Joe Frisch holds a miniature waveguide for use on the LCLS coherent radiation monitors. The pinhole-size opening is the same size as the wavelength of radiation emitted by a passing electron pulse. (Click on the image for a larger version.)

Faster than a Speeding Femtopulse

by Brad Plummer

When the Linac Coherent Light Source (LCLS) begins delivering x-rays in 2009, it will be one of the most powerful x-ray instruments ever built. From this power will come one of the LCLS's most intriguing applications: atomic-scale imaging.

That's not easy. For researchers to produce x-rays with the right characteristics for gathering information on the atomic scale—where events are measured in quadrillionths of a second—the LCLS must first produce pulses of electrons that are extremely fast, faster in fact than typical instruments can measure. Regulation of the length and timing of these electron pulses will be crucial to any type of investigation of ultra-fast phenomena. But how do you go about measuring something that fast?

Oscilloscopes are the standard signal measuring devices used to characterize laser pulses and are precise down to around 20 picoseconds. Although this is extremely fast (light travels a mere quarter inch in 20 picoseconds), pulses from the LCLS will last only about 100 femtoseconds (one quadrillionth of a second—the amount of time light takes to travel a hair's breadth). Read more...

Dosimeter FAQs

(Photo - Dosimeter) Why must SLAC Personnel wear dosimeters?
The law requires radiation dose measurements for potentially exposed workers. Although radiation levels are low at most SLAC locations, we measure personnel radiation doses to ensure that dose levels are As Low As Reasonably Achievable (ALARA) and keep records which are required by the Department of Energy.

Where at SLAC do I have to wear my dosimeter?
If you are issued one or more SLAC whole-body dosimeter(s), you are required to wear them while working in or visiting areas that are defined as Radiologically Controlled Areas (RCAs); Radioactive Material Storage Areas; Radiation, High Radiation, and Very High Radiation Areas; and Contamination Areas.

What training do I need to get a dosimeter?
All employee, visitors, users and subcontractors are required to take Employee Orientation to Environment, Safety, and Health (EOESH) training at SLAC. General Electrical Radiation Training (GERT) certification is required for personnel who need unescorted access to Radiologically Controlled Areas (RCAs). Radiological Worker Training (RWT) is required for personnel identified as radiological workers.

More dosimeter FAQs can be found on the ES&H website.

WIS Lecture Today:
Antarctica 2.0: Where Did All the Ice Go?

(Photo - Leslie Roberts) Akin to the moon race, the race to reach the South Pole captured the world's attention at the turn of the 20th century. One hundred years later, scientific explorers report back to us on mega icebergs, shrinking glaciers, and stranded penguins. In Antarctica, global climate change and its effects are not discussed in the future tense.

In today's Women's Interchange at SLAC (WIS) Seminar, Leslie C. Roberts, Associate Director of the Stanford Publishing Courses and Antarctica Scholar, will talk about some of the latest research on climate change, how it gets reported to "the masses," and what we are to do with the 21st century version of Antarctica in "the news."

All are invited to attend this brownbag talk, which begins at noon in the Panofsky Auditorium.

Safety Seconds

by John Cornuelle

In yesterday's edition, I asked if you could identify the best problem-solving technique for when a previously good process suddenly stops working. A Kepner-Tregoe study found that the most effective problem solvers look only at things that changed in the system. The problem solvers realized that some combination of those changes would explain what went wrong in the process. This technique can be useful in evaluating close calls, accidents and injuries at the lab and beyond.

Events (see all | submit)

November 28: (12:00 p.m.) WIS Seminar: Antarctica 2.0. Where Did All the Ice Go?
November 28: (12:30 p.m.) Experimental Seminar: Discovery of Sigma_b

Access (see all)

Announcements
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Lab Announcements

Safety Orientation for Non-SLAC Employees (SON) now online

Community Bulletin Board

News (see all | submit)

ITER Agreement Signed FYI
Study Suggests the Existence of Ferroelectric Ice in the Universe PhysOrg.com
Atom Spied Interfering with Electron Flow New Scientist

View online at http://today.slac.stanford.edu/

Joe Frisch holds a miniature waveguide for use on the LCLS coherent radiation monitors. The pinhole-size opening is the same size as the wavelength of radiation emitted by a passing electron pulse. (Click on the image for a larger version.) Faster than a Speeding Femtopulse by Brad Plummer When the Linac Coherent Light Source (LCLS) begins delivering x-rays in 2009, it will be one of the most powerful x-ray instruments ever built. From this power will come one of the LCLS's most intriguing applications: atomic-scale imaging. That's not easy. For researchers to produce x-rays with the right characteristics for gathering information on the atomic scale—where events are measured in quadrillionths of a second—the LCLS must first produce pulses of electrons that are extremely fast, faster in fact than typical instruments can measure. Regulation of the length and timing of these electron pulses will be crucial to any type of investigation of ultra-fast phenomena. But how do you go about measuring something that fast? Oscilloscopes are the standard signal measuring devices used to characterize laser pulses and are precise down to around 20 picoseconds. Although this is extremely fast (light travels a mere quarter inch in 20 picoseconds), pulses from the LCLS will last only about 100 femtoseconds (one quadrillionth of a second—the amount of time light takes to travel a hair's breadth). Read more...

Dosimeter FAQs Why must SLAC Personnel wear dosimeters? The law requires radiation dose measurements for potentially exposed workers. Although radiation levels are low at most SLAC locations, we measure personnel radiation doses to ensure that dose levels are As Low As Reasonably Achievable (ALARA) and keep records which are required by the Department of Energy. Where at SLAC do I have to wear my dosimeter? If you are issued one or more SLAC whole-body dosimeter(s), you are required to wear them while working in or visiting areas that are defined as Radiologically Controlled Areas (RCAs); Radioactive Material Storage Areas; Radiation, High Radiation, and Very High Radiation Areas; and Contamination Areas. What training do I need to get a dosimeter? All employee, visitors, users and subcontractors are required to take Employee Orientation to Environment, Safety, and Health (EOESH) training at SLAC. General Electrical Radiation Training (GERT) certification is required for personnel who need unescorted access to Radiologically Controlled Areas (RCAs). Radiological Worker Training (RWT) is required for personnel identified as radiological workers. More dosimeter FAQs can be found on the ES&H website.	WIS Lecture Today: Antarctica 2.0: Where Did All the Ice Go? Akin to the moon race, the race to reach the South Pole captured the world's attention at the turn of the 20th century. One hundred years later, scientific explorers report back to us on mega icebergs, shrinking glaciers, and stranded penguins. In Antarctica, global climate change and its effects are not discussed in the future tense. In today's Women's Interchange at SLAC (WIS) Seminar, Leslie C. Roberts, Associate Director of the Stanford Publishing Courses and Antarctica Scholar, will talk about some of the latest research on climate change, how it gets reported to "the masses," and what we are to do with the 21st century version of Antarctica in "the news." All are invited to attend this brownbag talk, which begins at noon in the Panofsky Auditorium. Safety Seconds by John Cornuelle In yesterday's edition, I asked if you could identify the best problem-solving technique for when a previously good process suddenly stops working. A Kepner-Tregoe study found that the most effective problem solvers look only at things that changed in the system. The problem solvers realized that some combination of those changes would explain what went wrong in the process. This technique can be useful in evaluating close calls, accidents and injuries at the lab and beyond.	Events (see all \| submit) November 28: (12:00 p.m.) WIS Seminar: Antarctica 2.0. Where Did All the Ice Go? November 28: (12:30 p.m.) Experimental Seminar: Discovery of Sigma_b Access (see all) South Gallery Road temporarily closed between Sector 27 & 29 Building 40 construction Bldg 084 GLAST ISOC Facility construction Bldg 084 parking spaces closure Alpine Gate & PEP Ring Road closed Gates 17 & 30 open 24-7 Research Yard bisected Announcements (see all \| submit) Lab Announcements Safety Orientation for Non-SLAC Employees (SON) now online Community Bulletin Board Tree planting ceremony to remember R. Yeager Influenza vaccine is available in SLAC Medical Department SLAC Holiday Party - December 14th Cool the Planet: Tip #3 from Cool Families News (see all \| submit) ITER Agreement Signed FYI Study Suggests the Existence of Ferroelectric Ice in the Universe PhysOrg.com Atom Spied Interfering with Electron Flow New Scientist
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View online at http://today.slac.stanford.edu/


	Tuesday - November 28, 2006