One of my favorite aspects of my job at Stanford is that I get to go on adult field trips on the regular. My first, last week, was probably one of the coolest I’ll get to attend…the Stanford Linear Accelerator Center, also known as SLAC National Accelerator Laboratory. SLAC was founded in 1962 and was, at the time, the longest linear particle accelerator in the United States. Today, it maintains a partnership with Stanford, and is fully funded by the Department of Energy. Scientists from all over the world apply to perform experiments there, and we, as Stanford employees, got a major peek behind the scenes at some of the amazing experimental science happening there!
Our tour started with an informational video that lasted about 15 minutes – 15 minutes that officially proved to me that, while I’m pretty smart by layman’s standards, I’m actually pretty freaking average. We all kind of looked shell-shocked at its conclusion – I’m pretty sure I only understood the very barest minimum of the topics that were barely touched on in the video. SLAC’s scientists/work have earned 4 Nobel prizes, and discovered 3 of the 6 known quarks today, among dozens of other major scientific advances and achievements. As we all exchanged totally incredulous “wow we’re idiots” looks, our SLAC guide, Enrique, loaded us onto our fancy coach bus for our first stop – an open segment of the Linear Accelerator!
What is a linear accelerator, you ask? Well, campers, in Lizzie terms, it’s essentially a racecourse for atoms, and when they hit the finish line, they smash into a target and create collisions or impacts that are study-able. SLAC is home to the longest linear accelerator in the world, although these days, only about 1/3 of the original accelerator is still in use. The accelerator cost $100 million to build in the 60s, and would cost well over $1billion today.
We were able to view a section of the accelerator designed for models/demonstrations – the actual accelerator emits too much radiation to make casual tourism possible. The accelerator itself is 30 meters below ground, insulated by a layer of loose rock and dirt to minimize seismic impact. Even a shift of a few millimeters can shut the accelerator down, which is costly and detrimental to those doing research. When one factors in the length of the accelerator – 2 miles – and the level of precision required, the results are staggering. SLAC is officially the longest, flattest single building in the world, and when it was constructed, they built a highway bridge for Highway 280 over it before Highway 280 even existed. The level of exactness is necessary in order to ensure that the accelerator can force electrons to hit speeds of 99.9999999% of the speed of light (that’s right, 7 percents!!).
Hitting that absurd speed requires an enormous amount of energy, of course. SLAC is on the Northern California power grid, and pays an energy bill monthly just like everyone else…theirs simply runs to the tune of tens of millions of dollars every few weeks. These guys are largely responsible: invented at Stanford in the 30s, the “klystron” microwave generator was named by the Stanford Classics department from Homer’s Odyssey. The term klys is ancient Greek for “waves crashing on the floor,” appropriate for a microwave, huh? These 2 miles of microwaves, however, have the collective power of 14.7 million American home microwaves. (I think my jaw actually dropped when Enrique shared this factoid.)
Nowadays, the majority of the accelerator has been decommissioned and is being redeveloped into an entirely new form of accelerator that is based on cryogenics…with the idea being to eventually to create a plasma Wakefield accelerator, which packs a lot more power into a lot smaller space. Once developed, these accelerators, per Enrique, could someday enable hospitals to zap single cancer cells rather than using radiation, to make particle colliders accessible to college science programs and smaller research facilities, and to revolutionize general approaches to particle research worldwide.
Our second stop was at SLAC’s Stanford Synchrotron Radiation Light Source (SSRL), the most powerful x-ray laser in the world. Most of the science behind SSRL went way over my head, but essentially the SLAC crew noticed that the accelerator was throwing off x-rays that were up to 10 million times more powerful than traditional hospital x-rays. Using undulators (magnets that force electrons to wiggle, for lack of a better term), those x-rays can be further amplified to 30 billion times more powerful.
One of the most exciting uses of the SSRL is as a high-powered camera, essentially, using x-ray diffraction images to see things that would otherwise be impossible to study. Think of it as the fastest aperture speed in the world…a femtosecond exposure. To put a femtosecond in perspective, a femtosecond is to a second as a second is to 32 million years. Again, jaw dropping. The lightning-fast speeds of the SSRL enable scientists to photograph infinitesimal reactions, like atoms actually splitting or photosynthesis in process. I wish I knew more science-y things and could better explain this - it was incredible to hear it firsthand from SLAC scientists, who actually know what they're talking about!
So what’s a SLAC tour guide to do for a big finish? Let a bunch of finance people play with a gamma ray, of course. SLAC is experimenting with using diamonds to further amplify x-rays, and as beam splitters to enable multiple beams from one laser. We got to witness this in action, from within a lead-lined room, and yours truly got to push the button. I literally fired a short-term molecular gamma ray laser, guys. If I knew what that actually meant, I’m sure I’d appreciate the experience even more – but as it was, it was pretty freaking crazy.
Having watched the insane data spikes after firing (sorry crew, no photos of the action allowed), we loaded the bus up again and headed back to our decidedly less mad-scientist desk jobs, visions of laserbeams dancing in our heads (or at least in mine, anyway!). As fascinating as our SLAC trip was, knowing we barely scratched the surface is the most fascinating aspect of all to me…looking forward to following SLAC’s research in campus and world news now that I’m basically an expert!