Thomas John Ypsilantis (; June 24, 1928 – August 16, 2000) was an American

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 ...

of Greek descent. Ypsilantis was known for the co-discovery of the

antiproton The antiproton, , (pronounced ''p-bar'') is the antiparticle of the proton. Antiprotons are stable, but they are typically short-lived, since any collision with a proton will cause both particles to be annihilated in a burst of energy. The exis ...

in 1955, along with

Owen Chamberlain Owen Chamberlain (July 10, 1920 – February 28, 2006) was an American physicist who shared with Emilio Segrè the Nobel Prize in Physics for the discovery of the antiproton, a sub atomic particle, sub-atomic antiparticle. Biography Born i ...

Emilio Segrè Emilio Gino Segrè ( ; ; 1 February 1905 – 22 April 1989) was an Italian-American nuclear physicist and radiochemist who discovered the elements technetium and astatine, and the antiproton, a subatomic antiparticle, for which he was award ...

, and Clyde Wiegand. Following this work, he moved to

CERN The European Organization for Nuclear Research, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in Meyrin, western suburb of Gene ...

to develop

Cherenkov radiation Cherenkov radiation () is electromagnetic radiation emitted when a charged particle (such as an electron) passes through a dielectric medium (such as distilled water) at a speed greater than the phase velocity (speed of propagation of a wavefro ...

detectors for use in

particle physics Particle physics or high-energy physics is the study of Elementary particle, fundamental particles and fundamental interaction, forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the s ...

Biography

Tom Ypsilantis was born in Salt Lake City in 1928. His father was killed by lightning in 1931. He graduated from South High School in 1945, and attended the

University of Utah The University of Utah (the U, U of U, or simply Utah) is a public university, public research university in Salt Lake City, Utah, United States. It was established in 1850 as the University of Deseret (Book of Mormon), Deseret by the General A ...

graduating with a degree in chemistry in 1949. He then attended the

University of California, Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California), is a Public university, public Land-grant university, land-grant research university in Berkeley, California, United States. Founded in 1868 and named after t ...

where he joined the four person team at the Berkeley

Bevatron The Bevatron was a particle accelerator — specifically, a Weak focusing, weak-focusing proton synchrotron — located at Lawrence Berkeley National Laboratory, U.S., which began operations in 1954. The antiproton was discovered there in ...

that observed the first

; this became the subject of his PhD thesis and the two senior members of this team won the

Nobel Prize in Physics The Nobel Prize in Physics () is an annual award given by the Royal Swedish Academy of Sciences for those who have made the most outstanding contributions to mankind in the field of physics. It is one of the five Nobel Prizes established by the ...

in 1959. Ypsilantis was associate professor of physics at the

, and was instrumental in the founding of the Demokritos Research Center in Athens, Greece. In 1969, he went to Geneva to work at

(Centre European Research Nucleaire), where he met Jacques Séguinot. In 1977, Ypsilantis and Séguinot proposed the technique later called the Ring Imaging Cherenkov (RICH) counter. Together with

Tord Ekelöf Tord Johan Carl Ekelöf (born 12 September 1945 in Uppsala, Sweden) is a Swedish professor of particle physics at Uppsala University. Biography Ekelöf is the son of Per Olof Ekelöf and Marianne (Hesser) Ekelöf. He graduated in 1964 from th ...

, they introduced this technique for high-energy physics: the first large-scale application was for the

DELPHI experiment DELPHI (DEtector with Lepton, Photon and Hadron Identification) was one of the four main detectors of the Large Electron–Positron Collider (LEP) at CERN, one of the largest particle accelerators ever made. Like the other three detectors, it reco ...

at LEP. They later worked in the framework of the LAAS Project on noble-liquid

calorimetry In chemistry and thermodynamics, calorimetry () is the science or act of measuring changes in '' state variables'' of a body for the purpose of deriving the heat transfer associated with changes of its state due, for example, to chemical reac ...

and on a very large water

neutrino detector A neutrino detector is a physics apparatus which is designed to study neutrinos. Because neutrinos only weakly interact with other particles of matter, neutrino detectors must be very large to detect a significant number of neutrinos. Neutrino ...

based on the fast-RICH technique. Ypsilantis also made major contributions to the

LHCb experiment The LHCb (Large Hadron Collider beauty) experiment is a particle physics detector collecting data at the Large Hadron Collider at CERN. LHCb specializes in the measurements of the parameters of CP violation in the interactions of b- and c-hadron ...

at CERN. He served as the Senior Research Director in Geneva, Project Director in

Bologna Bologna ( , , ; ; ) is the capital and largest city of the Emilia-Romagna region in northern Italy. It is the List of cities in Italy, seventh most populous city in Italy, with about 400,000 inhabitants and 150 different nationalities. Its M ...

, Italy, and Consultant to the French Nuclear Agency in Saclay, France.

References

External links

obituary
1928 births 2000 deaths Scientists from Salt Lake City University of Utah alumni University of California, Berkeley alumni 20th-century American physicists American particle physicists American people of Greek descent People associated with CERN Fellows of the American Physical Society {{US-physicist-stub