Inside the Vacuum Chamber
Inside NDP Vacuum Chamber at NIST
The mechanism inside the current NIST NDP chamber was constructed having benefited through learning in the use of two earlier designs. The earlier and simpler chambers were successfully applied in far less spacious locations, e.g., Beam Tube-3 at NIST. The existing NDP system, recently moved to the end station of cold neutron guide 1 at the NCNR has a chamber that is both spacious (61 cm diameter) and versatile. Samples, such as shown above - a 200 mm diameter silicon wafer patterned with memory structures, can be rotated about the center of the chamber and rastered vertically and horizontally. As a result every point on the sample's surface can be measured without breaking the vacuum. In addition, an array of samples can be positioned for analysis on either/or both the front and the back of a holder for analysis. Furthermore, one or many detectors can be placed in satellite positions around the sample at any radius from the sample and simultaneously analyze it at a variety of angles. And, if the sample is sufficiently thin, detectors can be diametrically aligned for use in coincidence NDP spectrometry - a very powerful method of analysis.
This chamber and most measurement techniques used with the system are described in detail by consulting one of the publications given on this website.