Double detector

Previously, it has been demonstrated that by use of a double detector and ion counting optimal piedsion and sensitivity in the quantitative determination of isotopic distributions can be achieved. ... 

Off-line SEC-NMR (which consists of collecting the SEC fractions, evaporating the solvent and then adding a deuterated solvent) does not suffer the above drawbacks. The signal-to-noise ratio is good when medium-field magnets (200 MHz up to 500 MHz) are employed thus, the cost of such experimental set-up is attractive, i.e., on the same order of magnitude of double-detector SEC assemblies. 

Abstract Most radiation related to nuclear properties is outside the visible part of the electromagnetic spectrum or involves submicroscopic particles, hence is invisible. Detectors -devices to sense the radiation, and perhaps measure its properties - are essential. The emphasis in research has moved from the characteri2ation of radioactivity, through simple nuclear reactions, to explorations of the extremes of nuclear matter, but the central importance of suitable radiation detectors has persisted. This chapter emphasi2es detectors associated with measurements of radioactivity, as opposed to nuclear reactions. Thus, much of the current creative work is excluded, but otherwise the scope of these volumes would at least double. Detectors are classified broadly as based on ionization of gases, conduction in semiconductors, or scintillation. The concluding section is an introduction to systems based on two or more components of one of these basic types. 

In the acausal bond graph representation, replace the modulated elements (resp. detectors) associated with inputs (resp. outputs) by double detectors DeDf (resp. double sources SeSf). 

Along each power line chosen at step I propagate bicausality from the double source to the double detector and propagate causality through the junction structure taking into account the causality constraints ofO- and I-junctions, TF-and GY-elements. If at this step causal conflicts or non-solvable causal loops appear, repeat the previous steps with another set of disjoint I/O power lines. If none of them solves the problem of causal conflicts or non-solvable causal loop appearance then the model is not invertible (Criterion 3) and the procedure stops. 

Compare the calculated conjugate power variables at the double detector ports to the data of the manufacturer s documentation. 

Undesired effects in fluorescence confocal microscopy can be corrected by ratio imaging. Rati-oing (i.e., the compensation of two channels by digital division) can substantially reduce cross-talk effects in double detectors [63]. Environmental markers indicating the pH value or the level of free calcium ions (Ca"" ) also require ratio imaging to compensate for structural densities or section thickness [19]. 

Determined by GPC with small-angle light scattering and RI double detectors. 

This is a double-channel flaw detector having their own microcomputer with 1 Mbyte memory to store data of the LMA and the LF channels for 800...2000 m of a rope under inspection. The instrument can be used in two modes as a tester for operative inspection or as a device for the inspection data storage. 

A much better way would be to use phase contrast, rather than attenuation contrast, since the phase change, due to changes in index of refraction, can be up to 1000 times larger than the change in amplitude. However, phase contrast techniques require the disposal of monochromatic X-ray sources, such as synchrotrons, combined with special optics, such as double crystal monochromatics and interferometers [2]. Recently [3] it has been shown that one can also obtain phase contrast by using a polychromatic X-ray source provided the source size and detector resolution are small enough to maintain sufficient spatial coherence. 

Objects which are not covered completely by the fan-beam, which is defined by the linear detector array and the source can be inspected in a special mode. In this case the usable width of the fan is doubled, by placing the turning centre of the object onto the two edges oft the fan. 

Figure Bl.10.8. Time spectrum ftom a double coincidence experiment. Tln-ough the use of a delay in the lines of one of the detectors, signals that occur at the same instant in botii detectors are shifted to tlie middle of the time spectrum. Note the unifonn background upon which the true comcidence signal is superimposed. In order to decrease the statistical uncertainty in the detemiination of the true coincidence rate, the background is sampled over a time Aig that is much larger than the width of the true coincidence signal. Ax.

Figure Bl.10.11. Electron impact double ionization triple coincidence experiment. Shown are the source of electrons, target gas, tluee electron detectors, one for the scattered electron and one for each of the ejected...

The amplified signal is passed to a double-balanced mixer configured as a phase-sensitive detector where the two inputs are the NMR signal (cOq) and the frequency of the synthesizer (03. gf) with the output proportional to cos(coq - co gj.)t + 0) + cos((coq + + 9). The sum frequency is much larger than the total bandwidth of the... 

Infrared instruments using a monochromator for wavelength selection are constructed using double-beam optics similar to that shown in Figure 10.26. Doublebeam optics are preferred over single-beam optics because the sources and detectors for infrared radiation are less stable than that for UV/Vis radiation. In addition, it is easier to correct for the absorption of infrared radiation by atmospheric CO2 and 1420 vapor when using double-beam optics. Resolutions of 1-3 cm are typical for most instruments. 

Fig. 25-2. Double-beam, double-pass transmissometer for measuring smoke density in stacks. A[, chopper wheel A, beam gating wheel A3, aperture D, detector Fj, spectral filter F2, solenoid-activated neutral density filter L, lamp M, half-mirror/beam splitter Rj, solenoid-activated zero calibration reflector R2, retroreflector (alignment bullseye not shown). Design patented. Source Drawing courtesy of Lear Siegler, Inc.

For measurement of local ion intensities in the direct imaging mode (see Fig. 3.19), amplification ensuring laterally uniform-single ion detection is necessary. Depending on the sensitivity of the detector a single or double channel plate is used. Two imaging devices are in use ... 

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