Text for EPSRC JeSRP1 form -------------------------- Last Revised: 24.11.05 Title ----- Decay Spectroscopy of Exotic Nuclei at FAIR Joint Proposal Reference ------------------------ D225007 Start Date ---------- 1.8.2007 Duration -------- 48 months Objectives ---------- 1. To construct a new generation ASIC-based Double-sided Silicon Strip Detector system for decay spectroscopy experiments of exotic nuclei on the new FAIR accelerator facility at GSI, Darmstadt, Germany. 2. To commission and test this system in-beam, and perform ongoing implantation-decay experiments, primarily at GSI, prior to the availability of beams from FAIR. 3. To maintain a world leading role for UK nuclear scientists and technologists in the development of new methodologies for nuclear physics research. Summary ------- It is an astonishing fact that most of the chemical elements we observe today were created from the ashes of ancient stellar explosions. The most spectacular events of this type are supernovae. With very high sensitivity modern telescopes we can study the chemical abundances of material ejected from distant supernovae and compare these abundances with those found in our own solar system. Understanding these abundances turns out to crucially depend on nuclear reaction processes. Stars can be thought of as naturally occurring nuclear reactors held together by gravity. Fortunately for us the sun is not currently in an explosive phase of development. However, most of the elements now present in the solar system were in fact produced in earlier generations of exploding stars. In this sense, we can think of ourselves as cosmic debris. The reaction processes in exploding stars are very different to those found in the sun, and involve nuclear species never seen before on our planet. Rather like chemicals that behave very differently according to their electronic shell structure - sodium is highly reactive with water but neon with one less electron is an inert gas - nuclear species can either be very stable or very reactive according to their precise composition of protons and neutrons. Reactions involving these previously unobserved nuclear species are responsible for the chemical abundances we observe today, but until now we have had no chance to study them. The new FAIR accelerator being built in Germany is the only one in the world that can produce intense, high energy beams of the heaviest naturally occurring element, Uranium. This element itself will have been produced during ancient supernova explosions in a chain of nuclear reactions scientists call the r-process in which many neutrons are rapidly absorbed by a seed nucleus! Our experiments will reverse this process, and use advanced separation and detector equipment to observe new exotic nuclear species produced by the fission (break up) of Uranium. These studies should provide a vital key for unlocking the mysterious origin of the heavy chemical elements. These are very difficult experiments, and as part of the international team, leading nuclear scientists from the UK are asking for money to build a fantastic new detector system, better than any other of its kind in the world. This team are world experts at building such devices. The experiments will be so sensitive we expect to be able to reach the very limits to nuclear existence for some elements. At these extreme limits new, and rare, nuclear decay processes can be studied. There are good reasons to believe the structure of extremely exotic nuclei will be very different, with new shell structures and new ways in which pairs of nucleons assemble inside the nucleus. High precision experiments on the beta-decays of exotic nuclei will enable us to test one of the key predictions of the Standard Model of Particle Physics - the so-called CVC hypothesis - which claims the fundamental rate of transformation of protons into neutrons should not depend on which nucleus the particles are contained in. These experiments may also provide clues for new science beyond the Standard Model. So, you see, our journey will take us to strange places in the land of the very small and the land of the very large. We can now see these realms are intimately connected to one another. In the end it is by visiting these exotic places we will understand the familiar world we live in today. At the same time by developing cutting edge technologies for this exciting work, we will be training new scientists for our country, perhaps you could be one of them? Beneficiaries ------------- The science programme outlined in this proposal will address key issues relating to the astrophysical r-process, nuclear structure at the limits of stability, and the physics of the Standard Model. The results will be of compelling interest to the international community of nuclear physicists, particle physicists and astrophysicists. For example, it will enable the understanding of the origins and abundance of heavy nuclei, the exploration of the evolution of shell structures far from stability, and crucial tests of supporting hypotheses for the Standard Model. This extraordinary and wide-ranging scientific programme will require equally extraordinary experiments utilising state of the art detector and instrumentation technologies. The long standing collaboration of Edinburgh and the UK Nuclear Physics community with Micron Semiconductor Ltd. UK has produced unique product features and production capabilities which will continue to provide this company with excellent export opportunities. ASIC instrumentation is widely recognised as a key enabling technology for the future nuclear physics programme. The ASIC instrumentation developments proposed will provide the UK with many opportunities for wider exploitation at future international radioactive beam facilities such as the EURISOL project. Both CCLRC RAL and DL have proven records in providing open access to advanced instrumentation and software technologies. Because ASIC technology is becoming pervasive in advanced radiation detection and imaging applications, projects of this type enhance core CCLRC skills and capabilities to the benefit of the wider UK science base.