We briefly review the concept and properties of the Thick GEM (THGEM); it is
a robust, high-gain gaseous electron multiplier, manufactured economically by
standard printed-circuit drilling and etching technology. Its operation and
structure resemble that of GEMs but with 5 to 20-fold expanded dimensions. The
millimeter-scale hole-size results in good electron transport and in large
avalanche-multiplication factors, e.g. reaching 10^7 in double-THGEM cascaded
single-photoelectron detectors. The multiplier's material, parameters and shape
can be application-tailored; it can operate practically in any counting gas,
including noble gases, over a pressure range spanning from 1 mbar to several
bars; its operation at cryogenic (LAr) conditions was recently demonstrated.
The high gain, sub-millimeter spatial resolution, high counting-rate
capability, good timing properties and the possibility of industrial production
capability of large-area robust detectors, pave ways towards a broad spectrum
of potential applications; some are discussed here in brief.Comment: 8 pages, 11 figures; Invited Review at INSTR08, Novosibirsk, Feb
28-March 5 200
Vitamins are essential nutrients for human metabolism, playing an important role as coenzymes or enzymes in many vital processes for the normal functioning of the body. In recent years, it has become apparent that vitamins are crucial in health and human disease, due to several studies that studied this relationship. Currently, it is known that vitamins can have an important role in the prevention and treatment of cancer, but until now no conclusive results were obtained. In this review, we will present the work and more relevant conclusions obtained in recent years of investigation about the relationship between vitamins and cancer, namely vitamin A, vitamin B complex, vitamin C, vitamin D, vitamin E, and vitamin K.
The operation of Thick Gaseous Electron Multipliers (THGEM) in Ne and Ne/CH 4 mixtures, features high multiplication factors at relatively low operation potentials, in both single-and double-THGEM configurations. We present some systematic data measured with UV-photons and soft x-rays, in various Ne mixtures. It includes gain dependence on hole diameter and gas purity, photoelectron extraction efficiency from CsI photocathodes into the gas, long-term gain stability and pulse rise-time. Position resolution of a 100x100 mm 2 X-ray imaging detector is presented. Possible applications are discussed.
We report on the progress in the study of cascaded GEM and GEM/MHSP gas avalanche photomultipliers operating at atmospheric pressure, with CsI and bialkali photocathodes. They have single-photon sensitivity, ns time resolution and good localization properties. We summarize operational aspects and results, with the highlight of a high-gain stable gated operation of a visible-light device. Of particular importance are the results of a recent ion-backflow reduction study in different cascaded multipliers, affecting the detector's stability and the photocathode's lifetime. We report on the significant progress in ion-blocking and provide first results on bialkali-photocathode aging under gas multiplication. r
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