The understanding of the neutrino sector is a worldwide priority, promising physics beyond the Standard Model in a unified theoretical framework that goes from the electroweak scale to the highest energy scales. During a seminar on CERN’s neutrino platform, Sergio Bertolucci presented the current and future steps of the Organisation in this field of research. He emphasized how the rapid progress in neutrino oscillation physics, with significant European involvement, has established a strong scientific case for a long-baseline neutrino programme exploring CP violation and the mass hierarchy in the neutrino sector.

The European Strategy for Particle Physics (ESPP) of 2013 classified the long-baseline neutrino programme as one of the four highest-priority scientific objectives with required international infrastructure. There are currently plans for a large neutrino oscillation physics facility mentioned in both the European strategy document and that from P5 in the US. This new facility will focus on probing CP-violation in the neutrino sector, determining the neutrino mass hierarchy, looking for sterile neutrinos (i.e. testing the three neutrino flavour paradigm), proton decay (through kaon channels), and with an ability to observe supernova neutrinos. In Japan an extensive upgrade of SuperKamiokande through international cooperation (HyperKamiokande) is considered a priority project, while the US has formed the ELBNF collaboration with a timescale of 25+ years for both short and long (1300km) baseline experiments that will use a precise near detector and a 40 kt liquid argon far detector. ELBNF follows the organisational paradigm of the LHC collaborations and so far is comprised of 142 institutes from 23 countries.

In the framework of the ESPP programme, a new neutrino platform will be begin operation in the North Area of CERN in 2016, and the ICARUS neutrino detector has been transferred from Gran Sasso to CERN to be refurbished and upgraded, with the final goal of moving it to Fermilab. Weighing 760 tonnes, ICARUS T600 is the world’s largest liquid argon neutrino detector. In addition, CERN has suspended neutrino beam projects to support the planned US and Japanese experiments. The intention is to do R&D and offer support to these experiments, as well as provide a basis to unify the European neutrino communities towards contributing to the US and Japanese projects. In particular, significant R&D effort will be made on LAr TPC technologies.

The first ICARUS TPC arrived at CERN on 1 December and is now being housed in a CERN clean room. 

The new platform will allow the large community of neutrino experts to develop their R&D programmes here at CERN, in preparation for their participation in the large neutrino experiments that will be carried out world-wide. A multi-detector program will address the unexplained anomalies that could hint at new physics. In addition to detailed studies of neutrino oscillations, the experiments could make important contributions in the field of cosmology and astrophysics by searching for supernova bursts and proton decay, providing a significant improvement in discovery sensitivity over current searches for the proton lifetime.

Results from multiple experiments have hinted at a possible additional oscillation. However, while each of the measurements alone lacks the significance to claim a discovery, together they could be hinting at important new physics. Bertolucci pointed out that: “the discovery of a light sterile neutrino would be monumental for particle physics and cosmology!”

A 70-metre extension of the EHN1 experimental hall,  will host the experimental apparatuses.

The new neutrino platform will also contribute to all logistics aspects related to the R&D programmes, which will be approved by CERN committees and management. “The CERN platform will also support neutrino experiments in the field of cryogenics, magnet technology, integration and assembly techniques, and, in general, in all fields in which CERN has a proven global expertise,” concluded Bertolucci. “However, for the time being, CERN is not committing to any neutrino beam being built here. Instead, we remain open to discussions in view of a common road map to be agreed on with the other laboratories.”

In summary, CERN is offering a platform for neutrino detector R&D that is now a well-established part of the CERN MTP. Bertolucci mentioned that it will be actively supported and help WA104, WA105, and all other proposals approved by the SPSC. CERN is currently building a large neutrino test area (EHN1 extension) with charged beam capabilities that will be available in 2017. Moreover, CERN will collaborate with FNAL on the LBNF infrastructure and assist the European neutrino community in their long term common plans.