You can see a newer device based on the same design here: https://forcetechnology.com/-/media/force-technology-media/pdf-files/unnumbered/energy-and-environment

You can see a newer device based on the same design here: https://forcetechnology.com/-/media/force-technology-media/pdf-files/unnumbered/energy-and-environmental-services/mic/mic-manual-rev-4-generel-december-2020-v4-1.pdf https://forcetechnology.com/-/media/force-technology-media/p... Page 33 shows all of the components and 34 shows the Measuring Ionization Chamber with the housing removed and a radiation warning underneath. They both use Americium alpha foil which is the Americium in a gold matrix.