This repository contains the files to simulate a crab cavity failure for HL-LHC using SixTrack.

The aim of SixTrack is to track two nearby particles taking into account the full six–dimensional phase space including synchrotron oscillations in a symplectic manner. It allows to predict the long–term dynamic aperture which is defined as the border between regular and chaotic motion. This border can be found by studying the evolution of the distance in phase space of two initially nearby particles. Parameters of interest like nonlinear detuning and smear are determined via a post–processing of the tracking data.

To download the latest version:

svn co http://svn.cern.ch/guest/SixTrack

This will download something similar to the SixTrack folder of this repository. To create the executable you will have to go to SixTrack/trunk/Sixtrack and compile the source code sixtrack.s with the command:

./make_six gfortran collimat

Check the official website for more information.

There is a modified version of SixTrack, which includes a block to simulate crab cavities. The changes with respect to the original SixTrack code are:

• A new line describing the new element in the fort.2 lattice file.

• A new block in the fort.3 input file. Check it out here.

• A new database.

Find the source code in this repository (sixtrack.s_CC_block_vlineal_2), and the executable in run_lsf_template/bin.

Find a special version of SixTrack without the collimation block in the folder run_bpm_template. This version comes in handy to study the behaviour of the crab cavities, since without the collimation block the program is much faster. There's a special marker (BPM) to see the trajectory at a certain point.

Find other executables complementary to SixTrack for collimation studies (namely BeamLossPattern and CleanInelastic) and their description in run_lsf_template/bin.

To run SixTrack you will need several input files:

• Databases : find them in the folder run_lsf_template/DB.
• Geometry and parameter files :"fort.2" and "fort.3", find them in the folder run_lsf_template/input.

A converter has been developed which is directly linked to MAD-X. It produces the geometry file # 2 (fort.2); an appendix to the parameter file # 3 (fort.3) which defines which of the multipole errors are switched on; the error file # 16 and the file # 8 which holds the transverse misalignments and the tilt of the nonlinear kick elements. It also produce a file (unit 34) with linear lattice functions, phase advances and multipole strengths needed for resonance calculations for the program SODD.

MAD-X can help you generate your accelerator lattice, and store it in the geometry file "fort.2". The parameter file "fort.3" can be written by hand.

To see the MAD-X program that generates SixTrack input please check the folder madx.

Check out how to send SixTrack jobs to LSF here run_lsf_template.

There is an example of the needed files to run SixTrack locally in run_local_template. Modify fort.3 and CC_dataf, and run SixTrack:

./SixTrack_coll_fvlineal2

It is recommended to only run locally for a few jobs. SixTrack output can sometimes be very heavy and can easily fill your free disk space.

You can find some handy python scripts in python_modules.