John Hill, NSLS-II Director, is shown here overlooking the Electron-Spectro-Microscopy Beamline on the NSLS-II Experimental Floor.

John Hill, NSLS-II Director, is shown here overlooking the Electron-Spectro-Microscopy Beamline on the NSLS-II Experimental Floor.

Photo courtesy of Roger Stoutenburgh, photographer for Brookhaven National Laboratory

This is a series of articles profiling the directors of the Department of Energy Office of Science user facilities. These are the scientists who lead a variety of research institutions that provide researchers with the most advanced tools of modern science including accelerators, colliders, supercomputers, light sources and neutron sources, as well as facilities for studying the nano world, the environment, and the atmosphere.

Meet the director of NSLS-II: John Hill

Most of us watched NASA rocket launches on TV – smoke billowed, flames exploded, and sound vibrated through your living room. Now imagine yourself at the launch site, standing outside the fence experiencing these sights and sounds and smells. "As a seven-year-old in Titusville, Florida, I watched two NASA missions launch which really excited me," recalls John Hill. "As I got older, my interest in science became an interest in physics, and I ultimately followed my passion into condensed matter physics."

Hill's passion has a new focus and he is now the director of the National Synchrotron Light Source II, or NSLS-II, a U.S. Department of Energy (DOE) Office of Science user facility located at the Brookhaven National Laboratory.

"Overall, being the director is fun - and stressful, exciting, exhausting, and challenging!" says Hill. "The thing I've enjoyed most is leading this wonderful team. It's very rewarding to work with such a large group, all with a common goal of building and operating a premiere user facility."

The director's background:

Hill first came to Brookhaven National Lab as a graduate student at MIT. He returned to the Brookhaven Department of Physics as a post-doc in 1992 and has been with the Lab ever since. He conducted research at the original National Synchrotron Light Source and also used synchrotrons around the country for research into magnetism and high-temperature superconductivity.

"In 2006, I joined NSLS-II while it was under construction, and led one part of the construction project for two and a half years," Hill says. He returned to his research in condensed matter physics but was called up once again to serve a role at Brookhaven's new synchrotron. "The Lab asked me to come back to NSLS-II as Director. The construction project was finished and I was excited at the chance to come back and be a part of the first year of operations of a world-leading facility. It was an easy decision! Before I became the director, the research I carried out was mostly in small teams of a few people. Now it's me and 400 people, all with a common goal."

What is a synchrotron? A synchrotron is a very large machine that produces powerful X-rays by accelerating electrons to almost the speed of light. The electrons travel within a vacuum pipe around and around in the synchrotron circle, while powerful magnets in sequence create electromagnetic fields to bend the stream of electrons. As the electrons change direction, they emit energy, producing very bright light. This intense light – mostly in the X-ray spectrum – is millions of times brighter than light from conventional sources.

The Facility: What is the NSLS-II?

NSLS-II started operations in 2015. It is a state-of-the-art, medium-energy synchrotron light source, [SEE "What is a synchrotron?"] which allows scientists to probe the fundamental properties of matter. It is 10,000 times brighter than the 30-year-old NSLS facility it replaced. From the moment it took first light, NSLS-II has been one of the newest and most advanced synchrotron facilities in the world.

The design and construction was a $912 million project that came in on time and under budget, winning the Secretary's Award of Excellence in DOE's 2015 Project Management awards. Some of the beamline equipment from the original NSLS made its way to NSLS-II, repurposed into cutting-edge beamlines.

"It's still in the early days," Hill says, "but even in our first year we were able to host 400 users. In a few years, the facility should be fully built up and we will be working with thousands of users each year."

Typical day:

Hill says his favorite part of the day is walking out on the floor to talk with his staff scientists and meet visiting user scientists. "It's a half mile around the ring," says Hill. "So I get to meet a lot of new users and check in with our staff."

For visitors needing a layman's level explanation of the facility, Hill describes NSLS-II as "a machine that produces very bright X-rays, a type of light that travels through materials and allows us to see what is happening inside those materials.

"We operate 24 hours a day. For some users, it will be possible to log in remotely and do research, but most of our visiting scientists come to Brookhaven and stay here on site while they take data. That means they're here at all hours. This place never really sleeps."

The DOE Office of Science runs five light sources. "The light sources in this country are important drivers of technologies," explains Hill. "We can see that by the fact that other countries are investing so much in light sources of their own. Twenty-five years ago, the U.S. had a significant lead in the field of synchrotron science. That lead has eroded. NSLS-II is putting us back at the front."

Typical experiments: Plant cells, battery death, and space dust

Visitors are often surprised that the facility is free to use. "As long as they publish their results, there is no charge for our scientific users," says Hill. "The only exception is if they want to keep their results proprietary." Three typical research experiments that are finding answers at the NSLS-II are:

How does a plant cell take up toxins? Users at NSLS-II ran an experiment to determine if tomato plants take up diesel fuel additives from the soil and how that process works. Using the Hard X-ray Nanoprobe beamline, researchers found that the plants do in fact take up cerium dioxide nanoparticles through their cell walls. The next step is to find out if these nanoparticles are harmful to human health.

Why won't a battery hold a charge after a certain period of time? We don't fully understand the lifetime of batteries but we do know it has something to do with the atomic scale interface between the battery's electrodes and the electrolyte. At NSLS-II, researchers can study this mechanism at a much higher resolution than ever before and determine what changes in the atomic structure or chemical structure lead to battery death.

Uptake of cerium dioxide nanoparticles through plant cell walls.

Uptake of cerium dioxide nanoparticles through plant cell walls.

Photo courtesy of R. Tappero (Brookhaven National Laboratory) and J. Unrine (University of Kentucky)

What is interstellar dust made of? NASA sent satellites into space to collect interstellar dust and bring it back for study. At NSLS-II, scientists determined the mineral content of these tiny particles, which gives us clues as to how our solar system was born.

Best advice for any succeeding directors at NSLS-II:

Hill says he's not going anywhere soon, but his advice to any future directors at NSLS-II is simple: "Be excited by the science. Keep the big picture in mind. Remember: You are serving the user community and the nation."


In Fiscal Year 2021, our 28 user facilities welcomed more than 33,000 researchers from academia, industry, and government research enterprises from all 50 states and the District of Columbia to perform scientific research. For details on the individual Office of Science User Facilities, please go to

Please go to Profiles of User Facilities Directors to read more articles on the directors for the Office of Science user facilities.

The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website.