# Number of Isotopes created with decay <-> Chain Yield

The chain yield (or fission yield) states how many isotopes with a certain mass $$A$$ are created with the decay of $$^{235}$$U. But how do we know the fractions of specific Isotopes that are created under the decay? Because there are many isotopes with the same mass number.

• Different elements with the "same" mass can still be separated out in mass spectrum measurements. This is particularly true of accelerator mass spec (often used for C14 dating), where the slight mass differences from binding energy are readily separated magnetically. – Jon Custer Jan 15 at 13:54
• I think my question was misleading. I am rather wondering how we can now the production of a certain isotope just with the table of nuclides and the there stated chain yield?! – kalle Jan 15 at 14:19
• So, starting from 100% pure isotope A, follow all decay chains and at time $T$ determine how much of isotope B should be present? A straightforward but tedious calculation involving all possible decay paths down to B... – Jon Custer Jan 15 at 14:45