Search for Solar Axions the CAST experiment at

Search for Solar Axions: the CAST experiment at CERN Aisha Hunte for the CAST Collaboration June 2004, CERN

Axions α The STRONG CP PROBLEM Possible 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, Peccei-Quinn (1977) propose an elegant solution to this problem. q not anymore a constant, but a field the axion a(x). Aisha Hunte Search for Solar Axions: The CAST experiment CERN, 29 th June 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 q absorbed in the definition of a axion – gluon vertex • a qq transitions • a – p 0 mixing • 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. Aisha Hunte Dark matter candidate! Search for Solar Axions: The CAST experiment CERN, 29 th June 2004

Axions α pseudoscalar neutral practically stable phenomenology driven by the breaking scale fa and the specific axion model Couples to photon L = g (E • B) a Primakoff (1951) [ ] PRIMAKOFF EFFECT Any scalar or pseudoscalar particles: axion-like particles Aisha Hunte Search for Solar Axions: The CAST experiment CERN, 29 th June 2004

Axions α PRIMAKOFF EFFECT Stellar interior the Sun!! Solar Axions Flux at the Earth [K. van Bibber et al. , 1989] Aisha Hunte Search for Solar Axions: The CAST experiment CERN, 29 th June 2004

Axions α Transverse magnetic field (B) X-ray detector Signal: X-rays while tracking (magnet pointing to the Sun) over background L Sensitive for m < 10 -2 e. V Lazarus et al. , Brookhaven Tokyo Helioscope: B~4 T, L~2 m Aisha Hunte Search for Solar Axions: The CAST experiment CERN, 29 th June 2004

Axions CAST Sensitivity plot Phase II and up (? ) Filling the magnet bores with 3 He the photon acquires an effective mass: mγ > 0 and by changing the gas pressure we are sensitive to different masses up to ~ 1 e. V To Start in 2005 Aisha Hunte Search for Solar Axions: The CAST experiment CERN, 29 th June 2004

CERN Axion Solar Telescope Sunset Photon detectors Sunrise axions Sunset axions Decomissioned LHC test magnet Rotating platform 3 X-ray detectors X-ray Focusing Device Aisha Hunte Search for Solar Axions: The CAST experiment CERN, 29 th June 2004

CAST is here: Aisha Hunte LEP Point 8 (former DELPHI point) Building 2875 Search for Solar Axions: The CAST experiment CERN, 29 th June 2004

Magnet, platform, cryogenics CAST Experimental area SR 8 4 He L= 10 m B=9 T 100 times better conversion efficiency than any other !! flexible line Magnet Feed Box Aisha Hunte Search for Solar Axions: The CAST experiment CERN, 29 th June 2004

Magnet, platform, cryogenics Looking at the sunrise… MARCH’ 03 Twice a year (September&March) we can film the Sun through the window SEPTEMBER’ 03 Aisha Hunte Search for Solar Axions: The CAST experiment CERN, 29 th June 2004

On the coming sesion: The X-Ray Telescope & X-Ray Detectors EX-Ray Telescope (Focusing Device) EDetectors ECCD ETPC EMicromegas üBig value of B • L üLow background rate detectors X-Ray Telescope!!! Aisha Hunte Search for Solar Axions: The CAST experiment CERN, 29 th June 2004