Online Commissioning of the SoLid Experiment

SoLid searches for sterile neutrinos at the SCK•CEN BR2 reactor in Mol, Belgium. Inverse beta decay interactions of reactor anti-neutrinos result in a positron and neutron that are coincidental and correlated in space. To take advantage of these correlations, the detector uses a highly segmented design of 12,800 cells, each composed of two scintillators: PVT cubes 5cm cubes and 6LiF:ZnS(Ag) phosphor screens, enabling the detection and localisation of both neutron and electromagnetic signals. The cubes are read out using a 2D grid of 3,200 wavelength shifting fibres coupled to Silicon Photomultipliers. The need to operate the detector on the surface near a reactor, combined with the vast number of detector channels, introduces challenges during data taking. The sophisticated online data reduction techniques are presented, including novel trigger algorithms, that are required to optimise the sensitivity of the experiment whilst achieving a manageable output data-rate.