Abstract

In the absence of evidence for a magnetic monopole, the quantisation of charges remains a mystery. Simple extensions to the Standard Model can give rise to particles with very small, non-quantised charge, commonly known as millicharged particles. Existing constraints on such particles extend only to masses of around 100 MeV. Heavier millicharged particles may be produced at the Large Hadron Collider, but since they would exhibit very small ionisation energy losses, they would go unnoticed by existing detectors. I will present a simple, low-cost detector that will be installed in an unused underground tunnel near LHC Point 5 (CMS), and will be capable of discovering millicharged particles up to masses of ~100 GeV and charges down to ~0.001e.