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In this issue:
New Simulation Poised to Chart the Staggered, Scattered Cosmic Dawn
Science Today: Targeting the LCLS Bullseye
SLAC Users Organization Meeting
LCLS Construction Fences Removed Today

SLAC Today

Thursday - September 11, 2008

New Simulation Poised to Chart the Staggered, Scattered Cosmic Dawn

A portion of space 1 billion light years across, depicted in three moments of a reionization simulation comparable to the one pending in Alvarez and Ho's calculations. Dark colors indicate cold neutral gas, while red to blue to white indicates increasingly hot ionized gas. The bubbles form small but expand and merge. (Image courtesy of Marcelo Alvarez, Ralf Kaehler and Tom Abel. Click for larger image.)

A new simulation method recently developed by Stanford astrophysicist Marcelo Alvarez and Science Undergraduate Laboratory Internship student Patrick Ho spurns complexity to make headway in understanding the early universe's structure formation. Collapsing a complicated trajectory into a single relationship, their calculations cut simulation time from weeks to hours.

Short of trace amounts of helium, in early times there was only neutral (non-ionized) hydrogen. Simplicity, monotony—it matters little what one attributes to such a state: the smooth swathe that existed soon after the universe cooled from the Big Bang's hot mess of free electrons and energetic radiation is termed by astrophysicists the cosmological "dark ages." The preponderance of neutral hydrogen absorbed enough light to make this era all but opaque.  Read more...

(Daily Column - Science Today)

Targeting the LCLS Bullseye

The pending eve of first light at the world's brightest hard X-ray source tends to make one dream. I spend a lot of time dreaming of the ultimate game of darts—biomolecular darts.

One of the most exciting potential applications of the Linac Coherent Light Source is the ability to collect single pulse images of biological and inorganic materials that do not contain periodic structure,1 a requirement of the preceding technique, X-ray crystallography. At minimum, we will be able to take at- or near-atomic resolution two-dimensional images of complex materials, opening up a whole new world of nanoscale imaging with previously-unattainable time resolution. These experiments will have wide reaching implications from nanoscale manufacturing to energy production and human health.

This type of "FLASH" diffraction imaging was first reported in December 2006, using 25 femtosecond pulses from the soft X-ray free-electron laser in Hamburg, or FLASH, to image an object carved into a thin membrane.2 This experiment provided the foundations for an array of new applications of coherent X-ray diffractive imaging, ranging from femtosecond time-delay3 and massively parallel holography4 to monitoring nanoscale dynamics5 and single-particle imaging of encapsulated biomolecular complexes,6 cells, ellipsoidal nanoparticles and flame- or powder-dispersed aerosols.  Read more...

SLAC Users Organization Meeting

Remember to register for the SLAC Users Organization Meeting. SLUO 2008 convenes next Thursday, September 18, 8:00 a.m. to 6:30 p.m. in Kavli Auditorium. See also "SLUO Annual Meeting: SLUO2008" for details.

All SLAC and SLUO members are cordially invited to attend the meeting and the reception, which will follow in the breezeway from 6:30 p.m. to 8:30 p.m.

LCLS Construction Fences Removed Today

(Photo - LCLS research yard)
Construction fences in SLAC's Research Yard will be removed today, but the area remains a controlled-access construction zone. (Photo by Brad Plummer.)

Today, Research Yard fences maintained by Turner Construction Company around the Linac Coherent Light Source construction zone will be removed as civil construction wraps up. The site will remain a controlled-access construction zone, and requirements for personal protective equipment, or PPE, will still be enforced.

As a reminder, no one is allowed onto the construction site unless specifically authorized by LCLS or accompanied by a University Technical Representative. Contact Jesse Saldivar (x2261) for more information.

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