bluuebunny/crossref_metadata_2025 huggingface dataset:
Josephson Detectors Make Astronomical Observations
Authors: Lubkin Gloria B.
Published: December 2008

Since the discovery of the Josephson effect, astronomers have been intrigued with the possibility of using junctions of two superconductors connected by a weak link to detect millimeter and submillimeter radiation from astronomical objects. Now Bruce T. Ulrich of the University of Texas has reported (at the American Astronomical Society meeting in New York last December) the first astronomical observations with a Josephson junction; he has observed the sun, moon and Venus. His group and other groups (at the University of California at Berkeley and at the State University of New York at Stony Brook) are testing several different ways of using Josephson-type junctions in hopes of improving sensitivity.
Physicists with unusual careers
Authors: Rothenberg Marian S.
Published: December 2008

PHYSICISTS are usually found working in physics laboratories and teaching in physics departments. But there are now, and probably always have been, people who complete their education in physics but pursue careers outside these traditional areas. And they are happy in these jobs.
MIT Tokomak Has Anomalous-Resistivity Heating and 130 kG
Authors: Lubkin Gloria B.
Published: December 2008

MIT has started design and construction of a high-field Tokomak-like device called “Alcator.” By extrapolation of experimental results, the experiment could achieve confinement times considerably longer than previous Tokomaks, electron temperatures of roughly 5 keV, and electron and ion densities of 1014 particles/cm3. These parameters are of thermonuclear interest and, if achieved would allow the study of plasmas with reactor-like characteristics.
No Sign Found in Search For Neutral Tachyons
Authors: Levi Barbara G.
Published: December 2008

While theorists debate whether tachyons are forbidden or compulsory (PHYSICS TODAY, December 1969, page 47), the search continues for these faster-than-light particles. Last year Torsten Alväger, Michael N. Kreisler and Michael B. Davis failed to find evidence for charged tachyons. Now Charles Baltay, Gerald Feinberg and Noel K. Yeh of Columbia, and Ralph Linsker of the Goddard Space Flight Center, have set an upper limit on the production of neutral tachyons.
Low-Field Room Built at High-Field Magnet Lab
Authors: Lubkin Gloria B.
Published: December 2008

A magnetically shielded walk-in room whose residual field is about 100 nanogauss is now operating at MIT's Francis Bitter National Magnet Laboratory. The room's designer, David Cohen, has recently reported using a point-contact “SQUID” (superconducting quantum interference device) inside the room to record the magnetic field of the human heart without noise averaging. Cohen also plans to use the room for ac and dc measurements of the magnetic field from the human brain; roughly the brain's field is 1 nanogauss and the heart's peak field is 1 microgauss.
Quests and Questions Concerning Quarks
Authors: Levi Barbara G.
Published: December 2008

Some seven months after the announcement of evidence for quarks by Charles B. A. McCusker and his colleagues at the University of Sydney, more evidence has come forth from a second experiment. William T. Chu and Young S. Kim of Ohio State University, W. J. Beam of Rose Polytechnic Institute and Nowhan Kwak of the University of Kansas claim to have observed one track that could be interpreted as a quark after examination of cosmic-ray tracks in 10 000 pictures exposed in the Argonne 40-inch heavy-liquid bubble chamber.
Antihelium Is Produced At Serpukhov Accelerator
Authors: Lubkin Gloria B.
Published: December 2008

Five nuclei of antihelium-3 have been made by Yuri Prokoshkin and his collaborators at the Serpukhov 76-GeV synchrotron, according to a front-page report in Pravda. The group bombarded an internal target with protons, defined the momentum of outgoing particles by magnets and measured velocity by time of flight. Out of 2×1011 negative pions detected by the counters, five particles had the right mass to be He3.
Shopping for a time-sharing service
Authors: Elkholy Hussein
Published: December 2008

SMALL COLLEGES, or the small users within large colleges or universities, have recently found that access to a computer is economically within their grasp through computer time-sharing services. Yet the inexperienced may ask how to go about acquiring a time-sharing system and how to decide among the options available from the many firms that now flood the market. I will attempt to answer these questions by describing how a small physics department such as ours, with a faculty who did not know anything about computers, has acquired both a small computer and a time-sharing system. Taking advantage of the competitive situation, we obtained time-sharing services well within our budget. We have introduced computer instruction and have made it an integral part of the physics and mathematics curricula.
The Wraps Come Off Continuous High-Power Lasers
Authors: Lubkin Gloria B.
Published: December 2008

The latest kind of pump for a laser is a rocket engine; such a gas-dynamic laser has produced continuous power of 60 kilowatts in multimode operation. Many had suspected that such high-power devices were being built, but the research was classified until the Washington APS meeting, where Edward Gerry of Avco-Everett Research gave an invited paper.
Principle for a Pi-Pi Collision Device Proposed
Authors: Lubkin Gloria B.
Published: December 2008

“Precetron” is the name for a new kind of storage and collision device proposed recently by Bogdan Maglic of Rutgers University and Robert Macek of the Los Alamos Meson Physics Facility (reported in the new Gordon and Breach journal Particle Accelerators, April 1970). Unlike the usual storage rings, which provide particle interactions through colliding beams of relatively high intensity, the precetron is a device in which particles interact over their entire orbit; the orbits themselves are precessing—hence the name Maglic and Macek told us that the new device would produce observable collision rates—up to 1000 per hour—with unstable particles (whose lifetimes are as short as 10−8 sec), in addition to low-intensity uncollimated stable-particle systems.
Interferometry with x rays
Authors: Hart Michael , Bonse Ulrich
Published: December 2008

IN THIS NEW BRANCH of applied x-ray optics, crystals that obey Bragg's law of reflection are used as optical components. The physics of these devices is very simple and has long been available in the works of, for example, Max von Laue and Paul Ewald. Construction and operation of x-ray interferometers, however, had to await the arrival of large, almost perfect, artificially grown single crystals. In the five years that have elapsed since the first successful x-ray interferometer was made only a few of the possible applications have been exploited.
Nuclear physics in medicine
Authors: Brownell Gordon L. , Shalek Robert J.
Published: December 2008

RADIATION THERAPY and radioisotope imaging have become as common to modern medicine as stethoscopes and hypodermic needles. They illustrate the impact that nuclear physics has had upon medical diagnosis and therapy. For example, the design of particle accelerators led to radiation treatment with increasingly higher energies. Nuclear reactors provided a wide variety of radioisotopes for nuclear medicine. Development of instruments such as the Anger camera have improved imaging techniques. At times, nuclear physicists themselves have decided to apply their skills to health-related areas, and an increasing number of young physicists are now entering this field.
Writing science for the public
Authors: Sullivan Walter
Published: December 2008

AS WRITERS for general and scholastic audiences are discovering, young people today are more alert to scientific developments than ever before, whereas their elders in many cases have an utterly defeatist attitude. How tired are science writers of effusive, middle-aged ladies who, trying to be kind, say: “What a fascinating job you have—of course I don't understand what you write about but…”
The new journals
Authors: Scott John T.
Published: December 2008

Every time you turn around it seems that someone has published a new physics journal. Announcements of new journals appear regularly in PHYSICS TODAY, publishers' solicitations crowd your mail box, librarians demand extra display space for current issues.
Experimenters vie for first crack at Batavia
Authors: Lubkin Gloria B.
Published: December 2008

With Robert R. Wilson's recent announcement that the Batavia accelerator might have a beam in mid-1971 and that a low-intensity beam of 500 GeV could be produced not long after (PHYSICS TODAY, June, page 29), high-energy physicists are clamoring for a chance at being first to use the new machine. A call for proposals brought more than 80 replies, enough for several years' worth of experiments. Edwin Goldwasser, deputy director of the National Accelerator Laboratory, told us that some time this month NAL may tentatively accept some of the proposals—those that require a university group to start work now so that it could be ready in summer or fall of 1972.
Quantum mechanics and reality
Authors: DeWitt Bryce S.
Published: December 2008

Despite its enormous practical success, quantum theory is so contrary to intuition that, even after 45 years, the experts themselves still do not all agree what to make of it. The area of disagreement centers primarily around the problem of describing observations. Formally, the result of a measurement is a superposition of vectors, each representing the quantity being observed as having one of its possible values. The question that has to be answered is how this superposition can be reconciled with the fact that in practice we only observe one value. How is the measuring instrument prodded into making up its mind which value it has observed?
Far-infrared spectroscopy
Authors: Rothschild Walter G. , Möller Karl D.
Published: December 2008

The far infrared is that uncomfortable region of the electromagnetic spectrum falling between 50 and 1000 microns (200 to 10 cm−1) where conventional infrared methods cease to be efficient while microwave techniques cannot yet be applied in a straightforward way. Spectroscopic work in the far infrared has been hampered by the unavailability of intense broad-band sources of radiation. Although promising developments in far-infrared laser emission may change this picture, the most useful source of far-infrared radiation is still the mercury arc lamp, which was originally used by Rubens in his pioneering work at the turn of the century. Infrared detectors are all seriously affected by thermal noise because they inherently respond to a wide range of frequencies.
Origins of cosmic rays
Authors: Cowsik Ramanath , Price P. Buford
Published: December 2008

Laymen are probably more aware of the spectacular recent discoveries in astrophysics than in any other science. Newspapers and magazines have conditioned their readers to accept the reality of quasars, pulsars, black holes, gravitational waves, 2.7-K blackbody radiation, interstellar molecules, solar wind and ancient moon rocks, to name only a few currently fashionable topics.
A parting look at the National Register
Authors: Barisch Sylvia
Published: December 2008

Physicists and astronomers, according to the 1970 National Register of Scientific and Technical Personnel

▸ earned a median salary of $15 900; $1900 higher than they earned two years earlier and $900 higher than the median for all scientists.

▸ had an unemployment rate, in early 1970, of 2.1%, compared with 1.6% for all scientists and 1.0% at the time of the previous (1968) Register. Unemployment was substantially lower for those with PhD's than for those who stopped with a master's.

▸ continue to work for educational institutions more than for any other kind of employer, and work at research and development more than at any other kind of activity.
Model for amorphous semiconductors predicts energy band gaps
Authors: Rothenberg Marian S.
Published: December 2008

How do amorphous semiconductors get their energy band gaps? Experimental results over the past few years have shown that amorphous silicon and germanium films have gaps between valence and conduction bands that are similar to the gaps that exist when these substances are crystalline. Efforts to justify these gaps theoretically bog down because of the lack of Bragg planes in amorphous substances; energy band gaps in crystals arise because of scattering by the planes, and most solid-state theorists have assumed that some kind of periodicity is needed to explain gaps.
Do second-class currents exist in beta decay?
Authors: Lubkin Gloria B.
Published: December 2008

Since Denys Wilkinson last year reopened the question of whether or not second-class currents exist in the weak interaction (physics today, September 1970, page 17), a flurry of theoretical and experimental activity has occurred. And the waters are muddier than ever now. Second-class currents are those that have the opposite behavior under G-parity as first-class currents. The G-parity operation is the product of charge conjugation and charge symmetry (which rotates the isotopic spin through 180 deg).
Simple technique produces photon echoes and optical nutation
Authors: Lubkin Gloria B.
Published: December 2008

A simple way to generate and study photon echoes, optical nutation, and other coherent optical effects has been developed by Richard G. Brewer and Richard L. Shoemaker (IBM Research Laboratory, San Jose). The work was reported by Brewer at the Esfahan (Iran) Symposium on Fundamental and Applied Laser Physics in September, and appears in Physical Review Letters (27, 631, 1971).
Toro makes a threesome with Earth and Moon
Authors: Lubkin Gloria B.
Published: December 2008

A small asteroid named Toro forms a triplet system with the Earth and the Moon, according to Hannes Alfvén (University of California, La Jolla and Royal Institute of Technology, Stockholm). The discovery, which was made by Lars Danielsson (Royal Institute of Technology) and W. H. Ip (La Jolla), is the first indication that another celestial body is part of the Earth-Moon system.
Two accelerators switch to nitrogen ions
Authors: Rothenberg Marian S.
Published: December 2008

Experiments with high-energy nitrogen ions have now been done at two accelerators that were formerly devoted only to elementary-particle physics. At the Princeton Particle Accelerator (PPA) a 3.9-GeV nitrogen beam was achieved on 15 July, and the Bevatron at the Lawrence Berkeley Laboratory (LBL) produced its 36-GeV beam on 17 August. Both laboratories can now produce beams of sufficient intensity (at least 105 particles per sec) to carry out experiments, and the broad range of scientists eager to use the energetic heavy ions includes biologists, nuclear chemists, astrophysicists, solid-state physicists and high-energy physicists.
Theory of early universe explains particle production
Authors: Lubkin Gloria B.
Published: December 2008

If the early universe had a strongly time-dependent gravitational field, the field would have created pairs of particles, according to Ya. B. Zel'dovich (Institute of Applied Mathematics, USSR Academy of Sciences). This mechanism might explain the existence of particles in the universe, and it offers the hope of understanding why the present ratio of photons to baryons in the universe is 108.
Recollections of Rutherford and the Cavendish
Authors: Devons Samuel
Published: December 2008

A cat may look at a king, and in Cambridge in the 1930's there were many kings—eminent, renowned or celebrated in the sphere of learning and yet in Cambridge quite homely figures. Cambridge was their home, as it was ours, the lowly undergraduates. There was Hardy the “pure” mathematician, Housman the scholar-poet, Keynes the economist, Gowland-Hopkins the “father” of biochemistry, Wittgenstein the iconoclast of philosophy, Eddington, Dirac and many others. We might only occasionally see, and seldom hear, these illustrious individuals, but their presence gave us a sense of living in history. Education at Cambridge seemed, then, to be more a matter of inspiration by example than instruction by precept.
Solid-state physicists and metallurgy
Authors: Schmitt Roland W.
Published: December 2008

Are there good problems for solid-state physicists in metallurgy? I believe so, both from the physicist's and the metallurgist's point of view. On the one hand are the important unresolved scientific questions, and on the other are industry's needs for special materials. A brief survey of the ways physicists can help those who study the uses of metals will show an underlying theme. Metallurgists need theories that can help them generalize from diverse experimental data without depending on detailed quantum-mechanical models; they need phenomenological theories.
Amino acids in both moon and meteorite
Authors: Lubkin Gloria B.
Published: December 2008

The discovery of more and more complex molecules in outer space over the past two years has perhaps hardened us to such reports. But now comes the announcement that five amino acids have been found in a meteorite that fell (trajectory unknown) near Murchison, Victoria, Australia on 28 September 1969. Last year two groups had found some indication of two amino acids in samples from Apollo 11 and 12. Thus one more link in the chain of chemical evolution appears to have been forged.
Opportunities in geophysics
Authors: Crane H. Richard
Published: December 2008

What are the chances of a physicist finding an agreeable job in geophysics? The apparently poor prospects for jobs in academic physics led me to explore the possibilities in geophysics; this field, I guessed, is less dependent on government funds than is academic physics and should not have suffered the same kinds of cutbacks. For my survey of opportunities, I gleaned information from James T. Wilson, a seismologist, geologist and director of the University of Michigan Institute of Science and Technology; Helmut Landsberg of the University of Maryland, a past president of the American Geophysical Union; Homer Newell of the National Aeronautics and Space Administration, now the AGU president; Milton Dobrin, president of the Society of Exploration Geophysicists and Richard Geyer, head of the department of oceanography at Texas A&M University. Here is a digest of what I learned.
Mössbauer spectroscopy and biophysics
Authors: Johnson Charles E.
Published: December 2008

The emission and resonant reabsorption of low-energy gamma rays in recoilless nuclear transition offers a convenient way to study biochemical reactions. Biological molecules frequently have a transition-metal atom, such as iron, at the reactive site, and the Fe57 nucleus is particularly well suited for precise gamma-ray spectroscopy. By comparing the Mössbauer spectra of two different forms of one of these molecules, for example the oxidized and reduced forms, we learn something about the electron transfer that takes place in biological systems.
Lifetime of heliumlike metastable ions measured
Authors: Scott John T.
Published: December 2008

To an atomic physicist the 23S state of helium represents the classic metastable state. Lying nearly 20 eV above the 11S ground state, it can not emit radiation and drop to the ground state without violating the selection rules that an S state can not decay to an S state and terms of different multiplicities do not combine (that is, triplet states do not decay to singlet states). Usually, helium excited into this metastable state stays there until a collision with another atom or with a wall allows it to drop down; if neither an atom nor a wall obliges soon enough, the state will eventually decay by some “forbidden transition” that violates the selection rules. (Such a situation probably arises for helium atoms in planetary nebulae.) All this is true also for other members of the helium isoelectronic sequence—atoms or ions with but two electrons.
“Minirings” would allow many pi-pi collisions
Authors: Lubkin Gloria B.
Published: December 2008

A storage device in which particles collide over their entire orbit can be used for pi-pi collision experiments, according to Paul L. Csonka of the University of Oregon. Such devices have been talked about for several years. Csonka's apparatus, which he calls a “miniring,” could, for example, be used with a proposed proton storage ring at the Los Alamos Meson Physics Facility, to give 10 to 70 events per hour. Doing a conventional colliding-beam experiment with two pion beams, one would have to wait ten million years to see an event.
Laser-induced reaction separates isotopes
Authors: Rothenberg Marian S.
Published: December 2008

The first successful use of a laser to separate isotopes has been carried out at the Aerospace Corp. laboratories in El Segundo, Calif. S. W. Mayer, Munson A. Kwok, R. W. F. Gross and Donald J. Spencer used a high-power hydrogen-fluoride laser to separate methanol (H3COH) from deuteromethanol (D3COD), selectively exciting the methanol to react with bromine. The method, although not now economically practical (it uses more power per milligram of deuterium produced than do existing methods), gives encouraging results: The mixture of products includes less than five percent methanol and about 95% deuteromethanol, whereas the original mixture contained equal amounts of the two compounds.
Panel discussions: Is there any hope?
Authors: Leighton Robert B.
Published: December 2008

Recently at a meeting of a scientific society I found myself listening to a panel discussion ostensibly devoted to give-and-take discussion of a certain topic dear to my heart. I have attended—and participated in—several such discussions, and have usually found them less helpful than one would wish. I had never understood the reason for this, but, as I listened, something said by one of the panelists struck a responsive chord inside me. I soon recognized the deep truth of what he said, and a whole host of previous panel experiences were thereby illuminated.
Quantum-mechanics debate
Authors: Ballentine Leslie E. , Pearle Philip , Walker Evan Harris , Sachs Mendel , Koga Toyoki , Gerver Joseph , DeWitt Bryce
Published: December 2008

“Despite its enormous practical success, quantum theory is so contrary to intuition that, even after 45 years, the experts themselves still do not agree what to make of it…” noted Bryce DeWitt at the start of his September 1970 physics today article, “Quantum mechanics and reality.” His attempt to resolve the indeterminism question has resulted in a series of letters that appear to prove his opening statement right.
Element 112 evidence starts a rush on proton beam stops
Authors: Lubkin Gloria B.
Published: December 2008

Suppose you bombard a tungsten target with very high-energy protons. Sometimes a tungsten nucleus might receive enough energy to climb the Coulomb barrier in a second tungsten nucleus and produce some superheavy nucleus. That was the hypothesis of Amnon Marinov (on leave from Hebrew University at the Rutherford High Energy Laboratory) and his collaborators, C. J. Batty and A. I. Kilvington (Rutherford), G. W. A. Newton and V. J. Robinson (University of Manchester) and J. D. Hemingway (Universities Research Reactor, Risley, Lancashire), who examined two tungsten beam stops from the CERN proton synchrotron. After studying their alpha-decay properties and also observing spontaneous fission, they concluded that they may have observed production of element 112 by secondary reactions in tungsten targets irradiated by 24-GeV protons (Nature 229, 464, 1971).
Quark search gets help from Millikan
Authors: Lubkin Gloria B.
Published: December 2008

Every once in a while in discussions about quarks, you hear the old story that Millikan occasionally saw fractional charges while doing his oil-drop experiment. Now William Fairbank and Arthur Hebard at Stanford University are repeating the experiment, replacing the oil drop with a superconducting niobium ball. They hope to improve the chance of finding a fractional charge because the probability of finding such a charge is proportional to the mass of the sphere. Their sphere has a mass of 7×10−5 grams, in contrast to a typical Millikan oil drop of 3×10−11 grams.
1000 GeV with superconducting magnets at Batavia?
Authors: Rothenberg Marian S.
Published: December 2008

With a modest extension the Batavia accelerator may be able to produce 1000-GeV protons, double the expected 500-GeV maximum, according to National Accelerator Laboratory director Robert R. Wilson. On 9 March Wilson told the Joint Congressional Committee on Atomic Energy how a relatively inexpensive device ($10–20 million) consisting of small-bore superconducting magnets could act as an “energy doubler” that would pay for itself within the first few years of operation.
AIP annual report: 1970
Authors: Koch H. William
Published: December 2008

Service to the individual physicist has always been central to the aims of the American Institute of Physics throughout its 40-year history of service to its member societies. Yet the year 1970 saw an even stronger dedication to the needs of the physicists in AIP's family. The particular problems uppermost during the year can be summarized as “too much and too few”—too much physics literature (the “information explosion”) and too few employment opportunities.
Quasars are relatively local. Except those that are not
Authors: Scott John T.
Published: December 2008

How far away are the quasars? Either they are at cosmological distances, moving at a substantial fraction of the velocity of light—if you believe that their enormous red-shifts are of a piece with the general Hubble recession of the galaxies; or they are comparatively local—if you worry about their extraordinary luminosity and short-term variability. Each viewpoint has its own adherents; each adherent has a persuasive argument.
Long-lived kaon shows no 2-muon decay
Authors: Lubkin Gloria B.
Published: December 2008

The mysterious long-lived K meson has produced another surprise. An experiment to look for KL0→μ+μ− has failed to find any such decays and has established an upper limit to the branching ratio (for two-muon decay compared to all decays) of 1.82×10−9, with a 90% confidence level. Straightforward theoretical estimates had predicted a branching ratio of about 10−8, but in any case a fairly plausible lower bound of 6×10−9, more than three times larger than the experimental upper limit. The experiment was done at the Berkeley Bevatron by Alan Clark, Tom Elioff, Clive Field, Henry Frisch, Rolland Johnson, Leroy Kerth and William Wenzel, all of Lawrence Radiation Laboratory, Berkeley (Phys. Rev. Lett., 28 June).
How does the muon differ from the electron?
Authors: Perl Martin L.
Published: December 2008

One of the great puzzles of elementary-particle physics is how to understand the relationships between the muon and the electron. The set of properties that the muon and electron possess in common are collectively described by the phrase “muon–electron universality.” This set is large and comprises most of the properties of the muon and electron; see Table 1, page 44.
Improved Lamb-shift experiments
Authors: Rothenberg Marian S.
Published: December 2008

Precise measurement of the Lamb shift, the difference δ in energy between the S1/2 and P1/2 levels in single-electron atoms and ions, is a basic test of quantum electrodynamics. Several factors limit the accuracy of experimental determinations of δ; the most important are difficulties of measuring the resonance-line center, uncertainty about the velocity distribution of the atoms, and systematic errors, such as Stark-effect shifts, caused by the applied electromagnetic fields.
Solution of eight-vertex model excites critical-point theorists
Authors: Lubkin Gloria B.
Published: December 2008

A difficult problem in two-dimensional statistical mechanics has been solved by R. J. Baxter of the Australian National University in Canberra (Phys. Rev. Lett. 26, 832, 1971). The so-called “eight-vertex” model that he solved contains as special cases the square lattice Ising, dimer, ice, F and KDP (potassium dihydrogen phosphate) models. Baxter's elegant and beautiful solution has challenged one of the widely held precepts of critical-point theory, namely that the character of the critical behavior is independent of the substance provided the symmetry properties of the Hamiltonian are the same.
Neutrino search to go deep undersea?
Authors: Lubkin Gloria B.
Published: December 2008

A group of physicists, oceanographers and oceanographic engineers is studying the possibility of using the oceans to detect neutrinos originating in Earth's atmosphere and beyond. The group, which has organized itself under the acronym DUMAND (Deep Underseas Muon and Neutrino Detector), is now planning a second summer workshop this year.
Thermodynamic and transport properties of the Weeks–Chandler–Andersen fluid: Theory and computer simulation
Authors: Eskandari Nasrabad Afshin
Published: December 2008

The equilibrium molecular dynamics (MD) simulation method is utilized to compute the equation of state, pair correlation function, and transport coefficients of the Weeks–Chandler–Andersen model fluid over a wide range of densities and temperatures. The calculated pair correlation function is used within the virial minimization method to obtain the effective diameter and the results are applied within the generic van der Waals (GvdW) theory to compute the GvdW parameters. The GvdW parameter B, which corresponds to the mean excluded volume of particles, is used to calculate the mean free volume. The computed effective diameter and Gvdw parameters are then fitted to functions of the density and temperature. The modified Cohen–Turnbull theory is employed to calculate the diffusion coefficient using the computed effective diameter and mean free volume. A detailed analysis is presented for the results of the theory and MD simulations for the diffusion coefficient. The system-size dependence of the diffusion coefficient through the MD simulation is studied. The Dullien formula is used to obtain the shear viscosity and the results are compared with those from MD simulations.
Corrections
Authors: Finkelstein David
Published: December 2008

Following are corrections I have received to my review of Pimenov's book (April 1972):

Einstein did not find differential geometry “ready for him.” He had reinvented half of it before hearing of its existence.

Signals may propagate in Pimenov's semi-Riemannian spaces with arbitrarily high velocity, never “instantaneously.”

The index for which “the work pleads” was present in the original Russian.

Pimenov's imprisonment is not the result of any publication but merely of preliminaries to publication.
Influence of the preparation conditions on the morphology of perylene thin films on Si(111) and Si(100)
Authors: Casu M. B. , Yu X. , Schmitt S. , Heske C. , Umbach E.
Published: December 2008

Thin films of perylene on Si(111) and Si(100) substrates have been investigated using a variety of experimental techniques. We find that the structural and morphological properties as well as the growth modes strongly depend on the preparation parameters. In general, we observe the existence of a relatively weak coupling between perylene and the two single crystal substrates. However, under special preparation conditions, it is possible to obtain a multilayer phase on the Si(111) substrate that is characterized by flat-lying, parallel-oriented molecules, and strong coupling with the substrate in the first layer. This phase has different structural, electronic, and intermolecular bonding properties as compared to the known crystalline phases. On Si(100), by varying the deposition rate between 0.1 and 10 nm/min, it is possible to observe a transition from island growth mode, with large and isolated crystallites, to homogeneous film growth. These findings contribute to the basic knowledge for film engineering. Thus, the film morphology could be designed ranging from the growth of very large single grains suitable for a complete nanodevice to homogenous films for application in large displays.
Photoelectron imaging of atomic chlorine and bromine following photolysis of CH2BrCl
Authors: Hua Linqiang , Shen Huan , Hu Changjin , Zhang Bing
Published: December 2008

Photoionization of chlorine and bromine atoms following photodissociation of CH2BrCl was studied in the wavelength range of 231–238 nm by photoelectron imaging technique. Final state-specific speed and angular distributions of the photoelectron were recorded. Analysis of relative branching ratios to different levels of Cl+ and Br+ revealed that the final ion level distributions are generally dominated by the preservation of the ion-core configuration of the intermediate resonant state. Some Jc numbers of the intermediate states were newly assigned according to this regulation. The configuration interaction between resonant states and the autoionization in the continuum were also believed to play an important role in the ionization process since some ions that deviate from the regulation mentioned ahead were observed. The angular distributions of the electrons were found to be well characterized by β2 and β4, although the ionization process of chlorine and bromine atoms involves three photons.
Electron hole–phonon interaction, correlation of structure, and conductivity in single crystal La0.9Sr0.1FeO3−δ
Authors: Braun A. , Richter J. , Harvey A. S. , Erat S. , Infortuna A. , Frei A. , Pomjakushina E. , Mun Bongjin S. , Holtappels P. , Vogt U. , Conder K. , Gauckler L. J. , Graule T.
Published: December 2008

The conductivity and structure of the hole-doped polaron conductor La0.9Sr0.1FeO3−δ are reported for elevated temperatures. The conductivity increases exponentially with temperature to a maximum and decreases for T>700K following a power law, accompanied by a shift of spectral weight in the photoemission valence band. The conductivity decrease is accompanied by a phase transformation, due to the reduction of Fe, as evidenced by x-ray absorption spectra. Additional fine structures in the conductivity are correlated with a strong decrease in valence band intensity near EF and with the onset of a corresponding structural transition.
Broadening of the plasmon resonance due to plasmon-plasmon intermode scattering in terahertz high-electron-mobility transistors
Authors: Popov V. V. , Polischuk O. V. , Knap W. , El Fatimy A.
Published: December 2008

We calculate the terahertz absorption spectrum of the high-electron-mobility transistor with a short gate and long ungated channel regions and show that the main contribution to the linewidth of the gated plasmon resonance can be attributed to the plasmon-plasmon intermode scattering. The results allow interpreting recent experimental results on resonant terahertz detection by InGaAs nanotransistors. The physics of the plasmon-plasmon intermode scattering is discussed and efficiency of this process is quantitatively compared to the other possible plasmon damping mechanisms.
Fraunhofer regime of operation for superconducting quantum interference filters
Authors: Shadrin A. V. , Constantinian K. Y. , Ovsyannikov G. A. , Shitov S. V. , Soloviev I. I. , Kornev V. K. , Mygind J.
Published: December 2008

Series arrays of superconducting quantum interference devices (SQUIDs) with incommensurate loop areas, so-called superconducting quantum interference filters (SQIFs), are investigated in the kilohertz and the gigahertz frequency range. In SQIFs made of high-Tc bicrystal junctions the flux-to-voltage response ∂V/∂Φ is dominated by the variation in the critical current in the individual junctions (Fraunhofer-type) rather than by the SQUIDs interference. For a SQIF with 20 SQUID loops we find ∂V/∂Φ=40 mV/Φ0 and a dynamic range of more than 60 dB in the kilohertz range. In the 1–2 GHz range the estimated power gain is 20 dB and the magnetic flux noise level is as low as 10−4Φ0.
Influence of the contact metal on the performance of n-type carbonyl-functionalized quaterthiophene organic thin-film transistors
Authors: Schols S. , Van Willigenburg L. , Müller R. , Bode D. , Debucquoy M. , De Jonge S. , Genoe J. , Heremans P. , Lu S. , Facchetti A.
Published: December 2008

Organic thin-film transistors using 5, 5‴-diperfluorohexylcarbonyl-2,2′:5′,2″:5″,2‴-quaterthiophene (DFHCO-4T) as the electron conducting organic semiconductor are fabricated and the performance of these transistors with different top-contact metals is investigated. Transistors with Au source-drain top contacts attain an apparent saturation mobility of 4.6 cm2/V s, whereas this parameter is 100 times lower for similar transistors with Al/LiF top contacts. We explain this lower performance by the formation of a thin interfacial layer with poor charge injection properties resulting from a redox reaction between Al and DFHCO-4T.
Neutron stars grow magnetic whiskers
Authors: Lubkin Gloria B.
Published: December 2008

It is generally agreed that neutron stars or pulsars have enormous magnetic fields at their surface—in the range 1012–1013 gauss. Mal Ruderman of Columbia University has considered (Phys. Rev. Lett. 27, 1306, 1971) what happens to ordinary matter in such fields. He concludes that the surface of the neutron star is not a gas but condensed matter arranged in whiskers of atoms. “Neutron stars have hair,” he explains.
More power and smoother surface for Arecibo dish
Authors: Hein Steven M.
Published: December 2008

The National Astronomy and Ionosphere Center at Cornell, which runs the Arecibo Observatory in Puerto Rico, is planning a series of improvements in the radio-telescope radar system which, according to director Frank Drake, are expected to raise its sensitivity by a factor of 2000. Drake said that the upgrading program will enable the center to make radar maps of Venus with a resolution of about 1 km—comparable to the best currently-available earth-based maps of the moon—and to map Mercury, Mars and the major satellites of Jupiter.
Red-shift problem intensifies, says Burbidge
Authors: Lubkin Gloria B.
Published: December 2008

Since the discovery of quasistellar objects people have debated whether their large redshifts are of cosmological origin or not. Last year a report by Irwin Shapiro and his collaborators implied that quasar 3C 279 was a comparatively local object, while a report by James Gunn suggested that PKS 2251-11 was at a cosmological distance corresponding to a red shift of 0.32 (PHYSICS TODAY, July 1971, page 13).
Progress in holography
Authors: Leith Emmett N. , Upatnieks Juris
Published: December 2008

With the award of the 1971 Nobel prize in physics to Dennis Gabor, holography has reached a new pinnacle of prestige. Gabor won his prize for the invention of holography, a form of wavefront reconstruction in which a coherent reference wave appears to unlock a three-dimensional replica of an object from a two-dimensional standing-wave pattern.
Two new lasers share short-wavelength record
Authors: Scott John T.
Published: December 2008

The shortest-wavelength laser light yet obtained has been produced by stimulated emission in the molecular-hydrogen Werner bands. These 1160–1240-å transitions in the vacuum ultraviolet correspond to photon energies of about 10 eV, which are suitable for photochemical, photodissociation and photoionization experiments in most molecules. Lasers with output in this frequency range have been reported independently and nearly simultaneously by two different groups—Ronald W. Waynant of the Naval Research Laboratory, and Rod Hodgson and Russell Dreyfus of the IBM Thomas J. Watson Research Center. Both publications are in the 28 February issue of Physical Review Letters (pages 533 and 536 respectively).
Predictions for superheavy nuclei
Authors: Nix James Rayford
Published: December 2008

A frantic search for nuclei considerably heavier than any known up to now has been going on for the past five years. The search for these “superheavy” nuclei has included attempts to produce them artificially, as products of various reactions at accelerators throughout the world, as well as attempts to find them in nature. Man's quest in nature has led him from a 14th-century Russian Orthodox church to the ocean floor off the Fiji Islands, from California platinum and gold mines to meteorites and moon rocks. None of these attempts have yet resulted in any conclusive evidence for the existence of superheavy nuclei. But with the Berkeley Super-HILAC now joining accelerators in the USSR and France that are potentially capable of producing them, the coming years will witness a renewed search for these nuclei, whose existence was predicted seven years ago.
Energy from breeder reactors
Authors: Culler Floyd L. , Harms William O.
Published: December 2008

Within the next 30 years we will call upon our resources and technology to supply more energy than has been consumed throughout all history. Population pressures, the necessity for increased living standards in the underdeveloped nations, the demands of material affluence in the technological societies, the need to improve management of our dwindling natural resources and to protect our environment will force energy demand to unprecedented levels.
Gravity waves attract theories and experiments
Authors: Lubkin Gloria B.
Published: December 2008

The recent announcement in the popular press that an Israeli group had graound gravitational waves coming from the pulsar is just the tip of the gravitational iceberg. Since Joseph Weber's report in 1969 that he had observed gravitational waves at 1661 Hz, more and more experimenters have been peparing their own experiments to observe the waves. And theorists have been busy trying to explain what sort of source will produce gravitational waves.
Multimirror infrared telescope planned
Authors: Hein Steven M.
Published: December 2008

The University of Arizona and the Smithsonian Astrophysical Observatory are collaborating to build a large optical-infrared multimirror telescope. The telescope will have a light-collecting area equal to that of a conventional 176-inch telescope, but will consist of six 72-inch telescopes mounted on a common framework in a hexagonal array around a common axis with their images combined on this axis through two plane-mirror reflections. The six-barreled tube structure will be supported in an altitude–azimuth geometry and will be located at SAO's Mt. Hopkins station (elevation 8500 ft), 40 miles south of Tucson, Arizona.
Science and the worldview
Authors: Dart Francis E.
Published: December 2008

One evening not long ago I stood in the Nepalese town of Panga talking with a group of its citizens. For two hours or more I had been inquiring about their views of nature and of man's relation to nature, and our discussion had ranged widely over the world of familiar phenomena from rice planting to cosmology, from rainbows to moon and planets. Now as I was about to leave, we had stepped out into an enchantingly beautiful night. The houses across the square and the temple at its center were silhouetted against a brilliantly jewelled velvet black sky. Here and there a little mustard-oil lamp offered a flickering challenge to the darkness, but there was no glare of street light or neon sign. Now and then a child's voice or the murmur of a conversation somewhere accentuated the quiet of the night, but there was no sound of vehicles or sirens or other machines of civilization, and we stood silent ourselves while enjoying the night. Just as I turned to leave, a bright “Echo” satellite appeared from behind the pagoda and swept in a slow silent arc across the sky. We watched it for several moments before I took leave and departed for my lodgings in the city.
Infrared interferometer to measure size and shape of stars
Authors: Lubkin Gloria B.
Published: December 2008

A new high-resolution device for infrared astronomy is being developed at the University of California at Berkeley by Charles Townes and his collaborators, Michael Johnson, Albert Betz and Daniel Galehouse. Applying the new Techniques of quantum electronics to a concept originated by Albert A. Michelson, they have built the first infrared stellar interferometer. Townes expects an angular resolution to be orders of magnitude greater than that of an ordinary telescope. It will be used to measure the size and shape of stars and other astronomical objects.
Three US proposals for heavy-ion accelerator
Authors: Lubkin Gloria B.
Published: December 2008

A special evening session on heavyion accelerators was held during the Washington APS meeting to discuss three proposals to build such machines—at Argonne National Laboratory, Oak Ridge National Laboratory and Los Alamos Scientific Laboratory. Although over the years many proposals have been put forth, the field in the US appears to have narrowed down to the three discussed at the meeting.
Fine-structure components of Hα line resolved
Authors: Lubkin Gloria B.
Published: December 2008

Using high-resolution saturation spectroscopy, Theodore Hänsch, I. S. Shahin and Arthur Schawlow of Stanford University have been able to resolve for the first time single fine-structure components of the red Balmer line Hα of atomic hydrogen and to observe the Lamb shift directly in the optical absorption spectrum.
Physics in perspective
Authors: Bromley D. Allan
Published: December 2008

Early in 1969, and as a consequence of extended discussions within and among the Committee on Science and Public Policy of the National Academy of Sciences, the Division of Physical Sciences of the National Resarch Council, the Office of Science and Technology, the President's Science Advisory Committee and several of the major federal agencies that support physics, a decision was reached to initiate a survey of the US physics enterprise. The completed report of the Survey Committee will soon be available. (See box on this Pagefor table of contents.)
Pumping by chemical means
Authors: Tom Theodore
Published: December 2008

The need for a vacuum environment has been encountered by more and more fields over the years. In high-energy accelerators, extraneous molecules would attenuate the beam of particles being accelerated. In mass spectrometers, atmospheric gases would mask the sample being analyzed. In thin-film production, impurities would affect the electrical properties of the film being deposited. Similar considerations arise in the fields of space simulation, surface physics, thermonuclear research, pollution detection and control, analytical instrumentation and many others.
France and Germany share their thermal-neutron reactor
Authors: Rothenberg Marian S.
Published: December 2008

Unlike most tools of experimental condensed-matter physics, powerful sources of thermal neutrons demand a high initial investment, and the expense may be too great for a single nation. At the Institut Laue-Langevin, Grenoble, the French and German governments have solved the problem by sharing the costs of their new high-flux research reactor. The project, which will provide the highest external flux of thermal neutrons available, is moving from the construction to the experiment stage, and Rudolf Mössbauer has recently been appointed director of the Institute.
Vibrational lifetimes in liquids
Authors: Lubkin Gloria B.
Published: December 2008

For the first time the vibrational population lifetime of simple normal modes of polyatomic molecules in liquids has been directly measured, according to the experimenters, Alfred Laubereau, Dietrich von der Linde and Wolfgang Kaiser (Munich Technical University). Earlier the vibrational dephasing lifetime in both liquids and solids had been measured by the Munich group, who studied polyatomic molecules in liquids and lattice vibrations in diamond, and by Robert Alfano and Stanley Shapiro (General Telephone and Electronics), who measured lattice vibration lifetimes in calcite and molecular vibrational lifetimes in liquid nitrogen. Some observers believe that the technique opens a new field for the study of molecular relaxations in liquids and optical phonon relaxations in solids.