FAST ComTec MCA4A, User Manual

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Software Description
In the "Sum of counts" dialog you can select which ADCs will contribute to the superdetector. It is
recommended to enable "Use Calibration" and to perform a careful calibration of all selected ADC's:
Make a short acquisition using a pulser or a calibration source so you get a peak in each used ADC. In each
ADC zoom into the spectrum, then by keeping the right mouse button pressed drag from left to right over the
peak to mark a fit region and click on the "Fit" toolbar icon to make a Gaussian peak fit. Note the position
value of the peak in the first ADC. For the first ADC you can just enable "Use Calibration" in the calibration
dialog and use the standard parameters p0=0, p1=1. In the next ADC enter two calibration points: for the first
point enter 0 for the Channel and 0 for the value and click "Add>>". For the second calibration point use the
result of the fit: Click "Fit" to enter the Channel value of the fitted peak position. For the "Value" enter the fit
result of the peak position in the first ADC. Click "Calibrate" and enable "Use Calibration", then click "OK".
Proceed this way until all used ADCs are calibrated. You will immediately get the effect: Instead of a peak
multiplet you will see a single sharp peak in the sum spectrum.
Another good method to enter the calibration is to draw in the second spectrum a ROI over the peak by
keeping the right mouse button pressed and clicking the “Create ROI” icon , then select “Region..Edit”
item from the MPANT menu, select the ROI in the list, enter the fit result from the first spectrum for the value
of the Calibration Peak and click “Modify” and “OK”. Then choose Region..Auto Calib in the MPANT menu.
The automatic generated spectra name is for example "OR_3_C". The 3 is here an hexadecimal bit pattern
indicating that ADC1 (bit 0) and ADC2 (bit 1) contribute to the OR sum. The C at the end of the name means
that "Use Calibration" is enabled.
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Fig. 4.24: Sum of counts spectrum before and after calibration