ESSnuSBplus · Study of the use of the ESS facility to accurately measure the neutrino cross-sections for ESSnuSB leptonic CP violation measurements and to perform sterile neutrino searches and astroparticle physics

After the success of the H2020 ESSνSB Design Study proving the feasibility of the upgrade of the European Spallation Source to become, in addition to a neutron facility, also a very competitive neutrino facility, we propose here a study to reinforce and develop complementary features to this proposal in order to improve and widen the scientific and technological scope.The key objective of the H2020 ESSνSB Design Study was to demonstrate the feasibility of using the European Spallation Source (ESS) proton linac to produce the world's most intense neutrino beam concurrently with the 5 MW proton beam to be used for the production of spallation neutrons. After accomplishing all deliverables and the publication of the ESSνSB CDR, this is now fully demonstrated. With the present Design Study, it is proposed to take further steps towards its realization by introducing complementary studies and enlarging its scope by making studies on synergetic aspects of the project.The ESSνSB+ high-level objectives are to:• Study the civil engineering needed for the facility implementation at the ESS site as well as those needed for the ESSνSB far detector site.• Study the feasibility and implementation of a special target station for pion production and extraction for injection to a low energy nuSTORM decay ring and to a low energy Monitored Neutrino Beam decay tunnel, for neutrino cross-section measurements.• Study the low energy nuSTORM decay ring and the injection of the pions and muons from the special target station.• Study the low energy ENUBET-like Monitored Neutrino Beam decay tunnel and the injection of the pions and muons from the special target station.• Study the capabilities of the proposed setup for sterile neutrino searches and astroparticle physics.• Promote the ESSνSB project proposal to its stakeholders, including scientists, politicians, funders, industrialists and the general public in order to pave the way to include this facility in the ESFRI list.