Light Dark Matter Experiment (LDMX)

LDMX aims to decisively test thermal dark matter scenarios in the MeV-GeV mass range, a goal that no other existing or planned experiments can achieve. The primary focus is on light hidden sector (or "dark sector") dark matter in the mass range of 0.5 MeV to 0.5 GeV, roughly in the mass range of familiar matter such as electrons and protons. In this mass range, dark matter can be a thermal relic provided it interacts with the Standard Model through GeV-scale vector or scalar mediated forces.

The LDMX experiment proposes a high-statistics search for low-mass dark matter using an electron beam fixed-target missing momentum technique, scattering incoming electrons in a tungsten target to produce dark matter via “dark bremsstrahlung”. The clear signature is established by individually tagging incoming beam-energy electrons and unambiguously associating them with low energy, moderate transverse-momentum recoils and establishing the absence of a forward going photon. The primary backgrounds are traditional bremsstrahlung processes with photo-nuclear reactions occurring in the target or forward calorimeter. Therefore, the experiment requires a high-speed, granular calorimeter with MIP sensitivity to identify rare photo-nuclear reactions, in addition to low-mass tracking that provides high-purity tagging for incoming electrons and clean, efficient reconstruction of recoils. The LDMX concept proposes to meet these challenges by leveraging technology under development for the HL-LHC and experience from the HPS experiment.

At present this is a very bare-bones web space for LDMX – it will be changing rapidly as the summer 2016 studies get underway.