Survey of the K-shell emission from heliumlike ions with an X-ray microcalorimeter

The Electron Beam Ion Trap Microcalorimeter Spectrometer (ECS) routinely surveys the K-shell x-ray spectra that fall into the energy range between 200 eV and 14,000 eV. The spectra serve as in situ energy references and include the K-shell emission from ions between boron at the low-energy end and krypton at the high end. Example spectra are presented of the n = 2 → n = 1 emission from heliumlike noble gas ions neon, argon, and krypton, from the heliumlike transition metals iron and nickel, as well as the heliumlike ions of boron, silicon, sulfur, and germanium.