Tevatron operations: A way of life

September 30, 2011 | 10:38 am

Editor’s note: This afternoon, Sept. 30, Fermilab will shut down the Tevatron for the last time. A broadcast of the event will begin at 2 p.m. CDT and will be available online. Fermilab Director Pier Oddone will host the broadcast, which will feature the shutdown in the Main Control Room, and the CDF and DZero control rooms. Fermilab Today published this story to honor the operators – the men and women who have kept the accelerators running 24 hours a day, seven days a week, 365 days a year.

On July 23, current and former Fermilab operators celebrated 40 years of operations.

A steady, consistent beep is the soundtrack of the Main Control Room in Fermilab’s accelerator complex. The metronomic resonance, not unlike a submarine, is reassuring to those who know it best: The operators. The regular tone signals that all is well with the 10 accelerators maintained, and often improved, by the Accelerator Division at Fermilab. But when the monotonous pitch is interrupted by any one of several alerts, the operators leap into action – even in the middle of the night.

Operators – the men and women who keep the accelerators running – work 24 hours a day, seven days a week, 365 days a year. Four crews rotate through three shifts every weekday, with two 12-hour shifts on Saturday and Sunday. The weekday shifts are split into day, evening and owl. Every shift is different.

At the basic understanding of their job, operators run the accelerators. But it goes further than that. Not only do they send beam to whichever experiment needs it at the moment, they also provide constant care for the accelerators. The accelerators can be brought down by storms, heat, electrical surges and even frogs.

Operators work in unique conditions. They’re often the first to know that there’s a problem with an accelerator, and they’re often the first to propose a solution.

“We’re the first line of defense, the skin,” Duane Newhart, the Deputy Head of Accelerator Operations, said. “We have to logically respond to problems, while dealing with a variety of personalities, often in the middle of the night.”

In the 15 years that Newhart has worked in Operations at Fermilab, he said not a day has been the same. He recalled how one operator handled a particularly difficult mystery.

“Duane Plant once investigated this TeV ramp trip that kept happening, but it’d move forward 3 to 5 minutes every week,” Newhart said.

Plant found that a service van would drive by around that time. The sun reflected off of the van’s windows, bounced to the service building, hit the photocell on the dump switch, and then the switch would open, causing the ramp to trip off.

“Not only is it amazing to see how people solve these problems, but it’s also incredible to see all of these different people working together,” said Michael Backfish, Operator II. “I’ve seen people on all sides work together for science.”

The pressure can be intense, but the operators know how to alleviate their stress with a little good-natured fun.

“We played a few practical jokes back in the day,” Paul Czarapata, the Deputy Division Head and former Meson Crew Chief, said. “There was a tech who was crazy about keeping his tools secure and had a desk with an elaborate locking mechanism.”

One day, several operators jimmied the lock, removed the tools and put on innocent faces.

“The guy was flustered,” Czarapata said. “He thought it was funny, too, once we pointed out his tools sitting safely in the corner.”

They have fun playing pranks on each other, but the operators can become very serious, very quickly.

“We have fun, but it just takes one alarm to make everyone focus,” Newhart said. “We go from laughing to serious in a second.”

Despite the strange hours and unpredictable work day, or in some cases it’s because of these things, there’s an excitement in operations.

“You get to watch what happen,” said Bob Mau, the former Operations Department head. He’s now retired. “You get to go everywhere and see a little bit of everything.”

All of that on-the-job training gives operators exposure to the rest of the laboratory and the variety of jobs therein. Mau said that a former operator can be found in nearly every division and section.

“Most operators are hired right out of school. They’re trying to figure out what they want to do,” Mau said. “In operations, they learn the complex. It’s a great spring board for people to find what they’re really interested in.”

Regardless of where they end up, operations becomes a part of who they are.

On July 23, hundreds of Fermilab operators gathered to celebrate the 40th anniversary of Operations. Current employees, retirees and their spouses and children shared stories over a potluck picnic and barbeque. “There are people here that I haven’t seen in 15 or 20 years,” Mau said. “It’s nice to see that these people thought enough of their early jobs to travel all this way.”

“In operations, you become a bit of a family,” Jim Morgan, an engineering physicist, said. “Everyone is always in each other’s face, and we take all of the good and all of the bad. We’re close.”

There are often differences that need to be navigated, but operators are tied together in pursuit of the common goal to make the accelerators work.

“Operations is our opportunity to contribute to something bigger,” Dave Capista, an engineering physicist with the Main Injector Department, said. “It’s our chance to contribute to science.”

Ashley WennersHerron

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Fermilab’s Antiproton Source: A rich history and an exciting future

September 29, 2011 | 1:04 pm

Fermilab Today first published this story on Sept. 29, 2011.

A mock-up of the proposed upgrades to the Antiproton Source and the new Mu2e building.

Fermilab’s Antiproton Source has long produced the antimatter that makes Fermilab’s particle collisions possible. While the Antiproton Source will shut down along with the Tevatron on Sept. 30, there are plans for its future.

The facility that houses the Antiproton Source will be reconfigured for two proposed experiments: Muon g-2 and Mu2e. Instead of creating antiprotons, both experiments will use the reconfigured facility to generate intense muon beams. While each would produce exciting and interesting data, they are both very different from the Antiproton Source’s original mission.

Fermilab’s Antiproton Source came out of an upgraded design of a similar machine that was housed at CERN.

Fermilab’s first antiprotons were produced in the Tevatron’s first collider run in 1988. At that time, it took more than an hour to make 10¹⁰ antiprotons. Now, the Antiproton Source can make 30×10¹⁰antiprotons an hour.

“The antiproton production rate in those early days now seems like an incredibly slow pace,” said Steve Werkema, deputy head of the Antiproton Source. “I think we would’ve been amazed by the production number now.”

The Antiproton Source was upgraded in the mid-1990s, before collider Run II. Improved accelerator optics and upgraded stochastic cooling systems aided in the jump of antiproton production. The rate of antiprotons produced jumped significantly during this time, due to the combined efforts of improved accelerator complex components.

“We really have to recognizethe efforts by the operators,” Werkema said. “There are long periods of routine running, and the operators are not happy to merely sit and watch the beam. They get to work tuning the machine. I think a good part of the improvements are due to the amazing things they’ve done.”

More than tuning is necessary to convert the Antiproton Source facility into an area appropriately equipped to house the Muon g-2 and Mu2e experiments. Fermilab’s muon program is a strong component of the laboratory’s new direction. The laboratory will use muon beams to study fundamental laws of physics. Both of these experiments are possible, in large part, because of the cost savings that comes from reusing the Antiproton Source infrastructure.

These muon experiments will be at the cutting-edge of high-energy physics for Fermilab’s push into the Intensity Frontier in the coming decade. Both experiments are currently in their design stage, with scientists and engineers finalizing conceptual designs. Muon g-2, the smaller of the two experiments, is aiming to start construction in 2013 and begin taking data in early 2016. Mu2e expects to finalize their conceptual design this year and is working toward a construction period that would allow for data production toward the end of the decade.

“There’s a lot of work to do moving forward,” Werkema said. “We’re sad to see the Antiproton Source go, but we’re going to be busy.”

Muon g-2 is the newest generation of a similar experiment performed at Brookhaven National Laboratory in 2001, which found a disagreement in the data value and the Standard Model prediction of the gyromagnetic ratio “g” of the muon.

“We’re doing the same type of experiment, but with higher precision,” said Chris Polly, project manager for Muon g-2. “The Antiproton Source infrastructure plays a key role in getting to that higher precision. By building a 1,000 meter long beam line at Fermilab, the muon beam will have a much higher quality than what could be achieved with the 80 meter beamline used at Brookhaven.”

The Antiproton Source was not designed to employ the high beam intensities needed for these experiments. However, the scientists see a lot of potential in the current facility.

“The Antiproton Source rings makes Fermilab the ideal place to do the Mu2e experiment,” said Bob Bernstein, the Mu2e co-spokesperson. “Their length happens to be just right for our physics needs.”

The Mu2e experiment will increase the intensity of muons stopping in their target by four orders of magnitude over any prior experiment. The discovery potential and the techniques developed for Mu2e will pave the way for future possibilities with Project X, a proposed high-intensity proton accelerator that would generate high-intensity beams for various experiments.

“Working with regular matter seems like it would be boring after making antiprotons, but, thankfully, it’s not,” Werkema said. “Both of these experiments come with unique and serious challenges. We won’t be bored.”

Ashley WennersHerron

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Tevatron shutdown eve

September 29, 2011 | 11:00 am

On the eve of the shutdown of Fermilab’s Tevatron, collaborators from the CDF and DZero experiments are expressing their gratitude for all the hard work and dedication that made 26 years of capturing billions of proton and antiproton collisions possible. In these final hours of operations, both collaborations are making the pen mightier than the proton by writing notes of thanks and appreciation. A live broadcast of the shutdown activities that will take place in the CDF and DZero control rooms and the Main Control Room will begin tomorrow, Sept. 30, at 2 p.m.

Thank you from CDF

On October 13, 1985 at Fermilab, the Tevatron produced protons and antiprotons collisions inside the CDF detector for the very first time. It was a magical day for the few dozen people in the accelerator and CDF control rooms. Since that day, literally billions of matter-antimatter collisions took place inside CDF and then inside CDF and DZero. What was once novel is now routine – and routine at an unprecedented scale. The intensity of the beams gradually multiplied, thanks to the relentless efforts of the Tevatron accelerator physicists.

Friday at 2 p.m., after nearly 26 years of operation, a switch will be turned, ending the career of one of the most remarkably successful colliders ever in particle physics. The Tevatron collider established a brand identity for Fermilab and changed the physics landscape forever.

This program allowed CDF to achieve numerous physics highlights, including the discovery of the top quark, the precision measurement of the W boson mass, the observation of B_s mixing and the many limits set on potential new physics theories. Many of these results appeared in this column.

More than 3,000 physicists contributed to this rich program at one point in their career. Five hundred and thirty two students have received their Ph.D. in this program thus far, and the experiment produced a steady flow of more than 550 publications (and counting) in refereed journals. Now with a full dataset of 10 inverse femtobarns under the hood, CDF scientists expect to produce another hundred or so papers in the coming years.

The success of a program like this goes well beyond just those scientists involved. Twenty six years of fruitful operation requires a commitment from everyone here at the laboratory. From the accelerator scientists, to the technical staffs, the people in the business systems and those that maintain the laboratory infrastructure – each of you played a role in this success story. What a run it’s been – we should all be very proud of what we, as a team, accomplished. On behalf of all the members of CDF: Thank you, Fermilab. We did it together, and we did it very well!

—Rob Roser and Giovanni Punzi,
CDF co-spokespersons

Thank you from DZero

As the DZero collaboration prepares to join in tomorrow’s festivities and celebrate the Tevatron, we would like to take the opportunity to recognize those who have helped make the DZero experiment a success over the years.

To the Accelerator Division goes our gratitude for providing proton-antiproton collisions with remarkable reliability at beam intensities far beyond the design goals of the Tevatron. Their effort to optimize the delivered integrated luminosity to the experiments assured continuing success of our physics program.

The Particle Physics Division hosts the experiment construction and operations and a large fraction of the experiment’s physicists. The division assured reliable, safe and productive operation of the experiment.

We rely on the efforts of the Computing Division to perform the intense processing that transforms our raw data into the reconstructed physics objects that we use for analysis. Computing Division stores and provides access to our large data set and administrates the large farm of computers we rely on for our physics analyses.

Thanks to all laboratory personnel for providing services critical to the life of this large, international collaboration which culminated in many discoveries and exciting measurements at the Energy Frontier collider.

Much of our support comes from outside the laboratory, and we would like to acknowledge all of the universities and laboratories that are involved in the DZero experiment. Also critical to our success is the continuing support of many national and international funding agencies, especially that of the Department of Energy and the National Science Foundation.

Finally, we would like to give a very special thanks to our families and to the families of those thanked above. Though as a collaboration we keep careful track of every collision that occurs and each event that is stored, we tend to lose track of the number late nights, long weekends and 3 a.m. expert phone calls that add an intangible cost to our efforts to succeed!

The DZero collaboration is looking forward to producing many excellent physics results as we examine our complete data set from Run II of the Tevatron!

—The DZero Collaboration

Elizabeth Clements

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LHC control centers open to teens for a night

September 28, 2011 | 3:10 pm

ALICE physicist Ombretta Pinazza, right, explains the inner workings of the ALICE control center. Image: CERN

Making detector adjustments, analyzing data, calculating the subatomic world’s exotic properties — these are some of the things a physicist at the Large Hadron Collider is used to dealing with. Sharing the control room with a group of teenage students? Not so much.

On Friday Sept. 23, students arrived at control rooms for the LHC and its detectors throughout the evening in groups of five to 10. For the second time, members of the four largest experiments at the LHC at CERN were participating in Researchers’ Night, a Europe-wide event in which members of the public from more than 320 cities spend an evening alongside scientists in action.

At the ALICE control room, students were given a tour of the experiment and taken through the visitor center before going to the control room to meet and talk to shift workers on the job. “It’s difficult to explain to the kids what we do, but it’s a good exercise,” French Ph.D. student Nicolas Arbor said. “I’m surprised because the young people ask very precise questions – for example about the link between matter and energy – for being 13 or 14.”

Arbor had driven in for the evening from his home in Grenoble to help guide the French-speaking groups. “It’s good to have a young person who speaks their language,” said ALICE’s Despina Hatzifotiadou, herself a mother of two teenagers.

One group got lucky enough to actually send a request from ALICE to the LHC, said physicist Ombretta Pinazza. “They were on the right console at the right time,” she said. “They are much quicker than we are.” With the click of a button, the students for a moment truly became part of the experiment.

Pinazza, who hails from Italy, spent the later part of the evening showing an enthusiastic group from Milan around the control room. Slightly older than most of the students that night, they met up with Hatzifotiadou in the room next door afterwards for a more technical discussion of the physics.

While most of the Researchers’ Night participants came from the surrounding Swiss and French countryside, others came from as far away as Poland and Germany. So too do many of the experiment’s shift workers. ALICE researcher Ralf Averbeck spends most his time in Germany but travels to CERN two or three weeks of the year for his turn at the controls. He had just finished a few weeks of outreach for a travelling LHC exhibit in his hometown. Although he finds this work a bit time-consuming on top of his research, he still thinks it’s a fun and important part of his job. After all, he said, “In the end, [the public] pays for it.”

For some students, visiting ALICE was their first real introduction to particle physics. In school, he has yet to explore energy levels smaller than the atom, said Douglas McAllister, 14, from the Swiss town of Coppet.

Just because the students had not delved far into particle physics textbooks did not mean they asked only easy questions. McAllister asked Averbeck about whether the LHC would create black holes. Other researchers answered questions about the implications of the latest neutrino results. “It’s nice for the kids, but also for us, Pinazza said. “We see what they’re interested in.”

In addition to picking researcher’s brains about physics, some students wanted advice about careers and education. “I was especially satisfied because there were so many girls, and they saw that here there are many women,” Pinazza said. “Physics is not just a job for men.”

By midnight, the last teenagers were on their way back to CERN reception. Arbor got ready to drive the two hours home. He, for one, said he’d do it again.

Amy Dusto

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OPERA experiment sees neutrinos seem to beat speed of light

September 23, 2011 | 7:02 am

The OPERA experiment began in 2006 with the main goal of studying neutrino oscillation. Image courtesy of OPERA

The OPERA neutrino experiment announced today the kind of result that keeps a physicist up at night.

Scientists revealed that they have observed subatomic particles seeming to travel faster than the speed of light.

Leaders of the collaboration will share OPERA data with the world today at 9 a.m. CDT during a seminar to be broadcast live on the web. They have already posted the relevant paper online.

The OPERA experiment’s study of more than 15,000 neutrino events over the course of three years indicated that the particles reached a velocity 20 parts per million above light speed.

If neutrinos really are breaking the cosmic speed limit, a revolution is at hand in the field of particle physics. Einstein’s law of special relativity as we understand it and a century of experiment tell scientists such a result is impossible.

So, to them, the next step is clear: They will try their best to prove it wrong.

“This result comes as a complete surprise,” said OPERA spokesperson Antonio Ereditato of the University of Bern. “After many months of studies and cross checks we have not found any instrumental effect that could explain the result of the measurement. While OPERA researchers will continue their studies, we are also looking forward to independent measurements to fully assess the nature of this observation.”

Neutrinos are some of the most mysterious particles studied today. They rarely interact with other matter, so they have the ability to slip quietly through space and entire planets as if they weren’t there. The only way scientists can detect enough of these subatomic ghosts to study their properties is to aim an intense beam of them at a large target.

OPERA is a long-baseline neutrino experiment, meaning that its detector sits far from its neutrino source. For the OPERA experiment, particles stream from their origins at CERN to Gran Sasso, Italy, more than 450 miles away. Long-baseline experiments allow scientists to study a strange trait of the particles. Neutrinos come in three types, called flavors. As they travel, neutrinos oscillate from one flavor to another.

These experiments can also take precision measurements such as the one announced today. Two other long-baseline neutrino experiments, one in the United States and the other in Japan, could double-check OPERA’s results. The MINOS experiment sends a beam of neutrinos from Fermi National Accelerator Laboratory into a 6,000-ton detector in a former iron mine about 450 miles away in northern Minnesota. The T2K experiment studies neutrinos that travel more than 180 miles through Japan from Tokai to Kamioka.

Previous results from the MINOS experiment do not contradict OPERA’s findings, but they are less certain. Scientists on the MINOS collaboration plan to improve the accuracy of their measurement with upgrades already underway.

Members of MINOS and T2K, along with scientists from around the world, will scrutinize the OPERA measurement, looking for fatal flaws. Still other scientists will prepare for another possibility: What if the result is right? “In the upcoming weeks, we’ll see a flurry of papers come out with different interpretations of this,” said CERN theoretical physicist John Ellis.

Not all theorists will jump in. Many will wait for confirmation by other experiments before taking on the problem of how to square superluminal neutrinos with the rest of physics.

But those that offer their interpretations will guide experimentalists by giving them new parameters to test, Ellis said. “It’s good to produce a bunch of reactions and see which way nature decides to go.”

Read updates:
Scientists still seek explanation for faster-than-light neutrino result
Faster-than-light neutrino result withstands new test

Kathryn Grim

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Developers create virtual CERN

September 19, 2011 | 9:45 am

Neng Xu sits in the cafeteria, where he was inspired to create a virtual CERN. Photo credit: Amy Dusto

Neng Xu, a software engineer for the University of Wisconsin-Madison working on the ATLAS experiment, sat drinking coffee in a sunny corner of CERN’s cafeteria when he thought of a challenge. Could he create a virtual version of what he saw out the window: a lawn with cafe tables and a building across the street?

He could, he found, and more. With the help of a colleague, Xu is now growing his virtual CERN into an interactive app that will work across multiple platforms and is slated for a public beta version sometime this fall. Fans of digital art got a preview of the tool at this month’s Ars Electronica festival.

For years Xu has been a video game enthusiast. He’d toyed with the idea of making his own but ultimately decided, “Whatever I do, I can’t make better games than game companies.” Then he realized he could use the same type of software to do something different.

Xu used a free online game development tool called Unity to begin construction of the virtual cafeteria lawn and the building across the street, where in reality many physicists working on the ATLAS and CMS detectors have offices. Completing the project took two months of after-hours work. He’d included so much detail that the final file was huge, about 200 megabytes, and took nearly an hour to open.

When he moved on to his next idea, making a virtual model of the ATLAS detector, Xu cut down on the amount of information he included. That project took only half of a month to complete. After finishing it, Xu planted the virtual detector on the virtual lawn in front of the cafeteria to give a sense of the experiment’s enormity.

The ATLAS detector, parked in an usual spot. Image courtesy of Neng Xu

The resources coordinator for ATLAS saw the model. He asked Xu to make something similar that people outside of CERN could access online. Xu agreed. Although he was still working on this project beyond his day job, ATLAS began to provide him with some support. Besides software supplies, perhaps the most valuable asset Xu received was his introduction to fellow modeling innovator Joao Pequenao.

For the last decade, Pequenao has been working on multimedia, images and simulations for the ATLAS outreach office. While an undergraduate physics student in Lisbon, Portugal, he passionately pursued a hobby in graphic design. As the autodidact said, “Some kids play soccer, some kids go home to study [graphics] tools.”

Over the years, Pequenao’s work has gained worldwide attention. The logo for this year’s Ars Electronica festival was his 2006 visualization of a proton collision forming a microscopic black hole.

“There was a niche in the market,” he said. ”I’m at the intersection of physicist, computer scientist and designer.”

Xu and Pequenao realized they could help one another. Along with Pequanao’s student, Henrique Carvalho, they teamed up to become the first ATLAS group working on interactive multimedia.

Their new project, the ATLAS Virtual Interactive Online Navigator, or AVION, is a Web-based application that will soon be accessible to anyone with a laptop, smartphone, game console or other device connected to the Internet. Still in the alpha phase, AVION allows explorers to take guided tours of the experiment that start in the parking lot and delve underground into the LHC where collisions are occurring, or to examine individual pieces of the detector. Keeping up with Hollywood, the whole thing takes on an extra dimension with a pair of 3D glasses.

AVION takes the tour of CERN underground. Image courtesy of Neng Xu

AVION is designed to operate in a Web browser from any part of the world. Xu and Pequenao have visions of interactive games in the future in which players can build ATLAS and do their own physics analysis. And since the Unity engine is free online, the source files will be available to anyone who wants to download them, allowing users to modify AVION and create their own virtual CERN world.

“Add dinosaurs if you want,” said Xu.

Both he and Pequenao see AVION as a potentially valuable education tool for students and the public. “If you really have to build ATLAS, you will learn a lot,” Xu said.

The team expects AVION will be revealed to the world in the coming months via the ATLAS website.

Amy Dusto

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Keeping the Tevatron’s cool: A look back at electron cooling

September 13, 2011 | 2:58 pm

Fermilab Today published  this article on September 13, 2011.

When electron cooling was implemented at Fermilab in 2005, scientists thought it could help increase the peak luminosity by a factor of 1.5 to 2.

Some members from the electron cooling team at the Wideband test facility during the final stage of research and development.

Now, less than a decade later, it has become integral to the Tevatron’s success, leading to an increase of instantaneous initial luminosity by nearly a factor of 3.

“The successful implementation of electron cooling has had a larger effect on the initial luminosity for the Tevatron than any other single improvement,” said Accelerator Division head Roger Dixon.

Electron cooling condensed the beam to make it easier to manipulate and accelerate, but it also encouraged adjustments to the entire accelerator complex, which was optimized to work well with the new system. It provided additional cooling beyond that carried out in the Accumulator, the accelerator that collects antiprotons, to the Recycler. This enabled the Accumulator to collect antiprotons at higher rates, which translated to more collisions.

“I would say that without electron cooling, the Tevatron wouldn’t be running now,” said Fermilab electron cooling pioneer and scientist Sergei Nagaitsev. “We wouldn’t have enough luminosity to sustain Run II.”

Getting to cool

Russian-born scientists Sergei Nagaitsev and Sasha Shemyakin worked on electron cooling as graduate students at the Institute of Nuclear Physics in Novosibirsk, Russia, where electron cooling was pioneered. Nagaitsev came to the laboratory in 1995 specifically to develop the Recycler electron cooling system. He knew the technology could work, just not exactly how to make it work at the high energies necessary for the Tevatron.

“Many people didn’t think that this scheme of high-energy electron cooling was possible,” Nagaitsev said.

While it seemed like a long shot to some, Nagaitsev spent 10 years leading a small team in designing, testing and then implementing the system. Part of that effort included developing a new beamline, cooling and solenoid technologies. They created a full-scale prototype at Fermilab’s Wideband lab and then, once they had operated a stable beam for 24 hours in 2004, moved it and reassembled it in its current home as part of the accelerator complex.

During the electron cooler commissioning, the team members worked shifts almost around the clock to get the system up and stable.

In the summer of 2005, the team had finally achieved a stable electron beam, and it produced nearly immediate results. On July 9, 2005, when experts were studying in parallel the cooler and a new procedure in the Recycler, they began to see a sharp peak in the antiproton momentum distribution – a clear indication of interaction between beams.

“Knowing that the system was working was one of the top moments in my life,” said Shemyakin, who was on shift that day.

Nagaitsev attributes the system’s success to determination and hard work, but also to intuition and a lot of trial and error.

“The executive decisions we made, even without a lot of information, turned out to be key to the entire project,” Nagaitsev said. “We didn’t know how important these decisions would be.”

For example, he explained, they decided to add a flange to the Pelletron, the 5 million volt electrostatic accelerator that prepares and dispenses electrons, hence dividing the pressure vessel in two halves. The standard version comes as a single cylindrical tank. That allowed them to lengthen it later, which was integral to making the process work.

Present run

Once the machine was commissioned, the team worked to improve and keep it at peak performance. However, similar to other machines at Fermilab that are custom-made and involve thousands of parts, electron cooling’s success is occasionally interrupted. When the electron cooling system is down, it affects the entire complex.

“We always welcome it back after the electron cooling crew finishes some critical repairs or maintenance,” said Paul Czarapata, deputy head of the Accelerator Division.

When something does go wrong, it falls to a dedicated group of individuals who work around the clock on getting the system back up. The group includes two scientists working full time on the system, Shemyakin and Lionel Prost, who have helped keep it running for the past 7 years. They love the challenge.

“In our business, if you feel that you are clever and can predict how something will behave, then you come to the control room and see that you’re wrong,” Shemyakin said. “The hardware really tests your abilities.”

Currently, thanks in part to the electron cooling system, the Tevatron is running better than ever, a situation that makes the shutdown of the Tevatron and the cooling system on Sept. 30 hard for many.

“I’ve worked with beams all of my life,” Shemyakin said. “It is interesting, and there are always new questions and new techniques to explore.”

Although Prost is looking forward to new projects, he is dedicated to making the electron cooling system run well until the very end. There are currently no plans for the system to be incorporated into other experiments, but Nagaitsev explained, there are always future possibilities.

When the system shuts down, Shemyakin and Prost will transition to working on the proposed Project X. The transition, they said, will be bitter sweet.

Rhianna Wisniewski

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Particle accelerators used to compile nutritional database in Sudan

September 12, 2011 | 4:41 pm

Forty-one percent of the children in Sudan are malnourished and underweight, according to the Food and Agriculture Organization of the United Nations. Mohamed Eisa, a physicist at the Sudan University of Science & Technology, would like to change this statistic, and he believes that particle accelerators can help.

Maps of sulphur and calcium in a hair cross-section for a typical Sudanese (left) and South African (right). Sulphur appears to be distributed similarly.

By using the powerful beams of a proton accelerator, Eisa is analyzing the elemental composition of hard human tissues, such as kidney stones, hair and teeth from all regions in Sudan. His plan is to investigate and determine the levels of calcium, phosphate, iron and other elements in the samples and use the information to create a database that records nutritional deficiencies in the country.

“Sudan is a country of civil war for a long time, and this results in many problems, such as poverty and lack of main services like clean water and medical care,” Eisa says. “This is reflected on the lives of citizens in those affected areas, and I would like to have more focus on these problems to help the development and stability of those affected areas.”

Eisa started using accelerators to analyze samples about ten years ago when he was a graduate student at the iThemba Laboratory for Accelerator-Based Science and Cape Town University in South Africa. He uses a specialized technique called a nuclear microprobe.

In the accelerator, each sample gets exposed to a low-energy proton beam. The protons cause the sample to emit X-rays with wavelengths specific to a particular element. Eisa collects the information to analyze the composition of each sample and note deficiencies, such as iron.

“There is a deficiency in iron in most of the Sudanese regions due to diet, as stated by the Food and Agriculture Organization,” he says. “Fifty percent of all the children are anemic particularly at the war regions and rural areas.”

By pinpointing the specific regions of the country where children are lacking iron, for example, Eisa hopes the database will give officials the information necessary to provide nutrients to the areas that need them most.

“The results show a marked difference between the regions due to differences in food availability, climate as well as regional food habits in Sudan,” he says.

Eisa hopes to complete the study in 2012.

The following organizations have supported his work: iThemba LABS and the iThemba Collaboration in South Africa, Sudan University of Science and Technology, and the Third World Academy of Science – United Nations Educational, Scientific Cultural Organization (TWAS-UNESCO).

Elizabeth Clements

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EXO releases first results

September 9, 2011 | 10:54 am

SLAC published this article on Sept. 8, 2011.

Cooks think of watched pots. Handymen grumble about drying paint. Kids dread the endless night before Christmas morning.

SLAC engineer Knut Skarpaas with half of the EXO 200 detector.

Turns out physicists have their own expression to convey the concept of “slow,” and now, thanks to the Enriched Xenon Observatory (EXO), they know how slow “slow” really is: The flurry of activity during the 13.75 billion years from the Big Bang to us was positively hasty in comparison.

The expression is “2nubb” and it stands for “two-neutrino double-beta decay”, a rare type of particle decay undergone by certain forms of radioactive elements. In this type of decay, two neutrons, the neutral subatomic particles in the nucleus of an atom, spontaneously decay into two protons, two electrons, and two antineutrinos, which are the antimatter twins of the tiny, nearly massless mystery particles called neutrinos. The EXO team announced yesterday at a conference in Munich that, according to their measurements of two-neutrino double-beta decay in Xe-136, an isotope of xenon, the half-life of the process clocks in at 2.11 x 10²¹ years. In other words, it would take 100 billion times longer than the universe has even existed for half of a sample of this radioactive isotope to decay via the 2nubb decay pathway.

“This represents the slowest Standard Model process ever measured,” said Giorgio Gratta, Stanford University physicist and member of the joint SLAC-Stanford Kavli Institute for Particle Astrophysics and Cosmology, who leads the team. The Standard Model is the best description scientists have for the way all the building blocks of matter, like the aforementioned neutrons, protons and electrons, fit together, and why two-neutrino double-beta decay happens in the first place.

Two-neutrino double-beta decay fits neatly within the Standard Model, “so in this sense the observation was not unexpected,” Gratta said. In fact, this form of decay has been seen before in other elements. “In that sense, it is not even new.”

Even so, the team’s results mean much more than a shot at the Guinness Book of World Records.

The EXO 200 detector is the first to capture the 2nubb decay process in Xe-136, for example, and the measurement is based on little more than a month of data – “remarkably clean” data, with very little interference from background noise, Gratta explained. This solid signal has provided valuable data to theorists, enabling them to resolve puzzling discrepancies between their calculations and the results of previous experiments.

But the experiment is far from over, and the speed and clarity of these early results bode well for the team as they go after their real quarry.

What the EXO 200 team wants to find is another decay process – one that is not only even more fantastically rare than 2nubb, but that no one is certain even exists. It’s called zero-neutrino double-beta decay, or 0nubb, and it is decidedly not a Standard Model process.

In 0nubb, two neutrons once again decay into two protons and two electrons, but the antineutrinos are nowhere to be found. They must have been there; the IRS has nothing on Nature for keeping the books balanced. The two antineutrinos must have annihilated each other, like positrons and electrons can annihilate each other, or protons and anti-protons, or any particle and its antiparticle.

This means in order for 0nubb decay to happen, neutrinos must be their own antiparticles.

Odd as this sounds, the possibility of a particle that could be both itself and its anti-self was hypothesized by an Italian theoretical particle physicist named Ettore Majorana in 1937. Such particles are called Majorana particles, and if they exist physicists would need to get busy revising the Standard Model.

“This is a decay that people have been trying to find for a long time,” Gratta said.

“Zero-neutrino double-beta decay would be a big deal,” agreed Marty Breidenbach, SLAC physicist and EXO team member. He explained how the EXO 200 experiment intends to pursue such a prize. It all comes down to distinguishing between something that’s nearly impossible to see because of its rarity and something that’s clearly impossible to see because it may not even exist.

The team’s chief strategy is to give the 0nubb decays as many opportunities to happen and as few places to hide as possible. A detector chamber filled with 200 kilograms of liquid xenon takes care of the first strategic objective – the xenon has been enriched until it’s 80 percent Xe-136, the double-beta decaying isotope – but the second one is a bit tougher.

In order to make sure they’ll recognize 0nubb – or even 2nubb – decays, the team has had to cut out every other source of radioactivity they could. The equipment, made of ultrapure, ultraclean, non-radioactive materials, was constructed at Stanford University and trucked, not flown – flying would expose it to more cosmic rays – to the Chihuahuan Desert near Carlsbad, New Mexico, where it was installed about a half-mile underground in the salt bed used by the Waste Isolation Pilot Plant, the Department of Energy’s repository for nuclear waste. The choice seems odd, but the reasoning was sound. The same salt that keeps radioactivity from nuclear waste trapped in the repository keeps radioactivity from cosmic rays and decaying rocks out of the EXO 200 detector.

As the low background readings in their initial results show, the EXO 200 strategy seems to be working. According to Breidenbach, the experiment will continue to take data for several years, possibly as many as five, depending on progress with what’s called “full EXO,” an experiment using several tons of Xe-136 that’s currently in development.

“EXO 200 was always intended as a pilot project,” Breidenbach said. “We’re actively doing R&D for full EXO.”

In the meantime, there’s no moss gathering on the EXO collaboration. EXO 200 has already made its mark.

- Lori Ann White

The EXO collaboration comprises researchers from the following institutions: Department of Physics and Astronomy, University of Alabama, Tuscaloosa AL, USA; LHEP, Albert Einstein Center, University of Bern, Bern, Switzerland; Kellogg Lab, Caltech, Pasadena CA, USA; Physics Department, Carleton University, Ottawa ON, Canada; Physics Department, Colorado State University, Fort Collins CO, USA; Physics Department and CEEM, Indiana University, Bloomington IN, USA; Institute for Theoretical and Experimental Physics, Moscow, Russia; Physics Department, Laurentian University, Sudbury ON, Canada; Physics Department, University of Maryland, College Park MD, USA; Physics Department, University of Massachusetts, Amherst MA, USA; Department of Physics, University of Seoul, Seoul, Korea; SLAC National Accelerator Laboratory, Stanford CA, USA; Physics Department, Stanford University, Stanford CA, USA; Technical University Munich, Munich, Germany; Waste Isolation Pilot Plant, Carlsbad NM, USA.

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CERN, Ars Electronica introduce artist-in-residency program

September 8, 2011 | 2:22 pm

Ars Electronica Center. Image: Nicolas Ferrando, Lois Lammerhuber

Scientists from dozens of countries and cultures mingle at CERN, home to the Large Hadron Collider. Last weekend, the laboratory announced plans to introduce a new element into the mix: artists.

CERN and international cyberarts organization Ars Electronica will partner for the next three years to offer one part of CERN’s new multidisciplinary artist-in-residency program, Collide@CERN. They announced Collide@CERN at the ceremony for the Prix Ars Electronica, the Oscars of the digital media arts world, held this year in Brucknerhaus Concert Hall in Linz, Austria.

The digital artist who wins the Prix Ars Electronica Collide@CERN prize will spend two months at CERN developing a project and one month working with the Ars Electronica Futurelab team to realize it. A committee of judges will choose one artist per year for three years.

Each artist will pair with a scientist at CERN. The two will meet every week and will document their experiences in a blog hosted on the Ars Electronica website. Ars Electronica will provide the prize money, while two private individual donors will fund the grant for the residency including travel and subsistence. UNIQA Assurances SA Switzerland will provide insurance.

The program is the brainchild of Ariane Koek, winner of a Clore Fellowship for cultural leadership. Koek, a former BBC producer, was serving as director of The Arvon Foundation for Creative Writing, which runs 140 residencies a year in the UK, when the award from the Clore Leadership Program gave her the chance to develop a new project. She was offered positions in New York, London and Canada, but she turned them down in favor of forging a new path.

Koek said she found inspiration during the course of a bike ride to the British library. She was thinking about what made her stand out from others in the arts. “I said to myself, ‘What makes you weird?’” she said. “I’ve got a really nerdy interest in science.”

She knew CERN was performing cutting-edge research in particle physics. Where better to create a partnership with those doing cutting-edge work in the arts?

“I can’t think of anywhere more exciting on earth to come,” Koek said.

Members of CERN management supported Koek, voting unanimously in favor of her idea to create a new cultural policy at the laboratory. “Science underpins much of modern society and has an influence on the everyday lives of all of us,” said CERN Director General Rolf Heuer. “As such, it’s important for scientific organizations like CERN to engage with society on many levels, and for us, Collide@CERN is an important element of that engagement.”

To truly embed the arts program at CERN, Koek organized a board made up of renowned cultural leaders from across the CERN host states: Beatrix Ruf, director of the Kuntsthalle Zurich contemporary art exhibition center; Serge Dorny, director general of the Lyon Opera House; Franck Madlener, director of the IRCAM music institute in Paris. CERN scientist Michael Doser will represent the laboratory, and Christoph Bollman of art fair ArtbyGeneve will represent nearby Geneva. The board members will serve free of charge for three years.

For his part, Doser hopes to translate his experience evaluating scientific proposals to evaluating artistic ones. “Both endeavors [art and science] require a mix of creativity and hard-headedness,” he wrote in an email. “Gently encourage vague thoughts as they first start forming, and then, when they’ve had a chance to gel, subject them to the harsh light of intellect.”

The digital arts section of the Collide@CERN program will accept applications between Sept. 15 and Oct. 31 on the Ars Electronic website. Applicants are asked to submit a personal video testimony, to pitch an idea for a new project, and to turn in a production plan and a portfolio of work. A five-person jury including two representatives from both CERN and Ars Technica and one outside judge will choose the winner in November. That same month the next section of the Collide@CERN program will be announced — this one in dance and performance.

Kathryn Grim

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