Jim Brennan for the WATCHMAN Collaboration Detector Engineering Design Simulation courtesy G. Jocher/J Learned, U Hawaii This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA Lawrence Livermore National Security, LLC Global reactor antineutrino fluxes Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under Contract DE-AC04-94AL SAND Number WATer CHerenkov Monitoring of Anti-Neutrinos

Lawrence Livermore National Laboratory Sandia National Laboratories  Detector Design based on multiple parameters  Perry Reactor Site – Morton Salt Mine  Cavern size limits detector volume – Existing cavern 80’ x 60’ x 78’  Cylinder makes most efficient use of space + uniformity of coverage/sensitivity  Everything must fit down the mine shaft  Modular design.  Engineering Requirements  Exterior Tank design  PMT support structure – Light barriers  Water purity / Water system  Photomultiplier selection, QA, and characterization  Detector assembly  Possible upgrade to water based liquid scintillator  Physics  Gd doped water  Photocathode coverage 2

Lawrence Livermore National Laboratory Sandia National Laboratories  Main Detector and Cavern  PMT Specifications  PMT Wiring and Electronics  Water System  Data Acquisition  Mine Infrastructure 3

Lawrence Livermore National Laboratory Sandia National Laboratories  Main Detector and Cavern  Cavern Retrofit  Main Tank ~16m x 16m 304 SS  Modular PMT support structure  PMT Specifications  PMT Wiring and Electronics  Water System  Data Acquisition  Mine Infrastructure We have experts with years of experience in the design, construction, and operation of large liquid based detectors. 4

Lawrence Livermore National Laboratory Sandia National Laboratories 5 Existing washout area Existing cavern has debris from previous experiment Catwalks, electrical, lighting still intact Cavern liner has mostly fallen to bottom Concrete lab floor is badly damaged Existing transformer and water system components have not been evaluated Collapsed ventilation ducting partially blocking entry 78 feet

Lawrence Livermore National Laboratory Sandia National Laboratories 6 Excavate construction ramp to the main mine shaft Old concrete floor removed and replaced with steel flooring All debris removed Washout ramp filled with all debris from existing cavern Old concrete floor removed and replaced with steel flooring

Lawrence Livermore National Laboratory Sandia National Laboratories 7

Lawrence Livermore National Laboratory Sandia National Laboratories 8

Lawrence Livermore National Laboratory Sandia National Laboratories 9 Bolted tanks can be designed to the dimensions desired Individual panels will fit down mine shaft Flexible design allows virtually unlimited customization All Dimensions in Feet

Lawrence Livermore National Laboratory Sandia National Laboratories 10 Cables hold 96 columns of 30 PMTs PMTs (724 top and 724 bottom) are mounted to framing via PMT housing with optical barrier 320 side veto PMTs total – 81 top and bottom Lower framing has outer radius of 6.9m and inner radius of 6.4m and supports tension cables Drawn with 12” PMTs 4810 Total PMTs

Lawrence Livermore National Laboratory Sandia National Laboratories 11 Truss support members Trusses connect to PMT cable support beams Tank

Lawrence Livermore National Laboratory Sandia National Laboratories 12 Cables are spaced to accept PMT housings. Cables are attached to support beams and tensioned with turn buckles Inner cables support Fiducial PMTs - outer cables support Veto PMTs and signal/HV cables

Lawrence Livermore National Laboratory Sandia National Laboratories 13 PMT housing is injection molded to reduce cost Housing can be molded in white HDPE, ABS, or other material Making the material white give it diffuse reflector properties – no additional Tyvek liner needed PMT is supported in housing and wires route out and up the support cables Thin front panel of Black ABS plastic or similar material makes good light absorber – Mounts with panel clips or other fasteners

Lawrence Livermore National Laboratory Sandia National Laboratories 14 PMT housings slide directly onto support cables. Pins or bolts lock assembly into position on cables Can be positioned precisely and with ease Black absorber overlaps neighboring housings – completing light barrier Fiducial PMTs use 40.9 cm spacing Veto PMTs eliminate black absorber sheet

Lawrence Livermore National Laboratory Sandia National Laboratories 15 Similar injection molded housing No cable mounts – these bolt directly to frame Smaller housing dimension allows tighter packing

Lawrence Livermore National Laboratory Sandia National Laboratories PMTs to cover upper and lower fiducial volume Spacing can be optimized for ideal PMT count and spacing Having separate black absorber means spacing can be adjusted and a new absorber installed 304 SS Frame Assemblies hold both Fiducial facing and Veto PMTs. Frames bolt to I-beams built into structure

Lawrence Livermore National Laboratory Sandia National Laboratories 17 Similar stainless steel frames, designed to fill gaps at outer circumference of frame

Lawrence Livermore National Laboratory Sandia National Laboratories 18 Signal / HV cables are bundled and routed up PMT support cables 96 bundles of ~ 2” in diameter at top of tank

Lawrence Livermore National Laboratory Sandia National Laboratories 19 *Outer tank removed

Lawrence Livermore National Laboratory Sandia National Laboratories 20  Side PMTs, Top PMTs, Structure, Cables ~ 82,000 pounds  Tank ~ 60,000 pounds  Lower PMTs and Support Structure ~ 31,200 pounds  Signal Cables ~ 24,000 pounds  Buoyant Forces ~ 84,175 pounds (12 inch tubes)  Total Tank – 849,408 gallons  Displaced Volume – 21,661 gallons  Actual Gallons Needed – 827,747 gallons  Total Water – 6,895,132 pounds (3,447 tons)  Total Detector (without water) ~ 200,000 pounds (100 tons)  Total Mass ~ 7,090,000 pounds (3,545 tons)

Lawrence Livermore National Laboratory Sandia National Laboratories 21 Bolted tanks can be designed to the dimensions desired Individual panels will fit down mine shaft Flexible design allows virtually unlimited customization $516,416 *Base price without modifications Contacted USA Tank for Quote: 304 SS 16m x 16m Choice of seal Choice of input ports Will install in mine 10 – 12 weeks for delivery

Lawrence Livermore National Laboratory Sandia National Laboratories  Initial design concept has been completed and we are reviewing design criteria to best fit the physics (Tank and Frame)  Initial cost estimates have been determined – as the final design is refined, more rigorous costing can be determined  Conceptual design work on PMT supports, cabling, etc. complete 22