Memorandum submitted by the Particle Physics
and Astronomy Research Council (PPARC)
LARGE ACCELERATOR-BASED PHYSICS FACILITIES
This memorandum focuses on the provision for
the UK research community of access to large-scale accelerator-based
physics facilities. These facilities are essential tools for cutting-edge
research across the science base.
The scale of investment requires a long-term
strategy and decision-making framework within which timely decisions
can be made about:
the circumstances under which the
UK might justify having its own national facility; and
how the UK can best position itself
to negotiate participation in the construction and operation of
international collaborative facilities, and the possible hosting
of one or more of these facilities.
The scale and longevity (typically 10-15 years
from conception, R&D, technical design, construction to operation)
of the investment required makes it extremely difficult for any
single Research Council to absorb the cost within their baseline
funding. Facilities are also becoming increasingly multi-disciplinary
in their application. Hence the need to develop a national investment
strategy within the OST/Research Councils system.
Over the next 2-5 years decisions will be made
on the funding and construction of several international large
These facilities will come into operation in
the next 15 years. Some will be based on global collaborations.
Some will be European, American or Japanese. They will include
electron linear colliders, re-circulating linear colliders for
synchrotron radiation studies and free electron lasers operating
across a spectrum of wavelengths. High power proton accelerators
will be developed as drivers for pulsed neutron spallation sources,
muon derived neutrino beams, and muon colliders, and will have
the potential to transmute and even derive energy from nuclear
The main purpose of the proposed linear accelerators
will be to produce very high energy electron-positron colliders,
which will be used by particle physicists for precision follow-up
to the Large Hadron Collider now being constructed at CERN.
Some countries have already positioned themselves.
Germany published in March 2001 a design for a very high energy
electron-positron linear collider (TESLA) for particle physics
follow-up to the LHC at CERN. This design lead stemmed from a
decision several years ago at DESY to invest in the R&D at
a level of £20-30 million.
The need for such a global machine has now been
acknowledged as the highest priority for the global particle physics
community in recent US and European reports.
The UK particle physics community has identified
participation in a linear collider as its highest priority post-LHC.
Alternative designs, albeit less advanced than
the German design, are being developed in the US, Japan, and CERN.
The UK has considerable design expertise in CCLRC and universities
and has contributed both to the German TESLA design study and
R&D at CERN.
A linear collider will cost around $5,000 million,
of which the UK share might be around 10 per cent or £300
million over the period 2003-12. The debate in the next year or
so will be about where the machine should be built, and who will
be the lead participants in its design and construction.
To position itself the UK needs to increase
its investment now in R&D rising to about £5 million
per annum, and decide in the next year or so if it wants to participate
and on its negotiating position on the siting of the machine.
These high energy electron linear accelerators
are the basis of X-ray Free Electron Lasers which have the potential
to produce synchrotron radiation beams of exceptional brilliance,
opening new areas of investigation in the life sciences, material
sciences and chemistry.
The US and Germany are already positioning themselves
to build FELs. In Germany, a test facility has been constructed
associated with TESLA.
High intensity proton machines will be required
for many uses. The overall situation is reviewed in a report from
an OECD Global Science Forum Workshop held in September 2000.
The introduction to this report says: "During the next 10-15
years, a number of OECD countries will need to make decisions
about significant investments in one or more of the following
areas of basic and applied research:
Neutron spallation sources for research
in the physical, chemical, and life sciences, for materials irradiation,
and for isotope production.
Radioactive beam facilities for fundamental
nuclear physics research.
Accelerator-driven sub-critical devices
for transmutation of nuclear wastes.
Particle physics facilities that
use muons for colliding-beam experiments, or for producing beams
Decisions in the above areas will involve distinct
needs, constituencies, costs and timescales. The successful implementation
of any of the facilities will depend on the ability of scientists
and engineers to design and operate High Power Proton Accelerators
(HPPA) with beam energies in the Giga electron-volts (GeV) region,
and power levels ranging from 1-5 megawatts (pulsed) for some
applications to 50 megawatts (continuous) for others. In several
critical areas, the needed levels of performance greatly exceed
the state of current knowledge and technological capability (eg,
ion sources, microwave accelerating structures, beam transport,
high-power targets, control systems)."
HPPA are potentially of great interest to the
(nuclear) energy industry, because they could be used to transform
radioactive nuclear waste into shorter lived isotopes, and could
even become net energy producers by extracting energy from the
waste. The main driver for proton machines, however, is to produce
neutrons for material science and other condensed matter research,
and as producers of neutrinos and muons for particle physics research.
The detailed characteristics of the machines required for these
various applications are somewhat different, but the underlying
physics and technology is the same and all could spring from a
common R&D programme.
The UK would be a credible host for any of these
machines. By making a determined start now, there could be a major
international facility in the $B range on UK soil, with all the
scientific, technical, industrial and social benefits that accrue
to the host country.
The UK starts from a very strong base. It is
widely accepted that future developments in neutron sources will
be based on the technologies developed at ISIS. A proposed Second
Target Station for ISIS will offer unique instrumentation, specifically
optimised for studies of advanced materials, large scale structures,
surfaces and interfaces as well as systems of biological interest.
For the longer term the options for the UK and
Europe are the proposed 5MW European Spallation Source (ESS) or
the evolutionary development of the accelerator complex at ISIS
which could go beyond the present power levels in steps to 5MW.
The timescales for ESS are such that the ISIS Second Target Station
will be needed regardless of which of the two options is ultimately
chosen and the associated technical developments will provide
an important platform for establishing a third generation source.
Given the excellent reputation established by
ISIS at CCLRC, and given the fact that most of these new facilities
require high intensity proton beams, it would be logical for the
UK to look towards a proton rather than an electron based machine.
If this is to be a serious goal, strong support
is required at the highest political level and preparatory work
must start now in universities, institutes, industry and with
overseas collaborators. A vigorous R&D programme over the
next few years, growing to around £10 million per annum,
will be required.
The initial R&D programme aimed at the development
of advanced neutron sources, the UK strength, is common to developments
of high power proton accelerator systems for a neutrino factory,
the development of muon beams and transmission of nuclear waste.
For these machines to be scientifically at the
forefront, both accelerator and target technologies will need
to be pushed to their limits. To be able to contribute to a capital
programme for a future accelerator-based facility in kind requires
that the UK be involved in accelerator R&D some five years
in advance. The table below indicates the resources required from
SR2002 for accelerator R&D activities.
|Electron Linear Collider R&D||1|
|High Power Proton Accelerator R&D||3|
Over a 20-year span, the likely requirements for a Linear
|Linear ColliderUK Contribution||
It is in the UK's strategic interest to plan to host one
of the following proton-based machines:
ESS or Megawatt ISIS or Neutrino factory
and to deliver contributions in kind to the other projects
of interest wherever they are built.
|ESSUK Contribution (14%)|
|UK Site Premium||20|
|1 MW ISIS (UK 20%)||
|5 MW ISIS (UK 20%)||
Neutrino Beam (at
|Muon Based Neutrino Factory||
|UK Host Premium||
||Beyond 2020 ||
17 December 2001