Results 1 - 10 of 85159
Results 1 - 10 of 85159. Search took: 0.049 seconds
|Sort by: date | relevance|
[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] A few references are made to factors which affect the energy resolution of proportional scintillation. The coupling of proportional or primary scintillation devices to photoionization detectors (PIPS chamber) is considered, both in the gas and liquid phases, and using the data available some information is given concerning its expected characteristics of energy, position and time resolution. (orig.)
[en] Theoretical base of resolution is presented for a system of scintillation detectors combined with pulse shaping or calculating circuits. Using time-dependent probability generating functions, it has been shown that each of energy, timing and positioning resolution consists of two components. These components have different dependence on time due to the combined circuits. From the theoretical application, a method for determining the statistical component of energy resolution is also proposed. In this method, a scintillation current pulse is divided into two parts at the time when half of the mean full charge has been collected, and the statistical component is determined from the statistical fluctuation of the difference between charges collected in the two periods. (author)
[en] We demonstrate subwavelength spatial resolution with a scanning microlens operating in collection mode with a large-area detector. Optical contrast is created by refraction of off-axis light rays at angles larger than the maximum collection angle. With a microfabricated silicon microlens 10 μm in diameter, we measure spatial resolution due to refraction contrast of λ/4.3 at a wavelength of λ=10.7 μm. A model based on ray tracing is developed to explain our result, and we show that lens diameter and index of refraction limit resolution for large emission and collection angles. [copyright] 2001 American Institute of Physics
[en] Residual elastic strain in naturally deformed, quartz-containing rocks can be measured quantitatively in a petrographic thin section with high spatial resolution using Laue microdiffraction with white synchrotron x-rays. The measurements with a resolution of one micrometer allow the quantitative determination of the deviatoric strain tensor as a function of position within the crystal investigated. The observed equivalent strain values of 800-1200 microstrains represent a lower bound of the actual preserved residual strain in the rock, since the stress component perpendicular to the cut sample surface plane is released. The measured equivalent strain translates into an equivalent stress in the order of ∼ 50 MPa
[en] We summarize recent R and D progress for a silicon-tungsten electromagnetic calorimeter (ECal) with integrated electronics, designed to meet the ILC physics requirements. A basic physics requirement for ILC detectors is that they provide excellent reconstruction of hadronic final states. This allows access to new physics which is complementary to the LHC. One statement for a requirement on jet reconstruction is that intermediate particles which decay into jets, such as W, Z, or top, can be identified and isolated. This places unprecedented requirements on 2-jet or 3-jet mass resolution, typically at the level of 3-5% using the PFA technique, which makes challenging demands on the calorimeters. The electromagnetic energy resolution is not expected to limit jet resolution using a PFA. However, particle separation - photon-photon and charged hadron-photon - is crucial. In addition, if one provides this kind of imaging calorimeter to meet the PFA needs, these same features will also be put to good use for reconstruction of specific tau decay modes (to enable final-state polarization measurement), to 'track' photons (even if originating from a vertex displaced from the interaction point), to track MIPS, and so forth. Figure 1 and Table 1 provide some context for our ECal design within the SiD detector concept, along with some main design parameters. More detail is included in the presentation.
[en] The D0 experiment is recording physics quality data. Both the detector and the accelerator performance are continually improving. We are studying issues such as the b(bar b) mass resolution, b-jet tagging efficiency, missing ET resolution, and backgrounds to Higgs processes. We look forward to seeing exciting results. The status of the Higgs search at the upgraded D0 detector is discussed