Systems precise collimation

Precise collimation systems are needed to make measurements close to the primary beam. In addition, scattering at small angles is usually very weak. Both... 

Precise collimation systems are needed to make measurements close to the primary beam. In addition, scattering at small angles is usually very weak. Both pinhole and line collimation has been used block collimation systems require mathematically transforming the data from line collimation to point collimation. During the last 15 years, the development of synchrotron sources and better area detectors has led to a proliferation of scattering experiments that occur in real time. 

The basic requirement is a diffusion-pumped chamber attached to an ion gun. The ion gun is filled with high-purity inert gas such as Ar. This gas is accelerated between two electrodes with a high potential difference. This ionizes the gas and a beam of focused and collimated gas particles is aimed at the specimen surface. Modern electronics allows very precise manipulation of the ion beam in several ways. Most ion milling machines are singlebeam systems where one surface of the specimen is thinned. Alternatively, double-sided machines are also available where there are two ion beams focused on either side of the same specimen that is milled from both the top and bottom surfaces. 

This strategy was also exploited for the determination of alcoholic strength in beverages [103]. As the proposed flow injection system included an LED-based detector, the Schlieren signal was increased due to the poor collimation of the incident radiation beam. About 120 samples were run per hour, and precise results (r.s.d. = 3.4%) were obtained. 

The Rotation Modulation Collimator was originally conceived by Mertz [9] as a technique to encode an image formed in the focal plane of an optical Schmidt-telescope to allow electronic read-out by a photomultiplier. The technique was soon adapted to image forming in X-ray astronomy by Schnopper et al. [11], and was successfully used in a number of rocket flights to localize X-ray sources with good precision [12,14]. In 1974 the UK ARIEL-V and in 1975 the NASA SAS-3 satellite was launched both equipped with RMC systems. The source localizations provided by ARIEL-V and SAS-3 led to the discovery of many new X-ray sources and the identification of the optical counterparts of several sources [13,15,16]. 

The silver-embedded PLA films were studied by SAXS measurements using a Bruker Nanostar instrument having a microfocus X-ray source with copper (Cu) radiation and operation power 30 W and using a vAnTEC-2000 two-dimensional X-ray detector with a 140 mm x 140 mm detector window. Precise sample positioning in the X-ray beam is achieved by determining the sample transmission as a function of position (nanography). The sample is scanned perpendicular to the beam, and the transmission is determined at each x,y position and displayed as a color-coded map the user can then select a proper position(s) for the data collection. The system also contains spot focus optics for sealed tube, three-pinhole collimation for the best signal-to-noise ratio. The sample-to-detector distance is 1,070 mm. 

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