A Liquid-Cryogen-Free Superconducting Tunnel Junction X-ray Spectrometer for Astrobiology Research at the Synchrotron

Conference · Sun Jun 15 04:00:00 EDT 2008

OSTI ID:945540

Friedrich, S; Drury, O B; Hertrich, T; Hoehne, J

Superconducting tunnel junctions (STJs) are being developed as energy-dispersive soft X-ray detectors, because they combine the high energy resolution of low-temperature detectors with the comparably high count rates of non-thermal devices. We have built a 36-pixel spectrometer based on 200 {micro}m x 200 {micro}m Nb-Al-AlOx-Al-Nb STJs. It offers an energy resolution of {approx}10 to 20 eV FWHM in the soft X-ray band below 1 keV, a solid angle coverage {Omega}/4{pi} {approx} 10{sup -3}, and can be operated at total rates up to {approx}10{sup 6} counts/s. For STJ operation by non-expert users, we have built a liquid-cryogen-free spectrometer with a mechanical pulse-tube cryocooler and a two-stage adiabatic demagnetization refrigerator. It is fully automated for cooldown to a base temperature of <30 mK in 15 hours, and has a hold time of >3 days between demagnetization cycles for STJ operation at 0.3 K. The STJ spectrometers are used for speciation measurements on dilute samples by fluorescence-detected X-ray absorption spectroscopy, and can achieve sensitivities below 100 ppm. We discuss the spectrometer performance in representative applications on metals in meteorites in the context of geological signatures of biological activity.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 945540
• Report Number(s): LLNL-CONF-404878
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
99 GENERAL AND MISCELLANEOUS
ABSORPTION SPECTROSCOPY
ADIABATIC DEMAGNETIZATION
DEMAGNETIZATION
ENERGY RESOLUTION
METEORITES
PERFORMANCE
SPECTROMETERS
SYNCHROTRON RADIATION
SYNCHROTRONS
X-RAY SPECTROMETERS