LUX-ZEPLIN

Abstract:

The luminescence properties of Ba3Tb0.9Eu0.1(PO4)3 and Ba3Gd0.9Eu0.1(PO4)3 phosphors were studied for excitation over the 120-300 nm wavelength range. It is found that Tb3+, which exhibits a strong vacuum-ultraviolet (VUV) absorption band, provides sensitisation of Eu3+ emission in this host. This effect can be used to develop phosphors with enhanced conversion efficiency of the VUV radiation into visible light. © 2009 Elsevier B.V. All rights reserved.

Abstract:

The CRESST-II direct Dark Matter search is located in the Gran Sasso underground laboratories, Italy. CaWO4 crystals are used as scintillating targets for WIMP (weakly interacting massive particle) interactions. They are operated as cryogenic calorimeters in combination with a second cryogenic detector used to measure the scintillation light produced in the target crystal. For each particle interaction, the combination of phonon and light signals provides an event by event discrimination which allows to distinguish known particles (alphas, betas, gammas, neutrons) from the expected signal of WIMPs. A major upgrade of the setup comprises modifications of the shielding, installation of a muon-veto, and new read out electronics, as well as a new detector-support structure to accommodate up to 33 detector modules, i.e. 10 kg of target mass. The experiment was thereafter successfully commissioned in 2007. Data obtained during this commissioning phase from 2 detector modules are presented here. Combining the data collected with these two detector modules with data from one single module obtained during the CRESST-I phase, the experiment could already place a limit of ∼6 × 10-7 pb for the spin independent WIMP-nucleon scattering cross section at a WIMP mass of ∼60 GeV/c2. © BAS, BDP Sciences 2009.

Abstract:

Results are presented on our latest research, aimed at the development and study of oxide scintillation crystals (ZnWO4, ZnMoO4, PbWO4, PbMoO4, and MgWO4) with high scintillation yield and low intrinsic radioactivity. We report on the improvement of these properties for conventional scintillators, as well as on new promising crystals based on metal tungstates and molybdates. The results are discussed in view of applying these materials in cryogenic experiments searching for dark matter and/or neutrinoless double beta decay. © 2006 IEEE.