Monday, April 15, 2013

Have a safe day!

Monday, April 15


3:30 p.m.


Tuesday, April 16

3:30 p.m.

4 p.m.
Accelerator Physics and Technology Seminar - One West
Speaker: Gary Carinci, TMR Stainless
Title: Corrosion-Resistant Alloy Developments and Selection Criteria

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Wilson Hall Cafe

Monday, April 15

- Breakfast: pancake sandwich
- Italian minestrone
- Philly chicken sandwich
- Spaghetti and meatballs
- Smart cuisine: herbed pot roast with vegetables
- Garden beef wrap
- Assorted pizza
- Creole jambalaya

Wilson Hall Cafe menu

Chez Leon

Wednesday, April 17
- Assortment of quiches
- Marinated cucumber salad
- Mixed-berry sorbet with cookies

Friday, April 19
- Spinach salad
- Alaskan crab legs
- Parsley potatoes
- Grilled asparagus
- Lemon panna cotta with blueberry sauce

Chez Leon menu
Call x3524 to make your reservation.


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Frontier Science Result: CDMS

Dark-matter search results from CDMS II silicon detectors

Experimental upper limits (90 percent confidence level) for the WIMP-nucleon spin-independent cross section as a function of WIMP mass. The black dotted line is from the present analysis, and the blue solid line includes previous CDMS II silicon-detector data. Also shown are limits from the CDMS II germanium-detector standard and low-threshold analyses (dark and light dashed red), as well as limits from the XENON collaboration (dark and light dash-dotted green). The magenta oval shows a possible WIMP signal region proposed to explain data from CoGeNT. The light and dark blue regions indicate the 68 percent and 90 percent contours obtained if the present result were to be interpreted as a WIMP signal. The asterisk shows the maximum likelihood point under this interpretation.

Scientists around the world are working to understand the nature of dark matter, which accounts for most of the mass of the universe. The earth seems to be moving through a cloud of dark-matter particles that encompasses the visible parts of our galaxy. We should be able to sense this dark matter if we can deploy detectors that are sensitive to the 'billiard ball' scatter of a dark matter particle from an atomic nucleus inside these detectors.

The Cryogenic Dark Matter Search (CDMS) experiment was designed to do exactly that, using germanium and silicon detectors cooled to very low temperatures in order to detect the electric charge and heat liberated by single dark-matter particle collisions with nuclei and distinguish them from the messier interactions created by normal matter.

At the American Physical Society April meeting in Denver, the CDMS collaboration presented on Saturday its blind-analysis results from data taken with silicon detectors during CDMS II operation at the Soudan Underground Laboratory. Kevin McCarthy, a graduate student from MIT, presented the results, which were submitted to Physical Review Letters.

The blind analysis resulted in three candidate events. Although this number is higher than the expected background of roughly half an event, this is far from a discovery. Simulations of the known backgrounds indicate that a statistical fluctuation could produce three or more events about 5 percent of the time. In other words, if the experiment were done 100 times, five of them would show at least three events in the signal region even if dark-matter particles did not exist.

However, there is more information on the characteristics of the expected background events and the expected signals from weakly interacting massive particles, or WIMPs, which are the favorite particle explanation for dark matter. A likelihood analysis that includes the measured recoil energies of the three events yields a 0.19 percent probability for the background-only hypothesis when tested against a model that includes a WIMP contribution. This translates into roughly a 3-sigma confidence level for the hypothesis that the three events are due to WIMP interactions. This is exciting but still does not meet the scientific standard for a discovery. Further investigations are necessary.

Nevertheless, if one indulges in a "what if" scenario and interprets the result as due to a WIMP signal, the WIMP mass would be around 8.5 times the mass of a proton. For the simplest theories of WIMP interactions and using the Standard Model for dark-matter distribution in our galaxy, the rate found for such interactions is in some conflict with the current results from the XENON experiments. The paper presents more details.

In 2010, the CDMS collaboration published results on dark-matter searches with germanium detectors, which resulted in two events in the signal region and an estimated background of 0.8 events. The conclusion at the time was that these events were likely leakage surface electrons rather than true nuclear recoils, and other experiments have not found any signals in this mass region.

The SuperCDMS Soudan experiment is currently taking data with larger, and better, germanium detectors, and hopes to shed additional light on low-mass WIMPs before the end of the year. The collaboration is considering the use of silicon detectors in future experiments.

—Dan Bauer

From symmetry

Underground experiment sees possible hints of dark matter

The Cryogenic Dark Matter Search experiment adds new intrigue to the hunt for dark matter. Photo: Reidar Hahn

Physicists operating an experiment located half a mile underground in Minnesota reported this weekend that they have found possible hints of dark-matter particles.

The Cryogenic Dark Matter Search experiment has detected three events with the characteristics expected of dark matter particles, MIT graduate student Kevin McCarthy reported at the American Physical Society meeting in Denver on April 13. The result came about as part of McCarthy's thesis research.

Read more

Kathryn Jepsen

In the News

Iowa State, Argonne physicist preparing for first neutrino data from NOvA experiment

From Iowa State University News Service, April 10, 2013

AMES, Iowa – It won't be long before the NOvA experiment sends neutrinos on a 500-mile journey from northeast Illinois to northern Minnesota. And when one of those neutrinos shows up in the experiment's massive detector for the first time, Iowa State University's Mayly Sanchez will be right there.

Read more

Tip of the Week: Safety

Don't drive distracted

One text or call could wreck it all: Avoid distractions while driving.

Driver distractions have joined alcohol and speeding as leading factors in fatal and serious injury crashes. A distraction is any activity that could divert your attention away from the primary task of driving, including but not limited to:

  • Using a mobile communication device, for example, talking or texting
  • Adjusting a radio, CD player or MP3 player
  • Looking away from the road
  • Using a navigation system
  • Talking to passengers
  • Eating and drinking
  • Watching a video
  • Child care
  • Grooming
  • Reading

The National Safety Council estimates that 21 percent of all crashes in 2010 involved talking on cell phones, accounting for 1.1 million crashes that year. It also estimates at least 3 percent of crashes involve texting.

Many drivers mistakenly believe talking on a hands-free cell phone is safer than talking on a handheld device. Hands-free devices are often seen as a solution to the risks of driver distraction because they help eliminate two obvious risks:

  • The visual distraction of looking away from the road
  • The manual distraction of removing your hands from the steering wheel

However, a third type of distraction, a cognitive distraction, can occur when using cell phones while driving: taking your mind off the road. Hands-free devices do not eliminate cognitive distraction.

Multitasking is a myth. Medical research has shown that the human brain does not perform two tasks at the same time. The brain handles tasks sequentially, switching between a primary and a secondary task.

When the brain is experiencing an increased workload, information processing slows, and a driver is much less likely to respond to unexpected hazards in time to avoid a crash. The 2010 Illinois Text Messaging Ban states that a person may not operate a motor vehicle on a roadway while using an electronic communication device to compose, send or read an electronic message. There are exceptions for emergencies and public safety officials.

Cell phone distracted-driving crashes are tragic in part because they are so preventable. Families are forever changed, as you can see in this video, when a loved one is suddenly taken from our lives.

April is Distracted Driving Awareness Month, and you can find a variety of related free downloadable materials, including an infographic, posters and videos, at the National Security Council website. Join the NSC in observing Distracted Driving Awareness Month and take the pledge to drive cell-free.

Although Fermilab prohibits the use of cell phones while driving motor vehicles to include hands-free devices, there have been both complaints and tickets issued for driving while using an electronic communication device. Pull over to a safe place to talk on the phone, text or e-mail. For more on traffic safety at Fermilab, view this Traffic Safety Subcommittee Web page or this Business Services security Web page. You can also read the course material for the Traffic Safety Awareness Training Course.

J.B. Dawson

Photo of the Day

Is this a flying saucer or a fungus among us?

Leticia Shaddix, PPD, snapped this photo of an out-of-this-world fungus in Big Woods.
In the News

ATRAP nails down the antiproton's magnetic moment

From Physics World, April 8, 2013

Researchers working on the Antihydrogen trap (ATRAP) experiment at CERN have made the first single-particle measurement of the magnetic moment of the antiproton. Achieved with an uncertainty of 4.4 parts per million, the magnetic moment is exactly opposite to that of the proton, as predicted. This result is 680 times more precise than previous measurements made on exotic atoms containing antiprotons and is an important step towards understanding why the universe contains more matter than antimatter.

Read more


Today's New Announcements

Hubbard Street 2 Dance - Fermilab Arts Series - May 11

Fermilab Heartland Blood Drive - today and tomorrow

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

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

Engineering Group to hold seminars at Fermilab - April 26

Fermilab-CERN Hadron Collider Physics Summer School open for applications

Reminder - FSA debit card PIN required

International folk dancing meets Thursday evenings in Kuhn Barn

Indoor soccer

Fermilab Golf League

Indian Creek Riding Club

Chicago Fire discount tickets