$\text{Direct}~Q\text{-Value Determination of the}~β^-~\text{Decay of} ~^{187}\text{Re}$

Abstract

The cyclotron frequency ratio of ${}^{187}{\mathrm{Os}}^{29+}$ to ${}^{187}{\mathrm{Re}}^{29+}$ ions was measured with the Penning-trap mass spectrometer PENTATRAP. The achieved result of $R=1.000000013882(5)$ is to date the most precise such measurement performed on ions. Furthermore, the total binding-energy difference of the 29 missing electrons in Re and Os was calculated by relativistic multiconfiguration methods, yielding the value of $\hat{I}”E=53.5(10)$ eV. Finally, using the achieved results, the mass difference between neutral ${}^{187}$Re and ${}^{187}$Os, i.e., the $Q$ value of the $β^-$ decay of ${}^{187}$Re, is determined to be 2470.9(13) eV.

6 pages, 4 figures, 1 table