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T: Fachverband Teilchenphysik

T 19: Suche nach dunkler Materie I

T 19.5: Vortrag

Montag, 29. Februar 2016, 12:05–12:20, VMP9 SR 28

Upgrade of the InGrid based X-ray detector for the CAST experiment — Klaus Desch, Jochen Kaminski, Christoph Krieger, and •Sebastian Schmidt — Physikalisches Institut, Universität Bonn, Nußallee 12, 53115 Bonn

The CERN Axion Solar Telescope (CAST) is a magnetic helioscope searching for solar axions and chameleons using the inverse Primakoff effect. The produced photons are in the low X-ray regime.

Chameleon search demands high sensitivity to photons with less than 1 keV and a very low background rate. Several improvements to the detector design used in 2014/15 are envisaged for 2016.

The readout system is to be improved by including a flash ADC to read out the analog signal induced on the grid. The pulse shape contains information about the longitudinal shape of the event in addition to the transverse shape given by the pixel read out. Tracks passing through the chip orthogonally resemble photons in transverse shape. A scintillator behind the detector will also allow cross referencing chip and and scintillator signals to further reduce background rates.

Finally, a new X-ray window separating detector and X-ray telescope volume from one another will be installed. Due to the low expected signal rate, a window with very low X-ray opacity is needed. Due to a pressure difference of ∼ 1  bar between detector and the vacuum of CAST this is demanding. The usage of silicon nitride windows is being explored.

The current progress of the detector upgrade will be presented.