Re-evaluation of the Beck et al. data to constrain the energy of the Th-229 isomer

TL;DR

This paper re-analyzes previous gamma spectroscopy data to better constrain the energy of the Th-229 isomer, considering new experimental results that have not yet observed the transition.

Contribution

It provides a comprehensive analysis of existing data to narrow down the possible energy range of the Th-229 isomer, integrating recent experimental constraints.

Findings

Refined the parameter space for the isomer energy and branching ratio.

Identified regions consistent with previous measurements and non-observations.

Updated constraints on the Th-229 isomer energy based on re-evaluation.

Abstract

The presently accepted value of the energy splitting of the Th-229 ground-state doublet has been obtained on the basis of undirect gamma spectroscopy measurements by Beck et al., Phys. Rev. Lett. 98, 142501 (2007). Since then, a number of experiments set out to measure the isomer energy directly, however none of them resulted in an observation of the transition. Here we perform an analysis to identify the parameter space of isomer energy and branching ratio that is consistent with the Beck et al. experiment.