The OPAL Discussion Forum

["Rizzoglio Valeria (PSI)" <valeria.rizzoglio AT psi.ch>]

Dear all

I am running a simulation with a graphite degrader that reduces the energy of a proton beam from 250 to 70 MeV. Attached the input file (Degrader_70.in)

The goal of my analysis is to evaluate the emittance growth due to particle-matter interaction. I use the last monitor M_Moliere placed 1 m away from the degrader. The evaluated emittance results a factor 2 bigger than expected. I plot the beam profile (see attachment).
To me this beam profile looks weird. Is there any reason to see the 4 “perfect aligned” tails? Have you ever notice this kind of behaviour? I think this tails are responsible for the wrong emittance evaluation.

Thanks for your help

Valeria

Attachment: Degrader_70.in
Description: Degrader_70.in