National Synchrotron Light Source Seminar

"Very-High-Energy-Resolution X-ray Detectors for Synchrotrons"

Presented by W. Bertrand (Randy) Doriese, National Institute of Standards and Technology, Boulder, CO

Tuesday, November 13, 2007, 11:00 am — Seminar Room, Bldg. 725

The quantum sensors group at NIST Boulder has demonstrated cryogenic photon detectors with energy resolutions of 2 eV (FWHM) up to 1.5 keV, 2.4 eV up to 6 keV, and 22 eV up to 100 keV. These detectors, transition-edge-sensor (TES) microcalorimeters, have the potential to become powerful new detectors at synchrotron light sources. A TES microcalorimeter is a thin superconducting film, electrically biased in its resistive transition. Heat deposited by an incident photon increases the temperature and resistance of the TES. The resulting pulsed decrease in the device current, amplified by a SQUID ammeter, is used to measure the energy of the photon. TESs combine the high energy resolution associated with wavelength dispersive instruments with the broadband response of energy-dispersive detectors. In addition, although most development has focused on photon detection, TESs are also inherent energy-dispersive detectors of any other particle type, including electrons, atoms, and alpha particles.

Recent advancements in arraying TESs into two-dimensional cameras have removed the historical drawbacks to deploying TES detectors at synchrotrons. These drawbacks included small collecting area (pixels can range from a few hundred um to 1.5 mm on a side), and slow response (maximum count rates per pixel can range from a few hundred Hz to a few kHz). In this talk, I’ll discuss an instrument under development at NIST that is to be tested at the NSLS. The rough specifications of this 128-pixel instrument are 1 eV resolution over the 200 eV – 2 keV spectral band, 5.1 mm2 total collecting area, and ~100 kHz maximum total count rate. I’ll pay special attention to trade-offs that can be made among count rate, collecting area, and energy resolution as this and future instruments are designed. I will also discuss applications of TESs at synchrotrons and elsewhere.

Hosted by: Daniel A. Fischer

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