Absolute Energy Measurements with Superconducting Transition-Edge Sensors for Muonic X-ray Spectroscopy at 44 keV

TL;DR

This paper demonstrates the development and calibration of superconducting transition-edge sensors for precise absolute energy measurements of muonic X-ray lines at 44 keV, achieving high accuracy and resolution.

Contribution

The work introduces hard x-ray TESs with optimized absorbers for accurate absolute energy calibration at keV energies, advancing muonic X-ray spectroscopy capabilities.

Findings

Achieved ~1 eV absolute energy measurement accuracy at 44 keV.

Achieved < 12 eV energy resolution at 17.5 keV.

Developed TESs with different heat capacities for optimized performance.

Abstract

Superconducting transition-edge sensor (TES) microcalorimeters have great utility in x-ray applications owing to their high energy resolution, good collecting efficiency and the feasibility of being multiplexed into large arrays. In this work, we develop hard x-ray TESs to measure the absolute energies of muonic-argon ($\mu$-Ar) transition lines around 44 keV and 20 keV. TESs with sidecar absorbers of different heat capacities were fabricated and characterized for their energy resolution and calibration uncertainty. We achieved ~ 1 eV absolute energy measurement accuracy at 44 keV, and < 12 eV energy resolution at 17.5 keV.