Results of the Comparison Measurements (IMAGE) Physikalisch-Technische Bundesanstalt (PTB) Caption Results of the beta comparison measurements that have been carried out up to now. The lower and upper red-dotted limits and the red data points are valid for the very low-energetic radiation of promethium 147. Credit PTB Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.