Thursday, Feb. 27
- Breakfast: Canadian bacon, egg and cheese Texas toast
- Breakfast: Greek omelet
- Ranch house steak sandwich
- Asian beef and vegetables
- Barbecue pork spareribs
- Italian loaf sandwich
- Tex-Mex grilled chicken salad
- Chicken noodle soup
- Chef's choice soup
- Assorted pizza by the slice
Wilson Hall Cafe menu
Friday, Feb. 28
Wednesday, Mar. 5
Chez Leon menu
Call x3524 to make your reservation.
SeaQuest begins taking data
|Paul Reimer inspects part of the SeaQuest experiment, which began taking data last week. Photo: Reidar Hahn
On Thursday, Feb. 20, the SeaQuest experiment began taking physics data for the first time.
The experiment, managed by Argonne National Laboratory and conducted at Fermilab, aims to probe the internal structure of the proton and the strong force that binds its constituent parts, called quarks.
One of the questions SeaQuest will try to answer is how the effects of the strong force change when a proton is isolated from an atom, rather than situated inside it. It will also investigate a curious quark quantity turned up by an earlier Fermilab experiment, NuSea.
NuSea investigated the number of up antiquarks and down antiquarks swimming around in the sea of particles inside the proton. Contrary to the expectation that there would be equal numbers of both particles, it turned up evidence that there were more down antiquarks than up. It also showed that in a certain region of quark momentum, this was reversed.
SeaQuest aims to look further into this lopsided ratio. If it confirms NuSea's findings, it may mean scientists will have to rewrite the textbooks on the interplay of the stuff that makes up protons.
"The fun can begin now that we're taking data," said Argonne physicist and SeaQuest spokesperson Paul Reimer. "We've been looking forward to running the experiment for a long time, so we're eager to finally delve deep into the proton to better understand the universe that it constitutes."
SeaQuest will continue taking physics data for two years. Then experiment members will dig into the data to mine the sea of particles that make up protons.
Fifteen institutions from around the world collaborate on SeaQuest.
Science Next Door March newsletter now online
The March edition of "Science Next Door," Fermilab's monthly community newsletter, is now available online. View it or subscribe to get the latest about the laboratory's public events, including tours, lectures, arts events and volunteer opportunities.
March wellness offerings, fitness classes and discounts
Free wellness offerings this month include Employee Appreciation Day massages, Walk 2 Run, and BuZheng Qigong and Tai Chi Easy classes. Register for fitness classes that begin in March: Zumba Fitness, Zumba Toning, Butts and Guts or Martial Arts. Learn more about the new Society of Philosophy Club and employee discounts for March.
Free Wellness Offerings
Employee Appreciation Day massages
Sign up today for your complimentary 10-minute chair massage by emailing email@example.com or calling x2548.
Walk 2 Run
March 13 - May 15, 4:45-5:30 p.m.
Meets outside Wilson Hall, east side.
This free 10-week program teaches you to run, improves fitness, assists in losing weight and helps lower cholesterol. All are welcome regardless of age, speed or experience. Wear athletic shoes.
BuZheng Qigong and Tai Chi Easy
Mondays and Fridays through May 30, noon-1 p.m.
Wednesdays through May 28, 7-8 a.m.
Tuesdays, March 4 - April 22, 11:45 a.m.-12:30 p.m.
Fitness Center Exercise Room
$50/person. Register now.
Thursdays, March 6 - April 24, 11:45 a.m.-12:30 p.m.
Fitness Center Exercise Room
$50/person. Register now.
Butts and Guts
Fridays, March 7 - April 25, 11:45 a.m.-12:30 p.m.
Fitness Center Exercise Room
$60/person. Register by Feb. 28.
Mondays and Wednesdays, March 31 - May 7, 5-6 p.m.
Fitness Center Gym
$60/person. Register by March 24.
New Employee Club
Society of Philosophy
Meets biweekly. Next meeting is March 13, 12:30-1:30 p.m.
Req Room, WH4NW
Contact firstname.lastname@example.org for more information.
For other discount information, visit the WDRS employee discounts Web page.
Vaughan Athletic Center corporate rate for Fermilab
For more information, contact Jeanne Ecker in the Wellness Office at x2548 or at email@example.com.
The dark matter poltergeist
From Slate, Feb. 25, 2014
Touch something. Anything. What do you feel? Does it push back? That's electromagnetism. Any time you touch something solid, the sensation of not being able to put your hand right through it is caused by the electromagnetic force of the atoms in your hand pushing against the atoms of the object in question. Electromagnetism governs every interaction we have with the world — touch, sight, even smell and taste when you consider that the chemical reactions we perceive through these senses are changes in (electromagnetic) molecular bonds.
Evidence for rare single-top-quark process at CDF
|This shows a Feynman diagram for s-channel single top quark production. The top quark decays into a W boson and a b-jet.
This week, a combined effort from the CDF and DZero experiments reported the observation of a new top quark process. This article discusses the contribution to that result from the CDF experiment.
The top quark was discovered almost 20 years ago by the CDF and DZero experiments through a process in which it is produced in pairs. Events with two top quarks are quite distinctive and can be identified relatively easily. Top quarks could also be produced singly at the Tevatron, but at a lower rate than events with two top quarks. They are also harder to identify because they produce less distinctive signals in our detectors. In fact, because of these challenges, it took 14 years after the top quark was discovered for the Tevatron experiments to observe single-top-quark events.
Measurements of single-top-quark production are important because they can be used to constrain our Standard Model theory and could provide a window to new physics. At the Tevatron, top quarks could be produced singly through two different processes, and new physics could affect these two processes differently, thereby providing clues about the nature of the new physics.
The single-top process for which theory predicts the highest rate occurs when two quarks exchange a W boson to produce a top quark and another quark. This is called t-channel production.
A second process occurs in which two quarks fuse into a W boson that then splits into a top quark and another quark. This s-channel production occurs when an up quark and an anti-down quark combine to form a W boson that then breaks apart, leaving a top quark and an anti-bottom quark (see top figure).
When scientists discovered single-top events five years ago, it was primarily through the events produced in the t-channel process. In fact, until recently, no experiment had seen evidence of the s-channel process. We can separate the s-channel events from those of the t-channel because they are more centrally produced and because the events typically contain two b-jets rather than one.
Because of subtle differences between the proton-antiproton collisions of the Tevatron and the proton-proton collisions of the LHC, the Tevatron has the better chance to measure the s-channel single top. In fact, last summer the DZero experiment reported first evidence for s-channel single top production.
The result of our experiment is that CDF confirms the evidence previously reported by DZero and measures the s-channel cross section to be 1.41 +0.44/-0.42 picobarns using events with an imbalance in the transverse momentum, b-tagged jets and one lepton. CDF also recently submitted a paper that looks for the s-channel single top production by using events with an imbalance in the total transverse momentum, b-tagged jets and no identified leptons. Even more recently, CDF and DZero scientists have combined their results for this difficult process.
—Craig Group and Andy Beretvas
|These physicists were responsible for this analysis: Top row from left: Craig Group (Fermilab and University of Virginia), Hao Liu (University of Virginia). Second row from left: Yuri Oksuzian (University of Virginia), Frederico Sforza (INFN,
University of Pisa), Ben Wu (Baylor University).
|The great depth of the blanket of snow over Fermilab is evident near a stream across the street from the Meson Central Cryogenic Building.
Photo: Chip Edstrom, AD
Long-sought quark-formation process finally found
From LiveScience, Feb. 24, 2014
The hunt for new physics may have to continue for a while longer.
Scientists have found traces of an ultra-rare process to form top quarks, the particles that make up protons and neutrons. And that process seems to operate just as predicted by the Standard Model, the long-standing, yet incomplete, model that describes the subatomic particles that make up the universe.
Though the new results don't rule out other physics theories to explain the existence of dark matter and energy, they do suggest scientists have to look elsewhere for any hint of as-yet unknown physics.