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Forum: Geometry
Re: Question What is the correct way to create a G4Element consisting of a single G4Isotope? (Sergio Losilla)
Date: 28 Oct, 2018
From: Michael H. Kelsey <Michael H. Kelsey>

On Wed, 24 Oct 2018 12:42:50 GMT, Sergio Losilla wrote:
> Hi,
> 
> I am wondering what is the correct way to create an element consisting
> of a single isotope. Everything looks fine except for the mass number N:
> 
>     auto b10{new G4Element{"B10", "B", /* number of components : */ 1}};
>     b10->AddIsotope(new G4Isotope{"B10", 5, 10}, /* relative abundance : */ 1.0);
> 
>     std::cout << "Z: " << b10->GetZ() << std::endl;
>     std::cout << "N: " << b10->GetN() << std::endl;
>     std::cout << "A: " << b10->GetA()/(g/mole) << std::endl;
> 
> Output:
> 
>     Z: 5
>     N: 10.0129
>     A: 10.0129
> 
> I noticed that in G4Element.cc (lines 97 and 196) the effective mass
> number is just the effective atomic mass in different units:
> 
>     fNeff   = fAeff/(g/mole);
> 
> Should I expect that Neff for the element differs from N for the
> isotope? If not, how should I create the G4Element? If yes, what does
> Neff mean?

I think you were expecting that your specially created G4Element would reflect reality :-) You are creating your _own_ object of type G4Element, and it is up to you to specify its isotopic composition. What you did above was to specify a 100% purified "element" made of a single isotope, so of course A(element) = A(isotope), and trivially N(element) = N(isotope).

If you want to see an element's effective values which differ from an isotope, then you need to create your element with a combination of _different_ isotopes.

You may see this if you look at one of our predefined NIST elements, such as "G4_B", which is predefined as a mix of 19.9% boron-10, and 80.1% boron-11.

  -- Michael Kelsey

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1 None: Re: What is the correct way to create a G4Element consisting of a single G4Isotope?   (Sergio Losilla - 29 Oct, 2018)
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