Energy-resolving superconducting x-ray detectors with charge amplification due to multiple quasiparticle tunneling

Mears, C. A.; Labov, S. E.; Barfknecht, A.T.

doi:10.1063/1.110286

Cited by 87 publications

(36 citation statements)

References 11 publications

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“…The devices are fabricated at Conductus, Inc. in Sunnyvale, CA, using a modified photolithographic trilayer process (Barfknecht et al, 1991). Details of the fabrication process have been published elsewhere (Mears et al, 1993). The STJ detectors are operated in a liquid helium cryostat with an adiabatic demagnetization refrigerator (ADR) stage.…”

Section: Resultsmentioning

confidence: 99%

“…For Nb-based STJs, the statistics of the initial charge generation ultimately limit the resolution to values between 0.8 and 1.7 eV FWHM for X-ray energies between 0.2 and 1 keV (Kraft et al, 1998). In most practical devices, additional fluctuations in the number of tunneling events reduce the theoretically attainable resolution in that energy range by a factor of ≈2.5 (Mears et al, 1993).…”

Section: Stj Operating Principlementioning

confidence: 99%

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

et al. 1998

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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.

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Section: Resultsmentioning

confidence: 99%

Section: Stj Operating Principlementioning

confidence: 99%

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

et al. 1998

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“…Since the current pulse shape could not be modeled by self-recombmation alone, we repeated the fits using the more complicated model in equations (5) and (6). Estimates of z*loss and M2 were calculated from the fits.…”

Section: Self-recombination and Unwanted Trapping Modelmentioning

confidence: 99%

<title>Nonequilibrium dynamics in superconducting tunnel junction detectors</title>

et al. 1994

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L a w r e n c e L i v e r m o r e N a t i o n a l L a b o r a t o r y U n i v e r s i t y of C a l i f o r n i a ABSTRACTSuperconducting tunnel junctions have the potential to serve as high-resolution, high-efficiency x-ray detectors for astrophysical and industrial applications. When irradiated by X rays, each X ray excites over lo6 charge carriers which cause the detector to generate a pulse of current. We present an analysis of pulse shapes from detectors we have constructed and operated. We fit the decay of the current pulse to a simple model that considers two classes of carrier loss. One model considers only the normal recombination of the charge carriers with themselves, the other included additional losses due to recombination sites in the within the detector medium. We found that both mechanisms must be taken into account. We also found a small variation in pulse shape depending on which layer of the tunnel junction absorbed the X ray. We expect that this analysis will be a useful tool in comparing different detector designs and operating conditions.

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“…The theoretical limit for the FWHM energy resolution of an X-ray spectrometer based on the measurement of the X-ray induced quasiparticle excitations in pure Nb has been calculated to be about 5 eV at 6 keV incident X-ray energy (Rando et al, 1992). In practice, additional statistical¯uctuations associated with the trapping, tunnelling and recombination processes (Mears et al, 1993;Goldie et al, 1994) may degrade this limit, but a resolution of $10 eV at 6 keV should be obtainable.…”

Section: Introductionmentioning

confidence: 99%

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

Frank

Mears

Labov

et al. 1998

J Synchrotron Radiat

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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.

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Energy-resolving superconducting x-ray detectors with charge amplification due to multiple quasiparticle tunneling

Cited by 87 publications

References 11 publications

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

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

<title>Nonequilibrium dynamics in superconducting tunnel junction detectors</title>

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

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