Quantitative elemental microscopy on lateral highly inhomogeneous meteorite samples using ion beam analysis

A simple system for lateral dead-time correction was developed at the Leipzig ion nanoprobe LIPSION in order to investigate diverse meteorite samples. The meteorite building crystals can often be found in close proximity to massive iron-nickel grains which provides a challenge for ion beam analysis methods, like Particle Induced X-ray Emission (PIXE) or Rutherford Backscattering Spectrometry (RBS) due to the strongly varying dead-time of the detector electronics on such inhomogeneous samples. This leads to incorrect concentration mapping on a local scale. In order to account for this problem, a noise-triggered setup was developed that generates defined pulses statistically in time which are fed into the preamplifiers of the detector electronics and act as pseudo events in the data processing. A comparison of the number of generated and processed pulses allows the computation of a dead-time map and thereby a correction of the collected spectrum on a pixel per pixel basis. The proper function of this technique was verified by measurements on a simple test specimen and a chondrule of the Acfer 094 meteorite.