Detector Effects

Recent advances have greatly decreased the difficulties raised by these cautionary points. In particular, on-line viscosimetry and multi-angle lightscattering make it possible to determine the molecular weight and viscosity of samples as a function of elution volume. With such detectors, effects of solute-column packing interactions become unimportant, since the properties of narrow fractions can be measured. These detectors will be discussed in greater detail below. 

To model diffraction intensities, detector effects and the background intensity from thermal diffuse scattering must be included. A general expression for the theoretical intensity considering all of these factors is... 

The contribution from the detector effective volume can be approximately expressed as... 

For packed columns, new spreading Is a minor perturbation of the peak variance. Here the detector effectively operates as a plug filter on the Gaussian Input function. Since a V. /F, the effects of new spreading Is hidden In the uncertainty ot t e peak variance. 

Table 2.1. Properties of different solid scintillation detectors Detectors Effective Density Scintillation Photon Linear Energy...

Detector effects. The detector may affect the measurement in two ways. First, the size and thickness of the detector window (Fig. 8.1) determine how many particles enter the detector and how much energy they lose, as they traverse the window. Second, particles entering the detector will not necessarily be counted. The fraction of particles that is recorded depends on the efficiency of the detector (see Sec. 8.4.2). 

Because of pile-up and detector effects, a breakthrough in the counting capability of TCSPC cannot be achieved by simply making the signal processing electronics of the TCSPC device faster. 

Once all the simulated noises are computed, they are added to the interferograms at the Add Noise Module to simulate more realistic measurements. The simulated interferograms are then sent to the Detector Module, where the interferograms are distorted according to the detector effects such as the time response. This interferograms are then sampled and readout at the Sampling and Readout Module, which also stores the data for the data reduction and processing. 

TmeEffects, that allows the computation of the interferograms in a way that time effects such as the drive velocity errors can be included in the simulation. DetectorEffects, to create a set of interferograms including all the detector effects (otherwise the simulator returns the raw interferograms, which is described later in this chapter). 

This represents the time-dependence of the projection of the muon polarization on the axis of the positron detectors, effectively now for muons that are initially 100% polarized. This is the quantity provided by most theories, and is therefore what one wishes most to learn from the experiment. However, Aq can be divided out of the Fourier transform of the data as easily as from the signal, so it usually suffices to transform S(t). 

There are several primary contributors to system instability. The most prevalent is oscillator phase noise. Others include timing jitter, amplifier additive noise, A/D quantization, and I/Q detector effects. 

Mehran, M.T. Golkar, N. Cooper, W.T. and Vickers, A.K. Headspace analysis of some typical organic pollutants in drinking water using differential detectors Effects of columns and operational parameters. Journal of Chromatographic Science 1996, 34 (3), 122-129. 

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