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Superconducting Tunnel Junction Spectrometers for High Resolution Energy Dispersive Spectroscopy

Published online by Cambridge University Press:  02 July 2020

Carl A. Mears
Carl A. Mears*
Affiliation:
Physics and Space Technology, Lawrence Livermore National Laboratory Livermore, CA, 94550
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We have been developing superconducting tunnel junctions (STJs) for use as high-resolution energy dispersive spectrometers. STJ detectors simultaneously offer energy resolution better than 15 eV at 1 keV, count rates in excess of 10,000 counts per second, broad bandwidth and high efficiency. These attributes make them desirable detectors in a variety of applications, including x-ray microanalysis.

When an x-ray photon is absorbed in a superconductor, about 60% of its energy is used to break the Cooper pairs that make up the superconducting ground state into excited electron-like and hole-like states called quasiparticles. This process is analogous to the creation of electron-hole pairs in a conventional energy dispersive spectrometer (EDS) based on silicon or germanium. The difference is that the superconducting energy gap Δ is on the order of a few millielectron volts, roughly a factor of 1000 less than the band gap in common semiconductors.

Type
30 Years of Energy Dispersive Spectrometry in Microanalysis
Information
Microscopy and Microanalysis , Volume 4 , Issue S2: Proceedings: Microscopy & Microanalysis '98, Microscopy Society of America 56th Annual Meeting, Microbeam Analysis Society 32nd Annual Meeting, Atlanta, Georgia July 12-16, 1998 , July 1998 , pp. 174 - 175
Copyright
Copyright © Microscopy Society of America

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References

1. Rando, N., et al., Nuclear Instruments and Methods, 313, (1992) 173.CrossRefGoogle Scholar

2. Mears, C. A., et al, Applied Physics Letters, 63, (1993) 2961CrossRefGoogle Scholar.

3. This work was performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48 at the Stanford Synchrotron Radiation Laboratory (SSRL) with additional support from NASA contract NAS5-38013 and NASA grant number NAGW-3907Google Scholar