Radiative electron capture -A tool to detect He++ in space

Large clouds of totally ionised helium and hydrogen might exist in the intergalactic space, invisible for the usual optical observations. These clouds, bombarded with medium energy electrons, should generate photon radiation in the X-ray region. The radiation is associated with the Radiative Electron Capture, REC, by He++ ions and should be observable with space born detectors. The photon spectra calculated for a range of temperatures of the electron spectra as well as several column densities of the plasma clouds are discussed. (orig.)