Multiparameter Multichannel Analyzers / Questions and Answers

I would like to use the MPA-3 for building a spectra containing the sum of the counts from several smaller detectors to get a "superdetector". Is that possible?

Yes, it is now possible. See following snippet out of the Readme.txt: 

MPA-3 Server version 1.87 (Jul-21-2010):

- It is now possible to create spectra containing the sum of counts from several ADC's. It can be used to create a "superdetector" from multiple smaller detectors. It doesn't matter if the ADC's are used in single or coincidence mode, the sum spectra is calculated from the complete single spectra.

Choose Spectra... from the MPANT options menu or the corresponding toolbar icon, click "Add Calc..." and select the "Or = Sum of counts" radio button. 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 spectra, 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 spectra.

By the way, the SPA-3 software has that capability since the beginning. You know, that the SPA-3 software works with the MPA-3 hardware and can be downloaded from the MPA-3 download page.

Multiparameter Multichannel Analyzers