The Future of Neutrino Physics

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The Future of Neutrino Physics
SUPA Particle Physics Theme Launch 12 October
2005 Paul Soler University of Glasgow
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Contents
1. Present knowledge 1.1 Global fits 1.2 Unknown
facts 2. CP violation and q13 2.1 Super-beams 2.2
Neutrino factory concept 2.3 Physics reach of a
neutrino factory 2.4 Beta beams? 3.
Non-oscillation physics 4. Double beta decay 5.
UK activities in Neutrino Factories 5.1 Targets,
proton drivers 5.2 Hadron production yields 5.3
MICE
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1. Present knowledge
Neutrino oscillations discovered. Mixing
described by
For 3-flavour eigenstates U is Maki-Nakagawa-Sakat
a (MNS)
6 parameters 3 mixing angles - ?23,?12 and
?13 CP-violation angle - d
2 mass differences - ?m223 and ?m212
Transition probability
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1.1 Global fits

• Consistent picture emerging
• Information from atmospheric neutrinos, solar
  neutrinos, KamLand and reactor experiments used
  to extract parameters
• Global fit provides q23, q12, Dm122 and Dm232

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1.2 Unkown facts

• q13 not known
• CP violation phase d not known.
• Absolute neutrino mass scale not known
• Are neutrinos Majorana (ie. its own antiparticle)
  or Dirac
• Are there sterile neutrinos?
• Mass hierarchy not known

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2. CP Violation and q13

• First need to determine q13 using neutrino
  super-beams
• Do nm?ne oscillations and fit sin2q13 to

• Off-axis beams with 1-4 MW proton intensity
• Japanese T2K (Tokai to SuperK, 250 km) or
• MINOS off-axis (700 km)

Off-axis narrower energy band
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2.2 Neutrino factory concept

• Neutrino factory can provide sufficient neutrino
  luminosity to perform CP violation experiments at
  very long baseline 3000-7000 km.
• Conceptual design neutrinos produced from muon
  decay in storage ring. Rate calculable by
  kinematics of decay (Michel spectrum)

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2.3 Physics reach of a neutrino factory

• Far detector (3000-7000 km) can search for
  wrong-sign muons in appearance mode,
  disappearance of right-sign leptons, either e
  or m and possible appearance of t.
• Detectors
• Magnetised iron calorimeter?
• Liquid argon TPC?
• Totally active scintillator?
• Water Cherenkov, other?

• Can detect sign of Dm232 due to matter effects
  and determine CP violating phase d if it is large
  enough.

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2.3 Physics reach of a neutrino factory

• Determine q13 and CP phase d simultaneously need
  1021 muons/year
• Optimal CP phase sensitivity 6000 km but
• can obtain gt5s sensitivity for 1000-8000 km

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2.4 Beta beams?

• Beta beam beta decay of accelerated radioactive
  nuclei
• (P. Zucchelli, Phys. Lett. B, 532 (2002),
  166-172.)
• He-6 for neutrino production g 150
• Ne-18 for antineutrino production g 60
• Large Cherenkov detector at 150 km to perform
  oscillation searches.
  Measure CP violation and q13 with less
  background, since no need for charge selection.

d vs q13 sensitivity
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3. Non-oscillation physics

• High precision n-p and n-n deep inelastic
  scattering
• PDFs, nuclear shadowing
• ?S from xF3 - ??S0.003
• Vcd and Vcs, D0/ D0 mixing
• sin2?W - ?sin2?W 0.0001
• Polarised structure functions
• Beyond the SM searches
• n cross-sections for oscillations
• Other physics
• High muon flux flavour violating decays,
  muonium, muonic atoms, m-spin rotation,
  electroweak parameters
• High proton flux nuclear physics (heavy and
  exotic nuclei), nuclear astrophysics, atomic
  physics, medicine, materials,

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4. Double beta decay

• Double beta decay 35 possible beta emitters
  (even-even nuclei). Very rare (half-life more
  than 1020 years) since second order process.
• Beta decay kinematically forbidden and double
  beta kinematically allowed
• Neutrinoless double beta Majorana character of
  neutrino

• UK involvement in NEMO, Cobra

Aim 100 meV sensitivity
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5. UK activities in Neutrino factory RD

• UK Neutrino Factory Consortium Daresbury,
  Glasgow, Imperial College, Liverpool, Oxford,
  RAL, Sheffield, Warwick
• Many technological challenges for neutrino
  factory! Cost 2 bn
• Very high intensity proton drivers (4MW proton
  beams)
• Targets need to withstand shock-waves from
  protons and very rapid heating mercury jets,
  rotating band or cooled metal beads

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5.2 Hadron Production Yields

• Need hadron production yields from protons on
  targets to optimize neutrino factory energies
• HARP at CERN 2-15 GeV
• Preliminary results on Al target
• Useful for K2K expt.

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5.3 Muon Ionization Cooling Experiment (MICE)

Muon Ionization Cooling Experiment at RAL
demonstrates ionization cooling for neutrino
factory and muon collider
Squeezing of transverse emittance by ionization
and acceleration
MICE Phase I approved!!
Transverse emittance
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Outlook

• The Neutrino Factory is the ultimate tool for the
  study of neutrinos
• UK has established internationally recognised,
  broadly-based NuFact RD activity to demonstrate
  key technologies (not only MICE but also proton
  driver, targetry, neutrino detection etc.)
• SUPA partners already contributing to neutrino
  factory RD
• Glasgow, Edinburgh members of MICE MICE beamline
  simulation and diagnostics, measurement of
  emittance.
• Glasgow member of HARP hadron yields.
• Faraday partnership RF RD with Strathclyde
  University (Alan Phelps)
• Scoping study for World Design Study III
• Initiation of International Scoping Study to
  define parameters of neutrino factory physics,
  machine and detectors.
• Launched at NUFACT05 one year to define scope
  for World Design Study III based at RAL (design
  studies I II based at BNL and Fermilab).
• Aim produce robust proposal to EU FP7 for WDS
  (Mar 07)
• Main Glasgow involvement define detectors for
  neutrino factories
• SUSSP61 theme on Neutrinos, 8-23 August 2006, St
  Andrews.
• Many world leading figures in neutrino
  physics invited.