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Prototype CT scanner could improve targeting accuracy in proton therapy treatment

Monday, July 21st, 2014

This article appeared in Fermilab Today on July 21, 2014.

Members of the prototype proton CT scanner collaboration move the detector into the CDH Proton Center in Warrenville. Photo: Reidar Hahn

Members of the prototype proton CT scanner collaboration move the detector into the CDH Proton Center in Warrenville. Photo: Reidar Hahn

A prototype proton CT scanner developed by Fermilab and Northern Illinois University could someday reduce the amount of radiation delivered to healthy tissue in a patient undergoing cancer treatment.

The proton CT scanner would better target radiation doses to the cancerous tumors during proton therapy treatment. Physicists recently started testing with beam at the CDH Proton Center in Warrenville.

To create a custom treatment plan for each proton therapy patient, radiation oncologists currently use X-ray CT scanners to develop 3-D images of patient anatomy, including the tumor, to determine the size, shape and density of all organs and tissues in the body. To make sure all the tumor cells are irradiated to the prescribed dose, doctors often set the targeting volume to include a minimal amount of healthy tissue just outside the tumor.

Collaborators believe that the prototype proton CT, which is essentially a particle detector, will provide a more precise 3-D map of the patient anatomy. This allows doctors to more precisely target beam delivery, reducing the amount of radiation to healthy tissue during the CT process and treatment.

“The dose to the patient with this method would be lower than using X-ray CTs while getting better precision on the imaging,” said Fermilab’s Peter Wilson, PPD associate head for engineering and support.

Fermilab became involved in the project in 2011 at the request of NIU’s high-energy physics team because of the laboratory’s detector building expertise.

The project’s goal was a tall order, Wilson explained. The group wanted to build a prototype device, imaging software and computing system that could collect data from 1 billion protons in less than 10 minutes and then produce a 3-D reconstructed image of a human head, also in less than 10 minutes. To do that, they needed to create a device that could read data very quickly, since every second data from 2 million protons would be sent from the device — which detects only one proton at a time — to a computer.

NIU physicist Victor Rykalin recommended building a scintillating fiber tracker detector with silicon photomultipliers. A similar detector was used in the DZero experiment.

“The new prototype CT is a good example of the technical expertise of our staff in detector technology. Their expertise goes back 35 to 45 years and is really what makes it possible for us to do this,” Wilson said.

In the prototype CT, protons pass through two tracking stations, which track the particles’ trajectories in three dimensions. (See figure.) The protons then pass through the patient and finally through two more tracking stations before stopping in the energy detector, which is used to calculate the total energy loss through the patient. Devices called silicon photomultipliers pick up signals from the light resulting from these interactions and subsequently transmit electronic signals to a data acquisition system.

In the prototype proton CT scanner, protons enter from the left, passing through planes of fibers and the patient's head. Data from the protons' trajectories, including the energy deposited in the patient, is collected in a data acquisition system (right), which is then used to map the patient's tissue. Image courtesy of George Coutrakon, NIU

In the prototype proton CT scanner, protons enter from the left, passing through planes of fibers and the patient’s head. Data from the protons’ trajectories, including the energy deposited in the patient, is collected in a data acquisition system (right), which is then used to map the patient’s tissue. Image courtesy of George Coutrakon, NIU

Scientists use specialized software and a high-performance computer at NIU to accurately map the proton stopping powers in each cubic millimeter of the patient. From this map, visually displayed as conventional CT slices, the physician can outline the margins, dimensions and location of the tumor.

Elements of the prototype were developed at both NIU and Fermilab and then put together at Fermilab. NIU developed the software and computing systems. The teams at Fermilab worked on the design and construction of the tracker and the electronics to read the tracker and energy measurement. The scintillator plates, fibers and trackers were also prepared at Fermilab. A group of about eight NIU students, led by NIU’s Vishnu Zutshi, helped build the detector at Fermilab.

“A project like this requires collaboration across multiple areas of expertise,” said George Coutrakon, medical physicist and co-investigator for the project at NIU. “We’ve built on others’ previous work, and in that sense, the collaboration extends beyond NIU and Fermilab.”

Rhianna Wisniewski

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US reveals its next generation of dark matter experiments

Monday, July 14th, 2014

This article appeared in symmetry on July 11, 2014.

Together, the three experiments will search for a variety of types of dark matter particles. Photo: NASA

Together, the three experiments will search for a variety of types of dark matter particles. Photo: NASA

Two US federal funding agencies announced today which experiments they will support in the next generation of the search for dark matter.

The Department of Energy and National Science Foundation will back the Super Cryogenic Dark Matter Search-SNOLAB, or SuperCDMS; the LUX-Zeplin experiment, or LZ; and the next iteration of the Axion Dark Matter eXperiment, ADMX-Gen2.

“We wanted to pool limited resources to put together the most optimal unified national dark matter program we could create,” says Michael Salamon, who manages DOE’s dark matter program.

Second-generation dark matter experiments are defined as experiments that will be at least 10 times as sensitive as the current crop of dark matter detectors.

Program directors from the two federal funding agencies decided which experiments to pursue based on the advice of a panel of outside experts. Both agencies have committed to working to develop the new projects as expeditiously as possible, says Jim Whitmore, program director for particle astrophysics in the division of physics at NSF.

Physicists have seen plenty of evidence of the existence of dark matter through its strong gravitational influence, but they do not know what it looks like as individual particles. That’s why the funding agencies put together a varied particle-hunting team.

Both LZ and SuperCDMS will look for a type of dark matter particles called WIMPs, or weakly interacting massive particles. ADMX-Gen2 will search for a different kind of dark matter particles called axions.

LZ is capable of identifying WIMPs with a wide range of masses, including those much heavier than any particle the Large Hadron Collider at CERN could produce. SuperCDMS will specialize in looking for light WIMPs with masses lower than 10 GeV. (And of course both LZ and SuperCDMS are willing to stretch their boundaries a bit if called upon to double-check one another’s results.)

If a WIMP hits the LZ detector, a high-tech barrel of liquid xenon, it will produce quanta of light, called photons. If a WIMP hits the SuperCDMS detector, a collection of hockey-puck-sized integrated circuits made with silicon or germanium, it will produce quanta of sound, called phonons.

“But if you detect just one kind of signal, light or sound, you can be fooled,” says LZ spokesperson Harry Nelson of the University of California, Santa Barbara. “A number of things can fake it.”

SuperCDMS and LZ will be located underground—SuperCDMS at SNOLAB in Ontario, Canada, and LZ at the Sanford Underground Research Facility in South Dakota—to shield the detectors from some of the most common fakers: cosmic rays. But they will still need to deal with natural radiation from the decay of uranium and thorium in the rock around them: “One member of the decay chain, lead-210, has a half-life of 22 years,” says SuperCDMS spokesperson Blas Cabrera of Stanford University. “It’s a little hard to wait that one out.”

To combat this, both experiments collect a second signal, in addition to light or sound—charge. The ratio of the two signals lets them know whether the light or sound came from a dark matter particle or something else.

SuperCDMS will be especially skilled at this kind of differentiation, which is why the experiment should excel at searching for hard-to-hear low-mass particles.

LZ’s strength, on the other hand, stems from its size.

Dark matter particles are constantly flowing through the Earth, so their interaction points in a dark matter detector should be distributed evenly throughout. Quanta of radiation, however, can be stopped by much less significant barriers—alpha particles by a piece of paper, beta particles by a sandwich. Even gamma ray particles, which are harder to stop, cannot reach the center of LZ’s 7-ton detector. When a particle with the right characteristics interacts in the center of LZ, scientists will know to get excited.

The ADMX detector, on the other hand, approaches the dark matter search with a more delicate touch. The dark matter axions ADMX scientists are looking for are too light for even SuperCDMS to find.

If an axion passed through a magnetic field, it could convert into a photon. The ADMX team encourages this subtle transformation by placing their detector within a strong magnetic field, and then tries to detect the change.

“It’s a lot like an AM radio,” says ADMX-Gen2 co-spokesperson Gray Rybka of the University of Washington in Seattle.

The experiment slowly turns the dial, tuning itself to watch for one axion mass at a time. Its main background noise is heat.

“The more noise there is, the harder it is to hear and the slower you have to tune,” Rybka says.

In its current iteration, it would take around 100 years for the experiment to get through all of the possible channels. But with the addition of a super-cooling refrigerator, ADMX-Gen2 will be able to search all of its current channels, plus many more, in the span of just three years.

With SuperCDMS, LZ and ADMX-Gen2 in the works, the next several years of the dark matter search could be some of its most interesting.

Kathryn Jepsen

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Fermilab scientist Joe Lykken assumes deputy director role

Wednesday, July 2nd, 2014
Joe Lykken

Joe Lykken

Joe Lykken is a familiar name not only at Fermilab, where he has worked as a theorist since 1989, but to people across the country who have seen him on PBS or have read his words in Scientific American.

His vast experience in researching and communicating particle physics led Director Nigel Lockyer to select Lykken as Fermilab’s new deputy director. Lykken began in the new position on July 1.

Although Lykken is very familiar with the laboratory’s science, he hopes to become better acquainted with other aspects of Fermilab as he starts out in the directorate role.

“I’m really looking forward to having as many conversations one on one with as many people as I can,” he said.

In helping lead the laboratory, one of Lykken’s tasks will be to implement the P5 vision.

“P5 gave us a very strong push that we want to take advantage of,” he said. Part of that will be to work with international partners to put together the best possible neutrino program, for which LBNE has laid the groundwork, he said.

Implementing the P5 plan also involves communicating Fermilab’s scientific goals with its employees, decision makers and general audiences alike. Lykken is well suited to the task, having become one of the lab’s go-to scientists for talking with the public. He was one of the guest scientists on the PBS television series “The Elegant Universe” and has been interviewed for stories in publications such as The New York Times and Science, as well as on NPR.

“Part of my job is to help both this laboratory and the rest of the world understand Nigel’s vision and the program that we’re trying to implement — our ambitions and dreams,” Lykken said. “I’ll help explain the science, why it’s exciting and how it all fits together. It’s not just a laundry list of topics, but that’s not so obvious to most people.”

Prior to his arrival at the lab, Lykken was at the Santa Cruz Institute for Particle Physics, having completed his Ph.D. at MIT. Both an APS and a AAAS fellow, he started out at Fermilab as a string theorist and then became more involved in the CMS experiment at CERN’s Large Hadron Collider. He continued theoretical work on Higgs physics and supersymmetry while gaining interest in the experimental side.

In addition to his deputy director position, Lykken will serve as the laboratory’s chief research officer; Greg Bock will serve as deputy CRO. Lykken will also continue to work in the Theory Group, supervising postdoctoral students.

“Joe has an envious track record in scientific research as well as in translating science for the public,” said Director Nigel Lockyer. “He is adept at problem solving and enjoys combining his analytic thinking with keen intuition when solving challenging situations — and we have lots of them here at Fermilab for him to practice on. I very much look forward to his talents being applied to helping Fermilab achieve its goals.”

Leah Hesla

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Dark Energy Survey discovers exotic type of supernova

Friday, June 27th, 2014

This article appeared in Fermilab Today on June 27, 2014.

The Milky Way rises over the Cerro Tololo Inter-American Observatory in northern Chile. The Dark Energy Survey operates from the largest telescope at the observatory, the 4-meter Victor M. Blanco Telescope (left). Photo courtesy of Andreas Papadopoulos

The Milky Way rises over the Cerro Tololo Inter-American Observatory in northern Chile. The Dark Energy Survey operates from the largest telescope at the observatory, the 4-meter Victor M. Blanco Telescope (left). Photo courtesy of Andreas Papadopoulos

The first images taken by the Dark Energy Survey after it began in August 2013 have revealed a rare, “superluminous” supernova (SLSN) that erupted in a galaxy 7.8 billion light-years away. The stellar explosion, called DES13S2cmm, easily outshines most galaxies in the universe and could still be seen in the data six months later, at the end of the first of what will be five years of observing by DES.

Supernovae are very bright, shining anywhere from 100 million to a few billion times brighter than the sun for weeks on end. Thousands of these brilliant stellar deaths have been discovered over the last two decades, and the word “supernova” itself was coined 80 years ago. Type Ia supernovae, the most well-known class of supernovae, are used by cosmologists to measure the expansion rate of the universe.

But SLSNe are a recent discovery, recognized as a distinct class of objects only in the past five years. Although they are 10 to 50 times brighter at their peak than type Ia supernovae, fewer than 50 have ever been found. Their rareness means each new discovery brings the potential for greater understanding — or more surprises.

Before (left) and after (center) images of the region where DES13S2cmm was discovered. On the right is a subtraction of these two images, showing a bright new object at the center — a supernova. Image: Dark Energy Survey

Before (left) and after (center) images of the region where DES13S2cmm was discovered. On the right is a subtraction of these two images, showing a bright new object at the center — a supernova. Image: Dark Energy Survey


It turns out that even within this select group of SLSNe, DES13S2cmm is unusual. The rate at which it is fading away over time is much slower than for most other SLSNe that have been observed to date. This change in brightness over time, or light curve, gives information on the mechanisms that caused the explosion and the composition of the material ejected. DES can constrain the potential energy source for DES13S2cmm thanks to the exceptional photometric data quality available. Only about 10 SLSNe are known that have been similarly well-studied.

Although they are believed to come from the death of massive stars, the explosive origin of SLSNe remains a mystery. The DES team tried to explain the luminosity of DES13S2cmm as a result of the decay of the radioactive isotope nickel-56, known to power normal supernovae. They found that, to match the peak brightness, the explosion would need to produce more than three times the mass of our sun of the element. However, the model is then unable to reproduce the rate at which DES13S2cmm brightened and faded.

The DES13S2cmm superluminous supernova was discovered by Andreas Papadopoulos (right), a graduate student at the University of Portsmouth and lead author on a forthcoming paper about the supernova. Chris D'Andrea (left) is a postdoctoral researcher at Portsmouth and leads the DES supernova spectroscopic follow-up program. Photo courtesy of Andreas Papadopoulos

The DES13S2cmm superluminous supernova was discovered by Andreas Papadopoulos (right), a graduate student at the University of Portsmouth and lead author on a forthcoming paper about the supernova. Chris D’Andrea (left) is a postdoctoral researcher at Portsmouth and leads the DES supernova spectroscopic follow-up program. Photo courtesy of Andreas Papadopoulos

A model that is more highly favored in the literature for SLSNe involves a magnetar: a neutron star that rotates once every millisecond and generates extreme magnetic fields. Produced as the remnant of a massive supernova, the magnetar begins to “spin down” and inject energy into the supernova, making the supernova exceptionally bright. This model is better able to produce the behavior of DES13S2cmm, although neither scenario could be called a good fit to the data.

DES13S2cmm was the only confirmed SLSN from the first season of DES, but several other promising candidates were found that could not be confirmed at the time. More are expected in the coming seasons. The goal is to discover and monitor enough of these rare objects to enable them to be understood as a population.

Although designed for studying the evolution of the universe, DES will be a powerful probe for understanding superluminous supernovae.

Chris D’Andrea and Andreas Papadopoulos, Institute of Cosmology and Gravitation, University of Portsmouth

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Massive 30-ton MicroBooNE particle detector moved into place, will see neutrinos this year

Wednesday, June 25th, 2014

Fermilab published a version of this press release on June 24, 2014.

The 30-ton MicroBooNE neutrino detector is gently lowered into the Liquid-Argon Test Facility at Fermilab on Monday, June 23. The detector will become the centerpiece of the MicroBooNE experiment, which will study ghostly particles called neutrinos. Photo: Fermilab

The 30-ton MicroBooNE neutrino detector is gently lowered into the Liquid-Argon Test Facility at Fermilab on Monday, June 23. The detector will become the centerpiece of the MicroBooNE experiment, which will study ghostly particles called neutrinos. Photo: Fermilab

On Monday, June 23, the next phase of neutrino physics at Fermilab fell (gently) into place.

The MicroBooNE detector – a 30-ton, 40-foot-long cylindrical metal tank designed to detect ghostly particles called neutrinos – was carefully transported by truck across the U.S. Department of Energy’s Fermilab site, from an assembly building it was constructed in to the experimental hall three miles away.

The massive detector was then hoisted up with a crane, lowered through the open roof of the building and placed into its permanent home, directly in the path of Fermilab’s beam of neutrinos. There it will become the centerpiece of the MicroBooNE experiment, which will study those elusive particles to crack several big mysteries of the universe.

The MicroBooNE detector has been under construction for nearly two years. The tank contains a 32-foot-long “time projection chamber,” the largest ever built in the United States, equipped with 8,256 delicate gilded wires, which took the MicroBooNE team two months to attach by hand. This machine will allow scientists to further study the properties of neutrinos, particles that may hold the key to understanding many unexplained mysteries of the universe.

“This is a huge day for the MicroBooNE experiment,” said Fermilab’s Regina Rameika, project manager for the MicroBooNE experiment. “We’ve worked hard to create the best scientific instrument that we can. To see it moved into place was a thrill for the entire team.”

The MicroBooNE detector will now be filled with 170 tons of liquid argon, a heavy liquid that will release charged particles when neutrinos interact with it. The detector’s three layers of wires will then capture pictures of these interactions at different points in time and send that information to the experiment’s computers.

Using one of the most sophisticated processing programs ever designed for a neutrino experiment, those computers will sift through the thousands of interactions that will occur every day and create stunning 3-D images of the most interesting ones. The MicroBooNE team will use that data to learn more about how neutrinos change from one type (or “flavor”) to another, and narrow the search for a hypothesized (but as of yet, never observed) fourth type of neutrino.

“The scientific potential of MicroBooNE is really exciting,” said Yale University’s Bonnie Fleming, co-spokesperson for the MicroBooNE experiment. “After a long time spent designing and building the detector, we are thrilled to start taking data later this year.”

MicroBooNE is a cornerstone of Fermilab’s short-baseline neutrino program , which studies neutrinos traveling over shorter distances. (MINOS and NOvA, which send neutrinos through the Earth to Minnesota, are examples of long-baseline experiments.) In its recent report, the Particle Physics Project Prioritization Panel (P5) expressed strong support for the short-baseline neutrino program at Fermilab.

The P5 panel was comprised of members of the high-energy physics community. Their report was commissioned by the High Energy Physics Advisory Panel, which advises both the Department of Energy and the National Science Foundation on funding priorities.

The detector technology used in designing and building MicroBooNE will serve as a prototype for a much larger long-baseline neutrino facility planned for the United States, to be hosted at Fermilab. The P5 report also strongly supports this larger experiment, which will be designed and funded through a global collaboration.

Read the P5 report.

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

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

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Kids invited to Wave Like a Particle and Swing Like a Neutrino at Fermilab’s new outdoor exhibits

Thursday, June 12th, 2014

A version of this press release came out on on June 12, 2014.

Pi poles are part of a new exhibit for kids at Fermilab's Lederman Science Center, an educational center that houses resources for K-12 teachers and hosts science activities for students. Photo: Cindy Arnold

Pi poles are part of a new exhibit for kids at Fermilab’s Lederman Science Center, an educational center that houses resources for K-12 teachers and hosts science activities for students. Photo: Cindy Arnold

If you want to get children interested in the fundamentals of science, there’s nothing like letting them experience the phenomena first-hand. If you can make it fun at the same time, you have a formula for success.

That’s the thinking behind Fermilab’s in-progress outdoor physics exhibits, located near the Lederman Science Center. The Lederman Science Center is an educational center that houses science resources for K-12 teachers and hosts science activities for students. The Fermilab Education Office has just unveiled the latest exhibits, which allow kids to learn about basic principles of physics while playing in the sunshine.

The two new exhibits, called Wave Like a Particle and Swing Like Neutrinos, are combined into one newly built structure consisting of two poles shaped like the Greek letter Pi. Kids can make waves of various sizes by moving the rope that stretches between the two poles, thereby learning about wave propagation, one of the primary concepts of particle physics.

Children can also use the Swing Like Neutrinos portion of the exhibit – a pair of pendulums hanging from one of the Pi-shaped poles – to learn about coupled oscillations, a basic physics principle.

“Kids learn in different ways,” said Spencer Pasero of Fermilab’s Education Office. “The idea of the outdoor exhibits is to instill a love of learning into kids who respond to hands-on, fun activities.”

The Wave Like a Particle and Swing Like Neutrinos exhibits were built with funds through Fermilab Friends for Science Education, an Illinois not-for-profit organization supporting the Fermilab Education Office. Contributions were received from an anonymous donor and a grant from the Community Foundation of the Fox River Valley.

The new exhibits join the Run Like a Proton accelerator path, which opened in May 2013. Using this feature, kids can mimic protons and antiprotons as they race along Fermilab’s accelerator chain.

“We hope this series of exhibits will activate kids’ imaginations and that they immerse themselves in the physics we’ve been doing at Fermilab for decades,” Pasero said.

Fermilab is located 35 miles outside Chicago, Illnois. The Lederman Science Center is open to the public Monday to Friday from 8:30 a.m. to 4:30 p.m. and on Saturdays from 9 a.m. to 3 p.m.

The Community Foundation of the Fox River Valley is a non-profit philanthropic organization based in Aurora, Illinois that administers individual charitable funds from which grants and scholarships are distributed to benefit the citizens of the Greater Aurora Area, the TriCities and Kendall County Illinois. For more information, please see www.communityfoundationfrv.org.

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

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

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MINOS result narrows field for sterile neutrinos

Wednesday, June 4th, 2014

This article appeared in symmetry on June 4, 2014.

Data collected at the long-running MINOS experiment stacks evidence against the existence of these theoretical particles. Photo: Reidar Hahn

Data collected at the long-running MINOS experiment stacks evidence against the existence of these theoretical particles. Photo: Reidar Hahn

If you’re searching for something that may not exist, and can pass right through matter if it does, then knowing where to look is essential.

That’s why the search for so-called sterile neutrinos is a process of elimination. Experiments like Fermilab’s MiniBooNE and the Liquid Scintillator Neutrino Detector (LSND) at Los Alamos National Laboratory have published results consistent with the existence of these theoretical particles. But a new result from the long-running MINOS experiment announced this week severely limits the area in which they could be found and casts more doubt on whether they exist at all.

Scientists have observed three types or “flavors” of neutrinos—muon, electron and tau neutrinos—through their interactions with matter. If there are other types, as some scientists have theorized, they do not interact with matter, and the search for them has become one of the hottest and most contentious topics in neutrino physics. MINOS, located at Fermilab with a far detector in northern Minnesota, has been studying neutrinos since 2005, with an eye toward collecting data on neutrino oscillation over long distances.

MINOS uses a beam of muon neutrinos generated at Fermilab. As that beam travels 500 miles through the earth to Minnesota, those muon neutrinos can change into other flavors.

MINOS looks at two types of neutrino interactions: neutral current and charged current. Since MINOS can see the neutral current interactions of all three known flavors of neutrino, scientists can tell if fewer of those interactions occur than they should, which would be evidence that the muon neutrinos have changed into a particle that does not interact. In addition, through charged current interactions, MINOS looks specifically at muon neutrino disappearance, which allows for a much more precise measurement of neutrino energies, according to João Coelho of Tufts University.

“Disappearance with an energy profile not described by the standard three-neutrino model would be evidence for the existence of an additional sterile neutrino,” Coelho says.

The new MINOS result, announced today at the Neutrino 2014 conference in Boston, excludes a large and previously unexplored region for sterile neutrinos. To directly compare the new results with previous results from LSND and MiniBooNE, MINOS combined its data with previous measurements of electron antineutrinos from the Bugey nuclear reactor in France. The combined result, says Justin Evans of the University of Manchester, “provides a strong constraint on the existence of sterile neutrinos.”

“The case for sterile neutrinos is still not closed,” Evans says, “but there is now a lot less space left for them to hide.”

Andre Salles

The vertical axis shows the possible mass regions for the sterile neutrinos. The horizontal axis shows how likely it is that a muon neutrino will turn into a sterile neutrino as it travels. The new MINOS result excludes everything to the right of the black line. The colored areas show limits by previous experiments. Image courtesy of MINOS collaboration

The vertical axis shows the possible mass regions for the sterile neutrinos. The horizontal axis shows how likely it is that a muon neutrino will turn into a sterile neutrino as it travels. The new MINOS result excludes everything to the right of the black line. The colored areas show limits by previous experiments.
Image courtesy of MINOS collaboration

This graph shows the combined MINOS/Bugey result (the red line) in comparison with the results from LSND and MiniBooNE (the green areas). The vertical axis shows the possible mass regions for sterile neutrinos. The new MINOS/Bugey result excludes everything to the right of the red line. Image courtesy of MINOS collaboration

This graph shows the combined MINOS/Bugey result (the red line) in comparison with the results from LSND and MiniBooNE (the green areas). The vertical axis shows the possible mass regions for sterile neutrinos. The new MINOS/Bugey result excludes everything to the right of the red line.
Image courtesy of MINOS collaboration

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Out with the old: Fermilab accelerator magnet adorns Google Chicago’s offices

Monday, May 19th, 2014
Dan Yocum, left, formerly of Fermilab, shakes hands with Google's Brian Fitzpatrick in front of a quadrupole magnet at its new home in Google's Chicago offices. Photo: Troy Dawson

Dan Yocum, left, formerly of Fermilab, shakes hands with Google’s Brian Fitzpatrick in front of a quadrupole magnet’s new home in Google’s Chicago offices. Photo: Troy Dawson

Fermilab does a good job of recycling — from the ubiquitous blue trash cans to electromagnets to — in my case — employees. I myself left Fermilab in 1999 only to recycle back to the Experimental Astrophysics Group in 2000 to work on the Sloan Digital Sky Survey before leaving again in 2012.

When news of the Tevatron’s decommissioning reached Brian Fitzpatrick, head of software engineering in the Chicago offices of Google, he sent
me a short email lamenting the Tevatron closure. He included a request for a souvenir to display in Google’s Chicago offices. Brian and I met when he came to Fermilab to give a computing seminar talk on MapReduce and BigTable several years ago. We have remained in touch ever since, so I gladly accepted the challenge.

My next stop was the office of Accelerator Division head Roger Dixon. We discussed the possibility of acquiring something from the Tevatron for Google and conferred briefly with scientist Todd Johnson. We settled on a quadrupole steering magnet.

But getting a magnet out of the Tevatron was out of the question since the magnet would be slightly radioactive. As a rule, Fermilab’s safety section and the Department of Energy never let even slightly activated material leave the site to be recycled. But hope was not lost, and Roger suggested I speak with Dave Harding, then deputy head of the Technical Division, to see if there were any spare magnets in storage. Off I went to find Dave.

Dave determined that there were indeed several magnets that were clean and in storage because they had been determined to be flawed during post-manufacture testing. One man’s trash is another man’s treasure. I had hit pay dirt!

Roger had also warned that I would have to walk through a labyrinth of people in the Directorate, Business Services, Environmental Health and Safety and DOE before the magnet could be released. Over several months I proceeded to meet and speak with many folks. I list them here so they know how much I appreciate them: Gerald Annala, Dave Augustine, Jose Cardona, Debra Cobb, Shannon Fugman, Jack Kelly, Scott McCormick, Dean Still and John Zweibohmer.

After many emails of clarification, justification and negotiation, everything was signed off and the plan was approved.

Success! Or so I thought. I was already starting to feel a bit like Odysseus trying to get home after the Trojan War when I spoke with Jack Kelly in the Property Department: We had one more bit of stormy water to navigate. Luckily, Jack was an able guide, shepherding the paperwork and the magnet through not one but three online auctions for the DOE labs, the universities and, finally, eBay. He put the big shiny blue “Buy it Now” button on the final eBay page, where Google’s Brian Fitzpatrick clicked and paid $150 for a piece of Tevatron history. How did they come up with the price? That figure was based on the magnet’s estimated scrap metal value. But instead of being turned into scrap, it now proudly resides in Google’s Chicago offices.

On September 28, 2012, after 349 days of navigating a quagmire of paperwork, we had recycled a Tevatron quadrupole magnet and found a new home for it.

The magnet is the centerpiece amongst a myriad of historical scientific and computing items at the Google office. There’s even an Sloan Digital Sky Survey spectroscopic plug plate to keep it company.

Former Fermilab employee Paul Rossman, who works at Google, says, “It’s nice to pass an awesome piece of technology like the quadrupole magnet on the way to my desk. It’s almost like I got to take a little something with me from Fermilab.” Nice, indeed.

I’d like to express my sincerest appreciation to all the people named in this article. You are some of the best of Fermilab. Thank you.

Dan Yocum

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Saving the Feynman van

Monday, May 12th, 2014

A version of this article appeared in symmetry on May 8, 2014.

A team of Richard Feynman’s friends and fans banded together to restore the Nobel laureate’s most famous vehicle.

A team of Richard Feynman’s friends and fans banded together to restore the Nobel laureate’s most famous vehicle. Image courtesy of Seamus Blackley

“The game I play is a very interesting one,” says Nobel Laureate Richard Feynman in a low-resolution video posted to YouTube. “It’s imagination in a tight straitjacket.”

Feynman is describing his job as a theoretical physicist: to lay out what humanity knows about how the world works, and to search the spaces in between for what we might have missed.

The video shows more than Feynman’s way with words. It shows his approachability. One of the greatest minds that particle physics has ever known stands barefoot, lecturing in a distinct Queens, New York, accent for an audience lounging casually on the floor at the new-age Esalen Institute in Big Sur, California.

In a way, Feynman remains approachable to this day for all of the snippets of his personality left behind in books, letters and recordings of formal and informal lectures and interviews.

Recently, a more concrete bit of Feynman history came out of retirement: A small team has brought back to life the so-called “Feynman van.”

One camper, special order

In 1975, Feynman and his wife, Gweneth Howarth, bought a Dodge Tradesman Maxivan and had it painted with Feynman diagrams, symbols Feynman had invented to express complicated particle interactions through simple lines and loops.

It might seem arrogant to drive around in a van covered in reminders of one’s own intellectual prowess. But Feynman’s daughter, Michelle, thinks the decorations represented something else: a love of physics.

“My dad was pretty low-key about himself,” she says. “I think decorating the van was more to celebrate the diagrams than to celebrate himself.”

Michelle’s parents put a lot of thought into the design of the vehicle, which they primarily used for camping, Michelle says. It was outfitted with a small hammock for Michelle to use in case the family of four needed to sleep inside during inclement weather.

“I don’t think that they had ever done anything like that with a car purchase before,” Michelle says. “It was always: Go to the dealer and find something—it doesn’t really matter what color it is—and you’ll have it for a million years.”

The Feynman family took the van to Canada, Mexico and dozens of US campsites in between, often traveling with a couple of other families, often leaving the paved road for the unknown.

Michelle began driving the van to school after she turned 16.

“I thought it was kind of embarrassing,” she says. “But at a certain point I kind of got over it. If you want to drive at that age, you’ll drive anything.”

After Michelle’s first couple of years in college, one of her father’s friends, film producer Ralph Leighton—Feynman’s drumming partner in another famous fuzzy YouTube clip—bought the van and put it into storage, where it began to rust and fade.

Saving the Feynman van

When video game designer Seamus Blackley, known as the father of the Xbox, got ahold of the van in 2012, “it was just about too late,” Blackley says.

Blackley has a history with particle physics. He was in his early 20s, working on his PhD thesis at Tufts University and Fermi National Accelerator Laboratory, when he saw his plans for the future disintegrate with the defunding of the planned Superconducting Super Collider.

“I found out on CNN,” he says.

He changed course and wound up taking a job working on some of the first computer games with 3D graphics. He designed the physics of the game environments, “keeping things from going into other things.” He has helped shape the world of video games in a variety of different roles since.

Game design takes the same type of thinking Feynman described in his talk at the Esalen Institute, Blackley says. A designer must creatively solve problems without breaking the rules that keep the environment realistic—“and then you have to have a lot of intuition about how to make it fun.”

In 2005, Blackley moved to Pasadena, California, just miles from where Leighton was keeping Feynman’s van. Oblivious to his proximity to the famous camper, Blackley nonetheless began to make a hobby of restoring classic Italian cars.

It was fellow Pasadena resident Michael Shermer, founder of the Skeptics Society, who told him about the van in 2012. Blackley knew right away that he had to help save it.

“The universe is telling me I’ve gotta do this,” he says.

With the help of Leighton and Shermer, along with a donation from Feynman fan and world-class designer Edward Tufte, Blackley registered the van as a historic vehicle and brought it to his preferred restoration specialists in Los Angeles.

The van’s Feynman diagrams, which were painted poorly in the first place, turned out to be too degraded for restoration. So a pinstriper re-painted them, taking care to replicate the quality of the original work.

“It looks like this crappy job again,” Blackley says with a smile. “You see the brush marks and everything.”

After the restoration, Blackley prepared to ship the van across the country for a Feynman-themed exhibit by Tufte, held at Fermilab.

Keeping the Feynman spirit alive

The test of whether the specialists had stayed true to the original came when Blackley invited Michelle to come see the van before its next big trip. She came with her 11- and 13-year-old children.

It didn’t look brand new, Michelle says, but it was as if it had been rewound 30 years, back to the days when her father was still in the driver’s seat. She told Blackley and her kids about the times her father slept on the floor below her hammock.

“As a father now, you appreciate what that means,” says Blackley, who has an 11-year-old son.

A camping van incongruously covered in physics notations seems to be a fitting symbol for a man who couldn’t seem to help thinking about particle physics, Michelle says.

“I think it was impossible for him to turn it off,” she says. “I remember in the car there was a Kleenex box, and the back of it had been used for equations. Every little piece of paper and every waking moment was fair game.”

Richard Feynman died of cancer in 1988 at the age of 69. But projects like the van restoration keep his memory alive, Michelle says.

“He would’ve been an amazing grandfather, and he never had the opportunity,” she says. “So I’m thrilled that there are so many people around who want to share his spirit and his life so my kids can get a sense of who he is.”

Kathryn Jepsen

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Keeping things awesome on the Dark Energy Survey

Monday, May 5th, 2014

This article appeared in symmetry on May 1, 2014.

Scientists stay inspired in their sometimes tedious task of inspecting photographs taken in the Dark Energy Survey’s ambitious cataloging of one-eighth of the sky. Image courtesy of Dark Energy Survey

Scientists stay inspired in their sometimes tedious task of inspecting photographs taken in the Dark Energy Survey’s ambitious cataloging of one-eighth of the sky. Image courtesy of Dark Energy Survey

Physicists working on the Dark Energy Survey can expect to pull many an all-nighter. The international collaboration of more than 120 scientists aims to take about 100,000 photographs peering deep into the night sky. Scientists must personally review many of these photos to make sure the experiment is working well, and they’ve come up with ways to stay motivated while doing so.

DES scientists collected almost 14,000 photographs from August 2013 to February 2014, in the first of five seasons they plan to operate their sophisticated Dark Energy Camera. Even for those of us who aren’t trying to take the most detailed survey of the universe, it might not come as a surprise that complications can occur during operation. For example, the telescope may not always sync up with the natural movement of the night sky, and passing airplanes can create trails in the images. Software bugs can also cause issues.

Two of the DES researchers, Erin Sheldon of Brookhaven National Laboratory and Peter Melchior of The Ohio State University, created the DES Exposure Checker, an online gallery of images from the telescope. Team members use the photo repository as a way to spot imperfections and other issues with the images so they can fix problems as quickly as possible.

“These problems are easier for an actual person to see rather than some automated program,” Sheldon says. “And then we can create an inventory to help diagnose troubles that may occur with future images.”

When reviewing photos, DES scientists flag the ones that show symptoms of different problems, such as long streaks from satellites; unwanted reflections, called ghosts; or marks left by cosmic rays. But the process can get overwhelming with thousands of photos to look over. So the DES researchers decided to add a positive classification to the mix—an “Awesome!” category. When someone sees an incredible photo, they can mark it as such in the database.

Sheldon points out one of his favorite images, one that captured a passing comet. “It was just so serendipitous. We couldn’t find that if we pointed the telescope in the same place at any other time,” he says.

Steve Kent, Fermilab scientist and head of the experimental astrophysics group, says one of his favorite images from the survey shows a dying star. In the color photo, a bright blue oxygen haze surrounds the hot remnant of what was formerly a giant red star.

A second way to encourage team members classifying images is the leader board posted on the DES Exposure Checker website, honoring individuals who have categorized the most photos. Researchers compete to see their names at the top.

But more than friendly competition drives the DES team to categorize images. They’re also seeking answers to questions about the past and future of our universe such as: Has the density of dark energy changed over time? Why is the expansion of the universe speeding up?

“For me, it’s a mystery,” Sheldon says. “I have this question, and I have to find out the answer.”

Amanda Solliday

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