1 4YB, UK aaArmstrong Atlantic State University, 11935 Abercorn Street, Savannah, GA 31419, USA abUniversidad Nacional Autónoma de México (UNAM), Instituto de Física, Apartado Postal 20-364, México D.F., 01000, México acMTA Atomki, 4001 Debrecen, Hungary Abstract: The SNO+ experiment is located 2 km underground at SNOLAB in Sudbury ON, Canada. A low background search for neutrinoless double beta (0νββ) decay will be conducted using 780 tonnes of liquid scintillator loaded with 3.9 tonnes of natural tellurium, corresponding to 1.3 tonnes of 130Te. This paper provides a general overview of the SNO+ experiment, including detector design, construction of process plants, commissioning efforts, electronics upgrades, data acquisition, and calibration systems. SNO+ is reusing the acrylic vessel, PMT array, and electronics of the SNO detector, having made a number of experimental upgrades and essential adaptations for use with the liquid scintillator. With low backgrounds and a low energy threshold, SNO+ will also pursue a rich physics program beyond the search for 0νββ decay, including studies of geo- and reactor antineutrinos, supernova and solar neutrinos, and exotic physics such as the search for invisible nucleon decay. The SNO+ approach to the search for 0νββ decay is scalable: a future phase with high 130Te-loading is envisioned to probe an effective Majorana mass in the inverted mass ordering region. Keywords: Double-beta decay detectors; Neutrino detectors; Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators) ArXiv ePrint: XXXX.YYYYY Contents 1 Introduction1 1.1 Physics Goals1 1.2 The SNO+ Detector4 2 Development of Active Target Materials7 2.1 The SNO+ Liquid Scintillator8 2.2 Active Target Deployment Systems9 2.2.1 Water Systems 10 2.2.2 Scintillator Process Systems 10 2.2.3 Tellurium Process Systems 13 2.3 Material Compatibility 14 3 Detector Hardware Additions and Upgrades 16 3.1 Leaching of Radon Daughters 16 3.2 Hold-Down Rope-Net 17 3.3 PSUP and PMT Repairs 19 3.4 Cover Gas Systems 20 4 Electronics Upgrades 22 4.1 Refurbishing the SNO Electronics 23 4.2 Readout System Upgrade 24 4.3 Analog Trigger Upgrade 24 5 Data Acquisition and Processing 26 5.1 Slow Control 26 5.2 Data Acquisition and Monitoring Software 26 5.3 Data Processing 27 5.4 Detector Simulation 28 5.5 Grid Processing 29 6 Calibration Systems 30 6.1 Calibration Goals 31 6.2 Radon Mitigation for Calibration Hardware 31 6.3 Source Manipulator System 32 6.3.1 Umbilical Retrieval Mechanism 33 6.3.2 Interface with Acrylic Vessel 35 6.3.3 Source Umbilical 36 6.3.4 Umbilical Flasher Object 37 6.3.5 Source Interface 38 6.4 Camera System 39 – i – 6.5 Optical Calibration Sources 40 6.5.1 TELLIE 41 6.5.2 AMELLIE 42 6.5.3 SMELLIE 44 6.5.4 Laserball 45 6.5.5 Supernova Source 46 6.5.6 Cherenkov Source 48 6.6 Radioactive Calibration Sources 49 6.6.1 16N Calibration Source 50 6.6.2 Americium Beryllium Calibration Source 50 6.6.3 46Sc Calibration Source 52 6.6.4 Untagged Radioactive Calibration Sources 53 7 Conclusions and Outlook 55 – ii – 1 Introduction The Sudbury Neutrino Observatory (SNO) experiment [1] took data from 1999 to 2006, before 2 1 returning its target heavy water ( H2O or D2O) to the supplier.