Status report of Latest result from the Tokyo axion helioscope - PowerPoint PPT Presentation

Status report of Latest result from − the Tokyo axion helioscope experiment − − − − − − − − − − − − − Y. Inoue, ICEPP, University of Tokyo M. Minowa, Y. Akimoto, R. Ota, T. Mizumoto, Department of Physics, School of Science, University of Tokyo A. Yamamoto High Energy Accelerator Research Organization (KEK) TAUP2007, 11 September 2007, Sendai

Contents • Solar axion & axion helioscope • Tokyo axion helioscope • Sumico Phase III

Axion What is the Axion? • QCD → θ vacuum → Strong CP problem (eg. neutron EDM) • Peccei–Quinn mechanism: global chiral U(1) + SSB + (1 / 32 π 2 f a ) aF a ˜ → NG boson F a ↓ ↓ axion resolves Strong CP Searches/Limits: • Experiments: Accelerator, Reactor, Nuclear transition, Telescope, Solar axion, Laser, Microwave cavity, .. . • Astrophysics: Solar axion, Red giants, SN1987A • Cosmology: Ω a < 1

Exclusion plot ( g aγ vs m a ) [L.J. Rosenberg, K.A. van Bibber, Phys. Rep. 325(2000)1]

� � Solar axion The sun can be a powerful source of axions. In the solar core, axions can be produced from photons through the Primakoff proccess. K.van Bibber et al. , PRD39(1989)2089 10 /10 -10 GeV -1 ) 2 × ( g a axion flux [10 10 cm -2 s -1 keV -1 ] 8 photon axion 6 4 Ze 2 0 0 2 4 6 8 10 12 E [keV]

Axion telescope [P. Sikivie, Phys. Rev. Lett. 51(1983)1415] The solar axions can be reconverted into x-rays using a strong magnetic field in a laboratory. axion photon photon axion Magnetic Ze Field

Conversion rate Conversion rate: 2 � L � � P a → γ = g 2 = g 2 aγ B 2 sin 2 qL � � aγ Be iqz dz 2 , � � 2 q 2 � � 0 � � q = m 2 a / 2 E. (momentum transfer) � The coherence is lost for m a � πE/L .. . But coherence can be restored by filling the conversion region with buffer gas. In buffer gas, the momentum transfer becomes q = | m 2 γ − m 2 a | / 2 E, � 4 παN e m γ = . (effective photon mass) m e

Sumico V detector refrigerators solar axions superconducting magnet PIN photodiodes vacuum vessel turntable • B = 4 T , L = 2 . 3 m • 268A persistent current gas container • 16 PIN photodiodes • horiz. 360 ◦ , vert. ± 28 ◦

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Past measurements & results • Phase I — vacuum Upper limit (95% CL) 10 -8 m a < 0 . 03 eV 1997 December SOLAX, COSME (Solar-Germanium) [S. Moriyama et al ., Phys. Lett. B 434(1998)147] 10 -9 Solar age • Phase II — low density He ✁ [GeV -1 ] m a < 0 . 27 eV This experiment ( p < 2 kPa , T = 5.2–5.7 K) g a 10 -10 2000 July–September [Y. Inoue, et al ., Phys. Lett. B 536(2002)18] Axion models ( E/N = 8/3) 10 -11 10 -3 10 -2 10 -1 1 10 m a [eV]

✂ CAST @ CERN [Zioutas et al. ,PRL94(2005)121301] -8 10 ) -1 (GeV Lazarus et al. • B = 9 T , L = 9 . 26 m SOLAX, COSME a (LHC test magnet) g DAMA • Vertical ± 8 ◦ , horizontal ± 40 ◦ -9 10 Tokyo helioscope 3 He 4 • TPC, Micromegas, He CCD + mirror -10 10 ] HB stars 0 = CAST phase I N / E [ Z V Axion models CMB limit S K -11 10 -3 -3 -2 -2 -1 -1 10 10 10 10 10 10 1 1 10 10 m (eV) axion [Irastorza et al. , Rencontres de Moriond EW2007] http://moriond.in2p3.fr/EW/2007/

What’s next? — Sumico Phase III • Phase I — vacuum Upper limit (95% CL) m a < 0 . 03 eV 10 -8 1997 December SOLAX, COSME (Solar-Germanium) [S. Moriyama et al ., Phys. Lett. B 434(1998)147] 10 -9 Solar age • Phase II — low density He ✁ [GeV -1 ] Phase II Phase III Phase I m a < 0 . 27 eV Tokyo axion helioscope ( p < 2 kPa , T = 5.2–5.7 K) g a CAST I 10 -10 2000 July–September [Y. Inoue, et al ., Phys. Lett. B 536(2002)18] Axion models • Phase III — high density He ( E/N = 8/3) 10 -11 10 -3 10 -2 10 -1 m a � 2.2–2.6 eV 1 10 m a [eV] ( p � 1–2 atm, T = 5–6 K)

How to resist magnet quench? When the superconducting magnet quenches, its temperature rises up to 50–60 K within a few seconds. • No good commercial cryogenic relief valve • Know thy enemy. Measured the pressure change after a forced quench. 14 12 Pressure [kPa] 10 8 6 4 2 0 0 1000 2000 3000 4000 5000 6000 7000 8000 Time [s] → Not as fast as the magnet: use φ 1/4” tube

And a rupture disk • Hydrodyne • Cryogenic precision burst disc • 36 psi ± 5% @ 5 K • Exhaust through a normally evacuated 3/8” line.

Resonance width at high m a P a → γ = g 2 aγ B 2 sin 2 qL q = | m 2 γ − m 2 2 ; a | / 2 E q 2 • δN He /N He < 0 . 1% stabilize T + control p . p ✄✆☎ P a N He = FWHM=1 meV RT • Many many data points to scan → computer control 1.98 1.985 1.99 1.995 2 2.005 2.01 m a [eV]

Temperature stabilization VXI ADC PC1 5N Al strips Lakeshore Kevlar CGR thermistor insulating support TCP/IP ... ... gas container thermal bridge w/ heater magnet = heat sink DAC PC2

Gas container • Compact design • Welded 4 × st. steel 304 21 . 9 × 17 . 9 × 2300 mm 3 square pipes • Pure Al (99.999%) 0.1-mm thick, × 2 layers • Measured thermal conductivity � 10 − 2 W / K @ 5 K, 4 T

Gas controlling system PCI DAC card +amp PC2 Horiba PV−1000 diaphragm pump piezo valves PV PV TCP/IP exhaust Yokokawa MU101 EIA232 He gas PC1 evacuated line heat exchanger (40K, 5K) vacuum vessel rupture disc x−ray window gas container

Test result of p , T control p ∼ 15 kPa, T = 5.75 K temperature 15.15 pressure 15.1 15.05 15 temperature[K] pressure[kPa] 5.76 14.95 14.9 14.85 5.755 14.8 5.75 5.745 0 10000 20000 30000 40000 50000 time[s] Excellent!

Other progress / status • PIN diode dead layer measurement • Moved to a new site .. . again • Recontruction — almost finished, left final precision alignment • True north direction by gyrocompass • Repaired and refined mechanics of altazimuth stage • Cable handling robot — work in progress, half done • Repairing broken cables — work in progress

Summary • Sumico Phase III will explorer m a � 2.2–2.6 eV • Most technical difficulties have been overcome. • Now the magnet has been cooled. T mag = 6 K as of 10 September • Measurement will start soon.