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The CAST Experiment at CERN Search for Solar Axions: the CAST experiment at CERN http://www.cern.ch/cast The XXXIXth Rencontres de Moriond Thomas Papaevangelou CERN for the CAST Collaboration March 2004, La Thuile Outline: -Axions -Principles & Fulfillment -CAST : Description -Magnet,platform,cryogenics,tracking -X-Ray Telescope & X-Ray Detectors -Preliminary Results Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Axions α The STRONG CP PROBLEM CP-violating term in QCD lagrangian: ( ) Experimental consecuence: prediction of electric dipole moment for the neutron: (A = 0.04 – 2.0) BUT experiment says... So, Why so small? Peccei-Quinn (1977) propose an elegant solution to this problem. θ not anymore a constant, but a field Æ the axion a(x). Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Axions α The STRONG CP PROBLEM: Peccei-Quinn solution •New U(1) symmetry introduced in the SM: Peccei Quinn symmetry of scale fa •The AXION appears as the Nambu-Goldstone boson of the spontaneous breaking of the PQ symmetry θ absorbed in the definition of a •a Æ qq transitions axion – gluon •a – π0 mixing vertex •axion mass > 0 PQ Symmetry: Peccei & Quinn: CP invariance of the strong interactions expected in QCD, for a non vanishing scalar field that gives mass to a fermion through a Yukawa coupling. Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Axions α pseudoscalar neutral practically stable phenomenology driven by the breaking scale fa and the specific axion model Couples to photon Lαγ = gαγ (E•B)a Primakoff (1951) [π°→γγ] PRIMAKOFF EFFECT Any scalar or pseudoscalar particles: axion-like particles Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Axions α PRIMAKOFF EFFECT Stellar interior → the Sun!! Solar Axions Flux at the Earth [K.van Bibber et al.,1989] Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Axions α Transverse magnetic field (B) X-ray X-ray detector L Signal: X-rays while tracking (magnet pointing to the Sun) over background To preserve Coherence: |M|2 = 1 |M|2 = 2(1-cosqL)/(qL)2 Lazarus et al., Brookhaven -2 mα < 10 eV Tokyo Helioscope:B~4T, L~2m Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Axions α Extending the coherence to higher axion masses... •Coherence for higher masses by using buffer gas. •Fill magnetic channels with helium •The photon acquires an effective mass: mγ > 0 •Momentum transfer is (as opposed to ) •Coherence condition (qL<< 1) is recovered for a narrow mass range around mγ •mγ can be adjusted by changing the gas pressure: •Thus, changing the pressure of the gas will allow to be sensitive to an extended range of higher axion masses Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Prospects CAST Sensitivity plot Phase II and up (?) Filling the magnet bores with helium the photon acquires an effective mass: mγ > 0 and by changing the gas pressure we are sensitive to different masses mα < 1 eV To Start in 2005 Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 The Collaboration Canada Vancouver, University of British Columbia, Department of Physics Greece, Thessaloniki Aristotle University of Thessaloníki Michael HASINOFF Spyridon DEDOUSSIS, Christos ELEFTHERIADIS, Anastasios Croatia, Zagreb LIOLIOS, Argyrios NIKOLAIDIS, Ilias SAVVIDIS, Konstantin Ruder Boskovic Institute ZIOUTAS Milica KRCMAR, Biljana LAKIC , Ante LJUBICIC Italy, Pisa Scuola Normale Superiore (SNS) France, Gif-Sur-Yvette Luigi DI LELLA Centre d'Etudes de Saclay (CEA-Saclay), DAPNIA Russia, Moskva Samuel ANDRIAMONJE,Stephan AUNE ,Alain DELBART, Esther Russian Academy of Sciences, Institute for Nuclear FERRER, Ioanis GIOMATARIS, Emile PASQUETTO, Jean Pierre Research (INR) ROBERT Alexandre BELOV, Sergei GNINENKO, Nikolai GOLOUBEV Germany, Darmstadt Spain, Zaragoza Technische Universitat Darmstadt, Institut für Kernphysik Universidad de Zaragoza, Facultad de Ciencias, Instituto de Theopisti DAFNI, Dieter HOFFMANN, Manfred MUTTERER Física Nuclear y Altas Energías Germany, Frankfurt Berta BELTRAN, Jose CARMONA, Susana CEBRIAN, Gloria Applied Physics LUZON, Angel MORALES, Julio MORALES, Alfonso ORTIZ DE Vladimir ARSOV, Joachim JACOBY SOLORZANO, Jaime RUZ, Maria SARSA, Jose VILLAR Germany, Freiburg Switzerland, Geneve Albert-Ludwigs-Universität Freiburg European Organization for Nuclear Research (CERN) Klaus BARTH, Enrico CHESI, Gino CIPOLLA, Martyn Horst FISCHER, Juergen FRANZ , Fritz Hertbert HEINSIUS, DAVENPORT, Michel DELATTRE, Rui DE OLIVEIRA, Fabio Donghwa KANG, Kay KÖNIGSMANN, Christian SCHILL FORMENTI, Igor IRASTORZA, Jean-Noel JOUX, Christian Germany, Garching LASSEUR, Angelika LIPPITSCH, Thomas PAPAEVANGELOU, Max-Planck-Gesellschaft (MPG), Max-Planck-Institut für Alfredo PLACCI, Laura STEWART, Bruno VULLIERME, Louis Extraterrestrische Physik WALCKIERS Heinrich BRAUNINGER, Jakob ENGLHAUSER , Markus KUSTER United States of America, Chicago, Il Germany, Muenchen University of Chicago, Enrico Fermi Institute Max-Planck-Institut für Physik, Werner-Heisenberg-Institut Taylor AUNE, Juan COLLAR, Joaquin VIEIRA Rainer KOTTHAUS, Gerhard LUTZ, Georg RAFFELT United States of America, Columbia, Sc Greece, Athens University of South Carolina, Department of Physics and National Center for Scientific Research "Demokritos" (NRCPS) Astronomy George FANOURAKIS, Theodoros GERALIS, Katerina Frank AVIGNONE, Richard CRESWICK, Horacio FARACH ZACHARIADOU,Kostas KOUSOURIS Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 CERN Axion Solar Telescope Sunset Photon detectors Sunrise Photon detectors Sunrise axions Sunset axions DecomissionedDecomissioned LCH LCH test test magnet magnet RotatingRotating platform platform 33 X-ray X-ray detectors detectors X-rayX-ray Focusing Focusing Device Device Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 CAST is here: LEP Point 8 (former DELPHI point) Building 2875 Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Magnet,platform,cryogenics L= 10 m B=9 T CAST Experimental area Æ100 times better α→γ conversion efficiency SR8 than any other !! 4He flexible line Magnet Feed Box Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Magnet,platform,cryogenics Moving platform: alignment with the Sun for ~1200 hours per year MagnetMagnet atat -8°-8° MagnetMagnet atat +8°+8° Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Magnet,platform,cryogenics Tracking system •Motors •Encoders •E. ReadoutÆ computer •Software with astronomical calculations •Interface to move magnet •New high precision angle encoders! •Calibrated and correlated with celestial coordinatesÆ high precision geometer measurement Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Magnet,platform,cryogenics Looking at the sunrise… MARCH’03 TwiceTwice aa yearyear (September&March)(September&March) wewe cancan filmfilm thethe SunSun throughthrough thethe windowwindow SEPTEMBER’03 Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Magnet,platform,cryogenics Slow Control system Pressure, load & temperature logging Continuous status monitoring (valves, detector gas, various alarms) Mail and GSM notification On-line plots & history recall utilities. For: ¾ Smooth & safe operation ¾ Data analysis Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 X-Ray Telescope & X-Ray Detectors: (Detectors (CCD (TPC (Micromegas (X-Ray Telescope (Focusing Device) 9Big value of (LB)2 9Low background rate detectors X-Ray Telescope!!! Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 The X-Ray Telescope Telescope-Magnet Alignment Space technology: Spare part of the ABRIXAS Space mission Telescope on the Magnet with the CCD in place Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 The X-Ray Telescope ~35% efficiency due to reflections 3mm ∅ 1.7 m (27 nested pairs of mirrors (From 50mm∅(LHC magnet aperture) to ~3mm∅ 6 segments Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 CCD (Excellent Energy Resolution 55Fe 5.9keV lines K,L < 0.5 keV (Excellent Space Resolution Pixel size: 150µm x 150µm Surface : 1x3 cm2 Optimum working temperature:-130°C (Background: ~10-4 events keV-1 s-1cm-2 (Efficiency close to 100% over the full energy range (works in vacuum without window) Constrained only by the telescope Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Micromegas CAST Prototype: x-y structure: 192 charge collection strips for x 192 charge collection strips for y Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Micromegas Charge_run_1991 55 Entries 29421 Calibration Fe Integral 8.74167 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 0 10000 20000 30000 40000 50000 60000 70000 [ADC counts] Background rate: <10-4 events keV-1s-1cm-2 Plot with data from PANTER X-rayEfficiency conversion of the micromegas for 90% strongback efficiency transparency (X-Ray detection 0.8 0.7 Efficiency
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