Measurement of carbon cluster charge state passing through thin foils using a luminance plate

A measurement system based on Coulomb explosion imaging for analyzing the structure of small carbon clusters has been developed. A cluster ion accelerated to the MeV energy region passed through thin foil, and the fragment atoms exploded with Coulomb repulsion were detected with a luminance screen detector. The trace image of the fragment atoms on the screen of the detector monitored by the CCD camera was downloaded as digital data to a hard disc. In preliminary experiments, both chain and ring structures were observed for C3 and C6, respectively. In addition, we measured the average charge states of constituent atoms of the carbon cluster after it passed through the thin foil; these charges are related to the cluster structure.