| Summary: | G4_He seems to have wrong density | ||
|---|---|---|---|
| Product: | Geant4 | Reporter: | Thomas Kittelmann <thomas.kittelmann> |
| Component: | materials | Assignee: | Vladimir.Ivantchenko |
| Status: | RESOLVED FIXED | ||
| Severity: | trivial | ||
| Priority: | P5 | ||
| Version: | 10.0 | ||
| Hardware: | All | ||
| OS: | All | ||
Hello Thomas, Thank you for this report. The fix is provided: for all Geant4 NIST gases default temperature is now 20 degrees. It will be available with the next patch to Geant4 10.1. VI Thanks for the fix! :-) But I am a bit surprised, does that mean that the G4 NIST manager provides all materials at 20 Celcius rather than STP conditions? Or is there simply no general policy? Cheers, Thomas Hello, Original NIST DB provides data at NTP conditions - 20C, Geant4 traditionally assumed default temperature 0C - STP. When NIST materials were introduced inside Geant4 this fact was missed and it is a bug. The impact of this bug was only on specific set-ups where user defines NIST gases with specific temperature and pressure (not default) forcing re-computation of the density. Current fix switches Geant4 default from STP to NTP. VI |
G4_He provided via the G4 Nist manager, has density corresponding to helium at 20 degree Celcius: Material: G4_He density: 0.166 kg/m3 RadL: 5.671 km Nucl.Int.Length: 3.343 km Imean: 41.800 eV temperature: 273.15 K pressure: 1.00 atm ---> Element: He (He) Z = 2.0 N = 4.0 A = 4.00 g/mole ---> Isotope: He3 Z = 2 N = 3 A = 3.02 g/mole abundance: 0.00 % ---> Isotope: He4 Z = 2 N = 4 A = 4.00 g/mole abundance: 100.00 % ElmMassFraction: 100.00 % ElmAbundance 100.00 % At 273.15 K (STP) I believe the correct number is around 0.1786 kg/m3 rather than 0.166kg/m3. This is probably an issue in all recent releases.