The Ramo-Shockley theorem defines an efficient and physically very intuitive method for the computation of the electrical signal induced by moving charged particles on the readout electrodes of a particle detector.
This theorem, along with its various generalisations and extensions, applies only to situations that are quasi-electrostatic, i.e. where radiation and wave propagation effects do not play an appreciable role.
In this contribution, I will present a fully general signal theorem that encapsulates all electrodynamic effects without any approximations.
It is similar in spirit to the original theorem by Ramo and Shockley, encoding the geometry of the detector in the form of a (time-dependent) weighting field distribution.
I will show the origin of this result as a direct consequence of Maxwell’s equations and discuss how the original quasi-static theorem emerges as a special case. Due to its significant generality, this new theorem applies to all devices that detect fields or radiation from charged particles. I will highlight applications ranging from particle physics to cosmic ray physics, where it enables the computation of the radio signature of cosmic ray induced showers.