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Title: Superconducting tunneling-junction detectors of X-ray radiation. Issues concerning the energy resolution

Abstract

The effect of the recombination-and edge-related losses of nonequilibrium quasiparticles on the energy resolution of superconducting tunneling detectors is studied. The dependence of the signal on the energy of X-ray photons is measured and the shape of instrument-related lines is studied for the Ti/Nb/Al/AlO{sub x}/Al/Nb/NbN detectors with the Ti/Nb passive electrode. Experimental data are analyzed using the diffusion-based model of tunneling detectors.

Authors:
 [1];  [2]; ;  [3]
  1. Skobel'tsyn Research Institute of Nuclear Physics at the Moscow State University (Russian Federation), E-mail: andrva22@mail.ru
  2. Moscow State University, Department of Computational Mathematics and Cybernetics (Russian Federation), E-mail: v-p-gorkov@yandex.ru
  3. Russian Academy of Sciences, Institute of Radio Engineering and Electronics (Russian Federation)
Publication Date:
OSTI Identifier:
21088437
Resource Type:
Journal Article
Resource Relation:
Journal Name: Semiconductors; Journal Volume: 41; Journal Issue: 2; Other Information: DOI: 10.1134/S1063782607020194; Copyright (c) 2007 Nauka/Interperiodica; Article Copyright (c) 2007 Pleiades Publishing, Ltd; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM; ALUMINIUM OXIDES; DIFFUSION; ELECTRODES; ENERGY RESOLUTION; JUNCTION DETECTORS; NIOBIUM; NIOBIUM NITRIDES; PHOTONS; QUASI PARTICLES; RECOMBINATION; TITANIUM; TUNNEL EFFECT; X RADIATION

Citation Formats

Andrianov, V. A., Gor'kov, V. P., Koshelets, V. P., E-mail: valery@hitech.cplire.ru, and Filippenko, L. V. Superconducting tunneling-junction detectors of X-ray radiation. Issues concerning the energy resolution. United States: N. p., 2007. Web. doi:10.1134/S1063782607020194.
Andrianov, V. A., Gor'kov, V. P., Koshelets, V. P., E-mail: valery@hitech.cplire.ru, & Filippenko, L. V. Superconducting tunneling-junction detectors of X-ray radiation. Issues concerning the energy resolution. United States. doi:10.1134/S1063782607020194.
Andrianov, V. A., Gor'kov, V. P., Koshelets, V. P., E-mail: valery@hitech.cplire.ru, and Filippenko, L. V. Thu . "Superconducting tunneling-junction detectors of X-ray radiation. Issues concerning the energy resolution". United States. doi:10.1134/S1063782607020194.
@article{osti_21088437,
title = {Superconducting tunneling-junction detectors of X-ray radiation. Issues concerning the energy resolution},
author = {Andrianov, V. A. and Gor'kov, V. P. and Koshelets, V. P., E-mail: valery@hitech.cplire.ru and Filippenko, L. V.},
abstractNote = {The effect of the recombination-and edge-related losses of nonequilibrium quasiparticles on the energy resolution of superconducting tunneling detectors is studied. The dependence of the signal on the energy of X-ray photons is measured and the shape of instrument-related lines is studied for the Ti/Nb/Al/AlO{sub x}/Al/Nb/NbN detectors with the Ti/Nb passive electrode. Experimental data are analyzed using the diffusion-based model of tunneling detectors.},
doi = {10.1134/S1063782607020194},
journal = {Semiconductors},
number = 2,
volume = 41,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • In a superconducting detector, the energy resolution is expected to be superior than in a semiconductor detector, owing to the thousand times smaller energy gap ..delta... The performance of Sn/Sn-oxide/Sn tunneling junctions (operated in the Giaever mode at T = 0.32 K) exposed to 6-keV x-ray photons of a /sup 55/Fe source is presented. The best energy resolution observed is 67 eV (FWHM). Extrapolating to vanishing electronic noise, an intrinsic resolution of 0.7% (FWHM) is obtained. This is an order of magnitude worse than expected from the statistics of the 2.5 x 10/sup 6/ primary electron charges produced, and ismore » believed to be due to geometrical effects in the films. The energy response of the detector is nonlinear, owing to the self-recombination of the free charge carriers. At a fixed bias voltage, the pulses generated in either film of the junction were observed to have the same sign. If the junctions are evaporated onto a silicon substrate, most of the pulses originate, via phonon backscattering, from x-ray photons interacting in the substrate. Quasiparticle diffusion is essential in explaining the observed data.« less
  • Superconducting tunnel junctions coupled to superconducting absorbers may be used as high-resolution, high-efficiency x-ray spectrometers. We have tested devices with niobium x-ray absorbing layers coupled to aluminum layers that serve as quasiparticle traps. The energy resolution at 6 keV was 49 eV full width at half-maximum. We estimate that each quasiparticle tunnels an average of 19 times before recombining, increasing the total charge transferred and therefore decreasing the effects of electronic noise.
  • We present experimental results obtained with a cryogenically cooled, high-resolution x-ray spectrometer based on a 141{mu}m{times}141{mu}m Nb-Al-Al{sub 2}O{sub 3}-Al-Nb superconducting tunnel junction (STJ) detector in a demonstration experiment. Using monochromatized synchrotron radiation we studied the energy resolution of this energy-dispersive spectrometer for soft x rays with energies between 70 and 700 eV and investigated its performance at count rates up to nearly 60000 cps. At count rates of several 100 cps we achieved an energy resolution of 5.9 eV (FWHM) and an electronic noise of 4.5 eV for 277 eV x rays (the energy corresponding to C K). Increasing themore » count rate, the resolution 277 eV remained below 10 eV for count rates up to {approximately}10000cps and then degraded to 13 eV at 23000 cps and 20 eV at 50000 cps. These results were achieved using a commercially available spectroscopy amplifier with a baseline restorer. No pile-up rejection was applied in these measurements. Our results show that STJ detectors can operate at count rates approaching those of semiconductor detectors while still providing a significantly better energy resolution for soft x rays. Thus STJ detectors may prove very useful in microanalysis, synchrotron x-ray fluorescence (XRF) applications, and XRF analysis of light elements (K lines) and transition elements (L lines). {copyright} {ital 1998 American Institute of Physics.}« less
  • Giaever-type superconducting tunneling junctions are shown to be sensitive to the ionization energy of low-energy x-ray photons. The Mn K..cap alpha.. and Mn K..beta.. x-ray photons from a Fe/sup 55/ source were detected with an energy resolution of 67 eV full width at half maximum (FWHM) at an energy of 5.89 keV with Sn/Sn oxide/Sn junctions evaporated on fused silica and operated at a temperature of 0.38 K. In this paper, a model of this detector is presented. The basic features are well described by dynamical Cooper-pair breaking and the relaxation mechanisms of nonequilibrium superconductivity. Quasiparticle diffusion had to bemore » included in order to explain the observed data. The solutions of the four coupled Rothwarf-Taylor equations, one quasiparticle equation and one 2..delta..-phonon equation for each of the two films, agree reasonably well with measured pulse shapes.« less
  • The asymmetric response of the counter and base electrodes of x-ray detectors employing polycrystalline niobium tunnel junctions has been studied by low-temperature scanning electron microscopy (LTSEM). LTSEM has revealed that the base electrode produces a signal more than two times larger than the counter electrode, and effective quasiparticle lifetimes are 100 ns in the counter and 280 ns in the base. Based on the {ital I}-{ital V} characteristics and the measured effective quasiparticle lifetimes, we propose a model structure for a spatial variation of the gap parameter {Delta}, which involves proximity quasiparticle trapping layers. The small counter signal is causedmore » by the shorter quasiparticle lifetime and the trapping effect. The LTSEM results are consistent with x-ray spectra for a radioactive {sup 55}Fe source. {copyright} {ital 1996 The American Physical Society.}« less