Fermilab Today

	Friday, Aug. 24, 2012

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Have a safe day!

Friday, Aug. 24

3:30 p.m.
DIRECTOR'S COFFEE BREAK - 2nd Flr X-Over

4 p.m.
Joint Experimental-Theoretical Physics Seminar - One West
Speaker: Eun-Joo Ahn, Fermilab
Title: Measurement of the Proton-Air Cross Section at 57 TeV with the Pierre Auger Observatory

Monday, Aug. 27

THERE WILL BE NO PARTICLE ASTROPHYSICS SEMINAR THIS WEEK

3:30 p.m.
DIRECTOR'S COFFEE BREAK - 2nd Flr X-Over

THERE WILL BE NO ALL EXPERIMENTERS' MEETING THIS WEEK

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Wilson Hall Cafe

Friday, Aug. 24

- Breakfast: blueberry-stuffed French toast
- New Brunswick stew
- Philly portobello sandwich
- Southern chicken and biscuits
- Smart cuisine: Greek fish florentine
- Baked ham and Swiss ciabatta
- Greek chicken pizza
- Malaysian curried chicken

Wilson Hall Cafe Menu

Chez Leon

Friday, Aug. 24
Dinner
- Mandarin orange and red-onion salad
- Grilled mahi mahi w/ tomatillo-avocado salsa
- Thai rice pilaf
- Coconut cake

Wednesday, Aug. 29
Lunch
- Stuffed bacon-wrapped chicken breast stuffed w/ mushroom, cheese, onion and garlic
- Parmesan orzo
- Lemon cheesecake w/ blueberry sauce

Chez Leon Menu
Call x3524 to make your reservation.

Deconstruction: Big data

Big science takes both big data and big cooperation. For the Large Hadron Collider at CERN, storing, analyzing and accessing 25 petabytes of data each year requires a worldwide effort that spans more than 100 institutions in 36 countries. Here's how it works.

The Large Hadron Collider, the world's largest particle accelerator, produces a million gigabytes of data every single second. It's an incredible amount of information—too much for any single institution or computing center to handle.

Fortunately, out of the billions of collisions produced, only a fraction of the data is scientifically interesting enough to keep. Imagine searching for a needle in a haystack. Now imagine searching for a couple of needles in a football field full of haystacks. It takes a while to find the needles, but once you do, there's no need to keep the hay.

In all, CERN keeps about 25 petabytes—that's about 26,000,000 gigabytes—of data per year for physicists to analyze, but even that's more data than all of the text available in the American Library of Congress, multiplied by a thousand.

It's just not realistic for one facility to house and analyze that much information, so to share the load, CERN outsources some of the data storage and processing to more than 150 computing centers all around the world via the Worldwide LHC Computing Grid.

Once each experiment at the LHC decides which collisions are interesting enough to keep, it stores one complete copy of those raw data at CERN, while also dividing the same data among 11 "Tier 1" centers in Asia, Europe and North America. At CERN ("Tier 0") and at these Tier 1 centers, collision events are reconstructed from the raw data. The reconstructed events are then stored at both the Tier 0 and Tier 1 centers.

The United States is home to two Tier 1 computing centers, with ATLAS experiment data making its way to Brookhaven National Laboratory in Upton, New York, and CMS experiment data to Fermi National Accelerator Laboratory in Batavia, Illinois.

—Ashley WennersHerron

Photos of the Day

Triathletes cross the finish line

Aron Soha demonstrated his best Mo Farah impersonation as he crossed the Fermilab triathlon finish line on Saturday. Photo: Joseph Zennamo

Mike Kirby, pictured, was the individual second-place finisher in this year's Fermilab triathlon. First place went to John Olney. Third place went to Brian Hartsell. Photo: Joseph Zennamo

Mike Cooke, pictured, and Chip Edstrom were the triathlon's team winners. Photo: Joseph Zennamo

In the News

US telescopes faced with closure

From physicsworld.com, Aug. 22, 2012

A committee of the National Science Foundation (NSF) has recommended closing six major astronomy facilities in favour of building and supporting new telescopes. The observatories under threat include two leading radio telescopes – the Green Bank Telescope (GBT) in West Virginia and the Very Large Base Array (VLBA), which comprises 10 radio-dish antennas spread across the US from Hawaii to the US Virgin Islands. They are joined by four others based at Kitt Peak in Arizona – the Mayall Telescope, the Wisconsin-Indiana-Yale-National Optical Astronomy Observatory, a 2.1 m telescope and the McMath-Pierce Solar Telescope. US astronomers fear that if the telescopes close it will jeopardize the country's position as a world leader in astronomy.

Physics in a Nutshell

What is subatomic decay?

Decay manifests itself in many ways in normal life, from an old building falling apart to a piece of fruit rotting to a tooth needing a dentist. Decay has even trickier meanings in the subatomic world. Photo: caribb

Read the expanded column on subatomic decay.

Decay evokes a lot of images, from jumbled piles of stone that once composed breathtaking examples of architecture to the dank smell of a damp forest glen, with the rot of wet leaves and crumbling tree stumps filling your lungs.

The word decay also shows up a lot in Fermilab Today articles, which often talk about the decay of this particle or that. Is it possible that you, the reader, might be applying a common meaning to this most uncommon situation? Just what does this familiar word mean in a particle physics context?

In particle physics, decay means that a particular particle disappears and is replaced by two or more decay products. Conjuring up a human metaphor, we call the initial particle a mother particle and the decay products the daughter particles. Continuing the symbolism, the daughter particles can in turn decay into granddaughter particles, and so on until you get the final product.

There are three broad classes of subatomic decay, from a nucleus that splits into two pieces to a particle disappearing and being replaced by two daughters. To explore the various kinds of decay, take a look at this page, where I give a more detailed description of each kind of decay.

—Don Lincoln

Want a phrase defined? Have a question? Email today@fnal.gov.

In the News

And now, the space-weather forecast

From The Economist, Aug. 23, 2012

Radioactive materials decay at a predictable rate—so predictable, in fact, that scientists widely use them to date artefacts and geological objects. That, at least, is the received wisdom, which Jere Jenkins and Ephraim Fischbach, from Purdue University in Indiana, think may need revising. In 2006 Dr Jenkins noticed that the decay rate of the radioactive isotope manganese-54 dipped 39 hours before a solar flare came crashing into Earth's protective magnetic field. Now it seems that the sun might affect other types of decay, too.

As the researchers report in Astroparticle Physics, the decay rate of chlorine-36 increases as Earth approaches the sun. The difference is tiny: the rate fluctuates by less than 1% between the aphelion and perihelion, the points on Earth's orbit when it is farthest and closest to the sun, respectively. But it is discernible and persistent. As-yet-unpublished data for manganese-54 suggest that isotope follows a similar pattern. If confirmed, the insight might, among other things form the basis of a system for forecasting dangerous cosmic storms.

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