Auger Observatory closes in on long-standing mystery, links highest-energy cosmic rays with violent black holes

MALARGÜE, Argentina — Scientists of the Pierre Auger Collaboration announced today (Nov. 8) that active galactic nuclei are the most likely candidate for the source of the highest-energy cosmic rays that hit Earth. Using the Pierre Auger Observatory in Argentina, the largest cosmic-ray observatory in the world, a team of scientists from 17 countries found that the sources of the highest-energy particles are not distributed uniformly across the sky. Instead, the Auger results link the origins of these mysterious particles to the locations of nearby galaxies that have active nuclei in their centers. The results will appear in the Nov. 9 issue of the journal Science.

Active Galactic Nuclei (AGN) are thought to be powered by supermassive black holes that are devouring large amounts of matter. They have long been considered sites where high-energy particle production might take place. They swallow gas, dust and other matter from their host galaxies and spew out particles and energy. While most galaxies have black holes at their center, only a fraction of all galaxies have an AGN. The exact mechanism of how AGNs can accelerate particles to energies 100 million times higher than the most powerful particle accelerator on Earth is still a mystery.

“We have taken a big step forward in solving the mystery of the nature and origin of the highest-energy cosmic rays, first revealed by French physicist Pierre Auger in 1938,” said Nobel Prize winner James Cronin, of the University of Chicago, who conceived the Pierre Auger Observatory together with Alan Watson of the University of Leeds. “We find the southern hemisphere sky as observed in ultra-high-energy cosmic rays is non-uniform. This is a fundamental discovery. The age of cosmic-ray astronomy has arrived. In the next few years our data will permit us to identify the exact sources of these cosmic rays and how they accelerate these particles.”

Cosmic rays are protons and atomic nuclei that travel across the universe at close to the speed of light. When these particles smash into the upper atmosphere of our planet, they create a cascade of secondary particles called an air shower that can spread across 40 or more square kilometers (15 square miles) as they reach the Earth’s surface.

“The highest-energy cosmic rays must come from some of the most violent processes in the universe. Up until now we have known very little about their source,” said Dennis Kovar, acting associate director of the Office of Science for High Energy Physics at the Department of Energy. “These results represent an important step towards learning about the origin of these particles.”

The Pierre Auger Observatory records cosmic ray showers through an array of 1,600 particle detectors placed 1.5 kilometers (about one mile) apart in a grid spread across 3,000 square kilometers (1,200 square miles). Twenty-four specially designed telescopes record the emission of fluorescence light from the air shower. The combination of particle detectors and fluorescence telescopes provides an exceptionally powerful instrument for this research.

“Hundreds of scientists and dozens of funding agencies have contributed to the construction of the Pierre Auger Observatory,” said Joe Dehmer, director of the Physics Division at the National Science Foundation. “Now all these efforts are paying off. We already have seen Auger results on the cosmic-ray spectrum and composition, and today’s new result is the most dramatic achievement yet.”

While the observatory has recorded almost a million cosmic-ray showers, only the rare, highest-energy cosmic rays can be linked to their sources with sufficient precision. Auger scientists so far have recorded 77 cosmic rays with energy above 4 x1019 electron volts, or 40 EeV. This is the largest number of cosmic rays with energy above 40 EeV recorded by any observatory. At these ultra-high energies, the uncertainty in the direction from which the cosmic ray arrived is only a few degrees, allowing scientists to determine the location of the particle’s cosmic source.

“This result heralds a new window to the nearby universe and the beginning of cosmic-ray astronomy,” said Watson, a spokesperson of the Pierre Auger Collaboration. “As we collect more and more data, we may look at individual galaxies in a detailed and completely new way. As we had anticipated, our observatory is producing a new image of the universe based on cosmic rays instead of light.”

The Auger collaboration discovered that the 27 highest-energy events, with energy above 57 EeV, do not come equally from all directions. Comparing the clustering of these events with the known locations of 318 Active Galactic Nuclei, the collaboration found that most of these events correlated well with the locations of AGNs in some nearby galaxies, such as Centaurus A.

“Low-energy cosmic rays are abundant and come from all directions, mostly from within our own Milky Way galaxy. Until now the only source of cosmic ray particles known with certainty has been the sun. Cosmic rays from other likely sources such as exploding stars take meandering paths through space so that when they reach Earth it is impossible to determine their origins. But when you look at the highest-energy cosmic rays from the most violent sources, they point back to their sources. The challenge now is to record enough of these cosmic bullets to understand the processes that hurl them into space,” said Fermilab scientist Paul Mantsch, project manager of the Pierre Auger Observatory.

Cosmic rays with energy higher than about 60 EeV lose energy in collisions with the cosmic microwave background, radiation left over from the Big Bang that fills all of space. But cosmic rays from nearby sources are less likely to lose energy in collisions on their relatively short trip to Earth. Auger scientists found that most of the 27 events with energy above 57 EeV came from locations in the sky that include the nearest AGNs, within a few hundred million light years of Earth.

Scientists think that most galaxies have black holes at their centers, with masses ranging from a million to a few billion times the mass of our sun. The black hole at the center of our Milky Way galaxy weighs about 3 million solar masses, but it is not an AGN. Galaxies that have an AGN seem to be those that suffered a collision with another galaxy or some other massive disruption in the last few hundred million years. The AGN swallows the mass coming its way while releasing prodigious amounts of radiation. The Auger result indicates that AGNs may also produce the universe’s highest-energy particles.

Cosmic-ray astronomy is challenging, because low-energy cosmic rays provide no reliable information on the location of their sources: as they travel across the cosmos, they are deflected by galactic and intergalactic magnetic fields that lead to blurry images. In contrast, the most energetic particles come almost straight from their sources, as they are barely affected by the magnetic fields. Unfortunately, they hit Earth at a rate of only about one event per square kilometer per century, which demands a very large observatory.

Because of its size, the Auger Observatory can record about 30 ultra-high-energy events per year. The Auger collaboration is developing plans for a second, larger installation in Colorado to extend coverage to the entire sky while substantially increasing the number of high-energy events recorded.

“Our current results show the promising future of cosmic-ray astronomy,” said Auger cospokesperson Giorgio Matthiae, of the University of Rome. “So far we have installed 1400 of the 1600 particle detectors of the Auger Observatory in Argentina. A northern site would let us look at more galaxies and black holes, increasing the sensitivity of our observatory. There are even more nearby AGNs in the northern sky than in the southern sky.”

The Pierre Auger Observatory is being built by a team of more than 370 scientists and engineers from 17 countries.

“The collaboration is a true international partnership in which no country contributed more than 25 percent of the US$54-million construction cost,” said Danilo Zavrtanik, of the University of Nova Gorica and chair of the Auger Collaboration Board. The names of the funding agencies contributing to the Pierre Auger Observatory as well as the names of the participating institutions are listed below.

Groundbreaking for the southern hemisphere site of the Pierre Auger Observatory took place on March 17, 1999, in Argentina’s Mendoza Province. Following a period of detector deployment and testing, scientific data collection began in January 2004.

“Argentina is pleased to host and participate in this unique scientific endeavor,” said Alberto Etchegoyen, of Comisión Nacional de Energía Atómica and Southern Observatory spokesperson, “and now, looking back into these years of efforts and excitement, a feeling of gratitude and respect arises for all collaboration members who took care of every single minor detail leading to today’s announcement.”

The observatory is named for French scientist Pierre Victor Auger (1899-1993), who in 1938 was the first to observe the extensive air showers generated by the interaction of high-energy cosmic rays with the Earth’s atmosphere.

Notes for editors:

Fermilab, which hosts the project management office for the Pierre Auger Observatory, is a U.S. Department of Energy Office of Science national laboratory, operated under contract by Fermi Research Alliance, LLC. DOE and NSF have designated Universities Research Association, Inc. as the U.S. representative on the observatory’s international oversight board, currently chaired by URA President Fred Bernthal.

Country representatives who can provide national press releases for 17 countries are listed at:http://www.auger.org/contact/

Photos and background information: http://www.auger.org/media

Auger Observatory funding agencies (by country):

International
ALFA-EC / HELEN
UNESCO

Argentina
Comisión Nacional de Energía Atómica
Fundación Antorchas
Gobierno De La Provincia de Mendoza
Municipalidad de Malargüe

Australia
Australian Research Council

Brazil
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Financiadora de Estudos e Projetos (FINEP)
Fundação de Amparo à Pesquisa do Estado de Rio de Janeiro (FAPERJ)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Ministério de Ciência e Tecnologia (MCT)

Czech Republic
Ministry of Education, Youth and Sports of the Czech Republic

France
Centre National de la Recherche Scientifique (CNRS)
Conseil Régional Ile-de-France
Département Physique Nucléaire et Corpusculaire (PNC-IN2P3/CNRS)
Département Sciences de l’Univers (SDU-INSU/CNRS)

Germany
Bundesministerium für Bildung und Forschung (BMBF)
Deutsche Forschungsgemeinschaft (DFG)
Finanzministerium Baden-Württemberg
Helmholtz-Gemeinschaft Deutscher Forschungszentren (HGF)
Ministerium für Wissenschaft und Forschung, Nordrhein Westfalen
Ministerium für Wissenschaft, Forschung und Kunst, Baden-Württemberg

Italy
Istituto Nazionale di Fisica Nucleare (INFN)
Ministero dell’Istruzione, dell’Università e della Ricerca (MIUR)

Mexico
Consejo Nacional de Ciencia y Tecnología (CONACYT)

Netherlands
Ministerie van Onderwijs, Cultuur en Wetenschap
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)
Stichting voor Fundamenteel Onderzoek der Materie (FOM)

Poland
Ministry of Science and Higher Education

Portugal
Fundação para a Ciência e a Tecnologia

Slovenia
Ministry for Higher Education, Science, and Technology
Slovenian Research Agency

Spain
Comunidad de Madrid
Consejería de Educacíon de la Comunidad de Castilla La Mancha
FEDER funds
Ministerio de Educacíon y Ciencia
Xunta de Galicia

United Kingdom
Science and Technology Facilities Council

United States
Department of Energy
Grainger Foundation
National Science Foundation

Auger Observatory collaborating institutions (by country):

Argentina
Centro Atómico Bariloche (CNEA); Instituto Balseiro (CNEA & UNCuyo); CONICET
Instituto de Astronomía y Física del Espacio (CONICET)
Laboratorio Tandar (CNEA); CONICET; Univ. Tec. Nac. (Reg. Buenos Aires)
Pierre Auger Southern Observatory
Universidad Nacional de la Plata; IFLP/CONICET; Univ. Nac. de Buenos Aires
Universidad Tecnológica Nacional – Regionales Mendoza y San Rafael

Australia
University of Adelaide

Bolivia
Universidad Catolica de Bolivia
Universidad Mayor de San Andrés

Brazil
Centro Brasileiro de Pesquisas Fisicas (CBPF)
Pontifícia Universidade Católica, Rio de Janeiro
Universidade de Sao Paulo, Inst. de Fisica
Universidade Estadual de Campinas (UNICAMP)
Universidade Estadual de Feira de Santana (UEFS)
Universidade Estadual do Sudoeste da Bahia (UESB)
Universidade Federal da Bahia
Universidade Federal do ABC (UFABC)
Universidade Federal do Rio de Janeiro (UFRJ)
Universidade Federal Fluminense

Czech Republic
Charles University Prague, Institute of Particle and Nuclear Physics
Institute of Physics (FZU) of the Academy of Sciences of the Czech Republic

France
Institut de Physique Nucléaire, Orsay (IPNO)
Laboratoire AstroParticule et Cosmologie Université Paris VII
Laboratoire de l’Accélérateur Linéaire (LAL), Orsay
Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), Université Paris 6
Laboratoire de Physique Subatomique et de Cosmologie (LPSC) – Grenoble

Germany
Bergische Universität Wuppertal
Forschungszentrum Karlsruhe – Institut für Kernphysik
Forschungszentrum Karlsruhe – Institut für Prozessdatenverarbeitung und Elektronik
Max-Planck-Institut für Radioastronomie and Universität Bonn
Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen
Universität Karlsruhe (TH) – Institut für Experimentelle Kernphysik (IEKP)
Universität Siegen

Italy
Dipartimento di Fisica dell’Università and INFN, L’Aquila
Dipartimento di Fisica dell’Università and Sezione INFN, Milano
Dipartimento di Fisica dell’Università di Napoli “Federico II” and Sezione INFN, Napoli
Dipartimento di Fisica dell’Università di Roma “Tor Vergata” and Sezione INFN Roma II
Dipartimento di Fisica e Astronomia dell’Università di Catania & Sezione INFN, Catania
Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Torino
Dipartimento di Fisica, Università del Salento and Sezione INFN
Istituto di Fisica dello Spazio Interplanetario (INAF), Dipartimento di Fisica Generale dell’Università and Sezione INFN, Torino
Laboratori Nazionali del Gran Sasso, INFN
Osservatorio Astrofisico di Arcetri

Mexico
Benemérita Universidad Autónoma de Puebla (BUAP)
Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV)
Universidad Michoacana de San Nicolás de Hidalgo
Universidad Nacional Autónoma de México

Netherlands
Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud Universiteit
Kernfysisch Versneller Instituut (KVI), Rijksuniversiteit Groningen
Nationaal Instituut voor Kernfysica en Hoge Energie Fysica (Nikhef)
Stichting Astronomisch Onderzoek in Nederland (ASTRON), Dwingeloo

Poland
Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences
University of Łódź

Portugal
Laboratory of Instrumentation and Experimental Particle Physics (LIP)

Slovenia University of Nova Gorica

Spain
Instituto de Física Corpuscular, CSIC-Universitat de València
Universidad Complutense de Madrid
Universidad de Alcalá de Henares
Universidad de Santiago de Compostela
University of Granada

United Kingdom
Oxford University
University of Leeds, School of Physics & Astronomy

United States
Argonne National Laboratory
Case Western Reserve University
Colorado School of Mines
Colorado State University, Fort Collins
Colorado State University, Pueblo
Columbia University
Fermi National Accelerator Laboratory
Louisiana State University
Michigan Technological University
New York University
Northeastern University
Ohio State University
Pennsylvania State University
Southern University
University of California, Los Angeles
University of Chicago
University of Colorado
University of Hawaii
University of Minnesota
University of Nebraska
University of New Mexico
University of Utah
University of Wisconsin-Madison
University of Wisconsin-Milwaukee

Vietnam
Institute of Nuclear Science and Technology of Hanoi (INST)

Batavia, Ill. — Restoring a native prairie and recycling material are just two examples of the environmentally friendly activities run by the Department of Energy’s Fermi National Accelerator Laboratory. The highlight, however, is a management philosophy at the core of the laboratory that goes far beyond. On October 11, Fermilab officially received international recognition of its environmentally sound management practices at a small ceremony at the lab.

NSF International Strategic Registrations, represented at the ceremony by William Rutledge, awarded Fermilab with the ISO 14001 certification for its environmental management system. NSF International Strategic Registrations is a company that provides management systems registrations worldwide.

“This is a notable achievement for Fermilab,” said Bill Griffing, director of Environment, Safety & Health at Fermilab. “We have a reputation for environmental excellence in the United States. The ISO 14001 registration puts our name on a list of corporations recognized internationally for their excellent environmental management systems.”

For many years, Fermilab’s commitment to the environment has gone beyond meeting its obligations under federal, state and local regulations. The laboratory’s dedication to reducing its impact on the environment crosses all levels of organization, including major project planning, how individuals perform their daily activities, and waste-saving opportunities offered to visitors when they come to the laboratory.

Recent improvements at Fermilab include better recycling opportunities for various types of material and working with neighboring communities to compost brush picked up at their curbsides. Fermilab also participates in the Federal Electronics Challenge to manage and recycle electronic items.

The ISO 14001 standards require an organization to meet a stringent set of criteria. The organization must have an infrastructure and management plan that allows it to comply with environmental laws and standards, to improve its environmental performance and to achieve measurable environmental objectives.

An ISO 14001-certified organization must have an environmental management system that assesses the environmental impacts of all activities taking place across the organization, from the planning of major new projects to the daily activities of workers. Managers must communicate with their employees about environmental aspects of their work and look at ways to minimize the environmental impact of daily activities.

“We’ve had many components of an environmental management system in place for some time,” said Paul Kesich, manager of the Environmental Protection Team at Fermilab. “In 2006, we decided to seek ISO 14001 certification to strengthen our system and to gain more credibility. We developed the missing components and began the registration process. The laboratory went through three audits, including a weeklong onsite audit conducted by two NSF International Strategic Registrations representatives.”

Fermilab is a national laboratory funded by the Office of Science of the U.S. Department of Energy, operated by the Fermi Research Alliance, LLC. The DOE Office of Science is the largest supporter of basic research in the physical sciences in the nation. Fermilab is home to the Tevatron, the world’s highest-energy particle accelerator, and is a leader in the development of accelerator technology since the laboratory’s founding in 1967.

BATAVIA, Ill. – Chicago Mayor Richard Daley announced today (Oct. 2, 2007) that Fermilab in Batavia produced the seventh most important scientific achievement in the six-county Chicago region.

Daley named the top ten scientific innovations, discoveries and events in Chicago history during a ceremony in Daley Plaza. A plaque and banners in plaza commemorate the scientific accomplishments.

The Department of Energy’s Fermi National Accelerator Laboratory earned seventh place for the discovery March 2, 1995, of the top quark, the last of the missing subatomic building blocks thought to make up all the matter in the world, including people, plants and buildings. The top quark plays a role in determining the weight of you and everything around you.

“It is wonderful that a fundamental science discovery about how the universe is made makes it into the top 10 scientific achievements of Chicago,” said Fermilab Director Pier Oddone.

The top quark was one of the key missing pieces in the theory of how matter is formed from a variety of combinations of 12 elementary particles. All matter exists of atoms, which are comprised of smaller particles such as protons, neutrons and electrons, which are comprised of even smaller particles called quarks.

The top quark is the heaviest of all the elementary particles, nearly 40 times heavier than the next heaviest quark.

It took nearly a thousand scientists from more than a dozen countries 18 years to discover the top quark in two Fermilab experiments: CDF and DZero. The physics world drew a collective sigh of relief at the discovery.

If the top quark had failed to exist, the scientific community would have been turned on its head, having to rethink nearly three decades of research and billions of dollars of experiments. The top quark’s discovery validated the Standard Model of particles and forces, essentially a how-to guide to building the material world. As the heaviest of the fundamental particles of nature, the top quark’s discovery and measurement allows scientists to test theories of supersymmetry, new forces and extra dimensions.

Fermilab scientists had to recreate the conditions that existed right after the Big Bang to search for the top quark, which is believed to have vanished less than a billionth of a second after the start of the universe. To produce just one top quark, scientists had to slam protons and their antiparticles, antiprotons, together at nearly the speed of light using Fermilab’s Tevatron, the highest-energy accelerator in the world. Collisions were measured in particle detectors the size of three-story homes. The detectors observed hundreds of thousands of collisions per second. Every once in a while, a proton and an antiproton would collide just right, and the energy set free produced, the top quark, which is about 200 times heavier than a proton.

Fermilab continues to be the only place in the world producing the top quark. At the time the top quark was discovered, only a few dozen were produced each year, but today thousands are produced annually at Fermilab and studied by scientists from across the globe in an attempt to get a better understanding of how the universe works.

“We would like to get a few more in the top 10 in the future,” Oddone said.

About Fermilab
Fermilab is a national laboratory funded by the Office of Science of the U.S. Department of Energy, operated by the Fermi Research Alliance, LLC.

Links to more information and photos from Fermilab:
http://www.fnal.gov/pub/inquiring/physics/discoveries/top_quark.html
http://www.symmetrymagazine.org/cms/?pid=1000496

Graphics/photos:

Graphic of collision producing top quark
http://www-visualmedia.fnal.gov/VMS_Site/gallery/stillphotos/1995/0700/95-0754D.hr.jpg

Photo with top quark newspaper articles:
http://www-visualmedia.fnal.gov/VMS_Site/gallery/stillphotos/1996/0000/96-0027.hr.jpg

Photos of the Tevatron/accelerator complex:
http://www-visualmedia.fnal.gov/VMS_Site/gallery/stillphotos/1995/0300/95-0341.jpg
http://www-visualmedia.fnal.gov/VMS_Site/gallery/stillphotos/2004/0400/04-0475D.hr.jpg
http://www-visualmedia.fnal.gov/VMS_Site/gallery/stillphotos/2003/0300/03-0390-18D.hr.jpg

Photos of CDF (1990s):
http://www-visualmedia.fnal.gov/VMS_Site/gallery/stillphotos/1992/0100/92-0110.hr.jpg
http://www-visualmedia.fnal.gov/VMS_Site/gallery/stillphotos/1996/0400/96-0419.hr.jpg

Photos of DZero (1990s):
http://www-visualmedia.fnal.gov/VMS_Site/gallery/stillphotos/1996/0300/96-0368-12.hr.jpg
http://www-visualmedia.fnal.gov/VMS_Site/gallery/stillphotos/1999/1000/99-1067.hr.jpg

About Science in the City

Nominations were selected from museums, universities and community partners in Chicago’s scientific arena. A panel of scientists, historians and educators from area universities, colleges a Chicago public school and laboratories voted on the winners.

View the Chicago press release and complete top 10 list at:
http://www.chicagoscienceinthecity.org/ScientificInovations.html

MALARGÜE, Argentina — Scientists of the Pierre Auger Collaboration will begin today (July 3) the public release of one percent of the cosmic-ray events recorded by the Pierre Auger Observatory in Argentina. New cosmic-ray data-about 70 events per day-will be posted on a daily basis. The data and their visualizations are available atwww.auger.org and www.auger.org.ar.

The international Pierre Auger Collaboration, which includes scientists from 17 countries, explores the origins of extremely rare ultra-high-energy cosmic rays-particles from space that hit Earth, some with energies 100 million times higher than those made by the world’s highest-energy particle accelerator, the Tevatron at Fermilab. These are the highest-energy particles ever recorded in nature. When such a particle hits the atmosphere it creates an air shower that can contain 200 billion particles by the time it reaches the ground.

The one-percent release is part of the worldwide Pierre Auger education and outreach program. It will allow teachers to expose students to real scientific data and the breathtaking processes that take place in the cosmos, hurling charged particles toward Earth. The two Web sites provide the data both as graphical displays and in tabular form. For each cosmic-ray air shower, the Web sites show the energy and direction of the incoming cosmic-ray particle. The public data provides information on cosmic-rays with extremely high energy, up to 5 x 10^19 electron volts (eV).

When construction is complete near the end of the year, the Pierre Auger Observatory will extend over 3,000 square kilometers (~1,000 square miles) in Argentina’s Mendoza Province, just east of the Andes Mountains. The full observatory will consist of an array of 1,600 detectors that record the arrival of air showers on the ground. Information gathered by the detectors is transmitted to a central data acquisition system using solar-powered cellular phone technology. Surrounding the detector array and looking toward its center is a set of 24 telescopes that-on clear moonless nights-observe the ultraviolet fluorescence light produced as shower particles travel through the atmosphere.

The Pierre Auger collaboration includes more than 370 scientists and engineers from 60 institutions in 17 countries, which share the construction cost of approximately $50 million (US). The international funding agencies contributing to the Pierre Auger Observatory as well as the participating institutions are listed below.

Notes for editors:

Fermilab, which hosts the project management office for the Pierre Auger Observatory, is a U.S. Department of Energy Office of Science national laboratory, operated under contract by Fermi Research Alliance, LLC.

Images are available at: http://www.auger.org/media/

Auger Observatory funding agencies (by country):

ALFA-EC
UNESCOArgentina
Comisión Nacional de Energía Atómica
La Provincia de MendozaAustralia
The Australian Research CouncilBrazil
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Financiadora de Estudos e Projetos do Ministerio da Ciencia e Tecnologia (FINEP / MCT)
Fundação de Amparo à Pesquisa do Estado de Rio de Janeiro (FAPERJ)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Czech Republic
Ministry of Education, Youth and Sports of the Czech RepublicFrance
Centre National de la Recherche Scientifique (CNRS)
Conseil Régional Ile-de-France
Département Physique Nucléaire et Corpusculaire (PNC-IN2P3/CNRS)
Département Sciences de l’Univers (SDU-INSU/CNRS)Germany
Bundesministerium für Bildung und Forschung (BMBF)
Deutsche Forschungsgemeinschaft (DFG)
Finanzministerium Baden-Württemberg
Helmholtz-Gemeinschaft Deutscher Forschungszentren (HGF)
Ministerium für Wissenschaft und Forschung, Nordrhein Westfalen
Ministerium für Wissenschaft, Forschung und Kunst, Baden-WürttembergItaly
Istituto Nazionale di Fisica Nucleare (INFN)
Ministero dell’Istruzione, dell’Università e della Ricerca (MIUR)Mexico
Consejo Nacional de Ciencia y Tecnología (CONACYT)Netherlands
Ministerie van Onderwijs, Cultuur en Wetenschap
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)
Stichting voor Fundamenteel Onderzoek der Materie (FOM)Poland
Ministry of Science and Higher EducationPortugal
Fundação para a Ciência e a TecnologiaSlovenia
Ministry for Higher Education, Science, and Technology
Slovenian Research AgencySpain
Comunidad de Madrid
Consejería de Educacíon de la Comunidad de Castilla La Mancha
FEDER funds
Ministerio de Educacíon y Ciencia
Xunta de GaliciaUnited Kingdom
Science and Technology Facilities CouncilUnited States
Department of Energy
National Science Foundation
The Grainger Foundation

Auger Observatory collaborating institutions (by country):

Argentina
Centro Atómico Bariloche (CNEA); Instituto Balseiro (CNEA & UNCuyo); CONICET
Instituto de Astronomía y Física del Espacio (CONICET)
Laboratorio Tandar (CNEA); CONICET; Univ. Tec. Nac. (Reg. Buenos Aires)
Pierre Auger Southern Observatory
Universidad Nacional de la Plata; IFLP/CONICET; Univ. Nac. de Buenos Aires
Universidad Tecnológica Nacional – Regionales Mendoza y San RafaelAustralia
University of AdelaideBolivia
Universidad Catolica de Bolivia
Universidad Mayor de San AndrésBrazil
Centro Brasileiro de Pesquisas Fisicas (CBPF)
Universidade de Sao Paulo, Inst. de Fisica
Universidade de Sao Paulo, Instituto Astronomico e Geofisico
Universidade Estadual de Campinas (UNICAMP)
Universidade Estadual de Feira de Santana (UEFS)
Universidade Estadual do Sudoeste da Bahia (UESB)
Universidade Federal da Bahia
Universidade Federal do Rio de Janeiro (UFRJ)
Universidade Federal FluminenseCzech Republic
Charles University Prague, Institute of Particle and Nuclear Physics
Institute of Physics (FZU) of the Academy of Sciences of the Czech RepublicFrance
Institut de Physique Nucléaire, Orsay (IPNO)
Laboratoire AstroParticule et Cosmologie Université Paris VII
Laboratoire de l’Accélérateur Linéaire (LAL), Orsay
Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), Université Paris 6
Laboratoire de Physique Subatomique et de Cosmologie (LPSC) – GrenobleGermany
Bergische Universität Wuppertal
Forschungszentrum Karlsruhe – Institut für Kernphysik
Forschungszentrum Karlsruhe – Institut für Prozessdatenverarbeitung und Elektronik
Max-Planck-Institut für Radioastronomie and Universität Bonn
Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen
Universität Karlsruhe (TH) – Institut für Experimentelle Kernphysik (IEKP)
Universität SiegenItaly
Dipartimento di Fisica dell’Università and INFN, L’Aquila
Dipartimento di Fisica dell’Università and Sezione INFN, Lecce
Dipartimento di Fisica dell’Università and Sezione INFN, Milano
Dipartimento di Fisica dell’Università and Sezione INFN, Napoli
Dipartimento di Fisica dell’Università di Roma “Tor Vergata” and Sezione INFN Roma II
Dipartimento di Fisica Sperimentale dell’Università and Sezione INFN, Torino
Istituto di Fisica dello Spazio Interplanetario (INAF), Dipartimento di Fisica Generale dell’Università
Laboratori Nazionali del Gran Sasso, INFN
Osservatorio Astrofisico di Arcetri
Sezione INFN di Catania & Dipartimento di Fisica e Astronomia dell’Università, CataniaMexico
Benemérita Universidad Autónoma de Puebla (BUAP)
Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV)
Universidad Michoacana de San Nicolás de Hidalgo
Universidad Nacional Autónoma de MéxicoNetherlands
Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radboud Universiteit
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Batavia, Ill.-Scientists at the Department of Energy’s Fermi National Accelerator Laboratory have announced the observation of the cascade b baryon-again.

In a paper submitted for publication to Physical Review Letters on June 12, scientists of Fermilab’s DZero experiment announced their discovery of the “triple scoop” baryon, which contains one quark from each generation of matter.

Then, on June 15, scientists from Fermilab’s CDF experiment announced their own independent cascade b observation.

At a packed Fermilab seminar on June 15, no sooner had DZero’s Eduard De La Cruz Burelo sat down after presenting DZero’s discovery of the cascade b baryon than Dmitry Litvintsev of Fermilab’s CDF collaboration rose to present CDF’s observation of the cascade b baryon to the same standing-room-only audience. The CDF scientists will submit their results for publication this week.

The newly discovered cascade is made of a down, a strange and a bottom quark. It is the first observed baryon formed of quarks from all three families of matter. After independently gathering and analyzing data from Fermilab’s Tevatron collider for more than six years, the two Fermilab collider experiments reported the results of the their search for the cascade b baryon within days of each other.

“It is remarkable that our two collaborations would uncover the same particle at practically the same time,” said Jacobo Konigsberg, University of Florida physicist and cospokesperson of the CDF experiment.

The CDF and DZero experiments are located about a mile apart on the Tevatron accelerator ring. Each collaboration numbers about 700 physicists from universities and laboratories worldwide. Currently, CDF and DZero are the highest-energy collider experiments in the world. As the start of operations at the Large Hadron Collider in Europe approaches, interest heightens in particle physics discoveries at Fermilab.

“These are very exciting times for the Tevatron program,” said Director Pier Oddone. “There is a friendly yet intense competition between the two experiments, and this is a healthy thing. Not only are they able to cross-check each other, they are also pushing harder, knowing that their sister experiment may be doing exactly the same thing at the same moment.”

The two collaborations found a remarkably similar number of proton-antiproton collisions that resulted in the production and detection of such rare, previously unseen, particles. From the trillions of collisions that have occurred in each experiment since 2001, the DZero experiment reported 19 candidate cascade b baryons, while the CDF experiment had 17. Both experiments measured the mass of this new particle. DZero measured 5.774 ± 0.019 GeV/c²; and CDF measured the mass with even greater precision at 5.7929 ± 0.0030 GeV/c². The two results are consistent.

“This is a demonstration of the beauty and power of the laws of physics. By studying these collisions, two different teams, using different apparatus, at different points of the Tevatron accelerator, are able to find an incredibly rare particle, formed by three different quarks, and get a consistent picture of nature,” said CDF cospokesperson Rob Roser, Fermilab.

To keep their research unbiased, experimental collaborations normally share their results only when they are final, through publications in scientific journals. Once each collaboration publishes its individual results on a particular topic, the experiments sometimes combine those published results in order to obtain an even better result with higher precision. The cooperation and teamwork needed to combine final results will be increasingly important as both collaborations push to find rare subatomic processes, including those that involve the elusive Higgs boson.

The discovery of the cascade b is the latest in a chain of discoveries made by CDF and DZero in the last few years. Last October, the CDF collaboration discovered another particle related to the cascade b, the sigma b. As the Tevatron delivers more and more data, the possibilities increase for the observation of even rarer processes.

Notes for editors:

The June 13, 2007 press release on the DZero discovery of the cascade b baryon is at http://news.fnal.gov/2007/06/fermilab-physicists-discover-triple-scoop-baryon/

Technical information on the CDF observation of the cascade b baryon is at: http://www-cdf.fnal.gov/physics/new/bottom/070607.blessed-cascadeB/

Fermilab is a Department of Energy Office of Science national laboratory operated under contract by the Fermi Research Alliance, LLC. CDF is an international experiment of 700 physicists from 61 institutions and 13 countries. It is supported by the U.S. Department of Energy, the U.S. National Science Foundation and a number of international funding agencies (the full list can be found at http://www-cdf.fnal.gov/collaboration/Funding_Agencies.html). In 1995, the CDF and DZero experiments discovered the top quark, the final and most massive quark in the Standard Model.

 

BATAVIA, Illinois – Members of the public are invited to become “citizen scientists” and help ecologists track prairie restoration at the Department of Energy’s Fermi National Accelerator Laboratory with the Prairie Quadrat Program. Participants in the program, which is free and begins this month, will learn how to identify prairie plants, map a prairie plot and help Fermilab ecology experts track restoration progress.

“This program gives citizens an opportunity to take ‘real science’ data while exploring the Fermilab prairie, walking through plants six to eight feet tall,” said Sue Sheehan, Fermilab’s Education Program Leader.

Participating citizen scientists spend about two hours collecting information in the prairie and then enter the data into a Web site scientists use to monitor the prairie’s condition. Participants can come once or multiple times during the summer to observe changes in the prairie; they can also continue to track the prairie for years to come. The volunteers will get to hike and explore parts of Fermilab’s preserve that are not normally open to the public.

This is the second year the Fermilab Education Office is offering this program. “We are looking forward to seeing returning as well as new volunteers this summer,” Sheehan said.

Most of this summer’s sessions are geared toward adults and children ages 14 and up. A special session for children entering the 4th grade and above will take place in July. There are a total of seven outings throughout the summer. All sessions are free of charge.

A complete schedule of sessions and registration information can be found athttp://ed.fnal.gov/programs/quadrat/.

Fermilab is a national laboratory funded by the Office of Science of the U.S. Department of Energy, operated by Fermi Research Alliance, LLC.

Three-quark particle contains one quark from each family.

Batavia, Ill. – Physicists of the DZero experiment at the Department of Energy’s Fermi National Accelerator Laboratory have discovered a new heavy particle, the Ξ_b (pronounced “zigh sub b”) baryon, with a mass of 5.774±0.019 GeV/c², approximately six times the proton mass. The newly discovered electrically charged Ξ_bbaryon, also known as the “cascade b,” is made of a down, a strange and a bottom quark. It is the first observed baryon formed of quarks from all three families of matter. Its discovery and the measurement of its mass provide new understanding of how the strong nuclear force acts upon the quarks, the basic building blocks of matter.

The DZero experiment has reported the discovery of the cascade b baryon in a paper submitted to Physical Review Letters on June 12.

“Knowing the mass of the cascade b baryon gives scientists information they need in order to develop accurate models of how individual quarks are bound together into larger particles such as protons and neutrons,” said physicist Robin Staffin, Associate Director for High Energy Physics for the Department of Energy’s Office of Science.

The cascade b is produced in high-energy proton-antiproton collisions at Fermilab’s Tevatron. A baryon is a particle of matter made of three fundamental building blocks called quarks. The most familiar baryons are the proton and neutron of the atomic nucleus, consisting of up and down quarks. Although protons and neutrons make up the majority of known matter today, baryons composed of heavier quarks, including the cascade b, were abundant soon after the Big Bang at the beginning of the universe.

The Standard Model elegantly summarizes the basic building blocks of matter, which come in three distinct families of quarks and their sister particles, the leptons. The first family contains the up and down quarks. Heavier charm and strange quarks form the second family, while the top and bottom, the heaviest quarks, make the third. The strong force binds the quarks together into larger particles, including the cascade b baryon. The cascade b fills a missing slot in the Standard Model.

Prior to this discovery, only indirect evidence for the cascade b had been reported by experiments at the Large Electron-Positron collider at the CERN Laboratory near Geneva, Switzerland. For the first time, the DZero experiment has positively identified the cascade b baryon from its decay daughter particles in a remarkably complex feat of detection. Most of the particles produced in high-energy collisions are short-lived and decay almost instantaneously into lighter stable particles. Particle detectors such as DZero measure these stable decay products to discover the new particles produced in the collision.

Once produced, the cascade b travels several millimeters at nearly the speed of light before the action of the weak nuclear force causes it to disintegrate into two well-known particles called J/Ψ (“jay-sigh”) and Ξ^– (“zigh minus”). The J/Ψ then promptly decays into a pair of muons, common particles that are cousins of electrons. The Ξ^– baryon, on the other hand, travels several centimeters before decaying into yet another unstable particle called a Λ (“lambda”) baryon, along with another long-lived particle called a pion. The Λ baryon too can travel several centimeters before ultimately decaying to a proton and a pion. Sifting through data from trillions of collisions produced over the last five years to identify these final decay products, DZero physicists have detected 19 cascade b candidate events. The odds of the observed signal being due to something other than the cascade b are estimated to be one in 30 million.

DZero is an international experiment of about 610 physicists from 88 institutions in 19 countries. It is supported by the Department of Energy, the National Science Foundation, and a number of international funding agencies. Fermilab is a national laboratory funded by the Office of Science of the U.S. Department of Energy, operated under contract by Fermi Research Alliance, LLC.
Notes for editors:

The DZero paper on the cascade b discovery is available in the hep/ex preprint location at http://arxiv.org/abs/0706.1690.

DZero collaborating institutions:

• Universidad de Buenos Aires, Buenos Aires, Argentina
• LAFEX, Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil
• Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil
• Instituto de Fisica Teorica, Universidade Estadual Paulista, Sao Paulo, Brazil
• University of Alberta, McGill University, Simon Fraser University and York University, Canada
• University of Science and Technology of China, Hefei, People’s Republic of China
• Universidad de los Andes, Bogota, Colombia
• Charles University, Center for Particle Physics, Prague, Czech Republic
• Czech Technical University, Prague, Czech Republic
• Institute of Physics, Academy of Sciences, Center for Particle Physics, Prague, Czech Republic
• Universidad San Francisco de Quito, Quito, Ecuador
• Laboratoire de Physique Corpusculaire, IN2P3-CNRS, Universite Blaise Pascal, Clermont-Ferrand, France
• Laboratoire de Physique Subatomique et de Cosmologie, IN2P3-CNRS, Universite de Grenoble, Grenoble, France
• CPPM, IN2P3-CNRS, Universite de la Mediterranee, Marseille, France
• Laboratoire de l’Accelerateur Lineaire, IN2P3-CNRS et Universite Paris-Sud, Orsay, France
• LPNHE, Universites Paris VI and VII, IN2P3-CNRS, Paris, France
• DAPNIA/Service de Physique des Particules, CEA, Saclay, France
• IPHC, IN2P3-CNRS, Universite Louis Pasteur Strasbourg, and Universite de Haute Alsace, France
• Institut de Physique Nucleaire de Lyon, IN2P3-CNRS, Universite Claude Bernard, Villeurbanne, France
• RWTH Aachen, III. Physikalisches Institut A, Aachen, Germany
• Universitat Bonn, Physikalisches Institut, Bonn, Germany
• Universitat Freiburg, Physikalisches Institut, Freiburg, Germany
• Universitat Mainz, Institut fur Physik, Mainz, Germany
• Ludwig-Maximilians-Universitat Munchen, Munchen, Germany
• Fachbereich Physik, University of Wuppertal, Wuppertal, Germany
• Panjab University, Chandigarh, India
• Delhi University, Delhi, India
• Tata Institute of Fundamental Research, Mumbai, India
• University College Dublin, Dublin, Ireland
• Korea Detector Laboratory, Korea University, Seoul, Korea
• SungKyunKwan University, Suwon, Korea
• CINVESTAV, Mexico City, Mexico
• FOM-Institute NIKHEF and University of Amsterdam/NIKHEF, Amsterdam, The Netherlands
• Radboud University Nijmegen/Nikhef, Nijmegen, The Netherlands
• Joint Institute for Nuclear Research, Dubna, Russia
• Institute for Theoretical and Experimental Physics, Moscow, Russia
• Moscow State University, Moscow, Russia
• Institute for High Energy Physics, Protvino, Russia
• Petersburg Nuclear Physics Institute, St. Petersburg, Russia
• Lund University, Royal Institute of Technology, Stockholm University, and Uppsala University, Sweden
• Lancaster University, Lancaster, United Kingdom
• Imperial College, London, United Kingdom
• University of Manchester, Manchester, United Kingdom
• University of Arizona, Tucson, Arizona, USA
• Lawrence Berkeley National Laboratory and University of California, Berkeley, California, USA
• California State University, Fresno, California, USA
• University of California, Riverside, California, USA
• Florida State University, Tallahassee, Florida, USA
• Fermi National Accelerator Laboratory, Batavia, Illinois, USA
• University of Illinois at Chicago, Chicago, Illinois, USA
• Northern Illinois University, DeKalb, Illinois, USA
• Northwestern University, Evanston, Illinois, USA
• Indiana University, Bloomington, Indiana, USA
• University of Notre Dame, Notre Dame, Indiana, USA
• Purdue University Calumet, Hammond, Indiana, USA
• Iowa State University, Ames, Iowa, USA
• University of Kansas, Lawrence, Kansas, USA
• Kansas State University, Manhattan, Kansas, USA
• Louisiana Tech University, Ruston, Louisiana, USA
• University of Maryland, College Park, Maryland, USA
• Boston University, Boston, Massachusetts, USA
• Northeastern University, Boston, Massachusetts, USA
• University of Michigan, Ann Arbor, Michigan, USA
• Michigan State University, East Lansing, Michigan, USA
• University of Mississippi, University, Mississippi, USA
• University of Nebraska, Lincoln, Nebraska, USA
• Princeton University, Princeton, New Jersey, USA
• State University of New York, Buffalo, New York, USA
• Columbia University, New York, New York, USA
• University of Rochester, Rochester, New York, USA
• State University of New York, Stony Brook, New York, USA
• Brookhaven National Laboratory, Upton, New York, USA
• Langston University, Langston, Oklahoma, USA
• University of Oklahoma, Norman, Oklahoma, USA
• Oklahoma State University, Stillwater, Oklahoma, USA
• Brown University, Providence, Rhode Island, USA
• University of Texas, Arlington, Texas, USA
• Southern Methodist University, Dallas, Texas, USA
• Rice University, Houston, Texas, USA
• University of Virginia, Charlottesville, Virginia, USA
• University of Washington, Seattle, Washington, USA

 

Batavia, Illinois – Kathleen Stanley of Warrenville, a graduating senior at Rosary High School in Aurora who hopes to major in chemical engineering in college, has been named the recipient of the Fermilab Science Award and scholarship, sponsored by the Fermilab Friends for Science Education and the Franklin Fund. The award and scholarship were presented Wednesday night, May 23 in a ceremony at Rosary High School.

The award is given annually to a high school senior in DuPage or Kane County, with considerations for academic achievement, participation in activities such as science clubs, academic competition, talent searches, original work and internships. The $1,000 scholarship, awarded this year for the first time, is provided by FFSE in partnership with Paul DesCouteaux, Geneva, of the Franklin Fund.

Ms. Stanley, daughter of Mr. and Mrs. Keith Stanley, participated in Rosary’s Math and Chemistry WYSE teams, representing the school in the Illinois State Finals in Champaign. She is president of the school’s National Honor Society chapter, and a member of both Mu Alpha Theta (National High School and Two-Year College Mathematics Honor Society) and the Foreign Language Honor Society. She is also a two-sport athlete, received the Coach’s Award in both soccer and basketball.

“Kathleen is a highly gifted scholar athlete and a well-rounded, respected person,” said Sr. Patricia Burke, O.P., Principal of Rosary High School. “She is a kind and supportive leader with a wonderful sense of humor. Despite her busy schedule, she makes time for others in need. Her generous spirit will take her far in the years ahead.”

In presenting the award to Ms. Stanley, FFSE President Marge Bardeen said: “Kathleen is a very strong science student, and we are sure her future will be bright.”

The Fermilab Friends for Science Education is a non-profit organization supporting education outreach programs at Fermilab. Information on the organization and membership is available here.

Fermi National Accelerator Laboratory is the home of the Tevatron, the world’s highest-energy particle accelerator and a leader in the development of accelerator technology since the laboratory’s founding in 1967. Fermilab collaborates closely with laboratories around the world on R&D for the International Linear Collider and future accelerator facilities proposed for Illinois, including heavy ion acceleration and high intensity neutrino sources. Particle beams from Fermilab’s accelerator complex are used to treat cancer patients at Fermilab Neutron Therapy Facility. Fermilab is managed by the Fermi Research Alliance, LLC for the U.S. Department of Energy’s Office of Science.

CHICAGO, Ill. – In celebration of Particle Accelerator Day this weekend in Illinois, two U.S. Department of Energy Laboratories, Argonne National Laboratory and Fermi National Accelerator Laboratory, have planned events at their respective accelerator facilities. This is the second year that the two labs are celebrating “Particle Accelerator Day”- a celebration that follows Governor Rod Blagojevich’s proclamation of April 21 as Particle Accelerator Day in Illinois.

“The technology of particle accelerators will translate into significant scientific and economic benefits for our state and our nation, so I am happy to once again declare April 21st ‘Particle Accelerator Day’ in Illinois and encourage everyone to learn more about the contributions of this incredible technology to our world,” said Gov. Blagojevich. “Argonne National Laboratory and Fermi National Accelerator Laboratory work every day to advance important new technologies and discoveries and we look forward to continue supporting both federal labs in attracting even larger investments into these facilities.”

Fermilab and Argonne National Laboratory are world leaders in the science, technology and operation of particle accelerators. Last year both labs formalized their intent to collaborate on accelerator technology through a Memorandum of Understanding making Illinois a global center of excellence in the development of accelerator technology, both for scientific discovery and for the security and economic competitiveness of the State of Illinois and the nation.

“These are exciting times for accelerator scientists,” says Argonne director Robert Rosner, “and we are delighted with Governor Blagojevich’s proclamation of ‘Illinois Particle Accelerator Day.’ Our state is home to one of the most diverse set of accelerators in the world, carrying out research in science areas as different as particle and nuclear physics to material science, biological and medical sciences and energy sciences, based on close collaborations between national labs, universities, and industry; and such collaborations position Illinois as a recognized leader in accelerator science.”

Argonne is celebrating “Illinois Particle Accelerator Day” today by hosting a class of honors chemistry students from the College of DuPage. These students have been using Argonne’s accelerator research facilities to perform experiments as a part of their class, and today will tour the Advanced Photon Source. Argonne scientists will give them a glimpse into the world of particle physics, and will discuss the role of accelerators in today’s world and the unique discoveries they make.

The Department of Energy’s Fermi National Accelerator Laboratory will celebrate “Particle Accelerator Day” with Illinois high school students from Lincoln Park High School, who tour the laboratory on Monday. The students will also join Fermilab physicists for a discussion of the role of accelerators in the discovery of the fundamental nature of the universe. Scientists will share their own experiences as students and their excitement at the revolutionary discoveries that are unfolding in the field of particle physics.

Each year, some 20,000 students from middle school through university visit Fermilab to tour the facility and learn first-hand about science at a national accelerator laboratory.

“We thank Governor Blagojevich for his proclamation recognizing the role of particle accelerators in making the State of Illinois a center of scientific leadership,” said Fermilab Director Pier Oddone. “We look forward to celebrating ‘Particle Accelerator Day’ with Illinois students at Fermilab. After all, ‘Accelerator’ is our middle name!”

The text of the Governor’s Particle Accelerator Day proclamation is available here.

About Argonne and Fermilab Argonne National Laboratory
The nation’s first national laboratory, Argonne National Laboratory conducts basic and applied scientific research across a wide spectrum of disciplines, ranging from high-energy physics to climatology and biotechnology. Argonne operates the Advanced Photon Source, one of the world’s highest intensity x-ray light sources. Since 1990, Argonne has worked with more than 600 companies and numerous federal agencies and other organizations to help advance America’s scientific leadership and prepare the nation for the future. Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy‘s Office of Science.

Fermi National Accelerator Laboratory
Fermilab is the home of the Tevatron, the world’s highest-energy particle accelerator and a leader in the development of accelerator technology since the laboratory’s founding in 1967. Fermilab collaborates closely with Argonne and with other laboratories around the world on R&D for the International Linear Collider and future accelerator facilities proposed for Illinois, including heavy ion acceleration and high intensity neutrino sources. Particle beams from Fermilab’s accelerator complex are used to treat cancer patients at Fermilab Neutron Therapy Facility. Fermilab is managed by the Fermi Research Alliance, LLC for the U.S. Department of Energy‘s Office of Science.

Batavia, Illinois–Scientists of the CDF and DZero experiments at the Department of Energy’s Fermi National Accelerator Laboratory presented today (April 15) at the annual April meeting of the American Physical Society the latest results of intriguing measurements made with the Tevatron particle collider. Highlights of the presentations were the observation of rare particle processes never observed before and new constraints on the mass of the Higgs boson, which in principle make the observation of this elusive particle at the Fermilab Tevatron collider more likely. Based on the world’s best measurements of the top quark mass and the W boson mass, the new upper limit for the mass of the Higgs boson is now 144 GeV/c² with 95 percent probability.

More than 60 scientists working on the Tevatron experiments are presenting results at the APS meeting in Jacksonville, Florida. They are showing results for the rare production of single top quarks, one of the rarest collision processes ever observed at a hadron collider; a new measurement of the top quark mass; the first observation of events that simultaneously produce a W boson and a Z boson, an important milestone in the search for the Higgs boson; an update on measurements of bottom quarks, including B_s oscillations; and searches for new particles predicted by Supersymmetry and other theoretical models. These searches have led to more stringent constraints on the masses of supersymmetric particles and forces associated with such particles.

The steadily increasing number of collision events produced by the Tevatron as well as the innovative analysis methods employed by CDF and DZero scientists bode well for future discoveries. In particular, the direct experimental exclusion of a Higgs boson with a mass near 160 GeV/c² seems to be within reach while searches for a Higgs boson with lighter mass will require more data. The Tevatron experiments will collect 2-3 times more data in the next two years. This will give the two experiments access to extremely rare subatomic processes, including access to a significant region of the expected Higgs mass range.

Here is a summary of the key results obtained by the Tevatron experiments, presented at a press conference at the APS conference in Jacksonville, Florida, on April 15:

I. The top quark and the Higgs, presented by Kevin Lannon, Ohio State University:

1. Combining their latest measurements, the Tevatron experiments find the value of the top quark mass to be 170.9 GeV/c², with an uncertainty of only 1 percent. This precision already exceeds the goal set for the entire duration of Tevatron Collider Run II, which is expected to continue until 2009. This new top quark mass value lowers the predicted range of allowed Higgs boson mass.
2. The DZero collaboration has observed the first evidence of single top quarks produced in a rare subatomic process involving the weak nuclear force. The result is an important test of predictions made by particle theory, such as the number of quarks that exist in nature. The measurement yields the first constraints on the electroweak parameter V_tb, which is related to the probability of the top quark decaying into bottom quark. The observation of single top quarks validates new analysis techniques that provide scientists with improved tools to search for the Higgs boson.

II. W and Z bosons and the Higgs, presented by Gerald Blazey, Northern Illinois University:

1. Both Tevatron experiments have recorded candidate events for the production of a pair of Z bosons in a single collision, with the CDF experiment reporting a first value of the cross section of this process. The ZZ process is the final step before reaching the even rarer process of a Higgs boson decaying into a pair of W bosons.
2. The CDF collaboration recorded 16 collisions that produced simultaneously a W boson and a Z boson, a milestone on the path to discovering the Higgs. The WZ cross section is one of the rarest ones ever measured.
3. The CDF collaboration has produced the world’s best individual measurement of the W mass, better than measurements made by any other single experiment, despite the large backgrounds that hadron colliders such as the Tevatron produce compared to the “cleaner” collision environments at lepton colliders. Combining the CDF result with other measurements worldwide leads to a lower average value of the W-boson mass of 80,398 +/- 25 MeV/c², representing a precision of 3 parts in 10,000.
4. The new upper limit for the mass of the Higgs boson based on the new values for the W boson mass and the top quark mass is 144 GeV/c² with 95 percent probability.
5. The experimental sensitivity for directly observing the Higgs boson is steadily improving. The Tevatron experiments are within reach of directly excluding a Higgs boson with mass near 160 GeV/c². Searches for a Higgs boson with lighter mass will require more data.

III. Searches for non-Standard Model Higgs bosons and exotic particles, presented by Ulrich Heintz, Boston University:

1. Scientists think that dark matter is made of particles not accounted for in the Standard Model of Particles and Forces. A leading candidate for dark matter particles are supersymmetric particles such as charginos and neutralinos. The Tevatron experiments have greatly extended the constraints on the properties of these particles.
2. The Tevatron experiments have set new limits on a variety of particles predicted by Supersymmetry and other beyond-Standard Model theories. For example, DZero and CDF set new lower limits on the mass of non-standard W and Z bosons of 965 and 923 GeV/c², respectively.

Notes for editorsFermilab is a Department of Energy Office of Science national laboratory operated under contract by the Fermi Research Alliance, LLC. CDF is an international experiment of 700 physicists from 61 institutions and 13 countries. DZero is an international experiment conducted by about 700 physicists from 90 institutions and 20 countries. The experiments are supported by the U.S. Department of Energy, the U.S. National Science Foundation and a number of international funding agencies.

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