1. Blas Cabrera - Stanford UniversitySuperCDMSPage 1 CDMS-II Completion and SuperCDMS Collaboration Meeting UC Santa Barbara February 12, 2005 Blas Cabrera Stanford University - KIPAC

2. Blas Cabrera - Stanford UniversitySuperCDMSPage 2 Path to SuperCDMS SUF Run 21 - 2002 –Tower 1 (4 Ge and 2 Si detectors) at SUF (neutron limited) Soudan Run 118 - Oct 2003 to Jan 2004 –Tower 1 at Soudan - PRL 93, 211301 (2004) best by x4 –More detailed PRD submission in Feb 2004 Soudan Run 119 - Mar 2004 to Aug 2004 –Towers 1& 2 run has increased Ge data x3 and Si data x8 –Analysis well underway plan to announce results at Apr APS Soudan Run 120 - 2005 –Towers 1-5 run is expected to increase Ge exposure x6 SuperCDMS Development Project (possible delay in start) –Towers 1-5 continued running is expected to increase Ge x3 –Development Project - 5 kg Ge new detectors run at Soudan AGENCY APPROACHES AND STRATEGIES

3. Blas Cabrera - Stanford UniversitySuperCDMSPage 3 133 Ba gamma & 252 Cf neutron calibrations Use phonon risetime and charge to phonon delay for discrimination of surface electrons “betas” Cuts and analysis thresholds determined entirely from calibration data with WIMP search data blinded until after the cuts and thresholds were set. gammas neutrons ejectrons

4. Blas Cabrera - Stanford UniversitySuperCDMSPage 4 Simulation setting cut with calibration Calibration - Gaussian distribution 1000 evts Data - same distribution 100 evts Data x10 Cal x10 Cut at last event Probability 0.1 of event past cut On average area beyond last event = 1 On average area beyond cut = 0.1

5. Blas Cabrera - Stanford UniversitySuperCDMSPage 5 Detector MC progress Use detector MC to improve our understanding of the origin of timing and partition response (Matt Pyle)

6. Blas Cabrera - Stanford UniversitySuperCDMSPage 6 About to Operate Five Towers in Soudan

7. Blas Cabrera - Stanford UniversitySuperCDMSPage 7 Completed fabrication & testing of T3-5 4.5 kg of Ge !!! (1 kg Si)

8. Blas Cabrera - Stanford UniversitySuperCDMSPage 8 CDMS-II Scientific Reach CDMS-II explores MSSMs in series of runs SUF Tower 1 in 2002 Soudan Tower 1 in 2003 Soudan Tower 1-2 in 2004 Soudan Towers 1-5 2005 Another factor of 3-5 improvement at Soudan past CDMS-II (neutrons) THEN MUST GO DEEPER - Planning SuperCDMS at SNOLab in Canada EGRET gammas as DM annihilation astro-ph/0408272 DAMA EDELWEISS

9. Blas Cabrera - Stanford UniversitySuperCDMSPage 9 Sensitivity Reach of CDMS-II & SuperCDMS

10. Blas Cabrera - Stanford UniversitySuperCDMSPage 10 Summary and bold future vision Limit at SUF 2002 (during CDMS II) Development Project 5 kg of Ge 2008 SuperCDMS Phase C 1000 kg of Ge World-best limit today SuperCDMS Phase A 25 kg of Ge 2011 CDMS II goal 2006 SuperCDMS Phase B 150 kg of Ge 2014

11. Blas Cabrera - Stanford UniversitySuperCDMSPage 11 What do we learn if we see a signal? Our recent 90% C. L. corresponds to < 1 evt per 8 kg-d for Ge Suppose we see 8 events at the rate of 1 evt per 50 kg-d of Ge Then mass & cross section determined as shown and SI vs SD determined from different targets Suggest properties to look for at LHC and future ILC If SUSY seen first at LHC would still want to determine if LSP is the dark matter, SO NEED TO PUSH DIRECT DETECTION EITHER WAY A convincing signal would motivate large TPC such as DRIFT for velocity distribution actual signal

12. Blas Cabrera - Stanford UniversitySuperCDMSPage 12 Compare with Competition NaI - annual modulation with no discrimination (<6 pe/keV) –DAMA signal is suspect because near threshold (systematics) –LIBRA - 250 kg new installation (still no discrimination) Cryogenic technologies - lowest intrinsic threshold (10 6 phon/keV) –(Super)CDMS Ge & Si ionization + phonon + timing (best) –EDELWEISS Ge thermal + ionization (no timing) –CRESST CaWO 3 thermal + scintillation (no light for W) Liquid Xenon - intrinsically high threshold (~1 pe/keV) –ZEPLIN I & XMASS scintillation (uncalibrated result) –XENON scintillation + ionization (need demo of threshold & stability) Superheated liquids - no energy resolution (counting) –SIMPLE & PICASO CF 3 Br & CF 3 I (need demo of stability) Liquid He (HERON) and Ne (NEON) detectors good for SD only TPC DRIFT - good for future directionality (not enough mass now)

13. Blas Cabrera - Stanford UniversitySuperCDMSPage 13 Propose to operate at SNOLab (6060 mwe) At SUF –17 mwe –0.5 n/d/kg At Soudan –2090 mwe –0.5 n/y/kg At SNOLab –6060 mwe –1 n/y/ton Log 10 (Muon Flux) (m -2 s -1 ) Depth (meters water equivalent)

14. Blas Cabrera - Stanford UniversitySuperCDMSPage 14 SuperCDMS Roadmap to SNOLAB

15. Blas Cabrera - Stanford UniversitySuperCDMSPage 15 Detector development plans

16. Blas Cabrera - Stanford UniversitySuperCDMSPage 16 Detector development (Paul) Existing ZIPs 3” dia x 1 cm thick Thicker ZIPs 3” dia x 1” thick (base detector) Explore larger ZIPs to 4” dia and up to 4 cm thick CIS - Balzers & Ultratech Varian - Balzers; CIS - Laurell & EV aligner

17. Blas Cabrera - Stanford UniversitySuperCDMSPage 17 Interleaved Ionization electrodes concept Alternative method to identify near-surface events –Phonon sensors on both sides are virtual ground reference. –Bias rails at +3 V connected to one Qamp –Bias rails at -3 V connected to other Qamp –Signals coincident in both Qamps correspond to events drifted out of the bulk. –Events only seen by one Qamp are < 1.0 mm of the surface.

18. Blas Cabrera - Stanford UniversitySuperCDMSPage 18 Interleaved Ionization electrode design Design details –To maintain ~60 pF of capacitance requires keeping bias and ground rails ~ 1 mm apart. –Phonon sensors ‘contained’ within the (200  m wide) ground rails. –First wafer recently completed: Ground ring around side to define the ‘Qouter’ volume containing all surfaces

19. Blas Cabrera - Stanford UniversitySuperCDMSPage 19 Identify and Reduce 210 Pb, 14 C & 40 K Use Van de Graaff to attract positive ion radon daughters 222 Rn -> 218 Po -> 214 Pb -> 214 Bi -> 214 Po -> 210 Pb Run VdG for 2 hrs Wipe surface & count 3.8d3.1m27m20m.16ms 250kV ground

20. Blas Cabrera - Stanford UniversitySuperCDMSPage 20 New Read-out schemes Two-stage SQUIDs for reading out new phonon sensors –Allows lower R n, more TESs, better phonon sensor surface area coverage. Will improve effectiveness of present phonon risetime cut even further. –Allows move to Al-Mn TESs to overcome W Tc variability Resitivity of Al-Mn < W, hence risk /design constraint of electro-thermal oscillation if change-over to two-stage SQUIDs not implemented. –Commensurate with NIST-style time-domain multiplexing. ZIP detector phonon pulses are probably sufficiently slow to utilize this scheme effectively to reduce the readout wiring to room temperature that would otherwise be required.

21. Blas Cabrera - Stanford UniversitySuperCDMSPage 21 Two-stage SQUID configuration –Ionization detector transformer-coupled to first-stage SQUID –Eliminate potential microphonic read-out issues associated with FET readout –Eliminate IR photon leakage –Eliminate heated FET load on 4 K –Transformer ~ 12 mm x 6 mm chip, fabricated at NIST. –Critically damped circuit, ~1 MHz sampling required. –Simulations give 0.4 keVee FWHM Ionization read-out using SQUIDs

22. Blas Cabrera - Stanford UniversitySuperCDMSPage 22 How to build a 1000 kg experiment in stages

23. Blas Cabrera - Stanford UniversitySuperCDMSPage 23 Schematic of new ‘SNObox’ x3 Exploring cryocooler system with little or no cryogen servicing

24. Blas Cabrera - Stanford UniversitySuperCDMSPage 24 Conclusion For CDMS-II important that we –complete Run 118 PRD –complete Run 119 analysis PRL and futher PRD –start and complete Run 120 For SuperCDMS we have –submitted base support proposals for NSF groups –submitted Development Project proposal to DOE/NSF –submitted MRI for Cryosystem to NSF –started detector R&D at Stanford –started cryosystem R&D at Fermilab And we need to –push on NSF for base support decision and DOE/NSF for review –Look for new collaborators (Nat Labs, UMN, UCSB, & Canada)