https://biblio.ugent.be/publication/685594/file/1130605.pdf

Review of Particle Physics

Phosphor-converted white light-emitting diodes (pc-WLEDs) are emerging as an indispensable solid-state light source for the next generation lighting industry and display systems due to their unique properties including but not limited to energy savings, environment-friendliness, small volume, and long persistence. Until now, major challenges in pc-WLEDs have been to achieve high luminous efficacy, high chromatic stability, brilliant color-rending properties, and price competitiveness against fluorescent lamps, which rely critically on the phosphor properties. A comprehensive understanding of the nature and limitations of phosphors and the factors dominating the general trends in pc-WLEDs is of fundamental importance for advancing technological applications. This report aims to provide the most recent advances in the synthesis and application of phosphors for pc-WLEDs with emphasis specifically on: (a) principles to tune the excitation and emission spectra of phosphors: prediction according to crystal field theory, and structural chemistry characteristics (e.g. covalence of chemical bonds, electronegativity, and polarization effects of element); (b) pc-WLEDs with phosphors excited by blue-LED chips: phosphor characteristics, structure, and activated ions (i.e. Ce 3+ and Eu 2+ ), including YAG:Ce, other garnets, non-garnets, sulfides, and (oxy)nitrides; (c) pc-WLEDs with phosphors excited by near ultraviolet LED chips: single-phased white-emitting phosphors (e.g. Eu 2+ –Mn 2+ activated phosphors), red-green-blue phosphors, energy transfer, and mechanisms involved; and (d) new clues for designing novel high-performance phosphors for pc-WLEDs based on available LED chips. Emphasis shall also be placed on the relationships among crystal structure, luminescence properties, and device performances. In addition, applications, challenges and future advances of pc-WLEDs will be discussed.

Phosphors in phosphor-converted white light-emitting diodes: Recent advances in materials, techniques and properties

A review of quartz optically stimulated luminescence characteristics and their relevance in single-aliquot regeneration dating protocols

The recent confirmation that at least some γ-ray bursts originate at cosmological distances1,2,3,4 suggests that the radiation from them could be used to probe some of the fundamental laws of physics. Here we show that γ-ray bursts will be sensitive to an energy dispersion predicted by some approaches to quantum gravity. Many of the bursts have structure on relatively rapid timescales5, which means that in principle it is possible to look for energy-dependent dispersion of the radiation, manifested in the arrival times of the photons, if several different energy bands are observed simultaneously. A simple estimate indicates that, because of their high energies and distant origin, observations of these bursts should be sensitive to a dispersion scale that is comparable to the Planck energy scale (∼1019 GeV), which is sufficient to test theories of quantum gravity. Such observations are already possible using existing γ-ray burst detectors.

/pdf/tests-of-quantum-gravity-from-observations-of-g-ray-bursts-36h2zmgj9a.pdf

Tests of quantum gravity from observations of γ-ray bursts

/pdf/review-of-particle-physics-1996-1997-jeg703df6k.pdf

Review of Particle Physics, 1996-1997

When using X-rays in multiphase flow meters operating according to the DEGRA principle, the number of energy values as well as the X-ray energies can in principle be chosen freely. This report assesses the problem of optimization of both the number of energies and the energies themselves for application in the oil industry, where oil, water, and gas mixtures flow through pipes.

/pdf/the-optimal-x-ray-energy-problem-in-multi-phase-flow-59xp6ilvk1.pdf

The optimal X-ray energy problem in multi-phase flow metering

Detailed lattice relaxation studies of the excited nsnp states of Tl+ and In+ in KCl have shown that the calculated Stokes shift of the 6s-6p transition of Tl+ is most sensitive to the accuracy of the lattice relaxation around the substituted ion. This is a result of the strong cancellation between the influence of the spin-orbit interaction and the lattice relaxation on the 6s6p level positions. The results were calculated with a HF-LCAO embedded cluster method as well as with a DFT based supercell approach. Unexpectedly the supercell method completely fails for thallium in predicting the Stokes shift. Using the embedded cluster method, a value of 0.706 eV was found for the shift for thallium and 1.24 eV for indium. The experimental values are 0.88 and 1.44 eV respectively. It was also clearly established that the temperature dependence of the decay time of the main emission line of thallium is directly related to the Jahn-Teller distortion by which the trapping 3A1u level approaches the emitting 3T1u level. For indium this does not play a role because of the much smaller spin-orbit interaction.

https://iopscience.iop.org/article/10.1088/0953-8984/13/24/306/pdf

Ab initio study of the stokes shift of the ns-np transition of Tl+ and In+ in KCl, Jahn-Teller effect in the nsnp configuration

Evidence for the existence of a 17 keV neutrino was first reported in 1985. Since then many experiments have been performed, however, with contradicting results. Confirming the existence of a 17 keV neutrino would represent the first evidence for physics beyond the standard model of interactions of elementary particles. Consequently it is of extreme importance to settle the question of the 17 keV neutrino mass. In this paper we describe an experiment with a new approach to the problem by the introduction of a gas scintillation proportional detector.

/pdf/a-gas-scintillation-proportional-detector-to-search-for-17-2xhm6hn9eh.pdf

A gas scintillation proportional detector to search for 17 keV neutrinos

Theoretical investigation of cross luminescence in CdF2

It is recognized by various groups in the world that liquid xenon (LXe) is an interesting medium for the detection of γ-rays. In spite of all the experimental and theoretical effort expended during recent years, the processes that take place in this medium are not yet fully understood. We have obtained some preliminary results using an ionization chamber with a Frisch grid. This chamber could be filled with LXe and with solid xenon (SXe). We also investigated dual phase (GXe/SXe) systems. Our study will be continued with a newly developed detection cell described in this article.

C.W.E. van Eijk

Papers

The optimal X-ray energy problem in multi-phase flow metering

Ab initio study of the stokes shift of the ns-np transition of Tl+ and In+ in KCl, Jahn-Teller effect in the nsnp configuration

A gas scintillation proportional detector to search for 17 keV neutrinos

Theoretical investigation of cross luminescence in CdF2

Liquid/solid/dual phase xenon γ-ray detectors