Oral Presentation 26th ACMM “2020 Visions in Microscopy”

WDS(SD) - Reasons Why to Replace the Proportional Counter (PC) in a Wavelength Dispersive Spectrometer (WDS) with a Silicon Drift Detector (SDD)  (#16)

Richard Wuhrer 1 , Kenneth Moran 2
  1. Western Sydney University, Parramatta, NSW, Australia
  2. Moran Scientific , Goulburn, NSW, Australia

Traditional wavelength dispersive spectrometers (WDS’s) design utilises a gas counter (GC) or proportional counter (PC) [1-3]. The traditional GC-WDS has many issues including things like the gaseous detector resolution and stability [1-3]. The electron microprobe operator using WDS has to be meticulous in monitoring items such as gas flow, gas purity, gas pressure, noise levels of baseline and window, gas flow proportional counter (GFPC) voltage levels, count rate suppression, anode wire contamination and other detector parameters [1].

 

The superiority of a WDS(SD) is easily seen once in operation [3-6]. The incorporation of the SDD has been found to provide the following:

  1. No more peak shift with count rate.
  2. No more high order diffraction included in collection.
  3. No more interferences from extraneous X-Rays.
  4. No more peak shift (drift) with air pressure.
  5. No more slowly deteriorating proportional counter due to gas contamination.
  6. No more gas. Better Vacuum.
  7. Better peak to background ratio’s (P/B).
  8. Better energy resolution.
  9. Better low energy performance (improve the light and mid element range)
  10. Ability to do analysis without measuring backgrounds.

 

Any one of these is reason to go to a solid state detector, WDS(SD), (SDD in WDS). But, all ten points would be silly and even irresponsible not to upgrade. The first 9 points have to be done correctly, before considering point 10. This presentation will cover advantages and current limitations of WDS(SD) as well as our current research on background determination.

 

  1. R. Wuhrer and K. Moran, IOP Conf. Series: Materials Science and Engineering 304 (2017).
  2. K. Moran and R. Wuhrer, Microsc. Microanal. 22 (Suppl 3), 2016, p92-93.
  3. R. Wuhrer and K. Moran, Microsc. Microanal. 23 (Suppl 1), 2017, p1048-1049.
  4. K. Moran and R. Wuhrer, Microsc. Microanal. 24 (Suppl 1), 2018, p756-757.
  5. K. Moran and R. Wuhrer, Silicon Drift Detector Incorporated into Wavelength Dispersive Spectrometer (SD-WDS) – Allowing Bremsstrahlung Determination by Theoretical Calculation, EMAS 2019, Thondheim Norway.
  6. K. Moran and R. Wuhrer, Microsc. Microanal. 25 (Suppl 2), 2019, p2316-2317.