Michel Gonin is a French scientist expert in nuclear physics, particle physics and neutrino physics. His research focuses on themes related to the primordial cosmology of the Universe. He took part in two major discoveries, the production of quark-gluon plasma in heavy ion collisions and the observation of the phenomenon of the appearance of electron neutrinos in flavor oscillation.
In 1987 he defended his thesis at the University of Strasbourg. After his postdoctoral work at A&M University in Texas, he was recruited as physicist at the Brookhaven National Laboratory. He returned in 1995 to France to be recruited at the Leprince-Ringuet Laboratory of CNRS. Between 1995 and 1998, he was visiting professor at the Niels Bohr Institute in Copenhagen and became professor at Ecole Polytechnique in 2004. In 2021, he was appointed visiting professor at the University of Tokyo and director of the ILANCE Laboratory. Exceptional Class Senior Physicist at the CNRS, he has held many national and international responsibilities such as principal investigator at the IN2P3-CNRS, supervised eight doctoral theses mentoring numerous undergraduate students.
He began his research career working on the mechanism of incomplete nuclear fusion before studying during his postdoctoral years the temperature limits of hot nuclei. In 1990, he participated in a new heavy ion collision program at Brookhaven to produce some very dense nuclear matter like that of neutron stars. In 1995, he joined CERN’s NA50 experiment to produce a deconfined phase of quarks and gluons present in our primordial universe. From 2000 to 2009, he engaged his group in the characterization of the primordial plasma with the PHENIX experiment at the RHIC. In 2006, he took part in the construction phase of the T2K near detectors and measured the first muon neutrino beams delivered at the end of 2009, followed in 2013 by the appearance of electron neutrinos that paves the way for CP violation measurements. More recently, he joined in 2016 with his team the Super-Kamiokande experiment for a original and ambitious cosmology program thanks to the addition of gadolinium in the water tank.
Takaaki Kajita is a Japanese physicist known for his important contributions to neutrino experiments. He has been involved in neutrino physics research since his days as graduate student, participating in the original Kamiokande project and in the construction and operation of Super-Kamiokande. In 2015, he received the Nobel Prize in Physics.
He studied physics at Saitama University and graduated in 1981. He received his doctorate in 1986 from the University of Tokyo, where he joined the research group of Masatoshi Koshiba. Since 1988, Takaaki Kajita has worked at the Institute for Cosmic Radiation Research at the University of Tokyo, where he became an associate professor in 1992 and professor in 1999. He became director of the Institute for Cosmic Ray Research in 2008. Since 2007, he is Principal Investigator at the Institute for the Physics and Mathematics of the Universe in Tokyo. He is currently the principal investigator of the KAGRA gravitational wave project at Kamioka. On October 1 2020, he becomes president of the Scientific Council of Japan.
In 1996, the Super-Kamiokande experiment began its data collection with Takaaki Kajita as head of atmospheric neutrino studies. In 1998, Kajita’s team discovered that when cosmic rays hit Earth’s atmosphere, the resulting neutrinos switched between two flavours before reaching the underground detector, if they came from the other side of the Earth. This discovery made it possible to prove the existence of the flavours quantum oscillation of neutrinos and that neutrinos have mass. In 2015, Takaaki Kajita shared the Nobel Prize in Physics with Canadian physicist Arthur McDonald, whose Sudbury Neutrino Observatory discovered similar results. The works of Kajita and McDonald solved the long-standing problems of solar and atmospheric neutrinos, which were major discrepancies between predicted and measured neutrino fluxes, and indicated that the Standard Model, which required neutrinos to be massless, had weaknesses. Their discovery changed our understanding of the innermost workings of matter and became essential to our view of the universe.