Mass-to-charge ratio used as its unit in the field of mass spectrometry. Some fields use the charge-to-mass ratio ("Q"/"m") instead, which is the multiplicative inverse of the mass-to-charge ratio. The 2014 CODATA recommended value for an electron is = . When charged particles move in electric and magnetic fields the following two laws apply: where F is the force applied to the ion, "m" is the mass of the particle, a is the acceleration, "Q" is the electric charge, E is the electric field, and v × B is the cross product of the ion's velocity and the magnetic flux density. This
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