From “Symmetry”: “Reverberations of the Higgs”

From “Symmetry”

DOE’s Fermi National Accelerator Laboratory Wilson Hall.

DOE’s SLAC National Accelerator Laboratory campus with world’s first x-ray laser- the Linac Coherent Light Source (LCLS) unveiled in 2009.

06/21/22
Nikita Amir

Illustration by Sandbox Studio, Chicago with Corinne Mucha.

The discovery of the Higgs boson inspired young people around the world to pursue a career in science and technology.

European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) ATLAS Higgs Event June 18, 2012.

European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH)CMS Higgs Event May 27, 2012.

The Higgs boson is the final predicted piece of the Standard Model, physicists’ best understanding of the elementary particles and forces that underlie our existence.

Standard Model of Particle Physics, Quantum Diaries.

But finding the Higgs particle proved to be a difficult task.

On July 4, 2012—almost 50 years after theorists first predicted the existence of the Higgs boson—scientists representing the CMS and ATLAS experiments at the Large Hadron Collider made one of the biggest scientific announcements in recent memory. They had discovered the Higgs at last.

The news quickly traveled across the planet. Meet four people whose academic and career trajectories were affected by the momentous discovery.

Abhishek Panchal, India

Abhishek Panchal can trace his love for physics back to his days at a boarding school in the Surat district of Gujarat, India. At age 13, during his first year away from his family and friends, he sought refuge in books. In a series he found on famous historical scientists, Panchal first encountered the term “elementary particles.” He fondly remembers flipping back the purple cover of his big Collins Dictionary of Science to look for more information about quarks, protons, hadrons and leptons.

“Science was just something very logical. It was something other than magic, that was like magic for me,” he says. “At the time, I had this dream that when I became a scientist and discovered a new particle, I’d name it Abhion, for my name—yeah, it was very silly.”

A year later, scientists at the Large Hadron Collider at CERN announced the discovery of the Higgs boson. As the news became a talking point among the students around him, Panchal found he had something to contribute to the conversation; he actually knew a thing or two about the particle physics world. “Even people who weren’t into science, they wanted to know about it,” he says. “I think that really helped a lot of people, not just me, to get into science in this field.”

After graduation, Panchal began a bachelor’s degree in physics at the Centre for Excellence in Basic Sciences in Mumbai and quickly jumped into a summer research project with the only particle physicist he knew in the department. He stuck with particle physics until the final year of his degree program, when he took a class in quantum electrodynamics and decided to change course.

Today Panchal is a master’s student in laser plasma physics at the Institut Polytechnique de Paris. His research involves working on a new technique for accelerating electrons. He hopes to apply his research in the emerging field of electron therapy to treat cancer.

“It’s not related at all to whatever I started to do, but I think it’s evolved in a good way,” he says.

Caleb Fangmeier, USA

Caleb Fangmeier grew up on a farm near Lincoln, Nebraska. He thought he had a future in engineering, until an administrative mix-up at the University of Nebraska-Lincoln set his major to physics.

He went with it. And as he started taking classes, he grew more interested in the field.

“One of the lightbulb moments for me was working with a graduate student,” he says. “We had made a couple of plots and I was looking at it like, This is real data that was collected at the LHC. I thought that was so cool and kind of took off from there.”

Fangmeier was a student in the summer of 2012, when rumors swirled about the impending discovery of the Higgs boson. Fangmeier decided to stay up until 2 in the morning, Nebraska time, to tune in for the big announcement.

“It was historic, right?” he says. “It’s one of those moments in the history of physics that only comes once in a while.”

Fangmeier says he thinks that if nothing new had come out of the LHC, then his attention might have shifted to a different part of physics. Instead, the novelty and excitement helped Fangmeier stay dedicated to the field—though, ironically, his interests have shifted back over toward the engineering side.

Today, Fangmeier runs a lab at his alma mater, where he designs detector parts for CMS, one of the two experiments scientists used to discover the Higgs.

Jurina Nakajima, Japan

Jurina Nakajima was 16 when she first learned about particle physics. She went out and bought a copy of the Japanese science magazine Newton to learn more. That same year, news of the Higgs broke, the excitement spread around her peers and teachers as well.

“I remember feeling even more fascinated that there was an undiscovered thing in the world and that we found it,” she says. “I thought, if I study elementary particles, I will also be able to find new particles that no one knows about.”

That interest carried her through her studies all the way to her current PhD program. She is working on research related to the International Linear Collider, a proposed particle accelerator designed to be a “Higgs factory.” It would produce massive amounts of the particle that inspired Nakajima so that scientists can measure it to new levels of precision.

These precision measurements could tell scientists about more than just the Higgs—including whether there are more undiscovered particles hiding out of our view.

Federico Ronchetti, Italy

Federico Ronchetti heard the news about the discovery of the Higgs boson on top of a mountain near Como in Italy, while on a trip with a friend’s family. He was 16 years old.

He didn’t fully understand the significance of the event at the time, but he started looking into it as soon as he got home. Ronchetti was amazed at how people from all over the world—from physicists to engineers to mechanics—came together to make the discovery possible.

In high school, Ronchetti had the chance to visit CERN, the site of the Higgs discovery. He and his classmates ventured underground on a tour of the towering ALICE detector, a sight that helped solidify his love for physics.

Ronchetti enrolled at the University of Insubria, where he developed an interest in medical physics. As a student, he returned to CERN, this time for a month with his research group to perform tests on silicon detectors.

Actually working on detector technology at the home of the LHC steered Ronchetti back toward particle physics. “As someone interested in detector research and development, being at CERN is the best possible thing one can do,” he says.

He completed his master’s degree and is now applying to PhD programs. For inspiration, he keeps a poster on his wall of the moment the Royal Swedish Academy of Sciences awarded the Nobel Prize to theorists François Englert and Peter W. Higgs.

See the full article here .

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Symmetry is a joint Fermilab/SLAC publication.

From “Symmetry”: “Think like a computer”

From “Symmetry”

DOE’s Fermi National Accelerator Laboratory Wilson Hall.

DOE’s SLAC National Accelerator Laboratory campus with world’s first x-ray laser- the Linac Coherent Light Source (LCLS) unveiled in 2009.

05/10/22
Erin Lorraine Broberg

A pilot program, designed in part by educators at Sanford Underground Research Facility, is introducing computational thinking into elementary school curricula.

Illustration by Sandbox Studio, Chicago with Steve Shanabruch.

In Belle Fourche, South Dakota, science teacher Ann Anderson instructs 100 fifth-grade students each day. Recently, they were learning about matter.

Her students were working to find out: Is an empty cup truly empty? How do we know atoms have even smaller sub-components?

Anderson helped students tackle some of these questions through hands-on activities. And after each lesson, she challenged her students to think through how they approached the problem. “Did you take multiple steps to figure this out?” she asked. “Did you ignore some things so you could focus on the important things? Did you look for patterns?”

“The goal is to help young students see computer science as an avenue they could pursue later in life,” says Ben Sayler, lead investigator on the grant and a physical science and mathematics professor at BHSU. “If students at the lower grades are practicing and enjoying it, then when they get to high school and have the option of a computer science elective, they are more likely to feel like that is an option for them.”s? Did you look for patterns?”

These questions are designed to help students understand a concept called “computational thinking”.

Computational thinking is not quite computer science. Rather, it’s a precursor to computer science; it’s the way computer scientists approach the problems that they want to solve using a computer.

Anderson’s students—along with the students of 11 other fifth-grade teachers in South Dakota—are participating in a pilot program designed by educators at Black Hills State University, Sanford Underground Research Facility, and a South Dakota educational resource organization called Technology & Innovation in Education.

The program is funded by a grant as a part of the National Science Foundation’s “Computer Science for All” initiative, which aims to provide all US students with the opportunity to learn about computer science and computational thinking as early as preschool.

“The goal is to help young students see computer science as an avenue they could pursue later in life,” says Ben Sayler, lead investigator on the grant and a physical science and mathematics professor at BHSU. “If students at the lower grades are practicing and enjoying it, then when they get to high school and have the option of a computer science elective, they are more likely to feel like that is an option for them.”

Sharing the magic

Ian Her Many Horses, who along with BHSU’s June Apaza and TIE’s Julie Mathiesen is a co-principal investigator on the grant, knows the utility of learning computing skills early on.

He built his first website—a tribute to Godzilla—as a high school student in the late 1990s at a public university’s summer STEM camp about 200 miles from his hometown on the Rosebud Indian Reservation.

He says learning to make his own site made him feel akin to a pop-culture “hacker.” “It was just a static page, but it felt like magic,” Her Many Horses says. “You just type in a spell and instantly change what happens on the screen. That lit the spark in me.”

When he returned to school, he bought a book titled Learn Visual Basic in 30 Days, convinced a teacher to create an independent study for him, and taught himself the programming language in a semester.

After graduating, Her Many Horses went to The University of Colorado-Boulder to study computer science. His goal was to bring this magic back home. “I wanted students from my community to have the opportunities that I was fortunate enough to have,” he says.

But at the time, most universities—CU Boulder included—did not train students to become licensed high school computer science educators. So Her Many Horses got a license in math education instead, then returned to his hometown as a math teacher and convinced the school’s administration to let him teach one computer science course.

He says designing the course was a struggle.

“I had a great amount of preparation to be a math teacher,” Her Many Horses says. “I understood the theories of learning, how to support students and how to help them think through concepts. But when I tried to teach computer science, I didn’t have that preparation or pedagogical content knowledge. I was teaching it the way I was taught, which at the time was sink-or-swim.”

After a trial run, the course was cut from the school’s offerings.

But Her Many Horses was convinced that the next generation of students would need to start learning these skills before college. He went back to CU Boulder and graduated with the university’s first-ever doctorate in computer science education.

Now, Her Many Horses teaches other computer science educators as a professor at CU Boulder—and works toward systemic changes to support computer science learning, especially in rural classrooms.

Building up to computer science

Computational thinking can be summed up by its four pillars.

First, there’s decomposition, or breaking problems into manageable pieces. Then, there’s abstraction, or identifying non-essential factors and removing them from our thought processes. Third, there’s pattern recognition, or figuring out how things are related. And last, there’s algorithmic thinking, or creating rules to lead to a solution.

To avoid overburdening educators, the new curriculum that teachers in South Dakota are trying embeds these four pillars in the disciplines teachers are already teaching.

“As students investigate science concepts, we have them practice the four pillars,” says Nicol Reiner, director of the education team at SURF and a partner in the pilot program. “In the past, our curriculum didn’t emphasize computational thinking, but the concepts existed in there, silently. Now, we’re calling them out directly.”

Anderson introduced computational-thinking concepts into her science curriculum in the fall of 2021. After nearly a full school year, she says her students can use them to describe their thought processes. “It’s really made students more aware of how they are solving problems,” she says.

The grant project is structured as a researcher-practitioner partnership. The format puts researchers—like Her Many Horses, Sayler and Reiner—and practitioners—like Anderson—on an even playing field. Both groups work together to establish major research questions, define methodology, report on progress, and learn from the results of the research.

The project gathers student perception surveys and educator feedback. Next year, a cohort of fourth grade educators also located around South Dakota will join the pilot group.

Her Many Horses says he wants to spread knowledge of computer science to empower small, rural communities. He sees opportunities for farmers to build sensors that monitor the pH of their soil, for ranchers to use cameras to monitor cattle movement across pastures, and for small businesses to code their own webpages, track their own data and store data privately on their own servers.

He doesn’t want people to have to wait for someone else to invent a solution for them, then be obligated to pay for the service and share data with the service-provider.

“Everybody has an idea in their head of something they think would make lives better, but they don’t know what the next step is,” Her Many Horses says. “There are so many problems in front of us that technology could solve, and I want to help people design solutions for themselves.”

See the full article here .

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Please help promote STEM in your local schools.

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Symmetry is a joint Fermilab/SLAC publication.

From Symmetry: “Double trouble Higgs”

From Symmetry

DOE’s Fermi National Accelerator Laboratory Wilson Hall.

DOE’s SLAC National Accelerator Laboratory campus with world’s first x-ray laser- the Linac Coherent Light Source (LCLS) unveiled in 2009.

04/26/22
Sarah Charley

Illustration by Sandbox Studio, Chicago.

Scientists worried Higgs pairs would be too rare for LHC experiments to find. But by using machine learning, they now are getting tantalizingly close.

In 2011, physicist Javier Duarte and his friends ran the surface roads above the 17-mile circumference of the Large Hadron Collider, a subterranean particle accelerator located on the Franco-Swiss border. They eventually finished the tour, but it took them four increasingly agonizing hours.

“The first half was very pleasant, but the second half was much tougher,” he says. “I hadn’t trained appropriately and was not super well prepared.”

A new pair of running shoes or some carb-loaded snacks might have improved Duarte’s performance—but only slightly. To find his stride and make good time, Duarte needed more than refinement. He needed to fundamentally change his approach to running.

Three years and a comprehensive training program later, Duarte tackled a much longer run: He finished the Chicago marathon in three hours and 15 minutes.

Duarte once again finds himself in a marathon, one with a fixed time limit and a more elusive finish line. He’s looking for evidence of the Higgs self-coupling-a process so rare that scientists have worried they might never discover it at the LHC.

Scientists initially projected that even after combining data from the two general-purpose detectors at the LHC, and even with an upgrade from the LHC to the High-Luminosity LHC, “we would still fall somewhat short of the full concrete observation of this phenomenon,” says Duarte, who is now a professor at The University of California-San Diego and whose research is supported by the US Department of Energy.

To find this rare process—which can only be observed when Higgs particles are produced in pairs—scientists on the ATLAS and CMS experiments needed a new approach. Today, they are rethinking how they filter, process and evaluate their data—a shift they hope will get them across the finish line.

Higgs boson, Higgs field

The Higgs boson is a fundamental particle that was discovered by the ATLAS and CMS experiments in 2012.

European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) ATLAS Higgs Event June 18, 2012.

European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH)CMS Higgs Event May 27, 2012.

Since the Higgs discovery, scientists have tried to learn everything they can: its mass, its traits, its lifetime and how it plays with the other fundamental particles. But one thing scientists have yet to see is how the Higgs interacts with itself. “That is the missing piece,” says Liza Brost, an ATLAS physicist at The DOE’s Brookhaven National Laboratory.

Seeing the Higgs interact with itself will give scientists a window into the Higgs field, an invisible medium that fills the entire universe and is responsible for giving fundamental particles their mass. While scientists have made many measurements of the Higgs boson, the properties of the Higgs field are still mysterious.

“We want to learn more about the Higgs field and in particular, the shape of its potential and what Higgs-field configurations cost the least energy,” says CMS physicist Cristina Mantilla Suarez, a Lederman postdoctoral fellow at The DOE’s Fermi National Accelerator Laboratory. “It sounds theoretical but has huge implications.”

According to Duarte, the shape of the Higgs potential is a kind of cosmic blueprint that guided how the energy that was released during the Big Bang solidified into the stable matter we see today.

“The Higgs is intimately linked to the evolution of the universe, how the universe came to be the way it is, and its ultimate fate,” Duarte says. “The Higgs links big cosmic questions to the microscopic scales.”

A rare event

Even though the Higgs field exists everywhere, Higgs bosons have only a one-in-a-billion chance of materializing during collisions in the LHC. The collisions convert the energy of the colliding particles into mass, momentarily producing new particles.

After more than a decade of operation, scientists estimate that the LHC has generated about 7.5 million Higgs bosons. But they estimate that out of quadrillions of collisions, the LHC has produced only about 4,500 Higgs-boson pairs, which is the only way scientists can see how the bosons interact with one another.

“Di-Higgs production is so incredibly rare, but we know it’s there,” Suarez says. “The challenge is that it is very easily confused with other processes that look the same.”

Higgs bosons are so short-lived that scientists don’t see them directly. Instead, scientists use gigantic detectors to capture and measure the particles that the Higgs bosons produces when it decays.

In the hunt for Higgs boson twins, both CMS and ATLAS have turned their attention to the most common Higgs boson decay product: bottom quarks, which are produced about 58% of the time.

Unfortunately for Higgs researchers, bottom quarks are a favorite decay path for more than just Higgs bosons. “There’s a lot of ways to make two bottom quarks,” Duarte says.

Teasing out the tiny portion of bottom quarks that originally came from a Higgs boson—as opposed to anything else—is remarkably difficult, like a Where’s Waldo? book in which all the characters are dressed in red and white stripes and far too small to see.

Two ways of looking at a Higgs

That’s why researchers at CMS and ATLAS are studying specific subsets of bottom quark events.

Even though Higgs bosons are microscopic, they are not exempt from certain laws of motion. “If I toss a soccer ball to my friend while walking past him, the ball will travel almost perpendicular to my path,” Duarte says. “But if I do this from a car traveling at 60 miles per hour, that soccer ball is going to have a lot of forward momentum.”

Applied to subatomic scales, this means that Higgs bosons with a lot of forward momentum will toss out bottom quarks with a lot of forward momentum. Duarte and his colleagues on CMS realized this could help them.

Because of their unique interactions, Higgs bosons are produced with large momentum more easily than other lighter particles that also produce bottom quarks. So “boosted” bottom quarks are more likely to come from Higgs bosons.

“We get fewer signal events, but we also get fewer background events,” Duarte says. “The ratio increases in our favor. These boosted bottom quarks from the Higgs also look very different from the other sources, which we can use to our advantage.”

In contrast, Brost and her colleagues on ATLAS have been looking to the lower end of the energy spectrum. Brost studies double-Higgs events in which one Higgs boson transforms into a pair of bottom quarks and the other Higgs boson transforms into two photons, the particle form of light. While this process is very rare—only 0.26% of all double-Higgs decays—it’s also phenomenally clear.

“That’s how we designed the calorimeters in our detector; to see photons,” Brost says. “This has been one of our strongest channels.”

Rise of the machines

Scientists are using new sophisticated computational tools to narrow down the search even further.

Traditionally, physicists isolate interesting particle collision events using what Brost calls a “cut and count” technique. She likens it to cutting mold (unwanted background events) off cheese (valuable signal events).

“It’s a problem of how many times we’re willing to slice versus how much cheese we lose,” Brost says.

More restrictive requirements help scientists remove unwanted background events. But it also means they lose more of their signal. To minimize signal loss, physicists have turned to machine learning. A machine-learning algorithm can learn the differences between signal and background and scrape away the uninteresting events with delicate precision.

“The first time we applied machine-learning techniques [on ATLAS data], it blew everything out of the water,” Brost says. “It was so much more sensitive than anybody expected. Then we had to spend the next year or two proving to everybody that it wasn’t wrong.”

On CMS, Suarez was developing machine-learning algorithms for other projects when she realized they could be applied to finding Higgs pairs.

When Suarez first implemented a new algorithm, she was cautiously optimistic. “New experimental tools need to be validated and tested,” Suarez says. “This tool was so new that it wasn’t widely available. It took a lot of work to put it into our analysis and apply it to the data.”

She worried that if she couldn’t get the new software to work, she would have wasted several months with nothing to show. But according to Suarez, “sometimes you have to take the risk.”

Hot on the trail

The risk paid off. With the new software and machine-learning techniques, Suarez and her colleagues discovered that their analysis is just as sensitive as the techniques CMS scientists have been honing for years.

“Any new method can become a significant improvement when we combine them all together, especially long-term,” Suarez says. “We keep developing new ways to probe the Higgs self-coupling earlier and with less data. The sooner we know how strongly the Higgs interacts with itself, the sooner we’ll be able to answer many more questions.”

These new methods are helping ATLAS researchers as well. Brost and her colleagues have been doing back-of-the-envelope calculations to see how their improved particle reconstruction and data filtering will impact their searches for double Higgs bosons during Run 3 of the LHC, which just began.

“We’ve been doing scribbles on the back of the envelope and we’re tantalizingly close,” Brost says. “It’s an exciting time.”

To go from evidence to discovery in this area, scientists predict they will still need the power of the High-Luminosity LHC, which is scheduled to start up in 2029. It will increase the collision rate by at least a factor of 5 throughout a decade of planned operations. With that much more data, scientists will be able to explore in detail how Higgs particles interact with each other.

See the full article here .

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Symmetry is a joint Fermilab/SLAC publication.

From Symmetry: “What’s new for LHC Run 3?”

From Symmetry

DOE’s Fermi National Accelerator Laboratory Wilson Hall.

DOE’s SLAC National Accelerator Laboratory campus with world’s first x-ray laser- the Linac Coherent Light Source (LCLS) unveiled in 2009.

04/22/22
Sarah Charley

Credit: Samuel Joseph Hertzog, CERN.

CERN’s accelerators and the LHC’s detectors have undergone major upgrades that will allow scientists to collect more data in the upcoming run than they did in the previous two runs combined.

The European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) [CERN].

The European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH)[CERN] map.

CERN LHC tube in the tunnel. Credit: Maximilien Brice and Julien Marius Ordan.

SixTRack CERN LHC particles.

The LHC has been shut down since 2018, but that doesn’t mean scientists have been on break. Physicists, engineers and technicians have been upgrading both the accelerator and the detectors to make this next run of the LHC—scheduled to last until the end of 2025—the most powerful yet.

With these upgraded capabilities, scientists plan to collect more data during LHC Run 3 than they did in the first two runs combined. This will allow them to search for rare phenomena and to tackle questions such as how the Higgs boson interacts with itself.

CERN’s accelerator complex

Linac4. Credit: Melissa Marie Jacquemod.

A major goal of the long shutdown was to update and upgrade CERN’s accelerator complex. Starting with the new Linac4, particles are fed into CERN’s accelerator complex, grouped into bunches, and then fed into a chain of increasingly large (and increasingly powerful) accelerators that feed the bunches into the LHC and other experimental areas.

Perhaps the biggest change is that CERN’s accelerator complex will no longer be fed protons, but negatively charged hydrogen ions, each made up of a proton and two electrons. As the ions are injected, the electrons will be stripped off, leaving just the protons. These protons will be joined by more negatively charged hydrogen ions, which will undergo the same process. By repeatedly interweaving negative and positive ions, scientists can create tightly packed bunches of protons. A more compact proton beam will mean more particle collisions per second.

Opening interconnection on magnet in the LHC tunnel. Credit: Maximilien Brice, CERN.

A big upgrade for the LHC itself is planned for the next long shutdown, with the commissioning planned for 2029. During that long shutdown, the LHC will be converted into the High-Luminosity LHC, which will have a collision rate five times greater than the LHC’s original design. But the LHC also underwent some upgrades during this shutdown to prepare it for the more intense beam.

Scientists are especially excited about two new features: The first is a 4.5% increase in energy—from 13 TeV to 13.6 TeV—which will give scientists a boost in their searches for new physics and rare phenomena. The second is a 50% increase in the collision rate combined with luminosity leveling, a process in which the crossing angles and size of the beam are continually adjusted to maintain a steady stream of collisions for around 10 to 15 hours.

ALICE

ALICE detector during the installation of the time-projection chamber. Courtesy of CERN.

Scientists use the ALICE detector to study the hot, dense liquid that filled the universe immediately after the Big Bang. Their goal is to understand the properties of this primordial soup, called a quark gluon plasma, and how it cooled into all the ordinary matter we see today.

ALICE had some of the most major experimental upgrades during the long shutdown. These upgrades will not only prepare ALICE for LHC Run 3, but also for the planned HL-LHC.

ALICE time-projection chamber. Credit: Maximilien Brice, CERN.

A major renovation was the replacement of ALICE’s time-projection chamber. A time-projection chamber is a gas-filled particle detector that uses electric and magnetic fields to affect the path of particles. Judging by how the particles move, scientists can then reconstruct their trajectory, momenta and properties. The new ALICE TPC, which is based on nine years’ worth of R&D, is projected to accumulate 50 times more heavy-ion collision data in the upcoming LHC Run 3 than in Runs 1 and 2 combined.

Installation of the outer layers of the new ALICE inner tracking system. Courtesy of CERN.

ALICE scientists also designed, built and installed a new inner tracking system, a detector that sits close to the point where particles collide. ALICE’s inner tracking system is made from silicon wafers, the same type of sensor material used to make digital cameras. The new detector will significantly increase the resolution of the “pictures” ALICE takes of particle collisions. It has a surface area of 10 square meters, making it the largest pixel detector ever built.

ATLAS

New Small Wheel descent into the experimental cavern. Courtesy of CERN.

ATLAS is one of the two general-purpose experiments at the LHC. Measuring 46 meters (150 feet) long and 25 meters (82 feet) in diameter, it is also the largest detector ever constructed for use in a particle collider.

ATLAS was designed to study the laws of physics and search for new phenomena. After co-discovering the Higgs boson along with the CMS experiment in 2012, ATLAS is now studying the properties of the Higgs and looking for physics beyond the Standard Model, the best model physicists have of the subatomic world.

ATLAS New Small Wheel. Credit: Andreas Hoecker, CERN.

A major renovation at ATLAS during the long shutdown was the replacement of its two Small Wheels. The Small Wheels are detectors designed to catch muons—heavier cousins of electrons. Even though “small” is part of their name, each wheel is 9 meters in diameter (almost 30 feet). These wheels hold 16 wedge-shaped detector slices (which in turn, consist of 16 detecting layers each). The aptly named New Small Wheels will help ATLAS measure the momenta and trajectories of muons created during the high energy collisions inside the LHC.

ATLAS New Small Wheel lowering. Credit: Julien Marius Ordan, CERN.

ATLAS scientists have also updated their detector’s trigger system—which is responsible for quickly filtering the data coming off the detector—and the software that processes, reconstructs and analyzes the data.

CMS

CMS detector. Courtesy of CERN.

CMS is the other general-purpose experiment at the LHC. It is also the heaviest detector at CERN, weighing about 14,000 metric tons (about 15,400 tons).

CMS was designed to investigate the laws of physics at subatomic scales. After co-discovering the Higgs boson along with the ATLAS experiment in 2012, CMS is now studying the properties of the Higgs and looking for new physics and rare phenomena.

CMS BRIL installation. Courtesy of CERN.

During the long shutdown, CMS scientists refurbished the pixel tracker, which sits a mere 2.9 centimeters away from the beam pipe, where particles circulate and collide. Around 600 million particles pass through 1 square centimeter of this inner detector every second. To keep track of the number of particles, scientists upgraded a detector close to the pixel tracker called BRIL, which will monitor the experimental conditions and help scientists calibrate their data.

CMS Gas Electron Multiplier. Credit: Julien Marius Ordan, CERN.

The CMS experiment also completed the installation of their newly designed Gas Electron Multiplier detectors, which will detect muons close to the beam pipe. In addition, CMS scientists have implemented new software to help the experiment quickly filter and process their data.

LHCb

LHCb cavern. Courtesy of CERN.

Along with ALICE, LHCb had some of the most major experimental upgrades during the long shutdown.

The LHCb experiment specializes in studying the properties of composite particles containing bottom quarks (hence the “b” in the name of the experiment). Scientists’ goal is to find deviations from the Standard Model that could help explain big mysteries in physics, such as the imbalance between matter and antimatter in the universe.

Scintillating fiber. Credit: Noemi Caraban Gonzalez, CERN.

Scientists installed a new detector called SciFi, made from 10,000 kilometers (more than 6,200 miles) of optical fiber, a type of material that emits light when a particle interacts with it.

LHCb’s Vertex Locator (VELO). Credit: Maximilien Brice, CERN.

They also installed a new and faster Vertex Locator (VELO), a detector that will sit as close as possible to where the particles collide. What makes the new VELO detector unique is that scientists can lift it out of the way as they prepare the particle beams for collisions, then move it mechanically into place when LHCb is ready to collect data. This will allow scientists to capture clear information from the first particles that radiate from the collisions without unnecessary wear and tear from the beam.

In addition, LHCb scientists have implemented a new data-acquisition system, which will allow them to more quickly and precisely reconstruct what transpired during particle collisions.

See the full article here .

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Please help promote STEM in your local schools.

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Symmetry is a joint Fermilab/SLAC publication.

From Symmetry: “How to make a muon beam”

From Symmetry

DOE’s Fermi National Accelerator Laboratory Wilson Hall.

DOE’s SLAC National Accelerator Laboratory campus with world’s first x-ray laser- the Linac Coherent Light Source (LCLS) unveiled in 2009.

Artwork by Sandbox Studio, Chicago with Steve Shanabruch.

04/12/22
Lauren Biron

For the Muon g-2 experiment, researchers create billions of muons to study their surprising properties.

DOE’s Fermi National Accelerator Laboratory Muon g-2 studio. As muons race around a ring at the Muon g-2 studio, their spin axes twirl, reflecting the influence of unseen particles.

Muons are having a moment. This heavy cousin of the electron made headlines in 2021 when researchers found the particles behaving in ways they didn’t expect. Their movements were not predicted by the Standard Model of particle physics, our best theory about how the subatomic world works.

Standard Model of Particle Physics, Quantum Diaries.

The takeaway? Either the muon is affected by a potential new particle or force that lurks out of sight, or we’re poised to learn something new about one of the particles or forces we already know and love.

Only time will tell. Scientists on the Muon g-2 experiment, hosted by the US Department of Energy’s Fermi National Accelerator Laboratory, continue to gather data and build on their 2021 result.

The precision experiment requires studying the behavior of billions of muons. The particles circulate through a 50-foot-diameter magnetic storage ring, providing data about what’s happening at the tiniest scales. To produce the sheer quantity of muons required, scientists turn to Fermilab’s particle accelerator complex.

How to make a muon beam.

To create muons, accelerator operators at Fermilab send trillions of protons through a series of sophisticated machines, starting with the linear accelerator. It feeds into the Booster, which accelerates the protons from 400 megaelectronvolts to 8 gigaelectronvolts, close to the speed of light. From there, the protons are directed into the Recycler, where the beam is diced into experimentally useful groups called bunches.

About 10 times every second (on average), the bunches of protons smash into a target made of nickel alloy. The collision creates particles called pions. As the pions travel to the experimental hall, they decay into muons and other subatomic particles. A final round of particle selection using magnets prepares the muon beam, which travels along a transport line and into the Muon g-2 experiment.

As the muons travel in the experiment’s magnetic field, they interact with virtual particles, popping in and out of the not-so-empty vacuum of space. Studying how the muons behave allows scientists to rigorously test the Standard Model and see whether the muons are interacting with something they didn’t predict.

Muon g-2’s first result looked at 8 billion muons, only 6% of the total number the experiment will examine at Fermilab. Researchers are currently conducting their fifth experimental run, with plans to switch the polarities of all the experimental magnets and begin collecting data next year using oppositely charged muons.

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Symmetry is a joint Fermilab/SLAC publication.

From Symmetry : “Where do theories come from?”

From Symmetry

DOE’s Fermi National Accelerator Laboratory Wilson Hall.

DOE’s SLAC National Accelerator Laboratory campus with world’s first x-ray laser- the Linac Coherent Light Source (LCLS) unveiled in 2009.

04/05/22
Sarah Charley

Illustration by Sandbox Studio, Chicago.

The catalysts for inspiration are hard work and innumerable connections with a wider scientific community.

It could be the smell of chlorine, or the patterns of light dancing along the bottom of the pool. For whatever reason, the recreation center at the University of The University of California-Riverside is Flip Tanedo’s muse.

“The sparks of creativity show up in the swimming pool, when I’m not pushing myself to think about physics,” says Tanedo, who is a theorist and assistant professor at UC Riverside. “When you turn off your brain, something is still chugging away.”

For Peter Woit, eureka moments arrive during slumber.

“Before going to sleep, I’ll start reading some papers related to what I’m working on,” says Woit, who is a theorist and mathematician at Columbia University. “They put me to sleep fairly quickly. And then I’ll wake up in the morning with some new ideas.”

Stories of sudden revelation make the work of a theorist seem somewhat passive, or even divine. But the bulk of a theorist’s time is spent actively creating the conditions for a new idea to appear.

New ideas for theories come from keeping up with the latest research, trying and failing and trying again, and using all of the wrong turns to map out a clear and convincing path to the right answer.

Absolute immersion

Dorota Grabowska has been a physics enthusiast since childhood. Grabowska still enjoys tossing around ideas with climbing buddies and people on Twitter, as a hobby.

But in college, physics morphed from a hobby into a career.

“I’m 33 now,” says Grabowska, who is a fellow in The European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH)[CERN]’s theory group. “Physics has been my full-time job since I was 18. That’s—oh god—15 years of accumulated knowledge and discussions.”

Those years of effort enabled Grabowska to do theory work beyond dreaming up “what ifs” on the climbing wall.

If someone is serious about developing a new hypothesis, Grabowska recommends they hit the books. “There is such a massive base of knowledge that it can be hard for someone who hasn’t been soaking in the academic physics world to judge the validity of their idea,” Grabowska says. “It’s difficult to come up with a new idea if you don’t know what has already been conceived, tested and discarded. It has nothing to do with innate talent.”

Even for experts, staying current on the latest developments in theoretical physics can be a challenge. Theorist Sophie Renner starts her workday by going online and checking arXiv.org, a continually updated online repository of research papers.

“I’ll skim the titles and abstracts and see if there’s anything I want to read more deeply,” says Renner, who is also a fellow in the CERN theory group. “Most people do this every day because otherwise you’ll miss things. If there’s an interesting paper, you’ll ask your colleagues: Have you read it, and what do you think?”

Finding the right problem

When experimentalists report seeing something unexpected, Renner’s ears perk up.

“It’s an obvious starting point,” she says. “There’s something weird in the data—let’s think about that.”

Renner is currently mulling over odd results from multiple experiments: BaBar, Belle and most recently, LHCb. In certain decays of composite particles called B mesons, scientists have detected slightly more electrons than muons.

SLAC National Accelerator LaboratoryBaBar

KEK Belle detector, at The High Energy Accelerator Research Organization [高エネルギー加速器研究機構](JP) in Tsukuba, Ibaraki Prefecture, Japan.

The European Southern Observatory [La Observatorio Europeo Austral][Observatoire européen austral][Europäische Südsternwarte](EU)(CL) LHCb

“The muon is just a slightly heavier copy of the electron, so the ratio should be the same,” she says. “But they didn’t see that. This is unexpected and beyond our current theory.”

Once she’s identified a potentially interesting anomaly, Renner thinks through the possible implications to home in on a specific and manageable question.

“Maybe there’s some new force or particle which distinguishes between muons and electrons,” she says. “Maybe we can connect it with some other strange measurements. The Muon g-2 experiment is an obvious connection because it also studies muons.”

DOE’s Fermi National Accelerator Laboratory Muon g-2 studio. As muons race around a ring at the Muon g-2 studio, their spin axes twirl, reflecting the influence of unseen particles.

Work with a capital “W”

Once a physicist knows what question to ask, they can start developing and testing possible answers. Tanedo describes this part of the process as, “Work with a capital ‘W.’”

“When I’m not teaching, it’s between 8 and 11 in the morning,” Tanedo says. “It’s early enough that my grad students haven’t woken up, so it’s pretty quiet.”

Tanedo says he uses these morning hours to untangle knotty calculations.

“You start with one tweak of one theory and then hammer everything you can,” he says. “And when you realize that your one, little, dinky theory cannot answer your questions, you realize how your theory fails.”

Repeated failure is an unavoidable part of the creative process of theory building, Tanedo says. “You are defined more by how you fail and how you get up than by how you succeed.”

A moment of clarity

Eventually, Tanedo reaches his limit. “Right around when I’m starting to get hungry is when I hit my maximum grumpiness,” Tanedo says.

He breaks for lunch and then walks across campus to the UCR Recreation Center.

When Renner reaches this point, she takes a stroll through the fields behind the ATLAS experiment at CERN.

The European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH)[CERN] ATLAS. Credit CERN SCIENCE PHOTO LIBRARY.

“If you’re banging your head against a problem, then doing literally anything else is best. You’re doing something else, but the problem still runs in the background.”

When the mind wanders, sometimes a new connection is made. “You can often borrow ideas or techniques from things that seem unrelated,” Renner says.

Renner will suddenly stumble upon a smooth solution to her gnarly problem. But the relief of the moment is short-lived, Renner says. “I find it a bit of an anticlimax because I have a very brief ‘Aha’ moment and then it immediately turns into frustration. I’m angry at myself for not seeing it earlier.”

Making a story

But Renner’s work is not yet complete. Once she has a solid idea, Renner thinks about the best way to articulate it. “I can only really understand it once I can put it into words,” she says.

She condenses the meandering journey into a clear and concise narrative. This can be miles from where she originally started, as often even the question itself has evolved.

“You have to understand what questions have been asked and answered before, and where there are gaps to be filled in,” she says.

During this part of the process, Renner shifts her focus to other theorists and how they might interpret her work. “I might understand it like this, but is this the best way to present it to my reader?” she asks. “And if I’m going to make this point, what plots and data do I need to make it as clear as it can be? This is the process—to get to the point where it seems easy.”

She collaborates with other theorists to work out the details and draft a scientific paper. Then she submits their work to arXiv.org, where even more theorists (and experimentalists) will come across it, perhaps as they peruse the site while having their morning coffee. And the process will start anew.

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Symmetry is a joint Fermilab/SLAC publication.

From Symmetry: “How JWST will test models of cold dark matter”

From Symmetry

DOE’s Fermi National Accelerator Laboratory Wilson Hall.

DOE’s SLAC National Accelerator Laboratory campus with world’s first x-ray laser- the Linac Coherent Light Source (LCLS) unveiled in 2009.

03/22/22
Madeleine O’Keefe

Illustration by Sandbox Studio, Chicago with Olena Shmahalo.

Two projects in JWST’s first observation cycle will probe the nature of dark matter.

On Christmas morning of 2021, an Ariane 5 CEA rocket blasted off from Kourou, French Guinea. It carried with it the largest and most sophisticated space telescope ever built: the James Webb Space Telescope.

National Aeronautics Space Agency/European Space Agency [La Agencia Espacial Europea] [Agence spatiale européenne][Europäische Weltraumorganisation](EU)/ Canadian Space Agency [Agence Spatiale Canadienne](CA) James Webb Infrared Space Telescope annotated, finally launched December 25, 2021, ten years late.

Since then, JWST has reached its orbit about 1 million miles from Earth, unfurled its tennis-court-sized sunshield, and aligned its 18 hexagonal mirror segments. The telescope’s first images are expected by summer.

Over the next decade, JWST will make cutting-edge observations to help scientists answer myriad outstanding questions in astronomy—including questions about the nature of dark matter.

Illustration by Sandbox Studio, Chicago with Olena Shmahalo.

Hot, warm or cold

Dark matter is an enigmatic substance that scientists believe accounts for 85% of matter in the universe. But so far it has not been observed directly; scientists can infer dark matter’s presence only by observing its gravitational effects on normal matter.

Different theories posit different types of dark-matter particles. Dark-matter candidates considered “hot” or “warm” are particles that would have moved so quickly in the early universe that gravity would not have been able to confine them. On the other hand, dark-matter candidates considered “cold” are thought to have moved so slowly that gravity would have formed them into small dark-matter structures that eventually would have coalesced into larger, “clumpy” ones.

“Decades’ worth of computer simulations have tested how structure forms and grows under the hypothesis of cold dark matter,” says Matthew Walker, an associate professor of physics at Carnegie Mellon University.

Cold dark-matter simulations show dark matter clumping into small blobs, which encounter other blobs and merge together, continually snowballing until large structures like the Milky Way are formed. These gravitationally bound blobs of dark matter are known as halos.

Caterpillar Project A Milky Way size Dark Matter halo and its subhalos circled, an enormous suite of simulations. Griffen et al. 2016.

JWST can see your halo

Anna Nierenberg, assistant professor of physics at The University of California-Merced, was awarded 39 hours of observing time during JWST’s Cycle 1 to look for small dark-matter halos.

Many models, including the baseline dark-matter model, predict the existence of small (107 solar mass) halos that do not actually contain galaxies. Such a halo would “just be a blob of dark matter” with no stars inside it, Nierenberg says.

If there are no stars within these blobs of invisible material, how can we even try to detect them? Nierenberg and her team of nearly 20 scientists in the US, Canada, the United Kingdom, Switzerland, Spain, Belgium and Chile are using a phenomenon called gravitational lensing.

Gravitational Lensing National Aeronautics Space Agency and European Space Agency [La Agencia Espacial Europea][Agence spatiale européenne][Europäische Weltraumorganisation](EU).

PhysRev.133.B835″Gravitational microlensing, S. Liebes, Physical Review B 133.B835, 133 (1964): 835.

Born of Albert Einstein’s Theory of General Relativity, gravitational lensing says that matter bends spacetime and, subsequently, any light that encounters it. If light from a distant source travels through the universe toward Earth and passes by a massive object—such as a blob of dark matter—the light will be warped around it. If the in-between object is massive enough, the light is deflected in such a way that we’ll see up to four images of the light source appearing around the mass.

Nierenberg’s group will measure the number of small dark-matter halos by observing a sample of quasars (supermassive black holes at cosmological distances surrounded by dusty accretion disks) that have been gravitationally lensed. Detecting small halos would be a triumph for the cold dark-matter theory; conversely, not detecting small halos would imply that cold dark matter does not exist.

Because the light from these quasars must travel a great distance in an ever-expanding universe, it is stretched along the way, pulling its wavelengths into the infrared range. The mid-infrared wavelengths they are observing are almost impossible to see with ground-based telescopes. “We’re going to be observing with absolute reddest bands that JWST can accommodate,” Nierenberg says.

These wavelengths cannot be observed by the Hubble Space Telescope, which studies gravitational lensing at visible wavelengths. And older space-based telescopes that can see in the mid-infrared don’t have the resolution to separate the different lenses. Making these observations in mid-IR requires the high spatial resolution that only the JWST can provide, Nierenberg says.

Daniel Gilman, a postdoc at The University of Toronto (CA) and one of Nierenberg’s co-investigators, says, “The kind of data that we can get with JWST is unique and much more powerful or constraining than the kind of data that we could get with Hubble or from the ground.”

Nierenberg says, “I really believe that this is going to be a huge scientific step forward.”

Looking far and wide

Walker is leading another dark-matter project in JWST’s Cycle 1, but his group didn’t apply for observing time. Instead, they are using data that JWST is collecting for other programs.

Walker’s group’s “archival research” is looking inside dwarf galaxies to find wide binary stars, systems of two stars orbiting each other at relatively large distances (on the order of one parsec, slightly less than the distance between the sun and our closest neighbor, Proxima Centauri).

“Because [wide binary stars] are so far apart, they’re very fragile systems,” says Walker. “If, say, a little dark-matter halo were to fly past a wide binary-star system, it could exchange energy with either or both of the stars in that system. And it just takes a small fraction of a fraction of a percent increase in the energy of either star to rip the pair apart.”

If Walker’s team finds wide binary stars, “we can be reasonably confident that those sub-galactic cold dark matter halos don’t exist,” he says. “And that, then, would be a real problem for the cold dark-matter model in general.”

Lamda Cold Dark Matter Accerated Expansion of The universe http://www.scinotions.com the-cosmic-inflation-suggests-the-existence-of-parallel-universes. Credit: Alex Mittelmann.

That’s what Katharine Lee, a junior physics major at Carnegie Mellon University in Walker’s group, likes about the project. “I particularly think this research is really interesting because the current framework for what we think of as the structure of dark matter is the cold dark-matter model, and the research that Professor Walker’s doing could potentially invalidate that.”

If the group did not find wide binary stars, it could be a sign that they were destroyed by dark matter. But it would not prove that they were destroyed—they may just have never formed in these dwarf galaxies in the first place.

Walker says that JWST is an ideal tool for this search because of its “exquisite sensitivity to faint objects,” as well as the telescope’s abilities to take high-quality images and distinguish pairs of sources at very small separations. And thanks to its 21-foot-diameter primary mirror, JWST will see farther than any other telescope ever built.

“I think JWST is going to give us a new and really powerful angle,” says Jorge Peñarrubia, a professor at The University of Edinburgh (SCT) and one of Walker’s co-investigators. “But even if that fails, we’ll find other ways.”

Indeed, there are many other techniques that scientists use to search for dark matter, including direct searches by physics experiments. And both Nierenberg and Walker are using gravitational lensing and wide binary-star methods on data from the Hubble Space Telescope while they wait for JWST to open its eyes.

Future JWST science programs might further explore the mysteries of dark matter, whether through gravitational lensing or perhaps by observing statistics of galaxy evolution that scientists can then compare to dark-matter theories.

“We don’t lack theories of what dark matter could be. There are a lot of them,” Gilman says. “What we lack are observations that wield a lot of constraining power over these theories. And that’s something that JWST is going to give us.”

See the full article here .

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Symmetry is a joint Fermilab/SLAC publication.

From Symmetry: “Building for Science and Society” Elaine McCluskey, project manager extraordinaire, retires.

From Symmetry

DOE’s Fermi National Accelerator Laboratory Wilson Hall.

DOE’s SLAC National Accelerator Laboratory campus with world’s first x-ray laser- the Linac Coherent Light Source (LCLS) unveiled in 2009.

03/15/22
Nikita Amir

The career of Elaine McCluskey, who most recently served as project manager constructing the future facility for the Deep Underground Neutrino Experiment, has had a lasting impact.

Elaine McCluskey, project manager extraordinaire, retires.
“Elaine has put her heart and soul into moving this project forward, overcoming countless challenges,” said Chris Mossey, project director of LBNF/DUNE-US. “LBNF/DUNE simply would not be where it is today without Elaine’s extraordinary dedication and leadership.” Photo: Sanford Underground Research Facility.

As a child, Elaine McCluskey liked to make things. Growing up in the 1950s and ’60s, this translated into hobbies considered appropriate for girls: making crafts, sewing clothes and cooking.

“I even made my own prom dress pattern,” she says.

At school, her interest translated into a passion for math and science. As she neared graduation, her father, an electrical engineer, encouraged her to enroll in a joint undergraduate degree in physics and civil engineering.

She spent three years at Carleton College in Minnesota before transferring to Washington University in St. Louis.

“I was very much encouraged by my parents to never feel like I couldn’t go do something,” she says. “It was very, very important that I felt empowered to go and do whatever I want, wherever I wanted to do it.”

That encouragement helped her weather the challenges of finding her way in a male-dominated field. The career she built touched the lives of many, ranging from students and educators to medical professionals and patients to physicists and engineers.

From small cohort to smaller cohort

At Carleton, McCluskey studied physics in a class about a third of which was made up of women. This was unusual; when she graduated in 1976, women were awarded just 11% of bachelor’s degrees in physics in the United States, according to the American Institute of Physics.

The ratio was different when she studied civil engineering in St. Louis. In 1978, the year she earned her second degree, women earned just 8.9% of bachelor’s degrees in engineering in the United States, according to the National Science Foundation.

There were barely any other women in civil engineering, McCluskey says. At the meetings for the American Society for Civil Engineers, there were only five women in her cohort. They were unable to wear the name tags the society provided, as the tags were designed to be slipped into a suit jacket pocket.

“‘I don’t have a suit jacket, and I don’t have a pocket to put that in, what can we do about that?’” she asked the organizers. After she brought it up, they switched to pin-on name tags instead. “I felt that was quite a victory for myself,” she says.

Later in her career, McCluskey became an engineering consultant. She says that the number of women around her dropped even further; she was often the only one in the room. McCluskey made do with the support she could find.

“I’ve often had men who are my confidants or my professional role models, just because there aren’t women there to do that. And so oftentimes, I would rely on just personal friends to talk through things.”

Building for society

It was in college that McCluskey figured out exactly what she wanted to do.

She remembers watching through her dorm window as workers poured the foundation for a new building. She says that at the time, she wondered: How do they know it’s going to stand up? Who decided that that amount of concrete in that shape is the right thing to do?

McCluskey says she was taken by “the whole business of eventually creating this beautiful building.”

For McCluskey, civil engineering is all about helping people. It’s about building structures and systems so that a society can function. “Civil engineering is very much in the fabric of what a society needs in order to be in a good place.”

Over her career, she has built schools, hospitals, and even a reinforced support for the statue of the goddess Ceres atop the Chicago Board of Trade.

“To me, designing a school and a hospital, those are fundamental things that everybody needs,” McCluskey says. “And if I can make a school that’s going to last a long time and be really useful for our community, then I feel a lot of reward driving by that school, knowing that I’ve done something that can help a lot of people.”

As she gained experience, McCluskey became interested in taking on new challenges as well. That’s when she heard about a job at the DOE’s Fermi National Accelerator Laboratory. After initially working part-time, she was hired full-time by the Facilities Engineering Services Section in 1995.

Civil engineering requirements for different projects are often pretty similar. Not at Fermilab, though. “The scientists want to do an experiment and maybe change the matrix and change our thinking about the world,” she says. “It’s the passion that comes with the work that really drives us to want to continue to do what is sometimes very hard or something that’s not been done before.”

One of her first projects was one of her most challenging: the remodeling of the laboratory’s main building, Wilson Hall [above]. Inspired by a cathedral, it consists of two concrete sides that slope gently together as they reach more than 200 feet in the air. The hall is visible from most of the lab’s flat 6,800-acre site.

The problem was that the iconic building had begun dropping small pieces of concrete. McCluskey and her team set to work rebuilding parts of the hall floor by floor, replacing windows, skylights, water piping and the entire front entrance. To make things more complex, the project needed to be completed while the building remained occupied, so much of the work happened at night.

McCluskey says that for years afterward, she took pride in checking every time she walked by to make sure everything was in perfect condition.

McCluskey made sure that everyone on a project could take that same pride in their work, says fellow project manager Jolie Macier, who started working with McCluskey in those early days. The key was giving her team the guidance they needed to work independently.

But she also found ways to help team members work well together, Macier says. During Women’s History Month a few years ago, McCluskey brought in a puzzle celebrating women in science and engineering. “It provided this meeting point over the course of a couple of days for people to stop and talk with each other,” Macier says. “It obviously wasn’t only about the puzzle. It was more about this moment and creating this interaction.”

During the winter, McCluskey would bring amaryllis to the office. She would nurture them at home before sharing them in the winter, the only time of year when their flowers bloom.

“Everything isn’t just about working on the to-do list, but really looking at ways that help people feel like they’re part of something,” Macier says.

For the last 12 years, McCluskey has worked as project manager on one final, adventurous build for Fermilab: the beamline and cavernous homes for the huge particle detectors of the international Deep Underground Neutrino Experiment, the lab’s flagship LBNF/DUNE project.

DOE’s Fermi National Accelerator Laboratory DUNE LBNF from FNAL to Sanford Underground Research Facility, Lead, South Dakota, USA.

DOE’s Fermi National Accelerator Laboratory DUNE LBNF Caverns at Sanford Underground Research Facility.

More than 1,400 scientists and engineers from over 35 countries are collaborating on DUNE. The experiment needs a facility that produces a neutrino beam and sends it straight through the earth to the DUNE detectors, first at the Fermilab site, and then 800 miles away to a former-mine-turned-underground-laboratory in Lead, South Dakota. There, shielded underground to better study subatomic particles, scientists aim to discover what role neutrinos play in the universe.

“Elaine is the rock that held the LBNF/DUNE project together for a decade and advanced it to where we are today,” says Fermilab Director Nigel Lockyer. “Her even-keel approach to problem solving was masterful and highly appreciated in a difficult project.”

Chris Mossey, project director of LBNF/DUNE-US, agrees. “Elaine has put her heart and soul into moving this project forward, overcoming countless challenges. LBNF/DUNE simply would not be where it is today without Elaine’s extraordinary dedication and leadership.”

About 800,000 tons of rock need to be moved to create the underground space for the DUNE detectors at the Sanford Underground Research Facility. Excavation is underway. When complete, the new Long-Baseline Neutrino Facility at SURF will have a total floor space of about the area of two soccer fields. The facilities will include large cryostats, underground nitrogen refrigeration and argon recirculation systems.

That work will need to be completed without McCluskey, though; in February, she announced her retirement.

But she isn’t turning her back on her passions. She still serves as a volunteer in the Frank Lloyd Wright Trust, an architectural nonprofit in Chicago. And in June, McCluskey plans to meet up with fellow Carleton physics alumni for a reunion they hold every five years.

“It’s always a special time for the physics majors to get together,” she says, “and those women from that physics year are always there.”

See the full article here .

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Symmetry is a joint Fermilab/SLAC publication.

From Symmetry: “Beyond the Standard Model”

From Symmetry

02/22/22
Katrina Miller

Illustration by Sandbox Studio, Chicago with Corinne Mucha.

Standard Model of Particle Physics, Quantum Diaries.

The Standard Model is one of the most well-tested theories in particle physics. But scientists are searching for new physics beyond it.

Humans have always sought to understand the essence of the world around them. Ancient civilizations believed everything was composed of basic constituents like earth, air, water and fire; in the 1800s, these classical elements gave way to a meticulous record of over a hundred chemical elements, known today as the modern periodic table. The discovery of the electron in 1897 ushered in a new era, as scientists realized that the true building blocks of nature were even smaller than they had thought.

Since then, a slew of subatomic particles has been discovered and organized into a theory called the Standard Model, which impressively describes the properties and behavior of the matter surrounding us in a single, albeit hefty, mathematical equation.

“The Standard Model is scientists’ best guess at explaining the universe,” says Don Lincoln, a physicist at the US Department of Energy’s Fermi National Accelerator Laboratory.

DOE’s Fermi National Accelerator Laboratory (US) Don Lincoln

Since its formulation in the early 1970s, the Standard Model has predicted the outcome of countless experiments in particle physics with remarkable accuracy. Its most recent addition, the Higgs boson in 2012, rounded out the model by shedding light on how subatomic particles gain their mass.

European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) ATLAS Higgs Event June 18, 2012.

European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH)CMS Higgs Event May 27, 2012.

“It’s simply the most successful theory we have for explaining the behavior of the matter we see,” Lincoln says.

Why, then, are scientists so intent on discovering physics beyond the Standard Model?

“We have a precise model of only a small sliver of reality,” Lincoln says. “And there are a lot of unexplained mysteries,” ones that can’t be understood within the Standard Model’s tried-and-true mathematical framework.

Perhaps the most intriguing puzzle is the relative lack of antimatter found in the universe. Antimatter is composed of particles with certain properties, like charge and spin, flipped from their ordinary matter counterparts. According to the interactions of the Standard Model, the birth of our universe should have produced matter and antimatter in equal amounts—but somehow, that balance was tipped to create the matter-dominated world we live in today.

Another hint that there is physics beyond the Standard Model is that the theory does not account for Dark Matter, which physicists believe to be five times more prevalent than visible matter in the universe. While Dark Matter has never been directly observed, ample evidence of its presence exists. For example, scientists think the gravitational pull of dark matter causes galaxies to rotate at speeds unexplainable by the influence of the matter we can see.

“It’s what holds the universe together,” says Marcela Carena, a theoretical particle physicist at Fermilab. “But we have no clue what it’s made of, or why it is there at all.”

Attempts to decipher these mysteries require deep collaboration between the theoretical and experimental sides of particle physics, says Flip Tanedo, a physicist at the University of California-Riverside who works on understanding the nature of Dark Matter.

Many physicists think that new additions to the Standard Model will be part of a hidden “dark sector” of particles that interact only rarely, if at all, with the matter we are familiar with. But proving this hypothesis will take concrete experimental evidence. Any observation that doesn’t agree with Standard Model predictions is a clue. But only after scientists make rigorous checks—to confirm that it cannot be explained away by a fluke in the data or an error in theoretical calculations—is it a smoking gun. Once both of those paths have been ruled out, Carena says, “then the explanation for the discrepancy must be something new.”

“We are at an amazing time in history,” Carena says, because of the sophisticated technology available to explore past the limits of current understanding. “We have such amazing tools, and very powerful mathematical methods, to learn about our universe and about ourselves.”

Nonetheless, it’s improbable that physics will ever reach a point so far beyond the Standard Model that the theory gets replaced entirely by something new. “There are pieces missing in the puzzle,” she says. “But we’re not going to throw away all the pieces that already fit so well together.”

Tanedo agrees: “A theory is a model of nature, not a definition of what nature is,” he says.

What’s more likely is that the Standard Model will be regarded as effective at only certain scales and energies, similar to how chemistry describes atomic structure without much need for the mathematics of particle physics. “I wouldn’t pick up a subatomic particle physics textbook to understand the periodic table of elements,” Tanedo says.

With so much of the matter and energy in our universe left to unravel, the search for physics beyond the Standard Model is a journey ripe for discovery. “The ocean of what we don’t understand is far more vast than the little pond in which we’ve explored,” Lincoln says. “Anyone who wishes to explore this sea of knowledge can get on a boat and sail away.”

See the full article here .

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Please help promote STEM in your local schools.

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Symmetry is a joint Fermilab/SLAC publication.

From Symmetry: “What is annihilation?”

From Symmetry

02/15/22
Graycen Wheeler

Artwork by Sandbox Studio, Chicago.

In particle physics, “annihilation” is a transformation.

When you hear the word “annihilation,” you might think of a Marvel Comics storyline, or perhaps the first book in the Southern Reach Trilogy. Or you might just think of the dramatic common definition of the word: destruction to the point of non-existence.

To particle physicists, annihilation has a different meaning.

Annihilation occurs when a bit of matter meets up with its corresponding bit of antimatter. What happens is not destruction; it’s transformation.

What emerges on the other side of the annihilation process is a new pair of particles. They can have the same identities as before; they can transform into a brand new particle-antiparticle pair; or they can convert entirely into photons, particles that carry electromagnetic energy.

Governing this reaction (and, in fact, all reactions) is the principle that energy cannot be created or destroyed. That includes energy in the form of any matter with mass. “We’re happy with E=mc2, so mass is energy,” says Flip Tanedo, a theoretical particle physicist at the University of California-Riverside.

But mass is not the only form of energy. There’s also kinetic energy—energy related to motion—and radiant energy—electromagnetic energy in the form of photons.

When two particles undergo annihilation, the energy of whatever they become must be the same as the energy of the original pair.

To illustrate this, Tanedo asks you to picture two big, chunky particles: a bowling ball and an anti-bowling ball. “They’re just sitting around because they’re so heavy,” he says. “But if these two bowling balls annihilate and turn into two billiard balls, then those billiard balls have to be moving really fast [and thus have a lot of kinetic energy] to make up for the difference in mass.”

Quantum leaps

Our journey to understanding annihilation began in 1928, when British physicist Paul Dirac first predicted the existence of antimatter.

Dirac was developing an equation to describe an electron’s movement when he noticed an intriguing mathematical quirk: His equation worked as intended to describe a particle with all the properties of an electron. But it could also work if all those properties were multiplied by -1, implying the existence of a particle that behaved exactly like an electron but with all its quantum properties mirrored.

Four years later, an American professor named Carl Anderson observed the particle Dirac had predicted, the positron. Anderson was using a cloud chamber—a device that allowed him to see ionizing subatomic particles by eye—to observe the high-energy cosmic rays that constantly bombard Earth from space. Anderson spotted an unusual particle making its way through the cloud chamber. It had the same properties as an electron, but the way it curved in a magnetic field implied that it had a positive charge.

A year later, in 1933, physicists observed that when a positron emerged from the cosmic rays in a cloud chamber, it was always accompanied by an electron spiraling in the opposite direction from the same point. In this process, dubbed “pair production,” electromagnetic radiation converts into a particle-antiparticle pair.

Physicists quickly began to search for the reverse process, in which electrons and positrons might be converted into energy instead. By the mid-’30s, several groups [European Physical Journal H] had experimentally observed this process: We had annihilation.

As far as humans have seen, whenever energy converts into matter, the same amount of antimatter appears. The universe should be filled with equal amounts of matter and antimatter—or just a sea of photons left over from matter-antimatter annihilation.

But for reasons physicists don’t understand, our universe ended up with an imbalance that heavily favors matter instead.

“Based on what we know about the laws of physics, if the universe has one gram of matter, there should be one gram of antimatter,” Tanedo says. “But that’s not what we see, we just see a whole bunch of matter and [almost] no antimatter. There’s some weird asymmetry.”

Annihilation and you

To a particle physicist, asking what makes annihilation cool is like asking someone to wax poetic about covalent bonds or elastic collisions. “It’s kind of a funny question,” Tanedo says. “This is just one type of reaction, and there’s nothing special about this reaction versus any other.”

Annihilation happens all the time. Unless you’ve literally been living under a mile of rock, you’ve been bombarded with cosmic rays like the ones Carl Anderson was observing when he first saw the positron. These and other high-energy astronomical events convert energy into equal amounts of matter and antimatter. But in our matter-full universe, the lonely antiparticles are quick to find their reciprocal matter particles and annihilate back into photons.

But annihilation doesn’t just occur in space. On Earth, rare potassium atoms found in all plant and animal tissue—especially that of potassium-rich bananas—occasionally produce positrons through radioactive decay.

Scientists have even figured out how to produce antimatter in the lab. But it’s expensive and energy-consuming to do; in more than half a century, scientists at accelerator laboratories such as The European Organization for Nuclear Research [La Organización Europea para la Investigación Nuclear][Organisation européenne pour la recherche nucléaire] [Europäische Organisation für Kernforschung](CH) [CERN] and DESY Electron Synchrotron[ Deütsches Elektronen-Synchrotron](DE) in Europe and The DOE’s Fermi National Accelerator Laboratory (US) have collectively created less than a couple dozen nanograms of the stuff. Accelerators such as the Large Electron-Positron Collider at CERN and the Tevatron at Fermilab ran beams of matter and antimatter through one another to release energy via annihilation.

CERN Large Electron Positron Collider

FNAL/Tevatron CDF detector

FNAL/Tevatron DØ detector

The energy from those annihilations converted into matter, producing previously undiscovered particles.

Matters of great import

For how ordinary it might seem to particle physicists and astrophysicists, annihilation is still important in their research.

Some particles, like photons, act as their own antiparticles. Scientists are studying neutrinos to find out if this is the case for them, too. Learning that neutrinos can annihilate with other neutrinos could give scientists an important clue in the mystery of the imbalance between matter and antimatter in the universe.

Astrophysicists have posited that annihilation could help us to indirectly detect particles of dark matter, which have made their presence known only via the pull of gravity. If dark-matter particles and antiparticles annihilate, they could convert their energy into a more easily detectable form.

“We live in an ocean of dark matter, so maybe we should be looking for its annihilation products,” says Tanedo, who specializes in dark-matter research.

In 2009, the Fermi Gamma-ray Space Telescope detected unexpected diffused gamma-ray radiation coming from the center of the Milky Way.

National Aeronautics and Space Administration(US) Fermi Gamma-Ray Large Area Telescope.

National Aeronautics and Space Administration(US)/Fermi Gamma Ray Space Telescope.

The physicists who observed this extra radiation initially suspected it was a product of dark-matter annihilation—and the math checked out.

But since then, astrophysicists haven’t found evidence to support this explanation. The energy could be coming from another source, such as pulsars or a black hole. A newer detector, the Alpha Magnetic Spectrometer, has detected some positrons of mysterious origin, but there’s no decisive evidence that they are the result of dark-matter annihilation.

Still, dark-matter annihilation could be happening out there, and physicists are keeping an eager eye out for it. “The mystery has stayed fun,” Tanedo says.

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

Symmetry is a joint Fermilab/SLAC publication.