The OPAL Discussion Forum

["Dragos Constantin" <dragos.constantin AT varian.com>]

Hi All,
In the AWAGun example I would like to get rid of the particles that are being
pushed back by the gun RF field. I have tried to use a collimator element with
zero aperture before the GUN source but I get segfaults.

What is the best way to discard from the simulation the particles with a
negative pz?

Thanks,
Dragos