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MAD MAX
Javier RedondoUniversidad de Zaragoza (Spain)Max Planck Institute für Physik
Axions are necessarily dark matter
0 ⇡�⇡
time
n
nCoherent oscillations
=Dark Matter Axions
Energy
~ One parameter theory
axion mass✓(t, x) = a(t, x)/fa
ma = 6meV109 GeV
fa
Measured today |✓| < 10�10 (strong CP problem)
- is it a dynamical field? ✓(t,x)generated by QCD!
✓(t) = ✓0 cos(mat)
Relic density as function of mass
- Random IC (after a phase transition)- One Universal IC (inflation smoothens the axion field)
�⇡
✓
⇡
Theta evolution, Averaged SCENARIO I
DM dominated by string radiation
- Axion DM scenarios
Excluded (too much DM) ok sub
Phase transition (N=1)strings+unstable DW’s
Axion dark matter
Initial conditions set by :
Excluded (too much DM) ok sub
Phase transition (N=1)strings+unstable DW’s
- Axion DM scenarios
oktuned (anthropic?) tuned
Inflation smooth⌦aDMh2 ' ✓2I
✓80µeV
ma
◆1.19
Excluded
Axion dark matter
Initial conditions set by :
Detecting Axions
⇢aDM = 0.3GeV
cm3
✓0 = 3.6⇥ 10�19
⇢a =1
2(a)2 +
1
2m2
aa2 =
1
2m2
af2a✓
20
V✓✓
Cavities Mirrors LC-circuit
Spin precession Atomic transitions Optical
Axion experiments (target areas)
osc. EDM
LC
only one running
not DM
test bench
Axion Dark Matter eXperiment (Seattle, Yale...)
Excluded
IAXO?
SCENARIO I
ADMXADMX-HF
QUAX
?
ARIADNE✓0QCD > 10�14?
CAPP
osc. EDM only one running
baby bornMunich Axion Dark MAtter “eXperience”
not DM✓0QCD > 10�14?
Excluded
IAXO?
SCENARIO I
ARIADNE✓0QCD > 10�14?
QUAX
?LC
MADMAX
Axion experiments (target areas)
ADMXADMX-HF
CAPP
- In a static magnetic field, the oscillating axion field generates EM-fields
B-field
- Electric fields - Oscillating at a frequency
(amp independent of mass!)
Axion DM in a B-field
LI = �Ca�↵
2⇡
a
faB ·E
LI = �Ca�↵
2⇡✓(t)B
ext
·E
source
! ' ma
Ea = Ca�↵B
ext
2⇡✓0
cos(mat)
10-7 10-6 10-5 10-4 10-310-1
1
10
102
10310-1 1 10 102
10-1
1
10
102
103
c�KSVZ
DFSZ
AD
MX
RBF
UF
AD
MX AD
MX
2 AD
MX
-HF
CARR
ACK
?
ma[µeV]
⌫[GHz]
IAXO
- Haloscope (Sikivie 83) “Amplify resonantly the EM field in a resonant cavity”
- Signal (V / m�3a ) P
out
/ V ma ⇠ 1
m2
a
- Noise Pnoise
= Tsys
�⌫a / m2
a
P ⇠ Q|Ea|2(V ma)G
Resonant cavity experiments
Output EM power
on resonance ⌫res =ma
2⇡
Ca�
ma[eV]
30 cm 0.6 cm
spherical reflecting dish
pre MADMAX (dish antenna)- Do not give up volume -> Area
D � 1
ma
P ⇠ |Ea|2A
Radiation from a dielectric interface ...
Emitted EM-wave
E(t) =c�↵✓0B
2⇡✏cos(mat) E(t) =
c�↵✓0B
2⇡cos(mat)
Boundary conditions!E||1 = E||2Emitted EM-wave
Radiation from a magnetised mirror : Power
Emitted EM-wave
MIR
ROR
Power
Area
⇠ 2.2⇥ 10
�27Watt
m
2
✓Ca�
2
B||
5T
◆2
Many dielectrics : MADMAX at MPP Munich
Emitted EM-waves from each interface
+ internal reflections ......
- Emission has large spatial coherence; adjusting plate separation -> coherence
boost factorP
Area⇠ 2.2⇥ 10�27 W
m2
✓Ca�
B||
10T
◆2
⇥ �2(!)
0 1 2 3 4
0.2
0.4
0.6
0.8
1.0
One dielectric
Axion emission (boost factor) (n=2,3,4)
⌫/⌫00 1 2 3 4
0.2
0.4
0.6
0.8
1.0
transmission coefficient
⌫/⌫0
�0
2= d
- Frequency response
Close to nu0, many layers
18 19 20 21 22
20
40
60
80
100
120
140
Emitted EM-waves from each interface
+ internal reflections ......
boost factor (N=10,40,80; n=3,nu0=20 GHz)
⌫[GHz]
�N ⇠ N ⇥ �1
Nice boost, excellent bandwidth!
mirror
n = 1, �
n, �n
20 40 60 80 1000
1
2
3
4
5
6
z
z=4.5, 4, 3.5, 3, 2.5 mm
zn
zn=0.65 mmn=3
⌫[GHz]
[...]
�
When dielectrics are non-transparent, mild resonances appear that allow higher boosts
Close to 2nu0, cavity effects
Maximum effect for z =�
2, zd =
�0
4=
�
4n
tuning
Distances between layers allow tuning (transfer matrix formalism)
JCAP 1701 (2017)
Broadband vs narrowband central frequency
Potential reach
A = 1 m^2B-field = 10 T80disk n=5
whys
- why can it work?
Large volume + (relatively) simple tuning long measurements broadbandshort measurements narrowband
- What can go wrong?
- 10T dipole-like Magnet, 1 m^2 aperture !- 1 m^2 dielectrics (tiling smaller pieces)- Tolerances (several micron distances)- difraction
Conclusions
- Strong CP problem and dark matter motivate Axions
- Most predictive model (N=1) mass~ 0.1 meV (fa ~ 10^11 GeV)
- Many experimental efforts, solid player missing in that range
- MW emission from interfaces is weak , make layered haloscope
- Munich Axion Dark MAtter eXperiment