Electron scattering by gas in HVEM at energies between 0.5 MeV and 2.5 MeV

The problem of observing sensitive materials in electron microscopy is not fully resolved at the time being. One of the questions in biology is the possibility of doing experiments with hydrated samples. The authors have chosen to test a given type of environmental cell; it is transparent to electrons. The gas pressure is maintained by differential pumping. In order to establish the conditions in which images should be obtainable with good contrast and resolution, they have determined the partial electron scattering cross-sections with several gases at different pressures. (Auth.)