One of the greatest mysteries of in cosmology and particle physics is dark matter. We know it exists as we see its gravitational effects on several different manifestations, and we know makes up most of the mass of the universe. However, its nature remains almost completely unknown, except that we know it has no electric charge.
LDMX is an experimental effort to probe thermal dark matter over most of the sub-GeV mass
range, with orders of magnitude more sensitivity than any previous or proposed experiments. It
addresses many of the science drivers that are highlighted in the 2017 US Cosmic Visions New
Ideas in Dark Matter Community Report. The experiment would use a missing momentum
technique to search for dark matter via dark breamsstrahlung in an electron beam. The detector
employs a hadron calorimeter with excellent neutron detection efficiency and good angular
coverage. The technology we have developed for the Mu2e Cosmic Ray Veto detector serves as
a basis for the design. LDMX received Stage 1 approval from the US Department of Energy on
February 28, 2020. We are currently in the design stage and next year will fabricate and test
The UVA group joined this effort in early 2019 when it became clear that the technology we have developed for the Mu2e Cosmic Ray Veto would be ideal for the LDMX hadronic calorimeter. As members of the LDMX hadronic calorimeter group we are responsible for the design of the counters and their fabrication. LDMX received first funding from the DOE in early 2020. Designs are completed, prototypes will be fabricated and tested with fabrication of the detector slated to start in year three of this proposal.