Performance of an X-ray single pixel TES microcalorimeter under DC and AC biasing

TL;DR

This study compares the performance of a TES microcalorimeter under DC and AC biasing, focusing on parameters like energy resolution, noise, and impedance, revealing similar behavior with some deviations at low transition points.

Contribution

It provides a detailed comparison of TES microcalorimeter performance under DC and AC biasing, highlighting differences in energy resolution and operational characteristics.

Findings

Energy resolution of 2.7 eV (DC) vs. 3.7 eV (AC) at 5.89 keV

Similar behavior in current-voltage and impedance characteristics

Deviations observed at low superconducting transition levels

Abstract

We are developing Frequency Domain Multiplexing (FDM) for the read-out of TES imaging microcalorimeter arrays for future X-ray missions like IXO. In the FDMconfiguration the TES is AC voltage biased at a well defined frequencies (between 0.3 to 10MHz) and acts as an AM modulating element. In this paper we will present a full comparison of the performance of a TES microcalorimeter under DC bias and AC bias at a frequency of 370kHz. In both cases we measured the current-to-voltage characteristics, the complex impedance, the noise, the X-ray responsivity, and energy resolution. The behaviour is very similar in both cases, but deviations in performances are observed for detector working points low in the superconducting transition (R/RN < 0.5). The measured energy resolution at 5.89keV is 2.7eV for DC bias and 3.7eV for AC bias, while the baseline resolution is 2.8eV and 3.3eV, respectively.