LHC weekly update: Feb 27, 2009

February 27, 2009 | 11:34 am

LHC work this week includes cold-testing of more magnets, cryostating of more magnets (fitting the cooling systems to replacement magnets), upgrades to the magnet interconnects (one of which failed last year), and replacements of pressure nozzles throughout the ring to deal with the case of magnet quenches. More technical details here.

CERN has also posted the slides and some talks from the Chamonix LHC performance workshop that examined LHC repairs and recommended a new schedule for operations in the coming year.

David Harris

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Pluto still a planet where Fermilab sits

February 27, 2009 | 10:32 am

Yesterday the Illinois Senate decided enough was enough. No longer would they suffer the implied ignominy caused when the discovery of one of their natural-born sons was so spectacularly demoted in the standing of the most-august International Astronomical Union. And so, in the fashion of all legislatures who are similarly perturbed, they took decisive action.

On the historic twenty-sixth day of the month of February, in the year 2009, the Illinois Senate declared:

Streator lies about 65 miles southwest of Fermilab, as the crow flies, but the resolution takes effect throughout Illinois. At this time Fermilab astrophysicists have made no official statement about the effects on their work.

(Thanks to Govert Schilling for the tip about this, via @govertschilling.)

David Harris

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From Project X to the Higgs particle: AAAS slide set

February 27, 2009 | 10:19 am

Earlier this month, more than 40 scientists and teachers gave talks on particle physics, astrophysics, and cosmology at the annual conference of the American Association for the Advancement of Science in Chicago, one of the largest and most diverse science meetings in the United States. The conference coincided with the winter meeting of the American Association of Physics Teachers.

A Fermilab Web site now offers pdf and PowerPoint files of most of these presentations. Highlights include a session on Project X and physics at the intensity frontier; the hunt for the Higgs particle at the Tevatron and Large Hadron Collider experiments; and particle physics experiments for high school students. Craig Dukes’ talk gives a great explanation of what scientists hope to learn from Project X.

Kurt Riesselmann

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Neutrinos, Chastinos: Meet Tom, Dick, and Harry

February 26, 2009 | 10:07 am

Boris Kayser, a theoretical physicist at Fermilab, was part way into a Feb. 13 talk at the AAAS meeting in Chicago about the role of neutrinos in the evolution of the universe. He asked, are neutrinos the reason we exist? Maybe so–if, as some theorize, these ethereal particles were responsible for the triumph of matter over antimatter in the early universe.

He went on to explain that neutrinos come in three types, or flavors: the electron neutrino, the muon neutrino, and the tau neutrino, each denoted by the Greek letter ν followed by a number. But let’s just call them Tom, Dick and Harry.

Huh?

Kayser says he got the idea from the cover of the May 2007 isssue of symmetry, which featured a guide to subatomic particles, real and imagined, by New Yorker cartoonist Roz Chast. More of her cartoons are inside the issue, illustrating an article on the search for dark energy.

He said he always hated the rather sterile Greek-letter names of the neutrinos. So for a public lecture in Aspen in January 2008, he asked Chast for permission to use some of the symmetry cartoons in his slides, and he called the neutrinos by their Chastian monikers.

“I would rather the names be more poetic than Tom, Dick, and Harry,” he said, “but I’d rather have Tom, Dick, and Harry than the first, second, and third one.”

He said he was a bit apprehensive at first: Would the audience go for the pictures and not the physics?  But, he said, ”it turned out very well.”

Glennda Chui

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R&D a must for America's future

February 25, 2009 | 4:20 pm

On the eve of Congress voting on the FY2009 budget, “R&D Daily” had a somber comparison of how the United States and China view research investment.

While the article focused mainly on private-industry investment, its overall message of the need to look long-term applies to government funding just as well. It is a message President Barack Obama has touted: the need to look past the next election cycle, and not just put out current economic fires.

In the face of such upheaval I would imagine most companies would continue to keep close counsel about R&D expenditures.

Not so the Chinese. R&D Global Funding Forecast, which was published in December 2008, predicts China will move gross domestic R&D funding up about 16% this year. That’s about $20 billion, or almost as much as Russia’s entire R&D expenditure. And most of this increase will come from industry (although many of these companies are government-owned).

The U.S. is expected to bump R&D spending by about $6.6 billion, but that’s a much smaller percentage of a much larger R&D pie, more than 2.5 times China’s. Will R&D expenditures remain a strategic priority? Of course. Nobody wants to miss the crest of an eventual return of consumer confidence and for the moment cuts will be reflected more in reduced energy and resource usage and, as we have seen, sharp reductions in workforce.

… But message is there: many Asian countries, including India and Korea, are ignoring their economic woes and will likely be eager to occupy any R&D vacuum we don’t want to fill.

The article stresses the need to prepare the country for economic vibrancy down the road by funding research today. Obama has stressed that basic science is a key component of paving that pathway to future job security.

Traditionally, basic science has led to the game-changing leaps in technology that have produced new industries and jobs.

On this front too, the United States seems to be falling behind. A New York Times article quoted several studies tracking America’s slide in global prominence for innovation and competitiveness, particularly in regards to science and technology.

A report last year by the Rand Corporation concluded that the United States was in “no imminent danger” of losing its competitive advantage in science and technology.

The new report, published on Wednesday, offers a more pessimistic portrait. Its assessment is in line with a landmark study in late 2005, “Rising Above the Gathering Storm,” by the National Academies, the nation’s leading science advisory group. It warned that America’s lead in science and technology was “eroding at a time when many other nations are gathering strength.”

Tona Kunz

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Why the dark side of the universe matters

February 24, 2009 | 3:45 pm

The world we see, including ourselves, barely makes a dent in the universe or our understanding of it. The 4 percent of the universe that is visible matter fails to shine a light on how the universe evolved or why galaxies spin the way they do. Those answers lie instead just out of reach of our understanding in the dark patches of the cosmos: the so called dark matter.

But year by year during the last decade scientists have inched their flashlights closer to this dark matter threatening to uncover its constitutes and how it works.

“Most of the matter in our universe, about 85 percent, is not explained. It is not stars or planets or dust or gas,” said Fermilab physicist Mike Crisler at the 2009 meeting of the American Association for the Advancement of Science in Chicago. “It is not made from atoms or molecules, protons, neutrons, or electrons. It does not absorb or emit light. We use the phrase “dark matter” in much the same way that ancient cartographers used the phrase ‘terra incognita.’ We do not know its nature.”

Even though we can’t “see” dark matter, we infer its presence because of its gravitational pull, affecting the rotation speed of stars and galaxies. Stars are moving faster than they would if they were only influenced by the gravitational pull of the galaxy core, so the galaxy itself must be embedded in large clouds of dark matter exerting another pull.

The power of the dark side

Luminous matter accounts for only about 4 percent of the universe.

Scientists believe that without dark matter, galaxies would fly apart, the universe wouldn’t have formed, and galaxies wouldn’t cluster.

“Until we find this stuff, we can’t really say that we understand gravity,” said Dan Akerib, a physics professor from Case Western Reserve University in Ohio, at another AAAS talk on dark matter.

While the discovery of what makes up dark matter wouldn’t change our everyday lives, it would change our perspective about the world, Crisler said.

“I think it would be a dramatic moment philosophically about the human role in the history of the universe,” said Crisler.

Scientists across the globe are racing to make dark matter in the laboratory, see it in the sky, and catch it in deep underground caverns.

“This is a very active field. There are experiments being done in the United States, Europe, Asia,” Akerib said. “During the last decade the sensitivity has increased by a factor of 100.”

If that continues, the next five to 10 years could hold key discoveries, he added.

The AAAS talks highlighted upgrades in two of those experiments at Fermilab in Illinois that use temperature extremes to search for dark matter–the Chicagoland Observatory for Underground Particle Physics, COUPP; and the Cryogenic Dark Matter Search, CDMS.

COUPP bubble chamber

COUPP

Scientists first used superheated liquid in bubble chambers in the 1960s, but their use died out in the 1980s. COUPP revived and upgraded the bubble chamber and gave it a new use: the search for dark matter.

“Bubble chambers may be the next big thing in dark matter detection,” said Crisler.

Bubble chambers effectively trace the interactions of weakly interacting massive particles, or WIMPs, with normal matter. Scientists believe the abundance of WIMPs left over from particle collisions just after the big bang may account for dark matter, Crisler said.

Mike Crisler adds a one-liter jar to the COUPP bubble chamber.

The liquid in a bubble chamber—typically hydrogen—is kept just above its normal boiling point, but under enough pressure that it will not boil unless disturbed. When a charged particle zips through the liquid it triggers boiling along its path, visible as a series of small bubbles. The biggest limitation for bubble chambers of the past was an inability to keep the liquid in a superheated state for an extended period of time. This required operators to time short blasts of particles from an accelerator to the few milliseconds when the temperature was just right. The COUPP collaborators got around this by finding a way to keep their liquid on the verge of boiling 80 percent of the experiment time, increasing the probability of catching dark matter particles.

Crisler and his colleagues recently upgraded a one-liter bubble chamber to block out more background noise and are almost finished constructing a 30-liter chamber, which will increase the probability of dark matter interactions. The current bell jar-shaped bubble chamber sits 350 feet underground at Fermilab and is filled with iodotrifluoromethane.

CDMS

At the opposite end of the temperature spectrum, CDMS uses cryogenics rather than super-heated liquid to pin-point WIMPs.

CDMS fridge and icebox in Soudan Mine.

When particles interact they can give off energy, which registers as heat. Scientists super cool the detector so that it conducts electricity without resistance. When energy is released from an outside particle colliding with a particle in the detector, it warms up part of the detector, briefly removing its superconductivity ability, and allowing scientists to see an electrical charge.

By measuring the difference in voltages associated with the temperature increases from an interaction, scientists can determine if the particle was a WIMP or a more common particle not associated with dark matter. WIMPs produce a low-charge yield while electron recoil from a photon has a large-charge yield.

ZIP detector in its mount.Silicon and germanium ZIPs, weighing 100 g and 250 g respectively, will be used in CDMS II.

The CDMS detector has been taking data since 2003 in the Soudan Mine in Minnesota with a 5 kg of active detector mass. An upgraded detector, with 25 kg of active detector mass and four times more sensitivity to particle collisions, is under construction. It will consist of seven stacks of six detectors, creating what Akerib calls the equivalent of a dark matter telescope underground.

Each type of technology used to search for dark matter has its strength. Which will prove the most useful remains to be seen.

CDMS and COUPP are racing other experiments in the United States, Europe, and Asia to find dark matter with accelerators, various types of underground detectors and telescopes.

“The search for dark matter is a horse race…,” Crisler said. But many physicists see the finish line in sight.

With additional reporting by Kristine Crane.

Tona Kunz

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LHC weekly update: Feb 20, 2009

February 20, 2009 | 1:02 pm

In this week’s update from the LHC, CERN reports that all replacement magnets to be installed in the LHC this year have been fitted with cryostats (the insulating vessel that allows the superconducting magnets to be chilled to close to absolute zero).

In the tunnel itself, workers are repairing the connections between the superconducting magnets and the pipeline that supplies them with liquid helium that were damaged in last September’s incident; these repairs should be complete within one month.

The replacement for a problematic superconducting magnet from another sector of the LHC is in place and workers are now connecting it to its neighbors.

Technical details from CERN.

Katie Yurkewicz

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Most extreme gamma-ray blast also probes quantum gravity

February 19, 2009 | 2:01 pm

GRB 080916C's X-ray afterglow appears orange and yellow in this view that merges images from Swift's UltraViolet/Optical and X-ray telescopes. Credit: NASA/Swift/Stefan Immler

A paper published today in Science Express details the most extreme gamma-ray blast ever observed, seen by the Fermi Gamma-ray Space Telescope. While I am sure this will make plenty of news around the world, the aspect I find most interesting isn’t the mere superlative native of the blast, but the science that comes from it.

In particular, the details of the blast place the tightest constraints yet on the constancy of the speed of light at different energies. This is important for the development of theories of quantum gravity, as many flavors of those theories predict that the speed of light does actually change with the frequency/color/wavelength of light. (So far, there has been no experimental evidence to suggest the speed of light changes, but it is possible for there to be small changes in the speed of light, consistent with everything that has ever been observed.)

The gamma rays from the burst came in spread out over 16.5 seconds. This time delay could be due to gamma-rays being emitted from different regions of space, some slightly closer to us than others. However, assuming that the gamma rays were all emitted from the same place at the same time, this spread of arrival times gives a maximum speed difference between the different gamma-ray energies. Doing the most conservative calculation possible shows that any change in the speed of light must be no more than a certain limit, and that limit is the tightest yet measured. (The assumption that the gamma rays come from the same place makes the constraint the most conservative, rather than invalidating this kind of conclusion.)

This movie compresses about 8 minutes of Fermi LAT observations of GRB 080916C into 6 seconds. Colored dots represent gamma rays of different energies. Visible light has energy between about 2 and 3 electron volts (eV). The blue dots represent lower-energy gamma rays (less than 100 million eV); green, moderate energies (100 million to 1 billion eV); and red, the highest energies (more than 1 billion eV). Credit: NASA/DOE/Fermi LAT Collaboration

Interestingly, this technique could be used to search for changes in the speed of light, called Lorentz violation in the argot. If the spread is due to spatial separation of the bursting elements, then the time delay between the start and end of the burst should not depend on the distance of the burst from us. However, if the speed of light varies, then we would expect the time delay to increase for bursts further away. The Fermi Gamma-ray Space Telescope will be in an excellent position to measure many of these bursts and collect precisely this kind of data.

Because the geometric layout of bursts isn’t well understood, nobody will be rushing to suggest that this technique can identify Lorentz violation. However, by doing these studies, the contraints on how much Lorentz violation could possible exist will get tighter and tighter, perhaps tight enough to rule out some theories of quantum gravity.

The press release issued by SLAC National Accelerator Laboratory is as follows:

Most extreme gamma-ray blast ever, seen by Fermi Gamma-ray Space Telescope

With the greatest total energy, the fastest motions, and the highest-energy initial emissions ever before seen, a gamma-ray burst recently observed by the Fermi Gamma-ray Space Telescope is one for the record books. The spectacular blast, which also raises new questions about gamma-ray bursts, was discovered by the FGST’s Large Area Telescope, a collaboration among NASA, the US Department of Energy (DOE) Office of Science and international partners.

“Burst emissions at these energies are still poorly understood, and Fermi is giving us the tools to figure them out,” says Large Area Telescope Principal Investigator Peter Michelson, a Stanford University physics professor affiliated with the Department of Energy’s SLAC National Accelerator Laboratory.

The explosion, designated GRB 080916C, occurred at 7:13 p.m. EDT Sept. 15 (after midnight GMT, Sept. 16) in the constellation Carina. FGST’s other instrument, the Gamma-ray Burst Monitor (GBM), simultaneously recorded the event. Together, the two instruments provide a view of the blast’s gamma-ray emission from energies ranging from 3000 to more than 5 billion times that of visible light.

A team led by Jochen Greiner at the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, established that the blast occurred 12.2 billion light-years away using the Gamma-Ray Burst Optical/Near-Infrared Detector (GROND) on the 2.2-meter telescope at the European Southern Observatory in La Silla, Chile.

“Already, this was an exciting burst,” says Julie McEnery, an FGST deputy project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “But with the GROND team’s distance, it went from exciting to extraordinary.”

With the distance in hand, FGST team members showed that the blast exceeded the power of nearly 9,000 ordinary supernovae and that the gas bullets emitting the initial gamma rays must have moved at no less than 99.9999 percent the speed of light. This burst’s tremendous power and speed make it the most extreme recorded to date.

The burst is not only spectacular but also enigmatic: a curious time delay separates its highest-energy emissions from its lowest. Such a time lag has been seen clearly in only one earlier burst, and researchers have several explanations for why it may exist.

The environment around a gamma-ray burst is extremely complicated. Although the specifics vary from burst to burst, the surrounding area generally includes the remnants of a stellar explosion, a magnetic field, a black hole and various particles accelerated by the black hole’s gravitational pull, as well as huge amounts of radiation. It is possible that the delays could be explained by the structure of this environment, with the low- and high-energy gamma rays “coming from different parts of the jet or [being] created through a different mechanism,” Michelson says.

Another, far more speculative theory posits that perhaps time lags result not from anything in the environment around the black hole, but from the gamma rays’ long journey from the black hole to our telescopes. If the theorized idea of quantum gravity is correct, then at its smallest scale space is not a smooth medium but a tumultuous, boiling froth of “quantum foam.” Lower-energy (and thus lighter) gamma rays would travel faster through this foam than higher-energy (and thus heavier) gamma rays. Over the course of 12.2 billion light years, this very small effect could add up to a significant delay.

The FGST results provide the strongest test to date of the speed of light’s consistency at these extreme energies. As FGST observes more gamma-ray bursts, researchers can look for time lags that vary with respect to the bursts. If the quantum gravity effect is present, time lags should vary in relation to the distance. If the environment around the burst origin is the cause, the lag should stay relatively constant no matter how far away the burst occurred.

“This one burst raises all sorts of questions,” Michelson says. “In a few years, we’ll have a fairly good sample of bursts, and may have some answers.”

The team’s results appear in the February 19 edition of Science Express.

Gamma-ray bursts are the universe’s most luminous explosions. Astronomers believe most occur when exotic massive stars run out of nuclear fuel. As a star’s core collapses into a black hole, jets of material-powered by processes not yet fully understood-blast outward at nearly the speed of light. The jets bore all the way through the collapsing star and continue into space, where they interact with gas previously shed by the star. This generates bright afterglows that fade with time.

David Harris

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Galaxy Zoo 2: Join the search for weird celestial objects

February 18, 2009 | 4:29 pm

A galactic merger. Image courtesy of Oxford University.

As we pointed out in our March/April 08 issue, astronomy is one of the few fields of science in which amateurs can make a substantial contribution. There’s no better illustration of that than Galaxy Zoo, a spinoff of the Sloan Digital Sky Survey that allows anyone with a computer to help classify galaxies spotted by the survey.

During the last 18 months, more than 150,000 people  submitted 80 million classifications of one million objects, according to a press release from the University of Oxford (their astronomers lead the Galaxy Zoo effort, which involves six other universities in the US and UK as well as Adler Planetarium in Chicago.)

The volunteers sorted the galaxies by type–spiral or elliptical–and by which way they were rotating. They discovered 3,000 pairs of merging galaxies and a very weird, one-of-a-kind green blob called Hanny’s Voorwerp (voorwerp means “object” in Dutch) after schoolteacher Hanny Van Arkel, who found it. The blob was later partially explained as the result of a jet of energetic particles from a black hole.

Hanny's Voorwerp, or Object

Now the Zoo keepers have launched Galaxy Zoo 2,  which will focus on the 250,000 brightest and most interesting objects from Zoo 1.

From the press release:

‘The first Galaxy Zoo provided us with a Rough Guide to the sky and now we want our users to fill in all the details and create a real Hitchhiker’s Guide to the Galaxies,’ said Dr Chris Lintott of Oxford University, one of the founders of Galaxy Zoo… As with the original site people are free to look at and describe as many galaxies as they like – even five minutes’ work will provide a valuable contribution. Galaxy Zoo 2 is intended to be even more fun as galaxies are pitted against each other in ‘Galaxy Wars’ (which one is more spirally?) and users can compete against their friends to describe more objects as well as record their best finds.

Unfortunately the publicity surrounding the launch of Zoo 2, including this report from BBC, generated 10 times as many hits on the Web site as did Zoo 1 and apparently crashed the server, according to Oxford science blogger Pete Wilson.

So be patient and keep checking. You, too may have a giant green blob in your future.

Glennda Chui

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The Galileoscope: an ultra-cheap, high-quality telescope for the IYA

February 17, 2009 | 12:36 pm

One of the fun aspects of being at a conference like AAAS is that you can be sitting at breakfast in the hotel when a group of people suddenly pull out a bunch of plastic parts which they rapidly assemble into a telescope and start looking at the skyline.

Now just about anybody will be able to see the moons of Jupiter, the rings of Saturn, and other astronomical objects not visible to the naked eye. Stephen Pompea from the National Optical Astronomy Observatory is leading the charge to make the Galileoscope, a high-quality, cheap telescope, available to anybody interested in star-gazing, especially in an urban environment, for the International Year of Astronomy, or IYA.

He had been frustrated that most telescopes for children were expensive, had poor optics, and the eyepieces were hard to use. He had discovered from his experience that many children would look through a telescope, not really be able to see what they had been told about, and essentially shrug it off and give up. “The view of Saturn is exciting to kids and will get them interested in science,” Pompea said. But first the child has to actually see the rings.

Shortly after this interview, Sir Martin Rees, Astronomer Royal of the United Kingdom, took an interest in the Galileoscope and played around with it. Photo courtesy of Doug Isbell, AAS.

Chatting with me at his breakfast table in the hotel lobby, Pompea told me that “most telescope kits are good to demonstrate the principles of optics, but not good for actually looking at things.” The Galileoscope is powerful enough to see the kinds of objects Galileo could see but the simple design is based on how kids use small telescopes. Eyepieces, in particular, are typically difficult for children to use. This eyepiece has a wide angle from which it be seen into, and it works well wearing glasses, as I discovered looking through the high atrium windows at the Chicago skyline.

The Galileoscope debuted at the opening of the IYA in Paris a few weeks ago, but it will be available for orders starting this week.

At breakfast, Kevin Marvel, executive officer of the American Astronomical Society, said, “Our goal is to have one million telescopes around the world this year.” He hopes to have them widely distributed in time for the northern hemisphere autumn observing season. The telescope will cost US$15, with discounts for orders of 100 or more.

Doug Isbell, also of AAS, added that “Jupiter is great in August and September” in the United States. He hopes that the telescope becomes one of the major legacies of the IYA.

After peering through the telescope, I called over a colleague who knows a lot more about telescopes than I and asked him to take a look. He was impressed and commented that he has a nice telescope but doesn’t use it as often as he would like because he doesn’t want to leave it setup on a tripod all the time, and it takes too long setup and pack away for casual use. He seemed to think this would be much more useful for casual viewing and thought he would probably get one.

The Gaileoscope will be supplemented by educational activities for teachers, astronomy clubs, and anybody else interested in using it.

See the Galileoscope being pulled apart and reconstructed in this video shot at AAAS in Chicago.

Video credit: Brad Plummer, SLAC National Accelerator Laboratory

David Harris

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