SBND is the final part of Fermilab’s Short-Baseline Neutrino (SBN) Program. It will help solve a long-standing mystery in particle physics.
The Standard Model explains how the universe works at a basic level. It’s the primary tool for physicists studying particle collisions and rare events. However, the Standard Model is not complete. For 30 years, experiments have found strange results that suggest a new type of neutrino.
Scientists at the Short-Baseline Near Detector (SBND) at Fermilab have detected their first neutrino interactions.
Two hundred fifty physicists and engineers from Brazil, Spain, Switzerland, the UK, and the US designed, tested, and built this detector over nearly ten years. After carefully activating each part of the detector over a few months, they finally reached a significant milestone.
Neutrinos are the second most common particles in the universe but are very hard to study. They only interact through gravity and the weak nuclear force, making them challenging to detect. Neutrinos have three types or flavors: muon, electron, and tau. One interesting thing about them is that they can change from one flavor to another, a process called oscillation.
Scientists know how many of each type of neutrino should be found at different distances from a source. However, previous experiments have shown results that don’t match these predictions.
Fermilab scientist Anne Schukraft said, “That could mean more than the three known neutrino flavors. 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 as it should.”
The Short Baseline Neutrino Program at Fermilab is searching for neutrino oscillations and signs of a possible fourth neutrino. SBND acts as the near detector, while ICARUS, which started collecting data in 2021, serves as the far detector. A third detector, MicroBooNE, also recorded data using the same neutrino beam in 2021.
This program is unique because it has both a near and a far detector. SBND measures neutrinos right after they are produced, while ICARUS measures them after they have changed flavors. Unlike previous experiments that had to guess the original types of neutrinos, the SBN Program will know exactly what they started with.
In addition to searching for a fourth neutrino with ICARUS, SBND has an exciting physics program.
Located near the neutrino beam, SBND records about 7,000 daily interactions—more than any similar detector. This large data will enable researchers to study neutrino interactions with unmatched precision.