Tokyo axion helioscope experimentand
other axion experiments
Y. InoueInternational Center for Elementary Particle Physics, The University of Tokyo
for the Sumico Collaboration
Rencontres de Moriond EW2011, 18 March 2011, La Thuile, Italy
Collaborators
M. Minowa, R. Ohta, T. Mizumoto, T. HorieDepartment of Physics, School of Science, The University of Tokyo
Y. InoueInternational Center for Elementary Particle Physics, The University of Tokyo
A. YamamotoHigh Energy Accelerator Research Organization (KEK)
Logo designed by −→Yuki AkimotoGraduate School of Medicine, The University of Tokyo
Outline
• Introduction
– What & how we are going to detect?
• Tokyo axion helioscope
– Hardware, results & prospects
• Other experiments
– CAST
– Crystalline detectors
– Microwave cavity (axion haloscope)
• Conclusions
Introduction
Strong CP problem
Two independent sources of CP violation in QCD:
Lθ̄ =θ̄
32π2Fµν
a F̃aµν , θ̄ = θ + arg detMq,
where{
θ ← initial QCD ground stateMq ← quark mass matrix (EW scale physics)
⇑r⇓
Neutron EDM:
dn < 2.9× 10−26 e cm (θ̄ < 10−10)
Peccei–Quinn mechanism
Global chiral U(1)PQ + SSB −→ Axion (NG boson)
+ Making θ̄ into a dynamic parameter which should fall into thepotential minimum:
θ̄ = θ + arg detMq +a
fa
Axion mass:
ma =√
z
1 + z
fπmπ
fa
-πfa 0 πfa
a
V [a]
@@@I
θ̄ = 0
Axion-photon coupling
The axion couples to two photons:
Laγγ = −14gaγaFµν F̃µν = gaγa~E · ~B
gaγ =α
2πfa
[E
N− 2(4 + z)
3(1 + z)
]
= 1.9× 10−10( ma
1 eV
)[E/N − 1.92][GeV−1]
Model dependent factor:
E/N = 0 (std. KSVZ), 8/3 (GUT DFSZ).
E = Tr(QPQQ2em), N = Tr(QPQQ2
c)
Exclusion plot (gaγ–ma)
gaγ
[GeV
-1]
ma [eV]
10-16
10-15
10-14
10-13
10-12
10-11
10-10
10-9
10-8
10-7
10-6
10-6 10-5 10-4 10-3 10-2 10-1 100 101
Axion Helioscope
Axion models
E/N = 0 (K
SVZ)
E/N = 8/3 (G
UT-DFSZ)
Solar age
HB stars
Crystal solar axion
Microwave cavity
Laser
Axion helioscope[P.Sikivie, PRL51,1415(1983)]
The sun can be a powerful source of axions.
Primakoff process
photon axion
Ze ← Laγγ = gaγa~E · ~B → MagneticField
axion photon
Axion helioscope[P.Sikivie, PRL51,1415(1983)]
0
2
4
6
8
10
0 2 4 6 8 10 12
ax
ion
flu
x [
10
10cm
-2s-1
keV
-1]
E [keV]
×(gaγ/10-10
GeV-1
)2
Conversion rate:
Pa→γ . 14g2
aγB2L2
Sensitivity:gaγ ∝ (BL)−
12
(bg rate
time× area
) 18
Buffer gas — to reach out for heavier axions
Conversion rate:
Pa→γ =g2
aγ
2
∣∣∣∣∣∫ L
0
Beiqzdz
∣∣∣∣∣
2
.g2
aγB2L2
4,
q = kγ − ka ≈m2
γ −m2a
2E.
In vacuum, coherence is lost for ma &√
πE/L. . .
⇓
The effective photon mass in buffer gas:
mγ =√
4παNe
me.
Ne: electron density
0 0.05 0.1 0.15 0.2 0.25P
a→
γm
a [eV]
vacuum with buffer gas
Tokyo axion helioscope
Tokyo axion helioscope (Sumico)
Sumico V detector
• B = 4T, L = 2.3m
• 268A persistent current
• 16 PIN photodiodes
• Track the sun ∼ 12 hours/day
Gas handling system
PIN photodiodes
PV PV
heat exchanger (40K, 5K)
evacuatedline
rupture disc
diaphragm pump
exhaust
PC1
PC2
TCP/IP
EIA232
He gas
vacuum vessel
DAC cardPCI
+amp
piezo valvesPV−1000
Yokogawa MU101
HORIBASTEC
(5K)
gas container (5K)x−ray window
Helium density time chart
400
450
500
550
600
Dec Jan Feb Mar Apr0.8
0.9
1
hel
ium
den
sity
[m
ol/
m3 ]
ph
oto
n m
ass
[eV
]
5meV
3days
start
(encoder broken)end
quench
end of the 1stunmanned tracking
2nd unmanned tracking
2007 2008
PIN photodiode X-ray detector
• Inside OFHC shield @ T = 60K
• 16 PIN photodiodes4 PIN/module
• chip:Hamamatsu S3590-06-SPL
• size:11× 11× 0.5mm3/PIN
• active area > 9× 9 mm2/PIN
• inactive surface < 0.35µm
[T.Namba et al., NIMA489(2002)224][Y.Akimoto et al., NIMA557(2006)684]
Energy spectrum
0
1
2
3
4
5
6
7
8
0 5 10 15 20
cou
nt
rate
[10
-4k
eV-1
s-1]
E [keV]
solarbackground
-3
-2
-1
0
1
2
3
0 5 10 15 20
sola
r –
bg
[10
-4k
eV-1
s-1]
E [keV]
fit
Upper limit 95% CL (mγ=ma=1.004eV)
χ2(ma) =
mγ,maxXmγ=mγ,min
20 keVX
E=4 keV
»Nsolar(E, mγ)−Nbg(E, mγ)−Ntheo(E, q)
σ(E, mγ)
–2
Exclusion plot[Y.Inoue et al., PLB668(2008)93]
5×10-10
1×10-9
2×10-9
3×10-9
0.8 0.9 1
gaγ
[GeV
-1]
ma [eV]
Upper limit (95% CL)
χ2(ma) =
mγ,maxXmγ=mγ,min
20 keVX
E=4 keV
»Nsolar(E, mγ)−Nbg(E, mγ)−Ntheo(E, q)
σ(E, mγ)
–2
Sumico results & prospect
gaγ
[GeV
-1]
ma [eV]
10-11
10-10
10-9
10-8
10-3 10-2 10-1 100 101
PLB434(1998)147 PLB536(2002)18PLB668(2008)93
Phase I (vacuum) Phase IIPhase III latest
Phase IIIprospect
Sumico
Axion modelsE/N =
0 (KSVZ)
E/N =
8/3 (GUT-D
FSZ)
Solar age
HB stars
SOLAX, COSME, CDMS
DAMA (90%)
CAST vacuum
4He3He
Lazarus
Phase III upgrades, troubles & status
3 Introduced a cryogenic rupture disk (Done)
3 Automated gas density control (Done)−−−−−−−−−−−−−−−−−−−−−−−Sumico 2007–2008 run −−−−−−−−−−−−−−−−−−−−−−−
3 Reworked He pipelines for quicker evacuation (Done)
3 Thermoacoustic oscillation at higher ρHe
→ Introduced a blind-end bellows at Troom section (Resolved)
• Thermal non-uniformity at higher ρHe
→ Introduced new heat exchangers (Testing)
3 1st X-ray window got a puncture/crack→ Repaired by the manifacturer (Test passed)
8 2nd Spare window broken entirely by thermal stress (Alas!)
Phase III upgrades, troubles & status (gallery)
©©¼New heat exchangers
¢¢
¢®
Light shinningthrough the
2nd X-ray window
1st X-ray windowrepaired
with epoxy
?
Other experiments
CAST (CERN Axion Solar Telescope)[K.Zioutas et al., PRL94,121301(2005)]
• B = 9 T, L = 9.26m (LHC test magnet)
• Vertical ±8◦, horizontal ±40◦
• TPC, Micromegas, CCD X-ray telescope
Sumico & CAST side-by-side
Sumico CAST
Tokyo CERN
4T× 2.3m 9T× 9.26m
12 hours/day 2× 1.5 hours/day4He @ 5 K (ma . 2 eV) 4He,3He @ 1.9 K (ma < 1.1 eV)
CAST result
From[J.Galan, arXiv:1102.1406]
Crystal detectors[R.J.Creswick et al., PLB427(1998)235]• Primakoff conversion
in a lattice
• Bragg condition:
2d sin θ = nλ
θθ
d
axion photon
• SOLAX — Ge [A.O.Gattone et al., NPB-PS70(1999)59]
gaγ < 2.7× 10−9GeV−1 (95%)
• COSME — Ge [A. Morales et al., Astropart. Phys. 16(2002)325]
gaγ < 2.78× 10−9GeV−1 (95%)
• DAMA — NaI(Tl) [R.Bernabei et al., PLB515(2001)6]
gaγ < 1.7× 10−9GeV−1 (90%)
• CDMS — Ge [Z.Ahmed et al., PRL103,141802(2009)]
gaγ < 2.6× 10−9GeV−1 (95%)
Microwave cavity (axion haloscope)[P.Sikivie, PRL51,1415(1983)]
0B
a hνm
Laγγ = gaγa~E · ~Bhν = γma,
⟨β2
⟩ ∼ 10−6
1GHz = 4.14 µeV
Power =g2
aγV B20ρhaloCmode
mamin(Qcavity, Qhalo)
gaγ ∝ B−10 V −1/2T
1/2noise
Pioneers: Rochester-BNL-FNAL (RBF), Florida (UF)
ADMX (Axion Dark Matter eXperiment)[S.J.Asztalos et al., PRL104,041301(2010)]
http://www.flickr.com/photos/llnl/4305091276
• LLNL
• B0 = 7.6T
• GaAs HFET (Ts ∼ 2K)
→ dc SQUID (Ts = 47mK @ 700 MHz)
• Scanned ma = 1.9–3.53 µeV
• Next upgrade: Tcavity ∼ 2K→ 100mK
CARRACK(Cosmic Axion Research with Rydberg Atoms in resonant Cavity in Kyoto)
[M.Tada et al., NPB-PS72(1999)164]
• Microwave photon counting using Rydberg atoms39K, 85Rb, etc.; ns→ np, n = O(100–200)
• B = 7 T, Tcavity = 10 mK
• Goal: cover ma = 8–30 µeV up to gaγ ∼ DFSZ prediction.
http://www.ltm.kyoto-u.ac.jp/newcarrack/
γaxion
laser
e
g
strong magnetic fieldfree frommagnetic field
selectivefieldionizationdetector
electrondetector
conversion cavity detection cavity − V
0e
ion
BextRydberg atoms
gαγγ
[M.Tada et al., arXiv:physics/0101028]
Exclusion plot
gaγ
[GeV
-1]
ma [eV]
10-16
10-15
10-14
10-13
10-12
10-11
10-10
10-9
10-8
10-7
10-6
10-6 10-5 10-4 10-3 10-2 10-1 100 101
Phase I Phase II
Phase III latest
Sumico
Axion models
E/N = 0 (K
SVZ)
E/N = 8/3 (G
UT-DFSZ)
Solar age
HB stars
SOLAX, COSME, CDMS
DAMA
CAST
CAST 4He
CAST 3He
Lazarus
AD
MX
UF+RFB
CA
RR
AC
K g
oal
Laser
Conclusions
• 2 Fronts of experimental axion searches:
– Solar axion ma ∼ O(eV)Sumico, CAST, crystals
– Dark matter axion ma ∼ O(µeV)ADMX, CARRACK
• Sumico Phase III
– Sumico 2007–2008 result:
gaγ < 5.6–13.4× 10−10GeV−1 (0.84 < ma < 1.00 eV)
– Upgrading toward ma . 2 eV
Backup
Axion-photon oscillation[Raffelt & Stodolsky, PRD37(1988)1237]
Wave equation for (A⊥, A‖, a) plane wave propagating along thez axis:
ω2 + ∂2z −m2
γ 0 00 ω2 + ∂2
z −m2γ gaγBω
0 gaγBω ω + ∂2z −m2
a
A⊥A‖a
= 0.
↓A‖ a mixing
Notes on buffer gas• 4He is used ⇐⇒ CAST is using 3He
• Temperature is kept high enough above the critical point(pc = 0.227MPa, Tc = 5.1953K)
• X-ray absorption and decoherence due to gravity are not fataleven at mγ ∼ 2 eV
mγ =√
4παNe
me
−→
0
0.5
1
1.5
2
2.5
3
3.5
0 0.05 0.1 0.15 0.2 0.25 0.3
effe
ctiv
e p
ho
ton
mas
s [e
V]
pressure [MPa]
4He T=6K
rup
ture
dis
k
X-r
ay w
ind
ow
safety region
Buffer gas container
• Welded 4 ×st. steel 30421.9× 17.9× 2300 mm3
square pipes
• Wrapped with99.999% pure Al0.1-mm thick × 2 layers
• Thermal conductivity(measured)& 10−2W/K @ 5 K, 4 T
X-ray window
Metorex C10 window(custom)
• 25µm Be foils with 1µm polyimide coating
• Supported by Ni grid
• Withstands up to 0.3 MPa
• Transmits & 80% for E > 3keV
Internal calibration source
55Fe (5.97 keV)
Internal calibration source
55Fe (5.97 keV)
Data acquisition system
preamp
Clear PulseCP4026
TechnolandN-TM405
discr.
shaper
HoshinC005
inpu
t reg
iste
r
Q
LAMLAMO
PINVETO
TechnolandN-TM203
delay
fan out
scaler
TechnolandC-TS203
VETO
ch0clock1 kHz
N-TM203
FADC
clock10MHz
clock
in
stop
REPICRPC-081
bipolar3us
LAM
hit pattern
CA
MA
C b
us
live time
wave form
1 Kwords/ch
50us
fan out
fan out
100 sµ
home-made
home-made
16ch • 16 input channels
• Waveform recording:PIN photodiode↘ Charge sens. preamp.↘ Flash ADC
• Offline shaping
• Trigger:shaper + leading edge discr.
• Precise live time
• Control: CAMAC
Sumico results & prospect
3 Phase I — vacuumSumico 1997 run: [S.Moriyama et al., PLB434(1998)147]
gaγ < 6.0× 10−10GeV−1 (ma < 0.03 eV)
3 Phase II — low density 4He (ρHe . 105Pa/298K)Sumico 2000 run: [Y.Inoue et al., PLB536(2002)18]
gaγ < 6.8–10.9× 10−10GeV−1 (0.05 < ma < 0.27 eV)
+ Phase III — high density 4HeSumico 2007–2008 run: [Y.Inoue et al., PLB668(2008)93]
gaγ < 5.6–13.4× 10−10GeV−1 (0.84 < ma < 1.00 eV)
Upgrades are continuing. . .Goal: p . 0.1MPa @ T = 6K →ma . 2 eV
Pioneering axion helioscope[Lazarus et al., PRL69,2333(1992)]
• BNL-Rochester-FNAL
• B = 2.2T, L = 1.8m, fixed dipole magnet
• He gas (0, 50, 100 Torr)
• Proportional chamber (Ar 90% CH4 10%)
• 15 minutes/day (sunset)
• gaγ < 3.6× 10−9GeV−1 for ma < 0.03 eV,
gaγ < 7.7× 10−9GeV−1 for 0.03 eV < ma < 0.11 eV.
cf. Solar age: gaγ < 2.4× 10−9GeV−1
