Kollineare Laserspektroskopie an Calcium und Zinn an TRIGA-LASER und ISOLDE

From the optical spectra of the ions and atoms we can extract the spin, the change in mean square charge radius, the magnetic dipole moments, and the electric quadrupole moments. To investigate these properties, collinear laser spectroscopy is a particular appropriate method because it is universally applicable, very efficient and allows to investigate short-lived particles with lifetimes in the range of milliseconds and production rates of a few hundred particles per second. Within the scope of this work, a control system (TRITON) was developed for the collinear laser spectroscopy experiment LASPEC at FAIR, which allows distributed access to the various control elements and is therefore very flexible. It was developed and tested on the LASPEC prototype, the TRIGA-LASER experiment at the research reactor TRIGA Mainz. Using TRITON, the isotope shifts of the stable calcium isotopes 40,42,44,48Ca have been measured in the 4$s$$_{1/2}$ → 4$p$$_{3/2}$ transition with an accuracy, which exceeded the previous literature values by about one order of magnitude. These data were the basis for the precise determination of the nuclear charge radii of the calcium isotopes $^{49−52}$Ca from collinear laser spectroscopy installation COLLAPS at ISOLDE/CERN. Furthermore, developments for spectroscopy on $^{53,54}$Ca at COLLAPS have been carried out, where TRITON was also used. The production rates for $^{54}$Ca are about one ion per second and optical detection is no longer possible. Instead, the technique of optical pumping with state selective charge exchange and β-detection of single ions was implemented at COLLAPS and successfully demonstrated at $^{52}$Ca. With these applications, the performance and operational readiness of the LASPEC control system for FAIR was successfully demonstrated. In the second part of the work, spectroscopy on the tin isotopes $^{109,112−134}$Sn has been performed at the COLLAPS experiment. Several electromagnetic moments close to the $N$ = 82 shell closure have been determined with a tenfold higher accuracy than within earlier experiments. In addition, with the investigation of the isotopes $^{133,134}$Sn, the evolution of the nuclear charge radii could be established beyond the shell closure for the first time. A number of well-known isomers have also been measured, namely the isomers with odd neutron number $^{113m,117m−131m}$-Sn, and the $I$ = 7 isomers $^{128m}$-Sn and $^{130m}$-Sn. From the measured isotope shifts and the hyperfine structure, the nuclear charge radii, magnetic dipole moments, electric quadrupole moments, and isomer shifts were determined. Below the N = 82 shell closure, the charge radii are similar to those of the element cadmium and can be described very well with the model of Zamick and Talmi. The "kink" at the shell closure is more pronounced than on the tellurium (Z = 52) and therefore much stronger than expected by theoretical models. The evolution of the electric quadrupole moments of the isotopes with valence neutrons in the $h$$_{11/2}$ shell is similar to that of cadmium. Both show a linear trend along a much longer chain than expected for the $h$$_{11/2}$ shell. Similar curves are also obtained for the differences in the charge radii between the 11/2 intruder states and the states of ordinary parity. The preliminary results presented here are to be further underlined in future beam times at COLLAPS on a different transition.