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In this issue:
Looking for the "On" Button
Director's Column: Welcome back!
Google Joins LSST Effort
Physics Today: Belief and Knowledge—A Plea About Language
Safety First

SLAC Today

Monday - January 8, 2007

Looking for the "On" Button

Matt Cyterski of the Accelerator Operations Department tests radiation safety systems in preparation for turning on the accelerator. (Click on image for larger version.)

After a hiatus of more than four months, SLAC's linear accelerator this week resumes its job delivering beams of electrons and positrons to PEP-II. The task of cycling the linac back into action began last November, with the whole process taking a team of more than 400 engineers, physicists and technicians two months to achieve. Turning SLAC's historic workhorse back on, perhaps not surprisingly, turns out to be quite a bit more complicated than simply pressing the "on" button.

The first priority for linac operators, of course, is safety. And with more than three miles of underground tunnels that must remain off-limits when the accelerator and PEP storage rings are running, it is little wonder the meticulous process of securing the linac housing and PEP tunnels takes time. In the case of the most recent shut down, a laundry list of Linac Coherent Light Source (LCLS) preparations, PEP-II upgrades, and maintenance projects filled the four-month calendar. Completing all this work and getting the linac back up to speed on schedule has required a complex choreography of overlapping activities.  Read more...

(Director's Column)

Welcome back to SLAC and very best wishes for 2007! I hope you all had a very restful and enjoyable holiday. Thanks to the hard work of a number of staff who worked through the holiday break, LCLS construction and linac-related installation activities were able to continue, post holiday resumption of SSRL and PEP-II programs and accelerator operations are able to proceed on schedule and upgrades are nearly finished on PEP-II.

The break was a busy time for LCLS construction. In the Research Yard, crews used the time to continue preparations for tunneling and to modify electrical utilities and water systems. Near the Collider Hall, construction workers continued excavation for the LCLS Near Experimental Hall. Major installation work was completed on the main linac modifications in the area of the new LCLS injector. I encourage you to watch the LCLS take shape by viewing these two sites with the construction webcams, which offer live feed of the accelerating progress on this major new venture.

SSRL accommodated users until December 22, when the SPEAR3 accelerator shut down until January 2 for the holidays. During the holiday shutdown, staff serviced monochromator, detector and vacuum systems, and utilized the short break in the user program to upgrade computer clusters, servers and domain control servers. SPEAR3 came up quickly after the break and the SSRL user program is already in full operation, marking the beginning of another busy year of user activities, R&D and beamline upgrades.

PEP-II is now coming to the end of 4 months of upgrades and general repairs. During this time, physicists, engineers and maintenance crews worked on many aspects of the accelerator including new power supplies for several of the quadrupole focusing magnets and the replacement of PEP-II’s two RF stations, which is one of the final steps that will allow operations at even higher currents.

A warm thank you to those who made the holiday break so productive and to everyone at the lab for your continued efforts in support of a safe and effective program at SLAC. We can all look forward to another exciting year of progress and science.

—Keith Hodgson

Google Joins LSST

(Image - LSST)
The Large Synoptic Survey Telescope, scheduled to see first light atop Cerro Pachón in Chile in 2013. (Simulated image courtesy of Michael Mullen Design, LSST)

Google has joined a group of nineteen universities and national labs that are building the Large Synoptic Survey Telescope (LSST).

Scheduled to begin operations in 2013, the 8.4-meter LSST will be able to survey the entire visible sky deeply in multiple colors every week with its three-billion pixel digital camera, probing the mysteries of Dark Matter and Dark Energy, and opening a movie-like window on objects that change or move rapidly: exploding supernovae, potentially hazardous near-Earth asteroids as small as 100 meters, and distant Kuiper Belt Objects. LSST is a public-private partnership.  Read more...

Physics Today:
Belief and Knowledge
A Plea About Language

(Photo - Helen Quinn)I remember the puzzlement of a friend as my husband described his thesis research—a coincidence experiment. His listener stopped listening; she was thinking about why anyone would try to measure coincidences. I pointed out that the word "coincident" simply means "occurring at the same time." The experiment used its precise timing to ensure that two particles detected at the same time had a very high probability of coming from the same source event. Thus the term coincidence was used in a sense opposite to the everyday meaning, where a coincidence is two uncorrelated events that come together.
Read more in Physics Today...

Safety Firsts

Most of you may recall that recently someone was murdered by polonium 210 poisoning, polonium being an extraordinarily fierce emitter of radiation. Would you be surprised to know that many of us are inhaling significant amounts of this material on a daily basis?

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