## Posts Tagged ‘Fermilab’

### How to make a neutrino beam

Friday, December 12th, 2014

This article appeared in Fermilab Today on Dec. 11, 2014.

Ingredients for a neutrino beam: speedy protons, target, magnetic horn, decay pipe, absorbers. Image adapted from Fermilab

Fermilab is in the middle of expanding its neutrino program and is developing new detectors to study these ghostly particles. With its exquisite particle accelerator complex, Fermilab is capable of creating very intense beams of neutrinos.

Our neutrino recipe starts with a tank of hydrogen. The hydrogen atoms are fed an extra electron to make them negatively charged, allowing them to be accelerated. Once the charged atoms are accelerated, all of the electrons are ripped off, leaving a beam of positive protons. The protons are extracted into either the Booster Neutrino Beamline (BNB) or are further accelerated and extracted into the Neutrino Main Injector beamline (NuMI). Fermilab is the only laboratory with two neutrino beams. Our two beams have different energies, which allows us to study different properties of the neutrinos.

In the BNB, these protons smash into a target to break up the strong bonds of the quarks inside the proton. These collisions are so violent that they produce new quarks from their excess energy. These quarks immediately form together again into lighter composite short-lived particles called pions and kaons.

Since the pions and kaons emerge at different directions and speeds, they need to be herded together. As a bugle tunes your breath into musical notes, a horn of a different type rounds up and focuses the pions and kaons. The BNB horn looks roughly like the bell of a six-foot long bugle. It produces an electric field that in turn generates a funnel-like magnetic field, which directs all of the dispersed pions and kaons of positive electric charge straight ahead. Particles with negative charges get defocused. By switching the direction of the electric field, we can focus the negatively charged particles while defocusing the positive charges.

The focused particles in the BNB beam travel through a 50-meter long tunnel. This is where the magic happens. In this empty tunnel, the pions and kaons decay in flight into neutrinos, electrons and muons. At the end of the decay tunnel is a wall of steel and concrete to stop and absorb any particle that is not a neutrino. Because neutrinos interact so rarely, they easily whiz through the absorbers and on towards the experiments. And that’s the basic formula to make a beam of neutrinos!

A single neutrino beamline can support many experiments because the neutrinos interact too rarely to get “used up.” The BNB feeds neutrinos to MicroBooNE, and most of them go on through to the other side towards the MiniBooNE detector. Similarly, most of those go on through the other side as well and continue traveling to infinity and beyond. Detectors located in this beam measure neutrino oscillations and their interactions.

The NuMI beamline is designed similarly, but uses a different target material, two focusing horns, and a 675-meter decay pipe. The spacing between the two NuMI horns is adjustable, allowing fine-tuning of the neutrino beam energy. The NuMI beamline has higher-energy neutrinos than the BNB and thus studies different properties of neutrino oscillations.

The NuMI beamline feeds neutrinos to the MINERvA experiment and on through to the MINOS near detector. The NuMI beamline then continues about 450 miles through Earth on toward the MINOS far detector in the Soudan mine in Minnesota. By the time the beam reaches the far detector, it is about 20 miles in diameter! By having a near and far detector, we are able to observe neutrino flavor oscillations by measuring how much of the beam is electron neutrino flavor and muon neutrino flavor at each of these two detectors.

The last of the big Fermilab neutrino experiments is NOvA. Its near detector is off to the side of the NuMI beam and measures neutrinos only with a specific range of direction and energy. The NOvA far detector is positioned to measure the neutrinos with the same properties at a greater distance, about 500 miles away in Ash River, Minnesota. By placing the NOvA detectors 3 degrees to the side of the beam’s center, NOvA will get to make more precise oscillation measurements for a range of neutrino energies.

As more experiments are designed with more demanding requirements, Fermilab may expect to see more neutrino beamline R&D and the construction of new beamlines.

Tia Miceli

### Scintillator extruded at Fermilab detects particles around the globe

Wednesday, November 26th, 2014

This article appeared in Fermilab Today on Nov. 26, 2014

The plastic scintillator extrusion line, shown here, produces detector material for export to experiments around the world. Photo: Reidar Hahn

Small, clear pellets of polystyrene can do a lot. They can help measure cosmic muons at the Pierre Auger Observatory, search for CP violation at KEK in Japan or observe neutrino oscillation at Fermilab. But in order to do any of these they have to go through Lab 5, located in the Fermilab Village, where the Scintillation Detector Development Group, in collaboration with the Northern Illinois Center for Accelerator and Detector Design (NICADD), manufactures the exclusive source of extruded plastic scintillator.

Like vinyl siding on a house, long thin blocks of plastic scintillator cover the surfaces of certain particle detectors. The plastic absorbs energy from collisions and releases it as measurable flashes of light. Fermilab’s Alan Bross and Anna Pla-Dalmau first partnered with local vendors to develop the concept and produce cost-effective scintillator material for the MINOS neutrino oscillation experiment. Later, with NIU’s Gerald Blazey, they built the in-house facility that has now exported high-quality extruded scintillator to experiments worldwide.

“It was clear that extruded scintillator would have a big impact on large neutrino detectors,” Bross said, “but its widespread application was not foreseen.”

Industrially manufactured polystyrene scintillators can be costly — requiring a labor-intensive process of casting purified materials individually in molds that have to be cleaned constantly. Producing the number of pieces needed for large-scale projects such as MINOS through casting would have been prohibitively expensive.

Extrusion, in contrast, presses melted plastic pellets through a die to create a continuous noodle of scintillator (typically about four centimeters wide by two centimeters tall) at a much lower cost. The first step in the production line mixes into the melted plastic two additives that enhance polystyrene’s natural scintillating property. As the material reaches the die, it receives a white, highly reflective coating that holds in scintillation light. Two cold water tanks respectively bathe and shower the scintillator strip before it is cool enough to handle. A puller controls its speed, and a robotic saw finally cuts it to length. The final product contains either a groove or a hole meant for a wavelength-shifting fiber that captures the scintillation light and sends the signal to electronics in the most useful form possible.

Bross had been working on various aspects of the scintillator cost problem since 1989, and he and Pla-Dalmau successfully extruded experiment-quality plastic scintillator with their vendors just in time to make MINOS a reality. In 2003, NICADD purchased and located at Lab 5 many of the machines needed to form an in-house production line.

“The investment made by Blazey and NICADD opened extruded scintillators to numerous experiments,” Pla-Dalmau said. “Without this contribution from NIU, who knows if this equipment would have ever been available to Fermilab and the rest of the physics community?”

Blazey agreed that collaboration was an important part of the plastic scintillator development.

“Together the two institutions had the capacity to build the resources necessary to develop state-of-the-art scintillator detector elements for numerous experiments inside and outside high-energy physics,” Blazey said. “The two institutions remain strong collaborators.”

Between their other responsibilities at Fermilab, the SDD group continues to study ways to make their scintillator more efficient. One task ahead, according to Bross, is to work modern, glass wavelength-shifting fibers into their final product.

“Incorporation of the fibers into the extrusions has always been a tedious part of the process,” he said. “We would like to change that.”

Troy Rummler

### Neutrinos, claymation and ‘Doctor Who’ at this year’s physics slam

Monday, November 24th, 2014

This article appeared in Fermilab Today on Nov. 24, 2014.

Wes Ketchum of the MicroBooNE collaboration is the Physics Slam III champion. Ketchum’s slam was on the detection of particles using liquid argon. Photo: Cindy Arnold

On Nov. 21, for the third year in a row, the Fermilab Lecture Series invited five scientists to battle it out in an event called a physics slam. And for the third year in a row, the slam proved wildly popular, selling out Ramsey Auditorium more than a month in advance.

More than 800 people braved the cold to watch this year’s contest, in which the participants took on large and intricate concepts such as dark energy, exploding supernovae, neutrino detection and the overwhelming tide of big data. Each scientist was given 10 minutes to discuss a chosen topic in the most engaging and entertaining way possible, with the winner decided by audience applause.

Michael Hildreth of the University of Notre Dame kicked things off by humorously illustrating the importance of preserving data — not just the results of experiments, but the processes used to obtain those results. Marcelle Soares-Santos of the Fermilab Center for Particle Astrophysics took the stage dressed as the Doctor from “Doctor Who,” complete with a sonic screwdriver and a model TARDIS, to explore the effects of dark energy through time.

Joseph Zennamo of the University of Chicago brought the audience along on a high-energy journey through the “Weird and Wonderful World of Neutrinos,” as his talk was called. And Vic Gehman of Los Alamos National Laboratory blew minds with a presentation about supernova bursts and the creation of everything and everyone in the universe.

The slammers at this year’s Fermilab Physics Slam were, Michael Hildreth, University of Notre Dame (far left); Marcelle Soares-Santos, Fermilab (second from left); Vic Gehman, Los Alamos National Laboratory (third from left); Wes Ketchum, Fermilab (second from right); Joseph Zennamo, University of Chicago. Fermilab Director Nigel Lockyer (third from right) congratulated all the participants. Photo: Cindy Arnold

The winner was Fermilab’s Wes Ketchum, a member of the MicroBooNE collaboration. Ketchum’s work-intensive presentation used claymation to show how different particles interact inside a liquid-argon particle detector, depicting them as multicolored monsters bumping into one another and creating electrons for the detector’s sensors to pick up. Audience members won’t soon forget the sight of a large oxygen monster eating red-blob electrons.

After the slam, the five scientists took questions from the audience, including one about dark matter and neutrinos from an eight-year-old boy, sparking much discussion. Chris Miller, speech professor at the College of DuPage, made his third appearance as master of ceremonies for the Physics Slam, and thanked the audience — particularly the younger attendees — for making the trek to Fermilab on a Friday night to learn more about science.

Video of this year’s Physics Slam is available on Fermilab’s YouTube channel.

Andre Salles

### Stanley Wojcicki awarded 2015 Panofsky Prize

Tuesday, November 18th, 2014

This article appeared in Fermilab Today on Nov. 18, 2014.

Stanley Wojcicki

In late October, the American Physical Society Division of Particles and Fields announced that Stanford University professor emeritus of physics and Fermilab collaborator Stanley Wojcicki has been selected as the 2015 recipient of the W.K.H. Panofsky Prize in experimental particle physics. Panofsky, who died in 2007, was SLAC National Accelerator Laboratory’s first director, holding that position from 1961 to 1984.

“I knew Pief Panovsky for about 40 years, and I think he was a great man not only as a scientist, but also as a statesman and as a human being,” said Wojcicki, referring to Panofsky by his nickname. “So it doubles my pleasure and satisfaction in receiving an award that bears his name.”

Wojcicki was given the prestigious award “for his leadership and innovative contributions to experiments probing the flavor structure of quarks and leptons, in particular for his seminal role in the success of the MINOS long-baseline neutrino experiment.”

Wojcicki is a founding member of MINOS. He served as spokesperson from 1999 to 2004 and as co-spokesperson from 2004 to 2010.

“I feel a little embarrassed being singled out because, in high-energy physics, there is always a large number of individuals who have contributed and are absolutely essential to the success of the experiment,” he said. “This is certainly true of MINOS, where we had and have a number of excellent people.”

Wojcicki recalls the leadership of Caltech physicist Doug Michael, former MINOS co-spokesperson, who died in 2005.

“I always regret that Doug did not have a chance to see the results of an experiment that he very much contributed to,” Wojcicki said.

In 2006, MINOS measured an important parameter related to the mass difference between two neutrino types.

Fermilab physicist Doug Glenzinski chaired the Panofsky Prize review committee and says that the committee was impressed by Wojcicki’s work on flavor physics, which focuses on how particles change from one type to another, and his numerous contributions over decades of research.

“He is largely credited with making MINOS happen, with thinking about ways to advance neutrino measurements and with playing an active role in all aspects of the experiment from start to finish,” Glenzinski said.

More than 30 years ago, Wojcicki collaborated on charm quark research at Fermilab, later joining Fermilab’s neutrino explorations. Early on Wojcicki served on the Fermilab Users Executive Committee from 1969-71 and on the Program Advisory Committee from 1972-74. He has since been on many important committees, including serving as chair of the High-Energy Physics Advisory Panel for six years and as member of the P5 committee from 2005-08. He now continues his involvement in neutrino physics, participating in the NOvA and MINOS+ experiments.

“I feel really fortunate to have been connected with Fermilab since its inception,” Wojcicki said. “I think Fermilab is a great lab, and I hope it will continue as such for many years to come.”

Rich Blaustein

### Fermilab’s Oliver Gutsche keeps LHC community computing

Wednesday, November 12th, 2014

This article appeared in DOE Pulse on Nov. 10, 2014.

Fermilab’s Oliver Gutsche leads worldwide computing operations for the CMS experiment. Photo: Reidar Hahn

Since he was a graduate student in Germany, Oliver Gutsche wanted to combine research in particle physics with computing for the large experiments that probe the building blocks of matter.

“When I started working on the physics data coming from one of the experiments at DESY, I was equally interested in everything that had to do with large-scale computing,” said Gutsche of his time at the German laboratory. Gutsche now works at DOE’s Fermi National Accelerator Laboratory. “So I also began working on the computing side of particle physics. For me that was always the combination I wanted to do.”

Gutsche’s desire to merge the two focuses has paid off. For the past four years Gutsche has been in charge of worldwide computing operations of the Large Hadron Collider’s CMS experiment, one of two experiments credited with the 2012 Higgs boson discovery. In December he was awarded the CMS Collaboration Award for his contributions to the global CMS computing system. And more recently, he has been promoted to assistant head of the Scientific Computing Division at Fermilab.

As head of CMS Computing Operations, Gutsche orchestrates data processing, simulations, data analysis and transfers and manages infrastructure and many more central tasks. Monte Carlo simulations of particle interactions, for example, are a key deliverable of the CMS Computing Operations group. Monte Carlo simulations employ randomness to simulate the collisions of the LHC and their products in a statistical way.

“You have to simulate the randomness of nature,” explained Gutsche. “We need Monte Carlo collisions to make sure we understand the data recorded by the CMS experiment and to compare them to the theory.”

When Gutsche received his Ph.D. from the University of Hamburg in 2005, he was looking for a job to combine LHC work, large-scale computing and a U.S. postdoc experience.

“Fermilab was an ideal place to do LHC physics research and LHC computing at the same time,” he said. His postdoc work led to his appointment as an application physicist at Fermilab and as the CMS Computing Operations lead.

Today Gutsche interacts regularly with people at universities and laboratories across the United States and at CERN, host laboratory of the LHC, often starting the day at 7 a.m. for transatlantic or transcontinental meetings.

“I try to talk physics and computing with everyone involved, even those in different time zones, from CERN to the west coast,” he said. Late afternoon in the United States is a good time for writing code. “That’s when everything quiets down and Europe is asleep.”

Gutsche expects to further enhance the cooperation between U.S. particle physicists and their international colleagues, mostly in Europe, by using the new premier U.S. Department of Energy’s Energy Sciences Network recently announced in anticipation of the LHC’s restart in spring 2015 at higher energy.

Helping connect the research done by particle physicists around the world, Gutsche finds excitement in all the work he does.

“Of course the Higgs boson discovery was very exciting,” Gutsche said. “But in CMS Computing Operations everything is exciting because we prepare the basis for hundreds of physics analyses so far and many more to come, not only for the major discoveries.”

Rich Blaustein

### New technique for generating RF power may dramatically cut linac costs

Monday, November 3rd, 2014

This article appeared in Fermilab Today on Nov. 3, 2014.

A team from the Accelerator Division has successfully powered this small SRF cavity with a magnetron. Now they aim to power a large, application-specific model. Photo: Brian Chase, Fermilab

If you own a magnetron, you probably use it to cook frozen burritos. The device powers microwave ovens by converting electricity into electromagnetic radiation. But Fermilab engineers believe they’ve found an even better use. They’ve developed a new technique to use a magnetron to power a superconducting radio-frequency (SRF) cavity, potentially saving hundreds of millions of dollars in the construction and operating costs of future linear accelerators.

The technique is far from market-ready, but recent tests with Accelerator Division RF Department-developed components at the Fermilab AZero test facility have proven that the idea works. Team leaders Brian Chase and Ralph Pasquinelli have, with Fermilab’s Office of Partnerships and Technology Transfer, applied for a patent and are looking for industrial partners to help scale up the process.

Both high-energy physics and industrial applications could benefit from the development of a high-power, magnetron-based RF station. The SRF cavity power source is a major cost of accelerators, but thanks to a long manufacturing history, accelerator-scale magnetrons could be mass-produced at a fraction of the cost of klystrons and other technologies typically used to generate and control radio waves in accelerators.

“Instead of paying $10 to$15 per watt of continuous-wave RF power, we believe that we can deliver that for about \$3 per watt,” Pasquinelli said.

That adds up quickly for modern projects like Fermilab’s Proton Improvement Plan II, with more than 100 cavities, or the proposed International Linear Collider, which will call for about 15,000 cavities requiring more than 3 billion watts of pulsed RF power. The magnetron design is also far more efficient than klystrons, further driving down long-term costs.

The magnetron project members are, from left: Brian Chase, Ed Cullerton, Ralph Pasquinelli and Philip Varghese. Photo: Elvin Harms, Fermilab

But the straightforward idea wasn’t without obstacles.

“For an accelerator, you need very precise control of the amplitude and the phase of the signal,” Chase said. That’s on the order of 0.01 percent accuracy. Magnetrons don’t normally allow this kind of control.

One solution, Chase realized, is to apply a well-known mathematical expression known as a Bessel function, developed in the 19th century for astronomical calculations. Chase repurposed the function for the magnetron’s phase modulation scheme, which allowed for a high degree of control over the signal’s amplitude. Similar possible solutions to the amplitude problem use two magnetrons, but doubling most of the hardware would mean negating potential savings.

“Our technique uses one magnetron, and we use this modulation scheme, which has been known for almost a hundred years. It’s just never been put together,” Pasquinelli said. “And we came in thinking, ‘Why didn’t anyone else think of that?'”

Chase and Pasquinelli are now working with Bob Kephart, director of the Illinois Accelerator Research Center, to find an industry partner to help them develop their idea. Inexpensive, controlled RF power is already needed in certain medical equipment, and according to Kephart, driving down the costs will allow new applications to surface, such as using accelerators to clean up flue gas or sterilizing municipal waste.

“The reason I’m not retired is that I want to build this prototype,” Pasquinelli said. “It’s a solution to a real-world problem, and it will be a lot of fun to build the first one.”

Troy Rummler

### New high-speed transatlantic network to benefit science collaborations across the U.S.

Wednesday, October 22nd, 2014

This Fermilab press release came out on Oct. 20, 2014.

ESnet to build high-speed extension for faster data exchange between United States and Europe. Image: ESnet

Scientists across the United States will soon have access to new, ultra-high-speed network links spanning the Atlantic Ocean thanks to a project currently under way to extend ESnet (the U.S. Department of Energy’s Energy Sciences Network) to Amsterdam, Geneva and London. Although the project is designed to benefit data-intensive science throughout the U.S. national laboratory complex, heaviest users of the new links will be particle physicists conducting research at the Large Hadron Collider (LHC), the world’s largest and most powerful particle collider. The high capacity of this new connection will provide U.S. scientists with enhanced access to data at the LHC and other European-based experiments by accelerating the exchange of data sets between institutions in the United States and computing facilities in Europe.

DOE’s Brookhaven National Laboratory and Fermi National Accelerator Laboratory—the primary computing centers for U.S. collaborators on the LHC’s ATLAS and CMS experiments, respectively—will make immediate use of the new network infrastructure once it is rigorously tested and commissioned. Because ESnet, based at DOE’s Lawrence Berkeley National Laboratory, interconnects all national laboratories and a number of university-based projects in the United States, tens of thousands of researchers from all disciplines will benefit as well.

The ESnet extension will be in place before the LHC at CERN in Switzerland—currently shut down for maintenance and upgrades—is up and running again in the spring of 2015. Because the accelerator will be colliding protons at much higher energy, the data output from the detectors will expand considerably—to approximately 40 petabytes of raw data per year compared with 20 petabytes for all of the previous lower-energy collisions produced over the three years of the LHC first run between 2010 and 2012.

The cross-Atlantic connectivity during the first successful run for the LHC experiments, which culminated in the discovery of the Higgs boson, was provided by the US LHCNet network, managed by the California Institute of Technology. In recent years, major research and education networks around the world—including ESnet, Internet2, California’s CENIC, and European networks such as DANTE, SURFnet and NORDUnet—have increased their backbone capacity by a factor of 10, using sophisticated new optical networking and digital signal processing technologies. Until recently, however, higher-speed links were not deployed for production purposes across the Atlantic Ocean—creating a network “impedance mismatch” that can harm large, intercontinental data flows.

An evolving data model
This upgrade coincides with a shift in the data model for LHC science. Previously, data moved in a more predictable and hierarchical pattern strongly influenced by geographical proximity, but network upgrades around the world have now made it possible for data to be fetched and exchanged more flexibly and dynamically. This change enables faster science outcomes and more efficient use of storage and computational power, but it requires networks around the world to perform flawlessly together.

“Having the new infrastructure in place will meet the increased need for dealing with LHC data and provide more agile access to that data in a much more dynamic fashion than LHC collaborators have had in the past,” said physicist Michael Ernst of DOE’s Brookhaven National Laboratory, a key member of the team laying out the new and more flexible framework for exchanging data between the Worldwide LHC Computing Grid centers.

Ernst directs a computing facility at Brookhaven Lab that was originally set up as a central hub for U.S. collaborators on the LHC’s ATLAS experiment. A similar facility at Fermi National Accelerator Laboratory has played this role for the LHC’s U.S. collaborators on the CMS experiment. These computing resources, dubbed Tier 1 centers, have direct links to the LHC at the European laboratory CERN (Tier 0).  The experts who run them will continue to serve scientists under the new structure. But instead of serving as hubs for data storage and distribution only among U.S.-based collaborators at Tier 2 and 3 research centers, the dedicated facilities at Brookhaven and Fermilab will be able to serve data needs of the entire ATLAS and CMS collaborations throughout the world. And likewise, U.S. Tier 2 and Tier 3 research centers will have higher-speed access to Tier 1 and Tier 2 centers in Europe.

“This new infrastructure will offer LHC researchers at laboratories and universities around the world faster access to important data,” said Fermilab’s Lothar Bauerdick, head of software and computing for the U.S. CMS group. “As the LHC experiments continue to produce exciting results, this important upgrade will let collaborators see and analyze those results better than ever before.”

Ernst added, “As centralized hubs for handling LHC data, our reliability, performance and expertise have been in demand by the whole collaboration, and now we will be better able to serve the scientists’ needs.”

An investment in science
ESnet is funded by DOE’s Office of Science to meet networking needs of DOE labs and science projects. The transatlantic extension represents a financial collaboration, with partial support coming from DOE’s Office of High Energy Physics (HEP) for the next three years. Although LHC scientists will get a dedicated portion of the new network once it is in place, all science programs that make use of ESnet will now have access to faster network links for their data transfers.

“We are eagerly awaiting the start of commissioning for the new infrastructure,” said Oliver Gutsche, Fermilab scientist and member of the CMS Offline and Computing Management Board. “After the Higgs discovery, the next big LHC milestones will come in 2015, and this network will be indispensable for the success of the LHC Run 2 physics program.”

This work was supported by the DOE Office of Science.
Fermilab is America’s premier national laboratory for particle physics and accelerator research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance, LLC. Visit Fermilab’s website at www.fnal.gov and follow us on Twitter at @FermilabToday.

Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy.  The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time.  For more information, please visit science.energy.gov.

One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by the Research Foundation for the State University of New York on behalf of Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit applied science and technology organization.

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The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

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### Fermilab’s 500-mile neutrino experiment up and running

Monday, October 6th, 2014

This Fermilab press release came out on Oct. 6, 2014.

With construction completed, the NOvA experiment has begun its probe into the mysteries of ghostly particles that may hold the key to understanding the universe. Image: Fermilab/Sandbox Studio

It’s the most powerful accelerator-based neutrino experiment ever built in the United States, and the longest-distance one in the world. It’s called NOvA, and after nearly five years of construction, scientists are now using the two massive detectors – placed 500 miles apart – to study one of nature’s most elusive subatomic particles.

Scientists believe that a better understanding of neutrinos, one of the most abundant and difficult-to-study particles, may lead to a clearer picture of the origins of matter and the inner workings of the universe. Using the world’s most powerful beam of neutrinos, generated at the U.S. Department of Energy’s Fermi National Accelerator Laboratory near Chicago, the NOvA experiment can precisely record the telltale traces of those rare instances when one of these ghostly particles interacts with matter.

Construction on NOvA’s two massive neutrino detectors began in 2009. In September, the Department of Energy officially proclaimed construction of the experiment completed, on schedule and under budget.

“Congratulations to the NOvA collaboration for successfully completing the construction phase of this important and exciting experiment,” said James Siegrist, DOE associate director of science for high energy physics. “With every neutrino interaction recorded, we learn more about these particles and their role in shaping our universe.”

NOvA’s particle detectors were both constructed in the path of the neutrino beam sent from Fermilab in Batavia, Illinois, to northern Minnesota. The 300-ton near detector, installed underground at the laboratory, observes the neutrinos as they embark on their near-light-speed journey through the Earth, with no tunnel needed. The 14,000-ton far detector — constructed in Ash River, Minnesota, near the Canadian border – spots those neutrinos after their 500-mile trip and allows scientists to analyze how they change over that long distance.

For the next six years, Fermilab will send tens of thousands of billions of neutrinos every second in a beam aimed at both detectors, and scientists expect to catch only a few each day in the far detector, so rarely do neutrinos interact with matter.

From this data, scientists hope to learn more about how and why neutrinos change between one type and another. The three types, called flavors, are the muon, electron and tau neutrino. Over longer distances, neutrinos can flip between these flavors. NOvA is specifically designed to study muon neutrinos changing into electron neutrinos. Unraveling this mystery may help scientists understand why the universe is composed of matter and why that matter was not annihilated by antimatter after the big bang.

Scientists will also probe the still-unknown masses of the three types of neutrinos in an attempt to determine which is the heaviest.

“Neutrino research is one of the cornerstones of Fermilab’s future and an important part of the worldwide particle physics program,” said Fermilab Director Nigel Lockyer. “We’re proud of the NOvA team for completing the construction of this world-class experiment, and we’re looking forward to seeing the first results in 2015.”

The far detector in Minnesota is believed to be the largest free-standing plastic structure in the world, at 200 feet long, 50 feet high and 50 feet wide. Both detectors are constructed from PVC and filled with a scintillating liquid that gives off light when a neutrino interacts with it. Fiber optic cables transmit that light to a data acquisition system, which creates 3-D pictures of those interactions for scientists to analyze.

The NOvA far detector in Ash River saw its first long-distance neutrinos in November 2013. The far detector is operated by the University of Minnesota under an agreement with Fermilab, and students at the university were employed to manufacture the component parts of both detectors.

“Building the NOvA detectors was a wide-ranging effort that involved hundreds of people in several countries,” said Gary Feldman, co-spokesperson of the NOvA experiment. “To see the construction completed and the operations phase beginning is a victory for all of us and a testament to the hard work of the entire collaboration.”

The NOvA collaboration comprises 208 scientists from 38 institutions in the United States, Brazil, the Czech Republic, Greece, India, Russia and the United Kingdom. The experiment receives funding from the U.S. Department of Energy, the National Science Foundation and other funding agencies.

For more information, visit the experiment’s website: http://www-nova.fnal.gov.

Note: NOvA stands for NuMI Off-Axis Electron Neutrino Appearance. NuMI is itself an acronym, standing for Neutrinos from the Main Injector, Fermilab’s flagship accelerator.

Fermilab is America’s premier national laboratory for particle physics and accelerator research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance, LLC. Visit Fermilab’s website at www.fnal.gov and follow us on Twitter at @FermilabToday.

The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

### High school students advance particle physics and their own science education at Fermilab

Tuesday, September 30th, 2014

This article appeared in Fermilab Today on Sept. 30, 2014.

Illinois Mathematics and Science Academy students Nerione Agrawal (left) and Paul Nebres (right) work on the Muon g-2 experiment through the Student Inquiry and Research program. Muon g-2 scientist Brendan Kiburg (center) co-mentors the students. Photo: Fermilab

As an eighth grader, Paul Nebres took part in a 2012 field trip to Fermilab. He learned about the laboratory’s exciting scientific experiments, said hello to a few bison and went home inspired.

Now a junior at the Illinois Mathematics and Science Academy (IMSA) in Aurora, Nebres is back at Fermilab, this time actively contributing to its scientific program. He’s been working on the Muon g-2 project since the summer, writing software that will help shape the magnetic field that guides muons around a 150-foot-circumference muon storage ring.

Nebres is one of 13 IMSA students at Fermilab. The high school students are part of the academy’s Student Inquiry and Research program, or SIR. Every Wednesday over the course of a school year, the students use these weekly Inquiry Days to work at the laboratory, putting their skills to work and learning new ones that advance their understanding in the STEM fields.

The program is a win for both the laboratory and the students, who work on DZero, MicroBooNE, MINERvA and electrical engineering projects, in addition to Muon g-2.

“You can throw challenging problems at these students, problems you really want solved, and then they contribute to an important part of the experiment,” said Muon g-2 scientist Brendan Kiburg, who co-mentors a group of four SIR students with scientists Brendan Casey and Tammy Walton. “Students can build on various aspects of the projects over time toward a science result and accumulate quite a nice portfolio.”

This year roughly 250 IMSA students are in the broader SIR program, conducting independent research projects at Argonne National Laboratory, the University of Chicago and other Chicago-area institutions.

IMSA junior Nerione Agrawal, who started in the SIR program this month, uses her background in computing and engineering to simulate the potential materials that will be used to build Muon g-2 detectors.

“I’d been to Fermilab a couple of times before attending IMSA, and when I found out that you could do an SIR at Fermilab, I decided I wanted to do it,” she said. “I’ve really enjoyed it so far. I’ve learned so much in three weeks alone.”

The opportunities for students at the laboratory extend beyond their particular projects.

“We had the summer undergraduate lecture series, so apart from doing background for the experiment, I learned what else is going on around Fermilab, too,” Nebres said. “I didn’t expect the amount of collaboration that goes on around here to be at the level that it is.”

In April, every SIR student will create a poster on his or her project and give a short talk at the annual IMSAloquium.

Kiburg encourages other researchers at the lab to advance their projects while nurturing young talent through SIR.

“This is an opportunity to let a creative person take the reins of a project, steward it to completion or to a point that you could pick up where they leave off and finish it,” he said. “There’s a real deliverable outcome. It’s inspiring.”

Leah Hesla

### Breakthrough: nanotube cathode creates more electron beam than large laser system

Monday, September 22nd, 2014

This article appeared in Fermilab Today on Sept. 22, 2014.

Harsha Panunganti of Northern Illinois University works on the laser system (turned off here) normally used to create electron beams from a photocathode. Photo: Reidar Hahn

Lasers are cool, except when they’re clunky, expensive and delicate.

So a collaboration led by RadiaBeam Technologies, a California-based technology firm actively involved in accelerator R&D, is designing an electron beam source that doesn’t need a laser. The team led by Luigi Faillace, a scientist at RadiaBeam, is testing a carbon nanotube cathode — about the size of a nickel — in Fermilab’s High-Brightness Electron Source Lab (HBESL) that completely eliminates the need for a room-sized laser system currently used to generate the electron beam.

Fermilab was sought out to test the experimental cathode because of its capability and expertise for handling intense electron beams, one of relatively few labs that can support this project.

Tests have shown that the vastly smaller cathode does a better job than the laser. Philippe Piot, a staff scientist in the Fermilab Accelerator Division and a joint appointee at Northern Illinois University, says tests have produced beam currents a thousand to a million times greater than the one generated with a laser. This remarkable result means that electron beam equipment used in industry may become not only less expensive and more compact, but also more efficient. A laser like the one in HBESL runs close to half a million dollars, Piot said, about hundred times more than RadiaBeam’s cathode.

The technology has extensive applications in medical equipment and national security, as an electron beam is a critical component in generating X-rays. And while carbon nanotube cathodes have been studied extensively in academia, Fermilab is the first facility to test the technology within a full-scale setting.

“People have talked about it for years,” said Piot, “but what was missing was a partnership between people that have the know-how at a lab, a university and a company.”

The dark carbon-nanotube-coated area of this field emission cathode is made of millions of nanotubes that function like little lightning rods. At Fermilab’s High-Brightness Electron Source Lab, scientists have tested this cathode in the front end of an accelerator, where a strong electric field siphons electrons off the nanotubes to create an intense electron beam. Photo: Reidar Hahn

Piot and Fermilab scientist Charles Thangaraj are partnering with RadiaBeam Technologies staff Luigi Faillace and Josiah Hartzell and Northern Illinois University student Harsha Panuganti and researcher Daniel Mihalcea. A U.S. Department of Energy Small Business Innovation Research grant, a federal endowment designed to bridge the R&D gap between basic research and commercial products, funds the project. The work represents the kind of research that will be enabled in the future at the Illinois Accelerator Research Center — a facility that brings together Fermilab expertise and industry.

The new cathode appears at first glance like a smooth black button, but at the nanoscale it resembles, in Piot’s words, “millions of lightning rods.”

“When you apply an electric field, the field lines organize themselves around the rods’ extremities and enhance the field,” Piot said. The electric field at the peaks is so intense that it pulls streams of electrons off the cathode, creating the beam.

Traditionally, lasers strike cathodes in order to eject electrons through photoemission. Those electrons form a beam by piggybacking onto a radio-frequency wave, synchronized to the laser pulses and formed in a resonance cavity. Powerful magnets focus the beam. The tested nanotube cathode requires no laser as it needs only the electric field already generated by the accelerator to siphon the electrons off, a process dubbed field emission.

The intense electric field, though, has been a tremendous liability. Piot said critics thought the cathode “was just going to explode and ruin the electron source, and we would be crying because it would be dead.”

One of the first discoveries Piot’s team made when they began testing in May was that the cathode did not, in fact, explode and ruin everything. The exceptional strength of carbon nanotubes makes the project feasible.

Still, Piot continues to study ways to optimize the design of the cathode to prevent any smaller, adverse effects that may take place within the beam assembly. Future research also may focus on redesigning an accelerator that natively incorporates the carbon nanotube cathode to avoid any compatibility issues.

Troy Rummler