Resolution Measurement And Calibration; Figure 1. Alpha Duo Sample Chamber; Figure 2. Alpha Mega Sample Chamber - Ametek ORTEC Alpha Duo Hardware User's Manual

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Figure 1. Alpha Duo Sample
Chamber
3.4

RESOLUTION MEASUREMENT AND CALIBRATION

The measurement of alpha-particle resolution should be performed in a vacuum with a uniform, ultra-
thin source located at a source-to-detector distance at least equal to the detector diameter. Using old
or inferior sources may cause apparently poor resolution and can lead to detector contamination due
to recoil sputtering. When using a source in an Alpha chamber, either for resolution measurement or
system calibration, the following steps should be used for best results.
1) Place the source on a sample tray and insert it into the Alpha chamber. Placing the source as
far as possible from the detector helps reduce any solid-angle-related and/or count-rate
problems.
2) Evacuate the chamber.
3) Set the target bias and turn the bias on with the controls on the High Voltage property page in
MAESTRO (see Section 3.5.5) or the Hardware panel in AlphaVision. Wait 2 minutes.
4) Accumulate a peak containing at least 1,000 counts in the peak channel.
5) Determining the resolution requires measurement of the full-width at half maximum (FWHM) of
the peak. Use the Peak Info command in MAESTRO or the PeakSearch and PeakFit features
in AlphaVision.

Figure 2. Alpha Mega Sample Chamber

CHAPTER 3. OPERATION
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