SLAC Today is available online at:
http://today.slac.stanford.edu
In this issue:
New Telescope Will Focus Under Chilean Skies
Science Today: BaBar - Revealing the Nature of New States
ES&H Safety Concern: Suspect Rigging Items
Alpine Gate Update

SLAC Today

Thursday - June 1, 2006
(Image - LSST site)
El Peñón on Cerro Pachón, an 8,800-foot mountain peak in northern Chile, is the future site for the LSST. (Image courtesy of C. Claver, NOAO/LSST)

New Telescope Will Focus Under Chilean Skies

by Krista Zala

The Large Synoptic Survey Telescope (LSST) has found a home. The LSST Corporation Board of Directors has announced that they have selected Cerro Pachón, a 8,800-foot mountain in the Chilean Andes that already hosts two observatories, for the LSST.

The new observatory consists of three parts: the telescope that gathers and focuses light, a camera that records three-billion-pixel images, and a data management system that handles the 30 terabytes of data recorded each night.

Some twenty researchers at SLAC and the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) are currently helping to design the camera. This group, which is leading the R&D for the multi-institutional project, includes KIPAC Assistant Director and LSST Camera Scientist Steve Kahn and Camera Manager Kirk Gilmore. Read more...

(Daily Column - Science Today)

BaBar: Revealing the Nature of New States

by Daniele del Re

(Graph) On this plot of missing mass distributions, the DsJ(2460)+

contribution is circled.
(Click on image for full graph.)

After discovering the DsJ states in 2003, which produced a lot of excitement among particle physicists, BaBar scientists are now studying the properties of these new states.

In a paper recently submitted to Physical Review, BaBar researchers developed a powerful new experimental approach that exploits the large sample of e+e- → Υ(4S) collisions provided by the PEP-II accelerator. This method is based on the complete reconstruction of the Υ(4S) event, with the exception of the particle under study.

The event's "missing mass" (see image above) is then used to count how many times the DsJ(2460)+ particle has been produced in B meson decays. The analysis relies on the excellent track and photon reconstruction efficiency of the detector.

By combining this analysis with previous BaBar results the researchers find that around 75 percent of DsJ(2460)+ mesons decay via photon or pi emission to Ds(*). This first measurement of DsJ(2460)+ absolute decay rates casts further light on the nature of the recently discovered state. It also suggests that as much as 25 percent of the decays of these masons have not yet been observed.

Important Emergency Information

As of 9:00 a.m. this morning, the Stanford University and Hospital phone system is down and it is unknown when service will be restored. If you have an emergency, please use a cell phone to call 911 or the Stanford Police Department at (650) 329-2413. For non-emergency calls to the Stanford police, please use a cell phone and call (650) 280-7607 or (650) 924-3254.

ES&H Safety Concern: Suspect Rigging Items

by Dave Ernst

(Image - Rigging) Recently, unapproved rigging devices were discovered in general use at Jefferson Labs. A preliminary investigation indicates that these items probably came from experimental equipment brought to the lab by visiting researchers, and not through procurement channels.

ES&H asks all SLAC employees and users to inspect their hoist and rigging equipment for safety. For more information or to report unapproved equipment, contact the SLAC Hoist and Rigging Chair Dave Ernst (x3846) or ES&H Program Manager Linda Knudsen (x3019).

More information (pdf)...

Alpine Gate Update

by Kelen Tuttle

The construction at Alpine Gate continues, with crews beginning the final phase of the drainage and road improvement project this month.

In addition to updating the Alpine Gate road and drainage system, construction crews recently moved the guard shack several hundred meters further into the SLAC site to decrease congestion along Alpine Road. Crews are now installing power, phone and internet cables to feed a LCLS contractor trailer that will soon be installed near the newly located guard shack. This trailer is where LCLS contractors will attend orientation, take safety training courses and gather their SLAC badges before entering the site.

Thank you for your patience and understanding. A reopening date has not yet been set; please stay tuned to SLAC Today for additional updates as they become available.

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