Detection in field

Transportable high-current KEC-25M betatron on 25 MeV energy with power dose of radiation on 1 m away from the target of 30 Gr/min is the source of penetrating radiation intended for flaw detection in field conditions and radiation visualization of dynamic processes [2]. 

G.V.Akulov, V.I.Bogdashkin, V.A.Moskalev, V.L.Nikolaev, A.V.Tzimbalist, V.V.Shashov, V.G.Shestakov - Mobile betatron installation on energy of 25 MeV for radiative visualization of dynamic processes and flaw detection in field conditions. Atomic science and technique problems. Electrophysical equipment. -1987,v.23,p. 19-21. 

Particularly rich in B. are pollens (for Brassica napus ca. 100 xg/kg). B., especially brassinolide and 24-epibrassinolide, have unusually high phytohormonal activity. B. effect a general promotion of growth in plants (e. g., in roots), stimulate photosynthesis and protein biosynthesis, modulate the mode of action of other phytohormones, and delay senescence processes. B. exhibit antiecdysteroid effects on insects. For practical uses of B. the so-called anti-stress action on plants is of major interest and has been detected in field experiments under unfavorable cultivation conditions (e.g., drought, cold, nutrient deficiency, pest infestation). 

The product species detected in this simulation study were compared (Table 5.2) with the species detected in field observations [ 106]. It is foimd that the neutral species observed in the laboratory resemble the constituents observed in the Earth s atmosphere. On the basis of this resemblance, it is concluded that the MW discharge-induced chemistry observed in the N2/O2/H2O plasma may be helpful for understanding atmospheric chemistry. Laboratory simulation experiments can yield results directly applicable to the Earth s atmosphere. It should be noted, however, that there are significant differences in the relative amounts of the prodncts, especially for NO and HNO2. The ionic products were compared with those detected by Eisele et al. [107] in a remote desert area of southeastern Arizona and on top of Moimt Washington in New Hampshire. No agreement in terms of the prodncts, except for one species at miz 60. A number of ionic clusters with NO+ and H2O+ produced by gas-phase ion-molecule reactions were detected, bnt the NH + prodncts observed by Eisele were not observed. This difference remains imexplained at this time. The as-yet-nnidentified ionic species at mIz 60 in both stndies is probably NO (NO), which is present with considerable intensity in the plasma at a H2O partial pressure of 1 Pa. It is assumed that some of the ionic prodncts foimd in the simnlation study... 

Due to the symmetrical construction the resulting magnetic field between the two coils is zero in y-direction, if a conductive structure is symmetrically situated in the area a (see fig. 3) in the near of the probe. A resulting field is detectable by the Hall-effect device, if there are unsym-metrics in the structure in area a. The value of the Hall voltage is proportional to the detected magnetic field. 

Since optical fields oscillate too quickly for direct detection, they are measured in quadrahire —as photons (see below). There are two ways to achieve quadrahire. One is homodyne detection in which the new field is measured at... 

The nonlinear response of an individual molecule depends on die orientation of the molecule with respect to the polarization of the applied and detected electric fields. The same situation prevails for an ensemble of molecules at an interface. It follows that we may gamer infonnation about molecular orientation at surfaces and interfaces by appropriate measurements of the polarization dependence of the nonlinear response, taken together with a model for the nonlinear response of the relevant molecule in a standard orientation. 

Flow which fluctuates with time, such as pulsating flow in arteries, is more difficult to experimentally quantify than steady-state motion because phase encoding of spatial coordinate(s) and/or velocity requires the acquisition of a series of transients. Then a different velocity is detected in each transient. Hence the phase-twist caused by the motion in the presence of magnetic field gradients varies from transient to transient. However if the motion is periodic, e.g., v(r,t)=VQsin (n t +( )q] with a spatially varying amplitude Vq=Vq(/-), a pulsation frequency co =co (r) and an arbitrary phase ( )q, the phase modulation of the acquired data set is described as follows ... 

Alternatively, ions of any one selected m/z value can be chosen by holding the magnetic field steady at the correct strength required to pass only the desired ions any other ions are lost to the walls of the instrument. The selected ions pass through the gas cell and are detected in the singlepoint ion collector. If there is a pressure of a neutral gas such as argon or helium in the gas cell, then ion-molecule collisions occur, with decomposition of some of the selected incident ions. This is the MS/MS mode. However, without the orthogonal TOF section, since there is no further separation by m/z value, the new ions produced in the gas cell would not be separated into individual m/z values before they reached the detector. Before the MS/MS mode can be used, the instrument must be operated in its hybrid state, as discussed below. 

Fig. 9. Spectral sensitivity of detectors where the detector temperatures in K are in parentheses, and the dashed line represents the theoretical limit at 300 K for a 180° field of view, (a) Detectors from near uv to short wavelength infrared (b) lead salt family of detectors and platinum siUcide (c) detectors used for detection in the mid- and long wavelength infrared. The Hg CdTe, InSb, and PbSnTe operate intrinsically, the doped siUcon is photoconductive, and the GaAs/AlGaAs is a stmctured supedattice and (d) extrinsic germanium detectors showing the six most popular dopants.

Chemical and biological sensors (qv) are important appHcations of LB films. In field-effect devices, the tunneling current is a function of the dielectric constant of the organic film (85—90). For example, NO2, an electron acceptor, has been detected by a phthalocyanine (or a porphyrin) LB film. The mechanism of the reaction is a partial oxidation that introduces charge carriers into the film, thus changing its band gap and as a result, its dc-conductivity. Field-effect devices are very sensitive, but not selective. 

In field testing, there are many commercial products and instmments available that ate helphil in rapidly detecting, identifying, and quantifying micro organisms. 

Future developments of this instrumentation include field emission electron sources at 200-300 kV that will allow better elemental detectability and better spatial resolution. Multiple X-ray detectors having large collection angles will also improve elemental detectability in X-ray microanalysis. The higher accelerating... 

Detector tube A direct method for identifying airborne contaminants, also known as length-of-stain tube. It is a convenient tool for detecting and quantifying contaminants in field or emergency situations. 

---