Being able to place a detector aboveground also helps if you want to convince a reactor facility to get onboard. “Most operators of nuclear reactors don’t respond too kindly to building a 6-meter hole in the ground,” says Huber.
Proof that aboveground detectors could work came in 2018, when two projects—called Prospect and Chandler—on which Huber is a collaborator, did, in fact, catch the ghost particles at the surface. The combination of Watchman’s progress and this novel aboveground detection have helped kindle interest among officials who’d like to potentially put the technology to more than prototype, navel-gazing use. Recently, the Department of Energy commissioned a group, including Huber, to lay out where and how neutrino science could actually be useful for nuclear security. They looked at, for instance, whether the elusive particles could reveal nuclear tests, spent fuel, and reactor activity.
Although the official report isn’t ready yet, the team did, this spring, compile some of the findings into a publicly available paper titled “Neutrino Detectors as Tools for Nuclear Security.” The group found that, at least in the near term, neutrinos weren’t that useful for picking up explosions or spent fuel. But they could help, relatively soon, with reactor monitoring.