7.22 elastic_scattering

• type: major action command
• function: perform simulation of elastic scattering at multiple s locations, for use in computing elastic 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 elasticScatteringAnalysis.
  • 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 elasticScatteringAnalysis 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 angle, 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 values of n_phi and n_theta slightly. The product of these values should not evenly divide the number of working cores (which is one less than the total number of cores).
• theta_min — Minimum polar scattering angle in radians. Should be small enough that no particle scattered by this angle are lost, regardless of the scattering location. See also twiss_scaling.
• theta_max — Maximum polar scattering angle in radians. Should be large enough that no particle scattered by this angle survives, regardless of scattering location.
• n_theta — Number of polar scattering angle values on the range theta_min to theta_max.
• quadratic_theta_spacing — If non-zero, the spacing of theta values is quadratic, which emphasizes smaller values.
• n_phi — Number of azimuthal scattering angles on the range [0,π].
• twiss_scaling — If nonzero, then theta_min is scaled by min(,), where s is the location of the scattering location and s = 0 is the start of the lattice.
• 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 non-zero, certain errors or suspect conditions are ignored.
• allow_watch_file_output — If non-zero, WATCH file output occurs during tracking. This may be helpful in diagnosing problems.