New Research Facilities

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Publication
Physics Today
Publication Date
December 1952
Publisher
American Institute of Physics
Citation
Physics Today 5, 12, 23 (1952)
Abstract

Walter Kidde Nuclear Laboratories The first privately-financed research organization devoted primarily to the development of atomic power for industrial purposes, the Walter Kidde Nuclear Laboratories, has begun research operations at its recently constructed laboratory near Garden City, on Long Island. The new laboratory, housed in a brick structure of modern design, with laboratory area for work in physics, chemistry, metallurgy, radiochemistry, and materials testing, is expected to be in full operation by the latter part of 1953, by which time it is expected that a minimum staff of one hundred will be employed. The stated objectives of the organization are (1) the development of commercial atomic power, with particular emphasis on original research and development in the field of low-cost nuclear reactors, (2) cooperation on a contract basis with government agencies and their contractors in the development and design of atomic facilities, and (3) collaboration with private industrial organizations, laboratories, and others interested in the application of the nuclear sciences to specific problems.

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The Brookhaven nuclear reactor

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Author(s)
Lyle B. Borst
Publication
Physics Today
Publisher
American Institute of Physics
Citation
Physics Today 4, 1, 6 (1951)
Abstract

On August 22, 1950 the Brookhaven reactor became critical. The work of scientists is notable for its lack of drama. It is usually difficult to say when a piece of apparatus starts to work, and it is even more difficult to decide when an experiment is complete. The uranium chain reaction is outstanding, therefore, since the change from an inert subcritical assembly of fissionable material to a supercritical chain reactor is sudden and, to all intents and purposes, discontinuous.

A small lump of uranium undergoes spontaneous fission of U 238 with a half-life at least a million times that for alpha decay. The rate is so slow as to render measurement difficult. By assembling quantities of uranium in a moderator such as heavy water or graphite, the rate of fission is found to vary with the amounts of material used. Upon adding additional materials, the neutron level at a given position and, of course, the fission rate (partly now in U235 ) increase rapidly at first, then slowly, approaching a new constant level. The steady level may be two, ten, or a million times that to be expected from the spontaneous fission rate.

Excerpt(s)

Brookhaven's reactor was designed to support a substantial and diversified research program. Ample facilities are provided for many simultaneous studies.

Most experiments will be conducted at a number of four-inch square experimental holes extending horizontally through the graphite structure and both shields. These are located at table height above the working balconies to permit convenient handling of research equipment. The neutron flux available at each hole will depend largely upon its position with respect to the center of the reactor. One row of these holes will extend through a region of graphite without uranium. The neutron flux in this internal thermal column will be particularly rich in thermal neutrons and relatively depleted of fast fission neutrons.

These experimental ports may be used for the insertion of equipment into the shield, or into the graphite structure. In these experiments fluxes up to 4 X 10 12 neutrons per cm 2 sec. can be obtained. Under normal circumstances the equipment would reach the ambient temperature of the graphite. For experiments requiring temperature control, heating or cooling can be introduced. The simplest coolingarrangement consists of a duct through the shield which will allow room air to leak around the apparatus and into the cooling air stream. Special cooling systems or thermostatic control can be provided if warranted.

Collimators can be inserted into the shield holes permitting a beam of reactor' radiation to emerge. If unfiltered, these beams contain fast, intermediate, and slow neutrons, and also gamma and beta rays. Filters can be devised to enrich the beam with regard to any of these constituents. Beams can be run to a distance of 40 feet within the building, and to much greater distances outside the building.

A single twelve-inch square hole will accommodate large size experimental equipment. Since this constitutes the largest aperture penetrating a high flux reactor, this facility is expected to be in heavy demand. Equipment must therefore be constructed for easy removal.

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The American Physical Society

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Publication
Physics Today
Publication Date
October 1951
Publisher
American Institute of Physics
Citation
Physics Today 4, 10, 18 (1951)
Abstract

THE American Physical Society was founded on May 20, 1899 by a group of about forty physicists who met in a small lecture room in Columbia University's Fayerweather Hall in New York City. The first regular meeting of the Society was held five months later. Before that time, physicists had customarily joined in the annual meetings of the American Association for the Advancement of Science, its Section B being concerned primarily with physics. The formation of an independent Society for the "advancement and diffusion of the knowledge of physics" was only one of a series of events marking the swift development of physics in the history of American science.

When the newly formed American Physical Society joined in the 49th meeting of the AAAS in New York in June, 1900, the Society and the Association's Section B met on alternate days. It was remarked in a contemporary report of the event that although the two programs were kept separate, there was little else to distinguish the groups. The difference, eloquently enough stated by the action of the charter members in forming the new Society, was their conviction that the time had come for a separate professional scientific organization devoted to the advancement of physics. A cooperative and close relationship has nevertheless been maintained between the two organizations, and the Physical Society for many years met frequently in joint session with Section B of the AAAS. At the end of its first year, the Physical Society had a total membership of only fifty-nine; the present membership is nearly ten thousand.

Excerpt(s)

SAMUEL A. GOUDSMIT, senior scientist at Brookhaven National Laboratory, is managing editor of The Physical Review, official journal of the Physical Society.

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Physics at Oak Ridge

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Author(s)
Alvin M. Weinberg
Publication
Physics Today
Publication Date
June 1950
Publisher
American Institute of Physics
Citation
Physics Today 3, 6, 8 (1950)
Abstract

The research effort here in Oak Ridge bears in some measure on almost every phase of the country's atomic energy program. For the laboratory hereunlike the national laboratories at Argonne, Brookhaven, Berkeley, Ames, and Los Alamos—has no single primary function but has many different areas in which it contributes, with about equal emphasis, to the development of atomic energy technology.

The Oak Ridge National Laboratory is large; since the recent merger of the research activities at the electromagnetic plant with those of the original Oak Ridge National Laboratory, nearly 2800 technical and nontechnical people are associated with it. Its activities include, on the applied side, radioactive chemical technology; Oak Ridge National Laboratory was the chemical pilot plant for the Hanford plutonium process. It includes reactor technology; the laboratory is engaged in three separate reactor projects, among which are the materials testing reactor to be built at Arco as a joint project of Argonne and Oak Ridge, and the nuclear powered aircraft in cooperation with NEPA and NACA. It includes electromagnetic isotope separation research and production of America's isotopes, both radioactive and stable.

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The reality of neutrinos

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Author(s)
George Gamow
Publication
Physics Today
Publication Date
July 1948
Publisher
American Institute of Physics
Citation
Physics Today 1, 3, 4 (1948);
Abstract

In the year 1914 a young (at that time) British physicist, James Chadwick, w h o was sent to Germany to study the phenomena of radioactive decay, came across a rather interesting but, as it looked then, not very important discovery. H e found that electrons emitted by radioactive substances in the process called beta transformation do not all possess the same velocity. In fact their velocities vary over a rather wide range.

This discovery did not at first attract much attention. It "was believed that the difference in velocity between one emitted electron and another occurs simply because the slower electron loses some energy in escaping from a deeper layer within the radioactive material. It was only thirteen years later that this seemingly natural assumption was questioned and disproved by two other British physicists, C. D. Ellis and W . A. Wooster. They took some radium E, a beta-active element, and arranged to measure the heat liberated by radioactive decay both inside and outside the parent body. They chose radium E because it has no appreciable gamma radiation, which would confuse the issue. They were also careful to subtract from the total heat measured the part supplied by alpha particles given off by the polonium into which radium E decays.

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The challenge of industrial physics

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Author(s)
Howard A. Robinson
Publication
Physics Today
Publication Date
June 1948
Publisher
American Institute of Physics
Citation
Physics Today 1, 2, 4 (1948)
Abstract

In physics, as in every other branch of human endeavor, there comes a time when each individual must consider for himself the future of his personal relationship with the science he is attempting to master. At the present moment, with the war years over, large numbers of students propose to join the ranks of the 10,000 or 12,000 of us in this country who have been educated in physics. While it is true that the colleges of the country, because of their increased enrollments, will be in a position to absorb an increased number of these younger people, many more of them will go into the industrial and government laboratories of the country.

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Elementary particles

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Author(s)
T. D. Lee
Publication
Physics Today
Publication Date
October 1960
Publisher
American Institute of Physics
Citation
Physics Today 13, 10, 30 (1960)
Abstract

THE urge and the interest to find those ultimate elements in terms of which everything else is made of are almost as old as the human civilization. However, as our knowledge increases what were thought to be elementary may turn out to be composites. Consequently, the class of these supposedly fundamental elements changes with time. Such was, for example, the periodic table of atoms in the last century. Today we know that all different molecules, atoms, and nuclei are complexes resulting from the existence and the interactions of some thirty particles which are called "elementary particles".

Excerpt(s)

AS early as it as of was ft physicists decay, already suggested by several different groups of physicists that the different weak processes such as ß decay, μ decay, and  μ capture may be characterized by a single universal form of interaction. However, at that time because of the lack of detailed and accurate knowledge of these reactions it was difficult to subject this attractive idea to quantitative tests.

Since the establishment of nonconservation of parity, the discovery that in a decay process the neutrino carries away not only energy and momentum but also a definite (longitudinal) angular momentum gives a new possibility of investigating the dynamics of weak interactions by measuring angular momenta. These new measurements on angular momenta together with other already existing experiments lead now to a much simpler phenomenological description of the weak interactions. 41 Indeed, it was found 42 quantitatively that a certain coupling constant in the beta decay appears to be exactly the same as that which occurs in the ju, decay in spite of the difference that nucleons have strong interactions but juT and e ± have only electromagnetic and weak interactions. Such identity and other universal characters of these interactions may lead to a deeper and unifying principle underlying all different weak reactions.

It was realized in the 192O's that by analyzing the energy spectrum of the electron in beta decay there was an apparent nonconservation of energy. Pauli 10 resolved this difficulty by postulating the existence of a neutral particle with spin = \ h and zero (or very small) mass. Subsequently, Fermi l l developed the theory of beta decay. This neutral particle was called the neutrino v and its antiparticle the antineutrino.

Further experimental confirmations of this particle came later from the measurement of the recoil of the final nucleus, from the capture experiment of the antineutrinos and from the over-all verifications of Fermi's beta-decay theory.

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Annual APS-AAPT Meeting

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Publication
Physics Today
Publication Date
March 1958
Publisher
American Institute of Physics
Citation
Physics Today 11, 3, 52 (1958)
Comment(s)

Report on the APS meeting where Rustad and Ruby gave their post-deadline paper.

Abstract

ATTENDANCE reached what is apparently an all•time high for gatherings of physicists at the 1958 annual meeting of the American Physical Society and the American Association of Physics Teachers, held jointly in New York City at the end of January. A total of 3314 persons registered for the meeting at the Hotel New Yorker, although the program itself was no more extensive than at last year's joint meeting. The morning and afternoon schedules of the Physical Society generally involved the usual five parallel sessions each of contributed papers in addition to sessions designed to accommodate invited papers. The AAPT program was responsible for additional sessions. In all, some 400 contributed papers and 40 or so invited papers were presented. Also included were the joint ceremonial session of the two societies, the joint banquet, and the annual business meetings. Although the sessions were generally well attended, the New Yorker's lobby and mezzanine remained crowded with physicists during the entire course of the meeting.

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Rehovoth Conference on Nuclear Structure

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Author(s)
Harry J. Lipkin
Publication
Physics Today
Publication Date
January 1958
Publisher
American Institute of Physics
Citation
Physics Today 11, 1, 17 (1958)https://doi.org/10.1063/1.3062362
Comment(s)

Report by Harry Lipkin on the pivotal 1957 Rehovot Conference on Nuclear Structure, where several presenters questioned the validity of Rustad-Ruby. The full conference proceedings edited by Lipkin, including his irreverent daily newsletter, was also published the same month.

Abstract

FROM September 8 to 15 an international gathering of physicists took place for the first time in the small new state of Israel. The 220 participants registered at the conference included 155 guests from countries ranging alphabetically from Argentina to Yugoslavia. The choice of the Weizmann Institute of Science in Rehovoth, Israel, as the location of the International Conference on Nuclear Structure was undoubtedly in recognition of Israel as a center of that particular kind of nuclear research which has made the name Racah familiar in laboratories throughout the world. However, in his opening address to the conference, Professor Racah found other links between nuclear structure and the State of Israel. The first Zionist Congress, said Racah, was held at about the same time as the discovery of radioactivity; the Balfour Declaration announcing British Government support for a Jewish National Home in Palestine was promulgated at about the same time as the discovery of artificial radioactivity; and in 1948 the State of Israel was born together with the shell model. To avoid being accused of partisanship with regard to nuclear models, however, he pointed out that one of the distinctive features of Israel were the collective settlements.

Excerpt(s)

The conference opened with a reception and dinner given by the Weizmann Institute and the Municipality of Rehovoth, at which the Israel Prime Minister Mr. David Ben Gurion welcomed the participants on behalf of the Government of Israel. Prof. G. Racah was in the chair and the Chairman of the Institute's Executive Council, Mr. Meyer W. Weisgal, joined in the welcome to the delegates. The sessions began the following morning and lasted from 9:15 A.M. to 6:00 P.M. for four full days, with an additional evening session on the first day. These were held at the Weizmann Institute in the Michael and Anna Wix Auditorium. Coffee and tea were conveniently served in the auditorium lobby during the short breaks in the sessions, and lunch was obtained at the cafeteria in the Faculty Club Building. The air conditioning in both the auditorium and the faculty club gave welcome relief from the warm Israel September weather, although a number of participants, particularly those from northern Europe, expressed their pleasure at being in a place where the sun shone all the time. Every evening cocktails were served informally at the pleasant seaside hotel where most of the participants were staying, the Sharon Hotel near Tel Aviv. Discussions continued until all hours, after which some of the more energetic scientists took a midnight swim in the Mediterranean from the beach just outside the hotel. Evening entertainment possibilities also included performances by theater and dance groups in nearby Tel Aviv. In the middle of the conference, the Hebrew University invited the delegates to a tour of Jerusalem, ending with a reception given by the President of Israel, Mr. I. Ben Zvi. The last session was followed by a garden party given by Mr. Weisgal at his home in the Institute compound. The following day there was a sightseeing excursion to the region just south of Rehovoth including the town of Ashkelon with its ruins and antiquities from the times of the Philistines, Romans, and Crusaders, and also a border collective settlement overlooking the Gaza Strip. In the evening the conference was officially closed at the Conference Dinner with Professor Pauli as toastmaster.

THE two parity sessions were considerably less turbulent than had been expected a few weeks before, when different laboratories had obtained contradictory results for parity experiments, particularly the measurement of beta-ray polarization. The parity experimentalists succeeded in settling their differences among themselves just before the conference and presented a "united front", to the great disappointment of certain theorists who had hoped to see a big scrap. It was now admitted by all concerned that all reliable results obtained thus far for beta-ray polarization were consistent with full polarization in all cases, left-handed for negatons and right-handed for positons. Only the recoil experiments measuring electron-neutrino angular correla-tion still presented a confused picture of mutually inconsistent experimental results.

These sessions began with a series of lectures presenting an excellent survey of the present state of beta decay. E. J. Konopinski presented a summary of the conclusions regarding the nature of the beta-decay interaction which were obtainable from "classical" (before parity) experiments. He stressed the revisions necessary in these conclusions in view of the nonconservation of parity, particularly those drawn from the absence of Fierz interference. The weakening of these conclusions left accurate recoil experiments as the only method for determining the beta interaction. T. D. Lee then presented the theoretical aspects of parity nonconservation in beta decay, treating a four-component neutrino, introducing the concept of helicity, and pointing out the simplifications possible if lepton conservation and twocomponent theory were valid. C. S. Wu presented the experimental aspects of parity conservation, including a description of the different types of new parity experiments and a summary of the present state of experimental data.

The session concluded with report on the recent controversial recoil experiments by Allen et al. on A35 (presented by H. Frauenfelder) and Ridley et al. on Ne23 (presented by P. E. Cavanagh), after which Chairman 0. Kofoed-Hansen concluded that since it had taken two years of careful work in these difficult recoil experiments to reach the present confused state, it would probably take another two years to clear it up.

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The Neutrino

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Author(s)
James S. Allen and Arthur H. Snell
Publication
Physics Today
Publication Date
November 1958
Publisher
American Institute of Physics
Citation
Physics Today 11, 11, 36 (1958)
Comment(s)

Review of James Allen's 1958 book highlights his account of the beta decay experimental history.

Abstract

All physicists recognize as one of the absorbing aspects of their science the crossing and interlocking of its many threads, the appearance of basic principles in various forms when varying subjects are under scrutiny, and the diverse viewpoints from which sets of phenomena can be assessed. Take the subject of beta decay. The classical expositionary approach has been based upon the Fermi theory, with emphasis on the shape of the continuous spectrum, the allowed and forbidden transitions, the ft values, and so on, and indeed the remarkable developments of the last two or three years can be incorporated as capstones upon a structure of this kind. In Dr. Allen's book he has shown that the story can also be developed with emphasis upon the neutrino, and that such a development can be given sweep and vigor.

Excerpt(s)

Dr. Allen's treatment retains the physics of the many aspects of beta decay; the shape of the continuous spectrum (especially near its end point), angular correlations in the three-body breakup, double beta decay, decay of polarized nuclei, meson decay, helicity experiments, the nature of the basic interactions, and the universal Fermi interaction all receive discussion.

There is sufficient theory to give unity and a feeling for the objectives sought by all of the investigations, but the text is at its best when it deals with the experiments. As one reads successively about the various measurements that have informed us about the neutrino, one cannot avoid being struck by the ingenuity that has been shown. The account is in a way an incidental history of the development of laboratory skills, exemplified in the progressively increasing specificity of the experiments.

The latter have been notoriously difficult, for sundry reasons: the measurements of the upper end of the tritium spectrum were difficult because of the low energy of the particles and the fact that they vanish in intensity in the region of interest, and yet they have told us that the rest mass is less than a thousandth of that of an electron; the experiments on nuclear recoil from electron capture have been difficult because of the low energy of the recoils, with the consequence that "vacuum" sources have to be used, and yet they have been forced to such detail as a revelation of the recoil line shapes; the experiments on beta particle-recoil nucleus angular correlations have been difficult for similar reasons, and yet they have informed us about the nature of the basic interactions; the experiments on double beta decay have been difficult because of the tantalizing infrequency of the events; the radiochemical experiments have demanded the application of the finest of technique, sometimes almost on a chemical engineering scale; and (most of all) the experiments on the detection of the free neutrino have been difficult because they demanded the measurement of interaction cross sections about 10 12 times smaller than those that had previously been considered small.

It is therefore fitting that the emphasis be experimental, as it is also fitting that the story be told by one who has contributed substantially to it.

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