june 2010

issue 3

volume 7dimensionsof particle physicssymmetry

A joint Fermilab/SLAC publication

symmetryA joint Fermilab/SLAC publication

02EditorialParticle physics, or at least the news reports of it, often seems concerned only with the existence of various particles. However, physicists are just as interested in what happens as those particles turn into each other.

03Commentary: Becky ParkerAn electronic chip developed at CERN inspires teenagers to design an experi-ment that will fly into space—and inspires their teacher to start a research network for high-school students.

04Signal to Background Gob-smacked by a dinobird; National Lab Day gets an island vibe; a physicist’s winning formula for predicting baseball winners; taking greenhouse-gas trapping to a new level; a very stretchy midnight snack; letters; correction

08symmetrybreakingA summary of recent stories published online in symmetry breaking, www.symmetrymagazine.org/blog/june2010

volume 7 | issue 3 | june 2010

On the coverIn this artwork, Braniac, John Zaklikowski used every last mother board, cell phone and floppy disk he had collected—and an array of low-tech goods ranging from old-fash-ioned telephone bells to a kitchen-sink strainer. He began with a rigid plywood armature and used screws to attach hundreds of components. A thick blue ring made of wax mixed with pigment added coherence to the intricate result, a juxtaposition of high and low tech. See more of his work in the Gallery on page 38.Photo: Bradley Plummer, SLAC

10The Muon Guys: On the Hunt for New PhysicsScientists are resurrecting an experiment that died two deaths on two continents over the course of two decades. Called Mu2e, it will look for an event so rare that, according to the Standard Model, people should never be able to build a machine sensitive enough to see it.

18The LHC DecodedWalk like a physicist, point by point, through three displays that highlight scientific and technical milestones from the Large Hadron Collider’s first months of operation.

26Science Road TripIn the summer of 1928, the young Ernest O. Lawrence set out across America in a Flying Cloud coupe to begin his new life at the University of California, Berkeley. Eighty-one years later, a writer and a pho-tographer took a road trip to visit the legacy of this accelerator-physics pioneer: American Big Science.

34Day in the Life: Joe FrischRunning the world’s most powerful X-ray laser requires a special intensity.

38Gallery: John ZaklikowskiOver the past several years, John Zaklikowski has spent nearly all of his savings on the circuitry and electrical components he used to create nearly a dozen works, most of them modeled on large-scale particle phys-ics experiments.

42Accelerator Apps: Sterilizing Medical SuppliesFor certain products, such as prepackaged syringes, the ideal sterilizing agent may be a stream of electrons from an accelerator.

C3Logbook: CERN Touch ScreenOn March 11, 1972, CERN engineer Bent Stumpe proposed a new type of interactive computer display for controlling the lab’s new Super Proton Synchrotron accelerator. It was apparently the world’s first capaci-tive touch screen, a technology now widely used in ticket machines and smart phones.

C4Explain it in 60 Seconds: Charged LeptonsCharged leptons are a breed of elemen-tary particle that comes in three masses: the lightweight electron, responsible for the electricity in our homes; the middle-weight muon; and the heavy tau. The Mu2e experiment hopes to catch muons turning into electron, a phenomenon known as flavor violation.

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The enlightening transition from stuff to stuffIn practice, much of particle physics involves looking at how stuff turns into other stuff. When high-energy particles decay into new particles, the properties of those decays tell you all sorts of things about the original particles. Conversely, some of the properties of the new particles can be deduced from how they came into being. The process of change is just as important as the characteristics of the stuff involved in that change when it comes to understanding the laws of nature.

In many cases, the process is obscured; physicists see only the start or the end of it. When all of the energy that goes into a particle colli-sion can’t be accounted for in the aftermath, it means physicists are not seeing some of the end products—neutrinos, perhaps, or something more exotic that their detectors aren’t picking up. In other cases, only the end products are visible, such as in experiments where physicists see light coming from high-energy muons that were created as neutrinos hit the detector. Astrophysicists may look for gamma rays that are the end product of dark-matter annihilation, which we can’t see directly.

But in the best cases, when both the initial and end products are visible, physicists can often close loopholes involving exotic particles or unknown physical phenomena. One example recently is the

OPERA experiment’s observation of muon neu-trinos turning into tau neutrinos in a process called oscillation. This marked the first time that the second half of the process—the tau neutrino appearing out of the oscillation—had been cap-tured. (See the May 31 post in symmetry breaking online for more details of that experiment.)

A planned experiment called Mu2e, in which muons might be seen turning into electrons, is another example of capturing both the initial components and end products of a change. (See page 10.) Physicists don’t yet know if this process actually exists, but the question of whether it does or not (see “Explain it in 60 Sec-onds” on the back cover) has big implications for the fundamental structure of the laws of the universe, especially as scientists try to unify all the particles and forces into a sensible, consistent framework.

Particle physics, or at least the news reports of it, often seems concerned only with the exis-tence and characteristics of various particles. However, physicists are just as interested in what happens as those particles turn into each other. The universe is not merely a zoo of strange stuff. It is an oddly behaved, mysterious, and intriguing dance of evanescent players, with an ever-changing choreography, and new performers appearing on the floor as it progresses. It is the dance of the universe that enlivens us and drives us, gradually revealing its steps to those persistent enough to watch closely.David Harris, Editor-in-Chief

from the editor

SymmetryPO Box 500MS 206Batavia Illinois 60510USA

630 840 3351 telephone 630 840 8780 fax mail@symmetrymagazine.org

For subscription services go to www.symmetrymagazine.org

symmetry (ISSN 1931-8367) is published six times per year by Fermi National Accelerator Laboratory and SLAC National Accelerator Laboratory, funded by the US Department of Energy Office of Science. (c) 2010 symmetry All rights reserved

Editor-in-ChiefDavid Harris650 926 8580

Deputy EditorGlennda Chui

Managing EditorKurt Riesselmann

Senior EditorTona Kunz

Staff WritersElizabeth Clements Calla Cofield Kathryn Grim Kelen Tuttle Rhianna Wisniewski

InternsMarissa CevallosJulie KarceskiAndrea MustainDaisy Yuhas

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commentary: becky parker

A student research network built on a chipWhat inspired you in physics? Was it the curricu-lum at school? For me it was a lecture about Mars that Carl Sagan gave at the Royal Institution; it was 1977, and he invited the audience—I was watching on the TV—to have tea with him on Mars.

At Simon Langton Grammar School for Boys in Canterbury, where I teach, we are trying to inspire the next generation of scientists and engineers by getting them involved in real scien-tific activity—not just cookbook experiments where you turn the page and there’s the answer.

We got a valuable jolt of inspiration from a field trip to CERN, the European particle physics center on the Swiss-French border. It led our students to build an instrument that will be flown in space and spawned the CERN@school pro-gram, which has the goal of placing cosmic-ray detectors in school laboratories throughout Europe and beyond, allowing student-scientists to collaborate and share their data through the Langton Star Centre here on campus.

It all started in 2007, when 48 of our students visited the labs of Michael Campbell and his team at CERN. The team was working on Medipix chips—sensitive light detectors, originally devel-oped for particle physics research at the Large Hadron Collider, that have been adapted for medical imaging and other uses.

On our return to the United Kingdom, we were notified of a space experiment competition run by what is now the UK Space Agency along with Surrey Satellite Technology Limited, or SSTL, the world’s largest manufacturer of small satellites. The guidelines warned that the orbiting experiments could suffer damage from cosmic rays. I remember sitting in my lab with a crowd of students who were still excited from the trip to CERN. One of them said, “Why don’t we use those Medipix chips we have just seen to measure the cosmic radiation?” I responded, “Brilliant!”

My students, ages 16 to 18, won the competition with their design for a cosmic ray detector made from five chips from the Medipix series. Their instrument, called LUCID for Langton Ultimate Cosmic ray Intensity Detector, will fly on a satellite called TechDemoSat to be launched by SSTL in early 2012. The students have been developing the detector with help from SSTL engineers and Larry Pinsky, chair of physics at the University of Houston. It’s thrilling to know that NASA is interested in the data.

With our students so inspired, it seemed sen-sible to extend this enthusiasm and involve other schools. So the CERN@school project was

born. It allows school laboratories to obtain smaller versions of the LUCID detector for experiments in cosmic-ray detection and radioactivity. Students in 10 pilot schools are already taking and sharing data.

We also hope the CERN@school package will draw more people into physics teaching; recent and upcoming physics graduates I have talked with say the ability to do real research with their students would make teaching physics a more attractive proposition.

Our school, with about 1000 students, pro-duces between one-half and one percent of the United Kingdom’s physicists. We are sure that when LUCID and CERN@school are fully rolled out they will significantly increase the number of graduating students who go into science and engineering. Even though we are a boys’ school, we do enroll girls in the last two years before graduation, and the impact of the project on girls’ uptake of physics and engineering courses is even more significant.

We want the Langton Star Centre to be the hub of research projects across the sciences, a place where teachers and their students will come for training in labs and classrooms and go on to transform science education into the vibrant, wonderful subject it should be.

We also want to collaborate with other student cosmic-ray projects—including QuarkNet in the United States, HISPARC in the Netherlands, and the Canadian ALTA project, which links to net-works in the United States and the Czech Republic—to develop a common protocol for data. This would give students a much larger data set to work on, with great potential.

Students need inspiration to allow them to become the great scientists and engineers of the future. I am hopeful that CERN@school can help inspire many into physics.

Becky Parker is head of physics at Simon Langton Grammar School for Boys and director of the Langton Star Centre. She was named a Member of the Order of the British Empire in 2008 for her work in science education.

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Hey, waiter! There’s a feather in my fossil!One hundred and fifty million years ago, a creature part dino-saur and part bird sank into the murky depths of a lagoon, never to fly again. Its fossilized remains, unearthed from a German limestone quarry, are the most complete and best preserved of the 10 known fossils of Archaeopteryx, the famous evolutionary link between dinosaurs and birds.

In December 2008, this urvogel—German for “primordial bird”—traveled from its home at the Wyoming Dinosaur Center to SLAC National Accelerator Laboratory for the first-ever chemical analysis of a dinobird specimen, performed by an unlikely mix of physicists, pale-ontologists, and geochemists from around the world.

Their tool was a powerful X-ray beam generated by elec-trons racing around a particle

storage ring at SLAC’s Stanford Synchrotron Radiation Lightsource. Sweeping the hair-thin beam over the 40-by-40-centimeter fossil, the team found remnants of the bird’s original chemistry, including phosphorus, sulfur, copper, and zinc.

“For 50 years, everyone has assumed that these beautiful feather impressions were nothing but impressions,” says University of Manchester geochemist Roy Wogelius. “But they’re not. The feather shafts are still there. There’s actually original chemistry left.”

What’s more, trace metals in the fossil, including copper and zinc, are “undoubtedly from the bones,” says SLAC physicist Uwe Bergmann. This suggests that Archaeopteryx, like modern birds, needed these elements in its diet to stay healthy.

“Quite simply, there’s much more inside of fossils than we ever imagined,” says University

of Manchester paleontologist Phil Manning. “There’s gob-smackingly exciting stuff on the horizon; I think we have hit on some very exciting mod-ern science. But this science can’t happen without people who work out of their box. This work is the result of com-pletely unrelated sciences all coming together and making a perfect storm.”

It wasn’t the first time chemical traces of the original animal have been found in a fossil. But until recently the techniques were too slow and too lacking in detail for practical use. Now they have improved to the point that researchers could detect not just chemicals from the dinobird, but also the chemical processes involved in its fossilization, materials that had been used in its resto-ration, and even fingerprints on its stony surface.Kelen Tuttle

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signal to background

Gob-smacked by a dinobird; National Lab Day gets an island vibe; a physicist’s

winning formula for predicting baseball winners; taking greenhouse-gas trapping

to a new level; a very stretchy midnight snack; letters; correction

National Lab Day puts scientists in the classroomPier Oddone wandered past stu-dents who were setting up electrical circuits and asked how many of them were considering careers in science. Half raised their hands. “What about a career in physics?” he asked. All but two hands dropped.

“Well, I’m here to change that,” he said.

For the next few hours, Oddone, the director of Fermi National Accelerator Laboratory in Illinois, told the students from various Hawaiian high schools about his life as a scientist and his journey from Argentina to become head of the leading high-energy physics laboratory in the United States. He told them no one can yet explain how the universe formed, and talked of the mysteries that particle physics research could unravel. He fielded questions about whether antimatter bombs like the ones in the movie Angels and Demons could exist (no) and whether the Large Hadron Collider might generate Earth-gobbling black holes (no again).

“He connected with them,” says physics teacher Hanno Adams. “They saw a scientist as human, and how science could affect their lives. The kids got a feeling that science is still in a discovery stage.”

Oddone had succeeded in doing at President Barack Obama’s alma mater, Punahou School in Honolulu, what the president had asked scientists across the nation to do in honor of National Lab Day: engage students in science, technology, engineering, and math. Hundreds of professionals fanned out to schools during the first week of May to push students to sharpen their skills in those key fields, make them aware of the careers those skills unlock, and give them a chance to learn with their hands, not just their textbooks.

Oddone and his wife, Barbara, who were on vacation

in Hawaii at the time, chose to visit Punahou because it partici-pates in the national QuarkNet program, which helps students construct cosmic-ray detectors for classroom research.

Eventually teachers had to pry the students away from the now-weary-looking Oddones.

“They were flooding around him to get pictures and auto-graphs,’” Adams says. “They were into it.”Tona Kunz

Take me out to the calculatorBaseball fans and physicists share two key loves: numbers and acronyms. While fans pore over statistics on RBIs, OBPs, and ERAs, physicists analyze data from particle accelerators such as RHIC, LHC, and CESR.

Kerry Whisnant, a professor of physics at Iowa State University and lifelong baseball fan, studies the ghostly parti-cles known as neutrinos. Growing up in central Illinois, he loved the St. Louis Cardinals and still catches their games when he can.

About two years ago, his love of baseball took an analytical turn. He began writing a regular column for dugoutcentral.com on the mathematics behind baseball statistics. And he started tinkering with a hallowed formula, developed three decades ago by statistician Bill James, that uses the number of runs a team scores per game

to predict how it will do in a given season.

First Whisnant factored in how those runs are distributed across a season. Consistency mattered. For example, teams that consistently score about six runs per game will fare better over the course of the season than teams that fluctuate between two and 10 runs, even if the average score per game is the same.

Whisnant then accounted for the slugging percentage, which predicts the power of a hitter based on how many singles, doubles, triples, and home runs he hits per opportunity at bat.

Folding these two factors into the formula significantly improved its ability to predict how well a team would do over the course of a season, Whisnant says. It cut the already-small difference between a team’s predicted record and its actual record by half.

The impact of slugging per-centage is large enough that teams might want to use it to help determine a player’s value, Whisnant says. At the same time, he acknowledges that this is just one piece of a compli-cated puzzle that includes such things as star power and popu-larity with fans.

Whisnant presented his find-ings in March at the MIT Sloan Sports Analytic Conference. His paper won first place in the academic division. Julie Karceski

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Getting down with CO2When Princeton University geo-scientist Catherine Peters learned about a plan to build the world’s deepest sciencelaboratory in an abandoned gold mine in South Dakota, she saw a chance to tackle an urgent challenge: how to store carbon dioxide deep under-ground so it can’t escape into the atmosphere and contribute

to global warming.Peters and colleagues from

Princeton and Lawrence Berkeley National Laboratory hope to carry out their DUSEL CO2 project at the proposed Deep Underground Science and Engineering Laboratory, which will host research in physics and a wide range of other fields.

“The geology of the Homestake Mine is not what we’re interested in,” Peters says. “Instead it’s the depth.”

In the mine’s roomy interior, scientists plan to build models of the kinds of geological structures that are being con-sidered for carbon storage, says Curtis Oldenburg, leader of the Berkeley Lab contingent. These “flow columns” aren’t miniatures. Taller than the Empire State Building, packed with layers of sand and clay and filled with brine or other fluids, they will allow researchers to see what happens to dense CO2 injected at different tem-peratures and pressures. They want to know if the CO2 will stay deep underground, and what happens if it leaks out.

The Houston-based company Schlumberger, a leader in deep monitoring technology in the oil and gas fields and DUSEL CO2’s industrial partner, works in far deeper wells across the world. But with a well, the only way in is from the top. The Homestake Mine’s shafts and drifts will allow access from top to bottom, revealing at what point the CO2 changes phase from a liquid to a gas, whether the paths it takes through fractured shale or cement well linings get bigger over time or seal themselves, and what role microbes play in converting CO2 to other gases or minerals.

Open to scientists from all over the world, DUSEL CO2 will allow scientists to model the deep Earth on a scale a bit smaller than Earth itself.Paul Preuss

Sharing pizzaacross the PacificMonitoring a particle detector on the midnight shift can have a limited upside: the food.

To compensate for the bad hours and limited social con-tact, control room supervisors on CDF, one of the Tevatron collider experiments at Fermilab, have a tradition of supplying their crews with dinner or a midnight snack. Offerings have included donuts and chips, a selection of fine cheeses and meats, and sushi brought in from two towns away.

But Japanese and Italian collaborators working remotely from control rooms at their home institutions lost out—until one night in April.

Junji Naganoma, a postdoc working at KEK in Japan, was sitting more than 6000 miles away, watching on a videocon-ference screen as his Illinois colleagues got ready for their midnight feast, when he heard a knock on the door.

It was a delivery man with an American-style pizza, a present from the CDF shift supervisor.

Other students gathered to gawk and hold up a Web cam so a shocked Naganoma could prove to his peers that he got their present and was eating the same thing they were. Everybody got a slice.

“They thought it was good of CDF to do,” Naganoma says.

Back at Fermilab, shift leader William Wester was relieved the delivery worked out. There

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signal to background

had been so many things to worry about. The first pizza place he called in Tsukuba, Japan, had closed down. No one spoke English at the second, so he tried to order online, praying the buttons he clicked wouldn’t stick him with a bill for a hun-dred pizzas—and that his credit card company wouldn’t balk at approving a transaction

involving an Illinois man ordering pizza for delivery in Japan.

Finally, Wester resorted to calling CDF collaborator Fumi Ukegawa, who was teaching in Japan, and had him place the order. As the clock ticked down to delivery time, Wester shot furtive glances at the videoconference screen, worry-ing Naganoma would start

eating his own meal. Laughing at the complexity

of the delivery, Naganoma said it reminded him of times he spent working at Fermilab and reinforced one of the things he loves about particle physics: collaborating with people from many countries and sharing thoughts and traditions. Tona Kunz

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letters

correction

More universities offer accelerator trainingWhile I was generally pleased by the content and message of Chris Knight’s article on accelerator physics as a career in the April 2010 edition of symmetry—particularly by the wise advice offered by my old Caltech undergraduate advisor Alvin Tollestrup—I think Chris missed the growing contributions of smaller US universities to the training of the next generation of accelerator physicists and tech-nologists. Examples might include the free-electron laser programs at the University of California at Santa Barbara, Duke University, the Naval Postgraduate School in Monterey, Calif., and my own institution, the University of Hawai’i at Manoa.

Free-electron lasers on the one hand, and high-gradient laser accelerator systems on the other, now offer such smaller schools the opportunity to do competitive front-line research with facilities and resources they can afford, much like the grand old days of “high energy” nuclear and particle physics. And for students at such smaller institutions, with generally smaller and more closely integrated research teams, the only limits to the scope of their training and contributions are set by their ambitions and commitments to the field—an ideal environment for those looking to extend the state of the art.

Caltech did indeed run such a program 50 years ago, and my exposure to Alvin, his colleagues, and staff did much to inspire my own subsequent efforts to demonstrate and develop the free-electron laser and the high-brightness injectors that have helped to make these devices practical. John Madey, University of Hawai’i at Manoa

The editors respond: Thanks for pointing this out. It has been brought to our attention that the program at Northern Illinois University was also left off the list. Our sincere apologies for these omissions.

The year Salpeter diedIn our April 2010 issue, a logbook article about a 1962 meeting of Nobel laureates misstated the year that physicist Edwin Salpeter died. It was 2008, not 2009.

symmetrybreaking

Highlights from our blog

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Anticipating the first steps beyond the Standard ModelJune 3, 2010

Members of the SLAC theory group describe the kinds of questions they are trying to answer and mysteries they are trying to resolve based on the expected first data from the Large Hadron Collider.

Listening to the sound of scienceJune 1, 2010

Ever wondered what you would hear if you could shrink to the size of a proton, squeeze into the Large Hadron Collider beam pipe, and listen to particles col-liding? Would there be sounds, noises, maybe even music? That’s what Lily Asquith, ATLAS scientist and head of the LHCsound project, believes.

OPERA catches its first tau neutrinoMay 31, 2010

Scientists from the OPERA experiment at INFN’s Gran Sasso National Laboratory have announced the first direct observation of a neutrino trans-forming from one type into another. Detecting this one rare event took three years.

Accelerator physicists strive to lower cost of cancer treatmentMay 28, 2010

Accelerator physicists from industry and academia were challenged this week at the First International Particle Accelerator Conference in Kyoto, Japan, to find ways to make a new cancer treatment, carbon-ion therapy, more affordable.

Middle East accelerator project approaches barrierMay 27, 2010

An unlikely international col-laboration that is building the first synchrotron lightsource in the Middle East has dealt with outdated equipment, inexperi-ence, and language barriers. Now it faces another hurdle: finding more than $24 million to complete the final section of the accelerator.

The ATLAS Experiment: Popping up next month across North America May 20, 2010

The world’s first Large Hadron Collider pop-up book has gotten a makeover for North American readers. The silver edition of Voyage to the Heart of Matter features enhanced pop-up action to better represent the Large Hadron Collider and ATLAS detector.

Fermilab scientists find evidence for significant matter-antimatter asymmetryMay 18, 2010

Scientists from Fermilab’s DZero collaboration announced that they have found evidence for significant violation of matter-antimatter symmetry in the behavior of particles containing bottom quarks beyond what is expected in the current theory, the Standard Model of parti-cle physics.

Looking at the Galaxy Zoo with (gravitational) lensesMay 14, 2010

Can you tell a gravitational lens from a distant spiral galaxy? With an expansion of the Galaxy Zoo citizen-science project, you can try your eye at lens identification.

Read the full text of these stories and more at www.symmetrymagazine.org/blog/june2010

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LHC: the catalog shotMay 6, 2010

My geek confession for today: I love the day the Jameco Electronics catalog arrives in the mail. But to make it even geekier, I was excited to see that the latest cover features a photograph of the construction of the ATLAS detector at the Large Hadron Collider.

Protons not as “strange” as expectedApril 27, 2010

The G-Zero experiment, which measures how much the strange quark contributes to the proton, has found there is a lot less strangeness than previous theo-ries and experiments indicated.

A long-lost object on the moon will help test general relativityApril 26, 2010

In 1971, a Soviet moon lander called Lunokhod 1 sent its last signal back to Earth. Since that time, scientists have been keep-ing an eye out for it but not had any luck. Now the lander has been found, and a simple but important piece of cargo on it is intact.

Dark matter: Can you hear me now?April 16, 2010

Scentists with the COUPP experiment have found that simulated WIMPS—particles of dark matter—make a distinctly different noise when passing through a bubble chamber than imposter particles do. This could make it much easier to identify a particle of real dark matter if and when it arrives.

Giant natural particle accelerator discovered above thundercloudsApril 15, 2010

A lightning researcher at the University of Bath has discov-ered that during thunderstorms, giant natural particle accelera-tors can form 40 km above the surface of the Earth.

Einstein’s theory fights off challengersApril 15, 2010

Two new and independent stud-ies have put Einstein’s General Theory of Relativity to the test like never before. These results, made using NASA’s Chandra X-ray Observatory, show Einstein’s theory is still the best game in town.

Running the world’s biggest particle acceleratorApril 8, 2010

What exactly do the Large Hadron Collider’s operators do to get the collider up and run-ning, and keep it that way?

Just what your iPod needs: a Fermilab rap videoApril 7, 2010

“Rock stars of physics, particle business, smash matter, anti-matter and witness quarks, bottom to top, they don’t stop ‘Where the Higgs at?’ Yo that’s their mark! Go! Go! Go!”

X-band research accelerates at SLACApril 5, 2010

Emerging as a new option for powering linear accelerators, the X-band segment of the electro-magnetic spectrum could have applications in accelerators for physics as well as medicine and industry. It allows cheaper and more compact accelerators.

Top quark motto: Live fast, die youngApril 1, 2010

Most of the subatomic particles made at the Tevatron have a fleeting existence, but it is rare for one to live as briefly as the top quark. DZero scientists have determined that the top quark’s lifetime is just three times 10-25 seconds. This is a mind-bog-glingly tiny number, and there are no good analogies to de- scribe something that ephemeral.

THE MUON GUYSON THE HUNT FOR NEW PHYSICS

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By ANDREA MUSTAiNPHOTOGRAPHy By REiDAR HAHN, FERMiLAB

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AMId A SPRAWl of mysterious equipment in a workroom at Fermi National Accelerator Laboratory,

Gueorgui Velev and Alexander Makarov leaned over an elegant metal box the size of a single file cabinet. Suffused by a warm halo of late-afternoon sunlight, the two men, a physicist and an engineer, had the look of modern-day priests of industry gently handling a beloved reliquary.

Velev lifted the box top, revealing a thin slice of dark-gray ferrite—a ceramic compound used in powerful magnets. Although the ferrite was wired up like an intensive-care patient, for the moment it felt cool and deliciously smooth to the touch.

Velev and Makarov have been testing ferrites like this one for almost a year now, send- ing powerful currents through the compound, pushing the material to its limits. Far from being a relic of something dead, the ferrite is a symbol of resurrection for an experiment that could star in its own soap opera. Attempts to carry out this experiment have died two deaths on two continents over the course of two decades.

Velev and Makarov, along with a host of collaborators, are once again bringing it to life.The experiment’s newest name, in its incarnation at Fermilab, is Mu2e (pronounced

Mew to E), which stands for muon-to-electron conversion; and it is a testament to the strength of the science behind this experiment that physicists are still fighting to do it. Scientists plan to break ground at Fermilab in Batavia, Illinois, in 2013 and begin taking data four years later.

The experiment will search for a phenomenon so incredibly rare that, according to the Standard Model of physics, humans could never build a machine sensitive enough to actually see it. Which is exactly why scientists want to build this experiment. Mu2e is on the hunt for new physics.

Specifically, Mu2e is trying to catch a glimpse of one kind of particle turning into another. The experiment will look for signs of a muon—which is basically an electron’s fatter cousin—converting, in a Cinderella-like transformation, into its more slender and well-known relative.

If a muon does undergo this transformation, the signs will be unmistakable. This fact alone sets Mu2e apart from many other particle physics experiments, where scientists must sort through a huge amount of “background” data that bury the sought-after results in a torrent of distractions. Finding the result you’re looking for can be like picking out a whisper amidst the cacophony of Times Square. In Mu2e, the signal will blare out from the background like a siren.

symmetry | volume 7 | issue 3 | june 2010

From left: Jim Miller, Ron Ray, and Robert Bernstein think the Mu2e experiment may answer one of the fundamental riddles of particle physics.

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CHOREOGRAPHiNG AN iNviSiBLE DANCETo pick up this signal, physicists must build a system of jaw-dropping pre-cision and complexity that is capable of producing 500 million billion muons per year. In a slow-motion, subatomic ballet, it must gently capture these muons within the orbits of aluminum atoms, which will provide the staging ground for the predicted transfiguration. If the Large Hadron Collider is a high-energy particle mosh pit, Mu2e is a delicate and sophis-ticated pas de deux. Orchestrating such minute choreography requires the combined efforts of more than 100 scientists at universities and laboratories around the globe.

Even humanity’s boldest endeavors must endure one painful fact of life: meetings. Surely the Romans held meetings before they built their aque-ducts, and Ernest Shackleton must have met with his crews before setting out on his famed expeditions to Antarctica.

To plan their own undertaking, Mu2e collaborators gather every Thursday in a conference room on the 12th floor of Fermilab’s Wilson Hall.

On a bright morning last February, physicists clad in what seems to be the experiment’s unofficial uniform (subdued sweaters over neat button-downs, jeans, a preponderance of suspenders) drifted in, carrying laptops and clutching coffee cups. Mu2e co-spokesperson Robert Bernstein was already set up at the conference table, laptop open, hurling curses at the LCD projector.

“I am pushing the right button, right? Why isn’t this working?!” he said, wav-ing a remote control toward the ceiling. “I am pushing the right button, right?”

Somebody crawled under the conference table to fiddle with cables, and was soon joined by two more physicists.

“Wait, it just reacted!” said another physicist, peering at the uncooperative machine.

“This is how all meetings begin,” said Ron Ray, the Mu2e project manager, from his post near the front of the room.

“We always think we’re going to start on time, and then we have these technical difficulties,” said Jim Miller, a professor at Boston University and Mu2e’s other co-spokesperson. “And we think we’re going to mount this complicated experiment.”

He was kidding. Mostly.

The Mu2e experiment will use alu-minum atoms to capture muons—heavy, electron-like particles. The muon begins to orbit the nucleus of the atom, just as ordinary elec-trons do. Scientists predict that a tiny fraction of the time a bound muon will change directly into an electron, with no other particles emerging from the decay and fly off into the detector. The signal from this single, energetic electron will blare like a siren against a background of other events.

This is the process we are looking for.This is what we start with.

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THE MEN BEHiND THE MACHiNEBernstein, Ray, and Miller are the three people most intimately involved with Mu2e’s progress.

Ron Ray is the details guy—the one who keeps tabs on the ferrite, along with all the other pieces of the experiment that are in various stages of development at Fermilab and collaborating institutions. As the project manager, it’s his job to make sure Mu2e passes reviews, stays on budget, and doesn’t blow deadlines.

It’s a difficult position with a great deal of responsibility, but one to which Ray is well suited—even though he says physics was always Plan B. The Los Angeles Dodgers clock on his office wall and a photograph of the 1972 Los Angeles Lakers lineup are the only vestiges of Plan A. Until you see Ray himself.

“I wasn’t a nerdy kid. Or at least if I was, I was a secretly nerdy kid,” Ray says. “I did well in school, but I was more interested in sports than anything.” Tall and lean, Ray still looks like he’d be right at home on the basketball court. He played through his freshman year at the University of California, Irvine, but eventually found the pull of physics irresistible. “I kept taking it and I kept liking it—partly because it was a challenge. I like to do hard things,” he says.

Ray was the first person in his family to graduate from college, let alone get a PhD in particle physics. He says his interest in the subject came as a bit of a surprise to his family. “Sports, they understood. I’d play basketball in the driveway with my Dad when I was a kid. But the physics stuff, I don’t think anybody understands where that came from.”

Robert Bernstein’s office is just down the hall. The son of a toll collector and a housewife, Bernstein, like Ray, was the first person in his family to graduate from college. But unlike Ray, he knew from a very young age that he wanted to be a physicist. “I was five years old, and I said to my mother, ‘Why don’t clocks run backwards?’ I didn’t understand why the universe didn’t run backwards in time. And my mother didn’t know, and I said to her, ‘Well, who knows about that?’ And she said, ‘I think physicists know about that.’ And I said, ‘OK, that’s what I’m going to do when I grow up.’”

Such cerebral ambition can make life lonely in high school. Bernstein says it wasn’t until he was an undergrad at the Massachusetts Institute of Technology that he truly felt like he fit in. “I was the biggest nerd that ever existed. And I still am,” he adds. He memorized pi to a thousand digits on a bet one weekend, and sang it to Liszt’s “Hungarian Rhapsody Number Four.” He was the president of the science fiction club. “Talk about nerds!” he says. “I got to meet all these cool guys like Theodore Sturgeon and Arthur C. Clarke.”

While Bernstein talks, he’s rarely far from the enormous whiteboard that covers one office wall. “I like it. It’s huge. I can’t live without it,” he says. He regularly leaps out of his chair to scribble equations and diagrams.

Jim Miller, stationed a few doors up from Bernstein, could be Mu2e’s television news presenter. He has the sonorous voice and discreet bear-ing of a particle-physics Peter Jennings, with a mischievous chuckle that peppers his conversation. Bespectacled, with graying hair, Miller looks every bit the physics professor—which he is, and has been for more than three decades at Boston University. If there is ever a question in your mind about particle physics, Miller can explain the answer.

As a kid growing up in Cleveland, Ohio, Miller says he was like a lot of other science geeks, tinkering away in the garage on motors and electrical things, building radio sets. “When I was very young I wanted to understand things, how they worked,” he says. “Back then I was just struggling to understand things that were already understood,” he adds, laughing. “But now I’m in the lucky position of being among a group of scientists who may be the first to discover something new about the universe.”

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THE FAMiLy REBELPhysicists have been looking for muon-to-electron conversion for decades, almost since the muon’s unexpected discovery in 1936. André de Gouvêa, a theorist at Northwestern University, says that since the muon acts like a massive electron, physicists expected it to behave a certain way. They thought it would break down into a more stable electron and jettison its extra mass in the form of energy. “But they didn’t see this happen,” de Gouvêa says, “so that was a big puzzle.”

In fact, the muon seemed to be following some mysterious new rule, which prevented it from transforming directly into a single electron. This rule became known as flavor conservation, and was eventually adopted into the Standard Model of particles and their interactions. To understand the concept of flavor conservation, one must first understand particle flavor, and that requires a closer look at the muon’s extended family.

The muon belongs to a class of particles called charged leptons. There are three charged leptons—electrons, muons, and taus, all with a negative electric charge, each heavier and more rare than the last. The muon is about 200 times more massive than the electron; the tau is a whopping 3000 times heavier than the electron. At the Charged Lepton family reunion, the electron would be the Hollywood starlet (she’s skinny, she’s famous), the muon would be the more generously built Goth girl, and the tau would be the full-figured opera singer. Each has her own unique qualities, and thus, her own particular flavor.

So why are muon and tau so rare, when their popular cousin seems to be everywhere? It turns out that muon and tau aren’t stable. In the particle world, this means they live only a short time before they decay into lighter particles. In contrast, their slim cousin electron, through some pact with the devil, lives forever.

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The Standard Model of particles and forces includes three charged leptons: electron (e), muon (μ), and tau (τ). Scientists wonder whether these particles can trans-form into each other as the three generations of quarks (u, c, t, d, s, b) and neutrinos (νe, νμ, ντ) do.

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FLOUTiNG THE FLAvOR RULEScientists have observed that particles, like many humans, yearn for stability. So it would make sense that chubby muon would, presto!—shed its extra heft and morph directly into svelte, immortal electron.

In fact, muons do typically decay into electrons that are accompanied by neutrinos—the aloof particles that rarely interact with anything. However, this is not flavor violation; only the direct conversion of a muon to a single electron, with the emittance of nothing else but energy, qualifies, and this has never been seen.

De Gouvêa says the law of flavor conservation “seems to be a fundamental symmetry of nature, and we want to find out why—in particular, because it is a very ad hoc one. It wasn’t necessary for the world to exist. It was just some-thing that happened.”

Physicists have come to the conclusion that the Standard Model, with its ad-hoc flavor conservation policy, does, in fact, allow muons to convert directly to electrons—but only if this happens so rarely that nobody would ever be able to observe it.

However, theories that lie outside the Standard Model, such as super-symmetry, suggest that breaches of this policy—called flavor violation—do happen far more often than the model allows. That’s why physicists believe there is a revolution afoot. If they’re right, observing the muon-to-electron transformation should be well within the reach of Mu2e’s particle detectors. It would be “unmistakable evidence of physics beyond the Standard Model,” Miller says.

When a muon is trapped in an orbit around the nucleus of an aluminum atom (see diagram on page 12), it can decay in several different ways. The Mu2e experiment will look for the extremely rare process in which the muon converts directly to an electron (left). The observation of this process, predicted by new theories such as supersymmetry, would indicate the presence of a new particle or force. The energy of the single electron emerging

from the atom would be exactly 105 mil-lion electronvolts, making it easy to see against a noisy background of more common events. Two of those possible background events are shown here as well. Most of the time a muon decays into a set of three particles: an electron, a neutrino and an antineutrino (center). in this case, the electron will have much less energy than 105 Mev; hence this event is easy to reject as background. But sometimes the electron gets an

extra kick of energy from the nucleus (right). Since particle detectors are unable to see neutrinos and antineu-trinos, the decay could resemble the signal scientists are looking for. if the neutrino and antineutrino happen to have little energy, the electron could even end up with an energy close to 105 Mev, making this decay more dif-ficult to distinguish from the sought-after signal.

Signal Background (A) Background (B)

THE EXPERiMENT THAT WOULD NOT DiERecent discoveries make the case for flavor violation within the charged lepton family even more compelling. Physicists have found that neutrinos—leptons without electric charge—are notorious flavor violators. So far, though, experiments looking for charged lepton flavor violation have come up empty handed. Many physicists believe the technology just hasn’t been good enough.

Mu2e will be about 10,000 times more powerful than the last experiment to look for muon-to-electron conversion in a similar way, SINDRUM II at Switzerland’s Paul Scherrer Institute, which finished taking data in the year 2000.

It will have a sensitivity of 10-17, a fancy way of saying that if only one in 100 million billion muons transforms into an electron, Mu2e will see it. The experiment is able to reach such limits because of advances that had their genesis back in the 1980s, behind the Iron Curtain. In a way, Mu2e was born in the Soviet Union.

In February 1989, the Soviet Journal of Nuclear Physics ran a letter to the editor from physicists Vladimir Lobashev and Rashid Djilkibaev, in which they proposed an experiment that would perform the most thorough search yet for muon-to-electron flavor violation.

Lobashev had dreamed up some creative changes to existing technology, and in 1992, the experiment, named MELC, was given the green light and work began at the Moscow Meson Factory. But by 1995, Djilkibaev says, the experiment shut down, felled by the political and economic crisis gripping a faltering empire.

At around the same time, a physicist and flavor-violation specialist named William Molzon, based at the University of California, Irvine, started looking around for a new experiment to work on. Molzon says he’d heard about Lobashev’s work and was intrigued enough to go to Russia to meet with him. “I actually visited the accelerator,” says Molzon. “It was sort of like a ghost town.”

By 1997, Molzon and his collaborators had a proposal to revive a MELC-based experiment at Brookhaven National Laboratory on Long Island. Their experiment had a new design, a new kind of detector, and a new name: MECO.

R&D got under way in 2001, and MECO was on its way to becoming the most sensitive muon-to-electron conversion experiment ever built. But in 2005, despite glowing reviews from experts, the funding agency pulled the plug. “We were quite far along,” Molzon says. “That was a very sad story.”

One of Molzon’s collaborators on MECO was Jim Miller. As a self- proclaimed “muon guy,” he’d joined the experiment a few years before it was killed. “I thought, well, there go two or three years down the tubes. And for some people it was many more years,” he says.

But those years weren’t a complete loss, because Mu2e is building on the effort put into MECO and its predecessors, Miller says. “Those guys put a lot of design work and thought into this,” he says, “so they didn’t waste their lives, even though some of them may not be around to see the results.”

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THE MOMENT THEy’RE ALL WAiTiNG FORThe magic result all these scientists are after—the one they have been chasing for so many decades—is one simple number: 105.

The Mu2e experiment will use an intense proton beam to produce a huge number of muons. The slowest muons are then captured by powerful electromagnets and pushed, ever so gently, against a sheet of aluminum only about 10 times thicker than the foil in your kitchen cabinet. The negatively charged muons find the positively charged aluminum nuclei irresistible; they are drawn inexorably inward, until the two bodies, muon and nucleus, nestle together in a cozy orbit.

If the muon does perform its nifty transformation into its much smaller electron cousin, physicists know that this electron will wrest free from the aluminum atom’s embrace, and shoot into Mu2e’s particle detector with an energy that is unmistakable: 105 million electronvolts.

This number in the detector would be solid evidence that the muon has transformed, the tell-tale glass slipper the electron leaves behind. More impressively, this Cinderella would be wearing size 17 shoes; if the slipper is there, you’ll see it. And the fairy godmother responsible for the meta-morphosis would be something brand new—a new particle, a new force, a new something that would change our most basic understanding of how the universe works.

For now, Ray, Miller, and Bernstein spend their days focusing on the tem-poral matters at hand—running computer simulations, battling the LCD projec-tor, keeping track of tests that will determine which type of ferrite is best for the specialized electromagnet that will keep Mu2e’s proton beam pristine.

Bernstein seems undaunted by the rather ordinary nature of the day-to-day operations required to bring this massive experiment to fruition.

“I’ll be doing this for a decade,” Bernstein says, “then figure out what to do after that. I’m not gonna retire; they’re gonna pull me out of here feet first.

“Why would I leave here?” he says, grinning. “This is the greatest place in the world.”

The Mu2e Experiment

Muons

Muons (very slow)

Look for 105 Mev electrons

Aluminum atoms capture muons

Magnet captures slow muons and directs them to aluminum target

Particle detectors

Muons decay

Stopping target

Protons from Fermilab accelerator

The proton beam creates pions, which decay into muons and other particles

The Mu2e particle detector is embedded in a series of magnets that create a low-energy beam of muons and steer it into an aluminum target. The process starts (as shown below) where protons from a Fermilab accelerator hit a target and produce pions, which decay into muons and other particles. A magnet steers slow-moving muons to an aluminum-foil target. There the muons go into orbit around the nuclei of aluminum atoms. This should allow muons to convert directly to electrons. The distinctive energy of these electrons, 105 Mev, makes them easy to identify in a set of particle detectors.

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Walk like a physicist, point by point, through three of the displays that highlight scientific and technical milestones from the Large Hadron Collider’s first months of operation.

The LhC DeCoDeD

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Capturing the moment

For every important event in particle physics—such as the record-setting collisions at the Large Hadron Collider that marked the official start of its research program, shown at left—there is a picture that shows at a glance what would take hundreds or thousands of words to explain.

Painted by pixels on computer screens, these images tell scientists what is happening in their machines and document key moments in the lives of the accelerator, its detectors, and the scien-tists who work with them. They come in two types. Status displays show the workings of the accel-erator and its particle detectors, and event displays reveal what happens in a detector when particles collide.

All are made possible by interactive software that physicists can operate from their desktops or laptops nearly anywhere in the world, as well as from remote monitoring centers like the one at Fermi National Accelerator Laboratory in Illinois, which monitors the CMS detector. Researchers can call up many different forms of data, super-impose them on one anther to gain deeper insights, and rotate images to get a better view of the fleeting, messy aftermath of a particle collision. They scan for patterns that may reveal new phys-ics or glitches in software or equipment. When they go off duty, they can hand off monitoring chores to colleagues in the next time zone over.

When the accelerator reaches a milestone or interesting physics results pop up in a detector, specialists create a version of the computer dis-play that shows what happened and highlights particular features of interest. It may be cropped, rotated, or rendered in different colors than the displays physicists use on a daily basis. It may take just an hour to put together the first draft; the process of refining an event display until all 2000-3000 members of an experimental collaboration are pleased with the result takes a whole lot longer. Yet that’s what it takes to get an event display approved for release to the rest of the scientific community and the public.

Today’s event displays are the product of decades of evolution. For most of the history of particle physics, scientists recorded and displayed particle interactions by taking photographs. They shot photos of the tracks particles left in a cloud chamber or bubble trails they left in a bubble chamber, and measured the features in those pho-tos using protractors and other hand tools.

Joseph Perl of SLAC National Accelerator Laboratory remembers watching his father, Martin Perl, who later would win the Nobel Prize,

conduct experiments with a spark chamber at the lab. When a particle hit the chamber’s 12-foot-tall metal plates, “A bolt of lightning would flash and a camera would capture it, and you would actually have this crashing sound,” he says with relish. Joseph Perl went on to develop event displays for four SLAC experiments over the past 20 years.

In 1968, the invention of the multi-wire propor-tional chamber at CERN allowed physicists to hook their detectors directly up to computers so they could collect and analyze data without scan-ning photos. This breakthrough nudged particle physics into the electronic age and eventually led to computerized displays.

Today’s electronic depiction of a particle event is “a diagram rather than a photograph,” Perl says. “It’s like a good subway map; it’s highly formalized to pack as much information as you can into that space. The trick with the software is to make it so you can generate this thing very quickly on the fly for anything that people would want to study. The standard is that you should be able to do that from any desktop anywhere. I want it to work on the cheap com-puter that some grad student has at home, late at night.”

In the next few pages we’ll walk you through displays from the Large Hadron Collider control room and from two of its four major experiments, ATLAS and CMS.

Daisy yuhas, Katie yurkewicz, and Glennda Chui contributed to this article, which is based on information from a series of articles in the CERN Bulletin and symmetry breaking. Links to those articles and other information are at http://www.symmetrymagazine.org/LHC_display/

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LHC page 1: Indicates which status display is shown. Page 1 shows the overall status of the collider; eight other LHC-related pages can be displayed, as well as pages for other CERN accelerators.

Mode of operation: PROTON PHYSICS indicates the machine mode; STABLE BEAMS indicates the beam mode.

Fill: An archiving number that increases every time a new beam is injected into the LHC.

E: The energy of each beam, 3500 billion electronvolts, or GeV.

Date and local time: At top right are the date and local time in Central European Summer Time.

Energy and intensities: The energy and intensities of the two proton beams. B1 (blue) and B2 (red).

The chart: Plots the beam’s intensity over time. LHC operators can show any image or text of their choosing in this space, or leave it blank.

Comments: A space for LHC operators to express themselves. Here the operator is celebrating the first day of collisions with stable 7 TeV beams.

BiS status and SMP flag: In the lower right corner, the Beam Interlock System (BIS) and Safe Machine Parameter (SMP) flags indicate the status of a number of accelerator settings that can be critical for the scientists running the LHC and its experiments.

LHC: Page 1

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Page 1: A window into the heart of the big machine

The Large Hadron Collider, or LHC, is a 27-kilo-meter ring beneath the Swiss-French border where two beams of protons going in opposite directions are accelerated to nearly the speed of light. They collide in the hearts of four detec-tors—enormous, multilayered machines studded around the ring—and give off sprays of particles.

Each detector is composed of sub-detectors that measure specific properties of certain types of particle. By combining all of this information, scientists determine the types and quantities of particles produced in the collision.

The status display on this page, known as Page 1, shows the overall status of the collider. It changes throughout the day with the changing activity of the machine—whether it is preparing for beam, testing an accelerator system, or providing experimental collisions—and includes comments from LHC operators.

Let’s start with the mode of operation. PROTON PHYSICS indicates the “machine mode”; in this status display, collisions are being provided to the experiments for physics studies. STABLE BEAMS indicates the “beam mode”; in this case two proton beams are circulating and colliding, and accelerator operators will make no further major adjustments to the beams. This particular display was captured less than one hour after the LHC collided its first protons at an energy of 7 trillion electronvolts, or TeV, in the process setting a new world record and launching the LHC’s research program.

Above this title are three sets of numbers. Fill is an archiving number that increases every time a new beam is injected into the LHC. E is the energy of each beam, 3500 billion electronvolts, or GeV. This is the maximum energy for the LHC’s current run, which will last until late 2011. At top right are the date and local time: March 30, 2010, at 1:47 p.m. Central European Summer Time.

The line below the title shows the energy and intensities of the two proton beams, called B1 (blue) and B2 (red). The graph below plots the beams’ intensities over time. You can see that they were pretty much identical over the previous two hours, drooping slightly toward the end. The slight drop was caused by the insertion of collima-tors—beam cleaners—into their normal positions before the beams were declared stable. In the comments section at lower left, one of the oper-ators has written, “Stable beams!”

In the lower right corner, the Beam Interlock System (BIS) and Safe Machine Parameter (SMP) flags indicate the status of a number of accelerator settings that can be critical for the scientists run-ning the LHC and its experiments. Green means “true” and red means “false.”

Here’s what each flag means:

Link Status of Beam Permits: Indicates whether the two beam permits are linked. If they are linked, the dumping of one beam will cause the dumping of the other.

Global Beam Permit: Beam is allowed into the LHC.

Setup Beam: The intensity of the beam is below a certain level, minimizing the risk to the accelerator.

Beam Presence: Beam is circulating in the LHC.

Moveable Devices Allowed in: Some of the parts that make up the LHC detectors sit very close to the particle beam, where they can be harmed by unstable beams. This flag indicates whether these detectors, which include the TOTEM experiment’s “Roman pots” and LHCb’s vertex detectors, may be moved into position next to the beam line.

Stable Beams: Beams are stably colliding; no major adjustments to the beams can be performed by the accelerator operators. This tells the scien-tists running the LHC experiments that they can turn on even the most sensitive parts of their detectors.

PM Status B1 and B2: The PM, or Post-Mortem, system provides a record of what happened in the accelerator during an event such as a magnet quench or beam abort, so LHC scientists and technicians can get the whole picture. sy

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Beam’s eye view: Looking straight through the central collision point.

Side view: Shows the three main regions of the detector. The beams run horizontally through the middle.

Three-dimensional perspective: Here the beam line runs from upper left to lower right and can be rotated.

Collision point: Marks the spot where protons from the two beams smash into each other.

Beam line: The arrows show the paths of the beams. One travels right to left, the other left to right.

Silicon tracker: The first layer of the detector tracks particles’ momentums and paths.

Calorimeters: Record the energies of electrons, photons, and hadrons.

Muon chambers: The outermost component of the detector records information about muons.

Muons: Physicists studying this display have hypothesized that this event produced two muons, whose trails are marked in red.

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CMS: A dimuon trophy

Looking at the title and text on this event display from the Compact Muon Solenoid (CMS) experi-ment, we can see that this event occurred on December 14, 2009 at 4:46 a.m. Central European Time. It was the 5,686,693rd event recorded in Run 124120. A run is a period of continuous oper-ation in a given part of the detector. Physicists use run and event numbers to catalog their data. The run number will increase throughout the life of the detector; the event number resets to zero at the start of each run.

The fourth line tells you that the energy level of the collision was 2.36 trillion electron volts (TeV).

Event displays are divided into multiple screens that view the split second of the collision and the resulting spray of particles in different ways and from different angles. This event display includes a beam’s eye view, looking straight through the central collision point; the view from the side, which shows the beams entering from left and right, colliding, and spraying parti-cle debris through the three main regions of the CMS detector; and a 3D perspective that can be rotated and examined from all sides. The 3D view shows the beam running diagonally from the upper left to lower right of the screen.

Looking at the side view, you can see the paths of the proton beams entering and leaving the detector. One is traveling from left to right, the other from right to left.

The collision point, which physicists call the interaction point, is the exact spot where two particles collide. It occurs within a broader area called the interaction region, where the two beams cross. Despite all efforts to pack the billions of protons in a beam into dense bunches, and thus maximize the number of collisions, the pro-tons are so tiny and spaced just far enough apart that very few of them smack into each other head-on. Some just bump or nudge each other and the vast majority pass without interacting at all, like people in a crowded pedestrian crossing.

When a collision does take place, the result-ing spray of particle debris flies off through the detector. Its layers are cleverly arranged to identify key properties of these particles—their paths, energies, masses, charges, and so on—and sort them into smaller and smaller bins, metaphori-cally speaking, until each one has been identified as an electron, hadron, muon, or photon of light.

In CMS, the first thing the particles encounter is the silicon tracker, which is best seen outlined in green on screens A and B.

The tracker sits in a magnetic field that curves the paths of particles traveling through. This affects only charged particles, such as muons, electrons, and charged hadrons; the rest keep going straight.

The degree of curvature reveals the particle’s momentum. The direction of the curvature—clock-wise or counter-clockwise—indicates positive or negative charge. Since the curve may bend in some directions but not in others, it’s important to see it from multiple vantage points.

The tracker reconstructs the movements of charged particles point by point; those points appear as yellow dots. When we connect the dots we see the particle paths, represented here by red and green lines.

Next come the calorimeters, which stop cer-tain particles and record the energy they deposit. This allows scientists to determine their mass.

First the particles hit the electromagnetic calorimeter, or ECal, which mostly records the energies of electrons and photons; it’s repre-sented by a red bar. Other particles continue to the hadronic calorimeter, or HCal, which traps hadrons and measures their energies; it’s shown as a blue bar. The heights of the bars indicate the amount of energy deposited.

Finally, the remaining particles enter the third and outermost layers of the detector, the muon chambers. These show up on screen B as red blocks above and below the detector and blue blocks on either side; chambers that have recorded a muon hit are highlighted in red.

This particular event display shows a dimuon event, the production of two muons in a collision; their paths are shown as thin red lines on each screen. How can we be sure they’re muons? Their tracks in the silicon tracker show they are charged particles that flew out from the collision in a partic-ular direction and with a specific momentum. The energy they left in the calorimeters reveals their mass. And their passage through the muon cham-bers confirmed their IDs. Of course the scientists can’t claim to see dimuon production based on one event alone; instead they wait until a number of events accumulate and analysis shows that the sighting was not a fluke. sy

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ATLAS: Detector from the inside

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Side view: Gives a good picture of the beamline and collision point.

Beam’s eye view: Seen from the point of view of an incoming beam

Lego plot: Shows energy deposited by particles in the liquid argon and tile calorimeters.

Collision point: Where the proton beams collided at a combined energy of 2.36 TeV.

Beam line: The arrows show the paths of the beams. One travels right to left, the other left to right.

Tracking detectors: Measure the momentums of charged particles.

Central solenoid magnet: Bends the paths of charged particles as they pass through the tracker.

Liquid argon calorimeter: Measures the energies of electromagnetic particles.

Tile calorimeter: Measures the energies of hadronic particles.

Muon spectrometer: Records the passage of muon particles.

The energy deposited by the jet in the calorimeters: Shown in all three views.

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ATLAS: Powerful jets

Dimuon events are one of a number of familiar phenomena seen by the LHC experiments dur-ing the collider’s first few months of operation. As of May 2010, the list included energetic muons; events in which W and Z bosons, first discovered at CERN in 1983, may have been created; and Beauty particles, which combine one bottom quark and one quark of a different type.

Physicists call these “trophies.” While they don’t break new ground, they are exciting milestones for the thousands of scientists working on the experiments, because they confirm that the detectors are working as they should.

This image from the ATLAS event display shows another trophy: the production of jets.

Jets are sprays of particles that are produced only in violent, head-on proton collisions—the type of collision most likely to produce heavy new parti-cles. So physicists expect to see jets in the signa-tures of almost every interesting collision at the LHC. The yellow marks that are circled in white represent energy deposited by jets in the detector.

In this case the protons collided at a com-bined energy of 2.36 electronvolts, or TeV. This is the same collision energy as in the CMS event display, and in fact the two events took place just 16 minutes apart on Dec. 14, 2009, a time when collision energies were being gradually ramped up following a one-year shutdown for repair and refurbishment. This was the highest collision energy that could be safely achieved, given the tests that had been completed at that point.

Why is collision energy important? It has to do with Einstein’s famous equation, E=mc2, which says matter and energy are equivalent. When particles collide, their mass instantly converts to energy. Then all the energy released by the collision turns back into particles. The higher the collision’s energy, the heavier the particles it can produce. Scientists expect heavy, exotic, never-before-seen particles to come out of the record-setting collision energies at the LHC.

Three views of this particular collision are shown. One looks at the ATLAS detector from the side; another takes a beam’s eye view. All the information collected by ATLAS’s detector sub-systems is projected onto these slices, translating a three-dimensional event into two dimensions. The third view shows information from just two sub-detectors, the calorimeters. It’s called a Lego plot because it stacks the amounts of energy the calorimeters collected as if they were LEGO bricks. This gives physicists a quick impression

of how much energy was carried away from the collision by a particle or jet.

As with CMS, the event display shows the collision point from two directions, and the side view shows the paths of the proton beams entering and leaving the detector. Particles go through these sub-detectors in the same sequence.

First, the three tracking detectors measure the momentums and determine the charges of charged particles.

The pixel detector sits directly above and below the collision point in the side view and surrounds the collision point in the head-on view. The semi-conductor tracker is a bit farther from the collision point. In both of these trackers, the passage of a particle is indicated by a colored square. Gray squares show activity that, after more analysis, was determined not to be of interest. Black squares indicate no activity in that area of the detector. The transition radiation tracker is in purple.

Particles that registered in all three tracking detectors are shown as colored lines radiating from the collision point.

Next is the central solenoid magnet, in green. It curves the paths of particles as they pass through the tracking detectors, as seen in the side view. This is one of two large magnet systems in ATLAS; the second, much larger one, called the toroid magnet system, is not shown here.

On to the liquid argon calorimeter, in gray, which measures the energies of electromagnetic particles such as electrons and photons. The amounts of energy these particles deposit are shown as yellow rectangles.

Electrons can be distinguished from photons because they are charged particles that leave tracks in the tracking detectors before dumping energy in the liquid argon calorimeter. Photons, which have no charge, don’t leave tracks.

The tile calorimeter, in red, measures the ener-gies of hadronic particles such as protons and neutrons. Energy deposits are again indicated by yellow rectangles.

Protons can be distinguished from neutrons because they are charged particles, and leave tracks in the trackers. The neutral neutrons do not.

Finally the remaining particles hit the muon spectrometer. Since this collision produced no muons, only part of this spectrometer is shown.

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Text by Lizzie Wade & photos by Nick Russell

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in the summer of 1928, the young Ernest O. Lawrence set out across America in a Flying Cloud coupe to begin his new life at the University of California, Berkeley. Eighty-one years later, a writer and a photographer took a road trip to visit the legacy of this accelerator-physics pioneer: American Big Science.

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Every good cross-country road trip needs a theme. Sure, you can drive across the United States in three days flat, heading in a straight line on impersonal interstates and stopping at the occasional Waffle House for sustenance. But that doesn’t do justice to the great American tradition of the road trip, heading from sea to shining sea with the windows down and the radio on. From On the Road to Easy Rider, we’ve learned that the destination isn’t the point—it’s how you get there that counts.

So when my boyfriend Nick Russell and I decided to drive from New York City to Los Angeles last summer, we weighed various options for our theme: The always-classic National Parks? The quirkier tour of Elvis museums? Major cities? Small towns? Desert, mountains, prairie?

Uninspired, we threw out ideas for stops along the way. Marfa, Texas—good art, family friends, and UFO lights in the desert. Pueblo, Colorado—the Rocky Mountains, a friend’s parents, and Casa Bonita, a cross between a Mexican restaurant and Disneyland. Petersburg, Kentucky—the Creation Museum, devoted to disproving evolution, which we ultimately decided was not for us. And then we remembered Chicago, Illinois—a cousin with a spare bedroom and Fermi National Accelerator Laboratory, where I’d worked as a science-writing intern for a summer in college. The idea snow-balled from there, and soon our itinerary included visits to eight Department of Energy national laboratories (Brookhaven, Oak Ridge, Fermilab, Argonne, Los Alamos, Berkeley, Livermore, and SLAC), one NASA lab (the Jet Propulsion Laboratory), one gigantic radio telescope (the Very Large Array), and one ghost lab in East Texas (the abandoned site of the Superconducting Super Collider).

Big Science through human eyesOur lab-to-lab trek meandered all over the country, taking us through rolling green hills in Tennessee, a flash flood in Indiana, misty forests in Arkansas, the wizened desert of West Texas, and the winding California coast. But the route also presented some challenges: it zigzagged wildly (those rolling hills in Tennessee were beautiful, but I’m not sure we needed to see them twice in one week) and the logistics of arriving at each lab on a working weekday meant we often drove until well into the night. Blame it on fatigue, but we mistook a power plant for the Oak Ridge lab. One late night we wondered if we were about to be abducted by aliens as we drove through a seemingly endless field of red lights flashing in unison in the middle of Texas (we never did figure out what they were). Eventually, we even started to appreciate the idea of a drive-through Starbucks.

The trip was as much a physical experience as an intellectual one. Just as there’s no way to grasp the amount of empty space in the United States until you’ve driven through it, there’s no way to comprehend how big Big Science is until you stand on a plateau in New Mexico trying to catch sight of the most distant satellite dish in the Very Large Array, which at its widest point would span Washington, DC; or stand under the recently finished National Ignition Facility at Lawrence Livermore National Lab, which looks like a prototype for the Star Wars Death Star, right down to the intersecting laser beams.

Driving continuously from one lab to the next also humanized Big Science in surprising ways. We had to sleep somewhere, and that often turned out to be at a lab employee’s house. In the space of a few hours, Fermilab’s Kurt Riesselmann shifted from giving us a tour of the latest developments in technology for the proposed International Linear Collider to explaining how his washing machine worked so we could do some much-needed laundry. At Brookhaven we bunked with the run coordinator for the Relativistic Heavy Ion Collider, John Haggerty, who didn’t even make it home because a surprise thunderstorm threatened the lab’s power supply.

(Above) One of two laser bays at Livermore’s National Ignition Facility, where 192 powerful lasers are focused onto a target the size of a pin in an attempt to cause nuclear fusion. (Far right) Nick and Lizzie at Fermilab; photo by Kurt Riesselmann. (Lower right) Los Alamos’s proton radiography imager uses protons instead of pho-tons to make detailed internal images of small explosions, allowing scientists to test aging nuclear weapons without detonating them.

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(Top) Enormous scale was the theme of our trip, but nothing compared with the city-sized Very Large Array, stretching off in three directions into the vast New Mexico desert.

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(Top) History is everywhere at the national labs. At Argonne, we almost drove right past the building that formerly housed the 1950s-era Chicago Pile 5 reactor.

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Extra-ordinary scenesNext on the road trip survival list was eating, frequently in lab cafeterias. Lunch was often the most informative part of a visit, with a wide variety of people dropping by our table to say hi to our scientist tour guides, breaking the façade of experimental rivalries and giving us a sense of the camaraderie in each lab. The social dynamics often seemed familiar and even mundane. Like all large organizations, national laboratories have their share of office politics, gossip, and administrative struggles—and even cubicles, whether they are located in high rises, in trailers, or between the arms of a synchrotron.

But just when things started to look too ordinary, we spotted the building at Argonne that housed the Chicago Pile 5 reactor, last in Enrico Fermi’s famous line of Chicago-Pile reactors; remembered that another version of the rover we were examining at the Jet Propulsion Laboratory was exploring Mars at that very moment; spotted an old gas canister labeled “Property of the Atomic Energy Commission” at SLAC; or encountered one of the discoverers of dark energy in a hallway at Berkeley Lab.

Even the machines themselves have distinct personalities. There is always troubleshooting to be done on even the most state-of-the-art equip-ment, and many of the machines at the national labs are far from new, having been repaired and upgraded dozens of times since they first came on line. Oak Ridge, for example, has been using the same cyclotron to accelerate particles since 1962. Parts of Brookhaven’s PHENIX detector are plastered with packing tape. Detector computer rooms brim with tangled cables. And many of the sensitive physics machines we saw were at least partially covered in aluminum foil.

Yet if this image seems chaotic, it showcases the deepest truth we encoun-tered this summer: American experimental physics remains deeply resourceful and hands-on. When a part breaks, it is as likely to be fixed as replaced. When a detector isn’t functioning as well as it could, someone is likely to step up and figure out a way to make it better. And when a machine becomes obso-lete, it stands a good chance of being incorporated into the next big project.

The road to the 21st centuryHigh-energy physics machines may have long life spans, but high-energy physics is just a century old, starting with Ernest Rutherford’s discovery of the atomic nucleus in 1911. Since much of the field developed within living memory, the history is often still visible, or even in use. Ernest O. Lawrence’s first cyclotron, small enough to hold in your hand, is on permanent display at UC Berkeley’s public science center, the Lawrence Hall of Science. The magnet for his last cyclotron can be found right where he left it at the Rad Lab (now Lawrence Berkeley National Laboratory), where it supports a giant crane in the lab’s synchrotron, the Advanced Light Source.

American high-energy physics came into its own when World War II’s Manhattan Project sequestered many of the world’s best physicists in the mountains of New Mexico to work on the atomic bomb. For an effort so classified that it justified building the secret “atomic cities” of Los Alamos, New Mexico, and Oak Ridge, Tennessee, the Manhattan Project’s history is surprisingly accessible today. Even Oak Ridge’s graphite reactor—one of the world’s first nuclear reactors, used to perform early nuclear research and process plutonium for the first atomic bombs—was simply powered down after a flood in 1963 and kept intact for visitors to explore.

Although the town of Los Alamos is now a thriving community, it’s hard to visit without feeling unease at the weight of its history. Besides the mas-sive lab itself, the town houses a small museum full of Manhattan Project arti-facts and Cold War paraphernalia, as well as the lab-run Bradbury Science Museum where, among many other displays, you can see scale models of the two early bomb designs and browse the ID photos of the lab’s Manhattan Project residents. The young Hans Bethe, Robert Oppenheimer, Edward Teller—and the very young Richard Feynman—are particular standouts. A book-store adjacent to the science museum even sells blueprints of Little Boy and Fat Man, the atomic bombs dropped on Hiroshima and Nagasaki in 1945.

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(Above left) Scientists in the control room for Brookhaven’s Relativistic Heavy Ion Collider attempt to fix a prob-lem that had shut the collider down for several hours. (Above right) The view from Oak Ridge’s cafeteria includes a waterfall and a building that houses one of the world’s most powerful Van de Graaf generators. (Left) At SLAC, we stumbled across gas tanks labeled by the Atomic Energy Commission, which ceased to exist in 1974. (Far left) When NASA’s Spirit rover got stuck in Martian sand, Jet Propulsion Laboratory scientists used their spare rover to figure out how to get it out. Sadly, Spirit had to be redesignated as a Stationary Research Platform on Day 2157 of its 90-day mission.

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Ghosts of physics pastAfter the Manhattan Project ended, the government continued its strong support of high-energy physics research. As with the Space Race, beating the Soviets to the frontiers of physics was considered an integral part of national security and pride, even when the discoveries had no military application whatsoever. Former Fermilab director John Peoples told us that the US government was willing to supply its scientists with the resources needed to meet this end. He recalled that when Fermilab’s founding director, Robert Wilson, asked Congress for the money to build the laboratory, they gave him $90 million and told him to come back if he needed more. Construction was completed ahead of time and under budget, in part because Wilson himself designed many of the more imaginative buildings, which still stand as testaments to a particularly dynamic era in American particle physics.

That era came to an end in 1993 with the cancellation of the Superconducting Super Collider, whose ghost still haunts high-energy phys-ics. With a 54-mile circumference, the underground tunnels of the SSC would have encircled an area comparable to the city of Dallas and surrounded the small city of Waxahachie, Texas. It would have had nearly three times the power of Europe’s new Large Hadron Collider, now the world’s most powerful particle accelerator, and would have almost certainly revealed the Higgs boson (if it exists) along with many other results that physicists are still waiting for today. But with the end of the Cold War, the race with the Soviets lost its urgency and high-energy physics could no longer assume a privileged place among government science programs. When the SSC’s projected cost soared billions of dollars over budget, Congress pulled the plug—leaving several buildings and 14 miles of tunnel abandoned in rural East Texas.

Although officially owned by a Texas investment company, these days the SSC is a ghost lab. A cluster of warehouses, empty except for the ceiling cranes still waiting to assemble a detector, loom over a few holes in the ground that lead down to the water-filled accelerator tunnel. The only signs that we weren’t the first visitors in almost 20 years were an abandoned couch in a driveway, some ghostly footprints on the carpet inside, a half-empty Frappuccino bottle in an office cabinet, and, most crucially, the busted window pane we used to sneak into the main building.

New opportunitiesThe SSC certainly represents a missed opportunity in the history of high-energy physics, but its cancellation hasn’t stopped the field from moving forward on many different fronts. Fermilab, now the nation’s only dedicated particle-physics lab, is expanding its focus to include a high-intensity neutrino physics program, even while the high-energy Tevatron collider con-tinues to search for the Higgs boson and other exciting new physics. Interdisciplinary fields like photon science are drawing unprecedented amounts of attention at several national labs, along with supercomputing and energy science. Physicists continue to develop technologies for the accelerators of the future, which may include schemes to make Big Science smaller with breakthroughs that could shrink giant particle acceler-ators to tabletop size. And thousands of US physicists are collaborating with researchers from all over the world on experiments at CERN’s Large Hadron Collider.

Faced with all these new opportunities, American Big Science must continually ask itself the same question we confronted as we pondered Google Maps’ directions: where do we go from here?

For more pictures and an in-depth look at the science going on at each lab we visited, check out our blog: summerofscience.wordpress.com

(Above left) Lizzie overlooks the ceiling crane that scientists would have used to build components for the Superconducting Super Collider if the project hadn’t been cancelled in 1993. (Above right) Part of Ernest Lawrence’s last, biggest cyclotron is still housed in his Rad Lab—though today the building is home to Berkeley Lab’s Advanced Light Source, and the magnet yoke of the cyclotron is all that’s left, supporting a massive crane. (Right) A com-menter on our blog made these eerie footprints inside the abandoned SSC magnet assembly building. (Far right) Microwave cavities for SLAC’s two-mile linear accelerator extend off into the dis-tance. Today, the linac powers an X-ray laser.

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(Top) Robert Wilson’s eccentric design tastes help make Fermilab unique. In addition to power poles shaped like the Greek letter π, the lab has more than its share of strangely shaped orange and blue structures.

day in the life: joe frisch

Text by Marissa CevallosPhotography by Bradley Plummer

Every weekday at 11:45, Joe Frisch pulls himself away from answering emails and strides off the SLAC National Accelerator Laboratory campus for a fast-paced, two-mile-round-trip “Death March” with a handful of fellow physicists. They cut through parking lots and squeeze past metal fences to a street called Alameda de Las Pulgas, or Boulevard of the Fleas, and pause to decide what to grab for lunch: Mexican food, pizza, or pub grub?

If it’s pizza, “someone declares themselves Pizza Dictator,” Frisch says. The dictator decrees the pizza toppings, and the rest of the group has 60 seconds to come up with a better list of ingredients. One good strategy is to wait as long as possible—counting to 59 seconds in your head—to stage a coup for pizza power. But appointing yourself dictator is even better, Frisch says, because your choices will often go uncontested.

His playful strategizing and obsession with numbers might be why his colleagues call him one of the best accelerator scientists at SLAC’s giant X-ray laser, the Linac Coherent Light Source.

Accelerator scientists play a role that’s largely invisible to the public, but crucial for controlling instruments such as the LCLS, the brightest X-ray laser ever built. It’s seen as an exciting new tool for probing individual protein molecules, as well as observing super-hot and high-pressure materials like those in the core of a planet. While most of the press attention goes to the experi-ments that happen at these X-ray hubs and their high-profile results, roughly 150 accelerator physi-cists and operators work around the clock to keep the laser and other SLAC instruments aligned and running. It’s a ship sailing 24 hours a day; when the boat is on course, you hardly notice the crew.

If there’s anyone who can keep up with SLAC’s quick-paced lasers, it’s Frisch, who thinks, talks, and walks just a bit faster than he can credit to his three cups of coffee a day. On the Death March, he has to remember to look over his shoul-der and wait for the rest of the group to catch up. In an 8 a.m. meeting where sleepy-eyed physicists get updates on how the laser behaved through the night, Frisch peppers presenters with questions. Dressed in a blue-striped collared shirt and black

jeans, he crosses and uncrosses his legs, twiddles his fingers, and fidgets with a salt-and-pepper beard that looks too grandfatherly for a face that is still boyish at age 47.

On this particular Wednesday, the beam is turned off for 24 hours so scientists can enter and fix any broken parts. That means the minute Frisch walks into the LCLS control room, people flock to him with questions, and he’s moving in a flurry from computer to computer to a series of engineers with clipboards.

Today they’re switching out a laser system that shaped the beam into a rectangle, for a simpler system that lets the laser take its desired circular shape. But the move might inadvertently bump up the beam’s emittance—a measure of how small a space the beam can pack the speeding electrons into. The lower the emittance, the brighter the laser beam. Frisch is concerned the switch might take longer than a day. He’s swapped out laser systems before, and lots of things can go wrong with the optics that have to fine-tune a beam to a point much smaller than a speck of dust. At the meeting, he asks a col-league what time the swap will happen. He wants to be prepared for a call if anything goes wrong.

“He knows the accelerator systems,” says Axel Brachmann, a colleague a few seats away at the morning meeting. “He understands them better than most people.”

Frisch has two jobs: designing accelerator parts that test how well the laser beam is behaving, and operating the accelerator during shifts. This week, he’s the program deputy, a position he dubs the Officer of the Watch, like the temporary captain on a warship. “I’m on call all the time,” he says, after fielding a phone call from an operator at the main control room in the afternoon, pacing his small office and twisting the phone’s springy cord. “I’m the fix-it guy.” He’s used to midnight emergency phone calls from frantic operators.

Frisch says he was attracted to lasers as an undergraduate at the California Institute of Technology in the early 1980s, when the gravita-tional wave detector LIGO, which uses lasers to detect tiny changes in gravitational fields, was being conceived. He got his PhD in physics at Stanford University and took a staff job at SLAC in 1990.

“I always had a bit of an engineering bent,” says Frisch, who often flies his shared 1967 Beechcraft Bonanza commuter plane to Oregon on weekends to hike and scope out volcanoes. The only wall decorations in his office, aside from three shelves of physics textbooks and a Dilbert comic strip, are framed photos of snow-covered mountains rising above clear blue lakes.

Frisch bristles at the job title “accelerator

Go, man, go! Running the world’s most

powerful X-ray laser requires a special intensity

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day in the life: joe frisch

physicist.” Titles aren’t relevant here when so many people are crossing into new areas to solve problems on the LCLS, he says; if any-thing, he should be called an accelerator engi-neer. “Building an accelerator involves gadgets and wires and bulbs,” Frisch says. “It’s like building an airplane. You start from an existing design, which has things like wings and tails that you know, from physical principles, gener-ate lift. Then you ask, what makes it fly better? It’s both physics and engineering.”

Because accelerator scientists are not under pressure to publish results, Frisch says they can have frank discussions about how to solve problems. Everyone contributes, and no one person can claim to have made the accelerator work, unlike science in an academic setting where scientists race to publish first.

The job keeps him busy—too busy to have children, Frisch admits. He married his college sweetheart, an engineering student who lived down the hall from him at Caltech. She started out in architecture, but is now a defense con-tractor with the military—“She’s either making targets or weapons,” Frisch jokes.

Both work hard and play hard, the unofficial creed of their alma mater in Pasadena. They use vacation time to travel to China, Italy, South

America, and New Zealand. But at SLAC, Frisch’s work day stretches from early morning until late at night.

On this particular Wednesday, Frisch stays late. With the day’s trouble-shooting over, he joins the other scientists at LCLS to take the new laser equipment for a test drive. At 8 p.m., the beam turns on. By 10 p.m., there is a sense of excitement among the physicists in the control room—at least “as much excitement as people who’d been there for 14 hours could muster,” Frisch says. To their surprise, the switch to the new system has not increased the laser beam’s emittance; in fact, it chopped emittance by 20 percent.

“I think it’s the best we’ve ever done,” Frisch says. “It’s not often that you make a change like that and it’s a win in all ways. Usually there’s a trade-off.”

Improvements like these may not excite the public as much as the biological insights scientists will reap by shining X-rays on protein or watch-ing movies of how plants churn out energy during photosynthesis. Lots of small steps, however, are what make big projects like the $420 million X-ray laser successful, and what satisfy Frisch at the end of the day.

“I’m happy when LCLS works,” Frisch says, “espe-cially if it’s because of something I did.”

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gallery: julian voss-andreae gallery: john zaklikowski

From junked part to detector artBy Kelen Tuttle

For nearly 15 years, artist John Zaklikowski col-lected every computer, telephone, answering machine, stereo, and remote control that passed through his hands. He enjoyed taking the elec-tronics apart, but wasn’t always as good at putting things back together. And so he collected bits and pieces, saving the parts he liked—circuit boards, hard drives, video cards—until he had quite a stash.

“It was always in the back of my mind that I’d make a series of artworks that would incorpo-rate some of these things,” he said on a recent afternoon in his San Francisco studio. “And finally, about three or four years ago, I thought, ‘Just throw this shit out, already, or do something with it.’”

Do something with it he did. Zaklikowski used every last mother board, cell phone and floppy disk—and an array of low-tech goods ranging from old-fashioned telephone bells to a kitchen-sink strainer—to make an artwork, Brainiac, six feet tall and six feet wide. He began with a rigid plywood armature and used screws to attach hundreds of components. A thick blue ring made of wax mixed with pigment added coherence to the intricate result, a juxtaposition of high and low tech.

Zaklikowski was pleased, and decided he needed to explore the unusual medium of electri-cal components further. By then, what had taken him so many years to gather was gone; he had no components left. But he soon discovered that the best place to buy unwanted electronics is eBay, where hundreds of mom-and-pop shops across the country sell obsolete equipment.

“This stuff turns over very rapidly; the hard drives aren’t big enough or the motherboards don’t

“i’m not a physicist. i don’t have an engineering background. But i am intrigued with the symmetry, scale, and complexity of particle- physics detectors.”

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support the new hardware,” Zaklikowski says. “So I’m competing with the gold reclaimers who will pull precious metals off this stuff.”

Over the past several years, Zaklikowski has spent nearly all of his savings on the circuitry and electrical components he used to create nearly a dozen works, most of them modeled on large-scale particle physics experiments.

“I’m not a physicist. I don’t have an engineering background; I don’t have a computer tech back-ground. But I am intrigued with the symmetry, scale, and complexity of particle-physics detectors,” he says, “and also with particle physicists’ role in the human endeavor to understand the world that we are in. This is something that physicists and visual artists share—a desire to make sense of the world.”

One such work, Collider Detector at Fermilab, is an elaborate replica of a detector at Fermi National Accelerator Laboratory’s Tevatron collider.

In fact, it’s genuinely difficult to distinguish a photograph of CDF from a photograph of Zaklikowski’s version (above). But as you step closer to Collider Detector at Fermilab, its unique but equally complex nature becomes clear.

One of the detector’s many onion layers is made of shiny hard drives, the next of circuitry and hard disks. Dotting one layer is a series of computer keys, spelling out gibberish every-where but in the upper-right quadrant, where

From left to rightLarge Hadron Collider, 200984 x 80 x 25 inchesPrimarily based on the Compact Muon Solenoid.

Stanford vacuum Chamber, 2010 104 x 96 x 8 inchesStainless steel, brass, more than 70 feet of copper tubing, 200 vac-uum tubes, 18 security cameras and two dozen anti-shock pads.

Collider Detector at Fermilab, 200872 x 72 x 8 inchesAn ancient Chinese divination device called a Luo PanCompass serves as the central object in this image of CDF.

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gallery: john zaklikowski

a sharp observer can spy the word “HIGGS.” The detector itself rests on a foundation of silver lids, of the variety one might find on the top of a cheese shaker.

“These things work on so many different levels,” Zaklikowski says. “Like particle-physics detectors, the individual components are oftentimes men-tally intriguing or attractive objects in themselves, adding another layer of interest.”

Zaklikowski’s later works stray from exact replication, as he muddies the boundary between physicist and artist. With LHC, inspired by the Large Hadron Collider on the border between France and Switzerland, he brings together 90 hard drives, 100 razor blades and scalpels, and many square feet of circuit boards to create a detector part CMS, part ATLAS, as two of the colliders’ giant detectors are known.

“I have to caution visitors that this work could be dangerous with all the razor and scalpel

blades,” he says, gesturing to the center of the three-dimensional work, where a circle of sharp blades protrudes toward the viewer. “It’s not necessarily intentional, but there is a little play on how some people think these particle accel-erators are dangerous machines that are going to create micro-black holes that are going to destroy the Earth. Of course that’s not the case, but those perceptions are part of the reality, too.”

Zaklikowski’s most recent particle-physics-based work, which is still in progress, is a stylized interpretation of SLAC National Accelerator Laboratory’s particle detectors. Working from photographs of the SLAC Large Detector and the BaBar detector, he is creating an eight-by-eight-foot piece surrounded by green circuit boards. As the eye is pulled inward by radial lines, it sweeps past banks of shiny silver hard drives and toward the central component, a circle of vacuum tubes of varying sizes.

“i find particle detectors to be very beautiful things; fascinating, compelling, powerfully moving objects from a visual point of view.”

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“Younger people often don’t know what these are because they have never seen a vacuum tube,” he says. “But when I was young, all radios and televisions were filled with these because solid-state electronic devices weren’t invented yet. In fact, particle detectors were originally made of vacuum chambers—not vacuum tubes, but similar. And so I call this the Stanford Vacuum Chamber.”

He says that as an artist, he is continually amazed by the tools of physics.

“I find particle detectors to be very beautiful things; fascinating, compelling, powerfully moving objects from a visual point of view,” Zaklikowski says. “If we were to take the CMS and the CDF out of their respective tunnels and cart them into an art gallery or museum that had high enough ceilings, I think you would find them to be extraordinarily beautiful objects in themselves.”

Prepared Piano, 200976 x 64 x 66 inchesReconfigured baby grand piano incorporating hundreds of computer components, six flutes, three clarinets, a tabla drum, six harmonicas, eight tuning forks, a hundred cell phones, 10 cue balls and one perfectly functioning cross-bow.

From left to right

Language Arts, 200850 x 50 x 12 inches

Trampoline, 200850 x 50 x 18 inches

Number Theory, 200850 x 50 x 9 inches

The objects are stained with roofing compound diluted with mineral spirits.

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accelerator apps: sterilizing medical supplies

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Beaming up sterile syringesSterilizing equipment is a critical aspect of modern medical care: think of all the contact patients have with syringes, surgical tools, and bandages. The first breakthrough in sterilization technology was the autoclave, which kills microbes with high- pressure steam; it’s been used in hospitals for more than a century. Today’s medical equipment may be bombarded with gamma rays or treated with a chemical such as ethylene oxide gas.

But there is another method with unique advantages: bombarding the equipment and its packaging with a beam of electrons or X-rays derived from a particle accelerator.

For convenience and safety, manufacturers often sterilize syringes, bandages, surgical tools, and other medical gear in their final packaging. They need to kill every single germ on both the product and packaging, which are very different materials, without damaging or altering either.

Heat sterilization is out of the question, because it could warp the plastic. And techniques involving gamma radiation or harsh chemicals raise concerns about worker safety and proper waste disposal.

Particle accelerators sidestep those problems.E-beam sterilization dates back to 1956,

when Johnson & Johnson developed the first commercial system. As accelerator technology advanced, pushed along by the demands of high-energy physics research at US national labora-tories, industry continued to refine accelerators

for its own needs. Today e-beam represents a small but promising segment of the medical equipment sterilization market.

In an e-beam facility, packaged syringes, sur-gical sutures, gauze, and so on ride a conveyor belt through a tunnel while one or more small accelerators hit them with electron beams. Electrons pass through the packaging materials and eradicate any microbes on the surface of the product.

Like any method, this one has its pros and cons.E-beams have limited penetration and work

best on simple, low-density, high-volume products, such as syringes and bandages.

One big advantage of the method is that it takes a matter of seconds, compared to hours for gamma-ray sterilization, says Wayne Rogers, a consultant with years of experience in the field. E-beams are less damaging to some materials and devices than other techniques, and leave no chemical residue. E-beams shift from the higher to lower doses that are required for different prod-ucts much faster than other technologies allow. High-powered electron accelerators are also being used to generate X-rays, which are as effective as gamma rays for sterilization.

“It’s very flexible,” says Susie Perlman of BeamOne, a Denver company that contracts with manufacturers to sterilize medical equipment using electron beams. “I can sterilize a single piece of tissue and then switch over to a truckload of Petri dishes immediately after.”Julie Karceski

www.symmetrymagazine.org/archive/apps

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logbook: CERN touch screen

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On March 11, 1972, CERN engineer

Bent Stumpe proposed a new type of interactive com-puter display for controlling the lab’s new Super Proton Synchrotron accelerator. His 16-page handwritten proposal describes what was apparently the world’s first capacitive touch screen, a technology now widely used in ticket machines and smart phones.

Up to that point, every command sent to an accelerator at the European particle physics lab traveled directly from a button, knob, or switch in the control center via individual cable. Existing touch screens—including one based on acoustics, invented at what is now SLAC National Accelerator Laboratory—were too bulky. So Frank Beck, who would become head of SPS Central Controls, asked Stumpe for a more streamlined solution.

Stumpe came up with a fixed number of programmable

buttons on a flexible screen. Just below the screen, an array of capacitors—devices for storing electric charge—were etched into a copper film. The touch of a finger on one of the buttons changed the level of electrical current flowing through the system. Specialized electronics recorded those changes and brought up a new set of labels for the display buttons— a new set of commands that could be selected.

The SPS control room opened in 1976 with three 16-button touch screens, some of which continued to operate for 30 years. By 1977, CERN’s touch screens were being sold to other research institutes and companies, including Rutherford Laboratory in the United Kingdom and Mitsubishi in Japan.

Capacitive touch screens have since been reinvented in many applications, including the iPad, and are ubiqui-tous worldwide.Adapted from an article by Bent Stumpe and Christine Sutton in the CERN Courier.

Charged leptons are a breed of ele-mentary particle

that comes in three masses: the lightweight electron, responsible for the electricity in our homes; the middle-weight muon; and the heavy tau. Two other types of elementary particles, quarks and neutrinos, come in three masses as well.

You might not think about dogs while you wonder about particle physics, but there are similarities. Poodles, for example, also come in three sizes—toy, miniature and standard—but they’re all the same breed, and genetically similar. Learning how poodles and other breeds are related helps us understand the rules of dog genetics.

We want the same type of understanding of how elementary particles relate to one another. Quarks can

change from one type to another; so can neutrinos. If you want to have any sensible “laws of genetics” for particle physics, that last breed, the charged leptons, had better be able to change types as well. That’s called charged lepton flavor violation. Surprisingly, physicists have never seen it happen.

Previous experiments have looked at about 10 trillion muons; Fermilab’s Mu2e experiment will observe 10,000 times more data, looking for a change from a muon to an electron. Discovering this change would point us toward a single theory explaining the genetics of the particles born in the big bang. If we don’t discover this change, there will be a lot of head-scratching (as opposed to fur-scratching) as we try to understand the rules of the universe.Bob Bernstein, Fermilab

symmetryA joint Fermilab/SLAC publicationPO Box 500MS 206Batavia Illinois 60510USA

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