Beam index tube

The Ce -activated cathode-ray phosphors are used in applications where a very short decay time is a requirement [13). Since the emi.ssion is a completely allowed transition (5t/-> 4/, Sect. 3.3.3Ji), the decay time of Ce varies between about 15 and 70 ns, depending on the emission wavelength. One application is in the beam-index tubes which generate color images by means of one electron gun [1,13]. This system could, however, never compete with the above-mentioned shadow-mask tube. The beam-index phosphor indicates the location of the electron beam. Therefore, the emission should have a very short decay time and, in order not to disturbe the image, should be situated in the ultraviolet. A good choice is Y2Si2C>7 rCe with a radiant... 

When heat is produced in the sample after the photolytic flash, the refractive index of the liquid changes and the probe beam is deflected. The intensity of this probe beam measured by a photomultiplier tube placed behind the pinhole decreases as the temperature of the irradiated volume increases (then its density and its refractive index decrease). The total optical signal change is a measurement of all the heat produced in the sample, i.e. the sum of non-radiative transitions, chemical reactions and solvation energies. Luminescence does not contribute to this signal (nor does scattered light) and for this reason thermal lensing can be used to determine luminescence quantum yields. 

One of the most satisfactory types of apparatus yet developed is that of Zimm (1948 b). In his arrangement, the cell containing the liquid under study is a small thin-walled glass bulb, immersed in an outer cell containing a liquid of approximately the same refractive index as that in the inner cell. The scattered light is received on a photomultiplier tube, while a portion of the incident beam falls on a phototube of much lower sensitivity. The currents produced in the two tubes are balanced in a precision potentiometer at balance, the setting of the potentiometer shows the ratio of the currents. Details of the electronic circuit are given... 

Miniaturization Application of lasers as light sources resulted in a reduction in the size of refractive index detectors and made them compatible with in-line monitoring systems that are needed in capillary separation technology. The refractive index of minute amounts of solution may be determined by the measurement of the diffraction phenomenon produced in the interaction between the laser beam and a fluid-filled capillary. The laser beam passing through an off-center capillary produces a fan of scattered light in the plane perpendicular to the tube axis. The position of a single line corresponds to the refractive index of the fluid within the tube... 

The dosimetric quantities typically used in CT are the CT dose index (CTDI) and the dose length product (DLP). The CTDI is defined for an axial CT scan (one rotation of the X-ray tube) by dividing the integral of the absorbed dose along the z axis by the nominal beam width. As shown in Fig. 4.2, this value is equivalent to the dose within the nominal width of the slice assuming that the absorbed dose has a rectangular profile with a constant dose inside the nominal width and zero dose outside. 

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