IONS AND ATOMS IN SUPERFLUID-HELIUM (HE-4) .3. MOBILITY MEASUREMENT OF ALKALI-EARTH IONS

An improved ion source based on laser ablation was developed which all ows to implant a great variety of impurity ions into liquid helium (He -4). This ion source can be operated in the gas phase as well as insid e the liquid helium opening up the opportunity to use pressurized liqu id helium for the mobility studies also. Low field mobilities have bee n remeasured for He+, Ca+, Sr+ and Ba+ ions and measured for the so fa r unknown case of Mg+. The data for the ions investigated previously a gree well with former measurements at similar temperatures. The mobili ty data for the Mg+ ion fit well into the trend extrapolated from the other ions.