10 words that mean something different to physicists

Some of this science sounds awfully familiar.

Physics Slang

Given the popularity of our first article about physics concepts with deceptively common names, Symmetry is back with 10 more seemingly normal words that mean something different in a science context. Get ready to talk science:

Illustration by Sandbox Studio, Chicago with Corinne Mucha


In particle physics, flavor has nothing to do with your taste buds. Instead, the term signifies different kinds of particles. There are six “flavors,” or varieties, of quark: up, down, top, bottom, strange and charm. There are also six flavors of leptons: the electron, muon and tau, and their corresponding neutrinos (the electron, muon and tau neutrinos).

Illustration by Sandbox Studio, Chicago with Corinne Mucha


Put away your box of crayons. Color, much like flavor, is another way of differentiating subatomic particles, but it isn’t based on hue. Quarks can be designated as red, green or blue, but the colorful naming scheme represents an abstract characteristic of the particles’ charge related to the strong (instead of electric) force rather than an actual color. In fact, there’s a whole field of physics dedicated to QCD: quantum chromo (or color) dynamics.

Illustration by Sandbox Studio, Chicago with Corinne Mucha


Physical fields can be dotted with crops or laden with grass and flowers. Fields in physics, however, are more monotone, and usually extend to infinity. They permeate the universe, becoming apparent only when they encounter something that can interact with them. Electrically charged particles can interact with the electromagnetic field; particles with mass can interact with the gravitational field, and part of what gives those particles mass is the Higgs field.

Illustration by Sandbox Studio, Chicago with Corinne Mucha


This is your captain speaking: In particle physics, jets are unrelated to airplanes. Jets are showers of hadrons (particles made of quarks and gluons) that often emerge from high-energy collisions in places like the Large Hadron Collider. They’re caused when an energetic quark or gluon starts to head off on its own. Quarks and gluons don’t like to appear solo, so the energetic particle pulls some friends out of the vacuum, creating a shower of particles headed in roughly the same direction. A jet is born!

Illustration by Sandbox Studio, Chicago with Corinne Mucha


We typically think of a trigger as a device that sets something off. In particle physics experiments, a trigger is the system that tells a computer in a split second to capture the data from a certain collision. It’s a way of focusing on just the most interesting and relevant particle interactions at experiments that produce far more data than can be reasonably recorded, stored and analyzed.

Illustration by Sandbox Studio, Chicago with Corinne Mucha


Backgrounds aren’t just for paintings and photographs. In physics experiments, the background refers to all of the extra signals that a detector may pick up while it is searching for something unique. For example, a detector built to study a beam of neutrinos produced at an accelerator might also detect particles coming from space. Sorting the desired signal from the background is a crucial part of particle physics experiments.

Illustration by Sandbox Studio, Chicago with Corinne Mucha


While “wimp” is an insult used to imply someone lacks courage or is weak, a “WIMP” is a strong candidate for dark matter. WIMP is an acronym for “weakly interacting massive particle,” a hypothetical particle that would be massive enough to explain mysterious gravitational effects cosmologists see in the universe but that would interact with other matter rarely enough to explain why it has yet to be observed. They’re one of several ideas for what makes up dark matter, the invisible substance that is thought to vastly outnumber regular matter in our universe.

Illustration by Sandbox Studio, Chicago with Corinne Mucha


Inflation probably makes you think of a balloon blowing up or currency going down in value. But it could also inspire thoughts of the beginning of our universe. Physicists refer to inflation as the period just after the Big Bang when space expanded exponentially in all directions, causing small quantum variations to expand to a cosmic scale. This ultimately led to the large-scale structure of matter in the universe that we see today in things like galaxy clusters.

Illustration by Sandbox Studio, Chicago with Corinne Mucha


When most of us deal with something entangled, it’s usually something like the cables of a pair of headphones. But for particle physicists, entanglement refers to what Einstein called “spooky action at a distance”: the way that two particles can be separated by great distances but “connected” in such a way that influencing one seems to affect the other instantaneously.

Illustration by Sandbox Studio, Chicago with Corinne Mucha


Your standard candle is probably made of wax and has a wick. An astrophysicist’s standard candle is an astronomical object with a known brightness (or luminosity) that can be used to measure distances on an enormous scale. Examples of standard candles include X-ray bursts and different types of stars, such as Cepheid variable stars or supernovae (exploding stars). Measuring the speed of the expansion of the universe over time using standard candles, scientists made the startling discovery that the universe is growing at an accelerating rate.

The bubble chamber sand mandala

One sprinkle of sand at a time, two artists recreated the moment a particle passed through a detector 30 years earlier.

Overhead view of artists kneeling on a blue surface and creating an image of bubble chamber tracks with white sand

For 30 days, Chris Klapper and Patrick Gallagher spent about 12 hours per day sitting or kneeling atop a 20-by-14-foot platform at The Invisible Dog Art Center in Brooklyn. All day they gently scratched the sides of foot-long copper tubes, using the vibrations to coax grains of crushed, dyed marble onto a large blueprint.

Slowly, they sculpted out a replica of a decades-old photograph—an image of tracks of microscopic bubbles left behind by charged particles curving through a magnetic field in a scientific instrument called a bubble chamber.

Titled “Everything and Nothing,” the bright blue and white sculpture was part of Klapper and Gallagher’s ongoing series, “Dataatadata.” The piece was inspired by the Tibetan Buddhist tradition of the sand mandala.

Mandalas, figures that often feature concentrically arranged, repeating shapes, originated in both Hinduism and Buddhism as ritual symbols for the universe. Buddhist monks painstakingly create and then dismantle intricate mandalas made of sand as a meditation on the impermanence of life.

Mandalas can be found as far back as 14th century art. Bubble chambers, on the other hand, are not so old. Just a few decades ago they were considered cutting-edge technology in particle physics.

Bubble chambers were large vessels filled with transparent liquid, heated just below boiling point. A piston would rapidly decrease the pressure inside the chamber, which caused the charged particles that passed through the superheated liquid to produce microscopic bubbles as they traveled. Scientists photographed those bubbles to study the paths the particles took and the energy they left behind.

To find the perfect bubble chamber image to recreate, Klapper and Gallagher scrolled through hundreds of these photographs in the archive at the US Department of Energy’s Fermi National Accelerator Laboratory.

One had a large circle, a remnant of the bubble chamber piston, directly in the middle of all the particle tracks.

As it happens, mandala means “circle” in Sanskrit. “That image really stood out to us,” Gallagher says: It was the perfect marriage of mandala and particles.

Using a grid system, the artists sketched each square of the photograph onto their platform, mapping more and more particle tracks as they went. Once their blueprint was ready, they began the task of putting millions of tiny grains in place.

When guests entered the gallery during their work, either Klapper or Gallagher would pause and explain what they were doing.

“Normally people don’t get to see artists in the process of creating,” Klapper says. “We got to create these incredible connections with people and see the moment their eyes lit up with interest and understanding.”

With their bubble chamber, Fermilab physicists had created a permanent record of a fleeting particle interaction, by photographing it. The sand mandala was a different kind of record.

On the final day of the sand mandala exhibit in New York, an audience gathered to witness the performance one last time. At 7:30 p.m., the two creators stood across from each other on the platform and finished their piece—by dismantling it. They used thick brushes to sweep their carefully placed sand into a single pile, honoring the impermanence of the particles they depicted.

In a process they say was more about transformation than destruction—and perhaps a nod to the conservation of the energy—the final collection of sand was placed into a large glass beaker to one day be displayed again.

An astronomical data challenge

The Large Synoptic Survey Telescope will manage unprecedented volumes of data produced each night.

An illustration of the LSST

The Large Synoptic Survey Telescope—scheduled to come online in the early 2020s—will use a 3.2-gigapixel camera to photograph a giant swath of the heavens. It’ll keep it up for 10 years, every night with a clear sky, creating the world’s largest astronomical stop-motion movie

The results will give scientists both an unprecedented big-picture look at the motions of billions of celestial objects over time, and an ongoing stream of millions of real-time updates each night about changes in the sky.

37 billion objects observed over 10 years

Illustration by Sandbox Studio, Chicago with Ana Kova

Accomplishing both of these tasks will require dealing with a lot of data, more than 20 terabytes each day for a decade. Collecting and storing the enormous volume of raw data, turning it into processed data that scientists can use, distributing it among institutions all over the globe, and doing all of this reliably and fast requires elaborate data management and technology.

International data highways

This type of data stream can be handled only with high-performance computing, the kind available at the National Center for Supercomputing Applications at the University of Illinois, Urbana-Champaign. Unfortunately, the U of I is a long way from Cerro Pachón, the remote Chilean mountaintop where the telescope will actually sit. 

But a network of dedicated data highways will make it feel like the two are right next door.

Every 40 seconds, LSST’s camera will snap a new image of the sky. The camera’s data acquisition system will read out the data, and, after some initial corrections, send them hurtling down the mountain through newly installed high-speed optical fibers. These fibers have a bandwidth of up to 400 gigabits per second, thousands of times larger than the bandwidth of your typical home internet.

Within a second, the data will arrive at the LSST base site in La Serena, Chile, which will store a copy before sending them to Chile’s capital, Santiago. 

From there, the data will take one of two routes across the ocean. 

The main route will lead them to São Paolo, Brazil, then fire them through cables across the ocean floor to Florida, which will pass them to Chicago, where they will finally be rerouted to the NCSA facility at the University of Illinois. 

If the primary path is interrupted, the data will take an alternative route through the Republic of Panama instead of Brazil. Either way, the entire trip—covering a distance of about 5000 miles—will take no more than 5 seconds.


Illustration by Sandbox Studio, Chicago with Ana Kova

Cerro Pachon, Chile La Serena, Chile Lyon, France Tucson, USA NCSA, University of Illinois


Curating LSST data for the world

NCSA will be the central node of LSST’s data network. It will archive a second copy of the raw data and maintain key connections to two US-based facilities, the LSST headquarters in Tucson, which will manage science operations, and SLAC National Accelerator Laboratory in Menlo Park, California, which will provide support for the camera. But NCSA will also serve as the main data processing center, getting raw data ready for astrophysics research. 

NCSA will prepare the data at two speeds: quickly, for use in nightly alerts about changes to the sky, and at a more leisurely pace, for release as part of the annual catalogs of LSST data.

5.5 million images observed over 10 years

Illustration by Sandbox Studio, Chicago with Ana Kova

Alert production has to be quick, to give scientists at LSST and other instruments time to respond to transient events, such as a sudden flare from an active galaxy or dying star, or the discovery of a new asteroid streaking across the firmament. LSST will send out about 10 million of these alerts per night, each within a minute after the event.

Hundreds of computer cores at NCSA will be dedicated to this task. With the help of event brokers—software that facilitates the interaction with the alert stream—everyone in the world will be able to subscribe to all or a subset of these alerts.

NCSA will share the task of processing data for the annual data releases with IN2P3, the French National Institution of Nuclear and Particle Physics, which will also archive a copy of the raw data. The two data centers will provide petascale computing power, corresponding to several million billion computing operations per second

60 petabytes of data collected over 10 years

Illustration by Sandbox Studio, Chicago with Ana Kova

The releases will be curated catalogs of billions of objects containing calibrated images and measurements of object properties, such as positions, shapes and the power of their light emissions. To pull these details from the data, LSST’s data experts are creating advanced software for image processing and analysis. They are also developing machine learning algorithms to help classify the different objects LSST finds in the sky. 

Annual data releases will be made available to scientists in the US and Chile and institutions supporting LSST operations.  

Last but not least, LSST’s data management team is working on an interface that will make it easy for scientists to use the data LSST collects. What’s even better: A simplified version of that interface will make some of that data accessible to the public.

Poster: LSST by the Numbers
Artwork by Sandbox Studio, Chicago with Ana Kova

Taking a collider to the dark energy problem

Every second, the universe grows a little bigger. Scientists are using the LHC to try to find out why.

Simulation of a dwarf galaxy

With the warmth of holiday cheer in the air, Nottingham University theoretical physicist Clare Burrage and her colleagues decided to hit the pub after a conference in December 2014 and do what many physicists tend to do after work: keep talking about physics.

That evening’s topic of conversation: dark energy particles. The chat would lead to a new line of investigation at the Large Hadron Collider at CERN.

Dark energy is a catch-all term that scientists coined to describe whatever seems to be pushing the bounds of the universe farther and farther apart. If gravity were the only force choreographing the interstellar ballet of stars and galaxies, then—after the initial grand jeté of all of the matter and energy in the universe during the big bang—every celestial body would slowly chassé back to a central point. But that’s not what’s happening. Instead, the universe continues to drift apart—and it’s happening at an accelerating rate. 

“We really don’t know what’s going on,” says Burrage. “At the moment, there are problems with all of our possible solutions to this problem.”

Most experiments studying this mysterious cosmic expansion look at intergalactic movements and precision measurements of the effects of gravity. Dark energy could be a property of spacetime itself, or just a huge misunderstanding of how gravity works on a cosmic scale. 

But many theorists suspect that dark energy is a new type of force or field—something that changes how gravity works. And if this is true, then scientists might be able to put just the right amount of energy into that field to pop out a particle, a particle that could potentially show up in a detector at the LHC. This is the way scientists discovered the Higgs field, by interacting with it in just the right way for it to produce a Higgs boson.

“Cosmologists know that there is new physics we don’t understand, and all the evidence is pointing towards something very fundamental about our universe,” Burrage says. “The experiments on the LHC are also very interested in the fundamentals.”

The ATLAS and CMS experiments, the big general-purpose experiments at the LHC, search for new fundamental forces and properties of nature by recording what happens when the LHC smashes together protons at just under the speed of light. The giant detectors surround the collision points and map the energy and matter released from the collisions, giving scientists a unique view of the clandestine threads that weave together to build everything in the universe.

The theory Burrage and her colleagues were poring over at the pub predicted that if dark energy is a new type of field, it might produce light particles with strong and specific interactions with matter. “The main focus of LHC has been heavy particles, so we had to go back and re-interpret the data to look for something light,” she says.

Burrage worked with Philippe Brax of Université Paris-Saclay and Christophe Englert of the University of Glasgow to check publicly available data from the first run of the world’s most powerful collider for signs of a lightweight dark energy particles. They quickly determined that the signs they were looking for had not appeared.

With this simple model easily eliminated, they decided to take on another idea with a more cryptic signature. They knew that more complex analyses would require the expertise of an experimentalist. So in April 2016, along with Michael Spannowsky of Durham University in the UK, they published a new hypothesis in the scientific journal Physical Review Letters—and waited.

They found their experimentalist in Spyros Argyropoulos, a postdoc at the University of Iowa working on the ATLAS experiment, who read their article. 

“The idea of testing dark energy was intriguing,” Argyropoulos says. “It’s not something we typically look for at the LHC, and making progress on this problem is a win-win for both cosmologist and particle physicist.”

Argyropoulos reached out to Burrage and her colleagues to define the parameters, and then he and a group of ATLAS scientists went to the data.

According to this new theory, dark energy particles should radiate off of energetic top quarks and show up in the detector as missing energy. Argyropoulos and his colleagues went through ATLAS analyses of top quarks and, in a separate search, looked at certain other collisions to see if any of them showed the signatures they were looking for. They did not.

While this might seem like a disappointing result, Argyropoulos assures that it’s anything but. “Physics isn’t just about finding the right answer,” he says. “It’s also about narrowing down all the possibilities.”

Burrage agrees: “Eliminating an idea with experimental data is a positive thing, even if it means our pet theory gets killed in the process. Theorists can always come up with more ideas, and it’s good for the field to have the spectrum of possibilities narrowed down.”

The landscape of dark energy theories is enormous. Burrage’s specialty is scouring that landscape, searching for theories that can be tested, and then proposing ways to test them. 

“Ten years ago, nobody was thinking that collider physics could put constraints on dark energy searches,” she says. “Theories have to pass all relevant experimental tests, and it’s looking like surviving the Large Hadron Collider is going to be an important one to our field.”

A taste of particle physics

For physicists Katy Grimm and Katharine Leney, science is a piece of cake.

Photo of people picking up pieces of cake from a table

If one wanted to follow the recipe for the universe, it would call for about 14 parts dark energy, 5 parts dark matter and 1 part visible matter. In a perpetually expanding cosmic landscape that reaches far beyond what even the most powerful telescopes can see, this might be hard to visualize. 

Physicists Katy Grimm and Katharine Leney, who are part of the ATLAS collaboration at CERN, found a solution for this: Use this recipe for the cosmos to bake a proportionally correct dark matter cake. Inside this cake, decorated on the outside with purple swirls of stars and galaxies, white chocolate chips represent visible matter, dark chocolate chips are dark matter, and beets, which are undetectable, take the place of dark energy. 

“We wanted to make it so that when you bite into this cake, it becomes clear just how little of the world is made up of the matter we can detect, and how much of it is made of elusive dark matter,” Leney says. “Our hope was to use the cake to teach people about the composition of the universe.”

Colliding passions

Grimm and Leney met while collaborating on the Di-Higgs searches at CERN—experiments that look for events that produce two Higgs bosons at the same time. These events are predicted in the Standard Model, but will require massive amounts of data before they can be found. Discovering them sooner than expected might be a sign of new physics.

While collaborating on these experiments, the physicists realized they have something else in common: Both of them grew up with a passion for baking. Each of their families stressed the importance of homecooked food, encouraging them to learn to cook and bake from a young age. But it wasn’t until recently that the two decided to combine two of their passions—science and baking—to start Physics Cakes, an outreach project that uses baked goods to explain complex topics related to particle physics. 

“I think the value of this project is being able to communicate complex scientific ideas in a fun, tangible way that doesn’t throw people off with complexity,” Leney says. “It's digestible.”

Schrödinger’s Kit Kat

The two have collaborated on many delicious science-y desserts, including an elaborate ATLAS detector cake, Standard Model cupcakes, Feynman diagram cookies, and treats they call “Schrödinger’s Kit Kat,” cake-like confections with bits of Kit Kats embedded in half of them, mirroring Schrödinger’s cat-in-a-box thought experiment that demonstrates the quantum phenomenon of superposition. 

Grimm remembers using “proton cookies” to teach a group of Girl Scouts about particle physics. She instructed them to coat graham crackers with frosting, which represents gluons, and three M&Ms, representing the quarks. The girls then smashed the cookies together, showing what happens at the Large Hadron Collider. Eating the cookies, Grimm explains, demonstrates the role of particle detectors in these experiments.

One of Leney’s cakes, which she baked for LGBTQ STEM day at CERN, received a lot of attention on the Physics Cakes Twitter account. The cake was covered with physics equations on the outside, and cutting into the cake revealed colored layers arranged into a rainbow.  

A good physics cake depends on the audience, Grimm says. People in the particle physics community tend to enjoy the more complex cakes. But for outreach, the cake should be simple so that people are able to understand it instead of getting bogged down by complicated details. Leney adds that her favorite cakes are the ones that allow people to learn about physics.

Taking whisks

The two hope to use Physics Cakes to reach groups that might not otherwise be exposed to science. They’re also baking up a plan use these tasty physics treats to create a book. The book would include photos of their creations along with recipes and explanations of the science behind them.

If anyone is interested in creating their own physics cakes, Grimm says they just need to tap into their creativity and passion and not be afraid to take risks.

“If you find some little tidbit in physics that you think is exciting, use your imagination to think about how that might become a cake,” she says. “Don’t worry about making it perfect or beautiful, just have fun.”

Tenacious persistence

Fermilab’s Liz Sexton-Kennedy talks to Symmetry about her lifelong drive to learn and how it led to her current role as Chief Information Officer for Fermilab.

An illustration of Liz Sexton-Kennedy

Liz Sexton-Kennedy first came to Fermilab as an intern during her sophomore year at Rutgers University. 

She went on to a PhD program in physics at University of California, San Diego, then spent some time teaching at a community college there, but when she saw a chance to return to the lab, she took it. 

In 1988 she joined the Data Acquisition Group for the CDF experiment at Fermilab’s Tevatron particle collider. She rose through the ranks, and in April 2018 was named the lab’s Chief Information Officer.

Jim Daley of Symmetry spoke to Sexton-Kennedy about her experiences in STEM, her career at Fermilab, and a bit about herself.  

What was something that first got you interested in science?


I was a young, impressionable kid when I first saw [the 1977 short film] “Powers of Ten.” The concept that there were dimensions to the world that we couldn't see, or that there were things out there that we couldn’t understand because we can only see so many stars when we look up, the idea that the cosmos could be thought about in a whole, organic sort of way—all of that was new and fascinating to me when I was a kid.

I was the oldest of four kids, and my parents didn’t have time to tutor me, and so relative to a lot of my classmates when I started school, I was behind. But in sixth grade, I had one particular science and math teacher, Mr. Moore, who was very influential in my life. He made it cool to be good at math and science. 

When it came to the playground, I was always picked last. But when it came to the math contests, I was always picked first. It was a reversal of recognition. 

When I went to high school, I knew I wanted to be taking calculus by my senior year, so I talked my way into getting into the most advanced algebra class they offered. The class was self-paced. I finished the whole year in half a year.

Was that alienating, or empowering, or both?


I think it was alienating. There was a dimension of being a female there, because the instructor literally thought I was not understanding the material and that was why I was having trouble paying attention. Actually, I was just bored. 

After high school, you did an internship at Fermilab, right?


That was my second year of college. 

My first year of college, they placed me into a set of classes that weren’t very challenging for me. I had done a full year of college-level calculus when I was a senior in high school. 

I went to the head of the math department. He was very surprised at this young woman just standing up for herself and saying, “I don’t care if you don’t give me the credit, I want to be in this advanced class because this one is boring me to tears.” 

So they placed me in a more advanced physics class with a smaller class size and a teacher who knew how to challenge a class. So that was fun for me.

I took the sophomore year electronics class. I did well in that class, and the professor needed someone to come out to Fermilab because two of their graduate students were getting married to each other [and would both be out at the same time]. 

The internship gave me a taste of what this career would be like if I were to continue in this direction, so that made me think differently when I got to graduate school. By graduate school I was completely determined. 

It seems you were a determined person from a very young age.


From a very young age, but my determination in the early years was just to learn as much as I possibly could. Being paid to learn was a strange concept to me! 

Do you have thoughts on the kinds of barriers that are still presented to women and girls in STEM?


It’s definitely still there. I have three daughters; they’ve all encountered it. 

My husband was a genius, and they got some of his genius genes, and they grew up in a household where people were talking science at the dinner table all the time. But for whatever reason they were definitely discouraged in math. 

My oldest daughter was lucky to have a high school biology and chemistry teacher who really encouraged her, so she’s a doctor now. She’s a resident at UIC now. 

My middle daughter was much more interested in the human psyche, and she went into psychology. Now she’s in law school. 

Do you think there's a role for an institution like Fermilab in supporting young people who are facing barriers?


Yeah, I think there is, because certainly when I came here when I was 19, I was immersed in a group where I was treated as an equal. I was lucky because I landed in an experiment that had a high fraction of female scientists. In a collaboration of 20, I can name five or six women off the top of my head.

I think one of the things that Fermilab brings—or any big institution that is aware of these biases—is the idea of a meritocracy. People want to succeed in the sciences, and they want to bring in the best people to get them there. 

I'm not saying there aren't politics here, but in the end, the data and the cogent argument win in any dispute.

What developments are you excited about in high-energy physics computing?


I think for software and computing, we’ve been really successful over the years, especially in high-energy physics. The Large Hadron Collider experiments have needed a worldwide network of interconnecting centers that all cooperate and satisfy the needs of their high-data throughput users. We’ve managed to stay ahead of the curve, and when you’re in the thick of the battle you don’t realize how far you’ve come. 

Building on that success is exciting. There’s no way we can reach our science goals unless we can solve some of the challenges that are coming up. 

The physics driving the silicon chip manufacturing is reaching limits. There’s a physical limit that we're approaching with the materials we have, the leakage currents. 

People are talking about different technologies like quantum computing and neuromorphic computing, but both are 15 years out. Fermilab and other labs are looking at what you can do with mid-scale noisy quantum.   

Getting a qubit to operate like a computer seems impossible, but maybe that means we’re just making the wrong assumptions. Maybe you shouldn’t make it operate like a computer. Maybe the answer is: It will always be something that you have to design the problem for, and the role of traditional computers will still continue to be there forever. 

What’s interesting is that the nature of computing has to change in order for us to continue doing the science we've done in the past. That’s going to require a lot of human effort, and that’s kind of exciting, to marshal our forces to meet that challenge.

What hobbies do you enjoy?


I did ballet for over 35 years, and I hope to get back to it. I’ve been doing a lot of singing. I’m in a choir at church and I sing with the Fermilab choir every once in a while. I sang for an HEP-version of “The Monster Mash” with the choir for Symmetry in October.

Are there parallels between the challenges in ballet and your career in STEM?


I would say so. It takes a certain amount of putting up with the pain and perseverance in both.

What advice might you have for young people and young women in STEM?


I would say that perseverance is key, and don’t let anybody tell you that you are not worthy or that you have not the appropriate skills or talents to do something if you think you can do it. Have confidence in yourself and do it.

Retired equipment lives on in new physics experiments

Physicists often find thrifty, ingenious ways to reuse equipment and resources.

Move of ICARUS detector from Morris, IL to Fermilab site

What do you do with 800 square feet of scintillator from an old physics experiment? Cut it up and give it to high schools to make cosmic ray detectors, of course.

And what about an 800-ton magnet originally used to discover new particles? Send it off on a months-long journey via truck, train and ship halfway across the world to detect oscillating particles called neutrinos. 

It’s all part of the vast recycling network of the physics community, where decommissioned experimental equipment and data are reused, re-analyzed and repurposed, giving expensive materials and old tapes of data second or even third lives—often in settings vastly different from their original homes.

For physicists whose experiments can easily cost millions or even billions of dollars, such reuse is not just thrifty, it’s essential for building next-generation experiments.   

When experiments are shut down, “the vultures come knocking at your door,” jokes Jonathan Lewis, deputy head of the particle physics division at Department of Energy’s Fermi National Accelerator Laboratory. He was in charge of decommissioning the Collider Detector at Fermilab (CDF) experiment in 2011. “You try to get the word out, but people in the community know what experiments are being shut down. They start to look to see what’s available.”

Shipping magnets around the world

Take, for example, the UA1 experiment magnet. Originally built in 1979, it was part of a particle detector at CERN that discovered the W and Z bosons. After that experiment shut down in 1990, it was used in the NOMAD neutrino experiment from 1995 to 1998. But then it sat outside at CERN, rusting a bit and waiting for its next home, which would ultimately be the T2K neutrino experiment in Japan. 

“Even with the amount of work needed to refurbish it, and the cost of transporting it, it was still worthwhile to reuse it,” says Chang Kee Jung, US principal investigator for the experiment and professor at Stony Brook University. “Usually when you are using old equipment, it’s like driving a used car. The parts aren’t new, so it will break down more often, and you will have more maintenance costs. But magnets generally have much longer lifetimes than other devices, since they are rather simple equipment.”

In 2009, the magnet was dismantled, cleaned and polished. Most of it was then loaded up into 35 containers, which traveled by train to Antwerp before being loaded onto container ships bound for Japan. The magnet eventually reached the J-PARC facility north of Tokyo and became part of the T2K neutrino oscillation experiment. 

Magnet reuse is common—even magnets from MRI scanners have been reused in physics experiments—but their special transportation often makes headlines. In 1979, Argonne National Laboratory sent a 107-ton superconducting magnet to what is now called SLAC National Accelerator Laboratory. Jung recalls stories about local news stations reporting on its 20-day journey via a special tractor-trailer, which took up two lanes of interstate highway while traveling 25 miles per hour. The Muon g-2 experiment at Fermi National Accelerator Laboratory in Illinois uses a giant magnet transported 3200 miles by land and sea from its original home at Brookhaven National Laboratory in New York. (That trip even had its own hashtag: #bigmove.)

But magnets prove their worth. Even as the UA1 magnet nears its fifth decade, Jung imagines it still has a good decade worth of life left. “Second lives for equipment in physics are not unusual, but to have a third life like this is unusual,” he says. “This is probably the longest-used magnet.”

Absorbing an old experiment into a new one

Sometimes, entire detectors are absorbed from one experiment to another. That was the case with ICARUS, the first large-scale time projection liquid-argon neutrino detector. It started out at the Laboratori Nazionali del Gran Sasso in Italy to look for neutrino oscillations over a long baseline, then was transported to CERN for refurbishment and then to Fermilab in 2017. There, it will join the lab’s program to search for sterile neutrinos, which could help solve questions about the origin of our universe. The detector survived a complex journey, traveling thousands of miles via truck and barge. (Hashtag: #IcarusTrip.)

Physicist Angela Fava transferred labs along with the experiment. Fava worked with the detector in graduate school and is helping to install it at Fermilab as part of a trio of experiments in the Short-Baseline Neutrino program. In Italy, the detector found only a couple neutrino interactions per day; in its new role, it will likely detect that amount every minute. Fava says it is up for the challenge. 

“I thought it was amazing how the same detector can adapt to such different conditions of operation,” she says. “It gives you an idea of how flexible detection technology can actually be.”

ICARUS also reuses parts from other experiments, including plastic scintillators from the concluded MINOS experiment. 

Reusing mines, battleships

Physics experiments don’t just reuse their own equipment—they also often give second lives to non-scientific facilities and resources. Old mines, with their hollowed-out underground sites shielded from cosmic rays, have been the sites of countless physics experiments. The Homestake Mine in South Dakota houses several experiments, including the Majorana Demonstrator, LUX dark matter experiment, and the upcoming Deep Underground Neutrino Experiment. The Mozumi Mine in Japan has been home to many experiments, including the Super-Kamiokande, and a set of experiments (KamiokaNDE, KamLAND, and KamLAND-Zen) that have all re-used the same neutrino detector. 

Other resources have found new life in physics experiments: the Sudbury Neutrino Observatory in Canada, for example, once borrowed 1000 tons of heavy water from Canadian nuclear reactors to use in a neutrino detector. 

And the CDF experiment, which studied high energy proton-antiproton collisions at Fermilab’s Tevatron collider, was partially constructed using steel from decommissioned battleships. That experiment ultimately paid it forward by disassembling and sharing a long list of experimental equipment after it was shut down in 2011. Lewis can cite where everything went: phototubes to India, electronics to Italy, computer servers to South Korea. Here in the United States, Brookhaven National Laboratory and Jefferson Lab got hundreds of phototubes for nuclear physics experiments, and 1000 tons of the old battleship steel will be used as shielding for the Long-Baseline Neutrino Facility target.

The 800 square feet of scintillator was sent to QuarkNet, an educational program, to be used as cosmic ray detectors for high schools. 

“All that’s left is the magnet and a few detector pieces that are on display,” he says. “And a legacy of over 700 papers and lots of memories. In fact, people are still doing analysis on the data.”

Revisiting old data anew

Data can be analyzed and looked at anew for years to come. 

That’s the case for DZero, the other experiment on the Tevatron at Fermilab that ran from 1992 to 2011. In its heyday, the experiment revealed particles like the top quark. Though it shut down soon after the start of the Large Hadron Collider, scientists have data from about 10 billion events that still have a story to tell. Dozens of papers from that data have been published in the last six years.

“They are probably not Nobel Prize-winning measurements, but they are very important for understanding specific areas in particle physics,” says Dmitri Denisov, a distinguished scientist at Fermilab and spokesperson for the DZero experiment. For example, the data has been important in searching for exotic particles, a field that did not become popular until after the Tevatron shut down. 

From experiment to education

Perhaps one of the most inspirational ways for experiments to live second lives is as educational displays. The DZero experiment was left mostly intact, and now thousands of visitors per year can stand right next to a four-story particle detector Fermilab scientists used to discover the top quark. 

Denisov sometimes leads tours of high school students through the control room, where computer screens still look as though they are taking data. “You can see how excited the students are,” he says. “It shows them the joy of complex particle physics experiments. That’s probably the best second life that none of us expected.”