--optics Option

[Laurie Nevay]

Several options are required to be set correctly in order to create a suitable optical comparison between a BDSIM model and an optical description of a machine such as MADX. We should provide a simple executable option that sets all of these options to avoid incorrect comparisons.

Options to be set:

• stopTracks=1
• em physics to allow particles to interact with matter, ie be killed with stopTracks
• strong physics cuts to prevent secondaries should they arise
• build geometry with open collimators
• build geometry with increased aperture
• use apertureType="circularvacuum" - faster tracking; aperture still increased to extend applicable field region
• sample, all;

We also have the possibility of storing a special optics structure in the output that would be more optimised (reduced analysis time) - perhaps all events per sampler (sampler as 'entry' in ROOT file) rather than general all samplers per event. Optics is a special case where we have a very large number of samplers unlike conventional physics studies.

[Jochem Snuverink]

strong physics cuts to prevent secondaries should they arise

one can use option, stopSecondaries = 1; for this.