The format of the twiss table is best illustrated with an TFS file example.

access to parameters from TWISS and other tables using the table access function.

SixTrack \cite{SixTrack}\cite{SixTrack_www} is a separate beam optics code that is often used for long term tracking of particles, e.g. for dynamic aperture studies, because of its speed and controllability.

However the input files are notoriously difficult to produce by hand. This command may be used to generate SixTrack input files from a sequence loaded in \madx.

SIXTRACK, C̄AVALL=logical, MULT_AUTO_OFF=logical, MAX_MULT_ORD=integer,
SPLIT=logical, APERTURE=logical, RADIUS=real;

The parameters are defined as:

CAVALL (optional flag) This puts a cavity element (SixTrack identifier 12) with Volt, Harmonic Number and Lag attributes at each location in the machine. Since for large hadron machines the cavities are typically all located at one particular spot in the machine and since many cavities slow down the tracking simulations considerably all cavities are lumped into one and located at the first appearance of a cavity. This default is enforced by omitting this flag.

MULT_AUTO_OFF (optional flag, default = FALSE) If TRUE, this module does not process zero value multipoles. Moreover, multipoles are prepared by SIXTRACK (output file fc.3) to be treated up to the order as specified with MAX_MULT_ORD.

MAX_MULT_ORD (optional parameter, default = 11) Process up to this order for MULT_AUTO_OFF = TRUE.

SPLIT (optional flag) OBSOLETE. This splits all the elements in two. This is for backward compatibilty only. The user should now use the MAKETHIN command instead.

APERTURE (optional flag) flag to convert the apertures from \madxto SixTrack so that SixTrack can track with apertures defined. The aperture data is found in file fc.3.aper.

RADIUS (optional, default value is 1 m). This sets the reference radius for the magnets. This argument is optional but should normally be set.

Important Notes:

• •

  The files contain all information concerning optics, field errors and misalignments. Hence these should all be set and a \madxmpTWISS, SAVE; command should always be issued before calling the SIXTRACK command.

• •

  The BV flag is presently ignored by SIXTRACK.

• •

  SixTrack and the \madxcommand SIXTRACK are presently set up for names of a maximum of 16 characters!!!!! Therefore, it is mandatory to respect this limit for \madxnames.

The SIXTRACK command always produces at least one output file:

• •

  fc.2 - the basic structure of the lattice.

It may also produce any or all of the following files, depending on the sequence and command attributes:

• •

  fc.3 - multipole mask(s).

• •

  fc.3.aux - various beam parameters.

• •

  fc.3.aper - aperture element data (units are mm and degrees).

• •

  fc.8 - misalignments and tilts.

• •

  fc.16 - field errors and/or combined multipole kicks.

• •

  fc.34 - various optics parameters at various locations
  This file is not needed by SixTrack but may be used as input to the program SODD\cite{SODD}.)

For a full description of these files see the SixTrack website\cite{SixTrack_www}, the SixTrack user manual\cite{SixTrack}; and for information on running SixTrack see the SixTrack run environment description\cite{SixTrack_RE}.

An SXF\cite{SXF} lattice description is an ASCII listing that contains one named, “flat”, ordered list of elements, delimited as {…}, with one entry for each element. The list resembles a \madx“sequence” describing the entire machine. The syntax is supposed to be adapted for ease of reading by human beings and for ease of parsing by LEX and YACC.