Nuclear Decay & Binding Lab

Decay chains start with a pure parent population. Amounts are fractions of the initial atom count; relative activities are λN/N₀ in s⁻¹, not a dose or a measured sample activity. The model is a linear chain with 100% feeding to the next member; presets omit branches or very short intermediate states. Stable members stop feeding. Custom rows use Name, half-life unit or Name, stable; units are s, min, h, d, y. Equal and nearly equal half-lives are supported. Decimal points and commas are accepted; incomplete numeric tokens are rejected.

The solver evaluates a positive transition-matrix exponential with scaling and squaring, rather than dividing by differences of decay constants. This preserves parent survival and supports large rate differences. Finite numerical limits still apply. Choose the time window to resolve the daughters of interest; a long window can hide short-lived peaks.

Binding energy uses the semi-empirical liquid-drop formula with coefficients aᵥ=15.75, aₛ=17.8, a꜀=0.711, aₐ=23.7 and aₚ=11.18 MeV. The curve chooses Z near the stability valley; it is an approximation, especially for light nuclei, not an evaluated binding-energy table.

Q examples use selected neutral atomic mass excesses from IAEA LiveChart. D–T gives about 17.589 MeV. Net hydrogen fusion gives about 26.731 MeV including positron annihilation; neutrinos carry part of this energy away. The specified U-235/Ba-141/Kr-92 channel gives about 173.278 MeV, not the total energy of a complete fission-plus-decay history. The iron split uses the mass formula instead of tabulated masses. No dose, shielding or decay-heat calculation is provided.