Berlin 2005 – scientific programme

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MS: Massenspektrometrie

MS 9: Pr
äzisions-MS kurzlebiger Nuklide 2

MS 9.2: Talk

Monday, March 7, 2005, 16:30–16:45, HU Senatssaal

Investigations of the magnetic field stability at SHIPTRAP — •C. Rauth — GSI, Planckstrasse 1, D-64291 Darmstadt, Germany

The ion trap facility SHIPTRAP at GSI Darmstadt was set up to study different properties of the heavy elements produced in fusion evaporation reactions at SHIP. First investigations focus on precision mass measurements with a Penning trap mass spectrometer. With these results the nuclear binding energy can be determined to test different nuclear models or to look at shell structure effects. The mass of an ion inside a Penning trap can be determined by measuring the cyclotron frequency ω_c which is given by ω_c=eB/m. In order to calibrate the magnetic field strength inside the trap, the cyclotron frequency of a reference ion with a well known mass is measured. The mass of the ion is calculated from the cyclotron frequency ratios and the mass of the reference ion. Systematic errors can occur if the magnetic field strength changes significantly between the two frequency measurements. To investigate the temporal stability of the magnetic field, the cyclotron frequency of different reference ions was measured over many days and the changes due to the variation of the magnetic field determined. As reference ions ¹³³Cs and ⁸⁵Rb from a surface ion source as well as nobel gases like ⁴⁰Ar from a cross beam ion source were used. Cross correlations between these measurements also allow to determine other systematic errors.