| Abstract: | A 16.5 liter spherical ion chamber was constructed of conducting muscle-equivalent plastic and filled to 760 mm-Hg with a muscle-equivalent gas. The use of the chamber for measurements of natural environmental backgrounds was made quite feasible with the aid of the recently developed Shonka vibrating quartz fiber electrometer. This instrument is routinely operable at the extremely high sensitivity of better than 5000 divisions per volt. This system, therefore, has made possible reproducible measurements of absorbed dose-rates of fractions of a micro-rad per hour without any need for the usual corrections for wall-effect, stopping power, and so forth. |
