Prize Recipient

Recipient Picture

Kimio Niwa
Nagoya University


"For the first direct observation of the tau neutrino through its charged-current interactions in an emulsion detector."


Education and Main positions held: Shinshu Univ., Arts and Sciences, Sc.B., 1969 Nagoya Univ., Physics, M.Sc. 1972 Nagoya Univ., Physics, D.Sc. 1976 Researcher, Toyota Physical and Chemical Research Institute, 1977 Assistant Professor, Nagoya University, 1978-1986 Associate Professor, Nagoya University, 1987-1995 Professor, Nagoya University, 1996-2009 Professor Emeritus, Nagoya University, 2010-Present Research history and the achievement: 1972 Started research on X particles (charm particles) under the guidance of Professor Kiyoshi Niu. Started the development of automated nuclear emulsion read-out systems. Practical application of semi-automated system. Propose the basic principle of fully automated system (70's) Instructed Torii, Aoki and others to develop the world's first automated emulsion read-out system (80’s) After that, Toshiyuki Nakano realized the ultra-high-speed systems, which led to the realization of large-scale neutrino experiments (from 90’s) and the discovery of an unknown big void in the pyramid (2017), leading to various developments using the current nuclear emulsion technology. 1978: Devised nuclear emulsion-counter hybrid experimental technology and researched charm particles using neutrinos (Fermilab E531). After that, this hybrid emulsion technology was applied to beauty particle research (CERN WA75, Fermilab E653, etc.) and neutrino research (CHORUS, DONUT, OPERA, etc.). 1986: Set the world's first upper limit to the direct coupling of muon neutrinos to tau particles and the oscillation from muon neutrinos to tau neutrinos (Fermilab E531). 1988~92: Conducted research on double hypernucleus / H dibaryon (KEK / E176) using hybrid emulsion technology. Representative of Nagoya University Group. 1991: World's first successful detection of identified double hypernucleus. 1990: Organized a short baseline neutrino oscillation experiment to explore the potential of neutrinos as a candidate for dark matter (CERN WA95 CHORUS). Representative of Japanese researchers. 1998: Updated the upper limit of oscillation from muon neutrino to tau neutrino. 1993: Detected full leptonic decay of Ds mesons (CERN WA75). Suggested that the decay of Ds mesons into tau neutrinos has a significant value, and made the direct detection of tau neutrinos in beam dump experiments realistic. 1994: Organized a beam dump experiment to detect tau neutrinos and study their properties (Fermilab E872 DONUT). Representative of Japanese Group 1998: Successful detection of the world's first tau neutrino interaction (first event). 2000: Detection of four clear tau neutrino interactions among 203 neutrino interactions. 1999: Organization of long baseline neutrino oscillation experiment based on the results of CHORUS, DONUT and Kamioka (deficit of atmospheric muon neutrinos) (CERN / LNGS CNGS1 OPERA)、Co-Spokesman. 2010: Detection of the first tau neutrino event that appears by the neutrino oscillation. 2015: Established the existence of neutrino oscillation phenomena by the detection of tau neutrino appearance. (detection of fifth event). 2004: Received the Nishina Memorial Prize for the Discovery of the tau neutrino by fully automatized scanning device for nuclear emulsion. 2020: Received the Bruno Pontecorvo Prize for the development of the high-resolution nuclear emulsion technique, which led to the identification of the tau neutrino and direct observation of tau neutrino oscillations.

Selection Committee:

Kam-Biu Luk (University of California at Berkeley), James Hirschauer (Fermilab), Edward Kearns (Boston University), Jeffrey McMahon (University of Chicago), Bing Zhou (University of Michigan at Ann Arbor)