The PROSPECT detector will consist of an 11 x 14 array of long skinny cells filled with liquid scintillator, which is designed to sense antineutrinos emanating from the reactor core. If a sterile neutrino flavor exists, then PROSPECT will see waves of antineutrinos that appear and disappear with a period determined by their energy. Composition not drawn to scale.
The individual cells themselves (top right) are filled with an unconventional liquid blend partially developed by NIST. In addition to containing a commercially available scintillating solution that turns hits into light, the liquid is doped with lithium ions, which allows researchers to capture the antineutrino signals in a detector of relatively small size (see diagram below).