A system for fast enutron radiography

摘要

A system has been designed and a neutron generator installed to perform fast neutron radiography. With this system, objects as small as a coin and as large as a 19 liter continer have been radiographed. The neutron source is an MF Physics A-711 netron generaor which produces 3x10~(10) neutrons/second with an average energy of 14.5 MeV. The readiography system uses x-ray scintillation sereens and film in commercially available light-tight cassettes. The cassettes have been modified to include a thin sheet of plastic to produce protons from the neutron beam through elastic scattering from hydrogen and other low Z materials in the plastic. For film densities from 1.8 to 3.0, exposures range from 1.9 x 10~7 n/cm~2 to 3.8 x 10~8 n/cm~3 depending on the type of screen and film. The optimum source-to-film distance was found to be 150 cm. At this distance, the geometric unsharpness was determined to be approximately 2.2-2.3 mm (or 8.7-9.1