Speaker
Description
The X17 anomaly refers to a bump seen in the pair production spectrum of the decay to ground state of excited Be8 nuclei. This was first observed in 2015 at the ATOMKI Van de Graaf generator and was repeated using He4 and C12. The most prominent explanation is a hidden-sector boson that mediates a “fifth force” that couples to dark matter and has small kinetic mixing with the electromagnetic force. We will run an experiment in Hall B of Jefferson Lab that will search for this proposed particle using Bremsstrahlung-like production in the photon field of a thin tantalum target. Our experiment aims to fully resolve the anomaly by having sensitivity to the full coupling constant spectrum that has not already been ruled out by other experiments. We are scheduled to run our experiment at the start of the FY2026 CeBAF run period. In this talk I will discuss the motivation for this experiment, as well as design decisions, preparations, and planning for the upcoming run.
