NeutronHP warning for wrong isotope in text geometry definition

Physics Processes, Models and Cross Sections
1

Hi, I’m trying to simulation the a CLYC thermal neutron detector with text geometry. I define Li6 and Li7 like this, with 0.1eV neutron, and physics list QGSP_BERT_HP.

:ISOT Li6 3 3 6
:ISOT Li7 3 4 7

I believe this is right according to https://geant4.web.cern.ch/collaboration/working_groups/persistency/docs/textgeom.pdf, which tell me the syntax is :ISOT NAME Z N A.
But warinings for wrong isotope Li3, Li4 were shown.

NeutronHP: /Elastic file for Z = 3, A = 3 is not found and NeutronHP will use /home/wqd/soft/geant4/geant4-v11.2.2-install/share/Geant4/data/G4NDL4.7.1/Elastic/CrossSection/3_6_Lithium
NeutronHP: /Elastic file for Z = 3, A = 4 is not found and NeutronHP will use /home/wqd/soft/geant4/geant4-v11.2.2-install/share/Geant4/data/G4NDL4.7.1/Elastic/CrossSection/3_6_Lithium

If I switch the definition to this one, the warning for Li disappeared.

// CLYC
:ISOT Li6 3 6 6
:ISOT Li7 3 7 7

Geant4 Version: geant4-11-02-patch-02 [MT]
Operating System: Debian GNU/Linux 12
Compiler/Version: g++ (Debian 12.2.0-14) 12.2.0
CMake Version: 3.30.4

2

I’ve moved this to the physics category as it looks like the materials/geometry are constructed correctly, but this is an issue with the use of the NeutronHP physics.

3

Yes, the geometry is right. The message is saying that Li3 file does not exist in database, likely because there is no experimental data.

4

Well, I think the warning suggests that the G4tgbVolumeMgr mistakenly regarded :ISOT Li6 3 3 6 to Li3, and regarded :ISOT Li6 3 6 6 to Li6.
This might be unrelated to physics, but be related to the implementation of G4tgbVolumeMgr.

5

You are right, it is a bug in the doc
:ISOT
• Name
• Z
• N
• A
while it should be
:ISOT
• Name
• atomic number (Z)
• mass number (A)
• atomic mass

6

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