Prototype scintillator cell for an In-based solar neutrino detector

We describe the work carried out at MPIK to design, model, build and characterize a prototype cell filled with a novel indium-loaded scintillator of interest for real-time low energy solar neutrino spectroscopy. First, light propagation in optical modules was studied with experiments and Monte Carlo simulations. Subsequently a 5cm×5cm×100cm prototype detector was set-up and the optical performances of several samples were measured. We first tested a benchmark PXE-based scintillator, which performed an attenuation length of ∼4.2m and a photo-electron yield of ∼730pe/MeV. Then we measured three In-loaded samples. At an In-loading of 44g/l, an energy resolution of ∼11.6% and a spatial resolution of ∼7cm were attained for 477keV recoil electrons. The long-range attenuation length in the cell was ∼1.3m and the estimated photo-electron yield ∼200pe/MeV. Light attenuation and relative light output of all tested samples could be reproduced reasonably well by MC. All optical properties of this system have remained stable over a period of >1year.