bluuebunny/crossref_metadata_2025 huggingface dataset:
Solid-state plasma
Authors: Chynoweth A. G. , Buchsbaum S. J.
Published: April 2009

Some twenty years ago Ruthemann and Lang shot a monoenergetic beam of electrons in the keV range through a thin foil of aluminum and measured the energy distribution of the emergent electrons. They noticed that while most of the beam penetrated the metal without an appreciable loss of energy, there was a distinct group of electrons which lost very nearly 15 eV. When a different metal was substituted for aluminum, the same phenomenon was observed except that the characteristic energy loss differed from metal to metal. The explanation of this effect was not long in coming. Some of the electrons lost a certain definite amount of energy by exciting longitudinal plasma oscillations inside the metal at a frequency ωp characteristic of the particular metal. This cost the electron a “quantum” of energy ℏωp, where ℏ is Planck's constant; Pines called this quantum the “plasmon”. The experiment, and the Bohm and Pines theory of it, marked the beginning of research into the properties of solid-state plasmas.
Photoproduction of mesons and hyperons
Authors: Bacher R. F.
Published: April 2009

Pions, heavy mesons, and hyperons were all first observed in cosmic-ray interactions many years ago. Considering the rarity of the observed events and the difficulty of the experiments, an extraordinary amount of knowledge was obtained from this work. The rate of discovery of new particles and of excited states of particle systems increased rapidly with the development of high-energy accelerators for protons and electrons, and the pace has now been very fast for several years. This report concerns some of the work in one section of the field, the photoproduction of mesons and hyperons.
The prehistory of solid-state physics
Authors: Smith Cyril Stanley
Published: April 2009

Prehistory implies the selection of a date when history begins. In solid-state physics this is very recent, dating, perhaps, from Debye's specific-heat theory of 1913, but most of all from the famous diffraction experiment of Friedrich, Knipping, and Von Laue in March 1912. It was this tool of perfection which laid the ground for imperfection to become of interest to physicists. The growth of solid-state physics marks, I think, a basic change in the attitude of physicists toward matter. Virtually all the development of mechanics, marvellous though it was, was based on a treatment of matter that was essentially structureless and whose measured elastic constants and densities gave the constants to put into equations that became ever more elaborate. When physicists at last paid attention to the structure of real crystals, they soon became aware of imperfections, both theoretically and experimentally, and the great flourishing of solid-state physics in the last three decades has been mostly based on the elucidation of the role of mechanical, ionic, and electrical imperfections in a crystal, accompanied, of course, by a continued development of understanding of bonding and dynamics of the ideal lattice.
Report from Culham… 1. Experimental plasmas
Authors: Spitzer Lyman
Published: April 2009

Seven years after the declassification of the plasmaphysics program it is clear that the physics of hot plasmas has become a mature scientific discipline. Plasma theory, which is both extensive and elegant, is in much closer touch with observational research than was possible in the early years of diis subject.
The computer and you
Authors: Spinrad Robert J.
Published: April 2009

The folk wisdom of most nations has a proverb that comments on man's discomfort with new ideas or experiences. In English the saying is “You can't teach an old dog new tricks.” In Slovene it is, “The tree must be shaped when it is young.” One does not normally think in these terms, however, when discussing the deliberations of science because scientific thought reputedly represents the ascendancy of objectivity over subjective predilections. The professional scientist is thought of as one whose training enables—or rather compels—him to grasp the new if it can help him in his search.
Science… and public policy
Authors: Daddario Emilio Q.
Published: April 2009

This subject—science and public policy—needs discussion. Not that it hasn't received plenty in the past several years. Almost every time we turn around, we run into some sort of exposition dealing with science and government or science and the national economy or science and the utilization of manpower or science and American education or something similar.
Crystallography
Authors: Ibers James A.
Published: April 2009

The annual meeting of the American Crystallographic Association (ACA) was held July 24–31, 1964, on the beautiful campus of Montana State College at Bozeman, Montana. Approximately 400 crystallographers, over thirty percent of the membership of the ACA, took an active part in the meeting. Of the 170 papers of 15-minutes duration, about 50 were presented in single sessions, and the rest were distributed between two simultaneous sessions.
Low temperature physics
Authors: Yaqub M.
Published: April 2009

In spite of the increasing popularity of lowtemperature conferences in recent years, some of the pundits argue that the subject of low temperatures has ceased to be a coherent whole, and that low-temperature conferences should be abandoned. It is true that we have progressed far beyond the pioneering days when every experiment revealed a new phenomenon and every discovery offered a new challenge. With the disappearance of liquid helium and superconductivity from the list of unsolved problems, we are no longer worried by any major mysteries. However, the theories of Landau and Feynman and Bardeen, Cooper, and Schrieffer have not only explained existing facts but have raised new problems, and it is clear that there are enough interesting and unresolved fundamental questions to keep most of us happily occupied for many years to come, and although at present it appears unlikely, there may be further surprises around the corner.
The physics of liquids …a conference report
Authors: Hunter Joseph L. , Carome Edward F.
Published: April 2009

Under the sponsorship of the National Science Foundation, the Physics Department of John Carroll University played host to about sixty researchers in the field of the physics of liquids at a fourday conference from June 1 through June 4, 1964. Although the meeting was built around a nucleus of prepared talks, several of the participants preferred the more informal approach of participating from the floor in all of the talks. Among the latter were Daniele Sette of the University of Rome, Henry S. Frank of the University of Pittsburgh, Martin Greenspan of the National Bureau of Standards, and Robert T. Beyer of Brown University. As a matter of fact, most of those delivering talks preferred to think of themselves as discussion leaders rather than lecturers.
Regional counselors in physics
Authors: Dressel Ralph
Published: April 2009

Since its inception in October 1961 as a joint project of the American Association of Physics Teachers and the American Institute of Physics, the Regional Counselor Program has directed its attention to the complex problems involved in the effective presentation of physics in the high schools. Under this program, physicists from local universities or industrial laboratories, one for each state, the District of Columbia, and Puerto Rico, are appointed to serve as regional counselors. Each of the fifty-two counselors serves voluntarily, devoting as much time as he can to establishing contacts and responding to invitations from high schools in his region.
Recent discoveries in radio astronomy
Authors: Roberts Morton S.
Published: April 2009

The application of radio techniques to astronomy has opened an immense new window on the universe. Till relatively recent times, the earthbased astronomer was restricted to an opticalwavelength region ranging over a factor of three. He now has available an additional part of the electromagnetic spectrum whose range in wavelength is more than a factor of one thousand.
Private and public communications in physics
Authors: Moravcsik Michael J.
Published: April 2009

The problem of communication among physicists has grown more and more acute in the past few years. Discussions of this crisis have ranged from innumerable bull sessions during coffee breaks, through frequent editorials in scientific journals, up to a formal report of a special panel of the President's Scientific Advisory Committee, headed by Alvin Weinberg.
The International Center for Theoretical Physics
Authors: Salam Abdus
Published: April 2009

The idea of creating an international center for theoretical physics was conceived in Rochester at the High-Energy Physics Conference in September 1960. In his banquet address, John A. McCone, who was then the chairman of the US Atomic Energy Commission, mentioned with approval a suggestion that nations collaborate in setting up a joint high-energy accelerator. Some of us—Hans Bethe, Robert Sachs, Nicholas Kemmer—who assembled afterwards, wondered whether it might not be more practical to start on a smaller scale with a modest, truly international center for theoretical physics—financed, perhaps, by one of the United Nations family of organizations. No such institutes existed then; a theoretical physics institute possibly might even set a pattern for a future United Nations University.
Plasma physics
Authors: Oberman Carl
Published: April 2009

The opening of the new International Center for Theoretical Physics on October 5, 1964, in Trieste, Italy, also marked the commencement of the first of its activities—a four-week Seminar on Plasma Physics. In an attempt to be true to the principles upon which the center was founded, the seminar was designed to serve three purposes: (a) to introduce the subject of plasma physics to students, primarily those from developing and scientifically isolated countries who, while scientifically skilled, lacked any specialized experience in the field; (b) to expose new researchers in the field to the outstanding problems and the techniques proposed for their solution; and (c) provide a meeting ground for colloquy among experts in order to test new and sometimes tentative approaches.
The on-line computer counter and digitalized spark-chamber technique
Authors: Lindenbaum S. J.
Published: April 2009

In the fall of 1962 at the Brookhaven Alternating Gradient Synchrotron, a remarkable event took place. A highly complex elastic-scattering experiment involving high-energy (7–20 BeV/c) protons and pions scattered by a hydrogen target was investigated by a system of several hundred scintillation-counter hodoscopes covering a large fraction of the solid angle in the investigated angular region. The system was all in fast (a few to 30 nsec) coincidence with complicated-logic trigger requirements, and it automatically trigger-selected, compiled, stored, and finally transmitted the data to an on-line computer. The computer then processed the data automatically and rapidly in real time according to a carefully pre-programmed analysis, stored the desired results in suitable bins, and transmitted the program-requested data displays back to the display scopes of the experimental group. Desired physical answers based on cumulative statistics (such as computed cross sections, errors, background values and distribution, displays of counter-efficiency uniformity, etc.) were also available in detailed print-out tabular (or, if desired, graphical) form, upon initiation by the experimenters of a simple output routine.
Musings in the museyroom
Authors: Brown Laurie M.
Published: April 2009

“Symmetry Principles at High Energy” can be read either as a caption or a headline; the double meaning might have pleased the great Irish novelist whose quarks have, in one form or another, dominated this year's conference. The Coral Gables Conference, meeting again in the University of Miami's Lowe Art Gallery (the “museyroom” of the title), between January 20 and 22 of this year, heard a number of contributions dealing with relativistic extensions of the static SU (6) quark model, itself an extension of the SU (3) octet model; these extensions invariably led to a symmetry group called either Ũ(12) or M (12) based on twelve fundamental generators or “objects”. The reward for enlarging the symmetry group consists of larger supermultiplets, for example, the pseudoscalar octet is united with the nine vector mesons, and the baryon octet with the decuplet. Having a formally relativistic theory makes possible the writing of Ũ(12) invariant interactions among these thirty-five mesons and baryons which involve only two independent (and known) coupling constants! The theory is also simple enough that important new consequences can be derived with relative ease. Some of these will be mentioned below, and others will undoubtedly, within a short time, begin to fill the pages of the physics journals. But, it should be emphasized that this is only a beginning and that the present forms of U (12) are incomplete; they may also have other difficulties, which will be mentioned subsequently.
Source retrieval
Authors: Richmond Phyllis A.
Published: April 2009

One of the most common experiences in the life of a physicist is the discovery of a lead to further information on some aspect of his current research project. He writes down his reference and goes to his library to look for it. Many times he cannot locate the source journal or the source document by his own unaided efforts.
The taxation threat to the progress of american physics
Authors: Sawyer Ralph A.
Published: April 2009

Published newspaper and magazine articles, private communications, and oral reports in recent months have posed this threat: the Internal Revenue Service is thinking seriously of taxing income derived from subscriptions and from advertising in the journals of such tax-exempt organizations as the American Institute of Physics and its member societies as well as other scientific organizations.
AIP annual report 1964
Authors: Hutchisson Elmer
Published: April 2009

Submitted by the director and accepted by the Governing Board of the American Institute of Physics as its annual report to the Member Societies of the AIP, March 20, 1965
Collected works
Authors: Henisch H. K. , Henisch B. A.
Published: April 2009

About four years ago, there appeared in the Personal Column of the (London) Times an advertisement which invited readers to send “new, unpublished and unorthodox scientific theories to essayist-advertiser for purposes of evaluation and review”. The response was more than gratifying and, in this simple way, some rich additions were quickly made to a collection which had been growing steadily but only slowly over the years.
Old and new fashions in field theory
Authors: Dyson Freeman J.
Published: April 2009

Sixteen years ago I gave my first invited talk to the American Physical Society, and spoke about the exciting work that was then just coming to an end in quantum electrodynamics. Now I am here again, and it seems that everything looks very much the same as it did in 1949. Only two things have changed. I am not as nervous as I was then, and the audience looks a great deal younger.
Scions are fermions, a law of socio-physics?
Authors: Green Alex E. S.
Published: April 2009

In a previous article* the writer drew attention to the fact that some of the models, mathematical formalism, and language used in describing nuclear phenomena can be applied to a particular sociological problem: the remuneration of scientists. In particular, the independent-particle model and its associated formalism which have been used so successfully in accounting for bound-state and scattering phenomena in nuclei, seem also to provide a basis for correlating scientific salaries. In the case of nuclear phenomena, the basic interactions between nucleons are two-body interactions. Nevertheless, it appears to a good approximation that the interaction of a particular proton or neutron with all the other particles in a complex nucleus can be characterized by a family of potentialversus-radius functions which represents the average interaction of this particular particle with all the particles in the nucleus. In the sociological problem, again scientists are people, and people essentially interact in pairs. Yet it would appear that somehow in the course of the many two-body interactions (scientist and personnel man, scientist and manager, scientist and scientist, scientist and contract monitor) some sort of overall interaction of scientist with society results which seems describable by a percentile distribution function versus rate of pay.
American Crystallographic Association meets in motel
Authors: Knox Kerro
Published: April 2009

The American Crystallographic Association made an experiment in departing from the form of previous meetings for its winter meeting, February 24–26, 1965. The meeting was held, not on a university campus, but at a commercial motel in Suffern, New York, where the isolation provided little distraction from business. A small meeting was planned, but nearly 200 crystallographers eventually showed up. The first day was devoted to six invited papers in a symposium organized by S. C. Abrahams on accuracy in x-ray intensity measurement. This subject has become of vital interest and some controversy among diffractionists with the growing sophistication of their experimental and computational techniques. This was followed by four sessions comprising 43 contributed papers, most of which illustrated directly the theme of the symposium.
Science, technology, and the Library of Congress
Authors: Gray Dwight E.
Published: April 2009

The walrus' catalog of “many things” as reported by Lewis Carroll comprised a form of footwear, a mode of transportation, a resin-turpentine mixture, a thick-leaved member of the mustard family, a rank of male royalty, an aspect of oceanic temperature, and a possible anatomical aberration of swine. Although the “many things” dealt with by the Science and Technology Division of the Library of Congress are mostly different from those enunciated by Carroll's walrus, they are fully as varied and vastly more numerous. They have included, for example, aerospace and the Antarctic, permafrost and plastics, diodes and Diesel engines, magnetism and marine borers, lasers and Loran, photointerpretation and physiology, bioregeneration and blood flow, isotopes and infrared, catamarans and cloud seeding, and many others.
Physics at the American University of Beirut
Authors: Zahlan A. B.
Published: April 2009

When scientists of developed countries discuss the potentialities of scientific activity in developing nations, arguments are often advanced that pure research can be carried out only in the established centers with tradition, accessibility, time, and funds; and that anyway what Africa and Asia need are sanitation systems and a “good fifty-dollar bulldozer”. Establishing truly significant scientific research programs in countries still lacking tractors and sewage systems is more difficult than adding another laboratory in Greater Boston or establishing another institute in Southern California. However, if such arguments had prevailed in the past, Harvard would not have been founded—Oxford and Cambridge were already there; MIT would not have opened—Princeton and Harvard were there; and California would have remained wilderness. Growth and development, if they are to exist, cannot be fettered by the chains of absolute logic. If the underdeveloped countries of the world wait until they have brought the everyday conveniences of modern life into their most remote villages before they begin to attempt competition in the quest for knowledge, they will be doomed to an eternity of trailing further and further behind countries well embarked on a second industrial revolution before they have reached the first. They will be condemned to an economic dependence more crippling than any of the colonialist era.
Vibration isolation
Authors: Vigness Irwin
Published: April 2009

We are going to describe principles and devices that are useful in determining how to isolate equipment from disturbing vibrations. Perhaps the only way that we can truly isolate an item of equipment is to place it in a satellite that contains no internal energy sources and to have it travel in interstellar space. Isolation is a matter of degree. Generally one compromises by putting some effort into making the equipment so that it can withstand a reasonable amount of vibration. Then a sufficient amount of isolation is provided so that the situation can be endured.
Cross-section measurements made with neutrons from a nuclear detonation
Authors: Hemmendinger A.
Published: April 2009

Ever since the first nuclear detonation near Alamogordo, N. M., on July 16, 1945, there has been much speculation, and a few full-scale experiments, on the use of such detonations as a source of neutrons for measurements using time-of-flight definition of neutron energy. Although these time-of-flight experiments are in principle quite simple, they had to await the solution of a myriad of unusual engineering problems. When the United States and other nations agreed in 1963 to discontinue atmospheric testing of nuclear weapons, the Atomic Energy Commission invested considerable effort in the development of techniques for underground testing. In the course of this work, vacuum flight paths hundreds of meters long were used from time to time. They were quite straight, with antiscattering baffles and provision for closure to contain bomb debris and radioactive gases. The dirt fill around the pipe provided excellent shielding for the neutron collimator, and it was natural at this stage of development to consider the possibility of cross-section measurements.
A new laboratory—How to work in it
Authors: Newell Homer E.
Published: April 2009

It is not my intention to parade before you long lists of space missions, launch vehicles, spacecraft, and other hardware, budgets, schedules, and such—inseparable though these may be from space activities. Rather, the discussion to follow will dwell on science, with only just enough reference to those other aspects of the space program to illustrate how our growing national space capability is providing valuable tools, techniques, and opportunities for scientific research.
Plutonium criticality experiments
Authors: Clayton E. D.
Published: April 2009

Plutonium, the man-made element of atomic number 94, has established itself mainly as the fissile component of nuclear weapons. It is always made in the operation of a uranium-fueled reactor and has been manufactured in large quantities since its introduction in World War II. It has long been considered inevitable that plutonium will become an important reactor fuel. It offers hazards and puzzles to reactor physicists, and for two reasons in particular they must know the conditions under which assemblies containing it become critical. First, they must design processing systems that will not have accidental and dangerous chain reactions. Second, they need data for reactor design.
Eclipse
Authors: Korff Serge A.
Published: April 2009

Total eclipses of the sun provide astrophysicists with the same excuse for travel as physicists find in cosmic-ray investigation. Some unkind people have even referred to this as a “racket”. They should attempt unloading several tons of equipment from a boat while standing in three feet of water flowing over a coral reef.
Physics of quantum electronics
Authors: Tannenwald P. E. , Kelley P. L. , Lax B.
Published: April 2009

The intent: to hold a gathering of a small number of active scientists to discuss the physics of quantum electronics in a setting that would afford a maximum opportunity for close contact in a relaxed atmosphere with a minimum number of formally scheduled papers.
New particles excite experimenters and puzzle theorists
Authors: Lubkin Gloria B.
Published: April 2009

The world of high-energy physics has been set afire by the discovery of a new particle with very narrow width at 3.1 GeV. Experimentalists everywhere have rushed to their laboratories to try to measure some of the properties of the new particle. Already a second particle has been found at 3.695 GeV by one of the two groups that discovered the first particle. Theorists are consulting in corridors and in hastily summoned seminars to discuss possible interpretations of the discoveries. Some are calling the events “the greatest thing since strange particles.”
Superconductor operates in magnetic fields above 500 kG
Authors: Rothenberg Marian S.
Published: April 2009

A compound of lead, molybdenum and sulfur, Pb1.0Mo5.1S6, has remained superconducting in a 510-kilogauss magnetic field at liquid-helium temperature, 4.2 K. This is the highest upper critical field Hc2 (4.2 K) yet reported for a superconductor, and the predicted value for Hc2 (0) is 600 kG. Materials that remain superconducting at high magnetic fields could be formed into powerful, lightweight magnets if they can support high current density and are sufficiently strong to withstand the resulting forces. Simon Foner, Edward J. McNiff Jr and Edwin Alexander of the Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology, described the high-field measurements at the recent Applied Superconductivity Conference in Oak Brook, Illinois (30 September–2 October) and in the 23 September issue of Physics Letters.
Odd behavior of giant quadrupole resonance
Authors: Lubkin Gloria B.
Published: April 2009

Intensive study of an isoscalar giant electric quadrupole resonance in nuclear spectra, stimulated by its apparent discovery several years ago at a position just below the well established giant dipole resonance, has produced a modified—and puzzling—picture of its behavior. Stanley Hanna of Stanford University summarized the current experimental status of the giant quadrupole resonance (GQR) at a conference on Nuclear Structure and Spectroscopy held in Amsterdam, 9–13 September.
Anaheim hosts the APS and AAPT
Authors: Saar Robert A.
Published: April 2009

Issues directly affecting the human condition—food production, health, energy, education and applications of physics will all be discussed in sessions at the annual joint meeting of the American Physical Society and the American Association of Physics Teachers. The four-day meeting, starting on 29 January (running Wednesday through Saturday), will take place mostly at the Anaheim Convention Center in Anaheim, California, a southeastern suburb of Los Angeles and the home of world-famous Disneyland. The gatherings not being held at the Convention Center will be most APS–AAPT joint sessions and all AAPT meetings, to be conducted at the nearby Royal Inn.
Two physicists on Capitol Hill
Authors: Cooper Benjamin S. , Werthamer N. Richard
Published: April 2009

In the 28 May 1973 issue of Physical Review Letters there appeared an unusual “Help Wanted” ad:

“…the Council [of the American Physical Society] at its meeting on 22 April authorized a Congressional Fellowship Program. Funds were appropriated to support up to two APS Congressional Fellows—physicists who will serve for a year in the Offices of Senators, Representatives, or Congressional Committees beginning September 1973. Any physicist who wishes to apply should submit a resume, references, and a statement indicating how his background and interests qualify him for the position…”
International cooperation in physics
Authors: Scott John T.
Published: April 2009

Physics is the uniquely international science. No other science is so closely tied, in all countries, to budgetary and regulatory agencies at the government level, and so no other science is as well placed as physics to implement cooperative ventures cutting across national boundaries. And its followers communicate in an international language that transcends any trivial difficulties over mere words; physicists around the world may not always agree, but at least they know what their foreign counterparts are saying and publishing.
TRIUMF becomes world's third operating meson factory
Authors: Rothenberg Marian S.
Published: April 2009

Champagne flowed in Vancouver, British Columbia recently as the TRIUMF cyclotron yielded its first extracted full-energy beam. With the production of 500-MeV negative hydrogen ions, the Tri-University Meson Facility (TRIUMF) thus joined the other two new meson factories—the Clinton P. Anderson Meson Facility (LAMPF) in Los Alamos, New Mexico and the Swiss Institute for Nuclear Research (SIN) in Villigen; both of these have already achieved external beam production, have begun their experimental programs and are busy building up beam intensity. The TRIUMF cyclotron, part of a meson factory that has been under construction since 1971, will eventually furnish intense secondary beams of pions, muons and neutrons to experimental areas. The impetus behind the meson factories has been the need for sufficiently intense beams of these particles to act as probes for the otherwise unobtainable details of nuclear structure. Intensities are typically 103–104 times that available at existing machines, and energy resolution is 100 times better. Some particle physics is also possible, as is a program of applied research, notably pion radiation therapy.
Fermi Lab produces a 225-GeV electron beam
Authors: Rothenberg Marian S.
Published: April 2009

The Fermi National Accelerator Laboratory has produced a 225-GeV electron beam, a record energy for electrons. According to Thomas Nash, the NAL physicist responsible for the beam's development, beam intensity in the 100–150-GeV range was about 4×105 electrons per pulse, in agreement with predicted values for 2×1011 protons injected per pulse. Intensity is expected to be over 107 electrons per pulse for a full intensity proton beam of over 1012 protons per pulse. Of course, intensity at 225 GeV is much lower but is also within the range predicted. The electrons will be used as a source of “tagged” photons, rather than for themselves; NAL already has a muon beam for doing lepton physics, but the ability to produce photons of known energy is unique. Before the NAL beam was produced, the highest energy electron beams were at Serpukhov, USSR (35 GeV) and at the Stanford Linear Accelerator Center (20 GeV).
Japan builds a science city
Authors: Birnbaum Henry
Published: April 2009

Japan is building a major science city, Tsukuba Newtown for Research and Education, a project so massive that it took the government ten years to commit itself to the undertaking. Although construction at the site north of Tokyo has been under way for three years, the debate on Tsukuba still continues.
More data on the new particles: theory uncertain
Authors: Goss Levi Barbara
Published: April 2009

High-energy experimentalists are starting to paint a more complete, although still sketchy, picture of the new particles at 3.1 and 3.7 GeV that were discovered by surprise last November (see PHYSICS TODAY, January, page 17). Results so far are consistent with the early expectations that both particles are vector particles. They have been photoproduced, and the high-energy resonance has been seen to decay into the lower one. Finally, these two particles appear to stand alone, as searches for other narrow resonances have so far yielded nothing except a broad peak at 4.1 GeV. Such was the picture presented by experimentalists from several institutions at the Annual APS Meeting in Anaheim, California from 29 January to 1 February. While the new results fit into some of the proposed theoretical schemes better than into others, they do not mesh completely with any of them. In a possibly related development, a weakly interacting particle carrying a new quantum number has been suggested by recent neutrino experiments. (See box on page 24.)
A pulsar that doesn't slow down fast enough
Authors: Rothenberg Marian S.
Published: April 2009

A pulsar that is slowing down much less rapidly than any other known pulsar may have some interesting implications for current theories of pulsar formation and perhaps even for theories of expansion of the universe. David Richards, John Rankin and Gustave Zeissig studied the pulsar, JP 1953, as one of 13 in a continuing program of precise pulse timing at the Arecibo Observatory in Puerto Rico. A surprising result of the study, they comment in Nature is that for JP 1953, dP/dt, the change in its 0.4 sec period with time, is only about 0.003±0.007×10−15 seconds per second. The previously known smallest value for any pulsar had been 0.15×10−15, and a typical value exceeds 10−15.
Probing the weak force with neutrinos
Authors: Cline David B. , Mann Alfred K. , Rubbia Carlo
Published: April 2009

Interest in neutrino physics has surged up recently, partly because the “little neutral ones” are being groomed for the job (for which they alone are qualified) of probing the interiors of stars. Among elementary particles the neutrino is unique. This is because—as far as we know—it alone interacts with other particles only through the Fermi, or weak, interaction. In this article we will discuss how recent experiments, with new accelerators and detectors, such as the ones at CERN and Fermi Lab, have shed new light on some of the fundamental questions regarding the weak interactions. We will review the recent discoveries of neutral weak currents that conserve strangeness, parity violation and point-like neutrino collisions, as well as some of the implications of these experiments to particle theory.
Resetting biological clocks
Authors: Winfree Arthur T.
Published: April 2009

A pendulum can be stopped by a single impulse of the right magnitude, delivered at the proper time; started again, its phase will have changed. A biological oscillation, although it is a vastly more complicated phenomenon, can likewise be arrested by a single stimulus of a definite strength delivered at the proper time. This remarkable fact emerges from experiments I have conducted on two biological clocks, in organisms in the plant and animal kingdoms. The most interesting potential applications are, of course, those that involve the internal clocks of Man.
The role of industry in international energy programs
Authors: Schmitt Roland W. , Stewart Peter J.
Published: April 2009

The time has come for technical people in industry to take the lead in establishing international programs in energy research and development. To show why we believe this, we will have to explain why we think international ventures in the energy field will turn out to be best handled by industry-to-industry contacts, rather than through some kind of government-to-government dialog, and also why we think it is time that industrial scientists, rather than purely business-minded executives, played leading roles. Close links with cooperating government agencies will of course still be appropriate and necessary, but initiatives should now come from industrial scientists.
Radio-wave deflection experiments confirm Einstein
Authors: Rothenberg Marian S.
Published: April 2009

Einstein yes, Brans–Dicke no, is the apparent verdict of some recent experiments at the National Radio Astronomy Observatory, Green Bank, West Virginia. Edward Fomalont and Richard Sramek measured the deflection of microwave radiation by the Sun's gravitational field and report results sufficiently precise that they are consistent with Einstein's general relativity but not with scalar–tensor formulations such as Brans–Dicke theory. The remaining uncertainty concerns possible systematic errors in these observations, not the formal statistical error, which appears to be sufficiently small. The experimenters used a 35-km baseline radio interferometer to study three nearly collinear radio sources at two frequencies and found the bending to be 1.015±0.011 times that predicted by general relativity; the Brans–Dicke prediction differs by about seven percent.
Ion–surface scattering reveals unexpected oscillations
Authors: Rothenberg Marian S.
Published: April 2009

A series of ion-surface scattering studies has revealed surprising oscillatory cross sections that some atomic physicists are hailing as macroscopic evidence of quantum-mechanical phase interference phenomena. Robert Erickson and David Smith (Central Research Laboratories, 3M Company, St. Paul) saw the pronounced regularly spaced oscillations when they measured scattering cross sections as a function of primary energy for the elastic scattering of lowenergy noble-gas ions from a number of solid surfaces. Although similar oscillations are well known in ionic collisions in gases, this is the first report of such oscillations in scattering from surfaces. Erickson and Smith explain their results in terms of binary collisions (as in a gas) between an incident ion and a surface atom, and a resulting quasimolecular state with shared electrons. Although not everyone is satisfied that the experimental data are yet sufficient to rule out other likely explanations, most agree that the results are exciting if this interpretation is borne out.
Excitation-transfer nitrogen lasers
Authors: Scott John T.
Published: April 2009

A high-power, high efficiency laser with a wavelength in the visible or near-ultraviolet would be very desirable for such proposed applications as laser-induced fusion and isotope separation. Demonstration models of systems that might lead to this goal have been recently reported from the Naval Research Laboratory, Northrop Corporation, the University of Texas at Dallas and the Lebedev Physics Institute in Moscow. All these systems employ electron-beam energy deposition; they all use rare-gas and nitrogen mixtures, and they lase at wavelengths in the 3000–5000 Å range with efficiencies around 2%. At Los Alamos work is proceeding on a somewhat different approach that attempts to increase the output pulse length of lasers of this type.
Surface Physics: An Introduction
Authors: Schrieffer J. Robert , Soven Paul
Published: April 2009

There is a growing interest in fundamental studies of surfaces, stimulated in part by the advent of new experimental techniques capable of characterizing the surface of a microscopic level, and in part by the relevance of research on surfaces to some very practical problems facing our technological society. These problems are found in areas such as heterogeneous catalysis, corrosion, embrittlement, photocells and many solid-state electronic devices. A good example is methanation, in which methane is produced via the reaction of H2 and CO with a metal catalyst. Although this simple reaction is of great practical importance, the mechanism underlying it is not known, and the reasons for nickel's outstanding specificity to methane are not understood.
Theory of the electronic structure
Authors: Schrieffer J. Robert , Soven Paul
Published: April 2009

A solid surface is characterized in the same way as any solid or molecule. We must determine the chemical identity of the atoms present, the geometrical arrangement of these atoms and the distributions of electrons surrounding these atoms, both in energy and space. This characterization of the static surface is the first step in understanding the dynamics of the interaction of the surface with external systems such as atoms, molecules, photons or other surfaces.
Photoelectron spectroscopy
Authors: Eastman Dean E. , Nathan Marshall I.
Published: April 2009

The surge of growth in surface science, demonstrated by this special issue of PHYSICS TODAY, can be attributed to several complementary factors. First, the gas–solid interface is amenable to investigation by many new research tools that involve various combinations of electrons, photons, ions, electric fields and so on. Second, the insights and information obtained from modern surface-science experiments are useful to many technologically important fields, such as catalysis, corrosion and semiconductor devices among others. Third, two-dimensional interfaces such as the gas–solid interface constitute a distinct phase of condensed matter with unique properties that we are only beginning to understand—thus, studies of solid surfaces are an attractive “new frontier” for materials scientists and are being vigorously explored.
Inner-shell spectroscopy
Authors: Park Robert L.
Published: April 2009

If a surface exposed by cleaving a mica sheet is sprayed immediately with distilled water from an atomizer, the water seems to disappear as it uniformly wets the surface. If several seconds had been allowed to pass before the surface were sprayed, the water would bead up in distinctly visible droplets. In that brief moment the surface has been contaminated by organic vapors from the laboratory air; even at a pressure of 10−12 atmospheres, a complete monolayer of contamination can condense on a surface in less than an hour. Such layers may determine the characteristics of the surface with respect to lubrication, corrosion, catalysis, emissive properties and adhesion; yet prior to 1967 no general method existed by which the surface composition could be analyzed.
Vacuum–tunneling spectroscopy
Authors: Plummer E. Ward , Gadzuk John W. , Penn David R.
Published: April 2009

Any spectroscopy that is to be used to study surfaces must be sensitive, almost specific to the surface. The most successful surface spectroscopies, whether they measure emission or absorption spectra of electrons, can be grouped into two general categories depending upon the origin of their surface sensitivity. The first group, which includes photoemission, Auger and appearance-potential spectroscopy, owes its surface sensitivity to the strong electron–electron interactions of an incoming or outgoing electron, which limits the inelastic mean free path of an unscattered electron to at most a few atomic layers in the appropriate range of electron energy. The second group of electron spectroscopies, which is the subject of this article, derive their surface sensitivity from a sampling of the exponential tails of the wave functions, which tunnel into the vacuum. We have called this set of experimental techniques “vacuum-tunneling spectroscopy.”
New solar energy cells may prove economical
Authors: Levi Barbara G.
Published: April 2009

Research on solar cells focusses on finding devices that have the simultaneous promise of high efficiency, long lifetime and low cost. Therefore observers have been excited about the recent development of two new solar cells with efficiencies of 12–13% that might be many times cheaper than silicon cells—if they fulfil their potential to be made by thin-film techniques. The potential of these two devices for solar-energy conversion was recognized by Sigurd Wagner and Joseph Shay of Bell Laboratories as they were investigating new materials and components for optical communications systems. One of these cells consists of a thin film of cadmium sulfide deposited on a single-crystal substrate of indium phosphide.1 The other has a cadmium-sulfide layer on a single-crystal substrate of copper indium diselenide.2
Ultraheavy cosmic rays
Authors: Israel Martin H. , Price P. Buford , Waddington C. Jake
Published: April 2009

Ultraheavy cosmic-ray nuclei, those with atomic number over thirty, constitute less than about one in 107 of the relativistic particles that stream through our solar system, yet they promise to lead to a major contribution in our understanding of the complex phenomena of the cosmic-ray gas that pervades interstellar space. The study of these nuclei should advance our understanding of the sources of cosmic rays as well as of the nature of the physical processes that influence the particles after their acceleration. This work is greatly accelerating with the advent of satellite experiments, such as the Skylab mission pictured in figure 1.
Physics in 1975—new problems and insights
Authors: Panofsky Wolfgang K. H.
Published: April 2009

Following the tradition of past farewell messages, I will comment on the general health of physics; I also want to report, however, on a singular development that occurred during my term in office. This was the discovery of the new particles, an event that has generated a 20-year high in the level of excitement among high-energy physicists.
Light as a fundamental particle
Authors: Weinberg Steven
Published: April 2009

We take it pretty much for granted that the whole visible world of matter and radiation can be explained, if not in fact at least in principle, in terms of the interactions of a handful of so-called “elementary particles”: the electron; the proton; the neutron; the quantum of light, the photon; the quantum of gravitational radiation, the graviton, and perhaps also the neutrino. We would like to know why these particles have the properties they have, and therefore why the world is the way it is. Or, if you do not believe that scientists should ask “why,” you can restate the question in this form: What we want to know is the set of simple principles from which the properties of these particles, and hence everything else, can be deduced.
X-ray lasers
Authors: Chapline George , Wood Lowell
Published: April 2009

One of the great barriers to improving our understanding of the molecular basis of life is that we do not yet have any way of examining individual macromolecules in living tissue. The progress made so far in unravelling the structures of biological macromolecules is based on painstaking chemical and x-ray crystallographic analyses of pure, crystalline samples of a given macromolecule.1 This situation could, however, be completely revolutionized if a source of coherent x rays were available. Although, as we shall show below, the realizaton of this goal is beset with difficulties, experiments aimed towards its accomplishments are under way, as shown in figure 1.
Macroscopic yields by laser isotope separation
Authors: Rothenberg Marian S.
Published: April 2009

Laser separation has for the first time produced macroscopic amounts of isotopically enriched compounds of such elements as boron, chlorine and sulfur. Last fall experimenters at the Institute for Spectroscopy, Moscow1 and the National Bureau of Standards2 both described experiments on boron isotope separation from boron trichloride. An NBS group has also done work on separating chlorine isotopes. This past March the Moscow group reported their recent successes with sulfur. Shortly thereafter the Los Alamos Scientific Laboratory made public similar sulfur experiments. Results at all three places indicate that significant progress has been made since we last reported on laser isotope separation (PHYSICS TODAY, September 1974, page 17).
Ultrashort phenomena
Authors: Alfano Robert R. , Shapiro Stanley L.
Published: April 2009

Physicists and chemists have gained an impressive amount of new information on rapid phenomena in materials by using sophisticated new techniques for handling picosecond light pulses. The reason for the great growth of interest is not solely the development of new techniques for probing this time region, but also its importance for understanding the most fundamental processes in materials physics and chemistry. Since particle-collision rates within materials are rapid, the picosecond time scale is the appropriate gauge for a larger number of energy-transfer processes in substances.
Go and catch a falling neutron…
Authors: Lubkin Gloria B.
Published: April 2009

A team of experimenters has used a neutron interferometer to observe the quantum-mechanical phase shift of neutrons caused by their interaction with the Earth's gravitational field. The experiment is one of the first (if not the first) observations of the principle of equivalence for a quantum-mechanical system. The experimenters, who reported their work in Phys. Rev. Letters on 9 June, are Roberto Colella and Albert W. Overhauser (Purdue University) and Samuel A. Werner (Ford Motor Company).