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Tokyo Axion Helioscopeaka Sumico
MINOWA, Makoto
Department of Physicsand
RESCEUThe University of Tokyo
2011-04-12 ASK2011
Collaborators
University of TokyoM. MINOWA
Y. InoueY. Akimoto
R. OhtaT. Mizumoto
KEKA. Yamamoto
Solar axion detection – the principle
The proposal by K. van Bibber et al.
Hadronic axion window was open ma = O(1 eV)
The first experiment by Lazarus et al.
A small accelerator magnet fixed on the floor
Solar axion, principle of the detection
4
2sin
222
2
LBg
qLqBg
p
a
aa
γ γ
γ γγ
=
=→
2/1
22
)(4
2
=
−=
e
e
a
mzNm
mmq
π α
ω
γ
γ
Tokyo Axion Helioscope aka Sumicofirst result in 1997
● No Liq. He● B=4T, L=2.3m● 268A persistent current● 16 PIN photodiodes● Altazimuth: Horiz. 360°, vert. ±28°
Tokyo axion helioscope - a start upmake it as simple as possible
because of limited budget
● Dedicated superconducting dipole magnet✔ Designed by A. Ymamaoto(KEK)
● Computer controled altazimuth● Buffer gas for non-zero mass axions● Pressure-resistant X-ray window● X-ray detector in vacuum and low temperature
Details of the HelioscopeSuperconducting magnet and refrigerators
2x Gifford-McMahon refrigerators, no liq. helium T=5 – 6K268 A persistent
current for B=4TEasy trackingUnmanned operation
altazimath mount
● 2 servomotors and 2 rotary encoders for altitude and azimuth
● Horiz. 360°, vert. ±28°● NOVAS-C program for the tracking
Helium-4 does not liquefy @1atm, 6K.
2/1
22
)(4
2
=
−=
e
e
a
mzNm
mmq
π α
ω
γ
γ
4
2sin
222
2
LBg
qLqBg
p
a
aa
γ γ
γ γγ
=
=→
Buffer gas for non-zero mass axions
Sensitivity width
4
2sin
222
2
LBg
qLqBg
p
a
aa
γ γ
γ γγ
=
=→
2/1
22
)(4
2
=
−=
e
e
a
mzNm
mmq
π α
ω
γ
γ
gas handlig system
pressure setting with piezo valves
T=5.75K
∆mγ = 2 meV
rupture disk to survive quenching
● When the superconducting magnet quenches, the temperature rises up to 50 – 60K within a few seconds.● Pressure change is, however, rather slow.● A rupture disk is added.● It breaks at P = 0.248 Mpa before X-ray window explodes.
Buffer gas container
● Container wrapped with hi-thermal conductivity 99.999%-pure Al sheet● Thermal contact only at one end.
➔ Uniform temperature along the container● X-ray window on one end
Pressure-resistant X-ray windowto separate
5 - 6K magnet and PIN diodes
● 25μm-thick Be with 1μm-thick polyimide coating and Ni frames● withstands 0.3 Mpa● Transmissivity 81.4% @2.98 keV
● 16 x Hamamatsu S3590-06-SPL● High efficiency with 0.5 mm thickness● Only 0.35μm inactive surface layer● Cold operation at T=60K anchored at the radiation Shield● Background 6x10-5 cts/s/keV/cm2
X-ray detector in vacuum and low temperature
calibration system with 55Fe55Fe
DAQ
● Waveform recording
● Offline shaping
Search results – exclusion plots
1992
1997 2000
2004
2008
2009
Y. Inoue et al., Phys. Lett. B 668 (2008) 93
Sumico vs. CASTto scale
Sumico vs. CAST
BL 4T x 2.3m 9T x 9.26mT 5 - 6 K 1.8 Kbuffer gas helium-4 helium-4 and -3cooling refrigerator liq. heliumswing (360°), ±28° 100°, ±8°detectors PIN photodiodes many kindsrunning cost ~20kW (¥10k/d) don't know# institutes 2 17# collab. 6 61size \small \Huge
Denser gas might make problems
X-ray absorption decreases the conversion prob.Gravity deforms the probability curve.Sumico is still OK with ma=2eV.
Limitation and Hope
Smaller BL cannot be compensated by any other factors.
→ CAST wins
X-ray absorption and decoherence due to gravity arenot fatal in helium-4 buffer gas even with m
γ=2 eV.
→ Sumico might survive in 1 < ma < 2 eV.
2/12/14/18/18/1 −−−−∝ LBATNgaγ γlimit N : background rate
T : running time A : detector area
Hidden photon search a by-product
Hidden photon search – a by-product
• Extensions of the Standard Model:– Additional U(1) gauge
symmetry• Mixing with a photon
Ref: S. N. Gninenko et al., Phys. Lett.B 664 (2008) 180
µ νµ νχ BFL
21
int −=
No magnetic field is required
)mfor (2
)2
(sin4)(
222
22
ωω
ωω
χω
γγ
γ
γγ
< <≈−−=∆
∆=
′′
′
→′
mmq
lqP
Hidden photon detection unit
● PMT with Low-dark-noise < 5 Hz● Low-cost parabolic mirror for a searchlight
Parabolic mirrororiginally designed for a searchlight
diam.=500mmf=1007mmFocul spot 1.5mm
Photon counting PMT
Hamamatsu R3550Pdiam.=25mmDark noise: 4 - 5 Hz at room temperature
Piggyback on Sumico
Prospect
J. Redondo, 6th Patras Workshop(2010)
Costs Sumico(1995)● Magnet 50 MJPY incl. cylinder+cryogenics● Altazimuth 4 MJPY● DAQ 5 MJPY● PIN diodes 1 MJPY● X-ray window 4 MJPY● Buffer container 1 MJPY● Misc. 5 MJPY
Hidden photon unit(2010)● Cylinder 2 MJPY● Mirror 1 MJPY● Misc. 1 MJPY
1 MJPY = 13 MKRW1 MJPY = 12 KUSD
Photo gallery
終わり
Fin
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