After a decades-long journey spanning international laboratories, the world’s first large liquid-argon neutrino detector, ICARUS, has released its initial physics results from its location at Fermi National Accelerator Laboratory near Chicago. The 27-institution collaboration, formed in the 1990s to develop liquid-argon time projection chamber technology, physically relocated the detector from Italy’s Gran Sasso National Laboratory to CERN to be refurbished and improved before arriving at Fermilab in 2017, demonstrating the complex logistics of large-scale scientific endeavors. The first analysis of data collected from 2022 to 2023 revealed no evidence of muon-neutrino disappearance, but the findings represent an important milestone for the Short Baseline Neutrino Program at Fermilab and confirm the detector’s data quality and validate the sophisticated software tools developed for analysis. “These first disappearance results mark a major milestone for ICARUS and the broader Short Baseline Neutrino Program at Fermilab,” said Carlo Rubbia, 1984 Physics Nobel laureate and ICARUS spokesperson, indicating progress toward future searches for sterile neutrinos.
ICARUS Validates Data Quality for Short-Baseline Neutrino Program
A decades-long international effort culminated in a significant validation of data quality for the Short-Baseline Neutrino Program at Fermilab, as the ICARUS detector has now demonstrated its readiness for detailed physics analyses. The ICARUS collaboration, comprised of more than 180 scientists, engineers, and technical staff from 27 institutions, formed in the 1990s to develop liquid-argon time projection chamber technology, and the recent results confirm the maturity of the associated software tools. The initial analysis, utilizing data collected between 2022 and 2023, focused on searching for muon-neutrino disappearance, a potential signal of a fourth, “sterile” neutrino. Although the analysis did not observe muon-neutrino disappearance, the result represents an important milestone for the SBN Program, and exclusion limits were placed as a result of the analysis. The collaboration meticulously examined data-driven uncertainties, allowing for a precise description of the neutrino beam and interactions within the liquid argon.
They were able to place exclusion limits on the 3+1 sterile-neutrino model with 90% confidence, a crucial step for refining theoretical models. “They demonstrate the exceptional performance and stability of the detector and confirm that we now have the precision analysis tools in place to rigorously explore the sterile-neutrino hypothesis.” This validation is vital for the SBN program, which also includes the SBND and MicroBooNE experiments, and it serves as a proving ground for the technology that will underpin the forthcoming Deep Underground Neutrino Experiment (DUNE), a significantly larger undertaking currently under construction. “With ICARUS fully validated and operating, we are entering, in concert with SBND, a new era of neutrino physics in which definitive, world-leading measurements are finally within reach,” Rubbia added.
3+1 Sterile Neutrino Model Tested via Muon-Neutrino Disappearance
The search for neutrinos continues to drive innovation in particle physics, with the ICARUS detector at Fermilab now contributing to the Short Baseline Neutrino (SBN) Program and its investigation of these elusive particles. This international effort, built on decades of development beginning in the 1990s, represents a significant undertaking; a 27-institution collaboration has refined liquid-argon time projection chamber technology to high levels of precision. ICARUS itself boasts a unique history, initially studied at Gran Sasso National Laboratory in Italy before a complex relocation, first to CERN to be refurbished and improved, and then to Fermilab, demonstrating the logistical challenges of deploying such large-scale instruments. Recent results from ICARUS, utilizing data collected from 2022 to 2023, focus on testing the 3+1 sterile-neutrino model, a hypothesis suggesting the existence of a fourth neutrino flavor beyond the three already known.
Despite an exhaustive search, the collaboration observed no evidence of muon-neutrino disappearance, a phenomenon that would have supported the model. However, this negative result is not unproductive; the analysis represents an important milestone for the SBN Program, and the collaboration placed exclusion limits on the 3+1 sterile-neutrino model with 90% confidence as a result of the analysis. The experiment’s success extends beyond the search for sterile neutrinos, establishing the quality of the ICARUS data and validating the software tools used for analysis.
These first disappearance results mark a major milestone for ICARUS and the broader Short Baseline Neutrino Program at Fermilab.
Carlo Rubbia, 1984 Physics Nobel laureate and ICARUS spokesperson
The detector’s relocation and upgrade were essential steps in preparing it for its role within the Short Baseline Neutrino (SBN) Program. The collaboration meticulously validated the detector’s performance and refined the software tools used for data analysis, establishing a robust foundation for future investigations. DUNE will be significantly larger, more than 20 times the size of ICARUS, but will rely on the principles first proven by this detector.
With ICARUS fully validated and operating we are entering, in concert with SBND, a new era of neutrino physics in which definitive, world‑leading measurements are finally within reach.
Carlo Rubbia, 1984 Physics Nobel laureate and ICARUS spokesperson
ICARUS Detector Deployment: From Gran Sasso to Fermilab’s SBN Program
The successful deployment of the ICARUS detector at Fermilab marks the culmination of a decades-long international effort, beginning with the collaboration’s formation in the 1990s to develop liquid-argon time projection chamber technology. Originally studied at Italy’s Gran Sasso National Laboratory starting in 2010, the detector undertook a significant logistical journey; it was moved to CERN in 2014 to be refurbished and improved before ultimately arriving at Fermilab three years later to integrate into the Short Baseline Neutrino (SBN) Program. This relocation underscores the complexity inherent in establishing large-scale scientific instruments capable of probing fundamental physics. Recent results, published on the arXiv preprint server, detail the first physics analyses conducted with ICARUS at its new location, focusing on searches for neutrino oscillations. The SBN Program strategically positions three detectors, SBND, MicroBooNE, and ICARUS, at varying distances from the neutrino source to comprehensively study neutrino behavior.
With ICARUS fully validated and operating we are entering, in concert with SBND, a new era of neutrino physics in which definitive, world‑leading measurements are finally within reach.
Carlo Rubbia, 1984 Physics Nobel laureate and ICARUS spokesperson
