The opportunity offered by the ESSnuSB project to exploit the larger leptonic CP violation signal at the second oscillation maximum and the requirements of this project on the ESS accelerator complex

TL;DR

The paper discusses the potential of the ESSnuSB project, utilizing the European Spallation Source's high-power neutrino beam and a large detector, to discover leptonic CP violation at the second oscillation maximum within a decade.

Contribution

It proposes leveraging the ESS accelerator complex to create a high-intensity neutrino Super Beam and a large detector to explore CP violation in the leptonic sector.

Findings

Potential to discover leptonic CP violation at 5 sigma in over half of the phase space.

Upgrading to a 2.5 GeV beam increases discovery coverage to 65%.

Operates with a 2.0 GeV linac proton beam and a 540 km baseline.

Abstract

Very intense neutrino beams and large neutrino detectors will be needed to enable the discovery of CP violation in the leptonic sector. The European Spallation Source (ESS), currently under construction in Lund, Sweden, is a research center that will provide, by 2023, the world's most powerful neutron source. The average power will be 5 MW. Pulsing this linac at higher frequency, at the same instantaneous power, will make it possible to raise the average beam power to 10 MW to produce, in parallel with the spallation neutron production, a high performance neutrino Super Beam of about 0.4 GeV mean neutrino energy. The ESS neutrino Super Beam, ESSnuSB, operated with a 2.0 GeV linac proton beam, together with a large underground Water Cherenkov detector located at 540 km from Lund, close to the second oscillation maximum, will make it possible to discover leptonic CP violation at 5 sigma significance level in 56 percent (65 percent for an upgrade to 2.5 GeV beam energy) of the leptonic Dirac CP-violating phase range after 10 years of data taking. The paper gives an overview of the proposed facility and presents the outstanding physics reach possible for CP violation with ESSnuSB.