High-resolution gamma-ray spectrometers using bulk absorbers coupled to Mo/Cu multilayer superconducting transition-edge sensors

D. T. Chow, A. Loshak, M. L. van den Berg, Matthias Frank, T. W. Barbee, S. E. Labov

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


In x-ray and gamma-ray spectroscopy, it is desirable to have detectors with high energy resolution and high absorption efficiency. At LLNL, we have developed superconducting tunnel junction-based single photon x-ray detectors with thin film absorbers that have achieved these goals for photon energies up to 1 keV. However, for energies above 1 keV, the absorption efficiency of these thin-film detectors decreases drastically. We are developing the use of high-purity superconducting bulk materials as microcalorimeter absorbers for high-energy x-rays and gamma rays. The increase in absorber temperature due to incident photons is sensed by a superconducting transition-edge sensor (TES) composed of a Mo/Cu multilayer thin film. Films of Mo and Cu are mutually insoluble and therefore very stable and can be annealed. The multilayer structure allows scaling in thickness to optimize heat capacity and normal state resistance. We measured an energy resolution of 70 eV for 60 keV incident gamma-rays with a 1×1×0.25 mm3 Sn absorber. We present x-ray and gamma-ray results from this detector design with a Sn absorber. We also propose the use of an active negative feedback voltage bias to improve the performance of our detector and show preliminary results.

Original languageEnglish (US)
Pages (from-to)67-75
Number of pages9
JournalProceedings of SPIE - The International Society for Optical Engineering
Issue number1
StatePublished - Nov 21 2000
Externally publishedYes


  • Cryogenic detector
  • Gamma-ray spectroscopy
  • Microcalorimeter

ASJC Scopus subject areas

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


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