Hello! In the egspp (EGS C++) geometry package there is a linac geometry example. Maybe you could adapt it to your problem. Best regards!

Thanks for the advice but I  use  EGSnrc in Windows. I cannot use EGS C++

Yours faithfully

Thanks for the advice but I  use  EGSnrc in Windows. I cannot use EGS C++

Yours faithfully

You can work with C++ geometry library on Windows:

"System requirements

EGSnrc works on GNU/Linux, Unix, Mac OS X and Windows. EGSnrc is a set of source files and utilities to build your own Monte Carlo simulations. "

http://www.nrc-cnrc.gc.ca/eng/solutions/advisory/egsnrc_index.html

I used this  EGSnrc and I think I input data of scattering foil mistake.

when I preview see on picture