decay curve A graphical representation of the exponential rate at which radioactive disintegration occurs (see RADIOACTIVE DECAY). If half the parent nuclide remains after one time increment, one-quarter will remain after the next (identical) time increment, and so on. A plot of the surviving parent atoms against time in half-lives (see DECAY CONSTANT) gives a decay curve that approaches the zero line asymptotically. In theory it should never attain zero. The number of surviving parent atoms N_(t) at the end of a number of half-lives (n) is simply N₀/2ⁿ. Plotted as a function of time t, survivors form a characteristic decay curve, the equation of which is N_t = N₀e^−λt, where e = 2.718 and λ is the decay constant.

decay curve A graphic representation of the rate of decay of a radioactive isotope of an element. Radioactive disintegration is exponential. If half the parent nuclide remains after one time increment, one-quarter will remain after the next (identical) time increment, and so on. A plot of the surviving parent atoms against time in half-lives (see decay constant) gives a decay curve that approaches the zero line asymptotically. In theory it should never attain zero.