<title>Review of low x-ray fluence detection developments on flash radiography</title>

Abstract

Dealing with dynamic behavior of solids, flows, detonator initiation, high explosives properties, shock waves and other fast processes, implies a large amount of metrology problems. When studies on shock waves began, forty five years ago, only flash X-ray radiography achieving chronometric measurements was developed, in order to investigate shaped charges jets. This technique has also been widely used in detonics because it does not affect hydrodymanic phenomena. Since that time, a large amount of data has been gathered and has allowed physicists to confirm many theories. Later pulsed high energy radiographic machines emitting X-rays have allowed large images record of voluminous objects containing dense materials (with high atomic numbers) and therefore very absorbing. Our laboratory has been working in this field for more than 30 years. A great deal of effort has been spent to enhance the radiographic capabilities of our X-ray machines. High dose levels and better spot size diameter of X-ray sources have allowed quite good records for a better understanding on material densities and boundaries. During the same period of time many works were led on the detection of low X-ray fluences. We present in this communication the main studies developed in that field on cells of light screens coupled with visible film and on microchannel plates image intensifiers.