Select Committee on Science and Technology Minutes of Evidence


Memorandum submitted by the Particle Physics and Astronomy Research Council (PPARC)

LARGE ACCELERATOR-BASED PHYSICS FACILITIES

INTRODUCTION

  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 science need;

    —  relative priorities;

    —  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 accelerator-based facilities.

  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 waste.

ELECTRON LINEAR ACCELERATORS

  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.

FREE ELECTRON LASERS (FELS)

  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 POWER PROTON ACCELERATORS (HPPAS)

  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 of neutrinos.

  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.

Resources

  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.
£m2003
2004
2005
2006
2007
2008
2009
Electron Linear Collider R&D1
2
3
5
5
5
5
High Power Proton Accelerator R&D3
5
7
10
10
10
10



  Over a 20-year span, the likely requirements for a Linear Collider are:
£m2005
2006
2007
2008
2009
2010-2014
2015-2019
Total UK
Total
Linear Collider—UK Contribution
20

25

30

50

175

300

3,500



  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.
£m2005
2006
2007
2008
2009
2010-2014
2015-2019
Total UK
Total
ESS—UK Contribution (14%)
25

25

25

25

25

50

{

235

1,250
—UK Site Premium20
20
20
{
or
1 MW ISIS (UK 20%) 12
12
12
24
60
300
5 MW ISIS (UK 20%) 45
45
90
450
Super Conventional
Neutrino Beam (at
CERN)

10

10

10

30

300
Muon Based Neutrino Factory
20

20

130

30

200

2,000
—UK Host Premium 300
300
Muon Collider Beyond 2020
Transmutation Demonstrator
Beyond 2020


17 December 2001




 
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Prepared 7 February 2002