Tuesday - July 18, 2006
SLAC Today is available online at:
http://today.slac.stanford.edu
In this issue:
symmetry Logbook: The First Vertex Detector
Safety Today: Main Gate Safety
BaBar International Finance Committee Visits "France-West"
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Tuesday - July 18, 2006 |
symmetry Logbook: The First Vertex Detector The Positron Electron Project (PEP) collider at SLAC produced its first collisions in 1979. All sorts of particles burst out, including the tau lepton, an ephemeral cousin of the electron. Theory had predicted the tau's lifetime, but no one could measure it. John Jaros and his collaborators took on the challenge. "We built a precision drift chamber—the first collider vertex detector," he says. The device had to pinpoint two vertices: a tau's point of creation and its point of decay. Jaros's team installed the new precision instrument at the center of the Mark II detector in 1981. That September, postdoc Nigel Lockyer overcame the intricacies of the Mark II software and, for the first time, transferred signals from the vertex detector to Mark II's data acquisition system. This logbook shows his success—a cosmic muon traversing the entire Mark II detector—and notes "Nigel wins in overtime." The vertex chamber (solid circle) had recorded with unprecedented precision the muon's path (small crosses). Read more... |
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Main Gate Safety
Over the past few weeks, security guards have noticed an increase in vehicles unsafely passing bicyclists at SLAC's main gate. The majority of these safety concerns result from drivers not slowing down or not merging with enough care. "To keep everyone safe, we ask both drivers and cyclists to be cautious when approaching the main gate," says Simon Ovrahim. Ovrahim specifically asks drivers approaching SLAC from the west on Sand Hill Road not to cross into the bike lane until the white line becomes broken (see above image). Drivers merging early run the risk of hitting unseen bicyclists or other drivers who are merging after the solid white line ends. Security also asks that once drivers turn into SLAC they refrain from passing bicyclists. "When cyclists enter SLAC in the right lane, they often swerve left to give the guard a better view of their ID, coming too close to vehicles entering in the same lane," says Ovrahim. "We ask all drivers to slow down and proceed through the gate with caution." |
BaBar International Finance Committee Visits "France-West"
BaBar is an international collaboration, and the operating costs of the experiment are shared among the partners of the collaboration. Twice each year there is a meeting of representatives of the larger financial contributors, called the International Finance Committee (IFC). At these meetings the progress of BaBar is discussed, along with the financial needs of the experiment.
The most recent meeting was June 26th and 27th at a small but extreme western region of France: Washington D.C.'s French Embassy. The Embassy very generously offered to host the meeting at the request of Gerard Bonneaud, a member of BaBar who worked two years as the Scientific Counselor of the Embassy.
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