Super Beams, Beta Beams and Neutrino Factories (a dangerous trip to Terra Incognita)

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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

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Outline A dangerous trip
BBNF
SB
LBL
Evidence of oscillations
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Evidence of neutrino oscillations
You are here
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Inoe/Chen
Kajita
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Long Base Line experiments
(2005-2015)
Measure atmospheric oscillation parameters to
10 Some sensitivity to q13
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Super Beam experiments (1st generation)
(2010-2020)
Observe subleading oscillation Measure
q13 Measure q23 ,Dm23 to O(1)
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The first Super-Beam T2K
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Observation of subleading oscillation
Measurement of q23 ,Dm23
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Measurement of q13. Correlations
The appearance probability P(?q13,?d) obtained
for neutrinos at fixed (E,L) with input
parameters (?q13,?d) has no unique solution.
Indeed the equation
has a continuous number of solutions
Correlation error
Cervera et al.
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Measurement of q13 Intrinsic degeneracy
For neutrinos and antineutrinos of the same
energy and baseline the system of equations
has two intersections. The true one (?q13,?d) and
a second, energy dependent point (clone) that
introduces and ambiguity in the determination of
the parameters
Degeneracy error
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Discrete degeneracies

• Two other sources of degeneracy.
• Ignorance of the sign of Dm232
• Ignorance of the octant of q23

These two discrete values assume the value ?1
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Eightfold degeneracy
Experimental measurement. Number of observed
chaged leptons Nb Integrate P over Fn, s, and
detector efficiencies.
Since satm soct not known, one should consider
also 2 other equations which result in an 8-fold
degeneracy
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Approaching Terra Firma Circa 2020
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.
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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
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CERN-SPL
High power, low-energy neutrino
super-beam
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MTON water detector
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Performance of SPL SB
Burguet, Casper, Hernández, Mezzetto, JJGC
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Systematic errors
kajita
Super-Beams have some intrinsic limitations to
its ultimate performance Intrinsic beam
background Systematic errors in flux
determination Cross sections
Dependence of sensitivity with overall systematic
error
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Neutrino Factories and Beta Beams
(2020--)
Measure (q13,d) Neutrino mass hierarchy CP
violation phenomena
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Fluxes from muon and radioactive b ions decay
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Neutrino Factory
ADR, Gavela, Hernández
S. Geer
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Detectors for NUFACT
10 x Minos 5 x Opera 10 x Icarus
Migliozzi
Cervera, Didak, JJGC
Rubbia, Bueno, Campanelli
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Golden Silver channels at NUFACT
ADR, Gavela, Hernández
Donini, Migliozzi, Meloni
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How to solve degeneracies
Burguet. Hernández, JJGC

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 ne
   ? nt. Need a tau-capable detector

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Solving degeneracies at NUFACT
SPLSBNF
donini
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Sensitivity of NUFACT
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Beta Beam
P. Zucchelli
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BB The low gamma scenario
Mezzetto Lindroos
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NUFACT vs Low-gamma BB
P. Hernández
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8-fold Degeneracy in low-gamma BB
S. Rigolín
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Sensitivity of low gamma BBSPL
Poorer performance than Comparable facility,
JHF-HK
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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. 2500 (4160)
--- LHC Beta-Beam belongs to the Terra Incognita
era (gt 2020). One should seriously explore all
available options and not stick to the
conservative (convenient?) one.
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Higher-gamma Beta Beam example
P. Hernández
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Major Physics improvement
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Sensitivity Intermediate BB
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New results SPS limit gamma
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
g-He150 g-Ne250
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Sensitivity as a function of distance
Current design (or simpler!) Much improved
sensitivity (but need to go to around 300 km!)
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The options compared
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High Energy BB
What if q13 is very small? And it would be
feasible to accelerate/store/extract heavy ions
at the LHC?
Migliozzi
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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.
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On Terra Firma
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.
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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.