Superconducting transition-edge sensors (TESs) are highly sensitive detectors. Based on the outstanding performance on spectral resolution, the X-ray Integral Field Unit (X-IFU) instrument on-board Athena will be equipped with a large array of TES based microcalorimeters. SRON is developing a Frequency Domain Multiplexing (FDM) readout scheme for the X-IFU instrument. SRON will also develop and produce TiAu bilayer-based TES arrays for the X-IFU instrument as a backup option.
For optimal performance in terms of the energy resolution it is essential to limit undesirable non-linearity effects in the TES detector. Weak-link behavior is such a non-linearity effect and it has been observed when TES detectors are operated under ac bias in the MHz regime. Weak link behavior is induced by TES to lead contacts, and can cause kinks in the transition curve which drastically limit the access of optimal biasing points. To determine the magnitude of the effect of the leads on the intrinsic transition curve of the TiAu bilayer, we designed smart test structures. We will measure and analyze accurately the transition curves of these test structures.
Based on the results we re-engineered and fabricated further optimized TES based X-ray detectors. We will measure the noise of these detectors and their performance on spectral resolution using an X-ray source. In this contribution we report on the details and the results of this investigation.
This work is partly funded by European Space Agency (ESA) under ESA CTP contract ITT AO/1-7947/14/NL/BW, and is partly by the European Union’s Horizon 2020 Programme under the AHEAD project with grant agreement number 654215.
|Student (Ph.D., M.Sc. or B.Sc.)||N|
|Less than 5 years of experience since completion of Ph.D||N|