Abstract
The 0.96 MeV gamma-radiation following the decay of 63Zn is selectively scattered by copper. The intensity of elastic scattering from copper at 90° is several times greater than from iron, provided that the 63Zn source is in solution; with a solid source, only slight evidence of resonant scattering has been found.
These results are interpreted as resonant nuclear scattering by 63Cu, and are analysed in terms of the displacement and broadening of the emission line by nuclear recoil, which persists longer in the liquid than in the solid.
The mean life of the 0.96 MeV excited state of 63Cu is estimated to be of the order of 6 × 10−13 second.
From the absence of any observable selective scattering by iron of the gamma-rays following the decay of 56Mn, the mean life of the 0.84 MeV excited state of 56Fe is estimated to exceed 8 × 10−12 second.