7.73 track

• type: major action command.
• function: track particles.
• sequence: must follow run_setup, run_control, and beam definition with bunched_beam or sdds_beam.
• can use parallel resources (Pelegant)
• Command syntax, including use of equations and subcommands, is discussed in 7.2.

• center_on_orbit — A flag indicating whether to center the beam transverse coordinates on the closed orbit before tracking.
• center_momentum_also — A flag indicating whether to center the momentum coordinate also.
• offset_by_orbit — A flag indicating whether to offset the transverse beam coordinates by the closed orbit before tracking. Similar to center_on_orbit, but the initial centroids of the beam are preserved. The beam is simply displaced by the closed orbit rather than being centered on it.
• offset_momentum_also — A flag indicating whether to also offset the beam momentum to the momentum of the closed orbit. If the start_from_centroid or start_from_dp_centroid parameters are used on the closed_orbit command, this flag should be set to 0; otherwise, one will offset the beam central momentum by its own value.
• soft_failure — If there is an error during tracking (e.g., a failure of orbit correction), continue to produce file output. This creates essentially empty slots in the files corresponding to the failed steps.
• stop_tracking_particle_limit — If a non-negative is given, then elegant will stop tracking when the number of particles falls below the given value. It will be as if all the particles were lost.
• check_beam_structure — For debugging use only.
• interrupt_file — Gives the (possibly incomplete) name of a file to monitor as a semaphore to interrupt the tracking. If the file is created or updated during tracking, then tracking will terminate on completion of the next pass. Output already written to WATCH files is preserved, but unwritten data (e.g., buffered, but not written to disk) is lost.

There are also several deprecated parameters:

• use_linear_chromatic_matrix — For each particle, a first-order matrix is computed for the particular momentum offset of the particle using the linear chromaticity and linear dependence of the beta functions on momentum. Use ILMATRIX elements instead.
• longitudinal_ring_only — Tracks longitudinal coordinates only for a ring. Use ILMATRIX elements instead.