Road Map of Future Neutrino Physics A personal view Ken Peach Round Table discussion at the 6 th NuFACT Workshop Osaka, Japan 26 th July – 1 st August 2004

Ken Peach NuFact04, 26 th July to 31 st August 2004, Osaka, Japan Key questions 1.Is the LSND effect real? (Desperately waiting for MiniBooNE) If LSND effect real What happens to the Standard Model? What experimental programme is required? 2.Is  13 >0? Need T2K, “child-of-CHOOZ”, … If  13 =0 (or <<1 o ) Why? What next? 3.What is the absolute mass scale? KATRIN, 0 , cosmology/astrophysics? It makes a difference if m lightest = 0eV, eV, eV 4.Do neutrinos have a Majorana component? 0  If not, why not? If yes How to measure the phases? What is the Majorana mass mechanism?

Ken Peach NuFact04, 26 th July to 31 st August 2004, Osaka, Japan Let us assume LSND is not confirmed  13 >0  13 precisely –Need to understand the hierarchy of the angles Phase angle  precisely –Need to look for CP/T violation –  may not be large Determine the sign of  m 2 23 –Possibly parasitic on one of the above Determine the absolute mass scale –KATRIN, 0 , cosmology/astrophysics Look for 0  … then we need to measure… When? Note LSND apart SK, SNO, KL, K2K show that non-standard effects aresmall

Ken Peach NuFact04, 26 th July to 31 st August 2004, Osaka, Japan Oscillations: What to Measure? Neutrinos e disappearance e   appearance e   appearance  disappearance   e appearance    appearance … and the corresponding antineutrino interactions Note: the beam requirements for these experiments are: high intensityknown flux known spectrum known composition (preferably no background)

Ken Peach NuFact04, 26 th July to 31 st August 2004, Osaka, Japan CP sensitivity domain of 99% CL effect for maximal CP violation Bouchez Degeneracies – need complementary measurements (baselines, energies, flavours, channels)      

Ken Peach NuFact04, 26 th July to 31 st August 2004, Osaka, Japan How to get there? Build the Neutrino Factory as soon as possible Numi/CNGS, Off-Axis Beams, SuperBeams, Beta Beam, Neutrino Factory The Fast TrainThe Slow Train

Ken Peach NuFact04, 26 th July to 31 st August 2004, Osaka, Japan How to choose? The Fast Train Advantages –fastest route (possibly) –cheapest route (possibly) Disadvantages –money (big commitment) –politics (related to money) The Slow Train Advantages –incremental (duplication?) –lower risk (e.g. if no CPV) Disadvantages –costs more (duplication) –may never get there (why measure better?)

Ken Peach NuFact04, 26 th July to 31 st August 2004, Osaka, Japan A Neutrino Factory is … … an accelerator complex designed to produce >10 20 muon decays per year directed at a detector thousands of km away Principal Components High Power H (-) source Proton Driver TargetCapture Cooling Muon Acceleration ‘near’ detector ( km) ‘far’ detector ( km) Muon Storage Ring ‘local’ detectors

Ken Peach NuFact04, 26 th July to 31 st August 2004, Osaka, Japan Neutrino Factory Challenges Technology –Proton driver RCS or LINAC? –Proton energy? HARP, E910, MIPP –Target MW beam power –Mercury, solid, liquid-cooled, pellet, … –Pion/muon collection and/or cooling Magnetic Horns or Solenoids? Phase Rotators, FFAG’s, cooling (ring, linear, …)? –RF and acceleration RLA’s or FFAG’s? –Muon Storage Ring Racetrack, triangular or bow-tie Conventional or FFAG? Options x x 2  5184  72 Some don’t work – divide by 2 ¾ don’t make any sense 36 9 Not all match efficiently ~ 9 feasible NF designs!!!!

Ken Peach NuFact04, 26 th July to 31 st August 2004, Osaka, Japan Neutrino Factory R&D High Power proton drivers –MW power, ns pulses RF –30% of the cost? Cooling –How much? (20% of the cost?) RLA or FFAG? –Which is cheaper? BNL Feasibality Study 2

Ken Peach NuFact04, 26 th July to 31 st August 2004, Osaka, Japan Summary My view –we will need a neutrino factory especially if the neutrino sector is more complicated than 3 generation mixing –there are enough technology options to be confident that it will work but we need demonstrators –need to avoid (too much) duplication (how many Megaton Water Cerenkov’s equal one Neutrino Factory?)