Friday, April 4, 2014

Have a safe day!

Friday, April 4

3:30 p.m.

4 p.m.
Joint Experimental-Theoretical Physics Seminar - One West
Speaker: Oleg Brandt, University of Heidelberg
Title: Top Quark Mass Measurements at DZero: How Precise Does It Get?

Monday, April 7

12:30 p.m.
Particle Astrophysics Seminar (NOTE TIME) - Curia II
Speaker: Valery Frolov, California Institute of Technology, and Hartmut Grote, Albert Einstein Institute
Title: Gravitational Wave Detectors in Europe and the U.S.

2 p.m.
Particle Astrophysics Seminar - Curia II
Speaker: Anja VonderLinden, SLAC
Title: Weighing the Giants: Accurate Weak Lensing Mass Measurements for Cosmological Cluster Surveys

3:30 p.m.

4 p.m.
All Experimenters' Meeting - Curia II

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Wilson Hall Cafe

Friday, April 4

- Breakfast: French bistro breakfast
- Breakfast: chorizo and egg burrito
- Grilled chicken quesadilla
- Smart cuisine: herb and lemon fish
- Vegetarian eggplant lasagna
- Cuban panino
- Breakfast-for-lunch omelet bar
- New England clam chowder
- Texas-style chili
- Assorted pizza by the slice

Wilson Hall Cafe menu
Chez Leon

Friday, April 4

Wednesday, April 9
- Bayou catfish with Creole sauce
- Island rice
- Sauteed green beans
- Chocolate pecan pie with Bourbon cream

Chez Leon menu
Call x3524 to make your reservation.


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In the News

Fermi data tantalize with new clues to dark matter

From NASA, April 3, 2014

Editor's note: Read more about this dark-matter result in the March 21 Frontier Science Result, written by Fermilab's Dan Hooper, who is a lead scientist in the study described in this press release.

A new study of gamma-ray light from the center of our galaxy makes the strongest case to date that some of this emission may arise from dark matter, an unknown substance making up most of the material universe. Using publicly available data from NASA's Fermi Gamma-ray Space Telescope, independent scientists at the Fermi National Accelerator Laboratory (Fermilab), the Harvard-Smithsonian Center for Astrophysics (CfA), the Massachusetts Institute of Technology (MIT) and the University of Chicago have developed new maps showing that the galactic center produces more high-energy gamma rays than can be explained by known sources and that this excess emission is consistent with some forms of dark matter.

"The new maps allow us to analyze the excess and test whether more conventional explanations, such as the presence of undiscovered pulsars or cosmic-ray collisions on gas clouds, can account for it," said Dan Hooper, an astrophysicist at Fermilab in Batavia, Ill., and a lead author of the study. "The signal we find cannot be explained by currently proposed alternatives and is in close agreement with the predictions of very simple dark matter models."

Read more

Physics in a Nutshell

Proving special relativity: episode 2

Particle accelerators routinely create beams of particles traveling at nearly the speed of light. Without Einstein's theory of special relativity, they simply wouldn't work.

Read the full second episode on proving special relativity

In my last column, I described some of the recurring questions raised by people skeptical about whether Einstein's theory of special relativity accurately describes the motion of objects traveling close to the speed of light. A particle accelerator is an environment in which very high velocities are commonplace, so we can use the experience of successfully running the Tevatron for more than a quarter century to address the question.

Prior to the shutdown of the Tevatron in 2011, the Fermilab accelerator complex consisted of five accelerators. Much like the gears on a car with a manual transmission, each accelerator added some energy to a proton until it reached the Tevatron's maximum energy of 1 trillion electronvolts. At that energy, the proton travels with a velocity 99.99995 percent the speed of light, which is 186,000 miles per second. To give some perspective, a proton traveling at that speed could circle the Earth's equator almost eight times in a single second.

Read more

Don Lincoln

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Photo of the Day

Barn on the ring

It looks as though spring conditions might soon arrive. Blue sky and rippling water surrounding the barn on the Main Ring cooling pond give reason to hope. Photo: Amanda Solliday
In the News

Weird 'techni-quarks' may lurk inside Higgs boson particle

From LiveScience, April 2, 2014

The Higgs boson — a particle thought to explain how other particles get their mass — is tiny, but it may not be the tiniest particle yet. Theories have long predicted the existence of even smaller particles that might make up the Higgs, and recent research suggests these pip-squeaks, dubbed techni-quarks, are likely lurking in the universe.

However, it will take the upgrade of the Large Hadron Collider (LHC) — the world's most powerful particle accelerator — or the next generation of colliders to spot these Higgs components, saidThomas Ryttov, a particle physicist at the University of Southern Denmark.

"We have nailed it down to only a few theories that have the right properties and characteristics to explain the Higgs particle and the Higgs mechanism," Ryttov said.

Read more

Frontier Science Result:
Sloan Digital Sky Survey

Sloan Digital Sky Survey and the cosmological constant

The allowed region for cosmological parameters according the recent analysis of supernova data combined with the previously published results from the Planck satellite data.

The Sloan Digital Sky Survey supernova (SDSS SN) survey was born in 2004, when a team led by Fermilab's Josh Frieman was approved as part of the first extension of the original survey. Frieman, now leader of the Dark Energy Survey, recognized that the wide-field-of-view Sloan telescope made it an ideal instrument to observe supernovae — extremely bright, exploding stars.

The Sloan supernova project has resulted in more than 30 publications, including the recent paper of Betoule, et al, to be published in Astronomy and Astrophysics. It is the most precise analysis of supernova data to date.

Stars in the type Ia class of supernovae explode with the same intrinsic brightness. Thus scientists can determine the distance to a supernova by measuring the apparent brightness as seen from Earth. The wavelength of distant light is shifted toward redder colors, and the amount of redshift reveals how long ago the light was emitted. Taken together, the measurements of the supernova brightness and redshift allow scientists to determine the size of the universe as a function of cosmic time.

The Nobel Prize-winning discovery of Perlmutter, Riess and Schmidt showed the expansion of the universe is now accelerating, not decelerating from gravity as expected. The phenomenon is called dark energy, and its properties are often described in terms of the ratio of its pressure to its density — a ratio called w. Einstein's equations for general relativity include the possibility of a value called the cosmological constant, which could provide the mathematical description of dark energy if the value of w is exactly -1. Any other result requires some other modification to Einstein's equations.

The Sloan supernova survey and a similar, higher-redshift survey known as the Supernova Legacy Survey formed a "joint lightcurve analysis" group (JLA) to analyze supernova data from both surveys. The full SDSS SN sample and essential improvements in analysis technique produced the new, precise result.

The figure above shows the result of the JLA analysis and illustrates the effectiveness of combining the supernova data with data from the Planck satellite, which has provided the most precise measurement of the cosmic microwave background. Along the horizontal axis, labeled ΩM, is the fraction of the universe that consists of ordinary matter, and w is the parameter that describes dark energy. The color contours show the experimentally allowed region for these cosmological parameters. The gray region shows the combination of the Planck and the JLA results.

The measured value of w is -1.018 ± 0.057 and is consistent with Einstein's cosmological constant. Nevertheless, it is still only a step towards understanding dark energy.

John Marriner


Today's New Announcements

Wilson Hall Cafe open Saturday, April 5, from 10 a.m. to 4 p.m.

Strength Training registration due April 11

English country dancing with live music at Kuhn Barn - April 6

LabVIEW seminars scheduled on April 10

Interpersonal Communication Skills course - April 16

Edward Tufte artist reception - April 16

MySQL relational database management course - April 22-23

Tour guides for Illini Alumni event - May 3

West bike rack area closed

On sale now: Fermilab Natural Areas hats and shirts

Abri Credit Union gives away two $1,000 scholarships

Active For Life Multilab Challenge

Walk 2 Run

2014 Fermilab Golf League season is upon us

Wednesday Walkers

Martial Arts

Scottish country dancing meets Tuesday evenings at Kuhn Barn

International folk dancing meets Thursday evenings at Kuhn Barn

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