This project hosts very simple but working geometries written in GDML and compatible with REST. The aim of those geometries is to serve as a reference to new REST users.
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01.boxes: Just two boxes shifted.
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02.sphere: A spherical volume contained in a stainlessteel vessel.
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03.detector: A gaseous detector box surronded by a lead box.
These files are splitted in a main setup.gdml file that defines the main parameters, and a geometry.xml where the solids, volumes and physical volumes are defined.
The GDML geometries we write for REST are slightly modified, and are not directly compatible with ROOT. Our GDML files support the use of system variables ${VARIABLE} and adding remote http files and include them in a XML entity.
We use a class named TRestGDMLParser to help reading this modified GDML file and translate it to be compatible with ROOT. The class responsible to read a GDML geometry in ROOT is a TGeoManager. See also the TGeoManager documentation from ROOT pages.
Therefore, the TRestGDMLParser allows us to get a TGeoManager object that we can visualize in ROOT.
Still, we need to define few system variables GDML_XX, that in our case define the gas properties, and that we hard-coded inside our simple geometry files. Using export directive in a bash shell terminal we will be able to give them a value before using the geometry.
export GDML_GAS=Neon_ISO
export GDML_PRESSURE=1
export GDML_QUENCHER=0.02
restRoot
[0] TRestGDMLParser *g = new TRestGDMLParser();
[1] TGeoManager *geo = g->GetGeoManager("setup.gdml");
[2] geo->GetTopVolume()->Draw("ogl");
We use a common materials file that is located at the Git materials project. The materials file is shared through the following remote http location being the remote synchronized with the Gitlab project.
The materials file is included in the geometry using the following line:
<!ENTITY materials SYSTEM "http://sultan.unizar.es/materials/materials.xml">
We will be allowed to use any material included in that file for our geometrical volumes. If the material you need is not found we encourage to upload that material to the Gitlab materials project and share it with anyone else.
When we launch restG4, the simulation conditions will be stored inside a TRestGeant4Metadata object at the output ROOT file. The GDML geometry defines the following header at the beginning of the setup.gdml file.
<!-- ##VERSION Boxes basic geometry Version 1.0 (${GDML_GAS} - ${GDML_PRESSURE}bar - Quencher: ${GDML_QUENCHER})## -->
That line will be stored at a data member inside the TRestGeant4Metadata class. Including the values we used for each of the GDML_ variables. As it is seen at the following screen dump from TRestGeant4Metadata::PrintMetadata.
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|| Geant 4 version : 10.5.1 ||
|| Random seed : 72146224 ||
|| GDML geometry : Boxes Basic geometry Version 1.1 (Neon_ISO - 1bar - Quencher: 0.02) ||
|| GDML materials reference : REST materials 1.1 ||
|| Max. Step size : 0.5 mm ||
⚠ WARNING: REST is under continous development. This README is offered to you by the REST community. Your HELP is needed to keep this file up to date. You are very welcome to contribute fixing typos, updating information or adding new contributions. See also our Contribution Guide.