0000000000444786
AUTHOR
A. Iivonen
The squeezer ion guide
Abstract The properties of an ordinary ion guide can be improved by inserting a grid between the nozzle and the skimmer. When positive ions are transported, an electric potential lower than +10 V is connected to the grid and one of the order of − 10 V to the skimmer. Efficient focusing is achieved between the nozzle and the grid by a combined action of the viscous helium flow field and the weak electric field. The focusing device is called a “squeezer”. It can be extended by adding more grids, a second skimmer, and differential pumping. Contrary to the first grid, the additional elements act more or less like electrostatic lenses in medium vacuum. With the squeezer ion guide, ions created i…
Focusing ions by viscous drag and weak electric fields in an ion guide
Abstract A new special ion guide has one or more grids at low electric potential in the space between nozzle and skimmer. Viscous drag caused by helium flow is used together with weak electric fields for focusing ions through the skimmer. A typical yield through the skimmer is 75% of that through the nozzle. The focusing device is called a “squeezer”. Most properties of the “squeezer ion guide” are similar to those of an ordinary ion guide. Because the kinetic energies are only of the order of 10 eV, however, problems caused by ion scattering are greatly reduced as compared to ordinary ion guides.
Collinear fast atomic-beam laser spectroscopy at riken garis/igisol
We have constructed a fast atomic-beam collinear laser spectroscopy system connected to the on-line isotope separator facility GARIS/IGISOL at RIKEN. This system is potentially powerful in studying refractory elements. To test the system, an off-line collinear experiment was made on stable Hf isotopes produced by means of laser ablation technique. For production of radioactive Hf isotopes, the use of the inverse kinematics of a fusion reaction,9Be(166Er,xn)175-xHf, was investigated. The radioactive isotope169Hf was successfully extracted from GARIS/IGISOL and accelerated up to 30 keV.
Velocity distribution of ion beams from the RIKEN IGISOL
Abstract A direct measurement of the velocity distribution of ion beams from an ion-guide isotope separator on-line (IGISOL) was carried out at RIKEN with a technique of laser spectroscopy. The skimmer-potential and gas-cell pressure dependence of the velocity distribution were also measured. The velocity distribution was found to be about two times narrower than that estimated from the mass resolving power (MRP). It is pointed out that the velocity spread deduced from MRP is considerably overestimated at various conditions. The way of improvement to make the velocity distribution of the ion beam from the IGISOL narrower and the feasibility of fast atomic-beam collinear laser spectroscopy a…