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0001
0002 ePIC Barrel HCAL Detector Geometry
0003 ----------------------------------
0004
0005 John Lajoie - 1/17/2024
0006 revised 2/16/2024
0007 lajoiejg@ornl.gov
0008
0009
0010 This directory contains the gdml geometry files for the ePIC barrel hadronic calorimeter absorber structure as well as the orginal CAD step files and the FreeCAD projects used to generate the GDML.
0011
0012 STEP Files:
0013 -----------
0014
0015 *2021MAY12_sPHENIX_CM.STEP*: Original geometry STEP file received from sPHENIX engineers. Note that this contains the magnet poletips for sPHENIX that are not a part of ePIC. These must be removed.
0016
0017 *2021MAY12_sPHENIX_CM_Full.STEP*: STEP file created using SolidWorks 2021 and removing the sPHENIX poletips. Written out in AP214 STEP format.
0018
0019 *2021MAY12_sPHENIX_CM_Full_NoCombs.STEP*: STEP file created using SolidWorks 2021 and removing the sPHENIX poletips and HCAL plate combs. These combs are complicated and generate complicated tessellated model, which is not really necessary for the G4 simulations. Written out in AP214 STEP format.
0020
0021 *2021MAY12_sPHENIX_CM_Plates_EndPlates_Only.STEP*: STEP file created using SolidWorks 2021 and removing the sPHENIX poletips, combs and dogbone rings. Written out in AP214 STEP format.
0022
0023 *2021MAY12_sPHENIX_CM_Plates_EndPlates_Only.STEP*: STEP file created using SolidWorks 2021 and removing the sPHENIX poletips, combs, dogbone rings and endplates. Written out in AP214 STEP format. This is usually used in debugging the tile placement in DD4HEP as it allows better visibility in the viewer.
0024
0025 *2021MAY12_sPHENIX_CM_Sector_NoCombs.STEP*: STEP file extracted from the full geometry for a single HCAL sector. The sector combs have been removed.
0026
0027 *2021MAY12_sPHENIX_CM_ChimneySector_NoCombs.STEP*: STEP file extracted from the full geometry for a single HCAL chimney sector. The sector combs have been removed.
0028
0029 *2021MAY12_sPHENIX_CM_EndRing.STEP*: STEP file extracted from the full geometry for the end ring ("dogbones").
0030
0031
0032
0033 FreeCAD File:
0034 -------------
0035
0036 The FreeCAD files follow the same naming convention as the STEP files above. The files were created by importing the relevant STEP file above in the GDML workbench and translating the imported structure to y=-3959.37mm to remove an offset in the original CAD model. If the dogbone rings are included they are translated to create a 1mm gap between the endplates and dogbone rings to avoid numerical precision errors creating overlap errors on contact surfaces between the parts.
0037
0038 These files were created with FreeCAD version 0.21 using GDML workbench v2.0 Beta.
0039
0040 *preMesh*: Project with imported geometry prior to creating the mesh
0041
0042 *Union_preMesh*: When the endplates are included the plates and endplates must be combined in a FreeCAD Fusion to avoid numerical precision errors creating overlap errors on contact surfaces between the parts.
0043
0044 *Meshed*: Project with the meshed solids, ready for GDML export
0045
0046 GDML Files:
0047 -----------
0048
0049 These files can be accessed directly by the simulation by editing the epic/compact/hcal/barrel_gdml.xml file. The availability of multiple versions aids in debugging as well as verifying the effects/utility of increasing complex absorber geometry.
0050
0051 *barrel_hcal_steel_full.gdml*: The full ePIC barrel HCAL geometry, including the sector combs. This is a vert large tesselated object.
0052
0053 *barrel_hcal_steel_full_nocombs.gdml*: The ePIC barrel HCAL geometry, excluding the sector combs. *This is the DD4HEP default for ePIC Simulations.*
0054
0055 *barrel_hcal_steel_plates_endplates_only.gdml*: Simplified ePIC barrel HCAL geometry, with only the absorber plates and endplates. The dogbone rings are not included.
0056
0057 *barrel_hcal_steel_plates_only.gdml*: Very simplified ePIC barrel HCAL geometry, with only the absorber plates. The dogbone rings and endplates are not included.
0058
0059 *barrel_hcal_steel_sector_nocombs.gdml*: Single HCAL sector without sector combs.
0060
0061 *barrel_hcal_steel_chimneysector_nocombs.gdml*: Single HCAL chimney sector without sector combs.
0062
0063 *barrel_hcal_steel_sector_endring.gdml*: Single end-ring (dogbones)
0064
0065
0066 The GDML had to be hand edited to fix two issues:
0067
0068 - The units needed to be added to the identity matrix definition at the end of the <define> section:
0069
0070 <rotation name="identity" x="0" y="0" z="0" unit="deg"/>
0071
0072 - The <structure> and <setup> sections at the very end of the file were simplified to:
0073
0074 <structure>
0075 <volume name="BarrelHCalSteel">
0076 <solidref ref="Mesh2Tess"/>
0077 </volume>
0078 </structure>
0079 <setup name="Default" version="1.0">
0080 <world ref="BarrelHCalSteel"/>
0081 </setup>
0082
0083
0084 Note that the material for the structure is defined in barrel HCAL xml file.
0085
