Dark Matter: Looking for WIMPs in the Galactic Halo Dan Akerib Case Western Reserve University CDMS Collaboratio n PANIC 27 October 2005
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 1/44
Dark Matter: Looking for WIMPs inthe Galactic Halo
Dan AkeribCase Western Reserve University
CDMS Collaboration
PANIC27 October 2005
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 2/44
Standard Cosmology
WMAP
WMAP
Colley, Turner & Tyson from Perlmutter, Phys. Today
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 3/44
Non-Baryonic Dark Matter
• Matter density ΩMatter = 0.30 ± 0.04
• Big Bang Nucleosynthesis ΩBaryons = 0.05 ± 0.005
• Nature of dark matter
Non-baryonic Large scale structure predicts
DM is ‘cold’
• WIMPs – Weakly InteractingMassive Particle ~10–1000 GeV Thermal relics
TFO ~ m/20 σA∼ electroweak scale
SUSY/LSP
Production = Annihilation (T≥mχ)
Production suppressed (T<mχ)
Freeze out: H > ΓA~ nχ 〈σA v 〉
1 10 100 1000
mχ / T (time)
C o m o v i n g N u m b e r D e n
s i t y
~exp(-m/T)
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 4/44
WIMPs in the Galactic Halo
WIMPs – the source of Mass in the Rotation
Curves?
halo
bulge
disksun
The Milky Way
WIMPdetector
energy transferred appears in‘wake’ of recoiling nucleus
WIMP-Nucleus Scattering
Erecoil
L o g ( r a t e )
Scatter from a Nucleus in a TerrestrialParticle Detector
〈E〉~ 30 keV
Γ < 1/kg/day
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 5/44
SUSY Dark Matter: elastic scattering cross section
• The ‘standard’ progress plot in our
business Sample SUSY parameter space
Apply accelerator and other particle physics constraints
Bound on relic density, eg, WMAP
→ Extract WIMP-nucleon cross-
section (~event rate) versus WIMPmass
Experimental bounds &unconstrained models
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 6/44
SUSY Dark Matter: elastic scattering cross section
• The ‘standard’ progress plot in our
business Sample SUSY parameter space
Apply accelerator and other particle physics constraints
Bound on relic density, eg, WMAP
→ Extract WIMP-nucleon cross-
section (~event rate) versus WIMPmass
Constrained by theory
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 7/44
SUSY Dark Matter: elastic scattering cross section
• The ‘standard’ progress plot in our
business Sample SUSY parameter space
Apply accelerator and other particle physics constraints
Bound on relic density, eg, WMAP
→ Extract WIMP-nucleon cross-
section (~event rate) versus WIMPmass
Constrained modelsConstrained by theory
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 8/44
SUSY Dark Matter: elastic scattering cross section
• The ‘standard’ progress plot in our
business Sample SUSY parameter space
Apply accelerator and other particle physics constraints
Bound on relic density, eg, WMAP
→ Extract WIMP-nucleon cross-
section (~event rate) versus WIMPmass
Constrained modelsTheoretical benchmarks
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 9/44
SUSY Dark Matter: elastic scattering cross section
• The ‘standard’ progress plot in our
business Sample SUSY parameter space
Apply accelerator and other particle physics constraints
Bound on relic density, eg, WMAP
→ Extract WIMP-nucleon cross-
section (~event rate) versus WIMPmass
Constrained by theory
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 10/44
SUSY Dark Matter: elastic scattering cross section
• The ‘standard’ progress plot in our
business Sample SUSY parameter space
Apply accelerator and other particle physics constraints
Bound on relic density, eg, WMAP
→ Extract WIMP-nucleon cross-
section (~event rate) versus WIMPmass
Muon g-2 from SUSY?
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 11/44
SUSY Dark Matter: elastic scattering cross section
• The ‘standard’ progress plot in our
business Sample SUSY parameter space
Apply accelerator and other particle physics constraints
Bound on relic density, eg, WMAP
→ Extract WIMP-nucleon cross-
section (~event rate) versus WIMPmass
Muon g-2 from SUSY?
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 12/44
Direct Detection and Accelerators
L H C
o n l y
I L C ( 5
0 0 ) o n l y
2 5 k g S C
D M S
Direct Detection
only
Excluded by Direct Detection
E x c l u
d e d b y A c c e l e r a t o r s Overlap
• Broad mass range of DirectDetection LHC has 2 Tev limit for gluino,
squark, slepton: neutralinosonly up to 300 GeV in mostSUSY models
Direct Detection may indicate a
mass too large for LHC andprovide clues for ILC
• Accelerators reach down tolower elastic cross section
Potential guidance for directdetection searches
• Rich physics in overlap regionof LHC and 10–100 kg DM expt Exciting opportunity to establish
concordant model
http://dmtools.brown.edu/gaitskell&mandic
C D M S - I I
L i m i t
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 13/44
WIMPs and SUSY
• LHC/ILC constraints
compared with direct DMsearches by Linear Collider Cosmologyworking group Specify a benchmark model,
eg, here LCC1 is mSugra‘bulk region,’ consistentwith WMAP relic density
Explore range of all modelscompatible with accelerator
data Constrain secondary
parameters, eg, neutralinomixing angles and elasticcross section
elastic cross section
ILC+LHC-500
LHC
ILC+LHC-1000
MW from LHC
LCC1
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 14/44
How do we makemeasurements?
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 15/44
What nature has to offer
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 16/44
What you hope for!
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 17/44
Getting rid of the ‘haystack’: Recoil Discrimination
• Measure division of depositedenergy into multiple channels ionization
heat
athermal phonons timing
scintillation timing
• Exploit differential response
• Also, background immunity from directional
threshold
Energy (Ch. 1)
B a c k g r o u
n d
S i g n a l
E n e r g y ( C h .
2 )
WIMPs ‘look’ different – recoil discrimination
Photons and electrons scatter from electrons
WIMPs (and neutrons) scatter from nuclei
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 18/44
Getting rid of the ‘haystack’: Recoil Discrimination
Ephonons Erecoil
E c h a
r g e
C h a r g e
Y i e l d
B a c k g r o u
n d Background
Signal S i g n a
l
WIMPs ‘look’ different – recoil discrimination
Photons and electrons scatter from electrons
WIMPs (and neutrons) scatter from nuclei
In CDMS:
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 19/44
Getting rid of the ‘haystack’: Recoil Discrimination
Ethermal Erecoil
E c h a
r g e
C h a r g e
Y i e l d
B a c k g r o u
n d Background
Signal S i g n a
l
Gammas
Neutrons
WIMPs ‘look’ different – recoil discrimination
Photons and electrons scatter from electrons
WIMPs (and neutrons) scatter from nuclei
In CDMS:
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 20/44
Getting rid of the ‘haystack’: Recoil Discrimination
Ethermal Erecoil
E c h a
r g e
C h a r g e
Y i e l d
B a
c k g r o u
n d Background
Signal S i g n a
l
Gammas
>50000:1 rejection
WIMPs ‘look’ different – recoil discrimination Photons and electrons scatter from electrons
WIMPs (and neutrons) scatter from nuclei
In CDMS:
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 21/44
CDMS: Cryogenic “ZIP” detectors
RTES
(Ω)
4
3
2
1
T (mK)T c ~ 80mK
~ 10mK
Superconducting films that
detect minute amounts of heat
Transition Edge Sensor sensitive tofast athermal phonons
Ionization measurement
1 μm tungstenaluminum fins
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 22/44
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 23/44
Betas: a low-yield background source
• Low-energy electrons (tagged •) that interact in detector
surface “dead layer” result in reduced ionization yield
5 0 , 0 0 0 g a m m a c a l i b r a t
i o n e v e n t s
Nuclear-recoil WIMP-signal region
Neutrons from252Cf source
31K Gammas
from133Ba Source
Accept
Reject
Ionization Yield
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 24/44
Second Soudan Run WIMP-search data
ESTIMATE BKG: 0.4 ± 0.2 (sys.) ± 0.2 (stat.)electron recoils, 0.05 recoils from neutrons expected.
Optimized for ~0.5 background events
Z2/Z3/Z5/Z9/Z11
1 candidate
(barely) near-miss
Z2/Z3/Z5/Z9/Z11
I o n i z a t i o n Y i e l d
Recoil Energy (keV)
I o n i z a t i o n
Y i e l d
Recoil Energy (keV)0 10 20 30 40 50 60 70 80 90 100
1.5
1.0
0.5
0.0
0 10 20 30 40 50 60 70 80 90 100
1.5
1.0
0.5
0.0
Before timing cuts After timing cuts
34 kg-d after cuts
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 25/44
1st Year CDMS Soudan Combined Limits
• Upper limits on theWIMP- nucleon cross
section are 1.7×10-43 cm2 for a WIMP withmass of 60 GeV/c2
Factor 10 lower thanany other experiment
• Excludes regions of SUSY parameter spaceunder someframeworks Bottino et al. 2004 in
magenta (relax GUT
Unif.) Ellis et al. 2005
(CMSSM) in green
90% CL upper limits assumingstandard halo, A2 scaling (Spin. Ind.)
Z E P L I N I
E D E L W E I S
S
C D M S G e 2 - T o
w e r
C D M S G e
C o m b i n e
d
C r o s s s e c t i o n [ c m 2 ] ( n o r
m a l i z e d t o n u c l e o n )
WIMP Mass [GeV/c2 ]
1-tower: PRL 93, 211301 (2004); PRD 72 , 052009 (2005)
C D M S S i
2 - T o w e r D A M A
1 9 9 6
2-tower and combined: astro-ph/0509259
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 26/44
DAMA: NaI & Annual Modulation
100-kg detector mass, but no
rejection of gamma background
JuneJune
Dec DecDec
±2% Background
WIMP Signal
JuneJune
Dec DecDec
1 Y CDMS S d C bi d Li i
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 27/44
1st Year CDMS Soudan Combined Limits
• Upper limits on theWIMP- nucleon cross
section are 1.7×10-43 cm2 for a WIMP withmass of 60 GeV/c2
Factor 10 lower thanany other experiment
• Excludes regions of SUSY parameter spaceunder someframeworks Bottino et al. 2004 in
magenta (relax GUT
Unif.) Ellis et al. 2005
(CMSSM) in green
90% CL upper limits assumingstandard halo, A2 scaling (Spin. Ind.)
Z E P L I N I
E D E L W E I S
S
C D M S G e 2 - T o
w e r
C D M S G e
C o m b i n e
d
C r o s s
s e c t i o n [ c m 2 ] ( n o r
m a l i z e d t o n u c l e o n )
WIMP Mass [GeV/c2 ]
1-tower: PRL 93, 211301 (2004); PRD 72 , 052009 (2005)
C D M S S i
2 - T o w e r D A M A
1 9 9 6
2-tower and combined: astro-ph/0509259
DAMA 7-year NaI, Bernabei et al., astro-ph/0307403
DAMA Na ann. mod.(Gondolo/Gelmini)
S i D d WIMP li i
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 28/44
Spin-Dependent WIMP limits
ZEPLIN I
CRESST I
DAMA/NaI
CDMS II Ge
CDMS II Si
CDMS Stanford Si
CDMS II Ge
CDMS II Si
CDMS Stanford Si
CRESST I
DAMA/NaI
NAIAD
Super-K
Neutron coupling Proton coupling
Following the method of C. Savage, P. Gondolo, and K.
Freese, PRD70, 123513 (2004) (astro-ph/0408346).
http://dmtools.brown.edu/gaitskell&mandic
astro-ph/0509269
different nuclear form factors
S d d b d h d h t 1 t
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 29/44
Soudan and beyond: phased approach to 1-ton
• Maximize discovery
potential Background-free Lots of information
on each event
CDMS II today
CDMS II Soudan goal 2007
SuperCDMS:
Phase A (25 kg) 2011Phase B (150 kg)
Phase C (1000 kg)
25-kg technically ready and
endorsed by SNOLab
ZEPLIN I
EDELWEISS
ZEPLIN 2 goal
XENON 10 goal
http://dmtools.brown.edu/gaitskell&mandic
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 30/44
Survey of other techniques
Ed l i I i F j T l “1 k ” t
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 31/44
• First data taking in Fall 2000 at 4800 mwe depth
•
Detector improvements: 2nd data set early 2002• 3rd data taking: October 2002 - March 2003
Archeologicallead
3 * 320 g Ge detectors:heat and ionizationsimultaneous readout(NTD thermistor)Installed May 2002
Edelweiss-I in Frejus Tunnel: “1 kg” stage
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 32/44
EDELWEISS-I results
• 2000-2003: Exposure of ~60 kg-d
Three nuclear recoil candidates (30-100keV) consistent with neutron bkg
E D E L
W E I S S
- I
C D M
S - I I ( 2
0 0 4 )
WIMP search data (partial) WIMP cross section limit
astro-ph/0503265
Ed l i II
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 33/44
Edelweiss-II
• 100-detector cryostat being
installed at Frejus• Phase 1 detectors: 21 x 320-g NTD detectors ready
7 x 400-g NbSI detectors -expected end of 2005
• metal-insulator transition -additional fast component for surface event discrimination
CRESST II Ph d S i till ti
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 34/44
CRESST II: Phonons and Scintillation
Results from a 6g CaWO4 prototype
Very small scintillation signal for tungsten recoils
Scaled up to 300g detectors
• Nuclear recoils have much smaller
light yield than electron recoils
• Photon and electron interactions
can be distinguished from nuclear
recoils (WIMPs, neutrons)
Mirror
Particle Thermometer
Thermometer
Light Detector
Phonon Detector
hep-ex/9904005
Phonons (keV)
L i g h t ( k e V e e
)
CRESST II Ph d S i till ti
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 35/44
CRESST II: Phonons and Scintillation
Results from 20.5 kg-d expoure of two300-g CaWO4 prototypes
# No neutron shielding# Observe low-yield events
consistent with neutron rates andoxygen cross section & light yield
# Claim no tungsten recoils in lightyield region below oxygen yield
(not distinct from noise)
Astro-ph/0408006
Liquid Noble Detectors
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 36/44
WIMP
LXe E d
E s
Liquid Noble Detectors
PMTs
-
Time
Primary5 µs/cm
~40 nswidth
~1 µs width
---
B.A.Dolgoshein, V.N. Lebedenko, B.U. Rodionov, JETP Lett. 11 (1970) 513.
Courtesy of T. Shutt
Dual-phase LXe Time
Projection Chamber (TPC)
• Liquid Xe, Ar, Ne Detectors
• Atomic excimer states provide
recoil discrimination Pulse Shape Discrimination Secondary ionization signal
• eg, dual phase
May readily scale to large mass
• Challenges discrimination at low threshold 87Kr, 39Ar backgrounds
• Several programs Zeplin (UK/UCLA) – Xenon
• RESULTS from single phase PSD• Dual phase under construction
XENON (Columbia, Brown, Case, Yale, Florida)
• 10-kg in construction at Gran Sasso DEAP (LANL, Queens) – Argon
CLEAN (Yale, LANL) – Neon
UK Collaboration: Zeplin I
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 37/44
UK Collaboration: Zeplin I
•Single-phase detector Measure primary scintillation
Pulse shape discrimination
5kg LXe target (3.1kg fid)
3 PMTs
Cu construction
Polycold cryogen cooling
1 tonne Compton veto
Pulse shape
e.r.n.r.
e.r.
gamma+neutron calib.
gammas only
Zeplin I: Best limit on Xenon target
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 38/44
Zeplin I: Best limit on Xenon target
• 230 kg-days in 3.1-kg fiducial
mass Gamma calibration data from
contemporaneous veto events
Systematics dominated — no insitu neutron calibration
• Trouble recondensing target
Pulse shape
E D E L
W E I S S
2 0 0 2
Z E P L
I N I
D A M A
1 9 9 6
Astroparticle Physics 23 (2005) 444–462
Technology demonstration 10 kg → 100 kg→ Ton scale
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 39/44
ZEPLIN MAX – 1-Ton
ZEPLIN III
Technology demonstration 10 kg → 100 kg→ Ton scale
PMT
Gas
phaseLiquid
targetZEPLIN II
‘XENON’ Collaboration(Columbia et al)
+DEAP (LAr)
+CLEAN (LNe)+WARP (LAr)
+XMASS (LXe)(UK+UCLA)
Bubble Chamber Revival
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 40/44
Bubble Chamber Revival
• 2-kg CF3I Bubble Chamber – Chicagogroup (Collar, Sonnenschien, Crisler)
• Tune thermodynamic parameters Insensitive to min. ionizing and low-energy
electron recoils
Stability (time between events) consistentwith laboratory neutron background
Quadruple neutron-scatter event
Installed at 300 mwe depth at FNAL
Galactic origin: Directional signal & DRIFT
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 41/44
Dan Akerib Case Western Reserve University
Galactic origin: Directional signal & DRIFT
Cathode
Scattered WIMP
Recoil
Atom
Drift
direction
CS2 Recoil
Electron
E-Field
40 keV Ar in 40 torr Ar
y
( m m )
0
→
4 0
0 → 40x (mm)• Sensitive to direction of recoiling nucleus
Diurnal modulation signal – galactic origin of signal
• Drift negative ions in TPC (J. Martoff, Temple U.) No magnetic field required
Reduced diffusion• Electron recoils rejected via dE/dx
• DRIFT I: Proof of principle
• DRIFT II 1-kg modules
Full demonstration
•Challenge is MASS: how big is needed for ~100 events?
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 42/44
Summary
8/3/2019 Dan Akerib- Dark Matter: Looking for WIMPs in the Galactic Halo
http://slidepdf.com/reader/full/dan-akerib-dark-matter-looking-for-wimps-in-the-galactic-halo 43/44
Summary
• Dark matter remains a fundamental mystery Central role in cosmology, but we don’t yet know its nature
Possible solution lies in new fundamental particle physics
• Direct detection of DM Frontier HEP at accelerators
• Explore interesting SUSY region on similar time scale
• Potential to provide key info to ILC
An essential aspect to finding a concordant model:• dark matter in the laboratory ≠ dark matter in the halo!
• measurements needed on both frontiers— particle mass
— particle lifetime
— relic density
Indirect detection: astrophysical signal from annihilation products
• Significant recent advances in sensitivity New technologies have come online
Broad R&D enterprise
Next 5-10 years looks very exciting!