The DarkLight Experiment: A Precision Search for New Physics at Low Energies

TL;DR

The DarkLight experiment aims to detect a potential dark photon in the 10-100 MeV/c^2 range by precisely measuring electron-proton scattering and detecting complete final states, advancing low-energy physics and new technology development.

Contribution

It introduces a new experimental setup for searching for dark photons at low energies with detailed detection of all final state particles.

Findings

Phase-I experiment funded and scheduled within 18 months.

Complete phase-II design underway for future data collection.

Development of new technology for beam, target, and detector systems.

Abstract

We describe the current status of the DarkLight experiment at Jefferson Laboratory. DarkLight is motivated by the possibility that a dark photon in the mass range 10 to 100 MeV/c$^2$ could couple the dark sector to the Standard Model. DarkLight will precisely measure electron proton scattering using the 100 MeV electron beam of intensity 5 mA at the Jefferson Laboratory energy recovering linac incident on a windowless gas target of molecular hydrogen. The complete final state including scattered electron, recoil proton, and e+e- pair will be detected. A phase-I experiment has been funded and is expected to take data in the next eighteen months. The complete phase-II experiment is under final design and could run within two years after phase-I is completed. The DarkLight experiment drives development of new technology for beam, target, and detector and provides a new means to carry out electron scattering experiments at low momentum transfers.