Fermilab Today

	Friday, April 22, 2011

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Calendar

Have a safe day!

Friday, April 22
3:30 p.m.
DIRECTOR'S COFFEE BREAK - 2nd Flr X-Over
4 p.m.
Joint Experimental-Theoretical Physics Seminar - One West
Speaker: Patrick Fox, Fermilab
Title: Hunting for Dark Matter at the Tevatron

Monday, April 25
2 p.m.
LHC Physics Center Topic of the Week Seminar - Sunrise,WH11NE
Speaker: Christopher Rogan, California Institute of Technology
Title: Razor for Searches at the LHC
2:30 p.m.
Particle Astrophysics Seminar (NOTE LOCATION) - Hornet’s Nest, WH8XO
Speaker: Jillian Bellovary, University of Michigan
Title: The Formation and Evolution of Massive Black Holes in Cosmological Simulations
2:30 p.m.
DIRECTOR'S COFFEE BREAK (NOTE TIME) - 2nd Flr X-Over
4 p.m.
All Experimenters' Meeting - Curia II
Special Topics: Science Being Done on the Wilson Cluster; T-992: SLHC Rad-Hard Sensor Tests at FTBF

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a weekly calendar with links to additional information.

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Secon Level 3

Wilson Hall Cafe

Friday, April 22

- Breakfast: Chorizo burrito
- *Chunky vegetable soup w/orzo
- Buffalo chicken wings
- Cajun breaded catfish
- *Teriyaki pork stir-fry
- Honey mustard ham & Swiss panini
- Assorted sliced pizza
- *Carved turkey

*Heart healthy choice

Wilson Hall Cafe Menu

Chez Leon

Friday, April 22
- Closed

Wednesday, April 27
Lunch
- Gingered flank steak
- Sake glazed vegetables
- Rice pudding

Chez Leon Menu
Call x3524 to make your reservation.

STEM Career Expo at Fermilab draws hundreds of students

Technical Division employee David Harding talks to a high school student during the 2010 STEM Career Expo at Fermilab.

On Wednesday, April 13, an estimated 550 students and parents from the western suburban Chicago area visited Fermilab to talk to scientists and professionals at the STEM Career Expo.

“As a science laboratory, it is our responsibility to train the next generation of scientists,” said Susan Dahl, Fermilab Education Office. “We wanted to give the students a real experience talking one-on-one with people working in the industries.”

This was the fourth year for the STEM Career Expo at Fermilab, which aims to help high school students get a better understanding of the type of work people do in various jobs and figure out what interests them, Dahl said.

“Freshmen can start thinking about what courses they want to take in high school,” Dahl said. “Students getting ready for college can acquire firsthand knowledge of various career paths by speaking with professionals in those specific fields.”

Mark Bollinger, deputy manager of the DOE Fermi Site Office, said the event provided a much-needed opportunity to emphasize to students the importance of science and engineering in society.

“If we glorified scientists and engineers as much as we did the athletes, we wouldn’t have a problem, it would be easy,” he said.

Students and parents alike expressed gratitude for the opportunity to talk with scientists and engineers in their post-event evaluations.

“The professionals were so helpful and clear, explaining what they do and how it works,” wrote one parent from Geneva.

A sophomore from Geneva High School wrote, “I really liked being able to just pick the brains of everyone here and learn about everything they had to offer."

Bollinger said he was encouraged by the students’ enthusiasm.

“Personally, it was invigorating to see all the interest in science,” Bollinger said. “It was great to have them all come to Fermilab and be able to highlight what we do.”

-- Christine Herman

InterActions.org press release

LHC sets world record beam intensity

Around midnight this night CERN's Large Hadron Collider set a new world record for beam intensity at a hadron collider when it collided beams with a luminosity of 4.67 x 10³²cm^-2s^-1. This exceeds the previous world record of 4.024 x 10³²cm^-2s^-1, which was set by the US Fermi National Accelerator Laboratory's Tevatron collider in 2010, and marks an important milestone in LHC commissioning.

"Beam intensity is key to the success of the LHC, so this is a very important step," said CERN Director General Rolf Heuer. "Higher intensity means more data, and more data means greater discovery potential."

Luminosity gives a measure of how many collisions are happening in a particle accelerator: the higher the luminosity, the more particles are likely to collide. When looking for rare processes, this is important. Higgs particles, for example, will be produced very rarely if they exist at all, so for a conclusive discovery or refutation of their existence, a large amount of data is required.

The current LHC run is scheduled to continue to the end of 2012. That will give the experiments time to collect enough data to fully explore the energy range accessible with 3.5 TeV per beam collisions for new physics before preparing the LHC for higher energy running. By the end of the current running period, for example, we should know whether the Higgs boson exists or not.

In the News

The sound of accelerator cavities

From ILC Newsline, April 21, 2011

Liquid helium’s curious properties help scientists focus on cavity defects.

Heat waves aren’t always a bad thing. For scientists working on accelerator cavities, they provide a simple way to locate hard-to-see surface defects, which can turn an otherwise superconducting cavity into a dud.

Cornell University’s second-sound detection system homes in on a cavity defect, such as a pit hiding in the cavity wall, by tracking the heat that emanates from it once the cavity reaches a certain accelerating gradient.

“It’s turned out to be a very convenient, fast and effective way of isolating the defect location to less than an inch,” said Don Hartill, member of the SRF (superconducting radiofrequency) group at Cornell University. Because it calls for very little equipment, it’s also inexpensive.

In second-sound detection, sensors are positioned outside and around the cavity. The sensors and the cavity, powered by a radiofrequency transmitter, are submerged in a bath of liquid helium.

CMS Result

A little balance is hard to find

A schematic of the sort of collision debris that would hint at supersymmetry: a muon and an electron accompanied by jets and missing energy (invisible particles inferred from the lopsidedness of the rest of the debris). The vast majority of proton collisions produce only jets.

If you smash two protons together what would come out in the debris? In 99.9999 percent of the collisions, the result would be nothing but quarks and gluons, each of which then becomes a jet --- a spray of particles made of more quarks and gluons. Though these complex events contain many particles, less than half of the known fundamental particles are represented.

Leptons such as electrons, muons and invisible neutrinos only emerge in the last 0.0001 percent of cases. However, detectors such as CMS are designed to be especially sensitive to leptons. They can even see invisible leptons by measuring of missing energy, the lopsidedness of all the rest of the debris.

Many theories of new physics, some incorporating the supersymmetry principle, result in more balanced event pictures such as the one shown above. This is not true of all supersymmetric theories, but considering the Standard Model’s million-to-one preference for jets over leptons, searching for events with one or two leptons eliminates huge backgrounds from interactions that are already understood. Squarks, sleptons, and other supersymmetric variants of known particles could lead to events containing a little of everything: jets, leptons and missing energy.

CMS physicists recently searched for this kind of particle signature: two or more electrons or muons, two or more jets, and missing energy [paper]. Despite the enormous number of proton collisions in the 2010 dataset, the Standard Model predicts that only about one of them would fit such a strikingly balanced menu. One event was found, confirming the old theory and ruling out some, but not all, supersymmetric models. As the 2011 data pour in, CMS physicists are using this technique to uncover yet more elusive theories.

- Jim Pivarski

These US-based physicists, working in cooperation with physicists across the world, contributed to this analysis.

The CMS forward hadron calorimeter is needed to identify jets close to the beampipe and to measure missing energy more accurately. Pictured above are some of the physicists who recently completed an important upgrade of that system.

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