EAGER: The CHANDLER Reactor Neutrino Detector

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

Neutrinos from nuclear reactors have played a central role in our understanding of the properties of these elusive, hard-to-observe fundamental particles. Three different types of neutrino are known to exist, having been detected through their interaction via one of the known forces of nature. A fourth type of neutrino has been postulated, a so-called light sterile neutrino, that is presumed to only interact via gravity. Persistent, unproven hints of such a neutrino have been around since the late 1990's, when some accelerator data were shown to be incompatible with the 3-neutrino framework of the Standard Model of Particle Physics. More recent results and re-analyses of older data continue to suggest the existence of this type of new physics, but no experiment has been able to definitively demonstrate or rule out their existence. Going forward, reactor neutrinos offer a promising means to resolve the cluster of anomalies commonly attributed to a light sterile neutrino. One hint of particular relevance is the so-called reactor neutrino anomaly whereby all reactor experiments find a deficit in the neutrino interaction probability when compared to calculations of the reactor neutrino flux. Technologies for reactor neutrino detection may have applications beyond basic science. It has been pointed out that a high-efficiency detector with good energy resolution could determine the plutonium content of a reactor in situ. Such a capability could be used to evaluate new reactor designs, or as a part of a verification scheme for nuclear non-proliferation. A real-world application to non-proliferation safeguards will require a detector technology which can operate at the surface, in close proximity to a reactor, with minimal shielding and without hazardous liquids. The CHANDLER technology was conceived with these requirements in mind. The CHANDLER project will continue to be an excellent training ground for young scientists. This project also involves two high school teachers through the QuarkNET program. The discovery of a light sterile neutrino would be truly transformative to the field of particle physics, while a thorough debunking of the ~1 eV sterile neutrino hypothesis would simplify interpretations of future long-baseline experiments. This EAGER award provides funding to perform a full systems test of a new reactor neutrino detector technology, known as CHANDLER, by deploying the 80 channel, 80 kg MiniCHANDLER prototype, at the North Anna Nuclear Power Plant. The goal of this deployment is to evaluate the detector's performance. In particular, it will determine whether MiniCHANDLER can adequately isolate reactor neutrino events from the background, and whether this technology is capable of the high precision spectral measurement required to definitively discover or rule out the sterile neutrino hypothesis. A successful demonstration will prove the suitability of this technology for a full-scale short-baseline neutrino oscillation search.