Message: Re: What is the correct way to create a G4Element consisting of a single G4Isotope? Not Logged In (login)

## Re: What is the correct way to create a G4Element consisting of a single G4Isotope?

Forum: Geometry
Date: 30 Oct, 2018
From: Michael H. Kelsey <Michael H. Kelsey>

 ```Sergio Losilla writes: > Hmmm, OK, looking at G4Element.hh in more detail answered my question: > > 134: // Atomic weight in atomic units > 135: inline G4double GetN() const {return fNeff;} > 136: inline G4double GetAtomicMassAmu() const {return fNeff;} > > So G4Element::GetN() returns the atomic weight, and not the average N. > > Is this standard notation? I apologize if this is a silly question, I am > not a particle or nuclear physicist but a computational physics > outsider... Unfortunately, I'm not a chemist, and they're the ones who invented elements ;-> I don't know if it's a standard definition in the literature. As near as I can tell, it's in G4 as a convenience, in order to get from a proper value of atomic mass in real mass units (g/mol) to a dimensionless value, without having to do two divisions everywhere. > I mean, at the moment it seems that: > > A_element = sum_isotope w_isotope * A_isotope > N_element = A_element/(g/mol) > > instead of what I expected > > A_element = sum_isotope w_isotope * A_isotope > N_element = sum_isotope w_isotope * N_isotope Actually, the latter is what might naively have expected as well. > My main worry is that I am defining the element wrong, and that a wrong > value of N is used at some stage of the simulation yielding wrong > results. But I guess I can proceed safely. Nope. I can guarantee that if N=A/(g/mol) is what's in the code, then any G4 code that _uses_ G4Element::GetN() will be expecting that value, and changing it would break much more than it "fixed" :-) -- Mike ```

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1 Re: What is the correct way to create a G4Element consisting of a single G4Isotope?   (Sergio Losilla - 30 Oct, 2018)
 to: "Re: What is the correct way to create a G4Element consisting of a single G4Isotope?"
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