On the 18th of August 2016, we lost our colleague and friend Professor Nikos D.Giokaris. He died at the age of 66 and more than twenty years of his lifetime he participated in activities of our international organization being first a member of the Program Advisory Committee for particle physics and later a member of the Scientific Council of the Joint Institute for Nuclear Research.

He studied physics at the University of Athens and the University of Chicago and then he worked at some universities of Europe and USA, at Fermilab. Since 1996 he was an Associate Professor at the Physics Department of the University of Athens.

He participated in a variety of fixed target experiments with hadron, neutrino, and electron beams. Нe was a participant of the CDF collider experiment at the Tevatron of Fermilab. At the CERN project ATLAS he with his group of scientists of the University of Athens made a considerable contribution to the construction and the commissioning of the Hadronic Tile Calorimeter. High pressure gas calorimeters for high energy/high luminosity colliders is one of his highly-evaluated proposals. Among his other effective proposals are the use of the total transverse energy in top-antitop quark candidate events to separate the signal from the background and, more recently, the development of a technique to use the lepton (electron and muon) transverse momentum to obtain an accurate measurement of the top quark mass. He coauthored more than 300 papers resulting in more than 18000 citations worldwide. He was invited to referee papers for the Physical Review Letters and the Nuclear Instruments and Methods in Physics Research. His latest research interests included the precise measurement of the top quark mass with CDF and ATLAS and the search for the Standard Model Higgs particle with the ATLAS experiment.