Coincidence recording

Anticoincidence, Coincidence Recording. An inherent problem in an anticoincidence-shielded spectrometer is that a decay scheme having gamma-rays in coincidence will appear to produce the same interaction between the Ge(Li) detector and anticoincidence shield as that of a Compton event. If only the events from the Ge(Li) detector are counted in the absence of a signal from the shield, those nuclides that decay... 

Figure 4.48 Typical spectrum of electron-electron coincidences recorded with a TDC. The data refer to a situation in which the photon beam has no time structure. True coincidences are collected in the peak while accidental coincidences give a flat and smooth background. At indicates the coincidence resolving time and dt the time resolution of the time-measuring device. The two shaded areas represent accidental coincidences, measured on the left-hand side together with the desired true coincidences, but on the right-hand side separately (and simultaneously) in the full time spectrum.

Fig.9.24. Delayed-coincidence recordings of decay curves for excited barium 6snd D2 states and plot of lifetime results for perturbed barium Rydberg state sequences. An excitation scheme can be found in Fig.9.5 ([9.101, first Ref.] and [9.102])... 

Comcidence experiments have been connnon in nuclear physics since the 1930s.The widely used coincidence circuit of Rossi [9] allowed experimenters to detennine, within tire resolution time of the electronics of the day, whether two events were coincident in time. The early circuits were capable of submicrosecond resolution, but lacked the flexibility of today s equipment. The most important distinction between modem comcidence methods and those of the earlier days is the availability of semiconductor memories that allow one to now record precisely the time relations between all particles detected in an experiment. We shall see the importance of tliis in the evaluation of the statistical uncertainty of the results. 

It is basically irrelevant in steady-state measurements in which direction the polarization curves are recorded that is, whether the potential is moved in the direction of more positive (anodic scan) or more negative (cathodic scan) values. But sometimes the shape of the curves is seen to depend on scan direction that is, the curve recorded in the anodic direction does not coincide with that recorded in the cathodic direction (Eig. 12.3). This is due to changes occurring during the measurements in the properties of the electrode surface (e.g., surface oxidation at anodic potentials) and producing changes in the kinetic parameters. 

It can be seen from Fig. 15.2 that in semilogarithmic plots of AE vs. log/, the polarization characteristics are linear [i.e., obey the Tafel equation (6.3)]. Slopes b practically coincide for most metals and have values of 0.11 to 0.13 V. However, the absolute values of polarization recorded for a given current density (CD) vary within... 

Carotenoid neutral radicals are also formed under irradiation of carotenoids inside molecular sieves. Davies and Mims ENDOR spectra of lutein (Lut) radicals in Cu-MCM-41 were recorded and then compared with the simulated spectra using the isotropic and anisotropic hfcs predicted by DFT. The simulation of lutein radical cation, Lut +, generated the Mims ENDOR spectrum in Figure 9.7a. Its features at B through E could not account for the experimental spectrum by themselves, so contribution from different neutral radicals whose features coincided with those of the experimental... 

The explosive decomposition of the solid has been studied in detail [6], The effect of moisture upon ignitibility and explosive behaviour under confinement was studied. A moisture content of 3% allowed slow burning only, and at 5% ignition did not occur [7], Thermal instability was studied using a pressure vessel test, ignition delay time, TGA and DSC, and decomposition products were identified [8], The presence of acyl chlorides renders dibenzoyl peroxide impact-sensitive [9], There is a further report of a violent explosion during purification of the peroxide by Soxhlet extraction with hot chloroform [10], Residual traces of the peroxide in a polythene feed pipe exploded when it was cut with a handsaw [11]. The heat of decomposition has been determined as 1.39 kJ/g. The recently calculated value of 69° C for critical ignition temperature coincides with that previously recorded. 

Thus, the region 2100-1830 cm 1 can be covered. This allows us to monitor CO(v,J) by resonance absorption and various M(CO)n [n = 3-6] as a result of near coincidences between the CO laser lines and the carbonyl stretching vibrations of these species. The temporal response of the detection system is ca. 100 ns and is limited by the risetime of the InSb detector. Detection limits are approximately 10 5 torr for CO and M(CO)n. The principal limitation of our instrumentation is associated with the use of a molecular, gas discharge laser as an infrared source. The CO laser is line tuneable laser lines have widths of ca. lO cm 1 and are spaced 3-4 cm 1 apart. Thus, spectra can only be recorded point-by-point, with an effective resolution of ca. 4 cm 1. As a result, band maxima (e.g. in the carbonyl stretching... 

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