A Single Atomic Particle Forever Floating at Rest in Free Space: New Value for Electron Radius

An updated survey of mostly experimental spectroscopy work in Seattle on an individual closely-confined isolated atomic or elementary particle is presented. The classical notion of an atomic particle at rest in free space is discussed, and shown to be approximable by zero-point confinement of the particle in a laboratory trap. An important tool for cooling the particle, and in the case of an electron, for obtaining directly the difference of spin and cyclotron frequencies vs, vc, is side band excitation. The quantum numbers of the geonium "atom", an electron in a Penning trap, have been continuously monitored in a non-destructive way by the new "continuous" Stern-Gerlach effect. In this way the g-factors of electron and positron have been determined to unprecedented precision,