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Research into the structure of extremely rare atomic nuclei, and how they decay, is providing the deepest insights yet into the formation of heavy elements that occur during explosions on the surface of stars. The research carried out by an international team of scientists at the GSI (link opens in a new window) Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, represents a major milestone in current nuclear structure physics research, the results of which have been published in Nature, 20th June 2012.
The team of researchers, including nuclear physicists from the Universities of Surrey and Edinburgh, supported by the Science and Technology Facilities Council (STFC), has performed the first experiment to study the radioactive decay of Tin-100. A very rare and unstable isotope of Tin, Tin-100 does not occur in nature, but only on the surface of exploding stars, and for no more than a second. It is also the heaviest element observed with equal proton and neutron numbers.
To study the isotope in detail the team at GSI used a highly specialised gamma-ray detector, known as RISING, designed and developed by the Nuclear Physics Group at STFC’s Daresbury Laboratory and the University of Liverpool. The most powerful instrument of its kind in the world, the researchers were able to use RISING to measure the half-life and decay energy of Tin-100 and its decay products, as it captured the extremely weak gamma rays emitted as it decayed.
Professor Paddy Regan, Professor of Nuclear Physics at the University of Surrey, and Spokesperson for the RISING collaboration which undertook the research on Tin-100 said: “Tin-100 is the heaviest of all nuclei with equal proton and neutron numbers that can currently be studied at this level and it’s great to observe such fascinating results. This detailed study of the internal structure of this most exotic nucleus also gives new and unique insights into the internal structure of atomic nuclei and the creation of elements heavier than iron. ”
Not only is Tin-100 extremely rare, it is also 'magic’, according to the ‘shell model of nuclear physics’, which identifies a small handful of ‘magic numbers’, one of which is number 50, that give rise to special properties. Tin-100 is therefore ‘doubly magic’ because it comprises 50 protons and 50 neutrons, and is of particular interest to nuclear physicists as it is the heaviest atomic nucleus, with equal numbers of protons and neutrons yet to be observed.
The Tin-100 nuclei exist on average for only one second before changing to form another element, indium-100. This change arises from the transformation of a single proton in Tin-100 to a neutron via the nuclear process of decay. The research showed that the speed of this decay in Tin-100 is the fastest of its kind so far observed, and presents indisputable evidence for a very simple underlying quantum shell structure for the protons and neutrons to form the Tin-100 nucleus.
Professor Philip Woods, Head of the Nuclear Physics Group at the University of Edinburgh, said: “This result illustrates the fundamental insights into nuclear structure and decay processes that can be gained by the study of these rare doubly-magic nuclei. It also shows the importance of UK nuclear physicists playing leading roles in both the science programme and development of advanced detection systems at world leading laboratories such as GSI."
Professor John Simpson, Head of STFC’s Nuclear Physics Group, said: “Nuclear physicists look to create and study the very heaviest elements predicted to exist. It is really exciting to see technology developed by the Nuclear Physics Group at STFC and UK Universities contribute to this research that could answer some of the most fundamental questions about our universe.
Furthermore, the instruments and techniques developed through this kind of research can normally go on to be applied to a wide range of other areas including energy generation and the diagnosis and treatment of cancers.”
This research paves the way for further UK science programmes at the future international FAIR (link opens in a new window) accelerator (Facility for Antiproton and Ion Research) at GSI, where the UK will play a significant role in this growing area of atomic science through a collaboration called NuSTAR (link opens in a new window) (Nuclear Structure Astrophysics and Reactions).
Superallowed Gamow-Teller Decay of the Doubly Magic Nucleus Sn-100, Hinke et al., Nature (link opens in a new window), 21. Juni 2012 – DOI: 10.1038/nature11116
available on request: RISING Gamma Ray detector
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The University of Surrey
The University of Surrey is one of the UK’s leading professional, scientific and technological universities with a world class research profile and a reputation for excellence in teaching and research. Ground-breaking research at the University is bringing direct benefit to all spheres of life – helping industry to maintain its competitive edge and creating improvements in the areas of health, medicine, space science, the environment, communications, defence and social policy.
Programmes in science and technology have gained widespread recognition and it also boasts flourishing programmes in dance and music, social sciences, management and languages and law. In addition to the campus on 150 hectares just outside Guildford, Surrey, the University also owns and runs the Surrey Research Park, which provides facilities for 140 companies employing 2,700 staff.
The Sunday Times names Surrey as ‘The University for Jobs' which underlines the university’s growing reputation for providing high quality, relevant degrees.
Surrey is a member of the 1994 Group (link opens in a new window)of 19 leading research-intensive universities. The Group was established in 1994 to promote excellence in university research and teaching. Each member undertakes diverse and high-quality research, while ensuring excellent levels of teaching and student experience.
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Amongst the largest of the colleges of the University of London, Queen Mary has accepted an invitation to join the Russell Group, which represents the 24 leading universities in the UK. We will officially join the Group in August 2012.
Queen Mary’s 3,800 staff deliver world class degree programmes and research across 21 academic departments and institutes, within three sectors: Science and Engineering; Humanities, Social Sciences and Laws; and the School of Medicine and Dentistry.
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The College has a strong international reputation, with around 20 per cent of students coming from over 100 countries. Queen Mary has an annual turnover of £300 million, research income worth £70 million, and generates employment and output worth £600 million to the UK economy each year.
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