From Particles to the Cosmos
DARK MATTER
“Looking for The Body Cosmic”
Rick Gaitskell
Brown University, Department of Physics
source at http://cdms.brown.edu/
Gaitskell
Cosmic Anatomy: A Little Decomposition
Research opportunities in PARTICLE ASTROPHYSICS - Contact Prof Richard
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Time Table / Graduate Research
• Experimental Particle Astrophysics - Search for DARK MATTER
• CDMS Phase I Experiment
Has
been fully operating in shallow site California (Stanford) since 1997
• One of World’s Most Sensitive WIMP Dark Matter Experiment, now being used for
prototyping
• CDMS Phase II Experiment
Infrastructure
nearing completion in Soudan Mine, Minnesota (~1 km deep)
Install First Detectors Spring 2003 - Dark Matter Data 2002->2006 as
experiment grows
• Brown Goals
—On-site
operations & analysis Software for Events ~100 Gbyte/day
—Monte Carlo Analysis of Radioactive Backgrounds
—(Gaitskell lead effort to build CDMSII detectors in 1997-2001)
• New Detector Development - aimed at next phase (1 tonne Dark
Matter detector)
Liquid
Xenon (T~160 K) Scintillation / Photodetectors
• Brown Goals
—Detector
Development, will require combination of Solid State/Low Temp
Physics\
& AstroParticle
PhysicsASTROPHYSICS - Contact Prof Richard
Research
opportunities
in PARTICLE
3
Current Group At Brown
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Looking for Particle Dark Matter!
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CDMS Collaboration
Brown University
R.J. Gaitskell, J.-P. Thompson, M. Attisha,
P Sorensen, R. Morris, YW Kim
Case Western Reserve University
D.S. Akerib, A. Bolozdynya, D. Driscoll,
S. Kamat, T.A. Perera, R.W. Schnee, G.Wang
Fermi National Accelerator Laboratory
M.B. Crisler, R. Dixon, D. Holmgren
Lawrence Berkeley National Laboratory
R.J. McDonald, R.R. Ross, A. Smith
National Institute of Standards and Technology
Santa Clara University
B.A. Young
Stanford University
L. Baudis, P.L. Brink, B. Cabrera,
C. Chang, T. Saab
University of California, Berkeley
M.S. Armel, S.R. Golwala, V. Mandic,
Meunier, M. Perillo Isaac, W. Rau,
B. Sadoulet, A.L. Spadafora
P.
University of California, Santa Barbara
D.A. Bauer, R. Bunker,
D.O. Caldwell, C. Maloney,
H. Nelson, J. Sander, S. Yellin
J. Martinis
Princeton University
University of Colorado at Denver
M. E. Huber
T. Shutt
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Ω (assumes h~0.7)
CMB
SNIa
CDM
BBN
Map Galaxy Clusters at few Mpc scale
using:
Observation
Gas Mass
i) x-rays from gas
ii) Mapping S-Z CBR decrement
Galaxy Cluster Mass
i) Galaxy Motion and Virial Th.
ii) Hydrostatic Gas
iii) Grav. Lensing
~50/50 @ 8 kpc in Milky Way
ΩCMB photons
-5
~10
010320.3.rjg
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- Contact Prof
RichardAll
Underlying scale from Mike Turner, Chicago
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Ω (assumes h~0.7)
CMB
SNIa
CDM
Critical  10h 2 keVcm 3
~ 10 4
DM Local Halo  0.6GeVcm 3 (factor 2 uncertainty)
BBN
Map Galaxy Clusters at few Mpc scale
using:
Observation
Gas Mass
i) x-rays from gas
ii) Mapping S-Z CBR decrement
Galaxy Cluster Mass
i) Galaxy Motion and Virial Th.
ii) Hydrostatic Gas
iii) Grav. Lensing
~50/50 @ 8 kpc in Milky Way
ΩCMB photons
-5
~10
010320.3.rjg
Research opportunities in PARTICLE ASTROPHYSICS
- Contact Prof
RichardAll
Underlying scale from Mike Turner, Chicago
8
Cosmic Anatomy: A Little Decomposition
(Animation)
Hair Luminous (Stars) 0.5%
i.e. Baryonic material that is burning
Baryonic 5% Head
i.e. “Conventional” Material
e.g. Protons/Neutrons + Electrons (small)
MACHOs (?)
Pupils
Photons 0.001%
i.e. CMB Cosmic Microwav
Background
Dark Energy 60%
Unknown, but has property Trunk
of negative pressure(unlike matter)
causing acceleration in expansion of
Universe
Limbs
Cold Dark Matter 35%
Unidentified (but dominant) matter component
Also responsible for structure formation in early Universe
e.g. WIMPs, AXIONs, Heavy Neutrinos, Wimpzillas
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Cosmic Evolution (Animation)
Radiation Dominates g~a-4Matter Dominates m~a-3
L Dominates L~const
Size~1026 m
1
µs
10bn
yrs
1
bn
yrs
300,000
15bn
5,000
y y
3
mins
ps
Size~1 m
Size~Solar Sys.
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SUSY WIMP Outline
• Interplay of Cosmology and Particle Physics

3 Dark Matter Problems
• ~4.5% Baryonic (Protons/Neutrons etc)
• ~30% Non-Baryonic “New” Particles e.g. WIMPs
• ~65% Dark Energy - many possibilities, but no firm solution

SUSY WIMP Particle Dark Matter’s possible place in the
Universe
• Weakly Interacting Massive Particles
• Cryogenic Dark Matter Search - Results from CDMSI & II
Philosophy & techniques behind this experiment
 Looking for <1 event / kg /day, may be 1 events / kg / year !

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Navarro Astro-ph/9801073
Rotation Curves-Galactic Dark Matter
• Galaxies have constant rotation curves
If mass were
localised
GMm
rˆ
2
r
v2
  m rˆ
r
F
v
GM
r
For :
v  constant
then :
M r   r
Mdark  10 Mlum
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Considerable Debate in the US Press ...
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CDMS II: Site Depths & Muon Flux
SUF->Soudan Muon Flux Falls by ~104.5
MC predict residual punch-through neutron
signal
10-4 events/keV/kg/day
Muon Flux (m-2s-1)
Stanford Underground Site
Soudan Mine Head
Site of the CDMS
Experiment
(and most popular tourist
500 Hz muons
attraction in Minnesota!)
in 4 m2 shield
1 per
minute
in 4 m2 shield
Depth (mwe)
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CDMS-II Soudan Mine Installation
• Soudan, Minnesota, USA
Depth 2000 mwe
CDMS Huts, Fridge & Clean Rooms
(Hut in place, Shield/Icebox installation Nov 2000-)
(CDMS II starts data taking June 2002)
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Operating at 2341ft below surface …
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Panorama of Underground Soudan Clean Lab
• Look for :

Dilution Fridge
“Icebox” surrounded
by
• Polyethylene
• Pb

Faraday Cage
QuickTime™ and a Photo - JPEG dec ompres sor are needed to see this pic ture.
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CDMS II Detector Deployment
•Already demonstrated discrimination to < 10 event / kg /
year


>99.95% rejection of photons >10 keV (~0.5 events/keV/kg/day)
>99% rejection of surface-electrons >15 keV (~0.05
events/keV/kg/day)
•Identical Icebox, but no internal lead/poly, so fits seven
Towers each with three Ge & three Si ZIP detectors


Total mass of Ge = 7 X 3 X 0.25 kg > 5 kg
Total mass of Si = 7 X 3 X 0.10 kg > 2 kg
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Photograph of Shielding
Scintillator
muon veto
Copper cold volume
Neutronmoderator
moderator
Neutron
Pb shielding
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Radiopure Cold Volume (“Icebox”)
Cutaways of lids of
concentric copper
cans
Electronics stem for
signal cables
To internal
lead shield
and
detectors
Cold electronics
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Advanced detectors to be installed in Soudan
Mine
• An ‘all-up’ engineering run at SUF for CDMS II, install
underground for “First Dark” at Soudan Mine, Minnesota in
FET cards
June 2003
First tower with 3 Ge and 3 Si ZIPs
SQUID cards
4K
0.6 K
0.06 K
0.02 K
ZIP 1 (Ge)
ZIP 2 (Si)
ZIP 3 (Ge)
ZIP 4 (Si)
ZIP 5 (Ge)
ZIP 6 (Si)
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CDMS Ge & Si Fast Phonon & New Electrode
Detectors
Al/W Grid
8 Traps
37 - 5 mm
Squares
60% Area Coverage
Aluminum Collector Fins
888 X 1 µm
tungsten TES
in parallel
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ZIP: Active W Meander
1 µm W meander
(biased on superconducting transitio
Al-W Traps (films overlap)
Al Fins (~400 µm)
T<<Tc 1.2K
Quasiparticles Diffuse in Al films
Trapping
R
T
W meander
~65 mK
∆Wactive
∆Wtrap
Phonon from bulk of detecto
enters superconducting Al fil
and breaks Cooper Pair
generating quasiparticles
∆Al
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CDMS Nuclear Recoil Discrimination - Event by
Event
• Nuclear recoils arise from
 WIMPs

NOT A SIMULATION!
1334 gamma events, 616 neutron events
Gammas (external source)
Neutrons
• Electron Recoils arise from



photons
electrons
alphas
1/
2
year’s background
Neutrons (external source)
(Typical Background)
• Ionization yield

ionization/recoil energy
strongly dependent on type of
recoil
>> 1/2 year’s signal !!
Trigger Threshold
• Recoil energy

Phonons give full recoil energy
010402.3.rjg
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Richard
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More Information
Searching for the Missing Mass of the Universe WIMPs
GRADUATE & UNDERGRADUATE
OPPORTUNITIES
Cryogenic Dark Matter Search (CDMS II)
XENON (Next Generation) Dark Matter Search
CONTACT: Prof. Rick Gaitskell (x3-9783)
Brown University, Department of Physics
http://cdms.brown.edu/
http://gaitskell.brown.edu/
http://particleastrophysics.brown.edu/
Research
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