@spacemagick @jimdonegan So, here's my stab at answering this question, so if it isn't clear let me know. Firstly, the hypothesis here is that by generating neutrinos in the first place, you are generating both neutrinos, and anti-neutrinos in the same beam. The purpose in the DUNE experiment is to determine if the hypothesis is true. The hypothesis in question is derived from a theoretical model that mathematically predicts the existence of neutrinos with two states, that is the positive or right-spin neutrino, and the negative or left-spin neutrino (antineutrino). The physicists are predicting that generated neutrinos have a left-spin or a right-spin, and if you throw a bunch of them at a detector, you'll get two distinct results, e.g. you'll see a big clump of data with x-value, and another big clump of data with y-value, meaning that there do exist both neutrinos and antineutrinos, or more specifically, that neutrinos have two spin states verifying the hypothesis set out by the scientists.