Large Scale Searches for Relic Dark Matter Mani Tripathi University of California, Davis January 21, 2010 Aspen Particle Physics Winter 2010 Mani Tripathi, Jan 2010
Direct DM Search - Progress & Breakthroughs Rick Gaitskell XENON 10 Mani Tripathi, Jan 2010 Year
This review focuses on highly scalable technologies using liquid targets. 1. Liquid Xenon Xenon10, Xenon100, Xenon1T, MAX … ZEPLIN-I, ZEPLIN-II, ZEPLIN-III LUX-350, LUX-ZEPLIN @Sanford (LZS) , LZ@DUSEL (LZD) 2. Liquid Argon/Neon Mini-CLEAN, DEAP, CLEAN … WArP DarkSide, MAX 3. Other COUPP, COUPP-60, COUPP-Tonne Scale Mani Tripathi, Jan 2010
Target Comparison -- WIMP Nucleus Elastic Scattering A 2 Recoil Spectra Dependence Higher sensitivity for Xe for Recoil Energy < 20 keV. Favored regime for Ar for Recoil Energy > 40 keV. Mani Tripathi, Jan 2010
Estimate of Target Sensitivities Akerib, Gaitskell et al Assume 100 GeV, Assume natural Ar. 4x10 -45 cm 2 . Target Energy Fiducial Total Max Threshold * Mass number of acceptable / assumed required for ER events leakage in signal 25 WIMP in Fiducial ER acceptance events in Mass for Rejection 100 live- 100 live- days †† days ** Xe TPC 2 keVr / 100 kg 17 0.05 80% 2 x 10 8 5 x 10 -9 Ar (†) 40 keVr / 1.5 tonnes 90% 8 x 10 8 1 x 10 -10 Ar (†) 80 keVr / 6.5 tonnes 90% 2 x 10 5 5 x 10 -6 Ge 10 keVr / 350 kg (CDMS) 50% Mani Tripathi, Jan 2010
Why Noble Liquids? Very powerful Self- shielding. Effective when size > attenuation length => ~20 cm buffer for Xe => Fiducial Mass > 100 kg. Mani Tripathi, Jan 2010
Two Signal Technique PMT Array Time Time Anode e - - e e - e - - e e - e - - e E AG Gas phase ~1 µ s width Secondary Grids E GG - e - e e - - e e e - - (S2) e - - e 0–350 µ s depending - e - e e - - e E GC e - - e on depth e - - e Liquid phase Primary (S1) ~40 ns width Cathode E AG > E GG > E GC Interaction Mani Tripathi, Jan 2010
γ /neutron Discrimination Differences in recombination efficiency is exploited to discriminate between electron and nuclear recoils. XENON 10 Figure of merit derived from plots of: Log (charge escaping recombination/total Mani Tripathi, Jan 2010 primary light produced) … Next slide.
Calibration Data (Prototype Xe Cell at Case Western) 252 Cf Neutrons 133 Ba Electrons Recoil Energy (keVr) Recoil Energy (keVr) These measurements were made above ground, but agree well with Xenon10 experience. Mani Tripathi, Jan 2010
Simulated Signal in LUX 350 Electron recoil background ~2.6x10 -4 dru (based on screening of materials) 300 days acquisition 100 kg fiducial mass Mani Tripathi, Jan 2010
Power of self-shielding XENON10 Data -- 5.4 kg, 59 days LUX Simulation -- 100 kg, 100 days Red points are for a simulated signal of 100 GeV WIMP and a cross section 5x10 -45 cm 2 . Open points are for 25 kg fiducial. Mani Tripathi, Jan 2010
Switch to talk about Argon and COUPP and return to Xenon The CLEAN Program Thanks to Dan McKinsey Mani Tripathi, Jan 2010
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The WArP Program Thanks to Cristiano Galbiati Mani Tripathi, Jan 2010
WArP being installed in its Cryostat 12/18/08 Mani Tripathi, Jan 2010
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DarkSide Program Thanks to Cristiano Galbiati Mani Tripathi, Jan 2010
DarkSide UMass Amherst Arizona State University Augustana College Black Hills State University Fermilab University of Houston University of Notre Dame Princeton University Temple University UCLA
DarkSide-50 •dual-phase TPC •50 kg active mass •5 ph.el/keV ee •23 keV r threshold •background-free for 3 yrs •sensitivity 10 -45 cm 2 First test for three technological advances crucial to achieve zero background: • depleted argon • QUPIDs at LAr temp • active liquid scintillator neutron veto
Princeton Prototype Plant for Industrial Scale Production News: NSF funding (NSF PHY-0811186) Achieved 1.5 kg/day (depletion >25), goal ~few kg/day in 2010
The COUPP Program Thanks to Juan Collar Mani Tripathi, Jan 2010
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COOUPP Approach Insensitive to MIP, γ and β Spin-1/2 19 F provides sensitivity to spin dependent cross section Main background from a-decays A 60 kg detector is built and being commissioned in a test facility To be deployed at SNOLab Mani Tripathi, Jan 2010
Juan Collar HEPAP Presentation Mani Tripathi, Jan 2010
The XENON Program Thanks to Elena Aprile Mani Tripathi, Jan 2010
~50 scientists from 10 institutions: Willhelms Universität Münster University of California Los Angeles Max-Planck-Institut für Kernphysik Rice University Houston Universität Zürich Laboratori Nazionali del Gran Sasso Columbia University New York Universidade de Coimbra Jiao Tong University Shanghai Subatech Nantes Waseda University 31
XENON100: first results by Spring 2010 veto PMT bell 98 PMT top array +5000V 170kg PTFE TPC, liquid xenon field shaping 80 PMT bottom array - 16000V veto PMT Rafael F. Lang (Columbia): Search for Dark Matter with XENON 37
XENON100: operational at LNGS 1400 m Rock (3100 mwe) XENON100
XENON Sensitivity Projections spin-independent interaction: 65
XENON Sensitivity Projections pure spin-dependent neutron coupling: 66
The ZEPLIN Program Thanks to Tim Sumner Mani Tripathi, Jan 2010
International Collaborators UK Collaboration Coimbra, ITEP, Rochester, Texas A&M, Torino, UCLA Edinburgh, ICL, RAL, Sheffield ZEPLIN - I 5kg LXe target (3.1kg fid) 3 PMTs ZEPLIN - III ZEPLIN - II Cu construction 8 kg fiducial target 31kg LXe target (7.5kg fid) Polycold cryogen cooling 31 PMTs 7 PMTs Operated stably for long runs Mani Tripathi, Jan 2010
ZEPLIN - III Mani Tripathi, Jan 2010
Tim Sumner Nov. 2009 Note: XENON10 limit is single- sided and only at 85% confidence! ZEPLIN-III Results with spin-independent limits – Lebedenko et al., arXiv:0812.1150 (2008) Mani Tripathi, Jan 2010
Spin-dependent Results ZEPLIN-III Spin-dependent limits – Lebedenko et al., arXiv:0901.4348 (2009) Mani Tripathi, Jan 2010
ZEPLIN-III future plans • Veto installation (plastic + Gd) - done • PMT upgrade – b/g 1/30 - done • Calibration – about to start • Physics Exploration • Second science run (~10 -8 pb) Mani Tripathi, Jan 2010
The LUX/LZ Program Mani Tripathi, Jan 2010
LUX At Sanford Lab Mani Tripathi, Jan 2010
LUX Goals • 99.3 – 99.9% Electron Recoil background rejection for 50% Neutron Recoil acceptance, in Edelweiss I the range 5 keVr < E < 25 keV WARP ZEPLIN II • γ + β rate < 8 x 10 -4 CDMS II events/kg/keVee/day with 99.4% Edelweiss I CDMS II@Soudan (2008) XENON10 rejection (conservative) SuperCDMS@Soudan (2009) SuperCDMS@SNOLab (2013) • 10 month run w/ 50% NR acceptance (net 15,000 kg-days) LUX (2010) • DM reach σ ~ 4x10 -46 cm 2 (Equivalent to an event rate of ~0.4/100kg/month in 100kg fiducial) Mani Tripathi, Jan 2010 (SuperCDMS Goal @ SNOLab: Gross Ge Mass 25 kg (x 50% fid) for 1000 days running)
• Internal Neutrons ( α ,n) & fission << • Internal Gammas strong self- γ + β . ~65% double scatter. shielding against PMT activity (main source). Double Compton scatters are rejected. External γ + Neutrons shield with veto for cavern n, and HE neutrons from muon. Mani Tripathi, Jan 2010
The LUX detector • 350 kg Dual Phase liquid Xe TPC • 60 PMTs (Hamamatsu R8778) each in top and bottom arrays • ~100 kg achievable in the fiducial volume Active Water Shield Mani Tripathi, Jan 2010 Detector - aspect ratio ~ 1.2
Davis Cavern Mani Tripathi, Jan 2010
De-watering Milestone -- LUX hopes to be underground in Fall 2010. Mani Tripathi, Jan 2010
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Future Program: Scaling Up Mani Tripathi, Jan 2010
LZS LZD Mani Tripathi, Jan 2010
Summary •A diverse and vibrant program in direct search for Dark Matter is around the corner. Complementary to the LHC searches. •The new generation detectors like Xenon100 and LUX will surpass current best limits in <1 week of running. •If WIMP Dark Matter exists x10 below current limits, discovery is within reach in the next year or two. •Design efforts are underway to design even larger detectors for the DUSEL era. If WIMPs are not detected down to 10 -48 cm 2 , there will be serious need for new models for Dark Matter. Mani Tripathi, Jan 2010
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