Thursday, March 26, 2015
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Employee discount at Chipotle on March 30

Pilates registration due March 30

2015 FRA scholarship applications accepted until April 1

Wilson Hall southwest stair work: temporary access restriction through April 4

Nominations for Employee Advisory Group due April 17

2014 FSA deadline is April 30

Interpersonal Communication Skills course - May 20

Mac OS X security patches

Fermilab Board Game Guild

Muscle Toning class

Monday Golf League

Changarro restaurant offers Fermilab employee discount


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From symmetry

The dawn of DUNE

A powerful planned neutrino experiment gains new members, new leaders and a new name. Image: Fermilab

The neutrino experiment formerly known as LBNE has transformed. Since January, its collaboration has gained about 50 new member institutions, elected two new spokespersons and chosen a new name: Deep Underground Neutrino Experiment, or DUNE.

The proposed experiment will be the most powerful tool in the world for studying hard-to-catch particles called neutrinos. It will span 800 miles. It will start with a near detector and an intense beam of neutrinos produced at Fermi National Accelerator Laboratory in Illinois. It will end with a 10-kiloton far detector located underground in a laboratory at the Sanford Underground Research Facility in South Dakota. The distance between the two detectors will allow scientists to study how neutrinos change as they zip at close to the speed of light straight through the Earth.

"This will be the flagship experiment for particle physics hosted in the U.S.," says Jim Siegrist, associate director of high-energy physics for the U.S. Department of Energy's Office of Science. "It's an exciting time for neutrino science and particle physics generally."

In 2014, the Particle Physics Project Prioritization Panel identified the experiment as a top priority for U.S. particle physics. At the same time, it recommended the collaboration take a few steps back and invite more international participation in the planning process.

Physicist Sergio Bertolucci, director of research and scientific computing at CERN, took the helm of an executive board put together to expand the collaboration and organize the election of new spokespersons.

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Jennifer Huber and Kathryn Jepsen

Photo of the Day

What congestion?

Throwback to last fall and to a location, while not on the Fermilab site, still very much connected with it: Soudan, Minnesota, home of the MINOS far detector. In the midst of this bucolic scene is a road sign declaring the stretch a "congested area." During the entire week he was there, William Badgett saw not a single soul on this street. Photo: Wiliam Badgett, ND
Wellness Feature of the Month

April wellness, special events and fitness classes

Spring Book Fair
Tuesday, March 31, 10 a.m.-3 p.m.
Wednesday, April 1, 8 a.m.-2 p.m.
Wilson Hall atrium

Fitness Classes

Mat Pilates
Mondays, April 6-May 18, noon-12:45 p.m.
Fitness Center Exercise Room
$87. Register by March 30.

Free trial open house yoga class for potential new students
Monday, April 20, noon-12:45 p.m.
WHGFE Training Room
RSVP to or x2548.

Yoga Mondays
Mondays, April 27-June 15 (no class May 25), noon-12:45 p.m.
WHGFE Training Room
$55. Register by April 20.

Yoga Thursdays
Thursdays, April 30-June 18, noon-12:45 p.m.
WHGFE Training Room
$60. Register by April 23.

Athletic Leagues

Monday Golf League
Tanna Farms Golf League has openings for players on Monday evenings. League play begins May 4 and runs for 16 weeks. It will follow an individual-handicap format with weekly games. Contact Ron Evans at x4166 or Gary Davis at x4171 for information or to join.

Fermilab Golf League
Two leagues are available as part of the Fermilab Golf League: Tuesdays at Bliss Creek and Wednesdays at Fox Valley. League play offers four-person team competition using a handicap format. Golfers of all abilities are welcome. Individuals and teams are invited. Substitutes are also needed. For information contact Mike Matulik at x4091.

Employee Discount
Changarro restaurant

For more discounts, visit the employee discount Web page.

Frontier Science Result: DZero

Flipping the magnets (not the burgers)

Similar to the way that flipping a burger ensures all parts of the patty have been exposed to heat, flipping the magnetic field direction in DZero provides protection against unwanted effects of detector nonuniformities. Photo: Mike

Several recent DZero results have involved the production of a particle and its antiparticle and their directional tendencies.

The Tevatron collided oppositely directed protons and antiprotons. Sometimes a particle created in the collision exited in the direction of the incoming proton while its oppositely charged antiparticle emerged in the direction of the incoming antiproton. Sometimes the situation was reversed. The difference in these configurations is usually cast in terms of a forward-backward asymmetry, where "forward" refers to the first situation and "backward" to the second.

In the case of top and antitop quark production, the measured asymmetry originally seemed to be larger than expected, which if true would have signaled some new physics. (Later measurements resulted in better agreement with the Standard Model predictions.) Subsequently scientists sought such asymmetries in the production of particles containing bottom quarks. Further studies of asymmetries involving the decay products of Z bosons or muon pairs allowed further sensitive tests of the Standard Model.

In all of these measurements, the effects caused by asymmetries in the detector itself must be minimized. But measuring these accurately is nearly impossible.

In controlling detector asymmetries, DZero has a unique secret weapon. As with other collider experiments, DZero has a magnet surrounding the inner detectors that record the curving particle tracks. Unlike other experiments, DZero was able to reverse this magnetic field.

Reversing the magnet polarity is no big trick: One simply throws a giant switch. But most detectors measure particle trails in a gas, and this only works with one magnet polarity. In DZero's case, there were no gas-filled tracking detectors. Instead it relied on thin layers of silicon or scintillator, which are nearly insensitive to the magnetic field direction. The DZero magnet was reversed every two weeks with equal data samples for each.

The reversal allows for almost complete cancellation of the asymmetries caused by detector effects. The reason is easy to see if one considers two possible event configurations for producing a particle and its oppositely charged antiparticle: In one, the positive particle travels in the forward direction in a positive magnet polarity, and the negative particle travels in the backward direction. In the second, the negative particle travels in the forward direction in a negative magnet polarity, and the positive particle travels in the backward direction.

These two configurations interchange the "forward" and "backward" categories. But the positive particle in the positive polarity field travels on the exact same trajectory as the negative particle in the negative polarity, and thus their detection efficiencies should be essentially the same.

This pairing of equivalent configurations assures that the effects of the forward-backward instrumental asymmetries are nearly canceled.

Like flipping the burgers, flipping the magnets assures uniform cooking!

Paul Grannis

Keeping the Run II DZero experiment running smoothly around the clock required close supervision of magnets, detectors, electronics, cryogenic and safety systems. The Run II run coordination team included, top row, from left: Jon Kotcher, Dmitri Denisov, Alan Stone, Arnd Meyer. Middle row, from left: Michele Weber, George Ginther, Bill Lee, Taka Yasuda. Bottom row, from left: Norm Buchanan, Marc Buehler and Stefan Gruenendahl.
In the News

Earth's most powerful physics machine gets back in action

From Wired, March 24, 2015

In the fall of 2008, CERN's high-energy physicists ran into a problem. A faulty electronic connection at the Large Hadron Collider in Switzerland — the biggest, baddest, most powerful particle accelerator ever built — caused a couple of magnets to overheat and melt, triggering an explosion of pressurized helium gas. The accident, which happened just nine days after the LHC turned on for the first time, led to months of delays. "It was pretty depressing when we broke the accelerator," says Aaron Dominguez, a physicist at the University of Nebraska. "That was not a good day."

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