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

The main requirements on neutron detectors based on storage phosphors (SPs) are formulated. It is shown that commercial gadolinium-containing neutron SPs (Gd-SPs) based on mixtures of BaFBr:Eu2+ with Gd2O3 (a neutron converter) do not possess optimum neutron characteristics because of a high sensitivity to gamma radiation. A comparative study of photostimulated luminescence (PSL) kinetics was performed for samples of halogen-containing borates Sr2B5O9Br(Cl) and Ca2B5O9Br(Cl) activated with Ce3+ ions and of the commercial Gd-SPs upon neutron and gamma irradiation. The results suggest that the PSL characteristics of the above borates with 100% content of 10B must be similar to those of Gd-SPs. Use of the halogen borates as SPs offers an advantage to Gd-SPs, because the former neutron detectors are less sensitive to gamma radiation.

New storage phosphors for thermal neutron detection

The elemental composition of a sample at nanometer scale is determined by measurement of the characteristic energy of Auger electrons, emitted in coincidence with incoming primary electrons from a microbeam in a scanning transmission electron microscope (STEM). Single electrons are detected with position sensitive detectors, consisting of MicroChannel Plates (MCP) and MultiStrip Anodes (MSA), one for the energy of the Auger electrons (Auger-detector) and one for the energy loss of primary electrons (EELS-detector). The MSAs are sensed with LeCroy 2735DC preamplifiers. The fast readout is based on LeCroy's PCOS III system. On the detection of a coincidence (Event) energy data of Auger and EELS are combined with timing data to an Event word. Event words are stored in list mode in a VME memory module. Blocks of Event words are scanned by transputers in VME and two-dimensional energy histograms are filled using the timing information to obtain a maximal true/accidental ratio. The resulting histograms are stored on disk of a PC-386, which also controls data taking. The system is designed to handle 10 5 Events per second, 90% of which are accidental. In the histograms the “true” to “accidental” ratio will be 5. The dead time is 15%.

Inexpensive read-out for coincident electron spectroscopy with a transmission electron microscope at nanometer scale using micro channel plates and multistrip anodes

Recently it has been experimentally shown that saw tooth shaped p/sup +/ strips allows confinement of drifting electrons in the lateral direction. This is achieved by means of potential gutters induced by an appropriate saw tooth design of p/sup +/ cathodes. The saw tooth period p/sub x/ (=anode pitch) is the parameter mainly determining the maximal capacity of confined charge. Up-to-now the confinement effect was experimentally observed with a saw tooth detector with p/sub x/=500 /spl mu/m. The final detector is intended to have an anode pitch of 250 /spl mu/m. The simulation of a saw tooth configuration with p/sub x/=250 /spl mu/m, p/sub y/=200 /spl mu/m, and /spl alpha/=60/spl deg/ showed that potential gutters with a depth of 80 mV will be produced assuming a drift field of 250 V/cm. We will give experimental evidence of these shallow charge confining potential gutters.

Experimental results of electron confinement in a silicon drift detector with saw tooth shaped p/sup +/ strips

Silicon detectors have been proven to be useful in pradiochromatography and DNA-sequencing, because of their good spatial resolution and high detection efficiency. In DNA-sequencing the demands for a fast and accurate detection system are growing. Our group has made a prototype detection system for DNA- sequencing based on a two dimensional position sensitive silicon detector. The experimental setup and read-out electronics will be described. The results of test measurements performed in collaboration with the Biochemistry group of the Department of Biochemistry of the University of Leiden will be presented .

http://ieeexplore.ieee.org/iel4/531/3487/00693516.pdf

A Silicon Pixel Detector For Dna-sequencing

The construction and performance are described of a position sensitive detector for 511 keV annihilation radiation. The detector consists of a barium fluoride crystal sandwiched between two wire chambers which are operated with 45 and 50° C TMAE vapour. Energy, time and position resolution are presented. The advantages and limitations of the detector are discussed.

C.W.E. van Eijk

Papers

New storage phosphors for thermal neutron detection

Inexpensive read-out for coincident electron spectroscopy with a transmission electron microscope at nanometer scale using micro channel plates and multistrip anodes

Experimental results of electron confinement in a silicon drift detector with saw tooth shaped p/sup +/ strips

A Silicon Pixel Detector For Dna-sequencing

A gamma camera for pet using a barium fluoride scintillator and a TMAE filled wire chamber