Advances in Thick GEM-like gaseous electron multipliers. Part I: atmospheric pressure operation

Thick GEM-like (THGEM) gaseous electron multipliers are made of standard printed-circuit board perforated with sub-millimeter diameter holes, etched at their rims. Effective gas multiplication factors of 100000 and 10000000 and fast pulses in the few nanosecond rise-time scale were reached in single- and cascaded double-THGEM elements, in atmospheric-pressure standard gas mixtures with single photoelectrons. High single-electron detection efficiency is obtained in photon detectors combining THGEMs and semitransparent UV-sensitive CsI photocathodes or reflective ones deposited on the top THGEM face; the latter benefits of a reduced sensitivity to ionizing background radiation. Stable operation was recorded with photoelectron fluxes exceeding MHz/mm2. The properties and some potential applications of these simple and robust multipliers are discussed.Comment: 41 pages, 27 figures. Submitted to Nucl. Instr. and Meth. A, Dec 21, 200

Thick GEM-like multipliers - a simple solution for large area UV-RICH detectors

We report on the properties of thick GEM-like (THGEM) electron multipliers made of 0.4 mm thick double-sided Cu-clad G-10 plates, perforated with a dense hexagonal array of 0.3 mm diameter drilled holes. Photon detectors comprising THGEMs coupled to semi-transparent CsI photocathodes or reflective ones deposited on the THGEM surface were studied with Ar/CO2 (70:30), Ar/CH4 (95:5), CH4 and CF4. Gains of ~100000 or exceeding 1000000 were reached with single- or double-THGEM, respectively; the signals have 5-10 ns rise times. The electric field configurations at the THGEM electrodes result in an efficient extraction of photoelectrons and their focusing into the holes; this occurs already at rather low gains, below 100. These detectors, with single-photon sensitivity and with expected sub-millimeter localization, can operate at MHz/mm2 rates. We discuss their prospects for large-area UV-photon imaging for RICH.Comment: 5 pages, 6 figure

Physics of multi-GEM structures

We show that physics of multi-GEM structures is rather complex, regarding the number of phenomena affecting detector performance. The high-pressure operation in noble gases and the ion feedback are considered in more detail. It is proposed that the dominant avalanche mechanism in He and Ne, at high pressures, is the associative ionization. Ion feedback effects related to the dependence on gas, pressure and gain and to possible avalanche extension outside the GEM holes are discussed.Comment: Presented at the 8th International Conference on Instrumentation for Colliding Beam Physics, Novosibirsk, Febuary 28 - March 6, 2002. To be published in Nucl. Instr. and Meth.

Triad. Method for studying the core of the semiotic parity of language and art.

The purpose of this paper is to present and describe a new method for studying pre-speech language. The suggested approach allows correlate epistemology of linguistics to the ideological tradition of other scientific disciplines. Method is based on three linguistic categories – nouns, verbs, and interjections in their motor and expressive qualities – and their relation to the three basic forms of art – graphics (visual art), movement (dance), and sound (music). The study considers this correlation as caused by the nature of the human receptor system. This method explains the nature of art and the phenomenon of aesthetics and allows for the chronological arrangement of important cultural processes; it identifies the fundamental unanimity of the semiotic nature of language and art

Триада: Метод изучения сущности семиотического единства языка и искусства

Целью данного исследования является описание нового метода изучения доречевого языка. Предлагаемый подход позволяет соотнести эпистемологию лингвистики с общефилософскими мировоззренческими традициями других научных дисциплин. Метод построен на соответствии трёх лингвистических категорий – существительных, глаголов и междометий, по своим моторным и выразительным качествам, трём основным видам искусства – графике (изобразительному искусству), движению (танцу) и звукам (музыке), и рассматривает подобное соотношение как обусловленное природой рецепторной системы человека. Объясняя фундаментальное единство семиотической природы языка и феноменов искусства и эстетики, метод позволяет провести хронологизацию важных культурных процессов

Ion-induced effects in GEM & GEM/MHSP gaseous photomultipliers for the UV and the visible spectral range

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 liftime. We report on the significant progress in ion-blocking and provide first results on bialkali-photocathode aging under gas multiplication.Comment: 6 pages, 8 figure

High-gain DC-mode operated Gaseous Photomultipliers for the visible spectral range

We shortly describe recent progress in photon detectors combining bi-alkali photocathodes and cascaded patterned gas-avalanche electron multipliers. It permitted the development and the first feasibility demonstration of high-gain gaseous photomultipliers sensitive in the visible spectral range, operated in DC mode with single-photon sensitivity.Comment: Proceedings to the 5th International Conference on New Developments In Photodetection 2008, Aix-les-Bains, France, June 15-20, 2008, submitted to NIM