Super Beams, Beta Beams and Neutrino Factories (a dangerous trip to Terra Incognita) J.J. Gómez-Cadenas IFIC/U. Valencia Original results presented in this talk based on work done in collaboration with P. Hernández, J. Burguet & D. Casper

Evidence of oscillations LBL SB BB+NF Outline: A dangerous trip

You are here Evidence of neutrino oscillations

Kajita Inoe/Chen

Measure atmospheric oscillation parameters to ~10% Some sensitivity to  13 Long Base Line experiments ( )

Pb Emulsion layers  1 mm

Observe subleading oscillation Measure  13 Measure  23,  m 23 to O(1%) Super Beam experiments (1st generation) ( )

The first Super-Beam: T2K

Measurement of  23,  m 23 Observation of subleading oscillation

Measurement of  13. Correlations The appearance probability P(   13,   ) obtained for neutrinos at fixed (E,L) with input parameters (   13,   ) has no unique solution. Indeed the equation: has a continuous number of solutions Correlation error Cervera et al.

Measurement of  13 : Intrinsic degeneracy For neutrinos and antineutrinos of the same energy and baseline the system of equations has two intersections. The true one (   13,   ) and a second, energy dependent point (clone) that introduces and ambiguity in the determination of the parameters Degeneracy error

Discrete degeneracies Two other sources of degeneracy. 1.Ignorance of the sign of  m Ignorance of the octant of  23 These two discrete values assume the value  1

Eightfold degeneracy Experimental measurement. Number of observed chaged leptons N  Integrate P over , , and detector efficiencies. Since s atm & s oct not known, one should consider also 2 other equations which result in an 8-fold degeneracy

Huber & al Reactor experiments combine well with SB experiments and may be crucial to break degeneracies T2K and NOVA have similar E/L: Combination no optimal First generation SB experiments, together with new reactor experiments will go for discovery. If they see a signal, they will open the way to a next generation of neutrino experiments. Approaching Terra Firma: Circa 2020

Second Generation Super-Beams Apply the principle of bigger is better (caballo grande, ande o no ande) Enormous power ~4 MW Large detectors (~1Mton water Cerenkov) Notice: A second-generation super-beam comes as a by-product of the neutrino factory (but not necessarily as a by product of a beta-beam) T2K (phase II), SPL at CERN

CERN-SPL High power, low-energy neutrino super-beam

MTON water detector

Performance of SPL SB Burguet, Casper, Hernández, Mezzetto, JJGC

no BG signal stat only (signal+BG) stat only stat+2%syst. stat+5%syst. stat+10%syst. Systematic errors kajita Dependence of sensitivity with overall systematic error Super-Beams have some intrinsic limitations to its ultimate performance Intrinsic beam background Systematic errors in flux determination Cross sections

Measure (  13,  ) Neutrino mass hierarchy CP violation phenomena Neutrino Factories and Beta Beams (2020--)

Fluxes from muon and radioactive  ions decay

Neutrino Factory S. Geer ADR, Gavela, Hernández

Pb Emulsion layers  1 mm Detectors for NUFACT 10 x Minos 5 x Opera 10 x Icarus Cervera, Didak, JJGC Rubbia, Bueno, Campanelli Migliozzi

Golden & Silver channels at NUFACT ADR, Gavela, Hernández Donini, Migliozzi, Meloni

How to solve degeneracies 1.Use spectral information on oscillation signals  experiment with energy resolution 2.Combine experiments differing in E/L (and/or matter effects)  need two experiments 3.Include other flavor channels: silver channel e  . Need a tau-capable detector Burguet. Hernández, JJGC

Solving degeneracies at NUFACT donini SPLSB +NF

Sensitivity of NUFACT

Beta Beam P. Zucchelli

BB: The low gamma scenario Mezzetto Lindroos

NUFACT vs Low-gamma BB P. Hernández

S. Rigolín 8-fold Degeneracy in low-gamma BB

Sensitivity of low gamma BB+SPL BB+SB Poorer performance than Comparable facility, JHF- HK

Higher-gamma Beta Beam Low-gamma beta-beam: Conservative design sticking to today-technology solutions for acceleration and storage scheme. But higher energies can be achieved at CERN and elsewhere. One could imagine higher gamma factors: 125(250) -- pushing the SPS acceleration capabilities 350 (500) -- refurbished SPS, Tevatron… (4160) --- LHC Beta-Beam belongs to the Terra Incognita era (> 2020). One should seriously explore all available options and not stick to the conservative (convenient?) one.

Higher-gamma Beta Beam example P. Hernández

Major Physics improvement

Sensitivity Intermediate BB

New results: SPS limit gamma  He=150  Ne=250 Consider the maximum gamma factor that could be delivered by the SPS. This option is basically as “conservative” as the low beta option However, ion energy is in a better range for physics

Sensitivity as a function of distance Current design (or simpler!) Much improved sensitivity (but need to go to around 300 km!)

The options compared

High Energy BB What if  13 is very small? And it would be feasible to accelerate/store/extract heavy ions at the LHC? Migliozzi

On the sea First generation Super-Beams (T2K and NOVA) will allow us to cross the sea and reach Terra Incógnita by observing subleading transitions. To explore Terra Incognita, we need to burn our ships and build new facilities which will provide pure, intense and understood neutrino beams. These are the NuFACT and/or the Beta-Beam.

The Beta-Beam offers and alternative/complement to the Neutrino Factory. Different technology, different systematic errors and different E/L. Combination of both facilities is ideal to solve degeneracies. A future beta-beam facility will need for ultimate sensitivity 1Mton class detector. Such a detector has a great physics potential (proton decay, supernova observatory) of their own, but it is extraordinarily challenging to build (10-20 times the size of Super- Kamiokande). Costs and design effort from the machine side must be balanced with the effort, costs and time scale of such a detector. On Terra Firma

For best physics performance of the Beta Beam, higher neutrino energies are preferable to lower ones. Increasing the energy results in increasing the base- line. One cannot therefore fix the detector site or the machine site, but not both of them at the same time, before understanding the best operative energy. Terra Firma is probably still twenty years ahead us. This is the time to carefully consider all the possibilities, and let physics steer our ships. On Terra Firma