Contrast mechanisms for neutron radiography

The use of thermal neutrons in contact radiography and tomography [Schlenke r and Baruchel, Physica B 137, 309 (1986)] provides a powerful nondestructi ve analysis technique for materials that are difficult to study with x rays [Kirz , Quart. Rev. Biophys. 28, 33 (1995)]. Since x rays are strongly abs orbed by the heavier elements and neutrons are preferentially scattered by light elements, neutron radiography is well suited to the visualization of light elements in the interior of metallic objects. In this letter, we demo nstrate neutron radiography using a number of different contrast mechanisms . We find we are able to obtain radiographs showing features hitherto unobs ervable. (C) 2001 American Institute of Physics.