Tokyo axion helioscope experiment

Tokyo axion helioscope experiment and other axion experiments Y. Inoue International 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. Horie Department of Physics, School of Science, The University of Tokyo Y. Inoue International Center for Elementary Particle Physics, The University of Tokyo A. Yamamoto High Energy Accelerator Research Organization (KEK) Logo designed by Yuki Akimoto Graduate 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: L θ = θ 32π 2 F a µν F aµν, θ = θ + arg det Mq, { θ initial QCD ground state where quark mass matrix (EW scale physics) M q Neutron EDM: d n < 2.9 10 26 e cm ( θ < 10 10 )

Peccei Quinn mechanism Global chiral U(1) PQ + SSB Axion (NG boson) + Making θ into a dynamic parameter which should fall into the potential minimum: θ = θ + arg det M q + a f a Axion mass: z m a = 1 + z f π m π f a V [a] a -πf a 0 πf a θ = 0

The axion couples to two photons: Axion-photon coupling L aγγ = 1 4 g aγaf µν Fµν = g aγ a E B g aγ = α 2πf a [ E N = 1.9 10 10 ( m a 1 ev Model dependent factor: ] 2(4 + z) 3(1 + z) ) [E/N 1.92][GeV 1 ] E/N = 0 (std. KSVZ), 8/3 (GUT DFSZ). E = Tr(Q PQ Q 2 em), N = Tr(Q PQ Q 2 c)

g aγ [GeV -1 ] 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14 10-15 10-16 Microwave cavity Exclusion plot (g aγ m a ) Axion models Laser Crystal solar axion Solar age Axion Helioscope HB stars E/N = 0 (KSVZ) E/N = 8/3 (GUT-DFSZ) 10-6 10-5 10-4 10-3 10-2 10-1 10 0 10 1 m a [ev]

Axion helioscope [P.Sikivie, PRL51,1415(1983)] The sun can be a powerful source of axions. Primakoff process photon axion axion photon Ze L aγγ = g aγ a E B Magnetic Field

Axion helioscope [P.Sikivie, PRL51,1415(1983)] 10 (g aγ /10-10 GeV -1 ) 2 axion flux [10 10 cm -2 s -1 kev -1 ] 8 6 4 2 0 0 2 4 6 8 10 12 Conversion rate: P a γ 1 4 g2 aγb 2 L 2 Sensitivity: g aγ (BL) 1 2 ( bg rate ) 1 8 time area E [kev]

Buffer gas to reach out for heavier axions Conversion rate: P a γ = g2 aγ 2 L 0 Be iqz dz 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 0 0.05 0.1 0.15 0.2 0.25 m a [ev]

Tokyo axion helioscope

Tokyo axion helioscope (Sumico)

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

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 (5K) heat exchanger (40K, 5K) vacuum vessel PIN photodiodes x ray window gas container (5K)

Helium density time chart 600 1 helium density [mol/m 3 ] 550 500 450 400 start 5meV 2007 2008 3days 2nd unmanned tracking end of the 1st unmanned tracking end (encoder broken) Dec Jan Feb Mar Apr quench 0.9 0.8 photon mass [ev]

PIN photodiode X-ray detector Inside OFHC shield @ T = 60 K 16 PIN photodiodes 4 PIN/module chip: Hamamatsu S3590-06-SPL size: 11 11 0.5 mm 3 /PIN active area > 9 9 mm 2 /PIN inactive surface < 0.35µm [T.Namba et al., NIMA489(2002)224] [Y.Akimoto et al., NIMA557(2006)684]

Energy spectrum Upper limit 95% CL (m γ =m a =1.004eV) count rate [10-4 kev -1 s -1 ] 8 7 6 5 4 3 2 1 solar background solar bg [10-4 kev -1 s -1 ] 3 2 1 0-1 -2 fit 0 0 5 10 15 20 E [kev] -3 0 5 10 15 20 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

3 10-9 Exclusion plot [Y.Inoue et al., PLB668(2008)93] Upper limit (95% CL) 2 10-9 g aγ [GeV -1 ] 1 10-9 5 10-10 0.8 0.9 1 m a [ev] 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

10-8 SOLAX, COSME, CDMS Sumico results & prospect Lazarus g aγ [GeV -1 ] 10-9 10-10 DAMA (90%) Sumico CAST Phase I (vacuum) PLB434(1998)147 vacuum Solar age Phase II PLB536(2002)18 4 He 3 He Phase III prospect Phase III latest PLB668(2008)93 HB stars 10-11 E/N = 0 (KSVZ) E/N = 8/3 (GUT-DFSZ) Axion models 10-3 10-2 10-1 10 0 10 1 m a [ev]

Phase III upgrades, troubles & status Introduced a cryogenic rupture disk (Done) Automated gas density control (Done) Sumico 2007 2008 run Reworked He pipelines for quicker evacuation (Done) Thermoacoustic oscillation at higher ρ He Introduced a blind-end bellows at T room section (Resolved) Thermal non-uniformity at higher ρ He Introduced new heat exchangers (Testing) 1st X-ray window got a puncture/crack Repaired by the manifacturer (Test passed) 2nd Spare window broken entirely by thermal stress (Alas!)

Phase III upgrades, troubles & status (gallery) New heat exchangers 1st X-ray window repaired with epoxy Light shinning through the 2nd X-ray window

Other experiments

CAST (CERN Axion Solar Telescope) [K.Zioutas et al., PRL94,121301(2005)] B = 9 T, L = 9.26 m (LHC test magnet) Vertical ±8, horizontal ±40 TPC, Micromegas, CCD X-ray telescope

Sumico & CAST side-by-side Sumico CAST Tokyo CERN 4 T 2.3 m 9 T 9.26 m 12 hours/day 2 1.5 hours/day 4 He @ 5 K (m a 2 ev) 4 He, 3 He @ 1.9 K (m a < 1.1 ev)

CAST result From [J.Galan, arxiv:1102.1406]

Primakoff conversion in a lattice Crystal detectors [R.J.Creswick et al., PLB427(1998)235] axion photon Bragg condition: 2d sin θ = nλ θ θ d SOLAX Ge g aγ < 2.7 10 9 GeV 1 (95%) [A.O.Gattone et al., NPB-PS70(1999)59] COSME Ge [A. Morales et al., Astropart. Phys. 16(2002)325] g aγ < 2.78 10 9 GeV 1 (95%) DAMA NaI(Tl) g aγ < 1.7 10 9 GeV 1 (90%) CDMS Ge g aγ < 2.6 10 9 GeV 1 (95%) [R.Bernabei et al., PLB515(2001)6] [Z.Ahmed et al., PRL103,141802(2009)]

Microwave cavity (axion haloscope) [P.Sikivie, PRL51,1415(1983)] m a hν 1 GHz = 4.14 µev B 0 L aγγ = g aγ ae B hν = γm a, β 2 10 6 Power = g2 aγv B 2 0ρ halo C mode m a min(q cavity, Q halo ) g aγ B 1 0 V 1/2 T 1/2 noise Pioneers: Rochester-BNL-FNAL (RBF), Florida (UF)

ADMX (Axion Dark Matter experiment) [S.J.Asztalos et al., PRL104,041301(2010)] LLNL B 0 = 7.6 T GaAs HFET (T s 2 K) dc SQUID (T s = 47 mk @ 700 MHz) Scanned m a = 1.9 3.53 µev Next upgrade: T cavity 2 K 100 mk http://www.flickr.com/photos/llnl/4305091276

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 atoms 39 K, 85 Rb, etc.; ns np, n = O(100 200) B = 7 T, T cavity = 10 mk Goal: cover m a = 8 30 µev up to g aγ DFSZ prediction. axion selective field ionization detector conversion cavity detection cavity V e g αγγ ion γ e 0 g Rydberg Bext atoms http://www.ltm.kyoto-u.ac.jp/newcarrack/ strong magnetic field laser free from magnetic field [M.Tada et al., arxiv:physics/0101028] electron detector

g aγ [GeV -1 ] 10-6 10-7 10-8 10-9 10-10 10-11 10-12 10-13 10-14 10-15 10-16 ADMX UF+RFB CARRACK goal Exclusion plot Laser SOLAX, COSME, CDMS Sumico CAST Axion models Solar age DAMA Phase I E/N = 0 (KSVZ) E/N = 8/3 (GUT-DFSZ) 10-6 10-5 10-4 10-3 10-2 10-1 10 0 10 1 m a [ev] Lazarus Phase II CAST 4 He CAST 3 He HB stars Phase III latest

Conclusions 2 Fronts of experimental axion searches: Solar axion m a O(eV) Sumico, CAST, crystals Dark matter axion m a O(µeV) ADMX, CARRACK Sumico Phase III Sumico 2007 2008 result: g aγ < 5.6 13.4 10 10 GeV 1 Upgrading toward m a 2 ev (0.84 < m a < 1.00 ev)

Backup

Axion-photon oscillation [Raffelt & Stodolsky, PRD37(1988)1237] Wave equation for (A, A, a) plane wave propagating along the z axis: ω 2 + z 2 m 2 γ 0 0 0 ω 2 + z 2 m 2 γ g aγ Bω 0 g aγ Bω ω + z 2 m 2 a A A a = 0. A a mixing

Notes on buffer gas 4 He is used CAST is using 3 He Temperature is kept high enough above the critical point (p c = 0.227 MPa, T c = 5.1953 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] 3.5 3 2.5 2 1.5 1 0.5 0 safety region 4 He T=6K 0 0.05 0.1 0.15 0.2 0.25 0.3 pressure [MPa] rupture disk X-ray window

Buffer gas container Welded 4 st. steel 304 21.9 17.9 2300 mm 3 square pipes Wrapped with 99.999% pure Al 0.1-mm thick 2 layers Thermal conductivity (measured) 10 2 W/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

55 Fe (5.97 kev) Internal calibration source

55 Fe (5.97 kev) Internal calibration source

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

Sumico results & prospect Phase I vacuum Sumico 1997 run: g aγ < 6.0 10 10 GeV 1 [S.Moriyama et al., PLB434(1998)147] (m a < 0.03 ev) Phase II low density 4 He (ρ He 10 5 Pa/298 K) Sumico 2000 run: [Y.Inoue et al., PLB536(2002)18] g aγ < 6.8 10.9 10 10 GeV 1 (0.05 < m a < 0.27 ev) Phase III high density 4 He Sumico 2007 2008 run: g aγ < 5.6 13.4 10 10 GeV 1 [Y.Inoue et al., PLB668(2008)93] (0.84 < m a < 1.00 ev) Upgrades are continuing... Goal: p 0.1 MPa @ T = 6 K m a 2 ev

BNL-Rochester-FNAL Pioneering axion helioscope [Lazarus et al., PRL69,2333(1992)] B = 2.2 T, L = 1.8 m, fixed dipole magnet He gas (0, 50, 100 Torr) Proportional chamber (Ar 90% CH 4 10%) 15 minutes/day (sunset) g aγ < 3.6 10 9 GeV 1 for m a < 0.03 ev, g aγ < 7.7 10 9 GeV 1 for 0.03 ev < m a < 0.11 ev. cf. Solar age: g aγ < 2.4 10 9 GeV 1