Accurate mass measurements of very short-lived nuclei Prerequisites for high-accuracy investigations of superallowed β-decays

摘要

Mass measurements of ~(34)Ar, ~(73-78)Kr, and ~(74,76)Rb were performed with the Penning-trap mass spectrometer ISOLTRAP. Very accurate Q_(EC)-values are needed for the investigations of the Ft-value of 0~+→0~+ nuclear β-decays used to test the standard model predictions for weak interactions. The necessary accuracy on the Q_(EC)-value requires the mass of mother and daughter nuclei to be measured with δm/m≤3·10~(-8). For most of the measured nuclides presented here this has been reached. The ~(34)Ar mass has been measured with a relative accuracy of 1.1·10~(-8). The Q_(EC)-value of the ~(34)Ar 0~+→0~+ decay can now be determined with an uncertainty of about 0.01%. Furthermore, ~(74)Rb is the shortest-lived nuclide ever investigated in a Penning trap.