SPECIAL ION DETECTORS WHICH REDUCE THE CONTAMINATION IN ELECTROMAGNETIC ISOTOPE SEPARATORS OR SPECTROMETERS

Special ion detectors for mass separators or spectrometers are proposed which reject a large percentage of contaminating ions of the mass m passing the exit slit for mass mo because of scattering processes in their flight through the vacuum system. Such detectors accept ions only if they lie within a small range of angles of inclination and if they have the correct energy. Since such a detector is absolutely insensitive to ions scattered just behind the ion source and just before the exit slit, a higher rest gas pressure than normal can be tolerated in these regions, as long as a lower rest gas pressure than normal is achieved in the main separator tank, thus reducing rest gas scattering. In addition, with a better pumping geometry the rest gas pressure in the ion acceleration region is able to reduce the number of ions of wrong energy formed by charge exchange processes. © 1979.