Detectors integral

An instantaneous detector is related functionally to an integrating detector as an ammeter is to a coulometer. Most detectors can function in either manner, though not necessarily with comparable efficiency or... 

To the analytical chemist, a standard deviation31 is a logical figure of merit for the comparison of detectors. We shall merely introduce the important subject of counting errors (10.2) here. For present purposes, it suffices to know that these errors are predictable, and that they set a lower limit to the standard deviation in an analytical method that depends upon measuring the intensity of an x-ray beam by an integrating detector. 

Integrating capacitor in PXQ, 256 Integrating detectors, 43, 44 Intensifying screens, 12, 13, 44... 

In order to assess the accuracy of the present method, we compared it with two other methods. One was the Track Etch detector manufactured by the Terradex Corp. (type SF). Simultaneous measurements with our detectors and the Terradex detectors in 207 locations were made over 10 months. The correlation coefficient between radon concentrations derived from these methods was 0.875, but the mean value by the Terradex method was about twice that by our detectors. The other method used was the passive integrated detector using activated charcoal which is in a canister (Iwata, 1986). After 24 hour exposure, the amount of radon absorbed in the charcoal was measured with Nal (Tl) scintillation counter. The method was calibrated with the grab sampling method using activated charcoal in the coolant and cross-calibrated with other methods. Measurements for comparison with the bare track detector were made in 57 indoor locations. The correlation coefficient between the results by the two methods was 0.323. In the case of comparisons in five locations where frequent measurements with the charcoal method were made or where the radon concentration was approximately constant, the correlation coefficient was 0.996 and mean value by the charcoal method was higher by only 12% than that by the present method. 

Skinner, S.W. and P.C. Nyberg, Method for the Calculation of Radon Response Characteristics of Integrating Detectors, Health Physics 45 544-550 (1983). 

Although in principle the time structure of the SR beam may be exploited in time resolved studies the major limiting factor is the rate at which three dimensional data may be accumulated. In this respect time resolved methods are bound to develop in tandem with the development of high count rate/fast refresh rate electronic area detectors. This applies to both monochromatic and white beam methods. For the latter the use of an integrating detector such as a CCD or image plate are the main expected improvements over film. 

Figure 7 shows the absorption efficiency of the BaFBr calculated as a function of the X-ray photon energy. The absorption efficiency is 96% for 17keV X-rays when the phosphor is 150 pm thick. The absorption edge at 37.4 keV is due to barium. The quantum efficiency of integrating detectors, however, can not be determined by the absorption efficiency alone, because the noise level of the system causes the quantum efficiency of these detectors to deteriorate. In Fig. 8, the relative uncertainty... 

Integral detector. A detector dependent on the total amount of a sample component passing through it. 

The response we can distinguish differential detectors, which monitor the difference in the composition of the column effluent, and integral detectors, which measure the amount of sample component passing through the detector. 

Mass spectrometry (MS) is now an integrated detector for liquid chromatography. This is due to the advent of atmospheric pressure ionization (API) interfaces. In an API interface, the column effluent is nebulized into an atmospheric pressure ion region. Nebulization is performed pneumatically in atmospheric pressure chemical ionization (APCI) by a strong electrical field in electrospray or by a combination of both in ion spray. Ions are produced from the evaporating droplets... 

A micromachined CE device featuring a truly monolithically integrated detector has been recently reported by Webster et al. [79]. A semiconductor radiation detector was fabricated together with a separation channel on a silicon substrate in a 10-mask process. The preliminary results achieved with the detection of beta decay events of 32P-labeled DNA at 27 V/cm demonstrate the feasibility of the concept. 

While these data show that the image dissector is superior to the silicon target vidicon in several respects for atomic spectroscopy, the silicon vidicon and other integrating detectors retain significant advantages for molecular absorption (39) and fluorescence spectroscopy (40) where resolution requirements are not so demanding, available radiant fluxes are higher, and a... 

High Performance Size Exclusion Chromatography. The Hewlett-Packard 1090 liquid chromatograph was used with the HP 1040 diode array or HP 1037A refractive index (and HP 3392 integrator) detectors. A fifty A (5 mm, 300 x 7 mm) Polymer Laboratories PL gel (polystyrene-divinylbenzene copolymer gel) column was used and standards were as described in Chum et al. (13). Tetrahydrofuran solutions of oil and oil fractions were analyzed. 

The reservoir can also act as a post-column reactor. The appropriate reagent is dissolved in the mobile phase and will react immediately with any solute eluted from the column to form a derivative that can be sensed by the detector. Using the integral detector as a post-column reactor, however, can only be successful if the derivatives are not... 

Integrating systems, the main representative of which is the TV-tube detector, do not suffer from this limitation. In these systems, the signals of many photon events are accumulated in the detector itself, and only the integrated result is stored. At first glance, the integrating detectors seem to be advantageous for synchrotron radiation applications. However, several drawbacks have to be taken into account as we will see. 

In the absence of an appropriate technique for measuring analyte contents directly in the drop, this must be transferred to a detection device. There are two different ways of transferring samples from an acoustic levitator to an analytical detector, namely by transferring the whole sample to an integral detector (e.g. a graphite-furnace atomic absorption... 

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