Towards the realization of a global neutrino infrastructure
30 April 2015
Date Issued: April 30, 2015
The agency(1) representatives and laboratory directors(2) gathered at the 2nd International Meeting on Large Neutrino Infrastructures(3) hosted at Fermilab on 20-21 April 2015, reiterated their firm belief that neutrino physics is a worldwide research priority in fundamental physics.
As was stated by the Nobel Prize winner Carlo Rubbia at the meeting: “The neutrino together with the Higgs, are so far the only elementary particles whose basic properties are still largely unknown”. The complexity of the questions concerning the nature of the neutrino and its impact on the knowledge and understanding of our universe, demands a coherent programme, ranging from large infrastructure deployment to small scale projects. This complexity continues to be a constant source of innovation in accelerator, particle detection and underground technologies, with significant societal applications. Furthermore, the parallel increase in precision of the terrestrial neutrino program and of cosmological surveys, measuring the impact of neutrinos in cosmic structure formation, is a major avenue to probe new physics beyond the Standard Models of Fundamental Interactions and/or Cosmology.
During the first meeting of last year the agencies had invited the neutrino scientific community to develop urgently a coherent international programme in the long-baseline oscillation accelerator field, consistent with the recommendations of the European Strategy for Particle Physics and the HEPAP/P5(4) report. In the second meeting, organized by Fermilab and APPEC(5) , the agency representatives were impressed by the rapidity, quality of convergence and momentum of the efforts of the community working on liquid argon Time Protection Chambers (LAr TPCs), to develop a credible scientific program based on:
- an ambitious large infrastructure effort, consisting of a long-baseline beam and detector project (LBNF/DUNE(6)) hosted at Fermilab and SURF(7), based on previous design studies, but largely upgrading them, proposed by an international collaboration, very rapidly setting up its governance structure and preparing answers to an aggressive schedule of DOE critical design reviews in July and November 2015;
- a medium-scale programme of short-baseline oscillation experiments at Fermilab (Short-Baseline Near Detector, MicroBoone(8) and ICARUS(9)) aiming to test the sterile neutrino hypothesis with unprecedented accuracy;
- a rich R&D and prototyping programme in the CERN North Area, related to the above programme along with other long-baseline efforts in the world (e.g. Hyper-Kamiokande(10)).
The agencies and national laboratory directors welcomed the proposed measures to complement the establishment of the international collaboration for LBNF/DUNE with appropriate agency oversight bodies: the Long-baseline Neutrino Committee (LBNC), the Resource Review Board (RRB) and an International Advisory Committee (IAC).
In addition they appreciated the progress towards the realization of the Hyper-Kamiokande experiment. An international proto-collaboration encompassing the cosmic ray and particle physics communities has been formed with large international participation and largely complementary to the LBNF/DUNE US-based program. A Memorandum of Understanding between IPNS/KEK and ICRR, University of Tokyo regarding cooperation in promoting Hyper-Kamiokande was recently signed. The Hyper-Kamiokande detector design, based on the well-established water Cherenkov detection technique, is being optimized by the international collaboration and a design report will be prepared in 2015 in view of the next immediate milestone of an international review under IPNS/ICRR.
The agencies noted the complementarity of the large detectors using different detection techniques (water, liquid argon, and liquid scintillator) in the program of neutrino parameter measurements but also, and above all, in the domain of proton decay and neutrino astrophysics. Furthermore, the complexity of the neutrino sector is such that the larger programmes need to be complemented by small and medium scale programs. The overall coherence between these programmes will guarantee an understanding of whether the Standard Model with three neutrino flavours is the one realised in Nature or, conversely, establish a ground-breaking discovery. In this context, one should consider the importance of the reactor and source neutrino experiments attempting to clarify the “reactor anomaly”, possibly due to sterile neutrinos, or the proposed measurements of the neutrino mass hierarchy by atmospheric (PINGU(11), ORCA(12), INO(13)) and reactor neutrinos (JUNO(14),RENO-50(15)). The agencies also took note of the good progress in the evaluation of systematics affecting the measurements of the neutrino mass-hierarchy by PINGU and ORCA and encouraged their further coordination actions.
Finally, there is a rich and diverse physics program in the development of single beta and neutrino-less double beta decay experiments exploring the degenerate neutrino mass region till the end of this decade. The ambitious goal for neutrino-less double-beta decay in the next decade will be the coverage in sensitivity of the inverted mass-hierarchy region. Achieving this goal will require ton-scale detectors and may require large-scale enrichment of isotopes, boosting the scale of the infrastructures and, hence, demanding large international collaborations for their construction. This coordination would involve an effort similar to the one performed for the long-baseline program, but still requires the continuation of the current measurements and R&D work for the next two or three years. It further implies the coordination with agencies not currently present at the 2nd International Neutrino Meeting. In view of the above, the agencies will deploy the necessary efforts so that all major stakeholders coordinate in the next years in the effort to identify the most promising technologies for ton-scale detector(s) whose construction could start towards the end of this decade.
The agencies and the laboratory directors thanked the Neutrino ICFA panel(16) as well as the IUPAP working group of APPIC(17) for accompanying the process and providing key advice and insight on the program.
The 3rd International Neutrino Meeting on Large Neutrino Infrastructures, to review progress towards these aims, will take place in Japan in early 2016 at a venue to be decided later this year.
(1) In the meeting the agencies were represented by (in agency alphabetical order): J. Siegrist (associate director Department Of Energy, DOE), R. Pain (deputy 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), J. Seed (Associate Director of Science and Technology Facilities Council, STFC, UK), A. Ereditato (representing SNFS and SERI, Switzerland). H. J Donath from PT-DESY representing BMBF Germany. R. Davidson and G. Leveque (Vice-president and Director of programs respectively of the Canada Foundation of Innovation, CFI) participated as observers. APPEC was represented by its chair F. Linde.
(2) In the meeting the directors of laboratory present were (in laboratory alphabetical order): F. Gianotti director-general elect and S. Bertolucci director of research at CERN, N. Lockyer director of Fermi National Accelerator Laboratory, N. Roe director of Physics Division of LBL, J. Cao deputy director of Institute of High Energy Physics, IHEP of Beijing, N. Mondal Project 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, T. Kobayashi Deputy Director of the Institute of Particle and Nuclear Studies (IPNS) High Energy Accelerator Research Organization (KEK) in Japan, N. Smith director of the Sudbury Neutrino Observatory, SNOLAB, Dr. Kim SB director of RENO laboratory, Korea. The ICFA neutrino panel and APPIC were represented by K. Long and M. Spiro, respectively.
(3) Second International Meeting for Large Neutrino Infrastructures
(4) HEPAP/P5: The Particle Physics Project Prioritization Panel report was delivered and approved by the High Energy Physics Advisory Panel in May 2014
(5) APPEC (Astroparticle Physics European Consortium)
(6) LBNF/DUNE : Long-Baseline Neutrino Facility/ Deep Underground Neutrino Experiment
(7) Sanford Underground Research Facility
(9) ICARUS : Imaging Cosmic And Rare Underground Signals
(11) PINGU : Precision IceCube Next Generation Upgrade
(12) ORCA : Oscillations Research with Cosmics in the Abyss
(13) INO : India-based Neutrino Observatory
(14) JUNO : Jiangmen Underground Neutrino Observatory
(15) RENO-50 : Reactor Experiment for Neutrino Oscillation
(16) ICFA : International Committee for Future Accelerators neutrino panel
(17) APPIC: Astroparticle Physics International Committee