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
Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 [K.van Bibber et al.,1989] 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 2 = 1 Coherence |M|2 = 2(1-cosqL)/(qL)2 Lazarus et al., Brookhaven : |M| -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 reco γ ) •mγ can be adjusted by changing the gas pressure:
vered for a narrow mass range around m •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 heliumchanging the the photon gas pressure acquires anwe are sensitive to different effective mass: mγ > 0 and by 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 Michael HASINOFF
Croatia, Zagreb Ruder Boskovic Institute
Milica KRCMAR, Biljana LAKIC , Ante LJUBICIC
France, Gif-Sur-Yvette Centre d'Etudes de Saclay (CEA-Saclay)
Samuel ANDRIAMONJE,Stephan AUN Greece,Spain, Zaragoza Thessaloniki FERRER, Ioanis GIOMATARIS, Emile PASQUETTO, Jean Pierre AristotleUniversidad University de Zaragoza,, Sergei of Thessaloníki GNINENKO, Facultad de Nikolai Ciencias, GOLOUBEV Instituto de ROBERT SpyridonFísica Nuclear DEDOUSSIS, y Altas Energías Christos ELEFTHERIADIS, Anastasios LIOLIOS,Berta BELTRAN, Argyrios Jose NIKOLAIDIS, CARMONA, Ilias Susana SAVVIDIS, CEBRIAN, Konstantin Gloria Germany, Darmstadt , DAPNIA ZIOUTASLUZON, Angel MORALES, Julio MORALES, Alfonso ORTIZ DE Technische Universitat Darmstadt E ,Alain DELBART, Esther Switzerland,SOLORZANO, Geneve Jaime RUZ Theopisti DAFNI, Dieter HOFFMANN, Manfred MUTTERER DAVENPORT,Italy, Pisa Michel DELATTRE EuropeanScuola Organization Normale Superiore for Nuclear (SNS) Research (CERN) Germany, Frankfurt , Maria SARSA, Jose VILLAR KlausLuigi BARTH, DI LELLA Enrico CHESI, Gino CIPOLLA Applied Physics FORMENTI, Igor IRASTORZA, Jean-Noel JOUX, Christian , Institut für Kernphysik Vladimir ARSOV, Joachim JACOBY LASSEUR,Russia, Angelika Moskva LIPPITSCH, Thomas PAPAEVANGELOU Russian Academy of Sciences , Martyn Germany, Freiburg Research (INR) , Rui DE OLIVEIRA, Fabio Albert-Ludwigs-Universität Freiburg Alexandre BELOV Horst FISCHER, Juergen FRANZ , Fritz Hertbert HEINSIUS, , , Institute for Nuclear Donghwa KANG, Kay KÖNIGSMANN, Christian SCHILL Alfredo PLACCI, Laura STEWART, Bruno VULLIERME, Louis WALCKIERS Germany, Garching Max-Planck-Gesellschaft (MPG) United States of America, Chicago, Il Extraterrestrische Physik University of Chicago, Enrico Fermi Institute Heinrich BRAUNINGER, Jakob ENGLHAUSER , Markus KUSTERTaylor AUNE, Juan COLLAR, Joaquin VIEIRA
Germany, Muenchen United States of America, Columbia, Sc , Max-Planck-Institut für PhysikMax-Planck-Institut für University of South Carolina, Department of Physics and Rainer KOTTHAUS, Gerhard LUTZ, Georg RAFFELT Astronomy Frank AVIGNONE, Richard CRESWICK, Horacio FARACH Greece, Athens National Center for Scientific , Werner-Heisenberg-Institut Thomas PapaevangelouGeorge Searc FANOURAKIS,h for Solar Theodoros Axions: GERALIS, The Katerina CAST experiment at CERN La Thuile, March 2004 ZACHARIADOU,Kostas KOUSOURIS
Research "Demokritos" (NRCPS) 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 α→γtimes better conversion efficiency than any other !! SR8 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 Spare part of the ABRIXAS Space technology: 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 threshold Efficiency : ~0.6KeV 0.6 (95%Ar+5%Isobutane)0.5 0.4 (Clean materials 0.3 0.2 (Muon vetos 0.1 0 012345678910 Photon energy [keV] Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 TPC
(Conventional therefore robust and stable (Position sensitive (3mm spacing) (48 anode wires(x) (96 cathode wires(y) (time (!) Exploded View
Both windows with data from PANTER
Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 TPC 55Fe Calibration spectrum Clean materials + shielding (polyethylene+copper+ancient lead)
1.85 × 10-4 NO SHIELDING c/keV/sec/c m2
-5 SHIELDING 6.83 × 10 c/keV/sec/cm2
SHIELDING -5 + N FLUX 4.38 × 10 2 c/keV/sec/cm2
Low Background: <10-4 counts keV-1cm-2s-1
Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Analysis: CCD
PRELIMINARY
Prominent CuKa and CuKb fluorescence lines Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Analysis: CCD
CCD upper Limit g αγγ from fit to background subtracted data
PRELIMINARY
Subtracted Spectrum × -10 -1 g αγγ (95%)< 1.1 10 GeV
Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Analysis: CCD
Number of hits in color code CCD position information to be used in refined analysis will reduce efficiently signal to background ratio. On progress.
• CCD area divided into cells of 16×16 Pixels ≈ 7mm2 corresponding to image size of axion source of the sun
Measuring at the same time background and tracking!!!!
New calibration system for this year run!
Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Analysis: Micromegas
Charge_runs_1983-2069 Entries 1530 x10-1 Integral 0.00212034
-1 0.003 keV -2 0.0025 Tracking (red): 20.4h cm -1
0.002 Background (black): 253h
counts s PRELIMINARY 0.0015
0.001 Using Subtracted3 Subtracted3 0.0005 x10-2 Entries -18059 0.003-1 Mean 3.304 2-8RMS keV 1.747 keV
0.002-2 0 02468101214 cm 0.001-1 [keV] 0
-0.001counts s -10 -1 gαγγ (95%CL)< 1.41x 10 GeV -0.002 χ2 /dof = 14/10 -0.003 min -0.004
-0.005
-0.006 Constrained to the physical region 02468101214 [keV]
Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Combined result Combined result Entries 0
Analysis: Micromegas 2 χ 35 Micromegas Data: 30 Combined result
of 3 Subsets 25
20
PRELIMINARY 15
10 -10 -1 gαγγ (95%CL)<1.23x 10 GeV 5 2 χ min/dof = 28 /30 -9 0 x10 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 -1 gaγγ(GeV ) Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Analysis: TPC Tracking & background spectra combined
Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 Analysis: TPC chi2 minimization – 95% C.L. exclusion.
-10 -1 gαγγ(95%)=1.27×10 GeV 2 (χ = 39.9)
χ2 min/dof = 36.0 / 28 Constrained to the physical region
Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004 PRELIMINARY ANALYSIS RESULTS
To be combined
CAST data from 2002 and 2003
Thomas Papaevangelou Search for Solar Axions: The CAST experiment at CERN La Thuile, March 2004