OPERA catches its first tau neutrino

May 31, 2010 | 6:49 am

The OPERA detector underground at Italy's Gran Sasso National Laboratory. Image credit OPERA Collaboration.

Scientists from the OPERA experiment at INFN’s Gran Sasso National Laboratory have announced the first direct observation of  a neutrino transforming from one type into another. When confirmed by a few more such events, this observation will provide further  evidence that neutrinos have mass, a phenomenon that remains unexplained by physicists’ recipe for understanding the universe, the Standard Model.

Neutrinos are very light, neutral particles that exist in three types: electron, muon and tau. Over the past 15 years, several experiments have shown that neutrinos can spontaneously change type, or oscillate, as they travel long distances. These experiments, however, all measured the disappearance of certain types of neutrinos, leaving open the question of whether oscillation is a one-way or a two-way process. OPERA is the first experiment to measure the appearance of a tau neutrino in a beam of muon neutrinos, thus confirming that neutrinos oscillate between different types.

The scientists of the OPERA experiment have spent the last three years searching for the appearance of a tau particle in their detector as a beam of muon neutrinos, created 732 kilometers away at CERN in Geneva, Switzerland, passed through their underground experiment. The appearance of a tau particle in their detector indicates that one of the billions upon billions of muon neutrinos transformed into a tau neutrino.

More details can be found in the INFN press release and CERN press release, or you can watch this video from CERN that describes neutrinos and the oscillation phenomenon, the OPERA detector and creation of the muon neutrino beam, and today’s announcement.

Katie Yurkewicz

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Accelerator physicists strive to lower cost of cancer treatment

May 28, 2010 | 6:56 am

HIMAC in Chiba, Japan, was the first carbon-ion therapy center to take patients, in 1994. The accelerator sends carbon ions into three treatment rooms. Image courtesy of NIRS.

Several facilities that will offer cancer patients the latest innovation in hadron therapy, a medical application of particle accelerators, are under construction in Europe and Asia.

But so far the high cost of building and operating these facilities has prevented the treatment from becoming widely available.

Accelerator physicists from industry and academia challenged one another this week at the International Particle Accelerators Conference in Kyoto, Japan, to find ways to make the treatment, carbon-ion therapy, more affordable.

Hadron therapy uses an accelerator to send particles such as protons or ions into a patient’s tumor. The particles travel through the patient’s body and release most of their energy into the tumor cells, damaging them while limiting harm to the surrounding healthy tissue.

The development of proton therapy was a huge advancement in the treatment of cancer and is often just as effective as the more expensive carbon-ion therapy, said William Chu of Lawrence Berkeley National Laboratory in a talk on the subject of carbon-ion therapy this week at IPAC ’10. It has been the most widely used form of the treatment.

By the end of 2009, about 78,000 patients worldwide had been treated using hadron therapy, according to the Particle Therapy Co-Operative Group, PTCOG. About 86 percent were treated with protons, and less than 10 percent–about 7000 patients–with carbon ions.

Both treatments damage the DNA in a tumor cell, which can lead to its death, said Chu, a retired physicist who worked on hadron therapy at Lawrence Berkeley National Laboratory between 1975 and 1993.

DNA is made up of two strands of units called nucleotides that form a double helix. Each nucleotide in a strand has a partner nucleotide in the other strand. Proton therapy usually destroys a nucleotide in a single strand, leaving its partner nucleotide intact. The partner nucleotide can tell an enzyme how to replace the nucleotide that was destroyed. This way, the body can repair the damaged cancer cell.

Carbon ions, on the other hand, are more likely to damage both strands of DNA. This leaves enzymes without instructions on how to repair the cell and makes it more likely to die.

Using carbon ions also can be more effective in tumors with large centers void of the dissolved oxygen that blood vessels deliver, Chu said.

Four facilities currently offer carbon-ion therapy: the Heavy-Ion Medical Accelerator in Chiba, Japan; the Hyogo Ion Beam Medical Center in Hyogo, Japan; GSI in Darmstadt, Germany; and the Heidelberg Ion Beam Therapy Center in Heidelberg, Germany. Six new carbon-therapy facilities are under construction in Wiener Neustadt, Austria; Pavia, Italy; Heidelberg, Marburg, and Kiel, Germany; and Maebashi, Japan.

However, Chu said, building and operating a facility for carbon-ion therapy costs about twice as much as building and operating one for proton therapy–already an expensive venture at $120 to $180 million. So accelerator physicists will need to develop cheaper ways to offer the treatment if it is to gain the prominence of its more popular relative.

Kathryn Grim

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Middle East accelerator project approaches barrier

May 27, 2010 | 10:56 am

The BESSY I synchrotron-light source was originally operated at the Berlin Electron Storage Ring Company for Synchrotron Radiation. Image courtesy of BESSY.

Members of an unlikely international collaboration constructing the Middle East’s first synchrotron light source have dealt with outdated equipment, inexperience, and language barriers.

But one hurdle looms particularly large in their path: They need to gather more than $24 million to complete the final section of the accelerator.

The collaboration has struggled to find the funds within its membership and has begun discussions in Europe and the United States, said technical director Amor Nadji in a talk at IPAC ’10.

A synchrotron accelerator uses magnets to circulate electrons at almost the speed of light, creating a beam of bright ultraviolet and X-ray light. Scientists use beams from synchrotrons in materials science and biomedical applications. For example, biologists used a synchrotron light source to establish the double-helical structure of DNA.

The Synchrotron Light for Experimental Science and Applications in the Middle East, or SESAME, represents a rare example of cooperation between Bahrain, Cyprus, Egypt, Iran, Israel, Jordan, Pakistan, Palestinian Authority, and Turkey.

Young scientists from around the contentious region have been working side-by-side on construction of SESAME since 2003.

“The purpose is to try to use science for peace,” Nadji said.

Physicists Herman Winick, Gustav-Adolf “Gus” Voss, and others planted the seed for the project in 1997 when they proposed that Germany donate rather than scrap a recently decommissioned synchrotron called BESSY I.

As scientists in Germany began construction of the synchrotron’s successor, BESSY II, others packed the components of the original into crates and shipped them to a town near Amman, Jordan.

The process of fitting the pieces back together into a working accelerator has not been easy. Scientists have had to find replacements for parts built in the ‘70s and decipher notes handwritten in German. On top of that, most of those willing to work on SESAME are fresh out of school.

“Building an accelerator is not something you can learn in class,” Nadji said. “You need to go to the laboratory.”

More experienced scientists tend to go abroad to participate in projects with more stable funding, which offer higher salaries. Nadji grew up in Algeria but moved to France to complete his PhD. He worked at the Laboratoire pour l’Utilisation du Rayonnement Electromagnetique, or LURE, and more recently helped build the Soleil synchrotron near Paris.

SESAME is located near Amman, Jordan.

Nadji said he enjoys the teaching aspect of his job at SESAME.

“These are inexperienced people,” he said. “But if they have confidence in you, it’s a very good atmosphere. Every day at the end of the day, I think I did something good because I told this one about a strategy he didn’t know or because I know that one can manage something on his own now.”

Despite their freshness, members of the SESAME collaboration are not content simply to rebuild the German synchrotron. They plan to upgrade the accelerator to run at 2.5 gigaelectronvolts, up from its original 0.8 GeV.

The improvement necessitates a storage ring about twice the size of the original and raises the cost of building the accelerator from its original estimate. But it will make SESAME competitive with other synchrotrons around the world, an important factor in attracting veteran scientists to use the machine.

Read more about the origins of SESAME in symmetry.

Kathryn Grim

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Physicists hold first international particle accelerator conference

May 24, 2010 | 10:27 am

For decades, scientists from laboratories and universities around the world have worked together to build and operate particle detectors.

Until recently, accelerator physicists have done just the opposite, working predominantly with fellow scientists at the same institution to build their machines.

This week hundreds of accelerator physicists have gathered in Kyoto, Japan, to take part in the first International Particle Accelerator Conference, taking a step toward the practices of their detector-building colleagues. “Any new accelerator will surely need to be built in an international collaboration,” said Katsunobu Oide, chair of the IPAC 2010 organizing committee, in his introductory remarks.

Detector builders expect to work with collaborators from outside their institutions. If a particle physicist wants to take part in an experiment, he or she must take some responsibility for the detector by helping with construction or taking shifts running it.

There is no similar expectation that the scientist help build or run the accelerator that delivers particles to the detector. The physicists, engineers, and technicians that do this historically have had little assistance from outside the host institution.

One reason for this is that operating an accelerator is more complicated than operating a detector, Oide said.

“A detector is more of a passive device,” he said. “Once you build it, you use it.” The major work takes place during construction.

But an accelerator requires constant, specialized attention. “It cannot be automatic if you want cutting-edge performance,” he said.

Those who run particle accelerators need to work in close proximity to the accelerator so that they can investigate if something goes wrong. The philosophy has been that if locals are going to operate the accelerator, they might as well build it, too.

But particle accelerators have grown larger and more complex over time. It is no longer feasible for a single institution to provide the manpower and funding necessary to complete construction.

The Hadron Electron Ring Accelerator, or HERA, completed in 1992 at DESY in Hamburg, Germany, was the first accelerator to receive a significant in-kind contribution from a collaborating institution. Italian scientists built half of its 416 superconducting dipole magnets.

Since then, multiple institutions have worked together on accelerators such as the Large Hadron Collider and Europe’s XFEL. Proposed future accelerators such as the International Linear Collider, the Compact Linear Collider, and the muon factory are set to follow this trend.

This week, accelerator scientists at IPAC 2010 hope to find new ways to capitalize on the advantages and manage the disadvantages that the new experience of working as a team can bring.

Kathryn Grim

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The ATLAS Experiment: Popping up next month across North America (and on Tuesday in NYC)

May 20, 2010 | 1:59 pm

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 changes to text and design, as well as some enhanced pop-up action to better represent the Large Hadron Collider and ATLAS detector. The new edition of the eight-page book will be available from major bookstores and online retailers in the United States and Canada starting at the end of June.

LHC-philes (and pop-up aficionados) in the New York City area can get a sneak preview of the book and learn more about the world’s most powerful particle accelerator at a special event next Tuesday evening, May 25 at the New York Academy of Sciences. “Pop-Up Particle Physics from the Large Hadron Collider” will feature a panel discussion moderated by Alan Alda, book-signing and reception. Panelists will include Harvard theoretical physicist Lisa Randall, ATLAS physicist and Columbia University professor Michael Tuts, and book author Emma Sanders from CERN.

Katie Yurkewicz

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Fermilab scientists find evidence for significant matter-antimatter asymmetry

May 18, 2010 | 1:25 pm

The DZero collaboration has found evidence for a new way in which elementary particles break the matter-antimatter symmetry of nature. This new type of CP violation is in disagreement with the predictions of the theoretical framework known as the Standard Model of particles and their interactions. The effect ultimately may help to explain why the universe is filled with matter while antimatter disappeared shortly after the big bang. Credit: DZero collaboration

Scientists of the DZero collaboration at the Department of Energy’s Fermi National Accelerator Laboratory announced Friday, May 14, 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 particle physics. The new result, submitted for publication in Physical Review D by the DZero collaboration, an international team of 500 physicists, indicates a one percent difference between the production of pairs of muons and pairs of antimuons in the decay of B mesons produced in high-energy collisions at Fermilab’s Tevatron particle collider.

The dominance of matter that we observe in the universe is possible only if there are differences in the behavior of particles and antiparticles. Although physicists have observed such differences (called “CP violation”) in particle behavior for decades, these known differences are much too small to explain the observed dominance of matter over antimatter in the universe and are fully consistent with the Standard Model. If confirmed by further observations and analysis, the effect seen by DZero physicists could represent another step towards understanding the observed matter dominance by pointing to new physics phenomena beyond what we know today.

Using unique features of their precision detector and newly developed analysis methods, the DZero scientists have shown that the probability that this measurement is consistent with any known effect is below 0.1 percent (3.2 standard deviations).

“This exciting new result provides evidence of deviations from the present theory in the decays of B mesons, in agreement with earlier hints,” said Dmitri Denisov, co-spokesperson of the DZero experiment, one of two collider experiments at the Tevatron collider. Last year, physicists at both Tevatron experiments, DZero and CDF, observed such hints in studying particles made of a bottom quark and a strange quark.

When matter and anti-matter particles collide in high-energy collisions, they turn into energy and produce new particles and antiparticles. At the Fermilab proton-antiproton collider, scientists observe hundreds of millions every day. Similar processes occurring at the beginning of the universe should have left us with a universe with equal amounts of matter and anti-matter. But the world around is made of matter only and antiparticles can only be produced at colliders, in nuclear reactions or cosmic rays. “What happened to the antimatter?” is one of the central questions of 21st–century particle physics.

The DZero result is based on the comparison of the distributions of positively and negatively charged muons (μ+ and μ-) emerging from high-energy proton-antiproton collisions produced by the Tevatron particle collider. A strong magnetic field inside the DZero particle detector forces the muons that emerge from those collisions to travel along a curved path. Two muons with opposite charge follow paths that curve in opposite direction (see graphic). Scientists first compared the muon distributions when the the magnetic field inside the DZero detector pointed in one direction (configuration 1) and then compared their distributions when the magnetic field had been reversed (configuration 2). If the matter-antimatter symmetry were perfect, the comparison of the muon distributions in the two configurations would yield the same result. Instead, the DZero experiment observed a one-percent deviation, evidence for a matter-antimatter asymmetry. Credit: Fermilab

To obtain the new result, the DZero physicists performed the data analysis “blind,” to avoid any bias based on what they observe. Only after a long period of verification of the analysis tools, did the DZero physicists look at the full data set. Experimenters reversed the polarity of their detector’s magnetic field during data collection to cancel instrumental effects.

“Many of us felt goose bumps when we saw the result,” said Stefan Soldner-Rembold, co-spokesperson of DZero. “We knew we were seeing something beyond what we have seen before and beyond what current theories can explain.”

The precision of the DZero measurements is still limited by the number of collisions recorded so far by the experiment. Both CDF and DZero therefore continue to collect data and refine analyses to address this and many other fundamental questions.

“The Tevatron collider is operating extremely well, providing Fermilab scientists with unprecedented levels of data from high energy collisions to probe nature’s deepest secrets. This interesting result underlines the importance and scientific potential of the Tevatron program,” said Dennis Kovar, Associate Director for High Energy Physics in DOE’s Office of Science.

The DZero result is based on data collected over the last eight years by the DZero experiment: over 6 inverse femtobarns in total integrated luminosity, corresponding to hundreds of trillions of collisions between protons and antiprotons in the Tevatron collider.

“Tevatron collider experiments study high energy collisions in every detail, from searches for the Higgs boson, to precision measurement of particle properties, to searches for new and yet unknown laws of nature. I am delighted to see yet another exciting result from the Tevatron,” said Fermilab Director Pier Oddone.

DZero is an international experiment of about 500 physicists from 86 institutions in 19 countries. It is supported by the U.S. Department of Energy, the National Science Foundation and a number of international funding agencies.

Fermilab is a national laboratory funded by the Office of Science of the U.S. Department of Energy, operated under contract by Fermi Research Alliance, LLC.

Press Release

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Neutrinos: a fishy explanation

May 18, 2010 | 1:13 pm

Collaboration members for the NOvA neutrino experiment held public tours of the future site of the NOvA detector facility the weekend of Minnesota’s annual Governor’s Fishing Opener. Aside from proximity of the site to the opener, held on Lake Kabetogama, does the experiment have anything to do with fishing? Maybe. Fishing guide Frank House and physicist Mark Messier explain.

Kathryn Grim

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Minnesota governor visits NOvA site

May 17, 2010 | 8:29 pm

Saturday, May 15, marked a state holiday in Minnesota. Enthusiasts headed north to the annual Governor’s Fishing Opener, the first day of the fishing season, in search of Minnesota’s state fish, the walleye.

On Friday, Minnesota Gov. Tim Pawlenty stopped to visit Minnesota residents and visitors interested in a different type of catch: neutrinos.

Pawlenty took a quick tour of the future site of the NOvA neutrino detector facility in Ash River, Minn. The facility is not far from where Minnesotans cast their lines during this year’s opener, Lake Kabetogama. Scientists and those managing construction held public tours on Friday before welcoming the governor.

Pawlenty expressed his support for conducting the research in Minnesota. But he didn’t stay long; the afternoon clouds had begun to clear just in time for the Fishing Opener community picnic.

Kathryn Grim

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Looking at the Galaxy Zoo with (gravitational) lenses

May 14, 2010 | 1:00 pm

An example gravitational lens from the SDSS data set. This image is known as the 8 o'clock arc.

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, thanks in part to the efforts of Phil Marshall at SLAC and Stanford’s Kavli Institute for Particle Astrophyics and Cosmology.

Galaxy Zoo, which has been running for three years, is now turning to the Hubble Space Telescope for data, coinciding with HST’s 20th anniversary. The original Galaxy Zoo project allowed people to comb through mountains of image data from the Sloan Digital Sky Survey, a ground-based telescope system in New Mexico. The “Zooites,” as these 21st century amateur astronomers are known, are able to classify galaxies accurately and efficiently, thus taking part in a massive scientific project and unloading a lot of work from professional astrophysicists. From the very beginning, the Zooites started spotting new and unusual objects–including gravitational lens candidates, on a discussion forum thread started by the Zoo’s instigator, Kevin Schawinski.

The website leads visitors through a questionnaire that helps them learn to properly identify galaxy types, such as elliptical or spiral. Marshall, who studies strong gravitational lenses, and Chris Lintott, Galaxy Zoo principal investigator, realized they could help the Zooites spot lenses more efficiently by adding an additional question to the procedure. This resulted in users identifying several thousand Galaxy Zoo galaxies that show potential lensing-like features. From this large list, Aprajita Verma, who is leading the follow-up investigation from Oxford, selected 20-30 good gravitational lens candidates for further observation.

“We know that lenses are very rare,” Marshall says. Now, Galaxy Zoo is providing a number of tools to allow the zooites to whittle down their list of lens candidates themselves. “We hope that ‘crowd-sourcing’ this problem will provide a more complete sample of gravitational lenses than could be generated blindly by computer.”

With the addition of the Hubble data, scientists have a plethora of new galaxies to sort – galaxies that are much younger and further away because of Hubble’s increased scope. Considering there are nearly 250,000 users of Galaxy Zoo, they have plenty of help!

by Julie Karceski

You can see more about gravitational lenses in this short film explaining how to make your own.

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National Lab Day brings Fermilab physics to students

May 12, 2010 | 12:06 pm

Fermilab scientist Al Sondgeroth demonstrates force and motion to students from Annunciation BVM School in Aurora.

“I want to try, too!” This was the chorus that rang out across Jennifer Wardynski’s sixth grade class last Tuesday, when Fermilab’s Al Sondgeroth got students involved in a demonstration of angular momentum at Annunciation BVM elementary school in Aurora.

Sondgeroth was one of 20 Fermilab volunteers who gave hands-on presentations in area elementary and high schools last week to celebrate National Lab Day. His presentation gave students an opportunity to experience Issac Newton’s laws in action.

“It helped bridge the gap between the abstract concepts of physics and real-world applications that are all around us,” Wardynski said.

In addition to Sondgeroth’s presentation on force and motion, volunteers talked about topics such as electricity and magnetism, light and color and the physics of sports.

On Thursday, Fermilab Deputy Director Young-Kee Kim spoke to the young women in teacher Falguni Soni’s chemistry classes at Rosary High School. Her visit to Rosary was prompted in part by the interest of sophomore Emily Launer, who wrote a prize-winning research piece on the history of Fermilab.

Kim discussed the field of particle physics and some of the scientific mysteries that Fermilab pursues. She also encouraged the girls who have an interest in science and advised them not to be daunted by a field historically dominated by men.

Many of the students said the presentation helped them relate the science that they are learning about in the classroom to the physics at Fermilab.

“It was all really interesting,” said junior Mary LeDoux. “I had heard some of the information about science done at Fermilab before but it really helps to hear it all again because these are very deep concepts.”

National Lab Day is a response to President Obama’s call to encourage students across the country to learn about math, science, technology and engineering. Over the course of the week, Fermilab presentations reached about 2500 elementary and high school students.

by Daisy Yuhas

This story first appeared in Fermilab Today on May 12, 2010.

Symmetry Intern

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