Determination of β -decay ground state feeding of nuclei of importance for reactor applications

Abstract

In β-decay studies the determination of the decay probability to the ground state (g.s.) of the daughter nucleus often suffers from large systematic errors. The difficulty of the measurement is related to the absence of associated delayed γ -ray emission. In this work we revisit the 4πγ − β method proposed by Greenwood and collaborators in the 1990s, which has the potential to overcome some of the experimental difficulties. Our interest is driven by the need to determine accurately the β-intensity distributions of fission products that contribute significantly to the reactor decay heat and to the antineutrinos emitted by reactors. A number of such decays have large g.s. branches. The method is relevant for nuclear structure studies as well. Pertinent formulas are revised and extended to the special case of β-delayed neutron emitters, and the robustness of the method is demonstrated with synthetic data. We apply it to a number of measured decays that serve as test cases and discuss the features of the method. Finally, we obtain g.s. feeding intensities with reduced uncertainty for four relevant decays that will allow future improvements in antineutrino spectrum and decay heat calculations using the summation method.

Total absorption γ -ray spectroscopy of the β decays of Y96gs,m

“…Finally, we have also applied the 4πγ − β counting method introduced by Greenwood et al [69] and recently revisited in Ref. [70]. It is based on the number of counts registered in the DTAS β-gated spectrum together with the number of counts registered in the β detector.…”

The DESPEC setup for GSI and FAIR

“…The full assembly was commissioned using low energy radioactive beams from the IGISOL IV facility at the Cyclotron Laboratory of the University of Jyväskylä [19,42], and took data published in [41,[43][44][45][46]. A summary of the results obtained in the IGISOL IV campaign can be found in [47].…”