SLAC Today is available online at:
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In this issue:
Attobarns: Not for Your Average Size Cow
Science Today: Tau Analysis Team to Resume Search for Lepton Flavor Violation
Photo: LSST All-Hands
Two SLAC Physicists Become APS Fellows

SLAC Today

Thursday - December 7, 2006

Attobarns: Not for Your Average Size Cow

(Image - Barn)
Image courtesy of Alan Chou

Today, BaBar collaborators are holding an all-day workshop on "1/ab." Not familiar with the term? It stands for inverse attobarns, which means big things for BaBar.

An inverse attobarn corresponds to one billion pairs of B and anti-B particles produced by the PEP-II accelerator. More data means more physics.

For BaBar, this number will be 10 years in the making, from when the experiment turned on in 1999 to when it ends in September 2008. To date, the experiment has generated almost half an inverse attobarn.

"To put that in perspective, when BaBar turned on the total number of B, anti-B pairs collected by previous electron-position colliders operating at this energy was roughly 10 million. Now we are less than two years from achieving one billion pairs collected," said Jim Olsen, BaBar's physics analysis coordinator.  Read more...

(Daily Column - Science Today)

Tau Analysis Team
Continues Search for
Lepton Flavor Violation

(Image: interaction)
A simulated tau-tau+ event in the BaBar detector. Click on image for larger version and explanation. (Image courtesy of S. Banerjee.)

While much of the work at the SLAC B Factory has been on B-meson physics and the study of subtle matter-antimatter asymmetries in the laws of physics, a BaBar team has also been exploiting PEP-II's ability to produce copious quantities of another type of particle, the tau lepton.

In the Standard Model of Particle Physics, the electron, the muon and the tau make up the family of fundamental particles called charged leptons, and each has a neutral partner called a neutrino. The tau, being relatively heavy, can decay into an electron or a muon, or into many other types of particle. In the Standard Model, modified to include the effects of recently discovered neutrino oscillations, tau-lepton decays almost always produce a tau neutrino, conserving a quantity called lepton flavor. The neutrinos are impossible to detect at BaBar, so their presence is inferred from missing energy, an imbalance between the energy of the original tau and the observed energy of its decay products.  Read more...

Photo: LSST All-Hands

(Photo - LSST All Hands Meeting 2006)
Click on image for larger version.
(Image courtesy of Diana Rogers.)

More than 100 LSST collaborators are currently at SLAC to take part in their third All-Hands Meeting. A warm welcome to them all!

Two SLAC Physicists
Become APS Fellows

The American Physical Society has awarded fellowships since its inception in 1899. The Society currently awards fellowships to approximately 200 members a year, about one half of one percent of their total membership. To receive a fellowship, APS members are nominated and elected by APS fellowship committees and the APS Council. Fellowship is an honor signifying recognition by one's professional peers.

SLAC Today is pleased to congratulate:

Piero Pianetta
Citation: For his pioneering contributions to the synchrotron based photoelectron spectroscopy study of electronic structure of surfaces and interfaces.
Nominated By: Condensed Matter Physics (DCMP)

Mark Hogan
Citation: For scientific achievement and leadership in the development of electron and positron beam-plasma interactions, including the first experimental demonstration of meter-scale wakefield acceleration.
Nominated By: Physics of Beams (DPB)

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