QEC -value determination for Na21→Ne21 and

Jonas Karthein

¹

,

D. Atanasov

²

,

Klaus Blaum

³

et al.

Abstract

We report on high-precision QEC values of the 21 Na→ 21 Ne and 23 Mg→ 23 Na mirror β-transitions from mass measurements with ISOLTRAP at ISOLDE/CERN. A precision of δm/m = 9 · 10 −10 and δm/m = 1.5 · 10 −9 was reached for the masses of 21 Na and 23 Mg, respectively. We reduce the uncertainty of the QEC values by a factor five, making them the most precise experimental input data for the calculation of the corrected Ft-value of these mixed Fermi/Gamow-Teller transitions. For the 21 Na→ 21 Ne QEC value, a 2.3σ deviation from the literature QEC-value was found.

Comprehensive analysis of beta decays within and beyond the Standard Model

“…• The results from ref. [14] have motivated several measurements of branching ratios, lifetimes and Q-values for the extraction of F t values [44][45][46]. The review of spectroscopic data is not within the scope of the present analysis.…”

“…• For completeness, for all these β + transitions, we update the maximal total energies ∆ = Q EC − m e , using the transition energies Q EC given in the 2016 Atomic Mass Evaluation (AME) Database [47], except for 21 Na for which we use a newer measurement [46]. B = −0.755( 24) [42] Table 1.…”

“…(2.6), using the endpoint energy listed in the table. The latter are taken from AME2016 [47], except that of 21 Na [46]. The values of f A /f V come from refs.…”

Analysis methods and code for very high-precision mass measurements of unstable isotopes

“…The frequency scale differs between the two species to allow for a better display of both data sets. The displayed data is a subset of the data published in [Ka19a]. For details, see text.…”

Mass-Difference Measurements on Heavy Nuclides with an eV/c2 Accuracy in the PENTATRAP Spectrometer

“…The data analysis scheme of choice is called the "polynomial" method, which has already been successfully employed in several experiments [20][21][22]. It is based on the reasonable assumption that the magnetic field drift and, hence, the free cyclotron frequency changes in time can be approximated by a polynomial of low order.…”