SLAC at 55 | February 21, 2018 | Almanac | Almanac Online |


Cover Story - February 21, 2018

SLAC at 55

A look at what's new at this big-league laboratory

by Dave Boyce

It's been five years since the 50th anniversary of Menlo Park's SLAC National Accelerator Laboratory on Sand Hill Road — a straight, two-mile-long buried tube that's been pumping out high-speed subatomic particles since 1962 for scientists and engineers trying to advance human understanding of the universe. So what's new?

Here's a bit of news: SLAC's 2017-18 budget, according to the U.S. Department of Energy's Office of Science, is up 1 percent from the previous year. That's remarkable in that the 2016-17 budget was up 22 percent from 2015-16, and the 2015-16 budget was higher than the previous year by 13.5 percent.

The 2017-18 budget for the Office of Science, which supports operations at SLAC and nine other national research laboratories, is down 17 percent from two years ago.

"The President's FY 2018 budget request reflects the administration's goal to reprioritize federal discretionary spending while maintaining key investments in DOE's (Department of Energy's) core areas," said Allison Eckhardt of the Office of Science in an email.

When asked to comment on the proposed budget, SLAC spokesman Andrew Gordon referred The Almanac to the Department of Energy, which commented (above) through Ms. Eckhardt.

A strobe light

SLAC's accelerator was first used to push electrons to near the speed of light to see what happened when they collided. The federal funding continued after that area of research tapped out and scientists found other uses for the high-velocity electrons.

Since 2009, SLAC has used a third of its accelerator's length for its X-ray laser, a kind of strobe light that generates 120 X-ray pulses per second. To create the X-rays, electrons speed through a pipe about a fifth of an inch in diameter, passing between 224 sets of magnets that excite the electrons and cause them to wiggle and give off X-rays.

Over the past five years, SLAC scientists, and the engineers who design their special-purpose tools, have used X-rays to watch a virus preparing to infect a healthy cell, to test a device that could reduce the environmental costs of producing hydrogen for vehicle fuel, to prepare a form of carbon that improves battery storage capacity, and to develop a protein that disrupts the process by which cancers spread. And more.

In 2017 alone, they used the laser to sustainably produce ethanol from carbon dioxide, to decipher the atomic structure of an intact virus, to help uncover the blueprint of a vaccine for a hemorrhagic fever virus, and to create a stretchable plastic electrode from a substance used to thicken soup. And more.

The laser operates five days a week and provides experimenters with several thousand hours of research time annually — and accepts just 20 percent of the proposals received. "It's very tough to get time here," said Michael Minitti, a staff scientist and group leader leader at the soft X-ray facility. "We expect our users to publish," he added. "If they don't, we banish them."

If all that sounds interesting, a guided tour of SLAC may be interesting, too. SLAC employees are busy, but usually not too busy to answer questions from guests. Given that they're engaged in big science and draw on extraordinary abilities to form questions and analyze results — about half of the staff of 1,500 have advanced degrees in science and engineering — are they sober about the challenges they face? Are they solemn about the discoveries with which they're credited?

They are not. An atmosphere of cheerful brilliance seems to prevail. What else could those letters S, L, A and C mean? "Scientists Learning And Celebrating?" That would work. "So, Let's Analyze the Cosmos!" would not be misplaced. "Sciences, Like, Are Cool," could work, too, depending on your audience.

Targeting tumors

The routine for cancer patients undergoing radiation therapy is arduous. A patient at a clinic spends 30 minutes getting prepared and three to four minutes being irradiated, to be repeated every weekday for a month, according to Mike Fazio, head of the Klystron Department at SLAC.

Treatment is complicated by interference from bodily motions, including breathing, heartbeats and the movement of organs, Dr. Fazio said. Treating children usually requires anesthesia, "a big negative," he said.

SLAC is in a partnership with the Stanford medical school to develop "new types of accelerating structures ... that are extremely efficient and extremely compact," Dr. Fazio said. "If you can get the radiation in very quickly, in between heartbeats, basically, and image it in real time, you have improved that dramatically."

The plan is to encircle the patient with 16 compact accelerators and hit the tumor "where it needs to be hit," Dr. Fazio said. The system is expected to be ultra fast — it would deliver a month's worth of radiation treatment in less than a second — and highly accurate, with minimal side effects, high throughput and competitive on costs, he said.

"If you can minimize the side effect of all that radiation treatment in terms of damage to healthy tissue, you're way ahead," Dr. Fazio said.

Really big science

Work continues at SLAC on parts for the Large Synoptic Survey Telescope. In three or four years, this collaboratively built device should be sitting in the Atacama Desert in Chile, a premium spot for viewing the night sky of the Southern Hemisphere.

When it's up and running, it will photograph the entire southern sky every three or four nights for 10 years, SLAC experimental cosmologist Aaron Roodman said. The result should be 800 to 1,000 sets of nearly identical night sky images for scientists to analyze.

Using a camera sensor built at SLAC, the telescope will collect 15 terabytes of data every night, adding up to a collection of images of some 20 billion galaxies, 17 billion stars in the Milky Way, and between 5 million and 6 million solar system objects, Dr. Roodman said.

The collected observations will be the basis for "a multicolored movie of the (southern) sky to unprecedented dimness," everything from killer asteroids to the hypothetical ninth planet in our solar system to galaxies that are billions of light years away, he said.

The telescope's sensor will be about 250 times larger than that in a smart phone, Dr. Roodman said. Despite its size, it will be extraordinarily flat, varying from perfect flatness by no more than 11 microns, he said — a small fraction of the width of a human hair.

SLAC scientists' uses for the telescope data include looking for dwarf galaxies in the Milky Way, and studying dark energy, a mysterious phenomenon thought to be powering the accelerated expansion of the universe.

SLAC is also searching for evidence of dark matter, of which there is likely to be more than the everyday matter we can touch and see, said Thomas Shutt, a professor of particle physics, astrophysics and physics at Stanford University.

The target of the search is a particle about the size of a neutrino but with the mass of a heavy atom — a weakly interacting massive particle. If so-called WIMPs are out there, quantities of them pass through our bodies every second, Dr. Shutt said.

To detect these particles, it's necessary to shield the detector from background radiation, so a team from SLAC, the United Kingdom, Portugal and South Korea will be using a former gold mine in South Dakota, the same mine used to detect neutrinos.

Liquified xenon inside a large tank of water is the WIMP detector, Dr. Shutt said. SLAC scientists have assembled a detector prototype that should emit flashes of light if WIMPs bump into xenon atoms.

A speedier bullet

The U.S. Department of Energy has authorized a second X-ray laser for SLAC, this one using a superconductor that operates at -456 degrees Fahrenheit. The effect of such intense cold on electron behavior will produce X-rays that are 10,000 times brighter and 8,000 times faster than in the current laser, scientists said.

This $1 billion project, scheduled to be completed in the 2020s, is funded through the Office of Science and is a collaboration with four other national labs and Cornell University, according to a SLAC statement.

These lasers use X-rays to destroy — they annihilate molecules — but the scientists capture that action in the same manner that images by Massachusetts Institute of Technology photographer Harold E. Edgerton captured the action of a bullet passing through an apple.

While the velocity of a high-intensity X-ray is in a different class entirely than a bullet, the principle is the same, Dr. Minitti said. "You know the apple blows up, but you're at least capturing (images of) the state that it's in, a transient state," he said. "We do the same thing. It's just a billion times faster."

This reporter asked whether the high-energy bombardment of the molecule would bring on the observer effect — a phenomenon in physics in which actions taken to observe an object have the effect of changing the object before you can look at it, thereby compromising the observation.

"These are chemical processes that do obey the laws of physics," Dr. Minitti said. "When you dump all this X-ray energy into these molecules, they will be destroyed." But the exposures to the pulses are so brief in time that they capture the images before the object disintegrates, he said.

"We can take a picture of its state as the X-rays see it, and about six orders of magnitude later the thing will blow up," Dr. Minitti said. "We basically pioneered a technique called 'defract before destroy.'"

Tours of the SLAC laboratory on Sand Hill Road are available twice monthly, by registration only. To find out more or to register, go to


Like this comment
Posted by SLAC Engineer
a resident of Portola Valley: Westridge
on Mar 7, 2018 at 7:48 pm

The LCLS hard x-ray laser operates 7 days a week not 5 days a week as stated in the article.

Like this comment
Posted by Fred G. Kraese
a resident of another community
on Mar 9, 2018 at 3:46 pm

Is there a future commerical application for the "Speedier Bullet" research?

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