Vertex and Tracking detector for the LDMX experiment

This is the authors' abstract. We don't add key points for this paper.

The constituents of dark matter (DM) are still unknown, and the viable possibilities span a very large mass range. Considerable experimental attention has been given to exploring Weakly Interacting Massive Particles in the upper end of this range (few GeV – TeV), while the region MeV to GeV is largely unexplored. If there is an interaction between light DM and ordinary matter, as there must be in the case of a thermal origin, then there necessarily is a production mechanism in accelerator-based experiments. The most sensitive way, (if the interaction is not electron-phobic) to search for this production is to use a primary electron beam to produce DM in fixed-target collisions. The Light Dark Matter eXperiment (LDMX) is a planned electron-beam fixed-target missing-momentum experiment to be based at the Linac to End Station A (LESA) beamline, which is being constructed at SLAC. The LDMX experiment has unique sensitivity to light DM in the sub-GeV range and, if a signal would be observed, can estimate the dark matter mass scale. The LDMX working principle is based on the efficient reconstruction of the incoming beam electron on target as well as the precise measurement of the transverse momentum of the scattered recoil electron. The experiment employs two silicon strip based trackers, named Tagger and Recoil trackers, specifically designed to achieve the experiment physics requirements. This contribution will give an overview of the LDMX experiment tracking system, its projected performance and details on the reconstruction techniques in a highly inhomogeneous magnetic field.