With Columbia’s Help, a Fermilab Particle Detector Spots Neutrinos

Scientists working on the Short-Baseline Near Detector (SBND) at Fermi National Accelerator Laboratory, also known as Fermilab, have identified the detector’s first neutrino interactions. The SBND collaboration, of which Columbia is a key partner, has been planning, prototyping and constructing the detector for nearly a decade. After a few-months-long process of carefully turning on each of the detector subsystems, the moment they’d all been waiting for finally arrived.

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

“We are thrilled that our hard work has paid off and that the detector is in action,” said Georgia Karagiorgi, associate professor of physics at Columbia. Columbia’s main contribution to SBND construction was the readout electronics for the detector’s Time Projection Chamber, which operates as a three-dimensional camera, continually capturing images of neutrino interactions. The readout electronics are responsible for processing the high-resolution video that streams out of the detector in real time, packaging the data into digestible information for collaborators to analyze offline. That work is largely overseen by Columbia postdoctoral fellow Daisy Kalra, who is permanently stationed at the Fermilab.

SBND is the final element that completes Fermilab’s Short-Baseline Neutrino (SBN) Program and will play a critical role in solving a decades old mystery in particle physics.

The Standard Model is the best theory for how the universe works at its most fundamental level. It is the gold standard particle physicists use to calculate everything from high-intensity particle collisions in particle accelerators to very rare decays. But despite being a well-tested theory, the Standard Model is incomplete. And over the past 30 years, multiple experiments have observed anomalies that may hint at the existence of a new type of neutrino.

Neutrinos are the second most abundant particle in the universe. They come in three types, or flavors: muon, electron and tau. Despite being so abundant, they’re incredibly difficult to study because they only interact through gravity and the weak nuclear force, meaning they hardly ever show up in a detector.

Scientists have a pretty good idea of how many of each type of neutrino should be present at different distances from a neutrino source. Yet observations from a few previous neutrino experiments disagreed with those predictions.

“That could mean that there are more than the three known neutrino flavors,” explained Fermilab scientist Anne Schukraft. 

The Short-Baseline Neutrino Program at Fermilab will perform searches for neutrino oscillation and look for evidence that could point to this fourth neutrino, potentially rewriting elements of the Standard Model and our overall understanding of the universe.

Getting SBND to this point has been an international effort. The detector was built by an international collaboration of 250 physicists and engineers from Brazil, Spain, Switzerland, the United Kingdom and the United States. The Columbia neutrino group is funded by the U.S. National Science Foundation. 

With the detector operational, the Columbia team will begin carefully analyzing unprecedented statistics of neutrino interactions. “We are about to look where no one has ever looked before,” Karagiorgi said. “Opportunities for new discoveries abound!”

Read more about the news on Fermilab’s website.

This article was adapted from a press release by the Fermilab.