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Search for Solar Axions with the CAST experiment

Search for Solar Axions with the CAST experiment. J. Galán on behalf of the CAST Collaboration University of Zaragoza (Spain). 8/Oct/2009 J.Galán 11th ICATPP Como, Italy. The CAST Collaboration. Canada Universiy of British Columbia, Department of Physics , Vancouver M. Hasinoff

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Search for Solar Axions with the CAST experiment

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  1. Search for Solar Axions with the CAST experiment J. Galán on behalf of the CAST Collaboration University of Zaragoza (Spain) 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  2. The CAST Collaboration Canada Universiy of British Columbia, Department of Physics, Vancouver M. Hasinoff Croatia RudjerBoskovicInstitute, Zagreb RudjerBoskovic, M. Krcmar, B. Lakic, A. Ljubicic France DAPNIA, CEA-Saclay, Gif-sur-Yvette S. Aune, E. Ferrer-Ribas, I. Giomataris, T. Papaevangelou Germany TU Darmstadt, InstitutfürKernphysik D. H. H. Hoffmann, M.Kuster, A. Nordt GSI Darmstadt D. H. H. Hoffman Universität Frankfurt, InstitutfürAngewandtePhysik, Frankfurt J. Jacoby UniversitätFreiburg H. Fischer, J. Franz, F.H. Heinsus, D. Kang, K. Königsmann, J. Vogel MPE Garching H.Bräuninger, M. Kuster, A. Nordt WHI München R. Kotthaus, G. Lutz, G. Raffelt, P. Serpico Greece University of Patras A. Gardikiotis,Y. Semertzidis, M.Tsagri, K. Zioutas • National Center forScientificResearch “Demokritos”, Athens • T. Karageorgoplou, G. Fanourakis, T. Geralis, K. Kousouris • AristotleUniversity of Thessaloniki • C. Eleftheriadis, A. Liolios, I. Savvidis, T. Vafeiadis • Hellenic Open University, Patras • C. Bourlis, S. Tzamarias • Russia • RussianAcademy of Science, Institutefor Nuclear Research (INR), • Moscow • Belov, S. Gninenko • Spain • University of Zaragoza • B. Beltrán, J. Carmona, S. Cebrián, T. Dafni, J. Galán, H. Gómez, • I.G. Irastorza, G.Luzón, A. Morales, J. Morales, A. Ortiz, A. Rodríguez, • J.Ruz, A. Tomás, J. Villar • Turkey • DogusUniversity, Istambul • E. Arik, S.Boydag, S.A. Cetin, O.B. Dogan, I. Hikmet, C. Yildiz • USA • Lawrence LivermoreNationallaboratory, Livermore, CA • M. Pivovaroff, R. Soufli, K. van Bibber • University of Chicago, Enrico Fermi Institute and KICP • J. Collar, D. Miller • Switzerland • EuropeanOrganizationfor Nuclear Research (CERN), Genève • D.Autiero, K. Barth, S. Borgui, M. Davenport, L. Di Lella, N. Elias, • C. Lasseur, T. Ninikowski, A. Palacci, H.Riege, L. Stewart, L. Walkiers 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  3. Outline • IntroducingtheAxion and Solar AxionModel. • ReviewtheAxiondetectiontechniques. • The CAST HelioscopeDescription. • CAST Status (resultsfrom 4He Phase and progressin 3He Phase). • The new He3 System and detector performances • Future of HelioscopeAxionSearches. 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  4. Why do we need Axions? QCD predicts violation of CP in strong interactions Bad agreement between theoretical and experimental values for the electric dipole moment of neutron All you need is Axions! Peccei-Quinn introduced the axion field to solve this problem 4 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  5. What are the Axion properties? The theory predicts one unique parameter (scale factor) to describe the axion. Mass depends on this parameter and it needs to be determined experimentally. • Neutral pseudoscalar • Practically stable • Very low mass • Very low cross-section • Coupling to photons If the axion mass is small enough could contribute to the content of Cold Dark Matter of the Universe. 5 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  6. Direct Axion Detection Techniques (I) Bragg Difraction Geomagnetic Axion Conversion Microwave Cavity Searches Davoudiasl & Huber, hep-ph/0509293 Axions can convert to photons in Earth’s magnetic field Idea is to observe the Sun through the Earth e.g. Asztalos et al., Phys. Rev. D 69, 011101(2004) [astro-ph/0310042] 6 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  7. Direct Axion Detection Techniques (II) Laser experiments Telescope Searches Light Shining Through Wall Vacuum properties e.g. Grin et al. 2006 astro-ph/0611502v1 Helioscope Searches Inoue et al. 2002 astro-ph/0204388v1 Lazarus et al. Phys. Rev. Lett. 69 2333 (1992) 7 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  8. Production: The Solar Axion Spectrum Axions should be produced in the core of the Sun. The well known Solar Model is used to calculate the expected axion flux in Earth 8 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  9. Detection: The Probability Conversion L = magnet lenght, Γ = absorption coefficient Expected Number of counts Assuming : events/day 9 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  10. The Experimental Axion Signature On resonance Off Resonance ∆m = 2 meV Off Resonance ∆m = 7 meV Off Resonance ∆m = 11 meV 10 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  11. The Experimental Axion Signature On resonance Off Resonance ∆m = 2 meV Signaturetoidentifyanaxionsignal. And a wayto determine theaxionmassin a vacuumphase. Off Resonance ∆m = 7 meV Off Resonance ∆m = 11 meV 11 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  12. CAST Location 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  13. The CAST Helioscope LHC dipole: L = 9.3m, B = 9T Solar Tracking : 3.5 h/day, background data rest of the day Signal : excess of x-rays while pointing the Sun 4 x-ray detectors 13 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  14. Tracking System Precision GRID Measurements Sun Filming • Horizontal and Vertical encoders define the magnet orientation • Correlation between H/V encoders has been established for a number of points (GRID points) • Periodically checked with geometer measurements • Twice a year (March – September) • Direct optical check. Corrected for optical refraction • Verify that the dynamic Magnet Pointing precision (~ 1 arcmin) is with our aceptance CAST magnet is tracking the Sun with the required precision. 14 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  15. CAST Status and progress CAST Phase I (Vacuum) •ma<0.02eV •Completed(2003-2004) •PRL94(2005)121301 •JCAP04(2007)020 •P< 13.4mbar, 160steps •0.02<ma<0.39eV •Completed(2005-2006) •JCAP02(2009)008 CAST Phase II (4He) •P< 120 mbar •0.39<ma<1.16eV •Started in Nov 2007 •Willcontinueto Dec2010 CAST Phase II (3He) LowEnergy Solar Axions •2 weeks data in 2008 (2-4eV) •few eVup to 1keV range 15 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  16. CAST Status and progress CAST Phase I (Vacuum) •ma<0.02eV •Completed(2003-2004) •PRL94(2005)121301 •JCAP04(2007)020 •P< 13.4mbar, 160steps •0.02<ma<0.39eV •Completed(2005-2006) •JCAP02(2009)008 CAST Phase II (4He) •P< 120 mbar •0.39<ma<1.16eV •Started in Nov 2007 •Willcontinueto Dec2010 CAST Phase II (3He) CAST continuestaking data and measuringwithsensitivityforaxionmassesabove 0.75eV LowEnergy Solar Axions •2 weeks data in 2008 (2-4eV) •few eVup to 1keV range Today -> Pstep : 564 16 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  17. The 3He System Upgrade: The metering volumes • 4He gas saturates at ~16 mbar for T=1.8 K, for higher pressures only 3He remains gas •Controlled injection of He in the bores. Order of 1000 pressure steps required •Precise measurement of gas quantity •Precise monitoring of gas pressure and temperature •High reproducibility precision (back and forward) •Extra safety for 3He loss 17 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  18. The 3He System : Expansion volume The new 3He System is prepared to protect the thin Cold windows in case of Magnet Quench. 18 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  19. The 3He System : Expansion volume The new 3He System is prepared to protect the thin Cold windows in case of Magnet Quench. Refilling must be done as fast as posible to dont loss data taking efficiency. 19 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  20. 3He Control, Monitoring and Recovery System 20 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  21. Daily Data Taking Protocol • Detectors data is analysed daily and sent by mail to the CAST collaboration. • A protocol takes into account the background level of the detectors. • All the information from the 4 detectors taking data in CAST is taken into account The protocol allows us to decide if we should continue measuring in the same pressure step. In such way, we avoid to skip a signal that is close to the sensitivity limit of the experiment. 21 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  22. Detectors Systems (4He Phase) • 2) X-ray Telescope coupled to pnCCD • pn CCD chip • Pixels 150μm x 150μm • ExcellentEnergy resol. • X-rayfingerautomatedcalibration • ABRIXAS space X-raytelescope • 27 nestedmirrorcells. • Magnet bore size (42.5 mm) • pnCCDFocusfrom • d=43mm to d=3mm Improved signal/noise by a factor of up ~200 Background in Signal Region: 0.18cts/h (1-7keV) 22 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  23. Detectors Systems (4He Phase) 2) Micromegas X-ray detector (sunrise) • 2) Micromegas X-ray detector (sunrise side) • Position sensitive (x-y) • Precision ~ 70μm • Lowbackground • Verystable • Background: 25cts/h(2-10keV) • (for the full magnet bore) • 3) TPC detector (sunset both bores) • Position sensitive • Properhielding • Background: 85cts/h(2-12keV) • (for the both magnet bores) 3) TPC detector (sunset both bores) 23 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  24. Detectors Data (4He Phase) TPC Mean background versus Tracking Spectrum CCD Hitmap Integrated background and Tracking + 1 day tracking Micromegas Mean Background Rate + Trackings 24 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  25. Detector Systems (2008) • New Sunrise Micromegas Detection Line • New vacuum detection line holding space for focussing device installed in 2007. • Implemented frontal calibration system. • Implemented new shielding (Cupper, Lead, Cadmium, Plexiglass and Polyethylene. • Improved control and monitoring of detector gas system and improved vacuum. • Clean Nitrogen flux surrounding the detector inside the inner shielding. 25 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  26. Detector Systems (2008) • New Sunset Micromegas Detectors • 2 new Micromegas detectors installed in Sunset side replacing the previous TPC. • Background level reduced by more than a factor 20 due to discrimination capabilities from micromegas detectors versus TPC detector. • System redesigned and vacuum improvements achieved. • Calibration is taken daily from the detectors back. Some work already schedulled for implementing frontal calibrators. 26 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  27. CAST Frame Store CCD (fall 2009) • Better low energy response: • 0.2 keV < E < 1 keV • Lower background (built of radio pure materials) • Better energy resolution (<160eV(FWHM) @ 6keV) • Mechanical design, cooling system (CERN: engineers, Cryolab) Imaging area 256 x 256 Pixels 75 x 75 μm2 1.92 x 1.92 cm2 27 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  28. Prospects for the post-CAST era Experience gathered during last years running with the improved detectors systems and the latests and expected new technology in the coming years could push the limits in axion searches even lower. Sensitivity Estimator 29 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  29. Conclusions • CAST has published (JCAP02(2009)008, arXiv:0810.4482v2 [hep-ex])the best laboratory limit for the mass range 0.02eV-0.39eV, with 4He as buffer gas inside the magnet bores. • Since 2008 CAST has been collecting data with 3He in the magnet bores. • 2010: CAST should be able to fulfil its program • In parallel, we are developing the low energy (visible) axion program • High sensitivity detectors may lead to great improvements in mass region up to 0.02 eV (Vaccuum) 30 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

  30. Backup Slides

  31. MICROMEGAS Ultralow Background Periods • Observed periods of very low background in micromegas detectors. • Several improvements: • New designed shielding. • New micromegas detectors made of low radiactivity materials. • More sofisticated statistical analysis. • Still not well understood nature background could be dominated by: • Radon • Compton scattering (not signal like in 85-90% of the cases) • Ectons ( explosive electron emission ) • Work in progress for understanding the low background nature. • Full simulation process chain. • Underground Laboratory controlled measurements. 28 8/Oct/2009 J.Galán 11th ICATPP Como, Italy

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