N=Z

The study of nuclei along the N=Z line, where protons and neutrons occupy the same shell-model orbital, is of particular interest for nuclear structure as well as for astrophysics studies. Our group is mainly active in beta-decay studies of the region towards ¹⁰⁰Sn and around nickel.

The determination of half-life values is crucial for the understanding of the rapid proton capture process. An advantage of beta-decay studies is that it gives a direct measure of the difference between the initial and the final state wavefunctions and as such, it provides an important test of structure calculations for that nucleus. A disadvantage, however, is that it can only cover information on the states within the Q_EC window.

The laser ion source at the LISOL mass separator in combination with intense heavy ion beams of CRC offers unique possibilities to produce low-energy isobaric and isotopically pure radioactive ion beams of ⁵⁴Ni, ⁵⁰Fe and ⁴⁶Cr and from Tc up to Pd close to N=Z. By comparing Gamow-Teller cross sections from (³He,t) reactions with Gamow-Teller strengths from beta-decay to states in ⁵⁴Co, ⁵⁰Mn and ⁴⁶V, respectively, isospin symmetry can be tested for the pf-shell nuclei. The close proximity of ¹⁰⁰Sn near the Tc up to Pd nuclei makes large-scale shell model calculations possible allowing a more complete comparison of not only level schemes but also of electromagnetic transition rates and Gamow-Teller strengths. The most neutron-deficient isotopes are even expected to undergo beta-delayed proton emission.