EU-funded scientists are embarking on a major effort to construct a nuclear atomic clock, a device that would represent a major improvement over the atomic clocks used to set time today. The work is being made possible thanks to a EUR 1.3 million, 5 year 'starting grant' from the European Research Council (ERC) to Thorsten Schumm of the Institute of Atomic and Subatomic Physics at Vienna University of Technology (TU Vienna) in Austria. The ERC funding comes on top of a START Award granted to Dr Schumm at the end of 2009 by the Austrian Science Fund (FWF). At the heart of the project is the radio-isotope 229-thorium. Atoms are made up of a nucleus which is surrounded by a shell of electrons. In most atoms, the amount of energy required to trigger changes (such as 'excitations') in the nucleus and the electron shell differs by several orders of magnitude. As a result, scientists working on different components of the atom tend to use different tools to study them; atomic physicists predominantly use lasers to look at the electron shell, while nuclear physicists rely on particle accelerators to investigate the nucleus. 229-thorium is different in that it has an unusually low-energy nuclear excited state. 'It may hence be possible to create an excited state of an atomic nucleus using (laser) light!' the researchers write on their website. 'It is the aim of this project to find and characterise this low-energy nuclear transition and make it accessible for fundamental investigations and applications.' Specifically, Dr Schumm and his colleagues hope to apply the unusual properties of 229-thorium's nucleus to the construction of a nuclear atomic clock. Currently, a second is defined as 9,192,631,770 oscillations of a light wave. This causes specific changes in the electron shell of an atom of caesium, a fact which is exploited in atomic clocks that are used to set our time standards. However, electron transitions are highly sensitive to magnetic and electric fields, so atomic clocks come with complex shielding structures. Furthermore, the measurements have to be carried out in free-fall, meaning that the next generation of atomic clocks would have to be based on satellites. A nuclear atomic clock based on 229-thorium would get around these problems. 'Thorium ions can be embedded in UV [ultraviolet] transparent crystals,' the researchers explain. 'The complicated and bulky vacuum system currently required by atomic clocks could be replaced by a single crystal at room temperature doped with 229-thorium atoms.' If the team is successful, the resulting nuclear atomic clock would also enable the accuracy of our time standards to be significantly increased. Dr Schumm has already started building his research team and work is underway to build a state-of-the-art laboratory that meets the high standards needed for his work with lasers (i.e. the temperature is kept extremely stable and vibration levels are low) and has radiation protection approval. The lab should be ready by October 2010. According to the team, the Institute of Atomic and Subatomic Physics is one of just a few places in the world where nuclear and particle physics can be combined with precision laser spectroscopy. 'This environment is truly unique and demonstrates TU Vienna's commitment to this project,' commented Dr Schumm.