Design of the LBNF Beamline
The Long Baseline Neutrino Facility (LBNF) will utilize a beamline located at Fermilab to provide and aim a neutrino beam of sufficient intensity and appropriate energy range toward DUNE detectors, placed deep underground at the Sanford Underground Research Facility (SURF) in South Dakota. The primary proton beam (60-120 GeV) will be extracted from the MI-10 section of Fermilab’s Main Injector and will be transported via a series of sixty-nine conventional magnets to a solid target. Neutrinos are produced after the protons hit the target and produce mesons which are subsequently focused by magnetic horns into a 194 m long decay pipe where they decay into muons and neutrinos. The hadron absorber, located directly downstream of the decay pipe is designed to absorb the residual energy from protons and secondary particles which have not decayed. Muon detectors placed downstream of the hadron absorber will provide important information about the neutrino beam properties such as the beam direction and intensity as well as the associated muon spectrum. The parameters of the facility were determined taking into account the physics goals, spacial and radiological constraints and the experience gained by operating the NuMI facility at Fermilab. The LBNF beamline facility is designed for initial operation at a proton-beam power of 1.2 MW, with the capability to support an upgrade to about 2.4 MW. LBNF/DUNE obtained CD-1 approval in November 2015. We discuss here the design status and the associated challenges as well as the R&D and plans for improvements before baselining the facility.