symmetry

The personal side of science

The Story Collider visits Fermilab to highlight true stories from scientists.

The storytellers of Story Collider gather on stage

How do snails, shooting stars and science fiction books all relate to physics? They’re just a few examples of where Fermilab scientists and other guest speakers drew inspiration for a recent edition of The Story Collider.

“Stories underlie a lot of what we do as scientists, whether we know it or not,” says Cindy Joe, a Fermilab engineering physicist. “We have a lot of beautiful stories, both science-related and not, but as scientists we sometimes pretend we’re above the emotional part of what we do. But it’s okay for emotion to underlie it.”

The Story Collider features storytellers in podcasts and live shows across the country—everyone from comedians and doctors to poets and physicists. It aspires to humanize its speakers and show that at the basis of every profession, including the sciences, is a person with hopes, dreams, desires and struggles.

On May 12, The Story Collider visited Fermilab with hosts Erin Barker and Kellie Vinal to explore some personal stories from people affiliated with lab. It was the culmination of the spring season of the Fermilab Arts and Lecture Series, which organizes and hosts events like concerts, theater productions and public lectures at the lab.

The evening saw both laughter and tears. Joe told the story of her pet snail who helped her through difficult times at the beginning of her physics career, when she often felt overlooked and ignored. But caring for a small, often overlooked and non-traditional pet helped Joe realize her worth as a person and a scientist.

“I realized that my core belief that every single person had fundamental, inherent value should maybe also apply to myself,” she said. “That my different perspective was important. That my experiences were real. That my contributions were good. That I deserved no less gentle kindness and consideration than anyone else. And maybe I should treat myself like it.”

Don Lincoln, Fermilab senior scientist and book author, told the audience about an accomplishment he is especially proud of: inspiring a young woman to pursue the sciences through his writing. He emphasized that writing popular science books for a general audience is a crucial method of inspiring young scientists.

“There was someone out there— someone who had the ability and passion to learn but didn’t even know that a career in physics existed,” he said.

Fermilab scientist emeritus Mike Albrow painted a picture of the night sky for his audience. The same night sky stirred him as both a child and adult, always creating, “a feeling of being all alone in the vast emptiness of it all.” He told the audience how much of a detriment light pollution was to the night sky and for kids (and adults) who wanted to look at the stars.

Visual artist and first-ever Fermilab artist-in-residence Lindsay Olson walked the audience through intermingling science and art—and how she fell in love with science in the middle of a waste water treatment plant. At Fermilab, despite feeling intimidated by high-energy physics, she relied on her curiosity to explore and then show through her art that you don’t need a PhD to be fascinated by physics.

Finally, Fermilab senior scientist Herman White described when a small and coincidental connection—his roots in Alabama—became a way for him to connect to people and share his science with them.

“Especially now, it’s incredibly important to connect the public to science and change their perception of it,” White says. “We need to relate to people on a human level.”

Joe notes that many scientists aren’t used to telling stories, but their stories are an opportunity both to convey the value of science and create relationships with people outside of the field. She highlights that science is part of everyone’s life, no matter where they come from or what they do for a living.

“The underlying theme is that science is human," she says. "We can all tell stories about science, no matter its role in our lives, by sharing our feelings, thoughts, and background. And our stories as scientists are really just our stories as humans.”

The Story Collider at Fermilab

Video of The Story Collider at Fermilab
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Five (more) fascinating facts about DUNE

Engineering the incredible, dependable, shrinkable Deep Underground Neutrino Experiment.

Supernova

The Deep Underground Neutrino Experiment, designed to solve mysteries about tiny particles called neutrinos, is growing by the day. More than 1000 scientists from over 30 countries are now collaborating on the project. Construction of prototype detectors is well underway.

Engineers are getting ready to carve out space for the mammoth particle detector a mile below ground.

The international project is hosted by the Department of Energy’s Fermi National Accelerator Laboratory outside of Chicago—and it has people cracking engineering puzzles all around the globe. Here are five incredible engineering and design feats related to building the biggest liquid-argon neutrino experiment in the world.

1. The DUNE detector modules can (and will) shrink by about half a foot (16.5 centimeters) when filled with liquid argon.

The DUNE detector modules can (and will) shrink by about half a foot (16.5 centimeters) when filled with liquid argon.

Artwork by Sandbox Studio, Chicago with Ana Kova

Each of the large DUNE detector modules in South Dakota will be about 175 feet (58 meters) long, but everything has to be able to comfortably shrink when chilled to negative 300 degrees Fahrenheit (negative 184 degrees Celsius). The exterior box that holds all of cold material and detector components, also known as the cryostat, will survive thanks to something akin to origami. It will be made of square panels with folds on all sides, creating raised bumps or corrugations around each square. As DUNE cools by hundreds of degrees to liquid argon temperatures, the vessel can actually stay the same size because of those folds; the corrugation provides extra material that can spread out as the flat areas shrink. But inside, the components will be on the move. Many of the major detector components within the cryostat will be attached to the ceiling with a dynamic suspension system that allows them to move up to half a foot as they chill.

2. Researchers must engineer a new kind of target to withstand the barrage of particles it will take to make the world’s most intense high-energy neutrino beam for DUNE.

Researchers must engineer a new kind of target to withstand the barrage of particles

Artwork by Sandbox Studio, Chicago with Ana Kova

Targets are the material that a proton beam interacts with to produce neutrinos. The Fermilab accelerator complex is being upgraded with a new superconducting linear collider at the start of the accelerator chain to produce an even more powerful proton beam for DUNE—and that means engineers need a more robust target that can stand up to the intense onslaught of particles. Current neutrino beamlines at Fermilab use different targets—one with meter-long rows of water-cooled graphite tiles called fins, another with air-cooled beryllium. But engineers are working on a new helium-gas-cooled cylindrical rod target to meet the higher intensity. How intense is it? The new accelerator chain’s beam power will be delivered in short pulses with an instantaneous power of about 150 gigawatts, equivalent to powering 15 billion 100-watt lightbulbs at the same time for a fraction of a second.

3. A single DUNE test detector component requires almost 15 miles of wire.

A single DUNE test detector component requires almost 15 miles of wire.

Artwork by Sandbox Studio, Chicago with Ana Kova

Before scientists start building the liquid-argon neutrino detectors a mile under the surface in South Dakota, they want to be sure their technology is going to work as expected. In a ProtoDUNE test detector being constructed at CERN, they are testing pieces called “anode plane assemblies.” Each of these panels is made of almost 15 miles (24 kilometers) of precisely tensioned wire that has to lay flat—within a few millimeters. The wire is a mere 150 microns thick—about the width of two hairs. This panel of wires will attract and detect particles produced when neutrinos interact with the liquid argon in the detector—and hundreds will be needed for DUNE.

4. DUNE will be the highest voltage liquid-argon experiment in the world.

DUNE will be the highest voltage liquid-argon experiment in the world.

Artwork by Sandbox Studio, Chicago with Ana Kova

The four DUNE far detector modules, which will sit a mile underground at the Sanford Underground Research Facility in South Dakota, will use electrical components called field cages. These will capture particle tracks set in motion by a neutrino interaction. The different modules will feature different field cage designs, one of which has a target voltage of around 180,000 volts—about 1500 times as much voltage as you’d find in your kitchen toaster—while the other design is planning for 600,000 volts. This is much more than was produced by previous liquid-argon experiments like MicroBooNE and ICARUS (now both part of Fermilab’s short-baseline neutrino program), which typically operate between 70,000 and 80,000 volts. Building such a high-voltage experiment requires design creativity. Even “simple” things, from protecting against power surges and designing feedthroughs—the fancy plugs that bring this high voltage from the power supply to the detector—have to be carefully considered and, in some cases, built from scratch.

5. Researchers expect DUNE’s data system to catch about 10 neutrinos per day—but must be able to catch thousands in seconds if a star goes supernova nearby.

Researchers expect DUNE’s data system to catch about 10 neutrinos per day—but must be able to catch thousands in seconds

Artwork by Sandbox Studio, Chicago with Ana Kova

A supernova is a giant explosion that occurs when a star collapses in on itself. Most people imagine the dramatic burst of light and heat, but much of the energy (around 99 percent) is carried away by neutrinos that can then be recorded here on Earth in neutrino detectors. On an average day, DUNE will typically see a handful of neutrinos coming from the world’s most intense high-energy neutrino beam—around 10 per day at the start of the experiment. Because neutrinos interact very rarely with other matter; scientists must send trillions to their distant detectors to catch even a few. But so many neutrinos are released by a supernova that the detector could see several thousand neutrinos within seconds if a star explodes in our Milky Way galaxy. A dedicated group within DUNE is working on how best to rapidly record the enormous amount of data from a supernova, which will be about 50 terabytes in ten seconds.

In case you missed it, here are the first “Five fascinating facts about DUNE.” 

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Inside the Large Hadron Collider

If two protons collide at 99.9999991 percent the speed of light, do they make a sound?

a mosquito in amber, two apples colliding, an ear, a hard hat with the CERN logo, Einsteins head, spilled coffee

What is it like inside the LHC? Symmetry tackles some unconventional questions about the world’s highest energy particle accelerator.

The LHC accelerates beams of particles, usually protons, around and around a 17-mile ring until they reach 99.9999991 percent the speed of light. If you could watch this happening, what would you see?

A:

The LHC ring is actually made up of both straight and curved sections. If you were watching protons fly through one of the straight sections, it would be totally dark. But as the protons pass through the LHC’s curved sections, the particles emit synchrotron radiation in the form of photons. 

At low energies, the photons are generally in the infrared, but at a couple of particular points in the ring, special magnets called undulators cause visible light to be emitted.

During the acceleration process (the so-called ramp), the energy of protons increases, and the energy of the photons they emit also increases. Once the protons reach their maximum energy, most of the photons are in the ultraviolet range. If you looked in the beam pipe at that point, you wouldn’t be able to see anything, but you would get a pretty good sunburn.

What are space and time like for an LHC proton traveling at 99.9999991 percent the speed of light?

A:

Two strange but well-known effects of moving at speeds that are a signification fraction of the speed of light are time dilation (moving clocks tick slowly) and length contraction. 

Time dilation tells us that the time experienced by a moving observer is shorter than time experienced by a stationary observer. Length contraction tells us that a stationary observer will observe a moving object to be shorter in length than it would be if it were at rest.

To a proton travelling very close to the speed of light, time would appear to be passing normally. Proton time would seem strange only to an observer outside the LHC, for whom 1 second for the proton would appear to last about 2 hours. 

What would seem strange from the proton’s point of view would be length. To the proton screaming around the LHC, the 17-mile circumference of the accelerator would appear to take up just about 13 feet. 

Speaking of screaming, do the particles going around the LHC generate any sound? If you stuck your ear up against the beam pipe and listened to the protons colliding, what would you hear?

A:

The particles in the LHC are travelling in a very good vacuum, and there’s no sound in a vacuum. But there is a recording of the proton beam smashing into the graphite core of the beam dump, where particles are sent when scientists want to stop circulating them in the accelerator, and they do land with a bang.

How powerful are the collisions in the LHC?

A:

The LHC collides two beams of protons at a combined energy of 13 TeV, or 13 trillion electronvolts. An electronvolt is a unit of energy, like a calorie or a joule. Electronvolts are used when to talk about the energy of motion of really small things such as particles and atoms. 

One photon of infrared light has about 1 electronvolt of energy. A flying mosquito has about 4 trillion electronvolts of energy.

Knowing that, you might think 13 trillion electronvolts isn’t much. But what’s impressive is not so much the energy as the energy density: The energy of about 3 flying mosquitos is crammed into a space about 1 trillion times smaller across than one annoying insect. Nowhere else on Earth can we concentrate energy that much.

What if, instead of colliding protons at 13 TeV, you could collide apples at the same speed?

A:

If you could do that, you’d get some real specialty apple juice—and a huge amount of energy: close to 1 x 1020Joules. That’s about the same order of magnitude as the energy that was released when a meteor hit Canada 39 million years ago. The impact of that collision resulted in the Haughton Crater, which is about 14 miles (23 kilometers) across.

The LHC can’t accelerate an apple, though. Right now, it can accelerate about 600 trillion protons at a time. That may sound like a lot, but altogether, it adds up to about 1 nanogram of matter—roughly the same mass as a single human cell.

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Leveling the playing field

Conferences for Undergraduate Women in Physics aims to encourage more women and gender minorities to pursue careers in physics and improve diversity in the field.

Many CUWiP programs include a poster session where students have the opportunity to describe research

Nicole Pfiester, an engineering grad student at Tufts University, says she has been interested in physics since she was a child. She says she loves learning how things work, and physics provides a foundation for doing just that. 

But when Pfiester began pursuing a degree in physics as an undergraduate at Purdue University in 2006, she had a hard time feeling like she belonged in the male-dominated field. 

“In a class of about 30 physics students,” she says, “I think two of us were women. I just always stood out. I was kind of shy back then and much more inclined to open up to other women than I was to men, especially in study groups. Not being around people I could relate to, while it didn't make things impossible, definitely made things more difficult.”

In 2008, two years into her undergraduate career, Pfiester attended a conference at the University of Michigan that was designed to address this very issue. The meeting was part of the Conferences for Undergraduate Women in Physics, or CUWiP, a collection of annual three-day regional conferences to give undergraduate women a sense of belonging and motivate them to continue in the field.

Pfiester says it was amazing to see so many female physicists in the same room and to learn that they had all gone through similar experiences. It inspired her and the other students she was with to start their own Women in Physics chapter at Purdue. Since then, the school has hosted two separate CUWiP events, in 2011 and 2015.

“Just seeing that there are other people like you doing what it is you want to do is really powerful,” Pfiester says. “It can really help you get through some difficult moments where it’s really easy, especially in college, to feel like you don’t belong. When you see other people experiencing the same struggles and, even more importantly, you see role models who look and talk like you, you realize that this is something you can do, too. I always left those conferences really energized and ready to get back into it.” 

CUWiP was founded in 2006 when two graduate students at the University of Southern California realized that only 21 percent of US undergraduates in physics were women, a percentage that dropped even further in physics with career progression. In the 12 years since then, the percentage of undergraduate physics degrees going to women in the US has not grown, but CUWiP has. What began as one conference with 27 attendees has developed into a string of conferences held at sites across the country, as well as in Canada and the UK, with more than 1500 attendees per year. Since the American Physical Society took the conference under its umbrella in 2012, the number of participants has continued to grow every year. 

The conferences are supported by the National Science Foundation, the Department of Energy and the host institutions. Most student transportation to the conferences is almost covered by the students’ home institutions, and APS provides extensive administrative support. In addition, local organizing committees contribute a significant volunteer effort.

“We want to provide women, gender minorities and anyone who attends the conference access to information and resources that are going to help them continue in science careers,” says Pearl Sandick, a dark matter physicist at the University of Utah and chair of the National Organizing Committee for CUWiP.

Some of the goals of the conference, Sandick says, are to make sure people leave with a greater sense of community, identify themselves more as physicists, become more aware of gender issues in physics, and feel valued and respected in their field. They accomplish this through workshops and panels featuring accomplished female physicists in a broad range of professions.

Before the beginning of the shared video keynote talk, attendees at each CUWiP site cheer and wave on video.

Before the beginning of the shared video keynote talk, attendees at each CUWiP site cheer and wave on video. This gives a sense of the national scale of the conference and the huge number of people involved.

Courtesy of Columbia University
Students attending the conference had the opportunity to meet and network with women with successful careers in physics.

Students attending the conference have the opportunity to meet and network with women with successful careers in physics.

Courtesy of Columbia University
Many CUWiP programs include a poster session where students have the opportunity to describe research

Many CUWiP programs include a poster session where students have the opportunity to describe research in which they have been engaged, often through summer research programs.

Photo by Eleanor Starkman
Ava Ghadimi, a math and physics graduate student from CUNY Baccalaureate for Unique and Interdisciplinary Studies

Ava Ghadimi, a math and physics graduate student from CUNY Baccalaureate for Unique and Interdisciplinary Studies, presents her research on "Searching for sources of astrophysical neutrinos: a multi-messenger approach with VERITAS" at the Princeton poster session.

Photo by Eleanor Starkman
Jazlin McKinney of Texas Southern University discusses her research topic, “African American, Hispanic and Native American Women

Jazlin McKinney of Texas Southern University discusses her research topic, “African American, Hispanic and Native American Women Students in STEM: Recommendations for Increasing the Bachelors, Masters and PhD Graduates,” with another participant at the CUWiP at the University of Kansas.

Photo by Matt Rennells, Shedluv Photography
Zoe de Beurs of the University of Texas at Austin describes her research project

Zoe de Beurs of the University of Texas at Austin describes her research project, “Neutral Atom Focusing Using a Pulsed Electromagnetic Lens.“ Zoe was one of three students awarded the top poster presentation prize at the CUWiP at the University of Kansas.

Photo by Matt Rennells, Shedluv Photography
Madison physics and applied math major Arianna Ranabhat presents her poster on “Geocoronal Hydrogen Observations”

University of Wisconsin, Madison physics and applied math major Arianna Ranabhat presents her poster on “Geocoronal Hydrogen Observations” at the Iowa State University CUWiP.

Photo by Massimo Marengo/Iowa State University
Alynie Walter is presenting her research on

Alynie Walter, an applied physics and mathematics major at St. Catherine University in Minnesota, presents her research on "Calibration of Temperature Sensors in Preparation for the 2017 Total Solar Eclipse” during the CUWiP at Iowa State poster session.

Photo by Massimo Marengo/Iowa State University
Alyssa Miller, Iowa State University alumna and a member of Fermilab staff in the Beam Division

Alyssa Miller, Iowa State University alumna and a member of Fermilab staff in the Beam Division, brainstorms about careers that use a physics degree.

Photo by Massimo Marengo/Iowa State University
At the 2017 CUWiP at Princeton, attendees had the opportunity to touch a Van de Graaff generator

At the 2017 CUWiP at Princeton, attendees had the opportunity to touch a Van de Graaff generator, which produces static electricity.

Photo by Eleanor Starkman
At Princeton, attendees had the opportunity to participate in CUWiP+ workshops

At Princeton, attendees had the opportunity to participate in CUWiP+ workshops, in which they could participate in hands-on demonstrations and perform introductory laboratories. In one of the workshops, students had the opportunity to construct simple plasma apparatus.

Photo by Eleanor Starkman
The conferences include workshops and panels featuring accomplished female physicists in a broad range of professions.

The conferences include workshops and panels featuring accomplished female physicists in a broad range of professions.

Photo by Eleanor Starkman
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“Often students come to the conference and are very discouraged,” says past chair Daniela Bortoletto, a high-energy physicist at the University of Oxford who organizes CUWiP in the UK. “But then they meet these extremely accomplished scientists who tell the stories of their lives, and they learn that everybody struggles at different steps, everybody gets discouraged at some point, and there are ups and downs in everyone’s careers. I think it’s valuable to see that. The students walk out of the conference with a lot more confidence.”

Through CUWiP, the organizers hope to equip students to make informed decisions about their education and expose them to the kinds of career opportunities that are open to them as physics majors, whether it means going to grad school or going into industry or science policy.

“Not every student in physics is aware that physicists do all kinds of things,” says Kate Scholberg, a neutrino physicist at Duke and past chair. “Everybody who has been a physics undergrad gets the question, ‘What are you going to do with that?’ We want to show students there’s a lot more out there than grad school and help them expand their professional networks.”

They also reach back to try to make conditions better for the next generations of physicists. 

At the 2018 conference, Hope Marks, now a senior at Utah State University majoring in physics, participated in a workshop in which she wrote a letter to her high school physics teacher, who she says really sparked her interest in the field. 

“I really liked the experiments we did and talking about some of the modern discoveries of physics,” she says. “I loved how physics allows us to explore the world from particles even smaller than atoms to literally the entire universe.”

The workshop was meant to encourage high school science and math teachers to support women in their classes.

One of the challenges to organizing the conferences, says Pat Burchat, an observational cosmologist at Stanford and past chair, is to build experiences that are engaging and accessible for undergraduate women.

“The tendency of organizers is naturally to think about the kinds of conferences they go to,” says Burchat says, “which usually consist of a bunch of research talks, often full of people sitting passively listening to someone talk. We want to make sure CUWiP consists of a lot of interactive sessions and workshops to keep the students engaged.”

Candace Bryan, a physics major at the University of Utah who has wanted to be an astronomer since elementary school, says one of the most encouraging parts of the conference was learning about imposter syndrome, which occurs when someone believes that they have made it to where they are only by chance and don’t feel deserving of their achievements. 

“Science can be such an intimidating field,” she says. “It was the first time I’d ever heard that phrase, and it was really freeing to hear about it and know that so many others felt the same way. Every single person in that room raised their hand when they asked, ‘Who here has experienced imposter syndrome?’ That was really powerful. It helped me to try to move past that and improve awareness.”

Women feeling imposter syndrome sometimes interpret their struggles as a sign that they don’t belong in physics, Bryan says. 

“It’s important to support women in physics and make sure they know there are other women out there who are struggling with the same things,” she says.

“It was really inspirational for everyone to see how far they had come and receive encouragement to keep going. It was really nice to have that feeling after conference of ‘I can go to that class and kill it,’ or ‘I can take that test and not feel like I’m going to fail.’ And if you do fail, it’s OK, because everyone else has at some point. The important thing is to keep going.”

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Construction begins on SuperCDMS SNOLAB

The SuperCDMS SNOLAB project is expanding the hunt for dark matter to particles with properties not accessible to any other experiment.

Photo of one of the experiment's detector crystals within its protective copper housing

The US Department of Energy has approved funding and start of construction for the SuperCDMS SNOLAB experiment, which will begin operations in the early 2020s to hunt for hypothetical dark matter particles called weakly interacting massive particles, or WIMPs. The experiment will be at least 50 times more sensitive than its predecessor, exploring WIMP properties that can’t be probed by other experiments and giving researchers a powerful new tool to understand one of the biggest mysteries of modern physics.

SLAC National Accelerator Laboratory is managing the construction project for the international SuperCDMS collaboration of 111 members from 26 institutions, which is preparing to do research with the experiment.

"Understanding dark matter is one of the hottest research topics—at SLAC and around the world," says JoAnne Hewett, head of SLAC’s Fundamental Physics Directorate and the lab’s chief research officer. "We're excited to lead the project and work with our partners to build this next-generation dark matter experiment."

With the DOE approvals known as Critical Decisions 2 and 3, the researchers can now build the experiment. The DOE Office of Science will contribute $19 million to the effort, joining forces with the National Science Foundation, which will contribute $12 million, and the Canada Foundation for Innovation, which will contribute $3 million.

“Our experiment will be the world’s most sensitive for relatively light WIMPs—in a mass range from a fraction of the proton mass to about 10 proton masses,” says Richard Partridge, head of the SuperCDMS group at the Kavli Institute for Particle Astrophysics and Cosmology, a joint institute of SLAC and Stanford University. “This unparalleled sensitivity will create exciting opportunities to explore new territory in dark matter research.”

An ultracold search 6800 feet underground

Scientists know that visible matter in the universe accounts for only 15 percent of all matter. The rest is a mysterious substance called dark matter. Due to its gravitational pull on regular matter, dark matter is a key driver for the evolution of the universe, affecting the formation of galaxies like our Milky Way. It therefore is fundamental to our very own existence.

But scientists have yet to find out what dark matter is made of. They believe it could be composed of dark matter particles, and WIMPs are top contenders. If these particles exist, they would barely interact with their environment and fly right through regular matter untouched. However, every so often, they could collide with an atom of our visible world, and dark matter researchers are looking for these rare interactions.

In the SuperCDMS SNOLAB experiment, the search will be done using silicon and germanium crystals, in which the collisions would trigger tiny vibrations. However, to measure the atomic jiggles, the crystals need to be cooled to less than minus 459.6 degrees Fahrenheit—a fraction of a degree above absolute zero temperature. These ultracold conditions give the experiment its name: Cryogenic Dark Matter Search, or CDMS. The prefix “Super” indicates an increased sensitivity compared to previous versions of the experiment.

The collisions would also produce pairs of electrons and electron deficiencies that move through the crystals, triggering additional atomic vibrations that amplify the signal from the dark matter collision. The experiment will be able to measure these “fingerprints” left by dark matter with sophisticated superconducting electronics.

The experiment will be assembled and operated at the Canadian laboratory SNOLAB—6,800 feet underground inside a nickel mine near the city of Sudbury. It’s the deepest underground laboratory in North America. There it will be protected from high-energy particles called cosmic radiation, which can create unwanted background signals.

“SNOLAB is excited to welcome the SuperCDMS SNOLAB collaboration to the underground lab,” says Kerry Loken, SNOLAB project manager. “We look forward to a great partnership and to supporting this world-leading science.”

Over the past months, a detector prototype has been successfully tested at SLAC.

“These tests were an important demonstration that we’re able to build the actual detector with high enough energy resolution, as well as detector electronics with low enough noise to accomplish our research goals,” says KIPAC’s Paul Brink, who oversees the detector fabrication at Stanford.

Together with seven other collaborating institutions, SLAC will provide the experiment’s centerpiece of four detector towers, each containing six crystals in the shape of oversized hockey pucks. The first tower could be sent to SNOLAB by the end of 2018.

“The detector towers are the most technologically challenging part of the experiment, pushing the frontiers of our understanding of low-temperature devices and superconducting readout,” says Bernard Sadoulet, a collaborator from the University of California, Berkeley.

A strong collaboration for extraordinary science

In addition to SLAC, two other national labs are involved in the project. Fermi National Accelerator Laboratory is working on the experiment’s intricate shielding and cryogenics infrastructure, and Pacific Northwest National Laboratory is helping understand background signals in the experiment, a major challenge for the detection of faint WIMP signals.

A number of US and Canadian universities also play key roles in the experiment, working on tasks ranging from detector fabrication and testing to data analysis and simulation. The largest international contribution comes from Canada and includes the research infrastructure at SNOLAB.

“We’re fortunate to have a close-knit network of strong collaboration partners, which is crucial for our success,” says KIPAC’s Blas Cabrera, who directed the project through the CD-2/3 approval milestone. “The same is true for the outstanding support we’re receiving from the funding agencies in the US and Canada.”

Fermilab’s Dan Bauer, spokesperson of the SuperCDMS collaboration says, “Together we’re now ready to build an experiment that will search for dark matter particles that interact with normal matter in an entirely new region.”

SuperCDMS SNOLAB will be the latest in a series of increasingly sensitive dark matter experiments. The most recent version, located at the Soudan Mine in Minnesota, completed operations in 2015.

”The project has incorporated lessons learned from previous CDMS experiments to significantly improve the experimental infrastructure and detector designs for the experiment,” says SLAC’s Ken Fouts, project manager for SuperCDMS SNOLAB. “The combination of design improvements, the deep location and the infrastructure support provided by SNOLAB will allow the experiment to reach its full potential in the search for low-mass dark matter.”

Editor's note: A version of this article was originally published as a SLAC press release.

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Q&A: SLAC’s archivist closes a chapter

Approaching retirement, Jean Deken describes what it’s like to preserve decades of collective scientific memory at a national lab.

Jean Deken holding abstract
Jean Deken portrait

Jean Deken was hired at SLAC National Accelerator Laboratory for a daunting task—to chronicle the history and culture of the decades-old lab and its reseachers as the fast pace of its science continued. She became SLAC’s archivist on April 15, 1996. 

Deken is retiring after more than 20 years at the lab. In this Q&A, she discusses big changes in physics, the challenges that archivists face, and her most surprising finds.

What was it like when you first arrived at the lab?

JD

At the time, I remember feeling overwhelmed because the archives were unstaffed for more than a year. When I arrived, I couldn’t fully open the door to my office because there were so many boxes that had been stacked there. Gradually, I unearthed the desk, chair, computer and phone. 

BaBar was ramping up, which was the big experiment at the time that was exploring antimatter, the interactions of quarks and leptons, and new physics. The physicists wanted to know what do with their records, because they knew they were making history. 

The Superconducting Super Collider in Texas had recently been canceled, and the contents of their library were distributed to other labs. SLAC received pallets and pallets of microfilmed physics journals. I worked with the library to figure out what to do with all them. 

There was a pent-up need to get information into the archives. Because I was so busy, I sometimes didn’t have time to eat until the evenings.

How did you first get involved with archiving science?

JD

I was looking for a part-time job between undergraduate and graduate school, and I began working at the Missouri Botanical Garden as a cataloguing assistant. There was a stack of stuff in the corner of the cataloguing department that no one wanted to go near. I started digging into it and found manuscripts from the early days of the botanical garden by the founder and his scientific advisor. 

I became fascinated by these documents, and the director of the library told me, “What you’re interested in, that’s called archiving.”

So I acquired some archival procedure manuals and started working on arranging these papers. Soon, I began fielding all the questions the library got about the history of the garden.

How did you make your way to SLAC?

JD

For many years, I worked at the National Archives in St. Louis, Missouri. While I was there, the Archives decided to celebrate the 50th anniversary of World War II in a really big way. In St. Louis we made a traveling exhibit that focused on war efforts of civilian and military personnel. I took the lead on looking into the civilian war effort, which included Women Air Service Pilots (WASPs) and scientists working in research and development, including those whose work contributed to the Manhattan Project. 

Working on the exhibit, I became increasingly aware of the importance of preserving scientific perspectives as we uncovered stories hidden in personnel records. I thought, “Why did I never hear about this before?” It’s partly because the records of these efforts were scattered. That got me interested in learning more about archiving the records of government science.

At the same time, contemporary records were going electronic, in a big way. I remember thinking, “This changes everything.” I decided that the best solution for an archivist would be to be as close as possible to the records as they’re being created, to be embedded in an organization while working on how to preserve this information. Wanting to be an embedded archivist, and wanting to work with the records of government science, I applied for the archivist job at SLAC, and they offered it to me the day of my interview.

What does it mean to process an archival collection, exactly?

JD

For paper collections, you process the documents to try and maintain the original order. The contextual information gives insight into the personality and intellect of the records’ creator. But there’s often disorder in storage and therefore in reconstructing the original order. 

The first stage is to create an inventory of every box and folder and tag each item to see connections with institutions and topics. This is how to make sure the contents are roughly chronological and sorted by topic. 

Next I would make sure the documents were stored in acid-free boxes and file folders. At this point, I would also look for contaminants, such as acidic paper, insects, old tape and rusty staples. For these damaged items, I would sometimes simply remove the contaminants, and other times [for more damaged items] photocopy the documents on acid-free paper and store the original in a protective sleeve. 

In one collection, I found an envelope full of cash. I went back to the scientist and said, “I’ve never gotten a tip before.” He had been collecting meal money for a conference and had lost track of the envelope. 

After this physical work is done, I would create an electronic guide to the contents. We have also digitized some of the hardcopy archival materials when requested, and those copies are kept in a digital repository. We have just begun to dip our toes into archiving the lab’s digital materials, starting with photographs. The type of digital storage we are using is really an interim fix.

Speaking of the discipline, what are some of the challenges archivists face?

JD

I’ve been concerned about electronic records for decades now. The problem with digital records is that no one’s figured out how to make them last. This is still true, and it’s something archival science needs to address as a field. There are quite a few questions we’re asking ourselves: What data and records are worth preserving? How long should they be saved? Who will save them? And who gets access?

One of my own future efforts in the field—I’ll keep busy during retirement—has to do with data archiving. With data, there’s such a vast amount of information, and each scientific discipline has different protocols. At international and national labs such as SLAC, many of the scientists come from elsewhere, and there are various agreements and regulations about responsibilities towards data and records. I’m working on proposing policies for these varied situations using SLAC datasets as a test case. 

Was it challenging to learn enough about the science to preserve it well?

JD

During the interview for the job, I asked, “You know I don’t have a physics background, why are you interested in me?” The interviewers told me, “We can teach you the physics that you need to know, and we also consider it part of our job to be able to explain physics.” But they told me they needed me to figure out the government regulations that relate to archives. 

When I started, I bought children’s books about physics, listened and asked a lot questions.

What have you learned about scientists themselves?

JD

It surprised me that these absolutely brilliant scientists were actually down-to-earth and approachable. The experimentalists, for example, would test you to make sure you knew your stuff, but then they considered you a member of their team. The researchers are used to multidisciplinary teams and needed to know that you could pull your own weight. 

I was also accustomed to a corporate government setting, and the environment at the lab was totally different. At first, I could not dress down enough to fit in. It was a funny, unexpected cultural shift.

How has the lab changed, from your perspective?

JD

The place has changed completely. When I started, SLAC was a single-purpose lab—focusing on high-energy physics. Later, it became a multipurpose laboratory and expanded into many other research areas. 

In the 1990s, SLAC was mature in the field of high-energy physics. The leaders of the lab had a sense that we had a history that needed to be preserved.

That generation has moved on, and with the shift in scientific focus, everything is new enough that there’s a different sense of history. Right now, we are running full tilt to get research programs set up, and that’s where a lot of the attention is aimed. I often have to say to the scientists, “Remember, you’re doing something that’s historic.”

What are some of the projects you’re most proud of?

JD

During my interview, several people mentioned SLAC’s involvement with the early web. 

SLAC has the oldest web pages still in existence. Even though Tim Berners-Lee at CERN created the first website, the original code wasn’t preserved. It has to do with a quirk of HTML—when you overwrite the code, it disappears. At SLAC, Louise Addis and Joan Winters had the foresight to understand this from almost the beginning, and they saved the original HTML pages from the first North American website. So, I was able to deposit those pages into the Stanford Web Archives when it was established a few years ago.

I was also a co-author of [SLAC Founding Director] Pief Panofsky’s memoir, which I edited. I like to tell people that his first language wasn’t German; it was physics. I really had to pull the story out of him to get the full flavor of what he wanted to say, but it was a lot of fun. 

Overall, I’m really proud of the SLAC archives. It’s a robust and well-respected program with minimal resources. And it’s been a whole lot of fun. There’s nothing I’d rather have done.

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First collisions at Belle II

The Japan-based experiment is one step closer to answering mystifying questions about antimatter.

Dozens of researchers celebrate in the control room after first collisions.

For the first time, the SuperKEKB collider at the KEK laboratory in Tsukuba, Japan, is smashing together particles at the heart of a giant detector called Belle II.

“These first collisions represent a moment that all of us at Belle II have been looking forward to for a long time,” says Elisabetta Prencipe, a scientist at the German research center Forschungszentrum Juelich who works on particle tracking software and statistical analyses for Belle II. “It’s a step forward to opening a new door to the universe and our understanding of it.”

The project looks for potential differences between matter and its mirror-world twin, antimatter, to figure out why our universe is dominated by just one of the pair. The experiment has been seven years in the making.

During construction of the Belle II detector, the SuperKEKB accelerator was recommissioned to increase the number of particle collisions, a measure called its luminosity. Even now, the accelerator is preparing for the second part of this upgrade, which will take place in stages over the next 10 years. The upgrade will more tightly focus the beams and solidify SuperKEKB’s position as the highest-luminosity accelerator in the world.

On March 21, SuperKEKB successfully stored an electron beam in the main ring, and on March 31 it stored a beam of positrons, the electron’s antimatter counterparts. With the two colliding beams in place, Belle II saw its first successful collisions today.

Pink and blue swirls radiate out from a black center: the first particle collisions seen by the Belle II detector.
KEK/Belle II

The beauty of quarks

Scientists predict that antimatter and matter should have been created in equal amounts during the hot early stages of the big bang that formed our universe. When matter and antimatter meet, they annihilate in a burst of energy. Yet despite their presumed equal ratio, matter has clearly won the fight, and now makes up everything we see around us. It is this confounding mystery that Belle II seeks to unravel.

Belle II’s beauty lies in its ability to detect unimaginably minute debris from high-energy collisions between electrons and positrons—particles so small they aren’t made up of anything else. In this debris, scientists look for physics beyond what they currently know by comparing particles’ properties to their predictions. The detector is especially sensitive to how other fundamental particles called quarks decay. It can closely study both quark properties and the structure of hadrons: particles made of multiple quarks bound together tightly.

At Belle II’s core, electrons and positrons collide at a high enough energy to create B-mesons, particles made of one matter and one antimatter quark. Scientists are particularly interested bottom quarks, also known as beauty quarks.

Bottom quarks are produced along with charm quarks at the center of Belle II. Both are heftier cousins of up and down quarks, which make up all ordinary matter, including you and whatever device you’re using to read this article. The collisions also produce tau leptons, which are like massive electrons. All of these particles are seldom found in nature, and observing them can reveal new physics.

Since B-mesons contain bottom quarks, which have diverse kinds of decays, scientists will use Belle II to observe the different meson decays. If a meson containing regular quarks decays differently than one containing their antimatter twins, this could help explain why the universe is full of matter.

Bolstering Belle

Belle II is the successor of earlier experiments used to produce B-mesons, Belle and BaBar. It will record about 40 times as many collisions as the original Belle. It’s also a tremendous collaboration between 25 countries, with 750 national and international physicists.

“Every measurement we’ve made until this point and every hint of new physics is limited by statistics and by the amount of data we have,” says Tom Browder, professor at the University of Hawaii and spokesperson for Belle II. “It’s very clear that to find any new physics we need much more data.”

With more collisions at the center of Belle II, scientists have more opportunities for an uncommon or unheard-of decay event to take place, giving them better insight into quarks’ behavior and how it factors into the universe’s creation.

“With 40 times more collisions per second than the previous Belle experiment, we’ll be able to search for rare decays, possibly observe new particles, and try to answer still unsolved questions about the origin of the universe,” Prencipe says. “Many of us are quite excited because this could mean the start of a new era, where lots of data are expected, new detectors will be tested, and we have great possibilities to perform unique physics.”

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The coevolution of physics and math

Breakthroughs in physics sometimes require an assist from the field of mathematics—and vice versa.

Einstein and Reimann in a geometric field of color, pattern, and shape

In 1912, Albert Einstein, then a 33-year-old theoretical physicist at the Eidgenössische Technische Hochschule in Zürich, was in the midst of developing an extension to his theory of special relativity. 

With special relativity, he had codified the relationship between the dimensions of space and time. Now, seven years later, he was trying to incorporate into his theory the effects of gravity. This feat—a revolution in physics that would supplant Isaac Newton’s law of universal gravitation and result in Einstein’s theory of general relativity—would require some new ideas.

Fortunately, Einstein’s friend and collaborator Marcel Grossmann swooped in like a waiter bearing an exotic, appetizing delight (at least in a mathematician’s overactive imagination): Riemannian geometry. 

This mathematical framework, developed in the mid-19th century by German mathematician Bernhard Riemann, was something of a revolution itself. It represented a shift in mathematical thinking from viewing mathematical shapes as subsets of the three-dimensional space they lived in to thinking about their properties intrinsically. For example, a sphere can be described as the set of points in 3-dimensional space that lie exactly 1 unit away from a central point. But it can also be described as a 2-dimensional object that has particular curvature properties at every single point. This alternative definition isn’t terribly important for understanding the sphere itself but ends up being very useful with more complicated manifolds or higher-dimensional spaces.

By Einstein’s time, the theory was still new enough that it hadn’t completely permeated through mathematics, but it happened to be exactly what Einstein needed. Riemannian geometry gave him the foundation he needed to formulate the precise equations of general relativity. Einstein and Grossmann were able to publish their work later that year.

“It’s hard to imagine how he would have come up with relativity without help from mathematicians,” says Peter Woit, a theoretical physicist in the Mathematics Department at Columbia University. 

The story of general relativity could go to mathematicians’ heads. Here mathematics seems to be a benevolent patron, blessing the benighted world of physics with just the right equations at the right time. 

When you go far enough back, you really can’t tell who’s a physicist and who’s a mathematician.

But of course the interplay between mathematics and physics is much more complicated than that. They weren’t even separate disciplines for most of recorded history. Ancient Greek, Egyptian and Babylonian mathematics took as an assumption the fact that we live in a world in which distance, time and gravity behave in a certain way. 

“Newton was the first physicist,” says Sylvester James Gates, a physicist at Brown University. “In order to reach the pinnacle, he had to invent a new piece of mathematics; it’s called calculus.”

Calculus made some classical geometry problems easier to solve, but its foremost purpose to Newton was to give him a way to analyze the motion and change he observed in physics. In that story, mathematics is perhaps more of a butler, hired to help keep the affairs in order, than a savior.

Even after physics and mathematics began their separate evolutionary paths, the disciplines were closely linked. “When you go far enough back, you really can’t tell who’s a physicist and who’s a mathematician,” Woit says. (As a mathematician, I was a bit scandalized the first time I saw Emmy Noether’s name attached to physics! I knew her primarily through abstract algebra.)

Throughout the history of the two fields, mathematics and physics have each contributed important ideas to the other. Mathematician Hermann Weyl’s work on mathematical objects called Lie groups provided an important basis for understanding symmetry in quantum mechanics. In his 1930 book The Principles of Quantum Mechanics, theoretical physicist Paul Dirac introduced the Dirac delta function to help describe the concept in particle physics of a pointlike particle—anything so small that it would be modeled by a point in an idealized situation. A picture of the Dirac delta function looks like a horizontal line lying along the bottom of the x axis of a graph, at x=0, except at the place where it intersects with the y axis, where it explodes into a line pointing up to infinity. Dirac declared that the integral of this function, the measure of the area underneath it, was equal to 1. Strictly speaking, no such function exists, but Dirac’s use of the Dirac delta eventually spurred mathematician Laurent Schwartz to develop the theory of distributions in a mathematically rigorous way. Today distributions are extraordinarily useful in the mathematical fields of ordinary and partial differential equations.

Though modern researchers focus their work more and more tightly, the line between physics and mathematics is still a blurry one. A physicist has won the Fields Medal, one of the most prestigious accolades in mathematics. And a mathematician, Maxim Kontsevich, has won the new Breakthrough Prizes in both mathematics and physics. One can attend seminar talks about quantum field theory, black holes, and string theory in both math and physics departments. Since 2011, the annual String Math conference has brought mathematicians and physicists together to work on the intersection of their fields in string theory and quantum field theory.

String theory is perhaps the best recent example of the interplay between mathematics and physics, for reasons that eventually bring us back to Einstein and the question of gravity.  

String theory is a theoretical framework in which those pointlike particles Dirac was describing become one-dimensional objects called strings. Part of the theoretical model for those strings  corresponds to gravitons, theoretical particles that carry the force of gravity.

Most humans will tell you that we perceive the universe as having three spatial dimensions and one dimension of time. But string theory naturally lives in 10 dimensions. In 1984, as the number of physicists working on string theory ballooned, a group of researchers including Edward Witten, the physicist who was later awarded a Fields Medal, discovered that the extra six dimensions of string theory needed to be part of a space known as a Calabi-Yau manifold. 

When mathematicians joined the fray to try to figure out what structures these manifolds could have, physicists were hoping for just a few candidates. Instead, they found boatloads of Calabi-Yaus. Mathematicians still have not finished classifying them. They haven’t even determined whether their classification has a finite number of pieces. 

As mathematicians and physicists studied these spaces, they discovered an interesting duality between Calabi-Yau manifolds. Two manifolds that seem completely different can end up describing the same physics. This idea, called mirror symmetry, has blossomed in mathematics, leading to entire new research avenues. The framework of string theory has almost become a playground for mathematicians, yielding countless new avenues of exploration.

Mina Aganagic, a theoretical physicist at the University of California, Berkeley, believes string theory and related topics will continue to provide these connections between physics and math. 

“In some sense, we’ve explored a very small part of string theory and a very small number of its predictions,” she says. Mathematicians and their focus on detailed rigorous proofs bring one point of view to the field, and physicists, with their tendency to prioritize intuitive understanding, bring another. “That’s what makes the relationship so satisfying.”

The relationship between physics and mathematics goes back to the beginning of both subjects; as the fields have advanced, this relationship has gotten more and more tangled, a complicated tapestry. There is seemingly no end to the places where a well-placed set of tools for making calculations could help physicists, or where a probing question from physics could inspire mathematicians to create entirely new mathematical objects or theories.

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