Transcript Document
Soudan Underground Laboratory Features Moderate depth (2100 mwe) augmented with active muon veto shield Existing infrastructure (power, water, networking, personnel, cranes, etc) and running experiments ESO and EPS in place External Sales Org = non-overheaded user invoicing mine labor, supplies, cryogens… Experimental Planning Statement = new experiments or screeners can be approved quickly (safety, materials, scheduling) Radon levels change seasonally: 300 – 700 Bq/m3 Space for expansion, including enough for a 10 m dia x 6 m high water tank Mature Education and Outreach program with visitor’s center and tours Soudan Underground Laboratory HPGe Screening (SOLO) Cu Electroform New Clean Room Fully lined with an active muon veto Gamma screening and isotope ID High Purity Germanium Diode-M 0.5kg in heavy use by XENON managed by Brown U (Gaitskell) http://particleastro.brown.edu/SOLO Gator 1.2 kg Florida Start-up moved (Mar 2007) to Gran Sasso Gopher 1.2 kg Coming in January CDMS has many samples M. Laubenstein: in screening sites around the world, the main backgrounds are internal to the detector and shielding itself Copper Electroforming (Reeves & Sons, LLC) Funded via DOE Small Business Innovation Research grant TASKS: • Electroform and test a large vacuum copper cryostat structural integrity up to 2 atm, cooling capabilities, and electronic noise. • Measure the amount of thorium-232 in the electroformed copper. PNNL measured < 1uBq/kg of 232Th in the copper • New Screener R&D to measure large quantities of Cu down to 0.1 uBq/kg Endcap mandrel (16" diam x 14”) square cross arm mandrel for cold finger + wires A 2090 mwe experimental hall (35’x40’x100’) lined with an active muon veto shield. Ceiling veto panels Veto tube test stack Refurbished Soudan2 Muon Veto shield New gas system and controllers Pump jacks for tube repair New DAQ: Database of muons available to users: time stamp and location On Mezzanine: New Clean room Additional coincident tubes Structural support for lead cages An interactive graphical interface program retrieves the data remotely. Currently studying muon angular distribution, multiplicity, shower fragments Preliminary Angular distribution from new data compared to actual topological map of overburden S W N E S What moves into this space? Medtronics soft memory error study is already there Dark Matter Ge Detector (December 2007) Neutron Multiplicity Counter: DUSEL R&D project (Case and UC Santa Barbara) Ultra-sensitive Screeners: Beta cage, XIA ab counter, and Reeves Cu screener Still room for a large multi-purpose water tank Good match for the space and good usage of a pre-existing muon shield 100 ft n multiplicity more muon tubes Clean room Clean room Beta Cage mezzanine Ge Dark Matter Medtronics Water tank Muon veto shield Muon veto shield Muon veto shield Active Shielding Active Muon Veto outside tank reduces for more effective depth background from neutrons made in the shield 99.5% Muon Veto reduces n’s from shield by x 200 and n’s produced in rock by 4 Total n bkgd ~ 8 x 10-6 n/day/kg Active Shielding Active Muon Veto outside tank reduces for more effective depth background from neutrons made in the shield For Homestake depth, both curves drop by 30-40 Without an active veto, 4850 mwe is 4 times worse than 2100 mwe Total n bkgd