FASER (ForwArd Search ExpeRiment) is planned to be one of the eight particle physics experiments in 2022 at the
Large Hadron Collider
The Large Hadron Collider (LHC) is the world's largest and highest-energy particle collider. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008 in collaboration with over 10,000 scientists and hundr ...
at
CERN. It is designed to both search for new light and weakly coupled
elementary particle
In particle physics, an elementary particle or fundamental particle is a subatomic particle that is not composed of other particles. Particles currently thought to be elementary include electrons, the fundamental fermions (quarks, leptons, antiq ...
s, and to study the interactions of high-energy
neutrino
A neutrino ( ; denoted by the Greek letter ) is a fermion (an elementary particle with spin of ) that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass ...
s.
The experiment is installed in the service tunnel TI12, which is 480 m downstream from the interaction point used by the
ATLAS
An atlas is a collection of maps; it is typically a bundle of maps of Earth or of a region of Earth.
Atlases have traditionally been bound into book form, but today many atlases are in multimedia formats. In addition to presenting geograp ...
experiment.
This tunnel was formerly used to inject the beam from the
SPS into the
LEP accelerator. In this location, the FASER experiment is placed into an intense and highly collimated beam of both neutrinos as well as possible new particles. Additionally, it is shielded from ATLAS by about 100 meters of rock and concrete, providing a low background environment. The FASER experiment was approved in 2019 and will start taking data during Run 3 of the LHC, starting in 2022.
New physics searches
The primary goal of the FASER experiment is to search for new light and weakly interacting particles, that have not been discovered yet, such as
dark photons,
axion
An axion () is a hypothetical elementary particle postulated by the Peccei–Quinn theory in 1977 to resolve the strong CP problem in quantum chromodynamics (QCD). If axions exist and have low mass within a specific range, they are of interest ...
-like particles and
sterile neutrinos. If these particles are sufficiently light, they can be produced in rare decays of