LUX-ZEPLIN

Abstract:

We studied the feasibility of using sensitization for the improvement of the VUV-to-visible conversion efficiency of red-emitting pentaborate phosphor. It is shown that Tb 3+ ions that exhibit a strong absorption throughout the 160-230 nm wavelength range facilitate enhancement of Eu3 emission in TbM gB 5O 10-Eu at excitation in this spectral range. The maximum increase of the Eu 3+ emission efficiency in a pentaborate host at excitation with 150 nm photons is ca.10%. It is also shown that substitution of Zn for Mg in Gd(Mg,Zn)B 5O 10- Mn phosphor results in strong (up to 2.4 times) enhancement of the intensity of Mn 2+ emission. A possible reason for the observed host sensitization effect is discussed. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Abstract:

The possibility to use Tb3+ as luminescence sensitizer for enhancement of the conversion efficiency of vacuum-ultraviolet (VUV) radiation into visible light was examined. We studied the luminescence properties of K3Tb(PO4)2 and Ba3Tb(PO4)3 activated by Eu3+, and of SrAl12O19 co-doped with Mn2+ and Tb3+ at excitation over the 120 to 300nm wave-length range. It is shown that Tb3+ ions, exhibiting a strong absorption band in the VUV, can provide efficient sensitization of Eu3+ and Mn2+ emissions for excitation in this spectral range, giving rise to intense red and green luminescence, respectively. This study provides a proof for the concept of VUV sensitization, which enables the engineering of luminescence materials with improved efficiency for excitation from a noble gas discharge. © Taylor & Francis Group, LLC.

Abstract:

An increasing number of applications of scintillators at low temperatures, particularly in cryogenic experiments searching for rare events, has motivated the investigation of scintillation properties of materials over a wide temperature range. This paper provides an overview of the latest results on the study of luminescence, absorption and scintillation properties of materials selected for rare event searches so far. These include CaWO4, ZnWO4, CdWO4, MgWO4, CaMoO4, CdMoO4, Bi4Ge3O12, CaF2, MgF2, ZnSe and Al2O3-Ti. We discuss the progress achieved in research and development of these scintillators, both in material preparation and in the understanding of scintillation mechanisms, as well as the underlying physics. To understand the origin of the performance limitation of self-activated scintillators we employed a semi-empirical model of conversion of high energy radiation into light and made appropriate provision for effects of temperature and energy transfer. We conclude that the low-temperature value of the light yield of some modern scintillators, namely CaWO4, CdWO4 and Bi4Ge312, is close to the theoretical limit. Finally, we discuss the advantages and limitations of different materials with emphasis on their application as cryogenic phononscintillation detectors (CPSD) in rare event search experiments. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.