Superconducting High-Resolution X-Ray Spectrometers For Chemical State Analysis Of Dilute Samples
- Advanced Detector Group, Lawrence Livermore National Laboratory, L-270, Livermore, CA 94550 (United States)
- Physics Biosciences Division, Lawrence Berkeley National Laboratory, MS 6-2100, Berkeley, CA 94720 (United States)
- Department of Applied Science, University of California, Davis, CA, 95616 (United States)
Cryogenic X-ray spectrometers operating at temperatures below 1 K combine high energy resolution with broadband efficiency for X-ray energies up to 10 keV. They offer advantages for chemical state analysis of dilute samples by fluorescence-detected X-ray absorption spectroscopy (XAS) in cases where conventional Ge or Si(Li) detectors lack energy resolution and grating spectrometers lack detection efficiency. We are developing soft X-ray spectrometers based on superconducting Nb-Al-AlOx-Al-Nb tunnel junction (STJ) technology. X-rays absorbed in one of the superconducting electrodes generate excess charge carriers in proportion to their energy, thereby producing a measurable temporary increase in tunneling current. For STJ operation at the synchrotron, we have designed a two-stage adiabatic demagnetization refrigerator (ADR) with a cold finger that holds a 3 x 3 array of STJs inside the UHV sample chamber at a temperature of {approx}0.1 K within {approx}15 mm of a room temperature sample. Our STJ spectrometer can have an energy resolution below 10 eV FWHM for X-ray energies up to 1 keV, and has total count rate capabilities above 100,000 counts/s. We will describe detector performance in synchrotron-based X-ray fluorescence experiments and demonstrate its use for XAS on a dilute metal site in a metalloprotein.
- OSTI ID:
- 20653123
- Journal Information:
- AIP Conference Proceedings, Vol. 705, Issue 1; Conference: 8. international conference on synchrotron radiation instrumentation, San Francisco, CA (United States), 25-29 Aug 2003; Other Information: DOI: 10.1063/1.1757962; (c) 2004 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ABSORPTION SPECTROSCOPY
ADIABATIC DEMAGNETIZATION
ALUMINIUM OXIDES
CHARGE CARRIERS
CHEMICAL STATE
COUNTING RATES
EFFICIENCY
ELECTRODES
ENERGY RESOLUTION
EV RANGE 01-10
FLUORESCENCE
FLUORESCENCE SPECTROSCOPY
KEV RANGE 01-10
LI-DRIFTED SI DETECTORS
NIOBIUM COMPOUNDS
PERFORMANCE
REFRIGERATORS
SOFT X RADIATION
SUPERCONDUCTING DEVICES
SUPERCONDUCTING JUNCTIONS
SYNCHROTRON RADIATION
SYNCHROTRONS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0273-0400 K
TUNNEL EFFECT
X-RAY SPECTRA
X-RAY SPECTROMETERS
X-RAY SPECTROSCOPY