Neutrino Physics Enters the Global Era
The agencies1 and laboratory directors2 gathered at the International Meeting on Large Neutrino Infrastructures hosted by the Astroparticle Physics European Consortium (APPEC)3 in Paris on 23 and 24 June 2014, agreed that 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. Furthermore, this program is complementary to neutrino related measurements made in cosmology and provides crucial input to the knowledge of the Universe.
They further examined the neutrino program developing internationally relating to experiments using accelerator beams, reactors, cosmic rays and underground laboratories. They were pleased with the first efforts of coordination of the neutrino community in the above domains.
Concerning the first domain, they welcome the recent approval by the CERN council of the medium-term CERN plan, consistent with the European Strategy document, including the hosting of a neutrino platform at CERN for R&D and prototyping for the next generation of neutrino detectors, as the main CERN investment to the development of a worldwide program. They also welcome the proposed upgrade of the J-PARC beam and the proposal to construct Hyper-Kamiokande, a megaton scale water Cherenkov detector with large international participation in Kamioka. These upgrades are clearly the continuation of Japan’s tradition of maintaining a leading neutrino program.
They support the vision of the HEPAP/P5 report to host an international facility for short and long-baseline neutrino oscillations at Fermilab, where internationally driven collaborations are encouraged to propose a program optimised in baseline and detector technology. This approach, in parallel with the decision of Fermilab to upgrade its beam infrastructure (PIP-II) gives the opportunity for a rich international neutrino program at Fermilab.
The agencies and laboratory directors invite the neutrino scientific community to develop urgently a coherent international program which exploits the above opportunities. They will meet again in early 2015 in the U.S.A, to evaluate the progress made with respect to this goal.
Furthermore, the situation concerning the "neutrino anomalies" needs to be clarified. This will be addressed by the neutrino short baseline program mentioned above and by smaller scale endeavours putting neutrino sources near the detector.
In the reactor related domain, there are currently two large projects in development in Asia. The approved JUNO experiment located in China, whose goal is to determine the mass hierarchy by using reactor neutrinos while also performing precision measurement of oscillation parameters, studies of supernova neutrinos, geo-neutrinos, solar and atmospheric neutrinos. The JUNO proto-collaboration welcomes more international participation. In parallel, the RENO-50 proposal, with quite similar characteristics, is under evaluation in Korea.
The neutrino mass hierarchy and sinθ23 octant will also be measured through atmospheric neutrinos a) in INO, a 50 kton magnetized iron detector in India, that will start deployment in a few years, calling for international participation to increase its size to 100 kton to address the mass hierarchy problem on a shorter time scale, b) through the proposed upgrades of the neutrino observatory IceCube (PINGU) and the projected KM3NeT (ORCA).
Last but not least, there is a rich physics program in development both for single beta and neutrino-less double beta decay measurements currently probing the quasi-degenerate region of neutrino masses. The next ambitious goal for double-beta decay is the coverage in sensitivity of the inverted mass-hierarchy region; achieving this goal will require large enrichment of isotopes and ton scale detectors, boosting the scale of the experiments and therefore demanding international collaborations for their construction. The agencies urge the underground laboratory directors to prepare the ground for an international evaluation in 2-3 years time leading to a selection of the most promising technologies for the next generation detectors worldwide.
While the agencies and the laboratory directors recognise that to realise the success of the above projects there will be a need for investment in theory and necessary support measurements, this document should not be interpreted as a funding endorsement.
Finally, the agencies and the laboratory directors will seek the advice of the Neutrino ICFA panel4 as well as the IUPAP working group of Astroparticle Physics International Committee (APPIC)5 on all the above issues.
1 In the meeting the agencies were represented by (in agency alphabetical order): J. Siegrist (associate director Department Of Energy, DOE) J. Martino (director Institut National de Physique Nucléaire et Physique des Particules, IN2P3/CNRS), A. Masiero (deputy director Insituto Nationale de Fisica Nucleare, INFN), H. Tanaka (representing the National Science and Engineering Research Council of Canada, NSERC) and J. Womersley (Chief Executive of Science et Technology Facilities Council, STFC). G.Patry (president and CEO of the Canada Foundation of Innovation, CFI) also participated as an observer.
2 In the meeting the directors of laboratory present were (in laboratory alphabetical order): S.Bertolucci director of research at CERN, N. Lockyer director of Fermi National Accelerator Laboratory, Y. Wang director of Institute of High Energy Physics, IHEP of Beijing, N. Mondal director of the India-Based Neutrino Observatory, INO, P. Chomaz director of the Institut de Recherche sur les lois Fondamentales de l’Univers, IRFU/DSM/CEA, Y. Okada executive director of the High Energy Accelerator Research Organisation, KEK in Japan, F. Piquemal director of the Laboratoire Souterrain de Modane, LSM and N. Smith director of the Sudbury Neutrino Observatory, SNOLAB.
Chairman of APPEC
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