the search for axion dark matter pierre sikivie u of florida fermilab colloquium nov. 15, 2006
DESCRIPTION
g A level pooltable on an inclined floorTRANSCRIPT
The Search for Axion Dark Matter
Pierre SikivieU of Florida
Fermilab ColloquiumNov. 15, 2006
Outline
• Introduction• Axion cosmology• Dark matter axion detection• Solar axion detection• Laser experiments
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A level pooltable on an inclined floor
The Strong CP Problem
Because the strong interactions conserve P and CP, .
2
QCD 2...32
a agL G G
1010
The Standard Model does not provide a reason for to be so tiny,
but a relatively small modification of the model does provide a reason …
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If a symmetry is assumed,
relaxes to zero,
PQU (1)
2
2
1... .32 2
a a
a
a gL G G a af
a
af
and a light neutral pseudoscalar particle is predicted: the axion.
f f
a
a
610 GeVeVa
a fm
aa
aL g E Bf
= 0.97 in KSVZ model 0.36 in DFSZ model
g
5fa f fa
aL i g f ff
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Searching for the pooltable oscillation quantum
1 ton
The invisible axion ?
laboratory searches
510 15101010 (GeV)af
(eV)am 1 510 1010
stellar evolution
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Relic pooltable oscillations
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The remaining axion window
laboratory searches
510 15101010 (GeV)af
(eV)am 1 510 1010
stellar evolution
cosmology
Thermal axions
q
ga
these processes imply an axion decoupling temperature
D
13
0106.75) 0.908 K(a N
T t
thermal axion
temperature today:
DN = effective number of thermal degrees of freedom at axion decoupling
11D 12
2
3 10 GeV10 GeV
afT
There are two axion populations: hot and cold.
When the axion mass turns on, at QCD time,
1T
1t
1 1 GeVT 71 2 10 sect
91
1
1) 3 10 eV(ap tt
Axion production by vacuum realignment
2 2 21 1 1 1
1
1
2
1
2( ) ( ) ( ) ( )a a at t t t
tn m a f
GeVT GeVT
V
a
V
a
1
0
3 76
0 1( ) ( )a aa aR
Rt tm mn
initialmisalignmentangle
Axions are cold dark matter
Density
Velocity dispersion
Effective temperature
75610 eV
aa m
25 3
0, eff10 eV
aa
T tm
55 6
170
10 eV10va
a mct
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Searching for relic pooltable oscillations
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Axion dark matter is detectable
aa
aL g E Bf
0B
a
X
A/D FFT0B001TME
3v 10c
2 21
2)ah m c
1aQ
1LQ
dPd
2 /am hc
610aQ
conversion power on resonancea
2
022
500 liter 7 Tesla 0.42 10 Watt BV C
2 2
25 3 50.36 5 10 gr/cm GHz 10La ag m Q
hc
search rate for s/n = 4
2
20 La a
a
gP V B
fC m Q
22
22
32 10 Watt
1.2 GHzyear n
P KT
dfdt
ADMX Collaboration
LLNL: S. Asztalos, C. Hagmann, D. Kinion, L.J Rosenberg, K. van Bibber, D. Yu
U of Florida: L. Duffy, P. Sikivie, D. Tanner
NRAO: R. Bradley
Axion Dark Matter eXperiment
High resolution analysis of the signal may reveal
fine structure …
ADMX hardwarehigh Q cavity experimental insert
ADMX hemt amplifiers
ADMX MedRes limits
Upgrade with SQUID AmplifiersIB
Vo (t)
The basic SQUID amplifier is a flux-to-voltage transducer
SQUID noise arises from Nyquist noise in shunt resistancescales linearly with T
However, SQUIDs of conventional design are poor amplifiers above 100 MHz (parasitic couplings).
Flux-bias to here
ADMX Upgrade: replace HEMTs (2 K) with SQUIDs (50 mK)
In phase II of the upgrade, the experiment is cooled with a
dilution refrigerator.
SQUIDs packaged into amplifiers
Darin KinionSQUIDs mounted on fridge
4 cavity array – engineering run
Piezo motors have low power dissipation, work at
low temperatures and high magnetic fields
3v 10c
2 21
2)ah m c
1aQ
1LQ
dPd
2 /am hc
610aQ
The cold dark matter particles lie on a 3-dimensional sheet in
6-dimensional phase space
the physical density is the projection of the phase space sheet onto position space
z
z.
( , t) = t) r rv
The cold dark matter particles lie on a 3-dimensional sheet in
6-dimensional phase space
the physical density is the projection of the phase space sheet onto position space ( , t) = t) ( , t)r r rv v
z
z.
The cold dark matter particles lie on a 3-dimensional sheet in
6-dimensional phase space
the physical density is the projection of the phase space sheet onto position space ( , t) = t) ( , t)r r rv v
z
z.
Phase space structure of spherically symmetric halos
Implications: 1. At every point in physical space, the
distribution of velocities is discrete, each velocity corresponding to a particular flow at that location.
2. At some locations in physical space, where the number of flows changes, there is a caustic, i.e. the density of dark matter is very high there.
(from Binney and Tremaine’s book)
Galactic halos have inner caustics as well as outer caustics.
If the initial velocity field is dominated by net overall rotation, the inner caustic is a “tricusp ring”.
simulations by Arvind Natarajan
The caustic ring cross-section
an elliptic umbilic catastrophe
D-4
On the basis of the self-similar infall model(Filmore and Goldreich, Bertschinger) with angular momentum (Tkachev, Wang + PS), the caustic rings were predicted to be
in the galactic plane with radii
was expected for the Milky Way halo from the effect of angular momentum on the inner rotation curve.
1, 2,3...n
rot max40kpc v j220km/s 0.26
nn
a
max 0.26j
Composite rotation curve(W. Kinney and PS, astro-ph/9906049)
• combining data on 32 well measured extended external rotation curves
• scaled to our own galaxy
The Big Flow
• density
• velocity
• velocity dispersion
24 35 1.7 10 gr/cmd
previous estimates of the total local halo density range from 0.5 to 0.75 10 gr/cm-24 3
in the direction of galactic rotation
in the direction away from the galactic center
5 (470 100 ) km/sv r
ur $ $
5v m/s
$r$
an environmental peak, as seen
in the medium
and
highresolutionchannels
L. Duffy et al.
Axion to photon conversion in a magnetic field
Theory
• P. S. ’83• L. Maiani, R. Petronzio and E. Zavattini ’86• K. van Bibber et al. ’87• G. Raffelt and L. Stodolsky, ‘88 • K. van Bibber et al. ’89
Experiment
• D. Lazarus et al. ’92• R. Cameron et al. ‘93• S. Moriyama et al. ’98, Y. Inoue et al. ’02• K. Zioutas et al. 04• E. Zavattini et al. 05
0B
a
22
2 2sin
( )z
za
Lqg
af q
p
x
with
in vacuum probability
2 2pl
2za
aE
mq
Cern Axion Solar Telescope
Decommissioned LCH test magnet
Rotating platform
3 X-ray detectors
X-ray Focusing Device
Sunset
Photon detectors
Sunset axions
Sunrise axions
Sunrise
Photon detectors
1a
a
L a E BM
1
1
a
aaMg
gf
Primakoff conversion of solar axions in crystals on Earth
a
x0 ( )E x
aE few keV
Bragg scattering on crystal lattice
Solax, Cosme ’98
Ge
DAMA ‘01
NaI (100 kg)
Detecting solar axions using Earth’s magnetic field
by H. Davoudiasl and P. Huber
hep-ph/0509293
Sun Eartha
0B
For axion masses , a low-Earth-orbit x-ray detector with an effective area of , pointed at the solar core, can probe down to , in one year. 1( )
a
aM
L a E B
410 eVam 4 210 cm
GeVaM
0B
A
Linearly polarized light in a constant magnetic field
Rotation
0B
A
'A 'A A
1
2' (1 )A A p i
2 2 220
2 44 sin4a
a a
B m LpM m
1a
a a
gg
f M
1
sin(2 )4p
Rotation and Ellipticity
0B
A
'A 'A A
1
2' (1 )A A p i
2 2 220
2 44 sin4a
a a
B m LpM m
1a
a a
gg
f M
2 2 2 20
2 42 sin2 2a a
a a
B m L m LM m
Experimental observation of optical rotation generated in vacuum by a magnetic field
the average measured optical rotation is(3.9 0.5) 10 rad/pass
through a 5 T, 1 m long magnet
by E. Zavattini et al. (the PVLAS collaboration)Phys. Rev. Lett. 96 (2006) 110406
-12
PVLAS
The PVLAS result can be interpreted in terms of an axion-like particle b
inconsistent with solar axion searches, stellar evolution
descrepancy may be avoided in some modelsE. Masso and J. Redondo, hep-ph/0504202
I. Antoniadis, A. Boyarski and O. Ruchayskiy, hep-ph/0606306R.N. Mohapatra and S. Nasri, hep-ph/0610068
1
bb ML b E B
5 61 10 GeV 6 10 GeVbM
0.7 meV 2 meVbm
Vacuum
Phase I Phase II
4He 3He
Shining light through walls K. van Bibber et al. ‘87
A. Ringwald ‘03
R. Rabadan, A. Ringwald and C. Sigurdson ‘05
P. Pugnat et al. 05
R. Battesti et al.
A. Afanasev et al.
0B
x0B
a
x
rate 4
1
af
Macroscopic forces mediated by axions
Theory:
J. Moody and F. Wilczek ’84
Experiment:
A. Youdin et al. ’96W.-T. Ni et al. ‘96
5f
f ffa fa
mf
fL a i fg
forces coupled to the f number density
forces coupled to the f spin density
1710f background of
magnetic forces
Conclusions
Axions solve the strong CP problem and are a cold dark matter candidate.
Axions haven’t been found yet.
If axions exist, they are present on Earth as dark matter and emitted by the Sun.
If an axion signal is found, it will provide a rich source of information on the structure of the Milky Way halo, and/or the Solar interior.
Telescope search for cosmic axions
M.S. Bershady, M.T.Resselland M.S. Turner ’90 galaxy clusters 3 – 8 eV B.D. Blout et al. ‘02 nearby dwarf galaxies 298 – 363 eV
a
2amE
25
25
2 )V 0.36
1(0.67 10 sec e
a gma
9 -11.0 10 GeVag