Can Hyperfine Excitation explain the Observed Oscillation-Puzzle of Nuclear Orbital Electron Capture of Hydrogen-like Ions?

TL;DR

This paper investigates whether hyperfine state transitions in hydrogen-like ions can explain the observed oscillations in orbital electron capture decays, concluding that such transitions cannot account for the experimental decay pattern.

Contribution

The study provides a detailed analysis showing that periodic hyperfine state transitions do not explain the observed decay oscillations in specific hydrogen-like ions.

Findings

Hyperfine transitions are insufficient to explain decay oscillations.

Allowed EC decay occurs only from the hyperfine ground state.

Periodic transitions to excited hyperfine states cannot account for the observed effects.

Abstract

Modulated in time orbital electron capture (EC) decays have been observed recently in stored H-like $^{140}$Pr$^{58+}$ and $^{142}$Pm$^{60+}$ ions. Although, the experimental results are extensively discussed in literature, a firm interpretation has still to be established. Periodic transitions between the hyperfine states could possible lead to the observed effect. Both selected nuclides decay to stable daughter nuclei via allowed Gamow-Teller transitions. Due to the conservation of total angular momentum, the allowed EC decay can only proceed from the hyperfine ground state of parent ions. In this work we argue that periodic transitions to the excited hyperfine state (sterile) in respect to the allowed EC decay ground state cannot explain the observed decay pattern.