The milliQan Experiment: Search for milli-charged Particles at the LHC

Recently, a search for milli-charged particles produced at the LHC has been proposed. The experiment, named milliQan, is expected to obtain sensitivity to charges of 101 103e for masses in the 0.1-100 GeV range. The detector is composed of 3 stacks of 80 cm long plastic scintillator arrays read out by PMTs. It will be installed in an existing tunnel 33 m from the CMS interaction point at the LHC, with 17 m of rock shielding to suppress beam backgrounds. In the fall of 2017 a 1% scale "demonstrator" of the proposed detector was installed at the planned site in order to study the feasibility of the experiment, focusing on understanding various background sources such as radioactivity of materials, PMT dark current, cosmic rays, and beam induced backgrounds. The data from the demonstrator provides a unique opportunity to understand the backgrounds and to optimize the design of the full detector.