Susceptibility study of TES micro-calorimeters for X-ray spectroscopy under FDM readout

TL;DR

This study evaluates the environmental sensitivity of TES micro-calorimeters used in X-ray spectroscopy under FDM readout, confirming their suitability for space instruments like Athena X-IFU.

Contribution

It provides the first detailed characterization of TES micro-calorimeters' environmental sensitivities under FDM, demonstrating their compliance with space instrument requirements.

Findings

FDM TES detectors are insensitive to magnetic fields due to design and AC readout.

The detectors meet the sensitivity requirements for the Athena X-IFU.

Characterization includes bias voltage, temperature, and magnetic field effects.

Abstract

We present a characterization of the sensitivity of TES X-ray micro-calorimeters to environmental conditions under frequency-domain multiplexing (FDM) readout. In the FDM scheme, each TES in a readout chain is in series with a LC band-pass filter and AC biased with an independent carrier at MHz range. Using TES arrays, cold readout circuitry and warm electronics fabricated at SRON and SQUIDs produced at VTT Finland, we characterize the sensitivity of the detectors to bias voltage, bath temperature and magnetic field. We compare our results with the requirements for the Athena X-IFU instrument, showing the compliance of the measured sensitivities. We find in particular that FDM is intrinsically insensitive to the magnetic field because of TES design and AC readout.