Angela Fava: studying neutrinos around the globe

This experimental physicist has followed the ICARUS neutrino detector from Gran Sasso to Geneva to Chicago.

Photo of Angela Fava giving a talk at the Fermilab User's Meeting

Physicist Angela Fava has been at the enormous ICARUS detector’s side for over a decade. As an undergraduate student in Italy in 2006, she worked on basic hardware for the neutrino hunting experiment: tightening bolts and screws, connecting and reconnecting cables, learning how the detector worked inside and out.

ICARUS (short for Imaging Cosmic And Rare Underground Signals) first began operating for research in 2010, studying a beam of neutrinos created at European laboratory CERN and launched straight through the earth hundreds of miles to the detector’s underground home at INFN Gran Sasso National Laboratory.

In 2014, the detector moved to CERN for refurbishing, and Fava relocated with it. In June ICARUS began a journey across the ocean to the US Department of Energy’s Fermi National Accelerator Laboratory to take part in a new neutrino experiment. When it arrives today, Fava will be waiting.

Fava will go through the installation process she helped with as a student, this time as an expert.

Photo of a shipping container with the words
Caraban Gonzalez, Noemi Ordan, Julien Marius, CERN

Journey to ICARUS

As a child growing up between Venice and the Alps, Fava always thought she would pursue a career in math. But during a one-week summer workshop before her final year of high school in 2000, she was drawn to experimental physics.

At the workshop, she realized she had more in common with physicists. Around the same time, she read about new discoveries related to neutral, rarely interacting particles called neutrinos. Scientists had recently been surprised to find that the extremely light particles actually had mass and that different types of neutrinos could change into one another. And there was still much more to learn about the ghostlike particles.

At the start of college in 2001, Fava immediately joined the University of Padua neutrino group. For her undergraduate thesis research, she focused on the production of hadrons, making measurements essential to studying the production of neutrinos. In 2004, her research advisor Alberto Guglielmi and his group joined the ICARUS collaboration, and she’s been a part of it ever since.

Fava jests that the relationship actually started much earlier: “ICARUS was proposed for the first time in 1983, which is the year I was born. So we are linked from birth.”

Fava remained at the University of Padua in the same research group for her graduate work. During those years, she spent about half of her time at the ICARUS detector, helping bring it to life at Gran Sasso.

Once all the bolts were tightened and the cables were attached, ICARUS scientists began to pursue their goal of using the detector to study how neutrinos change from one type to another.

During operation, Fava switched gears to create databases to store and log the data. She wrote code to automate the data acquisition system and triggering, which differentiates between neutrino events and background such as passing cosmic rays. “I was trying to take part in whatever activity was going on just to learn as much as possible,” she says.

That flexibility is a trait that Claudio Silverio Montanari, the technical director of ICARUS, praises. “She has a very good capability to adapt,” he says. “Our job, as physicists, is putting together the pieces and making the detector work.”

Photo of the ICARUS shipping container being transported by truck
Caraban Gonzalez, Noemi Ordan, Julien Marius, CERN

Changing it up

Adapting to changing circumstances is a skill both Fava and ICARUS have in common. When scientists proposed giving the detector an update at CERN and then using it in a suite of neutrino experiments at Fermilab, Fava volunteered to come along for the ride.

Once installed and operating at Fermilab, ICARUS will be used to study neutrinos from a source a few hundred meters away from the detector. In its new iteration, ICARUS will search for sterile neutrinos, a hypothetical kind of neutrino that would interact even more rarely than standard neutrinos. While hints of these low-mass particles have cropped up in some experiments, they have not yet been detected.

At Fermilab, ICARUS also won’t be buried below more than half a mile of rock, a feature of the INFN setup that shielded it from cosmic radiation from space. That means the triggering system will play an even bigger role in this new experiment, Fava says.

“We have a great challenge ahead of us.” She’s up to the task.

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Turning plots into stained glass

Hubert van Hecke, a heavy-ion physicist, transforms particle physics plots into works of art.

Stained glass image inspired by Fibonacci numbers

At first glance, particle physicist Hubert van Hecke’s stained glass windows simply look like unique pieces of art. But there is much more to them than pretty shapes and colors. A closer look reveals that his creations are actually renditions of plots from particle physics experiments.  

Van Hecke learned how to create stained glass during his undergraduate years at Louisiana State University. “I had an artistic background—my father was a painter, so I thought, if I need a humanities credit, I'll just sign up for this,” van Hecke recalls. “So in order to get my physics’ bachelors, I took stained glass.” 

Over the course of two semesters, van Hecke learned how to cut pieces of glass from larger sheets, puzzle them together, then solder and caulk the joints. “There were various assignments that gave you an enormous amount of elbow room,” he says. “One of them was to do something with Fibonacci numbers, and one was pick your favorite philosopher and made a window related to their work.” 

Van Hecke continued to create windows and mirrors throughout graduate school but stopped for many years while working as a full-time heavy-ion physicist at Los Alamos National Laboratory and raising a family. Only recently did he return to his studio—this time, to create pieces inspired by physics. 

“I had been thinking about designs for a long time—then it struck me that occasionally, you see plots that are interesting, beautiful shapes,” van Hecke says. “So I started collecting pictures as I saw them.”

Stained Glass Pieces
Hubert van Hecke
Stained glass inspired by the Higgs boson
Hubert van Hecke, Stained glass inspired by the Higgs boson
Stained glass piece inspired by the MiniBoone in red, orange, and yellow
Hubert van Hecke, Stained glass piece inspired by Neutrinos and the MiniBoone in red, orange, and yellow
Stained glass piece inspired by Quarks and Gluons in red and blue
Hubert van Hecke, Stained glass piece inspired by Quarks and Gluons in red and blue
Stained glass 'and Man Created the Universe'
Hubert van Hecke, Stained glass 'and Man Created the Universe'
Circular stained glass piece in light and dark blue
Hubert van Hecke, Circular stained glass piece in light and dark blue
Curved lines stained glass piece in red, yellow, and black
Hubert van Hecke, Curved lines stained glass piece in red, yellow, and black
Square stained glass piece in red, yellow, green, and blue
Hubert van Hecke, Square stained glass piece in red, yellow, green, and blue
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His first plot-based window, a rectangle-shaped piece with red, orange and yellow glass, was inspired by the results of a neutrino flavor oscillation study from the MiniBooNE experiment at Fermi National Accelerator Laboratory. He created two pieces after that, one from a plot generated during the hunt for the Higgs boson at the Tevatron, also at Fermilab and the other based on an experiment with quarks and gluons. 

According to van Hecke, what inspires him about these plots is “purely the shapes.” 

“In terms of the physics, it's what I run across—for example, I see talks about heavy ion physics, elementary particle physics, and neutrinos, [but] I haven't really gone out and searched in other fields,” he says. “Maybe there are nice plots in biology or astronomy.”

Although van Hecke has not yet displayed his pieces publicly, if he does one day, he plans to include explanations for the phenomena the plots illustrate, such as neutrinos and the Standard Model, as a unique way to communicate science. 

But before that, van Hecke plans to create more stained glass windows. As of two months ago, he is semiretired—and in between runs to Fermilab, where he is helping with the effort to use Argonne National Laboratory's SeaQuest experiment to search for dark photons, he hopes to spend more time in the studio creating the pieces left on the drawing board, which include plots found in experiments investigating the Standard Model, neutrinoless double decay and dark matter interactions. 

“I hope to make a dozen or more,” he says. “As I bump into plots, I'll collect them and hopefully, turn them all into windows.” 

Collected Plots
Hubert van Hecke
From the 2016 APS wall calendar, from Phys Rev D91, 07007 (2015)
Hubert van Hecke, From the 2016 APS wall calendar, from Phys Rev D91, 07007 (2015)
From the Dark Interactions workshop,  talk by Tim M.P. Tait.  Annotated version  v1
Hubert van Hecke, From the Dark Interactions workshop, talk by Tim M.P. Tait. Annotated version v1
Dark photons, wwnd 2015 Dipali Sharma
Hubert van Hecke, Dark photons, wwnd 2015 Dipali Sharma
Stained Glass Sketch_4
Hubert van Hecke
neutrinoless double beta decay
Hubert van Hecke, Neutrinoless double beta decay
neutrino/wimp talk, slide 21
Hubert van Hecke, Neutrino/wimp talk, slide 21
Neutrinoless double beta decay
Hubert van Hecke, Neutrinoless double beta decay
ICHEP 2012, Joao Guimaraes da Costa, Harvard.
Hubert van Hecke, ICHEP 2012, Joao Guimaraes da Costa, Harvard
ICHEP 2012, Joao Guimaraes da Costa, Harvard.
Hubert van Hecke, ICHEP 2012, Joao Guimaraes da Costa, Harvard.
Brazil plot from WWND 2015 Dipali Sharma
Hubert van Hecke, Brazil plot from WWND 2015 Dipali Sharma
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Watch the underground groundbreaking

This afternoon, watch a livestream of the start of excavation for the future home of the Deep Underground Neutrino Experiment.

Photo of the Yates surface facilities at Sanford Lab, a white building surrounded by tree-covered mountains

Today in South Dakota, dignitaries, scientists and engineers will mark the start of construction of the future home of America's flagship neutrino experiment with a groundbreaking ceremony.

Participants will hold shovels and give speeches. But this will be no ordinary groundbreaking. It will take place a mile under the earth at Sanford Underground Research Facility, the deepest underground physics lab in the United States.

The groundbreaking will celebrate the beginning of excavation for the Long-Baseline Neutrino Facility, which will house the Deep Underground Neutrino Experiment. When complete, LBNF/DUNE will be the largest experiment ever built in the US to study the properties of mysterious particles called neutrinos. Unlocking the mysteries of these particles could help explain more about how the universe works and why matter exists at all.

Watch the underground groundbreaking at 2:20 p.m. Mountain Time (3:20 p.m. Central) via livestream.

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Shaking the dark matter paradigm

A theory about gravity challenges our understanding of the universe.

Gravity vs. Dark Matter Reflection alternatives with dark matter on the left and no dark matter on the right.

For millennia, humans held a beautiful belief. Our planet, Earth, was at the center of a vast universe, and all of the planets and stars and celestial bodies revolved around us. This geocentric model, though it had floated around since 6th century BCE, was written in its most elegant form by Claudius Ptolemy in 140 AD.

When this model encountered problems, such as the retrograde motions of planets, scientists reworked the data to fit the model by coming up with phenomena such as epicycles, mini orbits.

It wasn’t until 1543, 1400 years later, that Nicolaus Copernicus set in motion a paradigm shift that would give way to centuries of new discoveries. According to Copernicus’ radical theory, Earth was not the center of the universe but simply one of a long line of planets orbiting around the sun.

But even as evidence that we lived in a heliocentric system piled up and scientists such as Galileo Galilei perfected the model, society held onto the belief that the entire universe orbited around Earth until the early 19th century.

To Erik Verlinde, a theoretical physicist at the University of Amsterdam, the idea of dark matter is the geocentric model of the 21st century. 

“What people are doing now is allowing themselves free parameters to sort of fit the data,” Verlinde says. “You end up with a theory that has so many free parameters it's hard to disprove.”

Dark matter, an as-yet-undetected form of matter that scientists believe makes up more than a quarter of the mass and energy of the universe, was first theorized when scientists noticed that stars at the outer edges of galaxies and galaxy clusters were moving much faster than Newton’s theory of gravity said they should. Up until this point, scientists have assumed that the best explanation for this is that there must be missing mass in the universe holding those fast-moving stars in place in the form of dark matter. 

But Verlinde has come up with a set of equations that explains these galactic rotation curves by viewing gravity as an emergent force — a result of the quantum structure of space.

The idea is related to dark energy, which scientists think is the cause for the accelerating expansion of our universe. Verlinde thinks that what we see as dark matter is actually just interactions between galaxies and the sea of dark energy in which they’re embedded.

“Before I started working on this I never had any doubts about dark matter,” Verlinde says. “But then I started thinking about this link with quantum information and I had the idea that dark energy is carrying more of the dynamics of reality than we realize.”

Verlinde is not the first theorist to come up with an alternative to dark matter. Many feel that his theory echoes the sentiment of physicist Mordehai Milgrom’s equations of “modified Newtonian dynamics,” or MOND. Just as Einstein modified Newton’s laws of gravity to fit to the scale of planets and solar systems, MOND modifies Einstein’s laws of gravity to fit to the scale of galaxies and galaxy clusters.

Verlinde, however, makes the distinction that he’s not deriving the equations of MOND, rather he’s deriving what he calls a “scaling relation,” or a volume effect of space-time that only becomes important at large distances. 

Stacy McGaugh, an astrophysicist at Case Western Reserve University, says that while MOND is primarily the notion that the effective force of gravity changes with acceleration, Verlinde’s ideas are more of a ground-up theoretical work.

“He's trying to look at the structure of space-time and see if what we call gravity is a property that emerges from that quantum structure, hence the name emergent gravity,” McGaugh says. “In principle, it's a very different approach that doesn't necessarily know about MOND or have anything to do with it.”

One of the appealing things about Verlinde’s theory, McGaugh says, is that it naturally produces evidence of MOND in a way that “just happens.” 

“That's the sort of thing that one looks for,” McGaugh says. “There needs to be some basis of why MOND happens, and this theory might provide it.”

Verlinde’s ideas have been greeted with a fair amount of skepticism in the scientific community, in part because, according to Kathryn Zurek, a theoretical physicist at the US Department of Energy’s Lawrence Berkeley National Laboratory, his theory leaves a lot unexplained. 

“Theories of modified gravity only attempt to explain galactic rotation curves [those fast-moving planets],” Zurek says. “As evidence for dark matter, that's only one very small part of the puzzle. Dark matter explains a whole host of observations from the time of the cosmic microwave background when the universe was just a few hundred thousand years old through structure formation all the way until today.”


Inline: Shaking the dark matter paradigm
Illustration by Ana Kova

Zurek says that in order for scientists to start lending weight to his claims, Verlinde needs to build the case around his theory and show that it accommodates a wider range of observations. But, she says, this doesn’t mean that his ideas should be written off.

“One should always poke at the paradigm,” Zurek says, “even though the cold dark matter paradigm has been hugely successful, you always want to check your assumptions and make sure that you're not missing something that could be the tip of the iceberg.”

McGaugh had a similar crisis of faith in dark matter when he was working on an experiment wherein MOND’s predictions were the only ones that came true in his data. He had been making observations of low-surface-brightness galaxies, wherein stars are spread more thinly than galaxies such as the Milky Way where the stars are crowded relatively close together.

McGaugh says his results did not make sense to him in the standard dark matter context, and it turned out that the properties that were confusing to him had already been predicted by Milgrom’s MOND equations in 1983, before people had even begun to take seriously the idea of low-surface-brightness galaxies.

Although McGaugh’s experience caused him to question the existence of dark matter and instead argue for MOND, others have not been so quick to join the cause.

“We subscribe to a particular paradigm and most of our thinking is constrained within the boundaries of that paradigm, and so if we encounter a situation in which there is a need for a paradigm shift, it's really hard to think outside that box,” McGaugh says. “Even though we have rules for the game as to when you're supposed to change your mind and we all in principle try to follow that, in practice there are some changes of mind that are so big that we just can't overcome our human nature.”

McGaugh says that many of his colleagues believe that there’s so much evidence for dark matter that it’s a waste of time to consider any alternatives. But he believes that all of the evidence for dark matter might instead be an indication that there is something wrong with our theories of gravity. 

“I kind of worry that we are headed into another thousand years of dark epicycles,” McGaugh says.

But according to Zurek, if MOND came up with anywhere near the evidence that has been amassed for the dark matter paradigm, people would be flocking to it. The problem, she says, is that at the moment MOND just does not come anywhere near to passing the number of tests that cold dark matter has. She adds that there are some physicists who argue that the cold dark matter paradigm can, in fact, explain those observations about low-surface-brightness galaxies.

Recently, Case Western held a workshop wherein they gathered together representatives from different communities, including those working on dark matter models, to discuss dwarf galaxies and the external field effect, which is the notion that very low-density objects will be affected by what’s around them. MOND predicts that the dynamics of a small satellite galaxy will depend on its proximity to its giant host in a way that doesn't happen with dark matter.

McGaugh says that in attendance at the workshop were a group of more philosophically inclined people who use a set of rules to judge theories, which they’ve put together by looking back at how theories have developed in the past. 

“One of the interesting things that came out of that was that MOND is doing better on that score card,” he says. “It’s more progressive in the sense that it's making successful predictions for new phenomena whereas in the case of dark matter we've had to repeatedly invoke ad hoc fixes to patch things up.”

Verlinde’s ideas, however, didn’t come up much within the workshop. While McGaugh says that the two theories are closely enough related that he would hope the same people pursuing MOND would be interested in Verlinde’s theory, he added that not everyone shares that attitude. Many are waiting for more theoretical development and further observational tests.

“The theory needs to make a clear prediction so that we can then devise a program to go out and test it,” he says. “It needs to be further worked out to get beyond where we are now.”

Verlinde says he realizes that he still needs to develop his ideas further and extend them to explain things such as the formation of galaxies and galaxy clusters. Although he has mostly been working on this theory on his own, he recognizes the importance of building a community around his ideas.

Over the past few months, he has been giving presentations at different universities, including Princeton, Harvard, Berkeley, Stanford, and Caltech. There is currently a large community of people working on ideas of quantum information and gravity, he says, and his main goal is to get more people, in particular string theorists, to start thinking about his ideas to help him improve them.

“I think that when we understand gravity better and we use those equations to describe the evolution of the universe, we may be able to answer questions more precisely about how the universe started,” Verlinde says. “I really think that the current description is only part of the story and there's a much deeper way of understanding it—maybe an even more beautiful way.”


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SLAC accelerator plans appear in Smithsonian art exhibit

The late artist June Schwarcz found inspiration in some unusual wrapping paper her husband brought home from the lab.


Photograph of June Schwarcz at home

Leroy Schwarcz, one of the first engineers hired to build SLAC National Accelerator Laboratory’s original 2-mile-long linear accelerator, thought his wife might like to use old mechanical drawings of the project as wrapping paper. So, he brought them home.

His wife, acclaimed enamelist June Schwarcz, had other ideas.

Today, works called SLAC Drawing III, VII and VIII, created in 1974 and 1975 from electroplated copper and enamel, form a unique part of a retrospective at the Smithsonian’s Renwick Gallery in Washington, D.C.

Among the richly formed and boldly textured and colored vessels that make up the majority of June’s oeuvre, the SLAC-inspired panels stand out for their fidelity to the mechanical design of their inspiration. 

The description next to the display at the gallery describe the “SLAC Blueprints” as resembling “ancient pictographs drawn on walls of a cave or glyphs carved in stone.” The designs appear to depict accelerator components, such as electromagnets and radio frequency structures.

According to Harold B. Nelson, who curated the exhibit with Bernard N. Jazzar, “The panels are quite unusual in the subtle color palette she chose; in her use of predominantly opaque enamels; in her reliance on a rectilinear, geometric format for her compositions; and in her reference in the work to machines, plans, numbers, and mechanical parts. 

“We included them because they are extremely beautiful and visually powerful. Together they form an important group within her body of work.”

Making history

June and Leroy Schwarcz met in the late 1930s and were married in 1943. Two years later they moved to Chicago where Leroy would become chief mechanical engineer for the University of Chicago’s synchrocyclotron, which was at the time the highest-energy proton accelerator in the world.

Having studied art and design at the Pratt Institute in Brooklyn several years earlier, June found her way into a circle of notable artists in Chicago, including Bauhaus legend László Moholy-Nagy, founder of Chicago’s Institute of Design.

Around 1954, June was introduced to enameling and shortly thereafter began to exhibit her art. She and her husband had two children and relocated several times during the 1950s for Leroy’s work. In 1958 they settled in Sausalito, California, where June set up her studio in the lower level of their hillside home. 

In 1961, Leroy became the first mechanical engineer hired by Stanford University to work on “Project M,” which would become the famous 2-mile-long linear accelerator at SLAC. He oversaw the engineers during early design and construction of the linac, which eventually enabled Nobel-winning particle physics research.

June and Leroy’s daughter, Kim Schwarcz, who made a living as a glass blower and textile artist until the mid 1980s and occasionally exhibited with her mother, remembers those early days at the future lab.

“Before SLAC was built, the offices were in Quonset huts, and my father used to bring me down, and I would bicycle all over the campus,” she recalled. “Pief was a family friend and so was Bob Mozley. Mom introduced Bob to his future wife…It was a small community and a really nice community.” 

W.K.H. “Pief” Panofsky was the first director of SLAC; he and Mozley were renowned SLAC physicists and national arms control experts.

June Schwarcz, SLAC Drawing III, 1974, electroplated copper and enamel. (Photo by Cate Hurst)
June Schwarcz, SLAC Drawing III, 1974, electroplated copper and enamel. (Photo by Cate Hurst)
June Schwarcz, SLAC Drawing VII, 1975, electroplated copper and enamel. (Photo by Cate Hurst)
June Schwarcz, SLAC Drawing VII, 1975, electroplated copper and enamel. (Photo by Cate Hurst)
June Schwarcz, SLAC Drawing VIII, 1975, electroplated copper and enamel. (Photo by Cate Hurst)
June Schwarcz, SLAC Drawing VIII, 1975, electroplated copper and enamel. (Photo by Cate Hurst)
June Schwarcz, SLAC Design Box, 1989, electroplated copper and enamel, mounted in a cherry box. (Photo by M. Lee Fatherree)
June Schwarcz, SLAC Design Box, 1989, electroplated copper and enamel, mounted in a cherry box. (Photo by M. Lee Fatherree)
June Schwarcz, Vessel, electroplated copper foil and enamel, sandblasted. (Photo by Cate Hurst)
June Schwarcz, Vessel, electroplated copper foil and enamel, sandblasted. (Photo by Cate Hurst)
Bowl, 1980, electroplated copper foil and enamel, iron plated. (Photo by Gene Young)
June Schwarcz, Bowl, 1980, electroplated copper foil and enamel, iron plated. (Photo by Gene Young)
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Finding beauty

Kim was not surprised that her mother made art based on the SLAC drawings. She remembers June photographing the foggy view outside their home and getting inspiration from nature, ethnic art and Japanese clothing.

“She would take anything and make something out of it,” Kim said. “She did an enamel of an olive oil can once and a series called Adam’s Pants that were based on the droopy pants my son wore as a teen.”

But the fifteen SLAC-inspired compositions were unique and a family favorite; Kim and her brother Carl both own some of them, and others are at museums.

In a 2001 oral history interview with the Smithsonian Institution's Archives of American Art, June explained the detailed work involved in creating the SLAC drawings by varnishing, scribing, electroplating and enameling a copper sheet: “I'm primarily interested in having things that are beautiful, and of course, beauty is a complicated thing to devise, to find.”

Engineering art

Besides providing inspiration in the form of technical drawings, Leroy was influential in June’s career in other ways.

Around 1962 he introduced her to Jimmy Pope at the SLAC machine shop, who showed June how to do electroplating, a signature technique of her work. Electroplating involves using an electric current to deposit a coating of metal onto another material. She used it to create raised surfaces and to transform thin sheets of copper—which she stitched together using copper wire—into substantial, free-standing vessel-like forms. She then embellished these sculptures with colored enamel.

Leroy built a 30-gallon plating bath and other tools for June’s art-making at their shared workshop. 

“Mom was tiny, 5 feet tall, and she had these wobbly pieces on the end of a fork that she would put into a hot kiln. It was really heavy. Dad made a stand so she could rest her arm and slide the piece in,” Kim recalls.

“He was very inventive in that way, and very creative himself,” she said. “He did macramé in the 1960s, made wooden spoons and did scrimshaw carvings on bone that were really good.”

Kim remembers the lower-level workshop as a chaotic and inventive space. “For the longest time, there was a wooden beam in the middle of the workshop we would trip over. It was meant for a boat dad wanted to build—and eventually did build after he retired,” she said.

At SLAC Leroy’s work was driven by his “amazingly good intuition,” according to a tribute written by Mozley upon his colleague’s death in 1993. Even when he favored crude drawings to exact math, “his intuitive designs were almost invariably right,” he wrote. 

After the accelerator was built, Leroy turned his attention to the design, construction and installation of a streamer chamber scientists at SLAC used as a particle detector. In 1971 he took a leave of absence from the California lab to go back to Chicago and move the synchrocyclotron’s 2000-ton magnet from the university to Fermi National Accelerator Laboratory. 

“[Leroy] was the only person who could have done this because, although drawings existed, knowledge of the assembly procedures existed only in the minds of Leroy and those who had helped him put the cyclotron together,” Mozley wrote.

Beauty on display

June continued making art at her Sausalito home studio up until two weeks before her death in 2015 at the age of 97. A 2007 video shows the artist at work there 10 years prior to her passing. 

After Leroy died, her own art collection expanded on the shelves and walls of her home.

“As a kid, the art was just what mom did, and it never changed,” Kim remembers. “She couldn’t wait for us to go to school so she could get to work, and she worked through health challenges in later years.”

The Smithsonian exhibit is a unique collection of June’s celebrated work, with its traces of a shared history with SLAC and one of the lab’s first mechanical engineers.

“June had an exceptionally inquisitive mind, and we think you get a sense of the rich breadth of her vision in this wonderful body of work,” says curator Jazzar.

June Schwarcz: Invention and Variation is the first retrospective of the artist’s work in 15 years and includes almost 60 works. The exhibit runs through August 27 at the Smithsonian American Art Museum Renwick Gallery. 

Editor's note: Some of the information from this article was derived from an essay written by Jazzar and Nelson that appears in a book based on the exhibition with the same title.

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A new model for standards

In an upcoming refresh, particle physics will define units of measurement such as the meter, the kilogram and the second.

Image of yellow ruler background with moon and red and Plank graphics

While America remains obstinate about using Imperial units such as miles, pounds and degrees Fahrenheit, most of the world has agreed that using units that are actually divisible by 10 is a better idea. The metric system, also known as the International System of Units (SI), is the most comprehensive and precise system for measuring the universe that humans have developed. 

In 2018, the 26th General Conference on Weights and Measures will convene and likely adopt revised definitions for the seven base metric system units for measuring: length, mass, time, temperature, electric current, luminosity and quantity.

The modern metric system owes its precision to particle physics, which has the tools to investigate the universe more precisely than any microscope. Measurements made by particle physicists can be used to refine the definitions of metric units. In May, a team of German physicists at the Physikalisch-Technische Bundesanstalt made the most precise measurements yet of the Boltzmann constant, which will be used to define units of temperature.

Since the metric system was established in the 1790s, scientists have attempted to give increasingly precise definitions to these units. The next update will define every base unit using fundamental constants of the universe that have been derived by particle physics.

meter (distance): 

Starting in 1799, the meter was defined by a prototype meter bar, which was just a platinum bar. Physicists eventually realized that distance could be defined by the speed of light, which has been measured with an accuracy to one part in a billion using an interferometer (interestingly, the same type of detector the LIGO collaboration used to discover gravitational waves). The meter is currently defined as the distance traveled by light (in a vacuum) for 1/299,792,458 of a second, and will remain effectively unchanged in 2018.

kilogram (mass):

For over a century, the standard kilogram has been a small platinum-iridium cylinder housed at the International Bureau of Weights and Measures in France. But even its precise mass fluctuates due to factors such as accumulation of microscopic dust. Scientists hope to redefine the kilogram in 2018 by setting the value of Planck’s constant to exactly 6.626070040×1034 kilograms times meters squared per second. Planck’s constant is the smallest amount of quantized energy possible. This fundamental value, which is represented with the letter h, is integral to calculating energies in particle physics.

second (time):

The earliest seconds were defined as divisions of time between full moons. Later, seconds were defined by solar days, and eventually the time it took Earth to revolve around the sun. Today, seconds are defined by atomic time, which is precise to 1 part in 10 billion. Atomic time is calculated by periods of radiation by atoms, a measurement that relies heavily on particle physics techniques. One second is currently defined as 9,192,631,770 periods of the radiation for a Cesium-133 atom and will remain effectively unchanged. 

kelvin (temperature):

Kelvin is the temperature scale that starts at the coldest possible state of matter. Currently, a kelvin is defined by the triple point of water—where water can exist as a solid, liquid and gas. The triple point is 273.16 Kelvin, so a single kelvin is 1/273.16 of the triple point. But because water can never be completely pure, impurities can influence the triple point. In 2018 scientists hope to redefine kelvin by setting the value of Boltzmann’s constant to exactly 1.38064852×10−23 joules per kelvin. Boltzmann’s constant links the movement of particles in a gas (the average kinetic energy) to the temperature of the gas. Denoted by the symbol k, the Boltzmann constant is ubiquitous throughout physics calculations that involve temperature and entropy.  

ampere (electric current):

André-Marie Ampère, who is often considered the father of electrodynamics, has the honor of having the basic unit of electric current named after him. Right now, the ampere is defined by the amount of current required to produce of a force of 2×10−7 newtons for each meter between two parallel conductors of infinite length. Naturally, it’s a bit hard to come by things of infinite length, so the proposed definition is instead to define amperes by the fundamental charge of a particle. This new definition would rely on the charge of the electron, which will be set to 1.6021766208×10−19 amperes per second.

candela (luminosity):

The last of the base SI units to be established, the candela measures luminosity—what we typically refer to as brightness. Early standards for the candela used a phenomenon from quantum mechanics called “black body radiation.” This is the light that all objects radiate as a function of their heat. Currently, the candela is defined more fundamentally as 1/683 watt per square radian at a frequency of 540×1012 herz over a certain area, a definition which will remain effectively unchanged. Hard to picture? A candle, conveniently, emits about one candela of luminous intensity.

mole (quantity):

Different from all the other base units, the mole measures quantity alone. Over hundreds of years, scientists starting from Amedeo Avogadro worked to better understand how the number of atoms was related to mass, leading to the current definition of the mole: the number of atoms in 12 grams of carbon-12. This number, which is known as Avogadro’s constant and used in many calculations of mass in particle physics, is about 6 x 10^23. To make the mole more precise, the new definition would set Avogadro’s constant to exactly 6.022140857×1023, decoupling it from the kilogram.

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Quirks of the arXiv

Sometimes, physics papers turn funny.

Header: Quirks of the arXiv

Since it went up in 1991, the arXiv (pronounced like the word “archive”) has been a hub for scientific papers in quantitative fields such as physics, math and computer science. Many of its million-plus papers are serious products of intense academic work that are later published in peer-reviewed journals. Still, some manage to have a little more character than the rest. For your consideration, we’ve gathered seven of the quirkiest physics papers on the arXiv.

Can apparent superluminal neutrino speeds be explained as a quantum weak measurement?

M V Berry, N Brunner, S Popescu and P Shukla

In 2011, an experiment appeared to find particles traveling faster than the speed of light. To spare readers uninterested in lengthy calculations demonstrating the unlikeliness of this probably impossible phenomenon, the abstract for this analysis cut to the chase.

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Quantum Tokens for Digital Signatures

Shalev Ben-David and Or Sattath

Sometimes the best way to explain something is to think about how you might explain it to a child—for example, as a fairy tale.

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A dialog on quantum gravity

Carlo Rovelli

Unless you’re intimately familiar with string theory and quantum loop gravity, this Socratic dialogue is like Plato’s Republic: It’s all Greek to you.

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The Proof of Innocence

Dmitri Krioukov

Pulled over after he was apparently observed failing to halt at a stop sign, the author of this paper, Dmitri Krioukov, was determined to prove his innocence—as only a scientist would.

Using math, he demonstrated that, to a police officer measuring the angular speed of Krioukov’s car, a brief obstruction from view could cause an illusion that the car did not stop. Krioukov submitted his proof to the arXiv; the judge ruled in his favor.

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Quantum weak coin flipping with arbitrarily small bias

Carlos Mochon

Not many papers in the arXiv illustrate their point with a tale involving human sacrifice. There’s something about quantum informatics that brings out the weird side of physicists.

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10 = 6 + 4

Frank D. (Tony) Smith, Jr.

A theorist calculated an alternative decomposition of 10 dimensions into 6 spacetime dimensions with local Conformal symmetry and 4-dimensional compact Internal Symmetry Space. For the title of his paper, he decided to go with something a little simpler.

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Would Bohr be born if Bohm were born before Born?

Hrvoje Nikolic

This tricky tongue-twisting treatise theorizes a tangential timeline to testify that taking up quantum theories turns on timeliness.

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When was the Higgs actually discovered?

The announcement on July 4 was just one part of the story. Take a peek behind the scenes of the discovery of the Higgs boson.

Photo from the back of a crowded conference room on the day of the Higgs announcement

Joe Incandela sat in a conference room at CERN and watched with his arms folded as his colleagues presented the latest results on the hunt for the Higgs boson. It was December 2011, and they had begun to see the very thing they were looking for—an unexplained bump emerging from the data.

“I was far from convinced,” says Incandela, a professor at the University of California, Santa Barbara and the former spokesperson of the CMS experiment at the Large Hadron Collider.

For decades, scientists had searched for the elusive Higgs boson: the holy grail of modern physics and the only piece of the robust and time-tested Standard Model that had yet to be found.

The construction of the LHC was motivated in large part by the absence of this fundamental component from our picture of the universe. Without it, physicists couldn’t explain the origin of mass or the divergent strengths of the fundamental forces.

“Without the Higgs boson, the Standard Model falls apart,” says Matthew McCullough, a theorist at CERN. “The Standard Model was fitting the experimental data so well that most of the theory community was convinced that something playing the role of Higgs boson would be discovered by the LHC.”

The Standard Model predicted the existence of the Higgs but did not predict what the particle’s mass would be. Over the years, scientists had searched for it across a wide range of possible masses. By 2011, there was only a tiny region left to search; everything else had been excluded by previous generations of experimentation. If the predicted Higgs boson were anywhere, it had to be there, right where the LHC scientists were looking.

But Incandela says he was skeptical about these preliminary results. He knew that the Higgs could manifest itself in many different forms, and this particular channel was extremely delicate.

“A tiny mistake or an unfortunate distribution of the background events could make it look like a new particle is emerging from the data when in reality, it’s nothing,” Incandela says.

A common mantra in science is that extraordinary claims require extraordinary evidence. The challenge isn’t just collecting the data and performing the analysis; it’s deciding if every part of the analysis is trustworthy. If the analysis is bulletproof, the next question is whether the evidence is substantial enough to claim a discovery. And if a discovery can be claimed, the final question is what, exactly, has been discovered? Scientists can have complete confidence in their results but remain uncertain about how to interpret them.

In physics, it’s easy to say what something is not but nearly impossible to say what it is. A single piece of corroborated, contradictory evidence can discredit an entire theory and destroy an organization’s credibility.

“We’ll never be able to definitively say if something is exactly what we think it is, because there’s always something we don’t know and cannot test or measure,” Incandela says. “There could always be a very subtle new property or characteristic found in a high-precision experiment that revolutionizes our understanding.”

With all of that in mind, Incandela and his team made a decision: From that point on, everyone would refine their scientific analyses using special data samples and a patch of fake data generated by computer simulations covering the interesting areas of their analyses. Then, when they were sure about their methodology and had enough data to make a significant observation, they would remove the patch and use their algorithms on all the real data in a process called unblinding.

“This is a nice way of providing an unbiased view of the data and helps us build confidence in any unexpected signals that may be appearing, particularly if the same unexpected signal is seen in different types of analyses,” Incandela says.

A few weeks before July 4, all the different analysis groups met with Incandela to present a first look at their unblinded results. This time the bump was very significant and showing up at the same mass in two independent channels.

“At that point, I knew we had something,” Incandela says. “That afternoon we presented the results to the rest of the collaboration. The next few weeks were among the most intense I have ever experienced.”

Meanwhile, the other general-purpose experiment at the LHC, ATLAS, was hot on the trail of the same mysterious bump.

Andrew Hard was a graduate student at The University of Wisconsin, Madison working on the ATLAS Higgs analysis with his PhD thesis advisor Sau Lan Wu.

“Originally, my plan had been to return home to Tennessee and visit my parents over the winter holidays,” Hard says. “Instead, I came to CERN every day for five months—even on Christmas. There were a few days when I didn't see anyone else at CERN. One time I thought some colleagues had come into the office, but it turned out to be two stray cats fighting in the corridor.”

Hard was responsible for writing the code that selected and calibrated the particles of light the ATLAS detector recorded during the LHC’s high-energy collisions. According to predictions from the Standard Model, the Higgs can transform into two of these particles when it decays, so scientists on both experiments knew that this project would be key to the discovery process.

“We all worked harder than we thought we could,” Hard says. “People collaborated well and everyone was excited about what would come next. All in all, it was the most exciting time in my career. I think the best qualities of the community came out during the discovery.”

At the end of June, Hard and his colleagues synthesized all of their work into a single analysis to see what it revealed. And there it was again—that same bump, this time surpassing the statistical threshold the particle physics community generally requires to claim a discovery.

“Soon everyone in the group started running into the office to see the number for the first time,” Hard says. “The Wisconsin group took a bunch of photos with the discovery plot.”

Hard had no idea whether CMS scientists were looking at the same thing. At this point, the experiments were keeping their latest results secret—with the exception of Incandela, Fabiola Gianotti (then ATLAS spokesperson) and a handful of CERN’s senior management, who regularly met to discuss their progress and results.

“I told the collaboration that the most important thing was for each experiment to work independently and not worry about what the other experiment was seeing,” Incandela says. “I did not tell anyone what I knew about ATLAS. It was not relevant to the tasks at hand.”

Still, rumors were circulating around theoretical physics groups both at CERN and abroad. Mccullough, then a postdoc at the Massachusetts Institute of Technology, was avidly following the progress of the two experiments.

“We had an update in December 2011 and then another one a few months later in March, so we knew that both experiments were seeing something,” he says. “When this big excess showed up in July 2012, we were all convinced that it was the guy responsible for curing the ails of the Standard Model, but not necessarily precisely that guy predicted by the Standard Model. It could have properties mostly consistent with the Higgs boson but still be not absolutely identical.”

The week before announcing what they’d found, Hard’s analysis group had daily meetings to discuss their results. He says they were excited but also nervous and stressed: Extraordinary claims require extraordinary confidence.

“One of our meetings lasted over 10 hours, not including the dinner break halfway through,” Hard says. “I remember getting in a heated exchange with a colleague who accused me of having a bug in my code.”

After both groups had independently and intensely scrutinized their Higgs-like bump through a series of checks, cross-checks and internal reviews, Incandela and Gianotti decided it was time to tell the world.

“Some people asked me if I was sure we should say something,” Incandela says. “I remember saying that this train has left the station. This is what we’ve been working for, and we need to stand behind our results.”

On July 4, 2012, Incandela and Gianotti stood before an expectant crowd and, one at a time, announced that decades of searching and generations of experiments had finally culminated in the discovery of a particle “compatible with the Higgs boson.”

Science journalists rejoiced and rushed to publish their stories. But was this new particle the long-awaited Higgs boson? Or not?

Discoveries in science rarely happen all at once; rather, they build slowly over time. And even when the evidence overwhelmingly points in a clear direction, scientists will rarely speak with superlatives or make definitive claims.

“There is always a risk of overlooking the details,” Incandela says, “and major revolutions in science are often born in the details.”

Immediately after the July 4 announcement, theorists from around the world issued a flurry of theoretical papers presenting alternative explanations and possible tests to see if this excess really was the Higgs boson predicted by the Standard Model or just something similar.

“A lot of theory papers explored exotic ideas,” McCullough says. “It’s all part of the exercise. These papers act as a straw man so that we can see just how well we understand the particle and what additional tests need to be run.”

For the next several months, scientists continued to examine the particle and its properties. The more data they collected and the more tests they ran, the more the discovery looked like the long-awaited Higgs boson. By March, both experiments had twice as much data and twice as much evidence.

“Amongst ourselves, we called it the Higgs,” Incandela says, “but to the public, we were more careful.”

It was increasingly difficult to keep qualifying their statements about it, though. “It was just getting too complicated,” Incandela says. “We didn’t want to always be in this position where we had to talk about this particle like we didn’t know what it was.”

On March 14, 2013—nine months and 10 days after the original announcement—CERN issued a press release quoting Incandela as saying, “to me, it is clear that we are dealing with a Higgs boson, though we still have a long way to go to know what kind of Higgs boson it is.”​

To this day, scientists are open to the possibility that the Higgs they found is not exactly the Higgs they expected.

“We are definitely, 100 percent sure that this is a Standard-Model-like Higgs boson,” Incandela says. “But we’re hoping that there’s a chink in that armor somewhere. The Higgs is a sign post, and we’re hoping for a slight discrepancy which will point us in the direction of new physics.”

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