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T: Fachverband Teilchenphysik

T 14: Gasgefüllte Detektoren I

T 14.4: Vortrag

Montag, 19. März 2018, 16:50–17:05, Z6 - SR 2.002

Set up of a new X-ray detector for CAST — •Tobias Schiffer, Klaus Desch, Jochen Kaminski, Christoph Krieger, and Sebastian Schmidt — Physikalisches Institut, Universität Bonn

The search for solar axions and chameleons with helioscopes like the CERN Axion Solar Telescope (CAST) requires detectors with very low background rates and high detection efficiency, since the expected rates are in the order of one per week and cm² or less in the region of 2 to 7 keV. For this, multipattern gaseous detectors like MicroMegas are a convenient solution. Due to their high granularity they achieve a very high spatial resolution, thus allowing eventshape reconstruction. An appropriate way to maximise the useage of the granularity is a pixelised readout chip, like the Timepix ASIC, with a perfectly aligned gas amplification stage on top. This so called GridPix is also able to detect single primary electrons giving a good energy reconstruction for X-rays.

The measurement of particles like axions or chameleons is done via conversion X-rays, so also the transmission for low energy X-rays has to be kept in mind. Taking these two major aspects into account a low background X-ray detector based on the GridPix technology has been developed and built, including subcomponents like a 300 nm thick vacuum tight entrance window, closed loop water cooling, FADC trigger recording the analogue signal induced on the grid and veto scintillators.

The challenges of the developement and construction will be discussed, also some first results will be presented.