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was a Japanese physicist and one of the founders of neutrino astronomy. His work with the neutrino detectors
Kamiokande The is a neutrino and gravitational waves 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 experimen ...
and Super-Kamiokande was instrumental in detecting
solar neutrinos A solar neutrino is a neutrino originating from nuclear fusion in the Sun's core, and is the most common type of neutrino passing through any source observed on Earth at any particular moment. Neutrinos are elementary particles with extremely smal ...
, providing experimental evidence for the
solar neutrino problem The solar neutrino problem concerned a large discrepancy between the flux of solar neutrinos as predicted from the Sun's luminosity and as measured directly. The discrepancy was first observed in the mid-1960s and was resolved around 2002. The fl ...
. Koshiba won the Nobel Prize in Physics in 2002 (jointly with
Raymond Davis Jr. Raymond Davis Jr. (October 14, 1914 – May 31, 2006) was an American chemist and physicist. He is best known as the leader of the Homestake experiment in the 1960s-1980s, which was the first experiment to detect neutrinos emitted from the Sun; f ...
) "for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos". He was a senior counselor at the
International Center for Elementary Particle Physics The is a division of the University of Tokyo, Japan dedicated to the study of particle physics. The ICEPP is located on the 10th floor of the Faculty of Science Building #1 at the University of Tokyo , abbreviated as or UTokyo, is a public res ...
(ICEPP) and professor at the University of Tokyo.


Early life

Koshiba was born in Toyohashi in central Japan on September 19, 1926, to Toshio and Hayako Koshiba. His father was a military officer. His mother died when he was three, leading to his father marrying his wife's elder sister. He grew up in Yokosuka, and completed his high school in
Tokyo Tokyo (; ja, 東京, , ), officially the Tokyo Metropolis ( ja, 東京都, label=none, ), is the capital and largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, with an estimated 37.46 ...
. It is mentioned that his initial interest was in studying German literature, but, ended up studying physics, spurred by a teacher's denigrating comments. He graduated from the University of Tokyo in 1951 and received a
PhD PHD or PhD may refer to: * Doctor of Philosophy (PhD), an academic qualification Entertainment * '' PhD: Phantasy Degree'', a Korean comic series * '' Piled Higher and Deeper'', a web comic * Ph.D. (band), a 1980s British group ** Ph.D. (Ph.D. al ...
in physics from the
University of Rochester The University of Rochester (U of R, UR, or U of Rochester) is a private research university in Rochester, New York. The university grants undergraduate and graduate degrees, including doctoral and professional degrees. The University of ...
, New York, in 1955.


Career and research

Koshiba started his career as a research associate at the Department of Physics, University of Chicago from July 1955 to February 1958, and was an associate professor at Institute of Nuclear Study, University of Tokyo from March 1958 to October 1963. While on leave from November 1959 to August 1962 he served as the acting director, Laboratory of High Energy Physics and Cosmic Radiation, Department of Physics, University of Chicago. At the University of Tokyo he became associate professor in March 1963 and then professor in March 1970 in the Department of Physics, Faculty of Science, and emeritus professor there in 1987. From 1987 to 1997, Koshiba taught at Tokai University. In 2002, he jointly won the Nobel Prize in Physics for "pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos". (The other shares of that year's Prize were awarded to
Raymond Davis Jr. Raymond Davis Jr. (October 14, 1914 – May 31, 2006) was an American chemist and physicist. He is best known as the leader of the Homestake experiment in the 1960s-1980s, which was the first experiment to detect neutrinos emitted from the Sun; f ...
and
Riccardo Giacconi Riccardo Giacconi ( , ; October 6, 1931 – December 9, 2018) was an Italian-American Nobel Prize-winning astrophysicist who laid down the foundations of X-ray astronomy. He was a professor at the Johns Hopkins University. Biography Born ...
of the U.S.A.) Koshiba's initial research was in cosmic rays. In 1969, he shifted into electron-positron collider physics, and was involved with the JADE detector in Germany, which helped confirm the Standard Model. Along with Masayuki Nakahata and Atsuto Suzuki, Koshiba designed the
Kamiokande The is a neutrino and gravitational waves 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 experimen ...
experiment to detect proton decay, a prediction of
grand unified theories A Grand Unified Theory (GUT) is a model in particle physics in which, at high energies, the three gauge interactions of the Standard Model comprising the electromagnetic, weak, and strong forces are merged into a single force. Although this ...
. No proton decay was detected, but Koshiba realized the detector could be made to detect neutrinos, and adapted the project accordingly, following the pioneering U.S. work of Davis. In the early 1970s, Koshiba collaborated with Gersh Budker (1918-1977), the particle-accelerator
electron cooling Electron cooling is a method to shrink the emittance (size, divergence, and energy spread) of a charged particle beam without removing particles from the beam. Since the number of particles remains unchanged and the space coordinates and their der ...
pioneer in the Soviet Union. This collaboration was cut short for unknown reasons but Budker died of heart attack a few years later. Through this experiment, he (and Davis in the U.S.) were able to confirm the prediction that neutrinos are generated during the nuclear fusion reaction in the sun. However, these experiments detected fewer neutrinos than had been expected. This deficit was called the
solar neutrino problem The solar neutrino problem concerned a large discrepancy between the flux of solar neutrinos as predicted from the Sun's luminosity and as measured directly. The discrepancy was first observed in the mid-1960s and was resolved around 2002. The fl ...
. The deficit would be eventually explained by "neutrino oscillations", whose existence was confirmed by an enlarged version of Kamiokande, known as Super-Kamiokande, run under the direction of Koshiba's student Takaaki Kajita. In 1987, the Kamiokande experimental detector detected neutrinos from the supernova explosion (designated
SN 1987A SN 1987A was a type II supernova in the Large Magellanic Cloud, a dwarf satellite galaxy of the Milky Way. It occurred approximately from Earth and was the closest observed supernova since Kepler's Supernova. 1987A's light reached Earth on ...
) outside the Milky Way, the Large Magellanic Cloud. His research was pioneering in the establishment of neutrino astronomy as a field of study. In 1996, with the promising results from Kamiokande, the team operationalized a larger and more sensitive detector called Super-Kamiokande. With this detector, scientists was able to demonstrate strong evidence to prove that neutrinos changed from one type to another of three types during flight. This demonstration resolved the solar neutrino problem with the reasoning being that the early detectors could detect one type of neutrino rather than all three types. Koshiba was a member of the Board of Sponsors of the '' Bulletin of the Atomic Scientists'', and also a foreign fellow of
Bangladesh Academy of Sciences Bangladesh Academy of Sciences is an academic forum for Bangladeshi scientists and technologists. Established in 1973, it aims to fulfill the role of promoting research and development of sciences in Bangladesh. History After the partition of ...
. He was a founding member of the Edogawa NICHE Prize Steering committee.


Personal life

Koshiba married Kyoto Kato, an art museum curator, when he returned to Japan in the late 1950s. The couple had a son and a daughter. He died on November 12, 2020, at the Edogawa Hospital in Tokyo at the age of 94.


Awards

Source(s): *1987 –
Asahi Prize The , established in 1929, is an award presented by the Japanese newspaper ''Asahi Shimbun'' and Asahi Shimbun Foundation to honor individuals and groups that have made outstanding accomplishments in the fields of arts and academics and have greatl ...
*1987 – Nishina Memorial Prize *1997 – Humboldt Prize *2000 –
Wolf Prize in Physics The Wolf Prize in Physics is awarded once a year by the Wolf Foundation in Israel. It is one of the six Wolf Prizes established by the Foundation and awarded since 1978; the others are in Agriculture, Chemistry, Mathematics, Medicine and Arts ...
*2002 – Nobel Prize in Physics *2002 – Panofsky Prize *2003 – Benjamin Franklin Medal in Physics


Honors

Source(s): *1985 – Order of Merit of the Federal Republic of Germany *1997 – Order of Culture *2002 – Honorary citizenship of
Suginami is a Special wards of Tokyo, special ward in Tokyo, Japan. The ward refers to itself as Suginami City in English. As of June 1, 2022, Suginami has an estimated population of 588,354 and a population density of 17,274 persons per km2. The total ...
*2002 – Honorary doctor of Meiji University *2002 – Elected Fellow of the American Physical Society. *2003 – Grand Cordon of the Order of the Rising Sun *2003 – In commemoration of the
Nobel Prize The Nobel Prizes ( ; sv, Nobelpriset ; no, Nobelprisen ) are five separate prizes that, according to Alfred Nobel's will of 1895, are awarded to "those who, during the preceding year, have conferred the greatest benefit to humankind." Alfr ...
-winning by Masatoshi Koshiba, ''Koshiba'' hall was established at the University of Tokyo's School of science.寺崎昌男 2007 『東京大学の歴史 大学制度の先駆け』 講談社 *2003 – Honorary citizenship of
Tokyo Tokyo (; ja, 東京, , ), officially the Tokyo Metropolis ( ja, 東京都, label=none, ), is the capital and largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, with an estimated 37.46 ...
*2003 – Emeritus Professor of the University of Tokyo


Publications

* *


See also

*
Institute for Cosmic Ray Research The Institute for Cosmic Ray Research (ICRR) of the University of Tokyo (東京大学宇宙線研究所 ''Tōkyōdaigaku Uchūsen Kenkyūsho'') was established in 1976 for the study of cosmic rays. The gravitational wave studies group is currentl ...
*
Kamioka Observatory The is a neutrino and gravitational waves 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 experim ...
* List of Japanese Nobel laureates * List of Nobel Laureates affiliated with the University of Rochester * List of Nobel laureates affiliated with the University of Tokyo *
University of Rochester The University of Rochester (U of R, UR, or U of Rochester) is a private research university in Rochester, New York. The university grants undergraduate and graduate degrees, including doctoral and professional degrees. The University of ...


References


External links


Prof. Koshiba has won the Nobel prize.
* including the Nobel Lecture December 8, 2002 ''Birth of Neutrino Astrophysics'' *
Freeview video 'An Interview with Masatoshi Koshiba' by the Vega Science Trust
{{DEFAULTSORT:Koshiba, Masatoshi 1926 births 2020 deaths Japanese Nobel laureates Japanese physicists Nobel laureates in Physics People from Toyohashi University of Chicago faculty University of Tokyo faculty University of Tokyo alumni University of Rochester alumni Tokai University faculty Wolf Prize in Physics laureates Fellows of Bangladesh Academy of Sciences Foreign Members of the Russian Academy of Sciences Foreign associates of the National Academy of Sciences Commanders Crosses of the Order of Merit of the Federal Republic of Germany Recipients of the Order of Culture Recipients of the Order of the Rising Sun Winners of the Panofsky Prize Fellows of the American Physical Society