User:JWB/Isotopes by isobar

Legend
This isotope table shows all nuclides with halflife at least one day and selected ones with halflife less than 1 day, arranged so that:
 * Half-lives are indicated by the color of each isotope's cell (see color chart to the right). Colored borders indicate half lives of the most stable nuclear isomer states.
 * Mass number (total number of nucleons) increases from top to bottom (each row is an isobar).
 * Atomic number (number of protons) increases from left to right, but adjacent rows are not aligned by atomic number. Instead, each row is arranged so that all beta decay and inverse beta decay proceed toward the center column.

Beta decay and position

 * Beta decay proceeds from isotopes on the left half of the chart towards the center column. The cell to the right of the original nuclide may show the halflife.
 * Inverse beta decay proceeds from isotopes on the right half of the chart towards the center column. The cell to the left of the original nuclide may show the halflife.
 * The only exception is that when both beta decay modes are possible with significant probability, the more probable of the two is towards the center column and marked with the halflife (for all decay modes combined), while the less likely is away from the center and marked with the probability in percent and a direction arrow ← or → pointing away from the center.
 * For the isobars of mass numbers 243, 247, 248, 252, 254, 258 a choice of center cell cannot be determined by beta decay, and in these cases it follows the predominant slow neutron capture series. (The center column in the rest of the table also tends to indicate the predominant slow neutron capture pathway.)

Arrows

 * ↓ in a nuclide cell means that this nuclide has a particularly high neutron absorption cross-section (is a notable nuclear poison).
 * ↑ in a nuclide cell indicates that it decays by alpha decay or spontaneous fission with insignificant or no beta decay of either type. ↑ in a halflife cell indicate that the two nuclides adjacent to the right and left both decay by alpha or SF (and therefore no beta decay crosses the cell in either direction).
 * ← or → indicates a direction of beta decay, and is only obligatory for a secondary decay mode (probability less than 50%) pointing away from the center.

Stability

 * Mass numbers 5, 8 and 211-221 have no isotopes with half-life at least 1 day.
 * Nuclides on the center column with mass numbers 1-4, 6-7, 9-208 are always stable, except 144, 147-49 which undergo extremely slow alpha decay. (144, 148 do have a stable isotope but they are not the center of beta decay.) Total of 202 stable nuclides.
 * Nuclides one away from the center column are never stable, though 10 of them have half-lives much greater than the age of the universe.
 * Nuclides two away from the center column are frequently stable (62 cases).
 * Nuclides three and more away from center are never stable and only 145Eu, 146Eu, 146Gd even have half-lives longer than 1 day.

Nuclear fission products

 * The leftmost stable or extremely long-lived isotope in a row will usually be the ultimate state of a fission product of this mass, since fission products usually start with excess neutrons and then undergo beta decay.
 * Radioactive nuclides of concern in spent nuclear fuel will usually be in the columns to the left of this final product, within the mass range expected for fission products. Nuclides of concern for nuclear waste disposal will be green or yellow. (halflives 10 years to 16 million years (for 129I))
 * A percentage in the leftmost column indicates yield for thermal neutron fission of 235U, while a F or f indicates a high-yield or low-yield fission product.