Highly Multiplexible Thermal Kinetic Inductance Detectors for X-Ray Imaging Spectroscopy

TL;DR

This paper introduces thermal kinetic inductance detectors (TKIDs) for X-ray spectroscopy, demonstrating their potential for high energy resolution and multiplexing capabilities, with initial prototypes achieving 75 eV resolution at 5.9 keV.

Contribution

The work presents the first functional TKID prototypes, detailing their fabrication, characterization, and multiplexing, and discusses design optimizations for improved energy resolution.

Findings

Achieved 75 eV energy resolution at 5.9 keV with initial prototypes.

Demonstrated the necessity of data fitting algorithms for photon energy extraction.

Outlined fabrication and multiplexing techniques for TKIDs.

Abstract

For X-ray imaging spectroscopy, high spatial resolution over a large field of view is often as important as high energy resolution, but current X-ray detectors do not provide both in the same device. Thermal Kinetic Inductance Detectors (TKIDs) are being developed as they offer a feasible way to combine the energy resolution of transition edge sensors with pixel counts approaching CCDs and thus promise significant improvements for many X-ray spectroscopy applications. TKIDs are a variation of Microwave Kinetic Inductance Detectors (MKIDs) and share their multiplexibility: working MKID arrays with 2024 pixels have recently been demonstrated and much bigger arrays are under development. In this work, we present our first working TKID prototypes which are able to achieve an energy resolution of 75 eV at 5.9 keV, even though their general design still has to be optimized. We further describe TKID fabrication, characterization, multiplexing and working principle and demonstrate the necessity of a data fitting algorithm in order to extract photon energies. With further design optimizations we expect to be able to improve our TKID energy resolution to less than 10 eV at 5.9 keV.