The clas12Tags repository

The clas12Tags repository serves as the simulation resource for the CLAS12 experiments at Jefferson Lab, providing:

• The CLAS12 detectors geometry database (in the form of ASCII files and a SQLITE database).
• Individual system steering cards (GCARDS)
• A customized version of the GEMC source code tailored specifically for the JLab CLAS12 experiments.
• The CLAS12 geometry source code.

The CLAS12 detector in the simulation. The electron beam is going from left to right.

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How to create the CLAS12 detector geometry database

You will need:

• java (openjdk >= 17) and groovy installed to run the coatjava geometry service.
• gemc environment, loaded either with module load clas12 or module load gemc.

The script create_geometry.sh will create an individual detector geometry or all of them:

Usage: create_geometry.sh [detector]
Creates the geometry for the given detector
If no detector is given, all detectors will be run

All detectors: 

alert band beamline bst bstShield cnd ctof dc ddvcs ec fluxDets 
ft ftof ftofShield htcc ltcc magnets micromegas pcal rich 
rtpc targets uRwell upstream

The script will install (if not present) the latest tagged coatjava in the directory geometry_source and run the geometry service for the requested detector(s).

Examples:

./create_geometry.sh cnd : creates the CND geometry ASCII database, updates the SQLITE database
./create_geometry.sh : creates all the CLAS12 detectors, updates the SQLITE database

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How compile the source code

You will need:

• gemc environment, loaded either with module load clas12 or module load gemc.
• scons

Run scons in the source directory:

cd source
scons -jN OPT=1

where N is the number of cores available.

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Release workflow

Please make a pull requests with changes pertaining to the directories:

• geometry_source: for changes to the geometry source code.
• source: for changes to the GEMC source code.

The changes will be reviewed and merged into the main branch. A nightly build and a cronjob ensure the latest version of the code and geometry is available on cvmfs.

Use at JLab:

The following releases of Clas12Tags are installed on CVMFS:

• dev (tagged nightly)
• 5.11
• 5.10
• 4.4.2

To load the GEMC environment at JLab:

module use /scigroup/cvmfs/hallb/clas12/sw/modulefiles
module load clas12

To switch to a different version of gemc use module switch. For example:

module switch gemc/dev

To run GEMC you can select one of the gcards in the clas12-config installed on cvmfs. For example:

gemc /scigroup/cvmfs/hallb/clas12/sw/noarch/clas12-config/dev/gemc/dev/rga_fall2018.gcard  -N=nevents -USE_GUI=0 

Alternatively the gcards can be downloaded from https://github.com/JeffersonLab/clas12-config

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Portal to Off-site farms CLAS12 Simulations

GEMC simulations can be run on the Open Science Grid (OSG) using the CLAS12 Simulation Submission Portal.

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FTOn, FTOff configurations

The default configuration for the first experiment is with "FTOn" (Figure 1, Left): complete forward tagger is fully operational. The other available configuration is "FTOff" (Figure 1, Right): the Forward Tagger tracker is replaced with shielding, and the tungsten cone is moved upstream.

FT On configuration: Full, OperationalForward Tagger.	FT Off configuration: FT Tracker replaced by shielding, Tungsten Cone moved upstream, FT if turned off.

To change configuration from FTOn to FTOff, replace the keywords and variations from:

	<detector name="experiments/clas12/ft/ft"                      factory="TEXT" variation="FTOn"/>
	<detector name="experiments/clas12/beamline/cad/"              factory="CAD"  variation="FTOn"/>
	<detector name="experiments/clas12/beamline/beamline"          factory="TEXT" variation="FTOn"/>

to:

	<detector name="experiments/clas12/ft/ft"                      factory="TEXT" variation="FTOff"/>
	<detector name="experiments/clas12/beamline/cad/"              factory="CAD"  variation="FTOff"/>
	<detector name="experiments/clas12/beamline/beamline"          factory="TEXT" variation="FTOff"/>

Changing a material

The option SWITCH_MATERIALTO can be used to change a material of a volume For example, to change the G4_lH2 to vacuum:

<option name="SWITCH_MATERIALTO" value="G4_lH2, G4_Galactic"/>

The option CHANGEVOLUMEMATERIALTO can be used to change the material of a volume. For example, to change the target cell lh2 material from LH2 to a vacuum:

<option name="CHANGEVOLUMEMATERIALTO" value="lh2, G4_Galactic"/>

Removing a detector or a volume

You can remove/comment out the <detector> tag in the gcard to remove a whole system. To remove individual elements, use the existance tag in the gcard. For example, to remove the forward micromegas:

<detector name="FMT">
    <existence exist="no" />
</detector>

Run numbers vs Run groups

Source: calcom run groups

rga_spring2018	3029 - 4326
rga_fall2018	4763-5666
rga_spring2019	6608-6783
rgb_spring2019	6150 – 6603
rgb_fall2019	11093 – 11301
rgb_winter20	11323 - 11571
rgc_summer2022	16043-16772
rgc_fall2022	16843-17408
rgc_winter23	17471-17811
rgd_fall2023	18305 - 19131
rgf_spring2020	11620 - 12282
rgf_summer2020	12389 - 12951
rgk_fall2018_FTOn	5674 - 5870
rgk_fall2018_FTOff	5874-6000
rgk_winter23	19200 - 19260
rgk_spring24	19300 - 19893
rgm_fall2021	15016 - 15884
rge_spring2024

Feedback

Please use CLAS12 discourse for feedback on anything clas12tags related:

https://clas12.discourse.group