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Heavy-ion collimation simulation

Applications

  • Loss map simulation (collimation cleaning inefficiency)
  • Input for energy deposition studies

Simplified Manual

Step 1: Prepare environmental variables

First we have to load the environmental variables. We can do this using the following code below. To load the environment for compiling Fluka: 

source /cvmfs/sft.cern.ch/lcg/contrib/gcc/9.2.0/x86_64-centos7/setup.sh

The environment for compling SixTrack can be loaded using 

# cmake for SixTrack
export PATH=/cvmfs/sft.cern.ch/lcg/contrib/CMake/3.14.2/Linux-x86_64/bin:$PATH
export CMAKE_ROOT=/cvmfs/sft.cern.ch/lcg/contrib/CMake/3.14.2/Linux-x86_64
The path to the FLUKA installation ${FLUKA} and the subpath ${FLUSPC} to the FLUKA afs project space are loaded using. We decide to use a local version of fluka that we have downloaded:

export FLUSPC=/afs/cern.ch/project/fluka
export FLUKA=/afs/cern.ch/work/p/pahermes/private/tools/fluka4-1.1

We can also add useful paths e.g. to flair (a FLUKA GUI, see here), pt (periodic table with Tkinter), fm (fluka manual) 

export PATH=${FLUSPC}:${FLUKA}/bin:${FLUSPC}/flair:$PATH

To access the fluka_coupling repository and the fedb_coupling repository (FLUKA element database), we run:

export CPLPATH=/afs/cern.ch/work/p/pahermes/private/tools/fluka_coupling

export FEDBPATH=/afs/cern.ch/work/p/pahermes/private/tools/fedb_coupling

Step 2: Prepare the input files

Structure of the input directories and the individual steps in linking the files can be set up similarly to the coupling setup for protons. In general, the user will start with a set of inputs from a corresponding proton run.

Optics setup

Make sure to produce the correct optics input for the simulation, reflecting the optics applied in the heavy-ion run that should be simulated. Examples for heavy-ion specific optics calculations and fort.2 generation can be found in the gitlab repository

https://gitlab.cern.ch/collteam/coupling_simulation_material/

For example, if we want to simulate Pb ions at 6.37Z TeV in the 2018 configuration with \beta^*=0.50cm, we have the relevant optics input in 

Simulation_scenarios/LHC/RunII/Pbions_6p37ZTeV_2018_50cm/B1_cleaning/Sixtrack/MADX

Setting up the fort.3 input file

To get started, we need, just like for a proton simulation, the following input files

allapert.b1
CollDB.data
fort.3 
fort.2
SurveyWithCrossing_XP_lowb.dat

The fort.3 file needs adjustment in order to specify the type of heavy-ions we want to simulate and to set the correct energy. We provide SixTrack with the information of the heavy-ion species we want to simulate, using a dedicated HION block, which looks similar to this:

HION
/ A  Z                 m
208 82 193.687690162648
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