Bonn 2010 – wissenschaftliches Programm
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T: Fachverband Teilchenphysik
T 113: Experimentelle Techniken der Astroteilchenphysik III
T 113.5: Vortrag
Donnerstag, 18. März 2010, 17:50–18:05, HG ÜR 1
The CAST X-ray Telescope — •Madalin-M Rosu — Institut für Kernphysik, Technische Universität Darmstadt, Germany
CAST (CERN Axion Solar Telescope) is a project at the European Organization for Nuclear Research CERN in Geneva, which searches for Axions coming from the Sun.
The most sensitive detector system used at CAST is the X-ray Wolter type I telescope. Its two constituents, the X-ray mirror optics and the fully depleted EPIC pn-CCD detector, were originally built for ABRIXAS and XMM-Newton space missions. Their combined use provides the X-ray telescope with the highest axion discovery potential of all CAST detectors , excellent imaging capability and almost 100% data tacking reliability in conditions of low background which is suppressed by a factor of 155 by focusing the photons from the aperture of the magnet of 14.5 cm2 to a spot of roughly 9.3 mm2 on the CCD chip. For achieving a high sensitivity the CCD chip is operated at -130∘C in a vacuum vessel made of aluminum and a passive shield of copper and led to reduce the external γ-ray.
All these combined with a extremely thin and homogeneous entrance window of 20 nm located on the back side of the chip result in a quantum efficiency of >95% in the photon energy range of 1 to 7 keV, which is the interesting region for the axion search with the CAST experiment.