First protons of 2010 circulate in LHC

February 28, 2010 | 7:06 am

Yesterday just before 11:25 p.m. Central European Time, the first protons of 2010 were injected in the Large Hadron Collider. By 2:45 a.m. CET a proton beam had made hundreds of turns around the 27-kilometer ring in one direction, and the same feat was completed in the other direction by 4:10 a.m. The beams had an energy of 450 billion electron volts (GeV), which is the energy at which they are injected into the LHC.

The circulating beams marked the end of a ten week particle-free hiatus for the world’s largest particle accelerator, during which LHC scientists and engineers have prepared the machine for it’s biggest challenge yet, particle collisions at an energy of seven trillion electron volts (TeV). The beams also mark the beginning of the LHC’s first long run, expected to last until at least mid-year 2011.

Over the next few weeks, the energy of the proton beams will be ramped up toward this year’s goal: colliding 3.5-TeV beams in the center of the LHC experiments.

by Daisy Yuhas

Symmetry Intern

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Physics is a hoot when it’s a tweet

February 26, 2010 | 5:24 am

Update:  You can read this article in Belarusian here.

Kids today.

Such may have been the disapproving sigh of an observer watching a busload of teenagers tour Fermi National Accelerator Laboratory last week. The 11^th and 12^th graders from Appleton, Wisconsin, spent an awful lot of time typing away on their cell phones. But be not dismayed, O horrified observer. They were just doing their homework.

“I was looking for a way for them to journal, but in a more realistic way. I think that’s what texting is and definitely what Twitter is—a way to journal,” says Dale Basler, instigator of all that cell-phone gazing and a physics teacher at Appleton East High School.

Basler gave the students several assignments for the field trip to Argonne National Laboratory and Fermilab; he’d set up a Twitter feed, and one option was to post tweets throughout the day.

But he laid out some ground rules. The students had to do at least 16 tweets, on a variety of topics–physics topics–and, Basler says, he enforced strict cell phone etiquette: ringers off, and utmost discretion while tweeting. 

He did allow for some lighthearted posting. “I figured it’s the same as talking around the lab table while you’re setting up an experiment,” Basler says. “But I told them they’d only get credit for ones with appropriate subjects.”

After touring Argonne, where the students learned about the laboratory’s isotope research and gamma detector, the class grabbed a quick breakfast, prompting both excitement and outrage (Ohmgeeee , “Finally getting some food!” SLAppletonEast , “What…only 20min to eat…”) Then it was off to Fermilab.

Within the first five minutes, the students unleashed upon the World Wide Web the following observations: Fermilab is huge, the tour guide has an awesome British accent, the main building is 16 stories tall, it was built in 1972, the entryway is made from steel from the USS Princeton aircraft carrier, and the atrium’s giant pendulum moves throughout the day, demonstrating the Earth’s spin.

Their thumbs were just getting warmed up.

Over the course of the morning, IGetPhysical noted, “Protons and antiprotons are collided using 5 accelerators that speed particles up to 99.996% the speed of light.” Tweeter xJamarcusx  exclaimed, “Fermilab uses up to one trillion volts of energy to accelerate the particle!”  Some students stuck to more temporal matters (crazo708, “We just ran up stairs to wake up. Phew.”)

The class commented on the wonders of neutrinos’ ghost-like travels, nuclear fission and fusion, the benefits of neutron therapy for cancer treatment, and the puzzle of dark matter’s omnipresence in the universe.

The trip wrapped up with a lecture from Dan Hooper, an associate scientist in the theoretical astrophysics group (coconutcarrier, “Sitting down to talk with a real physicist at Fermilab!”)  Hooper says he answered eager queries about the big bang, the origin of matter, dark energy, and the meaning of time.

“When the hour was up and they had to go catch their bus, it was hard to end. They were a very good group,” Hooper says.

When informed the students were tweeting throughout the discussion, Hooper was somewhat surprised.

“I didn’t notice at all,” he says. “I had no idea. To be honest, I’m not really sure what that means. I’m not that technologically savvy.” Proving that, to even the most brilliant minds, Twitter can be an enigma on par with the deepest mysteries of the cosmos.

During the 3½ -hour trip back to Wisconsin, the students reflected on their experiences (tylersoi , “Just left fermelab. The lecture at the end was by far the best part.” em_cee_squared,  “Learned a lot today. I am glad I went on this trip.” )

They even used Twitter to make some scientific observations of their own. One of the last tweets of the day came from  xJamarcusx: “BUS JUST BROKE DOWN!!!”

Andrea E. Mustain

Symmetry Intern

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First T2K neutrino event observed at Super-Kamiokande

February 25, 2010 | 11:30 am

Physicists from the Japanese-led multinational T2K collaboration announced today that they had made the first detection of a neutrino which had traveled all the way under Japan from their neutrino beamline at the J-PARC facility in Tokai village (about an hour north of Tokyo by train) to the gigantic Super-Kamiokande underground detector near the west coast of Japan, 295 km (185 miles) away from Tokai.

“It is a big step forward,” said T2K spokesperson Takashi Kobayashi. “We’ve been working hard for more than 10 years to make this happen.”

They have constructed their new neutrino beamline, which will deliver the world’s most powerful neutrino beams, to study the mysterious phenomenon known as neutrino oscillations, and the observation of this event proves that their study can now begin.

“Neutrinos are the elusive ghosts of particle physics,” Kobayashi explains. “They come in three types, called electron neutrinos, muon neutrinos, and tau neutrinos, which used to be thought to be immutable.”

Interacting only weakly with matter, neutrinos can traverse the entire earth with vastly less attenuation than light passing through a window. The very weakness of their interactions allows physicists to make what should be very accurate predictions of their behavior, and thus it came as a shock when measurements of the flux of neutrinos coming from the thermonuclear reactions which power our sun were far lower than predicted. A second anomaly was then clearly demonstrated by Super-Kamiokande, when it showed that the flux of different types of neutrino generated within our atmosphere by cosmic ray interactions was different depending on whether the neutrinos were coming from above or below (which should not have been possible given our understanding of particle physics). Other experiments, such as KamLAND (also performed at Kamioka), have conclusively demonstrated that these anomalies are caused by neutrino oscillations, whereby one type of neutrino turns into another.

“Congratulations from CERN on the first T2K neutrino event seen at Super-Kamiokande,” said CERN Director General Rolf Heuer. “Switching on the world’s first neutrino superbeam is a great achievement, and is set to bring great advances in the understanding of this most elusive of particles. Even in a time of financial difficulty around the globe, it’s important not to lose sight of the fact that basic science is and always will be a crucial element of progress. It is therefore heartening to see such an important new basic science initiative getting underway now.”

The T2K experiment has been built to make measurements of unprecedented precision of known neutrino oscillations, and to look for a so-far unobserved type of oscillation which would cause a small fraction of the muon neutrinos produced at J-PARC to become electron neutrinos by the time they reach Super-Kamiokande.

“This first neutrino event marks a great achievement for T2K and a milestone for the fast-growing field of neutrino physics worldwide,” said Fermilab Director Pier Oddone. “We send warmest congratulations from Fermilab, along with our best wishes for the exciting science that will follow.”

Excitement is shared by Dr. Nigel Smith, SNOLAB Director: “SNOLAB warmly congratulates the T2K team on this tremendous milestone for their project, which highlights the great achievements made by this collaboration in the development of new detectors and accelerator technology. The knowledge that T2K will tease out about the elusive neutrino will further our understanding of these sub-atomic particles and their role within the Universe, and why the Universe looks the way it is.” Prof. Dr. Joachim Mnich, Director in charge of High Energy Physics and Astroparticle Physics at DESY also notes: “Warmest congratulations from DESY on seeing the first neutrino event and thus becoming leader in the race to understand the elusive neutrino! Through our long history of collaboration with Japanese scientists and labs we value your work most highly and hope that the T2K project will help make the neutrino less elusive.”

Observing the new type of oscillation would open the prospect of comparing the oscillations of neutrinos and anti-neutrinos, which many theorists believe may be related to one of the great mysteries in fundamental physics–why is there more matter than anti-matter in the universe? “The observation of this first neutrino (see figure) means that the hunt has just begun,” said Prof. Koichiro Nishikawa, Director of the Institute for Particle and Nuclear Studies at KEK and founder of T2K. “The first physics results are expected later this year. This is the beginning. I am waiting for a lot more to come soon!”

Background: The T2K collaboration consists of 508 physicists from 62 institutes in 12 countries (Japan, South Korea, Canada, the United States, the United Kingdom, France, Spain, Italy, Switzerland, Germany, Poland, and Russia). The experiment consists of a new neutrino beamline using the recently constructed 30 GeV synchrotron at the J-PARC laboratory in Tokai, Japan, a set of near detectors constructed 280m from the neutrino production target, and the Super-Kamiokande detector in western Japan.

This release was issued on Feb. 25, 2010 by KEK.

Press Release

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Fermilab’s CDF, DZero cite banner year at the Tevatron

February 24, 2010 | 3:04 pm

As physicists from Fermilab’s Tevatron collider experiments, CDF and DZero, prepare to share their newest results at upcoming winter 2010 physics conferences, they took a few moments recently to look back on the accomplishments of 2009.

“By every measure,” said DZero spokesperson and University of Manchester physicist Stefan Soldner-Rembold, “the Tevatron set new records and built upon its stellar physics program of exciting discoveries and ultra-precise measurements.”

Both CDF and DZero investigate proton-antiproton collisions at 2 TeV, the world’s highest energy for a particle-antiparticle collider.  Combined, the two experiments involve over 1000 scientists from about 146 institutions in 27 countries. They have been operating the CDF and DZero experiments since 2001. The two collaborations expect to continue taking data through 2011, doubling the number of collisions that each experiment analyzed for their 2009 results.

“The Fermilab accelerator complex has continued to operate in superb fashion,” said CDF spokesperson Rob Roser. “The Tevatron set many new records for the number of collisions per second and the number of collisions delivered to experiments in a given week, month and year.  The Tevatron has now substantially exceeded its design parameters, providing CDF and DZero physicists with ever-expanding scientific opportunities.”

In the final week of 2009, the Fermilab accelerator complex set a lifetime record for the hours of collider operation in a single week, producing 151 hours of physics data.

The experiments have made good use of the torrent of data. In 2009, they published over 100 scientific papers and presented more than 150 new results at physics conferences all over the world.  Major highlights include the discovery of the production of single top quarks in the first observation of this extremely rare process. The collaborations made the world’s most precise measurement of the top-quark and W-boson masses with a precision of less than one per cent and one per mille, respectively; and they observed and studied new particles containing b quarks.  By combining their data, the CDF and DZero experiments also reached important new conclusions on the possible mass of the proposed Higgs particle, now excluding a mass range near that of twice the mass of the W boson (162-166 GeV/c²).

“In 2009, CDF and DZero continued to push the boundaries of the unknown,” said Fermilab Director Pier Oddone. “They have a good opportunity to exclude the existence or see first evidence of the elusive Higgs particle over the next two years.”

While journal articles are the “currency” of fundamental research, they are not its only measure.  Over 60 Ph.D. students graduated in 2009 after performing research at the Tevatron experiments, bringing the total number of Ph.D.’s to over 1000 since the Tevatron program began.

“Training new generations of scientists is a major success of the Tevatron program,” said DZero spokesperson Dmitri Denisov “In fact, a large fraction of the scientists now working at CERN’s Large Hadron Collider have trained at the Tevatron, bringing a wealth of experience with them to CERN.”

Fermilab physicists are watching with interest the restart of the LHC in Europe.

“We are all excited about the first LHC physics results,” said CDF spokesperson and University of Florida physicist Jacobo Konigsberg.  “At the same time, we have had remarkable results from the Tevatron program at Fermilab over the past year, and we’re looking forward eagerly to what the coming months will reveal.”

Judy Jackson

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US scientists analyze first LHC data through the Open Science Grid

February 23, 2010 | 5:34 am

On November 30, 2009, the Large Hadron Collider became the most powerful particle accelerator in the world. Over the next month, the LHC’s four particle detectors recorded 100,000 particle collisions at record-breaking energies. Since then, scientists around the world have been continuously analyzing and re-analyzing the long-awaited collision data, and are publishing the first scientific papers . These first collisions have tested not only the LHC and experiments, but also the global and national computing systems that link scientists around the world with LHC data.

The task of connecting scientists with LHC data falls to the Worldwide LHC Computing Grid, a collaboration linking computing grid infrastructures with each other and with 170 computing centers in 34 countries. In the United States, the Open Science Grid enables scientists to connect with the WLCG, and thus with data from their LHC experiments.

“We’re very proud to see how the Open Science Grid assisted LHC experiments during 2009,” says Ruth Pordes, OSG executive director. “It gives us confidence that the Worldwide LHC Computing Grid will enable future physics discoveries.”

The Open Science Grid allows the LHC experiments to access, maintain, and move huge quantities of data in the US. Through the OSG, experiments distribute the data taken from the detector to special computing centers called Tier-1 facilities. The two largest such facilities in the US are Fermi National Accelerator Laboratory for the CMS experiment and Brookhaven National Laboratory for ATLAS. Through the OSG, US centers make available roughly 7 petabytes of data for the ATLAS experiment and 4.4 petabytes for CMS. To give a sense of scale, one petabyte is roughly equivalent to the data stored in 10,000 laptops.

From a Tier-1 facility, data are accessed by smaller Tier-2 and Tier-3 facilities such as universities, where students and scientists study the data. Even now, when the LHC is not running, the data in Tier-1 facilities are being accessed continually as scientists study 2009 data to improve their models and predictions about what the LHC may reveal.

“On average right now, we are running anywhere from 6,000 to 10,000 computer processing tasks with this data at all times. It’s really amazing to see how such a large computing infrastructure spread over five Tier-2 and a Tier-1 facility can operate at this level continuously,” says US ATLAS operations coordinator, Kaushik De.

Though the LHC was only running for two months, the data collected during 2009 has given experiments like ATLAS and CMS, which search for a range of new physics phenomena, an opportunity to better understand their detectors. Studies of a detector’s behavior may not make headlines like a big-name physics discovery, but they are crucial to all future research. In order for scientists to recognize a never-before-seen phenomenon, whether it is the Higgs boson or dark matter, they need to know what to expect from the detector when looking at familiar physics events.

With this crucial study of the detector under way, scientists are even more prepared and excited for the discoveries to come. The importance of the 2009 data to the experiments was evident from the high volume of experimental collaborators accessing the LHC data through the Open Science Grid.

“The activity level was driven heavily by the number of people interested,” says CMS computing coordinator Ian Fisk. “A lot of people had been waiting for this.”

As the LHC begins collisions at even higher energies in the coming month, thousands of experimental collaborators worldwide will want to study the data. The successes of 2009 suggest that the OSG is fully prepared for the challenge.

Daisy Yuhas

Symmetry Intern

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Herman Winick accepts Sakharov Prize

February 22, 2010 | 8:02 am

At the 2010 April Meeting of the American Physical Society last week in Washington DC, SLAC physicist Herman Winick accepted the Andrei Sakharov Prize, given to a physicist for outstanding leadership and/or achievements in upholding human rights.  Also accepting the award was Joseph Birman of the City College of New York and the City University of New York, and Morris (Moishe) Pripstein, of the National Science Foundation.

Winick is a founding member of the Synchrotron light for Experimental Science and Applications in the Middle East (SESAME) collaboration, a synchrotron facility currently under construction in Jordan. The SESAME collaboration will consist of scientists from 9 Middle Eastern countries, some of which are currently engaged in conflicts with each other, with other nations, or internally. Winick said he hopes that the SESAME collaboration, along with bringing a third-generation light source to an area which currently does not have such a facility, will foster relationships between people from these countries. And not just scientists: Winick wants to have SESAME used as an international meeting facility for topics other than science. Collaborations like these may ultimately lead SESAME scientists to take up a practice that Winick has exercised many times before: to defend their international colleagues if they are persecuted by their home governments.  Winick shared the story of one such colleague during his acceptance speech.

In 2001 Winick was communicating regularly with Mohamed Hadi Hadizadeh, a native Iranian physicist whom everyone just called “Hadi.” The two were working on plans for SESAME together when Hadizadeh’s emails suddenly stopped coming.  Winick waited for communication, but instead heard from Hadiadeh’s wife, who told Winick  the Iranian government had put her husband in jail on charges of planning to overthrow the government.

“This stunned me,” said Winick. “How could someone that they knew [was] dedicated to…improving conditions in Iran be punished so severely?”

Winick and a group of supporters worked furiously to have Hadizadeh freed from prison. They started an international letter-writing campaign and eventually gathered written support from 34 Nobel laureates. “I had helped other scientists and other dissidents,” Winick continued. “However, this was the first time I was helping someone with whom I had a working relationship and a friendship, who was being severely persecuted for opinions which I shared.”

Hadizadeh was released on bail and returned to teaching, but was soon given a sentence of almost nine years in prison. As is often done in Iran, the government did not imprison Hadizadeh right away, but have the right to arrest him and send him to prison at any time.

Winick worked with a group of international physicists, some from the SESAME collaboration, to find temporary work opportunities for Hadizadeh in Japan, Jordan and Italy, so that he and his family could leave Iran. Hadizadeh and his family then moved to the United States; where they remained for five years while Hadizadeh taught and did research at the University of Ohio. They stayed with Winick and his family, as have many international scientists who came to the US under similar conditions.

Today, Hadizadeh, his wife, and one of their daughters have returned to Iran, while his oldest daughter is completing her PhD in physics at Northwestern University. Hadizadeh may still be called to go to prison. Winick said he believes that if Hadizadeh were imprisoned, many international physicists and scholars would come to his aid.

“Individual scientists like myself, and professional societies like APS and ACS, play an important role in supporting colleagues who are persecuted by government,” Winick continued. “Scientists have helped dissidents leave danger in their home countries and find employment in other countries, allowing them to continue to function as scientists.” He praised the program Scholars at Risk, created by New York University, which raises funds to support academics and their families who flee persecution in their home countries and seek sanctuary in the United States.

The Sakharov Prize was established in honor of Russian physicist Andrei Sakharov, who actively called for nuclear arms control during the Cold War. His actions lead to the loss of many of his own personal freedoms, while also earning him a Nobel Peace Prize in 1975.

Herman Winick is a Professor emeritus at the Stanford Linear Accelerator Center (SLAC) and the Applied Physics Department of Stanford University, where he has been since 1973. After receiving his AB (1953) and PhD (1957) in physics from Columbia University, he continued work in experimental high energy physics at the University of Rochester (1957-9) and then as a member of the scientific staff and Assistant Director of the Cambridge Electron Accelerator at Harvard University (1959-73). In the early 1960’s his interests shifted to accelerator physics and synchrotron radiation, moving to Stanford University in 1973 to take charge of the technical design of the Stanford Synchrotron Radiation Project. For the past 30 years he has played a leadership role in the development of synchrotron radiation sources and research at Stanford and around the world. He has served, and often chaired, review and advisory committees for projects in Armenia, Australia, China, Germany, India, Japan, Jordan, Russia, Taiwan, Thailand and the US. (From the Forum on International Physics).

Calla Cofield

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This week at the LHC: Preparing for the first protons of 2010

February 19, 2010 | 2:52 pm

After more than a month of preparation, the Large Hadron Collider could be circulating proton beams again as early as next week. Since the beginning of the new year, the Large Hadron Collider has been shut down to prepare the machinery for collisions at 7 TeV total energy (3.5 TeV per beam), the highest energy level ever attained by a particle accelerator.

This preparation has focused heavily on readying the LHC’s quench detection and protection systems, which keep the accelerator magnets from overheating. This has included replacing 4,000 connectors for cables and testing the magnets at increasing electrical levels up to six kiloamperes. For a closer look at the technical details of the winter shutdown, see the CERN Bulletin.

A few tests remain, including a careful check of the beam injection system and simultaneously powering the LHC’s more than 9,000 magnets. If all goes smoothly, the LHC will be well on its way to record-breaking collisions.

by Daisy Yuhas

Symmetry Intern

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New NOvA building pops up almost overnight

February 18, 2010 | 3:27 pm

This story first appeared in Fermilab Today on February 18, 2010.

The curvy MINOS surface building at Fermilab has a new neighbor. The new neutrino experiment in town recently moved in right next door.

Ward Commercial Construction Inc. of East Dundee began building the foundation for the NOvA Near-Detector surface building in late December, but putting up the prefabricated wall panels took only two days.

The NOvA collaboration will construct two detectors in the path of a beam of neutrinos generated at Fermilab. The Near Detector will gather data on-site at Fermilab, and the Far Detector will study the beam in Ash River, Minn., at a laboratory of the University of Minnesota’s School of Physics and Astronomy.

The base of the new building measures 72 by 35 feet, and it stands about 37 feet high. It will house the NOvA Near Detector during its year-long trial run, before the detector moves 330 feet underground into a hall below the MINOS building.

The NOvA collaboration plans to outfit the surface building with heat, lights, ventilation and structural steel and be ready to take data on July 12, said John Cooper, NOvA project manager at Fermilab.

The collaboration members have worked to match the design of the Near Detector as closely as possible to that of the Far Detector – except that the Near Detector will weigh 220 tons, just over 1 percent of the heft of the 14,000-ton Far Detector.

“This is like one tiny corner of the Far Detector,” said Steve Dixon of the Fermilab Engineering Services Section.

The collaboration placed the Near-Detector surface building near the MINOS building to skim neutrinos from the NuMI and Booster beams. The detector will not sit directly in the path of either beam but should see a couple of thousand interactions and also will collect data from cosmic rays, Cooper said.

You can watch a time-lapse video of the construction here. 

Kathryn Grim

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Fermilab physicists honored for uniting physics and cosmology

February 18, 2010 | 5:28 am

This story first appeared in Fermilab Today on February 16, 2010.

Last month, the American Institute of Physics and the American Astronomical Society honored two scientists who, more than any others, made particle astrophysics, if not a household name, a new scientific discipline.

Theoretical astrophysicists Michael Turner and Rocky Kolb won the annual Dannie Heineman Prize for Astrophysics “for their joint fundamental contributions to cosmology and their development of the field of particle astrophysics, which have resulted in a vibrant community effort to understand the early universe.”

Turner and Kolb conducted much of their pioneering work at Fermilab. They were the first members of the NASA/Fermilab Theoretical Astrophysics Group, which blossomed into the realm of experiment and observation and continues today at the Fermilab Center for Particle Astrophysics. In the process, they entertained generations in the Fermilab community with a new genre of cosmic humor, astroparticle shtick.

Former Fermilab Director Leon Lederman and the late David Schramm of the University of Chicago brought the two together in 1983. John Peoples, who followed Lederman as lab director, helped them realize their plan of expanding into particle astrophysics experiments.

Turner said, “While the two of us are getting the prize, really Fermilab and the University of Chicago deserve a lot of credit for all the support they’ve given us and for taking chances.” Not to mention auditioning their act.

For more than 25 years, the two each held joint appointments at Fermilab and the University of Chicago. Now both are professors full-time at the University of Chicago.

Taking the initiative

In the late 1970s, astrophysics had hit a wall. The standard hot big bang model seemed to have a problem. Neutrons and protons, the smallest known particles, were too large and interacted too strongly to allow sensible speculations about how the universe began.

Then particle physicists discovered quarks, the weakly interacting, point-like particles that make up neutrons and protons–and saved the model. Scientists could describe the early universe as a hot, primordial soup of quarks instead of a jumble of overlapping neutrons and protons.

It didn’t take long for Turner and Kolb to package “Condensed Primordial Soup: A quick meal in just 4.5 billion years” in a familiar red and white can.

Now scientists could start to tackle some big questions about how the universe began and how it was shaped. But neither astrophysicists nor particle physicists could answer those questions alone.

Fermilab made a first attempt to enter the world of astrophysics in 1979, making a bid to NASA to host its Space Telescope Science Institute, which analyzes data from the Hubble Space Telescope. NASA chose the bid from Johns Hopkins University instead. Soon after, Lederman went hiking in the Dolomites with Schramm, an astrophysicist and rising star at the University of Chicago.

“I was complaining about NASA’s decision,” Lederman said. “Schramm said, ‘You don’t need to win any contests. You’re the director of Fermilab. Why don’t you just make yourself an astrophysics group? I’ll help you.’”

The laboratory put in a new bid to NASA, this time to host a theoretical astrophysics group. This time, NASA said yes.

In 1983, Lederman hired Turner, a young assistant professor in the Astronomy Department that Schramm chaired at the University of Chicago, along with Kolb, an Oppenheimer Fellow from Los Alamos, to bring Fermilab to the cosmic frontier.

“Leon is a visionary,” Peoples said. “He was always looking around for the thing nobody else had thought about.”

Kolb and Turner were a perfect fit for the task, which was by no means guaranteed to succeed, Lederman said. They were good communicators; they could make people laugh. “That’s a big plus,” he said. “It could lighten any disaster.”

Kolb and Turner had first met in 1980 at a workshop in Santa Barbara.

“We started out working on similar research, but as competitors,” Turner said. “You’ve got a lot of testosterone when you’re a young post-doc trying to make a mark. But we had a lot in common: a passion for this area of science, a similar sense of humor. It was clear to me that we would have a greater impact if we worked together–and it would be more fun.”

Turner had already begun to establish himself at the University of Chicago, but he and Kolb were both in their 30s when they first came to Fermilab to head a group of about 10 post-docs and students. “I felt like I’d been given the keys to the candy store,” Kolb said. “Who would allow kids like us to run something? I always thought somebody would say, ‘Who’s really in charge?’”

The young scientists’ work paid off, Lederman said, and soon they ran the premier particle astrophysics groups in the nation. They built and studied theories of dark matter, extra dimensions, ultra-high-energy cosmic rays, superstring cosmology, the cosmic microwave background, and gravitational lensing.

“We were just a little bit ahead of everybody,” Lederman said. “Four or five years after our group had achieved successes, the other universities started to make those connections.”

Over the years, between teaching post-docs at Fermilab and students at the University of Chicago, Kolb and Turner trained a large fraction of the people who would become the next generation of leaders in the field they began.

In 1989, Kolb and Turner published what would become the handbook for particle astrophysics: a book called “The Early Universe.”

“We were so young, foolish and inexperienced, we thought it would be easy,” Kolb said. “It took about three years of pretty hard work.”

Around that time, they recognized that they needed to get involved in testing the theories that they had spent years developing. “We realized a purely theoretical activity is not as productive as an operation with connections to experiments and observations,” Kolb said. “Even though theorists are smarter and more attractive, we do need experimentalists.”

Peoples, then Fermilab’s new director, supported their plan. Fermilab joined the Sloan Digital Sky Survey, the most ambitious astronomical survey ever planned; the Cryogenic Dark Matter Search experiment; and the Pierre Auger Observatory, which in 2007 identified supermassive black holes as the most likely source of the highest-energy cosmic rays.

“As a director, you have to have a few things you take a chance on,” Peoples said. “If every experiment you do is successful, you’re not doing anything new.”

About 15 years after Turner and Kolb arrived at Fermilab, experimental results began to come in from the NASA’s Cosmic Background Explorer satellite, which found patterns in the way matter and energy had been distributed soon after the universe began. The new data matched predictions based on ideas coming out of early-universe cosmology, including inflation and cold dark matter.

“The world changed on Jan. 1, 1998,” Turner said. “These went from ideas to ideas supported by data. It became clear this wasn’t just a bunch of airy-fairy theory.”

The astrophysics group could not fully enjoy their triumph. Just days before Christmas of 1997, Schramm died in plane crash during a flight from Denver to Aspen in his private plane. He never saw the field that considered him a founder turn the corner toward widespread acceptance.

Kolb, Turner, and the particle astrophysicists at Fermilab and the University of Chicago have continued the work he championed.

The Fermilab Center for Particle Astrophysics participates in the COUPP dark matter experiment, the Dark Energy Survey and GammeV. The group continues to participate in the Cryogenic Dark Matter Search, the Pierre Auger Observatory, and the Sloan Digital Sky Survey. Scientists there hope to join the Joint Dark Energy Mission as well.

Since its inception, the Fermilab Theoretical Astrophysics Group has published more than 1000 papers. The Experimental Astrophysics Group was an anchor for the SDSS and now leads the Dark Energy Survey, designed to study the acceleration of the expansion of the universe.

Turner said he has high hopes for the current search for dark matter. “We have a full-court press on dark matter. One of these methods is going to pan out.”

He does not foresee solving the mystery of dark energy–a term he coined in 1998 to explain the mysterious force pushing the universe to expand at an increasing rate–anytime soon. But “I bet there’ll be a surprise ahead,” he said. “Each generation wants to get all the answers. After a few it gets a little more generous and says, ‘We’d better save some of the big questions for the next generation.’”

Turner and Kolb are recognized as pioneers who not only brought the field new knowledge, but helped frame the questions that drive future research. And left them laughing.

“You’re sure dark matter is there?” Turner once asked Kolb in a public debate on dark matter.

“I would bet your life,” Kolb replied.

Kathryn Grim

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Extreme jets take new shape

February 17, 2010 | 2:26 pm

Jets of particles streaming from black holes in far-away galaxies operate differently than previously thought, according to a study published today in Nature. The new study reveals that most of the jet’s light—gamma rays, the universe’s most energetic form of light—is created much farther from the black hole than expected and suggests a more complex shape for the jet.

The research was led by scientists at the Kavli Institute for Particle Astrophysics and Cosmology, jointly located at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University, with participation from scientists from around the world. The study included data from more than 20 telescopes including the Fermi Gamma-ray Space Telescope and KANATA telescope.

High above the flat Milky Way galaxy, bright galaxies called blazars dominate the gamma-ray sky, discrete spots on the dark backdrop of the universe. As nearby matter falls into the black hole at the center of a blazar, “feeding” the black hole, it sprays some of this energy back out into the universe as a jet of particles.

“As the universe’s biggest accelerators, blazar jets are important to understand,” said KIPAC Research Fellow Masaaki Hayashida, who serves as corresponding author on the paper with KIPAC Astrophysicist Greg Madejski. “But how they are produced and how they are structured is not well understood. We’re still looking to understand the basics.”

Researchers had previously theorized that such jets are held together by strong magnetic field tendrils, while the jet’s light is created by particles revolving around these wisp-thin magnetic field “lines.”

Yet, until now, the details have been relatively poorly understood. The recent study upsets the prevailing understanding of the jet’s structure, revealing new insight into these mysterious yet mighty beasts.

“This work is a significant step toward understanding the physics of these jets,” said KIPAC Director Roger Blandford. “It’s this type of observation that is going to make it possible for us to figure out their anatomy.”

Locating the Gamma Rays

Over a full year of observations, the researchers focused on one particular blazar jet, located in the constellation Virgo, monitoring it in many different wavelengths of light: gamma-ray, X-ray, optical, infrared and radio. Blazars continuously flicker, and researchers expected continual changes in all types of light. Midway through the year, however, researchers observed a spectacular change in the jet’s optical and gamma-ray emission: a 20-day-long flare in gamma rays was accompanied by a dramatic change in the jet’s optical light.

Although most optical light is unpolarized—consisting of light rays with an equal mix of all polarizations or directionality—the extreme bending of energetic particles around a magnetic field line can polarize light. During the 20-day gamma-ray flare, optical light streaming from the jet changed its polarization. This temporal connection between changes in the gamma-ray light and changes in the optical light suggests that both types of light are created in the same geographical region of the jet; during those 20 days, something in the local environment altered to cause both the optical and gamma-ray light to vary.

“We have a fairly good idea of where in the jet optical light is created; now that we know the gamma rays and optical light are created in the same place, we can for the first time determine where the gamma rays come from,” said Hayashida.

This knowledge has far-reaching implications about how energy escapes a black hole. The great majority of energy released in a jet escapes in the form of gamma rays, and researchers previously thought that all of this energy must be released near the black hole, close to where the matter flowing into the black hole gives up its energy in the first place. Yet the new results suggest that—like optical light—the gamma rays are emitted relatively far from the black hole. This, Hayashida and Madejski said, in turn suggests that the magnetic field lines must somehow help the energy travel far from the black hole before it is released in the form of gamma rays.

“What we found was very different from what we were expecting,” said Madejski. “The data suggest that gamma rays are produced not one or two light days from the black hole [as was expected] but closer to one light year. That’s surprising.”

Rethinking Jet Structure

In addition to revealing where in the jet light is produced, the gradual change of the optical light’s polarization also reveals something unexpected about the overall shape of the jet: the jet appears to curve as it travels away from the black hole.

“At one point during a gamma-ray flare, the polarization rotated about 180 degrees as the intensity of the light changed,” said Hayashida. “This suggests that the whole jet curves.”

This new understanding of the inner workings and construction of a blazar jet requires a new working model of the jet’s structure, one in which the jet curves dramatically and the most energetic light originates far from the black hole. This, Madejski said, is where theorists come in. “Our study poses a very important challenge to theorists: how would you construct a jet that could potentially be carrying energy so far from the black hole? And how could we then detect that? Taking the magnetic field lines into account is not simple. Related calculations are difficult to do analytically, and must be solved with extremely complex numerical schemes.”

Theorist Jonathan McKinney, a Stanford University Einstein Fellow and expert on the formation of magnetized jets, agrees that the results pose as many questions as they answer. “There’s been a long-time controversy about these jets—about exactly where the gamma-ray emission is coming from. This work constrains the types of jet models that are possible,” said McKinney, who is unassociated with the recent study. “From a theoretician’s point of view, I’m excited because it means we need to rethink our models.”

As theorists consider how the new observations fit models of how jets work, Hayashida, Madejski and other members of the research team will continue to gather more data. “There’s a clear need to conduct such observations across all types of light to understand this better,” said Madejski. “It takes a massive amount of coordination to accomplish this type of study, which included more than 250 scientists and data from about 20 telescopes. But it’s worth it.”

With this and future multi-wavelength studies, theorists will have new insight with which to craft models of how the universe’s biggest accelerators work.

The gamma-ray observations used in this study were made by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope, an astrophysics and particle physics partnership developed by NASA in collaboration with the U.S. Department of Energy Office of Science, along with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the United States. LAT collaboration members were key participants in the development of this research. SLAC National Accelerator Laboratory managed construction of the LAT and now plays the central role in science operations, data processing and making scientific data available to collaborators for analysis.

The optical polarization data that played a crucial role in this study was taken by the KANATA collaboration, using the KANATA telescope located in Higashihiroshima, Japan. The KANATA telescope is operated by Hiroshima University.

The GASP-WEBT observatories participating in this work are Abastumani, Calar Alto, Campo Imperatore, Crimean, Kitt Peak (MDM), L’Ampolla, Lowell (Perkins-PRISM), Lulin, Roque de los Muchachos (KVA and Liverpool), San Pedro Ma´rtir, St Petersburg for the optical–NIR bands, and Mauna Kea (SMA),Medicina, Metsahovi, Noto and UMRAO for the millimeter radio band.

The campaign also included data from NASA satellites Swift and the ROSSI X-ray Timing Explorer, and the Japanese satellite Suzaku.

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