Tremsin, A.S.; Lehmann, E.H.; Kardjilov, N.; Strobl, M.; Manke, I.; McPhate, J.B.; Vallerga, J.V.; Siegmund, O.H.W.; Feller, W.B.: Refraction contrast imaging and edge effects in neutron radiography. Journal of Instrumentation 7 (2012), p. C02047/1-9
10.1088/1748-0221/7/02/C02047

Abstract:
This paper reports on the edge enhancement and refraction/scattering effects in neutron radiography measured at thermal and cold neutron beams with a high resolution (55 mm) microchannel plate neutron counting detector. These effects in some cases can enhance the contrast of certain features in the neutron radiographic images. At the same time, the edge effects introduce image distortions, as in case of tomographic reconstructions. The edge effects in radiographies of several steel and aluminum objects are shown for different beam divergences and sample orientations relative to the beam. It is also demonstrated how novel microcapillary neutron collimators can enable refraction and scattering contrast imaging in some cases, where the refraction and scattering angles are relatively large. These collimators can also be used to reduce some refraction artifacts, namely remove bright edges in the transmission images.