Nuclear Instruments and Methods in Physics Research A 531 (2004) 228–237 Neutron imaging—detector options and practical results Eberhard H. Lehmann*, P. Vontobel, G. Frei, C. Br . onnimann Paul Scherrer Institut, Villigen 5232, Switzerland Available online 23 June 2004 Abstract For many years, the major detection system for neutron radiography consisted in an X-ray film, where the conversion from neutrons to detectable radiation was made with a metallic layer of Gd, Dy or In. With this method, high spatial resolution was achieved, only limited by the beam properties of the radiography facilities. This situation has changed when digital detection systems became available, enabling much higher sensitivities, larger dynamic ranges and the opportunity to use the digital image information for more quantitative evaluations. The article describes the performance of neutron imaging systems and gives an overview of existing and potential application of radiography and tomography with neutrons. r 2004 Elsevier B.V. All rights reserved. PACS: 25.85.Ge; 29.25.Dz; 87.59.Fm; 89.20.+a Keywords: Neutron imaging; Tomography; Hydrogen detection; Detector development; Detector performance; Quantification 1. Introduction Neutrons from strong sources, mainly fission reactors, have been used for many kinds of material investigations by transmission analysis [1]. Neutron radiography has been established as a tool in non-destructive testing (NDT) alternatively and complementary to roentgenography and other methods. There are many advantages of thermal neutrons compared to X-rays, e.g. in the sensitive detection of hydrogen and the penetration of thick objects made of heavy elements (lead, uranium, bismuth,y). For many years, the commonly used tool in neutron radiography was the film method, were a converter of a neutron absorbing material was used to produce the latent image on the silver halide film. Although a good spatial resolution has been obtained with this established technique, there are many drawbacks demanding for new detection systems with more flexible performances, espe- cially with respect to time resolution, dynamic range and quantitative information from the images. There are new approaches available and under development to overcome the limitations of the film method. It depends very much on the individual request of scientists and customers, which detection system fits best for the solution ARTICLE IN PRESS *Corresponding author. Tel.: +41-56-310-2963; fax: +41- 56-310-3131. E-mail address: eberhard.lehmann@psi.ch (E.H. Lehmann). 0168-9002/$-see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.nima.2004.06.010