Masters of the slung load

What do you do at Fermilab?

I’m a senior engineer, and I design application-specific integrated circuits, what we call ASICs, for quantum and high-energy physics applications, specializing on the analog side. Typically, these are intended for extreme environments. For my projects, that means exceptionally cold, but it can also mean extreme radiation.

I work on taking an analog signal from a detector that’s looking for a particle or measuring some quantum property and designing the piece that converts the signal to the digital domain. Once the information is digitized, you can do a lot more calculations, processing, and many other things more efficiently in terms of power and space.

How long have you been at Fermilab, and how has your career led you to this position?

I’ve worked at Fermilab in the Microelectronics Division for five years.

Before that, I worked at Sandia National Laboratories in New Mexico, where I also got to work on some quantum projects. Fermilab was beginning to ramp up in the quantum space, so it was a natural fit. I really appreciate the collaborative atmosphere at Fermilab. Working with others in unique situations and delivering products as a team are my favorite aspects of projects here.

Before Sandia, I earned my master’s and Ph.D. in electrical and computer engineering at Georgia Tech.

What is the main project you are working on now?

My main project is one of the few things I’m working on that’s not cryogenic. It’s a fast-timing design, where we’re trying to measure events with very precise time resolution — below 10 picoseconds — for four-dimensional tracking of particles. This buys a lot of information because it provides, not only a position, but also a time. These ASICs tend to accompany low-gain avalanche diodes, so it’s a cross-disciplinary project that provides another way to get better data for scientists to discover more.

What do you find most challenging about your job?

The unique kind of requirements for our work, although I also enjoy the unusual specifications and the challenges that are outside the norm. In quantum, the deep cryogenic environment means that there’s not a lot of design infrastructure in place. Usually, when you design a chip, there are established pieces inside a process design kit, what we call a PDK. Those don’t exist yet for cryogenic temperatures.

You typically have all sorts of checks, like simulations and mask layout rules, to make sure your chip will do what you want it to do. But when you cool something close to absolute zero, much of that is compromised. You can make some educated guesses about how a transistor may act, but in the end, you are dealing with a level of unknown that is not normal for what we do in chip development.

What do you see coming up for quantum?

The future of quantum is scaling. When you scale up, the number of resources you have to accomplish a goal all start falling. You have one thing that took this much power and this much space to accomplish, but now somebody says, “I want to do this for a hundred things, all at once.” That’s the era that we want to be in for quantum right now.

I have previously designed amplifiers that were microwatts of power, and that was great. Soon it will be, “I need 10 amplifiers for that much power.” A unique characteristic of dilution refrigerators is that you only get so much power. Even if you scale up, it’s not a given that you will get more cooling capacity. We constantly need to think of new ways to approach our goals with that in mind.  

What do you like to do when you’re not at work?

I enjoy spending time with my family, camping, watching TV shows and movies, and the occasional do-it-yourself project around the house. Back in May, we had a lot of fun camping with the Cub Scouts right outside the stadium after a game for the Kane County Cougars, the local minor league baseball team. We enjoyed the fireworks and a movie after the game. My wife and I like to watch sci-fi, so we’re excited for the last two seasons of Silo coming out.

Scientists and engineers are preparing to make the world’s biggest supercollider even more powerful with the High Luminosity upgrade to the Large Hadron Collider, or HL-LHC. This upgrade will increase the amount of data collected from particle collisions by an order of magnitude and enable new insights into rare physical phenomena. But how can scientists be sure that the new components will play together in harmony? According to CERN engineer Marta Bajko, this is the role of the HL-LHC string test, which is testing a line of interconnected magnets prior to their installation in the tunnel.

“We are reproducing the section of the accelerator that will be on the left side of the CMS experiment,” said Bajko, who is leading the string test. “This will let us characterize the collective behavior of the components.”

The Large Hadron Collider is made from millions of pieces that work together to steer particles and accelerate them to just under the speed of light. The string test allows engineers to verify that the individually tested components of the upgrade — some of which were made and tested in America — can function cohesively before they are installed around the HL-LHC’s collision points 100 meters underground.

“All the equipment is there,” said Giorgio Apollinari, a scientist at the U.S. Department of Energy’s Fermi National Laboratory and the project director of the HL-LHC Accelerator Upgrade Project. “Everything will operate at the nominal current; it’s the real LHC, but only 100 meters of it and not the full 27 kilometers.”

Several components developed, assembled and tested by the Accelerator Upgrade Project, a consortium of U.S. national laboratories and institutions, including Lawrence Berkeley National Laboratory, Brookhaven National Laboratory and Fermilab, debuted in the string test. Among them are four quadrupole accelerator magnets, shipped from Fermilab to CERN earlier this year.

“They were the final piece of the puzzle,” Bajko said.

These quadrupoles are 25 tons each and contain everything needed to focus the proton beams that will pass through their cores, including coils made from a new type of superconducting material.

“They are all based on this niobium-three-tin technology, which we as humanity are using for the first time in an accelerator,” Apollinari said.

According to Apollinari, the current LHC magnets are made from coils of niobium-titanium, a flexible superconductor that can achieve a magnetic field in a particle accelerator of up to 8 tesla, which is approximately 8,000 times stronger than a typical fridge magnet. But this is not strong enough for the planned high luminosity upgrade, which will pack twice as many protons into an even smaller beam volume. By contrast, niobium-three-tin can carry more current and reach magnetic fields around 50% higher than niobium titanium. The problem is that niobium-three-tin is difficult to work with.

“It is very brittle since it requires a high temperature heat treatment to make it into a superconductor,” Apollinari said.

While CERN was constructing the LHC in the late 2000s, scientists in the U.S. started experimenting with niobium-three-tin as the basis for future LHC accelerator magnets.

“Our American colleagues were the pioneers of this new technology,” Bajko said. “I was working on magnet design at the time, and two or three times a week, the Americans would wake up very early or we would stay at CERN very late so that we could discuss and exchange ideas.”

Bajko recalls that CERN and Fermilab worked together so closely that they were eventually able to build coils that are identical.

“We were able to put American coils and CERN coils into the same quadrupole,” Bajko said. “That was a very beautiful collaboration.”

Scientists and engineers have spent more than two decades preparing for the HL-LHC, and the string test is the final check before the new magnets are installed around the LHC’s collision points.

According to Bajko, engineers recently finished connecting all the magnets and are currently pressure testing the entire system. In September, they plan to cool the chain down to minus 456.25 degrees Fahrenheit, which is just 1.8 degrees above absolute zero. Before the end of the year, she hopes to power-up the chain to 17,300 amps, which is equivalent to a bolt of lightning continuously running through the magnetic coils.

“This is a huge project, and no one lab can do it alone,” Bajko said. “We need our partners, and we are happy that our partners have been there to share the technical challenges with us.”

About 200 physicists and engineers, including more than 50 students and postdoctoral researchers, attended the U.S. Higgs Factory – Future Circular Collider workshop at the Department of Energy’s Fermi National Accelerator Laboratory in April.

The event, co-hosted by Fermilab and Argonne National Laboratory, focused on the recently released Future Circular Collider Feasibility Study and brought together the U.S. particle physics community to engage with Europe’s vision for the successor to CERN’s Large Hadron Collider.

The feasibility study represents the combined input from a collaboration of 150 institutions across 30 countries and outlines a two-stage program: building an electron-positron collider, known as FCC-ee for short, to mass produce Higgs bosons for study, followed by construction of a high-energy hadron circular collider, or FCC-hh, which could lead to direct discovery of unknown particles and understanding of the nature of dark matter.

Since discovering the Higgs boson in 2012, scientists have been studying its properties at the LHC and planning future facilities to further study this fundamental particle associated with the energy field that gives mass to other particles in our universe.

Early in 2026, the European particle physics community is expected to recommend the construction of the FCC-ee Higgs factory at CERN. If approved and funded, the experimental collaborations would be launched by 2028, with physics operations projected to begin by 2045.

The workshop at Fermilab included key contributions from early-career scientists, and Fermilab postdoctoral researchers Irene Dutta and Grace Cummings played central roles in organizing the workshop.

“The project promises to provide the next generation of researchers with an exceptional training ground, where hands-on experience with new detector technologies, advanced data analysis and innovative theoretical techniques will build on the current knowledge and expertise in particle accelerators,” said Dutta. “It will strengthen our long-standing collaboration with CERN and help us push the frontiers of precision electroweak physics.”

Cummings emphasized the value of this international partnership for the future of particle physics and for early-career scientists.

“This workshop made it clear that the skills and international relationships early-career researchers have built and enjoyed with the Large Hadron Collider can grow with the FCC-ee,” Cummings said. “The FCC-ee offers a physics environment unfamiliar to those of us born and raised in the era of hadron collider supremacy, and a unique opportunity to learn a new flavor of instrumentation.”

Participants at the workshop explored detector technologies, accelerator design, physics analysis, software development and community engagement, contributing their expertise toward shaping the FCC-ee’s program. Fermilab, building on its long tradition of collider science, stands to play a major role within the international collaboration, and also as a center for a U.S.-based particle physics research community.

Artur Apresyan, a scientist at Fermilab and one of the organizers, emphasized the program’s importance.
“The FCC-ee will offer a unique opportunity to study the Higgs boson and the electroweak sector with unprecedented precision and discovery potential,” said Apresyan. “It is the most consequential particle physics experimental program viable before the mid-21st century with a path to a high-energy hadron machine, the FCC-hh, to explore the next energy frontier.”