Energy distribution of an ion beam extracted into air with a large bore metal capillary

Abstract In order to clarify the transmission properties of an ion beam extracted with a large bore metal capillary into air, we measured the energy distributions of extracted 4.0 MeV alpha particles using a pinhole slit. The metal capillary we used is a conventional injection needle with 500  μ m inner diameter. As a result, we obtained two-dimensional intensity distributions of the ion beam extracted into air with this large bore metal capillary and the energy spectra at each position. We discuss the result of two-dimensional intensity distributions and report the difference of the energy spectra at the center part and at the edge.