World’s Particle Physics Laboratories Join To Create New Communication Resource

www.interactions.org Goes Live

Batavia, Ill.-The worldwide particle physics community today (August 12) launched Interactions.org, a new global, Web-based resource developed to provide news, high-quality imagery, video and other tools for communicating the science of particle physics.

“The Web site, found at www.interactions.org, provides a newswire with the latest developments in particle physics and related fields, as well as links to current particle physics news from the world’s press,” said Communications Director Petra Folkerts of the DESY laboratory in Hamburg, Germany. “It offers high-resolution photos and graphics from the world’s particle physics laboratories and links to education and outreach programs.”

The site also presents timely information about science policy and funding; links to universities; a glossary and a conference calendar.

“Interactions.org was developed and is jointly maintained by the InterAction collaboration,” said deputy Communications director Youhei Morita, of KEK laboratory in Tsukuba, Japan. “Our collaboration represents the communication staffs of all the world’s particle physics laboratories. The new site responds to the growing demand for information and images from particle physics laboratories in Europe, North America and Asia.”

The group pooled experience and resources to create a centralized Web site.

“Already we have hundreds of journalists, researchers and policy-makers using Interactions.org on a daily basis,” said James Gillies, head of the Education and Communication Group at the CERN laboratory in Geneva, Switzerland. “This outstanding collection of materials represents the combined efforts of communications professionals from around the world.”

InterAction collaborators said the current Web site is only the beginning.

“Interactions.org will give the media, the science community, policy makers, funding agencies, students, and teachers the tools to better understand and communicate the nature and value of particle physics research and its connections to other fields of science,” said Judy Jackson, Public Affairs director at Fermilab near Chicago.

Physicist and communicator Stefano Bianco of INFN Frascati Laboratory, near Rome, said that users of interactions.org will find current information about the status of initiatives, people and facilities involved not only in particle physics but also in other related fields, and not only in one country but across the globe.

“Global collaboration is the foundation of success in this era of particle physics research,” Neil Calder, Director of Communications for the Stanford Linear Accelerator Center in Palo Alto, California. “Interactions.org will help facilitate that teamwork.”

Interactions.org Contributing Members include:
The American Physical Society (APS)
Brookhaven National Laboratory (BNL)
European Organization for Nuclear Research (CERN)
Deutsche Elektronen-Synchrotron (DESY)
Fermi National Accelerator Laboratory (FNAL)
High Energy Accelerator Research Organization (KEK)
INFN: Laboratori Nazionali del Gran Sasso (LNGS)
INFN: Laboratori Nazionali di Frascati (LNF)
Institut National de Physique Nucleaire et de Physique des Particules (IN2P3)
Institute for High-Energy Physics, Protvino (IHEP)
Istituto Nazionale di Fisica Nucleare (INFN)
Thomas Jefferson National Accelerator Facility (TJNAF)
Joint Institute for Nuclear Research, Dubna (JINR)
Laboratory for Elementary -Particle Physics at Cornell University (LEPP)
Lawrence Berkeley National Laboratory (LBL)
Saclay Physics Institute
Stanford Linear Accelerator Center (SLAC)

Free Public Lecture, Thursday, August 14, 7:30 p.m., Ramsey Auditorium, Fermilab

Reservations required: Call 630-840-8720 to reserve free tickets

Batavia, Ill.-“Before we had the Web,” said Fermilab physicist Irwin Gaines, “we didn’t know we needed it. I don’t think we can even dream of what we’ll be able to do with the Grid.”

There is a revolution ahead in the way people everywhere use computer technology to solve the most complex computational problems. The vision for the rapidly developing international Data Grid is to put the power of the world’s computing capacity at the fingertips of everyone with a laptop computer.

On Thursday, August 14, at 7:30 p.m., the Department of Energy’s Fermi National Accelerator Laboratory in Batavia, Illinois, will sponsor a free public lecture, “Extreme Computing: The Data Grid and the Future of Distributed Computing,” by six internationally known pioneers of emerging Grid technology:

• Dr. Ian Foster, co-author of “The Grid: Blueprint for a New Computing Infrastructure,” Associate Director of the Mathematics and Computer Science Division at the Department of Energy’s Argonne National Laboratory and Professor of Computer Science at the University of Chicago
• Dr. Ian Bird, of CERN, Project Manager for LHC Computing Grid, at CERN, the European Laboratory for Particle Physics
• Robert J. Aiken, Director of Academic Research and Technology Initiatives, Cisco Systems, Inc.
• Dr. Stephen Perrenod, Group Manager, High Performance Computer Marketing, Sun Microsystems
• Dr. David Martin, Program Director, Internet Standards and Technology, IBM
• Dr. Daniel Reed, Director, National Center for Supercomputing Applications, University of Illinois at Urbana-Champaign.

Speakers will present the state of the art and the outlook for the future of Grid computing from their own very different perspectives.

In the 1990s, the Web made the Internet a huge system for finding and retrieving all kinds of information. Grid technology takes the next step, pooling computing power over the Internet, linking and managing global computing resources for solving the fantastically challenging computer problems of particle physics and astrophysics, climate modeling, genetics, earthquake simulation, brain research and other fields of science. Supported by the National Science Foundation and the Department of Energy’s Office of Science, U.S. scientists are collaborating with colleagues around the world to develop the open-source software, the infrastructure and the standards to make the Grid a reality. Fermilab has achieved the first working Data Grids for physics in the United States.

Note to Reporters: Speakers will be available to meet with the members of the press at a pre-lecture buffet at 6:30 p.m. in the One North Conference Room of Fermilab’s Wilson Hall.

For more information: http://conferences.fnal.gov/lp2003/bulletins/grid_new.html
How to get to Fermilab: http://www.fnal.gov/pub/visiting/hours/index.html

BATAVIA, Ill.-Helen Edwards, whose work in the early days of the Department of Energy’s Fermi National Accelerator Laboratory is a foundation of past, present and future scientific achievements, and whose current work is helping shape the next generation of particle accelerators, has been awarded the 2003 Robert R. Wilson Prize by the American Physical Society.

The award is named for Fermilab’s founding director, Robert Rathbun Wilson (1914-2000), and was established in 1986 by friends of Wilson, and by the Division of Particles and Fields and the Division of Physics of Beams of the American Physical Society. Previous winners include Cornell University’s Maury Tigner (2000) and Fermilab’s Alvin Tollestrup (1989).

“It is a great honor to receive the Wilson Prize,” said Edwards, who with her husband, Don, worked with Wilson first at Cornell University and then at the National Accelerator Laboratory, later renamed Fermilab.

The 2003 award cites Edwards “for her pivotal achievement and critical contribution as the leader in the design, construction, commissioning and operation of the Tevatron, and for her continued contributions to the development of high gradient superconducting linear accelerators as well as bright and intense electron sources.”

“I was delighted to learn that Helen Edwards had been awarded the Wilson Prize,” said Fermilab Director Michael Witherell. “Bob Wilson brought Helen to work at Fermilab, and both of them made essential contributions to the remarkable success of Fermilab and its accelerators. I’m very pleased that Helen’s work has been recognized in this way.”

In a distinguished and much-heralded career, Edwards has been the recipient of a MacArthur Fellowship, the National Medal of Technology, and the Department of Energy’s E. O. Lawrence Award. She is a member of the American Academy of Arts and Sciences and of the National Academy of Engineering, and is a Fellow of the American Physical Society.

“My husband and I worked under Bob Wilson’s direction for over 20 years and we benefited greatly from his example,” Edwards said. “I believe this award is for my husband as much as for myself, as we have worked effectively as a team over the years. I have grown to appreciate Wilson’s leadership and convictions more and more over the years. Not only was he a great technical leader but he communicated his beliefs with great clarity. He lauded international collaboration and decried ‘creeping bureaucracy.’ I can do no better than to excerpt some of his thoughts from his 1969 testimony before Congress, on building the Fermilab accelerator: ‘…(T)his new knowledge has all to do with honor and country but it has nothing to do directly with defending our country except to make it worth defending.'”

The Tevatron, cited in the Wilson Award, accelerated its first beam in 1983 and recorded its first proton-antiproton collisions in 1985. With the Tevatron collider, scientists discovered the top quark in 1995. Still the world’s highest-energy particle accelerator, the Tevatron is poised for major breakthroughs in the understanding of elementary particles and forces during the current Collider Run II, at even higher energy and at a new record rate of proton-antiproton collisions.

Currently, Edwards is engaged in research in superconducting technology for one of the possible designs of an electron-positron linear collider, which has been proposed as the next machine for the field of high-energy physics, to be built as an international laboratory. She has been the leader of the Photoinjector Project, which used a superconducting radiofrequency cavity for the first time at Fermilab to accelerate an electron beam. She spends time at Deutsches Elektronen Synchrotron (DESY) in Hamburg, Germany on research and development for the TESLA superconducting linear collider.

For more information on the Robert R. Wilson Prize, and a list of previous winners since 1987, go to the American Physical Society Web page for prizes and awards at http://www.aps.org/praw/03winners.html.

Fermilab is a U.S. Department of Energy national laboratory, operated under contract by Universities Research Association, Inc.

Batavia, Ill.-Astrophysicist Edward W. “Rocky” Kolb, of the Department of Energy’s Fermi National Accelerator Laboratory and the University of Chicago, will join United States senator Edward M. Kennedy (D-Mass.), NPR News senior analyst Daniel Schorr, novelist Chinua Achebe, and other luminaries in addressing the 2002 incoming class of Fellows and Foreign Honorary Members of the American Academy of Arts and Sciences on Saturday, Oct. 5 at 3:30 p.m. at Harvard University’s Sanders Theatre in Cambridge, Massachusetts.

“I am honored and pleased to have been chosen as a member of this group,” Kolb said of the double honor of being inducted into the Academy and being chosen to address his new colleagues. He said his speech will focus on the unification of science with the humanities.

Kolb, 51, currently lives in Warrenville, Ill., and also has a home in Chicago. The New Orleans native received a Ph.D. in physics from the University of Texas and now serves as head of the NASA/Fermilab Theoretical Astrophysics Group. Kolb, along with fellow Fermilab scientists and Academy Fellows Leon Lederman and Michael Turner, founded the group in 1983 to explore the connections between cosmology and particle physics.

In addition to more than 200 scientific papers, Kolb is the author of the standard textbook on particle physics and cosmology, “The Early Universe,” and a cosmology book for the general public, “Blind Watchers of the Sky,” winner of the 1996 Emme award from the American Astronomical Society. He is a Fellow of the American Physical Society and has served on the editorial boards of several international scientific journals, as well as “Astronomy” magazine.

The Academy, which was founded in 1790, inducts approximately 150 new Fellows and Foreign Honorary Members each year, honoring intellectual achievement, leadership and creativity in all fields. The inductees, who are nominated and elected by current members, are divided into five classes: mathematics and physics; biological sciences; social sciences; humanities and arts; and public affairs and business. The Academy conducts non-partisan, interdisciplinary studies in areas such as international security, social policy, education and the humanities. Previous Fellows include the likes of Benjamin Franklin, Daniel Webster, Albert Einstein and Winston Churchill.

Fermilab is a Department of Energy national laboratory, operated under contract by Universities Research Association, Inc.

BATAVIA, Ill. and MENLO PARK, Calif.-The U.S. Department of Energy’s Fermi National Accelerator Laboratory in Batavia, Ill., and Stanford Linear Accelerator Center in Menlo Park, Calif., today jointly announce the launching of an email news wire, HEP Interactions, for communicating news from high-energy physics and related fields.

The free service will function as a source of timely information on high-energy physics, including press releases and news items from the world’s high-energy physics laboratories. A related web site will archive press releases and newsworthy stories.

For more information, or to receive this new electronic subscriber news service, visit the Web site at:http://www.interactions.org

The Stanford Linear Accelerator Center, a national laboratory in the U.S. Department of Energy’s Office of Science, is operated by Stanford University in Menlo Park, California. Fermi National Accelerator Laboratory is operated under contract by Universities Research Association, Inc., for the U.S. Department of Energy’s Office of Science.

Batavia, Ill. – Scientists of the Booster Neutrino Experiment collaboration announced this week that a new detector at the U.S. Department of Energy’s Fermi National Accelerator Laboratory has observed its first neutrino events. The BooNE scientists identified neutrinos that created ring-shaped flashes of light inside a 250,000-gallon detector filled with mineral oil.

The major goal of the MiniBooNE experiment, the first phase of the BooNE project, is either to confirm or refute startling experimental results reported by a group of scientists at the Los Alamos National Laboratory. In 1995, the Liquid Scintillator Neutrino Detector collaboration stunned the particle physics community when it reported a few incidences in which the antiparticle of a neutrino had presumably transformed into a different type of antineutrino, a process called neutrino oscillation.

“Today, there exist three very different independent experimental results that indicate neutrino oscillations,” said Janet Conrad, a physics professor at Columbia University and cospokesperson of the BooNE collaboration. “Confirming the LSND result would suggest the existence of an additional kind of neutrino beyond the three known types. It would require physicists to rewrite a large part of the theoretical framework called the Standard Model.”

Over the next two years, the BooNE collaboration will collect and analyze approximately one million particle events to study the quantum behavior of neutrinos. Although these ghost-like particles are among the most abundant particles in the entire universe, little is known about their role in nature.

“It is an exciting time for neutrino physics,” said Department of Energy Office of Science Director Raymond Orbach. “In the past few years experiments around the world have made extraordinary neutrino observations, shattering the long-standing view that neutrinos have no mass. The MiniBooNE experiment has the potential for advancing the revolution of our understanding of the building blocks of matter.”

The MiniBooNE experiment, under construction from October 1999 to May 2002, relies on an intense beam of muon neutrinos created by the Booster accelerator at Fermilab. About 1,500 feet from its production point, the neutrino beam traverses a 40-foot-diameter tank filled with ultraclean mineral oil. The tank’s interior is lined with 1,520 light-sensitive devices, called photomultiplier tubes, that record tiny flashes of light produced by neutrinos colliding with carbon nuclei inside the oil.

“We will operate the experiment 24 hours a day, seven days a week,” said Bill Louis, a Los Alamos scientist and cospokesperson of the BooNE collaboration. “We will be looking for oscillations of muon neutrinos into electron neutrinos. If nature behaves as LSND suggests, our detector will collect about one thousand electron neutrino events over the next two years. If not, we won’t see any electron neutrinos. Either way, we’ll get a definite answer.”

The BooNE collaboration comprises 66 scientists from 13 institutions from across the United States. The 19-million-dollar MiniBooNE experiment has received funding both from DOE’s Office of Science and the National Science Foundation.

“In addition to the importance of the science, MiniBooNE is an example of a successful partnership among federal agencies, universities and national laboratories,” said Marvin Goldberg of the National Science Foundation. “The project has also set new standards for education and public outreach in the field of high-energy physics. The small scale of the project allows undergraduate and graduate students to participate fully in all of the experimental components.”

Fermilab is a U.S. Department of Energy national laboratory, operated under contract by Universities Research Association, Inc.

The BooNE website

The MiniBooNE virtual tour

Why is the MiniBooNE detector filled with baby oil?

Signs of a fourth neutrino?

Neutrino physics at Fermilab

Milestones in neutrino physics around the world

More about neutrinos worldwide

 

Batavia, Ill.-Officials at the Department of Energy’s Fermi National Accelerator Laboratory announced today (September 10, 2002) that the laboratory would close to most visitors, effective immediately. All visitors to Fermilab must now enter through the Pine Street gate on the west side of the laboratory. There, authorized visitors can obtain temporary visitors’ passes. The laboratory will also be closed to pedestrian and bicycle traffic.

Fermilab, traditionally open to visitors, closed its gates in response to security concerns at federal facilities following the September 11, 2001 terrorist attacks. Last month Fermilab re-opened to public access. Today, Fermilab Director Michael Witherell announced that the laboratory would increase security measures once again.

“I have been advised that, by order of the Secretary of Energy and effective immediately, DOE facilities are to operate at an increased level of security. This is in response to a heightened level of security throughout the nation and will remain in effect until further notice,” Witherell wrote in a message to laboratory employees and visiting scientists.

Fermilab officials said they did not know how long the increased security measures will remain in effect at the laboratory.

Fermilab is a Department of Energy national laboratory, operated by Universities Research Association, Inc.

Soudan, Minn.-Minnesota Congressman James Oberstar today (July 2) joined scientists and other officials in an underground ceremony dedicating the particle detector for the Main Injector Neutrino Oscillation Search. When the MINOS detector begins operating in early 2005, scientists expect that it will shed new light on the fast-changing field of the physics of neutrinos, subatomic particles with no charge and-or so scientists believed until recently-no mass.

“The MINOS detector dedication represents a milestone in the field of neutrino physics,” said Raymond Orbach, director of the Department of Energy’s Office of Science, from his Washington office. The Department, together with the National Science Foundation, funds the project. “Together with the results from other neutrino experiments around the world, MINOS will help unlock the secrets of these mysterious and ghostly particles, which play such a fundamental role in physics and the universe.”

The MINOS experiment will explore the newly revealed phenomenon of neutrino mass. In contrast to the long-held picture of neutrinos as massless particles, recent results from experiments in Japan and Canada have provided convincing evidence for the existence of “massive” neutrinos. The MINOS experiment will take the next steps in characterizing this newly observed phenomenon.

To carry out the MINOS experiment, scientists will use the Main Injector accelerator at the Department of Energy’s Fermi National Accelerator Laboratory in Batavia, Illinois, to send a beam of muon neutrinos 450 miles, or 735 kilometers, through the earth to a cavern half a mile underground in a former iron mine in northeastern Minnesota. There, the MINOS detector, a 5,500-ton “sandwich” of 456 alternating layers of 8-meter steel plates and plastic scintillator, will look for oscillations, or changes, of muon neutrinos to other neutrino flavors. The observation of such oscillations provides a means of studying neutrino mass.

Dr. Michael Witherell, Fermilab director, welcomed guests to the detector’s dedication Tuesday. Representative Oberstar, of Minnesota’s 8th district where the MINOS detector is located, joined MINOS scientists and officials from the University of Minnesota, the National Science Foundation and the Minnesota Department of National Resources in cutting a ribbon to dedicate the detector.

To date, some 250 of the total number of planes, constituting the detectors first “supermodule,” have been installed. Already, with only roughly half of the detector in place, scientists can detect the interactions of naturally occurring neutrinos coming to earth from space.

“We know our detector works,” said MINOS spokesman Stanley Wojcicki, a Stanford University physicist. “This is a moment that our MINOS collaboration has been working toward for many years.”

The MINOS collaboration includes some 200 scientists from 32 universities and laboratories in France, Russia, the United Kingdom, Greece and the United States.

Fermilab is a Department of Energy National Laboratory operated by Universities Research Association, Inc.

Batavia, Ill.-Combining the newest of astronomical instruments with the most venerable techniques of patient attention to detail, scientists at the Department of Energy’s Fermi National Accelerator Laboratory, the University of Chicago and other institutions believe they have made the first optical observation of a gamma ray burst afterglow unprompted by prior observation of the gamma ray burst itself-a so-called “orphan afterglow.”

This unprompted observation has significance for astrophysicists because it helps them distinguish among competing models for the mechanism of these phenomenally powerful cosmic explosions.

“A gamma ray burst lasts for just seconds,” said Fermilab astrophysicist and David N. Schramm Fellow John Beacom, a collaborator in the research. “But it produces an afterglow that lasts for a week or so, and that astronomers can see as a bright object in optical telescopes. The trick in seeing an afterglow comes in knowing where to look. All previously observed GRB afterglows have been found as follow-ups to observations from satellite-borne gamma ray detectors. Finding the glow without the burst is a first, and it’s an important clue to how gamma ray bursts work.”

Astrophysicists believe that gamma rays are emitted in two narrowly focused jets in opposite directions from the site of the GRB. But there are competing views on the directionality and extent of the afterglow. If the GRB jet were not pointing right at you, would you see its afterglow? Some models predict that the afterglow takes the same focused direction as the burst itself; others predict it might be isotropic, emitting light in all directions. The observation of an orphan afterglow supports the isotropic model, because now observers have seen the glow without first seeing the gamma rays themselves, meaning the gamma ray jets likely emerged in a different direction.

In a meticulous examination of data taken in 1999 and 2000 by the Sloan Digital Sky Survey, a project to create a three-dimensional map of the universe, the researchers located an object about 100 times brighter than the brightest known supernova. The object was associated with an otherwise normal galaxy about six billion light-years away. Based on its colors, the astronomers thought the bright object might be a quasar. But when they looked at data taken about a year later, they found that the brightness had faded by a factor of at least 10. Since quasars don’t vary that much in brightness, the observers knew they had found something unusual, neither supernova nor quasar but a “highly luminous optical transient.”

“When we saw that it had faded so much, we knew it couldn’t be a quasar,” said Fermilab astrophysicist Dan Vanden Berk. “Another class of very bright objects whose luminosity varies is a gamma ray burst afterglow. When we calculated the object’s luminosity from our knowledge of its distance, that was our first hint that we might be looking at a GRB afterglow.”

When the observers found that the pattern of intensity in the object’s colors closely matched the typical pattern for a GRB afterglow, their conviction grew that they had indeed found an orphan afterglow.

“All of these pieces-brightness, transience and characteristic colors-came together to spell ‘afterglow,'” said Fermilab astrophysicist Kev Abazajian, a collaborator. “Other celestial objects have some of these characteristics, but a GRB afterglow combines all three.”

Their observation was a marked departure from usual afterglow sightings. Although gamma ray bursts have been detected for more than 30 years, all the GRB afterglows on record have been prompted by gamma ray detection by satellites. When they detect a gamma ray burst, the satellites pass on the alert to ground-based astronomers, telling them when and where they should begin searching for the burst’s optical afterglow. Even with the satellite prompting, afterglows are very hard to spot. Although astronomers have detected thousands of GRB’s, only about 20 afterglows have been observed so far. Finding an orphan afterglow, one without a previously observed GRB, is much more difficult.

“Astronomers have searched for orphan afterglows for years,” said Fermilab astrophysicist Brian Lee. “It took the capability of the Sloan Digital Sky Survey to give us a realistic chance of seeing one.”

The SDSS is designed to peer deeply into wide swaths of the sky, compiling a definitive map of more than 100 million celestial objects, including galaxies and quasars. SDSS can gather images in five wavebands, analogous to photographic filters, to select interesting objects (such as quasars) for spectroscopic follow-up. The spectra reveal the identities and redshifts of celestial objects, the key to determining their distance from earth, and hence their brightness. The SDSS telescope’s unique combination of features-its wide field of view, its reach in seeing faint objects, and its simultaneous images in five wavebands-enables it to discern luminosities in different colors and effectively screen out background images.

Even using the Sloan Data, finding the afterglow was a painstaking process. Vanden Berk, Lee, and astrophysicists James Annis of Fermilab and Brian Wilhite of the University of Chicago sifted through thousands of digital images taken in the course of more than a year of observations with the 2.5-meter SDSS telescope at Apache Point Observatory in New Mexico. They used a technique developed by Vanden Berk to winnow the data to manageable size by selecting for color and then looking for fading brightness.

University of Chicago astrophysicist Don Lamb, a collaborator, pointed out that SDSS has so far collected only a small fraction of the data it will ultimately amass, opening the possibility for identifying more orphan afterglow candidates, and thus shedding more light on gamma ray bursts.

“Gamma ray bursts are like bright beacons telling us that if we look in their direction we will learn something very interesting and important about cosmology and the universe,” Lamb said.

The researchers have submitted their results for publication to The Astrophysical Journal. They also announced their results Wednesday, November 7 at the Woods Hole 2001/Gamma Ray Burst and Afterglow Astronomy workshop in Woods Hole, Mass. To see the abstract, preprint and accompanying images, go to www.arxiv.org/abs/astro-ph/0111054.

The SDSS (www.sdss.org) is a joint project of The University of Chicago, Fermilab, the Institute for Advanced Study, the Japan Participation Group, The Johns Hopkins University, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, Princeton University, the United States Naval Observatory, and the University of Washington. Funding for the Sloan Digital Sky Survey (SDSS) has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Aeronautics and Space Administration, the National Science Foundation, the U.S. Department of Energy, the Japanese Monbukagakusho, and the Max Planck Society.

Fermilab(www.fnal.gov) is operated by Universities Research Association, Inc., under contract with the U.S. Department of Energy.

Batavia, Ill.-Scientists at the Department of Energy’s Fermi National Accelerator Laboratory have found a surprising discrepancy between predictions for the behavior of neutrinos and the way the subatomic particles actually behave. Although the difference is tiny, it is the kind of inconsistency that makes the hair stand up on the back of a physicist’s neck, because it could be the first sign of something that profoundly changes our picture of nature.

Experimenters at Fermilab’s NuTeV (Neutrinos at the Tevatron) experiment measured the ratio of two types of particles-neutrinos and muons-emerging from high-energy collisions of neutrinos with target nuclei. The results of generations of particle experiments with other particles have yielded precise predictions for the value of this ratio, which characterizes the interactions of particles with the weak force, one of the four fundamental forces of nature. For other elementary particles, including the quarks and electrons of ordinary matter, the predictions seem to hold true. But, to the NuTeV experimenters’ surprise, when they looked at neutrinos with comparable precision, neutrinos did not appear to fall into line with expectations.

“We looked at a quantity that physicists call ‘sine squared theta W,'” said NuTeV physicist Sam Zeller, a graduate student from Northwestern University. “It tells us the strength of the interaction of neutrinos with the Z boson, one of the carriers of the weak force. The predicted value was 0.2227. The value we found was 0.2277, a difference of 0.0050. It might not sound like much, but the room full of physicists fell silent when we first revealed the result.”

The NuTeV result gets physicists’ attention because it doesn’t quite fit the Standard Model, the very precise theoretical picture that physicists have developed to explain fundamental particles and forces and their interactions. In particle physics, such “misfit” results are often the harbinger of new particles, new forces and new ways of seeing nature. The experimenters reported a three-sigma discrepancy in sin2qW, which translates to a 99.75 percent probability that the neutrinos are not behaving like other particles.

“Our picture of matter has held true for thirty years of experimental results,” said Fermilab Associate Director Michael Shaevitz, a NuTeV cospokesperson. “With the NuTeV result, it’s possible we may have stumbled across a crack in the model. As yet, we don’t know the explanation, but we believe it may foreshadow discoveries just ahead at accelerator laboratories.”

NuTeV collaborator Kevin McFarland, assistant professor of physics at the University of Rochester, emphasized that the NuTeV measurement would not be so striking if the experiment had not achieved an extraordinary level of precision, unprecedented for a neutrino experiment of its kind.

“Because we examined the interactions of millions of neutrinos and antineutrinos, their antimatter counterparts,” McFarland said, “we determined that there is only a one in four hundred chance that our measurement is consistent with the prediction. Unless this is a statistical fluke, it looks as if neutrinos may really behave differently from other fundamental particles. Further, experimenters using the Large Electron Positron at CERN, the European Particle Physics Laboratory, recently measured this same neutrino interaction in a different particle reaction. They saw the same discrepancy we found, although with less precision. The consistency between these two very different measurements is striking.”

The elusive neutrinos carry no electric charge and “feel” only the weak force, which is a hundred times weaker than the electromagnetic force. As a result, neutrinos rarely interact with each other or with other particles, making them extremely hard to detect. Physicists designed the NuTeV experiment in order to observe the interactions of millions of the highest-energy, highest-intensity neutrinos ever produced. Starting with a proton beam from Fermilab’s Tevatron, the world’s highest-energy particle accelerator, experimenters created a beam of neutrinos directed at a giant particle detector. The detector itself was a 700-ton sandwich of alternating slices of steel and detector. As the beam passed from the first to the last slice, one in a billion neutrinos collided with a target nucleus, breaking it apart.

After the collision with a nucleus, the neutrino could either remain a neutrino or turn into a muon, a particle that is a heavier cousin of the electron. When NuTeV experimenters saw a nucleus break up, they knew a neutrino had interacted. If they saw a particle leaving the scene of the collision, they knew it was a muon. If they saw nothing leaving, they knew a neutrino (invisible to the detector’s “eye”) had come and gone. The NuTeV scientists measured the ratio of muons to neutrinos and compared it with the predicted values, which other experiments have verified to a part per thousand accuracy for other particles. A painstaking years-long analysis of the NuTeV data revealed the unexpected discrepancy.

The 45-member NuTeV collaboration-small on the scale of today’s particle physics experiments-operated for 15 months in 1996 and 1997. Rochester’s McFarland presented the measurement at an October 26 seminar at Fermilab. The collaboration has submitted the results to Physical Review Letters for publication. The collaboration included physicists from the University of Cincinnati, Columbia University, Fermilab, Kansas State University, Northwestern University, the University of Oregon, the University of Pittsburgh and the University of Rochester. The research was supported by the National Science Foundation, the U.S. Department of Energy and the Alfred P. Sloan Foundation.

“This wouldn’t be the first time that neutrinos have surprised us,” said Northwestern’s Zeller, noting recent evidence for a small mass in the ghostly particles found by the millions in every gallon of space in the universe. “Their pervasive presence in the world around us means that even very subtle properties of neutrinos have profound implications for the way the universe works.”

Fermilab is operated by Universities Research Association, Inc. under a contract with the U.S. Department of Energy.