Recent Results of Beta-Decay-Energies of Very Neutron-Rich Nuclei Around Mass Number A = 100

Abstract

The determination of beta-decay energies is a very useful method to explore the nuclear mass surface outside the region of stability. Such experiments are simple in principle, but they are difficult to evaluate due to the high decay energies, the large number of beta-transitions and the great complexity of the decay schemes of nuclei far away from the valley of β-stability |1|. These decay schemes must be known in their main features in order to derive the correct Q_β-value from the measured β-endpoint energies. A reliable Q_β-value can only be deduced in such experiments, if as many β-spectra as possible are measured in coincidence with γ-transitions, which depopulate different known levels in the daughter nucleus. In this way, also the reliability of the decay scheme of the nucleus studied can be checked. In addition, the final experimental error of the Q_β-value is reduced to about 100 keV for Q_β ≧ 10 MeV; this gives a relative error of about 10^-6 for the nuclear masses (for A ≅ 100).

This work has been funded by the German Federal Minister of Research and Technology (BMFT) under the contract number o6 BS 452 I.