M. Prata

WARP: A WIMP DOUBLE PHASE ARGON DETECTOR

The WARP programme for dark matter search with a double phase argon detector is presented. In such a detector both excitation and ionization produced by an impinging particle are evaluated by the contemporary measurement of primary scintillation and secondary (proportional) light signal, this latter being produced by extracting and accelerating ionization electrons in the gas phase. The proposed technique, verified on a 2.3 liters prototype, could be used to efficiently discriminate nuclear recoils, induced by WIMPs interactions, and measure their energy spectrum. An overview of the 2.3 liters results and of the proposed 100 liters detector is shown.

Realization of a high vacuum evaporation system for wave-length shifter deposition on photo-detector windows

In this paper, the authors present a system based on a vacuum chamber and Knudsen cells that can evaporate organic materials on convex surfaces up to 10 in. diameter, with a good uniformity, in a very short time. This system was successfully used at CERN for the deposition of tetra-phenyl butadiene wavelength shifter on the 8 in. window of 360 Hamamatsu R5912-MOD photomultiplier tubes (PMTs), before their installation inside the ICARUS T600 detector to be used for neutrino physics studies. The quantum efficiency in the vacuum ultraviolet region measured on the whole photocathode shows a good uniformity over the entire PMT active surface with an average value above 10% from 120 to 200 nm.

Systematic study of innovative hygroscopic and non-hygroscopic crystals with SiPM array readout

Different crystals with SiPM array readout were tested in laboratory. Hygroscopic crystals, such as LaBr 3 :Ce and CeBr 3 , and innovative non-hygroscopic crystals, such as PrLuAg and CeCAAG were studied. 4 × 4 SiPM arrays from different manufacturers were used as photodetectors. Best results were obtained with LaBr 3 :Ce crystals read by Hamamatsu S13361 TSV arrays. For LaBr 3 :Ce crystals, due to their high photon yield, it was possible to implement a simple readout scheme based on CAEN V1730 FADC, without any amplification. Energy resolutions (FWHM) better than 4% were obtained at the Cs 137 peak, with a detector linearity better than 2%.