Atomic recoil Atomic recoil Atomic recoil is the result of the interaction of an atom with an energetic elementary particle, when the momentum of the interacting particle is transferred to the atom as whole without altering non-translational degrees of freedom of the atom. It is a purely quantum phenomenon. Atomic recoil was discovered by Harriet Brooks, Canada's first female nuclear physicist. If the transferred momentum of atomic recoil is enough to disrupt the crystal lattice of the material, a vacancy defect is formed; otherwise a phonon is generated. Closely related to atomic recoil is electron recoil (see photoexcitation and photoionization), and nuclear
Particle decay to further decay. The term is typically distinct from radioactive decay, in which an unstable atomic nucleus is transformed into a lighter nucleus accompanied by the emission of particles or radiation, although the two are conceptually similar and are often described using the same terminology. Particle decay is a Poisson process, and hence the probability that a particle survives for time "t" before decaying is given by an exponential distribution whose time constant depends on the particle's velocity: All data is from the Particle Data Group. Note that this section uses natural units, where formula_4 The lifetime of a particle