Geo,

Reset the 93 keV energy span to 64 keV, you’re losing almost half of your energy resolution which you’ll need down in the low 15 keV energy range. Set the gain for a 64 keV span with 2048 channels.

Dud

?

?

Theory says Fe and Ca should XRF with quite low energy excitement = "just above the K-edge".
. Fortunately the test was left as-is last night, so it was easy to redo and save example .mca's. so here's a fresh set of .mca that show the reality of this skimming arrangement.?

Note the Ca, Fe and Ba peaks as exemplars. Also remember the possibility of stray "W" L-lines due to the Si-PIN collimator..?

The .mca marked as "ALLkVp" should contain the others too, if not I've included each individual .mca's.

Once I'm able to strike this test, I'll take a repeat this test wiht the standard 45 degree arrangement of exciter and detector angle.
Then a direct Gamma Scan of the beam itself to see how the internal tungsten target characteristic L lines look. If they are being filtered internally that would explain a lot.

Geo