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?

<P0-S0> 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. <P0-S1>  CERN is an official United Nations Observer. <P0-S2>  Established in 1954, the organization is based in a northwest suburb of Geneva on the Franco–Swiss border, ( ) and has 22 member states. <P0-S3>  Israel is the only non-European country granted full membership. <SEP> <P1-S0>  Kyriakos Tamvakis studied at the University of Athens and gained his Ph.D. at Brown University, Providence, Rhode Island, USA in 1978. <P1-S1>  His thesis title was "Induced Boson Selfcouplings In Four Fermion And Yukawa Theories". <P1-S2>  Since then he has held several positions at CERN’s Theory Division in Geneva, Switzerland. <P1-S3>  He has been Professor of Theoretical Physics at the University of Ioannina, Greece, since 1982. <P1-S4>  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. <P1-S5> Kyriakos Tamvakis (Greek: Κυριάκος Ταμβάκης ; born in 1950 ) is a Greek theoretical physicist and professor at the University of Ioannina. <SEP> <P2-S0> 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. <P2-S1>  It was established in 1997. <P2-S2>  The term "KEK" is also used to refer to the laboratory itself, which employs approximately 695 employees. <P2-S3>  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. <P2-S4>  Numerous experiments have been constructed at KEK by the internal and international collaborations that have made use of them. <P2-S5>  Makoto Kobayashi, emeritus professor at KEK, is known globally for his work on CP-violation, and was awarded the 2008 Nobel Prize in Physics. <SEP> <P3-S0> TRIUMF is Canada's national laboratory for particle and nuclear physics and accelerator-based science. <P3-S1>  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. <P3-S2>  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. <P3-S3>  TRIUMF houses the world's largest cyclotron, a source of 520 MeV protons, which was named an IEEE Milestone in 2010. <P3-S4>  TRIUMF's accelerator-focused activities involve particle physics, nuclear physics, nuclear medicine, materials science, and detector and accelerator development.