Understanding Neutron Radiography Reading VII-NRHB Part 2 of 2
Understanding Neutron Radiography Reading VII-NRHB Part 2 of 2
Understanding Neutron Radiography Reading VII-NRHB Part 2 of 2
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2.5.5.3 The data given below should therefore be used with the above<br />
reservation in mind as it does not represent an optimum set <strong>of</strong> conditions, but<br />
only a consensus <strong>of</strong> opinion.<br />
2.5.5.4 Vibration can be a problem when there are machines (e.g. cranes etc.)<br />
is use in nearby buildings. This should be verified by taking both short and<br />
long exposures <strong>of</strong> the object with a camera, using a slow speed photographic<br />
film, with the camera mounted on a base that is relatively unaffected by the<br />
vibrations.<br />
2.5.5.5 Geometry. The collimator ratio (L/D) should be 100 or higher, but it is<br />
considered that the advantages <strong>of</strong> increasing the ratio greater than 300 are<br />
diminishing.<br />
2.5.5.6 Converter foils for the transfer method are limited to indium<br />
dysprosium, and gold, all <strong>of</strong> which emit a particle <strong>of</strong> approximately 1 MeV, i.e.<br />
long range and not conducive to high resolution. However, the dysprosium<br />
foils are thinner and therefore have better resolution capability. A thickness <strong>of</strong><br />
0,025 mm (25μm) or less is recommended.<br />
Charlie Chong/ Fion Zhang
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