EVIDENCE OF SUPERELASTIC ELECTRON COLLISIONS FROM H2+ STUDIED BY DISSOCIATIVE RECOMBINATION IN A COOLER RING T.Tanabe1, H.Takagi2, I.Katayama3.1, K.Chida1, T.Watanabe1, Y.Arakaki1, Y.Haruyama4, M.Saito4, I.Nomura5,T.Honma6, K.Noda6, and K.Hosono7 1High Energy Accelerator Research Organization, Tanashi, Tokyo, 188-8501, Japan 2Physics Laboratory, School of Medicine, Kitasato University, Sagamihara 228-0829, Japan 3Center for Nuclear Study, University of Tokyo, Tanashi, Tokyo, 188-8501, Japan 4Kyoto Prefectural University, Kyoto, 606-0823, Japan 5National Institute for Fusion Science, Toki 509-5292, Japan 6National Institute of Radiological Sciences, Anagawa, Chiba 263-8555, Japan 7Himeji Institute of Technology, Himeji 671-220, Japan Vibrational cooling of H2+ by superelastic electron collisions is demonstrated by dissociative recombination using an ultracold electron beam from a storage ring.