Experimental set up at BR2 The SoLid short baseline experiment will make a measurement at close distance from the SCK•CEN BR2 reactor using next generation detector technology with the aim of delivering unprecedented sensitivity in the search for new oscillations. At the same time, it will provide one of the most precise measurements of a pure 235U antineutrino spectrum, an essential ingredient for the improvement of the reactor flux calculation.

The experimental set up consists of a detector stack made of 5 modules placed as close as 5.5m away from the reactor core on the other side of the reactor concrete wall. Each module is made of 10 planes and each plane has 256 scintillator voxels providing high level segmentation for optimum spatial resolution. The detector will be installed inside a container to provide thermal cooling surrounded by a layer of shielding materials to reduce the neutron and gamma-ray backgrounds. With a total fiducial mass of 1.6 tonnes, around 1800 antineutrinos will interact in the detector per day.

experimental sensitivity
Expected sensitivity for Phase I and Phase II

The experimental campaign will be divided into an exploratory phase of about a year (phase-I) followed by a precision phase to cover as much area as possible (phase-II). The experimental sensitivity to the hypothesis of an additional neutrino is shown on the figure above for both phases. The experiment can rule out the reactor anomaly best fit at 4σ C.L. after one calendar year of data taking.

The SoLid collaboration has around 50 members from 11 institutes in Europe and in the US.