A prelude to the Higgs

July 31, 2008 | 5:49 am

Smaller cross sections mean more sensitive detection ability is needed to spot certain fundamental processes. The observation of the ZZ process shows that Fermilab physicists are nearly at the level required to observe the Higgs boson decaying into two W bosons.

How rare is rare? In the case of the DZero experiment at the Fermi National Accelerator Laboratory, rare means three out of 200 trillion. That’s the result that DZero scientists found when they sifted through 200 trillion proton-antiproton collisions to find those that produced a pair of Z bosons-carriers of the weak force.

Next on the menu: collisions that produce the elusive Higgs boson, which would explain why elementary particles such as electrons have mass.

The discovery of the rare ZZ process–announced in a press release today–is the last step in a series of measurements of rarer and rarer processes made by the CDF and DZero experiments at Fermilab over the last 15 years (see graph right).

The ZZ process shares important characteristics and signatures of subatomic processes that involve the Higgs boson. Hence finding ZZ events is an essential step in demonstrating the ability of particle physicists at Fermilab to see the Higgs. If the Higgs particle is not too heavy, the CDF and DZero collaborations hope to find collisions that produce a Z boson and a Higgs boson simultaneously.

Kurt Riesselmann

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Particle accelerator reveals hidden Van Gogh

July 30, 2008 | 12:29 pm

Experts say as many as one-third of Vincent Van Gogh’s paintings may conceal earlier works that the artist chose to paint over. Now one of those hidden works has been revealed — the somber portrait of a peasant woman concealed beneath the sunny impressionistic colors of “Patch of Grass,” which was painted in Paris in 1887.

Conventional x-rays had revealed the presence of an earlier painting, but could not distinguish the colors in the image.  So an international team of researchers took it to DESY, the Deutsches Elektronen-Synchrotron, in Hamburg, where it was exposed to a powerful beam of X-rays generated by a particle accelerator.  The X-rays caused various elements in the pigments to fluoresce, enabling experts to recreate the colors.

According to an account in today’s Los Angeles Times:

Since each element in the painting had its own X-ray signature, the scientists were able to identify the distribution of metals in the various layers of paint and construct a three-dimensional model of the work. Then the team peeled off the layers one by one.

The top layer consisted of paints made with zinc, barium, sulfur and other elements. Behind that they found a uniform distribution of lead, which was used as a primer to hide the portrait and prepare the canvas for a new painting. Once that was removed, they combined the distributions of two more elements — mercury and antimony — to produce the outlines of the hidden portrait.

Then, with the help of computer software, the team embarked on an elaborate version of painting by numbers.

“We colorized those two distributions according to the color that the pigment would have had,” Dik said.

Chemical analysis revealed that the mercury was an ingredient of vermilion, the red pigment used to color the woman’s lips, cheeks and forehead. Antimony was a component of Naples yellow, which was mixed with zinc white paint to highlight certain areas of the woman’s face, according to the report in the August issue of Analytical Chemistry.

For more details see this press release from lightsources.org.

The same technique was used to uncover a 10th-century copy of treatises by Archimedes, whose parchment had been written over as a prayer book by a Christian monk.  This experimental scanning was performed at the Stanford Synchrotron Radiation Laboratory.   You can read all about the Archimedes Palimpsest here.

Glennda Chui

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Rapping the LHC

July 29, 2008 | 3:27 am

Like the Large Hadron Collider? Feel like you’ve been reading the same LHC articles or watching the same videos over and over again? Then check out the latest addition to the YouTube pantheon of LHC videos, the Large Hadron Rap.

The rap is the brainchild of Kate McAlpine, a.k.a. alpinekat, a freelance science writer and one of the editors of the ATLAS e-News. Having just produced her first physics rap, McAlpine was already planning an LHC rap when she arrived at CERN in October for a six-month stint in U.S. LHC communications.

“I’d just finished a rap about a neurochip, and my head was filled with information about the LHC and its goals,” said McAlpine. “I had access to experimental halls as well as stock footage. To not rap would have been a wasted opportunity.”

The dancing and rapping segments were filmed on location at CERN and in the LHC’s underground areas. While actors, musicians and even a dance troupe had visited the LHC, this was the first time it had starred in a rap video.

“The response was dubious when we were trying to get permission to film and intrigued once people found out what we were up to,” she said.

McAlpine’s newest venture has been attracting much more attention than she expected – she’s been interviewed by the BBC, and in the video’s first dozen hours on YouTube it attracted more than 1,300 views.

“You know what the status was eight hours after uploading N3UROCH!P [her first rap]? 14 people had seen it,” she added.

While alpinekat hasn’t yet signed with a record label, she’s already planning her next physics rap.

Katie Yurkewicz

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Got enough physics?

July 28, 2008 | 5:59 am

The eyes may be the windows to the soul, but it helps to have other reference points. Celtic dragon knots, Che Guevara headshots, Dilbert cartoons, and Shrödinger’s equation all fit the bill in the realm of expressive T-shirts.

If you’re one of those people who can never have enough physics in your life, you may enjoy digging around the physics-related shirts, mugs, clocks, and other merchandise available on the Internet.

In the online age, where everybody can participate, ventures like cafepress.com allow users to design their own products and have them made on demand, either for themselves or to sell in their own stores. At the site, a simple search for “physics” returns more than 7000 matches, and even though many of the items available are not really physics-fan desirables, there is a wealth of paraphernalia to explore.

A few ideas turn up often enough to vouch for their secure place in popular consciousness: references to Schrödinger’s cat, quotes by Einstein, and quantum mechanics’ allotment of a general sort of freakiness.

Other items offer assurances that science is hip: “PHYSICS BABE” shows a slinky cartoon woman in a space suit wielding a ray gun, while another shirt proclaims “Science makes me cool.” There are cheat-sheet designs that all but replicate a student’s notes onto a shirt; there is self-deprecating humor. ”Research…screwing up for fun and profit,” one T-shirt cracks. Or maybe it really is the case that “78% of all statistics are made up on the spot” and “Progress is directly proportional to equipment ruined.”

Many of these designs are in-jokes, intelligible and interesting primarily to those already in the know. Anyone want a Maxwell’s equations wall clock? How about this message: “Let’s put the fun back in wavefunction!”

I prefer designs that communicate through graphics: pictures of archaic physics equipment, the iconic head of Nikolai Tesla with his name all in caps, or “Chillin’ with my [ohm]ies.”  A simple image of a lab-coated man pouring liquid into a vial, labeled “SCIENCE!”,  appeals to me more than the slogan, ”Quantum physics says you’ll never find me if I stand still.”

One particularly obscure shirt features a kinematic equation purporting to show “the airspeed velocity of an unladen swallow.”  I didn’t get it, but my fellow intern Calla Cofield chuckled, explaining that it was a reference to Monty Python. ”Yeah,” she said, ”you have to be a double nerd to get that.”

Zoë Macintosh

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GLAST reports first observation

July 25, 2008 | 7:20 pm

Days after it switched on, the main instrument on the Gamma-ray Large Area Space Telescope began observing an extraordinarily bright gamma-ray blazar known as 3C 454.3, according to a new report.  Scientists have known about this object for a while – it’s been monitored by the AGILE gamma-ray satellite  and the Whole Earth Blazar Telescope – so this is not a new discovery.  But it’s exciting because the instrument, called the Large Area Telescope, is still undergoing the arduous tweaking and testing known as commissioning.  And while the researchers aren’t giving out exact details  – they can’t, really, until the instrument is properly calibrated – they say the blazar is much brighter and more intense than reported by earlier observers.

The news was posted yesterday on The Astronomer’s Telegram on behalf of the GLAST Large Area Telescope Collaboration by Gino Tosti of the INFN-Perugia lab in Italy; James Chiang, Eduardo do Couto e Silva and Jana Thayar John Gregg Thayer of Stanford Linear Accelerator Center; B. Lott of CENBG/Bordeaux; and J. Eric Grove of the US Naval Research Laboratory.  

“What’s exciting is that we’re already seeing interesting things in the sky and reporting to the overall community, which suggests that the instrument is working very well,” do Couto e Silva told me this afternoon.  “The point is to essentially say listen, there is something interesting happening in the sky.  If you have another instrument, another telescope, and you want to observe it, go for it, because it will be worthwhile.”

Launched June 11,  GLAST is a cooperative effort between NASA and the US Department of Energy, with key international contributions.   SLAC managed the construction of the Large Area Telescope and played a key role in assembling the instrument, whose data flows into a control center at the lab for distribution to scientists around the world. 

 It’s a follow-on to an earlier mission called CGRO-EGRET, which also looked at gamma rays –  the highest-energy form of light – generated by the most violent processes in the universe.   GLAST has two advantages over EGRET.  It returns to the same patch of sky every three hours, rather than briefly pointing at one object at a time; “We’ll be able to make movies, where before we could only make photographs,” do Couto e Silva says. And it monitors the most extremely energetic gamma rays, which earlier missions could not.  (For an overview, see this piece in the February 2006 symmetry.)  So GLAST should fill a gap in our understanding of the universe — as if we had been seeing the world in every color but red and now can add the missing hue.

Blazars are powerful jets of radiation spewing out of active galactic nuclei, or AGNs — the centers of galaxies containing supermassive black holes, millions to billions of times more massive than our sun.  The Large Area Telescope started observing blazar 3C 454.3 on June 28, five days after the instrument was switched on.   The researchers said they won’t be able to monitor the blazar regularly until commissioning is completed in early August, but they urged others to start following the blazar in other wavelengths of light.

Glennda Chui

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New clue to Fermilab code

July 25, 2008 | 12:10 pm

Local media interest in deciphering the coded message that Fermilab received last year continues.  On Wednesday, Naperville Community TV came to the laboratory to interview me (I’m the Fermilab PR director) and Eric Prebys, a Fermilab physicist who worked with Frank Shoemaker at Princeton University.

Eric Prebys. Photo courtesy of Fermilab VMS

Code crackers, who learned about the message from symmetry breaking, have determined that the first section of the message reads “FRANK SHOEMAKER WOULD CALL THIS NOISE.” Shoemaker, a physicist, worked at Fermilab in the early days of the laboratory.

The bottom part of the message, the on-line code crackers tell us, says “”EMPLOYEE NUMBER BASSE SIXTEEN.” What could this mean? Is “BASSE” a misspelling of “BASE”? To prepare for the TV interview, I called Fermilab’s Human Resources section to ask about Frank Shoemaker’s employee number.
Fermilab assigns employee numbers sequentially. Robert Wilson, the laboratory’s legendary first director, was employee number 1. Ned Goldwasser, Wilson’s deputy director, was 007. The latest Fermilab hire, as of last Monday, was number 15026.

According to Fermilab’s records, Frank Shoemaker was employee number 102. In base 16, I am told, 102 = 66.

Will this be the clue that cracks the hieroglyphic middle section of the coded letter? Or persuades the code maker to come forward?

Employee Number 10112

Judy Jackson

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How can the LHC be colder than space if space has no temperature?

July 25, 2008 | 5:52 am

This week’s headlines about the Large Hadron Collider operating at a temperature colder than that of deep space (see previous blog posts here and here) have inspired some to ask: If deep space is empty, with no atoms in it to jiggle around and produce what we define as heat, how can it be said to have any temperature at all?

Bad Astronomy tackles that question in a most interesting way involving emptiness, photons and the Mini Marshmallow of Science:

Sure, if there’s no there there, then there is no temperature. Of course, space isn’t really empty, it’s only mostly empty. Near the Earth, space actually has lots of subatomic particles per cubic centimeter. Even between galaxies, there are one or two particles per cc. But still, space is so empty that these hardly count when talking temperature. Right?

Well, it’s complicated.

When the Universe formed, it was hot and dense. As it expanded, it cooled off. At first, your average photon — a particle of light — had lots of energy. But fighting the expansion of space itself takes its toll, and the photons lost energy. Flash forward 13.7 billion years, and today we see these photons have lost a lot of energy. What used to be a raging fireball from the moment the Universe formed is now a chilled brew, with the photons in the microwave part of the spectrum; very low energy indeed. You can convert that energy into a kind of temperature, and the number you get is about 2.7 Kelvin (-270 Celsius, or about -450 F).

That means that even if space is totally empty of matter, there are still photons at that energy flowing through it. If you took a mini marshmallow (and why not) and stuck it in deepest space, it would drop in temperature until it got to 2.7 Kelvin. It wouldn’t get any colder than that, because those photons would warm it up to 2.7 K.

Be sure to check out the comments, many of them deliciously marshmallow-related.

Glennda Chui

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Purdue "barn-raising" installs a Grid computer cluster, fast

July 24, 2008 | 5:37 am

With the help of athletic rival Indiana University, Purdue University installed 1000 computers in a cluster the size of an 18-wheeler in just half a day — a process that usually takes weeks.  This new addition to the Grid, called Steele, was financed by more than two dozen faculty members.  One of the users will be the Tier-2 data center at Purdue, which will collect data from the Compact Muon Solenoid experiment at the Large Hadron Collider, soon to open on the Swiss-French border, and make it available to scientists on campus and around the world.

As International Science Grid This Week, reports:

The CMS Tier-2 centers support the computational needs of CMS physicists, both for physics analyses and simulations. It and the other six Tier-2 centers in the U.S. work in concert with the Tier-0 at CERN and the half-dozen international Tier-1 centers, primarily the U.S. Tier-1 at Fermilab. The world-wide Tier structure will manage and distribute the deluge of data expected from the CMS detector when the Large Hadron Collider turns on later this year.

Steele is one of a handful of facilities in the U.S. integrated with the two principal government-funded grid systems for scientific computing, OSG and TeraGrid. It replaces the older Lear cluster at Purdue, parts of which will be reassembled at Purdue’s Calumet and Fort Wayne satellite campuses. Steele has more than six times the processing power of Lear and at maximum speed is expected to reach 60 trillion operations per second.

“We got the new cluster running on the grid within a couple of hours,” says Purdue physics professor Norbert Neumeister. Smith says that it happened quickly for the same reasons the cluster itself came together in a few hours: careful planning and the automation recently built into the clustering and grid install procedures.

Check out the cool movie trailer-style video announcing Installation Day  (rated “R FOR RESEARCH. EXTREME UNPACKING AND INSTALLATION.”)

Glennda Chui

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Update: How cold is the LHC right now? What about now?

July 23, 2008 | 1:36 pm

Sector 3-4 magnets: Almost there

As CERN’s Large Hadron Collider is gradually chilled to its operating temperature of 1.9 degrees Kelvin — colder than the vacuum of outer space — you can follow along at this Web site.  It shows the temperature of each of the machine’s eight sectors in real time, or pretty close to it.    Thanks to Bad Astronomy for pointing this out.

Why so cold?   Check out this post from Monday.

Glennda Chui

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A droll, gleeful look at elements of the Periodic Table

July 23, 2008 | 5:06 am

Chemists at the University of Nottingham have made a series of short videos, one for each element of the Periodic Table, and they are a hoot.  Not that they’re silly;  no, they are quite solid (when not liquid or gaseous)  and demonstrate actual properties of these most basic substances.  But they’re definitely put together with a twinkle of the eye.

Take sodium:   A scientist in lab coat and safety googles removes a cylinder of the reactive metal from a jar and cuts off a piece to show how shiny it is.   He and a colleague carry a big chunk outside and drop it into a stoneware dog bowl full of water:   Sizzle! Smoke!  Flame! Pop!  Little chunks fly  out of the bowl — one pasting itself onto the camera — and the scientists chuckle like schoolboys.   These demonstrations are intercut with shots of Professor Martyn Poliakoff in his cluttered, book-bound office, explaining why sodium is unique and important.  It has a warm spot in his heart, he adds, because its chemical symbol is Na, which was his mother’s nickname.

Part of Poliakoff’s considerable charm is his cloud of gray hair; a cross between Einstein and Afro, it seems poised to take off on an adventure of its own.  According to his Wikipedia entry, Poliakoff recently won an award for best hair on the Internet.  While I’d take that claim with a grain of sodium chloride, you can see how it might be possible.

I spent some time browsing through elements with a particular connection to high-energy physics;  argon, mercury and xenon, which fill the chambers of some particle detectors; iron (did you know that the CMS detector at CERN, the particle physics lab on the Swiss-French border, contains more iron than the Eiffel Tower?); copper; the ubiquitous hydrogen and helium (boffo choices because one explodes into flame, the other makes you talk like Donald Duck.)  Not all of the films feature exciting demonstrations.  Niobium, for instance, a sleek metal used to fashion radiofrequency cavities, did not make a direct appearance in its video, although it had figured in some of Poliakoff’s experiments and he spoke of it fondly.  “It was very good to me,” he says. “I’ve always regarded niobium as a very friendly element.”  But the project Web site says the videos will be updated “with new stories, better samples and bigger experiments.”

Some of these elements are getting harder to obtain for physics experiments, according to an article David Harris posted here in April. The growing demand for xenon and helium is driving up prices; ingots of lead from sunken Roman ships are prized because they are free from contamination by thorium and uranium, but they are naturally in limited supply.

He concludes:

The list of materials in demand goes on; it seems that the resource struggle the whole world is facing has an impact on basic science research. Fortunately, the ingenuity of scientists generally finds a way around the problem, but this is one more challenge in the conduct of an experiment.

Glennda Chui

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