At the Tip of an MeV Beam: Provoking Cells and Performing Tomographic Imaging

Biological applications of ion beams have recently become a new important research field using single ion hit facilities to study individual living cells and their response to the hit of a counted number of ions. One motivation is the search for a better understanding of the fundamental processes taking place in cells and organs as a result of irradiation. Another comes from the increasing interest in using high energy protons and heavy ions as a modality for radiotherapy of deep seated tumours. In the view of treatment efficiency, study of cell culture behaviour under controlled radiation experiments, and in different chemical environments at single ion hit facilities, is a first step towards a better understanding of the processes. Tomographic techniques are applicable to situations where you need information of the inside of an object but do not want to section it into thin slices or cannot do it. Using focused MeV ion beams for tomography restricts the sample size to the order of 10-100 mu m, depending of the initial energy. On the other hand, the ability to focus at a sub-micrometer level makes ion beams well suited for analyses of small sized objects as cells, spores, etc. The scanning transmission ion microscopy mode of tomography gives the mass density and corresponding morphological structure of holes and pores. It can then be used to correct the results from the other mode, particle induced X-ray emission tomography. Here is discussed a porosity analysis of bentonite clay that is planned to form an important buffer zone around canisters filled with spent nuclear reactor fuel waste deposited 500 m underground in Sweden