Radioanalytical methods
The scientific activity of the Radioanalytical methods team (RAM) has been focused on methodological development and multidisciplinary applications of several radioanalytical techniques, namely neutron activation analysis (NAA), photon activation analysis (PAA), X-ray fluorescence analysis (XRF), and accelerator mass spectrometry (AMS). The radioanalytical methods have been applied in cooperation with domestic and foreign institutions namely in the fields of life sciences and ecology, cultural heritage, geology, geochemistry and cosmochemistry, and material research including nuclear technology and forensics. The methods have been employed wherever their advantageous features made them superior over other analytical methods.
NAA, a backbone of the portfolio of radioanalytical methods used at RAM, is a primary method of measurement for quantitative multi-elemental analysis. Combining various analytical modes of instrumental NAA (INAA), with a possibility to employ also radiochemical (RNAA) or pre-activation separation, allows determination of over forty elements, both major and trace ones. For neutron irradiation, NAA uses primarily the research nuclear reactor LVR-15 operated by the Research Centre Řež. An accelerator-driven fast neutron source operated by the NPI Dpt. of Accelerators can be used as an alternative for special applications.
PAA is a complementary method to NAA with similar advantageous features and application area. Number of elements determined by PAA and its sensitivity are generally lower than in NAA, but PAA allows determination of several elements whose determination by NAA is less sensitive, interfered, or even impossible. The lower sensitivity allows analysis of larger, more representative samples, which is required mainly in geochemical analysis. For photon (bremsstrahlung) irradiation, the MT25 Microtron operated by the NPI Dpt. of Accelerators is employed.
XRF is surface multi-elemental analysis technique with a wide field of applications. XRF benefits from its non-destructive character and the possibility to analyze relatively large objects, if a radionuclide source is used to generate X-rays in a sample. This feature is especially appreciated for analysis of archaeological artefacts. RAM team utilizes a modern XRF spectrometer Spectro Midex equipped with helium flush of the sample-detector space, and a motorized xyz sample stage for linear and area scans. Besides that, a Am-241 radionuclide source is available.
AMS is a significant extension of the portfolio of radioanalytical methods employed at RAM. The first and only Czech AMS laboratory, currently operated jointly by the NPU Dpt. of Radiation Dosimetry with the CAS Archaeological Institute, Prague, and the Faculty of Nuclear Sciences and Engineering of the Czech Technical University in Prague, has been built within the RAMSES project supported by MEYSCR (Ultra-trace isotope research in social and environmental studies using accelerator mass spectrometry, 2018-2023), and put in operation in 2022. The AMS laboratory operates a 300 kV Multi-Isotope Low-Energy Accelerator Mass Spectrometry system (AMS MILEA, Ionplus AG), and laboratories equipped for dedicated sample preparation processes. The main RAM research activities with AMS focus mainly on determination of cosmogenic nuclides Be-10 and Al-26 for archaeometry, geochronology, and paleoenvironmental studies.
All four methods are part of the NPI large infrastructure CANAM (Centre of Accelerator and Nuclear Analytical Methods), which allows to perform analyses in partly Open Access mode and thus reduce analytical costs or realize a pilot research without grant support. RAM laboratories are well-equipped for preparation and (radio)chemical treatment of samples, and with several dedicated detectors and spectrometers for radioactivity (gamma radiation mainly) and X-ray measurements.
