Dark matter search with the BDX-MINI experiment

TL;DR

BDX-MINI is a beam dump experiment at Jefferson Lab that searches for Light Dark Matter, setting new limits and demonstrating the potential for future high-sensitivity dark matter searches with electron beams.

Contribution

This study presents the first results from BDX-MINI, a novel beam dump experiment optimized for Light Dark Matter detection using a new detector setup and analysis method.

Findings

Set an upper limit on Light Dark Matter production.

Demonstrated sensitivity comparable to leading experiments in certain kinematic regions.

Validated background characterization and analysis techniques for future experiments.

Abstract

BDX-MINI is a beam dump experiment optimized to search for Light Dark Matter produced in the interaction of the intense CEBAF 2.176 GeV electron beam with the Hall A beam dump at Jefferson Lab. The BDX-MINI detector consists of a PbWO$_4$ electromagnetic calorimeter surrounded by a hermetic veto system for background rejection. The experiment accumulated $2.56 \times 10^{21}$ EOT in six months of running. Simulations of fermionic and scalar Dark Matter interactions with electrons of the active volume of the BDX-MINI detector were used to estimate the expected signal. Data collected during the beam-off time allowed us to characterize the background dominated by cosmic rays. A blind data analysis based on a maximum-likelihood approach was used to optimize the experiment sensitivity. An upper limit on the production of light dark matter was set using the combined event samples collected during beam-on and beam-off configurations. In some kinematics, this pilot experiment is sensitive to the parameter space covered by some of the most sensitive experiments to date, which demonstrates the discovery potential of the next generation beam dump experiment planned at intense electron beam facilities.