searches for dark matter
DESCRIPTION
A. Bashir, U. Cotti, C. de Leon, A. Raya, V. Villanueva and L. Villaseñor IFM-UMSNH XI Workshop on Particles & Fields DPyC-SMF Tuxtla Gutierrez, Chiapas 8-13 November, 2007. Searches for Dark Matter. Outline. Evidences for Dark Matter DM Candidates Direct & indirect detection - PowerPoint PPT PresentationTRANSCRIPT
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Searches for Dark Matter
A. Bashir, U. Cotti, C. de Leon, A. Raya, V. Villanueva and L. Villaseñor
IFM-UMSNH
XI Workshop on Particles & Fields DPyC-SMFTuxtla Gutierrez, Chiapas
8-13 November, 2007
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Outline
Evidences for Dark Matter DM Candidates Direct & indirect detection Running & future experiments Conclusion
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A Mexicangroup submitted a proposal to study DM in anunderground labto Conacyt in2007
R&D money willpossibly be granted in2008
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Evidence for Dark Matter
Fritz Zwicky (1933) measured thevelocities of the individual galaxies. He concluded that“dark” matter is required to hold the cluster
Coma cluster, 350 M ly
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Evidence for Dark Matter Flat Rotation curves
of Galaxies. V. Rubin and W.K. Ford (1970) “What you see is not what you get.”
Modified Newtonian Dynamics (Moglim 1983)
Modified Gravity such as Scalar tensor vector gravity theory (Moffat 2006)
Alternative Explanations
• vc ~ r 1/2
Local density : 0.3 GeV/cm3
6M. Persic et al. 1996
Measured over and over
Each plot contains 50-100galaxiesaccording to luminosity
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Widths of curves indicate 95% CL for the abundance predictions
Measurements are shown as boxes.
Non baryon dark mass is required!
D. Tytler, J. M. O’Meara, N. Suzuki, and D. Lubin, astro-ph/0001318
BB Nucleogenesis: Determines the present baryon mass density to only ~ 4% of critical density
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Evidence for Dark Matter
Bullet Cluster(Clowe et al., 2006)
two collidingClusters of Galaxies at a distance of about 3.4 billion light years
White – VisibleRed – X RaysBlue - Grav. Lensing
evidence against Modified Newtonian
Dynamics (MOND)
NASA RELEASE 06-297: "These observations provide the strongest evidence yet that most of the matter in the universe is dark"
White – Visible
Blue - Grav. Lensing
Red – X Rays
White – VisibleRed – X RaysBlue - Grav. Lensing
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Evidence for Dark Matter Lambda-Cold Dark Matter (concordance) model explains cosmic microwave background observations (WMAP), as well as large scale structure observations (Sloan Digital Sky Survey) and supernovae Ia data of the accelerating expansion of the universe.
The Composition of the Universe
14(Spergel et al. 2006)
ΛCDM MODEL
Particle Candidate for Cold Dark Matter: WIMP Weakly Interacting Massive Particle
Stable, TeV scale, electrically neutral, only weakly interacting
No such candidate in the Standard Model Good candidate: neutralino, Lightest
Supersymmetric Particle (LSP) in SUSY with m ~ 10 GeV to 10 TeV
Linear combination of the zino, the photino and the neutral higgsinos
May be produced at the LHC
Particle Candidate for Dark Matter
But there are many other possibilities (techni-baryons, gravitino, axino, invisible axion, WIMPZILLAS( Godzilla-sized version of WIMPS, ruled out by Auger data), etc)
WIMP Dark Matter Produced in early
Universe They are in thermally
equilibrium at high temperature
Decouple when expansion rate ~ interaction rate
Density left-over from annihilation depends on cross section
E.W. Kolb and M.S. Turner, The Early Universe
X=m/Temperature (time )
Com
ovin
g nu
mbe
r de
nsity
Nequillibrium
Increasing<Av>
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WIMP DETECTION
Direct Detection of halo particles in terrestrial detectors CDMS-II, ZEPLIN Edelweiss, DAMA, GENIUS, etc
f
f
Scattering
(direct) Detection method Since they are neutral and stable, what we
can expect is only a collision with ordinary matter.
Electron recoil does not give enough energy but nuclear recoil gives ~100keV if mDM~O(100GeV).
Dark Matterparticles
Energy deposit
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WIMP DETECTION
f
fAnnihilation
Indirect DetectionSuperK, AMANDA,
ICECUBE, GLAST
p
e+
_
•Search for neutrinos, gamma rays, radio waves, antiprotons, positrons in earth- or space-based experiments Direct and indirect
methods are complementary techniques along with a possible discovery at the LHC
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WIMP signatures (Direct Det) Nuclear recoils
Neutrons (produce similar recoils with sigma 1020 higher, 108-9 background reduction needed
Recoil spectrum shape
Exponential (as most bkg) Shape for backgrounds : electron/nuclear recoils
Absence of multiple scattering (against neutron) Uniform rate throughout volume (against surface
radioactivity) Directionality of nuclear recoils Annual rate modulation
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WIMP signatures (Direct Det)
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Current direct detection experiments
running 3 to 10 kg Liquid XeLight+ IonizationSurface to GS
XENON
running6 kg Liquid XeLight+ IonizationBoulby mineZEPLIN II
running20 g FreonBubble chamberSNOPICASSO
stopped0.262 kg Al2O3Heat + LightGran SassoCRESST-I
running50 g Al2O3 + 67 g Ge + 54 g CaWO4
Heat + LightCanfrancROSEBUD
stopped 46 kg NaILightBoulby mineNaIAD
running2 to 7 kg Ge + 0.4 to 1.4 Kg Si
Heat + IonizationSoudan mine
CDMS-II
running0.6 to 9.9 kg CaWO4Heat + LightGran SassoCRESST-II
running ???10 to 40 kg Ge in N2IonizationGran SassoGENIUS-TF
running41 kg TeO2HeatGran SassoCUORICINO
In istallation10 to 30 kg GeHeat + IonizationModaneEDELWEISS-II
stopped1 kg GeHeat + IonizationModaneEDELWEISS-I
stopped 1 Kg Ge + 0.2 Kg SiHeat + IonizationStanfordCDMS-I
stopped4 kg Liquid XeLightBoulby mineZEPLIN-I
running250 kg NaILightGran SassoLIBRA
stopped100 kg NaILightGran SassoDAMA
stopped2 kg Ge DiodesIonizationCanfrancIGEX
stopped0.2 kg Ge diodesIonizationGran SassoHDMS
StatusMaterialTechniqueLocationNameDiscrimination
Even
t-by
-ev
ent
Stat
istic
al
Non
e
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B. SadouletKEKTC6
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90% C.L. exclusion limits on WIMP-nucleon scattering cross-section (spin-independent)
CDMS (2006)
CDMS IISpin independent90% Exclusionlimits
mSUGRAsplit-SUSY
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Based in Gran Sasso lab (3500 mwe)
100 kg of NaI(Tl) Exposure : 107731 kg.d Coincidence between 2 PMTs Pulse shape rejection inefficient
at 2 keVee
NaINaINaINaI
PM
T
PM
T
NaI scintillation : DAMA
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NaI scintillation : DAMA
Used annual modulation Claim annual modulation at
6.3σ over 7 annual cycles Mχ ~ 52 GeV/c² σn ~ 7.2 10-6 pb
Not compatible with other experiments (CDMS, ZEPLIN, EDELWEISS)
Future = LIBRA (250 kg of NaI)
Single-hits events residual ratesDM density ~0.3GeV/cc100GeV WIMPs 1 WIMP / 7cm cubic, =105/cm2/sec
Depth of 2000 mwe reduces neutron background from~1 / kg / day to ~1 / kg / year
1 per minute in 4 m2 shield
Depth (mwe)
Log
10(M
uon F
lux)
(m-2s-
1)
Stanford UndergroundFacility
500 Hz muons in 4 m2 shield
CDMS II at Soudan
Experimental apparatus
DilutionRefrigerator
Cold stem toIcebox
Electronics stem from Icebox
Icebox can take 7 towers with 6 ZIP detectors each
Muon-veto paddles encasing outer lead and polyethylene shielding
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Heat-ionization: CDMS-II 4x250g Ge +
2x100g Si Net exposure: 19.4
kg.d Detector = ZIP
(sensitive to athermal phonon)
Active muon veto + shielding (PE + Pb)
ZIP 1 (Ge)ZIP 2 (Ge)ZIP 3 (Ge)ZIP 4 (Si)ZIP 5 (Ge)ZIP 6 (Si)
SQUID cards
FET cards
4 K
0.6 K0.06 K
0.02 K
•Identical Icebox as CDMS I, but fits seven towers.• Each tower (T1-7) contains three Ge and three Si ZIP detectors interlaced.Total mass of Ge = 7 x 3 x 0.25 kg > 5 kgTotal mass of Si = 7 x 3 x 0.10 kg > 2 kg
CDMS II Detector Deployment
T1
T7 T6
T5
T4T3
T2
(Extra polyethylene shield in SUF icebox onlyallows 3 towers to be run at SUF simultaneously.)
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Heat-ionization: CDMS-II Rejection of background surface events with
timing cuts
•CDMS I (1995-1999)Results for scalar-interacting (~A2) WIMPs probed are best
upper limits of any experiment for the mass range 10 to 35 GeV.
CDMS data are incompatible with DAMA signal at high confidence.
Sensitivity limited by external neutron background from muons interacting in surrounding rock.
•CDMS II (1999-2005) Construction underway at deep site: Soudan, Minnesota.First tower of 6 detectors ready for Soudan - they exceed
performance expectations - “First Dark” January 2003.Reduction of neutron background by factor of 2.3 due to
installation of internal moderator in agreement with Monte Carlo predictions.
More work required on surface-beta rejection/identification/subtraction in order to fully utilize deep site?
Neutrinos from the Earth (& Sun – but Sun more difficult for AMANDA IceCUBE)
IceCube
AMANDA’s BIG BROTHER: 1 km3 of Ice 4200 PMTs on 70 Strings 1450-2450 m ~10 Angular Resolution to Mu Neutrinos IceTop Air Shower Array to
Veto Downgoing Muons• Digitized/Time-Stamped at
Each PMT • Started Deploying 2005;• Construction Finished ~2011
Kathy Turner, 24May2006 37
Gamma-ray Large Area Space Telescope GLAST Large Area Telescope (LAT)
GLAST will have a very broad science menu that includes:• Systems with supermassive black holes (Active Galactic Nuclei)• Gamma-ray bursts (GRBs)• Pulsars• Solar physics• Origin of Cosmic Rays• Probing the era of galaxy formation, optical-UV background light• Solving the mystery of the high-energy unidentified sources• Discovery! Particle Dark Matter? Other relics from the Big Bang? Extra dimensions? Testing Lorentz invariance. New source classes.
GLAST will search for WIMP annihilation gamma rays from galactic center, galactic halo, galactic satellites and extragalactic
To be launched in late 2007, will survey the gamma-ray sky in the energy range of 20MeV-300 GeV.
• The existence of Nonbaryonic Dark Datter has been definitely established
• CDM is favoured• Supersymmetric particles (in particular,
neutralinos) are still among the best-motivated candidates
• New direct and indirect detection experiments will reach deep into theory parameter space
• The various indirect and direct detection methods are complementary to each other and to LHC
• The hunt is going on – many new experiments coming!
• The dark matter problem may be near its (s)solution…
Conclusion