p. sikivie- the admx search for axion dark matter
TRANSCRIPT
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
1/44
The ADMX search foraxion dark matter
P. Sikivie (CERN & U. of Florida)
Moriond 2006
La Thuile, March 16, 2006
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
2/44
Outline
Introduction
Axion cosmology
Dark matter axion detection
the Axion Dark Matter eXperiment
Phase-space structure of CDM halos
A high resolution search
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
3/44
The Strong CP Problem
Because the strong interactionsconserve P and CP, .
2
QCD 2...
32
a ag L 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
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
4/44
If a symmetry is assumed,
relaxes to zero,
PQU (1)
2
2
1
... .32 2
a a
a
a g
L G G a af
= + + + ..
%
a
af
=
and a light neutral pseudoscalarparticle is predicted: the axion.
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
5/44
f f
a
a
6
10 GeVeVa
af
m 6
a
a
a L g E B
f
=
ur ur
= 0.97 in KSVZ model0.36 in DFSZ modelg
5fa f fa
a L i g f f
f=
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
6/44
The remaining axion window
laboratorysearches
5
10
15
10
10
10(GeV)
a
f
(eV)am 1510 1010
stellar
evolution
cosmology
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
7/44
Axions are cold dark matter
Density
Velocity dispersion
Effective temperature
75
610 eVa
am
25 3
0,eff
10 eVa
aT t m
34
) 10 (
55 6
17
0
10 eV10v
a
am
ct
) 3
(
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
8/44
There are two axion
populations: hot and cold.
When the axion mass turns on, at QCD time,
1T
1t
1 1 GeVT7
1 2 10 sect
91
1
1) 3 10 eV(ap t t
=
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
9/44
Axion production by vacuum realignment
2 2 2
1 1 1 1
1
1
2
1
2( ) ( ) ( ) ( )a a at t t t
tn m a f
GeVT 1 GeVT 1
V
a
V
a
1
0
3 7
60 1( ) ( )a aa a
R
Rt tm mn
initialmisalignmentangle
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
10/44
If inflation after the PQ phase transition
2
2IHa
< >
1
( )a I
a a
H
f t
6 10
.may beaccidentallysuppressed
. producesisocurvaturedensity perturbations
isocurvature CMBR constraint
75 6
2
1
10 eV0.25 ( )
aat
m
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
11/44
If no inflation after the PQ phase transition
. cold axions are produced by vacuumrealignment, string decay and wall decay
.
75 610 eV0.5
a
am
axion miniclusters appear
5
5
313
mc
10 eV10
a
M Mm
5
1
613
mc
10 eV10 cm
a
lm
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
12/44
Axion dark matter is detectable
a
a
a L g E B
f
=
ur ur
0Bur
a
X
A/D FFT0Bur001TME
ur
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
13/44
3v 10c
=
2 21
2 )ah m c = (1 +
1
aQ
1LQ
dP
d
2/am hc
610aQ
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
14/44
conversion power on resonance
a
2
022
500 liter 7 Tesla 0.42 10 Watt
BV C =
2 2
25 3 50.36 5 10 gr/cm GHz 10
La ag m Q
h
c
search rate for s/n = 4
2
2
0 La a
a
gP V B
f
C m Q
1 =
22
22
3
2 10 Watt
1.2 GHz
year n
P K
T
df
dt
=
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
15/44
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
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
16/44
Axion Dark Matter eXperiment
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
17/44
High resolution analysis ofthe signal may reveal
fine structure
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
18/44
ADMX hardware
high Q cavity experimental insert
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
19/44
ADMX hemt amplifiers
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
20/44
ADMX MedRes limits
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
21/44
Upgrade with SQUID Amplifiers
IB
Vo (t)
The basic SQUID amplifier is a flux-to-voltage transducer
SQUID noise arises from Nyquistnoise in shunt resistance
scales linearly with T
However, SQUIDs of conventionaldesign are poor amplifiers above100 MHz (parasitic couplings).
Flux-bias to here
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
22/44
ADMX Upgrade: replace HEMTs (2 K)
with SQUIDs (50 mK)
In phase II of the upgrade, theexperiment is cooled with a
dilution refrigerator.
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
23/44
SQUIDs packaged into amplifiers
Darin KinionSQUIDs mounted on fridge
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
24/44
From outwards-in:
Iron shieldCryoperm (mumetal) shieldsSuperconducting shieldsSQUID amplifier packageSQUIDs
The upgrade will be sensitive tothe more pessimistically-coupledaxions even if they are a minorityfraction of the dark-matter halo.
The magnetic field needs tobe cancelled at the locationof the SQUID.
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
25/44
4 cavity array engineering run
Piezo motors have low power dissipation, work atlow temperatures and high magnetic fields
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
26/44
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
27/44
3v 10c
=
2 21
2 )ah m c = (1 +
1
aQ
1
LQ
dP
d
2/am hc
610aQ
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
28/44
The cold dark matter particles lie on
a 3-dimensional sheet in6-dimensional phase space
the physicaldensity is theprojection ofthe phase
space sheetonto positionspace ( , t) = t) ( , t)r r rv v( +
ur r r ur r
z
z.
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
29/44
The cold dark matter particles lie on
a 3-dimensional sheet in6-dimensional phase space
the physicaldensity is theprojection ofthe phase
space sheetonto positionspace ( , t) = t) ( , t)r r rv v( +
ur r r ur r
z
z.
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
30/44
Implications:1. At every point in physical space, the
distribution of velocities is discrete, eachvelocity corresponding to a particular flow
at that location.
2. At some locations in physical space, where
the number of flows changes, there is acaustic, i.e. the density of dark matter is veryhigh there.
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
31/44
Phase space structure of
spherically symmetric halos
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
32/44
(from Binney and Tremaines book)
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
33/44
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
34/44
simulation by Arvind Natarajan
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
35/44
The caustic ring cross-section
an elliptic umbilic catastrophe
D-4
-
8/3/2019 P. Sikivie- The ADMX search for axion dark matter
36/44
The Big Flow
density
velocity
velocity dispersion
24 3
5 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 50