Blueprints of the atomic bombs developed at Los Alamos during World War II are on sale today in the town's bookstore.

No tour of American science would be complete without a stop in Los Alamos, New Mexico. From 1943 to 1945, the U.S. government sequestered many of the world’s leading physicists on this high desert plateau under the auspices of the Army Corps of Engineers Manhattan Engineer District with the mission to build an atomic bomb before the end of World War II. Until they accomplished their goal, hundreds of scientists, along with their families and a large administrative and technical staff, disappeared from their former lives, leaving behind only an address for a P.O. Box in Santa Fe, New Mexico. (You can check out all their staff badge photos here.)

While most of Los Alamos’s new inhabitants left soon after the use of their invention ended World War II, some stayed. The town of Los Alamos soon became a place with real addresses, accessible roads, great mountain biking, and some of the best public schools in the state of New Mexico. But it still carries the weight of its history, with blueprints of Little Boy and Fat Man (the atomic bombs dropped on Hiroshima and Nagasaki) for sale in the town bookstore, and classified weapons research ongoing at the lab. We went there not really sure what we would be allowed to see or how we would feel about it. But while the history was problematic, the current (unclassified) science we saw exhibited many of the same traits we observed at other labs: creativity, ingenuity, and a lot of foil.

Upon observing the success of the Trinity "gadget" on July 16th, 1945, Oppenheimer visibly relaxed years of built-up tension then quoted a line from the Bhagavad Gita: "I am become death, the destroyer of worlds." Success it was: just 0.025 seconds after detonation, the explosion was several hundred meters across. As physicist Kenneth Brainbridge remarked: "Now we are all sons of bitches."

The first few fractions of a second of the Trinity shot on July 16th, 1945 in Alamogordo, New Mexico – and thus the first few fractions of a second of the atomic age, since Trinity was the first detonation of a nuclear device on the surface of the earth.

J. Robert Oppenheimer, who was named scientific director of the Manhattan Project in 1942, advocated Los Alamos for the site of the secret atomic city in part because he remembered the impressive and largely inaccessible landscape of northern New Mexico from the time he spent there as a teenager. And despite being literally and figuratively on the map today, the town of Los Alamos is still not very accessible. It’s housed on a series of mesas high in the New Mexican dessert northwest of Santa Fe – and while we weren’t as utterly blown away by the view as Richard Feynman (who had never ventured much outside the borders of New York City), we had to admit that it was one of the most impressive landscapes of our trip.

Our first stop in Los Alamos was the communications office, which is kept separate from the lab to make the flow of visitors easier to regulate and control. For obvious reasons, there are more rules and restrictions to follow when visiting Los Alamos than when visiting the non-weapons national labs. Even though we would only be seeing unclassified physics research, Nick’s photos had to be carefully composed to omit aspects of the experiments we visited, and James Rickman from the communications office had to escort us everywhere.

Our tour started with visits to the people responsible for our invitation to the lab: Melynda Brooks and Mike Leitch, two collaborators on the PHENIX detector at Brookhaven. Melynda showed us the muon tracking chambers she was working on.

Parts of a new muon detector slated for RHIC's PHENIX experiment

Parts of a new muon detector slated for RHIC's PHENIX experiment

As I mentioned in our accelerator technology post, particle detectors work by picking up the signals left behind by high-speed particle collisions. When particles smash into each other going at almost the speed of light, the energy released in the collision is converted into a shower of new particles. As time passes, those new particles decay into other particles, and so on and so on. This process usually happens so fast that by the time the detector picks up a signal a fraction of a second after a collision, the particles have already decayed several times. When physicists decide what particles they are interested in studying in a particular experiment, they must calculate their likely decay patterns and scour the data for those expected signatures.

Melynda explained, “There are just particular decay channels where the particles that are produced are muons. By taking like pairs of muons and reconstructing what they must have originated from we can calculate what the mass was, we can select particular particles. Here we work a lot on a particle called the J-psi.”

The muon tracking chambers Melynda and Mike’s team is working on will be able to tell exactly where the original particle decayed into muons, thereby allowing them to further differentiate the particles that result from a collision in the PHENIX detector and improve their samples of each type. Melynda gave us the example of distinguishing between the J-psi and the open charm samples produced at PHENIX: “The J-psi decays basically instantaneously….The open charms tend to decay a few microns away from the primary vertex,” she explained. This increased precision will allow the PHENIX team to construct better hypotheses about the quark-gluon plasma it is studying.

The PHENIX collaboration is somewhat of an anomaly at Los Alamos: not only is it unclassified, but it has nothing at all to do with weapons science or the military. As James explained, “There’s some straight science for science’s sake that comes out of Los Alamos, but most everything that we have here is a product in one way or another of the laboratory’s nuclear weapons mission. And so a lot of the really excellent science that comes out of there is a result of kind of leveraging that mission science and using it and applying it to problems of national importance, especially in the physics realm.” We saw that kind of applied “mission science” during our next stop: muon radiography.

Muon radiography at Los Alamos is a homeland security project designed to help find what our tour guide Andrew Green called “special nuclear materials” – from chunks of lead or uranium to suitcase bombs – that are being smuggled into the U.S. After the last decade, the words “homeland security project” usually make me think of human rights violations, not cosmic rays, but cosmic rays were exactly what were on display here. The team had just finished building a detector that used the muons passing through the atmosphere as cosmic rays to scan vehicles for hidden nuclear materials. It was en route to the border crossing at San Diego by the time we visited, but we still got a good sense of the project.

A small-scale version of the muon radiography detectors that will be used to protect the United States from smuggled nuclear materials

The real detectors, as this empty harness attests, will be large enough to drive a truck through

In 1946, as the world was struggling to understand the titanic changes caused by the development of the bomb, a senator asked Oppenheimer what tools existed to prevent a small group from smuggling a bomb in a crate into America and using it to completely destroy a major city. “A screwdriver,” Oppenheimer replied, to open every crate entering the country. Today, if anything, the risks of living in the nuclear age are even more terrifying than they were in the 1940s: as this New Yorker article about the black market trade of uranium refinement machinery demonstrates, the equipment and know-how required to build a bomb have been in the hands of the wrong people for decades.

Los Alamos’s muon radiography detector is essentially Oppenheimer’s screwdriver, without the screwdriver. Using techniques to measure how much cosmic ray muons scatter as they travel through the vehicle in the detector would allow border patrol agents to quickly catch any high density materials that may be hidden inside. The detector has a top and a bottom but no sides and is big enough that a truck or a shipping container could be driven into it. Best of all, it is completely passive – cosmic rays pass through us regardless of whether there’s a detector in place to observe them – and easily fast enough to be used at a border crossing.

“For the same reason that they [muons] are very useful for doing relativistic heavy ion physics, they are useful for this too,” Andrew said. “Muons are able to go through lots of material. And going through most detectors, they are just minimum ionizing. You see a track, and you’re able to reconstruct that track pretty much fully to high precision.” He continued, “To see a smoking gun signal takes only about a minute.”

With detectors installed at ports and commercial border crossings, we stand a real chance of catching potentially fissile materials before they make it into the United States. And as someone who has spent a good chunk of her life waiting to cross the Tijuana/San Diego border, the idea of a precise scan that would target dangerous materials and could actually speed up the line seems like a dream. “[Drivers] always have to stop [at the border] anyway to deal with customs,” Andrew said. “While they’re stopping, they get scanned, and it’s free – except for these million dollar detectors.”

We spent most of the summer exploring basic science, so this new realm of applied physics seemed a little strange. For starters, it was actually profitable. Some of the funding for the muon radiography detectors came from a company called Decision Sciences Corporation, which stood to make money from selling the technology. (At the time of this writing, it had an image of the muon radiography detector on its home page.) “We always like it when people can make money off of our ideas,” Andrew told us.

I was also enchanted by the creativity behind the project. Harnessing cosmic rays to easily, quickly, and precisely scan vehicles in border lines for smuggled nuclear materials just isn’t an idea that occurs to everyone. All in all, the project seemed like the perfect model of applied science: using particle physics detector technology to build a machine that solves a real world problem. (You can read Los Alamos’s press release about the muon radiography project here.)

Our next stop at the lab took us back to the world of basic science with the group searching for the electric dipole moment of the neutron, called the nEDM. An electric dipole moment is an expression of the separation between the positive and negative electrical charges within the same system. While it is hypothesized that the neutron experiences such a separation, the nEDM has never been experimentally observed. In part, physicists are interested in finding the nEDM because it would violate a law of classical physics called time-reversal symmetry, which posits that time cannot move backwards.

Yet strange as it may seem, time-reversal symmetry has actually already been disproven: according to quantum mechanics the only reason that a glass you’ve dropped on the floor doesn’t reassemble itself and jump back into your hand is that such an event is extremely improbable, not actually impossible. So why are physicists still looking for the nEDM? For one thing, finding the nEDM could be a step towards experimentally proving supersymmetry, a popular Beyond the Standard Model theory. No matter what happens, the nEDM is probably part of the next theoretical step: as our guide Martin Cooper told us, “You almost can’t invent a theory beyond the standard model which gets rid of the neutron EDM….Supersymmetry is just the popular one.” Additionally, identifying a new source of time-reversal symmetry breaking may help explain why there is so much more matter than antimatter in our universe, one of the great mysteries of physics.

An exposed portion of the cryogenic search for the neutron's electric dipole moment

An exposed portion of the cryogenic search for the neutron's electric dipole moment

The Los Alamos team we visited was working on the R&D for an experiment that will look for the nEDM at a fraction of a degree above absolute zero, using cryogenic equipment to measure the difference in how ultra-cold neutrons and helium-3 precess around a magnetic field. (Read Martin’s detailed explanation of his team’s work here. ) At time of our tour, the team’s main focus was figuring out how to work at such cold temperatures. Martin explained, “Most of the difficulties of this experiment are understanding how to build low temperature apparatus and the physics of very dilute mixtures of helium-3 and helium-4 in this region from 300 to 450 millikelvin….The neutron part of it only really comes at the end.”

Like much of the physics world, the search for the neutron's electic dipole moment rests on the ready availability of large quantities of foil

Indeed, the cryogenic nEDM work at Los Alamos is rivaled only by the nation's synchrotron light sources in the zealous application of foil to physics experiments

As Martin put it, “You’re here when physicists are in a frenzy to make something work, so things are in pieces a lot”

A beautiful example of an experimental sense of humor

While the final version of the experiment will be housed at the Spallation Neutron Source at Oak Ridge, the techniques that are being developed are so sensitive that the scientists must figure out all the ins and outs before building the final machine. “It’s such a big piece of apparatus that is takes like a month to cool down or a month to warm up, so the problem is that you can’t work on it very well. Every time you decide to make one change you spend $100,000 and two or three months of your time doing it. So we want to test every piece before it goes there,” Martin said. While experimental particle physics is often focused on proving big ideas (in this case, supersymmetry), the bread and butter of its operations are these very precise baby steps.

Somewhat surprisingly, we’d spent nearly two hours at Los Alamos at this point and hadn’t seen any projects related to nuclear weapons. Of course we weren’t going to be invited to see classified weapons research, but “stockpile stewardship”—making sure that the U.S.’s supply of nuclear weapons is understood and maintained—is a big part of the lab’s mission these days, and we got a good look at it during our next and last stop, proton radiography.

Los Alamos's proton radiography imager is the epitome of a building-sized physics machine

Proton radiography is a technique used to image objects and events on very small scales. In some senses it is similar to what we saw at the National Synchrotron Light Source, but instead of using x-rays, the team at Los Alamos uses focused beams of protons to image microscopic events. Also, the events they are looking at are incredibly powerful explosions.

A panorama of the proton radiography beamline

The proton radiography imager's beamline, with the imaging portion towards the top of the picture

Like virtually all physics experiments, proton radiography relies on big magnets. And like virtually all physics experimenters, Los Alamos's proton radiography team must be resourceful to get the job done: "We've recycled what became obsolete equipment. For example, all our focusing magnets and things were scrounged from previous experimental work."

In order to gather as much data as possible, the imaging system in Los Alamos's proton radiography setup uses six small mirrors in different orientations to direct image information into six separate cameras

A closer view of the proton radiography machine's imaging system

The main goal of proton radiography is to test weapons in the U.S.’s nuclear stockpile on a miniature scale. Our very enthusiastic guide Dale Tupa told us, “We here at proton radiography can test things that are components for nuclear weapons or other weapons system without actually setting off a bomb. We have been able to answer very important questions on the reliability of weapons that sit the stockpile without having them actually set one off.”

Since most of the weapons in the nuclear stockpile are decades old at this point, and the U.S. conducted its last nuclear test in 1992, there are serious questions about how they have changed over time. Will they still work? To use the stockpile as a deterrent, which is the stated policy of the United States, the answer must be a definitive yes. (To put this in perspective, the Air Force maintains 98.5% readiness of its minuteman missiles at all times). Have the weapons grown more or less sensitive over the years? Will it take more or less force to detonate them? How predictable will their yields be under these changing circumstances? In order to establish protocols for handling these weapons without setting one off by accident, we need to know. Dale and her team are able to answer these questions and more by setting off controlled explosions inside a chamber in the lab and taking detailed pictures of those explosions in progress.

To take one example, in the below photo (taken from the DOE Office of Nuclear Physics explanation of proton radiography), a disk of tin reacts to high explosives: “First, the detonation’s spherical shock wave bulges the disk (about 2 inches in diameter and 0.25 inch thick). Then, when the compressive shock wave reflects from the disk’s upper surface, the shock becomes tensile, dislodging and levitating the spall layer (the “flying saucer”). The shock wave’s high pressure and temperature also melt the tin (light gray region connecting the flying saucer and bulge).”

Stills from a movie of an explosion made by Dale's team

Dale works on the optical diagnostics for the shots, and she was clearly delighted and amazed that her job involved taking pictures of super cool explosions. While showing us some of the videos that her team as her produced, she exclaimed, “And they pay me!” It reminded me of my Physics for Poets professor Hal Evan’s explanation for why he became a physicist: “I have always been interested in smashing things into each other. This narrowed my career options to High Energy Physics or Demolition Derby. Not having good driving skills, I ended up doing research.”

Dale's team uses a 21st-century version of the Michelson and Morley beam-splitting experiment that disproved theories about the luminiferous aether and paved the way for Einstein's work into relativity

Not just recycled physics equipment gets put to new use in the labs

Dale's team named a multi-part portion of their laser run after the seven dwarves

Proton radiography showcased an interesting middle ground between basic science and military research. They employ some fundamentals of experimental particle physics to do truly cutting edge research into areas like shock waves and high pressure environments. But the work is contingent on the military’s needs. Whether political concerns can or should be separated from the discussion of such research, no matter how cool it may be, is a question I still can’t answer. But I did learn that Los Alamos’s “mission science” is a lot more creative and varied than I expected it to be. The lab may never escape its relationship to the Manhattan Project and the military, but that’s certainly not stopping the scientists there from doing research they love.

Los Alamos is also developing human teleportation devices, but since the work is "classified" we couldn't get much information about this device...

While planning our trip, Lizzie and I realized that we would have an awkward amount of extra time between our visits to the Superconducting Super Collider and Los Alamos. Though the drive from east Texas to New Mexico is formidable enough to require a night’s stay along the way, it has such high speed limits and so few turns that the miles tick by more quickly than just about anywhere else in the country. But since the July 4th weekend meant that we had to be at Los Alamos by the 2nd – unless they’re in the middle of a particularly intensive run, physicists get the same holiday weekends as the rest of us – there was only about a half-day to spare.

This wasn’t enough time to accommodate our original idea of camping at White Sands and driving by the Trinity Test Site (which is closed to the public all but two days a year anyway). But it turned out to be just the right amount of time to visit the accurately if unimaginatively named Very Large Array (VLA), located about 50 miles west of Socorro, New Mexico.

The heart of the Very Large Array

A wider view of the heart of the VLA. As the view extends outward, the scale starts to become apparent.

Click through to view an enormous panorama of the VLA. Even though the Array was not at its most outspread position, this enormous image still does not capture the whole thing.

Nestled on a vast, mountain-ringed, 7000-foot plateau in the central New Mexican desert, the VLA is safe from the interfering radio waves of just about anything that doesn’t come from space. Though it is comprised of 27 separate dishes, the observatory operates as a unified whole: by interferometrically combining the data from each dish, the array can simulate the results of a single radio telescope up to 22 miles wide.

One of the 230-ton, 28-meter diameter VLA radio telescopes. Note the railroad cars for scale.

As you can see from the railroad cars in the above picture, the telescopes themselves are absolutely enormous. Even more astoundingly, they move: placed on sets of railroad tracks, the dishes can be carefully shifted en masse to create one of four different total areas that correspond to different angular resolutions, each used to observe differently-sized chunks of the sky. The system works so efficiently that the gargantuan task of moving the dishes can be undertaken frequently, about once every four months. This ease of movement allows the observation of a tremendous range of celestial objects and variables, which, along with the fact that the observatory can operate during the daytime, helps to make the VLA the most-used radio telescope in the world.

Sunrays shine through the clouds onto the VLA, illuminating both the telescopes and the train tracks used to move them around the observatory.

This transportability also makes it easy to maintain the telescopes, as they can be rotated in and out of service as maintenance is required. Thus, although the functional array makes use of 27 dishes, the VLA has a total of 28. One dish is always undergoing routine servicing in the Antenna Assembly Building.

The rotating 28th antenna of the array, undergoing routine maintenance in the Antenna Assembly Building.

At its most outspread, the VLA’s footprint is larger than the Washington, DC metropolitan area (see map below). Because of this tremendous size and the flat terrain, you can see the observatory from miles away. Yet the plains that house it are themselves so vast that the installation is dwarfed by its backdrop. Indeed, it takes so long to walk among the telescopes that the observatory management has posted lightning warnings for visitors who wish to take the self-guided walking tour, and even in the midst of the array the furthest dishes seem ludicrously distant.

The VLA is so large that its arms could engulf the Washington, DC metropolitan area at its widest stance.

The VLA is enormous, but the plateau that houses it is larger still. Even in the midst of the telescopes, the most distant dishes seem tiny against the backdrop of plains and distant hills.

As such, the Array exists the very edge of human scale: too large for people to traverse it on foot, too small to compete with the surrounding landscape. More vividly than any other single site we visited this summer, this paradoxical size illustrates one of the unifying themes of the trip as a whole: Big Science tends to use increasingly enormous and complex machines to access parts of reality that would otherwise be inaccessible. Walter Benjamin touches on this phenomenon during his discussion of filmmaking in The Work of Art in the Age of Mechanical Reproduction:

[I]n the studio the mechanical equipment has penetrated so deeply into reality that its pure aspect freed from the foreign substance of equipment is the result of a special procedure, namely, the shooting by the specially adjusted camera and the mounting of the shot together with other similar ones. The equipment-free aspect of reality here has become the height of artifice; the sight of immediate reality has become an orchid in the land of technology…

The characteristics of the film lie not only in the manner in which man presents himself to mechanical equipment but also in the manner in which, by means of this apparatus, man can represent his environment… This circumstance derives its chief importance from its tendency to promote the mutual penetration of art and science. Actually, of a screened behavior item which is neatly brought out in a certain situation, like a muscle of a body, it is difficult to say which is more fascinating, its artistic value or its value for science.

In just the way in which artists frequently disguise the artifice of their methods of production, scientists work hard to eliminate as completely as possible the influence of their equipment on their results – indeed, the manner in which scientists carefully account for apparatus-induced error is a substantial part of what makes science science. But Benjamin implies something more: there is a real tendency for larger and more complex apparatus to cut more broadly and deeply into reality. So long as care is taken to hide the lights and microphones, camera and crew, the complex artifice of filmmaking can reveal more than unadulterated reality would; so long as care is taken to account for the influence of an inhumanly complex apparatus, Big Science can reveal ever more about the fundamentals of our world.

It is no surprise, in this light, that the machines that allow these groundbreaking studies of nature are often so astoundingly and increasingly large that they rank among the largest construction projects ever undertaken by humanity. (The VLA’s size requirements are at least partially related to the large size of the phenomena it measures; at many of the other laboratories we visited, the enormity of the machines was required to measure the very small.)

But as Fermilab’s Dr. Peoples sadly notes, this also means that particle physics will eventually build a “last machine” on the energy frontier. At some point on the path that physics is on – to be determined more by cost and other practical concerns than by nature – new discoveries in this realm of physics will truly move past the human scale and into the natural scale, beyond our ability to follow. Thus, the Faustian nature of Big Science: enormous rewards for the money, but at what often seems to be an ultimately unsustainable cost and pace.

Though tremendously expensive, the VLA was completed a year ahead of schedule and under budget, and has been used 362 days a year for the last thirty years – a marvelous success by any measure. On the other side of the spectrum, the failure of the Superconducting Super Collider and the difficulties that the Large Hadron Collider ran into during its first start up are signs that particle physics may already be stretching Benjamin’s bigger-is-better mode of exploration to the breaking point. We can only hope that this approach is made obsolete by the time that frontier hardens before us, that the need for larger and more expensive machines is replaced by more powerfully efficient methods. As Lizzie noted in our accelerator development post, development of the International Linear Collider is being channeled through more quickly realizable intermediate experiments like Project X, while research into more efficient accelerator methods continues around the country.

In this respect, the VLA embodies another important principle: rather than building one 22-mile dish that would have cost about as much as it would to colonize Mars, it made use of scientific principles to simulate such a dish with nearly equal scientific results. Although such shortcuts aren’t always possible, the more cleverly that science makes use of its own discoveries, the more feasible it becomes to carry out new work.

-Nick

A row of VLA radio telescopes.

A row of VLA radio telescopes.

Eighty years later, accelerators range from the relatively low-energy machines used to treat cancer in single hospital rooms to the Large Hadron Collider, which crosses an international border and gets us to energy levels last seen fractions of second after the Big Bang. Up until now bigger has meant better in terms of accelerators, but as we look forward to the proposed International Linear Collider and beyond, many physicists are investigating how to fit the biggest of Big Science onto a tabletop.

New accelerator technology at Fermilab

Of course, very fast moving particles are not an anomaly in our world, even without particle accelerators. More than 50 million neutrinos traveling at almost the speed of light pass through your body every second without causing a second glance, while cosmic rays racing through the atmosphere were among the first particles we learned to “see” in cloud chambers and, later, bubble chambers. What is special about a particle accelerator is that you know exactly what you’ve put into it, and you know exactly how fast those particles are going to go once you start the machine.

A particle accelerator is also the first step in building a particle collider, in which extremely fast moving subatomic particles are slammed into each other. In a beautiful practical application of Einstein’s famous e=mc², the energy released by that collision is transformed into a shower of other subatomic particles, which are then picked up by sophisticated detectors. The content of that particle shower is what physicists use to study the basic building blocks of the universe and the forces that hold them together.

A subatomic particle in a cyclotron travels through an alternating current, which pushes and pulls the charged particle to ever-greater speeds. Lawrence read about this novel way to accelerate particles in a paper by the Norwegian physicist Rolf Winderöe and was immediately intrigued, although a bit discouraged by the fact that in order to generate enough alternating current to accelerate particles to the required speeds, he would need several meters of charged cylinders lined up in a row—too long, he thought, for a laboratory. His breakthrough was realizing that if he applied a perpendicular magnetic field to the particles in the accelerator, they would travel in a spiral path, thereby saving space and cutting down on the amount of equipment needed to build his visionary machine. Indeed, the first cyclotron, which was completed in 1931, was so compact it could be held in the palm of your hand.

Ernest Lawrence's first cyclotron

As technology and funding improved, Lawrence built increasingly large cyclotrons, eventually reaching 184 inches in diameter. His initial worry about a two- or three-meter linear accelerator being too long to fit in any laboratory would, in just a few decades, come to seem laughable: SLAC’s linear accelerator, completed in 1966, is two miles long, and the proposed ILC is ten times that. Rather than worrying about how the accelerator would fit in a room, labs started being built to house increasingly large accelerators (case in point: Fermilab, home to the Tevatron and its four-mile ring).

But after the disastrously expensive development and subsequent cancellation of the Superconducting Super Collider in 1993, building a new lab every time you wanted a more powerful accelerator became an impossibility. The SSC’s replacement/successor, the LHC, fits neatly into the tunnel that previously housed CERN’s Large Electron-Positron Collider (LEP). As physicists look ahead to building the International Linear Collider, the main stumbling block is not that they don’t know how to build the next big machine. It’s that if they use current technologies, the ILC would be 20 miles long and could cost as much as $25 billion to construct—figures that might once again be physically and financially too big for any laboratory, or even any one country.

ILC development suffered some setbacks at the National Labs during the particularly lean years leading up to the stimulus package, and the international physics community can’t afford to get too excited about a machine they aren’t sure they will get to build. But as the LHC starts to produce results, the ILC could be indispensable for understanding the new science coming out of CERN. Aware that this could well be the next major step in high energy physics, Fermilab is pushing ahead with ILC development. Kurt Riesselmann from the Public Affairs Office took us on a tour of a building that was used for fixed-target experiments in the early days of lab and has recently been converted to house accelerator R&D.

Accelerator R&D takes over the New Muon Lab at Fermilab. Eventually the building will have to be expanded to make room for more components

The Fermilab team is working on building the type of superconducting cavities that would be used to build the ILC. Kurt called these cyromodules “bagel structures” and showed us a few of them in various stages of construction. “The challenge for the ILC, why it’s so expensive, is that you need something like 10,000 of the bagel structures, each of them about a meter long,” he explained. Furthermore, “At the moment it’s like putting together an airplane to make one of these. Then you need 1000 or 2000 of them.” If the construction process for each bagel structure could be simplified and sped up to under a month, the ILC’s anticipated price tag would fall dramatically.

Kurt Riesselmann explains the ILC's "bagel structures" to Lizzie

Liquid helium and liquid nitrogen would both be pumped in to different parts of the cyromodules to cool the equipment

But the cryomodules wouldn’t just be used for the ILC—they are also a major component of Project X, the high-intensity accelerator Fermilab is building to aid in its mission to scale up its neutrino physics program. After Project X’s initial acceleration phase, the next half-mile will use exactly these cryomodules. As exciting as Project X is by itself, it can also be seen as a huge step forward in ILC development. Kurt laid out a convincing argument for the lab’s foresight: “Once you’ve built Project X, not only have you built a machine that is really ready for neutrino physics and other experiments we haven’t talked about, but you can also say that we have built 1/40 of the ILC. And we can tell it costs this much, we’ve learned this, we can do it faster. At that time the answer might still be the ILC is too expensive, but at that time we also will know what the LHC has produced, so we will know if it’s actually worthwhile doing the ILC.”

A nearly complete ILC/Project X cryomodule

Closeup of a future ILC/Project X cryomodule

While Fermilab is directing its ILC development efforts towards perfecting current technology, other labs are taking an even longer view and are working on developing completely new accelerator technology in hopes of making future machines smaller and cheaper. At Argonne National Lab, postdoctoral fellow Sergei Antipov showed us around the building where he experiments with building wakefield accelerators.

While most of today’s accelerators use electro-magnetic fields to accelerate and control a single beam of particles, wakefield accelerators use the “wake” left behind by one beam of electrons to accelerate a second. As you may imagine, this process is all but impossible to describe without a few helpful surfing metaphors, which Sergei was happy to provide: “You take the first cloud of electrons and pass it through some structure. It leaves this wake behind it, just like a boat. You take a smaller electron bunch and pass it behind it, and sort of like a surfer on those waves, the smaller bunch will get accelerated by the wake.”

The experimental wakefield accelerator at Argonne

The upside is that wakefield accelerators are much more efficient than other accelerators, since the first beam, which can be relatively low energy and quite large, does most of the hard work of getting the second beam up to very high energies. This makes it relatively easy to increase the acceleration gradient of the machine, which means the accelerator itself can be shorter—a major goal for scientists working towards the ILC and beyond. The appeal of smaller accelerators reaches far beyond the high energy physics community, since they would be easier to install everywhere from hospitals (to treat cancer) to food processing plants (to irradiate produce).

The downside of wakefield accelerators is that we don’t yet know how to build structures that can withstand the huge energies the second beam can reach. Sergei is experimenting with many different kinds of ceramic structures and even working with some material scientists to determine how to ensure that the accelerator itself won’t break apart when the second beam travels through it.

Another important part of constructing a working wakefield accelerator is making sure you can get a big enough bunch of electrons into the first beam. As Sergei would say, a huge boat leaves a big wake, helping the surfer reach higher energies. He creates this “boat,” or the first beam of electrons, by hitting a cathode with a laser and capturing the electrons that are released. He needs to get as many electrons into the machine as he can in order to create the highest energy wake possible, so he is also doing painstaking experiments to create the most efficient cathode. This part of his work, part of which involves evaporating cesium telluride so that the molecules with drift over and stick to the surface of the cathode, seemed a little unreal even to Sergei, who said, “It’s still alchemy, we just have better equipment.”

Aluminum foil makes another appearance, this time on Argonne's experimental wakefield accelerator

Accelerator magnets held together by a clamp

Another way to create a wake for electrons to ride on is by using laser pulses. At Lawrence Berkeley National Lab, we visited the Laser Optics and Accelerator Systems Integrated Studies group, or L’OASIS, which is working on developing the technology needed for laser wakefield acceleration. Fittingly, Berkeley Lab was founded by Ernest Lawrence as his Radiation Laboratory, or Rad Lab for short, in order to house his increasingly large cyclotrons (it was designated a National Laboratory and renamed after Lawrence’s death in 1959).

Before going inside the rooms that house the L’OASIS experiments, we had to put on the most intense clean suits of our trip.

Lizzie with our L'OASIS tour guide Nick Matlis in their clean suits

Once inside, L’OASIS scientist Nicholas Matlis gave us a tour of the lab’s unique two-story laser system. In order to create a high enough quality beam for laser wakefield acceleration to work, it needs to be amplified and compressed many times along the way. At L’OASIS, the beam travels through two amplifying systems: Godzilla and T-Rex. (There is also a third and much smaller laser system named Chihuahua.) They look like a combination of a Rube Goldberg machine and the best maze a lab rat could ever hope to run.

Part of L'OASIS's laser run.

More L'OASIS laser run.

The junction where the the L'OASIS beam travels between floors of the building. As Nicholas told us, "It seems kind of cool to have lasers traveling between floors, but the truth is that it’s a bit of a pain."

The L'OASIS team keeps a photo on the outside of this case, since the equipment inside is so sensitive that it can only rarely be exposed

Equipment so sensitive it must be sealed in a thick metal box most of the time

L'OASIS equipment

More L'OASIS equipment

Even more L'OASIS equipment

Once the laser beam has been amplified to its fullest, it is shot through a plume of gas to ionize it, creating a plasma and leaving a wake in the form of a hugely powerful electron field. A beam of electrons can then follow the laser into the plasma and be accelerated by that electric field to energies that conventional metal structure could never support. (For a more detailed description of this process, check out this article by Paul Preuss, our wonderful guide at Berkeley Lab.)

L’OASIS made the cover of Nature in 2004 by proving that they could make useful electron beams through laser wakefield accelerator. But there are still many problems to be solved. As Nicholas told us, “At the moment there’s still a lot of physicists who sort of condescend and look down on this technology as not being real. It was only in 2004 that first demonstrated that you can make electrons of interesting quality with these lasers. But now they’re still at an energy that’s much lower than conventional accelerators and still not as high quality. We have yet to prove to the rest of the accelerator community to take us completely seriously and these experiments were designed to do that.”

One of the biggest problems the L’OASIS group is confronting is staging. Just like a car has to shift gears in order to accelerate from 0 to 60 mph, particles must go through several different “stages” of an accelerator before they reach their top speed. A new laser beam must be used for each stage of a laser wakefield accelerator, which creates the challenge of getting the timing just right so that the new laser hits the gas and makes a plasma tunnel just an instant before the existing high energy electron beam is ready to travel to through it. The previous laser beam must also be deflected very quickly in a way that won’t interfere with the electron beam riding on its wake. L’OASIS scientists are currently experimenting with the laser-reflecting properties of small water jets and – you guessed it – aluminum foil.

If the L’OASIS group is able to show staging, it could open the door for the development of a full-fledged accelerator that is a lot smaller than today’s conventional accelerators – think the size of a football stadium rather than the size of the city of Dallas.

It’s hard to believe that high energy physicists are already looking beyond the still hypothetical ILC, especially since we haven’t even seen any new results from the LHC. But as Fermilab’s Kurt Riesselmann said, “For the last 70 to 80 years we’ve developed accelerator technology, pushed it forward, and now it doesn’t make sense to all of a sudden say, OK, let’s drop it. We probably don’t know some of the applications that we still will discover for accelerators, so pushing the limits and making it more powerful and more precise some day will pay off.”

It has been suggested that the LHC might be the most powerful accelerator we ever build, especially if it doesn’t turn up the exciting results that physicists are hoping for. But each time a more powerful accelerator is built, not only does it offer a window onto previously unseen aspects of our universe, but it pushes the limits of human collaboration and international cooperation to new heights. Harry Weerts, director of the Argonne team working on the ILC, summed up the grand appeal of looking one step ahead to the next great machine when he said, “It sets a goal for everybody, that we as a human race can do something like this.”

-Lizzie

For more on the science behind many different types of accelerators, check out Nick’s post about Argonne National Lab.

This history is written all over the lab, even as it is already carving itself a place in the 21st century:

The beautiful but abandoned Building 330, which housed the 1950s-era Chicago Pile 5 reactor. Argonne was also the second home of Enrico Fermi's Chicago Pile 1, which was moved to the lab from the University of Chicago in 1943 and renamed Chicago Pile 2.

In an amazing contrast, old warehouses lodge some of the world's most cutting-edge research.

Argonne's obviously much newer Advanced Photon Source, which produces the brightest x-rays in the western hemisphere.

Like the PHENIX and STAR experiments at Brookhaven, Illinois’s Argonne and Fermilab share a faux-bitter rivalry. Argonne’s history gives it a unique place in American physics, and it is considerably larger than its neighbor in the Chicago suburbs; but particularly after the Tevatron was completed at Fermilab in the 1980s, the younger, smaller lab has received the lion’s share of media attention. That a proposed expansion of Argonne had to be rejected in the 1960s in favor of the entirely new particle physics lab just a few miles down the road naturally fueled the fire.

But as with most combative siblings, the rivalry is little more than the face of a close working relationship. Argonne’s proximity to the nation’s (and until just recently, the world’s) largest particle collider has made it a perfect site for the development of new accelerator techniques and the construction of accelerator parts. (More on this later: accelerator development is so multilaboratory in nature that Lizzie and I will be doing a separate post on the subject.) As early work on the International Linear Collider (ILC) progresses, Argonne and Fermilab work with the same components and problems, each responsible for their own pieces in the intricate process.

As a preview of our accelerator technologies post, here's a photo of some wakefield acceleration work being carried out at Argonne.

Rather than using radio frequency cavities to accelerate particles, wakefield acceleration uses the wake in a plasma caused by the injection of laser pulses or bunches of electrons: particles get caught up in the wake, much like surfers on ocean waves, and accelerate until their speed matches that of the wake.

When Lizzie and I visited in July, detector and accelerator designer Tom Fields, who has worked off-and-on at Argonne since the 1960s (and who helped start the MINOS/Soudan neutrino experiment), had just compiled a complete list of the accelerator projects housed at Argonne since the lab’s inception. Over the last forty years, these fourteen projects not only advanced fundamental physics and technology, but laid the groundwork for the user-based approach to research that the National Labs nearly all employ to some extent. With the help of others at the lab, this list (along with explanations) has now been made available on the Argonne Accelerator Institute’s website.

As Fields’s list also makes clear, Argonne isn’t defined by a single large-scale accelerator, as Fermilab was by the Tevatron. Indeed, as a multidisciplinary lab, it isn’t even solely focused on high energy physics. The Advanced Photon Source is the brightest source of x-rays in the western hemisphere, and like most contemporary synchrotrons it is used for virtually every field of science. And after weathering all the shifts in Atomic Energy Commission and Department of Energy mission over the last 60 years, the lab has played host to the development and improvement of just about every source of energy on the market. Four generations of nuclear reactor, as well as the reactors used by submarines and aircraft carriers; the windmills we saw around the country on our trip; even more obscure concepts like solar ponds. All were developed or substantively improved at Argonne.

On a more personal note, one of the more distinctive side-effects of visiting eleven physics-related sites in a short span of time is that you start seeing physics machines everywhere: from construction equipment on the highways to the oil rigs of Texas and the wind farms of California, suddenly every strange piece of machinery looked like it belonged in an underground lab. Argonne helped to make this actually the case.

A wind farm just east of San Francisco – and an example of how Argonne's research spreads far beyond the borders of the lab.

Physicists benefit from this arrangement as much as anyone, as there are tangible rewards for locating a small particle physics division in this larger, multidisciplinary environment. As Harry Weerts, the director of the Argonne team working on the International Linear Collider, remarked to us: nine out of ten solutions to a specialized problem will come from the discipline that needs it; but that one time where expertise from another discipline turns out to be relevant can make all the difference in a major project’s success.

One of Argonne’s current undertakings is the perfection of advanced materials science techniques for use in the construction of more efficient radio frequency cavities for accelerators. To make it happen, scientists from one part of the lab simply had to walk to another building and talk to their colleagues.

Likewise, construction of the country’s first non-reactor neutron source – the predecessor of the larger but similarly designed Spallation Neutron Source we visited at Oak Ridge – was instigated by a solid-state researcher from the University of Michigan who pitched his idea to an enthusiastic Argonne scientist. There may be good reason to concentrate particle physics research in a dedicated facility like Fermilab; but with successes like these, there will always be a place for multidisciplinary labs like Argonne as well.

_______________

Along with teams at Brookhaven, SLAC and Berkeley, Argonne physicists contribute to the ATLAS experiment at the Large Hadron Collider (Fermilab works by itself on a CMS collaboration). But there hasn’t been a major high energy research accelerator at Argonne since the Zero Gradient Synchrotron (ZGS), which operated from 1963 to 1979 at 12 GeV. With a fifteen-year run as one of the first large-scale accelerators in the world, the ZGS holds a hallowed space in the history of particle physics.

Conceived in an Atomic Energy Commission panic over the realization that Russia had built an accelerator of similar power and technology – what if they pointed it at us?! – the ZGS differed from more recent accelerators in that it used “weak focusing” to keep its accelerated particles together in a tight beam. This means that it relied on a single, uniform, strong magnetic field that directed its particles in a circle.

An illustration of weak focusing. (image taken from Brookhaven National Laboratory)

Weak focusing ultimately lost out to alternate-gradient or “strong” focusing, developed at CERN’s Proton Synchrotron (which has been re-purposed as a booster accelerator for the LHC) and Brookhaven’s Alternate Gradient Synchrotron (which now feeds into RHIC), since strong focusing allows for much tighter beam coherence.

An illustration of the principle behind alternate-gradient or "strong" focusing, which is a bedrock of contemporary particle accelerator technology. If a beam of light is focused first inward and then outward and then inward again using lenses, it will remain a fairly tight beam. Accelerated charged particles can be manipulated in roughly the same way, though physicists use strong magnetic fields instead of lenses. (image taken from Berkeley National Laboratory)

But weak-focusing technology had some unintended benefits too: alternating-gradient machines like the AGS couldn’t accelerate polarized particles, so the ZGS proved essential for explorations of polarity, and useful for broader areas of research where a particle’s polarity needed to be preserved. This helped to set a precedent, particularly at Argonne but at other labs as well, of allowing users from a range of fields to use an accelerator for research that had little to do with its original purpose, once that original purpose was fulfilled.

Since we didn’t get a chance to see anything but the outside of the ZGS, I dug up some historical images on Argonne’s website and in the University of Chicago’s Archival Photographic Files online database. (We didn’t actually tour the ZGS, so I’m guessing about some of what follows – it makes some sense to me after seeing a half-dozen accelerators/colliders over the summer, but if anyone reading this knows better, then please correct me. Also, click on any of the images to visit their original site for more information).

Just like the enormous accelerators of today’s physics, the ZGS used a series of acceleration techniques (some old, some new) to bring its particles up to speed. The protons began their journey in a 750-kv Cockcroft-Walton generator, one of the oldest particle accelerator designs.

This 750-kv Cockcroft-Walton generator was used as the first stage in accelerating ZGS protons. (Archival Photographic Files, apf digital item number apf2-00486, Special Collections Research Center, University of Chicago Library)

From there, they were accelerated to 50 MeV by a 110-foot linear accelerator:

The 110-foot, 50 MeV linear accelerator used to feed accelerated protons into ZGS ring. (Archival Photographic Files, apf digital item number apf2-00488, Special Collections Research Center, University of Chicago Library)

A view down the Zero Gradient Synchrotron's 110-foot linear accelerator. (Archival Photographic Files, apf digital item number apf2-00487, Special Collections Research Center, University of Chicago Library)

After this second acceleration, the particles were dumped into the main synchrotron ring, which relied on weak focusing to keep the beam moving in a circle as a single 20,000-volt radio-frequency cavity kicked the particles into higher energies each time they made a lap.

One eighth of the partially assembled ZGS ring magnet. Towards the back, in the middle of the image, you can see where the proton beam would enter the ring from the linear accelerator. (Archival Photographic Files, apf digital item number apf2-00493, Special Collections Research Center, University of Chicago Library)

The ZGS ring magnet as viewed from the inside. (Archival Photographic Files, apf digital item number apf2-00494, Special Collections Research Center, University of Chicago Library)

Finally fully accelerated, the protons would smash into their targets, and the resulting spray of particles would make its way into a detector. In order to observe only what was relevant, though, uninteresting pieces had to be separated out of the mess by electrostatic separators placed just ahead of the detectors.

An electrostatic separator at ZGS, used to pull out unwanted particles before observation. (Archival Photographic Files, apf digital item number apf2-00492, Special Collections Research Center, University of Chicago Library)

In the middle days of particle acceleration, detectors were generally bubble chambers – hydrogen-filled containers that responded when a charged particle went through them. Physicists could watch (and photograph) the tracks that the particles made, and by applying a magnetic field they could characterize the different types of particles by the amount that their tracks curved towards or away from the magnet.

(Fun fact about bubble chambers: contrary to popular anecdote, 1960 Nobel laureate Donald Glaser was not inspired to invent them by a glass of beer. But Glaser did put beer into some early prototypes, with little success.)

The enormous coil and magnet yoke that would encase a 30-inch hydrogen bubble chamber. (Archival Photographic Files, apf digital item number apf2-00491, Special Collections Research Center, University of Chicago Library)

The world's first neutrino observation in a hydrogen bubble chamber was found Nov. 13, 1970, on this historical photograph from the Zero Gradient Synchrotron's 12-foot bubble chamber. The invisible neutrino strikes a proton where three particle tracks originate (right). The neutrino turns into a mu-meson, the long center track. The short track is the proton. The third track is a pi-meson created by the collision. (image and caption taken from Argonne National Laboratory)

In all, the ZGS would have looked something like this:

A schematic of the Zero Gradient Synchrotron. (Archival Photographic Files, apf digital item number apf2-00485, Special Collections Research Center, University of Chicago Library)

Argonne's ZGS, viewed from above in 1963. (Archival Photographic Files, apf digital item number apf2-00470, Special Collections Research Center, University of Chicago Library)

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Argonne also happened to be the only opportunity Lizzie and I had to speak with a theoretical physicist. Everywhere else we visited last summer, experimental physicists were exploring the properties of particles predicted by the standard model. But for Ed Berger, the Standard Model is an unsatisfying piece of theory that doesn’t explain the universe so much as just fit our data – and only if we stay within fairly limited assumptions. Even more compelling ideas like supersymmetry and extra dimensions are merely promising “toys” to use in the process of developing a theory that he’s sure will run deeper and stronger than the Standard Model.

With this perspective, the LHC’s new higher-energy data isn’t exciting because it will verify what we know, or even because it will expand it. Rather, it’s exciting because of the possibility that it will contain something that hasn’t been theorized about at all. A wildly new, unexplainable discovery would put new bounds on what theorists can postulate, pushing their explanations of the universe into truly new territory. Right now, as Berger puts it, the theorists need the experimentalists to rescue them, to “get us out of our dark desert.” Until they have more data, the theorists “have too many unconstrained possibilities to help them.”

If the LHC does produce a deep mystery, we might see a theoretical revolution like the one that occurred in the early 1970s with the development of quantum chromodynamics (which explains strong nuclear interactions) and electroweak unification (which unifies electrodynamics with the weak nuclear force). Since almost all of today’s particle physics cam be characterized as a continual refinement of this revolution – finding predicted particles one-by-one, making better measurements – the theoretical possibilities that the LHC represents strike at the very heart of physics: who knows what we’ll find out there, and what it will lead us to understand?

-Nick

-Nick

The site of the abandoned Superconducting Super Collider.

The Superconducting Super Collider is rarely discussed anymore, but its ghost has haunted high energy physics for the last 16 years. Slated to begin operations in 1999 in Waxahachie, Texas, the SSC would have been nearly three times as powerful as the Large Hadron Collider at CERN. Had it been completed, we would probably not be waiting with bated breath for the hints of the Higgs Boson from the LHC: the Higgs and a slew of other physics would most likely be among the recent accomplishments of jubilant experimental physicists.

Alas, after ten years of planning and $2 billion in construction costs, Congress pulled the plug on the project in 1993. Today, several of the buildings and 14 miles of the planned 54-mile-long tunnel sit abandoned in the Texas desert — the tunnel intentionally filled with water in order to preserve it. Despite talk of turning the site into a mushroom farm or a data center, the site hasn’t been used for much other than a filming location for Universal Soldier: The Return, which even we aren’t curious enough to watch.

But wondering about what’s actually there, Nick and I decided to search for its remains on our way from Chicago to Los Alamos.

Lizzie comes face to face with the greatest unrealized dream in American particle physics.

Following the advice of Dr. Roy Schwitters, a professor at the University of Texas, Austin and the former director of the SSC, we started at the Ellis County courthouse, which is almost literally a gingerbread house in the town square:

The Ellis County Courthouse in Waxahachie, TX.

Because we still weren’t sure where to go from there, we poked around Waxahachie and discovered the Ellis County Museum. It seemed to be an organized version of the town’s attic, full of 1920s hats, WWII paraphernalia, and century-old maps of the area. The curator, Mr. Shannon Simpson, directed me to a website where he’s collected some information about the SSC and pulled out a big picture of the tunnel taken during construction:

A photo of the partially completed SSC tunnel at the Ellis County Museum.

We also flipped through some impact reports commissioned by the DOE about historic sites in the area, which contained some pretty great maps of the SSC ring. As you can see, it would have been truly enormous. While the Tevatron and RHIC surround small wildlife preserves, the SSC would have completely surrounded the city of Waxahachie:

A map from a DOE-commissioned survey of the area surrounding the planned SSC site.

In fact, it wouldn’t have been much smaller than Dallas, which lies 40 minutes or so to the north:

The SSC's planned footprint would have been only slightly smaller than the city of Dallas, entirely surrounding Waxahachie. (image taken from Wikipedia)

I thought the museum would be the best surprise of the day, but our adventure was just getting started. We found the SSC buildings in the middle of nowhere — literally a vast blank on the car’s GPS — and simply drove up one of the driveways. It was shockingly hot. As we wandered around the side of a long gray building, we stuck to the shade as much as we could.

As with the other labs we visited, the Superconducting Super Collider would have had Government Vehicle parking areas. Now the rusting signs are one of the only outward indications that this could have been a DOE facility.

I squeezed behind a huge box of circuit breakers and found an uncovered hole. When I dropped a rock in it, it made a splash. You know what that means: it was an entrance to the now water-filled tunnel! Despite the fact that it was 102 degrees under the East Texas sun, I got chills.

A water-filled hole by the SSC, which presumably led down into the collider tunnel itself.

I was surprised how few signs of trespassing there were, considering they are weird, huge buildings in the middle of nowhere. No graffiti, hardly any litter. But a key piece of vandalism allowed us access to what appeared to be the main building in the complex. One of the many windows encompassing the building’s staircase had been punched out and covered with plywood, making it easy to pry our way in. The first floor hallways were pitch dark, which posed a particular problem because we were both wearing sunglasses.

Exploring the SSC had its challenges and creepy moments, which were exacerbated by the fact that the electricity was turned off and we were wearing sunglasses. It was hard to escape the feeling that, if there are any secret alien hideouts, this would be one of them.

To escape the darkeness, we headed up to the top floor where we found ourselves in a huge empty office space (luckily with lots of windows). Though the architecture was a particularly ugly brand of early-90s dressed-up-industrial, it was easy to imagine how the offices and conference rooms could have been filled with lively physics discussions.

SSC offices overlooking the bucolic Texas countryside.

In one of the creepiest moments of the exploration, we realized with a start that we were standing on footprints made in the dust by previous visitors. Apparently the SSC still attracts the occasional guest - though not so many that the dust gets brushed away.

On the other side of the building we found a hangar-sized space with one of physics’ beloved cranes installed near the ceiling. Presumably this was where parts of the accelerator and/or the detectors were assembled (or would have been assembled).

An abandoned SSC assembly building.

Unfortunately, as we entered the presumed assembly hall, we started hearing some ominous clanking sounds. Worried that we had either set off an alarm or disturbed the aliens living in the building, we hightailed it outside.

Even more ominously, the light posts in the parking lot were squealing and shaking violently for no reason. It sounded so weird, especially after such a surreal experience, that we had to record it:

The above recording is what it sounded like to stand on this spot.

So just as we suspected, there is a ghost lab in East Texas, complete with half empty frappuchino bottles on the counters and haunting footprints on the carpets. But why? Why was the lab abandoned? Why was so much of it built at all? What happened to the Superconducting Super Collider?

The story has never been told in its entirety. This is partly because, in the words of former Fermilab director and self-identified “funeral director of the SSC” Dr. John Peoples, “If something goes this bad, everyone has a hand in it.” When the SSC is discussed at all these days, the narrative is usually reduced to the idea that the project was so over-budget and behind schedule that Congress had no choice but to kill it. Indeed, the initial estimate for building the SSC was $5.9 billion and by the time it was cancelled, it was expected to cost at least $11 billion. But while pulling the plug on the SSC may have seemed like a smart fiscal decision to federal lawmakers in 1993, such a move would have been considered wildly irresponsible in previous decades. The reason: the Cold War.

By the time the atomic bombing of Japan ended World War II, high energy physics was already enjoying a privileged place when it came to government funded science. Just think about the Manhattan Project: the U.S. spent billions in the middle of a war to build a secret town in the mountains of New Mexico and stock it with thousands of the world’s best scientists. During the arms race in the decades that followed, investment in high energy physics research was thought to be essential to the nation’s survival. As Dr. Peoples eloquently put it, “The Cold War was really, really important for the whole idea of, I would say, Big Science that can only be justified in terms of what it does to advance knowledge.”

So it’s no surprise that when Robert Wilson asked for money to build his weird dream lab, Congress gave him 90 million dollars (about a billion dollars in today’s money) and essentially said, “If you can really spend that much money, come back later.” After relaying that anecdote, Dr. Peoples added, “That just doesn’t happen anymore.” By 1993, basic research in high energy physics was no longer viewed as a weapon — which, according to the U.S.’s guns over butter attitude, meant that it was no longer a priority.

Due to the annual nature of the U.S. appropriations system, Congress had the ability to cut off funding to the SSC when Big Science and high energy physics fell from grace. CERN, on the other hand, receives a set percentage of each member state’s GDP every year. The European lab’s eminently stable budget is certainly a reason why the LHC was completed while the SSC was scrapped as soon as funds and interest waned. But the LHC was also built using existing infrastructure: namely, the tunnel originally used for the Large Electron-Positron Collider (LEP). The SSC was to built on what Dr. Peoples called “a green field site,” as close to the middle of nowhere as you can get, in large part because Texas politicians wanted a National Laboratory for their state.

A lack of public relations was another factor in cancellation. As Dr. Peoples reminded us, “The DOE emerged from a secret organization, the Atomic Energy Commission. It wasn’t their bag to go around telling people what great things they were doing.” After years of conducting secret nuclear weapons tests, the DOE wasn’t eager to share its work with the public — even when that work depended on the public’s support.

Due to DOE’s lack of communication, Dr. Peoples said, the SSC and high energy physics “became too esoteric as a science for the public to relate to.” NASA’s space program, for example, romanticized a permanent foothold in space with the International Space Station (which was approved around the same time the SSC was canceled) and produced beautiful pictures taken by the Hubble Space Telescope. But “the SSC could not make that connection to people.”

As the LHC gets up and running and plans are laid for the next generation of accelerators, how do we keep the SSC debacle from repeating itself? First and foremost, Dr. Peoples said, any future project must be international and have a guaranteed source of funding. As science historian Dan Kevles puts it in his article about the SSC, “no nation can write a blank check for science.” Kevles even reports that the U.S. seriously considered joining CERN after the SSC’s cancellation, a stunning vote of no confidence for our country’s ability to live up to our Big Science legacy, but also a possible note of stark realism.

In recent years, the high energy physics community has taken the SSC’s difficult lessons to heart. It’s hard to even conceive of a project that isn’t international these days, and communication with the outside world is going strong (as our own project should suggest). The budgets of the National Laboratories continue to be an issue, but the stimulus package provided them with a much needed boost after a few dangerously lean years. Plans for the future tend to stick with what is working now; the continued operation of the Tevatron is receiving much more money and attention than the possible plans for the next planned collider, the ILC.

But despite the shock to particle physics caused by the SSC catastrophe, there is still one comment that Dr. Peoples made that I haven’t heard anyone else dare to say: “There will be a last machine. We may be very close.” Eventually, the energy required to boost particles past the next meaningful physical threshold will be beyond humanity’s financial power to produce.

As Dr. Tom Fields of Argonne National Laboratory told us with a note of sadness, “I’m not sure that American high energy physics will ever recover the position that it should have had, had that project been completed… But it’s definitely in the past, the whole thing. And it’s hard enough for CERN to get their machine going.”

Sadly yet fittingly, someone has taken the trouble to dump an old couch in the SSC's courtyard.

(Check out another suburban spelunker’s SSC adventure here.  He seems to have explored the site in 2003 and was lucky enough to get to see it with the lights on. Wired recently published some SSC pictures as well, as part of an article about the foiled plans to turn the site into a data storage center.)

The MINOS Far Detector, buried 2,341 feet beneath the earth in the Soudan Mine in northern Minnesota. A mural by Joseph Giannetti about the power of science is painted on the right wall.

After visiting the point of origin of the MINOS neutrinos on our Fermilab tour at the beginning of the trip, it seemed a fitting conclusion to stop by their destination as my own road neared its end. So with Lizzie in Mexico, I made the Summer’s last science-related stop at the Soudan Mine with my friend Sam on our way back across the country.

As discussed in our previous post, the MINOS experiment uses a beam of neutrinos called NuMI (Neutrinos at the Main Injector) produced by decaying protons from Fermilab’s Main Injector. These neutrinos travel 450 miles through the earth to the 2341-foot deep Soudan Mine in northeast Minnesota (and beyond, of course), where physicists can isolate the Far Detector from just about any interference. Despite the fact that the detector is shaped like an enormous stop sign, only a tiny number of neutrinos obey the symbolic request: of all the trillions of neutrinos produced by NuMI, the Far Detector sees only about one a day.

Courtesy of Fermilab.

A rich iron mine between 1884 and 1962, Soudan remains the oldest and deepest mine in the Minnesota. Now it’s a state park where visitors can experience the underground world of a miner and see the physics laboratory that has sprung up since the mine’s closing. The primary difficulty with visiting is that the mine is remote even by mid-American standards: only around 30,000 people live within 50 miles of the site, and even the physicists mostly run the detector remotely. Our route did take us through both of Bob Dylan’s hometowns (Duluth and Hibbing), though, so we got to drive down Highway 61 listening to Highway 61 Revisited.

In a sense, there isn’t anything more to the MINOS Far Detector than what Lizzie and I saw of the Near Detector at Fermilab: it’s an enormous horizontal pile of hundreds of octagonal metal plates. That said, there are nearly twice as many of them – 486 vs. 282 — and each one is considerably larger, so the Far Detector has a more pronounced way of looming over you.

The MINOS Far Detector, which required as much metal as a battleship to construct.

A side view of the Far Detector. If uncovered, it would look much the same as the Near Detector (though it is significantly larger).

Above all, the fact that the detector is housed in a mine causes complications. Everything required to build the 6,000-ton detector, including the enormous metal plates themselves, had to fit inside the existing elevator shaft: digging a huge 350-foot hole for a science experiment is one thing; digging a huge 2341-foot hole (and keeping it stable) is something else entirely. The Soudan detector’s plates are therefore made up of sections, each of which was lowered separately before being combined in the detector hall itself and moved into position by one of the physics world’s ubiquitous ceiling cranes. Amazingly, the job came in ahead of schedule and under budget, in part because local layoffs provided an eager and expert workforce.

The mine’s isolation from cosmic rays and temperature variations also makes it ideal for the Cryogenic Dark Matter Search II (CDMS II), the second experiment currently operating out of Soudan. We couldn’t get in to see the detectors so pictures are scant, but the lab focuses on the search for Weakly Interacting Massive Particles (WIMPs), which are even more difficult to detect than neutrinos and may play a significant role in Dark Matter. Since its detectors reach their highest sensitivity just a fraction of a degree above absolute zero, CDMS II is also home to the coldest place in the known universe.

This sign greets visitors upon reaching level 27 of the mine. Needless to say, the tour is not for the claustrophobic.

The carts used on the underground mine tour, which is different from the high energy physics tour. Sadly, I had an 8-hour drive ahead of me and couldn't take advantage of the opportunity.

Originally used to let the "cage" elevator operators know that men (not metal) would be in the lift, today it chauvinistically dates the mine's construction.

The metal structure supporting the double-decker "cage" elevator that descends into the mine

Which brings us to the bats. They were everywhere, hanging upside down from walls and pieces of equipment, flying around our heads from the moment we stepped out of the elevator. I’d hazard a guess that there aren’t any other major experiments that let bats fly through their beamline, but that’s part of what makes mine-based neutrino work unique. If it turns out that bats have neutrino-damping properties no one is yet aware of, MINOS is taking a major hit. (Somehow, I don’t get the sense that anyone is worried.)

A bat detected on Soudan's wall.

A bat flying by the door to the underground laboratory.

The bats also bring to mind an extracurricular visit of Lizzie’s and mine to the Museum of Jurassic Technology in Los Angeles. It is impossible to succinctly describe the museum to someone who has not been there, though founder and curator David Wilson (of no known relation to Fermilab’s Robert Wilson) does as good a job as anyone: “We’re a small natural history museum with an emphasis on curiosities and technological innovation… We’re definitely interested in presenting phenomena that other natural history museums are unwilling to present.” (quote taken from Mr. Wilson’s Cabinet of Wonder, Lawrence Weschler’s wonderful book about the museum). Which is to say, half of it, improbable or not, is absolutely real; the other half of it is utter nonsense, at least as far as the rest of reality is concerned. But it’s all presented with a deadly seriousness that both mocks and pays a deep homage to the objective, authoritarian tone of most museums.

My favorite exhibit was about a fictional species of bat that emits x-rays instead of sound waves, granting it the ability to fly through solid objects. As with the rest of the museum, there was an inordinately detailed account of its extraordinary discovery and scientific meaning. Supposedly frustrated by all attempts to capture the creature — how, after all, does one study something that can fly through any container? — a team of scientists led by the estimable but entirely fictional Donald R. Griffith (notably not the real bat zoologist Donald R. Griffin) constructed a detector in the South American rainforest out of five 20-foot-tall spokes of eight-inch-thick lead, each 200 feet long. After more than two months of waiting they finally managed to catch one bat, which they identified using a specially designed portable X-Ray viewer. A large slab of lead sits behind glass at the Museum — but naturally without an x-ray viewer with which one could actually see the bat that it claims to encase.

The notion is ludicrous, of course. Weschler describes how one skeptic calculated that “Dr. Griffith” would require on the order of 190,000 assistants to transport 9,154,000 pounds of lead into the rainforest to build the bat detector.

Obviously impossible. And yet as I stared at a battleship’s worth of steel, which had been carefully lodged 2,341 feet below the surface of northern Minnesota in pieces and assembled into 486 horizontally stacked sheets, all to detect one or two of the relevant particles a day, with bats fluttering all around it…

Real science has a way of being even more ludicrous than the wildest of imaginings. Which, presumably, is exactly David Wilson’s paradoxical point.

-Nick

The enormous hole in the MINOS building that leads down to the NuMI neutrino beamline and MINOS

In all the fuss about how amazing the LHC is going to be, we often forget that there are things it won’t be able to do. One of the most glaring holes in the LHC’s research program is how little work it plans to do on neutrino physics, one of the most exciting and promising fields in the quest to go beyond the Standard Model. Neutrinos are elementary particles that are nearly massless and have no charge. They rarely interact with other particles, so you need to make a lot of them to have the faintest hope of detecting just a few in experiments. In other words, you don’t need very high energy protons to produce neutrinos, but you do need a lot of lower energy ones.

It wouldn’t really make sense to devote much of the LHC’s particle yield to experiments that don’t need anything approaching its high energies, especially during the early years of the experiment. So Fermilab, somewhat presciently, is stepping in to fill the gap. As our tour guide and gracious host Kurt Riesselmann told us, “Fermilab is moving from the energy frontier to the intensity frontier” — meaning that instead of producing a small number of the highest possible energy particles, the lab is figuring out how to make as many lower energy particles as possible.

A particularly exciting area of neutrino physics is the question of neutrino oscillations. Neutrinos come in three “flavors:” the electron neutrino, the muon neutrino, and the tau neutrino. The discovery that a single neutrino can transform into all three types — and back again — was the first clue that neutrinos have mass, and that the masses of each flavor must be different. That was a surprise, to say the least, because the Standard Model predicts that neutrinos are massless. In our search to discover gaps in the Standard Model, the questions of neutrino mass and oscillations have taken center stage.

We saw got a closer look at two neutrino experiments during our visit: MINOS and MiniBooNE. The Main Injector Neutrino Oscillation Search (MINOS) studies neutrino oscillation by sending a stream of the particles through the earth to a detector 450 miles away in an old iron mine in Soudan, Minnesota. Since neutrinos have no charge and barely any mass, they have no problem passing through the earth’s crust — so, unlike many current physics experiments, MINOS didn’t involve building a tunnel. It did, however, involve digging a 350-ft. hole.

Lizzie and Kurt by the enormous hole.

The experiment uses a coarse detector, since its main purpose is to simply count neutrinos, rather than identify their exact positions. “When we count how many neutrinos we see here [in Fermilab’s near detector], we’re able to project how many you expect to see up in Minnesota,” explained MINOS physicist Catherine James. “Do you see see that many? The answer is no.” The disappearing muon neutrinos are thought to have oscillated to become electron and tau neutrinos. (NOvA, a future experiment in a mine even further north along the beam than Soudan, will attempt to observe some of the missing muon neutrinos reappearing as electron neutrinos.)

The neutrino beamline layout (image courtesy of Fermilab).

Whereas the Tevatron experiments, CDF and DZero, have to wade through piles of useless data to find the interesting stuff, MINOS and all other neutrino experiments must struggle to find any data at all. A proton pulse from Fermilab’s Main Injector accelerator hits an underground target and produces a blast of billions of muon neutrinos every two seconds. But as Catherine told us, “We see maybe two, three, or four of those neutrinos in our tons of tons of steel. Our far detector [in the Soudan Mine] sees one beam neutrino a day.” Those numbers help put Fermilab’s idea of the intensity frontier in perspective. The more protons MINOS starts with, the more neutrinos they will be able to detect at every step of the experiment.

Lizzie, Kurt, Cat and Rachel standing in front of the MINOS near detector, deep under Fermilab.

Even 350 feet underground, we could not escape the physics world

Because neutrinos are so impossibly difficult to detect, physicists layer hundreds of detector plates in the path of the beamline to increase the chances of an event.

The detector at the Soudan Mine is almost eight times deeper in the earth than the detector at Fermilab. It is also considerably bigger, since the beam spreads out over the course of its trip and the larger surface area allows more data to be collected.

Signage by the MINOS near detector. If the elevator fails during an emergency, one can take the long trek up the (slightly irradiated) slope seen in the below picture.

The tunnel leading from the MINOS near detector to the neutrino beam's target hall and on to its previous incarnation as a proton beam (see above map). Although the tunnel slopes fairly steeply upwards out of the ground, it tracks the straight line between Fermilab and the detector in the Soudan Mine in Minnesota: the slope is caused by the curvature of the earth.

There is a target painted on the wall after the near detector, exactly where the beamline enters the earth. Next stop, Minnesota.

The MINOS building, located 350 feet above the near detector.

Another neutrino experiment at Fermilab is the Mini Booster Neutrino Experiment (MiniBooNE). While it also looks for muon neutrinos oscillating to become electron neutrinos, it was specifically designed to confirm or refute the results of the Liquid Scintillator Neutrino Detector (LSND) experiment at Los Alamos, which found evidence implying the existence of a fourth type of neutrino, called a sterile neutrino. In 2007, the MiniBooNE team released results which showed no evidence for sterile neutrinos, but it did detect what it called a “low energy excess.” They are now planning for the next generation experiment, MicroBooNE, to investigate what exactly is causing that excess.

The MiniBooNE detector is remarkably simple: a sphere filled with 800 tons of baby oil and lined with over 1000 photodetectors. The photodetectors pick up the signals produced when a neutrino collides with the nucleus of an atom, which happens about once every 20 seconds. MicroBooNE’s detector will be even more finely tuned and be able to distinguish between different types of signals. As MiniBooNE’s Georgia Karagiorgi explained to us, “A lot of background [in MiniBooNE] comes from interactions that produce a single photon. If it was a true signal, it would produce a single electron. It [MicroBooNE] can really tells us if the low energy excess is being caused by electron neutrinos interacting in the detector or some other interaction that we did not account for somehow — or is a new interaction that takes place that we didn’t know about before.”

If it weren’t buried underground (to avoid receiving even more background radiation), the MiniBooNE detector would be up there with the bubble chamber among the weirdest and most beautiful things at Fermilab. Check out a picture here. As it were, we could only see the room above the detector.

The room above MiniBooNE.

The room above MiniBooNE.

MiniBooNE's hill-building.

Georgia and our other MiniBooNE tour guide, Christina Ignarra, are both graduate students at MIT working with Janet Conrad, perhaps the greatest spokesperson neutrinos could ever hope to have. As Georgia said, “She makes you so excited about physics.” I got to know Janet at Columbia, where she taught before MIT, and her enthusiasm for the field is indeed infectious. You can read all about MiniBooNE and Janet’s cult of personality in this New Yorker profile, written by Los Angeles Times science writer (and fellow Barnard graduate) K.C. Cole.

I interviewed Janet about neutrino physics and Fermilab’s future in 2007. Back then she had recently started working on Project X, which she described as an upgrade that “provides a lot of protons, and it’s done with the technology you would use for the ILC” — the International Linear Collider, the proposed sister accelerator to the LHC (stay tuned for more on this exciting topic!). But when scientists at Fermilab first started thinking about the idea, the intensity frontier wasn’t part of the lab’s official narrative. “Project X was a code name because you couldn’t talk about anything but the ILC,” Janet explained. “And the code name stuck.”

Needless to say, the days of neutrino physics sneaking around behind the backs of higher energy experiments are over. Experiments like MINOS and MiniBooNE have, as Georgia said, already “proven that the Standard Model is inadequate to describe particle properties” — something that is notoriously difficult for experiments to do. Fermilab is clearly excited about its strong neutrino physics program, and I am excited to see the lab taking a new direction. Flexibility and a willingness to change direction aren’t often features of Big Science (or DOE programs), but Fermilab is investing in its own future precisely by being open to many different possibilities. I think Robert Wilson would be proud.

-Lizzie (photos and captions by Nick)

Update: Lizzie’s uncle, Don Wildman, also visited MINOS as the host of the History Channel’s show Cities of the Underworld. Read more about his visit here.

A panorama showcasing Wilson's blue-and-orange color scheme and his self-designed π-shaped power poles stretching off into the distance.

Fermilab was built on a green field site, meaning that there was almost nothing there before the lab. Since building where there is no existing infrastructure is so much more expensive than upgrading (or simply repurposing) existing lab space and equipment, it is rarely done anymore. The Superconducting Super Collider’s green field construction contributed significantly to its burgeoning cost estimates and thus played a role in its cancellation. By contrast, Brookhaven’s Relativistic Heavy Ion Collider makes use of a myriad of pre-existing accelerator components and the Large Hadron Collider is housed in the tunnel formerly used by CERN’s Large Electron-Positron Collider.

Fermilab was almost singlehandedly designed by the legendary physicist Robert Wilson, who managed to complete his pet project ahead of schedule and under budget by exerting an extraordinary degree of personal control over its construction details. His efficiency, along with the 1960s’ tremendous respect for physics, gave him the freedom to do things his way. In most instances, this freedom resulted in some seriously idiosyncratic architecture.

Wilson's idea of a sensibly-designed roof.

Wilson was particularly fond of enormous circles on doors.

More Fermilab architecture.

The π-poles in all their glory.

Additional construction at Fermilab has stayed very close to Wilson’s vision and steps have been taken to preserve the laboratory’s past. The pi poles are scrupulously, if laboriously, protected from woodpecker damage, and the original bubble chamber now serves as a sculpture that looks like something out of Willy Wonka’s factory.

The Bubble Chamber. Definitely the winner of the trip's "What in the hell is that?!" award.

It's a little unclear why the Bubble Chamber has to look so much like a spaceship. It even has a door.

And why did they need SO MANY of these inputs (or outputs)?

The Bubble Chamber's instrument-lined legs. Or possibly its rocket nozzles.

The lab is also home to a herd of bison. In the past, one was killed at the end of every summer for a barbeque, and a stuffed bison head still hangs above the pool table in the lab’s Users’ Center. Today, the bison are left to peacefully make their home in part of the lab’s prairie preserve.

Fermilab's bison, which, urban legend holds, serve the role of canaries in a mine: if something goes really wrong at Fermilab, you can tell because the bison start dying off.

Bison calves at play.

If Wilson could afford to build his weird dream lab because he stuck to the budget, Fermilab can afford to remain this quirky and strange because it is home to the Tevatron, which has been the world’s most powerful particle accelerator since 1983. The machine’s most important discovery was the 1995 observation of the top quark, which filled in the last missing piece in the Standard Model’s prediction of six quarks. (The fifth quark to be observed, the bottom quark, was discovered at Fermilab, too, but using fixed target experiments in 1977.) The Tevatron has been the heart of particle physics for the last 25+ years, and its presence has defined Fermilab since it was built.

Even when the data doesn’t shake the foundations of physics, the Tevatron provides a view into an aspect of reality that was previously accessible only to theory and imagination. As the most powerful collider in the world for so long, it remains the only place in the world – indeed, perhaps the only place in the universe since shortly after the Big Bang – where certain conditions and types of matter exist.

The Tevatron has two detectors: the Collider Detector Facility (CDF) and DZero, which is named for its position on the accelerator ring. We visited CDF on this visit:

The CDF detector building at the Tevatron. The detector you see in the center is actually just an enormous photograph. The detector itself is nestled behind the door on the right of the above image and is only brought out into the room for repairs.

The door hiding the CDF detector at the Tevatron.

Of course, once can’t talk about the Tevatron these days without talking about the LHC. Once it gets up and running, the LHC will produce collisions that are seven times more powerful than the ones at the Tevatron — essentially leaving the older accelerator in the dust when it comes to the search for the Higgs boson, supersymmetry, and other fields of Beyond the Standard Model physics that require higher energy machines. So what happens to the Tevatron? What happens to Fermilab? And more importantly, what happens to the thousands of scientists who have built their careers (and often, their lives) around Fermilab’s accelerator?

When I worked at Fermilab four years ago, I never heard anything but enthusiasm for and excitement about the prospect of the LHC. But it was clearly difficult for the lab to imagine itself playing second-highest-energy fiddle to CERN. Wilson Hall is even home to a remote LHC control room, so scientists at Fermilab can monitor the machine while their CERN counterparts are sleeping. A practical move, but one that seems to scream, “Don’t forget about us!”

The LHC Control Room located at Fermilab.

In 2005, the Tevatron was scheduled to be shut down in 2009. Now they’re talking about running through 2011, and given how difficult starting up the LHC is proving to be, the shut down date could be pushed back even further. When I asked CDF’s Gene Flannagan when he thought we’d be saying goodbye to the machine, he said, “They’ve been talking about turning the Tevatron off since I came here in 1999, so I have no idea.”

The Tevatron is now running better than ever. The machine’s luminosity (number of collisions) has increased so much in the last few years that it’s actually been difficult for the experiments to keep up. CDF expects to double its data sets in the next two years, and after decades of operation, the scientists have a pretty good idea of where to look for the most exciting results. It’s even possible the Tevatron experiments could detect the Higgs, if they get lucky and the particle has a low enough mass.

No matter how many low-mass Higgs searches the detectors run or how many remote control rooms Fermilab builds, the Tevatron will never be the LHC. But that doesn’t mean it’s automatically obsolete. In fact, as long as the LHC remains mired in technical difficulties, the Tevatron’s independence may prove to be its greatest strength. Shiny new machines dominate news about Big Science, but often older means wiser. I was struck by how smoothly everything runs at CDF — they actually manage to take date 24 hours a day when the machine is running, and many of the youngest collaborators have never even seen the detector because things need to be fixed so rarely. After 25 years, the Tevatron and the scientists who work with it know what they’re doing.

I have no doubt that the Tevatron will remain a vital part of high energy physics for many years, whether in its current capacity or serving a new and unexpected purpose. If Oak Ridge can find use for an 8-track player, Fermilab should be able to keep the second most powerful particle accelerator in the world alive.

Fermilab's Wilson Hall at sunset. Naturally, the building was designed by Robert Wilson.

Stay tuned for more about Fermilab’s neutrino research and the development of the International Linear Collider (ILC), the postulated successor to the LHC.

Lizzie staring into the exposed belly of the Recoil Mass Spectrometer

Initially, we didn’t think we’d have time to visit Oak Ridge – our planned route took us on a comparatively leisurely drive from New York to Chicago with a stop in Pittsburgh for a night. But as the recommendations began to pile up, first from John Haggerty and the other physicists at Brookhaven, then Cindy Kelly of the Atomic Heritage Foundation, we realized that the additional visit to Tennessee would probably be worth it.

The loading face of the Graphite Reactor at Oak Ridge National Laboratory

Oak Ridge was the site of the first nuclear reactor after Enrico Fermi’s successful chain reaction at the University of Chicago. Constructed during the early stages of the Manhattan Project, the Graphite Reactor was used to process plutonium for the first atomic bombs. A self-contained museum now, the reactor was never truly decommissioned – just ceremonially turned off about six months after a flood damaged it beyond reasonable repair. Myriad plans for the Reactor surfaced and dissolved as decades passed: a company was supposed to come in and fill the whole thing with concrete a few years ago; and there was a proposal to move the reactor face to a museum in the town of Oak Ridge. But today it sits as it ever did, still in cooldown phase, only intermittently accessible to the public since post-September 11th security measures limited access to the lab as a whole.

No radiation has been detected in the building for fifteen years, but in principle the reactor could be turned back on at any time. Of course, as our guide Fred Strohl put it, “technology has changed a little since then.” The reactor functioned on the barest of nuclear principles: workers would push rod-shaped chunks of uranium through holes in the reactor face with long sticks, a process not unlike the loading of an 18th century musket, until the critical mass of uranium was reached deep in the machine and the famous chain reaction would begin.

The loading face of the Graphite Reactor at Oak Ridge National Laboratory

Mannequins demonstrate the operation of the Graphite Reactor: slugs of uranium were pushed through the reactor face with long rods, one by one, until enough radioactive material was in place for a nuclear chain reaction to begin.

Amusingly enough, the first time that this happened at Oak Ridge was almost an accident. The bosses, M. D. Whitaker and R. L. Doan, had gone home for the night, not expecting the reactor to go critical until the next day. But they had overestimated the amount of uranium required and underestimated the zeal of their workers, who added fuel rods more quickly than the program had called for. Woken in the middle of the night, they gathered with their subordinates at the plant as the reactor burst into life.

After spending time in RHIC’s Main Control room, the control room for the graphite reactor was beautifully antiquated:

The state-of-the-art control room for Brookhaven's Relativistic Heavy Ion Collider

The control room for the Graphite Reactor at Oak Ridge

Control panels in the Graphite Reactor's control room. Note the pre-digital readout mechanism: outputs were written on paper that scrolled through the machine, not displayed as alterable numbers and letters.

After the war, the Graphite Reactor was used to produce radioisotopes for basic physics research, medicine, agriculture, and industry. This periodic table indicates all the radioisotopes it was capable of producing:

Periodic table representing all of the isotopes that the Graphite Reactor could produce.

While the Graphite Reactor is now firmly a part of physics history, another old machine is still contributing to science at Oak Ridge: the Oak Ridge Isochronous Cyclotron, or ORIC for short. While most cyclotrons were decommissioned long ago and turned into sculptures or scrap metal, ORIC has operated in various forms since 1962. It is currently part of the Holifield Radioactive Ion Beam Facility (HRIBF), helping to supply radioactive ion beams to several experiments.

A view of the Oak Ridge Isochronous Cyclotron

The cyclotron room was the first area we’d visited that could potentially have exposed us to harmful radiation. One of our guides, Carl Gross leaned in as we approached the room, and said with a gentle seriousness that commanded particular attention: “try not to touch anything while you’re in there.”

To enter the room, we passed through the most intimidating door we’d ever seen. Metal, twenty feet tall and six feet thick, hung on hinges the size of a man’s chest, with the following message inscribed on the inside:

NOTICE
In the event that you are locked in
this room, depress red button
on this door or any of the
red buttons on the walls
This cuts off power
to cyclotron
Leave red buttons all the way in
until cyclotron operator
opens the door
The cyclotron cannot be
operated while red buttons
are depressed

The enormous vault-like door that serves as the entrance to Oak Ridge's cyclotron. (Stay tuned for a whole post on physics laboratory doors).

An example of the precautions (careful signs, brightly colored ropes, etc.) that DOE scientists take to prevent contamination or exposure to radioactive material. Presumably also one of the things Carl warned us not to touch.

We were all careful not to touch anything with our hands while visiting the cyclotron, but it would be difficult to move without touching the floor. Here's Alan Tatum getting his feet checked for radioactive material by Carl Gross after we came out. Lizzie and I underwent the same treatment.

After ORIC does its job, the already fast-moving particles are sped up even more by the tandem accelerator, a 100-ft. tall version of the Van de Graff generators that make your hair stand on end at science museums. This one would do much more than ruin your hairstyle if you went inside while it was turned on, however, so we didn’t get to ride the tiny elevator that takes one person at a time inside for maintenance.

The curved bottom of the tandem accelerator enclosure. Access to the enclosure can only be achieved by using a one-person elevator (below), which rises through the submarine-like pressure door featured in the above picture.

The elevator that provides access to the tandem accelerator enclosure.

We rode a far larger elevator up the outside of the tandem’s enclosure to take a look at the top of the accelerator — and the view of the lab from its roof.

The top of the tandem accelerator enclosure, just below the roof.

A panoramic view of Oak Ridge from the top of the tandem accelerator tower, including the lake with swans imported from Fermilab.

A panoramic image of the view from the Oak Ridge dining hall, with the tandem accelerator tower on the right.

The fully accelerated particles travel down several beam lines, one of which ends at the Recoil Mass Spectrometer. By running the beam through a momentum separator and a mass separator, the RMS team can isolate specific products of nuclear reactions and study the structure and behavior of atomic nuclei.

Detail of the mass separator portion of the Recoil Mass Spectrometer.

Detail of the mass separator portion of the Recoil Mass Spectrometer.

Detail of the beginning of the momentum separator portion of the Recoil Mass Spectrometer.

Detail of a beautiful machine towards the end of the momentum separator portion of the Recoil Mass Spectrometer.

A wider view of a beautiful machine towards the end of the momentum separator portion of the Recoil Mass Spectrometer.

A target, semi-destroyed in the course of an experiment, that gives a sense of the size of the beam.

In keeping with Oak Ridge's practice of reusing what might otherwise be obsolete technology, an 8-track tape recorder, seen here, records data from experiments.

Other particles from the HRIBF are used to study the nuclear reactions that take place in novae and other stellar explosions. The experimental astrophysics group recently rescued the Daresbury Recoil Separator from the scrap pile in England to make precision measurements of certain products of such reactions.

The Daresbury Recoil Separator, which was brought over from England after the cancellation of a British research program.

The Daresbury Recoil Separator, like the Recoil Mass Spectrometer, relies on ORIC and the tandem accelerator to supply charged particles.

(Incidentally, Michael S. Smith, the leader of the experimental astrophysics research group, also heads the Nuclear Data Project, a totally cool effort to collect and evaluate the latest research on nuclear structure and astrophysics. Its open source ethos encourages data sharing and tries to address the many problems that accompany secrecy in science by emphasizing the free and efficient flow of information. Since Nick wrote his undergraduate thesis on commercially imposed secrecy in biotechnology, we were particularly excited to hear about the issue in another field of science.)

Lizzie talking with Michael S. Smith about the Nuclear Data Project.

Not everything at Oak Ridge is charmingly old, however. The lab is home to the National Center for Computational Sciences, and Jaguar, the second fastest supercomputer in the world. It also houses a stunning visualization wall that brings the lab’s research to life, allowing scientists to showcase their work and make connections that they might otherwise miss.

National Center for Computational Sciences at Oak Ridge, consistently home to some of the world's fastest computers (presently home to Jaguar, the world's second-fastest).

A detail of the enormous wall of high-resolution integrated projector screens at the visualization center.

Lizzie's shadow as she walks behind the projector screen wall at the visualization center.

The Spallation Neutron Source is on the cutting edge of materials science, using neutrons to probe the structure of many different kinds of matter. Like the National Synchrotron Light Source, it is a user facility, and thus fundamentally interdisciplinary. It even helped disprove the hypothesis that President Zachary Taylor was assassinated.

A laboratory at the Spallation Neutron Source.

Scientists in a lab at the Spallation Neutron Source.

Oak Ridge was an impressive mix of old and new, focused on preserving its history, adept at recycling machines that might otherwise have gone to waste, and dedicated to being a player in the interdisciplinary science that may well be the future of the National Labs. Thanks to Vince Cianciolo, Fred Strohl, Cindy Kelly, Jim Beene, Carl Gross, Alan Tatum, and Michael Smith for making our visit possible and for showing us their amazing work.

Next stop: Fermilab!

-text by Lizzie and Nick, photos by Nick