Hi,
I have a rather complex geometry implemented with tessellated GDML solids.
However, I stumbled on a rather strange issue: depending on the number of defined solids, the interaction of a gamma-ray beam is tracked…or not.
In the code below you can find a simplified geometry, which is imported through an external GDML file.
See the following image for reference (left panel) We have four simple (tessellated) volumes, two (A0, A1) thin Silicon slabs, and two (B0, B1) thicker CsI scintillator boxes.
I’m generating a 2 keV gamma-ray beam using GPS:
/gps/particle gamma
/gps/pos/centre 1 2 100 cm
/gps/direction 0 0 -1
/gps/energy 2 keV
/run/beamOn 100
If the four A0, A1, B0 and B1 volumes are defined, the beam does not interact with any volume. Instead, if a physical volume is commented out in the GDML file (for example, see the GDML code below in which the B1 physical volume is commented), the photons have correct physical interactions, with e.g. the 2 keV beam stopped by the thin Silicon slab.
The strange thing is that it does not matter which volume is left out. For example, if the volume A1 (which is well outside the beam!) is present, there is no beam interaction, while if it is commented out the interaction occurs…
Even more strange is that this problem occurs only if the primary is a gamma ray (of any energy). If I switch to a proton or electron beam, the physical interaction are tracked regardless of the number of the active volumes.
Using Geant 4.10.7 or 4.11.0.2 makes no difference.
I hope that the problem description is clear enough.
Thanks in advance for any comment.
Cheers
R
<?xml version='1.0' encoding='ASCII'?>
<gdml xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://service-spi.web.cern.ch/service-spi/app/releases/GDML/schema/gdml.xsd">
<define>
<constant name="HALFPI" value="pi/2."/>
<constant name="PI" value="1.*pi"/>
<constant name="TWOPI" value="2.*pi"/>
<position name="A0_0" unit="mm" x="4.0" y="9.899999618530273" z="314.70001220703125"/>
<position name="A0_1" unit="mm" x="4.0" y="49.5" z="314.70001220703125"/>
<position name="A0_2" unit="mm" x="18.5" y="49.5" z="314.70001220703125"/>
<position name="A0_3" unit="mm" x="18.5" y="9.899999618530273" z="314.70001220703125"/>
<position name="A0_4" unit="mm" x="18.5" y="9.899999618530273" z="315.1000061035156"/>
<position name="A0_5" unit="mm" x="4.0" y="9.899999618530273" z="315.1000061035156"/>
<position name="A0_6" unit="mm" x="4.0" y="49.5" z="315.1000061035156"/>
<position name="A0_7" unit="mm" x="18.5" y="49.5" z="315.1000061035156"/>
<position name="A1_0" unit="mm" x="4.0" y="50.5" z="314.70001220703125"/>
<position name="A1_1" unit="mm" x="4.0" y="90.0999984741211" z="314.70001220703125"/>
<position name="A1_2" unit="mm" x="18.5" y="90.0999984741211" z="314.70001220703125"/>
<position name="A1_3" unit="mm" x="18.5" y="50.5" z="314.70001220703125"/>
<position name="A1_4" unit="mm" x="18.5" y="50.5" z="315.1000061035156"/>
<position name="A1_5" unit="mm" x="4.0" y="50.5" z="315.1000061035156"/>
<position name="A1_6" unit="mm" x="4.0" y="90.0999984741211" z="315.1000061035156"/>
<position name="A1_7" unit="mm" x="18.5" y="90.0999984741211" z="315.1000061035156"/>
<position name="B0_0" unit="mm" x="17.299999237060547" y="11.350000381469727" z="296.3970031738281"/>
<position name="B0_1" unit="mm" x="17.299999237060547" y="11.350000381469727" z="311.45001220703125"/>
<position name="B0_2" unit="mm" x="5.199999809265137" y="11.350000381469727" z="311.45001220703125"/>
<position name="B0_3" unit="mm" x="5.199999809265137" y="11.350000381469727" z="296.3970031738281"/>
<position name="B0_4" unit="mm" x="5.199999809265137" y="18.290000915527344" z="311.45001220703125"/>
<position name="B0_5" unit="mm" x="5.199999809265137" y="18.290000915527344" z="296.3970031738281"/>
<position name="B0_6" unit="mm" x="17.299999237060547" y="18.290000915527344" z="311.45001220703125"/>
<position name="B0_7" unit="mm" x="17.299999237060547" y="18.290000915527344" z="296.3970031738281"/>
<position name="B1_0" unit="mm" x="17.299999237060547" y="18.790000915527344" z="296.3970031738281"/>
<position name="B1_1" unit="mm" x="17.299999237060547" y="18.790000915527344" z="311.45001220703125"/>
<position name="B1_2" unit="mm" x="5.199999809265137" y="18.790000915527344" z="311.45001220703125"/>
<position name="B1_3" unit="mm" x="5.199999809265137" y="18.790000915527344" z="296.3970031738281"/>
<position name="B1_4" unit="mm" x="5.199999809265137" y="25.729999542236328" z="311.45001220703125"/>
<position name="B1_5" unit="mm" x="5.199999809265137" y="25.729999542236328" z="296.3970031738281"/>
<position name="B1_6" unit="mm" x="17.299999237060547" y="25.729999542236328" z="311.45001220703125"/>
<position name="B1_7" unit="mm" x="17.299999237060547" y="25.729999542236328" z="296.3970031738281"/>
</define>
<materials>
</materials>
<solids>
<box name="WorldBox" x="100.0" y="100.0" z="100.0" lunit="cm"/>
<tessellated name="A0">
<triangular vertex1="A0_0" vertex2="A0_1" vertex3="A0_2" type="ABSOLUTE"/>
<triangular vertex1="A0_0" vertex2="A0_2" vertex3="A0_3" type="ABSOLUTE"/>
<triangular vertex1="A0_0" vertex2="A0_3" vertex3="A0_4" type="ABSOLUTE"/>
<triangular vertex1="A0_0" vertex2="A0_4" vertex3="A0_5" type="ABSOLUTE"/>
<triangular vertex1="A0_6" vertex2="A0_5" vertex3="A0_7" type="ABSOLUTE"/>
<triangular vertex1="A0_7" vertex2="A0_5" vertex3="A0_4" type="ABSOLUTE"/>
<triangular vertex1="A0_4" vertex2="A0_3" vertex3="A0_2" type="ABSOLUTE"/>
<triangular vertex1="A0_4" vertex2="A0_2" vertex3="A0_7" type="ABSOLUTE"/>
<triangular vertex1="A0_1" vertex2="A0_7" vertex3="A0_2" type="ABSOLUTE"/>
<triangular vertex1="A0_1" vertex2="A0_6" vertex3="A0_7" type="ABSOLUTE"/>
<triangular vertex1="A0_5" vertex2="A0_6" vertex3="A0_1" type="ABSOLUTE"/>
<triangular vertex1="A0_5" vertex2="A0_1" vertex3="A0_0" type="ABSOLUTE"/>
</tessellated>
<tessellated name="A1">
<triangular vertex1="A1_0" vertex2="A1_1" vertex3="A1_2" type="ABSOLUTE"/>
<triangular vertex1="A1_0" vertex2="A1_2" vertex3="A1_3" type="ABSOLUTE"/>
<triangular vertex1="A1_0" vertex2="A1_3" vertex3="A1_4" type="ABSOLUTE"/>
<triangular vertex1="A1_0" vertex2="A1_4" vertex3="A1_5" type="ABSOLUTE"/>
<triangular vertex1="A1_6" vertex2="A1_5" vertex3="A1_7" type="ABSOLUTE"/>
<triangular vertex1="A1_7" vertex2="A1_5" vertex3="A1_4" type="ABSOLUTE"/>
<triangular vertex1="A1_3" vertex2="A1_2" vertex3="A1_7" type="ABSOLUTE"/>
<triangular vertex1="A1_4" vertex2="A1_3" vertex3="A1_7" type="ABSOLUTE"/>
<triangular vertex1="A1_6" vertex2="A1_7" vertex3="A1_2" type="ABSOLUTE"/>
<triangular vertex1="A1_1" vertex2="A1_6" vertex3="A1_2" type="ABSOLUTE"/>
<triangular vertex1="A1_0" vertex2="A1_6" vertex3="A1_1" type="ABSOLUTE"/>
<triangular vertex1="A1_5" vertex2="A1_6" vertex3="A1_0" type="ABSOLUTE"/>
</tessellated>
<tessellated name="B0">
<triangular vertex1="B0_0" vertex2="B0_1" vertex3="B0_2" type="ABSOLUTE"/>
<triangular vertex1="B0_0" vertex2="B0_2" vertex3="B0_3" type="ABSOLUTE"/>
<triangular vertex1="B0_4" vertex2="B0_5" vertex3="B0_3" type="ABSOLUTE"/>
<triangular vertex1="B0_4" vertex2="B0_3" vertex3="B0_2" type="ABSOLUTE"/>
<triangular vertex1="B0_6" vertex2="B0_1" vertex3="B0_0" type="ABSOLUTE"/>
<triangular vertex1="B0_6" vertex2="B0_0" vertex3="B0_7" type="ABSOLUTE"/>
<triangular vertex1="B0_7" vertex2="B0_5" vertex3="B0_4" type="ABSOLUTE"/>
<triangular vertex1="B0_7" vertex2="B0_4" vertex3="B0_6" type="ABSOLUTE"/>
<triangular vertex1="B0_5" vertex2="B0_7" vertex3="B0_3" type="ABSOLUTE"/>
<triangular vertex1="B0_3" vertex2="B0_7" vertex3="B0_0" type="ABSOLUTE"/>
<triangular vertex1="B0_6" vertex2="B0_4" vertex3="B0_2" type="ABSOLUTE"/>
<triangular vertex1="B0_6" vertex2="B0_2" vertex3="B0_1" type="ABSOLUTE"/>
</tessellated>
<tessellated name="B1">
<triangular vertex1="B1_0" vertex2="B1_1" vertex3="B1_2" type="ABSOLUTE"/>
<triangular vertex1="B1_0" vertex2="B1_2" vertex3="B1_3" type="ABSOLUTE"/>
<triangular vertex1="B1_4" vertex2="B1_5" vertex3="B1_3" type="ABSOLUTE"/>
<triangular vertex1="B1_4" vertex2="B1_3" vertex3="B1_2" type="ABSOLUTE"/>
<triangular vertex1="B1_6" vertex2="B1_1" vertex3="B1_0" type="ABSOLUTE"/>
<triangular vertex1="B1_6" vertex2="B1_0" vertex3="B1_7" type="ABSOLUTE"/>
<triangular vertex1="B1_7" vertex2="B1_5" vertex3="B1_4" type="ABSOLUTE"/>
<triangular vertex1="B1_7" vertex2="B1_4" vertex3="B1_6" type="ABSOLUTE"/>
<triangular vertex1="B1_5" vertex2="B1_7" vertex3="B1_3" type="ABSOLUTE"/>
<triangular vertex1="B1_3" vertex2="B1_7" vertex3="B1_0" type="ABSOLUTE"/>
<triangular vertex1="B1_6" vertex2="B1_4" vertex3="B1_2" type="ABSOLUTE"/>
<triangular vertex1="B1_6" vertex2="B1_2" vertex3="B1_1" type="ABSOLUTE"/>
</tessellated>
</solids>
<structure>
<volume name="LV_B1">
<materialref ref="G4_CESIUM_IODIDE"/>
<solidref ref="B1"/>
</volume>
<volume name="LV_B0">
<materialref ref="G4_CESIUM_IODIDE"/>
<solidref ref="B0"/>
</volume>
<volume name="LV_A1">
<materialref ref="G4_Si"/>
<solidref ref="A1"/>
</volume>
<volume name="LV_A0">
<materialref ref="G4_Si"/>
<solidref ref="A0"/>
</volume>
<volume name="World">
<materialref ref="G4_Galactic"/>
<solidref ref="WorldBox"/>
<physvol name="PV-LV_A0">
<volumeref ref="LV_A0"/>
</physvol>
<physvol name="PV-LV_A1">
<volumeref ref="LV_A1"/>
</physvol>
<physvol name="PV-LV_B0">
<volumeref ref="LV_B0"/>
</physvol>
<!-- <physvol name="PV-LV_B1">-->
<!-- <volumeref ref="LV_B1"/>-->
<!-- </physvol>-->
</volume>
</structure>
<setup name="Default" version="1.0">
<world ref="World"/>
</setup>
</gdml>