Neutrino Factory and Beta Beam Experiment

1
Neutrino Factory and Beta Beam Experiment

• NO-VE 2006
• Venice, Italy
• February 8, 2006
• Walter Winter
• Institute for Advanced Study, Princeton

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Contents

• Introduction
• Neutrino factory
• Basics
• Correlation and degeneracy resolution
• ISS study Current status
• Optimization
• New physics tests and other oscillation physics
• Beta beams
• Basics
• Optimization
• Comparison to neutrino factory
• Summary

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Three-flavor oscillations Requirements
AtmosphericoscillationAmplitude
q23Frequency Dm312
SolaroscillationAmplitude q12Frequency
Dm212
Sub-leading effect dCP
Coupling strength q13
Key to subleadingeffects (CP violation, mass
hierarchy)

• Neutrino oscillation parameters (1s)Dm212 8.2
  10-5 eV2 - 5sin22q12 0.83 - 5Dm312
  (2 2.5) 10-3 eV2sin22q23 1 - 7sin22q13 lt
  0.14dCP ?Mass hierarchy?

(see e.g. Bahcall et al, hep-ph/0406294
Super-K, hep-ex/0501064 CHOOZsolar papers)
Neutrino factory/Beta Beam if q13 small!
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Timescales

• This talk beyond next ten years!
• Neutrino factory
• Medium to high g beta beam
• But Note that Beta Beams possible on different g
  scales!

(from FNAL Proton Driver Study)
Beta Beam? Depends on g!
Timescale 2025?
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Neutrino factory

• Ultimate high precision instrument!?
• Muon decays in straight sections of storage ring
• Technical challenges Target power, muon cooling,
  charge identification, maybe steep decay tunnels

Decays
Target
Cooling
m-Accelerator
m
n
p
p, K
m
Wrong sign
Right sign
Wrong sign
Right sign
(from CERN Yellow Report )
(Geer, 1997 de Rujula, Gavela, Hernandez, 1998
Cervera et al, 2000)
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Storage ring and typical params?

• Goal 1021 useful muon decays/year. Two models

racetrack (not to scale)
triangular
m or m-

• Operate two baselines in two polarities
  successively4 years x 1021 m decays 4 years
  x 1021 m- decays

• Operate one baseline in two polarities
  simultaneously8 years x 5 1020 m decays 8
  years x 5 1020 m- decays

Other typical parameters (high-E neutrino
factory) Em 50 GeV, L 3,000 km (CP
violation) Detector 50 kt magnetized iron
calorimeter (more ambitious 100 kt, 10 years
running time ISS values)
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Appearance channels nm ne
(Cervera et al. 2000 Freund, Huber, Lindner,
2000 Freund, 2001)

• Complicated, but all interesting information
  there q13, dCP, mass hierarchy (via A)

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Correlations and degeneracies

• Connected (green) or disconnected (yellow)
  degenerate solutions (at a chosen CL) in
  parameter space
• Affect performance of appearance measurements.
  For example, q13 sensitivity

(Huber, Lindner, Winter, 2002)

• Discrete degeneracies (also Barger, Marfatia,
  Whisnant, 2001) Intrinsic (d,q13)-degeneracy
  (Burguet-Castell et al, 2001)sgn-degeneracy
  (Minakata, Nunokawa, 2001)(q23,p/2-q23)-degenerac
  y (Fogli, Lisi, 1996)

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More correlations Matter density

• For instance Measure dCP with high precision
  for large q13at L 3 000 km

Matter density uncertainties in 3D models
5 (http//cfauvcs5.harvard.edu/lana/rem/mapvi
ew.htm)
5 matter density uncertainty in mantlenot
acceptable for these measurements!Has to be of
the order of 1(Figure from Ohlsson, Winter,
2003see also Koike, Sato, 1999 Jacobsson et
al, 2001 Burguet-Castell et al, 2001 Geller,
Hara, 2001 Shan, Young, Zhang, 2001 Fogli,
Lettera, Lisi, 2001 Shan, Zhang, 2002 Huber,
Lindner, Winter, 2002 Ota, Sato, 2002 Shan et
al, 2003 Kozlovskaya , Peltoniemi, Sarkamo,
2003 others)
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NF measurements Performance indicators

• Matter of definition and hypothesisWhat
  indicator to use depends on purpose!
• Examples (dCP only!)
• Allowed region in d-q13-planeIdentify how much
  parameter space remains for specific hypotheses
  of simulated values
• Sensitivity to max. CP violation p/2 or 3p/2Can
  CP violation be detected for the hypothesis of
  max. CP violation?
• Sensitivity to any CP violationFor what
  fraction of CP violating values can CP violation
  be detected? (CP fraction plots!)
• Precision of d ?How precisely can one measure d?
  (only defined in the high precision limit, since
  d cyclic also not Gaussian!)
• CP coverageHow precisely can one measure d or
  what fraction of the parameter space can be
  excluded?

True values Few examples
Purpose Looks like result
Level of condensation, computation time
Purpose Risk minimization
True values Complete relevant space
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NF measurements Example dCP coverage

• Define CP coverage Fraction of all fit values
  of d which fit a chosen true d 0 lt CP coverage
  lt 360o

CP scaling
CP pattern
Degeneracy problemeven bigger thanfor max. CP
violation!
(Dc2 9, 4, 1 dashed no degs)
(Fig. from Huber, Lindner, Winter, hep-ph/0412199)

• True values of d and q13 affect topology!
  Degeneracies!
• But Degeneracies not everywhere in param. space
  important

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NF-Strategies to resolve degeneracies depend on
sin22q13!
Intrinsic degeneracy disappears for better energy
threshold!

• Combine with superbeam upgrade(sin22q13 gt 10-3)
  (Burguet-Castell et al, 2002)
• Combine with silver channels ne -gt nt
  (sin22q13 gt 10-3 ?)(Donini, Meloni, Migliozzi,
  2002 Autiero et al, 2004)
• Better detectors Higher energy resolution,
  higher efficiencies atlow energies (CID!)
  (sin22q13 gt ?)(Will be important aspect in ISS
  study!)
• Second NF baseline Magic baseline (sin22q13 gt
  10-4)(Lipari, 2000 Burguet-Castell et al, 2001
  Barger, Mafatia, Whisnant, 2002 Huber, Winter,
  2003 others)
• Other possibilities?

sin22q130.001
(Fig. from Huber, Lindner, Winter, 2002)
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Example Magic baseline

• IdeaYellow term 0 independent of E,
  oscillation parameters

• Purpose Clean measurement of q13 and mass
  hierarchy
• Drawback No dCP measurement at magic baseline
• combine with shorter baseline, such as L3 000 km
• q13-range 10-4 lt sin22q13 lt 10-2,where most
  problems with degeneracies are present

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Magic baseline q13 sensitivity

• Use two-baseline space (L1,L2) with (25kt, 25kt)
  and compute q13 sensitivity including
  correlations and degeneracies

No CP violation measurement there!
Animation in q13-dCP-space
Optimal performance for all quantities
Unstable Disappears for different parameter
values
dCP
(Huber, Winter, 2003)
sin22q13
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CP coverage and real synergies
Any extra gain beyond a simple addition of
statistics

• 3 000 km 7 500 kmversus all detector mass at
  3 000 km (2L)
• Magic baseline allows a risk-minimized
  measurement (unknown d)
• Staged neutrino factory Option to add magic
  baseline later if in bad quadrants?

One baseline enough
Two baselines necessary
(Huber, Lindner, Winter, 2004)
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ISS studyInternational scoping study of a future
neutrino factory and super-beam facility

• Establish physics case for a facility
  (accelerator complex and detection systems) for a
  future long-baseline neutrino oscillation program
• Define requirements Muon energy, baselines,
  channels,
• Three working groups Physics, accelerator,
  detector(Dornan Blondel, Nagashima, Zisman
  King, Long, Roberts, Yasuda many others)
• Next plenary meeting April 24-29, 2006 at RAL
  (UK)
• Final written report September 2006?
• More information http//www.hep.ph.ic.ac.uk/iss/

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ISS issues Physics cases?
(Huber/POFPA report)

• Examples (q13 only)
• Large q13 sin22q13 gt 0.01(Physics case for
  NuFact at all? vs. Superbeams?)
• Small q13 10-4 lt sin22q13 lt 10-2(NuFacts
  golden age?)
• Zero q13 sin22q13 ltlt 10-4(What physics can be
  done? What does that mean?)
• Maybe Only build NF if T2K, Double Chooz etc. do
  not see a signal?

1
2
3
Neutrino factory!(or higher gamma beta beam)
Beta beam?Superbeam-Upgrade?n-factory?
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ISS issues Better detector?

• Better threshold (low-E efficiencies) helps for
  all measurements!
• Better energy resolution helps somewhat

(Huber, Lindner, Rolinec, Winter, to appear)
Preliminary

• Better threshold (low-E efficiencies) helps for
  all measurements
• Better energy resolution helps somewhat
• Better detector may be key component in large q13
  discussion

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Physics case for q130?
Establish MSW effect for q130by solar
oscillation (appearance prob.) L gt 5,500
km (Winter, 2004)
Determine mass hierarchy for q130(disappearance
probability) L 6,000 km (de Gouvea, Jenkins,
Kayser, 2005 de Gouvea, Winter, 2005)
Very long (gtgt 3,000 km) baseline important
component of any such program!Theoretical q130
would be an important indicator for some symmetry!
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Optimization of a neutrino factory

• Example q13 sensitivity relative to minimum in
  each plot (3s)
• Important resultSince muon energy 40 GeV
  enough?!
• Threshold effects

Preliminary
(Huber, Lindner, Rolinec, Winter, to appear
also Freund, Huber, Lindner, 2001)
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Disappearance channels

• Disappearance information important to reduce
  errors on leading parameters(see e.g. Donini,
  Fernandez-Martinez, Rigolin, 2005 Donini,
  Fernandez-Martinez, Meloni, Rigolin, 2005)
• Idea Use data sample without charge
  identification for disappearance, i.e., add
  right and wrong sign muon events
• Better efficiencies!

sin22q13 precision
(Fig. from Huber, Lindner, Winter, 2002)
Preliminary
sin22q13 0
(de Gouvea, Winter, 2005 Huber, Lindner,
Rolinec, Winter, to appear)
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Beyond three-flavor oscillations?

• Test unitarity and small ad-mixtures of new
  physics by
• nt detection PeePemPet 1? (Donini, Meloni,
  Migliozzi, 2002 Autiero et al, 2004)
• Neutral currents (hard, but harder than 1.?)
  (Barger, Geer, Whisnant, 2004)
• Construction of unitarity triangles? (Xing,
  Zhang, 2004/2005)
• Spectral signature for probability-level
  effectsExample Damping effects(Blennow,
  Ohlsson, Winter, hep-ph/0502147)
• More complicated Hamiltonian-level effects
  Spectrum shifts(e.g., Blennow, Ohlsson, Winter,
  hep-ph/0508175)Example Oscillation-NSI
  confusion theorem(Huber, Schwetz, Valle, 2002)

Characteristic enhancement/ depletion in certain
regions of spectrum while oscillation nodes
remain unchanged
Search for new physics motivated by
manytheoretical effects, suchas neutrino decay,
decoherence,search for steriles, LFV, extra
dimenstions,
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Other physics Geophysics?

• Example Measure inner core density rIC
• Per cent level precision not unrealistic
• Survives unknown oscillation parameters
• More recent discussions Discriminate seismically
  degenerate geophysics models in mantle, test plum
  hypothesis etc.?

sin22q130.01
JHF
BNL
CERN
(Winter, 2005)
Inner core shadow
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Beta beam

• Compared to superbeam no intrinsic beam BG
  limiting the sin22q13 sensitivity to gt 10-3
• Compared to neutrino factory no charge
  identification required
• In principle, very interesting alternative
  concept!

• Key figure (any beta beam)Useful ion
  decays/year?
• Standard values3 1018 6He decays/year1 1018
  18Ne decays/year
• Can these be achieved?
• Typical gamma 100 150 (for CERN SPS)

(Zucchelli, 2002)
(CERN layout Bouchez, Lindroos, Mezzetto, 2003
Lindroos, 2003 Mezzetto, 2003 Autin et al, 2003)
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From very low to high gamma

• Very low gamma (glt150?)
• Alternative to superbeam?
• Originally designed for CERN (SPS)
• Water Cherenkov detector
• (see before also Volpe, 2003)
• Low gamma (150ltglt300-350?)
• Alternative to superbeam!
• Possible at upgraded SPS?
• Water Cherenkov detector
• (Burguet-Castell et al, 20042005 Huber et al,
  2005)
• Medium gamma (300-350ltglt800?)
• Physics potential compared to effort?
• Requires large accelerator (Tevatron-size)
• Water Cherenkov detector or TASD or?
• (Burguet-Castell et al, 2004 Huber et al, 2005)
• High gamma (ggt800?)
• Alternative to neutrino factory?
• Requires very large accelerator (LHC-size)
• Detector technology other than water (TASD?)

Gamma determines neutrino energyand therefore
detector technology!
(Fig. from Huber, Lindner, Rolinec, Winter, 2005)
(for NOvA-like detector!)
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Optimization of a beta beam

• Baseline optimization depends on goals and
  gamma(Fig. from Huber, Lindner, Rolinec,
  Winter, 2005)
• For lower gamma Second osc. max. useful to
  resolve degs
• Neutrino/antineutrino running Have at least
  10-20 of originally proposed flux!

(for other degeneracy studies see, e.g. Donini,
Fernandez-Martinez, Rigolin, 2004 Donini,
Fernandez-Martinez, Migliozzi, Rigolin, 2004)
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Beta beam vs. Superbeam vs. NuFact?

• Lower gCan easily compete with superbeam
  upgrades if properly optimized
• Higher gAt least theoretically competitive to a
  neutrino factory
• Challenges
• Can fluxes be reached?
• Compare completely optimized accelerator
  strategies?

(Fig. from Huber, Lindner, Rolinec, Winter, 2005)
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Beta beam in ISS study (from talk given by Elena
Couce on Jan. 24 at KEK)

• Use of Water Cherenkov detector
• New efficiency andBG matrices for migration
• High gamma beta beambest alternative (even low
  flux)

Two differentoptions!
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Summary Key questions

• What if q13 is large? Do we need a NuFact/Beta
  beam programin this case?
• NuFact
• Feasibility of muon cooling, target power etc.
  (MICE, )
• Flexible storage ring concept for different
  physics scenarios?
• Detector Is there space for improvement?
• Beta beam
• Feasibility? Competitiveness? Price tag?
• Probably depends on gamma!
• Stored ions?
• Answers from EURISOL design study?
  http//www.eurisol.org/