High performance computers are used, amongst other things, by the MET Office for simulating potential climate change scenarios and are also used in the UK for analysing and predicting complex weather patterns. This investment comes from the Department of Trade and Industry's Large Facilities Capital Fund, established to ensure UK scientists have access to leading edge, large-scale experimental projects and facilities. The Engineering and Physical Sciences Research Council (EPSRC), which the DTI funds, will be managing the project on behalf of Research Councils UK and are making a significant contribution towards the cost of the service. The Natural Environment Research Council (NERC) and the Biotechnology and Biological Sciences Research Council (BBSRC) are also contributing financially to the project emphasising the breadth of science that will be supported. Lord Sainsbury said: "HECToR will be an indispensable tool for scientists across the entire breadth of the UK research base. The computational limits of the existing facilities are now being reached as new and increasingly complex research programmes place increasing demands on the computing power available. It is imperative that our scientists are able to access the best possible computer facilities to build on, and support, the work they do in the laboratory." The Engineering and Physical Sciences Research Council (EPSRC) is the managing agent on behalf of all Research Councils (RCs) for the procurement of a new high-end computing facility for use by UK academic users. This service, called HECToR, is due to start in 2007 and is expected to have an initial capability equivalent to 50-100 peak TFlop. Maintaining access to leading edge experimental facilities is a key element of keeping UK scientists at the forefront, and competitive, in their fields of research. In many cases the responsibility for the investment needed to maintain this access should properly fall to the universities and institutes in which the scientists are employed. For larger investments, the Research Councils have the responsibility for investments, with additional support provided by OST's Large Facilities Capital Fund. The science case for HECToR identified that the science and engineering fields that will benefit from further investment in high end computing span the entire breadth of the UK research base and all scales from elementary particles to the universe at large, and include the following 16 fields: atomic, molecular and optical physics; computational chemistry; materials simulations; nanoscience; computational engineering; biomolecular sciences; health sciences and bioimaging; radiation biology; particle physics; environmental modelling; earth sciences; cosmology; astrophysics; solar system science; plasma physics; disaster simulation and emergency response. Some of these fields already have world-class research programmes that are dependent upon access to high performance computing services at the national level, others are becoming increasingly dependent (e.g., biomolecular sciences), and yet others are just starting to explore the opportunities (e.g., radiation biology, disaster simulation and emergency response). The availability of a high performance computing capability brings additional value to the research projects carried out at the large facilities, e.g., synchrotron, neutron and laser sources. The data from these, e.g., diffraction patterns and energy spectra, provide validation for the simulations carried out using high performance computing. This gives confidence in the theoretical principles used to describe the systems under study, which can then be developed to describe whole systems.