Mitigation of the Magnetic Field Susceptibility of Transition Edge Sensors using a Superconducting Groundplane

• Main Authors: de Wit, Martin, Gottardi, Luciano, Ridder, Marcel L, Nagayoshi, Kenichiro, Taralli, Emanuele, Akamatsu, Hiroki, Vaccaro, Davide, Herder, Jan-Willem A. den, Bruijn, Marcel P, Gao, Jian-Rong
• Format: Journal Article
• Language: English
• Published: 23-08-2022
• Subjects: Physics - Instrumentation and Detectors; Physics - Instrumentation and Methods for Astrophysics
• DOI: 10.48550/arxiv.2208.10775

Phys. Rev. Applied 18, 024066 (2022) Transition edge sensor (TES) microcalorimeters and bolometers are used for a
variety of applications. The sensors are based on the steep
temperature-dependent resistance of the normal-to-superconducting transition,
and are thus intrinsically sensitive to magnetic fields. Conventionally the
detectors are shielded from stray magnetic fields using external magnetic
shields. However, in particular for applications with strict limits on the
available space and mass of an instrument, external magnetic shields might not
be enough to obtain the required shielding factors or field homogeneity.
Additionally, these shields are only effective for magnetic fields generated
external to the TES array, and are ineffective to mitigate the impact of
internally generated magnetic fields. Here we present an alternative shielding
method based on a superconducting groundplane deposited directly on the
backside of the silicon nitride membrane on which the TESs are located. We
demonstrate that this local shielding for external magnetic fields has a
shielding factor of at the least ~ 75, and is also effective at reducing
internal self-induced magnetic fields, as demonstrated by measurements and
simulation of the eddy current losses in our AC biased detectors. Measurements
of 5.9 keV X-ray photons show that our shielded detectors have a high
resilience to external magnetic fields, showing no degradation of the energy
resolution or shifts of the energy scale calibration for fields of several
microTesla, values higher than expected in typical real-world applications.