Moxtek now has a full energy dispersive X-ray fluorescence detector solution with Moxtek's XPINŽ detectors and our new MXDPP-50
electronics. We will present characterization methods and a few measurement details of the DPP with Moxtek's XPINŽ detectors.
One objective for Moxtek has been to develop a DPP to work with our X-ray detector products. This has been achieved with the
release of the new MXDPP-50 electronics in 2013, which comes in two versions, a boxed version (Figure 1) and a bare board
Figure 1: Outlines the basic hardware for DPP and X-ray detector functional testing.
A second objective has been to develop automated testing to fully characterize our DPP and X-ray detectors. The basic testing
method is an automated test which multiple different DPP and XPIN detector settings are surveyed. The test generates a report
on the performance over all the settings. This allows for rapid, consistent, and meaningful feedback, which has resulted in
Moxtek more fully understanding the functionality of our DPP in development. This automated test allows for a "quick" test
of our DPP and/or X-ray PIN detector over 4 to 14 standard peaking time settings, which takes about 15 to 30 min. This automated
test also allows for extensive tests, takes over 16 h or more, over an array of hundreds of settings changing multiple input
parameters, such as peaking time, input count rate, detector temperature, and so on.
The basic hardware used in this automated testing is outlined in Figure 1. The DPP controls attributes such as the peaking
time, the detector's temperature, the detector's high voltage, and more. The linear stage automatically positions a Fe55 isotope
source to set a desired detector dead time (or detector input count rate). All the hardware is controlled in a LabVIEW program
which automates all the hardware during the survey of desired settings. After each spectra is taken, over 150 independent
variables are processed and recorded from both the spectra and detector, such as the Fe55 peak FWHM (for both Fe55 Kα, and Kβ), Fe55 channel position, various peak-to-background ratios, detector internal temperature, detector power draw, input count rate
(ICR), output count rate (OCR), and may other variables.
The automated test generates a report at the end comparing several input parameters against each other. The information generated
is far greater than can be shown here (1). Table I shows a sub-set of information collected in automated test collected on
a XPIN 6 mm2-BT detector at typical temperature of -35 °C and a detector dead time of 50%. To build statistically relevant
results, five spectra were taken at each setting.
Table I: Outlines a small sub-set of information collected in the automated test
Many other functional dependencies are readily available as well. For example, critical variables such as the Fe55 Kα FWHM peak width can be expressed as a function of detector temperature, or the detectors count rate (1).
The MXDPP-50 is a digital pulse processor which now gives Moxtek a complete X-ray energy dispersive detector solution. Moxtek
has been able to rigorously test the MXDPP-50, with our new suite of automated testing routines, giving a considerable amount
of information quite quickly. This testing has shown the MXDPP-50 works well and works consistently from unit to unit (1).
(1) Link to DXC2013 poster: http://www.moxtek.com/x-ray-publications.html.
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