Fermilab mourns the passing of John Peoples, third director

John Peoples Jr., Fermilab director from 1989-1999, passed away on June 25, 2025 at the age of 92.

As the third director of Fermi National Accelerator Laboratory, his career spanned more than half of a century. Over the course of this time, Peoples led Fermilab during the run of the Tevatron, which contributed to the discovery of the top quark on March 2, 1995, made the Main Injector project a reality, and initiated an astrophysics program at Fermilab.

“Achieving great science requires great leadership, and John Peoples was that. His passion and dedication to physics and astrophysics led to significant contributions in Fermilab’s history,” said interim Fermilab Director, Young-Kee Kim. “He worked continually to maintain support from local, state and federal levels for Fermilab, helping secure funding for the Main Injector upgrade, which was significant to the lab’s rich science program since the 2000s,” she added.

Peoples earned his bachelor’s degree in electrical engineering from the Carnegie Institute of Technology in 1955. He worked briefly as an engineer before turning to physics, receiving his Ph.D. at Columbia University. Later in his career, that engineering background was often vital to finding solutions and solving technical problems.

He came to Fermilab on a sabbatical from Cornell in 1971 to start work on a photoproduction experiment. Joining the lab with temporary appointments as a scientist in 1972 and 1973, Fermilab’s first director, Robert Wilson, appointed him head of the proton beamline. Peoples officially joined the lab in April 1975 as head of the Research Division.

From 1980-1987, he led the design and construction of the antiproton source that collected and stored more antiprotons than any other facility in the world. In 1987, Peoples was appointed deputy director of Fermilab, and two years later he succeeded Leon Lederman as the lab director.

“John was tireless in his commitment to Fermilab and to it being the premier high energy physics laboratory in the U.S. He was ahead of his time in recognizing the talents and contributions of scientists at the lab who otherwise would’ve been overlooked,” said Regina Rameika, associate director for the Office of High Energy Physics in the Department of Energy’s Office of Science.  During People’s tenure as director, Rameika led the MINOS and DONUT experiments at Fermilab and was the deputy head of the lab’s research division.

Peoples formed an experimental astrophysics group in 1991 at Fermilab and the University of Chicago, and he was responsible for Fermilab becoming an early partner in what was to become the SDSS. Years later, he took on the role of director of the DES to pursue funding, collaboration from international partners and mentoring early career scientists.

In 2005, he worked with Fermilab to formally establish the Peoples Fellowship, created to assist young physicists interested in transitioning from experimental physics to accelerator physics. Over the last two decades, several dozen young researchers, many of whom achieved eminent positions in the scientific community, have benefited from the program.

Peoples was awarded the Robert R. Wilson Prize for Achievement in the Physics of Particle Accelerators from the American Physical Society in 2010 for his “critical and enduring efforts in making the Tevatron Collider the outstanding high-energy physics accelerator of the last two decades.”

In his retirement, Peoples made many visits back to Fermilab, checking on the status of projects like the Dark Energy Survey and talking to scientists about different experiments.

“John was a great leader,” said former Fermilab scientist Steve Holmes. “He was director during a very critical period, when the Tevatron accelerator really came to the forefront. And in the early ’90s he worked tirelessly to make the Main Injector project a reality. He realized that one day the Tevatron program would end, and the Main Injector would become the future of the lab. If not for this insight, Fermilab and the U.S. would not have an accelerator-based high-energy physics program today.”

Fermi National Accelerator Laboratory is America’s premier national laboratory for particle physics and accelerator research. Fermi Forward Discovery Group manages Fermilab for the U.S. Department of Energy Office of Science. Visit Fermilab’s website at www.fnal.gov and follow us on social media.

Forty high school students with Chicago Public Schools graduated from Fermi National Accelerator Laboratory’s Saturday Morning Quantum* (SMQ*) program on May 31, 2025.

The inaugural 10-week program was held at the Olive Harvey College Learning Center in Chicago’s South Shore community, near the Midwest’s up and coming global destination for quantum, the Illinois Quantum Microelectronics Park — a planned 128-acre quantum computing technology campus.

“Teaching students about how the world works at the quantum level and how quantum technology could transform our life is imperative in this rapidly changing world,” said Young-Kee Kim, interim director of Fermilab.

This new program was modeled after Fermilab’s Saturday Morning Physics (SMP) outreach program that is held annually at the laboratory in Batavia, Illinois. SMP has been successfully running for over 40 years.

SMQ* — the asterisk meaning “more” — was developed by Fermilab’s Education and Public Engagement team along with the lab’s Superconducting Quantum Materials Systems team to bring a quantum science curriculum to high school students in the City of Chicago.

Once a week during the 10-week course students learned about core topics in the field of quantum science and quantum computing — including quantum mechanics, superconducting technology, quantum computing and sensing, engineering and cryogenic platforms for quantum computers.

On top of gaining technical and scientific knowledge, students worked with quantum scientists and engineers and learn about what led them to pursue their career paths.

Commenting on the experience, one student said, “Thanks to the teachers, I was able to learn more about quantum and quantum computing. There were no dumb questions in class.”

Led by Fermilab staff, students also had the opportunity to tour laboratories and scientific spaces at Fermilab, including the Superconducting Quantum Materials and Systems Center (SQMS), where scientists and researchers work to develop and deploy the world’s most powerful quantum computers and sensors.

“Touring Fermilab and learning what they do and how they do it was rewarding,” said another student.

During the graduation ceremony, students received certificates for completing the program.

With programs like SMQ*, Fermilab is building pathways into science for Chicagoland students by bringing hands-on learning and mentorship into the heart of Chicago while inspiring future generations of scientists.

The Superconducting Quantum Materials and Systems Center is one of the five U.S. Department of Energy National Quantum Information Science Research Centers. Led by Fermi National Accelerator Laboratory, SQMS is a collaboration of 36 partner institutions — national labs, academia and industry — working together to bring transformational advances in the field of quantum information science. The center leverages Fermilab’s expertise in building complex particle accelerators to engineer multiqubit quantum processor platforms based on state-of-the-art qubits and superconducting technologies. Working hand in hand with embedded industry partners, SQMS will build a quantum computer and new quantum sensors at Fermilab, which will open unprecedented computational opportunities. For more information, please visit sqmscenter.fnal.gov.

Fermi National Accelerator Laboratory is America’s premier national laboratory for particle physics and accelerator research. Fermi Forward Discovery Group manages Fermilab for the U.S. Department of Energy Office of Science. Visit Fermilab’s website at www.fnal.gov and follow us on social media

Your average screen door isn’t exactly a marvel of modern technology. However, devices that resemble colossal screen doors — 150 of them, in fact — will play a crucial role in unraveling one of the universe’s greatest mysteries. These are called Anode Plane Assemblies, or APAs, and they are key components of the Deep Underground Neutrino Experiment, an ambitious international project aiming to untangle the mysteries surrounding matter–antimatter asymmetry, without which the universe as we know it would not exist.

Ever since the doors of modern physics were cracked open over a hundred years ago, scientists have been building increasingly ingenious devices to develop an understanding of the building blocks of matter and the forces that govern them. To this end, the U.S. Department of Energy’s Fermi National Accelerator Laboratory is hosting an international collaboration of institutions, scientists and engineers to construct DUNE in the United States.

Particle detectors are intricate, sophisticated devices for learning about the origins of the universe and the matter and energy that it is made of. The DUNE collaboration is set to build enormous detectors a mile underground at the Sanford Underground Research Facility in Lead, South Dakota. Their mission? To study neutrinos — electrically neutral subatomic particles so weakly interacting that they pass through matter almost undisturbed. An additional smaller detector will be installed 800 miles away on the grounds of Fermilab in Batavia, Illinois, just downstream from an upgraded particle accelerator complex at the laboratory that will generate the highest-intensity beam of neutrinos on the planet.

“We want to study a quantum phenomenon called neutrino oscillations,” said Pip Hamilton of Imperial College in the U.K. “Neutrinos spontaneously flip from one type to another as they travel through space and time, so we need detectors at each end of their journey to count how many of each type we see at the beginning versus at the end. Since the beam spreads, the detector at the far end has to be very large to capture a meaningful number of neutrinos.”

Since the beam spreads, the detector at the far end has to be very large to capture a meaningful number of neutrinos.

The DUNE far detectors in South Dakota will be housed in cryostats (think gargantuan thermos bottles) standing roughly 58 feet tall, 62 feet wide, and 215 feet long. The cryostats will be filled with liquid argon, a heavy, transparent fluid that must be kept at a cryogenic temperature of minus 303 degrees Fahrenheit (minus 186 degrees Celsius).

Neutrinos can’t be measured directly, but when one hits an argon nucleus, the interaction releases energy that ionizes electrons in the argon. A strong electric field, created between a cathode and an anode in the detector, drives the negatively charged electrons toward the positively charged anode, which registers the signals and sends them to the readout electronics as data.

The DUNE detector called FD-HD, which stands for Far Detector-Horizontal Drift, features sets of parallel vertical anodes and cathodes that create horizontal electric fields. (see figure 1) The anodes are composed of the DUNE collaboration’s Anode Plane Assemblies. An APA’s rectangular stainless steel frame, measuring 20 feet by 7 1/2 feet, is instrumented with several layers of copper-beryllium sensing wires strung at varying angles and biased at slightly different voltages, all relatively close to ground (zero volts). This screen-door-like assembly allows the scientists to construct a 3D picture of neutrino interactions regardless of the directions the electrons travel.

The APAs will be stacked in two tiers and arranged in three rows, 25 stacks wide, to form three anode planes spanning the full height and length of the cryostat. Cathode planes, set at minus 180,000 volts, will be placed between each pair, creating four adjacent electric field volumes, each 11 ½ feet wide.

The high-precision measurements that DUNE aims for require high-precision detector components — fractions of millimeters make a difference. Furthermore, the components can’t contain materials that will contaminate the argon, and the components must be kept very clean for the same reason. The bare APA frames, custom made by commercial industry, are shipped to DUNE’s two APA production points — one at the Science and Technology Facilities Council’s Daresbury Laboratory in the U.K. and the other at the University of Chicago in the U.S. — where they are checked for alignment, carefully cleaned, and meticulously outfitted with the hardware and wires that turn them into APAs.

Because neutrino interactions with liquid argon release both charge and light, DUNE’s detectors greatly benefit from an additional system for light detection. Liquid argon is transparent and an excellent scintillator, emitting light that helps precisely time each detected particle interaction. Detecting this light requires a different technology from charge detection, which means an additional component is needed. In the FD-HD design, 10 sets of light detectors are placed within an APA frame, positioned beneath the wire layers. (see figure 2)

The light detectors will be installed once the APAs are underground and being prepared for installation into the cryostat. However, the hardware and cabling they require must be installed beforehand, prior to winding the wire layers. All this labor is done by hand in a clean room and requires hundreds of screws, bolts, washers, nuts and ties to affix various plates, rails, spacers, sensors, cables and electronics boards to the frame.

“The placement and orientation of each element, the order in which it is installed, and the size and torque of the screws that hold it in place have all been explicitly engineered, and the instructions must be followed to a T,” said Daniel Salisbury, the lead detector technician at Daresbury. “An added complication is the fact that whereas the bare frames are all identical, the detector requires multiple variants in terms of the outfitting.”

Finding a way to wire the APAs efficiently took great ingenuity. Each APA requires a total of 3,520 individual wires, strung in four layers. At 0.15 millimeters, this wire is only slightly thicker than an average human hair, is strung slightly under a half centimeter away from all its neighbors and is uniformly tensioned to within about 10% of 1 1/2 pounds. The outer and inner layers run lengthwise along the frame, and the two in-between layers wrap around the frame in a helical fashion. (see figure 3) Their positions, critical for the high-precision measurements that DUNE intends to make, cannot deviate more than a half millimeter at any point.

No off-the-shelf machine was available for this unique winding job, and stringing the wire manually for 150 APAs was out of the question. While some detector components can be outsourced to industry for construction, most must be designed, manufactured and assembled by the experiment’s collaborators. DUNE charged a team at Physical Sciences Laboratory of the University of Wisconsin at Madison with designing a computer-controlled machine that would allow the large, heavy APA frame to remain stationary while a spool of wire passes across the plane of the frame and around its edges many times, in the right direction, adjusting its position on each turn based on intricately constructed algorithms.

“The machine has a device called a winding head that allows wire to unwind from a spool at a carefully regulated tension,” said Benjamin Oye, a research engineer at the Chicago site. “The principal innovation of this machine is that it transfers the head back and forth between the two sides, passing over, around, and under the frame, via an extendable arm.”

A given layer of wire is wound as one continuous strand and on each pass around the frame, the wire is laid against designated soldering points on both sides. Within the head, the wire from the spool passes through pulleys that move a plunger attached to a spring. The load on the spring indicates the wire tension, which is continuously measured, allowing dynamic control of the tension.

“As the frame cools in the liquid argon, or returns to room temperature after a cold test, the contraction or expansion of the frame could cause wires either to sag, or to stretch and snap,” said Oye. “So, maintaining the proper tension is very important.”

Before winding each layer, the team manually attaches electronics boards as well as spacers to set the wire positions for that layer, and spacers to separate the layers from each other. When a layer is completely wound, the wire is soldered by hand at each connection point on the board, then snipped. Finally, protective shields are placed on the completed APA to protect it from both damage and dirt, before packaging and shipping.

The fastest that an APA has been constructed starting from the bare frame is 30 days, but 40 days is more typical. With five — soon to be seven — winding machines, a larger team, and an earlier start, the Daresbury factory produces on average three APAs per month. The Chicago factory, which got up and running in 2024 with a single winder, produces roughly two every three months.

This production rate ensures that by the time far detector installation begins in South Dakota in early 2028, the necessary number of APAs will arrive each month, until all 150 of DUNE’s sophisticated “screen doors” are safely delivered to take their place in one of the most ambitious physics experiments ever conceived.