DEAP-1 for SNOLAB2009 Report to SNOLAB2009 Chris Jillings on behalf of the DEAP-1 team

DEAP-1 for SNOLAB2009 Timeline July 4, 2008 Fill –Gen 1 clean chamber –Topup: Radon spike –Background studies Jan March 2009 –Emanation measurements –Improved design/manufacture of chamber March 19, 2009 Fill –Gen 2 clean chamber –Radon trap –Install new DAQ –Strike –PSD running –Background studies Future

DEAP-1 for SNOLAB2009 Improvements Since October 2008 Backgrounds Reduced Factor of 10 –And much better understood DAQ/Electronics –Installed by TRIUMF team (F. Retiere/P.-A. Amaudruz) –Throughput ~x10 higher –Using hardware that will be used for DEAP-3600 PSD improved

DEAP-1 for SNOLAB2009 Zfit Calibration Zfit is a calibrated measure of position in the detector.

DEAP-1 for SNOLAB2009 Background Rates July 4, 2008 Run 2-3 mHz steady state Top-up added large 222 Rn spike Used to develop U-chain tags 0 10

DEAP-1 for SNOLAB2009 Emanation Measurement

DEAP-1 for SNOLAB2009 Emanation Measurement While warm treated DEAP-1 as emanation chamber –Pumped to high vacuum –Allowed to emanate for many days –134 +/- 19 Rn emanated/day –Repeated measurement with DEAP-1 chamber removed and blanked off: 6 +/- 4 Rn atoms/day –Also did background (“zero exposure”) emanations. Emanation results consistent with all Radon coming from chamber. Emanation of reflective paint at Queen’s was equal within error to emanation from all chamber.

DEAP-1 for SNOLAB2009 Improvement Details Generation I: 2008 Produced in glovebox Sanded surfaces –~20 particles/cm 2 left on acrylic –From 175 to mBq/kg U depending on brand/batch –0.01 to 3 mBq Rn in DEAP-1 TPB on inner surface –<4 mBq/kg U/Th Exposure during evaporation –~4 bgnd events/year Sealing of vacuum vessel –Possible admission of Rn in shipping Generation II: 2009 Improved glovebox/Rn monitoring Sanding Improvements –Used clean sandpaper –High-pressure rinse inside glove box As before Vacuum chamber was leak tested in glove box and filled with Rn-free air.

DEAP-1 for SNOLAB2009 Improvement Details (2) Generation I: failed fills allowing unknown quantity air into DEAP-1 Radon in argon during fill –Unknown how much gets through cooling coils –Could have ~1 day exposure to high Radon loads Background analysis –Offline, interpretations developed over weeks and months. –Data show surface  rates measurable before fill Generation II: 2009 Procedures improved. –Venting through bubblers –Last fills and top-ups worked Radon filter in DEAP-1 –Cold carbon trap Rn just above Argon boiling point –Prototype built. Tested. –Installed prototype for Mar16 fill Near-Online and Automatic Analysis

DEAP-1 for SNOLAB2009 Radon Filter Prototype charcoal filter operating temperature -110C. No measurable Rn punch through in tests at Queen’s. Used for March 19 fill. Similar but larger device to be used on DEAP-3600.

DEAP-1 for SNOLAB2009 Background Rates July 4, 2008 Run 2-4 mHz steady state Top-up added large 222 Rn spike Used to develop U-chain tags March 19, 2009 Run 0.2 to 0.4 mHz No initial spike

DEAP-1 for SNOLAB2009 U Chain: 222 Rn and short-lived daughters Model: 222 Rn and 218 Po decay in LAr (100% eff detection). 214 Po is on surface (50% eff det).

DEAP-1 for SNOLAB2009 Th Chain: 220 Rn to 216 Po to 212 Pb Seen at correct  energy with same z position in detector 30 events in 236 hrs (Mar 19 run)  t<1s

DEAP-1 for SNOLAB2009 Thorium Chain: 212 BiPo (300 ns)

DEAP-1 for SNOLAB2009  Backgrounds Rate from coincidence tag (40 events each of 222 Rn Rn) 10 days livetime

DEAP-1 for SNOLAB2009 Backgrounds in DEAP-1 Current background rate in ROI ( pe) is 0.15 mHz Need absolute background of < 2 nHz for DEAP-3600, or 2 micro-Hz before position reconstruction for surface events

DEAP-1 for SNOLAB2009 Backgrounds Clear evidence for Rn from U and Th chain based on alpha-coincidence tags Improving calibrations of light yields in TPP. To improve understanding of all alpha events below full-energy (in Argon) alpha peaks. This could include 210 Po (daughter of 210 Pb).

DEAP-1 for SNOLAB2009 PSD Dataset Events x10 8 Days to 10 8 Surface arXiv: ~20120 July 4, Mar 16, 2009 New DAQ (Could be halved with hotter source.) Mar 16, 2009 ~ Faster DAQ: >10 8 events in 22 days Data sets so far: 12x10 -9 demonstrated 7x10 -9 after analysis of all events on disk.

DEAP-1 for SNOLAB2009 Prototype of DEAP-3600 DAQ Installed and maintained by TRIUMF group. Allows data rates of ~15 Mbytes/sec ~600 events * 2 channels * bit samples/ch CAEN V1720 WFD MIDAS DAQ (well supported at TRIUMF) Scalers to be implemented V1720 Struck scaler Linux computer

DEAP-1 for SNOLAB2009 Future DEAP-1 is our most sensitive tool for understanding backgrounds. We are using DEAP-1 as a test bench for process systems and to measure activities in acrylic surfaces and TPB. We are using DEAP-1 to prototype and test electronics and DAQ. We are requesting to run DEAP-1 at SNOLAB for the next 2 to 3 years. We understand that a relocation may be necessary.

DEAP-1 for SNOLAB2009 end

DEAP-1 for SNOLAB2009 Scientists who have worked u/g on DEAP1 Mark Boulay 1, Bei Cai 1, Jeff Lidgard 1, Ian Lawson 2, Kevin Graham 3, Fraser Duncan 2, Chris Jillings 2, Paradorn Pasuthup 1, Noel Gagnon 2, Peter Skensved 1, Ueshima Kota 4, Hugh Lippincott 7, Kiyoshi Masui 1, Luc Gatien 2, Rafael Hakobyan 5, Kevin Olsen 5, Shawn Ligocki 1, Takashi Iida 4, Shawn Compton 3, Victor Golovko 1, Cameron Hurst 1, Michael Ronquest 6, Reyco Henning 6, Perry Young 1, Zach Fairchild 2, Brian Wong 2, TJ Robotham 2, Bruce Cleveland 2, Eoin Odwyer 1, Oleg Chekvoretz 2, Eric Vazquez 2,Marcin Kuzniak 1, Fabrice Retiere 8,Pierre-Andre Amaudruz 8, Rob Bark 2, Corina Nantais 1, Aline Trosset 1, Berta Beltran 5, 1: Queen’s 2: SNOLAB 3: Carleton 4: ICRR/Honda Canada Fellow 5: U. Alberta 6: U.N.C. 7:Yale 8: TRIUMF PhD, Graduate Student, Undergraduate student or degree