Researchers have discovered that superconducting nanowire photon detectors (SNSPDs), originally designed for detecting photons, can also accurately detect high-energy protons.
This unexpected finding could transform nuclear physics, enabling ultra-sensitive measurements in extreme environments.
A Groundbreaking Breakthrough at Fermilab
Particle detectors are essential tools for studying the fundamental components of the universe. They help scientists analyze the behavior and properties of particles created in high-energy collisions. In these experiments, particles are accelerated to nearly the speed of light and then smashed into targets or other particles. Detectors capture and measure the results, revealing valuable insights. However, traditional detectors often lack the sensitivity and precision needed for certain types of research.
Recently, researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory achieved a major breakthrough in high-energy particle detection. Their experiments, conducted at the Test Beam Facility at DOE’s Fermi National Accelerator Laboratory (Fermilab), have opened new possibilities for more precise and effective particle detection.
“This was a first-of-its-kind use of the technology. This step was critical to demonstrate that the technology works the way we want it to because it is typically geared toward photons. It was a key demonstration for future high-impact applications.” — Whitney Armstrong, Argonne physicist
Revolutionizing Photon Sensors for Particle Detection
They have found a new use for the superconducting nanowire photon detectors (SNSPDs) already employed for detecting photons, the fundamental particles of light. These incredibly sensitive and precise detectors work by absorbing individual photons. The absorption generates small electrical changes in the superconducting nanowires at very low temperatures, allowing for the detection and measurement of photons. Specialized devices able to detect individual photons are crucial for quantum cryptography (the science of keeping information secret and secure), advanced optical sensing (precision measurement using light), and quantum computing.
From Photons to Protons: A Surprising Discovery
In this study, the research team discovered that these photon sensors could potentially also function as highly accurate particle detectors, specifically for high-energy protons used as projectiles in particle accelerators. Found in the atomic nucleus of every element, the proton is a particle with a positive electrical charge.
The team’s breakthrough opens up exciting opportunities in the field of nuclear and particle physics.
“This was a first-of-its-kind use of the technology,” said Argonne physicist Whitney Armstrong. “This step was critical to demonstrate that the technology works the way we want it to because it is typically geared toward photons. It was a key demonstration for future high-impact applications.”
Testing the Limits: High-Energy Protons at Fermilab
The team made SNSPDs with different wire sizes and tested them with a beam of 120 GeV protons at Fermilab, which was the nearest facility equipped to carry out this experiment. These high-energy protons are important because they allow researchers to simulate and study the conditions under which SNSPDs might operate in high-energy physics experiments, providing valuable insights into their capabilities and limitations.
They found that wire widths smaller than 400 nanometers — the width of a human hair is approximately 100,000 nanometers — demonstrated the high detection efficiency needed for high-energy proton sensing. Further, the study also revealed an optimal wire size of approximately 250 nanometers for this application.
Expanding the Possibilities for Particle Accelerators
In addition to their sensitivity and precision, SNSPDs also operate well under high magnetic fields, making them suitable for use in the superconducting magnets used in accelerators to boost particle velocity. The ability to detect high-energy protons with SNSPDs has never been reported before, and this breakthrough widens the scope of particle detection applications.
“This was a successful technology transfer between quantum sciences, for photon detection, into experimental nuclear physics,” said Argonne physicist Tomas Polakovic. “We took the photon-sensing device and made slight changes to make it work better in magnetic fields and for particles. And behold, we saw the particles exactly as we expected.”
Shaping the Future of the Electron-Ion Collider
This work also demonstrates the feasibility of the technology for use in the Electron-Ion Collider (EIC), a cutting-edge particle accelerator facility being built at DOE’s Brookhaven National Laboratory. The EIC will collide electrons with protons and atomic nuclei (ions) to get a better look at the internal structure of those particles, including the quarks and gluons that make up the protons and neutrons of nuclei.
The EIC requires sensitive and precise detectors, and SNSPDs will be valuable tools for capturing and analyzing the resulting particles produced in collisions within the EIC. “The proton energy range that we tested at Fermilab is right in the middle of the span of the ion’s energy range that we will detect at EIC, so these tests were well-suited,” said Sangbaek Lee, a physics postdoctoral appointee at Argonne.
Reference: “Beam tests of SNSPDs with 120 GeV protons” by Sangbaek Lee, Tomas Polakovic, Whitney Armstrong, Alan Dibos, Timothy Draher, Nathaniel Pastika, Zein-Eddine Meziani and Valentine Novosad, 9 October 2024, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
DOI: 10.1016/j.nima.2024.169956
The research team made use of the Reactive Ion Etching tool at the Center for Nanoscale Materials, a DOE Office of Science user facility at Argonne.
Other contributors to this work include Alan Dibos, Timothy Draher, Nathaniel Pastika, Zein-Eddine Meziani, and Valentine Novosad.
The results of this research were published in Nuclear Instruments and Methods in Physics Research Section A. The study was funded by the DOE Office of Science, Office of Nuclear Physics.
