E-T detector

When the E-T detector is used for compositional contrast, the Faraday cage should be negatively charged (-50 V) to exclude SEs with energies lower than the bias voltage of the cage. Some SEM systems are equipped with a dedicated detector for BSE collection, which is placed above the specimen. To obtain compositional contrast, we can switch detection from the SE mode to the BSE mode by simply pushing a button on the SEM control panel. 

Figure 2.6. Shaded regions are secondary electron trajectories, drawn to the E-T detector from any part of the surface by the +250 V bias. Arrows indicate the backscattered electrons. Very few will reach the E-T detector from the surface facing away from it, so the surface facing the detector will be brighter. To collect most backscattered electrons, a large area detector is required.

The detector in the SEM that is normally used for imaging is the Everhart-Thornley scintillator/photomultiplier (E-T detector). This is a low-noise, high-speed and efficient detector that detects a small fraction of the... 

HRSEM images of STA-7 were taken using a JEOL JSM-7000F (FE SEM). Images of silicalite-2 and zeolite A were taken on a JEOL JSM-7401F (cold-FE SEM) using the Everhart-Thomley (E-T) secondary electron detector. Samples were not coated but placed on a conductive surface. 

Now, the effective linear response function h(t) can be identified with g(t) as defined in Eqs. (25) and (29) h(t) = g(t). The primary sample response is the heterodyne diffraction efficiencyy (t) = Chet(t)- The instantaneous contribution of the temperature grating to the diffraction efficiency is expressed by the 5-function in g(t) [Eq. (25)]. After the sample, an unavoidable noise term e(t) is added. The continuous yff) is sampled by integrating with an ideal detector over time intervals At to finally obtain the time-discrete sequence y[n]. 

Veirs, D.K., Ager, J.W., Loucks, E.T. and Rosenblat, G.M. (1990) Mapping materials properties with Raman spectroscopy utilizing a 2-D detector. Appl. Opt., 29, 4969 1980. 

Fig. 5. Separation of testosterone (T), epitestosterone (E), testosterone TMSi ether (T-D), and epitestosterone TMSi ether (E-D) with an OV-17 column. Conditions 12-foot, 1% OV-17 (on 100-120 mesh Gas-Chrom P) column temperature programmed at 1° per minute from 200° injector, 260° detector, 300° flame detector. The separation of the free steroids is due to a difference in selective retention with an OV-17 phase. The secondary 17 8-OH group of testosterone is less sterically hindered than the secondary 17a-OH group of epitestosterone, and this leads to selective retention of testosterone compared with epitestosterone. The TMSi ethers are eluted in the same order, but the separation is based on a difference in molecular shape, just as observed for OV-1. The derivatives (E-D, T-D) are eluted before the free steroids (E, T) as a consequence of the selective retention effect of the phase for hydroxyl groups. Reproduced from Homing (H13) with permission.

If we consider that the induced activity measured at time t corresponds to A, = sly XN, with e, the detector efficiency and the y-ray abundance, then ... 

N Ep) dEp = proton recoil energy spectrum = number of protons produced (by collisions with neutrons) with energy between E and E -t- dE R(E, Ep) dE = response function of the detector = probability that a proton... 

The principal parts of a Fourier-transform spectrometer (FTS) are the Michelson interferometer with a moving mirror (see Fig.l) and a computer that performs the Fourier transform of the interferogram and thus calculates the spectrum of an incident radiation E(t). A detector registrates the averaged intensity at the output of the Michelson interferometer... 

Fig. 7. DuPont gradient elution accessory, a, b = proportioning valves, c = holding coil, d, e, T, g, k = valves, h = solvent reservoirs, 1 = source of gas under constant pressure 25 psi), j - vacuum, 1 = pump, m = drain, n = mixing chamber, p = chrofnatograph (injection port, column, detector(s)), q = measuring container.

Jewett, K.L. Brlnckman, F.E. In "Detectors in Liquid Chromatography" Vickrey, T.M., Ed, Marcel Dekker New York, 1983 Chap.6. Schwedt, G. "Chromatographic Methods in Inorganic Analysis" ... 

Now, E(<) is the sum of the electric fields E (t) of the beams impinging on the detector from scattering points 1,2,..., N in the small volume considered. Since these points are moving thermally, the E " (t) and hence E(t) fluctuate from time to time. Techniques using electronic devices to measure the resulting fluctuation of i(t) have been developed in recent years. The QELS method aims at extracting information about the motion of scattering points from the i t) data so obtained. To this end we introduce two functions Ci(r) and C2(r) defined by... 

For this purpose we make the following assumption. The bivariant probability P E t), E t + r)) that the electric field of scattered light at the detector has a given value of E(t) at time t and a given value of E(< -I- r) at time t -t- r is Gaussian. This means that... 

Turndown may be limited by (a) burner stability range, flammability limits, mixing quality, (b) valve leak or process low-flow limit, either of which raises the denominator in the t/d equation, (c) flow controller range limit, (d) low-pressure air atomizer for liquid fuel, (e) flame detector range, and (f) transmitter turndown (4 to 20 ma 5 1 t/d). 

In this example, input-output pairs I t), e and E t), f2, respectively, are collocated. Hence, the left-hand side flow source and the effort detector in Fig. 4.20 can be combined into one source-sensor element SS. The same holds for the right-hand side effort source and the flow detector. The bond graph of the inverse model is... 

Close examination of Eq. 1.1 leads to the discoveiy of a misnomen the UV incident radiation is not truly cut off when A = I (i.e., T 0 at = 1), but rather is markedly attenuated. As a result, the cutoff, as defined above, occurs when the transmitted beam intensity reaching the detector is attenuated to 10% of the incident radiation on the sample. 

The analyzed signal in the last equation is a quadratic function on a whose minimum abscissa is the pump-induced dichroism A0"(o)., t) and whose minimum ordinate is the pump-induced birefringence magnitude A0 (< ><, t). Measurements of T for several different angles a provide A< " and A0 as solutions of Eq. 16 without knowing the incident probe intensity E the detector sensitivity, and the sample transmission expt-2< "(o>., t)] in either the ground or the excited state. 

Brodzinski, R.L., Miley, H.S., Reeves, J.H. Avignone, E.T. (1990). Further reductions of radioactive backgrounds in ultra-sensitive germanium detectors, Nucl. Instr. Meth. Phys. Res., A, 292, 337-342. 

Figure Bl.7.18. (a) Schematic diagram of the trapping cell in an ion cyclotron resonance mass spectrometer excitation plates (E) detector plates (D) trapping plates (T). (b) The magnetron motion due to tire crossing of the magnetic and electric trapping fields is superimposed on the circular cyclotron motion aj taken up by the ions in the magnetic field. Excitation of the cyclotron frequency results in an image current being detected by the detector electrodes which can be Fourier transfonned into a secular frequency related to the m/z ratio of the trapped ion(s).

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