SLAC’s newest X-ray laser fires up with world-class performance

Aside from shining a billion times brighter than prior technology, SLAC National Laboratory’s newly upgraded Linac Coherent Light Source (LCLS-II) heralds trailblazing research capabilities that could unlock the insights needed to create carbon-neutral steel, more sustainable fertilizer, more efficient hydrogen-powered cars or the next generation of pharmaceuticals, to name a few possibilities.

Late August, when SLAC scientists first tried to awaken the LCLS-II X-ray free-electron laser one magnet at a time, no sign of life was appearing on their live monitor readouts, said Mike Dunne, LCLS director and photon science professor. But when the last of the 21 magnetic structure components slid into place, an unassuming blot of X-rays popped up onscreen, prompting jubilant applause alongside sighs of relief.

Further tuning and testing followed over subsequent days before the accelerator’s capabilities were fully proven. In November, it will be in full service, available to researchers around the world.

 “I came here, almost nine years ago now, for this moment,” Dunne said. “This is the time to be around.”

“We can freeze frame the motion of the atoms … as they make chemical bonds or chemical bonds are broken, or as a quantum material comes up with its amazing properties of superconductivity, or as a virus invades your cell, you can actually study in a stop-motion movie what’s happening in the natural world,” he said.

This level of microscopic finesse is possible because images can be reconstructed from the diffraction patterns observed after X-ray light bounces off particles of interest. LCLS-II can fire at about one million times per second, which is five orders of magnitude greater than that of its predecessor.

LCLS-II is the result of a decade-long collaboration involving more than 1,400 individuals, including those from Fermilab, Argonne, Jefferson Lab, Berkeley Lab, the Facility for Rare Isotope Beams and Cornell University, according to LCLS-II Director Greg Hays. He also said the collaboration involved partners from outside the United States like Germany, Japan, Switzerland and France.

Hays first came to SLAC in 2006 to build laser components for the original LCLS and became involved with LCLS-II starting in 2011.

“This will be a machine that is going to be used for the next 25 to 30 years and will have a diverse, long-lasting impact in science,” he said.

Dunne said this new laser will also lend itself well to interdisciplinary collaboration between a host of fields, including bioengineering, quantum computing and photovoltaics.

Before, assembling a model of a single atom could take a year of nonstop data collection, Hays said, “but with an LCLS-II machine, you can do that in a matter of a day.”

Certain research on biological and chemical systems — such as sustainable manufacturing, ultrafast computing and pharmaceuticals — can only be done today using high-powered lasers like LCLS-II, said Mike Witherell, the Berkeley Lab director.

“There are a lot of these technologies that are not ready to deploy right today,” he said. “We’ve got to solve some R&D problems to see how to make them better, faster, cheaper. And that’s a lot of what this research is needed for.”

Every six months, SLAC hosts a competition in which scientists in medicine, atomic physics and several other fields petition to have time with the facility for their work, Dunne said. These submissions are run through an external peer review process and the top 20% from each field are granted access to the requested equipment.

Stanford University operates SLAC for the U.S. Department of Energy (DOE). With regular funding from the DOE, research at SLAC has expanded since its founding in 1962 to encompass materials science, high-energy astronomy, particle physics and more.

SLAC is one of 17 DOE-supported national laboratories in the U.S., and each one is affiliated in some way with a university, but Dunne said that the depth of SLAC’s partnership with Stanford in particular is unmatched. A wide range of members of the Stanford community, from undergraduates to senior professors, could potentially contribute to the conception, design and development of innovations like LCLS-II, he said.

Over the decades, the research center has established a storied lineage of scientific breakthroughs, including the discovery of the quark, the first direct evidence of dark matter and detailed imaging of DNA transcription. Four Nobel Prizes have been awarded for the research of six SLAC-affiliated scientists.

Today, scientists from around the world are already lined up for their turn with LCLS-II — including this year’s laureates for the Nobel Prize in Physics: Pierre Agostini of the Ohio State University, Ferenc Krausz of the University of Munich and Anne L’Huillier of Lund University.

Agostini, Krausz and L’Huillier have all contributed to pioneering work in the field of attosecond science in their careers, leading to new experimental methods for visualizing how electrons move inside atoms and molecules. An attosecond is one quintillionth of one second.

LCLS-II is the “greatest source” of attosecond pulses in the world and “SLAC is deeply engaged with that research community,” Dunne said.

“We can study how those attosecond X-rays tell us about what’s happening at the speed of an electron going around an atom,” he said. “That tells you the fundamentals, the basic building blocks of chemistry.”

Witherell said he looks forward to new insights into how photosynthesis works on a chemical level through the fine-grained view that LCLS-II provides, as well as discoveries in how to make clean energy technologies easier to produce.

“I’m really proud of SLAC for leading this team,” he said. “This is really a complicated and difficult facility to build and they really deserve a lot of credit for being able to carry this to the end.”

Next up is the high-energy upgrade on LCLS-II, which Hays said he started to work on in 2018 and will now continue to build into the foreseeable future. The project will feature “the same cast of characters,” Hays said.

“I never want to underemphasize the importance of our partner labs,” Hays said. “They brought their skill, their time, their people and they worked tireless hours to make these things come together.”

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