Thursday, April 4, 2013

Have a safe day!

Thursday, April 4

2:30 p.m.
Theoretical Physics Seminar - Curia II
Speaker: Wouter Waalewijn, University of California, San Diego
Title: Combining Helicity Amplitudes with Resummation Using SCET

3:30 p.m.


Friday, April 5

3:30 p.m.

4 p.m.
Joint Experimental-Theoretical Physics Seminar - One West
Speaker: Bill Morse, Brookhaven National Laboratory
Title: A Precision Measurement of the Anomalous Magnetic Moment of the Muon with Accuracy 10-10 at FNAL

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Wilson Hall Cafe

Thursday, April 4

- Breakfast: corned-beef hash and eggs
- White chicken chili
- Chicken quesadilla
- Honey-baked ham
- Smart cuisine: Mediterranean-style ziti with asparagus
- Buffalo chicken tender wrap
- Assorted pizza by the slice
- Grilled- or crispy-chicken Caesar salad

Wilson Hall Cafe Menu

Chez Leon

Friday, April 5
- Field greens with walnuts, dried cranberries and blue cheese
- Filet mignon with porcini sauce
- Grilled asparagus
- Strawberry crepes

Wednesday, April 10
- Grilled five-spice chicken
- Thai rice pilaf
- Sugar snap peas
- Pineapple upside-down cake

Chez Leon Menu
Call x3524 to make your reservation.


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From symmetry

AMS tiptoes toward answer to dark-matter question

The first result from the Alpha Magnetic Spectrometer experiment improves on previous measurements, promises precise future results. Photo: NASA

The space-based Alpha Magnetic Spectrometer experiment could be building toward evidence of dark matter, judging by its first result.

The AMS detector does its work more than 200 miles above Earth, latched to the side of the International Space Station. It detects charged cosmic rays, high-energy particles that for the most part originate outside our solar system.

The experiment's first result, released today, showed an excess of antimatter particles—over the number expected to come from cosmic-ray collisions—in a certain energy range.

There are two competing explanations for this excess. Extra antimatter particles called positrons could be forming in collisions between unseen dark-matter particles and their antiparticles in space. Or an astronomical object such as a pulsar could be firing them into our solar system.

Luckily, there are a couple of ways to find out which explanation is correct.

If dark-matter particles are the culprits, the excess of positrons should sink suddenly above a certain energy. But if a pulsar is responsible, at higher energies the excess will only gradually disappear.

"The way they drop off tells you everything," said AMS Spokesperson and Nobel laureate Sam Ting in [Wednesday's] presentation at CERN, the European center for particle physics.

The AMS result, to be published in Physical Review Letters on April 5, includes data from the energy range between 0.5 and 350 GeV. A graph of the flux of positrons over the flux of electrons and positrons takes the shape of a valley, dipping in the energy range between 0.5 to 10 GeV and then increasing steadily between 10 and 250 GeV. After that point, it begins to dip again—but the graph cuts off just before one can tell whether this is the great drop-off expected in dark-matter models or the gradual fade-out expected in pulsar models. This confirms previous results from the PAMELA experiment, with greater precision.

Ting smiled slightly while presenting this cliffhanger, pointing to the empty edge of the graph. "In here, what happens is of great interest," he said.

"We, of course, have a feeling what is happening," he said. "But probably it is too early to discuss that."

Read more

Kathryn Jepsen

Photo of the Day

Sky of pearl

A tree's bare branches stand out against the sunlight-diffused clouds. Photo: Elliott McCrory, AD
From Computing Bits

Teamcenter transforms engineering through integration and reuse

Detail of partial beamline assembly shown inside the PXIE enclosure displayed from Teamcenter. Image: Tony Metz

Have you seen the NOvA near- and far-detector construction exhibit in the Wilson Hall Atrium? Almost all physics experiments at Fermilab require the design, construction and engineering skills of large teams throughout the lab. In the past, engineering data was stored in a various locations throughout the laboratory, some on global fileservers, some on local disk drives, and in a variety of repositories. It was difficult for people to find engineering data easily, to make sure they had the latest version and to determine what documents were related to any piece of engineering data.

The laboratory is implementing Teamcenter, which is a key component of Fermilab's common Engineering Data Management System that will enable engineers, designers, scientists and other technical staff to build upon past work and to share engineering data more effectively. "Teamcenter is a commercial application that provides a centralized database of information that is easy to search and has links to related data and workflows," says Tony Metz, the Teamcenter project manager and head of the Computing Sector Engineering Application Support group. Key capabilities of Teamcenter are: integration between computer-aided design (CAD) software packages at Fermilab and at collaborating institutions; traceability between requirements, specifications, designs and other supporting documents; a library of common parts; electronic signoff; workflow processes; bill-of-material management and product visualization.

Read more

In the News

Quarks' spins dictate their location in the proton

From DOE Pulse, April 1, 2013

A successful measurement of the distribution of quarks that make up protons conducted at DOE's Jefferson Lab has found that a quark's spin can predict its general location inside the proton. Quarks with spin pointed in the up direction will congregate in the left half of the proton, while down-spinning quarks hang out on the right. The research also confirms that scientists are on track to the first-ever three-dimensional inside view of the proton.

Read more

Frontier Science Result: Theory Group

Theoretical predictions at LHC

Cross section for the production of Z pairs at hadron colliders as a function of the collider operating energy. The predictions of MCFM are compared with Tevatron data taken in proton-antiproton collisions at 1.96 TeV and with proton-proton LHC data at 7 and 8 TeV. Image courtesy of ATLAS

At the LHC, a single collision between beams of protons produces an event containing a spray of particles that can be detected by the experiments. Each event may contain any of the particles of the Standard Model, for instance, W or Z bosons, top or bottom quarks, or collimated jets of strongly interacting hadrons. Much of the experimental program is driven by the search for new physics—typically direct searches for conjectured types of particles—that may also be produced in the hadron collisions. Teasing out the hints, or signals, of the new particles usually requires an accurate assessment of the rate of production of Standard Model background events. Providing a good description of both signal and background events is where theorists can play a crucial role.

In the 1990s, theorists began producing the first accurate, or next-to-leading order (NLO), predictions for such background events at the Tevatron. In late 1998, Keith Ellis and I embarked on a project to provide NLO predictions for a wide variety of backgrounds that would be important to understand both at the Tevatron and in the future at the LHC. The project was born with a simple vision: to produce a readily available tool that could provide "one-stop shopping" for accurate predictions at hadron colliders.

We began by providing state-of-the-art predictions for the production of pairs of W and Z bosons, which we made available through a computer code called MCFM. Since then the code has evolved to include the production of W and Z bosons and jets, single top quarks, top quark pairs and more. Testing our understanding of these Standard Model processes is important to much of the ongoing work at the LHC. For instance, the discovery of the Higgs-like boson at the LHC relied on analyses searching for the Higgs boson decay into a pair of Z bosons. Besides being used in this role, MCFM was also used to predict the rate for producing a Higgs boson in association with two jets. This production mode is crucial to detecting the Higgs boson decay into tau pairs. Precise knowledge of the signal rate allows the experiments to test the couplings of the Higgs boson to fermions. Accurate predictions for the properties of signal and background events such as those in MCFM and other similar programs have been essential for exploiting the full potential of the LHC.

John Campbell

The following members of the Fermilab Theory Group contribute to the development of MCFM: From left: John Campbell, Keith Ellis, Ciaran Williams, Raoul Röntsch.

In memoriam: Tom Fitzpatrick

Fermilab employee Tom Fitzpatrick passed away on March 31 at the age of 53. He served the laboratory for 31 years, working in the Particle Physics Division's Electrical Engineering Department as a senior engineering associate.

A celebration of Fitzpatrick's life will be held on Saturday, April 6, at the Moss Family Funeral Home at 209 S. Batavia Ave. (Rte. 31) in Batavia. An informal visitation will be held from 1 to 3 p.m.; a memorial service will follow, beginning at 3 p.m. All memorial service attendees are invited to gather and share memories of Fitzpatrick immediately afterward at Two Brothers Roundhouse at 205 N. Broadway St. (Rte. 25) in Aurora.

Dress is casual. Additional parking is available on Main Street, at the church across Batavia Avenue from the funeral home, and in the city lot behind the church.


QuarkNet masterclass scientist attribution

Yesterday's feature on QuarkNet masterclasses stated that masterclass participant Teppei Katori was a Fermilab scientist. He is not a Fermilab scientist, but a postdoc at MIT.

The article is now corrected.


Today's New Announcements

Cafeteria open this Saturday, April 6

English country dancing at Kuhn Barn Sunday afternoon - April 7

Fermilab Singers concert - April 5

Hiring managers: submit summer personnel requisitions by April 12

The World According to Higgs - Chris Quigg - April 12

April - Fermilab Heartland Blood Drive - April 15-16

UChicago: Willy Wonka - movie and science demos - April 21

Fermilab Arts Series: Barynya: Music & Dance of Russia - April 20

Reminder - FSA debit card PIN required

2013 Fermilab Heartland Blood Drives - upcoming dates

Martial arts class

Free Zumba trial classes

Walk 2 Run

International folk dancing meets Thursday evenings in Kuhn Barn

Indoor soccer

Monday golf league