Timothy Knight Nelson
(SLAC National Accelerator Laboratory (US))
As the WIMP scenario for thermally-produced Dark Matter becomes greatly constrained by experiment, significant attention has been focused on the possibility that Dark Matter is only one element of a broader Dark Sector. Since the first experiments searching for Dark Sectors were proposed nearly a decade ago, progress in both theory and experiment have highlighted some key goals and challenges in exploring Dark Sector physics. One of these challenges is the availability of accelerator facilities suitable for these experiments, where the beam attributes required are often quite different than for typical experiments in HEP. The proposed Dark Sector Experiments at LCLS-II (DASEL) beamline proposes to use the LCLS-II drive beam at SLAC to create a facility that is ideal for a number of experiments in Dark Sector physics. As a first target, the Light Dark Matter Experiment (LDMX) aims to be the class-leading experiment in the exploration of thermally-produced light dark matter in the MeV-GeV range. The physics goals, design, and status of DASEL and LDMX will be discussed, along with a number of challenges that must be met along the way.