7.31 inelastic_scattering

• type: major action command
• function: perform simulation of inelastic scattering at multiple s locations, for use in computing inelastic gas scattering lifetime and loss distribution
• sequence: must follow run_control.
• Command syntax, including use of equations and subcommands, is discussed in 7.2.
• notes:
  • Only available in Pelegant.
  • Data may be postprocessed with the command inelasticScatteringAnalysis.
  • If zero-length elements are present, computations may be done at the same physical location twice. This not only wastes computing resources, but it will cause issues with the analysis using the inelasticScatteringAnalysis program. It is best to avoid this through introducing markers for the desired, unique locations in the lattice.

• losses — The (incomplete) name of an SDDS file to which the record of initial scattering location, initial scattering δ, and loss coordinates will be written.
• output — The (incomplete) name of an SDDS file to which the final coordinates of all surviving particles will be written.
• log_file — The (incomplete) name of an SDDS file to which statistical data will be written as the simulations run. Users should check the MinParticles and MaxParticles columns as the simulation runs to ensure reasonable load balance (e.g., within 10-20%). If balance is poor, consider changing the value of n_delta slightly.
• k_min — Minimum energy k of the brehmsstrahlung photon as a fraction of the beam energy. The electron has δ = -k after scattering. k_min should be small enough that no electron scattered by -k_min is lost, regardless of the scattering location.
• n_k — Number of scattering values on the range k_min to 1.
• momentum_aperture, momentum_aperture_scale — If given, names a file giving the momentum aperture vs s, which is interpolated at the scattering locations to obtain the local momentum aperture. Such a file may be obtained from running the momentum_aperture command. The absolute values of the values in the deltaNegative column will be used in place of k_min. The k_min values thus obtained are multiplied by momentum_aperture_scale, so there is some assurance that the minimally-scattered particles will survive. This ensures that the results are valid for computation of loss rates, for example.
• momentum_aperture_periodicity — If nonzero, the momentum aperture data from momentum_aperture is periodic with the given periodicity.
• s_start, s_end — Range of s location for simulated scattering sites.
• include_name_pattern — Wildcard-containing string to match to element names in selecting scattering sites.
• include_type_pattern — Wildcard-containing string to match to element types in selecting scattering sites.
• verbosity — Higher values may result in more verbose informational output.
• soft_failure — If nonzero, failure to kind a loss does not result in aborting the run.
• allow_watch_file_output — If nonzero, WATCH elements provide output during tracking.