Uniform beam illumination of a single pixel

Feature Requests / Discussions
1

Dear developers,

is it possible to have a uniform beam illumination of a pixel (e.g. the central pixel of a matrix)? What I mean is that I would like to have tracks perpendicular to the sensor surface (and for this I can set the beam_divergence = 0mrad 0mrad, I suppose) and also uniformly distributed over the pixel surface (as if the x,y initial coordinates were randomly extracted with a uniform distribution over the pixel surface, or as if I had a source that produces a beam with a uniform profile. This is also effectively different than setting the gaussian beam_size to a value much larger than the pixel pitch, because in this case I would have a very broad gaussian profile, so an almost “uniform” beam over the central pixel, but the particles would very often hit the matrix outside of the central pixel…! So I would like to use a beam with a uniform profile, but with a size restricted to e.g. one single pixel). How do you suggest I can do?

Thanks a lot and best regards,
Lorenzo

2

Hi Lorenzo,

you can find the manual entry for the DepositionGeant4 module here:
https://project-allpix-squared.web.cern.ch/project-allpix-squared/usermanual/allpix-manualch7.html#x8-900007.6

There is the possibility of a square beam. I think your pixels are squared, right? Otherwise you would need to add a similar rectangular implementation, which should be rather simple to do.
For a squared beam without divergence that would be …

source_type = "square"
square_side = 1mm
square_angle = 0mrad

Cheers
Paul

3

Hi @pschutze,

Thanks a lot!!

Best,
Lorenzo