Search for Solar : 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 : (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 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 – •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

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 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,, 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 ( 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