Dear John,
Sorry I didn´t get back to you sooner, but I have had some experimental and design work to do in addition to the Geant4 stuff. The line about UI session types says:
Available UI session types: [ Win32, GAG, csh ]
on the windows PC. I can check what it says on the Linux later.
A couple of problems I have are that
- I am using a 3D grid of points to represent the electric field. As the field considerably varies in strength depending on how far away the tip is, I use different grids at different scales. However, when I launch the electrons from the tip, the surface of the tip does not coincide with any grid points. Hence the electric field near the tip is interpolated incorrectly as the field inside the tip is zero. I can get around this for the moment by launching electrons from the sample surface. If I need to launch electrons from the tip, the current plan is to launch using COMSOL and note where the electrons strike the sample surface and then launch electrons from the positions as stored by COMSOL.
- As a test, I thought I would launch electrons using COMSOL and Geant4 from the same point on the surface with the same conditions. I should see the same results (more or less) for electrons flying through the vacuum. However, at the moment I do not. Secondary electrons generated within the material seem to fly in arcs if they escape into the vacuum, but primary electrons do not seem to feel the electric field and fly in straight lines right out of the tip-sample region (even for very low energies).
- I still have the problem with the program crashing. I just exit the program each time if I want to view a new set of electron trajectories.
Best Wishes
Chris