Silicon drift detector prototypes for the keV-scale sterile neutrino search with TRISTAN

The TRISTAN project is an extension of the KATRIN experiment to search for the signature of keV-scale sterile neutrinos in the tritium beta decay spectrum. Sterile neutrinos are hypothetical particles that mix with the active neutrinos and thus affect the spectral shape of the beta decay. For the spectroscopy of electrons from the high-activity tritium source a novel pixelated silicon drift detector (SDD) is in development. In this work the characterization of 7-pixel SDD prototypes equipped with the IDeF-X BD ASIC is presented. The prototype detectors have pixel diameters between 0.5 and 2 mm with 2-12 drift rings. The ASIC noise floor was reached with all designs. A particular focus of the characterization measurements was the study of charge sharing. A very good general performance of the SDD prototypes was demonstrated. In order to reduce charge sharing the detector prototyping continues with SDDs with a pixel diameter of 3 mm. The next prototypes with 160 pixels are in production. (C) 2017 Elsevier B.V. All rights reserved.