  The Deep Underground Neutrino Experiment and Long-Baseline Neutrino Facility
(DUNE-LBNF) are under development at Fermilab since early 2010s [1]. At
present, the work is being performed towards a comprehensive review conducted
by US Department of Energy (DOE)-the Critical Decision 2 (CD-2)-that is planned
to take place in the middle of 2022. The primary scientific objectives of DUNE
are to carry out a comprehensive investigation of neutrino oscillations to test
CP violation in the lepton sector, determine the ordering of the neutrino
masses, and to test the three-neutrino paradigm (electron, muon and tau
neutrino). The LBNF will provide a 120-GeV proton beam on a neutrino production
target utilizing a new 800-MeV superconducting Linac which is expected to be
completed in 2027 [2]. The neutrino beamline, which utilizes a target and horn
systems, decay pipe, hadron absorber and other systems, is a core component of
the LBNF. At present-as a result of numerous iterations-there exists an
optimized design with a 1.5-m graphite target and focusing system consisting of
three horns. Further optimization energy deposition and radiological
calculations are performed towards CD-2 and beyond. This paper describes
results of the most recent MARS15 [3] optimization studies.
