U. Schwan

Prototype scintillator cell for an In-based solar neutrino detector

Abstract 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 5 cm × 5 cm × 100 cm 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 ∼ 4.2 m and a photo-electron yield of ∼ 730 pe / MeV . Then we measured three In-loaded samples. At an In-loading of 44 g / l , an energy resolution of ∼ 11.6 % and a spatial resolution of ∼ 7 cm were attained for 477 keV recoil electrons. The long-range attenuation length in the cell was ∼ 1.3 m and the estimated photo-electron yield ∼ 200 pe / 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 > 1 year .

Luminescent properties of a new In-based organic liquid scintillation system

A novel liquid scintillator system using metal β-diketonate chemistry based on loadings of indium, a target of current interest in low energy solar neutrino detection, is developed. The optical absorption, fluorescence and scintillation properties for this new system are described. The scintillation light output as found from the irradiation by low energy gamma-rays is presented. Notable light yields are found.

Development of an optically pure In beta-diketoneate for the scintillator of an 115In-loaded solar neutrino detector

We report on the development of a novel In-loaded scintillator for a next generation low energy solar neutrino detector that would be based on neutrino interactions with 115In. In particular, β-diketone complexes added to organic scintillating solvents are investigated. Here we describe details of the chemical synthesis and unique purification steps for specific indium-β-diketonates that we developed so as to achieve the main properties needed for such an experiment: optical transparency, chemical stability and high solubility in a scintillator solvent. Together with suitably adjusted fluors, we find that notable light yields are possible.

Status of the Germanium Detector Array (GERDA) in the search of neutrinoless ββ decays of 76Ge at LNGS

The Germanium Detector Array (GERDA) in the search for neutrinoless ββ decays of 76Ge at LNGS will operate bare germanium diodes enriched in 76Ge in an (optional active) cryogenic fluid shield to investigate neutrinoless ββ decay with a sensitivity of T1/2 > 2 × 1026 yr after an exposure of 100 kg yr. Recent progress includes the installation of the first underground infrastructures at Gran Sasso, the completion of the enrichment of 37.5 kg of germanium material for detector construction, prototyping of low-mass detector support and contacts, and front-end and DAQ electronics, as well as the preparation for construction of the cryogenic vessel and water tank.