External Beam Upgrade
On the ion accelerator of the Jožef Stefan Institute, an extensive upograde was done on the beam line with an external beam (used for analysis objects in the external atmosphere). The main goal of the renovation was the possibility of measuring elemental distributions over the surface of a sample of dimension ~ 1 cm with a spatial resolution of ~ 100 µm. We installed a doublet of magnetic quadrupole lenses for focusing protons on the beam line, replaced the Al exit window with a thin window made of Si₃N₄ with a thickness of 500 nm and installed a chopper in the beam tube, which enables accurate normalization of the proton incident dose. We created control software that allows the movement of the sample and the simultaneous capture of X-ray spectra. The acquired data is assembled into a final image, which represents the distribution of each element. The spatial resolution of the measurement is determined by the transverse dimension of the proton jet in the air. We estimate the resolution after renovation at ~ 70-80 µm.
The figures above show the result of a test measurement on the grid and a map of the distribution of potassium in the plant leaf.
