A simulated tau/anti-tau event in the BaBar detector. (Image courtesy of Swagato Banerjee.)

A Particle of a Different Flavor?

by Amber Dance

Just as chocolate ice cream never spontaneously becomes strawberry or vanilla, leptons—electrons, muons and taus—are supposed to conserve their "flavor," or family. That is, taus can decay into tau neutrinos, but not electron or muon neutrinos, and when a decay produces one kind of lepton, a matching anti-neutrino should come with it. Researchers at SLAC are currently searching for evidence that one lepton breaks these rules. If they succeed, it would pave the way for new physics.

The rules come from the Standard Model of particle physics—but many physicists believe that the Standard Model isn't complete. According to Soeren Prell, current BaBar physics analysis coordinator and a professor at Iowa State University, almost every particle physics measurement is checked against the Standard Model and generally the theory holds up remarkably well. However, the theory can't explain everything, and several new extensions are waiting in the wings. The search for lepton-flavor-violating processes is one of many efforts to discover violations of the Standard Model.

BaBar's primary objective is to study B mesons, produced by the collision of electrons and positrons. But, in addition, such collisions produce large numbers of tau and anti-tau particles. Members of the BaBar tau analysis working group, led by Swagato Banerjee and Alberto Lusiani, are combing through Babar's copious data to search for lepton flavor violation. Read more...

Traffic at the Main Gate

SLAC's Main Gate.

The traffic regulations in place at the Main Gate are intended to allow for the smooth flow of traffic into and out of the SLAC site. Please be careful as you make your way though the Main Gate and be sure to follow the posted regulations.

Main Entry
The main entry is a "T" intersection with a two-way stop. Vehicles coming on-site turning either left or right onto the Loop Road have the right of way and do not need to stop.

Westbound Traffic
Vehicles traveling westbound on the Loop Road and exiting the site do not have to stop; however, westbound vehicles continuing on around the Loop Road must stop and yield to vehicles approaching from the north (right), entering the site.

Eastbound Traffic
Vehicles traveling eastbound must stop and yield to vehicles approaching from the north (left) or exiting the site from the west. In the interest of traffic safety and good citizenship, all individuals driving a vehicle on the SLAC site should observe all traffic regulations.

If you have any questions about driving policies at the lab, please contact SLAC Security Manager Simon Ovrahim at x2310.

SLAC Shows at SC 07

by Kelen Tuttle

Yemi Adesanya (left) and Tofigh Azemoon set up the SLAC/Stanford display at SC07. (Image courtesy of Alf Wachsmann; click on image for larger version.)

Earlier this month, 14 SLACers joined 300 exhibitors, more than 9,000 attendees, over a billion dollars in equipment and much of the world's newest and fastest information technologies at Supercomputing 2007.

Held in Reno, Nevada, the event offered a busy schedule of sessions, workshops, challenges, demonstrations and speakers. In addition, a massive exhibition floor brought together all the top contenders in high performance computing—including SLAC and Stanford University.

This year, the SLAC computing team partnered with several groups from Stanford University to set up a 5x5 monitor display floor. Conference attendees were invited to literally step into Stanford research by walking over the horizontal screens, which featured animations prepared by researchers in SLAC's Advanced Computations Department (ACD), BaBar, the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), LCLS Ultrafast Science Instruments (LUSI), Stanford University Medical Media and Information Technology (SUMMIT), Physics-based Simulation of Biological Structures (Simbios), the Stanford Cardiovascular Biomechanics Lab, the Center for Computational Earth and Environmental Science (CEES) and Folding@home.

In addition, the display included a cloud chamber, a cosmic ray detector, a klystron, a virtual surgery demonstration, the first Google IT storage system and a PlayStation 3 demonstrating Folding@home—a program that recently was named the world's most powerful distributed computing network by the Guinness Book of World Records.

"The event went extremely well," said Project Leader Alf Wachsmann of SLAC's Scientific Computing and Computing Services Group. "Many thanks to those who made this display possible, everyone from the Klystron Department to the Mechanical Fabrication Department's Welding and Carpentry shops."

See a photo of the SLAC and Stanford presenters here.

Events (see all | submit)

November 28: (9:00 a.m.) US ATLAS Tier 2 & Tier 3 Workshop
November 28: (12:00 p.m.) WIS Seminar "Stop Sitting on your Assets!" Wealth Enhancement Secrets
November 28: (4:00 p.m.) PULSE Seminar: Photo-dissociation of Br2 studied with time-resolved photo electron spectroscopy interpreted with theoretical simulations

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Lab Announcements

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Astronomy: Sloan at Five Nature
Argonne's Nuclear Energy Research Moves Toward Greater Reliance on Computer Simulation EurekAlert
Odd Little Stars Science

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View online at http://today.slac.stanford.edu/

A simulated tau/anti-tau event in the BaBar detector. (Image courtesy of Swagato Banerjee.) A Particle of a Different Flavor? by Amber Dance Just as chocolate ice cream never spontaneously becomes strawberry or vanilla, leptons—electrons, muons and taus—are supposed to conserve their "flavor," or family. That is, taus can decay into tau neutrinos, but not electron or muon neutrinos, and when a decay produces one kind of lepton, a matching anti-neutrino should come with it. Researchers at SLAC are currently searching for evidence that one lepton breaks these rules. If they succeed, it would pave the way for new physics. The rules come from the Standard Model of particle physics—but many physicists believe that the Standard Model isn't complete. According to Soeren Prell, current BaBar physics analysis coordinator and a professor at Iowa State University, almost every particle physics measurement is checked against the Standard Model and generally the theory holds up remarkably well. However, the theory can't explain everything, and several new extensions are waiting in the wings. The search for lepton-flavor-violating processes is one of many efforts to discover violations of the Standard Model. BaBar's primary objective is to study B mesons, produced by the collision of electrons and positrons. But, in addition, such collisions produce large numbers of tau and anti-tau particles. Members of the BaBar tau analysis working group, led by Swagato Banerjee and Alberto Lusiani, are combing through Babar's copious data to search for lepton flavor violation. Read more...

Traffic at the Main Gate SLAC's Main Gate. The traffic regulations in place at the Main Gate are intended to allow for the smooth flow of traffic into and out of the SLAC site. Please be careful as you make your way though the Main Gate and be sure to follow the posted regulations. Main Entry The main entry is a "T" intersection with a two-way stop. Vehicles coming on-site turning either left or right onto the Loop Road have the right of way and do not need to stop. Westbound Traffic Vehicles traveling westbound on the Loop Road and exiting the site do not have to stop; however, westbound vehicles continuing on around the Loop Road must stop and yield to vehicles approaching from the north (right), entering the site. Eastbound Traffic Vehicles traveling eastbound must stop and yield to vehicles approaching from the north (left) or exiting the site from the west. In the interest of traffic safety and good citizenship, all individuals driving a vehicle on the SLAC site should observe all traffic regulations. If you have any questions about driving policies at the lab, please contact SLAC Security Manager Simon Ovrahim at x2310.	SLAC Shows at SC 07 by Kelen Tuttle Yemi Adesanya (left) and Tofigh Azemoon set up the SLAC/Stanford display at SC07. (Image courtesy of Alf Wachsmann; click on image for larger version.) Earlier this month, 14 SLACers joined 300 exhibitors, more than 9,000 attendees, over a billion dollars in equipment and much of the world's newest and fastest information technologies at Supercomputing 2007. Held in Reno, Nevada, the event offered a busy schedule of sessions, workshops, challenges, demonstrations and speakers. In addition, a massive exhibition floor brought together all the top contenders in high performance computing—including SLAC and Stanford University. This year, the SLAC computing team partnered with several groups from Stanford University to set up a 5x5 monitor display floor. Conference attendees were invited to literally step into Stanford research by walking over the horizontal screens, which featured animations prepared by researchers in SLAC's Advanced Computations Department (ACD), BaBar, the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), LCLS Ultrafast Science Instruments (LUSI), Stanford University Medical Media and Information Technology (SUMMIT), Physics-based Simulation of Biological Structures (Simbios), the Stanford Cardiovascular Biomechanics Lab, the Center for Computational Earth and Environmental Science (CEES) and Folding@home. In addition, the display included a cloud chamber, a cosmic ray detector, a klystron, a virtual surgery demonstration, the first Google IT storage system and a PlayStation 3 demonstrating Folding@home—a program that recently was named the world's most powerful distributed computing network by the Guinness Book of World Records. "The event went extremely well," said Project Leader Alf Wachsmann of SLAC's Scientific Computing and Computing Services Group. "Many thanks to those who made this display possible, everyone from the Klystron Department to the Mechanical Fabrication Department's Welding and Carpentry shops." See a photo of the SLAC and Stanford presenters here.	Events (see all \| submit) November 28: (9:00 a.m.) US ATLAS Tier 2 & Tier 3 Workshop November 28: (12:00 p.m.) WIS Seminar "Stop Sitting on your Assets!" Wealth Enhancement Secrets November 28: (4:00 p.m.) PULSE Seminar: Photo-dissociation of Br2 studied with time-resolved photo electron spectroscopy interpreted with theoretical simulations Access (see all) Limited access to B015 and B245 parking lots TODAY Construction for seismic upgrade of Building 50 Alpine Gate & PEP Ring Road closed Gates 17 & 30 open 24-7 Research Yard bisected Announcements (see all \| submit) Lab Announcements Travel Paperwork Due by December 3 for 2007 Reimbursement Revised Winter Shutdown Schedule SLAC Bids Adieu to Communications Czar Neil Calder - December 13 Community Bulletin Board Second Harvest Food Drive A Christmas Carol - The Gift @ Notre Dame De Namur U. in Belmont - FREE News (see all \| submit) Astronomy: Sloan at Five Nature Argonne's Nuclear Energy Research Moves Toward Greater Reliance on Computer Simulation EurekAlert Odd Little Stars Science
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	Tuesday - November 27, 2007