A Large Area Tritium Standard Source for Traceable Calibration of Surface Contamination Monitors

A tritium calibration source is described in which there is no self absorption, therefore, the Beta Emission spectrum is not distorted other than by backscatter. The source consists of an aluminium substrate on which is laid a chemical layer one molecule thick with all molecules orientated the same way by employing the Langmuir-Blodgett technique. Theoretical and practical emission spectra for tritium absorption in air and in material of unit density are illustrated. The spectra provide the foundation for reproducible measurements of surface contamination as required for international accredibility and regulatory purposes. A complimentary paper by the same author is “Tritium Surface Contamination Measurements with International Credibility”.