Intensity Scan always returns 0 (BSE/SE) despite correct single-point simulation

[Paula]

Hi,

I'm running CASINO v3.3 and consistently getting an empty/blank Intensity Scan result (0.00–0.00 color scale, Backscattering Coefficient: 0, Secondary Yield: 0), even though everything else in the simulation appears to be working correctly. I've tested this across multiple independent projects, so it doesn't seem to be a corrupted file issue.

Setup:
- CASINO v3.3
- Sample: Si cube, tested at multiple sizes (300×300×300 nm and smaller 100×100×100 nm), centered at origin and repositioned so the top surface sits at Z=0
- Beam energy: 5 keV
- Number of simulated electrons: 1000
- Physics models: standard Monsel defaults (Total/Partial Cross Section: Mott by Equation, Browning [1994]; Random Number Generator: Lagged Fibonacci; Directing Cosine: Lowney [1994]; dE/dS: Joy and Luo + Lowney [Monsel]; Ionisation Potential: Joy and Luo [1989])

What works:
- Running a single-point trajectory simulation (Simulation → Start, viewing the 3D trajectory display) gives correct results: I can see elastic/inelastic scattering inside the cube, and the status bar shows non-zero Backscattering Coefficient and Secondary Yield.

What doesn't work:
- Running the "Intensity Scans" node (Microscope and Simulation Properties → XY Scan, e.g. -22 to 22 nm range, 1 nm spacing, ~1684 points) always returns a blank map with 0.00 for everything, and Backscattering Coefficient / Secondary Yield both read 0 in the status bar after completion (Progress reaches 100%, elapsed time is non-trivial, e.g. 2:31, so it does appear to run).
- In "Intensity Graph Properties," the correct region (Box_0 Inside) is checked, and "Backscattered Coefficients" is selected as the signal to display.
- I've tried:
  - Unchecking "Conserve Data For Each Simulated Points (Distributions)"
  - Correcting the Z focal point to match the actual top surface of the sample
  - Disabling the ADF Sensor
  - Increasing simulated electrons to 1000
  - Creating a brand-new simple project (small cube, 3×3 scan grid) — same blank result

None of these changes the outcome; the Intensity Scan always comes back empty.

Is this a known bug in 3.3, or is there a step in setting up/triggering the scan simulation that I might be missing (e.g., a specific way to "activate" scanning mode vs. point mode before running)? Happy to send my .sim file if that helps debug.

Thanks in advance!

[hdemers]

Hi Paula,

When running intensity scan, the results for each scan points is not saved. You need to select the correct Intensity Display->Intensity Distribution Display Options and you should see an image.

If it does not work, add the .sim file in your post and I will look at it.

Regards,
Hendrix