High-density arrays of x-ray microcalorimeters for Constellation-X

Caroline A. Kilbourne, Simon R. Bandler, Ari D. Brown, James A. Chervenak, Enectali Figueroa-Feliciano, Fred M. Finkbeiner, Naoko Iyomoto, Richard L. Kelley, F. Scott Porter, Tarek Saab, John Sadleir, Jennifer White

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)


We have been developing x-ray microcalorimeters for the Constellation-X mission. Devices based on superconducting transition-edge sensors (TES) have demonstrated the potential to meet the Constellation-X requirements for spectral resolution, speed, and array scale (> 1000 pixels) in a close-packed geometry. In our part of the GSFC/NIST collaboration on this technology development, we have been concentrating on the fabrication of arrays of pixels suitable for the Constellation-X reference configuration. We have fabricated 8×8 arrays with 0.25-mm pixels arranged with 92% fill factor. The pixels are based on Mo/Au TES and Bi/Cu or Au/Bi absorbers. We have achieved a resolution of 4.0 eV FWHM at 6 keV in such devices, which meets the Constellation-X resolution requirement at 6 keV. Studies of the thermal transport in our Bi/Cu absorbers have shown that, while there is room for improvement, for 0.25-mm pixels the standard absorber design is adequate to avoid unacceptable line-broadening from position dependence caused by thermal diffusion. In order to improve reproducibility and to push closer to the 2-eV goal at 6 keV, however, we are refining the design of the TES and the interface to the absorber. Recent efforts to introduce a barrier layer between the Bi and the Mo/Au to avoid variable interface chemistry and thus improve the reproducibility of device characteristics have thus far yielded unsatisfactory results. However, we have developed a new set of absorber designs with contacts to the TES engineered to allow contact only in regions that do not serve as the active thermometer. We have further constrained the design so that a low-resistance absorber will not electrically short the TES. It is with such a design that we have achieved 4.0 eV resolution at 6 keV.

Original languageEnglish
Title of host publicationSpace Telescopes and Instrumentation II
Subtitle of host publicationUltraviolet to Gamma Ray
Publication statusPublished - Oct 2 2006
Externally publishedYes
EventSpace Telescopes and Instrumentation II: Ultraviolet to Gamma Ray - Orlando, FL, United States
Duration: May 24 2006May 31 2006

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume6266 I
ISSN (Print)0277-786X


OtherSpace Telescopes and Instrumentation II: Ultraviolet to Gamma Ray
Country/TerritoryUnited States
CityOrlando, FL

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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