How to read a cell
Neutron number N runs horizontally and proton number Z runs vertically. Each row contains one element, with its isotopes arranged from left to right. This is called the Segrè layout.
Each cell shows a nuclide’s symbol and half-life. The colour band indicates its main decay mode. Tap a cell for branching percentages, natural abundance where available, and the daughter nuclides produced by decay.
You can follow a decay chain across the grid: β⁻ decay moves one cell up and one to the left; α decay moves two down and two left.
Decay mode colours
Where the data comes from
Half-lives, decay modes, branching intensities, isomeric states and natural abundances are taken from the NUBASE2020 evaluation — Kondev, Wang, Huang, Naimi and Audi, Chinese Physics C 45, 030001 (2021) — published open access under CC BY 3.0. Element names and symbols come from the open-source periodictable library.
Values come from NUBASE2020. Any changes are marked as required by the licence. The chart uses the standard Segrè layout, with original rendering.
Presented for training and reference. For operational radiological work, use your site’s controlled references. For cross sections, level schemes and fission yields, consult the IAEA and NNDC nuclear data resources.
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