Search results for "Dead Time"
showing 10 items of 22 documents
Enhanced detection of terrestrial gamma-ray flashes by AGILE
2015
At the end of March 2015 the onboard software configuration of the Astrorivelatore Gamma a Immagini Leggero (AGILE) satellite was modified in order to disable the veto signal of the anticoincidence shield for the minicalorimeter instrument. The motivation for such a change was the understanding that the dead time induced by the anticoincidence prevented the detection of a large fraction of Terrestrial Gamma-Ray Flashes (TGFs). The configuration change was highly successful resulting in an increase of one order of magnitude in TGF detection rate. As expected, the largest fraction of the new events has short duration (<100 μs), and part of them has simultaneous association with lightning sfer…
Effects of dead time losses on terrestrial gamma ray flash measurements with the Burst and Transient Source Experiment
2010
[1] Measurements from the Burst and Transient Source Experiment (BATSE) instrument on the Compton Gamma Ray Observatory (CGRO) are the only ones where characteristics of single terrestrial gamma ray flashes (TGFs) have been obtained thus far. However, it has been reported that the measurements suffer from significant dead time losses which complicates the analysis and raises question about earlier BATSE studies. These losses are due to the high-intensity flux combined with limitations of the time resolution of the instrument. Since these losses will affect both the spectrum and the temporal distribution of the individual TGFs, results based on BATSE data need to be revisited, including our …
Performance of Markers and the Homologous Series Method for Dead Time Estimation in Reversed-Phase Liquid Chromatography
2009
Abstract Two methods for dead time estimation (the use of markers and the homologous series mathematical method) are revised. Out of twelve assayed common markers, only KBr, KI, tartrazine, thiourea, uracil, and urea yielded retention times independent of the mobile phase composition in the range 10–90% acetonitrile, using a Zorbax Eclipse XDB−C18 column. On the other hand, the quality of the estimations provided by the homologous series method was limited by the mathematical approach and the data quality. With this method, the estimated dead time is an extrapolated value, which is severely affected by the data of the most retained compounds that act as leverage points, biasing the result. …
On the Measurement of Dead Time in Micellar Liquid Chromatography
1996
Abstract Modelling of the retention of solutes in micellar liquid chromatography allows the optimization of the resolution of a mixture of solutes and the determination of physico-chemical retention parameters. Both tasks imply the calculation of capacity factors, which are severely affected by the value of dead time. However, the determination of the dead time is not easy when a micellar mobile phase is used owing to the wide and variable perturbations that appear at the heads of the chromatograms. Four different criteria of determination of a reference time in the chromatograms are proposed and compared. The criteria are applied to mobile phases containing a varying concentration of surfa…
Global treatment of chromatographic data with MICHROM
1997
Abstract The program MICHROM for the general treatment of chromatographic data is presented. MICHROM takes part in all the stages of the analytical process. It allows determination of dead time, smoothing of chromatograms, measurement of peak parameters, fitting of skewed peaks, and deconvolution of overlapped peaks. Tools for the experimental design, optimization of the mobile phase composition to resolve a mixture of analytes, and simulation of chromatograms in several experimental conditions, are implemented. Routines for the graphical representation of chromatograms, resolution surfaces, contour maps, management of data series, optimization and regression analysis, are also included. Th…
Conceptual design of the TRACE detector readout using a compact, dead time-less analog memory ASIC
2015
[EN] The new TRacking Array for light Charged particle Ejectiles (TRACE) detector system requires monitorization and sampling of all pulses in a large number of channels with very strict space and power consumption restrictions for the front-end electronics and cabling. Its readout system is to be based on analog memory ASICs with 64 channels each that sample a View the MathML source window of the waveform of any valid pulses at 200 MHz while discarding any other signals and are read out at 50 MHz with external ADC digitization. For this purpose, a new, compact analog memory architecture is described that allows pulse capture with zero dead time in any channel while vastly reducing the tota…
Digital techniques for high-rate high-resolution radiation measurements
2014
Digital pulse processing (DPP) techniques are increasingly used in the development of modern spectroscopic systems. DPP systems, based on direct digitizing and processing of detector signals (preamplifier output signals), ensure higher flexibility, stability, lower dead time, higher throughput and better energy resolution than traditional pulse processing systems. In this work, we present our progress in the development of DPP systems for high-rate high-resolution radiation measurements. An innovative digital system, able to perform multi-parameter analysis (input counting rate, pulse height, pulse shape, event arrival time, etc.) even at high photon counting rates is presented. Experimenta…
Dead-time impact on the harmonic distortion and conversion efficiency in a three-phase five-level Cascaded H-Bridge inverter: mathematical formulatio…
2023
To avoid leg short-circuit in inverters, dead time must be introduced on leg gate signals. Dead time affects the inverter output voltage fundamental harmonic amplitude, voltage harmonic distortion and inverter efficiency by introducing additional voltage drops. In this regard, dead time effects have been widely investigated for traditional two-level three-phase voltage source inverters in the literature but not extensively for multilevel topology structures. This paper provides a detailed analysis of dead time impact on the harmonic distortion and efficiency of Cascaded H-Bridges Multilevel Inverters (CHBMIs). For this purpose, a general mathematical formulation to determine voltage drop du…
Energy resolution and throughput of a new real time digital pulse processing system for x-ray and gamma ray semiconductor detectors
2013
New generation spectroscopy systems have advanced towards digital pulse processing (DPP) approaches. DPP systems, based on direct digitizing and processing of detector signals, have recently been favoured over analog pulse processing electronics, ensuring higher flexibility, stability, lower dead time, higher throughput and better spectroscopic performance. In this work, we present the performance of a new real time DPP system for X-ray and gamma ray semiconductor detectors. The system is based on a commercial digitizer equipped with a custom DPP firmware, developed by our group, for on-line pulse shape and height analysis. X-ray and gamma ray spectra measurements with cadmium telluride (Cd…
High Resolution X-Ray Spectroscopy with Compound Semiconductor Detectors and Digital Pulse Processing Systems
2012
The advent of semiconductor detectors has revolutionized the broad field of X-ray spectroscopy. Semiconductor detectors, originally developed for particle physics, are now widely used for X-ray spectroscopy in a large variety of fields, as X-ray fluorescence analysis, X-ray astronomy and diagnostic medicine. The success of semiconductor detectors is due to several unique properties that are not available with other types of detectors: the excellent energy resolution, the high detection efficiency and the possibility of development of compact detection systems. Among the semiconductors, silicon (Si) detectors are the key detectors in the soft X-ray band (15 keV) and will continue to be the c…