Simulations and analysis for FASER and the Forward Physics Facility

Alongside operation of the Large Hadron Collider, several new experiments searching for new physics in the Dark Sector have been initiated at CERN under the Physics Beyond Colliders programme. The RHUL Accelerator Science group provides multi-physics simulation capability to understand the experimental beamlines, using RHUL's unique BDSIM expertise and leadership.
The ForwArd Search ExpeRiment (FASER) will provide sensitive searches for dark photons, axion-like particles, and light gauge bosons. Placed 480 m downstream of the ATLAS interaction point in the low pT blind spot that is inaccessible to the LHC collider detectors, the FASER detector is also ideally located to provide the first detection and studies of high-energy neutrinos produced at the LHC. In 2020-21, the FASER prototype detector was installed for operation during LHC Run3. For an integrated luminosity of 150 fb-1 planned to be collected during LHC Run 3, assuming SM cross sections, 1300 e, 20,000 , and 20 will interact in FASER, with mean energies of 600 Ge to 1 Te. With such rates and energies, FASER will open up windows on new physics, provide new constraints on neutrino cross sections at currently unexplored energies, and constrain models for forward particle production.
Vital to such measurements are accurate simulations of the particle spectra, flux and energies reaching the FASER detector. This PhD project, supervised by Gibson, will simulate the full propagation of events from pp collisions in ATLAS, through the accelerator optics and surrounding material, including hadronic shower development and secondary production, up to the FASER detector, where both the signal and background flux will be evaluated. The student will use RHUL's BDSIM software to create an exquisite 480m long Geant4 model for FASER, starting from the ATLAS cavern, with full details of the accelerator lattice, apertures, magnets and shielding. Applying this model, the student will calculate the neutrino and muon flux to allow comparison with measured signals during Run 3 of the LHC, enabling first results for FASER. The student will contribute to detector calibration, operation, and help to analyse first experimental data, playing a timely and key role to understand the anticipated signal and backgrounds. Pending the successful first phase, the student will update the accelerator model to study and optimise the design of FASER 2, a larger detector planned for the HL-LHC era, that further enhances the discovery potential.