IFFY introduces a new characteristic of isotopes, the Rung. To mix three metaphors, the end of a decay chain is the bottom of the energy ladder, and the sink into which unstable nuclei drain. The sink for the major decay chains is given a Rung value of Zero. This is a stable isotope, which means it has the “proper” proportion of protons and neutrons. Isotopes with too many neutrons have Rung values from one to nine, one for each excess neutron.
The table below shows how rapidly excess neutrons make the nucleus unstable.
Isotopes @ Rung per Time_Bin
No shadowed isotopes or Isomers
- All Rung 0 isotopes are stable or as good as stable for this analysis.
- At Rung 3, there are no isotopes with half-lives longer than a day.
- At Rung 4, there are no isotopes with half-lives longer than an hour.
- At Rung 5, there are no isotopes with half-lives over a minute.
- At Rung 6, there is just one isotope with a half-life over a second.