Skip to main content
U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Https

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Use of Transition Models to Design High Performance TESs for the LCLS-II Soft X-Ray Spectrometer

Published

Author(s)

Kelsey M. Morgan, Daniel T. Becker, Douglas A. Bennett, William B. Doriese, Johnathon D. Gard, K D. Irwin, Sang-Jun Lee, Dale Li, John A. Mates, Christine G. Pappas, Daniel R. Schmidt, Charles Titus, Daniel Van Winkle, Joel N. Ullom, Abigail L. Wessels, Daniel S. Swetz

Abstract

We are designing an array of transition-edge sensor (TES) microcalorimeters for a soft X-ray spectrometer at the Linac Coherent Light Source at SLAC National Accelerator Laboratory to coincide with upgrades to the free electron laser facility. The complete spectrometer will have 1000 TES pixels with energy resolution of 0.5 eV full-width at half-maximum (FWHM) for incident energies below 1 keV while maintaining pulse decay-time constants shorter than 100 μs. Historically, TES pixels have often been designed for a particular scientific application via a combination of simple scaling relations and trial-and-error experimentation with device geometry. We have improved upon this process by using our understanding of transition physics to guide TES design. Using the two-fluid approximation of the phase-slip line model for TES resistance, we determine how the geometry and critical temperature of a TES will affect the shape of the transition. We have used these techniques to design sensors with a critical temperature of 55 mK. The best sensors achieve an energy resolution of 0.75 eV FWHM at 1.25 keV. Building upon this result, we show how the next generation of sensors can be designed to reach our goal of 0.5 eV resolution.
Citation
IEEE Transactions on Applied Superconductivity
Volume
29
Issue
5

Keywords

transition-edge sensor, TES, microcalorimeters, soft X-ray spectrometer, Linac Coherent Light Source, SLAC National Accelerator Laboratory, free electron laser facility, FWHM, pulse decay-time, transition physics, two-fluid approximation, phase-slip line model
Created March 3, 2019, Updated July 8, 2020