Editing XRF SumPeak Processing (section)

=== Background ===

Sum peaks are a result of to xray photons arriving at the detector at the same time.  The pulse energy that is measured is twice the energy of a single photon, hence the name sum peak.  The FP
algorithm attempts to remove the sum peaks but finding the primary peak and then subtracting signal from the area of the spectrum double the primary peak energy.

Here you can see a single pulse, happens to be silver:
[[file:scope_singlepulse.jpg|Single Ag pulse]]

Now, are a couple of views of two pulses creating a sum peak.

[[file:scope_sumpeakpulse1.jpg|Sum Peak, Ag pulses]]
[[file:scope_sumpeakpulse2.jpg|Nearly Sum Peak, Ag pulses]]

If a second pulse occurs very early after the start of the first pulse, it will be accepted by the pulse processor and will show up in the spectra.  If the pulse occurs slightly later then the second pulse will be rejected and will not show up as a peak in the spectra.  This means that our post processing is the only way we have of determining if a peak is a true peak or a sum peak.

[[file:sumpeak1.jpg|Sum peak diagram]]