Moxtek’s objective has been to design a DPP to work with its X-ray detector products. In realization of this objective, the company released the new MXDPP-50 electronics in 2013, which is offered in a boxed as shown in Figure 1 and a bare board OEM version.
The second objective has been the development of automated testing to completely characterize its DPP and X-ray detectors. The basic testing method is an automated test by which multiple different XPIN and DPP settings are surveyed. From the rest a report is obtained on the performance over all the settings. This enables quick, reliable and meaningful feedback resulting in Moxtek understanding more fully the functionality of its DPP in development. This automated test enables a quick test of its DPP and orx-ray PIN detector over standard peaking time settings of that takes around 15 to 30mins. This automated test paves the way for extensive tests, taking over more than 16h over an array of hundreds of settings that change multiple input parameters, such as input count rate, peaking time, detector temperature, etc. This article presents characterization methods and a few measurement details of the DPP with Moxtek’s XPIN® detectors.
Experimental Conditions
Figure 1 shows the basic hardware used in this automated testing. Attributes such as the detector’s temperature, the peaking time, the high voltage of the detector are controlled by the DPP. A Fe55 isotope source is automatically positioned by the linear stage to set a desired detector dead time (or detector input count rate). A LabVIEW program that automates all the hardware while surveying desired settings is used for hardware control. After taking each spectra more than 150 independent variables are processed and recorded from both the spectra and detector, such as theFe55peak FWHM (for both Fe55Kα& Kβ), Fe55 channel position, detector internal temperature, various peak-to-background ratios, detector power draw, input count rate (ICR), output count rate (OCR), and may other variables.
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Figure 1. Outlines the basic hardware for DPP and X-ray detector functional testing.
Results
The final report generated by the automated test compares several input parameters against each other. The generated information is much greater than can be shown here. Table 1 shows a sub-set of information collected in automated test collected on a XPIN 6mm2-BT detector at typical temperature of -35°C and a detector dead time of 50%. Five spectra were taken at each setting to build statistically relevant results.
| Peaking time (usec) |
2 |
4 |
5 |
8 |
16 |
20 |
| Fe55 FWHM (eV) |
276.1 |
219.5 |
206.8 |
187.5 |
170.1 |
165.3 |
| Fe55 FWHM standard deviation (eV) |
0.12 |
0.19 |
0.17 |
0.19 |
0.3 |
0.36 |
| Peak-to-Background@2kV (Ratio) |
3068.6 |
4521.8 |
5260.7 |
5629.2 |
6151.6 |
6587.7 |
| Peak Channel Position |
1209.2 |
1229 |
1221.3 |
1216.8 |
1206.5 |
1205.5 |
A number of other functional dependencies are readily available as well. For instance, critical variables such as the Fe55 Kα FWHM peak width can be expressed as a function of detector temperature, or the detectors count rate.
Conclusions
The digital pulse processor, the MXDPP-50 now offers Moxtek a complete X-ray energy dispersive detector solution. Moxtek can rigorously test the MXDPP-50, with its new suite of automated testing routines, giving a considerable amount of information quite quickly. This testing has shown the MXDPP-50 workswell and works consistently from unit to unit.
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This information has been sourced, reviewed and adapted from materials provided by Moxtek, Inc.
For more information on this source, please visit Moxtek, Inc.