If there are multiple particles produced during a single decay, as in beta decay, their relative angular distribution, or spin directions may not be isotropic.
The first decay processes to be discovered were alpha decay, beta decay, and gamma decay.
The nucleus may capture an orbiting electron, causing a proton to convert into a neutron in a process called electron capture.
All of these processes result in a well-defined nuclear transmutation.
However, for a collection of atoms, the collection's expected decay rate is characterized in terms of their measured decay constants or half-lives. The half-lives of radioactive atoms have no known upper limit, spanning a time range of over 55 orders of magnitude, from nearly instantaneous to far longer than the age of the universe.
Certain highly excited short-lived nuclear states can decay through neutron emission, or more rarely, proton emission. random) process at the level of a singular quantum of single atoms, in that, according to quantum theory, it is impossible to predict when a particular atom will decay, regardless of how long the atom has existed.