Cryogenic high-resolution X-ray spectrometers for SR-XRF and microanalysis

Abstract

Experimental results are presented obtained with a cryogenically cooled high-resolution X-ray spectrometer based on a 141 Â 141 mm Nb-Al-Al 2 O 3 -Al-Nb superconducting tunnel junction (STJ) detector in an SR-XRF demonstration experiment. STJ detectors can operate at count rates approaching those of semiconductor detectors while still providing a signi®cantly better energy resolution for soft X-rays. By measuring¯uorescence X-rays from samples containing transition metals and low-Z elements, an FWHM energy resolution of 6±15 eV for X-rays in the energy range 180±1100 eV has been obtained. The results show that, in the near future, STJ detectors may prove very useful in XRF and microanalysis applications.

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

“…Fortunately, photolithographic device fabrication and a preamplifier with an off-the-shelf field effect transistor (FET) input stage allow easy scaling to multi-element arrays. For details of the experimental setup see Frank et al (1998a). One concern for the operation of detector arrays is device uniformity.…”

“…The detector development was initially driven by X-ray and particle astrophysics (Kraus et al, 1989;McCammon et al, 1993). More recently, applications in microanalysis (Wollman et al, 1997), material science (Frank et al, 1998a), and biophysics (Benner et al, 1997;Friedrich et al, 1999) have emerged and are being pursued for scientific and commercial interest.…”

Line-splitting in high-resolution superconducting tunnel junction EUV detectors

“…We have developed superconducting Nb-Al-AlOx-Al-Nb EUV and X-ray detectors for high-resolution spectroscopy in astrophysics, material science and biophysics [8], [9]. They consist of a 265 nm bottom Nb film and a 50 nm bottom Al trap, which is oxidized to form a thin AlOx tunneling barrier, a top 50 nm Al trap and a 165 nm Nb absorber film.…”

A Particle Detector Based on a Double Barrier Josephson Junction

“…A conventional STJ has a layered structure consisting of two superconducting layers separated by a tunneling barrier [5], [6]. A particle (or an X-ray photon) absorbed in one of the electrodes breaks Cooper pairs and thereby generates excess charge carriers in proportion to its energy.…”