Results 1 - 10 of 17411
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[en] We study the usage of various definitions of sampling fractions in understanding electron shower shapes in a sampling multilayer electromagnetic calorimeter. We show that the sampling fractions obtained by the conventional definition (I) of (average observed energy in layer)/(average deposited energy in layer) will not give the best energy resolution for the calorimeter. The reason for this is shown to be the presence of layer by layer correlations in an electromagnetic shower. The best resolution is obtained by minimizing the deviation from the total input energy using a least squares algorithm. The 'sampling fractions' obtained by this method (II) are shown to give the best resolution for overall energy. We further show that the method (II) sampling fractions are obtained by summing the columns of a non-local λ tensor that incorporates the correlations. We establish that the sampling fractions (II) cannot be used to predict the layer by layer energies and that one needs to employ the full λ tensor for this purpose. This effect is again a result of the correlations.
[en] The aim of this workshop is to be prospective in two respects: .what new fields might be opened in heavy ion physics at 20 to 100 MeV per nucleon; .what role can play the best energy resolution which can be achieved experimentally, let say ΔE/E approximately 2 x 10-4
[en] This work describes the measurement of the resolution variation of a Ge(Li) detector as a function of irradiation position by a collimated gamma-ray beam. Also the resolution dependence has been measured as a function of the detector applied voltage, using collimated and non-collimated gamma-ray beam. (A.C.A.S.)
[pt]Neste trabalho descreve-se as medidas feitas da variacao da resolucao de um detetor Ge(Li) em funcao da posicao de irradiacao por um feixe colimado de radiacao gama. A dependencia da resolucao tambem foi medida em funcao da voltagem aplicada ao detetor utilizando-se feixes de radiacao gama colimados e nao colimados. (A.C.A.S.)
[en] After a brief description of the main techniques of calorimeter ocnstruction, the energy resolution is discussed and compared for am and hadron calorimeters. Ways to improve the resolution by the mechanism of compensation are presented and discussed. (author). 22 refs.; 12 figs.; 3 tabs
[en] At BINP the construction of the tagging system for almost-real photons (TS) is in progress. The energy of tagging photons can be up to 1.5 GeV. The projected energy resolution of TS is better then 1%. For at least a half of photons the linear polarization can be determined. The tagging system will extend the possibilities for photoreaction studying at VEPP-3 significantly. TS would allow to perform a complete kinematics reconstruction, thus permitting a reliable rejection of the background processes; to extend the measurements to higher photon energy; to enabling Σ-asymmetry measurements and double polarization experiments.
[en] From energy data storage it was possible to quantify (10 to 15%) the variations in the position of the photopeak of a given uniformly distributed isotope in different zones of the camera field. This position dependence of the energy can lead to errors when images formed in digital windows and normalized by a conventional non-uniformity correction are compared quantitatively. An automatic method for correcting this effect is proposed. It uses the sequential acquisition of 4 million events for a uniform plane source. A correction coefficient matrix (16x16) is established. The results obtained show that the energy resolution is increased for a plane source, passing from 21 to 17% for 57Co, and that the matrices formed in accurately chosen windows are more directly comparable when the photopeak position variations are reduced to 2%
[fr]Le stockage de l'information energie a permis de quantifier (10 a 15%) les variations de la position en energie du photopic d'un isotope donne de distribution uniforme dans differentes zones du champ de la camera. Cette dependance en position de l'energie peut entrainer des erreurs lorsqu'on compare quantitativement des images formees dans des fenetres digitales et normalisees par une correction de non uniformite conventionnelle. Une methode de correction automatique de cet effet est proposee. Elle utilise l'acquisition sequentielle de 4 millions d'evenements pour une source plane uniforme. Une matrice de coefficients de correction (16x16) est constituee. Les resultats obtenus montrent que l'on augmente la resolution en energie pour une source plane, qui passe de 21 a 17% pour le 57Co, et qu'en reduisant les variations de la position du photopic a 2% on rend les matrices formees dans des fenetres choisies avec precision plus directement comparables
[en] This tube includes a photocathode deposited on a transparent window at the end of an insulating sleeve tube, the photocathode is carried to a reference potential V0. This tube includes an unique amplifier stage constituted by a dynode; its shape is a metallic surface one leaning on a contour surrounding sensitively the photocathode and bearing on its inner face a secondary emission material coating; an anode, constituted by a metallic grid homeomorphic to the dynode surface, is set parallel to and at a little distance of this one. The dynode and the anode are carried respectively to an electric potential V1 higher than the reference potential V0 and at an electric potential V2 higher than the dynode potential V1. This tubes can be used in particle accelerators, in nuclear physics
[fr]Ce tube comporte une photocathode deposee sur une fenetre transparente a l'extremite d'un manchon isolant; la photocathode est portee a un potentiel V0 de reference. Ce tube comporte un etage amplificateur unique constitue par une dynode, de la forme d'une surface metallique s'appuyant sur un contour entourant sensiblement la photocathode et portant sur sa face interne une couche d'un materiau a emission secondaire; une anode formee par une grille metallique homeomorphe a la surface de la dynode est placee parallelement et a faible distance de celle-ci. La dynode et l'anode sont portees respectivement a un potentiel electrique V1 superieur au potentiel V0 de reference et a un potentiel electrique V2 superieur au potentiel V1 de la dynode. Ces tubes sont applicables en physique nucleaire, dans les accelerateurs de particules
[en] The research is aimed at establishing quantitative relation between the values of light and spectral photocathode sensitivity and energy resolution of photomultiplier. The quantitative dependence of the energy resolution of photo-multipliers on photocathode light and spectral sensitivity is established. In the experiments processed are the data of measurements on the NaI(TL) crystal of the Ca-1 type with the diameter 63x63 mm2 using 40 samples of ''Kulon'' photomultipliers and 50 samples of the FEhU-78B-type with Sb-K-Cs photocathode. The data available on light technical characteristics and results of separate measurements of energy destruction for photomultipliers with antimonycesium FEhU-82 and EM19531V photocathode also agree with the established dependence