The Light Dark Matter eXperiment (LDMX) is a planned electron-beam fixed-target missing-momentum experiment that has unique potential to conclusively test models of such light Dark Matter in the MeV to GeV range. The experiment requires a primary 4-15 GeV electron beam capable of delivering 1e14 – 1e16 electrons on target with a low current.

The CERN SPS which once accelerated electrons up to 22 GeV for injection into LEP, together with the R\&D invested into a possible future CLIC, offer CERN an opportunity to create an optimal primary electron beam facility for LDMX. In addition such a facility could serve a beam dump experiment searching dark sector mediators decaying to Standard Model particles, Nuclear Physics, and R\&D on acceleration technology.

The conceptual design report is here