Improvement on sensitivity for the track- etch neutron radiography

One of the main restrictions to the employment of the track-etch neutron radiography technique, is the low-intrinsic optical contrast achieved in the recorded image that leads to a poor sensitivity to discern thickness changes of the materials. The sensitivity is determined by measuring the light transmitted through the images and for such purpose, conventional analog optical microphotometers are typically employed. In the present work a digital system has been employed to measure the light transmitted and a significant improvement in the sensitivity was achieved. The use of solid state nuclear track detectors(SSNTD) to record neutron radiography(NR) images is a well known technique. The radiography is obtained by irradiating a sample in an uniform neutron beam and a converter screen transforms the transmitted neutron intensity into ionizing radiation which is able to cause damages into the detector. Usually boron based converter screens are used, and in which case, alpha particles and lithium ions cause the damages. By means of a chemical etching the latent damages are enlarged and are called tracks and, they form a two-dimensional image which is visible by the naked eye. The insensitivity of the SSNTD to visible light, beta and gamma radiations, the high resolution achieved in the image, the feasibility of stopping the development at intermediate stages are some of their attractive characteristics for radiograph