DirectDirect SearchesSearches forfor DarkDark MatterMatter ParticlesParticles Igor G. Irastorza CEA/Saclay International Meeting on Fundamental Physics 2005 Benasque, March 2005 Summary: n The paradigm of Dark Matter n Candidates for DM: WIMPs and axions n Phenomenology of detection n Direct Searches for WIMPs IMFP2005,n Direct Benasque, Searches March for Axions 2005 Igor G. Irastorza / CEA, Saclay 1 DarkDark MatterMatter atat cosmologicalcosmological scalesscales n Important amount of observational evidence gathered up to now: – Multiple CMB observations – Distant Supernova Ia measurements (universe is accelerating its expansion à Dark energy). – Large Scale Structure (cold dark matter). – Nucleosynthesis, Lyman a forest, … n Last WMAP precision data adds evidence for LCDM cosmological model. IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 2 LLCDMCDM n The Universe is flat: “Dark – W = 1.02 ± 0.02 energy” n Precision Cosmology: (WMAP ~73% combined with others) Baryonic non baryonic < 5% Visible < 1% Dark Matter WMAP, Astrophys.J.Suppl.148:1,2003 ~23 % IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 3 DarkDark MatterMatter Rotation curve of the Milky Way atat galacticgalactic scalesscales n Galactic rotation curves They appear rather flat, evidencing matter beyond Rotation of galaxies the light distribution mesaured by Doppler shift n Gravitational mass of galaxy clusters (oldest evidence; 1933 Zwicky) IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 4 WhatWhat cancan DarkDark MatterMatter be?be? n Baryonic matter? NO – Dust, gas, planets, brown stars,… MACHOS (non visible conventional matter) – Ruled out by primordial Nucleo-synthesis, and the rest of cosmological observations. – Gravitational lensing of MACHOS à not enough n Non baryonic, but standard, matter? NO – Neutrinos would be the only candidate in the SM. Ruled out by cosmological observations (they would constitute Hot Dark Matter) n Non baryonic, beyond standard? most probable IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 5 CandidatesCandidates toto DarkDark MatterMatter n Two main candidates attract most of the present activity in the field: WIMPS n Like the LSP of supersymmetric theories Neutral (usually the neutralino). Heavy n WIMP stands for Weakly Interacting Massive Fermion Particle (generic name). n Axions appear as Nambu-Goldstone bosons in the PQ spontaneous symmetry breaking. AXIONS n More generically, we speak about axion-like Neutral particles, to refer to fundamental Very light (pseudo)scalars of similar properties without (pseudo)scalar referring to a specific theory model. IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 6 Dark Matter WIMPs detection In order to do predictions of expected WIMP WIMP fluxes/signals one has to make galactic halo working hypothesis about how WIMPs are clustered in the galactic halo Standard (=simpler) halo model Sphericity rW Isotropy Non-rotation WIMP and Thermalization phenomenology Non-Standard Mass f(v) Relaxing one or more of WIMP-nucleon at Earth the above assumptions cross section to some degree SD/SI coupling? Must explain rotation curve of Milky Way WIMP “wind” WIMPWIMP detectiondetection 232 kmEffect/s looked for at laboratory: Elastic dispersion of WIMPs with nuclei of detector WIMP nuclear recoil WIMP WIMPWIMP detectiondetection n Expected signal: nuclear rare low energy event recoil 0.5 Standard halo model 0.45 60 GeV 10-8 nbarn Specific challenges: 0.4 day Germanium / 0.35 semiconductor detector üLow threshold (~keV) kg / 0.3 üReasonable resolution 0.25 keV / 0.2 üVery low background at keV 0.15 scale: counts 0.1 0.05 üRadiopurity & rejection 0 techniques 0 5 10 15 20 25 30 üAim for large detector masses Visible energy (keV) üGreat stability over time. IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 9 WIMPWIMP detectiondetection WIMP nuclear recoil + + - + - - + + - - - + light charge heat IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 10 WIMPWIMP detection:detection: present efforts & projects EDELWEISS CUORICINO @Modane @GranSasso CDMS GENIUS @Soudan H/M @GranSasso CUORE @GranSasso @GranSasso ROSEBUD-I HEAT+ GEDEON @Canfranc IGEX-DM @Canfranc CHARGE CHARGE PICASSO @Canfranc @SNO CRESST-I MIMAC-He3 SIMPLE @GranSasso DRIFT @Grenoble HEAT @Rustrel @Boulby NEWAGE ORPHEUS @Kyoto @Bern HEAT+ LIGHT X-MASS @Kamioka XENON LIGHT+ CHARGE ZEPLIN-II @US CRESST-II @Boulby @GranSasso ROSEBUD-II WARP @Canfranc LIGHT ZEPLIN-I @GranSasso DAMA-NaI @Boulby @GranSasso ANAIS @Canfranc KIMS LIBRA DAMA-Xe NAIAD@YangYang @GranSasso @Boulby @GranSasso ELEGANTS @Oto IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 11 WIMPWIMP identificationidentification abilityability n WIMP spectrum is quite “feature-less”. Cannot evidence a WIMP signal (unless extremely above the expected background) n Most of present set-ups can only “reject” WIMPs, but not identify them. n Few kinds of positive signatures: – Annual modulation: BIG CHALLENGE. At reach (DAMA,…ANAIS, CUORICINO, CUORE, GENIUS, GEDEON,…) – Directional signal. VERY BIG CHALLENGE. Good progress (DRIFT, NEWAGE). Maybe at reach soon. – Target material dependence. VERY BIG CHALLENGE. Good progress (ROSEBUD-II, CRESST-II). Maybe at reach soon. – Diurnal variation. Some attempts in the past (COSME, SIERRA GRANDE). Very large statistics needed. IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 12 AnnualAnnual modulationmodulation signalsignal 232 km/s 0.5 Standard halo model 0.45 60 GeV 0.4 10-8 nbarn 0.35 Germanium day semiconductor detector / 0.3 kg / 0.25 keV 0.2 / 0.15 counts 0.1 0.05 0 0 5 10 15 20 25 30 Energy (keV) DAMADAMA--NaINaI n 100 kg of ultrapure NaI(Tl) operating for about 7 years at Gran Sasso n Looking for annual modulation of the data n 107731 kg day statistics gathered n Experiment out of operation in July 2002 to start work in LIBRA. IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 14 DAMADAMA positivepositive resultresult n Modulation detected along nNo systematic effect found that 7 years. can mimic that signal nModulation absent above 6 keV n 6.3s statistical significance. IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 15 DAMA Positive result: WIMP interpretation n Is the DAMA positive signal already excluded by other experiments? ßpolemic point… n Modification of the region for non-standard set of assumptions… IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 16 OtherOther NaINaI experimentsexperiments that could refute/corroborate DAMA result n ANAIS in Canfranc: – First prototype successfully n LIBRA in DAMA: 250 kg just operated starting in Gran Sasso – 100 kg available, being instrumented IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 17 IonizationIonization detectors:detectors: IGEXIGEX--DMDM n Still the best raw (no discrimination) background achieved: 0.2 c/keV/kg/day between 4-10 keV Best radiopurity & shielding conditions IMFP2005, Benasque, March CANFRANC 2005 Igor G. Irastorza / CEA, Saclay 18 IonizationIonization detectors:detectors: IGEXIGEX--DMDM IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 19 FutureFuture largelarge ionizationionization detectorsdetectors GEDEON GENIUS IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 20 HeatHeat ++ charge:charge: CDMSCDMS n Nuclear recoils events ionize less that electron n Events from gamma recoils of same energy calibration (~25% for Ge) n They can be efficiently distinguished by comparing heat and n Events from charge signals down to a neutron calibration threshold of ~10 keV n Most powerful technique to reject WIMPs up to now. IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 21 CDMSCDMS n19.4 kg-d of Ge net exposure recently released (PRL 93 (04)) n Moved underground (Soudan) in 2003. n O events surviving cuts (10-100 keV), – while less than one of background expected (0.7 misidentified electrons and 0.07 neutrons) EDELWEISSEDELWEISS n 3 x 320 g Ge bolometers in operation underground in Modane. n Last result (2003) released additional 45 kg·d (total 62 kg·d). n 40 nuclear events observed, above a threshold of ~15 keV. n Perspectives: multiply x10 the target mass (EDELWEISS-II) • Plots from the 1st run (2002) IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 23 n Both CDMS and EDELWEISS are working to increase their detector mass IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 24 Xe+ Ionisation +Xe Electron/nuclear recoil + Xe2 Excitation XenonXenon detectorsdetectors +e- (recombination) n ZEPLIN-I (at Boulby) measures Xe* Xe** + Xe only scintillation. Statistical +Xe discrimination of the nuclear Xe * 175nm 2 175nm recoils by pulse decay time. Triplet Singlet recoils by pulse decay time. 27ns 3ns n 293 kg´days of data 2Xe 2Xe n Moving to ZEPLIN-II which will measure both scintillation and charge. IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 25 FutureFuture XenonXenon experimentsexperiments ZEPLIN-II (30 kg) X-MASS (3 kg à 1 ton) ZEPLIN-III-IV (1 ton) XENON-10-100-1T IMFP2005, Benasque, March 2005 Igor G. Irastorza / CEA, Saclay 26 FutureFuture ofof WIMPWIMP detectiondetection n Build larger detectors and reduce backgrounds: CUORE, GENIUS, GEDEON,… à better exclusion plot & annual modulation signature n Pursue new ideas to achieve this: MacHe3, ORPHEUS, PICASSO, SIMPLE, spherical TPC(?) n Exploit new positive signatures: – Directional detectors: DRIFT, NEWAGE – Several material in same set-up: ROSEBUD-II, CRESST-II IMFP2005,