Scientists at the South Dakota School of Mines and Technology have produced two distinct sets of neutrino-related results tied to experiments at or connected to the Sanford Underground Research Facility, known as SURF. One team led an international analysis measuring how neutrinos produce a specific particle when they strike argon, while another contributed to a dark matter detector’s first-ever constraint on a faint signal left over from ancient supernovae. Together, the results sharpen the tools physicists will need when the massive Deep Underground Neutrino Experiment begins collecting data at the same South Dakota site.
A First-of-Its-Kind Kaon Measurement on Argon
The MicroBooNE Collaboration has delivered the first flux-integrated cross-section measurement for charged-current muon-neutrino-induced K+ production on argon. In plain terms, the team measured how often a muon neutrino striking an argon nucleus kicks out a positively charged kaon, a heavier cousin of the more common pion. The result matters because kaon production is a key background signal that future experiments must understand in order to search for proton decay, one of the most sought-after phenomena in particle physics.
South Dakota Mines scientists led the international analysis that produced this measurement using data from Fermilab’s MicroBooNE detector. The technical report underlying the analysis chain is indexed through the Office of Scientific and Technical Information, providing stable metadata and government provenance for the work. The measurement itself reports quantitative results with both statistical and systematic uncertainties alongside a protons-on-target exposure figure, giving other research groups the precision they need to cross-check the finding against their own models.
Why does a kaon measurement at Fermilab in Illinois connect to SURF in South Dakota? The answer is DUNE, the Deep Underground Neutrino Experiment being built at SURF. DUNE will use liquid argon as its detection medium, the same target nucleus MicroBooNE studied. If DUNE eventually observes what looks like proton decay, physicists need to know exactly how often ordinary neutrino interactions can mimic that signal by producing kaons. Without the MicroBooNE baseline, a false positive could derail years of analysis.
Kaon-producing interactions are relatively rare compared with more mundane neutrino events, and they leave a distinctive pattern of tracks and energy deposits in liquid argon detectors. By pinning down the cross section on argon, the MicroBooNE result helps calibrate how reconstruction algorithms identify those patterns and distinguish them from potential proton decay signatures. It also offers a benchmark for theoretical models of neutrino–nucleus interactions, which must extrapolate from simpler systems like hydrogen and carbon to the more complex argon nucleus that DUNE will use at massive scale.
The South Dakota Mines team’s leadership role in this analysis underscores how smaller institutions can drive high-profile measurements in large international collaborations. Their work involved not only statistical fitting and uncertainty estimation, but also careful validation of event selection criteria to ensure that the sample of kaon events was as pure as possible. That level of scrutiny is essential because any residual contamination from other interaction channels could bias the inferred kaon production rate and, by extension, the background estimates for future proton decay searches.
LZ Detector Sets New Neutrino and Dark Matter Benchmarks
A separate line of research at SURF has also yielded significant neutrino results. The LUX-ZEPLIN experiment, known as LZ, reported the first constraint on the diffuse supernova neutrino background through a process called coherent elastic neutrino-nucleus scattering. The diffuse supernova neutrino background is a faint, cumulative glow of neutrinos produced by every core-collapse supernova in the observable universe’s history. Detecting or constraining it would offer a census of stellar death stretching back billions of years.
Mines researchers played a key role in the LZ experiment whose world-leading dark matter results simultaneously set the tightest limits yet on proposed dark matter particles and provided a new look at neutrinos produced in the sun’s core. Dark matter accounts for about 85% of the mass in the universe, yet no experiment has directly observed it. The LZ detector, sitting deep underground at SURF to shield it from cosmic rays, was designed primarily for that dark matter hunt. The fact that the same instrument can also constrain the supernova neutrino background shows how versatile large-scale underground detectors have become.
Coherent elastic neutrino-nucleus scattering is a subtle process in which a low-energy neutrino “bounces” off an entire atomic nucleus, imparting a tiny recoil that can still be detected with exquisitely sensitive equipment. For LZ, that recoil appears as a minuscule burst of light and charge in a large tank of liquid xenon. By carefully modeling and subtracting known backgrounds, including neutrinos from the sun and from the Earth’s atmosphere, the collaboration could infer how large the diffuse supernova neutrino background could be without contradicting the data they collected.
Although LZ has not yet made a definitive detection of this cosmic neutrino glow, the new constraint narrows the range of viable theoretical predictions and demonstrates that dark matter detectors are entering a regime where neutrino signals are no longer negligible. For future multi-ton xenon experiments, neutrinos will become an irreducible background that limits dark matter sensitivity. Turning that “background” into a signal, as LZ has begun to do, turns a potential obstacle into a new astrophysical probe.
South Dakota Mines contributors helped develop the analysis tools, detector calibrations, and data quality checks that underpin these results. Their involvement illustrates how expertise in low-background techniques, honed for dark matter searches, naturally extends to neutrino physics. As with the MicroBooNE kaon study, the same skills in statistical inference, detector simulation, and uncertainty quantification are central to extracting rare signals from noisy data deep underground.
DUNE’s Underground Home Takes Shape
Both sets of results feed directly into the scientific program of DUNE, which is being constructed nearly a mile underground at SURF. The project completed underground excavation in South Dakota in August 2024. “This is an extraordinary achievement given the nature of the underground excavation,” noted a release published by Fermilab at the time, reflecting the engineering difficulty of carving massive caverns out of rock at that depth.
DUNE’s scientific ambitions extend well beyond neutrino oscillation studies. According to the collaboration’s finalized blueprint, DUNE scientists will be able to watch for neutrinos from a nearby supernova, which may go on to form a neutron star or black hole. The detector will also search for proton decay, a rare subatomic process that, if confirmed, would reshape the standard model of particle physics. Trillions of neutrinos travel through our bodies each second without leaving a trace; DUNE aims to capture a tiny fraction of them in unprecedented detail, turning an elusive particle into a precision tool for exploring the universe.
The new MicroBooNE kaon measurement provides essential input for DUNE’s planned proton decay searches in liquid argon. By quantifying how often neutrino interactions can imitate the telltale proton decay signature, it helps define what DUNE should expect from ordinary physics and how far beyond that baseline any candidate signal must lie. At the same time, LZ’s constraint on the diffuse supernova neutrino background informs expectations for the flux of low-energy neutrinos that DUNE might see from distant stellar explosions, complementing its primary sensitivity to a single, relatively nearby supernova in our own galaxy.
As DUNE’s massive caverns transition from bare rock to instrumented detectors filled with liquid argon, the work at South Dakota Mines demonstrates how the broader neutrino and dark matter community is already laying the groundwork for discoveries. Precision cross-section measurements on argon, improved models of astrophysical neutrino backgrounds, and advances in ultra-low-background detector technology all converge at SURF. The facility is evolving into a hub where insights from multiple experiments inform one another, increasing the odds that when the next big neutrino signal arrives, scientists will recognize it for what it is.
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*This article was researched with the help of AI, with human editors creating the final content.
