Precision cameras types

The simplest X-ray detector, and for years the workhorse of detectors, is X-ray-sensitive film, but film has been almost completely replaced by image plates and CCD detectors, which are described in more detail later. Various types of cameras (next section) can direct reflections to detectors in useful arrangements, allowing precise determination of indices and intensities for thousands of reflections from a single image. 

After the line positions are measured, their 0 values are calculated from the appropriate equation for the camera involved. But if no great precision is needed, both of these steps can be avoided in routine work by making a cardboard scale marked with 6 values this scale is placed next to the film and the 9 value of each line read off. A separate scale will be needed for each size and type of camera. 

CCN number concentration is measured using a CCN counter (CCNC). Several types of CCNCs have been developed (McMurry, 2000 Nenes et al., 2001 Roberts and Nenes, 2005). In most CCNCs, supersaturated conditions are produced by creating a temperature difference on wetted walls. CCN-active particles grow to large droplets in the artificial supersaturated environment. The number of droplets is then counted using an optical particle counter (OPC) (e.g., Stratmann et al., 2004 Roberts and Nenes, 2005) or a charge coupled device (CCD) camera (Otto et al., 2002). The most important parameter in CCN measurement is the precise value of the supersaturation (S) inside the instrument, which ensures compatibility with other studies (Seinfeld and Pan-dis, 2006). 

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