Different incident angle

Simulation / Configuration Questions
1

Dear developers,

I would be interested in performing some simulations with different incident angle of the particles on the sensor plane. At the moment I’m using the DepositionGeant4 module with:

source_type = “square”
square_side = 25um

in order to illuminate uniformly only the central pixel of a matrix.
I noticed the parameter square_angle : Cone opening angle defining the maximum submission angle, which I don’t think is the proper parameter to be changed for my purpose.
Maybe I’m missing something or do you have any suggestion on how to perform this kind of simulation?

Thank you in advance,
Chiara

2

Hi @cferrero

it might sound like an odd solution, but I would simply rotate the detector with respect to the source.

If you want, you can also do this from the command line if you want to for example scan over different angles:

for i in {0..45}
do
    allpix -c config.conf -g MyDetector.orientation="0deg {$i}deg 0deg"
done

Does that solve your issue?

Cheers,
Simon

3

Dear @simonspa,

thanks a lot for your suggestion, I think it will be a possible option to run the simulations in this way. Anyway, I had this error when I tried to run in the container the command that you suggested:

for i in {0…1}
do allpix -c examples/example.conf -g detector1.orientation=“0deg {$i}deg 0deg”
done

(FATAL) Error in the configuration:
Could not convert value ‘0deg {1}deg 0deg’ from key ‘orientation’ in section ‘detector1’ to type ROOT::Math::DisplacementVector3D<ROOT::Math::Cartesian3D, ROOT::Math::DefaultCoordinateSystemTag>: conversion not possible
The configuration needs to be updated. Cannot continue.

Do you know how can I manage it?

Thanks again,
Chiara

4

Hi @cferrero

just a typo by me. In bash this should be

for i in {0..45}
do
    allpix -c config.conf -g MyDetector.orientation="0deg ${i}deg 0deg"
done
5

Thanks a lot @simonspa!

At this point, since I’m rotating the pixels, I have to change the square_side parameter according to the rotation angle, in order to illuminate always a window of 25 um, taking into account the term cos(alpha). But in this way I will reduce also the illumination on the other coordinate (the x for me), as the source is squared.
Is there the possibility to keep the x of the source = 25um and change only the y? i.e. making a rectangular source?

Cheers,
Chiara

6

Hi @cferrero

I’m not sure why you need this exact matching with the pixel area. Why don’t you make the source bigger and

  • ignore all other pixels
  • or make your detector just 1x1 pixels big
  • or analyze all pixels

?

Cheers,
Simon