By Elizabeth Dougherty

As a graduate student in MIT’s Laboratory of Nuclear Science (LNS) in the Department of Physics, Brian Henderson applied his skills in physics to study sub-atomic particles, such as protons. He is now the first Stanton Fellow in Nuclear Science and Security in the Laboratory for Nuclear Security and Policy in the MIT Department of Nuclear Science and Engineering (NSE). His job is to put his experience in experimental particle physics to work in the realm of nuclear weapons detection, with an eye for making sure nuclear weapons policies are scientifically plausible.

“No one wants me to come here and just build experiments,” says Henderson. “My role is to have a broader perspective, which is very appealing. I’m interested in finding ways for my skills to be useful to society.”

Henderson’s projects are related to nuclear weapons detection. In one, he is exploring potential ways to solve the difficult problem of patrolling United States ports for nuclear materials that may be concealed among the tens of thousands of containers arriving in U.S. ports each day. “Cargo containers are generally considered the easiest way to smuggle a nuclear weapon into a populated area,” says Henderson. The strategy may appear simple — scan the cargo and flag containers that could potentially contain a nuclear weapon or weapons material — but it is scientifically tricky. To get a good picture of what’s inside a container, a scanning system must deliver a high dose of radiation. So Henderson and his advisor Areg Danagoulian, assistant professor of NSE, are experimenting with ways of interrogating the cargo with the least amount of radiation possible.

The second project is related to a nuclear weapons verification project that supports nuclear disarmament. The technology aims to allow 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. Henderson’s first job is to help put together an experimental setup that mimics a real warhead in need of verification. He is also working with scenarios involving fake nuclear weapons designed to defy the system.

“I joined this group to bring my experimental experience to these problems,” says Henderson. “The plans in place are sound on paper, but what we need to do now is build an experiment.”

As an undergraduate at Rice University, Henderson majored in physics and mathematics and participated in several undergraduate research projects in particle physics. Experiences working at Brookhaven National Laboratory and at Cornell University convinced him that his role in particle physics was as an experimentalist — working with particle detectors and accelerators and simulations of particle interactions — and not as a theorist.

Henderson wanted to continue work on particle physics in graduate school, but he didn’t want to participate in the very large experiments, such as those at the Large Hadron Collider. Experiments there often have thousands of physicists participating and writing papers together. “I wanted to work on a small team experiment,” he says.

There are few to choose from, but he found one at MIT’s Laboratory for Nuclear Science. He studied hadronic physics and focused on particles like protons and neutrons. He worked on an experiment called OLYMPUS with a goal of learning more about the composition of protons. It is understood that protons are not elemental particles; they are made of other particles. But it isn’t clear how those particles are distributed within the proton.

OLYMPUS, like most experiments in particle physics, is designed to uncover more about the composition of the proton by shooting things at it. “It’s a bit like having a hard object in a paper bag and shooting BBs at the bag to try to learn more about what’s inside,” says Henderson. “It’s the same with a proton, but we’re probing at a much smaller scale.”

These types of experiments inform theories about protons and neutrons and also about how most of the mass we experience in the world arises, which is still somewhat of a mystery. Henderson’s work was narrowly focused. He contributed to a specific test of a single hypothesis about two competing methods of making the same measurement. The two methods produce different results, underscoring a gap in physicists’ understanding of the underlying physics. Henderson’s project was part of an effort to close that gap.

Instead of pursuing a career with a continued focus on such fundamental science, when Henderson completed his PhD in 2016, he wanted to apply his skills more broadly. He found a match at NSE. “I’m working on bigger questions not only from a scientific perspective, but also from a societal perspective,” he says.


Posted
AuthorLaboratory for Nuclear Security & Policy

LNSP is pleased to announce that it will offer Stanton Foundation Fellowships in the area of technical nuclear-security studies. The fellowship is given annually for up to two years and is open to postdoctoral scholars and tenure-track faculty working at the intersection of technology and nuclear security. For more information, qualification requirements, and application instructions, please see the Stanton Fellowship page.


Posted
AuthorLaboratory for Nuclear Security & Policy

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.


Posted
AuthorLaboratory for Nuclear Security & Policy

Brian Henderson has been named LNSP's first Stanton Fellow.

The Stanton Fellowship in Nuclear Science and Security was created to honor the legacy of Frank Stanton, an American broadcasting executive who served as the president of CBS from 1946 to 1971 and then as vice chairman until 1973. He also served as the chairman of the RAND Corporation from 1961 to 1967, where he became familiar with the dangers of the nuclear arms race. His foundation has made the mitigation of nuclear weapon danger one of its primary missions.

Brian Henderson was selected as the inagural Stanton Fellow for his exemplary technical skill and interest in applying science to problems of international security. He received his bachelor's degrees (summa cum laude) in physics and mathematics at Rice University in 2010, where his research included electronics for particle and atomic physics applications as well as inorganometallic chemistry. Additionally, he worked on the development of low-emittance electron beam sources for the Cornell University Energy Recovery Linear Accelerator project. His Ph.D. thesis work at the MIT Laboratory for Nuclear Science (scheduled for completion in mid-2016) focused on questions of the electromagnetic structure of the proton on the OLYMPUS experiment, which took data in 2012 at DESY in Hamburg, Germany. He worked on many aspects of the experiment, including the development of highly detailed Monte Carlo simulations, construction and calibration of particle detectors, event reconstruction, and precision luminosity measurements.


Posted
AuthorLaboratory for Nuclear Security & Policy

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.


Posted
AuthorLaboratory for Nuclear Security & Policy