Cerenkov radiation as a light source for the 2000–620-Å spectral range

Spectral power density from Cerenkov radiation was measured in the vacuum ultraviolet from 2000 to 620 Å. The radiation was produced by passing a 500-MeV 1-mA-peak-current electron beam through 1.4 m of 1 atm of helium gas at room temperature. In the photon energy range from 6 to 20 eV, approximately 1014 photons /sec/Å/mA of electron-beam current were emitted, and our detection apparatus attenuated the radiation by 4–5 orders of magnitude.