Speaker
Description
More than fifty years ago, it was proposed that it is possible to split an atomic nucleus with a neutrino interaction, but no concerted experimental effort has ever been undertaken to confirm this prediction. The existence of neutrino-induced nuclear fission (hereafter referred to as “nuFission”) would inform both nuclear astrophysics and nuclear reactor monitoring while simultaneously providing a window into a process that bridges the weak and strong interactions. This would add neutrinos to the selective group of particles confirmed to induce nuclear fission. To that end, the NuThor detector was built in 2022 as a dedicated nuFission detector. The NuThor detector hermetically seals 52 kg of thorium metal inside a bespoke neutron multiplicity meter built to efficiently capture and detect fission neutrons emitted by the ruptured thorium nuclei. The neutron multiplicity meter is composed of gadolinium-doped water to moderate and subsequently capture the fission neutrons. An array of 7.7 kg NaI[Tl] scintillating crystals from the U.S. Department of Homeland Security’s Advanced Spectroscopic Portal Program is arranged around the complex of thorium and Gd-doped water to detect neutron-capture gamma rays. This entire apparatus is exposed to the neutrino flux of the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. The intense, pulsed neutrino source coupled with the NuThor apparatus presents a unique opportunity to conclusively put this half century mystery of nuFission to rest. This work presents the analysis results of NuThor’s three science runs.