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