CENTA
A Centre for Nuclear and Accelerator Technologies (CENTA) has been established at the Comenius University in Bratislava comprising of a tandem accelerator designed for Ion Beam Analysis (IBA), Ion Beam Modification (IBM) of materials, Nuclear Reaction Analysis (NRA) of environmental and material samples, and Accelerator Mass Spectrometry (AMS), initially only for Be-10. Therefore, we performed AMS analyses in cooperating laboratories (University of Vienna, universities in the USA (Tucson and Athens)) and in Institute for Nuclear Research in Debrecen (C-14).
Recent developments in accelerator technologies for IBA/IBM/NRA and AMS analyses, and their applications in nuclear, environmental, biomedical and material sciences have been an inspiration for creation of the CENTA laboratory comprising of a state-of-the art tandem accelerator designed for:
- IBA applications in environmental, life and material research, including cultural heritage studies;
- NRA studies with charged particles for new generations of fission reactors, for thermonuclear reactors, for environmental, biomedical and astrophysical research;
- IBM - modifications of materials used for construction of new generation of fission reactors, for thermonuclear reactors, for research in nanotechnology and space research;
- AMS studies of long-lived radionuclides in nuclear, environmental, life, geological and astrophysical sciences.
The orientation of the laboratory has been driven by general needs to establish in Slovakia a national laboratory devoted to ion beam studies and applications, and to assure for the future wide-range research capabilities and applications. Due to financial constraints, the construction of the CENTA laboratory was carried out in two stages. In the first stage, thanks to projects within the EU Structural Funds and in cooperation with the International Atomic Energy Agency, two ion sources were installed (Alphatross for gas and MC-SNICS for solid targets), the injection system, the 3 MV tandem accelerator of ions Pelletron, and a high energy analyser with two ion beam end stations. In the second stage, within the project "Advancing University Capacity and Competence in Research, Development and Innovation (ACCORD, TMS2014+:313021X329)", co-financed by the European Regional Development Fund, a unique Analyser of high-energy ions for accelerator mass spectrometry of long-lived isotopes was put into operation. Later installations will also include a nuclear microscope, a raster station for IBM studies of materials, and a station for biomedical research.
The analyser directly analyses radioactive nuclei as if they were stable, so there is no need to wait for their radioactive decays because the mass of the ions is analysed directly, not the radiation that arises during the radioactive decay of nuclei (e.g., beta-radiation), which due to their long half-lives is a serious problem. A target, prepared from the investigated sample, is placed in the ion source, from which a beam of studied ions is forwarded to the tandem accelerator, and then, after acceleration and focusing of the beam, the ions are analysed in the Analyser of high-energy ions, consisting of high resolution electromagnet, two 45o electrostatic analysers and the ionised chamber as the-end-of-the-line detector. When accelerated ions are analysed, the background is substantially reduced, so it is possible to analyse for example carbon-14 in microgram samples of carbon, which is a million times smaller than could be analysed using gas detectors. The measurement time has also decreased significantly from several days or weeks to a few minutes, so a preparation of samples represents the substantial part of the analysis (several hours/sample) . AMS will make it possible to significantly expand the research, especially long-lived radionuclides from tritium through beryllium-10, carbon-14, aluminum-26, chlorine-36, calcium-41, iron-55, strontium-90, iodine-129, cesium-135,137, lead-210, radium-226, protactinium-231, isotopes of thorium, uranium, neptunium, plutonium, americium up to isotopes of curium. AMS represents a revolution in the analysis of isotopes because it allows for research that was not possible before, either because of the low sensitivity of the analytical equipment or because of the necessity to use too large samples that were not available.
The analyser, together with facilities for sample analysis using ion beams, will significantly expand the research and use of accelerator technologies in natural, biomedical, technical, and humanitarian sciences, from astrophysics to archaeology. Among the most important applications will be climate change studies (Milankovitch cycles, variations in solar activity, past volcanic eruptions), space weather research (solar eruptions in the past, possible impacts on terrestrial infrastructure and space flights), the use of radionuclides as tracers of natural processes in the atmosphere-biosphere and atmosphere-hydrosphere (ocean) ecosystems, investigations of radioactive pollution of the environment from the operation and accidents of nuclear power plants, investigations of rare nuclear processes and decays, including the search for dark matter particles, nuclear reaction studies for astrophysics and thermonuclear physics, investigations of radioactive contamination of new generation of materials, modifications of properties of materials after their irradiation at the accelerator, research on damage to DNA and living organisms after their irradiation with ionizing radiation, research on degenerative changes in the brain of patients suffering from Alzheimer's and Parkinson's disease, investigations of the authenticity of works of art (paintings, statues), dating of archaeological and geological samples, and in many other applications. Much of this research will be possible thanks to terrestrial isotope archives (tree rings, ice-core samples from deep boreholes, stalagmites/stalactites, freshwater and marine sediments, etc.), but also thanks to extraterrestrial archives (meteorites, lunar samples and in perspective also rock samples from Mars), because some of them store isotopic information from thousand years to hundreds of millions of years. Broad domestic and international cooperation, including joint scientific projects with the participation of students, PhD students, and postdocs, will be a necessary prerequisite for successful research in such a wide range of scientific programs.
The built accelerator centre, including AMS and IBA/NRA technologies (produced by National Electrostatic Corp. (USA), together with low-background gamma- spectrometry, which has been a traditional research program at the Department of Nuclear Physics and Biophysics for about fifty years, belongs to the world unique laboratories engaged in accelerator technologies and in radioactivity studies of terrestrial and extraterrestrial objects.
A dedicated hall to accommodate the tandem accelerator has been built at the Comenius University campus at Mlynská dolina. The hall design separates the ion beam lines (placed in a bunker covered by soil) from the AMS line, enabling thus work in different radiation environments.
