FASER: Forward Search Experiment at the Large Hadron Collider at CERN

FASER, the Forward Search Experiment, is the first experiment dedicated to searching for new light weakly interacting particles at CERN’s Large Hadron Collider (LHC) in Geneva. The LHC accelerates counter-rotating beams of protons to the largest energies ever achieved in the lab. These beams collide at a few interaction points along the circular ring, and these points are surrounded by enormous detectors that are designed to look for evidence of new particles. If new light and weakly interacting particles exist, however, they are typically produced parallel to the beam line. The existing detectors at the LHC have holes along the beam line to let the proton beams in and are therefore blind to such particles. From its position just off the beam line and 480 meters downstream from one of these interaction points, FASER will cover this “blind spot” and provide world-leading sensitivity to these particles.

To achieve this sensitivity affordably and quickly, FASER will employ silicon strip detectors and electromagnetic calorimeter modules generously loaned by the ATLAS and LHCb collaborations, respectively. With three powerful permanent magnets to bend the trajectories of charged particles and a scintillator-based veto system to exclude more mundane processes, FASER will be able to unambiguously identify dark photons and other proposed long-lived particles that decay inside it. The discovery of such particles will have revolutionary implications for particle physics and cosmology, providing evidence for new forms of matter or new fundamental forces, and possibly a breakthrough in identifying the particle nature of dark matter.

Jonathan Feng works at the interface of physics and astronomy and explores the deep connections between our understanding of the universe at the smallest and largest length scales. His research spans topics in cosmology and astroparticle, particle and nuclear physics, and he is recognized both for his leadership of the FASER experiment at CERN and as a central figure in the theoretical study of dark matter through his work in constructing models, deducing observational consequences and motivating and interpreting experimental searches. Feng received degrees in physics and mathematics from Harvard, Cambridge and Stanford. He joined the University of California, Irvine faculty in 2002 and became professor and chancellor’s fellow in 2006. He is a fellow of the American Physical Society and the American Association for the Advancement of Science, and his research has been recognized by awards from the National Science, Sloan, Guggenheim, Heising-Simons and Simons Foundations.

Dave Casper received a Ph.D. in physics from the University of Michigan on the pioneering IMB water Cherenkov experiment. His dissertation covered the detection of neutrinos from Supernova 1987A and early evidence for atmospheric neutrino oscillation. After graduation, he received a CERN research associateship and worked as a postdoc on the ALEPH experiment at the LEP accelerator (located in the same tunnel that today houses the Large Hadron Collider). Dave returned to neutrino physics as a University of California, Irvine (UC Irvine) research scientist in 1997, following up his Ph.D. results as a member of the Super-Kamiokande experiment, whose subsequent discovery of neutrino oscillation was recognized by the 2015 Nobel Prize. He became a UC Irvine professor in 2001 and received a Department of Energy Outstanding Junior Investigator Award in 2004. Since 2014, Casper has worked on the ATLAS experiment at the LHC, and in late 2017, he became the first experimentalist to join the FASER team.