Gaitskell CDMS II Status + CDMS I / III / CryoArray Direct Detection of SUSY Cold Dark Matter Rick Gaitskell Brown University, Department of Physics see information at CDMS Dark Matter - Aachen EPS - 17 July 2003 Rick Gaitskell CDMS Collaboration Santa Clara University B.A. Young Stanford University L. Baudis, P.L. Brink, B. Cabrera, C. Chang, T. Saab University of California, Berkeley V. Mandic, P. Meunier, N. Mirabolfathi, W. Rau, B. Sadoulet, A. Lu University of California, Santa Barbara D.A. Bauer, R. Bunker, D.O. Caldwell, R. Ferril, R. Mahapatra, H. Nelson, J. Sander, C. Savage, S. Yellin University of Colorado at Denver M. E. Huber University of Minnesota P. Cushman, L. Duong, A. Reisetter Brown University R.J. Gaitskell, J.-P. Thompson, M. J. Attisha, L de Viveiros Case Western Reserve University D.S. Akerib, D. Driscoll, S. Kamat, T.A. Perera, R.W. Schnee, G.Wang Fermi National Accelerator Laboratory M.B. Crisler, R. Dixon, D. Holmgren Lawrence Berkeley National Laboratory J.H Emes, R.R. Ross, A. Smith National Institute of Standards and Technology J. Martinis Princeton University T. Shutt CDMS Dark Matter - Aachen EPS - 17 July 2003 Rick Gaitskell STATUS: CDMS II - Cold & Running First Dark achieved 12 detectors - cold & checked SOUDAN 6 Ge+6 Si Cryo / DAQ / Electronics / Analysis operating Tower 1 - currently calib Prev. 1/2 Stanford - b/g well understood 120 live days (50 kg-days Ge) Tower not changed -> Soudan Will be some improvement at depth Need stats to study bg (Prelim looks good) Tower 2 All New detectors Some improvements made in b/g handling Not yet measured b/g for this tower Initial SOUDAN Similar run to Stanford: 50 Ge kg-days Looking for Zero background (ZBG) >10 keV Expect very clean analysis Tower 1 Previously 1/2 year Stanford Tower 2 (New dets) CDMS Dark Matter - Aachen EPS - 17 July 2003 Rick Gaitskell Direct Detection: History & Future Oroville (88) [m = ?? GeV - if significantly better limit obtained at different mass] 90% CL Limit on Cross section for 60 GeV WIMP (scalar coupling) ~1 event kg -1 day -1 ~1 event kg -1 yr -1 ~1 event 100 kg -1 yr -1 LHC Not meant to be a complete list - seeDifferent Colours Indicate Different Technologies NOW rjg [m=20 GeV] Homestake (87) H-M (94) Hberg-Moscow (98), IGEX (00) DAMA (96) UKDMC (96) [m=100 GeV] DAMA (98) DAMA (00) Gaitskell (astroph ) CDMS SUF (99) CDMS SUF (02) Edelweiss (98) Edelweiss (01) ZEPLIN I Xe (02) Edelweiss (02) DRIFT II 1 kg CS 2 (T) ZEPLIN II+III 10 kg Xe (T) XENON / ZEPLIN 1t Xe (T) CDMS Soudan (T) 7 kg Ge+Si Cryodet Majorana Phase 1 (T) GENINO (T) 100 kg Ge Diode GENIUS (T) 100 kg Ge Diode CryoArray (T) tonne Cryodet DRIFT III 100 kg CS 2 (T) Ge NaI Cryodet (T) Target Signal Liq Xe Gas CS 2 CDMS Dark Matter - Aachen EPS - 17 July 2003 Rick Gaitskell Latest & Greatest Limits on Scalar C-S for WIMPs Latest Edelweiss result (updated May 2003) ZEPLIN I result (announced Sept 2002) CDMS I result (updated June 2003) ZEPLIN I - Liq nat130 Xe Edelweiss - nat72 Ge CDMS I Final~1 event kg -1 day -1 CDMS Dark Matter - Aachen EPS - 17 July 2003 Rick Gaitskell Detectors provide near-perfect event-by-event discrimination against otherwise dominant electron-recoil backgrounds 616 Neutrons (external source) 1334 Photons (external source) CDMS Background Discrimination Explanation of basics (On-going improvements in rejection) Ionization Yield (ionization energy per unit recoil energy) depends strongly on type of recoil Most background sources (photons, electrons, alphas) produce electron recoils WIMPs (and neutrons) produce nuclear recoils Ionization Threshold 233 Electrons (tagged contamination) Particles (electrons) that interact in surface dead layer of detector result in reduced ionization yield, very good (>95%) against surface electron-recoil backgrounds bulk > 1 / 2 years background >> 1 / 2 years signal !! NOT A SIMULATION! >98% CDMS Dark Matter - Aachen EPS - 17 July 2003 Rick Gaitskell CDMS II - Calibrations at Stanford ZIP Detector (250g Ge, or 100 g Si) 20,400 gamma events (5-100 keV) ~ 1 week continuous calibration with 60 Co source = ~one count in 12 years of gamma background (assuming project background level of 0.25 counts/keV/kg/day at CDMSII Soudan. Calibration still Poisson stats/neutron background limited ) Sensitivity better than 1 WIMP per year per detector Neutrons (external source) Gammas (external source) Trigger Threshold 1334 gamma events, 616 neutron events rjg CDMS Dark Matter - Aachen EPS - 17 July 2003 Rick Gaitskell 380 m Al fins 60 m wide Photolithographic patterning like CMOS but 1 big chip 37 cells per quadrant 7x4 array of W transition-edge sensors per cell, with Al collector fins covering only fraction of surface ZIP Detector Phonon Sensor Close-up A B C D CDMS Dark Matter - Aachen EPS - 17 July 2003 Rick Gaitskell Am 241 : 14, 18, 20, 26, 60 kev Cd Al foil : 22 kev Demonstration of xyZIP Position Sensitivity Cd 109 : 22 kev i.c. electr 63, 84 KeV Delay Plot AD CB CDMS Dark Matter - Aachen EPS - 17 July 2003 Rick Gaitskell Working at Soudan CDMS Dark Matter - Aachen EPS - 17 July 2003 Rick Gaitskell STATUS: CDMS II - Cold & Running First Dark achieved 12 detectors - cold & checked SOUDAN 6 Ge+6 Si Cryo / DAQ / Electronics / Analysis operating Tower 1 - currently calib Prev. 1/2 Stanford - b/g well understood 120 live days (50 kg-days Ge) Tower not changed -> Soudan Will be some improvement at depth Need stats to study bg (Prelim looks good) Tower 2 All New detectors Some improvements made in b/g handling Not yet measured b/g for this tower Initial SOUDAN Similar run to Stanford: 50 Ge kg-days Looking for Zero background (ZBG) >10 keV Expect very clean analysis Tower 1 Previously 1/2 year Stanford Tower 2 (New dets) CDMS Dark Matter - Aachen EPS - 17 July 2003 Rick Gaitskell 1 per minute in 4 m 2 shield Depth (mwe) Log 10 (Muon Flux) (m -2 s -1 ) Stanford Underground Facility 500 Hz muons in 4 m 2 shield Expected Backgrounds for CDMS II at Soudan On track for events/kg/keV/day at 15 keV? Depth of 2000 mwe reduces neutron background from ~1 / kg / day to ~1 / kg / year Also better neutron shielding CDMS Dark Matter - Aachen EPS - 17 July 2003 Rick Gaitskell 1999 Ge BLIP Ge Ga peak from 71 Ge: decays Expected Backgrounds for CDMS II at Soudan On track for events/kg/keV/day at 15 keV? Depth of 2000 mwe reduces neutron background from ~1 / kg / day to ~1 / kg / year Also better neutron shielding Photon background is already 0.7 events /(kg keV day) x expected leakage, despite the shallow site (good enough with background subtraction) CDMS Dark Matter - Aachen EPS - 17 July 2003 Rick Gaitskell BLIP5 single Z1+Z2+Z3 Ge electrons single Expected Backgrounds for CDMS II at Soudan On track for events/kg/keV/day at 15 keV? Depth of 2000 mwe reduces neutron background from ~1 / kg / day to ~1 / kg / year Also better neutron shielding Photon background is already 0.7 events /(kg keV day) x