Accurate mass measurements of very short-lived nuclei

Abstract

Mass measurements of 34Ar, 73–78Kr, and 74,76Rb 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 34Ar mass has been measured with a relative accuracy of 1.1 · 10−8. The Q ec -value of the 34Ar 0+ → 0+ decay can now be determined with an uncertainty of about 0.01%. Furthermore, 74Rb is the shortest-lived nuclide ever investigated in a Penning trap.