The Direct Search for Dark Matter with special emphasis on the XENON project Rafael F. Lang Tuchan Purdue University [email protected] IPMU Tokyo, March 8, 2013 picture: Thomas 1 Dark Matter Exists… baryon baryon fraction BBN D BBN 3He SDSS5 WMAP5 matter density …but what is it made of? Rafael F. Lang, Purdue: The Direct Search for Dark Matter 2 The Direct Search for Dark Matter • thermal relic hunting basics • discrimination techniques • DAMA/LIBRA • CoGeNT • CDMS-II and EDELWEISS • XENON100 and XENON1T Rafael F. Lang, Purdue: The Direct Search for Dark Matter 3 Search for The Invisible not impossible — a historical perspective: 1844: F. Bessel predicts companion of Sirius discovered by A. Clark in 1862 1845: J. Adams, U. Leverrier predict 8th planet discovered by J. Galle 1846 1930: W. Pauli predicts neutrino discovered by C. L. Cowan and F. Reines in 1956 and the discovery of ether, the black hole at the center of the Milky Way, ... But: Need an idea first! Rafael F. Lang, Purdue: The Direct Search for Dark Matter 4 Idea: It’s a Thermal Relic Particle from cosmology: nrelic robust scattering prediction: rate nequilibrium 2 Temperature / kbT/mc Time Rafael F. Lang, Purdue: The Direct Search for Dark Matter 5 How to Search a Thermal Relic • Production Collider Searches • Annihilation Indirect Searches Rafael F. Lang, Purdue: The Direct Search for Dark Matter 6 How to Search a Thermal Relic • Production Collider Searches • Annihilation Indirect Searches • Scattering Direct Searches Rafael F. Lang, Purdue: The Direct Search for Dark Matter 7 new would this is where we expect theusual in Expectations RafaelF. Lang, Purdue:The Direct SearchMatter for Dark physics (MSSM to show up etc.) s - m - Space Buchmueller et al. arXiv:1102.4585 8 Kadastik et al. PRL 104 201301 (2010) Roszkowski et al. JHEP07 075 (2007) Baltz&Gondolo PRD 67 063503 (2003) Direct Scattering Theory On One Slide • Rate large detector, long exposure (or ) • Coherent Scattering heavy target material • Maximum Recoil Energy low energy detector • Spectrum shielding, discrimination, multi target Rafael F. Lang, Purdue: The Direct Search for Dark Matter 9 Expected WIMP Spectrum • isothermal halo • local density • • coherent scattering • Helm form factor m = 1000 GeV m = 100 GeV m = 10 GeV / ) pb xenon kg d on dE keV ( / dN challenging signal! Recoil Energy / keV Rafael F. Lang, Purdue: The Direct Search for Dark Matter 10 Annual Modulation December 60° Galactic plane expect modulation of • rate June • spectral shape at the percent level Rafael F. Lang, Purdue: The Direct Search for Dark Matter 11 The Direct Search for Dark Matter • thermal relic hunting basics falling exponential, annual modulation • discrimination techniques • DAMA/LIBRA • CoGeNT • CDMS-II and EDELWEISS • XENON100 and XENON1T Rafael F. Lang, Purdue: The Direct Search for Dark Matter 12 The Power of Discrimination e-/g: electronic recoil a/n/WIMPs: nuclear recoil electronic recoils • are most common background • scintillate and ionize more (for given energy) → discriminate between the two e.g. measure both energy and some additional parameter (ionization yield, scintillation yield, ratio ionization/ scintillation, pulse decay times, acoustic signal) Rafael F. Lang, Purdue: The Direct Search for Dark Matter 13 Particle Detection Channels DarkSide ZEPLIN-III XENON100 XENON1T Direction XENON10 LUX ZEPLIN-II WIMP WARP DRIFT-II NEWAGE DM-TPC DEAP-I DEAP-3600 miniCLEAN XMASS IGEX Scintillation Ionization CoGeNT DAMA/LIBRA TEXONO XENON10 (S2) KIMS ANAIS XENON100 (S2) DM-ICE Target CDMS CRESST-II SuperCDMS ROSEBUD EDELWEISS Bubble Axion Nucleation Cavities Phonons COUPP PICASSO ADMX CRESST-I SIMPLE Rafael F. Lang, Purdue: The Direct Search for Dark Matter 14 Particle Detection Channels XENON100 XENON1T LUX Scintillation Ionization CoGeNT DAMA/LIBRA Target CDMS EDELWEISS Phonons Rafael F. Lang, Purdue: The Direct Search for Dark Matter 15 The Direct Search for Dark Matter • thermal relic hunting basics falling exponential, annual modulation • discrimination techniques various ways to reduce backgrounds • DAMA/LIBRA • CoGeNT • CDMS-II and EDELWEISS • XENON100 and XENON1T Rafael F. Lang, Purdue: The Direct Search for Dark Matter 16 DAMA/LIBRA Italy/China: 230kg ultra-pure NaI(Tl) scintillators by far largest and longest exposure but no discrimination Rafael F. Lang, Purdue: The Direct Search for Dark Matter 17 DAMA/LIBRA Data noise flat background 40K→40mAr (beta, Compton) arXiv:0804.2741 arXiv:1210.7548 Energy / keV fully explained by background, no space for signal, but: (2-4)keVee data from arXiv:0804.2741 and data from arXiv:0804.2741 arXiv:1002.1028 Rafael F. Lang, Purdue: The Direct Search for Dark Matter 18 Muon Flux at Gran Sasso DAMA: May 26 ± 7d ICARUS n LVD m: July 15 ± 15d DAMA and LVD μ phase show striking similarity (amplitude!) but not consistent phase arXiv:1111.4222 Rafael F. Lang, Purdue: The Direct Search for Dark Matter 19 The Direct Search for Dark Matter • thermal relic hunting basics falling exponential, annual modulation • discrimination techniques various ways to reduce backgrounds • DAMA/LIBRA modulation of unknown origin • CoGeNT • CDMS-II and EDELWEISS • XENON100 and XENON1T Rafael F. Lang, Purdue: The Direct Search for Dark Matter 20 CoGeNT Performance USA 440g P-type point-contact Ge detector conventional coaxial HPGe P-type point- contact HPGe threshold 400eV Collar, Collar, UC Davis and other talks, 2010 Rafael F. Lang, Purdue: The Direct Search for Dark Matter 21 CoGeNT Data noise pedestalnoise arXiv:1002.4703 arXiv:1106.0650 ~3s modulation after 15months. Background rejection? expected phase fit Rafael F. Lang, Purdue: The Direct Search for Dark Matter 22 CoGeNT With Background J. Collar, Marina Reydel2012 cutting at constant acceptance lower limit shifts down by >10s ! Still different from zero? arxiv:1002.4703 Rafael F. Lang, Purdue: The Direct Search for Dark Matter 23 The Direct Search for Dark Matter • thermal relic hunting basics falling exponential, annual modulation • discrimination techniques various ways to reduce backgrounds • DAMA/LIBRA modulation of unknown origin • CoGeNT signal slip-sliding away • CDMS-II and EDELWEISS • XENON100 and XENON1T Rafael F. Lang, Purdue: The Direct Search for Dark Matter 24 CDMS-II USA/Canada/Switzerland located at Soudan 19 Ge and 11 Si “ZIP” detectors with phonon (TES) and ionization signal data-taking finished , IDM2010 final analysis of 2 years data from 14 250g Ge detectors Armengaud next step: SuperCDMS with bigger and interleaved detectors Rafael F. Lang, Purdue: The Direct Search for Dark Matter 25 CDMS-II Results Ge dark matter search data two detectors with signal candidate events combined: bulk electronic recoils surface events bulk nuclear recoils two events observed, consistent with (revised) background expectation of 0.9 ± 0.2 events. arXiv:0912.3592 and arXiv:0912.3592 Saab, IDM2010 Rafael F. Lang, Purdue: The Direct Search for Dark Matter 26 EDELWEISS-II (~ SuperCDMS) France, Germany, Russia, UK in the Frejus Lab germanium crystals with phonon/ionization readout NTD phonon sensors interleaved electrodes (ionization) phonon collect veto sensor 1.5V 1.5V +4V +4V - - Ge crystal fiducial volume +1.5V +1.5V - - 4V 4V collect veto Rafael F. Lang, Purdue: The Direct Search for Dark Matter 27 EDELWEISS-II Data data from 1 year with ten 400g Ge crystals meanwhile four 800g modules installed with 210Pb b-source at LSM preliminary ionization/phonon yield , IDM2010 energy (phonon channel) beforeafter fiducialization 3 events near threshold Kraus, IDM2010 Armengaud Rafael F. Lang, Purdue: The Direct Search for Dark Matter 28 CDMS Limits DAMA CoGeNT CRESST CDMS CDMS strong limit arXiv:0912.3592 dedicated analysis constrains CoGeNT interpretation arXiv:1011.2482 Rafael F. Lang, Purdue: The Direct Search for Dark Matter 29 EDELWEISS Limit DAMA CoGeNT IDM2010 CRESST CDMS CDMS EDELWEISS Armengaud interleaved detectors ready for the next step in sensitivity Rafael F. Lang, Purdue: The Direct Search for Dark Matter 30 The Direct Search for Dark Matter • thermal relic hunting basics falling exponential, annual modulation • discrimination techniques various ways to reduce backgrounds • DAMA/LIBRA modulation of unknown origin • CoGeNT signal slip-sliding away • CDMS-II and EDELWEISS cleanest solid-state technology • XENON100 and XENON1T Rafael F. Lang, Purdue: The Direct Search for Dark Matter 31 Gran Sasso Underground Lab Gran Sasso mountain range cable car to ski resort hiking path lab tunnel Assergi highway Rafael F. Lang, Purdue: The Direct Search for Dark Matter 32 Dual-Phase Xenon TPC top 3D position information PMT array S2 hit pattern: (position) drift time: anode + gas xenon liquid xenon e- e- e- hn cathode - hn bottom PMT array S1 drift time S2 (S1, S2) Rafael F. Lang, Purdue: The Direct Search for Dark Matter 33 XENON100 98 PMT top array 80 PMT bottom array Rafael F. Lang, Purdue: The Direct Search for Dark Matter 34 XENON100 veto PMT bell 98 PMT top array +4500V PTFE TPC, 161kg field shaping liquid xenon 80 PMT bottom array -16000V veto PMT Rafael F. Lang, Purdue: The Direct Search for Dark Matter 35 XENON100 Shield 20cm H2O, 15cm Pb, 5cm French Pb, 20cm PE, 5cm Cu Rafael F. Lang, Purdue: The Direct Search for Dark Matter 36 Background Spectrum Understood low-energy background before discrimination events/keVee/kg/day 2 orders of magnitude below other Dark Matter searches Rafael F. Lang, Purdue: The Direct Search for Dark Matter 37 Absolute (!) Rate Matching XENON100 AmBe calibration: understanding at %-level in preparation Rafael F. Lang, Purdue: The Direct Search for Dark Matter 38 The Power of Fiducialization events after 225 live days of data taking 2011/2012: (trigger rate ~1Hz) radius / cm z / cm z / 34kg fiducial arXiv:1207.5988 2 2 Rafael F. Lang, Purdue: The Direct Search for Dark Matter radius / cm 39 Discrimination using S2/S1 60Co, 232Th and 241AmBe calibration S1 / PE electronic recoils (background) ER mean – /S1) b nuclear recoils (S2 10 (calibration) log energy / keVnr ~99.5% ER rejection @ 50% NR acceptance Rafael F.