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In this issue:
A Beamline is (Re)Born
People Today: Tom Hostetler is Still Having Fun
Reminder: Staff LCLS Tour Registration

SLAC Today

Wednesday - December 3, 2008

A Beamline is (Re)Born

SSRL staff scientist Thomas Weiss describes the SAXS experimental setup inside SSRL's Beamline 4.2 enclosure. (Photo by Brad Plummer. Click for larger image.)

For the first time in more than a year, Stanford Synchrotron Radiation Lightsource scientists and users now have access to a fully dedicated small angle X-ray scattering, or SAXS, beamline to study biological molecules. The new Beamline 4, which was moved from a previous location on the SPEAR storage ring and rebuilt from the ground up, also boasts two side stations—branch lines 4-1 and 4-3—for conducting X-ray absorption studies of biological and environmental samples.

SAXS is a technique in which a small amount of protein or virus suspended in solution is exposed to X-rays, which are scattered and picked up by a detector. It's used to study molecular dynamics that cannot be studied when the molecules are in a crystalline form. For example, the technique is useful in exploring how proteins fold. SAXS also is considered complementary to X-ray crystallography, which is used to create a high-resolution—but static—picture of the structure of biological molecules.  Read more...

(Weekly Column - Profile)

Tom Hostetler is Still Having Fun

Tom Hostetler, shown in the Beamline 2-2 experimental hutch, says he learns something new every day. (Photo by Calla Cofield. Click for larger image.)

Friends of Tom Hostetler may recognize the moment when he looks you square in the eye, his face focused on yours, and says, "You with me?" With that question, Hostetler checks to see whether his listener is on board as he leads down a path of explanation. From under his weather-beaten leather hat that smells of pipe tobacco, his eyes shine against tan skin. He'll amble through his knowledge of X-ray physics and engineering acquired after 20-plus years working at the Stanford Synchrotron Radiation Lightsource; pass by stories and memories from SLAC history; or just share his laid-back thoughts on life.

It's not surprising to learn that Hostetler studied philosophy before he ever learned physics. His inquisitive nature and somewhat spiritual perspective on life are just as prominent as his physics knowledge. Upon graduation from Stanford University in 1969, he alternated between thoughts of becoming a lawyer or a priest. An internship at SLAC and the woman he married changed those plans. He first worked at SLAC in 1967 as a summer student in Martin Perl's group, studying the rho meson, and then in David Leith's group. In SLAC's first decade, Hostetler recalls meeting Jonathan Dorfan, at the time a staff particle physicist, who would later serve as laboratory director. "He taught me how to eat a pear and have nothing left to throw away," says Hostetler.  Read more...

Reminder: Staff LCLS Tour Registration

Don't forget to reserve a space to join tomorrow's tour of the Linac Coherent Light Source. The registration deadline is noon today, so sign up while you still can! Bring your SLAC ID for the tour and wear long pants and comfortable closed-toe shoes. The walk is 3/4 of a mile long and will take approximately 45 minutes. Buses leave from Parking Lot C (across the street from the Stanford Guest House). See the tour Web page for online registration and more details.


(Photo - WIS tour of PEP)
Mike Sullivan and Kathleen Burrows (far left and right, respectively) introduced the essential functions of the PEP-II storage ring in a tour near Interaction Region 8 last week. (Photo by Shawne Workman. Click for larger image.)

All 25 spots were booked by 5:00 p.m. on the day that Women's Interchange at SLAC organizer Cherrill Spencer announced a November 25 tour of the PEP-II storage ring. Spencer said she aims to provide a glimpse of a lab area "that people don't usually get to see" each year. This year's tour gave participants a close-up look at the equipment that circulated PEP-II's electron and positron beams to their collision point inside the BaBar detector.

"The particles in the ring move so close to the speed of light that you can't tell the difference," said accelerator physicist and co-tour-guide Mike Sullivan. The facility set world records for luminosity—a measure of potential particle collisions—and generated data for more than 300 scientific papers that helped elucidate differences between matter and antimatter. Even months after the April 7 shutdown of the SLAC B Factory, ongoing analyses are expected to provide further discoveries for several more years, Sullivan said.

PEP-II Area Manager and co-tour-guide Kathleen Burrows noted that the ring's cooling water, required to avoid overheating during operations, is running even now to help prevent condensation and rust. The ring components are well maintained in anticipation of re-use. Multiple groups have expressed interest in the magnets and radio frequency components; possible destinations include Fermilab and a potential sister physics facility in Italy

(Photo - WIS tour of PEP)
WIS organizer and accelerator magnet engineer Cherrill Spencer (second from left) points out key elements of the PEP ring's focusing and bending magnets (visible near Spencer in adjacent yellow and blue boxes, and a red oblong below). (Photo by Shawne Workman. Click for larger image.)


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