A practical superconducting-microcalorimeter X-ray spectrometer for beamline and laboratory science

Area of Science:

• Physics
• Materials Science
• Spectroscopy

Background:

• Traditional high-resolution X-ray spectrometers often have limited efficiency.
• Applications involving photon-starved or radiation-sensitive samples require more sensitive detection methods.

Purpose of the Study:

• To describe the design, construction, and operation of a series of microcalorimeter X-ray spectrometers.
• To highlight the advantages of transition-edge sensor (TES) technology for X-ray spectroscopy.
• To showcase the adaptability and performance of these spectrometers across various experimental setups.

Main Methods:

• Utilized an array of several hundred transition-edge sensors (TESs) operating in their superconducting-to-normal-metal transitions.
• Employed a compact, 65 mK detector package with time-division-multiplexed superconducting quantum-interference device (SQUID) readout.
• Implemented a liquid-cryogen-free cryogenic system using a two-stage adiabatic demagnetization refrigerator and pulse tube cryocooler.
• Adapted the spectrometer architecture for diverse sample chambers and observing geometries.

Main Results:

• Achieved best demonstrated energy resolution of 2.1 eV (FWHM) at 5.9 keV for TES pixels below 10 keV.
• Achieved best demonstrated energy resolution of 1.0 eV (FWHM) at 500 eV for TES pixels below 2 keV.
• Successfully deployed seven spectrometers to synchrotron, accelerator, and laboratory-based experiments, with five more to be deployed.

Conclusions:

• The developed TES microcalorimeter X-ray spectrometers offer significant efficiency advantages for specialized applications.
• The flexible architecture allows for adaptation to a wide range of measurement needs.
• Future generations of TES-X-ray spectrometers are anticipated to feature improvements in array size, energy resolution, and counting speed.