Neutron research with multiple applications
Snaking through the woods outside the small Flemish town of Geel are a number of large metal tubes up to 400m long radiating out from a central building. This strange-looking structure is GELINA, a linear electron accelerator based at the Institute for Reference Materials and Measurements (IRMM), part of the European Commission's Joint Research Centre. 'We're the nuclear guys!' says Peter Rullhusen cheerfully, as CORDIS News embarked on a tour of the facilities at the IRMM. Dr Rullhusen is the Head of the Neutron Physics Unit. Dr Rullhusen explains that at the centre of an atom are positively charged protons and neutrons, which have no charge. In the central building of the accelerator, an electron beam is fired at a uranium target. This leads to the production of neutrons of different energies, which whiz off at high speeds down the flight paths, where regularly spaced experimental stations containing a range of instruments can perform various measurements and analyses. Understanding how neutrons behave is vital to ensuring the safety of existing nuclear power plants and developing safe new reactors, and GELINA is one of the leading centres in the world when it comes to producing high resolution, accurate neutron data. Nuclear waste is another issue addressed by Dr Rullhusen's team. One idea the scientists are working on is transmutation, in which the 'nastiest isotopes' are extracted from the nuclear waste and transformed into isotopes which are either stable or have shorter half lives. Accurate neutron data are also essential for the development of ways to reduce the amount of waste produced by the reactor in the first place. However, the work of the Neutron Physics Unit extends beyond the sphere of nuclear energy to include fields as diverse as medicine and archaeology. They are partners in a project called 'Ancient Charm', which is using GELINA to analyse the elements present in ancient objects. The technique being used is called Neutron Resonance Capture Analysis (NRCA). The technique involves placing the ancient object in the path of the neutrons from the accelerator. Each element captures neutrons of specific energies, so by looking at the energies of neutrons captured by the object, the researchers can deduce what elements the object is made of. The technique is non-destructive, giving it a huge advantage over other analytical methods which often require the removal of a sample from the object. With the technique, archaeologists hope to learn more about how our ancestors made these objects and help us determine how best to conserve them. Furthermore, the technique can be used to expose fakes. One study analysed the composition of bronze statuettes which were considered to be of Etruscan origin, as well as objects which were allegedly Etruscan but which were suspected of being fake. Here the most important question is the level of zinc in the statuette, due to the known fact that genuine Etruscan statues would be expected to have extremely low levels of zinc compared to bronze produced later by the Romans. Analyses at GELINA revealed this to be the case, while many objects which experts had identified as likely fakes were found to have higher levels of zinc. The work at GELINA is complemented by measurements at a second accelerator in the Unit, the Van de Graaff accelerator, where quasi-monoenergetic neutrons are produced. These are used for investigating the nuclear fission process: the splitting of heavy nuclei by neutron bombardment, the source of nuclear energy. Another very important field is nuclear reaction standards, for example the interaction of neutrons with the isotope boron 10. This reaction has found applications in the medical field, with the development of boron neutron capture therapy. The method, largely developed by the JRC's Institute for Energy in Petten, the Netherlands, entails injecting boron 10 isotopes into a patient with a cancerous tumour, and firing a neutron beam at them when the Boron atoms have accumulated in the malignant cells. This splits the boron atom in two, triggering the release of an alpha particle which damages the cancerous cell. The fact that measurements taken at GELINA have an extremely high resolution makes the facilities attractive to research teams from across Europe and beyond. Thanks to the EU-funded NUDAME (Neutron Data Measurements) project, research teams from anywhere in Europe can spend time at the IRMM and carry out experiments of their choice in fields such as radioactive waste management, nuclear technology and nuclear reactor safety.