Round table discussion with

1. The road map to future neutrino oscillation experiments Round table discussion with Steve Geer (Spokesperson of the Muon Collaboration) Helmut Haseroth (Chair of European Neutrino study Group, CERN) Kenzo Nakamura (Head of PS physics division, KEK) Ken Peach (Director of Particle Physics Division, RAL) Some questions from the moderator: 1. When? should we propose/decide on Neutrino Factory? how many steps (superbeam, megaton, betabeams etc….) before? 2. What are the accelerator R&D presrequisites in order to decide? 3.13 ? What do you think of the statement that one must have proven 13  0 before making the decision? 4 how about detector R&D?

2. The Neutrino Road Map Experiments to find q13 : 1. search for nmne in conventional nm beam (MINOS, ICARUS/OPERA) ==> 2005-2012 • limitations: NC p0 background, intrinsic ne component in beam • 2. Off-axis beam (JParc-SK, off axis NUMI,off axis CNGS) • (~2009-2014) or reactor experiments • 3. Low Energy Superbeam (BNL  Homestake, SPL Fréjus or J-Parc-HyperK) (~2014-2020) Precision experiments to find CP violation -- or to search further if q13 is too small 1.beta-beam 6He++  6Li+++ ne e- and 18Ne 10+  18F 9+ne e+ (also 2014-2020?) 2. Neutrino factory with muon storage ring (~2020) fraction thereof will exist . m+ e+ne nmand m- e-ne nm

3. CERN-SPL-based Neutrino SUPERBEAM 300 MeV n m Neutrinos small contamination from ne (no K at 2 GeV!) Fréjus underground lab. A large underground water Cerenkov (400 kton) UNO/HyperK or/and a large L.Arg detector. also : proton decay search, supernovae events solar and atmospheric neutrinos. Performance similar to J-PARC II There is a window of opportunity for digging the cavern starting in 2008 (safety tunnel in Frejus or TGV test gallery)

4. -- Neutrino Factory --CERN layout 1016p/s 1.2 1014 m/s =1.2 1021 m/yr _ 0.9 1021 m/yr m+ e+ne nm 3 1020 ne/yr 3 1020 nm/yr oscillates ne nm interacts givingm- WRONG SIGN MUON interacts giving m+

5. CERN: b-beam baseline scenario Nuclear Physics SPL Decay ring Brho = 1500 Tm B = 5 T Lss = 2500 m SPS Decay Ring ISOL target & Ion source ECR Cyclotrons, linac or FFAG Rapid cycling synchrotron PS

6. Possible planning CDR 2 3 MeV test place ready RF test place ready Linac4 approval SPL approval LHC upgrade if the SPL is firmly supported… funding window

8. Superbeam & Beta Beam cost estimates E

9. Neutrino Factory studies and R&D USA, Europe, Japan have each their scheme. Only one has been costed, US study II: + detector: MINOS * 10 = about 300 M€ or M$ Neutrino Factory CAN be done…..but it is too expensive as is. Aim: ascertain challenges can be met + cut cost in half.

10. Conclusions(neutrino) There is a baseline scenario for future neutrino facilities in Europe -- for discussion. --SPL + accumulator+target station and Low energy WBB give a superbeam aimed at very large underground detector(s) (WC and/or Larg) which has other applications (N decay and astronophysical neutrinos) -- possibly (easier if Eurisol choses CERN as host) a betabeam facility which has the nice feature to use the same detector! -- the long term goal is a neutrino factory. -- R&D on critical items should proceed: proton driver, targets, collection, muon cooling

11. Conclusions (Euro-centered) Unique opportunities exist in Europe: 1. Unique LHC(+PS,+SPS) upgraded+ Superbeam + betabeam + rare m decays synergies at CERN (accelerator complex + Isolde/Eurisol Expertise and physics ) 2. The Superconducting proton Linac option has (much) more potential for ultimate intensities -- the 'best' energy should be optimized. 3. Deep underground megaton laboratory opportunities in Europe at adequate distance (Fréjus…) 4. these are first steps towards Neutrino Factories and muon colliders.

12. we should take into account the windows of opportunity that open to us: --safety galleries/TGV under the alps --project gap at CERN between end-of-LHC and start of CLIC. these are numerically well matched to the above baseline road map. 'Good enough is best' 'il meglio é nemico del bene'.