|Message: Re: What is the correct way to create a G4Element consisting of a single G4Isotope?||Not Logged In (login)|
Click on the Forum title, e.g. on the "Forums by Category" page, to read a sequence of postings to the Forum and its threads all in one page. If you are only interested in one thread or the thread following a specific posting, click the thread or the posting, which takes you to a smaller page, which contains only the part you are interested in and may be easier to navigate.
Messages are "chained" if there are only replies at the first level, i.e. 1/1.html, 1/1/1.html etc. In case of "chained" messages the message number is replaced by the icon and there is no indentation.
Inline: Display the subject line only or also the text of the posting(s); for the choice "All" the "Outline" choices are switched off.
|1||0||1||no text / full text of posting|
|2||1||All||text for level 1 only / text for All postings|
Outline: Choose the depth of the posting thread, successive toggle controls provide increasing detail.
|1||2||1||2 levels / 1 level (original posting)|
|2||3||2||3 levels / 2 levels|
|3||3||All||3 levels / all levels (all postings)|
Sergio Losilla writes: > Hmmm I think I have not explained myself correctly. > > > 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, > > But I *do* want to specify a 100% purified "element" made of a single > isotope (10B)! :-D > > > so of course A(element) = A(isotope), and trivially N(element) > > = N(isotope). > > Well, this is the problem: N(element) = 10.0129 and N(isotope) = 10. I > expected that N(element) = 10. I do not want them to differ. Or well, I > think I do not want them to differ, that is why I was asking if this is > what I should expect. > > I hope I made more sense now. Yes, it does, sorry for my confusion previously. So, G4Isotope "knows" that is defines a single unique nucleus, and is built around "nuclear" assumptions. The G4Isotope constructor takes Z and N as _integer_ arguments, which count the number of protons and total number of nucleons respectively. You can tell it the atomic mass (A) as a double if desired, or it will compute it for you (including binding energy, atomic electrons, etc.). G4Isotope::GetN() returns an integer, which is just the N value you gave it in the constructor. G4Element, on the other hand, is designed to be some combination of isotopes, and is build around "chemical" definitions and assumptions. In particular, in a mixture of isotopes, the effective "number of nucleons" is taken as just the molar mass divided by N_A, which is a double. You can see in G4Element.hh that GetAtomicMassAmu() and GetN() return the same value, A/(g/mol). The latter is just shorthand for the former. For your case, that leads to the apparent inconsistency between the two GetN() values you print out. Conceivably, one could define N_eff as the weighted average of the isotopic N values. However, a G4Element doesn't have to have any isotopes at all attached to it -- it can be defined with values in isolation. In that case, the end user (and a constructor) would have allow setting N_eff and A_eff separately, with all the potential inconsistencies that would allow. -- Mike Kelsey
|Inline Depth:||Outline Depth:||Add message:|