Tests of timing silicon photomultipliers for NeuLAND

It is investigated whether NeuLAND may be reinstrumented with semiconductor based photosensors. Tests with an 11cm long slab of RP-408 plastic scintillator and a PiLas 45 ps laser diode system show time resolutions of σ = 100 ps.
The NeuLAND time-of flight detector for 1GeV neutrons will consist in its final configuration of 30 double planes of 100 scintillator bars (RP-408) each. Each bar of 270×5×5cm3 must be read out at each end. Thus altogether 6000 timing photomultipliers of 1” diameter are needed [1]. In order to limit their cost impact, it is being investigated whether parts of NeuLAND may be (re-)instrumented with semiconductor-based photosensors, socalled Silicon Photomultipliers (SiPMs). Previous experiments using the one-electron-per-bunch mode of the superconducting electron accelerator ELBE have shown that nearly full efficiency can be reached even when instrumenting one NeuLAND bar with just one 3×3mm2 SiPM [2]. However, in those first tests the charge resolution did not allow to separate single photons, and the time resolution did not fulfill the required σ ≤ 150 ps.