Determination of $\ensuremath{\beta}$-decay feeding patterns of $^{88}\mathrm{Rb}$ and $^{88}\mathrm{Kr}$ using the Modular Total Absorption Spectrometer at ORNL HRIBF

Determination of $β$ -decay feeding patterns of ${}^{88}{Rb}$ and ${}^{88}{Kr}$ using the Modular Total Absorption Spectrometer at ORNL HRIBF

P. Shuai et al.

Phys. Rev. C 105, 054312 – Published 18 May 2022

Abstract

Precise determination of ground-state feeding in the $β$ decay of fission products is an important but challenging component in modeling reactor antineutrino flux and reactor decay heat. The Modular Total Absorption Spectrometer (MTAS) is a versatile NaI(Tl) detector array that determines the true $β$ -decay pattern free from the pandemonium effect, including precise ground-state feeding intensities. In this paper, we report MTAS results of the $β$ feeding intensities of ${}^{88}{Rb}$ and ${}^{88}{Kr}$ , fission products with large cumulative yields in nuclear reactors. By comparing MTAS results with previous measurements, ${}^{88}{Rb}$ provides a validation of MTAS's ability to determine ground-state feedings in $β$ decays, while the precision of ${}^{88}{Kr}$ ground-state feeding is improved when compared with the Evaluated Nuclear Structure Data File (ENSDF). The investigation of sources that contribute to $β$ feeding branching uncertainties in MTAS experiments is discussed in detail. Lastly, the deconvolution of ${}^{88}{Rb}$ decay spectra suggests that MTAS can distinguish an allowed $β$ spectral shape from a first forbidden unique $β$ spectral shape.