A million Russian artillery shells helped scientists discover the Higgs boson. And all over the world, remnants of World War II weapons are built into the most mysterious experiments in physics.
In the mid-1990s, physicists needed tons of a metal strong enough to withstand the massive magnetic fields of the house-sized Compact Muon Solenoid (CMS) experiment, one of the particle detectors on the Large Hadron Collider in Geneva, Switzerland. They settled on high-quality brass - but where would they get enough of it?
Although Russian science was floundering during the 1990s, those Russian scientists who were part of the international CMS collaboration still wanted to help. One of the scientists remembered that the brass in the tough artillery shell casements had the exact qualities that the detector needed. A Russian navy commander agreed to give shells leftover from World War II to the CMS scientists, who used 600 metric tons of the brass in the experiment. The LHC turned on in 2009, and with the CMS detector's help, ended a 50-year, many-billion-dollar search with the joint discovery of the elusive Higgs boson particle in 2012.
Proving the most basic laws of physics (you know, just the ones that make up the fabric of our being) is really expensive. These days, fundamental particle-hunting experiments can cost billions of dollars, so recycling is common. Parts are frequently swapped between machines. Magnets originally built for medical imaging machines can find their way into nuclear physics research. And sometimes, decommissioned war parts end up in some of the most important physics experiments, including several Nobel Prize winners that have shaped our modern understanding of how the universe works.
World War II left behind huge warships plated with steel several inches thick, material from nuclear weapons development, and other parts which scientists acquired through connections, government surplus lists, and other back channels. In many cases, the parts are free (except for the cost of shipping).
In the United States, war-part re-purposing commonly involved using the steel armour plating from decommissioned ships. Particle physicists working during the 1960s and 1970s used metal to do just about the same thing it did for the warship: keep unwanted things out. For these experiments, that thing was background radiation.
"The physicists knew they were going to need large quantities of high-density material," Valerie Higgins, an archivist from Fermi National Accelerator Laboratory in Illinois, or Fermilab, told Gizmodo. "They were looking for inexpensive ways to get that material. They considered using used soil, or automobiles — but steel would be a much better means of shielding. What they needed was to filter out unwanted particles."
But more importantly, this cheap steel is thick as hell. In 1962, American physicists Leon Lederman, Jack Steinberger, and Melvin Schwartz could have been one of the first teams to incorporate such a large quantity of wartime metal into their experiments at Brookhaven National Lab in New York. They hoped to better study neutrinos, incredibly tiny and incredibly common particles which most experiments can't detect because they barely interact with regular matter at all. They're almost like ghosts.
Studying the properties of such elusive particles required ingenious thinking. The physicists thought they could blast a hunk of some target metal, beryllium, with a beam of protons from the Alternating Gradient Synchrotron experiment at Brookhaven. This would result in a shower of different particles. Putting the steel between the shower and their final detector would ensure only neutrinos made it through.
There's another reason wartime steel transitioned so well into particle physics, aside from cost-cutting. Steel from WWII and prior is sometimes called low-background steel, since it is less radioactive than steel from after the beginning of the atomic age. Newer steel is often contaminated with radioactive cobalt, said Phillip Barbeau, a physicist from Duke University who uses WWII-era steel in his own experiments. Present-day steel still isn't very radioactive, he said, "but it's radioactive for the physicist who worries about the radioactivity of fingerprints or dust."
A Fermilab letter discussing the use of the warship steel in 1974 (Image: Fermilab)
Low radioactivity is crucial for particle physics research. After all, radioactivity is a property of some matter, like very heavy metals, in which they spontaneously spit out high-energy particles. If the metal shielding is too radioactive, it might cause the experiment to detect false positives — particles from the shielding instead of from the experiment.
The special neutron beam and its battleship steel helped Lederman and his team win the 1988 Nobel Prize. Not only had they devised a whole new way of studying these elusive particles, but their ingenuity helped discover an entirely new kind, called the "muon neutrino."
"Leon was always amazing at finding this stuff," explained Robert Kephart, director of the Illinois Accelerator Research Center at Fermilab and a former colleague of Lederman's. "This stuff would just appear. I don't know exactly where he got it from." Kephart recalled Lederman acquiring a 41cm battleship gun to filter out particles travelling at the wrong angles. One of Lederman's grad students was just small enough to slip inside.
"I'll never have a grad student of that calibre again," Lederman would joke.
Other physicists realised that they could use the thick steel plating wherever they needed to keep ambient radiation out of a detector or keep particles from escaping. Through the 1970s, the National Accelerator Laboratory in Batavia, Illinois (now called Fermilab) acquired many tons of this wartime steel as shielding and filters for experiments that ultimately helped discover brand new particles.
Plenty of wartime vessels have made appearances in these physics experiments. Lederman's Nobel-winning discovery used machined sheets from the then-decommissioned USS Missouri battleship, write Carlo Giunti and Chung Kim in the Fundamentals of Neutrino Physics and Astrophysics textbook. Purchase orders sent to Gizmodo by Fermilab reveal requests for tons of steel from heavy and light cruisers, ships like the Fall River, Astoria, the Roanoke, and the Topeka.
"It was largely the steel shielding around the water line," the part of the hull below the water, "to make it much thicker so if torpedoes hit head-on, it would survive," explained John Peoples Jr., a physicist who began at Fermilab in 1971 and succeeded Lederman as the lab's director in 1989.
A purchase order for 197 tons of warship steel (Image: Fermilab)
During the 1970s, the Energy Research and Development Administration (ERDA, which merged with another agency to become the United States Department of Energy) would notify labs like Fermilab when the Navy had scrapped a ship. "Armour that could be useful to Fermilab is requisitioned by the Fermilab Research Division, and ERDA then requests that this steel be reserved for the factory's needs," according to a 1975 Fermilab newsletter.
Fermilab eventually acquired a whole lot of the stuff. The quark-discovering Tevatron collider, decommissioned in 2011, incorporated large blocks of battleship steel in its underground particle detector, the Collider Detector at Fermilab experiment or CDF. They used it as a filter and even built magnets out of it. When scientists realised that they needed more shielding, they began burying entire unused steel magnets in the dirt around it. "There were a bunch of these dipole magnets that were in inventory," said Kephart. Peoples decided that burying the magnets and keeping them in inventory was the same thing. "'I know where they are if I need them,'" Kephart recalled Peoples saying. "'They're buried.' They have been underground ever since."
It's not easy to move or manipulate this stuff. While it's free, explained Jonathan Lewis, associate head of Fermilab's particle physics division, shipping the steel to the experiment can be quite expensive. And remember, battleships used the plating to stop torpedoes. "It's extremely difficult to machine," said Barbeau at Duke. "Every time I have one of the guys in the machine shop work on it, it breaks the bits." You have to arc weld it — the dangerous kind of welding that requires melting the metal itself. "It's very bulletproof, let's put it that way," he said.
Others didn't have the same success using steel in their experiments. Occasionally, the steel contained slightly more radioactive metal left over from the radioactive thorium-containing welding rods, explained Todd Hossbach, senior research physicist from Pacific Northwest National Labs. Even steel without the radioactive welding rods was more radioactive than some other options. This was especially noticeable in the experiment Hossbach worked on, buried deep underground in South Dakota's Homestake Mine.
Eventually, Hossbach's team turned to specially fabricated, high-quality copper and other metals. Ultimately the decision to use steel relies on both cost and just how little background radiation the experiment requires. "Every situation is different," said Hossbach. "Today, for our standard low-background radiation detection systems, we would typically never use pre-atomic era steel for the innermost shielding. However, it is possible to use this material in the outer shielding layers or as part of a support structure."
Steel isn't the only wartime part that makes appearances in these experiments. Kephart's experiment used beryllium left over from nuclear weapons research. Another project at Fermilab used a cooling system taken from a California missile testing facility, according to another 1975 Fermilab newsletter.
The scientists of the neutrino-hunting team at Brookhaven continued to research. Steinberger moved to work at CERN and still visits the lab. Schwartz passed away in 2006. Leon Lederman lives with his wife in Idaho, but recently sold his Nobel Prize medal for almost $US800,000 ($1,044,346) to help pay for his medical bills after being diagnosed with dementia.
But wartime parts continue to play a crucial role in particle physics experiments, even today. Barbeau, who frequently uses strange metals (including ancient Roman lead) in his experiments at Duke, discovered tons of battleship steel behind a building on Duke's campus. Several experiments at Oak Ridge National Laboratory in Tennessee incorporate the stuff. That includes the COHERENT experiment, which recently discovered an interaction between neutrinos and entire atomic nuclei physicists thought would be impossible to detect. And of course, there's CMS and its Russian artillery shells.
Mysteries remain for particle physicists to solve. Are there new, fundamental particles we haven't discovered? What are the properties of the particles we already have discovered? Why does our universe contain particles like these, with properties whose values seem too fine-tuned to be the result of random chance? There are plans to build new, enormous colliders in Japan and in China. CERN proposes a successor to its current collider, the Large Hadron Collider, that may require up to 100 kilometers, or 100km, of experiment and tunnel. You can bet that these experiments will feature recycled parts, some of them a peaceful sequel to their wartime function.
"It's efficient," said Fermilab's Lewis. "Why wouldn't you do it? 'Reduce reuse recycle…' so we reused."