Radiation-Protection Slide Rule

This slide-rule model performs standard calculations in radiation protection. Special scales help find radiation quantities for different radioactive isotopes. For instance, the dosage through a substance is calculable from its volume, the distance to it, and the time. This instrument also allows one to calculate the drop in radioactivity over time on the basis of the different halflife values for each isotope, or the effect of a shielding as a function of the material, its thickness, and the radiation energy. This slide rule was developed thanks to the state of the art in the technology at the beginning of the atomic age. A slide rule was an everyday object in science and engineering until the 1970s, when it was largely replaced by the electronic calculator. It permits multiplication and division of numbers, and calculations of squares and cube roots and, depending on the version, the computation of trigonometric or exponential functions. It operates on the logarithmic principle, by substituting complex multistep arithmetic operations by an addition. For instance, multiplication is achieved by aligning two series of numbers on the slide rule. The total length of these rows yields the result. Its dimensions similar to a normal ruler allowed it to be carried about in a jacket pocket, like nowadays a smart phone. Portraits of individuals with slide rules from KIT’s predecessor institutions reveal that this tool was seen as a positive symbol of their work and was often chosen to reflect their self-image. kn