The SHIPTRAP experiment at GSI

The ion trap facility SHIPTRAP at GSI has been set up to enable precison experiments on very heavy ions produced at the SHIP velocity filter well known for the search and discovery of super heavy elements. At SHIPTRAP mass measurements, laser spectroscopy, ion chemical reactions and in the future in-trap decay experiments on heavy ions will be performed. SHIPTRAP can also deliver cold and clean samples of transuranium nuclides to other experimental users. For that purpose SHIPTRAP has the following sections: A stopping cell, a RFQ buncher and a double Penning trap system. The radioactive reactions products delivered by SHIP at a few 100keV/u are stopped and thermalized in a cell containing a highly pure helium buffer gas at a pressure of around 100 mbar. The stopped ions are extracted from the cell by the gas flow combined with electrical fields. In the next section - a RFQ structure (linear Paul trap) operated in bunched mode - they are cooled, accumulated, and bunched.

For purification, the ions are transferred into a Penning trap with a mass resolving power of about 100 000. By applying the mass selective buffer gas cooling technique isobaric purification is possible. A purified sample of ions is injected into the second Penning trap where precision mass measurements are performed. The mass of an ion is determined via its cyclotron frequency. The frequency is measured by the time of flight ion cyclotron resonance (TOF-ICR) method. An alternative and non destructive detection by the Fourier transform ion cyclotron resonance (FT-ICR) technique is being prepared.

A cold trapped ion cloud can be transformed into a low-emittance pulsed beam of tens of keV and be delivered to other experiments. The possibility to prepare low energy SHEs seperated from contaminants opens a wide spectrum of applications besides mass measurements such as nuclear spectroscopy, the study of chemical reactions and laser spectroscopy.

SHIPTRAP is supported by the European Union in the framework of the network NIPNET.