Linear Collider ILC and CLIC
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The mission of the Laser-Based Beam Diagnostics (LBBD) Collaboration is to
study the feasibility of laser-based diagnostics tools for the
International Linear electron positron Collider (ILC). The objectives
of the laser-wire project are to develop laser-based techniques for
determining the dimensions of electron (positron) bunches at the ILC
and optimising their application using simulations.
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LiCAS is short for Linear Collider Alignment and Survey. The
project aims to develop a survey system that can be used to align
accelerator components during the build stage of the International
Linear electron positron Collider to O(200 microns) over distances of
O(600)m. Refraction prevents using optical methods in open air to align
the components to the required accuracy. Instead, the plan is to do the
survey in 25m overlapping lengths. Our system will therefore take the
form of a 25m long survey train which will travel the 30km length of
the tunnel establishing a coordinate system of reference marks against
which the collider components will be surveyed. The train's internal
co-ordinate measurement system operates in vacuum. It uses FSI
(Frequency Scanning Interferometry) and LSM (Laser Straightness
Monitors) to measure absolute co-ordinates. The group closely
collaborates with the DESY metrology group and a first prototype will
be tested at DESY soon.
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The MONALISA project is developing accurate systems for
monitoring and stabilisation of key components in and around
accelerators. Current work is focused on a demonstration system in
Oxford and a test installation at ATF2.
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Simulations of the Linear Collider Beam Delivery System.
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The F.O.N.T. (Feedback On Nano-second Timescales) project was
set up to research, design and test an intra-train beam-based feedback
system to achieve and maintain beam collisions, and therefore high
luminosity, at a future electron-positron Linear Collider. It is one of
the projects of the LC-ABD group which is part of the LCUK
collaboration. We also participate through the TESLA Accelerator
Physics and Design group.
Neutrino factory:
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Neutrino Sources based on Muon storage rings have
found a lot of interest in the High Energy Physics community. The
strong point is the capability of providing very intense, very well
collimated neutrino beams. In such facility, an intense proton beam
hits a target, pions decay into muons in long decay channels, the muons
have to be cooled and then accelerated and finally get injected into a
storage ring where they decay. A recent Neutrino Factory interest is to
explore whether FFAGs could be used to provide a more economical
Neutrino Factory than one which uses cooling.
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International Muon Ionization Cooling Experiment Future
neutrino factories or muon colliders will require that intense muon
beams are accelerated and stored. Many tricks are required to do this
efficiently. The muons originate from the decay of pions and the beam
has a very high initial emittance (rms size times rms divergence). The
emittance must be reduced substantially to match the acceptance of
downstream accelerators. The muon lifetime is finite and conventional
cooling methods cannot be used: ionisation cooling is the only
possibility. In an ionisation cooling channel the muons are focussed by
solenoidal magnetic fields onto a series of low Z 'absorbers' where
ionisation loss reduces both transverse and longitudinal momentum; RF
cavities subsequently restore the longitudinal momentum thereby
reducing the net emittance of the beam. MICE is a UK/US/Japan/European
collaboration to build a section of muon cooling channel and
demonstrate ionisation cooling. MICE will consist of one lattice cell
of the US Neutrino Factory Feasibility Study 2 cooling channel design
and will make single-particle measurements of emittance reduction with
a precision of one part in a thousand. The experiment will take place
at the Rutherford Appleton Laboratory in a new muon beam from the 800
MeV ISIS proton accelerator. The John Adams Institute, in collaboration
with RAL, will provide the Absorber Focus Coil (AFC) modules for MICE.
These modules contain pairs of high-field superconducting coils
surrounding liquid hydrogen absorbers. The group is also working on the
design of thin windows for the absorbers and RF cavities, the beam
optics of the cooling channel, emittance measurements, and calculations
of energy loss and multiple scattering in liquid hydrogen (ELMS).
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The non-scaling fixed-field alternating gradient accelerator - or
NS-FFAG - offers the prospect of smaller, simpler, cheaper accelerators
operating with a high frequency and a high duty cycle. The project will
build a 20 MeV electron accelerator, EMMA to test the principle and
design a proton accelerator for medical applications, PAMELA, while
investigating other possible applications, from archaeology to zoology.
Here in the JAI, our main focus is on the medical application PAMELA –
the Particle Accelerator for MEdicaL Applications – where the aim is to
develop the design of a cancer treatment facility using protons and
light ions such as Carbon to treat certain types of cancer that are
otherwise difficult to treat.
Other projects:
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We are investigating how accelerator diagnostics can be applied to the beam
created by laser-driven plasma wakefield accelerators.
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The FACETS project aims to support researchers at the
University of Oxford interested in using external scientific facilities
such as the Diamond synchrotron. The website is under development but
will provide information on the science that can be done, guidance on
identifying the best instrument for your work and opportunities to find
potential collaborators at Oxford or at the facilities themselves.
- Other new ideas We are also looking at a range of other projects,
from
laser-plasma accelerators
, the development of femtosecond x-ray
pulses (in association with the
Diamond Light Source
) and a new Proton
Synchrotron at
CERN.
Past activities:
Longitudinal profile diagnostics using Smith-Purcell radiation
The objective of this research is the development of a method for the
determination of the longitudinal (temporal) profile of short, intense
and highly relativistic bunches of electrons. In principle, information
about the longitudinal charge distribution inside the bunch can be
obtained from any radiative process, whereby the beam is made to
radiate a very small amount of energy. The wavelength distribution of
this radiation can then be measured and used in order to infer the
charge distribution inside the bunch. This is only possible if the
radiation is coherent, i.e. if its wavelength is comparable to or
longer than the bunch length. The first Smith-Purcell experiment in the
multi-GeV regime [1] was recently carried out at SLAC (28.5GeV). The
results from this experiment were very encouraging, and the bunch
lengths measured were in line with alternative measurements (LOLA). 1.
G. Doucas et al., EPAC2008.-
ELMS is a study into the accurate simulation of the passage of
Muons through matter, specifically Liquid Hydrogen, in order to
investigate the feasibility of Muon Cooling. We showed that energy loss
and scattering corellation present in the full cross section, but not
considered by alternative treatments, might be significant. Seminar
2004 (PowerPoint) given in Oxford, 20th January 2004.
