Physics and Technology at a Neutrino Factory

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Physics and Technology at a Neutrino Factory
Seminar University of Bonn 18 May 2006 Paul
Soler University of Glasgow
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Contents
Thank you to many colleagues for letting me
borrow their slides!

1. Neutrino Standard Model
2. Neutrino Oscillations
3. Atmospheric neutrinos
4. Solar neutrinos
5. Three neutrino oscilllations
6. Future neutrino experiments
7. Physics Reach of a Neutrino Factory
8. Neutrino Factory Design
9. Far Detectors at a Neutrino Factory
10. Near Detector at a Neutrino Factory
11. NOMAD-STAR, a near detector prototype
12. Near detector ideas

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1. Neutrino Standard Model

• 6 quark masses
• mu , mc, mt
• md, ms, mb
• 3 lepton masses
• me, mm, mt
• mne, mnm, mnt 0
• 2 vector boson masses
• Mw, MZ (mg, mg0)
• 1 Higgs mass
• Mh
• 3 coupling constants
• GF, a, as
• 3 quark mixing angles
• q12, q23, q13
• 1 quark phase
• d

Three neutrinos are massless ? no mixing, no
right handed n
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2. Neutrino Oscillations

• If neutrinos have mass, they can mix like quarks
• 2 flavours (a b) 2 mass eigenstates (i j)

Neutrino oscillations
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3. Atmospheric Neutrinos

• Atmospheric neutrinos neutrino production from
  cosmic rays in atmosphere
• Protons hit atmosphere pions produced that decay
  (on average) into 2 muon neutrinos for each
  electron neutrino produced in an interaction

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3. Atmospheric Neutrinos

• Super-Kamiokande experiment 50,000 tons of
  water, surrounded by 11,000 phototubes to detect
  Cherenkov light in the water.

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3. Atmospheric Neutrinos
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3. Atmospheric Neutrinos

• Super-Kamiokande zenith angle distributions

Upward-going neutrinos depleted, while
upward-going electron neutrinos slightly higher
than expected proof of neutrino oscillations!
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3. Atmospheric Neutrinos
Oscillation parameters

• Super-Kamiokande L/E

Most likely transition nm-gt nt oscillations
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3. Confirmation Atmospheric Neutrinos

• K2K 12 GeV proton synchrotron at KEK to Kamioka
  mine (Japan). L250 km, ltEgt1.4 GeV. Running.

Observed 108 events in Super-K Expected (no
oscillation) 150.911.6-10.0
K2K Front Detector
Best fit 104.8 events
Probability no oscillation lt 1
Compatible with Super-K atmospheric Oscillation p
arameters.
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3. Confirmation Atmospheric Neutrinos

• Long baseline accelerator experiments confirms
  atmospheric results
• MINOS neutrinos from Main Injector (NuMI) at
  Fermilab to Soudan (Minnesotta). L730 km, ltEgt16
  GeV. Started running January 2005

nm disappearance confirms atmospheric result.
Next step ne appearance experiment
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4. Solar Neutrinos

• Standard Solar Model 4 hydrogen atoms burn in
  thermo-nuclear reactions to produce helium,
  neutrinos and energy
• Measured photon luminosity is 3.9x1026 J s-1.
• Energy per reaction 26.7 MeV 4.3x10-12 J
• Number of reactions 3.9x1026/4.3x10-12
  9.1x1037 s-1
• Distance sun-earth 1.5x1013 cm.

(64 billion neutrinos per second in 1 cm2
!!!!)
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4. Solar Neutrinos

• pp cycle 98.5 of the total suns power comes
  from these reactions
• CNO cycle catalysed by C, N and O only produces
  1.5 of power output
• Low energy (lt0.42 MeV) pp reaction (flux 6.0x1010
  cm-2 s-1) most abundant
• 8B neutrinos (lt14 MeV) only 10-4 total

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4. Solar Neutrinos

• Ray Davis Chlorine experiment inside Homestake
  mine in Lead, South Dakota

100,000 gallons (615 tons) cleaning fluid (C2Cl4)
Expect about 1.5 Ar atoms/day
Extract Ar and count in proportional counter
2.82 keV K-shell x-rays
Observation about 1/3 the expected number of
solar neutrinos
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4. Solar Neutrinos

• Results Super-Kamiokande experiment
• Proof that neutrinos come from sun angular
  correlation
• Neutrino flux is 46.5 that expected from the
  solar model

Confirmation Solar Neutrino Puzzle!
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4. Solar Neutrinos

• Sudbury Neutrino Observatory (Sudbury, Ontario,
  Canada).

1000 tonnes D2O, 6500 tonnes H2O, 10,000 PMTs
Phototube Support Structure (PSUP)
1000 tonnes D2O
Surface 2 km
Acrylic Vessel
6500 tonnes H2O
104 8 PMTs
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4. Solar Neutrinos

• First results with D2O
• Charged current (CC)
• Elastic scattering (ES)
• Neutral current (NC)

(0.35-0.02 SSM)
(Thresholdgt1.442 keV)
(1.01-0.12 SSM)
(Thresholdgt2.225 keV)
About 35 electron neutrinos make it to earth
(from CC) but flux of all neutrino species
(from NC and ES) as expected
Neutrinos change species in flight Neutrino
Oscillations!
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4. Solar Neutrinos

• Confirmation of results with with salt data

• All results consistent with oscillations
• ne CC rate is 0.31 SSM
• n ES rate consistent with Super-Kamioka
• NC rate (all n) as expected
• Neutral currents detected through neutron capture
  on 35Cl (increases NC sensitivity)

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4. Solar Neutrinos

• Global picture of solar neutrinos after SNO
  results Large Mixing Angle (LMA) solution of
• neutrino oscillations

• Interpretation solar neutrino results MSW
  resonant neutrino oscillations in the sun

Before SNO
After SNO
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4. Confirmation Solar Neutrinos

• KAMLAND reactor experiment in Kamioka mine
  (Japan) confirms Large Mixing Angle (LMA)
  solution of solar neutrino problem.
• Observed/Expected 0.611-0.085-0.041
• Average distance (L) to reactors 175-35 km

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4. Confirmation Solar Neutrinos

• Spectral distortions in KAMLAND no distortions
  fit 0.4 CL
• Best fit to
• Therefore

Independent confirmation of solar Neutrino
oscillation parameters!
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5. Three Neutrino Oscillations

• Neutrino oscillations well established!!
• CHOOZ reactor experiment (France) set limits on
  disappearance ltEgt6MeV, L1km
• Three neutrino flavour mixing Pontecorvo-Maki-Nak
  agawa-Sakata (PMNS) matrix
• Similar mixing matrix to CKM matrix

• where

• and

• Mixing of states

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5. Three Neutrino Oscillations

• Oscillations of three neutrino families, if

with

• Oscillations, if not negligible

(Jarlskog coefficient for CP violation)
q13?0
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5. Neutrino oscillation global fits

• Consistent picture emerging
• Global fit provides q23, q12, Dm122 and Dm232
• q13 not known, mass hierarchy not known,CP
  violation phase d not known!!

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6. Future Neutrino Experiments

• First, need to determine q13 possibly using
  neutrino super-beams
• Do nm-gtne oscillations and fit sub-leading
  oscillations sin2q13 to

• Possible super-beams 1-4 MW proton intensity to
  generate beam of neutrinos. Off-axis for better
  determination neutrino energy. For example MINOS
  off-axis (700 km) or Japanese T2K (Tokai to
  SuperK, 250 km)

Off-axis narrower energy band
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6. Future Neutrino Experiments

• Japanese JPARC (Tokai) Hadron Facility T2K
  (Tokai to SuperK, 295 km)

Discovery of ne appearance q13 Dm213
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6. Search for q13 and CP Violation

• For CP violation need to compare
  with
• Make CP asymmetry parameter
• Three neutrino oscillations in matter (through
  earth) mass heirarchy and CP phase accessible
  due to

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7. Physics Reach of a Neutrino Factory

• Matter-antimatter asymmetry of the universe
  baryogenesis (CP violation in quark sector),
  leptogenesis (CP violation in lepton sector)

• Neutrino factory very long baseline oscillation
  experiments to measure q13, mass hierarchy and
  leptonic CP violation

• Conceptual design neutrinos produced from muon
  decay in storage ring. Rate calculable by
  kinematics of decay (Michel spectrum)

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7. Physics Reach of a Neutrino Factory

• Far detector (3000-7000 km) can search for
  wrong-sign muons in appearance mode (gold
  channel), disappearance of right-sign leptons,
  either e or m and possible appearance of t
  (silver channel)
• Can detect sign of Dm232 due to matter effects
  and determine CP violating phase d if it is large
  enough.

Gold channel
Silver channel
Platinum channel
Silver channel
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7. Physics Reach of a Neutrino Factory

• Far detector (3000-7000 km) can search for
  wrong-sign muons in appearance mode (for
  example, Large Magnetic Detector)

Large Magnetic Detector

• Background charm production, charge
  misidentification.
• Qt Pm sin2 q cut eliminates backg at 10-6

• Other Detectors liquid argon TPC, water
  Cherenkov, emulsion can search for either e, m or
  t appearance

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7. 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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7. Physics Reach of a Neutrino Factory
P. Huber et al. 2006
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8. Neutrino Factory Design
Optimization in progress at International Scoping
Study report Autumn 2006

• Proton Driver
• primary beam on production target
• Target, Capture, Decay
• create ?, decay into ?
• Bunching, Phase Rotation
• reduce ?E of bunch
• Cooling
• reduce transverse emittance
• Acceleration
• 130 MeV ? 20-50 GeV
• Decay Ring
• store for 500 turns long straight section

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8. Neutrino Factory Design
1. Proton Drivers

• Technology depends on host laboratory JPARC,
  Brookhaven, Fermilab, CERN, RAL
• In Japan upgrade of JPARC to 4 MW
• Brookhaven AGS upgrade

• Fermilab 8 GeV superconducting LINAC

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8. Neutrino Factory Design
1. Proton Drivers

• At RAL 5-30 GeV synchrotrons

• At CERN, Superconducting Proton LINAC (SPL) 3.5
  GeV

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8. Neutrino Factory Design
Probably optimum energy is between 5 and 15 GeV
Need hadron production data (HARP experiment at
CERN) to verify models on which prediction is
based.
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8. Neutrino Factory Design

• HARP at CERN Pion production yields from
  protons on different targets to optimize neutrino
  factory energies
• Proton energies 2-15 GeV
• First results on Al target (qlt210 mrad)
• Useful for K2K expt.

Pion production
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8. Neutrino Factory Design
2. Target, capture, decay

• Carbon (solid) targets can withstand up to 1 MW
  beams

• Above 1 MW need to do something different Hg
  jets in 20 T solenoid field for pion capture
• MERIT experiment at CERN Hg in 20 T
  solenoid field

MARS simulations indicate 10 GeV protons on Hg
seem to provide best pion yield
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8. Neutrino Factory Design
3. Bunching, phase rotation

• Preferred RF cavities
• Bunching and phase rotation
• bunch width 2 ns

Phase rotation achieves monochromatic beam of
pions
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8. Neutrino Factory Design
4. Muon ionization cooling needed to achieve
1021 m/yr
20 cost of neutrino factory
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8. Neutrino Factory Design
Muon Ionization Cooling Experiment (MICE) at
RAL demonstration experiment of ionization
cooling
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8. Neutrino Factory Design
Fixed Field Alternating Gradient
(FFAG) developments in Japan
5. Acceleration
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8. Neutrino Factory Design
6. Decay rings
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9. Far Detector Designs

• Large Magnetic Iron Detector
• 40-100 kton
• B field 1 T
• Transverse resolution 1 cm
• Readout scintillator (liquid or solid) or RPC

Baseline option wrong sign muon golden channel
Optimised for small q13 Strong cut on muon
momentum gt 5 GeV/c Problems below muon momentum lt
3 GeV/c (cannot see second maximum)
1cm transverse resolution
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9. Far Detector Designs

• Attempting optimisation of segmented magnetic
  detector
• Iron free regions improve momentum and charge
  determination

• Combining iron-free regions with liquid
  scintillator to improve electron ID and to reduce
  momentum threshold.

Liquid scintillator
iron
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9. Far Detector Designs
100 kton detector with double phase readout 20 m
drift
Very large liquid argon detectors
GLACIER in Europe
FLARE in USA
Charge readout plane
Electronics racks
Gas Ar
E 3 kV/cm
Dp lt 0.1 atm
Extraction grid
Liq. Ar
Scint. (UV) and C light readout by PMTs
Field shaping electrodes
E 1 kV/cm
20 m drift
Cathode (- 2 MV)
p 3 atm
RD very challenging and very difficult to put a
magnetic field around it.
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9. Far Detector Designs
Emulsion detectors

• High precision tracking (dxlt1mm, dqlt1mrad) kink
  decay for nt identification a la OPERA
• Emulsion walls in between iron-scintillator
  magnetic detectors for tau ID?

1 brick 10.2x12.7x7.5 cm 57 Em. Plates 2CS 56
Pb (1 mm)
spectrometer
target
shower absorber
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10. Near Detector at a Neutrino Factory

• To achieve physics goals of neutrino factory,
  need to establish near detector for near/far
  ratio.
• Long baseline neutrino oscillation systematics
• Flux control and measurement for the long
  baseline search.
• Neutrino beam angle and divergence
• Beam energy and spread
• Control of muon polarization
• Measurement of charm backgrounds
• Near detector neutrino physics
• Cross-section measurements DIS, QES, RES
  scattering
• sin2?W - ?sin2?W 0.0001
• Parton Distribution Functions, nuclear shadowing
• ?S from xF3 - ??S0.003 _
• Charm production Vcd and Vcs, D0/ D0 mixing
• Polarised structure functions
• L polarization
• Beyond SM searches

General Purpose Detector(s)!!
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10. Near Detector at a Neutrino Factory

• Near detector(s) are some distance (d30-1000 m)
• from the end of straight section of the muon
  storage ring.
• Muons decay at different points of straight
  section near detector is sampling a different
  distribution of neutrinos to what is being seen
  by the far detector

• Different far detector baselines
• 730-7500 km, 20 m detector q30-3 mrad

If decay straight is L100m and d 30 m, at 8
mrad, lateral displacement of neutrinos is
0.25-1.0mm to subtend same angle.
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10. Near Detector Aims

• Neutrino beams from decay of muons

Polarisation dependence
Need to measure polarization!!
Spectra at d30 m
Pm1 gone!
E.g. With 50 kg ?109 n interactions/yr
Number CC interactions
Need high granularity
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10. Near Detector Measurements
Charm production

• Charm mesons produced
• Charm is background for oscillation signal
• Measure of Vcd and strange quark content nucleon
• Measure charm vs pt (background to oscillations)
• 6-7 of cross-section at 20 GeV?3 CC events
• about 30 million charm states per year

McFarland

• mixing doubly Cabbibo
  suppressed?SM very small, new physics

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10. Near Detector Measurements
Other physics

• Measurement cross-sections
• Measurement flux
• Other physics
• Structure functions
• ?S from xF3 - ??S0.003
• QCD sum rules
• sin2?W
• L polarization spin transfer from quarks to L

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11. NOMAD-STAR near detector prototype

• High granularity in inner region that subtends to
  far detector.
• Very good spatial resolution charm detection
• Low Z, large Xo
• Electron ID
• Does the detector have to be of same/similar
  technology as far detector?

NOMAD-STAR (Silicon TARget)

• Possibilities
• silicon vertex detector in a magnet with
  calorimetry, electron and muon ID
• (eg. NOMAD-STAR??)
• Liquid argon calorimeter problems with rate

• Does not need to be very big (eg. R50-100 cm)

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11. NOMAD-STAR

• RD in NOMAD for short baseline nt detector based
  on silicon
• NOMAD-STAR (NIMA 413 (1998), 17 NIMA 419
  (1998), 1 NIMA 486 (2002), 639 NIMA 506 (2003),
  217.)

• Total mass 45 kg of B4C target (largest density
  for lowest X0)

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11. NOMAD-STAR

• Aim of NOMAD-STAR reconstruct short lived
  particles in a neutrino beam to determine
  capabilities nt detection use impact parameter
  signature of charm decays to mimic nt

• t impact parameter 62 mm, normal nm charged
  current (CC) interactions 30 mm
• t signal very similar to charm signal

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11. NOMAD-STAR

• Longest silicon microstrip detector ladders ever
  built 72cm, 12 detectors, S/N161
• Detectors Hamamatsu FOXFET p on n, 33.5x59.9
  mm2, 300 mm thick, 25 mm pitch, 50 mm readout
• VA1 readout 3 ms shaping

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11. NOMAD-STAR

• nm CC event

• Secondary vertex

• Primary vertex

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11. NOMAD-STAR

• Increase noise in some ladders affected some
  efficiencies compensated by clustering algorithm
  with cuts as function of ladder

• Noise
• (e-)

• 2500

1500
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11. NOMAD-STAR

• Vertex resolution sy 19 mm

• Impact parameter resolution 33 mm

• sx33 mm

• Pull
• s1.02

• Double vertex resolution 18 mm from Ks
  reconstruction

• sz280 mm

• sx18 mm

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11. NOMAD-STAR

• Charm event selection

• Efficiency very low 3.5 for D0, D and 12.7
  for Ds detection because fiducial volume very
  small (72cmx36cmx15cm), only 5 layers and only
  one projection.
• From 109 CC events/yr, about 3.1x106 charm
  events, but efficiencies can be improved.

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12. Near Detector Ideas

• Passive target can provide target mass, but
  affects vertex and tracking reconstruction
  efficiency due to scatters
• Improve efficiency by having 2D space point
  measurement and more silicon planes.
• For example 52 kg mass can be provided by 18
  layers of Si 500 mm thick, 50 x 50 cm2 (ie. 4.5
  m2 Si) and 15 layers of B4C, 5 mm thick
• Optimal design fully pixelated detector (could
  benefit from Linear Collider developments in
  MAPS, DEPFET or Column Parallel CCD). With pixel
  size 50 mm x 400 mm ? 200 M pixels, 0.4 X0
• Could also use 3D detectors or double sided
  silicon strips (with long ladders of 50 cm x 50
  mm ? 360 k pixels).
• International Scoping Study (ISS) for a neutrino
  factory (July 2005 to August 2006) aim to define
  the scope of physics parameters, neutrino factory
  machine technology and detector technology needed
  to launch a full design study 2007-2010. Near and
  far detector technologies are being considered.
• Opportunity for another application of DEPFET
  detectors

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Conclusions

• The present series of neutrino experiments
  measure solar and atmospheric neutrino parameters
  
• The next series of experiments (off-axis) will
  aim to measure q13 and will provide a first
  attempt at measuring leptonic CP violation
• The neutrino factory is the ultimate tool for the
  study of neutrino properties.
• The Neutrino Factory International Scoping Study
  is defining the physics programme and is
  performing a first attempt at optimising the
  parameters for the machine in conjunction with
  the detectors.
• An intense RD programme is being carried out in
  the key technologies needed for a neutrino
  factory.
• There exists a baseline far detector consisting
  of a segmented magnetic detector to measure the
  wrong-sign muon signal.
• A near detector needs to measure the charm
  background for the far detector, and it should
  include a silicon vertex detector to identify
  charm candidates.
• Neutrino factories offer a varied and exciting
  physics programme. We should aim to build one
  before the end of the next decade.