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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