Recovery of spectral resolution for each annealing cycle. The abscissa shows the level of degradation at the onset of the annealing operation, while the ordinate shows the resolution as achieved immediately after the annealing, each for one of the better and one of the poorer resolution detectors (0, 4). Filled symbols are data points using the FWHM of the 1107 keV line before and after each annealing; open symbols are the same data, corrected by eliminating a long-term trend. The size of symbols represents the duration of annealings (see text).