Issues concerning solid state detectors for EXAFS. [X-ray Absorption Fine Structure Spectroscopy]

Conference · Tue Oct 01 04:00:00 EDT 1991

OSTI ID:5949209

Rossington, C S; Giauque, R D; Jaklevic, J M

Fluorescence extended x-ray absorption fine structure spectroscopy (EXAFS) is a commonly used technique in conjunction with x-ray synchrotron radiation for studying the local atomic structure of dilute elements in biological, geological and materials systems. Due to the nature of the EXAFS technique, and the difficulties associated with the detection of low energy x-rays, EXAFS has been used primarily in the energy range above 5 keV. However, there are a number of elements of interest with K- or L-absorption edges below 5 keV, which have not been easily accessible with existing EXAFS instrumentation. Several characteristics of solid state detectors must be optimized for use in low energy EXAFS measurements. The detector entrance window, or dead layer,'' must be as thin as possible to minimize the attenuation of the fluorescent signal. The detector spectral backgrounds must be minimized so that the tailing background on the low energy side of the scattered photopeak is as low as possible to maximize the S/N of the fluorescent photopeak. Based on our work, a thin Pd surface barrier contact on a Si(Li) detector offers the thinnest detector dead layer and also the lowest spectral background for the Si(Li) and Ge detectors studied to date. To maximize the S/N, the detectors must be operated at as high a count rate as possible, without compromising detector energy resolution. High count rates can be achieved using multiple detector arrays; close packing of the detector elements can further increase the S/N by utilizing the best'' portion of the scattered polarized synchrotron beam.

• Research Organization: Lawrence Berkeley Lab., CA (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5949209
• Report Number(s): LBL-31419; CONF-9109322--1; ON: DE92004173
• Country of Publication: United States
• Language: English

Related Subjects

440100* -- Radiation Instrumentation
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ABSORPTION
DETECTION
ELEMENTS
GE SEMICONDUCTOR DETECTORS
K ABSORPTION
LI-DRIFTED DETECTORS
LI-DRIFTED SI DETECTORS
MEASURING INSTRUMENTS
METALS
OPENINGS
OPTIMIZATION
PALLADIUM
PLATINUM METALS
RADIATION DETECTION
RADIATION DETECTORS
SEMICONDUCTOR DETECTORS
SENSITIVITY
SI SEMICONDUCTOR DETECTORS
SIGNAL-TO-NOISE RATIO
SURFACE BARRIER DETECTORS
TRANSITION ELEMENTS
WINDOWS
X-RAY DETECTION