According to NIST, it should be equal to 78 eV (https://physics.nist.gov/PhysRefData/XrayMassCoef/tab1.html), but in Geant4, it is equal to 81 eV. This value is present in both the documentation (https://geant4-userdoc.web.cern.ch/UsersGuides/ForApplicationDeveloper/html/Appendix/materialNames.html) and the code (G4NistMaterialBuilder.cc). Values for all other elements are the same. Only carbon has different values.
Marc, please, assign it to me. Carbon is a difficult material, because may exist in many forms why the current choice made and not NIST data directly are used we have to investigate. VI
Hello Marcin, Thanks for reporting on this problem. These numbers are taken from PSTAR and ASTAR material DB: https://physics.nist.gov/cgi-bin/Star There is a contradiction with NIST XRAY element data for carbon in the element data: rho=1.7 I = 78 in PSTAR and ASTAR: rho=2 I = 81 Inside Geant4 density effect data we have I=78, so likely we should change 81 to 78 but what to choose as the default for carbon density for me not clear. The fix will be available in the next public release of Geant4. VI
Hello, mean ionisation potential for G4_C is changed. The fix will be available in the next public release and in the next patch to Geant4 11.0. VI
