Analysis of Multi-exponential Decay Curves

Abstract

The contributions of cascades to multi-exponential decay curves are analysed. We define the quantitative cascade contribution to an exponential decay as the replenishment ratio, which is the ratio of the cascade repopulation rate to the decay depopulation rate. We recommend that this ratio be quoted in future papers on beam-foil or other cascade-affected decay measurements. We also present specific relationships between the fitting parameters and the level populations for decay curves which arise from electric dipole transition schemes of up to second order in cascading. Velocity dispersion effects in beam-foil decays are, in general, shown to be negligible, except for decays from ejected foil-particles.