Change of the

For the electron capture of 7Be in the metallic environments Pd and In the 7Be half-life was observed to increase by 0.9±0.2 and 0.7±0.2%, respectively, while in the insulator Li2O it was unchanged within experimental error (all samples cooled to T = 12K). The observations are consistent with the predictions of the Debye plasma model applied to the quasi-free electrons in the metals