ABSOLUTE DIELECTRONIC RECOMBINATION CROSS-SECTIONS OF HYDROGENLIKE HELIUM

We have measured the DELTAN=1 dielectronic recombination cross section s of hydrogenlike helium. Recombination rates were investigated as He ions interacted with free electrons in the electron-cooler section of an ion storage ring. The ion beam was cooled prior to recombination, resulting in enhanced energy resolution. Fits to the 2l2l' resonances yielded transverse and longitudinal temperatures of kT(perpendicular-t o) = 0.15 eV and kT(parallel-to) = 0.8 X 10(-4) eV, respectively. The resulting peak widths are approximately 0.3-eV full width at half maxi mum. The measured integrated cross sections are in qualitative agreeme nt with calculated resonance strengths.