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In this issue:
Gentlemen, Start Your Roadheaders
Safety Today: Computerized System to Keep Employees Safe
Jerry Jobe Celebrates His 33 Years at SLAC
Safety Seconds

SLAC Today

Tuesday - March 27, 2007

The LCLS roadheader. (Click here for larger version and additional photos.)

Gentlemen, Start Your Roadheaders

Tunnel excavation for the LCLS has officially begun behind the Collider Hall. After weeks of preparing a concrete portal through which to begin digging, crews fired up a machine called a "roadheader," which uses a rotating head spiked with Jurassic-looking teeth to chew through the soft sandstone. Excavation crews will spend the next nine months at work in the tunnel, eventually excavating the underground Far Experimental Hall and connecting to the Near Experimental Hall (NEH) currently under construction. (View the NEH webcam here.) 

Survey crews use a system of lasers to guide the roadheader along its underground path. A special low-profile excavator follows behind the roadheader to collect and remove the spoils. Crews stop digging every four feet to erect a steel brace and spray liquid concrete to shore up the inside of the tunnel.

Also underway this week, concrete trucks have returned to pour the walls of the NEH. Within the next couple of weeks, a second roadheader will be put to work in the Research Yard to excavate the Undulator Hall and connect it to the NEH. (View the Research Yard webcam here.)

(Column - Safety Today)

Computerized System to Keep Employees Safe

Until recently, SLAC's Personnel Protection System (PPS)—the devices that initiate a safety shutdown in the beamline—consisted of a very complex set of electromechanical relays and wires. The first computerized PPS using Programmable Logic Controllers (PLCs), designed by Control Safety Systems Engineers Patrick Bong and Joel Fitch, is now installed and running near the RF gun at the future Linac Coherent Light Source (LCLS). Beginning around 2010, the controllers will completely replace SLAC's relay system, controlling access to radiological areas and protecting employees working near the beam from radiation harm.

"Most other labs have been using programmable systems," Bong said. "When SLAC first opened, safety guidelines required mechanical, rather than computerized, safety systems. But safety PLCs are much safer than relays these days, and using them in personnel protection makes a lot of sense."

After seven years of research, development, and review, Bong and his group have designed a safe logic engine that will run in redundant computer software, eliminating 70% of the wire bulk found in mechanized systems. The PLC isn't immune to glitches, but Bong has taken precautions to greatly mitigate them. The controller is "internally redundant," meaning each of two processors checks itself for glitches and renders the system safe if it finds one.

"They're a lot like the safety shutdowns on carnival rides and ski lifts," Bong said. "And PLCs are easy to program and implement in this lab." An added benefit is that the computerized controllers will reduce the length of beam shutdown times because the PLCs are very reliable.

Bong is pleased that the new safety system will improve the lab's radiation risk reduction rating by a factor of 10. "We have never had any injuries from the beam," Bong said. "We're going to keep it that way."

Jerry Jobe Celebrates His 33 Years at SLAC

(Photo - Jerry Jobe)Jerry Jobe, SLAC's Associate Director for Business Services, retired on March 1 after 33 years of dedicated service to the lab.

"We have lost one of the mainstays of the Lab," said SLAC Director Jonathan Dorfan. "Working for 33 years in a variety of roles at SLAC made Jerry an invaluable resource to me and to his many colleagues over the years."

Jonathan went on to comment that, "Throughout his career at SLAC, Jerry deftly used his experiences in human resources (his first SLAC job), computing and artificial intelligence, budgets and finance, plus a few years away from SLAC in the corporate world, to bring leadership and improvements to our business processes. We will miss Jerry and his steady hand on the wheel."

A special "Open House" retirement reception for Jerry will held this Wednesday, March 28th, from 3:00 until 5:00 p.m. in the Research Office Building's Redwood Room. See details and instructions on how to RSVP here.

Jerry's successor, Stan S. Cohelan Jr., took over as Division Director for Business Services on Monday of this week. Stan is the former President and CEO of GNB Corporation in Sacramento.

A warm welcome to Stan as he joins the SLAC family!

Safety Seconds

I have mentioned before that learning from history is not just having a recollection of what has already happened. Real learning involves behaving differently in an upcoming situation from what either your or someone else's historical behaviors in that same situation were. So, for example, I am sure that Hitler and the German High Command were familiar with Napoleon's catastrophic invasion of Russia, yet that did not stop them from repeating the mistake with the same consequences.

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