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Search for Solar Axions the CAST experiment at CERN

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					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 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 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
                       mα < 10-2 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




Decomissioned LCH test magnet
Decomissioned LCH test magnet
Rotating platform
Rotating platform
33X-ray detectors
  X-ray detectors
X-ray Focusing Device
X-ray Focusing 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                                      100 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

                                                        Magnet at
                                                        Magnet at
                                                              -8°
                                                               -8°




                       Magnet at
                       Magnet at
                             +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. Readout computer
•Software with astronomical
calculations
•Interface to move magnet
•New high precision angle
encoders!

•Calibrated and correlated
with celestial coordinates
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
          Twice a year (September&March)
           Twice a year (September&March)
          we can film the Sun through the
           we can film the Sun through the
                      window
                       window
                                                                              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:
  Smooth & safe
  operation
  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)                  Big value of (LB)2
                                            Low 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
 Calibration 55Fe
                                                                   Entries        29421
                                                                   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]

                                                                                                                                   Plot with data from PANTER
Background rate: <10-4 events keV-1s-1cm-2
                                                            X-ray conversion efficiency
                                                                    Efficiency of the micromegas for 90% strongback transparency


  X-Ray detection
                                             Efficiency




                                                          0.8



threshold: ~0.6KeV
                                                          0.7

                                                          0.6


(95%Ar+5%Isobutane)                                       0.5

                                                          0.4


  Clean materials                                         0.3

                                                          0.2


  Muon vetos                                              0.1

                                                           0
                                                            0      1        2       3       4       5       6        7    8      9     10
                                                                                                                     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



                       SHIELDING           6.83 × 10-5
                                         c/keV/sec/cm2

                        SHIELDING
                         + N2 FLUX              4.38 × 10-5
                                              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                                                     PRELIMINARY
        CCD upper Limit g αγγ from fit to background subtracted data




        Subtracted Spectrum                             g αγγ (95%)< 1.1×10-10 GeV-1
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                                                                                PRELIMINARY
       Charge_runs_1983-2069                             Entries                             1530
                   -1
             x10                                         Integral 0.00212034
-1




  0.003
cm -2 keV




0.0025
                                                                                                  Tracking (red): 20.4h
-1




                                                                                                  Background (black): 253h
 counts s




  0.002


0.0015


  0.001

                                                                            Subtracted3
                                                                                                                                      Using
                                                                                                                                       Subtracted3
                                                                                                       -2
0.0005                                                                                           x10                                   Entries   -18059

                                                                                                                                      2-8 keV




                                                                   counts s -1 cm-2 keV -1
                                                                                                                                       Mean        3.304
                                                                           0.003
                                                                                                                                       RMS         1.747
                                                                           0.002
            0
             0          2   4   6        8      10      12        14
                                                                  0.001
                                                              [keV]
                                                                                             0

                                                                     -0.001

 gαγγ (95%CL)< 1.41x                         10-10 GeV-1             -0.002


         χ2min/dof = 14/10                                           -0.003

                                                                     -0.004

                                                                     -0.005

            Constrained to the physical region                       -0.006
                                                                           0                                2   4   6   8       10    12       14
                                                                                                                                           [keV]


     Thomas Papaevangelou           Search for Solar Axions: The CAST experiment at CERN                                    La Thuile, March 2004
                                       Combined result                                        Combined result


Analysis: Micromegas
                                                                                              Entries       0




                                     χ2
                                          35

Micromegas Data:
                                          30
     Combined result
     of 3 Subsets                         25


                                          20
  PRELIMINARY
                                          15


                                          10

gαγγ (95%CL)<1.23x 10-10GeV-1
                                           5
          χ2min/dof = 28 /30
                                           0                                                              x10-9
                                               -0.15 -0.1 -0.05        0      0.05     0.1    0.15
                                                                                                     -1
                                                                                         gaγ γ (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.
                                                           gαγγ(95%)=1.27×10-10 GeV-1
                                                                      (χ2 = 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

				
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