Rays of Light

Events of July 21, 2013

"There it is!" I cried, over the sound of Kelly Clarkson's singing on the radio, pointing out my window at the white sign gleaming in the morning sun.

"BNL" read the large letters at the sign's left, next to the smaller black text explaining their meaning: "Brookhaven National Laboratory, Operated by Brookhaven Science Associates under contract with the United States Department of Energy".

"Yup, that's it, we're here." My father agreed, slowing his speed as we approached the security checkpoint ahead. Being over 16, we pulled out the required photo-identification and showed it to the guard, who smiled and wished us a nice visit.

We followed the signs reading "Summer Sundays" and "Visitor Parking" down the streets, as my father remarked on the size of the laboratory campus.

"Wow, people live here? And they have their own fire department?"

"Yeah, it's like a whole college campus here." I said, having visited a few years before with one of my High School science classes.

The parking lot was already pretty full by the time we arrived at Berkner Hall, an angular off-white building surrounded by decorative pine trees. As we passed through the entrance door, laboratory employees wearing blue "Summer Sundays" shirts handed us informational sheets. I recognized the inside of the hall from my High School visit and from a previous Summer Sundays event I had attended with my mother and brothers several years before that. We made our way to the information desk and spoke to the women working there. Yes, we were in the right place for today's tour of the National Synchrotron Light Source II, and one of the women working there, Nora Detweiler, offered to answer my questions and helped us board a school bus leaving for the site.

The NSLS II was only a few blocks away from Berkner Hall, and on the way there, we passed the Center for Functional Nanomaterials, where my science class had come on my previous visit. During the bus ride, Nora explained the purpose of the facilities we would see today--the NSLS II was a particle accelerator, a device that propelled subatomic particles like neutrons and electrons to nearly the speed of light. The most famous use of particle accelerators is as "atom-smashers", causing two beams of super-fast particles to smash into each other and break apart so that their even smaller components can be studied. The European Large Hadron Collider (LHC), the Tevatron operated outside Chicago by Fermilab until 2011, and Brookhaven's own Relativistic Heavy Ion Collider (RHIC, pronounced "Rick") are all examples of this kind of particle accelerator.

These particle accelerators are all large and very powerful, and when they accelerate those particle beams to such high speeds, a lot of energy in multiple wavelengths is produced. This energy is known as synchrotron radiation, after a name for a specific type of particle accelerator. The idea of a synchrotron light source is to put that extra energy to use for other experiments.

At first, scientists just attached their instruments directly to "standard" particle accelerators and used the "extra" energy they produced in the course of studying subatomic structure. But the NSLS II isn't attached to the RHIC--it's an independent particle accelerator that has its own beam of electrons to produce high-energy radiation.

So what exactly do scientists DO with that energy now that it's been produced? Usually, they use it in a manner similar to light in a microscope, aiming the radiation at their study material to determine the composition or structure of that material. Nora told us about a recent project where a Rembrandt painting had been x-rayed at the NSLS to determine the chemical make-up of the paints Rembrandt had used and discover mistakes or other details that had been painted over in the final artwork.

Later in the day, we heard from Cornell University medical researcher Maria Sirenko, who had been using the NSLS to study chemicals in the brains of mice with Alzheimer's Disease and determine if there was a correlation between the presence of a certain form of copper within the brain cells and the onset of Alzheimer's. Those were just two of the many scientific investigations that have been conducted at the original National Synchrotron Light Source since it opened in 1983.

However, as useful as the NSLS has been, the scientists at Brookhaven know that even more could be discovered with more powerful radiation--"brighter light" for their "microscopes". To meet this need and take advantage of technological advances since the 1980s, an even-more-powerful replacement is being constructed at Brookhaven--the National Synchrotron Light Source II. It was this new NSLS II building that was the focus of today's public event. The building itself was complete, as was most of the hardware related to the electron beam, and Nora explained that the beam would be turned on in a few months, with the facility fully operational sometime in 2015.

The building was immense and curved, a metallic gray with red and orange accents on the windowed sections that jutted out to the left and right, respectively. There were probably similarly color-coded parts of the building elsewhere around its circumference, although it was so large that those two were all we could see from where we were.

Inside, the NSLS II building felt like something between a warehouse, an airplane hangar, and a factory. The floor was concrete, and the high ceilings overhead were metal, with various supports holding pipes and ventilation systems away from the ground, to make sure they didn't produce any vibrations that could interfere with the electron beam or the other sensitive instruments that would be used. The columns supporting the roof were each anchored in their own block of concrete, to further reduce vibrations. (This really is serious given the sensitivity of the instruments they use--when my class had visited the Center for Functional Nanomaterials, a scientist had told us that the best time for doing experiments was 2 AM, because "That's when there are the fewest planes flying overhead and the fewest cars going by on the Long Island Expressway.")

The electron beam itself was enclosed within white walls, but at set intervals there were clusters of machinery jutting out onto the floor area where we were, blocked off by a yellow safety chain. Nora explained that these were beamlines--stations around the accelerator ring where synchrotron radiation of a given wavelength (x-ray or ultraviolet light, for example) was funneled off the electron beam for use in experiments.

Nora had to return to Berkner Hall, but she turned us over to Chelsea Whyte, a science writer affiliated with the laboratory's public relations office, who she said could answer the rest of our questions. Chelsea introduced us to two scientists working in the NSLS II facility who had just finished a TV interview for the local news and said they would be glad to speak with me.

The first scientist I spoke to was Wah-Keat Lee, a bearded physicist previously employed at Argonne National Laboratory in Illinois who had come to Brookhaven to design an x-ray beamline for microscopic imaging. At Argonne, Dr. Lee had used x-ray imaging to study the circulatory and digestive systems of insects. While standard x-rays work well for studying the structure of the human body, x-ray microscopes are needed to examine the smaller bodies of insects. While Dr. Lee's work had focused on insects, he explained that the completed x-ray beamline would, like any microscope, be a useful tool in many different fields--x-ray imaging of the insides of building materials and batteries to reveal weaknesses could suggest future improvements.

"We build the facility not just for our own use, but for other people to use." He explained, gesturing excitedly. He said he enjoyed his job because he was able "to learn new things and find out things other people don't know about."

Juergen Thieme also worked with x-rays, and his beamline project was to combine high-resolution magnification of tiny details with spectroscopy--the process of finding the chemical composition of the objects being studied. "We combine chemistry and physics." And just how small are the details they'll be able to see? "We can achieve some hundred nanometers. One thousandth of a millimeter is a micron, one thousandth of a micron is a nanometer. ... We are really looking at very, very small things."

Before coming to Brookhaven, Dr. Theime had taught for thirty years at the University of Göttingen in Germany. He and his students used similar x-ray imaging for environmental research, examining soil and water samples and atmospheric aerosols to measure the amounts and effects of chemicals introduced into the land, water, and air by human activity.

To select a specific bandwidth for imaging a material, Dr. Theime's group used "silicon monochromators"--layers of silicon crystals that slightly deflected the x-ray beam to alter its angle and energy intensity. Examples of the monochromator set-up and the related x-ray detectors were on his group's table to examine.

After speaking with the scientists, I made my way around the open part of the floor, examining the different displays that had been set up related to different aspects of the NSLS. At a table explaining the use of crystals in x-ray deflection, I built a tetragonal crystal out of gumdrops and toothpicks--it looked a little dumpy because the toothpicks I picked weren't all the same length. Another display illustrated the effects of changing air pressure on different materials--balloons and marshmallows inside small vacuum chambers swelled as the air pressure was reduced and the gasses within them expanded, then shrunk as the pressure returned to normal, the gas being compressed again. (See also: Styrofoam cups on submarines and the size of stratosphere balloons at launch vs. altitude.)

Because the energies being dealt with in Brookhaven's synchrotron light sources are so intense, the equipment in contact with the beams can get pretty hot. That's why the machinery must contain cooling systems, many of which use liquid nitrogen, the subject of another display. The scientists at the table demonstrated how quickly a dunk in liquid nitrogen will freeze common objects like a banana (it becomes hard enough to hammer nails with), a flower (it shatters like glass upon hitting a table), a rubber ball (it feels and bounces like a ping-pong ball) and a modern zinc penny (when hit with a hammer, it shatters into pieces, but a pre-1983 copper penny just bends). Thus suitably impressed, my inner six-year old asked the presenters what would happen if liquid nitrogen was thrown on lava. They said they'd never tried it, but they imagined the liquid nitrogen would probably be quickly turned to gas by the heat, although the lava right at the point of contact might solidify. Liquid nitrogen is as far below room temperature as a pizza oven is above it, but lava can be more than three times hotter than that, so heat would definitely win out over cold in the end. (Can any chemists or volcanologists offer additional information on this subject?)

After the demonstration tables, my father and I joined a group of other visitors on a tour of the accelerator ring itself, led by engineer Lawrence Hoff. It was a long, white corridor with black pipes and insulated electrical wires running along the ceiling. The wires plugged into a long sequence of large magnets of varying color elevated on a metal support that came up from the floor ran continuously along the whole corridor until it curved out of sight, with the only gap in the magnets being the one we had come in through. The magnets reached from about waist height to eye level, and a steel tube ran through their centers--it was within this tube that the electron beam itself would run through the full 800 meters of the accelerator ring.

Mr. Hoff explained that the colors of the magnets indicated their type and function--the blue dipole and red corrector magnets would bend the electron beam, keeping it running in a circle, while the red quadrupole and orange sextupole magnets would focus it. While the NSLS II's magnets are far more powerful than those that stick to refrigerators, those at the RHIC are even stronger.

After seeing the NSLS II, my father and I crossed the street to see its older brother, which will remain operational until the NSLS II is ready to take its place. The beam at this older accelerator is nearly always on, weekdays or weekends, holidays or normal days, except for the December holidays. It was on the Sunday afternoon we visited, prompting our guide to point to the sign warning individuals with medical implants not to enter the laboratory area when the beam was in use. (Remember those magnets?) Fortunately, no one in our tour group did, so we proceeded inside. The laboratory floor was a maze of beamlines, catwalks, computer stations, cubicles, and equipment I couldn't begin to guess at the purpose of. It looked complicated, but everything was organized--the chairs at each computer station were even marked with the number of the station they were assigned to so they weren't used elsewhere. So this was what a fully-operational synchrotron light source looked like! On the walls of the hallways we walked through between beamline stations, posters described different research projects that had been carried out there--the most interesting to me was an analysis of material from Comet Wild 2 brought back to Earth by the Stardust probe.

After seeing both accelerators, my father and I caught another bus back to Berkner Hall for lunch in the cafeteria. We had missed most of the presentations being held for guests in the auditoriums there, but we still were able to play with a Van de Graaff generator (my hair was in a good standing-on-end mood, sometimes it's too curly for anything to happen) and check out some display cases about the history of Brookhaven Lab. After World War II, the government established national laboratories across the country for research into atomic physics and other important strategic fields, and many scientists had expressed the desire to have one in the northeast for proximity to the region's major cities and universities. The site eventually chosen was an army base in Suffolk Country called Camp Upton. In 1947, Camp Upton was closed, and Brookhaven Lab was established.

Finally, it was time to head home. We drove out of the Berkner parking lot, back down the streets past the houses and fire station, past the security checkpoint and the sign, and back out onto the Long Island Expressway, merging with the thousands of other cars on the road. It was hard to believe that such amazing things had been only a few miles off this familiar stretch of highway. I wondered how many of the other people driving by knew what was back there, behind those trees?