Double-$\beta$-decay $Q$ values of ${}^{130}\mathrm{Te}$, ${}^{128}\mathrm{Te}$, and ${}^{120}\mathrm{Te}$

The double-$\beta$-decay $Q$ values of ${}^{130}\mathrm{Te}$, ${}^{128}\mathrm{Te}$, and ${}^{120}\mathrm{Te}$ have been determined from parent-daughter mass differences measured with the Canadian Penning Trap mass spectrometer. The ${}^{132}\mathrm{Xe}\text{−}{}^{129}\mathrm{Xe}$ mass difference, which is precisely known, was also determined to confirm the accuracy of these results. The ${}^{130}\mathrm{Te}$ $Q$ value was found to be $2527.01\pm 0.32$ keV, which is 3.3 keV lower than the 2003 Atomic Mass Evaluation recommended value and is consistent with another recent Penning trap measurement. The ${}^{128}\mathrm{Te}$ and ${}^{120}\mathrm{Te}$ $Q$ values were found to be $865.87\pm 1.31$ and $1714.81\pm 1.25$ keV, respectively. For ${}^{120}\mathrm{Te}$, this reduction in uncertainty of nearly a factor of 8 opens up the possibility of using this isotope for sensitive searches for neutrinoless double-electron capture and electron capture with ${\beta }^{+}$ emission.

Figure 1

Time-of-flight spectra of events with $\le 5$ detected ions for (a) ${}^{130}\mathrm{Te}{}^{1+}$ and (b) ${}^{130}\mathrm{Xe}{}^{1+}$ ions using two-pulse Ramsey excitations over a total time of 3000 ms. The TOF offset was not measured and has no impact on the frequency determination. The curves are the fits to the data.

Figure 2

$Q$ values for (a) ${}^{130}\mathrm{Te}$, (b) ${}^{128}\mathrm{Te}$, and (c) ${}^{120}\mathrm{Te}$ determined from recent measurements and evaluations. The values shown are from the Manitoba II deflection-type mass spectrometer (Manitoba II measured) [12], the Manitoba II result supplemented with auxiliary mass data (Manitoba II w/auxiliary) [12], the 2003 Atomic Mass Evaluation (AME2003) [11], the Florida State University Penning Trap (FSU) [15], and the Canadian Penning Trap (this work). Note the different scale in the inset displaying the FSU result.