The First Indication of Neutrino-Induced Nuclear Fission

This book reports on the full-stack experimental search (from inception to discovery) of the first observation of neutrino-induced fission. Over fifty years ago, physicists predicted that neutrinos, such as those from supernova or nuclear reactors, could fission heavy nuclei. This “new way to split the atom” could serve as an exciting new way to observe low-energy neutrinos and would also play an important role in the creation of heavy nuclei in neutrino-rich astrophysical environments—for instance, in the R-process for nucleosynthesis. The challenge in detecting this interaction and thus confirming its existence was twofold: the neutrino interacts only rarely; and the targets of interest must be fissionable, and therefore already produce large radioactive backgrounds. This landmark thesis describes the inception, design, construction, and operation of the first measurement of neutrino-induced fission and the presentation of the first exciting results from the work. It is the first measurement of neutrino-induced fission and the first measurement of a neutrino cross-section on an unstable nucleus. The work is an open door for new experiments designed to search for new “NuFission” interactions and find new applications for this new approach to neutrino detection.

1 Introduction.- 2 Theoretical Background.- 3 Neutrinos at the SNS.- 4 Neutrino-Induced Fission on Thorium.- 5 The NuThor Detector.

Tyler Johnson is a postdoctoral associate at Yale University in the Physics Department and Wright Laboratory. His work centers around the development of Rydberg atom-based microwave photon sensors for the axion direct-detection experiment RAY and cryogenics for the ALPHA experiment. Additionally, he works on the neutrinoless double beta decay experiments CUORE and CUPID. He received a Ph.D. in physics from Duke University in 2025. His doctoral research focuses on developing novel particle detectors to study neutrino-nuclear interactions, specifically elucidating the existence of a new way to split the atom with neutrinos called neutrino-induced nuclear fission or “nuFission.”

Tyler was an Arms Control fellow for the Stanford US-Russia Forum, Alfred Sloan Foundation Minority Ph.D. scholar, NNSA Anti-neutrino Ph.D. fellow, Robert C. Richardson fellow, Goshaw Family fellow, and previously a Mellon-Mays Undergraduate fellow. At Duke, he sat on the Finance Committee for the Board of Trustees, the Capital Sub-Committee in service of the Finance Committee, the Board of Trustees Strategic Engagement Program, Duke’s University Center for Exemplary Mentoring Advisory Board, President’s Council on Black Affairs, the Advisory Committee on Investment Responsibility, the Search Committee for the Trinity Dean of Arts and Sciences, and the Young Trustee Nominating Committee. He also spent time at Italy’s National Institute for Nuclear Physics, Fermi National Accelerator Lab, and Oak Ridge National Lab. Tyler received his Bachelor’s in physics from the University of Chicago.