UC Berkeley, Geology & Geophysics Oxford ISIS 300 system
Summary of Specification Testing :
The following is a brief summary of the testing performed on the Oxford ISIS EDS during the past 2 months. Please refer to the specification listing for a complete description of the requirements. For details on the specification test results please contact John Donovan.
1. a) Software. Product is a Windows, VB based application software. Two licenses for both on line and off line use were provided. (satisfactory)
b) Documentation of EDS system control from a user written application. The provided disk (University of Virginia) is not only unfinished but completely undocumented (no source code comments even). We are extremely disappointed with Oxford's performance in this area. When we complained, we were told of a new Oxford product that can provide this feature (API interface) but that it would cost us $3K. (not satisfactory)
c) Standard calibration. (satisfactory)
d) EDS peak markers (satisfactory)
e) Software features. No standard position recall, otherwise complete. (satisfactory)
f) Imaging features. No X-Y scatter plotting of image intensities. (satisfactory)
g) Scale calibration of image. No micron scale bar stored with disk image file. (not satisfactory)
2. a) EDS window vent. Tested several times, once by Cameca engineer explosively. (satisfactory)
b) Carbon detection. Carbon detected was detected in the specified standard, although it is not immediately clear if carbon in matrix or carbon contamination was detected. (satisfactory)
c) EDS resolution. Performed twice by Phil Fox and accepted by John Donovan. (satisfactory)
d) No Fe55 source was supplied by Oxford. Test could not be performed. (not satisfactory)
e) Si double peak intensity.
Using Be window, 180 nA, 15 KeV on Si metal
Process time Si peak cps Si double peak cps % of parent peak
1 6310 107 1.7
Using Be window, 15 nA, 15 KeV on Si metal
Process time Si peak cps Si double peak cps % of parent peak
6 880 4 0.45
The ISIS system cannot meet the specification except at the highest resolution process time. Since no process time was specified the result is OK. (satisfactory)
f) Count linearity. The ISIS system really shined here. Less than 0.01 % deviation measured up to 50% deadtime (up to 18K cps). (satisfactory)
g) Internal fluorescence. Measured 0.1 % at 15 KeV, 30 nA on NiO. (satisfactory)
h) Energy drift with time/deadtime. After 10 days, the energy drift as measured on Ni Ka on NiO was 0.14% (one channel). The energy calibration from 2% to 90% deadtime was measured (at best resolution). There was no shift up to 50% deadtime and a 1 channel shift (or 20 eV) at 90% deadtime. (satisfactory)
i) Deadtime under 70% at 30K cps. Measured 31K cps at 15 keV and 449.3 nA. This produced at deadtime of 50% on the system at best acquisition rate, well under the 70% specification. (satisfactory)
H. Quantitative tests
Although UCB will use the EDS system primarily for qualitative analysis, it is important that at least semi-quantitative analysis can be performed. Using pure oxide standards when possible (to stress the matrix correction) the following analyses were performed on well characterized standards.
Test #1 (orthoclase)
Na Al Si K Fe
std nepheline Al2O3 SiO2 nepkeline magnetite
meas. .83 8.55 30.29 12.56 1.33
publ. .68 8.85 30.29 12.86 1.46
var% 29. -3.5 0.0 -2.3 -8.9
Test #2 (labradorite)
Na Al Si K Ca Fe
std nepheline Al2O3 SiO2 nepkeline diopside Fe3O4
meas. 2.98 16.01 23.76 .07 9.35 .51
publ. 2.84 16.34 23.96 .10 9.58 .32
var% 4.8 -2.1 -.8 -30. -2.4 59.
Major elements appear to be determined within 5% (the specification). (satisfactory)
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