Question: Kyriakos Tamvakis is a Greek theoretical physicist and professor who has held positions at what European research organization that operates the largest particle physics laboratory in the world?

 Kyriakos Tamvakis studied at the University of Athens and gained his Ph.D. at Brown University, Providence, Rhode Island, USA in 1978.  His thesis title was "Induced Boson Selfcouplings In Four Fermion And Yukawa Theories".  Since then he has held several positions at CERN’s Theory Division in Geneva, Switzerland.  He has been Professor of Theoretical Physics at the University of Ioannina, Greece, since 1982. Kyriakos Tamvakis (Greek: Κυριάκος Ταμβάκης ; born in 1950 ) is a Greek theoretical physicist and professor at the University of Ioannina.  Professor Tamvakis has published more than 100 articles on theoretical high-energy physics in various journals and has written two textbooks in Greek, on quantum mechanics and on classical electrodynamics. <SEP> TRIUMF is Canada's national laboratory for particle and nuclear physics and accelerator-based science.  TRIUMF is considered Canada's premier physics laboratory, and is consistently regarded as one of the leading subatomic physics research centers on the international level.  Owned and operated by a consortium of universities as a joint venture, TRIUMF is located on the south campus of one of its founding members - the University of British Columbia in Vancouver, British Columbia.  TRIUMF houses the world's largest cyclotron, a source of 520 MeV protons, which was named an IEEE Milestone in 2010.  TRIUMF's accelerator-focused activities involve particle physics, nuclear physics, nuclear medicine, materials science, and detector and accelerator development. <SEP>  CERN is an official United Nations Observer.  Established in 1954, the organization is based in a northwest suburb of Geneva on the Franco–Swiss border, ( ) and has 22 member states. The European Organization for Nuclear Research (French: "Organisation européenne pour la recherche nucléaire"), known as CERN ( ; ] ; derived from the name "Conseil Européen pour la Recherche Nucléaire"), is a European research organization that operates the largest particle physics laboratory in the world.  Israel is the only non-European country granted full membership. <SEP> The High Energy Accelerator Research Organization (高エネルギー加速器研究機構 , Kō Enerugī Kasokuki Kenkyū Kikō ) , known as KEK, is a Japanese organization whose purpose is to operate the largest particle physics laboratory in Japan, situated in Tsukuba, Ibaraki prefecture.  It was established in 1997.  The term "KEK" is also used to refer to the laboratory itself, which employs approximately 695 employees.  KEK's main function is to provide the particle accelerators and other infrastructure needed for high-energy physics, material science, structural biology, radiation science, computing science, nuclear transmutation and so on.  Numerous experiments have been constructed at KEK by the internal and international collaborations that have made use of them.  Makoto Kobayashi, emeritus professor at KEK, is known globally for his work on CP-violation, and was awarded the 2008 Nobel Prize in Physics.