Receiving slit

The absorption sample is mounted in the standard filter holder located between the monochromator crystal and the geiger-counter receiving slit. Pertinent distances are as follows target to quartz ciystal, 17 cm. quartz crystal to receiving slit, 17 cm. absorption sample to receiving slit, 6 cm. 

Powder X-ray diffraction patterns (XRD) for saponite and the corresponding PCH derivative were measured on Rigaku Rotaflex diffractometer equipped with a rotating anode under 45 kV and 100 mA and CuKa radiation (A = 1.542 nm). The scattering and receiving slits were 1/6 and 0.3 degrees, respectively. 

A pharmacosurveillance study performed in 268 children aged between 2 and 15 years and having received SLIT for up to 3 years showed that the overall incidence of systemic side effects involved 3% of the patients and 1/12,000 doses. Out of 8 side effects, only one (urticaria) was moderate and required treatment with a single dose of oral antihistamine. Overall, in none of the patients was the treatment discontinued [47],... 

Another pharmacosurveillance study in adult patients was recently published [48], One hundred and ninety-eight patients were observed while receiving SLIT either preseasonally or continuously over a 3-year period. Side effects were observed in 7.5% of patients and 0.52/1,000 doses administered. Four urticaria and 2 gastrointestinal complaints were judged as moderate. Also in this study, side effects were controlled by a temporary dose adjustment and in no case was the treatment discontinued. 

These data were collected on a Siemens D500 diffractometer, using monochromatic CuKa radiation, 6 seconds count time and a 0.01° 29 step size. The receiving slit was 0.05 and the apertures were 0.3°. The data were processed using programs written at Union Carbide Corporation. 

Measuring the portion of the diffracted intensity that passes through receiving slits, monochromator and detector windows. 

Knowledge of many other factors, such as the volume of the specimen which participates in scattering of the incident beam, the fraction of the irradiated volume which is responsible for scattering precisely in the direction of the receiving slit, and so on. 

This proportionality holds as long as the distance between the specimen and the receiving slit of the detector remains constant at any Bragg angle. 

Figure 3.7. Horizontal (left) and vertical (right) orientations of a flat sample. The location of the goniometer axis is shown using a dash-double dotted line with small filled circles at the ends. The dashed line indicates the location of the optical axis, which is the line connecting the focus of the x-ray tube, the receiving slit and the sample surface in the reflection geometry, or the sample center in the transmission geometry at 0 = 20 = 0°.

Figure 3.8. The schematic of the Bragg-Brentano focusing geometry using a flat sample when the self-focused diffracted beam is registered by the detector after reflection from the sample. F - focus of the x-ray source, DS - divergence slit, RS - receiving slit, D - detector, 0 -Bragg angle.

The second slit box is located on the detector arm between the sample and the detector. The slit nearest to the sample serves as a scatter slit. It is followed by another Soller slit and a receiving slit positioned just before the detector. The detector in this case is a solid-state detector, which is cooled by a built-in Peltier refrigerator enabling to adjust and maintain the detector sensitivity at extremely narrow width to allow only x-ray photons of specific energy to be registered. Monochromatization of the diffracted x-ray beam is, therefore, achieved electronically rather than by physical means (e.g. by a P-filter or a crystal monochromator), which increases the registered diffracted intensity by eliminating losses in the filter or in the monochromator. 

Figure 3.13. The overall view of the goniostat of the Rigaku TTRAX rotating anode powder diffractometer with the horizontal goniometer axis, and synchronized rotations of both the x-ray source and detector arms. This goniometer is equipped with variable divergence, scatter and receiving slits, curved crystal monochromator, and scintillation detector. (Courtesy of Rigaku/MSC.)...

Figure 3.33. The schematic of monochromatization of the diffracted beam using a curved crystal monochromator. RS - receiving slit, M - curved monochromator, MS -monochromator scatter slit, D - detector. The dash-dotted arc represents the goniometer circle. The dashed arc shows the focusing circle of the monochromator.

Figure 3.34. The set of x-ray powder diffraction patterns collected from the nearly spherical LaNi4 gsSno.is powder (see Figure 3.32, inset) on a Rigaku TTRAX rotating anode powder diffractometer using Mo Ka radiation. Goniometer radius R = 285 mm receiving slit RS = 0.03° flat specimen diameter d = 20 mm. Incident beam apertures were 0.05, 0.17, 0.25, 0.38, 0.5, 0.75, 1, 1.5, 2° and completely opened ( 5°), respectively. An automatic variable scatter slit was used to reduce the background. The data were collected with a fixed step A20 = 0.01°, and the sample was continuously spun during the data collection.

---