The heavy ion analyser PICCA for the comet Halley fly-by with Giotto

The heavy ion analyzer RPA2-PICCA is designed to identify the composition and distribution of thermal positive ions in the coma of the comet Halley. The instrument is an electrostatic analyzer which takes advantage of the large relative flyby velocity and the fact that the ions in the inner coma should have low temperatures and be predominantly singly charged. Thus, the energy/charged measurements can be directly related to the mass distribution of the ions. Mass identification will be provided in the range from 10 to 203 amu (atomic mass units) with a mass resolution of either 0.4 amu or 1 amu, dependent on the ion mass.