Valeri D. Saveliev

A very large area (100 mm 2 ) silicon drift detector for EXAFS applications

A 100 mm2 silicon drift detector (SDD) has been developed in an effort to improve the solid angle of our Vortex® SDD. The 100 mm2 SDD features the same basic structure as our smaller area (50 mm2) devices and possesses the same advantages, including low noise, high count rates, and excellent energy resolution with thermoelectric cooling. The 100 mm2 SDD is ideal for low or high count rate applications in which the x-rays of interest are occurring over a large solid angle, such as are encountered in TXRF (total reflection x-ray ray fluorescence), EXAFS (extended x-ray absorption fine structure) and other synchrotron applications. The new 100 mm2 SDD has been evaluated in an EXAFS experiment at the National Synchrotron Light Source at Brookhaven National Laboratory, which investigated the local atomic structure surrounding Mn in a LaMnO3/SrMnO3 superlattice. Results show that the new large area SDD delivers excellent energy resolution, high peak-to-background and significantly reduces the data collection time for these types of sensitive EXAFS measurements.

Large Solid Angle 50 mm 2 SDD for TEM Applications

Concomitant with this high spatial resolution capability is the need to optimize ancilliary detector systems to maximize the information collected during any microanalytical investigation. While SDDs have shown their remarkable high count rate performance, there remains a second and equally important advantage to these detectors. The new generation of SDDs offers a range of alternate geometries, which are particularly useful in electron-optical beam-lines. A customized SDD can significantly increase the collection efficiency over that of traditional Si(Li) systems, and also over an SDD which is attached to the EM column in the common up-angle geometry. Typical solid angles for many beam-lines with traditional Si(Li) detectors, with areas 10 -100 mm, are in the range of 0.01-0.1 sR [2].

Low Energy X-Ray Detection with a Silicon Multi-Cathode Detector for Microanalysis

This paper presents several aspects of our design efforts toward the development of a large-area, high energy resolution analytical x-ray spectrometry system for x-ray microanalysis and x-ray spectrum imaging [1]. The spectrometer achieves excellent energy resolution and is capable of operating at very high counting rates (up to 600,000 cps throughput). The Vortex-EM spectrometer is based on a thermoelectrically-cooled silicon multi-cathode detector (SMCD), which is a type of “drift” detector [2-3]. The detector is specifically designed for optimal performance in the 0.2 40 keV range. Recent advancements in the detector design enhance the low energy x-ray performance. The spectrometer utilizes a non-cryogenic design, operating with thermoelectric cooling and passive heat transfer to the ambient without using any moving parts; a photograph of the spectrometer is shown in Figure 1.