New Developments in Superconducting Tunnel Junction X-Ray Spectrometers for Synchrotron Science

Friedrich, S.; Carpenter, M.; Drury, Owen B.; Warburton, W. K.; Harris, Jared D.; Hall, John A.; Cantor, Robin

doi:10.1007/s10909-012-0569-8

Cited by 11 publications

(7 citation statements)

References 9 publications

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“…Figure 2 shows a typical STJ I-V trace (upper curve) generated this way. The small peaks are Fiske mode resonances in the STJ that are known to degrade energy resolution [11,12]. Because they are small, they are not well suited to machine identification processes of the sort required to automate the bias setting process.…”

Section: Noise Curves For Finding Fiske Modesmentioning

confidence: 99%

“…Superconducting tunnel junctions (STJs) are being developed as x-ray detectors in the 100 -2,000 eV range for synchrotron applications because of their demonstrated capability for obtaining energy resolutions below 10 eV at count rates approaching 10 kcps [1][2][3]. Detector sizes, however, are restricted to dimensions of approximately 250 µm by 250 µm or less by the presence of Fiske mode resonances in their I-V curves, which become too closely spaced at larger dimensions to allow an acceptable bias point to be found [4].…”

Section: Introductionmentioning

confidence: 99%

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High density processing electronics for superconducting tunnel junction x-ray detector arrays

Warburton

Harris

Friedrich

2015

Nuclear Instruments and Methods in Physics Research Section A:

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Superconducting tunnel junctions (STJs) are excellent soft x-ray (100-2,000 eV) detectors, particularly for synchrotron applications, because of their ability to obtain energy resolutions below 10 eV at count rates approaching 10 kcps. In order to achieve useful solid detection angles with these very small detectors, they are typically deployed in large arrayscurrently with 100+ elements, but with 1000 elements being contemplated. In this paper we review a 5year effort to develop compact, computer controlled low-noise processing electronics for STJ detector arrays, focusing on the major issues encountered and our solutions to them. Of particular interest are our preamplifier design, which can set the STJ operating points under computer control and achieve 2.7 eV energy resolution; our low noise power supply, which produces only 2 nV/√Hz noise at the preamplifier's critical cascode node; our digital processing card that digitizes and digitally processes 32 channels; and an STJ I-V curve scanning algorithm that computes noise as a function of offset voltage, allowing an optimum operating point to be easily selected. With 32 preamplifiers laid out on a custom 3U EuroCard, and the 32 channel digital card in a 3U PXI card format, electronics for a 128 channel array occupy only two small

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Section: Noise Curves For Finding Fiske Modesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High density processing electronics for superconducting tunnel junction x-ray detector arrays

Warburton

Harris

Friedrich

2015

Nuclear Instruments and Methods in Physics Research Section A:

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“…In [4] and [5], there is experimental evidence of dependence of energy resolution of STJ detectors on count rate. However, these data is insufficient to reveal the contribution of heating of STJ detector by X-rays, as there is another contribution caused by pulses overlapping also depending on the count rate.…”

Section: Temperature Fluctuations Of Stj Detector Caused By X-ray Fluxmentioning

confidence: 99%

Heating of Superconducting Tunnel Junction Detector by X-Ray Flux

Samedov

Tulinov

2012

J Low Temp Phys

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Superconducting tunnel junction (STJ) detectors are in common use for high-resolution soft X-ray spectroscopy at high count rates. Each quasiparticle in superconductor should be treated as quantum superposition of electron-like and holelike excitations. This duality nature of quasiparticle leads to multitunneling in STJ. Because of the multitunneling process, one quasiparticle can transfers into heat the energy that equals to the difference in quasiparticle energy between two electrodes more than once. As a result, the energy transferred into heat in STJ detector is several times grater the energy of X-ray quantum. In this work, the theory of branching cascade processes is applied to the process of energy transfer caused by quasiparticle multitunneling. The mean and the variance of STJ temperature shift from the substrate temperature caused by heating of STJ by X-rays flux were derived.

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“…More recently, STAR Cryoelectronics has developed STJs based on tantalum, since its high atomic number (Z Ta = 73) increases the quantum efficiency, and its small energy gap (Δ Ta = 0.7 meV) improves the energy resolution over earlier Nb-based STJs. These Ta-STJs have achieved an energy resolution between ~5 and ~15 eV at 0.5 keV and count rate capabilities of ~5,000 counts/s per pixel [6,7]. This is sufficient for XAS at synchrotron beam lines.…”

Section: Introductionmentioning

confidence: 99%