Neutrino Factory

1
The UKNeutrino FactoryProject

• Neutrino oscillations
• A neutrino created as one type or flavour
  changes into another type as it travels
• Implications for particle physics
• Neutrinos are massive and mix Standard Model is
  incomplete
• Neutrinos may violate matter-antimatter symmetry
• Impact on astrophysics and cosmology
• Origin of matter-dominated universe
• Contribution to dark matter known to exist in
  universe

• Sensitivity
• Key parameters
• Degree of matter-antimatter symmetry violation ?
  ?
• Degree of mixing e- and ?-neutrinos ? ?13
• Neutrino Factory has highest sensitivity
  

UK Neutrino Factory collaboration D. Rodger,
H.C. Lai, F. RobinsonApplied Electromagnetics
Research Group, Electronic and Electrical
Engineering Department, University of Bath,
Claverton Down, Bath, Avon BA2 7AY,
UK N.K. Bourne, A. Milne?Cranfield University,
Royal Military College of Science, Shrivenham.
Swindon, SN6 8LA, UK M.W. PooleAccelerator
Science and Technology Centre, Daresbury
Laboratory, Daresbury, Warrington, Cheshire, WA4
4AD, UK D. Wilcox?High Power RF Faraday
Partnership, c/o Rutherford Appleton Laboratory,
Chilton, Didcot, Oxfordshire, OX11 0QX,
UK A.T. Doyle, F. J. P. SolerDepartment of
Physics and Astronomy, Kelvin Building, The
University of Glasgow, Glasgow, G12 8QQ,
UK P. Cooke, J. B. Dainton, J. R. Fry, R. Gamet,
Ch. TouramanisDepartment of Physics, University
of Liverpool, Oxford St, Liverpool L69 7ZE,
UK G. Barber, P. Dornan, M. Ellis, K. Long, D.R.
Price, J. Sedgbeer, A. TapperImperial College
London, Prince Consort Road, London SW7 2BW,
UK G.D. Barr, J.H. Cobb, S. Cooper, G. Wilkinson,
Subdepartment of Particle Physics, University of
Oxford, Denys Wilkinson Building, Keble Road,
Oxford OX1 3RH, UK H. JonesSubdepartment of
Condensed Matter Physics, University of Oxford,
Department of Physics, Clarendon Laboratory,
Parks Road, Oxford OX1 3PU, UK G. Bellodi,
J.R.J. Bennett, S. Brooks, M.A. Clarke-Gayther,
C. Densham, P.V. Drumm, R. Edgecock,
D.J.S. Findlay, F. Gerigk, A.P. Letchford,
P.R. Norton, C.R. Prior, G. Rees,
J.W.G. Thomason, J.V. TrotmanCCLRC Rutherford
Appleton Laboratory, Chilton, Didcot,
Oxfordshire, OX11 0QX, UK P.F. HarrisonDepartment
of Physics, Queen Mary University of London,
Mile End Road, London, E1 4NS C. N. Booth,
E. Daw, P. HodgsonDepartment of Physics and
Astronomy, University of Sheffield, Sheffield S3
7RH, UK ? and Fluid Gravity Engineering, 83
Market St., St. Andrews, Fife ? and e2v
technologies, 106 Waterhouse Lane, Chelmsford,
Essex CM1 2QU, UK
R109
Near Detector
Schematic of the UK Neutrino Factory Design The
UK is playing a significant role in the
international design effort towards a neutrino
factory.
RFQ (Radio Frequency Quadrupole)
LEBT (Low Energy Beam Transport)
H- Ion Source
Beam Chopper
FFAG II (8-20GeV)
So far, four key areas have been identified in
which RD is particularly important these are
highlighted on this diagram and detailed
elsewhere in
FFAG III (20-50GeV)
180MeV DTL (Drift Tube Linac)
the presentation. Most of the technology
demonstrations will be constructed within the
next five years.
Achromat for removing beam halo
Muon Decay Ring (muons decay to neutrinos)
To Far Detector 1
Proton Driver Front-End Test Stand at RAL Any
accelerator complex must start with a particle
source (in this case H- ions) and a sequence of
components that are either tailored
for low-energy beam trans- port and
acceleration (LEBT, RFQ), or perform functions
that are most effectively done at low energy (the
chopper). The specification of a proton driver
for a neutrino factory demands that
these components push the envelope of high beam
current with very low uncontrolled losses. RAL
has an active ion source research programme and a
chopper development project running in parallel
with CERN.
FFAG Electron Model at Daresbury An
unconventional kind of accelerator called a
non-scaling FFAG is being devised to accelerate
the muons rapidly enough before they decay. To
verify this technology, a scaled model using
electrons instead of muons is being designed for
operation at Daresbury Laboratory, where
synergies with existing electron machines can
make it particularly cost-effective.
FFAG I (2-8GeV)

• Two Stacked Proton Synchrotrons (full energy)
• 6GeV
• 78m mean radius
• Each operating at 25Hz, alternating for 50Hz
  total

To Far Detector 2
Target enclosed in 20Tesla superconducting
solenoid (produces pions from protons)
Proton Beam Dump
Solenoidal Decay Channel (in which pions decay to
muons)
Stripping Foil (H- to H/protons)

• Two Stacked Proton Synchrotrons (boosters)
• 1.2GeV
• 39m mean radius
• Both operating at 50Hz

RF Phase Rotation
Muon Linac to 2GeV (uses solenoids)
UK Neutrino Factory collaboration
Muon Ionisation Cooling Experiment (MICE) The
muon beam must be cooled, or reduced in size,
to fit inside the accelerators downstream. MICE
uses a muon beam from an intermediate target of
the ISIS accelerator at RAL to prove the
practicality of a technique called ionisation
cooling, which is unique to muons. The
international MICE collaboration are showing two
posters here.
Muon Cooling Ring
UK Targetry RD Programme The target must survive
an extreme degree of heating dissipating 1MW of
heat at temperatures reaching over 2000C, while
having to withstand physical shocks caused by 50
proton pulses per second. RAL is working with
the RMCS at Cranfield University to investigate
these phenomena.

• Proton bunches compressed to 1ns duration at
  extraction
• Mean power 5MW

More about the front-end test stand, which will
be an integrated demonstration of all these
low-energy technologies, can be found below.

• Pulsed power 16TW

Target Studies
CCLRC - Imperial - Warwick Front End Test Stand
Parameters of the NF Target Proton Beam
pulsed 10-50 Hz pulse length 1-2 ms energy
2-30 GeV average power 4 MW Target (not a
stopping target) mean power
dissipation 1 MW energy dissipated/pulse 20 kJ
(50 Hz) energy density 0.3 kJ/cm3
The target operates at very high mean power
dissipation and extremely high energy density.
This high power density creates severe problems
in dissipating the heat and the short pulses
produce thermal shocks due to the rapid expansion
of the target material. These shocks can
potentially exceed the mechanical strength of
solid materials. In addition the pions and muons
created in the target must be collected in a 20
Tesla solenoidal field or a magnetic horn. This
imposes strong restraints on the target and
collector system which must ultimately be
designed as a single entity.
What? An experimental facility to test the
all-important early stages of high power
proton accelerators (HPPAs). High power proton
accelerators are the bases of spallation neutron
sources, transmutation machines, and neutrino
factories. Why? Because high power proton
accelerators must produce high quality megawatt
beams with beam losses of less than 0.0001 per
metre, and such high quality beams have yet to
be demonstrated. Where? At Rutherford Appleton
Laboratory in Oxfordshire. When? Design already
under way. Construction starts 2005. The test
stand will consist of an H ion source producing
60 mA, 2 ms pulses at 50 pps, a LEBT running at
75 keV to match the beam from the ion source into
the RFQ, an RFQ accelerator driven by a 12 MW,
234 MHz RF driver to increase the beam energy to
2.5 MeV, a beam chopper switching between beam
bunches in 2 ns, and a comprehensive suite of
diagnostics to measure beam currents, emittances,
energy distributions and bunch structures. The
design of the test stand involves much
sophisticated physics design, and the
construction involves challenging electrical,
electronic, mechanical, RF and vacuum
engineering, together with the procurement of
much high-tech apparatus.
beam
2 cm
20 cm
Several targets which potentially can withstand
the huge power density are currently being
considered worldwide a. Mercury (or a liquid
metal) jets b. Contained flowing mercury (or a
liquid metal) c. Solid target - tantalum rotating
toroid, thermally radiating at 2300 K d.
Granular solid target
The UK is currently investigating solid targets.
The solid target is simple in concept, but may be
susceptible to shock damage. There are many
examples of solids bombarded by proton beams at
similar power densities and even targets
operating at an order of magnitude higher power
density have been shown to survive many pulses.
Shock studies are the main thrust of the UK
activity. A toroid or band, rotating in vacuum
and thermally radiating its power to water-cooled
vacuum chamber walls could provide a simple,
clean and reliable high power target. It would
not require beam windows between the incoming
proton beam and the outgoing pion beam. It is
proposed to consider electromagnetic levitation
and guidance of the toroid and rotation by linear
motors, so that there are no moving parts (except
for the toroid) in the vacuum and no physical
contact with the toroid.
rotating toroid
toroid magnetically levitated and driven by
linear motors
solenoid magnet
toroid at 2300 K radiates heat to water-cooled
surroundings
proton beam
Schematic diagram of the radiation cooled
rotating toroidal target