Scanning Electron Microscopy and X-Ray Microanalysis

433 24

145 eV

128 eV

122.5 eV

OCR (1000 ns)

OCR (220 ns)

OCR (470 ns)

Single 10-mm^2 detector,

Max OCR = 130 kHz

SDD-EDS Throughput

1.4 10^6

1.2 10^6

1.0 10^6

8.0 10^5

6.0 10^5

4.0 10^5

2.0 10^5

0.0 10^0

0 10^0 1 10^6 2 10^6

Input Count Rate (X-rays/second)

Output Count Rate (X-rays/second)

3 10^6 4 10^6 5 10^6

> 500 kHz

> 200 kHz

Combined output

of four 10-mm^2 detectors

> 1.2 MHz

Ideal no deadtime

response

. Fig. 24.22 Throughput of an
SDD-EDS system consisting of
four 10-mm^2 detectors with the
outputs summed at three differ-
ent operating time constants

SDD-EDS Throughput

6e+5

5e+5

4e+5

3e+5

2e+5

1e+5

5.0e+5 1.0e+6 1.5e+6 2.0e+6 2.5e+6

Input Count Rate (counts/s)

Output Count Rate (counts/s)

0

0.0

. Fig. 24.23 Example of XSI
mapping at such high through-
put level that count rate based
artifacts appear: measured OCR
vs. ICR response for an SDD-EDS,
showing the same OCR for two
different ICR values, which could
represent different concentra-
tions of a highly excited element

24.4 · Strategy for XSI Elemental Mapping Data Collection