Study of the dependency on magnetic field and bias voltage of an AC-biased TES microcalorimeter

TL;DR

This study investigates how magnetic field and bias voltage affect an AC-biased TES microcalorimeter's performance, revealing a periodic noise dependency and comparing its energy resolution to DC bias configurations.

Contribution

It provides the first detailed characterization of AC-biased TES microcalorimeters' dependence on magnetic field and bias voltage, highlighting weak-link behavior effects.

Findings

Energy resolution of 3.7 eV at 6 keV for AC bias

Periodic noise dependency on bias voltage

Weak-link behavior observed in TES microcalorimeter

Abstract

At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in an AC bias configuration. For x-ray photons at 6 keV the pixel shows an x-ray energy resolution $dE_{FWHM} = 3.7\mathrm{eV}$, which is about a factor 2 worse than the energy resolution observed in an identical DC-biased pixel. In order to better understand the reasons for this discrepancy we characterised the detector as a function of temperature, bias working point and applied perpendicular magnetic field. A strong periodic dependency of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recently observed weak-link behaviour of a TES microcalorimeter