Smooth trends in fermium charge radii and the impact of shell effects.

The quantum-mechanical nuclear-shell structure determines the stability and limits of the existence of the heaviest nuclides with large proton numbers Z ≳ 100 (refs. ). Shell effects also affect the sizes and shapes of atomic nuclei, as shown by laser spectroscopy studies in lighter nuclides.

Ion implantation of Ra for a primary Rn emanation standard.

Laser resonance ionization at the RISIKO 30 kV mass separator has been used to produce isotopically and isobarically pure and well quantified Rn emanation standards. Based upon laser-spectroscopic preparation studies, ion implantation into aluminum and tungsten targets has been carried out, providing overall implantation efficiencies of 40% up to 60%. The absolute implanted activity of Ra was determined by the technique of defined solid-angle α-particle spectrometry, where excellent energy resolution was observed.

Detection of the Lowest-Lying Odd-Parity Atomic Levels in Actinium.

Two lowest-energy odd-parity atomic levels of actinium, 7s^{2}7p^{2}P_{1/2}^{o}, 7s^{2}7p^{2}P_{3/2}^{o}, were observed via two-step resonant laser-ionization spectroscopy and their respective energies were measured to be 7477.36(4) and 12 276.59(2)  cm^{-1}.

Optimization of a laser ion source for Ho isotope separation.

To measure the mass of the electron neutrino, the "Electron Capture in Holmium-163" (ECHo) collaboration aims at calorimetrically measuring the spectrum following electron capture in Ho. The success of the ECHo experiment depends critically on the radiochemical purity of the Ho sample, which is ion-implanted into the calorimeters. For this, a 30 kV high transmission magnetic mass separator equipped with a resonance ionization laser ion source is used.