Starting from the bottom

The bottom quark may lead physicists on a path to new discoveries.

metaphorical approach, person reading “standard model” keep getting bonked with apples labeled as different experiments

The Standard Model of particle physics has been developed over several decades to describe the properties and interactions of elementary particles. The model has been extended and modified with new information, but time and again, experiments have bolstered physicists’ confidence in it.

And yet, scientists know that the model is incomplete. It cannot predict the masses of certain particles, nor can it explain what most of the universe is made of. To discover what lies beyond the Standard Model, scientists are searching for its flaws—untenable assumptions and phenomena that it does not predict. A growing set of results from the study of bottom quarks may offer physicists a welcome chance to do just that.

“The Standard Model is very rigid,” says Marco Nardecchia, a theorist from Italy, “so the best way to break it is by precisely testing its predictions.”

The Standard Model makes many detailed predictions about how particles should interact or decay. Some subatomic processes are so complicated that even theorists aren’t quite sure exactly how they are supposed to work. For one: quarks—the constituents that make up elementary particles—should interact in the same way with the electron as with its heavier cousins, the muon or tau lepton. 

There are six types of quarks. The lightest and most common are the up and down quarks, which together make up protons and neutrons. Particles carrying a bottom quark—which is much heavier—are short-lived. In their decays, the bottom quark transitions into a lighter quark, preferentially a charm quark and rarely an up quark, forming another known particle.  

The remaining energy is carried by a charged lepton: an electron, a muon or a tau, each accompanied by its associated neutrino. According to the Standard Model, the rates of producing electrons, muons and taus differ only due to the very different masses of these three charged leptons. (The tau mass, for example, exceeds the electron mass by a factor of about 3500.)

“These predictions are straightforward and precise,” says Vera Lüth, a scientist on the Babar experiment, “which is why we decided to pursue these measurements in the first place.”

Scientists working on three different experiments are testing these predictions by examining specific decays of particles that carry a bottom quark. 

The first hint of an unexpected tau enhancement appeared in 2012 at the BaBar experiment at SLAC National Accelerator Laboratory, which studied close to 500 million events produced in electron-position collisions, and reconstructed less than 2000 decays involving taus. In 2015, the Belle experiment in Japan reported a similar enhancement in the tau rate in data collected from electron-position collisions at the same energy.

“A friend working on another experiment was sure that we had done something wrong,” Lüth says. “Then they observed the same effect.”

In 2015, scientists working on the LHCb experiment operating at CERN saw signs of the same phenomenon in very large samples of proton-proton collisions at much higher energy and collision rates. 

“All these results point in the same direction,” says Hassan Jawahery, a professor at the University of Maryland working on LHCb. “That’s what puzzles everyone.”

On their own, these individual results have a significance below the level that would raise an eyebrow. But together, they are “intriguing,” according to Tom Browder, the spokesperson of the Belle experiment and its successor, Belle II. “We are pretty sure that something new is out there. Proving even a tiny deviation from the  Standard Model could lead to a revolution in our field.”

The results accumulated so far have already inspired theorists to speculate about what kind of new physics processes might cause these enhancements. 

Some theories suggest that perhaps there is a yet undiscovered charged Higgs boson which favors the heavy tau over the much lighter muon and electron. Other models predict the existence of at least one new particle outside the Standard Model. “We may need something which interacts with quarks and leptons simultaneously,” Nardecchia says. 

Scientists won’t know what’s happening without further study, and gathering enough data to allow more detailed and precice studies will be a crucial step toward to find out.  

Scientists at the LHCb experiment are only at the beginning of this study. They plan to analyze about four times as many events in the next few years. They hope to complete new and updated measurements by this summer. The LHC accelerator complex program foresees major upgrades that will enlarge the experiments’ datasets over the next decade. In parallel, Belle II is scheduled to start collecting data in 2019 and is expected to record enough to shed light on this query in a few years. 

Physicists around the globe are eagerly waiting to compare notes.

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Global Physics Photowalk 2018

Eighteen physics facilities will give photographers a behind-the-scenes look at science.

Person wearing an orange jacket takes a picture of a room full of equipment from a catwalk.

Major science laboratories from around the world today announced a Global Physics Photowalk competition that will be open to amateur and professional photographers. Physics facilities in Asia, Australia, Europe and North America will open their doors for a rare opportunity to see behind the scenes of some of the world’s most exciting and ground-breaking science.

The photowalk will involve local and national competitions, with the winning national photos submitted to a global judging panel. The program is organized by the Interactions Collaboration and supported by the Royal Photographic Society (RPS). The global shortlist will be announced in August, followed by a public vote.

Confirmed locations include CERN, the home of the Large Hadron Collider; underground laboratories in the US, Australia and the UK; and labs and facilities in Italy, the UK, the US, Canada, and—for the first time—China.

“This is a fantastic celebration of the stunning beauty of science on an international scale," says Mark Richardson, Chair of the RPS Science Committee. "The world’s best scientific research is based on international collaboration, a worldwide melting pot of expertise and technologies, each working for the benefit of our global society and economy. The photowalk is a rare opportunity to capture work behind the scenes at the world’s best international laboratories and capture it, frame by frame.

The international competition will include the following laboratories:

Places for each photowalk are limited and are strictly by registration only.

Details about the facilities and local photowalks can be found by clicking on the links above, and you can follow along on social media with #PhysPics18. A selection of winning images from previous photowalks is available here

Editor's note: this article was adapted from a press release by the Interactions Collaboration.

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DUNE collaboration elects new co-spokesperson

University of Manchester’s Stefan Soldner-Rembold will join Edward Blucher of the University of Chicago as co-spokesperson.

The next two years are pivotal for the Deep Underground Neutrino Experiment, the international particle physics experiment hosted by the US Department of Energy’s Fermi National Accelerator Laboratory.

In a vote earlier this month, the DUNE collaboration elected Stefan Soldner-Rembold, professor of particle physics at the University of Manchester, as its new co-spokesperson to help guide the experiment through these next two years. Soldner-Rembold has experience leading a large collaboration—he was co-spokesperson of the 500-member DZero experiment at Fermilab from 2009 to 2011—and has been working in neutrino physics for more than a decade.

Soldner-Rembold has served in several leadership positions within the DUNE collaboration, including chair of the Speakers Committee, and was elected as a member of the DUNE Executive Committee in 2016.

Two prototype detectors for DUNE are scheduled to be completed at CERN in Switzerland later this year, and technical design on the experiment’s full-size detector will be worked out over the next 18 months. The DUNE collaboration continues to grow—it currently includes more than 1,000 members from 31 countries—and continues to attract young minds from around the world, eager to contribute to this global-scale neutrino experiment.

“This is a formative period for DUNE,” Soldner-Rembold says. “What we decide now will shape the detectors and the way the collaboration works for the next 10 to 20 years. I’m thrilled to be stepping in as co-spokesperson during such an exciting time.”

It’s also a time in which the UK’s contributions to DUNE are ramping up. The UK has committed $88 million to the construction of the experiment (including the facility that will house it and the accelerator upgrades that will power it), and Soldner-Rembold is currently leading the UK-US consortium designing and constructing vital components of the DUNE detector. Prototypes of these components are currently being installed in the ProtoDUNE detectors under construction at CERN, another major partner in DUNE.

“To build the world’s best neutrino detector, we need to attract further international partners,” Soldner-Rembold says. “The election of an international co-spokesperson sends a signal to other countries that this is an interesting and exciting project that they should join and commit to.”

Over the next few years, Soldner-Rembold says, it will be important to continue to encourage young scientists to participate in DUNE.

“In order to create a vibrant and strong collaboration, we need to encourage the next generation of young physicists to be engaged with the project,” he says.

Soldner-Rembold will take over the position from Mark Thomson of the University of Cambridge and will join Edward Blucher of the University of Chicago as co-spokesperson.

“I look forward to working closely with Stefan,” Blucher says. “His wealth of experience will prove invaluable as the DUNE collaboration navigates the exciting years ahead.”

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LHC exhibit expands beyond the visual

The touring Tactile Collider event explores new ways to access Large Hadron Collider science through touch, sound and live interaction.

View of the LHC for people with visual impairments

The world of particle physics is invisible to the naked eye, existing at a scale that’s almost inconceivably small. Stacked on top of each other, a trillion protons—particles found in an atom’s nucleus—would reach just 1 millimeter high. Physicists build tools to “see” this world, making it visible through data and charts.

In a new project in the United Kingdom, three scientists are reimagining how to represent subatomic life and explain fundamental ideas in a new way. The traveling event, called Tactile Collider, uses touch, sound and live interaction to bring the world of these tiny particles to students and others who are blind and visually impaired.

“I’ve spoken to a lot of people who thought science wasn’t for them, and we wanted to show that it could be,” says Chris Edmonds, a physics lecturer at the University of Liverpool and one of the project’s founders. “We can tell the story in a very different way. We wanted people to leave feeling that they could take this knowledge further, maybe even leading to a career in science.”

Tactile Collider has its origins in a previous exhibit about the Higgs boson called Collider. When Collider arrived at the Museum of Science and Industry in Manchester, Marieke Navin, then the director of the Manchester Science Festival, was approached by a visually impaired woman and her husband. They were looking for ways to augment her experience of the exhibit.

Navin called University of Manchester and Cockcroft Institute physicist Rob Appleby, who brought 3D-printed accelerating cavities and detector pieces, along with a real metallic accelerating cavity. Navin and Appleby then walked the couple through Collider, answering questions and using the objects as guides. She says the pair were thrilled. 

Hands on table feeling Tactile Collider
Artwork by Sandbox Studio, Chicago with Ana Kova

Collider wasn’t very hands-on. Everything was behind cases,” Navin says. “They enjoyed holding the objects, but really the key thing was having that conversation with the scientist. So after they left, Rob and I said, ‘We’re on to something here.’”

Along with Edmonds, they received a £90,000 grant from Research Councils UK and spent over a year preparing the new methods and materials. Because none of the three is visually impaired, they spoke with consultants trained on the use of tactile maps and visited museums with blind people to get a sense of their experiences with exhibits. 

They also enlisted the help of Robyn Watson, a qualified teacher of the visually impaired. Watson and her students communicated some of the challenges of teaching the visually impaired. What does it mean, for example, to tell a blind student that an elephant is big?

“It was a great opportunity for my children to be involved in something that was for them,” Watson says. “They could take ownership of the ideas and help to shape something that would hopefully inspire other students to grow and develop a subject that can be really difficult for all students to access.”

The final result is Tactile Collider, a 90-minute accelerator and particle physics experience that revolves around a 3.5-meter (11.4-foot) model accelerator named CASSIE (which stands for Conceptual Accelerator Supporting Scientific Inclusive Education). CASSIE links tables that contain various objects students can touch, interact with and listen to. With headphones, students can listen to audio featuring sounds generated from real data collected at the LHC. 

“It sounded like it was a different planet almost, it sounded alien,” says 10-year-old Grace, who visited the exhibit. 

Another student, 14-year-old Sean-Paul, says he enjoyed the exhibit’s magnets. “The North poles have spiky bits and the South poles are dented in so you could tell the difference,” he says.

Both students say they were fascinated with the way the scientists conveyed just how small fundamental particles are. They’d ask the students to handle a large ball and move stepwise down in size to a marble, a grain of sand and a piece of dust, an exercise that Sean-Paul’s teacher, Peter Marsh, noted could be helpful to anyone, visually impaired or not. 

“It gave a tactile idea of scale with something you couldn’t touch,” Marsh says. “And that was useful because you can’t see that, even with the best vision, and you can’t feel that, even with the best sense of touch.”

At each station, students engage with a scientist who explains the meaning of the objects, which convey four central ideas in particle physics: that everything is made of particles, how magnets are used to steer and focus beams, how particles are accelerated around a ring, and how scientists discovered the Higgs boson.

For Grace and her sister, 12-year-old Ella, the opportunity to interact with scientists was a highlight of the Tactile Collider experience. Ella, who likes chemistry and wants to be a nurse, has limited vision, while Grace, a physics enthusiast who plans to be a scientist, has no sight. Neither had ever met a scientist other than their science teachers.

“I enjoyed talking to the scientists,” Grace says. “I was asking them loads of questions at the end, and we had a great big discussion about dark matter.”

Ella adds, “The scientists explained things clearly. It was good.”

According to the Royal National Institute of the Blind, more than 2 million people in the UK, or about 3 percent of the population, have some kind of sight loss significant enough to affect their daily lives. In the United States, it’s about 10 million people.

“It’s a huge number,” Appleby says. “A lot of traditional ways of science engagement don’t take account of this at all.” 

The difficulty visually impaired people face in accessing physics creates a paradox for Tactile Collider. While extending physics outreach to a traditionally underserved population, “it’s really highlighted the fact that physics isn’t that accessible to visually impaired people as a career choice,” Navin says. “Say we visit all these visually impaired children and we inspire someone, and they say, ‘I want to study physics.’ Is that going to be possible?

“By training scientists and raising awareness of underrepresented audiences within the scientific community we will be tackling this head on. The staff and students working with us to deliver Tactile Collider are the lecturers of tomorrow.”

In addition to touring around schools for the visually impaired, the group also plan to bring the exhibit this summer to events for the general public, such as music festivals. They have a long-term goal to create a framework for teaching physics to the visually impaired in the hopes of sharing what they’ve learned throughout the community. 

“I’ve liked science for a long time because there’s so much to do,” Sean-Paul says. “With Tactile Collider, more people get to see what it’s like. Other people can know what it’s like. It’s not just for visually impaired people.”

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Bring a folding chair

National Society of Black Physicists President Renée Horton talks with Symmetry about finding a place to belong in physics.

Renee Horton

Recognized as gifted but frustrated by a hearing condition she did not yet understand, Renée Horton dropped out of college at age 18. When she returned a decade later, she was raising three kids on her own. 

A chance encounter with the National Society of Black Physicists gave Horton a new vision for her future. She went on to become the first African American to earn her PhD in material science—with a focus in physics—at the University of Alabama. Then she landed a job at NASA. 

About two years ago, members of NSBP approached Horton to help them reinvigorate the organization that had provided her guiding star. Now, at the end of her two-year term as NSPB president, she discusses her experiences with Symmetry.

How did you get interested in science?


I was always very aware of the stars and the sky, and was always interested in science, even in elementary school. 

But it wasn’t until I got to middle school and my science teacher—my 8th grade science teacher, Mr. Merrill, was very different. He was, like, a 6-foot-6 biker dude who actually came to school in black riding boots. He rode a Harley. And he had a leather jacket. And he had a beard like ZZ Top. 

What that said to me right then was, even though I really didn’t know any Blacks in science, you really didn’t have to look like the typical Einstein to be a scientist. He was an amazing science teacher, and I think, for me, that’s when my love really kicked off. 

I was in awe of the stars when I got my first telescope—you know, just being able to look beyond Earth. And then he just kind of sealed the deal for me, I guess. 

When did you get your first telescope?


I got my first telescope on Christmas, and I had to be maybe 8 or 9. We [my brother and I] used to scale the antenna on the side of the house and put the telescope on top of the roof. And then we’d sit on the roof and look up at the stars and pray that when we got down we didn’t break anything.

I guess you didn’t break anything?


Um, actually, I broke my arm once. We didn’t tell my parents we were on the roof, per se. But I think they may have known. It still didn’t stop me from scaling the antenna.

How did you wind up in physics?


I’m a nontraditional student. So I started school the first time, didn’t get through, got pregnant, got married, followed my husband’s career, and then went back to school as a single parent. And then I actually went into engineering. 

I got sent to a physics conference as a chaperone. It was the National Association of Black Physicists conference in 2003, and I was blown away. I was blown away at the research that the other students were doing. I was blown away that I was standing in a room of extremely smart Black people talking about things that were so beyond, you know, the universe, and I wanted that.

Was that your first science conference?


It wasn’t my first science conference. I had gone to NSBE, the National Society of Black Engineers, and I had gone to IEEE [the Institute of Electrical and Electronics Engineers]. 

But I never felt quite like engineering was it for me, because even when I was going to undergrad, the professor was like, “You need to go to grad school,” because I kept asking, “Well, why? Why are we doing this like this? And why are we doing this? And what happens if you do this differently?” 

And the professor was like, “Yeah, you need to go to grad school. That’s where they answer those questions at. We don’t answer those questions here.” 

And it was while I was in grad school for engineering that one of the professors—I wasn’t doing so well in his class, and he said, “You’re probably one of the dumbest students I’ve ever met. Are you sure you want to be doing a graduate degree?” 

I was having a lot of difficulty understanding him because I’m hearing-impaired, and he spoke English as a second language. And I wasn’t understanding a lot of the words that he was saying. And even though I had a note-taker, the note-taker was also having trouble understanding him. So I never really could get complete notes to be able to truly understand what he was teaching, and I just didn’t fare well at all in his class. 

But I was pretty certain I wasn’t dumb—because I could do physics, right? [She had taken a couple of lower-level classes.] And so I was like, I’m almost certain I’m not dumb. This just isn’t for me. Or this teacher just isn’t for me.

It was all that year that I was introduced to physics and was just in awe and gravitated toward it and wound up switching universities, switching concentrations from engineering to physics. I was just blown away with quantum. And math, I love math, and so when I got to do the math physics course, I was just like, yes, this is where I belong.

Were other people telling you that you didn’t belong?


I had a professor actually tell me that women should be at home raising the children. They shouldn’t be trying to get advanced degrees.

I was a single parent, too, so I was like, oh well, we rollin’ together, me and the kids. I’m going to get this degree one way or the other. 

The sad part about it is, even being a nontraditional student and graduating now almost seven years ago, I’m still running into students that are feeling like they’re being second-guessed. 

So that’s what I’m constantly talking about when I’m traveling now. What I’m constantly telling these students when I’m talking to them now is that you do belong here. You really have earned your seat at the table. Don’t let other people tell you you haven’t, because you have. You have a right to be here.

How did your hearing loss affect your studies?


When I went back to school the second time, I was more accepting of my hearing loss than I was before. I went back and it was like, you know what? This is who I am, and I’m going to accept it, and I’m going to learn to deal with it. 

I did the nerdy thing, too. I started studying my hearing loss. I started trying to figure out what my hearing loss was, what was the best way for me to learn, what accommodations I needed. 

And I was also more accepting of accommodations. Before I felt like accommodations were a show of weakness. When I went back to school it was like, yo, I want these accommodations—because I want to be amazing. I want to apply all my brainpower. 

I had a note-taker. Him and I ended up being best friends. Because we had to take classes together. So after that first semester, all of our classes were together. He was an electrical engineering major as well—with a minor in math. I convinced him he needed to do a minor in math because I needed the note-taker. And then he went back and got a Latin degree. And we’re best friends still to this day.

I did all the coursework, but I did not pass the qualifier for the master’s program to get my thesis. I ended up leaving and enrolling in the PhD program. A professor actually recruited me and was like, “You don’t have to have a master’s.” I was like, “What? Yes, you do.” And he was like, “No, I don’t have a master’s. You don’t have to have a master’s. Nobody really cares if you have a master’s.” 

And then I changed schools and went to University of Alabama and enrolled in the materials science program with a physics concentration. So all of my degrees actually came in my second time around, as a mom with three kids.

It’s a very interesting dynamic to have kids when you’re in school. The two were older, and when I went back to undergrad, my daughter was 2 at the time. So it was just a lot of preparation, a lot of planning that we had to do. We had a calendar on the wall, and if whatever the activity was didn’t make the calendar by Sunday, we didn’t do it. And I was very strict with that and held to that.

What do you do now?


I’m a materials physicist, so I am currently overseeing the metals and the welds on our space launch system, which is the new rocket that NASA is building that’ll eventually take us to Mars. 

It’s an amazing thing to me because I look at parts and pieces sometimes and then I watch these guys integrate it together and, sooner or later, this year or the beginning of next year, we’ll have a whole rocket based off of the parts and pieces that I actually saw. 

Mars is set for 2030, but we have some other missions that are coming before that. We have a mission in 2019 and then another one in 2020 or 2021. This is a new rocket system, so we really have to test it out way before we ever put humans on it.

When did you join the National Society for Black Physicists?


I didn’t join until 2004. In 2005 I represented the National Society for Black Physicists at the IUPAP [International Union of Pure and Applied Physics] Women’s Conference in Brazil, and everything just kind of took off from there. 

I came back and created a women’s group for NSBP. I stayed a part of the organization up until about 2010, when I had a disagreement with one of the physicists [in leadership] and dropped out. I didn’t have anything else to do with the organization until they called and said, “We need you to run for president.”

Why did they need you to run for president?


They knew my work ethic and my attitude. I had worked with the organization before and had done some great things with the women’s group. 

I’m very proud to say that we were able to help with restructuring debt that the organization had. We were able to rebuild membership with the organization, as well as reigniting that interest in the organization and getting more people to actually work with us and contribute financially.

How big is the organization?


The organization is about 385 members, with about 80 percent being students. 

There are some unique benefits that come with being a member of NSBP. A lot of times we get organizations that are particularly looking to diversify their workforce, or have special programs for diverse students, and so they come to our organization. 

Being a member also gives you direct access to mentors that have been through what you’re going through. It gives you access to the famous African American physicists—because most of them show up at the conference. 

Our membership is not just African Americans, it’s anybody that wants to support African Americans as well.

What have your goals been during your time as president?


I always felt that there were so many people and so many programs trying to help African American physicists or Black physicists, but none of them were asking us how we needed to be helped. They were kind of deciding, you know, “We should do this program,” and then we were getting invited afterwards. 

And one of the things we went into our tenure saying was that if you weren’t inviting us to the table when the planning was happening, we weren’t interested in being at the table.

What is something that people were missing?


One of the things is that they want to think that it’s enough to give a student a mentor, and they were neglecting how important it is for a student to see, know and interact with people who look like them. That’s really important. There’s a whole lot of research on that.

At NSBP we give you that. You can walk in a room and you can find somebody who looks like you, whether you’re male or female, but you can also find somebody who is as nerdy as you, you can find somebody who is as eclectic as you, you can find somebody who’s as straight and narrow as you. You really can. 

To be in a place where you can find somebody that you can find a connection with, that’s what you need sometimes. We would always say that the conference was the way that we refilled our cup, to be able to endure what it was like being the only—or being the first—or being one of two. 

You know, a lot of us are walking around with that feeling that, if I mess up, I’m going to close a door for the next Black that’s coming behind me. So that’s quite a big burden. But when they’re with us at the conference or with us in our environment, they don’t have to feel like that. So it’s a relief for them, even if it’s just a weekend. But it’s also just a way to refill that cup for them to keep going.

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Q&A: Jogesh Rout

What's it like being a theoretical neutrino physicist working on the Long-Baseline Neutrino Facility?

Jogesh Rout writing equations on a clear panel. The background is blue.

How do you build the biggest physics experiment ever constructed in the United States? With a lot of help from international friends.

Symmetry writer Sarah Lawhun checked in with one of those international partners: graduate student Jogesh Rout of Jawaharlal Nehru University in New Delhi, India. Rout discussed the experience of taking part in the Long-Baseline Neutrino Facility, the supporting infrastructure crucial to the Deep Underground Neutrino Experiment.

DUNE, a global project hosted by the US Department of Energy’s Fermi National Accelerator Laboratory, will send the world’s most intense high-energy beam of neutrinos 800 miles from Illinois to the world’s most advanced, mile-deep neutrino detectors in South Dakota. The goal? To study how the neutrinos change—oscillating from one type to another—to better understand how the mysterious particles might have influenced the evolution of our universe.

The experiment has more than 1000 researchers on board from 31 countries, a collaboration that scientists expect to continue to grow. Rout, a theoretical physicist originally from Odisha, India, received the second-ever Rajendran Raja Fellowship aimed at bringing students from India to conduct research at Fermilab.

What do you work on for LNBF?


My work is on the theory of high-energy physics. I predict what will happen to neutrinos in the beam made here at Fermilab as they travel, calculating how they oscillate. I also look at neutrino and antineutrino asymmetry, called CP violation, in both standard interactions and new physics scenarios that go beyond what we currently know about neutrinos.

Before this fellowship, had you ever been to Fermilab?


This is my first time. It’s actually my first time going anywhere outside India. Physics students in India have a dream to come to places like Fermilab or CERN. I’m just excited to be here. I’m like a tourist and want to learn about all the experiments here.

When did you find out that you liked physics?


I remember being interested in math and science from a young age. I was actually the first student to go on to study science in my hometown. In my family, I’m the first person to get a PhD.

I always liked physics and performed well in it, but I come from a very rural area, and even my college was in a rural area. I knew of very few science-related careers.

I had a good teacher and mentor during my bachelor’s degree who guided me, and I discovered my interest around this time. When other students were going on to get jobs, this teacher encouraged me to further my education in physics and get my master’s degree at a university in the city.

What challenges have you faced while getting your PhD?


While getting my bachelor’s, master’s and PhD, which I am in my final year of, there have been ups and downs. Getting a PhD is a difficult path in some respects. Financially it can be difficult. One needs commitment to developing their abilities. At times I felt I was not performing up to expectations. I just remembered that I shouldn’t give up because it takes perseverance and hard work.

My brother, Mr. Manguli Rout, has always been there for me as moral support and encouraged me. I’ve been lucky to have teachers to support and guide me, too. My own perseverance and support from my friends and mentors has helped me accomplish what I have. I’ve transformed into a better and stronger person.

What first got you interested in studying neutrinos?


Before graduate school, my exposure to particle physics was very little. I still didn’t know about Fermilab or other institutions that research particle physics outside of India like CERN.

During my master’s at Utkal University, I was taught a course on high-energy physics by very good teachers, Prof. Swapna Mahapatra and Prof. Karmadeva Maharana. They inspired me to take up research in the field of high-energy physics.

After I was selected to receive my PhD at Jawaharlal Nehru University in 2013, I carried out a semester-long research project on neutrino oscillations, doing analytic and numerical computations with Dr. Poonam Mehta. This piqued my interest in neutrino physics, so I joined Dr. Poonam Mehta for my PhD program.

What do you like about studying neutrinos?


I’ve been interested in high-energy physics since my master’s degree, and I’ve always really liked mathematics. My current university has a focus in neutrino theory and high-energy physics. The study of neutrino oscillations is sort of a combination of mathematics and high-energy physics, and since I like both of these, I chose this as my specialty.

Neutrinos are fascinating because they are tiny neutral particles with peculiar properties, produced by a wide variety of sources—solar, atmospheric, reactors and accelerators and more, all with different energies. They’re omnipresent and millions pass through us yet cause no harm. Neutrino physics connects various branches of physics—particle physics, astrophysics and cosmology—making it a more comprehensive study for theory.

What do you hope to discover about neutrinos while working on LBNF?


Some questions in neutrino oscillation physics remain unanswered. We know there are three flavors, electron, muon and tau, which have different energies and display particular behaviors.

Since I’m a theorist, I predict how they will oscillate when they pass through matter. The more precise my calculations are, the more accurately we can make a certain flavor of neutrino for experimental physicists to study. They’ll gather information on the neutrino’s characteristics to solve unknowns like CP violation and mass ordering of the neutrino mass states, which combine to form the neutrino flavors.

One mystery surrounding neutrinos is CP violation. This is where there are different numbers of antineutrinos than neutrinos or they behave differently. We want to study this and hope to solve the mystery of why it occurs. In the process, we could also end up accounting for other unknowns that can reveal more about how the universe works.

What do you hope to accomplish during your fellowship?


I want to learn techniques for making the best possible predictions before DUNE begins. The results of the experiment will be more accurate if I calculate exactly right. These calculations help us better engineer and construct LBNF and overall to understand neutrinos better.

Has anything surprised you about Fermilab?


If you are coming from one line of work, it’s surprising how people work within different departments. For example, theoretical people work independently and often work alone but need to be very precise because everyone else’s work depends on them.

Experimental departments work together and collaborate more. I’ve also been surprised by how fast we move with the calculations. I’ve become faster since working here, which is a good skill to have.

I’m especially surprised by how open everyone has been here. They answer all my questions, are always helpful and inspire me to come up with new ideas.

What is an average day like for you?


My work is split between Fermilab and JNU. At Fermilab, my supervisor is Dr. Laura Fields. At JNU, my PhD advisor is Dr. Poonam Mehta, and we are currently collaborating with Dr. Mary Bishai at Brookhaven National Laboratory, Dr. Mehedi Masud who is a post-doctoral fellow at IFIC-AHEP, Valencia, and two PhD students in our research group on different projects.

This means that while I do many calculations for LBNF work here at Fermilab, I also have a lot of phone calls and Skype meetings with collaborators at my university, which can be at odd times since they are in such different time zones.

Do you work with other international students or students from your university?


There are other Indian students working at Fermilab, but none from my university. I do have a friend here who I met in my master’s degree program. He actually works on NOvA [another neutrino experiment at Fermilab] while I am working on LBNF/DUNE. He’s very supportive of me and my studies and research.

What do you like about working on an international collaboration?


The best part is that you can easily approach anyone in the collaboration and there is so much expertise available. You get ideas from so many different people, and they are all eager to help you learn more and are open to hearing your ideas, too.

I really like the exchange of ideas between such diverse scientists and getting a good platform and facility to do research in. It’s quite competitive, so once you get it, you need to give it your 100 percent to make it a success. Overall, it’s surprising to me how huge the project is and how many experts in the field are working on it.

What have you learned so far?


My computational abilities have really improved. I’m beginning to compute results so I can compare them to actual experimental results later.

I’ve been thinking about the experimental side more than usual to see how theory translates into the experiment. My research is indirectly helping the experiment by ensuring the particles behave exactly how the experimenters want them to.

And I’ve learned how to collaborate and bounce ideas off of other people. The work culture is so diverse around campus. I’m learning to understand the requirements of different work environments and to communicate with all different kinds of people.

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Looking for nothing to test gravity

When they look for violations of Einstein’s general relativity, physicists deliberately plan experiments to find nothing at all.

Gymnasts measuring distance between Earth and moon, judges score a zero and gymnasts a happy.

In 1887, physicists Albert Michelson and Edward Morley performed one of physics’ most famous experiments (at Case Western Reserve University, coincidentally, across the street from where this article was written). Unlike other important experiments, they didn’t find what they were looking for, but unexpectedly their “null” result prepared the way for the theory of relativity.

Sometimes researchers deliberately set out to generate null results—while on the lookout for something new. One type of experiment is looking for deviations from Einstein’s general theory of relativity.

“General relativity has been the staple of gravitational understanding for 100 years,” says Katie Chamberlain, a physics student at Montana State University. “We have to rule out the potential for other existing theories to come in and replace [it].”

Many alternative theories of gravity are out there, designed to explain various phenomena or fix general relativity’s famous incompatibility with quantum theory. Some of these predict differences in the behavior of gravity that can be tested in the lab.

One experiment examined precision measurements of the distance between Earth and the moon. Another recent test involved superconducting gravimeters, which measure how strong gravity is in various places on Earth’s surface. If there are gravitational effects not described by general relativity, they might show up in those experiments: the highly coveted results known as “new physics.”

The null result tells us where new physics is not. That limits the places that one can continue to look for new physics.

In these cases, everything was perfectly in line with general relativity, but that doesn’t mean the experiments were failures.

“It isn’t especially a disappointment,” says Jay Tasson of Carleton College, who worked on the superconducting gravimeter analysis. “The null result tells us where new physics is not. That limits the places that one can continue to look for new physics.”

In other words, even an experiment in line with general relativity tells us something, in this case that any theory—including theories not yet born—with results at odds with these results (as long as they hold up) must be wrong.

“Progress in this field is often measured by [looking] with better sensitivity than anyone has looked before,” Tasson says

Einstein’s happiest thought

Though general relativity is mathematically complicated, it’s based on some simple concepts. Among those: Objects experiencing only gravity don’t feel any force acting on them. That’s how someone aboard the International Space Station can float as freely as if there were no gravity at all, even though the force of gravity at that orbit is only about 10 percent less than it is on the surface of Earth. Einstein called this realization “the happiest thought” of his life. 

A consequence of this happy thought is “local Lorentz invariance.” “Local” means “approximately at a single point in space,” and “invariance” means two experiments performed under equivalent conditions should return the same results. “Local Lorentz invariance” means (for example) two experiments at the same position should be the same if one is rotated by 90 degrees compared with the other. While real experiments take up more than a single point in space, researchers compensate for that through precision measurements and understanding how the size of their experiment affects results. 

Several theories of gravity predict violations of local Lorentz invariance, including string theory and other quantum theories of gravity. Most of these violations occur at smaller length scales than current experiments can reach, but some effects might “leak” into testable regimes.

Rather than test a particular alternative theory, gravitational physicists worked out a general framework for modeling deviations. The framework consists of numbers that are all zero in general relativity but take on various values depending on which alternative theory is doing the predicting.

“Currently there are a lot of constraints on different modified theories of gravity,” Chamberlain says. “As we’re able to explore more relativistic spacetimes with higher sensitivities from our instruments, we’ll be able to place much tighter constraints.”

Testing, testing

Astronauts starting with Apollo 11 left “retroreflectors” on the surface of the moon that reflect light directly back toward the source. Astronomers on Earth send laser beams through telescopes at those retroreflectors and time how long it takes the light to come back to the observatory. These “lunar-ranging” experiments are some of the best tests of general relativity we have.

“The usefulness of the lunar laser ranging experiment is mainly due to its very precise data,” says Adrien Bourgoin of the University of Bologna. He points out that these experiments are precise on the level of centimeters, compared with the 400,000 kilometer distance between Earth and the moon. That’s good enough to see possible deviations from general relativity.

For example, if gravity violates local Lorentz invariance, it might affect the travel time of light differently when the moon is aligned with the sun (full and new moon) than when the moon and sun are at right-angles with respect to Earth (half-moon). That’s a large-scale version of rotating the experimental apparatus.

The first lunar distance test began in 1969, with many follow-up experiments. Bourgoin and his colleagues looked at 13 tests involving five different observatories.

The lunar retroreflectors were intended to test relativity, but the Earth-bound superconducting gravimeters that Jay Tasson and his colleagues used in their relativity tests are primarily there to study variations in our planet’s gravity due to rock density, earthquakes, the moon’s pull, and so forth. These instruments consist of metal spheres cooled until they become superconducting, which means they can be levitated using electromagnets. By keeping them levitating at precisely the same height, the instruments can measure the gravitational field at that position.

As with lunar ranging, these gravimeters provide a lot of precise data, some going back over a decade. Tasson and his collaborators compared results between multiple groupings of gravimeters around the world to look for any variations that can’t be explained by ordinary phenomena.

Both sets of researchers concluded there are no violations of general relativity that can be detected at this level of precision. In both cases, though, these data are improvements over what came before, with the lunar-range experiment showing as much as a thousandfold increase in precision over prior measurements.

“Any set of experiments that you can do to test general relativity are going to be complementary to each other,” Chamberlain says. 

In particular, her research looks at how future gravitational-wave observatories might spot deviations from general relativity—including Lorentz invariance violations. Unlike the Earth and moon tests, these gravitational waves come from the strongest gravity we know: colliding black holes and neutron stars.

“We need very strong signals to be able to tell the difference between a Lorentz-violating gravitational-wave form and a gravitational-wave form that looks like it should in general relativity.”

In the meantime, nobody is terribly surprised to see experiments perfectly in line with Einstein’s theory.

“I’m pleased that the measurements are null,” Bourgoin says. “If not, I’ll still be working on the subject wondering if the measurements come from computational errors or if it is real.”

He recalls the experiment from 2011 that deceptively appeared to show neutrinos traveling faster than the speed of light, a result that vanished under later analysis. A seeming violation of local Lorentz invariance would also likely mean measurement snafus rather than a fundamental discovery.

But there’s always that chance. And, like the Michelson-Morley experiment, the “nothing” results tell us where new physics may or may not be hiding.

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Fusing Fermilab physics with art

Fermilab’s 2017 artist-in-residence, Jim Jenkins, melds pieces of physics experiments into his creations.

At the artist’s reception for Jenkins’ show, a visitor peers through the magnifying glass of a sculpture called The Wait of the

When founding director Robert R. Wilson first imagined Fermilab in the 1960s, he not only envisioned a lab that was at the forefront of physics, but a space that would inspire visitors and elicit an appreciation of the research. From the beginning, he recognized the importance of fusing art and science.

Today Fermilab continues this legacy through its Artist-in-Residence Program. The 2017 artist-in-residence, Jim Jenkins, has created sculpture and mixed media meant to capture the magic of complex experimental equipment and intangible particles.

To create the pieces for his Fermilab Art Gallery show, A Perplexity of Conundrums, he pulled mechanical parts right out of particle detectors and accelerators, incorporating them into intricate works of art. Their careful assembly reflects the same attention to detail required to make the technology involved in particle physics research.

“The Tevatron [Fermilab’s retired particle collider] has 500,000 parts, and they all had to work perfectly, in unison, to be able to do what it did. That is a staggering number,” Jenkins says.

Jenkins uses leftover materials or pieces from out-of-date equipment, giving them new life. These include a piece of copper buss (a bar used to ground or conduct electricity) from the Tevatron, a mirror once used for measuring the energy of particles, detector film and wire, and other odds and ends.

He carefully arranges these relics of experiments past amongst other curiosities, including a Canadian beaver pelt, bass strings, X-ray images, owl talons, a duck-handled umbrella, and even a copy of a page from Enrico Fermi’s calculations. 

Each piece is multifaceted with several, often contradictory, possible interpretations.

“Watching other people view this exhibit has been such a pleasure, because I’ve never seen people take so much time with art before,” says Georgia Schwender, the curator of Fermilab’s gallery.

Jenkins’ sculpture titled A Close Shave incorporates a spare part from the Tevatron called a beam trimmer.

Jenkins’ sculpture titled A Close Shave incorporates a spare part from the Tevatron called a beam trimmer.

Photo by Reidar Hahn, Fermilab
Jenkins’ Ring around the Ring sculpture originally functioned as a snowflake detector inspired by Fermilab

Jenkins’ Ring around the Ring sculpture originally functioned as a snowflake detector inspired by Fermilab’s particle detectors and is now on display in the gallery.

Photo by Reidar Hahn, Fermilab
In Jenkins’ sculpture called The Failure of the Material, he uses a magnifying class to emphasize a

In Jenkins’ sculpture called The Failure of the Material, he uses a magnifying class to emphasize an owl talon.

Photo by Reidar Hahn, Fermilab
At the artist’s reception for Jenkins’ show, a visitor peers through the magnifying gl

At the artist’s reception for Jenkins’ show, a visitor peers through the magnifying glass of a sculpture called The Wait of the World.

Photo by Reidar Hahn, Fermilab
A visitor closely examines Beauty & Boredom at the artist’s reception of the gallery opening.

A visitor closely examines Beauty & Boredom at the artist’s reception of the gallery opening.

Photo by Reidar Hahn, Fermilab
In the foreground is a duck head handle of an umbrella used in Sitting Duck Soup. Behind is a Geiger Counter.

In the foreground is a duck head handle of an umbrella used in Sitting Duck Soup. Behind it is a Geiger Counter that measures the melting water from the umbrella.

Photo by Lauren Biron
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Jenkins, who also exhibited at Fermilab in 2005, says he has become less inhibited in his art over time. In his 2017 show, he boldly symbolizes the danger of unsustainable human activity. He evokes mortality with bones and X-rays. He represents the fragility of the Earth with melting pyramids of ice and damaged mechanical parts. 

Many of his sculptures demonstrate the laws of physics in motion. They rhythmically drip water, sustain living fish, rotate through magnetic attraction, or use a Geiger counter to measure particle decay. Their energy embodies scientific research at Fermilab: an active endeavor.

In his piece Ring Around the Ring, Jenkins assembled a unique snowflake-detector system using wires from the Tevatron, a sensitive microphone, and a recorder, along with X-ray film on which to record the sounds of the ephemeral crystals. The sound of a snowflake landing on a wire is as subtle as the miniature burst of light a neutrino creates in a neutrino detector, Jenkins says. He hopes this parallel will help his audience grasp the nature of the ghostlike particle.

As Schwender says, “His art opens a door for people that don’t usually think about physics. Not everybody can sit down and look at a textbook and find joy or curiosity, and this is an alternative approach.”

For Jenkins, the research at Fermilab has always been part of his vision for his art. “In 1992 I made a bucket list of things I wanted to do and number 13 was, ‘I want to work at Fermilab and make art there.’”

A Perplexity of Conundrums opened January 8 and will run in the Fermilab Art Gallery until March 6. It is open to the public from 8 a.m. until 4:30 p.m. Monday through Friday. Jenkins will also be giving a Gallery Talk that is open to the public on Feb. 26 at noon in the Fermilab Art Gallery.

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