This interrupted experiment demonstrates a lack of `dark progression' of SeMet breakdown. Individual measurements of the peak `white line' absorbance cross section are plotted against the time elapsed since the beginning of the experiment. The depicted run was interrupted after 5 h and the sample was returned to liquid nitrogen. After a 5 h delay, the sample was mounted, re-centered, and the rest of the decay curve was measured. There is no apparent change in the height of the white line across the 5 h during which the experiment was interrupted. When these data are plotted against the absorbed dose instead of time, they follow an exponential decay (Fig. 2).