|Message: mean excitation energy of G4_WATER||Not Logged In (login)|
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In Geant4.9.6 user guide, |
this mean excitation energy is 75 eV on page 348.
On NIST website, this energy is also 75 eV
However, when we run Geant4, this energy is 78 eV:
Material: G4_WATER H_2O density: 1.000 g/cm3 RadL: 36.083 cm Nucl.Int.Length: 75.517 cm Imean: 78.000 eV
---> Element: H (H) Z = 1.0 N = 1.0 A = 1.01 g/mole
---> Isotope: H1 Z = 1 N = 1 A = 1.01 g/mole abundance: 99.99 %
---> Isotope: H2 Z = 1 N = 2 A = 2.01 g/mole abundance: 0.01 % ElmMassFraction: 11.19 % ElmAbundance 66.67 %
---> Element: O (O) Z = 8.0 N = 16.0 A = 16.00 g/mole
---> Isotope: O16 Z = 8 N = 16 A = 15.99 g/mole abundance: 99.76 %
---> Isotope: O17 Z = 8 N = 17 A = 17.00 g/mole abundance: 0.04 %
---> Isotope: O18 Z = 8 N = 18 A = 18.00 g/mole abundance: 0.20 % ElmMassFraction: 88.81 % ElmAbundance 33.33 %
Yes, I know if we use self-defined water material, this energy is different from the one used for G4_WATER, for example, according to my definition, it is 68.981 eV.
Material: Water density: 1.000 g/cm3 RadL: 36.086 cm Nucl.Int.Length: 75.510 cm Imean: 68.981 eV
---> Element: Hydrogen (H) Z = 1.0 N = 1.0 A = 1.01 g/mole ElmMassFraction: 11.20 % ElmAbundance 66.69 %
---> Element: Oxygen (O) Z = 8.0 N = 16.0 A = 16.00 g/mole ElmMassFraction: 88.80 % ElmAbundance 33.31 %
My understanding is we'd better use G4_WATER with 78 eV when we select water material to make simulation result better fit with the measurement.
I suggest the value should be updated in the user guide.
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