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In this issue:
From the Director of LCLS: What is SXR?
Second LCLS Instrument Sees First X-rays
Bike to Work Day Is Coming May 13

SLAC Today

Friday - May 7, 2010

From the Director of LCLS: What is SXR?

(Photo - Jo Stohr)

It is 6:18 p.m. on Thursday night and I am getting a late start writing my SLAC Today column for tomorrow. I had planned to write it on LCLS-II because we just got the green light for this exciting project. I just decided, however, that this has to wait when I opened an e-mail sent at 4:43 p.m. which made me very, very happy. The e-mail signals the conclusion of a Cinderella story called SXR.

It officially started with a note I wrote on October 10, 2007 to John Galayda beginning with the sentence "This note serves to start a dialogue with Linac Coherent Light Source management to establish an MOU for use of hutch 1 for 'soft X-ray spectroscopy, scattering and imaging.'" The note reflected my interest as a scientist, shared by my SLAC colleagues Anders Nilsson and Z. X. Shen, to create a soft X-ray facility at LCLS with emphasis on the study of materials. The original roadmap document "LCLS – The first Experiments" written in the fall of 2000 had not envisioned such a soft X-ray facility because it focused on hard X-rays. Production of soft X-rays was mostly seen as a necessary step in commissioning LCLS which was thought to be easier at soft than hard X-ray energies, and for the study of atoms and molecules in gases as part of the Atomic, Molecular and Optical instrument. Instead, my colleagues and I were interested in using soft X-rays to study the electronic and magnetic structure of materials. Over the years we began to build the scientific case for such a facility on LCLS and it was in principle approved by the LCLS Scientific Advisory Committee. Problem was, there were funds only for four instruments for which construction was coordinated by LCLS/LUSI. So we had to think out of the box.  Read more...

Second LCLS Instrument Sees First X-rays

The beam.  (Photo by Julie Karceski.)

For the first time, scientists at the SLAC National Accelerator Center pumped ultra-short X-ray pulses through the Soft X-ray Materials Research instrument yesterday. The team has begun aligning the beam for commissioning measurements, and the first shift of user experiments are slated for early July.

"This is a genuine team effort and everyone involved has been working at full speed for months," said Bill Schlotter, one of two instrument scientists who are coordinating the SXR commissioning launch. 

The SXR instrument resides in the second experimental hutch along the Linac Coherent Light Source. The Atomic, Molecular and Optical Science instrument was the first to use beam from the LCLS in the fall of last year.

Over the next month, scientists will fine-tune the beam to work at its optimal performance. Yesterday they aligned the beam by threading it through a series of apertures barely larger than the beam itself. Today, they will adjust the monochromator, which selects a particular color or wavelength of the X-ray beam. In the days to come it will be calibrated so scientists can choose exact photon wavelength ranges to observe. The commissioning process also involves focusing the beam and correlating energy detectors, so that the number of photons coming through the beam can be measured along its length.  Read more...

Bike to Work Day Is Coming May 13

(Photo - cyclists and volunteers at SLAC Bike to Work Day 2009)
Cyclists and volunteers gather across the road from SLAC's main gate during the 2009 Bike to Work Day. (Photo by Mike Woods.)

Mark your calendars and pump up your tires: The San Fransisco Bay Area's 16th Annual Bike to Work Day will take place Thursday, May 13. SLAC volunteers Mike Woods, Kirk Stoddard, Dwight Harbaugh and Judy Fulton will host an Energizer Station for riders, one of eight Stanford community stations this year. SLAC's station will be open from 6:30 to 9 a.m.


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