was a Japanese
physicist
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe.
Physicists generally are interested in the root or ultimate cau ...
and one of the founders of
neutrino astronomy
Neutrino astronomy is the branch of astronomy that observes astronomical objects with neutrino detectors in special observatories. Neutrinos are created as a result of certain types of radioactive decay, nuclear reactions such as those that take ...
. 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 experim ...
and
Super-Kamiokande
Super-Kamiokande (abbreviation of Super-Kamioka Neutrino Detection Experiment, also abbreviated to Super-K or SK; ja, スーパーカミオカンデ) is a Neutrino detector, neutrino observatory located Kamioka Observatory, under Mount Ikeno ...
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
)
, image = Nobel Prize.png
, alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then " ...
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; ...
) "for pioneering contributions to astrophysics, in particular for the detection of cosmic
neutrino
A neutrino ( ; denoted by the Greek letter ) is a fermion (an elementary particle with spin of ) that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass ...
s".
He was a senior counselor at the
International Center for Elementary Particle Physics (ICEPP) and
professor
Professor (commonly abbreviated as Prof.) is an academic rank at universities and other post-secondary education and research institutions in most countries. Literally, ''professor'' derives from Latin as a "person who professes". Professors ...
at the University of Tokyo.
Early life
Koshiba was born in
Toyohashi
is a city in Aichi Prefecture, Japan. , the city had an estimated population of 377,453 in 160,516 households and a population density of 1,400 persons per km2. The total area of the city was . By area, Toyohashi was Aichi Prefecture's second-lar ...
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
is a city in Kanagawa Prefecture, Japan.
, the city has a population of 409,478, and a population density of . The total area is . Yokosuka is the 11th most populous city in the Greater Tokyo Area, and the 12th in the Kantō region.
The city ...
, 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 List of cities in Japan, largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, ...
. 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
, abbreviated as or UTokyo, is a public research university located in Bunkyō, Tokyo, Japan. Established in 1877, the university was the first Imperial University and is currently a Top Type university of the Top Global University Project b ...
in 1951 and received a
PhD in physics from the
University of Rochester
The University of Rochester (U of R, UR, or U of Rochester) is a private university, private research university in Rochester, New York. The university grants Undergraduate education, undergraduate and graduate degrees, including Doctorate, do ...
, New York, in 1955.
Career and research
![Masatoshi Koshiba and Junichiro Koizumi 20030827](https://upload.wikimedia.org/wikipedia/commons/6/6a/Masatoshi_Koshiba_and_Junichiro_Koizumi_20030827.jpg)
Koshiba started his career as a research associate at the Department of Physics,
University of Chicago
The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private university, private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park, Chicago, Hyde Park neighborhood. The University of Chic ...
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
is a private non-sectarian higher education institution located in Tokyo, Japan. It was founded by Dr. Shigeyoshi Matsumae.
It was accredited under Japan's old educational system in 1946 and under the new system in 1950. In 2008, Tokai Un ...
.
In 2002, he jointly won the
Nobel Prize in Physics
)
, image = Nobel Prize.png
, alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then " ...
for "pioneering contributions to
astrophysics, in particular for the detection of cosmic
neutrino
A neutrino ( ; denoted by the Greek letter ) is a fermion (an elementary particle with spin of ) that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass ...
s". (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; ...
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 in ...
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 experim ...
experiment to detect
proton decay
In particle physics, proton decay is a hypothetical form of particle decay in which the proton decays into lighter subatomic particles, such as a neutral pion and a positron. The proton decay hypothesis was first formulated by Andrei Sakharov ...
, 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 u ...
. 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
Super-Kamiokande (abbreviation of Super-Kamioka Neutrino Detection Experiment, also abbreviated to Super-K or SK; ja, スーパーカミオカンデ) is a Neutrino detector, neutrino observatory located Kamioka Observatory, under Mount Ikeno ...
, run under the direction of Koshiba's student
Takaaki Kajita
is a Japanese physicist, known for neutrino experiments at the Kamioka Observatory – Kamiokande and its successor, Super-Kamiokande. In 2015, he was awarded the Nobel Prize in Physics jointly with Canadian physicist Arthur B. McDonald. On 1 ...
.
[
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 Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...
, the Large Magellanic Cloud. His research was pioneering in the establishment of neutrino astronomy
Neutrino astronomy is the branch of astronomy that observes astronomical objects with neutrino detectors in special observatories. Neutrinos are created as a result of certain types of radioactive decay, nuclear reactions such as those that take ...
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
Super-Kamiokande (abbreviation of Super-Kamioka Neutrino Detection Experiment, also abbreviated to Super-K or SK; ja, スーパーカミオカンデ) is a Neutrino detector, neutrino observatory located Kamioka Observatory, under Mount Ikeno ...
. 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
The ''Bulletin of the Atomic Scientists'' is a nonprofit organization concerning science and global security issues resulting from accelerating technological advances that have negative consequences for humanity. The ''Bulletin'' publishes conte ...
'', 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
The is the oldest and most prestigious physics award in Japan.
Information
Since 1955, the Nishina Memorial Prize has been awarded annually by the Nishina Memorial Foundation. The Foundation was established to commemorate Yoshio Nishina, who w ...
*1997 – Humboldt Prize
The Humboldt Prize, the Humboldt-Forschungspreis in German, also known as the Humboldt Research Award, is an award given by the Alexander von Humboldt Foundation of Germany to internationally renowned scientists and scholars who work outside of G ...
*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
)
, image = Nobel Prize.png
, alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then " ...
*2002 – Panofsky Prize
The Panofsky Prize in Experimental Particle Physics is an annual prize of the American Physical Society. It is given to recognize and encourage outstanding achievements in experimental particle physics, and is open to scientists of any nation. It w ...
*2003 – Benjamin Franklin Medal in Physics
Honors
Source(s):
*1985 – Order of Merit of the Federal Republic of Germany
The Order of Merit of the Federal Republic of Germany (german: Verdienstorden der Bundesrepublik Deutschland, or , BVO) is the only federal decoration of Germany. It is awarded for special achievements in political, economic, cultural, intellect ...
*1997 – Order of Culture
The 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, science, technology, or anything related to culture in general; recipient ...
*2002 – Honorary citizenship of Suginami
*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
, abbreviated as or UTokyo, is a public research university located in Bunkyō, Tokyo, Japan. Established in 1877, the university was the first Imperial University and is currently a Top Type university of the Top Global University Project b ...
'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 List of cities in Japan, largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, ...
*2003 – Emeritus Professor
''Emeritus'' (; female: ''emerita'') is an adjective used to designate a retired chair, professor, pastor, bishop, pope, director, president, prime minister, rabbi, emperor, or other person who has been "permitted to retain as an honorary title ...
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 currently ...
* 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
Since 1949, there have been 29 Japanese List of Nobel laureates, laureates of the Nobel Prize. The Nobel Prize is a Sweden-based international monetary prize. The award was established by the 1895 will and estate of Swedish chemist and inventor ...
* List of Nobel Laureates affiliated with the University of Rochester
* List of Nobel laureates affiliated with the University of Tokyo
This list of Nobel laureates by university affiliation shows the university affiliations of individual winners of the Nobel Prize since 1901 and the Nobel Memorial Prize in Economic Sciences since 1969. The affiliations are those at the time of th ...
* University of Rochester
The University of Rochester (U of R, UR, or U of Rochester) is a private university, private research university in Rochester, New York. The university grants Undergraduate education, undergraduate and graduate degrees, including Doctorate, do ...
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