AC/DC characterization of a Ti/Au TES with Au/Bi absorber for X-ray detection

TL;DR

This study compares the performance of a Ti/Au transition-edge sensor (TES) with an Au/Bi absorber under AC and DC bias to evaluate its suitability for high-resolution X-ray detection in space applications.

Contribution

It provides the first comparative analysis of a Ti/Au TES's performance under AC and DC bias conditions, relevant for frequency domain multiplexing in space telescopes.

Findings

Preliminary results show differences in dynamical parameters under AC and DC bias.

Noise performance varies between AC and DC biasing conditions.

Comparison lays groundwork for optimizing TES performance in multiplexed X-ray detection.

Abstract

Transition-edge sensors (TESs) are used as very sensitive thermometers in microcalorimeters aimed at detection of different wavelengths. In particular, for soft X-ray astrophysics, science goals require very high resolution microcalorimeters which can be achieved with TESs coupled to suitable absorbers. For many applications there is also need for a high number of pixels which typically requires multiplexing in the readout stage. Frequency Domain Multiplexing (FDM) is a common scheme and is the baseline proposed for the ATHENA mission. FDM requires biasing the TES in AC at MHz frequencies. Recently there has been reported degradation in performances under AC with respect to DC bias. In order to assess the performances of TESs to be used with FDM, it is thus of great interest to compare the performances of the same device both under AC and DC bias. This requires two different measurement setups with different processes for making the characterization. We report in this work the preliminary results of a single pixel characterization performed on a TiAu TES under AC and afterwards under DC bias in different facilities. Extraction of dynamical parameters and noise performances are compared in both cases as a first stage for further AC/DC comparison of these devices.