Reference masses for precision mass spectrometry: design and implementation of a Pierce geometry to the cluster Ion source at ISOLTRAP

At the mass spectrometer ISOLTRAP carbon clusters ($^{12}$Cn, 1$\leqslant$n$\leqslant$25) are provided as reference masses, which are of particular importance in higher mass ranges (m $\geqslant$ 200u). In this mass range the measurlment uncertainty is increasingly dominated by the difference of the reference mass and the mass of the ion of interest. Using carbon clusters instead of the common $^{133}$Cs ions, this difference decreases. The carbon clusters are produced in a laser ion source which has been improved in the frame of this thesis. The fluctuations of the count rate have been investigated as a function of the laser energy. Furthermore, the energy density at the target has been increased by implementation of a telescope into the laser beam line, which leads to a more narrow energy distribution of the ions. Through the exact adjustment of timing and length of a pulsed cavity an energy range with constant count rate could be selected. In order to provide ideal starting conditions during and after the laser ablation, a new extraction has been designed. The parts were manufactured according to technical drawings which have been produced. Moreover, by performing a precision mass measurement during an on-line run, the uncertainty of $^{208}$Fr was decreased almost one order of magnitude to less than 7 keV.