The Antimatter and Nuclear Engineering group specializes in the development and applications of positron-based spectroscopic tools in condensed matter research. It also works on reactor and radiation physics research in close collaboration with VTT research groups.
Recent review: “Defect identification in semiconductors with positron annihilation: Experiment and theory”, Rev. Mod. Phys. 85, pp. 1583 – 1631 (2013).
Positron physics and defect spectroscopy
Positron annihilation spectroscopy enables the unambiguous identification and quantification of vacancy defects and their surrounding atoms in crystalline solids. For instance, in the case of semiconductor materials, this type of basic research aims at the understanding of e.g. mechanisms of electrical compensation, the origin of optical absorption and the nature of electronic transitions of photoluminescence. In the past, the group has contributed substantially to the understanding of defect and doping impurity structures both in silicon and compound semiconductors, as well as the physics of positrons in solids.
Our work in this field involves the study of defects in semiconductors, development of positron methods for the study of matter, and nuclear materials research. All the instrumentation has been designed and constructed in-house.
Reactor and radiation physics
In reactor physics, the current research interests include Monte Carlo burnup calculation methodology, diffusion coefficient generation by the Monte Carlo method and uncertainty analysis in reactor physics. Essentially all research is computational using and/or developing codes such as Serpent, MCNP and NJOY in close collaboration with VTT Technical Research Centre of Finland Ltd.
In radiation physics our interests are in the computational methods of gamma-ray spectrometry and identification. The group is the birthplace of SAMPO codes for spectrum analysis and the expert system SHAMAN for subsequent radionuclide identification and quantification. We also belong to the developers of LINSSI database for gamma-ray spectrometry and are active members of the LINSSI Users' Group.