At the LHC, repaired magnets are powered up for the first time

April 29, 2008 | 10:41 pm

Thirteen months after a testing failure revealed serious design flaws in nine sets of “inner triplet” magnets for the Large Hadron Collider, engineers switched on the first of the repaired sets, ran it for an hour and subjected it to a highly stressful test that, in the words of Fermilab’s Jim Kerby, “releases a lot of energy, so if something is going to shake loose or be a problem, this is one event that could cause it to happen.”

The magnets performed just fine, to the great relief of about 50 scientists, engineers and technicians who worked on the repairs and countless others who made substantial contributions. Kerby reported the results Friday in an email, and Fermilab Director Pier Oddone described them Tuesday in a column entitled “Triplet Crown:”

A crown is what the folks who have worked over the last year to get the LHC triplets ready for operations at the Large Hadron Collider deserve… This is the first time that a triplet has worked at specifications (equivalent energy of 7 TeV) as a system of three magnets with all its power and cryogenics interconnections in place. We have come a long way from where we were a year ago.

“It’s a combination of relief and a thrill,” Kerby told me in a phone interview from CERN, the European particle physics laboratory on the Swiss-French border where the LHC is scheduled to turn on this summer. “There’s been an awful lot of hard work by an awful lot of people to get this far, and it’s a thrill to see it come together, finally.”

There are eight sets of inner triplet magnets in the LHC (the ninth is a spare.) Their job is to focus the particle beams into the four areas where particles will collide.

Within each set, two of the magnets, called Q1 and Q3, were designed at Japan’s KEK laboratory and built by industry. The third, Q2, was designed and built at Fermilab.  Fermilab also assembled all the magnets into cryostats and shipped them to CERN.

In March 2007, researchers subjected one of the inner triplets to some of the most extreme conditions they can expect to face during normal operations.  Superconducting magnets like these have to stay very cold in order to conduct electricity without any resistance.  If even a small part of the magnet “goes normal”–loses its superconductivity, and begins to resist the flow of current–this releases a lot of energy in a very small space, which can damage or even destroy the magnet. These events are known as quenches, and while they might seem a bit scary, they do occur from time to time during the running of a collider. In response, heaters fire up and and heat up the whole magnet, dissipating the energy over the magnet’s entire volume so it does no harm.

After the first set of inner triplets failed the quench test, investigators quickly found the problem: Certain support structures for the magnets were not designed to withstand the longitudinal forces they experienced during testing. These supports have been repaired, along with other equipment damaged by the test failure.

On Thursday night, Kerby and his team ran a normal operating current through a set of inner triplet magnets for the first time.  “It went to nominal operating current and came back down without a problem, which is good,” he said. “This is what we want.”

They powered the triplets up again and fired the quench protection heaters. “This is a big jolt,” Kerby said.  Again, the magnets passed.

Finally–by now it was Friday, Geneva time–the crew powered up the magnets again and ran them for an hour.

Kerby, who is a mechanical engineer, has been involved in the design of the magnets from the beginning.  He became the Fermilab project leader in in 1998 and is now the US LHC accelerator project leader.

Although the original test failure was not exactly pleasant, he says, it was far better than the alternative–discovering the problem after the collider is already in operation.

“The best thing you can do is tackle the problem head-on.  If there’s a goof, you fix it,” he said. 

Kerby said it was especially gratifying to see the way people from so many places–including Fermilab, KEK, CERN, the US Department of Energy and Brookhaven and Lawrence Berkeley national laboratories–stepped forward to help find a solution.

“That part is just spectacular,” he said. “You call on the expertise of various people–not just the design people or the people to fix it, but the procurement people, who in our case happen to be at Fermilab.  I probably got only a small fraction of their time, but for that fraction they knew exactly what they needed to do, and really pulled it off.” And that, he said, is just one of many examples.

Of the eight inner triplets in the LHC, he said, all but one have been successfully pressure tested.  Four are chilled nearly down to operating temperature, and another is on its way.

 As for the powering-up tests, he said, “One down, seven to go.”

Glennda Chui

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Precision atomic measurements

April 29, 2008 | 12:00 am

Scientists have learned to measure stuff really precisely. So precisely that the uncertainties in some of their measurements are down to the level of parts per billion, which is like being able to measure the diameter of the Earth to within the thickness of a human hair. Some specific measurements do so much better than that that it boggles the mind.

Being able to measure things so precisely means that scientists can make serious tests of some of the basic assumptions we have about the universe we live in. For example, has the electron always had the same mass since the beginning of time? Or does it vary slightly? Has the speed of light always been the same?

The meaning of change

If these quantities, which we assume to be constant, change over time, then our entire structure of physics has some flaws buried deep down in the heart of it. It would be possible to correct those flaws but it means we are playing a much harder game if we are trying to understand the universe.

Because this question is critical to our deepest understanding of science, and also has pretty significant philosophical ramifications as well, scientists need to test all our basic assumptions.

Electrons and protons

I came across a couple of new papers published in Physical Review Letters that touch on this topic and thought I’d point out the results here because of the significance of this work to the foundations of physics and particle physics. I also find some of this work interesting because it sits in between particle physics and AMO (atomic, molecular, and optical) physics.

The first of the papers looks at the ratio of the electron mass to the proton mass. The proton has a mass 1836 times greater than the electron. (Actually, it is not exactly that-there are a bunch of extra decimal places -but it is this rounded number that is burned into my brain from a physics degree!) This ratio has been tested in a variety of ways over the years. The tests range from astronomical to geological, spanning vast time frames, but also laboratory tests looking at the emissions of light from atoms and molecules, where the frequency of emissions changes in time depending on the change in the mass ratio.

Previously, none of these tests had been “pure” in the sense that they were independent of any assumptions about how some parts of atomic, nuclear, astrophysical, or geological physics works. The new test compares the molecular vibrations of sulfur hexafluoride with the atomic vibrations of cesium. I can’t get very far in telling this story without it becoming seriously technical so I won’t give you the gory details. The end result, however, is that the electron/proton mass ratio is stable to less than a change of four parts in 100 trillion per year. That’s pretty stable! Of course that test happens in a laboratory and was conducted over a timeframe of “only” two years. The physicists point out that this type of result needs to be compared with observations on cosmological timescales.

The tiny magnet that is an electron

The supposedly pure vacuum of empty space is actually a place teeming with activity. It’s not that there is any matter floating around there, but the nature of quantum physics says that there is a bustle of particles temporarily popping in and out of existence, in a way such that you can essentially never detect those particles directly. However, if you put another particle in the vacuum, it is affected, very very slightly.

For example, put an electron in a vacuum and the strength of its magnetism is changed by about one part in a thousand. That is just due to the presence of other electrons and positrons (or other pairs of particles) popping into existence, messing with the electromagnetic fields around the electron and then disappearing again, like sly pranksters who’d sneak into your home, rearrange the cutlery drawer, and take off again leaving no other trace. They don’t want to reveal their identities, just their presence.

The best measurement of the electron’s magnetic moment, as it is called, remained the same for nearly 20 years, until 2006, when some new measurements and new theoretical calculations improved the value. Now a mere two years later, that record has been broken again. (We tangentially mentioned the 2006 record breaking in symmetry.)

The work was done in a device that has been around for most of a century, but scaled down to miniature size. A cyclotron (see the cover of this symmetry for the first one ever) was built to contain a single electron and measure its movements in a magnetic field extremely precisely. The result is three times more precise than the 2006 record and comes in at a mere 0.28 parts per trillion.

Is the electron a detector for dark matter?

So why do we care about this value? It is so precise that if it differs from theoretically predicted values, physicists could discover all kinds of new physics, from finding that the electron is actually made up of smaller components to maybe even finding signs of a dark matter particle. (Aha! It’s the dark matter that rearranges my cutlery at night!)

The trouble with making any claims about new physics is that the theory needs to catch up and physicists need an independent measurement of other related properties of the electron. Still, with all these measurements getting more precise, perhaps we’ll be seeing some pretty amazing particle physics discoveries from benchtop experiments to complement the discoveries imminent at the Large Hadron Collider.

David Harris

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Accelerator Ladies' Night

April 25, 2008 | 12:04 pm

What better place to learn about particle physics and accelerator technology than the basement of a bar in Tokyo? The “Accelerator’s Nights” seminars put on there by Kenichi Kojima, who operates a sort of field-trip club for adults, draw regular crowds. On April 14, a special edition of the seminar featured an all-woman panel talking about gender equality in Japanese science and society, and what it’s like for a woman to do physics there.

The panelists were Fukuko Yuasa, a physicist who is responsible for network security at KEK, the international high-energy research organization in Tsukuba; Miho Nishiyama, a doctoral student at Shinshu University who is working on technology for a future International Linear Collider, or ILC; and Rika Takahashi, ILC communicator for Asia.

Junpei Fujimoto, a particle simulation specialist at KEK, described the evening in the ILC NewsLine:

One of the main topics was the gender-equal society. At KEK, the number of women scientists is only 5%, which is low compared with European institutes. Yuasa talked about the daily life of a woman physicist. Her husband is also a physicist of KEK. “My husband and I live like cooperative researchers at home. We usually have a lunch meeting at the cafeteria, planning what to do for the day. We share our housework, for example, I cook, and he does the dishes.” This may not sound so special; however, sharing the housework is still not so common in Japan. “Well, he uses a dishwasher, but he seems to have a strategic and well organised way to store dishes in it with the mind of a physicist,” she said.

Co-moderator Ayo Kaida, is a novelist with an enthusiasm for particle physics–and a flair for explaining difficult concepts in plain language.

Here’s her take on the calorimeter, which measures the energies of particles entering a detector:

Kaida told the audience to imagine a flying potato in the central tracker. At the boundary between the tracker and the calorimeter, there exists a fine mesh to make mashed potatoes. The calorimeter located behind the mesh will re-collect the very finely mashed potato as much as possible and reconstruct the original mass. This is the principle of the calorimeter that measures the energy of particles.

As for the difference between neutrinos streaming from the sun and those generated in accelerators:

… she immediately interpreted the neutrinos from the Sun as ‘wild fishes’ and the ones from KEK to Super-K as ‘cultivated fishes’. You know that Japan has a long culture of eating fish, thus Japanese are quite sensitive for ‘wild’ or ‘cultivated’.

The event was sponsored by the ILC Fan Club, which was formed on the Web by two women who learned about the project while on a field trip to KEK. It now has 60 members.

Co-founder Etsuko Iwasaki said:

“I have been a big fan of science-fiction novels and movies. I am expecting the ILC to make the sci-fi world come true.”

Glennda Chui

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Particle physics news in weekly digests

April 24, 2008 | 5:20 am

If you are a fan of particle physics, you have probably come across the interactions.org Web site, where you can find all kinds of news and resources about particle physics including the ever-useful image bank.

You might not know about the weekly digest of news stories, press releases, new images, and other featured items, but you can subscribe to receive the weekly update.

Although we’d love to think symmetry magazine is the only resource you need to stay in touch with particle physics, this is the place we go to to make sure we know what is happening, especially when we want to check out news coverage of particle physics from around the world.

David Harris

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The first oil paintings?

April 23, 2008 | 5:30 am

Hundreds of years before Europeans supposedly invented oil painting, ancient Buddhists were using a primitive form of the method to paint murals in the Bamiyan caves of Afghanistan, according to the results of a study announced yesterday; Nature has a news story here. The murals, hidden behind massive statues of Buddha, were defaced when the Taliban destroyed the statues in 2001.

The results from the European Synchrotron Radiation Facility mark the latest finding in light source science, a truly fascinating area that continues to shed light on the past.

Early this month, the lab announced that paleontologists are using synchrotron X-rays to study spiders, wasps, and other “wee beasties” preserved inside opaque chunks of ancient amber. They convert their data into plastic replicas of the fossilized creatures. One researcher said the models, which are much larger than the actual animals and can be manipulated by hand, are better than having the real thing.

And in 2006 another landmark experiment at SLAC used X-rays to reveal a 10th-century copy of 2000-year-old works by Archimedes.  The original writing had been scraped off pieces of parchment and covered with other writings.  It was by far the oldest copy of works by the great mathematician. symmetry has a story on that here.

Matt Cunningham, symmetry intern

Guest author

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Orbach urges hope for a brighter HEP future

April 22, 2008 | 4:04 pm

Dr. Raymond Orbach visited Fermilab Tuesday to learn about the laboratory’s advances and long-range plans as well as to offer support for its future for decades to come.

The DOE Under Secretary for Science told a crowd of nearly 1000 that they, and American science as a whole, face a critical time where America must decide whether it wants to remain a leader of nations.

The President in his State of the Union address continued to support science, Orbach said. The long-range plans under formation by the Department of Energy and the Particle Physics Project Prioritization Panel, or P5, also support the continued success of Fermilab.

“In my view, we have worked together to come up with a plan for high-energy physics that will support Fermilab for decades to come,” Orbach said.

The P5 plan is due in early May, and Congress will get the first five years of the DOE plan this summer.

Orbach stressed that the efficiency, attention to safety, and productivity of Fermilab, especially in the face of budget cuts, give Congress confidence that the laboratory can use the money it requests wisely. Orbach particularly praised the Tevatron’s increase in luminosity to more than 300 times above the accelerator’s original design, putting experimenters ever closer to the Higgs boson.

“Your efforts have given you strength for future operations that otherwise we wouldn’t have had,” Orbach said. “I cannot tell you personally how proud I am of Fermilab in the face of such treatment to show what you can do.”

Congress looks closely at past performance when deciding where to invest. Fermilab’s history of getting projects built on time and on budget, as well as producing a top safety record, sends a message that the laboratory is worth Congress’s investment, Orbach said.

He offered no promise for improved FY08 funding, but hope that the future looks brighter. The personal struggles and damage to the United States’ reputation as an international partner caused by the FY08 budget have resonated with Congress, he said.

Scientists, engineers, and technicians must work in tandem with DOE to convince Congress and the American people to pass the President’s FY 2009 budget request and lay the groundwork for a FY 2010 budget that supports HEP.

The HEP community also must work together with the Office of Science to present a 10-year plan that shows the importance of basic science and its budget-driven achievability on which the next administration can build its base of scientific initiatives.

“Every one of us has a responsibility to get the message out about science,” he said.

You can view the entire talk.

Tona Kunz

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Nothing but (Quark)Net

April 22, 2008 | 9:08 am

Science stars and sports stars rarely align, except on the NCAA basketball court. Wanna pick winners for the annual March Madness office pool? Skip the schools’ sports statistics and focus on their QuarkNet science-outreach programs.

Seriously.

For the past decade, employees at Fermilab and the University of Florida have tracked the rankings of NCAA teams compared to QuarkNet participation.

Scientists who give time to the program score big for their universities.

The men’s team from Kansas University, a QuarkNet school, took the title in 2008. Stanford University, a QuarkNet alum, finished second in the women’s championship.

The DOE- and NSF-sponsored QuarkNet program brings high school students and teachers to the frontier of 21st century research by involving them in research programs at the world’s major particle physics laboratories.

High school students and teachers connect with Fermilab and other particle physics research centers through university scientists working on experiments. At Fermilab, they work on the largest US particle detectors, DZero and CDF. For their classrooms, students build cosmic-ray detectors.

In the past decade, on average, a dozen of the 64 teams in each year’s NCAA bracket have had ties to QuarkNet. Half of the last 10 champion men’s teams claim QuarkNet membership.

“That’s pretty cool,” says Spencer Pasero, of Fermilab’s education office. “The QuarkNet men’s teams do better at every stage than expected. The QuarkNet schools in the women’s tournament do better in the first and second rounds and then come back to the field.”

QuarkNet consistently had a higher proportion of men’s teams advancing to the Final Four and women’s teams advancing to the Sweet 16. The men’s teams advance at a rate of one in seven, twice the expected rate. Non-QuarkNet teams advance to the Final Four at a rate of one in 21.

In the first round of play for the last decade, QuarkNet affiliated women’s teams had an 83-36 record and men’s teams a 72-43 record.

Why the basketball success link with science?

“I leave the correlation to the theorists. This is ground-breaking work,” says Tom Jordan, QuarkNet organizer at the University of Florida, who first noticed the trend. “But I have made the comment to a few close QuarkNet mentors, ‘Show this win-lose plot to your basketball coach. Perhaps he can free up some extra support for your science teachers.’”

Advice for the rest of us: If you’re going to bet your office coffee money on something, bet it on science.

QuarkNet in the 2008 NCAA men’s basketball (PDF)

QuarkNet in the 2008 NCAA women’s basketball (PDF)

Tona Kunz

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2007 Topcites Clouds

April 22, 2008 | 5:33 am

Last year a colleague of mine showed me tagcrowd.com, which is a neat way to take a bunch of text and visualize, very roughly, the important concepts in the text. The site performs a frequency analysis of words in the text, and displays it in the intuitive fashion we have all come to know and love when reading blogs or flickr or other tagging sites. However, tag clouds don’t have to be about tags, it can work for any mass of text.

Below, I took the titles of all 51 2007 Topcites from SPIRES (as well as abstracts from 37 of them and keywords from DESY for 27 of them) and threw them at the TagCrowd generator to see what it thought. So without further ado, here is an unintelligent, algorithmic, and probably very biased picture of the important concepts in HEP in 2007.

Travis Brooks

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Fermilab Meson Test Beam Facility begins testing detector

April 21, 2008 | 6:19 am

An important new ILC calorimeter research program was installed in the the Fermilab Meson Test Beam Facility on April 15, 2008. It is the largest detector and test beam program run at the Meson Test Beam Facility to date. The user for this project is the CALICE collaboration, an international ILC detector R&D group that will employ numerous methods of read out for electromagnetic and hadronic calorimetery. As the program moves forward over the next year, various new detector technologies will be swapped into place and tested.

The installation of the CALICE test beam calorimeter marks the continuation of a program that is truly international. Testing of this detector has taken place at CERN and at DESY and components are coming from KEK in Japan.

The Meson Test Beam Facility is a versatile beamline where users can test equipment or detectors in a beam of different particle types in a wide energy range (1-120 GeV) at suitable intensities. It is ideal for the ILC Detector test beam program.

The principle architect of the infrastructure being installed, and the hadron calorimeter project leader, is Felix Sefkow from DESY, and he comments here on this important milestone.

Fred Ullrich

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Midwest earthquake rattles Fermilab

April 18, 2008 | 3:50 pm

On Friday, April 18, at approximately 4:37 a.m., a 5.2-magnitude earthquake shook southern Illinois. It was the second strongest quake in the area in 40 years. Its vibrations were felt across the state, including at Fermilab.

Seismometers at the laboratory recorded the pre-dawn vibrations. Although there were no reports of damage, scientists said they likely would have lost the particle beam inside the Tevatron accelerator if it had been running.

The plot at left shows the reading from a tilt meter that recorded the slight back-and-forth motion of a single Tevatron magnet during the earthquake.

The one at right shows ground motion recorded by the on-site seismometer.

Read more about the quake in Friday’s Chicago Tribune article.

Rhianna Wisniewski

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