High-precision mass measurement of calcium-38 and development of the LEBIT 9.4-T Penning trap system.

摘要

The Low-Energy Beam and Ion Trap facility; LEBIT, has been designed to facilitate a variety of experiments at low energies with rare isotopes produced by fast-beam fragmentation. Gas stopping of the fast-fragment beams and modern ion manipulation techniques are used. The first experiments to be performed are high-precision mass measurements made possible with a 9.4 T Penning trap mass spectrometer. LEBIT has been commissioned and first experiments on stable and unstable nuclides have been performed. Here I present the results of a mass measurement on the unstable 38Ca isotope, measured with a precision of better than deltam/m=l x 10-8. 38Ca was the first successful radioactive nuclide measured with LEBIT. It is of particular interest as it is a 0+ → 0 + emitter, which makes it a possible test candidate for the Conserved Vector Current (CVC) hypothesis [?].; Also presented are design and commissioning details of the 9.4 T Penning trap system and mass measurements of the stable krypton isotopes, 83,84Kr, leading to improved mass values. In the interest of pushing the current limits of Penning trap mass spectrometry two new methods will be introduced. The first is a new excitation scheme of the ion motion using an octupolar radiofrequency field. The second, using the Lorentz steerer, is a fast preparation of ions previous to their capture in the Penning trap. Both methods have the potential to reduce the necessary measurement time, thus making high-precision measurements of shorter-lived species possible.