In this episode of the Physics World Weekly podcast, the CERN physicist Jamie Boyd talks about the ForwArd Search ExpeRiment (FASER), which is located 480 m downstream from a particle collision point on the Large Hadron Collider (LHC) in Geneva.

FASER is on the lookout for weakly interacting particles that are created in LHC collisions and then travel through rock and concrete to reach the detector. Earlier this year the experiment made history by being the first to detect neutrinos created at a particle collider.

But as Boyd explains, neutrinos were not the primary target when FASER was first proposed. Instead, the experiment was built to study hypothetical particles – such as dark photons – that are associated with dark matter. Dark matter is itself a hypothetical substance that many physicists believe can explain some puzzling properties of galaxies and larger-scale structures in the universe.