Yoji Totsuka
Encyclopedia
was a Japanese
physicist and Special University Professor, Emeritus, University of Tokyo
. Totsuka died on July 10, 2008 from colorectal cancer
.
.
(DESY) in Germany, where he investigated electron–positron collisions. Subsequently, he became an Associate Professor of the University of Tokyo from 1979 to 1987. In 1987, he was promoted to full Professor at the University of Tokyo. He later became the Director of the Kamioka Observatory
, part of the Institute for Cosmic Ray Research
(ICRR) at the University of Tokyo in 1995 and then Director of the Institute for Cosmic Ray Research in 1997. In 2003, Totsuka became the Director General of the High Energy Accelerator Research Organization
(KEK).
physics began following his time at DESY, when he began working as part of the Kamiokande experiment
with Nobel prize winner Masatoshi Koshiba
. The experiment, though designed to detect proton decay
, actually ended up successfully measuring the first and so far only neutrinos from a cosmogenic source on Earth, from SN 1987A
, along with the Irvine–Michigan–Brookhaven (IMB) detector in the US.
The success of Kamiokande, through Totsuka's leadership, led to the funding of a substantially larger water
Cherenkov detector
in 1991, the storied Super-Kamiokande
(Super-K) detector, which is still an active international collaboration. It was at Super-K that the first definitive evidence for neutrino oscillations was measured, via a high-statistics, high-precision measurement of the atmospheric neutrino flux. Super-K also confirmed, along with the Sudbury Neutrino Observatory
(SNO), the solution to the solar neutrino problem
.
The measurement of neutrino oscillations at such a high level of precision was a critical chapter in the history of particle physics. Neutrino oscillations, and thus the existence of neutrino mass, are not a prediction made by the Standard Model
of particle physics. Indeed, the Standard Model requires that neutrinos are massless. Totsuka's experiment provided incontrovertible evidence that there is still much about particle physics yet to be understood.
For the remainder of his time as a physicist, as the Director General at KEK, he oversaw successful the K2K experiment
and the Belle
B-meson "factory"
.
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
physicist and Special University Professor, Emeritus, University of Tokyo
University of Tokyo
, abbreviated as , is a major research university located in Tokyo, Japan. The University has 10 faculties with a total of around 30,000 students, 2,100 of whom are foreign. Its five campuses are in Hongō, Komaba, Kashiwa, Shirokane and Nakano. It is considered to be the most prestigious university...
. Totsuka died on July 10, 2008 from colorectal cancer
Colorectal cancer
Colorectal cancer, commonly known as bowel cancer, is a cancer caused by uncontrolled cell growth , in the colon, rectum, or vermiform appendix. Colorectal cancer is clinically distinct from anal cancer, which affects the anus....
.
Early life
Totsuka was born March 6, 1942 in Fuji, Shizuoka Prefecture. He completed his B.S. in 1965, his M.S. in 1967 and his Ph.D. in 1972 from the University of TokyoUniversity of Tokyo
, abbreviated as , is a major research university located in Tokyo, Japan. The University has 10 faculties with a total of around 30,000 students, 2,100 of whom are foreign. Its five campuses are in Hongō, Komaba, Kashiwa, Shirokane and Nakano. It is considered to be the most prestigious university...
.
Academic career
Totsuka became a Research Associate at the University of Tokyo in 1972, followed by seven years at Deutsches Electron SynchrotronDESY
The DESY is the biggest German research center for particle physics, with sites in Hamburg and Zeuthen....
(DESY) in Germany, where he investigated electron–positron collisions. Subsequently, he became an Associate Professor of the University of Tokyo from 1979 to 1987. In 1987, he was promoted to full Professor at the University of Tokyo. He later became the Director of the Kamioka Observatory
Kamioka Observatory
The is a neutrino physics laboratory located underground in the Mozumi Mine of the Kamioka Mining and Smelting Co. near the Kamioka section of the city of Hida in Gifu Prefecture, Japan. A set of groundbreaking neutrino experiments have taken place at the observatory over the past two decades...
, part of the Institute for Cosmic Ray Research
Institute for Cosmic Ray Research
The Institute for Cosmic Ray Research of the University of Tokyo was established in 1976 for the study of cosmic rays....
(ICRR) at the University of Tokyo in 1995 and then Director of the Institute for Cosmic Ray Research in 1997. In 2003, Totsuka became the Director General of the High Energy Accelerator Research Organization
KEK
, known as KEK, is a national organization whose purpose is to operate the largest particle physics laboratory in Japan, which is situated in Tsukuba of Ibaraki prefecture. Established in 1997. The term "KEK" is also used to refer to the laboratory itself, which employs approximately 900 employees...
(KEK).
Research
Totsuka's career in neutrinoNeutrino
A neutrino is an electrically neutral, weakly interacting elementary subatomic particle with a half-integer spin, chirality and a disputed but small non-zero mass. It is able to pass through ordinary matter almost unaffected...
physics began following his time at DESY, when he began working as part of the Kamiokande experiment
Kamioka Observatory
The is a neutrino physics laboratory located underground in the Mozumi Mine of the Kamioka Mining and Smelting Co. near the Kamioka section of the city of Hida in Gifu Prefecture, Japan. A set of groundbreaking neutrino experiments have taken place at the observatory over the past two decades...
with Nobel prize winner Masatoshi Koshiba
Masatoshi Koshiba
is a Japanese physicist. He jointly won the Nobel Prize in Physics in 2002.He graduated from the University of Tokyo in 1951 and received a Ph.D. in physics at the University of Rochester, New York, in 1955...
. The experiment, though designed to detect proton decay
Proton decay
In particle physics, proton decay is a hypothetical form of radioactive decay in which the proton decays into lighter subatomic particles, such as a neutral pion and a positron...
, actually ended up successfully measuring the first and so far only neutrinos from a cosmogenic source on Earth, from SN 1987A
SN 1987A
SN 1987A was a supernova in the outskirts of the Tarantula Nebula in the Large Magellanic Cloud, a nearby dwarf galaxy. It occurred approximately 51.4 kiloparsecs from Earth, approximately 168,000 light-years, close enough that it was visible to the naked eye. It could be seen from the Southern...
, along with the Irvine–Michigan–Brookhaven (IMB) detector in the US.
The success of Kamiokande, through Totsuka's leadership, led to the funding of a substantially larger water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
Cherenkov detector
Cherenkov detector
A Cherenkov detector is a particle detector using the mass-dependent threshold energy of Cherenkov radiation. This allows a discrimination between a lighter particle and a heavier particle ....
in 1991, the storied Super-Kamiokande
Super-Kamiokande
Super-Kamiokande is a neutrino observatory which is under Mount Kamioka near the city of Hida, Gifu Prefecture, Japan...
(Super-K) detector, which is still an active international collaboration. It was at Super-K that the first definitive evidence for neutrino oscillations was measured, via a high-statistics, high-precision measurement of the atmospheric neutrino flux. Super-K also confirmed, along with the Sudbury Neutrino Observatory
Sudbury Neutrino Observatory
The Sudbury Neutrino Observatory is a neutrino observatory located 6,800 feet underground in Vale Inco's Creighton Mine in Sudbury, Ontario, Canada. The detector was designed to detect solar neutrinos through their interactions with a large tank of heavy water. The detector turned on in May 1999,...
(SNO), the solution to the solar neutrino problem
Solar neutrino problem
The solar neutrino problem was a major discrepancy between measurements of the numbers of neutrinos flowing through the Earth and theoretical models of the solar interior, lasting from the mid-1960s to about 2002...
.
The measurement of neutrino oscillations at such a high level of precision was a critical chapter in the history of particle physics. Neutrino oscillations, and thus the existence of neutrino mass, are not a prediction made by the Standard Model
Standard Model
The Standard Model of particle physics is a theory concerning the electromagnetic, weak, and strong nuclear interactions, which mediate the dynamics of the known subatomic particles. Developed throughout the mid to late 20th century, the current formulation was finalized in the mid 1970s upon...
of particle physics. Indeed, the Standard Model requires that neutrinos are massless. Totsuka's experiment provided incontrovertible evidence that there is still much about particle physics yet to be understood.
For the remainder of his time as a physicist, as the Director General at KEK, he oversaw successful the K2K experiment
K2K experiment
The K2K experiment was a neutrino experiment that ran from June 1999 to November 2004. It used muon neutrinos from a well-controlled and well-understood beam to verify the oscillations previously observed by Super-Kamiokande using atmospheric neutrinos...
and the Belle
Belle experiment
The Belle experiment is a particle physics experiment conducted by the Belle Collaboration, an international collaboration of more than 400 physicists and engineers investigating CP-violation effects at the High Energy Accelerator Research Organisation in Tsukuba, Ibaraki Prefecture, Japan.The...
B-meson "factory"
B-Factory
In particle physics, a B-factory, or sometimes a beauty factory, is a collider-based scientific machine designed to produce a large number of B mesons and analyze their properties. The tauons and D mesons are also copiously produced at B-factories, which allows precise studies of their...
.
Personal life
When he left physics, towards the end of his life, Totsuka turned his attention to communicating with the Japanese public about his illness, science, and culture. He maintained a blog, The Fourth Three-Months, where he candidly discussed the extent, progress, and treatment of his cancer. Totsuka also revealed an interest in gardening, particularly the flowers in the area where he spent much of his career, in Mozumi, the village where Super-K is located.Awards and honors
- Asahi PrizeAsahi PrizeThe Asahi Prize is a prize awarded by the Japanese newspaper the Asahi shimbun for achievement in scholarship or the arts that has made a contribution to culture or society. It was established in 1929. Many recipients of this prize have later been honoured with a Nobel Prize...
, 1987 - Nishina Memorial PrizeNishina Memorial Prizeis the oldest and most prestigious physics award in Japan. Since 1955, the Prize has been awarded annually by the Nishina Memorial Foundation. The Foundation was established to commemorate Yoshio Nishina, who was the founding father of modern physics research in Japan and a mentor of the first two...
, 1988 - Bruno Rossi PrizeBruno Rossi PrizeThe Bruno Rossi Prize is awarded annually by the High Energy Astrophysics division of the American Astronomical Society "for a significant contribution to High Energy Astrophysics, with particular emphasis on recent, original work". Named after astrophysicist Bruno Rossi, the prize is awarded with...
, (American Astronomical SocietyAmerican Astronomical SocietyThe American Astronomical Society is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC...
),1989 - Inoue Prize for Science, 1990
- EPS Special Prize, European Physical SocietyEuropean Physical SocietyThe European Physical Society is a non-profit organization whose purpose is to promote physics and physicists in Europe. Formally established in 1968, its membership includes the national physical societies of 41 countries, and some 3200 individual members. The Deutsche Physikalische Gesellschaft,...
, 1995 - Order of CultureOrder of CultureThe is a Japanese order, established on February 11, 1937. The order has one class only, and may be awarded to men and women for contributions to Japan's art, literature or culture; recipients of the order also receive an annuity for life...
, 2004 - Benjamin Franklin Medal in PhysicsBenjamin Franklin Medal (Franklin Institute)The Benjamin Franklin Medal is a science and engineering award presented by the Franklin Institute, of Philadelphia, PA, USA.-Laureates:*1998 - Emmanuel Desurvire *1998 - Robert B. Laughlin *1998 - David N. Payne...
, 2007