Speaker
Description
A terrestrial population of millicharged particles can arise if they constitute a subcomponent of dark matter, or if sufficiently light millicharged particles are produced in cosmic-ray air showers. Through repeated scattering with ordinary matter, these particles thermalize to terrestrial temperatures in Earth’s environment. I will show that a simple electrified shell, such as a Van de Graaff generator, acts as an efficient accumulator of these room-temperature particles and can enhance their local density by up to twelve orders of magnitude. A millicharge detector placed inside the shell can therefore gain a dramatic boost in sensitivity. In particular, Cavendish tests of Coulomb’s law act naturally as both accumulators and detectors of this overdensity. Reinterpreting past Cavendish experiments already yields some of the strongest bounds on terrestrial millicharged-particle populations. I will also discuss a modified setup in which the Cavendish apparatus is surrounded by an additional charged shell, substantially improving the reach and potentially enabling detection of the minimum density generated by cosmic rays. With established electrostatic technology, such experiments can surpass the projected sensitivity of future accelerator searches for sub-GeV masses.