Superconducting Tunnel Junction Array Development for High-Resolution Energy-Dispersive X-ray Spectroscopy

Abstract

Cryogenic energy-dispersive X-ray detectors are being developed because of their superior energy resolution (10 eV FWHM for keV X-rays) compared to that achieved in semiconductor energy-dispersive spectrometry (EDS) systems. So far, their range of application is limited because of their comparably small size and low count rate. We present data on the development of superconducting tunnel junction (STJ) detector arrays to address both of these issues. A single STJ detector has a resolution of around 10 eV below 1 keV and can be operated at count rates of the order 10,000 counts/sec. We show that the simultaneous operation of several STJ detectors does not dimish their energy resolution significantly, and it increases the detector area and the maximum count rate by a factor given by the total number of independent channels.

Characterization of Heterogeneous Nickel Sites in CO Dehydrogenases fromClostridium thermoaceticumandRhodospirillum rubrumby Nickel L-Edge X-ray Spectroscopy

“…The experimental sensitivity of L-edge spectroscopy is now adequate for obtaining spectra on protein films. The introduction of more powerful undulator beamlines 66 and higher resolution detectors 67 will make measurements possible on dilute frozen solutions. L-edges can reveal information about electronic structure that is difficult or impossible to obtain by other methods.…”

Using softer X-ray absorption spectroscopy to probe biological systems

“…An additional experimental difficulty at low energies concerns detectors. For hard X-ray biological XAS the use of energy-dispersive array detectors (Friedrich et al, 1998) has become standard practice for facilitating separation of signal (typically the K fluorescence of a transition metal ion) and background radiation (typically elastic and inelastic scattered X-rays). With copper K-edge measurements, for example, the Cu K emission is more than 900 eV lower in energy than the absorption edge (and the elastic scatter), and about 700 eV lower in energy than the start of the scan.…”

Energy-sensitive cryogenic detectors for high-mass biomolecule mass spectrometry

“…Cryogenic detector arrays with many pixels read out by individual electronic channels are already under development by various groups. STJ detector arrays are currently being developed at Lawrence Livermore National Laboratory (Friedrich et al, 1998) and by a group at the European Space Research and Technology Centre (ESTEC) in The Netherlands (Schilling, 1996). At the same time, arrays of hot-electron microcalorimeters are planned for applications in micro-analysis (Ladbury, 1998) and X-ray astrophysics.…”