Tokyo axion helioscope

Transcription

1 Tokyo axion helioscope Y. Inoue International Center for Elementary Particle Physics, University of Tokyo COSMO/CosPA2010, 30 September 2010, Hongo, U. Tokyo

2 Collaborators M. Minowa, R. Ohta, T. Mizumoto, T. Horie Department of Physics, School of Science, University of Tokyo Y. Inoue International Center for Elementary Particle Physics, University of Tokyo A. Yamamoto High Energy Accelerator Research Organization (KEK) Logo designed by Yuki Akimoto

3 Strong CP problem: CP violating term in QCD L C P = θ 32π 2 F a µν What is the Axion? F aµν ( θ O(π)?) Neutron EDM: d n < e cm ( θ < ) Peccei Quinn mechanism: U(1) PQ + SSB Axion θ = a f a = 0. (NG boson)

4 Principle of Axion helioscope [P. Sikivie, Phys. Rev. Lett. 51(1983)1415] photon axion axion photon Ze L aγγ = g aγ a E B Magnetic Field

5 Principle of Axion helioscope [P. Sikivie, Phys. Rev. Lett. 51(1983)1415] axion flux [10 10 cm -2 s -1 kev -1 ] (g aγ /10-10 GeV -1 ) 2 Conversion rate: P a γ = 1 2 g2 aγ L 1 4 g2 aγb 2 L 2 0 Beiqz dz E [kev] q = k γ k a

6 p side mark for pdfwrite

7 Sumico V detector B = 4 T, L = 2.3 m 268A persistent current 16 PIN photodiodes Track the sun 12 hours/day

8 Sensitive to heavier axions by buffer gas Conversion rate: P a γ = g2 aγ 2 L 0 Be iqz dz 2 g2 aγb 2 q 2 sin 2 ql 2 g2 aγb 2 L 2, 4 q = k γ k a m2 γ m 2 a 2E In vacuum, coherence is lost for m a πe/l.... The effective photon mass in buffer gas: vacuum with buffer gas m γ = 4παNe m e. N e : electron density P a γ m a [ev]

9 Buffer gas container X-ray window (detector side) Ensure temperature uniformity along the container by: Suspending container body in vacuum Thermal contact at one end Active temperature control High thermal conductivity layer

10 Buffer gas container Welded 4 st. steel mm 3 square pipes Wrapped with % pure Al 0.1-mm thick 2 layers Thermal conductivity (measured) K, 4 T

11 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

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

13 Helium density time chart helium density [mol/m 3 ] start 5meV days 2nd unmanned tracking end of the 1st unmanned tracking end (encoder broken) Dec Jan Feb Mar Apr quench photon mass [ev]

14 PIN photodiode X-ray detector Inside OFHC T = 60 K 16 PIN photodiodes 4 PIN/module chip: Hamamatsu S SPL size: mm 3 /PIN active area > 9 9 mm 2 /PIN inactive surface < 0.35µm [T. Namba et al., NIMA 489(220)224] [Y. Akimoto et al., NIMA557(2006)684]

15 Data acquisition system PIN preamp home-made Clear Pulse CP4026 fan out fan out shaper Technoland N-TM405 bipolar 3us Technoland N-TM203 delay 50us N-TM203 clock 10MHz clock discr. 1 khz home-made VETO 16ch LAMO fan out Hoshin C005 input register LAM Q Technoland C-TS203 VETO ch0 scaler LAM hit pattern live time CAMAC bus 16 input channels Waveform recording: PIN photodiode Charge sens. preamp. Flash ADC Offline shaping Trigger: shaper + leading edge discr. in stop FADC clock REPIC RPC-081 wave form 1 Kwords/ch Precise live time Control: CAMAC 100 µ s

16 10-8 Lazarus et al. PRL69(1992)2333 SOLAX, COSME, CDMS Exclusion plots DAMA g aγ [GeV -1 ] Solar age Sumico (95%CL) Phase I vacuum PLB434(1998)147 CAST I PRL94(2005) Phase II low density PLB536(2002)18 CAST II 4 He JCAP0902:008,2009 CAST II 3 He preliminary Phase III latest PLB668(2008)93 Axion models (E/N = 8/3) m a [ev]

17 Sumico & CAST side-by-side Sumico CAST Hongo, U. Tokyo CERN 4 T K 9 T K 12 hours/day hours/day 4 He (m a 2 ev) 4 He+ 3 He (m a < 1.1 ev)

18 10-8 Lazarus et al. PRL69(1992)2333 SOLAX, COSME, CDMS Exclusion plots DAMA g aγ [GeV -1 ] Solar age Sumico (95%CL) Phase I vacuum PLB434(1998)147 CAST I PRL94(2005) Phase II low density PLB536(2002)18 CAST II 4 He JCAP0902:008,2009 CAST II 3 He preliminary Phase III latest PLB668(2008)93 Axion models (E/N = 8/3) m a [ev]

19 10-8 Lazarus et al. PRL69(1992)2333 SOLAX, COSME, CDMS Exclusion plots g aγ [GeV -1 ] Solar age Sumico (95%CL) Phase I vacuum PLB434(1998)147 CAST I PRL94(2005) DAMA Phase II low density PLB536(2002) CAST II 4 He JCAP0902:008,2009 CAST II 3 He preliminary Phase III latest PLB668(2008) Axion models (E/N = 8/3) m a [ev]

20 10-8 SOLAX, COSME, CDMS Future plan Lazarus et al. DAMA 10-9 Solar age Sumico (95%CL) Phase III prospect g aγ [GeV -1 ] Phase I vacuum CAST I Phase II low density CAST II 4 He Phase III latest CAST II 3 He preliminary Axion models (E/N = 8/3) ( ) 1/8 bg rate 10-3 gaγ limit 10-2 (BL) 1/ time area m a [ev]

21 Sumico Phase III upgrades Gas density control has been quit successful so far. We want to make 4 He density higher and higher! But higher density caused new problems... Reworked internal and external pipelines for safer operation. But a thermoacoustic oscillation set in at higher densities. Introduced a fast pressure gauge to monitor oscillation and bellows in the room temperature section. Unacceptable elevation-angle dependent temperature difference observed at higher densities. Introduced new heat exchangers. (Now testing)

22 Sumico Phase III upgrades 100 tail-to-head T [mk] New heat exchangers time [s] T

23 Summary Sumico, aka Tokyo axion helioscope, results: Phase I: vacuum g aγ < GeV 1, Phase II: low density 4 He g aγ < GeV 1, Phase III: cold dense 4 He g aγ < GeV 1, m a < 0.03 ev 0.05 < m a < 0.27 ev 0.84 < m a < 1.00 ev Sumico Phase III will explorer further up to m a 2 ev. Now started cooling!

24 Thank you

25 Helium-4 is used Notes on buffer gas Temperature is kept high enough above the critical point (p c = MPa, T c = K) X-ray absorption and decoherence due to gravity are not fatal even at m γ 2 ev m γ = 4παNe m e effective photon mass [ev] safety region 4 He T=6K pressure [MPa] rupture disk X-ray window

26 Resonance width at higher axion masses P a γ = g2 aγb 2 q 2 sin 2 ql 2 ; q m2 γ m 2 a 2E ql < 2π δn e N e < 4πE m 2 al O(10 3 ) ; m 2 γ = 4παN e m e for m a 2 ev. P a γ FWHM=1 mev stabilize T + control p. N He p RT Many data points to scan computer control m a [ev]

27 After quench, before explosion... When the superconducting magnet quenches, its temperature rises up to K within a few seconds. Pressure change is slower: 3 in 2 minutes 7 in 2 hours pipe line design pressure [kpa] time [s]

28 Pressure change after quench on Apr pressure [kpa] :20 12:25 12:30 12:35 12:40 12:45 12:50 12:55 13:00 Apr JST

29 Cryogenic rupture disk Hydrodyne cryogenic precision burst disc Protects X-ray window from over pressure Breaks at K

30 Energy spectrum Upper limit 95% CL (m γ =m a =1.004eV) count rate [10-4 kev -1 s -1 ] solar background count rate [10-4 kev -1 s -1 ] fit E [kev] E [kev] χ 2 (m a ) = m X γ,max m γ =m γ,min 20X kev E=4 kev» Nsolar (E, m γ ) N bg (E, m γ ) N theo (E, q) σ(e, m γ ) 2