Beamline alternatives ruled out

Visualization of the focusing system chosen by the optimization using a NuMI-style target (top), a Beryllium fin target (middle) and a cylindrical target (bottom).
Visualization of the focusing system chosen by the optimization using a NuMI-style target (top), a Beryllium fin target (middle) and a cylindrical target (bottom).
Visualization of the focusing system chosen by the optimization using a NuMI-style target (top), a Beryllium fin target (middle) and a cylindrical target (bottom).

To reach its ambitious physics goals, DUNE wants a neutrino beamline delivering neutrinos to the far detector by 2026. Over the last few months, many members of DUNE/LBNF have reviewed and evaluated an alternative beamline approach called Neutrinos from PIon beam Line, or NuPIL, as an alternative to the target/horn optimization of the baseline beamline design that has been ongoing since late last year, in order to determine the best path forward. Ultimately, LBNF and DUNE managements have decided to pursue the optimized LBNF wide-band beam design.

This decision was based on a number of factors, including open questions regarding achievable physics reach, technical feasibility and risks, and concerns about alternative beam designs’ energy tunability.  In addition, it appears that bringing NuPIL or other approaches to the necessary conceptual level would add at least two years to the current project schedule.

Overall, these reviews have reconfirmed the strength of the optimized LBNF beamline design. LBNF will now begin to transition to the next phase, completing the conceptual design for the beamline, so that the preliminary beamline design can begin in October 2017, and the technical design report can be ready as scheduled, by June 2019.