spectroscopy

Zain Abhari selected for SACLA graduate internship

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a woman stands in front of a tree with a Japanese castle in the near background
Zain Abhari on a tour at Himeji Castle, which is one of the last few fully intact castles in Japan and is located near the SACLA facility | Photo provided by Zain Abhari

Congrats to Physics PhD student Zain Abhari for being selected to the SACLA Research Support Program for Graduate Students. The one-year internship run by SACLA (the SPring-8 Angstrom Compact free electron LAser) accepts graduate students with a demonstrated interest in using X-ray free electron lasers (XFELs) for their research and provides them with training and beam time at the facility in Japan.

Prior to her acceptance in the program, Abhari had already spent time at SACLA as part of her research in Uwe Bergmann’s group. While there, her collaborator told her about the program and recommended she apply.

“My goal after the PhD is to work at one of these large-scale facilities, specifically the X-ray free electron lasers and there’s only six of them right now in the world,” Abhari says. “If I can get my foot in the door in Japan, or get the experience to then help me with any of the other ones, that would be pretty awesome.”

Abhari was also interested in the program because SACLA’s laser aligns well with the goals of her thesis research, which is to obtain intense, stable XFEL pulses to apply to different spectroscopy techniques. For about the past decade, XFEL has allowed researchers to make ultrafast movies of molecular changes, essentially helping them to see chemical reactions take place. But x-ray lasers are “dirty,” and they contain multiple wavelengths of light of varying intensity. Last year, Bergmann and his colleagues somewhat accidentally discovered a way to make the pulses cleaner through two intense, femtosecond-spaced pulses.

Even though the researchers think they know how the useful pulses work, producing and controlling them are a completely different story — and one that Abhari hopes to unravel in her research.

“Right now, they’re just random,” Abhari says. “So the goal is to understand them. And then if we understand them, can we control them? If we can control them, can we apply them?”

Abhari will travel to Japan for three months beginning in September, where the program provides on-campus housing and time on the laser. Without the access she is now granted by this internship, her research would have been much more focused on short rounds of data collection followed by off-site data analysis.

“Now, I can get my hands on the laser and collect data to try to understand parameters that allow us to get the specific output we’re looking for,” Abhari says. “I have data that allude me to what those parameters will be, but now in real time, I can be like, ‘If I do this, I see this; if I do that, I see that.’”

In addition to her thesis research, Abhari will be working with her SACLA collaborators on a machine learning project to optimize beam focusing, and helping learn about and improve a portable beam nanofocusing apparatus.

 

Congratulations to Professor Lawler on his retirement!

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After 42 years on the UW–Madison faculty, Jim Lawler, the Arthur and Aurelia Schawlow Professor of Physics, has announced his retirement. Lawler is an atomic, molecular & optical physicist with a focus developing and applying laser spectroscopic techniques for determining accurate absolute atomic transition probabilities. His retirement is official as of May 22.

“What we’ve really done gradually over four-plus decades is make atomic spectroscopy more quantitative so that people can use it to really learn the detailed physics and chemistry of the remote universe,” Lawler says.

Lawler received his MS (’74) and PhD (’78) from this department, studying with now-professor emeritus Wilmer Anderson. In the two years after earning his doctorate, he was a research associate at Stanford University, and returned to UW–Madison as an assistant professor in 1980.

“There was a little bit of a disadvantage to come back to a place where I had recently been as a student,” Lawler says. “But I knew I would get extremely good graduate students and I would have access to a lot of infrastructure, and that combination really drew me back.”

He had extremely good graduate students and postdocs. Lawler supervised 26 PhD students and 10 terminal MS students. Those students and postdocs have gone on to prestigious National Research Council Fellowships, group lead positions at major companies, and tenured professorships, amongst many others.

Lawler served as department chair from 1994-1997. He also accumulated numerous awards and honors over his distinguished career. He is a fellow of the American Physical Society, the Optical Society of America, the U.K. Institute of Physics, and in 2020 he was elected a Legacy Fellow of the inaugural class of American Astronomical Society Fellows. He won the 1992 W. P. Allis Prize of the American Physical Society and the 1995 Penning Award from the International Union of Pure and Applied Physics for research in plasma physics, the two highest National and International Awards in the field of Low Temperature Plasma Physics. In 2017, he won Laboratory Astrophysics Prize of the American Astronomical Society for research in spectroscopy.

Longtime collaborator Blair Savage, UW–Madison professor emeritus of astronomy, says:

“Jim’s work in laboratory astrophysics provided extremely important atomic ultraviolet transition probabilities in support of the Hubble Space Telescope programs to determine elemental abundances of gaseous matter in the interstellar medium from three different ultraviolet spectrographs over the 32-year history of the space observatory. They included the Goddard High Resolution Spectrograph, the Space Telescope Imaging Spectrograph and the Cosmic Origins Spectrograph.”

And Wilmer Anderson, Lawler’s doctoral advisor, says:

“He was a very good graduate student, and he of course has turned out to be a really great scientist and colleague. His lifetime measurements on atomic physics played a key role in understanding the neutron star collisions. I’m sorry to see him retiring but I’m sure that he will leave a legacy behind that’s really fantastic. It’s going to be a big loss to the department not to have him around.”

Lawler has collaborated with his AMO colleagues over the years, but in more of an intellectual capacity than in research. As he notes, much of AMO is headed in the quantum information and quantum computing direction, with public and private funding helping to drive it. Still, he does not see AMO headed solely in the quantum direction.

“Decades from now the currently Hot areas of physics will be less glamorous, but those stars are still going to be light years away,” Lawler says. “I think the connection of astronomy and spectroscopy — the way we learn about the physics and chemistry of the remote universe — is strong enough that it will survive. And helping make spectroscopy in astronomy more quantitative is what we’ve done that will have some lasting significance.”