Suffolk Reporter

Scientists at Fermi National Accelerator Laboratory have detected the first neutrino interactions using the Short-Baseline Near Detector (SBND). The SBND collaboration, which has been developing the detector for nearly a decade, successfully activated all subsystems after several months of preparation.

David Schmitz, co-spokesperson for the SBND collaboration and associate professor of physics at the University of Chicago, remarked, "It isn’t every day that a detector sees its first neutrinos. We’ve all spent years working toward this moment and this first data is a very promising start to our search for new physics."

The SBND completes Fermilab’s Short-Baseline Neutrino (SBN) Program and aims to address longstanding mysteries in particle physics. An international team of 250 physicists and engineers from Brazil, Spain, Switzerland, the United Kingdom, and the United States contributed to building the detector.

The Standard Model serves as a fundamental theory in particle physics but remains incomplete. Over three decades, various experiments have noted anomalies suggesting a potential new type of neutrino. Neutrinos are challenging to study due to their rare interactions with matter. They exist in three types—muon, electron, and tau—and can oscillate between these forms.

Anne Schukraft from Fermilab explained that discrepancies in previous neutrino experiments might indicate more than three known flavors of neutrinos: "Unlike the three known kinds of neutrinos, this new type of neutrino wouldn’t interact through the weak force. The only way we would see them is if the measurement of the number of muon, electron and tau neutrinos is not adding up like it should."

Fermilab's SBN Program will investigate these anomalies by comparing measurements from SBND with those from ICARUS, another detector collecting data since 2021. MicroBooNE also completed its data collection on particle collisions in 2021.

Schmitz emphasized that understanding past experimental anomalies has been a major goal for 25 years: "Together SBND and ICARUS will have outstanding ability to test the existence of these new neutrinos."

Beyond searching for additional neutrino types alongside ICARUS, SBND boasts an extensive physics program due to its proximity to Fermilab's beamline. This allows it to observe 7,000 interactions daily—more than any other similar detector—enabling unprecedented precision in studying neutrino interactions.

Ornella Palamara from Fermilab noted that SBND will collect significantly more data on argon-neutrino interactions than previous experiments: "So, the analyses that we do will be also very important for DUNE," referring to future long-baseline experiments such as Deep Underground Neutrino Experiment (DUNE).

SBND scientists also anticipate detecting particles beyond standard model predictions due to their close proximity to the particle beam. Andrzej Szelc from University of Edinburgh highlighted potential discoveries related to dark matter: "Theorists have devised a whole plethora of dark sector models...and SBND will be able to test whether these models are true."

This initial detection marks just the beginning for SBND. The collaboration plans ongoing operation and analysis over several years.

Palamara concluded by stating: “Seeing these first neutrinos is the start of a long process that we have been working towards for years. This moment is the beginning of a new era for the collaboration.”