First observation of the competitive double-gamma (“γγ/γ”) decay process N. Pietralla, C. Walz, H. Scheit, T. Aumann, R. Lefol and V.Yu. Ponomarev EPJ Web of Conferences, 107 (2016) 03002 Published online: 19 January 2016 DOI: 10.1051/epjconf/201610703002