1. ICHEP 2006 1 / 24 Status Report of CERN Axion Solar Telescope (CAST) Experiment Dieter H.H. Hoffmann (Tech. University Darmstadt & GSI – Darmstadt) on behalf of the CAST collaboration ICHEP, Moscow July 27 th 2006

2. ICHEP 2006 2 / 24 Summary of presentation Brief CAST overview Analysis of 2004 data (phase I) CAST phase II Schedule for next months Conclusions CAST Collaboration

3. ICHEP 2006 3 / 24 CERN and CAST CAST

4. ICHEP 2006 4 / 24 CAST working principle  Sikivie [1983] Axion source Axion detection

5. ICHEP 2006 5 / 24 CAST history 20022003200420052006 CAST construction CAST phase ICAST phase II First commissioning runs First Physics runs Physics runs – Enhanced operation Work to upgrade for phase II First physics runs – phase II 4 He Phase II (4He) operation

6. ICHEP 2006 6 / 24 C ern A xion S olar T elescope Thomas Sahner

7. ICHEP 2006 7 / 24 CAST setup overview LHC test magnet TPC Micromegas & CCD/Telescope

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9. ICHEP 2006 9 / 24 Tracking System : Calibrated and correlated with celestial coordinates Tracking System : Calibrated and correlated with celestial coordinates Twice a year (September&March) we can film the Sun through the window Looking at sunrise Magnet, sun tracking

10. ICHEP 2006 10 / 24 TPC

11. ICHEP 2006 11 / 24 HEC μMμM XRT CCD HEC

12. ICHEP 2006 12 / 24 Solar axion spectrum P a  γ  1.7  10 -17 

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15. ICHEP 2006 15 / 24 ~33% → On-Axis Effective Areas at PANTER and at CAST 0.0 2.0 4.0 6.0 8.0 10.0 12.0 0.51.52.53.54.55.56.57.58.59.5 Energy [keV] Calculated effective area in PANTER (48 mm diameter aperture) Measured Effective area in PANTER (48 mm diameter aperture) Expected effective area at CAST (42 mm diameter aperture) The effective area of the X-ray telescope f (E γ ). ↓ 4.5 keV

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17. ICHEP 2006 17 / 24 2004 data analysis CCD/Telescope Spot position well determined Full sensitivity of telescope exploited Counts inside the spot compatible with background level Tracking dataSignal simulation No axion signal detected

18. ICHEP 2006 18 / 24 2004 data analysis TPC 2004 subtracted spectrum Micromegas 2004 subtracted spectrum ~200 h of tracking data for each detector Almost non-interrupted operation. High quality data No axion signal detected

19. ICHEP 2006 19 / 24 2004 result for New exclusion plot, improving 2003 result Factor of 7 improvement beyond previous experimental searches. It goes beyond astrophysical limit of globular clusters for coherence masses Publication now under preparation

20. ICHEP 2006 20 / 24 CAST phase II – principle of detection Extending the coherence to higher axion masses... Coherence condition (qL << 1) is recovered for a narrow mass range around m  N e : number of electrons/cm 3  : gas density (g/cm 3 )

21. ICHEP 2006 21 / 24 CAST phase II CAST phase II approved by CERN Research Board on Dec 2004 CAST phase II approved by CERN Research Board on Dec 2004 Data taking with 4 He started last November Data taking with 4 He started last November 3 He phase will start mid 2007 (LLNL will provide the 3 He) 3 He phase will start mid 2007 (LLNL will provide the 3 He) CAST phase II sensitivity Cosmological limit (Hannestad et al, JCAP 0507 (05) 002) Present progress

22. ICHEP 2006 22 / 24 Schedule 2006 JulyAugSepOctNovDec Data taking with 4 He 1 step per day tests for ramping? 3 He system road map Complete TDR Complete Add. MoU TD Review Start construction components New detection line MM+optic PANTER tests Installation in CAST P ~ 9 mbar m a ~ 0.31eV P ~ 12 mbar m a ~ 0.37eV

23. ICHEP 2006 23 / 24 Schedule 2007 JFMAMJJASOND 3 He System Installation in CAST Commissionin g Data taking Start 3 He physics runs Double step Possibility of ramping mode? 20082009 Data taking Time needed to fully exploit new setup P ~ 45 mbar m a ~ 0.71 eV P ~ 120 mbar m a ~ 1.16 eV

24. ICHEP 2006 24 / 24 Conclusions CAST has successfully performed its transition into phase II: Phase I data analysis finished. Publication under preparation Upgrades to start phase II done during 2005: 4 He system, cold windows Phase II 4 He data taking ongoing Started in Nov 2005 Up to 4 mbar scanned already. 4 He runs planned until the end of the year Installation of new detector line with a second X-ray optics planned before the end of the year Phase II 3 He operation scheduled for mid next year 3 He system designed. Technical report in preparation Schedule for next months has been presented CAST will reach 60 mbar (0.8 eV) during 2008 3 He allows extension to even higher masses (1.16 eV)