| Summary: | G4_STAINLESS_STEEL is ill defined (should be mass composition not molar composition with those values) | ||
|---|---|---|---|
| Product: | Geant4 | Reporter: | Urs Hofmann <mail> |
| Component: | materials | Assignee: | Vladimir.Ivantchenko |
| Status: | RESOLVED FIXED | ||
| Severity: | critical | CC: | michel.maire, Vladimir.Ivantchenko |
| Priority: | P4 | ||
| Version: | 11.2 | ||
| Hardware: | All | ||
| OS: | All | ||
count atomic mass weight ratio reference Fe 74 55.845 4132.53 74.6 Cr 18 51.996 935.928 16.9 18 … 20 Ni 8 58.693 469.544 8.5 8.0 … 10.5 if i use the atomic composition as used for G4_STAINLESS-STEEL I end up with a Cr weight ratio of 16.9 which is less then the minimum Cr content defined by the standard for 304 alloy mentioned in the reference. For information: Stainless-Steel is correctly defined in hadronic example NeutronSource, DetectorConstruction.cc, lines 96-100. See NeutronSource.out, lines 52-75. Hello, you are right: in any case, the description of such material as stainless still should be not in atom counts but in mass fraction. Current description is not wrong but misleading. It is implementing variant of the still from http://www.azom.com/article.aspx?ArticleID=965 The problem of this material and several others is in the fact that each vendor has its own set of compositions of still, so whatever we will include into G4 DB may not be true for the real material used in a concrete setup. I would propose we will switch from atom counts to mass fraction for materials in G4DB, for which it is more natural, but we will not change mass fractions compared with the current values. The reason - these materials may be already used in applications, so we should not make surprises to users. If a vendor provides a different composition, then the material should be described in user application and not taken from our DB. VI Hello, the problem is addressed and improved version of the code will be available in the next public release. VI |
The G4NistMaterialBuilder defines stainless steel as ```c++ AddMaterial("G4_STAINLESS-STEEL", 8.00, 0, 0.0, 3); AddElementByAtomCount("Fe", 74); AddElementByAtomCount("Cr", 18); AddElementByAtomCount("Ni" , 8); ``` To the best of my knowledge those values should represent the mass composition and not the molar composition? In other places in the source code those ratios are also used as mass composition: ``` <material name = "STAINLESS-STEEL" formula="STAINLESS-STEEL" > <D value="8" /> <fraction n ="0.169001" ref = "G4_Cr" /> <fraction n ="0.746213" ref = "G4_Fe" /> <fraction n ="0.0847861" ref = "G4_Ni" /> </material> </materials> ``` I would assume that this predefined material is widely used by the community and a fix might be necessary?