The blackening of photographic plates by positive ions of the alkali metals

A short review is included of previous work on the blackening of photographic plates by positive rays and rays of an analogous nature.The blackening of Eastman x-ray plates, by positive ions, has been measured as a function of the energy of the ions of Li, Na, K, Rb, and Cs. The energy of the ions required to produce a photographic density of D = 0.3 with a one minute exposure at a current density of 1.32 × 10^?8 amperes per cm.² ranged from 1420 electron-volts in the case of cæsium to 860 electron-volts in the case of Li⁷. Approximately 10⁵ ions are required at these energies to render developable one silver-halide grain. For a threshold density, D = 0.04, under the same conditions the energy ranged from approximately 920 to 460 electron-volts for Cs and Li⁷ respectively.Sensitivity comparisons were made between x-ray plates and process and schumannized process plates. Potassium ions with an energy as low as 137 electron-volts were recorded on Schumann plates, and it is possible that positive ions of one-third this energy can be recorded.     

The role of technology in intelligence practice: linking the developer and the user perspectives

Technology has penetrated the social fabric of security practices so deeply that it is often used without much reflection on its role, significance and implications. This naturalisation of technology makes it difficult for practitioners to develop their own vision of technology. They may become subject to the coercive power of technology, and appropriate the narrow technological paradigm embodied in their tools. This, in turn, makes it difficult for technology developers to understand practitioner needs and to assess the transformative potential of technology. This paper aims to develop a conceptual framework for understanding the role of technology in intelligence. The focus is on the technological capabilities supporting an analysis of sociocultural processes related to so‐called ‘new threats’. The two main problems in intelligence nowadays are deciding what data are relevant and how they should be analysed. The major issue is not the collection of information, but turning information into knowledge and action. Accordingly, the practitioner thinking about technological tools can be usefully informed by the concept of technology as a mediator between areas of knowledge production and consumption. This concept highlights technology’s ability to affect intelligence analysts’ understanding of threats, identification of data sources and information gaps, and their interaction with colleagues and consumers of intelligence products.