Thursday, Feb. 23, 2012

Have a safe day!

Thursday, Feb. 23
10 a.m.
Special Joint Experimental-Theoretical Physics Seminar - One West
Speaker: Ashutosh Kotwal, from Duke University
Title: Measurement of the mass of the W Boson from CDF with 2.2 fb-1
2:30 p.m.
Theoretical Physics Seminar - Curia II
Speaker: Gerben Stavenga, Fermilab
Title: Proton Decay and Non-Perturbative Proton Stability
3:30 p.m.
LHC Physics Center Topic of the Week Seminar - Sunrise WH11
Speaker: Michael Peskin, SLAC National Accelerator Laboratory
Title: Light Composite Higgs: The Third Way to Electroweak Symmetry Breaking - Part 2
3:30 p.m.
4 p.m.
Accelerator Physics and Technology Seminar -
One West
Speaker: David Bruhwiler, TechX
Title: Coherent Electron Cooling Simulations for Parameters of the BNL Proof-of-Principle Experiment

Friday, Feb. 24
3:30 p.m.
4 p.m.
Joint Experimental-Theoretical Physics Seminar - One West
Speaker: Joshua Spitz, Massachusetts Institute of Technology
Title: Results from ArgoNeuT

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a weekly calendar with links to additional information.

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Wilson Hall Cafe

Thursday, Feb. 23

- Breakfast: Apple sticks
- Santa Fe black bean soup
- Steak tacos
- Chicken Wellington
- Chimichangas
- Baked ham & Swiss on a ciabatta roll
- Assorted sliced pizza
- Smart cuisine: Crispy fried chicken salad

Wilson Hall Cafe Menu

Chez Leon

Friday, Feb. 24

Wednesday, Feb. 29
- Braised beef w/ rosemary-mushroom sauce
- Whipped potatoes
- Broccoli
- Espresso-walnut cake

Chez Leon Menu
Call x3524 to make your reservation.


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World's best measurement of
W boson mass tests Standard Model, Higgs boson limits

The new CDF result for the W boson mass, combined with the world’s best value for the top quark mass, restricts the Higgs mass to the green area, requiring it to be less than 145 GeV/c2. Direct searches have narrowed the allowed Higgs mass range to 115-127 GeV/c2.

Editor's note: A special scienitific seminar on this result will take place today at 10 a.m. in One West.

Just as firemen use different methods to narrow the location of a person trapped in a building, scientists employ two techniques to find the hiding place of the theorized Higgs particle: direct searches for Higgs interactions and precision measurements of other particles and forces.

Today, scientists from the CDF collaboration have unveiled the world's most precise measurement of the W boson mass, based on data gathered at the Tevatron accelerator. The precision of this measurement surpasses all previous measurements combined and restricts the space in which the Higgs particle should reside according to the Standard Model, the theoretical framework that describes all known subatomic particles and forces.

The result comes at a pivotal time, just a couple of weeks before physicists from experiments at the Tevatron and the Large Hadron Collider in CERN plan to present their latest direct-search results in the hunt for the Higgs at the annual conference on Electroweak Interactions and Unified Theories known as Rencontres de Moriond in Italy.

CDF collaborators have measured the mass of the W boson with a precision of 0.02 percent and found the particle's mass to be 80387 +/- 19 MeV/c2. They measured the particle's mass in six different ways, which all match and combine to produce the final result. CDF collaborator and Duke University Professor Ashutosh Kotwal will present the details of the measurement at a special seminar at Fermilab today at 10 a.m., and additional information will be posted after the seminar on the CDF website.

Direct Higgs search limits established by the LEP experiments many years ago require the Higgs boson to be heavier than 114 GeV/c2. The new W mass measurement and the latest precision determination of the mass of the top quark from Fermilab triangulate the location of the Higgs particle and restrict its mass to less than 145 GeV/c2. This is in excellent agreement with the latest direct searches at the LHC, which constrain the Higgs mass to less than 127 GeV/c2, and direct-search limits from the Tevatron, which point to a Higgs mass of less than 156 GeV/c2.

"The result couldn't align more with the direct Higgs search results than this," said CDF co-spokesman Rob Roser. "It indicates that if the Higgs boson exists, it should be right where we are looking."

The DZero collaboration at the Tevatron expects to release its updated W mass result in the next couple of weeks.

Read more

—Tona Kunz

In the News

Faster-than-light neutrino results may be due to bad cables

From Wired, Feb. 22, 2012

The sensational result that neutrinos can travel faster than the speed of light may be undone by nothing more than a simple mechanical error.

Scientists from the OPERA collaboration at the Gran Sasso National Laboratory in Italy have "identified two issues that could significantly affect the reported result," wrote OPERA spokesman Antonio Ereditato in an email.

The first issue is a faulty connection of the fiber-optic cable bringing the GPS signal to the experiment's master clock. The experiment's GPS may also have been providing the wrong timestamps during synchronization between events.

"These two issues can modify the neutrino time of flight in opposite directions," Ereditato wrote.

Back in September 2011, OPERA researchers found bunches of neutrinos arriving 60 nanoseconds earlier than should be possible if they were traveling at less-than-light speeds. The neutrinos traveled 450 miles from experiments at CERN near Geneva, Switzerland.

The findings seemed to contradict Einstein's theory of relativity, which states that nothing can move faster than light. Many in the physics community kept a skeptical view of the findings, suggesting that some unknown source of error had perhaps entered the experiment.

Read more

In the News

Fermilab set to reveal "interesting" Higgs boson results

From Scientific American Observations Blog, Feb. 17, 2012

Last fall, the Tevatron accelerator at Fermilab in Illinois shut down for good. The long-running accelerator had been eclipsed by the vastly more powerful Large Hadron Collider outside of Geneva, Switzerland, which since 2010 has been generating data at an impressive rate. The move appeared to quash any hopes that Fermilab had of discovering the Higgs boson, the last great known unknown of modern particle physics.

Yet according to Rob Roser, the leader of the CDF experiment at the Tevatron, we shouldn't count Fermilab out quite yet. Though the machine is no longer generating data, physicists have not had time to properly analyze all the data that has been collected thus far. Today at the annual meeting of the American Association for the Advancement of Science, Roser announced that Fermilab will reveal its final Higgs results in March. "We will be able to say something interesting," he said, "though whether it is that we don't see it or we do see it remains to be seen."

Asked to clarify, Roser said that if the Higgs has a mass of around 125 gigaelectron volts—the mass that recent LHC results seem to indicate is most likely—the Tevatron would be able to identify the Higgs with "three-sigma" certainty. This is a statistical term that indicates the finding only has a tenth of a percent chance of being due to a random statistical fluctuation. Such a result would still fall short of being considered a "discovery," however, as the field of particle physics has adopted the more stringent five-sigma standard—a one-in-a-million chance.

Read more

Result of the Week

Missing pieces the key to measuring weak boson pairs

Neutrinos are inferred by a momentum imbalance after adding up all visible detector activity. This conservative estimator helps reject background events where that momentum imbalance is measured poorly.

The simultaneous production of two weak force carriers is a major background to the Higgs boson search. It also gives physicists an opportunity to study the weak sector of the Standard Model and probe for signs of new physics. A new DZero analysis focuses on the rarest of these processes, when a Z boson is produced at the same time as either a W boson or another Z boson. Each study starts by examining events with a pair of charged leptons that are consistent with a Z boson decay. But part, if not all, of the second boson's decay products in this analysis are invisible.

The W boson and the Z boson can produce neutrinos when they decay, and neutrinos are not seen directly by detectors built for collider experiments. Instead, their existence must be inferred by the imbalance of momentum their absence leaves behind. If the sum of the transverse momentum for all observed particles is not zero, then the missing piece must reflect the total transverse momentum carried away by neutrinos. However, the uncertainty of this measurement is influenced by the finite resolution of the momentum of every particle observed in the detector.

The DZero analyzers combat this compounded resolution problem differently in WZ or ZZ production. When a W boson produces the neutrino, in addition to a third charged lepton, the estimate of the missing transverse momentum is constrained by performing a fit on the Z boson decay products. For events in which a second Z boson decays into two neutrinos, the analyzers calculate the minimum feasible missing transverse momentum when considering the resolution of all the particles observed in the event. The cut on this missing transverse momentum estimator was optimized before looking at the data in the signal region and was chosen to minimize the total uncertainty on the cross section measurement. The final results from DZero represent the most precise cross section measurement in both channels at a hadron collider to date.

—Mike Cooke

These physicists made major contributions to this analysis.

The data quality group reviewed all of the data recorded by the DZero detector before it was used in any physics analysis. Analyzers rely on the data quality group's certification to ensure that every subdetector they require was delivering reliable information for all of the events they use.

Accelerator Update

Feb. 20-22

- The Main Injector LCW system was reconnected to CUB
- The EDIT School resumed taking beam
- Power Supply personnel repaired the Main Injector MI-30 quadrupole magnet power supply
- Linac personnel repaired a Linac RF station

Read the Current Accelerator Update
Read the Early Bird Report
View the Tevatron Luminosity Charts


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Weekend SharePoint outage -
Feb. 24 through Feb. 26

Butts & Guts - Mar. 1

Fermilab Lecture Series presents "The Intensity Frontier" - Mar. 23

Special Joint Experimental-Theoretical Physics Seminar -today

Embedded Design with LabVIEW FPGA and CompactRIO class scheduled - today

Introduction to LabVIEW scheduled - today

Weekend SharePoint outage beginning Feb. 24

SciTech preschool open house -
Feb. 25

PowerPoint 2010: Intro. - Feb. 28

No on-site prescription safety eyewear - Feb. 29

URA Visiting Scholars Program deadline - Feb. 29

Free ACU demo "Understanding Credit Reports" - Mar. 1

The University of Chicago Tuition Remission Program deadline -
March 2

Gallery Series present Arianna String Quartet - Mar. 4

NALWO Luncheon - Mar. 8

Word 2010: Intro Mar. 6

Excel 2010: Intro. - Mar. 8

Fermilab Arts Series presents Eileen Ivers & Immigrant Soul - Mar. 10

Access 2010: Intro. - Mar. 14

FRA scholarship applications due Apr. 1

Python Programming class - April 16-18

Martial arts classes

Fermilab Management Practices courses are now available for registration

"5 Treasures" Qigong for stress relief

NALWO - Volunteers needed for English conversation

Requests for on-site housing for summer

International folk dancing Thursday evenings in Kuhn Barn

Scottish country dancing Tuesday evenings in Kuhn Village Barn

Open badminton at the gym

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Atrium construction updates

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