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

TL;DR

The milliQan experiment aims to detect milli-charged particles at the LHC using a specialized detector, with a demonstrator installed to study backgrounds and optimize the full detector design.

Contribution

This paper introduces the milliQan experiment and reports on the installation and background studies of its demonstrator detector at the LHC.

Findings

Background sources characterized, including radioactivity and cosmic rays.

Feasibility of the detector design demonstrated through initial data.

Optimization strategies for the full detector are being developed.

Abstract

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 $10^{- 1} - 10^{-3}e$ 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.