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Julius Ashkin (August 23, 1920 – June 4, 1982) was a leader in experimental and theoretical physics known for furthering the evolution of particle physics from nuclear physics. As a theoretical physicist he made contributions in the fields of statistical mechanics, solid state physics, nuclear physics, and Particle physics. As an experimental physicist his main contributions concerned the passage of certain particles (pi-mesons, or ) through solid matter and their subsequent decay. He was recognized for the quality of his research and teaching.
: accessed December 23, 2013), Isadore Ashkin, Brooklyn (Districts 1251–1500), Kings, New York, United States; citing enumeration district (ED) 1261, sheet , family 298, NARA microfilm publication."United States World War I Draft Registration Cards, 1917–1918,"
: accessed December 23, 2013), Isadore Ashkin, 1917–1918; citing New York City no 86, New York, United States, NARA microfilm publication M1509, (Washington D.C.: National Archives and Records Administration, n.d); FHL microfilm 001765586."United States World War II Draft Registration Cards, 1942,"
: accessed December 23, 2013), Isadore Ashkin, 1942."United States Census, 1920,"
: accessed December 23, 2013), Isdor Ashkin, Brooklyn Assembly District 18, Kings, New York, United States; citing sheet , family 342, NARA microfilm publication T625, FHL microfilm 1821173. Within a decade of his landing in New York, Isadore had become a U.S. citizen and was running a dental laboratory at 139 Delancey Street in Manhattan. Ashkin's nickname was Julie. He is the uncle of the artist Michael Ashkin.
Physicists then working on Columbia's faculty in those years included professors Enrico Fermi, Isidor Isaac Rabi, Hans Bethe (visiting), Edward Teller (visiting), and instructors Arnold Nordsieck, Hugh Paxton, and Willis Lamb. All these men were recognized as among the finest of their generation and four of them — Fermi, Rabi, Bethe, and Lamb — were to be awarded the Nobel Prize.
As an undergraduate, Ashkin was invited to join an honorary mathematics society, and received awards. He entered the fall semester as an assistant lecturer and began work toward a master's degree. A year later, having received that degree, he began work toward a Ph.D. under the supervision of Willis Lamb. As a graduate student, Ashkin contributed to one paper in astrophysics. and two papers in statistical mechanics He collaborated with Lamb in writing the first of the two papers on statistical mechanics and with Teller in writing the second. This second paper, "Statistics of Two-Dimensional Lattices with Four Components" has since been frequently cited. He received his Ph.D. in physics in 1943.
Although Ashkin's interest, experience, and skill would seem to place him with the theoretical division, he worked in the physics division in a group called "Nuclear Physics — Experimental." His placement in this group suggests that Ashkin had prior experience in carrying out nuclear experiments while a student at Columbia. With the other members of the group — Feld, Szilard, Robert F. Christy, Herbert E. Kubitschek, and Seymour Bernstein (untraced) — Ashkin produced a number of technical reports on the theoretical aspects of nuclear fission. With Feld, he also produced a practical report on Poisoning and Production in a Power Plant which considered the power potential of sustained nuclear reactions as well as the radiation poisoning and other hazards that accompanied them. All these reports were secret when produced and have since been declassified and released.
Security at Los Alamos was very tight by standards of the time. The site was an uninhabited desert location (formerly a private school) whose perimeter was fenced, with guards at the gates. The scientists were permitted outside the facility but there was little available transportation. (Since they were not members of the military, they could not be ordered to comply with military secrecy orders and instead voluntarily agreed to abide by them.) Although urban-raised scientists, like Ashkin, were far from the amusements that cities afford, they were able to find amusing things to do. It helped that some of the married ones were able to bring their wives to live in the town of Los Alamos and thus parties of men and women could get together for social activities. These include such things as hikes of hills and canyons of the surrounding wilderness areas. It's likely Ashkin played outdoor team sports while at Los Alamos. A Met Lab colleague remembered playing touch football with him and Feld on an open space called the midway at the University of Chicago.
Feynman was particularly adept at leavening hard work with light-hearted games. His genius was as much playful as serious. He took pride in deceiving the mail censors, guessing the combinations of safes in which secret files were stored, picking door locks, and teasing the guards (he would depart from the main gate, circle around the perimeter to a hole in the fence, re-enter the facility, and then exit the gate again, thus causing confusion and consternation both.) He also liked to pound his bongo drums, a practice which made those within hearing range grit their teeth but which he believed put him in touch with the spirits of the Indians who formerly inhabited the place. Physicists are known for their love of music, particularly classical music, and their ability to play it. Feynman wasn't unusual in his affection for drumming but his choice of musical genres was atypical as was his lack of skill as a drummer. It appears that the music produced by his friends offended him as much as his relentless noise offended them. When Ashkin played the recorder, Feynman said he was using "an infernally popular wooden tube ... for making noises bearing a one-one correspondence to black dots on a piece of paper -- in imitation to music."
In 1946, before the scientists at Los Alamos dispersed, there was a brief period during which they gave lectures on subjects in which they had expertise. The program was styled the "Los Alamos University" and some junior members of laboratory personnel received college credit for attending them. Ashkin's were on theoretical mechanics. The course description says it covered the dynamics of particles, rigid bodies, elastic media, and fluids using vector analysis, particle dynamics, Lagrange's equations, and Hamilton's equations.
Along with other members of the Feynman team, Ashkin produced technical reports while at Los Alamos. These were classified at the time but have since been made public. One example gives an idea of the work carried out by the group. It is The Calculation of Critical Masses Including the Effects of the Distribution of Neutron Energies, by Feynman, R.P.; Welton, T.A.; Ashkin, J.; Ehrlich, R.; Peshkin, M.; and Reines, F. Report LA-524(Del.) January 21, 1947 (extract from abstract: "Convenient approximate methods are developed for the calculation of critical sizes and multiplication rates of spherical, active cores surrounded by infinite tampers. Special attention is given to those problems arising from the fact that neutrons of different velocities have different properties. The methods consist essentially of approximating the neutron densities at each velocity by fundamental mode shapes for each velocity.")
On July 16, 1945, Ashkin was present at the first-ever explosion of a nuclear bomb at the Trinity test site, Alamogordo. Only a few of the many scientists were permitted to witness this unspeakably dramatic culmination of their work. Ashkin was probably there because of his work on radiation poisoning, begun at Met Lab and probably continued afterward.
In 1950 it was revealed that one of the scientists at Los Alamos, Klaus Fuchs, was providing the Soviet intelligence bureau, NKGB, with secret information about bomb research. Between 1943 and 1946, Fuchs worked at both Columbia and Los Alamos. When the FBI interviewed Bethe and Feynman about their relationship with Fuchs while at Los Alamos, Feynman said Fuchs was quiet, reserved and not inclined to mix with other scientists outside of work. He also said he believed Fuchs was less stand-offish with Ashkin and seemed friendly with him.
While at Rochester, Ashkin was the first scientist to formally recognize the importance of the Feynman diagram. Feynman devised the diagram in 1948 to provide a simple visualization of the mathematical expressions governing the behavior of subatomic particles. Although the diagram and its offshoots were later seen as extremely important tools, Feynman did not give them a theoretical framework nor did he explain how he proposed they be used. Physicists had difficulty in understanding their function, distrusted their simplicity, and were reluctant to give them formal recognition. Feynman later said physicists did not realize the diagram's power and would employ a more complex method created by Julian Schwinger. Ashkin, he said, was the first to break with this pattern: "They somehow or other couldn’t do it. They had to go through this the to believe it. But that's all right. The only person who didn't, the first paper where it was used directly — which I kept looking for, I kept flipping through the Physical Review as it came out — was Ashkin. He'd done some calculation for some experiment, and he said, 'We’ve calculated this using Feynman's rules.' Bloop! There it was in writing! Then gradually more and more people did it."
While he was teaching at the University of Rochester, Ashkin married Claire Ruderman, a biologist studying at the same university. The couple had two daughters, Beth and Laura.
In 1953, with Bethe, his former director of theoretical work in Los Alamos, Ashkin published an article closely related to the work they had then done. This article, "Passage of Radiations Through Matter," summarized the effects of particles and radiation as they passed through solids. In time it became a standard reference for physics experimenters. Using the CIT cyclotron and following on work done by Bethe and Robert E. Marshak, Ashkin conducted experiments to determine the characteristics of a short-lived particle — the pi-meson or pion — that is produced when high energy cosmic ray protons and other cosmic ray components interact with matter in the Earth's atmosphere. Ashkin served as chair of the physics department between 1961 and 1972. After he died, CMU created the Julius Ashkin Teaching Award in his honor.
Ashkin died at Montefiore Hospital in Pittsburgh, Pennslylvania on June 4, 1982, after a lengthy illness.
Sabbatical at CERN
In 1958–1959 Ashkin won a Ford Foundation grant to spend a sabbatical year in Geneva, Switzerland, at CERN, the European Organization for Nuclear Research. There, he became a member of the first group of scientists to use that institution's new 600 MeV synchrocyclotron. Using this particle accelerator he helped to make a significant discovery which confirmed an aspect of the V-A Theory of weak interactions. Supported by a grant from the Guggenheim Foundation, in 1968 he also spent a year as a Fellow at All Souls College, Oxford.
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Categories: 1920 Births, 1982 Deaths, 20th-century American Physicists, People Associated With Cern, Manhattan Project People, University Of Rochester Faculty, Columbia College Alumni, Carnegie Mellon University Faculty, Jewish American Physicists, James Madison High School Alumni, Scientists From Brooklyn, Physicists From New York
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