PIXE analysis of environmental and biological samples using a proton microprobe

For the investigation of environmental and biological samples a proton microprobe has been built at the Bochum Dynamitron Tandem Laboratory. By several improvements of the apparatus, e.g. optimization of the focal lengths and fine adjustment of the quadrupole lenses according to the results of a detailed beam transport calculation the beam diameter has been reduced to 6 μm fwhm. This device is used to measure lateral distributions of trace elements with Z > 15 in thin samples by means of PIXE. This technique has been applied to environmental and biological samples. An impactor sample has been investigated in order to test PIXE trace element measurements performed with a standard accelerator beam. In the field of biological samples our investigations concern the level of cooperative cellular colonies. Proceeding from a microphoto of a thin sample of human skin the element content in the region of interest has been determined by scanning. (orig.)