Most of the visible mass of the universe is in the form of protons and neutrons that make up the everday nuclei found within the elements we see around us. This might suggest that protons and neutrons are the fundamental building blocks of matter, but, in fact, protons and neutrons are themselves composed of more fundamental particles known as quarks. Quarks are strongly attracted to each other and are never seen in isolation. They owe their attraction to gluons, which are force particles that stick quarks together. What makes this attraction different from other types of forces is that the gluons attract each other too. It is this interaction amongst the force particles that makes the nuclear force so strong. It also has a rather surprising effect: the strength of the interaction decreases with distance. This suggests that at high enough densities quarks and gluons behave as if they are free particles. In this case protons and neutrons would not exist at all. Instead matter would be comprised of a plasma of quarks and gluons. This would have been what matter was like during the first fraction of a second after the Big Bang. Attempts are now underway to recreate the conditions of the Big Bang in the laboratory, albeit on a much smaller scale, by colliding heavy nuclei at very high energies. In a head-on collision between two nuclei a significant amount of kinetic energy is converted into new particles, producing matter which is both extremely dense and extremely hot. What is needed is an experimental probe that can tell us exactly how dense and how hot it really is. One way to do this is to study jets. Jets occur when quarks and gluons collide head-on and are scattered sideways. As free quarks and gluons are not observed, they shower into a jet of hadrons. This is a rare process, but sufficient numbers are produced to make them a powerful diagnostic tool. The key to their usefulness lies in the fact that they can be absorbed in the hot dense medium that is the quark-gluon plasma, making them an ideal tool for studying the properties of this new state of matter. This proposal seeks to unite two experimental groups at Birmingham University to study jets, amongst other observables, in heavy-ion collisions at the Large Hadron Collider (LHC), which is situtated at the European Centre for Nuclear Research (CERN) in Switzerland. The LHC will start colliding protons in late 2007 and the first heavy-ion beams are expected at the end of 2008. Compared to previous studies at the Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC), near New York, the LHC will achieve collision energies 30 times higher than seen before. It is expected that the initial temperature will be 4-5 times higher than the critical temperature required to observe a transition to quark deconfined matter. One of the groups at Birmingham is already heavily involved in preparations for the first collisions to be seen in the ALICE experiment. The other group has been involved in an experiment called STAR at the RHIC facility and bring with them experience of data analysis using a similar detector system. Together, it is hoped that the two groups will make a major impact on an international quest to discover what matter was like a fraction of a second after the Big Bang.

Most people have heard of liquid crystals - they are the materials that are used in the flat-panel displays found in lap top computers, mobile phones and some of the most modern television sets. The technology is so successful that last year a liquid crystal display (LCD) was sold for every person on earth. There is always a push for faster, better display devices. These might use lower power, so are more environmentally friendly, or become more complex and faster, perhaps making them useful as specialist optoelectronic devices - things that improve telecommunications and computing. Liquid crystals aren't just high-tech materials though. They are fluids that have both function and order, and are a key component of many biological systems. For example liquid crystals help spider silk to have its amazing strength and flexibility, they cause the beautiful colours in some insects and even play a part in your brain which should be 70% liquid crystalline!The research in this proposal involves new liquid crystal materials at the forefront of technology. The materials we wish to study are being considered for use in a number of new applications where their optical properties or their sensitivity to surfaces might be useful. We can carry out a range of new experiments, including scattering x-rays of very precise energy (Resonant scattering) and measuring tiny changes in light scattered by the liquid crystal (Raman scattering), that will allow us to probe the exact kind of order that is important in our liquid crystal systems. We also want to build an experiment that will allow us to squeeze the liquid crystals to see how compressible they are. We believe that by carrying out this range of experiments and carefully combining all the information we gain, we can test theory and help theoreticians to understand how this important state of matter forms. We have new materials that will allow us to do some of the experiments we are proposing for the first time. Also, the unique combination of experiments that we are proposing will allow us to build a complete picture of whether the layers that we know form in this kind of liquid crystal are important in the process of forming the different types of liquid crystal structure. Understanding how this special kind of liquid crystal orders in the way it does has implications beyond technology. In studying physics or materials science, we try to understand why certain materials act in the way they do so that we can better use their properties, or so that chemists can improve them. Liquid crystals are an example of a fluid state of matter in which the molecules 'self-assemble' and the way in which they do depends very subtly on small changes in molecular structure or composition. How this happens is still not very well understood, despite this topic becoming increasingly important in areas like nanotechnology where materials with function are assembled into tiny structures that then act at a lager scale. Self-assembly is also a vital process in nature where, for example, the fluids we are composed of assemble in such a way that very high-level functions can take place. An important aspect of the research we plan is that we hope to understand how small changes in molecular structures in our systems lead to very large differences in their bulk physical properties. Such research has very broad relevance as it can potentially help us to understand how nature works. This final point isn't just speculative either / we recently used our understanding of liquid crystal optics to suggest how some fish see polarised light (without using Polaroid sunglasses!). There is no question that understanding self-assembly of fluids is important in many areas of science.

We shall investigate in collaboration with BNL electron and phonon relaxation processes in strongly correlated electron systems such as cuprate high-temperature superconductors. The dynamics of photoexcited electrons and photoinduced lattice expansions, measured by ultrafast (femtosecond) time-resolved spectroscopy at BNL, will be analysed in the framework of our theory of hot electron relaxation in metallic compounds. Using the exact analytical solutions of the kinetic equations and experimental relaxation times, we are aiming to resolve a controversial issue concerning whether the electron-phonon interaction is crucial, or else weak and inessential in novel superconductors.

Magnetic materials are ubiquitous in modern society, present in advanced devices, sensors and motors of every kind. As the magnetic force loses strength only over very long distances, it allows for communication between components that are physically well-separated. This unique property permits the conversion of electrical to mechanical energy, assists microwave devices in telecommunications, transmission and distribution of electric power, enables data storage systems and facilitates sensing of ambient conditions. Steady effort has been extended since the invention of the magnetic compass (first reported in the Qin Dynasty, 221 BC) to tailor and optimize magnetic materials' performance. Two thousand years later it is clear that breakthrough advances in the performance of magnetic devices will require new materials and novel design principles to control magnetic performance. In this project we will clarify the origins of a significant but poorly-understood phenomenon of extrinsic control of a classically intrinsic parameter - the magnetic transition temperature - in layered systems comprised of magnetic materials with strong electron-lattice coupling. This will be done by a joint transatlantic programme of research between the University of Leeds and STFC Rutherford Appleton Laboratory in the UK, and Northeastern University in the USA. Brookhaven National Laboratory will participate as a project partner. We shall use FeRh, which crystallizes in the CsCl phase, as a model system: this material undergoes a phase transition from antiferromagnetic (AF) to ferromagnetic (F) on warming through a critical temperature that is conveniently located at about 100 degrees Celsius, accompanied by an isotropic lattice expansion. As well as providing a material with the fascinating property that magnetism can be switched on and off at will, deep questions about the underlying mechanism for the transition remain.We have already demonstrated the capability to grow epitaxial thin films of this material in Leeds and the intrinsic transition has been characterized by SQUID, synchrotron x-ray diffraction, x-ray magnetic circular dichroism, and polarised neutron reflectometry by our research partners in the USA and UK. We now seek to use joint NSF-EPSRC support to cement this link, and carry out some novel experiments where we seek to control the AF-F phase transition using extrinsic parameters. In the films we have at present, as is known in the bulk, the position of the phase boundary can be controlled intrinsically by the exact FeRh stoichiometry. A few tantalising results are present in the literature where the transition has been quite markedly affected by other external parameters by building heterostructures incorporating magnetostructural materials. Here we will throw light on the underlying mechanism for the magnetostructural response by exploring such heterostructures and the response of the FeRh to extrinsic strain, magnetostatic and exchange fields, and seek ways in which they might be combined to enhance each other.

The Leeds Condensed Matter Physics Group have been regular users of synchrotron radiation at the NSLS now for over six years, where the unique element-specific sensitivity to magnetism of polarized soft x-rays has made great contributions to our research in studying disorder, anisotropy and hysteresis in a variety of nanomagnetic systems. Here we request travel funding to allow us to pursue here two main avenues of research in our new two year user programme at that facility. The first is soft x-ray magnetic scattering from arrays of nanomagnets, fabricated at the Brookhaven Center for Functional Nanomaterials, which exhibit frustrated geometries: whilst the underlying physical structure is periodic, the magnetic structure will display only short range order due to the frustration. Off-specular magnetic scattering will allow us to characterize this disorder as a function of sample array geometry, magnetic field, and temperature, yielding complementary information to real space imaging techniques. The second area is in the study of magnetic nanoclusters, formed by gas-phase aggregation and deposited as part of a magnetic multilayer stack such as a tunnel junction. We have the capability to produce very narrow and well-controlled size distributions, so size dependences. Here we will study spin-orbit moment ratios and chemical composition, such as oxidation from surrounding tunnel barrier material, using XMCD spectroscopy. Unlike similar european facilities, synchrotron beamtime at the NSLS does not come with money to support travel to the facility. The experiments form part of our ongoing and highly successful joint programme on magnetic scattering between Leeds and ISIS. The grant request is for travel and subsistence funds only to allow a team of three people to travel to Brookhaven for five weeklong periods in order to operate the experiment 24 hours a day, as well as carry out sample fabrication at the CFN and present our results at conferences.