Laser Points to the Future at Palomar

PALOMAR MOUNTAIN, Calif. — The Hale Telescope on Palomar Mountain has been gathering light from the depths of the universe for 55 years. It finally sent some back early last week as a team of astronomers from the California Institute of Technology, the Jet Propulsion Laboratory and the University of Chicago created an artificial star by propagating a 4-watt laser beam out from the Hale Telescope and up into the night sky.

The laser was propagated as the first step in a program to expand the fraction of sky available to the technique known as adaptive optics. Adaptive optics allows astronomers to correct for the fuzzy images produced by earth's moving atmosphere, giving them a view that often surpasses those of smaller telescopes based in space.

"We have been steadily improving adaptive optics using bright natural guide stars at Palomar. As a result, the system routinely corrects for atmospheric distortions. Now we will be able to go to the next step," says Richard Dekany, associate director for development at Caltech Optical Observatories. Currently astronomers at Palomar can use the adaptive-optics technique only if a moderately bright star is sufficiently close to their object of interest. The adaptive-optics system uses the star as a source by which astronomers monitor and correct for the distortions produced by earth's atmosphere.

Employing the laser will allow astronomers to place an artificial corrective guide star wherever they see fit. To do so, they shine a narrow sodium laser beam up through the atmosphere. At an altitude of about 60 miles, the laser beam makes a small amount of sodium gas glow. The reflected glow from the glowing gas serves as the artificial guide star for the adaptive-optics system. The laser beam is too faint to be seen except by observers very close to the telescope, and the guide star it creates is even fainter. It can't be seen with the unaided eye, yet it is bright enough to allow astronomers to make their adaptive-optics corrections.

The Palomar Observatory currently employs the world's fastest astronomical adaptive optics system on its 200-inch Hale Telescope. It is able to correct for changes in the atmosphere 2,000 times per second. Astronomers from Caltech, JPL, and Cornell University have exploited this system to discover brown dwarf companions to stars, study the weather on a moon of Saturn, and see the shapes of asteroids.

"This is an important achievement that brings us one step closer to our goal," says Mitchell Troy, the adaptive optics group lead and Palomar adaptive optics task manager at the Jet Propulsion Laboratory. The goal, achieving adaptive-optics correction using the laser guide star, is expected next year. This will place Palomar in elite company as just the third observatory worldwide to deploy a laser guide system. This laser will greatly expand the science performed at Palomar and pave the way for future projects on telescopes that have not yet been built.

"This is a terrific technical achievement which not only opens up a bold and exciting scientific future for the venerable 200-inch telescope, but also demonstrates the next step on a path toward future large telescopes such as the Thirty Meter Telescope, " says Richard Ellis, Steele Family Professor of Astronomy and director of the Caltech Optical Observatories. "The next generation of large telescopes requires sodium laser guide-star adaptive-optics of the type being demonstrated at Palomar Observatory," he adds.

Currently in the design phase, the Thirty Meter Telescope (TMT) will eventually deliver images at visible and infrared wavelengths 12 times sharper than those of the Hubble Space Telescope. The TMT project is a collaboration between Caltech and the Associated Universities for Research in Astronomy, the Association of Canadian Universities for Research in Astronomy, and the University of California.

The Caltech adaptive optics team is made up of Richard Dekany (team leader) and Viswa Velur, Rich Goeden, Bob Weber, and Khanh Bui. Professor Edward Kibblewhite, University of Chicago, built the Chicago sum-frequency laser used in this project. The JPL Palomar adaptive optics team includes Mitchell Troy (team leader), Gary Brack, Steve Guiwits, Dean Palmer, Jennifer Roberts, Fang Shi, Thang Trinh, Tuan Truong and Kent Wallace. Installation of the laser at the Hale Telescope was overseen by Andrew Pickles, Robert Thicksten, and Hal Petrie of Palomar Observatory, and supported by Merle Sweet, John Henning, and Steve Einer.

The Palomar adaptive optics instrument was built and continues to be supported by the Jet Propulsion Laboratory as part of a Caltech-JPL collaboration.

Support for the adaptive-optics research at Caltech's Palomar Observatory comes from the Gordon and Betty Moore Foundation, the Oschin Family Foundation, and the National Science Foundation Center for Adaptive Optics.

Writer: 
Jill Perry
Writer: 

CBI Reveals Motion in the Remotest Seeds of Galaxy Clusters in the Very Early Universe

PASADENA, Calif.--Cosmologists from the California Institute of Technology have used observations probing back to the remote epoch of the universe when atoms were first forming to detect movements among the seeds that gave rise to clusters of galaxies. The new results show the motion of primordial matter on its way to forming galaxy clusters and superclusters. The observations were obtained with an instrument high in the Chilean Andes known as the Cosmic Background Imager (CBI), and they provide new confidence in the accuracy of the standard model of the early universe in which rapid inflation occurred a brief instant after the Big Bang.

The novel feature of these polarization observations is that they reveal directly the seeds of galaxy clusters and their motions as they proceeded to form the first clusters of galaxies.

Reporting in the October 7 online edition of Science Express, Caltech's Rawn Professor of Astronomy, and principal investigator on the CBI project, Anthony Readhead and his team say the new polarization results provide strong support for the standard model of the universe as a place in which dark matter and dark energy are much more prevalent than everyday matter as we know it, which poses a major problem for physics. A companion paper describing early polarization observations with the CBI has been submitted to the Astrophysical Journal.

The cosmic background observed by the CBI originates from the era just 400,000 years after the Big Bang and provides a wealth of information on the nature of the universe. At this remote epoch none of the familiar structures of the universe existed--there were no galaxies, stars, or planets. Instead there were only tiny density fluctuations, and these were the seeds out of which galaxies and stars formed under the hand of gravity.

Instruments prior to the CBI had detected fluctuations on large angular scales, corresponding to masses much larger than superclusters of galaxies. The high resolution of the CBI allowed the seeds of the structures we observe around us in the universe today to be observed for the first time in January 2000.

The expanding universe cooled and by 400,000 years after the Big Bang it was cool enough for electrons and protons to combine to form atoms. Prior to this time photons could not travel far before colliding with an electron, and the universe was like a dense fog, but at this point the universe became transparent and since that time the photons have streamed freely across the universe to reach our telescopes today, 13.8 billion years later. Thus observations of the microwave background provide a snapshot of the universe as it was just 400,000 years after the Big Bang--long before the formation of the first galaxies, stars, and planets.

The new data were collected by the CBI between September 2002 and May 2004, and cover four patches of sky, encompassing a total area three hundred times the size of the moon and showing fine details only a fraction of the size of the moon. The new results are based on a property of light called polarization. This is a property that can be demonstrated easily with a pair of polarizing sunglasses. If one looks at light reflected off a pond through such sunglasses and then rotates the sunglasses, one sees the reflected light varying in brightness. This is because the reflected light is polarized, and the polarizing sunglasses only transmit light whose polarization is properly aligned with the glasses. The CBI likewise picks out the polarized light, and it is the details of this light that reveal the motion of the seeds of galaxy clusters.

In the total intensity we see a series of peaks and valleys, where the peaks are successive harmonics of a fundamental "tone." In the polarized emission we also see a series of peaks and valleys, but the peaks in the polarized emission coincide with the valleys in the total intensity, and vice versa. In other words, the polarized emission is exactly out of step with the total intensity. This property of the polarized emission being out of step with the total intensity indicates that the polarized emission arises from the motion of the material.

The first detection of polarized emission by the Degree Angular Scale Interferometer (DASI), the sister project of the CBI, in 2002 provided dramatic evidence of motion in the early universe, as did the measurements by the Wilkinson Microwave Anisotropy Probe (WMAP) in 2003. The CBI results announced today significantly augment these earlier findings by demonstrating directly, and on the small scales corresponding to galaxy clusters, that the polarized emission is out of step with the total intensity.

Other data on the cosmic microwave background polarization were released just two weeks ago by the DASI team, whose three years of results show further compelling evidence that the polarization is indeed due to the cosmic background and is not contaminated by radiation from the Milky Way. The results of these two sister projects therefore complement each other beautifully, as was the intention of Readhead and John Carlstrom, the principal investigator of DASI and a coauthor on the CBI paper, when they planned these two instruments a decade ago.

According to Readhead, "Physics has no satisfactory explanation for the dark energy which dominates the universe. This problem presents the most serious challenge to fundamental physics since the quantum and relativistic revolutions of a century ago. The successes of these polarization experiments give confidence in our ability to probe fine details of the polarized cosmic background, which will eventually throw light on the nature of this dark energy."

"The success of these polarization experiments has opened a new window for exploring the universe which may allow us to probe the first instants of the universe through observations of gravitational waves from the epoch of inflation," says Carlstrom.

The analysis of the CBI data is carried out in collaboration with groups at the National Radio Astronomy Observatory (NRAO) and at the Canadian Institute for Theoretical Astrophysics (CITA).

"This is truly an exciting time in cosmological research, with a remarkable convergence of theory and observation, a universe full of mysteries such as dark matter and dark energy, and a fantastic array of new technology--there is tremendous potential for fundamental discoveries here" says Steve Myers of the NRAO, a coauthor and key member of the CBI team from its inception.

According to Richard Bond, director of CITA and a coauthor of the paper, "As a theorist in the early eighties, when we were first showing that the magnitude of the cosmic microwave background polarization would likely be a factor of a hundred down in power from the minute temperature variations that were themselves a heroic effort to discover, it seemed wishful thinking that even in some far distant future such minute signals would be revealed. With these polarization detections, the wished-for has become reality, thanks to remarkable technological advances in experiments such as CBI. It has been our privilege at CITA to be fully engaged as members of the CBI team in unveiling these signals and interpreting their cosmological significance for what has emerged as the standard model of cosmic structure formation and evolution."

The next step for Readhead and his CBI team will be to refine these polarization observations significantly by taking more data, and to test whether or not the polarized emission is exactly out of step with the total intensity with the goal of finding some clues to the nature of the dark matter and dark energy.

The CBI is a microwave telescope array comprising 13 separate antennas, each about three feet in diameter and operating in 10 frequency channels, set up in concert so that the entire instruments acts as a set of 780 interferometers. The CBI is located at Llano de Chajnantor, a high plateau in Chile at 16,800 feet, making it by far the most sophisticated scientific instrument ever used at such high altitudes. The telescope is so high, in fact, that members of the scientific team must each carry bottled oxygen to do the work.

The upgrade of the CBI to polarization capability was supported by a generous grant from the Kavli Operating Institute, and the project is also the grateful recipient of continuing support from Barbara and Stanley Rawn Jr. The CBI is also supported by the National Science Foundation, the California Institute of Technology, and the Canadian Institute for Advanced Research, and has also received generous support from Maxine and Ronald Linde, Cecil and Sally Drinkward, and the Kavli Institute for Cosmological Physics at the University of Chicago.

In addition to the scientists mentioned above, today's Science Express paper is coauthored by C. Contaldi and J. L. Sievers of CITA, J.K. Cartwright and S. Padin, both of Caltech and the University of Chicago; B. S. Mason and M. Pospieszalski of the NRAO; C. Achermann, P. Altamirano, L. Bronfman, S. Casassus, and J. May all of the University of Chile; C. Dickinson, J. Kovac, T. J. Pearson, and M. Shepherd of Caltech; W. L. Holzapfel of UC Berkeley; E. M. Leitch and C. Pryke of the University of Chicago; D. Pogosyan of the University of Toronto and the University of Alberta; and R. Bustos, R. Reeves, and S. Torres of the University of Concepción, Chile.

 

Writer: 
Robert Tindol
Writer: 

David Politzer Wins Nobel Prize in Physics

PASADENA, Calif.--Hugh David Politzer has won the 2004 Nobel Prize in physics for work he began as a graduate student on how the elementary particles known as quarks are bound together to form the protons and neutrons of atomic nuclei. The announcement was made today by the Royal Swedish Academy of Sciences.

Politzer, a professor of theoretical physics at the California Institute of Technology, shares the prize with David Gross and Frank Wilczek. The key discovery celebrated by today's prize was made in 1973, when Politzer, a Harvard University graduate student at the time, and two physicists working independently from Politzer at Princeton University--Gross and his graduate student Wilczek--theorized that quarks actually become bound more tightly the farther they get from each other.

This discovery has been known for 31 years as "asymptotic freedom," and is often described by physics professors to their students with the analogy of a rubber band increasing in tightness as it is pulled apart. Asymptotic freedom established quantum chromodynamics (QCD) as the correct theory of the strong force, one of the four fundamental forces of nature.

Caltech president David Baltimore, himself a Nobel laureate, said he was pleased that another Caltech faculty member has joined the list of the Institute's Nobel recipients. "It's wonderful that David was acknowledged for something that was so far back in his career," Baltimore said. "It shows what young people can do if they think differently."

Politzer joined the Caltech faculty as a visiting associate in 1975, the year after finishing his Harvard Ph.D. in physics and three years after publishing his work on asymptotic freedom. He earned tenure in 1976, became a full professor in 1979, and served as head of the physics department (executive officer, in Caltech parlance) from 1986 to 1988.

A native of New York City, Politzer earned his bachelor's degree from the University of Michigan in 1969. The paper that inaugurated his Nobel Prize-winning work, titled "Reliable Perturbative Results for Strong Interactions?" appeared in the journal Physical Review Letters in 1973 and was Politzer's first published article. Politzer's initial foray into the public limelight came in 1989, when he was recruited to play physicist Robert Serber in the movie Fat Man and Little Boy, which recounted the story of the Manhattan Project and starred Paul Newman as the hard-driving project leader Gen. Leslie Groves. The director of the film, Roland Joffe, had been recruiting career physicists to play some of the roles, and he settled on Politzer, whose academic specialty was quite similar to that of the man he would play.

Politzer, who did not even own a television, later told a reporter from Caltech's internal publication On Campus that he had been reluctant to take the part, but had relented after Joffe convinced him that the "role would not require too much in the way of time or talent." During his two weeks on the set, Politzer warmed up to the project and began discussing nuclear defense policy with Paul Newman, with whom he shared a memorable dinner of spaghetti and salad--the latter dressed with "Newman's Own," of course.

Today's award brings to 31 the total number of prizes won by 30 Caltech faculty and alumni through the years (Linus Pauling won awards in both chemistry and peace). Founded in 1891, Caltech is located on a 124-acre campus in Pasadena. The Institute also manages the nearby Jet Propulsion Laboratory and operates eight other off-campus astronomical, seismological, and marine biology facilities. Caltech has an enrollment of some 2,000 students, more than half of whom are in graduate studies, and a faculty of about 280 professorial members and 65 research members, and some 560 postdoctoral scholars. Caltech employs a staff of more than 2,600 on campus and 5,100 at JPL.

U.S. News &World Report consistently ranks Caltech's undergraduate and graduate programs as being among the nation's best. The average SAT score of members of recent incoming freshman classes has consistently been at 1500.

Four Crafoord Prizes have been awarded to faculty members and alumni. Forty-seven Caltech faculty members and alumni have received the National Medal of Science; and nine alumni (two of whom are also trustees; and one is also a faculty member), two additional trustees, and one additional faculty member have won the National Medal of Technology. Since 1958, 14 faculty members have received the annual California Scientist of the Year award. On the Caltech faculty there are 78 fellows of the American Academy of Arts and Sciences; and on the faculty and Board of Trustees, 71 members of the National Academy of Sciences and 43 members of the National Academy of Engineering.

Caltech has more than 21,000 alumni.

 

The following information was written by Caltech's MacArthur Professor of Theoretical Physics John Preskill, a colleague of Politzer's. Preskill prepared the text upon learning that Politzer had won the Nobel Prize, and sent it from England this morning:

Of the four fundamental forces--the others besides the strong nuclear force are electromagnetism, the weak nuclear force (responsible for the decay of radioactive nuclei), and gravitation--the strong force was by far the most poorly understood in the early 1970s. It had been suggested in 1964 by Caltech physicist Murray Gell-Mann that protons and neutrons contain more elementary objects, which he called quarks.

Yet isolated quarks are never seen, indicating that the quarks are permanently bound together by powerful nuclear forces. Meanwhile, studies of high-energy collisions between electrons and protons performed at the Stanford Linear Accelerator Center (SLAC) had probed the internal structure of the proton, and Caltech's Richard Feynman had suggested in 1969 that the results of these experiments could be explained if quarks inside a proton are nearly free, not subject to any force. Feynman's suggestion, together with the observation that quarks are unable to escape from nuclear particles, posed a deep puzzle: how could nuclear forces be both strong enough to account for the permanent confinement of quarks and weak enough to account for the SLAC experiments?

The discovery of asymptotic freedom provided a highly satisfying resolution of this puzzle. The calculations of Gross, Wilczek, and Politzer showed that in quantum chromodynamics (QCD), quarks are held together strongly when separated by a distance comparable to the size of a proton, explaining quark confinement. Yet for the smaller separations explored in the high-energy SLAC experiments, the attraction is weaker, supporting Feynman's proposal.

Before this development, many physicists had anticipated that understanding the strong nuclear force would require revolutionary new concepts. But surprisingly, QCD has a remarkable mathematical similarity to quantum electrodynamics (QED), the theory that successfully explains electromagnetic phenomena. In QED the force between two electrically charged particles is mediated by the exchange of a photon (a particle of light) between the two particles; in QCD, the quarks carry a different kind of charge, called "color," and the force between two colored particles is mediated by the exchange of a "gluon" between the particles.

The crucial difference between the two theories is that while the photons of QED carry no charge of their own, the gluons of QCD are themselves colored particles. A quark is surrounded by a sea of "virtual" gluons that arise due to quantum fluctuations, and the color of the virtual gluons enhances the quark's own color. A probe coming closer and closer to the quark is influenced less and less by the virtual gluons, so that the effective color charge of the quark seems to weaken; this is asymptotic freedom.

Gross, Wilczek, and Politzer used pencil and paper to perform their breakthrough calculation. In 1973, the methods they needed were newly developed and fraught with subtleties. Today, the calculation is routinely assigned to physics graduate students as a homework exercise.

QCD predicts that the strength of the force between quarks changes with distance in a particular calculable way that has been well confirmed in experiments studying high-energy collisions of elementary particles. The theory makes other detailed predictions, such as the masses of various strongly interacting nuclear particles, which can be extracted only through large-scale numerical computations performed using supercomputers; these too are in satisfying agreement with experiment.

Because QCD, the theory of the strong nuclear force, turned out to be so similar to QED and to the theory of the weak nuclear force, it became possible after the discovery of asymptotic freedom to conceive of unified theories that incorporate all three forces into a common framework. Such theories have been proposed, but still await experimental confirmation. A further challenge, being pursued by many physicists today, is to achieve an even broader unification theory that encompasses the gravitational force as well.

Writer: 
RT

Caltech Physicists Achieve Measurement on a Single Magnetic Domain Wall

PASADENA, Calif.--Physicists for several years have been predicting a new age of semiconductor devices that operate by subtle changes in the orientation of electron spins. Known as "spintronics," the field relies on an intricate knowledge of the magnetic properties of materials and of how magnetic moments can be manipulated.

Now, scientists at the California Institute of Technology have developed a novel method of measuring the resistance of "domain walls," which are the nanoscale boundaries separating areas of a magnetized material that possess different magnetic alignments, or a "twist" of magnetic spins. Reporting in the September 2 issue of the journal Nature, Caltech physicists Hongxing Tang, Michael Roukes, and their colleagues show that their approach leads to an unparalleled precision in isolating, manipulating, and trapping domain walls one by one.

The authors have been able to trap individual domain walls between electrical probes for periods longer than a week. During that time, they are able to carry out extremely sensitive electrical measurements to identify the tiny amounts of resistance generated by this trapped single magnetic domain wall.

"We have demonstrated how a single magnetic domain wall can be monitored as it is made to traverse a patterned array of electrical probes in a microdevice made from single-crystal manganese-doped gallium arsenide," says Professor Roukes. Manganese- doped gallium arsenide belongs to a new class of ferromagnetic semiconductors that isexpected to have great potential for new spintronics devices.

This work also resolves an issue that has puzzled scientists for some time, according to Tang. Many physicists have thought that domain walls were a natural barrier to electron transport and that they cause positive resistance--in other words, the magnetic moments with different alignments created a natural opposition to the flow of charge from one side of the wall to the other. However, the new results show that the resistance is actually negative, which can be attributed to quantum effects in the locale of the domain wall itself. The very fact that the resistance is negative means that electrons can flow more easily under certain conditions, manifesting quantum mechanical origin in this novel phenomenon.

"We are certain that both this result and our new measurement methodology will be of interest to those working on future semiconductor devices based on spintronics," Tang says.

Understanding the dynamics of magnetic domain walls is crucial for magnetic storage devices such as magnetic hard drives, and for future magnetic memories. The methods have the potential to significantly alter the theoretical and experimental research for some time to come.

The work has been made possible through the Caltech team's earlier discovery of a phenomenon dubbed the "giant planar Hall effect." To reach the ultra-high resolution required to resolve the resistance of a domain wall, the authors advance a nanofabrication process for precise alignments of materials at the microscopic level and deploy an innovative way of manipulating domain walls.

"Using these advances, we have made careful measurements on many devices having domain walls of varying lengths and thicknesses," says Roukes. "All show negative resistance at the domain wall."

In addition to being a professor of physics, applied physics, and bioengineering at Caltech, Roukes is also founding director of Caltech's new Kavli Nanoscience Institute. Dr. Hongxing Tang is a senior research scientist at Caltech. Other authors of the paper are Sotiris Masmanidis, a Caltech graduate student in applied physics, and Roland Kawakami and Prof. David Awschalom, both of the UC Santa Barbara department of physics.

Writer: 
Robert Tindol

International Team of Scientists Establishes New Internet Land-Speed Benchmark

PASADENA, Calif.—Scientists at the California Institute of Technology (Caltech) and the European Organization for Nuclear Research (CERN), along with colleagues at AMD, Cisco, Microsoft Research, Newisys, and S2io have set a new Internet2 land-speed record. The team transferred 859 gigabytes of data in less than 17 minutes at a rate of 6.63 gigabits per second between the CERN facility in Geneva, Switzerland, and Caltech in Pasadena, California, a distance of more than 15,766 kilometers. The speed is equivalent to transferring a full-length DVD movie in just four seconds.

The technology used in setting this record included S2io's Xframe® 10 GbE server adapter, Cisco 7600 Series Routers, Newisys 4300 servers utilizing AMD Opteron processors, Itanium servers, and the 64-bit version of Windows Server 2003.

The performance is also remarkable because it is the first record to break the 100 petabit meter per second mark. One petabit is 1,000,000,000,000,000 bits.

This latest record by Caltech and CERN is a further step in an ongoing research-and-development program to create high-speed global networks as the foundation of next-generation data-intensive grids.

Multi-gigabit-per-second IPv4 and IPv6 end-to-end network performance will lead to new research and business models. People will be able to form "virtual organizations" of planetary scale, sharing in a flexible way their collective computing and data resources. In particular, this is vital for projects on the frontiers of science and engineering, projects such as particle physics, astronomy, bioinformatics, global climate modeling, and seismology.

Harvey Newman, professor of physics at Caltech, said, "This is a major milestone towards our dynamic vision of globally distributed analysis in data-intensive, next-generation high-energy physics (HEP) experiments. Terabyte-scale data transfers on demand, by hundreds of small groups and thousands of scientists and students spread around the world, is a basic element of this vision; one that our recent records show is realistic." Olivier Martin, head of external networking at CERN and manager of the DataTAG project said, "As of 2007, when the Large Hadron Collider, currently being built at CERN, is switched on, this huge facility will produce some 15 petabytes of data a year, which will be stored and analyzed on a global grid of computer centers. This new record is a major step on the way to providing the sort of networking solutions that can deal with this much data."

The team used the optical networking capabilities of the LHCnet, DataTAG, and StarLight and gratefully acknowledges support from the DataTAG project sponsored by the European Commission (EU Grant IST-2001-32459), the DOE Office of Science, High Energy and Nuclear Physics Division (DOE Grants DE-FG03-92-ER40701 and DE-FC02-01ER25459), and the National Science Foundation (Grants ANI 9730202, ANI-0230967, and PHY-0122557).

About Caltech:

With an outstanding faculty, including three Nobel laureates, and such off-campus facilities as Palomar Observatory, and the W. M. Keck Observatory, the California Institute of Technology is one of the world's major research centers. The Institute also conducts instruction in science and engineering for a student body of approximately 900 undergraduates and 1,000 graduate students who maintain a high level of scholarship and intellectual achievement. Caltech's 124-acre campus is situated in Pasadena, California, a city of 135,000 at the foot of the San Gabriel Mountains, about 10 miles northeast of the Los Angeles Civic Center. Caltech is an independent, privately supported university. More information is available at http://www.caltech.edu.

About CERN:

CERN, the European Organization for Nuclear Research, has its headquarters in Geneva, Switzerland. At present, its member states are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland, and the United Kingdom. Israel, Japan, the Russian Federation, the United States of America, Turkey, the European Commission, and UNESCO have observer status. For more information, see http://www.cern.ch.

About the European Union DataTAG project:

The DataTAG is a project co-funded by the European Union, the U.S. Department of Energy, and the National Science Foundation. It is led by CERN together with four other partners. The project brings together the following European leading research agencies: Italy's Istituto Nazionale di Fisica Nucleare (INFN), France's Institut National de Recherche en Informatique et en Automatique (INRIA), the UK's Particle Physics and Astronomy Research Council (PPARC), and Holland's University of Amsterdam (UvA). The DataTAG project is very closely associated with the European Union DataGrid project, the largest grid project in Europe also led by CERN. For more information, see http://www.datatag.org.

Writer: 
Robert Tindol
Writer: 

Gamma-ray burst of December 3 was a new type of cosmic explosion

PASADENA, Calif.—Astronomers have identified a new class of cosmic explosions that are more powerful than supernovae but considerably weaker than most gamma-ray bursts. The discovery strongly suggests a continuum between the two previously-known classes of explosions.

In this week's issue of Nature, astronomers from the Space Research Institute of the Russian Academy of Sciences and the California Institute of Technology announce in two related papers the discovery of the explosion, which was first detected on December 3, 2003, by the European-Russian Integral satellite and then observed in detail at ground-based radio and optical observatories. The burst, known by its birthdate, GRB031203, appeared in the constellation Puppis and is about 1.6 billion light-years away.

Although the burst was the closest gamma-ray burst to Earth ever studied (all the others have been several billion light-years away), researchers noticed that the explosion was extremely faint--releasing only about one-thousandth of the gamma rays of a typical gamma-ray burst. However, the burst was also much brighter than supernovae explosions, which led to the conclusion that a new type of explosion had been found.

Both supernovae and the rare but brilliant gamma-ray bursts are cosmic explosions marking the deaths of massive stars. Astronomers have long wondered what causes the seemingly dramatic differences between these events. The question of how stars die is currently a major focus of stellar research, and is particularly directed toward the energetic explosions that destroy a star in one cataclysmic event.

Stars are powered by the fusion ("burning'') of hydrogen in their interiors. Upon exhaustion of fuel in the interior, the core of massive stars collapse to compact objects--typically a neutron star and occasionally a black hole. The energy released as a result of the collapse explodes the outer layers, the visible manifestation of which is a supernova. In this process, new elements are added to the inventory of matter in the universe.

However, this nuclear energy may be insufficient to power the supernova explosions. One theory is that additional energy is generated from the matter falling onto the newly produced black hole. Many astronomers believe that this is what powers the luminous gamma-ray bursts.

But the connection between such extreme events and the more common supernovae is not yet clear, and if they are indeed closely related, then there should be a continuum of cosmic explosions, ranging in energy from that of "ordinary" supernovae to that of gamma-ray bursts.

In 1998, astronomers discovered an extremely faint gamma-ray burst, GRB 980425, coincident with a nearby luminous supernova. The supernova, SN 1998bw, also showed evidence for an underlying engine, albeit a very weak one. The question that arose was whether the event, GRB 980425/SN 1998bw, was a "freak" explosion or whether it was indicative of a larger population of low-powered cosmic explosions with characteristics in between the cosmological gamma-ray bursts and typical supernovae.

"I knew this was an exciting find because even though this was the nearest gamma-ray burst to date, the gamma-ray energy measured by Integral is one thousand times fainter than typical cosmological gamma-ray bursts," says Sergey Sazonov of the Space Research Institute, the first author of one of the two Nature papers.

The event was studied in further detail by the Chandra X-Ray Observatory and the Very Large Array, a radio telescope facility located in New Mexico.

"I was stunned that my observations from the Very Large Array showed that this event confirmed the existence of a new class of bursts," says graduate student Alicia Soderberg, who is the principal author of the other Nature paper. "It was like hitting the jackpot."

There are several exciting implications of this discovery, including the possible existence of a significant new population of low-luminosity gamma-ray bursts lurking within the nearby universe, said Shrinivas Kulkarni, who is the MacArthur Professor of Astronomy and Planetary Science at Caltech and Soderberg's faculty adviser.

"This is an intriguing discovery," says Kulkarni. "I expect a treasure trove of such events to be identified by NASA's Swift mission scheduled to be launched this fall from Cape Canaveral. I am convinced that further discoveries and studies of this new class of hybrid events will forward our understanding of the death of massive stars."

 

Writer: 
RT

Physicists Successful in Trapping Ultracold Neutrons at Los Alamos National Laboratory

PASADENA, Calif.—Free neutrons are usually pretty speedy customers, buzzing along at a significant fraction of the speed of light. But physicists have created a new process to slow neutrons down to about 15 miles per hour—the pace of a world-class mile runner—which could lead to breakthroughs in understanding the physical universe at its most fundamental level.

According to Brad Filippone, a physics professor at the California Institute of Technology, he and a group of colleagues from Caltech and several other institutions recently succeeded in collecting record-breaking numbers of ultracold neutrons at the Los Alamos Neutron Science Center. The new technique resulted in about 140 neutrons per cubic centimeter, and the number could be five times higher with additional tweaking of the apparatus.

"Our principal interest is in making precision measurements of fundamental neutron properties," says Filippone, explaining that a neutron has a half-life of only 15 minutes. In other words, if a thousand neutrons are trapped, five hundred will have broken down after 15 minutes into a proton, electron, and antineutrino.

Neutrons normally exist in nature in a much more stable state within the nuclei of atoms, joining the positively charged protons to make up most of the atom's mass. Neutrons become quite unstable if they are stripped from the nucleus, but the very fact that they decay so quickly can make them useful for various experiments.

The traditional way physicists obtained free neutrons was by trying to slow them down as they emerged from a nuclear reactor, making them bounce around in material to get rid of energy. This procedure worked fine for slowing down neutrons to a few feet per second, but that's still pretty fast. The new technique at Los Alamos National Laboratory involves a second stage of slowdown that is impractical near a nuclear reactor, but which works well at a nuclear accelerator where the event producing the neutrons is abrupt rather than ongoing. The process begins with smashing protons from the accelerator into a solid material like tungsten, which results in neutrons being knocked out of their nuclei.

The neutrons are then slowed down as they bounce around in a nearby plastic material, and then some of them are slowed much further if they happen to enter a birthday-cake-sized block of solid deuterium (or "heavy hydrogen") that has been cooled down to a temperature a few degrees above absolute zero.

When the neutrons enter the crystal latticework of the deuterium block, they can lose virtually all their energy, and emerge from the block at speeds so slow they can no longer zip right through the walls of the apparatus. The trapped ultracold neutrons bounce along the nickel walls of the apparatus and eventually emerge, where they can be collected for use in a separate experiment. According to Filippone, the extremely slow speeds of the neutrons are important in studying their decays at a minute level of detail. The fundamental theory of particle physics known as the Standard Model predicts a specific pattern in the neutron's decay, but if the ultracold neutron experiments were to reveal slightly different behavior, then physicists would have evidence of a new type of physics, such as supersymmetry. Future experiments could also exploit an inherent quantum limit of the ultracold neutrons to bounce no lower than about 15 microns on a flat surface—or about a fifth the width of a human hair. With a cleverly designed experiment, Filippone says, this limit could lead to better knowledge of gravitational interactions at very small distances. The next step for the experimenters is to return to Los Alamos in October. Then, they will use the ultracold neutrons to study the neutrons themselves. The research was supported by about $1 million funding from Caltech and the National Science Foundation.

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RT

From Cosmos to Climate, Six Caltech Professors Awarded Sloan Research Fellowships

PASADENA, Calif.— Six members of the Caltech faculty have received Alfred P. Sloan Research Fellowships for 2004.

The Caltech recipients in the field of mathematics are Nathan Dunfield and Vadim Kaloshin, both associate professors of mathematics. In physics, Sloan Fellowships were awarded to Andrew Blain, assistant professor of astronomy, Sunil Golwala, assistant professor of physics, Re'em Sari, associate professor of astrophysics and planetary science, and Tapio Schneider, assistant professor of environmental science and engineering.

Each Sloan Fellow receives a grant of $40,000 for a two-year period. The grants of unrestricted funds are awarded to young researchers in the fields of physics, chemistry, computer science, mathematics, neuroscience, computational and evolutionary molecular biology, and economics. The grants are given to pursue diverse fields of inquiry and research, and to allow young scientists the freedom to establish their own independent research projects at a pivotal stage in their careers. The Sloan Fellows are selected on the basis of "their exceptional promise to contribute to the advancement of knowledge."

From over 500 nominees, a total of 116 young scientists and economists from 51 different colleges and universities in the United States and Canada, including Caltech's six, were selected to receive a Sloan Research Fellowship.

Twenty-eight previous Sloan Fellows have gone on to win Nobel Prizes.

The Alfred P. Sloan Research Fellowship program was established in 1955 by Alfred P. Sloan, Jr., who was the chief executive officer of General Motors for 23 years. Its objective is to encourage research by young scholars at a time in their careers when other support may be difficult to obtain. It is the oldest program of the Alfred P. Sloan Foundation and one of the oldest fellowship programs in the country.

Nathan Dunfield conducts research in topology, the study of how geometric structures in three-dimensional space can be altered. His focus is on the connections to the symmetries of rigid geometric objects, especially certain types of non-Euclidean geometries, and he also uses computer experiments to probe some of the central questions in the study of topology. Dunfield will utilize his Sloan Fellowship to further his research in this area.

Vadim Kaloshin is an expert in chaos theory and "strange attractors." He is especially interested in mathematical equations known as Hamiltonian systems and how they apply to stability. His work could lead to a better understanding of how chaotic systems behave. Kaloshin will use his Sloan Fellowship to continue investigation in these fields.

Andrew Blain probes the origin of galaxies by observing them at great distances in the process of formation. He concentrates on the signatures that can be seen in the short-wavelength radio and long-wavelength infrared spectrum, where the gas and soot-like dust particles between the stars emit energy they absorb from the youngest and most luminous parts of galaxies. Most studies of the process are still carried out using the direct light from stars at shorter optical wavelengths, but the complementary information from longer wavelengths is essential to build up a more complete picture. The Sloan Foundation Fellowship will be used to link together these two techniques by investigating differences between the way distant galaxies found at each wavelength are distributed in space.

Sunil Golwala's research focuses on understanding dark matter and dark energy, components that dominate the universe but whose identity and nature are unknown. Golwala is interested in the development and use of particle detectors for observing the direct scattering of "Weakly Interacting Massive Particles," one of the leading candidates for dark matter. His work also involves the observation of varying aspects of the cosmic microwave background that inform us about the nature of dark energy via its effect on the growth of galaxy clusters and its clustering effects on super-horizon scales. Golwala will utilize his Sloan Fellowship in pursuit of this endeavor to better understand the universe.

Re'em Sari intends to utilize his Sloan Fellowship to examine the origin of planet formation, a first step in a long journey to look for life around other stars. Some of the fundamental questions he will investigate are: How do planets form? What are the necessary initial conditions for planet formation? What factors determined the number of planets in our solar system? How many planets like Earth do we expect to find around other stars? Are there binary giant planets? Sari will apply his fellowship to further understanding the "grand scheme of planetary systems."

Tapio Schneider works on understanding climate and the dynamical processes in the atmosphere that determine basic climatic features such as the pole-to-equator temperature gradient and the distribution of water vapor. Developing mathematical models of the large-scale (1000 km) turbulent transport of heat, mass, and water vapor is one central aspect of this research. The Sloan Fellowship will provide computing equipment and support to expand these studies on climate.

Contact: Deborah Williams-Hedges (626) 395-3227 debwms@caltech.edu

Visit the Caltech Media Relations Web site at: http://pr.caltech.edu/media

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Caltech, Cornell announce new $2-million study for building giant submillimeter telescope

PASADENA, Calif.—The California Institute of Technology and Cornell University are in the planning stages for a new 25-meter telescope to be built in Chile. The submillimeter telescope will cost an estimated $60 million and will be nearly two times larger in diameter than the largest submillimeter telescope currently in existence.

The first step of the plan, which is being announced today jointly by Caltech and Cornell, commits the two institutions to a $2-million study, says Jonas Zmuidzinas, a physics professor at Caltech who is leading the Institute's part of the collaboration. The telescope is projected for a 2012 completion date on a high site in the Atacama Desert of northern Chile, and will significantly ramp up Caltech's research in submillimeter astronomy.

Scientists from Cornell, Caltech, and Caltech's Jet Propulsion Laboratory (JPL) will be participating in the telescope study, including Caltech faculty members Andrew Blain, Sunil Golwala, Andrew Lange, Tom Phillips, Anthony Readhead, Anneila Sargent, and others.

"We are very much looking forward to working with our Cornell colleagues on this project," says Zmuidzinas.

At Cornell, the participants will include professors Riccardo Giovanelli, Terry Herter, Gordon Stacey, and Bob Brown.

Submillimeter wavelength astronomy allows the study of a number of astrophysical phenomena that do not emit much visible or infrared light. The new telescope will observe stars and planets forming from swirling disks of gas and dust, will make measurements to determine the composition of the molecular clouds from which the stars are born, and could even discover large numbers of galaxies undergoing huge bursts of star formation in the very distant universe.

Also, the 25-meter telescope could be used to study the origin of large-scale structure in the universe.

"So far, we have gotten just a small taste of what there is to learn at submillimeter wavelengths," says Zmuidzinas. "This telescope will be a huge step forward for the field."

The new telescope is poised to take advantage of the rapid development of sensitive superconducting detectors, an area in which Zmuidzinas and his Caltech/JPL colleagues have been making important contributions. The new superconducting detectors enable large submillimeter cameras to be built, which will produce very sensitive panoramic images of the submillimeter sky.

The 25-meter telescope is a natural progression in Caltech and JPL's longstanding interest in submillimeter astronomy. Caltech already operates the Caltech Submillimeter Observatory (CSO), a 10.4-meter telescope constructed and operated with funding from the National Science Foundation, with Tom Phillips serving as director. The telescope is fitted with sensitive submillimeter detectors and cameras, many of which were developed in collaboration with JPL, making it ideal for seeking out and observing the diffuse gases and their constituent molecules, crucial to understanding star formation.

The advantages of the new telescope will be fourfold. First, due to the larger size of its mirror and its more accurate surface, the 25-meter telscope should provide six to 12 times the light-gathering ability of the CSO, depending on the exact wavelength. Second, the larger diameter and better surface will result in much sharper images of the sky. Third, the large new cameras will provide huge advantages over those currently available.

Finally, the 16,500-foot elevation of the Atacama Desert will provide an especially dry sky for maximum effectiveness. Submillimeter wavelengths (as short as two-tenths of a millimeter) are strongly absorbed by the water vapor in the atmosphere. For maximum effectiveness, a submillimeter telescope must be located at a very high, very dry altitude--the higher the better--or best of all, in space.

However, while the idea of a large (10-meter) submillimeter telescope in space is being considered by NASA and JPL, it is still more than a decade away. Meanwhile, existing space telescopes such as the Hubble and the Spitzer work at shorter wavelengths, in the visible and infrared, respectively.

In 2007, the European Space Agency plans to launch the 3.5-meter Herschel Space Observatory, which will be the first general-purpose submillimeter observatory in space. NASA is participating in this project, and scientists at JPL and Caltech are providing detectors and components for the science instruments.

"It is a very exciting time for submillimeter astronomy," says Zmuidzinas. "We are making rapid progress on all fronts--in detectors, instruments, and new facilities--and this is leading to important scientific discoveries." 

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Robert Tindol
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Researchers Using Hubble and Keck Telescopes Find Farthest Known Galaxy in the Universe

PASADENA, California--The farthest known object in the universe may have been discovered by a team of astrophysicists using the Keck and Hubble telescopes. The object, a galaxy behind the Abell 2218 cluster, may be so far from Earth that its light would have left when the universe was just 750 million years old.

The discovery demonstrates again that the technique known as gravitational lensing is a powerful tool for better understanding the origin of the universe. Via further applications of this remarkable technique, astrophysicists may be able to better understand the mystery of how the so-called "Dark Ages" came to an end.

According to California Institute of Technology astronomer Jean-Paul Kneib, who is the lead author reporting the discovery in a forthcoming article in the Astrophysical Journal, the galaxy is most likely the first detected close to a redshift of 7.0, meaning that it is rushing away from Earth at an extremely high speed due to the expansion of the universe. The distance is so great that the galaxy's ultraviolet light has been stretched to the point of being observed at infrared wavelengths.

The team first detected the new galaxy in a long exposure of the Abell 2218 cluster taken with the Hubble Space Telescope's Advanced Camera for Surveys. Analysis of a sequence of Hubble images indicate a redshift of at least 6.6, but additional work with the Keck Observatory's 10-meter telescopes suggests that the astronomers have found an object whose redshift is close to 7.0.

Redshift is a measure of the factor by which the wavelength of light is stretched by the expansion of the universe. The greater the shift, the more distant the object and the earlier it is being seen in cosmic history.

"As we were searching for distant galaxies magnified by Abell 2218, we detected a pair of strikingly similar images whose arrangement and color indicated a very distant object," said Kneib. "The existence of two images of the same object indicated that the phenomenon of gravitational lensing was at work."

The key to the new discovery is the effect the Abell 2218 cluster's gigantic mass has on light passing by it. As a consequence of Einstein's theory of relativity, light is bent and can be focused in a predictable way due to the warpage of space-time near massive objects. In this case the phenomenon actually magnifies and produces multiple images of the same source. The new source in Abell 2218 is magnified by a factor of 25.

The role of gravitational lensing as a useful phenomenon in cosmology was first pointed out by the Caltech astronomer Fritz Zwicky in 1937, who even suggested it could be used to discover distant galaxies that would otherwise be too faint to be seen.

"The galaxy we have discovered is extremely faint, and verifying its distance has been an extraordinarily challenging adventure," Kneib added. "Without the magnification of 25 afforded by the foreground cluster, this early object could simply not have been identified or studied in any detail with presently available telescopes. Indeed, even with aid of the cosmic lens, our study has only been possible by pushing our current observatories to the limits of their capabilities."

Using the unique combination of the high resolution of Hubble and the magnification of the cosmic lens, the researchers estimate that the galaxy is small--perhaps measuring only 2,000 light-years across—but forming stars at an extremely high rate.

An intriguing property of the new galaxy is the apparent lack of the typically bright hydrogen emission seen in many distant objects. Also, its intense ultraviolet signal is much stronger than that seen in later star-forming galaxies, suggesting that the galaxy may be composed primarily of massive stars.

"The unusual properties of this distant source are very tantalizing because, if verified by further study, they could represent those expected for young stellar systems that ended the dark ages," said Richard Ellis, Steele Family Professor of Astronomy, and a coauthor of the article.

The term "Dark Ages" was coined by the British astronomer Sir Martin Rees to signify the period in cosmic history when hydrogen atoms first formed but stars had not yet had the opportunity to condense and ignite. Nobody is quite clear how long this phase lasted, and the detailed study of the cosmic sources that brought this period to an end is a major goal of modern cosmology.

The team plans to continue the search for additional extremely distant galaxies by looking through other cosmic lenses in the sky.

"Estimating the abundance and characteristic properties of sources at early times is particularly important in understanding how the Dark Ages came to an end," said Mike Santos, a former Caltech graduate student involved in the discovery and now a postdoctoral researcher at the Institute of Astronomy in Cambridge, England. "We are eager to learn more by finding further examples, although it will no doubt be challenging."

The Caltech team reporting on the discovery consists of Kneib, Ellis, Santos, and Johan Richard. Kneib and Richard are also affiliated with the Observatoire Midi-Pyrenees of Toulouse, France. Santos is also at the Institute of Astronomy, in Cambridge.

The research was funded in part by NASA.

The W. M. Keck Observatory is managed by the California Association for Research in Astronomy, a scientific partnership between the California Institute of Technology, the University of California, and NASA. For more information, visit the observatory online at www.keckobservatory.org.

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RT

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