Jayson Vavrek: turning particle detectors into weapons detectors

By Elizabeth Dougherty

Department of Nuclear Science and Engineering (NSE) graduate student Jayson Vavrek got his start in high-energy particle physics looking for the smallest forms of matter in the universe. Now at MIT, he uses the same tools and principles to verify nuclear weapons.

The system Vavrek is developing with his advisor, NSE Assistant Professor Areg Danagoulian, is called physical cryptography. It’s designed to precisely identify a nuclear warhead, but without revealing the weapon’s inner-workings. The goal is to allow inspectors to verify that actual nuclear weapons are being marked for disposal during a disarmament process without revealing the weapons’ internal secrets.

The work is being done in MIT’s Laboratory of Nuclear Security and Policy (LNSP), a collection of experts in physics, nuclear engineering, and public policy. “We have great people who I can talk to about anything, from nitty-gritty physics details to the loftier goals of getting this implemented in the political future,” says Vavrek.

As an undergraduate in physics at the University of Alberta in Canada, Vavrek studied particle physics, the kind of work that led to the discovery of the Higgs boson in 2012. But Vavrek also had a chance to work on a more practical project that involved looking for neutrino emissions from nuclear reactors as a way to detect nuclear material. Neutrinos can’t be shielded, says Vavrek, “So they’re an obvious signal.”

He used a detector called a liquid scintillator that detects high-energy charged particles. When neutrinos pass through the detector, their interactions create charged particles as a by-product that can be measured. “I found it interesting because it was using all the same tools as pure particle physics, but in an applied sense,” Vavrek says.

When it came time to apply to graduate school, Vavrek wasn’t sure he wanted to pursue particle physics. Experiments in this field often involve thousands of collaborators. “The chance to contribute something meaningful is really small,” he says.

But when he came across the MIT Department of Nuclear Science and Engineering, he remembered his project working with neutrinos and thought that a more applied path might be a good fit. “The skills weren’t all that different,” he says.

On day one of his arrival at MIT in 2014, he began work on physical cryptography. The research aims to develop a technology which would enable an inspector overseeing a treaty-driven nuclear weapons dismantlement process to authenticate a weapon with confidence yet still have no access to the classified information about that weapon’s design. Current arms reduction treaties are hampered by the absence of such technology.

The concept that Vavrek is researching involves shooting beams of photons through a weapon, producing a signal that is highly sensitive to the weapon’s makeup. Instead of being measured directly, however, the signal undergoes physical encryption first. The transmitted beam interacts with special materials called encrypting foils that produce a secondary, encrypted signal for detectors to measure.

Different materials create different encryptions, and it is impossible to decode the signal without knowing the composition of the foil materials. As a result, the foils act as virtual “notches” on a cryptographic “key.”

During an inspection, an inspector needs only to determine if the encrypted signal from a weapon undergoing verification matches that from another, previously authenticated weapon.

One of Vavrek’s goals is to determine whether or not it would be possible for a weapon owner to trick the system. A hoax would allow a weapons owner to dismantle fake weapons while claiming that they are compliant with the treaty.

Vavrek has to rely on his own creativity and the expertise of his advisor to simulate potential hoaxes because almost all nuclear weapons specifications are classified. He was able to run simulations using a simplified model of a nuclear weapon from the open literature. He also simulated potential hoaxes involving substitutions and rearrangements of weapons materials in ways intended to produce the same foil as a real weapon. As predicted, his skills from particle physics transferred over seamlessly. “Literally,” he says. “It’s the same simulation software we used in pure particle physics.”

Vavrek is still working on simulations, and he is also working to determine the system’s probability of producing false positives or false negatives or if it could leak information. Within the next year or so, Vavrek hopes to collaborate with the United States National Labs, which have access to weapons grade material.

Looking back on his decision to apply physics to real-world problems, Vavrek is satisfied. He’s already published a paper in the Proceedings of the National Academy of Sciences as one of four equally contributing authors. “I’m happy with the contribution I’ve been able to make,” he says.

Scott Kemp Named Sloan Fellow in Physics

From: MIT News Office

R. Scott Kemp, the Norman C. Rasmussen Assistant Professor of Nuclear Science and Engineering at MIT and director of the MIT Laboratory for Nuclear Security and Policy, is among the 23 American and Canadian researchers awarded the 2016 Sloan Research Fellowship in physics, the Alfred P. Sloan Foundation announced today.

Awarded annually since 1955, the Sloan Research Fellowships are given to early-career scientists and scholars whose achievements and potential identify them as rising stars among the next generation of scientific leaders. 126 awards are made across seven disciplines. This year's recipients are drawn from 52 colleges and universities across the United States and Canada.

“Getting early-career support can be a make-or-break moment for a young scholar,” said Paul L. Joskow, president of the Alfred P. Sloan Foundation, in a press release. “In an increasingly competitive academic environment, it can be difficult to stand out, even when your work is first rate. The Sloan Research Fellowships have become an unmistakable marker of quality among researchers. Fellows represent the best-of-the-best among young scientists.”

Administered and funded by the foundation, the fellowships are awarded in eight scientific fields: chemistry, computer science, economics, mathematics, evolutionary and computational molecular biology, neuroscience, ocean sciences, and physics. To qualify, candidates must first be nominated by fellow scientists and subsequently selected by an independent panel of senior scholars. Fellows receive $50,000 to be used to further their research.

Since the beginning of the program, 43 Sloan Fellows have earned Nobel Prizes, 16 have won the Fields Medal in mathematics, 68 have received the National Medal of Science, and 15 have won the John Bates Clark Medal in economics.

For a complete list of this year’s winners, visit the Sloan Research Fellowships website.

Aditi Verma: A multidisciplinary take on nuclear policy

By Leda Zimmerman

Aditi Verma’s first encounter with nuclear policy was nearly her last. She represented Germany at a high school version of the International Atomic Energy Agency (IAEA), and was frustrated by the debate on her group’s topic, nuclear waste. “We had to pass resolutions, but without a science and engineering background, people couldn’t really negotiate,” she recalls.

Today, Verma wonders if this experience paradoxically sparked her interest in the field. A doctoral student in nuclear science and engineering, Verma has spent her academic career acquiring the expertise in science, engineering, and the social sciences required to make sense of complex policy questions that arise around nuclear energy. Her studies have included an internship at the actual IAEA. Verma’s dissertation, entitled “Towards an International Nuclear Safety Framework,” highlights her distinctive, interdisciplinary approach. She draws on sociology and political science theory and practice, as well as quantitative analysis, to solve what she calls an “empirical puzzle”: how the U.S., French, and Russian nuclear programs developed different safety practices despite starting with similar technologies — and in the case of France, a reactor design identical to and originating from the U.S. (a type of pressurized water reactor).

Interviewing plant designers, operators, and regulators, as well as analyzing historical data and reviewing trade publications, Verma is teasing apart the divergent safety institutions that have evolved among the three nations. She has already detected sharp differences between the United States and France, where she spent the past summer applying her recently acquired French language skills. “In France, if they think of something that can go wrong with a reactor, even if the probability is very low, they will fix it,” Verma says. There, “regulators are constantly talking to designers, and setting safety objectives, with the idea that safety is something that must improve continuously.” In the U.S., on the other hand, “it’s more about establishing metrics and constantly being sure that quantitative targets are being met.”

About to start the field leg of her Russian research, Verma has begun the process of detailing the varied national approaches to nuclear safety. Her conclusions may be of interest to the 30 or more nations, mainly developing economies, currently pursuing nuclear energy. “If you’re trying to get into the game, you look around and see that different countries have different templates for doing things,” Verma says. “This raises questions: Is one way better than another, do different approaches matter, or are all of these people aiming for the same level of safety?”

Access to abundant, clean energy has preoccupied Verma since her childhood, where the Indian cities she lived in were frequently beset with power outages. A physics whiz, she entered MIT as an undergraduate and immediately focused on nuclear science. “I was eager to get started applying my knowledge to a problem I cared about, which happened to be energy.”

During her junior year, Verma experienced what she describes as a watershed moment in her studies: She enrolled in 22.812J (Managing Nuclear Technology), a graduate-level class taught by her advisor, Richard Lester. The course examined such nuclear industry issues as waste management and weapons proliferation. “I didn’t realize until then that you could bring economics, management, and policy insights to bear on nuclear projects,” Verma says.

She has been adding to her multidisciplinary toolkit ever since, applying both social science methodologies and quantitative technical analysis to explore, for instance, how the Indian nuclear energy program plans to meet its mid-century nuclear capacity targets, and effective ways for aspiring nuclear nations to develop a skilled workforce. With R. Scott Kemp, an assistant professor in the Department of Nuclear Science and Engineering, she is organizing a reading group for fellow graduate students that will apply concepts from philosophy, linguistics, architecture, and data sciences to problems in the design and safety of nuclear technologies.

“At first it was hard to think like a sociologist or political scientist about a part of the world I was so used to contemplating as an engineer,” Verma says. “But now jumping between two worlds is completely fascinating.” She believes this “dual way of looking at things” will help in a career she hopes will involve both studying and shaping nuclear industry policy. “I like the idea of being driven by questions, and with no disciplinary boundaries, finding the right tools and people to explore those questions.”

Areg Danagoulian wins IEEE Early Career Award

MIT Department of Nuclear Science and Engineering Professor Areg Danagoulian has been selected for the prestigious IEEE/NPSS Radiation Instrumentation Early Career Award. He is cited for "contributions to the field of cargo security and active interrogation, in particular for the development of the Prompt Neutrons from Photofission (PNPF) technique in fissionable material detection."

Danagoulian's research focuses on nuclear security, a field that includes active and passive interrogation of commercial cargoes and public areas, with the aim of preventing nuclear terrorism; nuclear nonproliferation; treaty verification; and arms controls. With senior research scientist Richard Lanza, Danagoulian leads the Monochromatic Radiography Program at MIT, which pursues new methods for achieving low-dose radiography and active interrogation of cargo containers. His group studies various nuclear reactions involving megaelectron-volt gamma rays, as well as advanced radiographic techniques and algorithms for using gamma rays in radiographic applications.

Danagoulian is also involved in the Zero Knowledge Warhead Verification program. The objective of this program is to develop a direct warhead verification protocol that does not reveal secret information about the warhead's design. The group employs a technique called nuclear resonance fluorescence to create a profile of the composition of nuclear warheads identified for disarmament. The generated profile can then be compared with a profile created by the actual warhead for authentication without revealing information about design. Such a verification technique would enable arms reduction treaties which are much more aggressive than the current ones when it comes to dismantlement of nuclear arsenals.

Funded by the IEEE Nuclear and Plasma Sciences Society, this award is given to a young investigator in recognition of significant and innovative technical contributions to the fields of radiation instrumentation and measurement techniques for ionizing radiation. The award will be presented at the IEEE/NPSS meeting in San Diego this November.

Ruaridh Macdonald: Upholding disarmament agreements with engineering

By Julia Sklar | MIT News

“Energy is incredibly fundamental to life,” MIT graduate student Ruaridh Macdonald says. “That’s why I keep studying it.”

This tenet has been the thread throughout Macdonald’s nearly eight years at MIT — first as an undergraduate, then as a master’s student, and now as a PhD student — all spent studying nuclear science and engineering. Though he has remained engaged in this one department, he’s participated in a variety of projects, first studying reactor design as he pursued his master’s degree and now working on a nuclear weapons verification project in the Laboratory for Nuclear Security and Policy.

Transportable reactors

Macdonald, who grew up in West London, spent his grade school days equally interested in the arts and humanities and in physics. But he ultimately chose physics when faced with the U.K.’s school system, which requires students to pick a concentration, similar to a major in college.

“I still have immense respect for the arts, but I asked myself which would allow me to help people most broadly, and I chose science,” Macdonald says.

His view of energy’s fundamental role in life is deeply rooted in the fact that so much of the world still doesn’t have access to it. Believing in the potential of nuclear energy as a clean, cheap source of power, Macdonald immediately dove into the subject at MIT. And as a master’s student, he worked on designing small, transportable nuclear reactors specialized to run in remote, isolated, and off-grid locations. The possibility of their widespread use invigorated him, but the slow movement from scientific discovery to real-world use frustrated him.

A timely pursuit

Moving on to the PhD program in MIT’s Department of Nuclear Science and Engineering, Macdonald resolved to find another, more readily applicable outlet for his interest in nuclear science, landing him in a lab that tackles an especially timely issue: how to ensure that countries with nuclear weapons abide by disarmament agreements.

The linchpin of these agreements is being able to verify that the signers are following the rules. But the trick, Macdonald says, is for both sides — or a third party — to be able to police weapons in a way that doesn’t give out too much information about them. If the U.S., for example, were to inspect a Russian weapon, in the process they might also be able to gather valuable information about how it was built — not information that governments want other countries to have.

Macdonald is involved in a project, called Zero Knowledge Warhead Verification, that tackles this problem with a beam of light, a scrambler, and a detector. Objects are made up of nuclei, which each give off a unique glow when hit with a gamma ray; the specific glow of an object acts like a fingerprint to identify what isotopes it’s made of. By carefully repeating this process from multiple angles, a nuclear weapon can be identified based on the composition and distribution of its isotopes.

To provide just enough of this identifying information, but no design information on a weapon, Macdonald says that the weapon is illuminated by the gamma ray beam; the resulting information is then passed on to a scrambler that mixes up the signals before reaching a detector. The resulting signal is then compared with one from a known weapon to see if they match. As both signals are scrambled, the inspector learns nothing useful about either, preserving the owner’s secrets — similar to the idea of “hashing” in digital cryptology.

Room for discovery

The project is one year into a five-year-long effort in which Macdonald and his colleagues are also working with Department of Energy labs to design such a verification device. And the lab work, necessarily, is acutely linked with on-the-ground politics.

While Macdonald remains focused on the science end of things, there are policy specialists — advisors and graduate students alike — among the lab members. Their job is to make sure that at the end of the day, the verification device he’s working to develop is not, as he says, “something that doesn’t actually matter, but is just scientifically interesting,” but is rather something that could be used by nations to uphold disarmament agreements.

Though Macdonald remains unsure exactly where his future will take him, he’s sure why he’ll stick with energy, and probably nuclear science: Apart from its role in creating an energy alternative, part of what drew him to nuclear science in the first place was its relative newness as a subject.

“If you think about it, nuclear engineering is really only 50 or 60 years old at this point,” Macdonald says. “That’s really young in the science world, and it leaves a lot of room for discovery.”