SMILETRAP—A Penning trap facility for precision mass measurements using highly charged ions

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2002-07, Vol.487 (3), p.618-651
• Main Authors: Bergström, I., Carlberg, C., Fritioff, T., Douysset, G., Schönfelder, J., Schuch, R.
• Format: Article
• Language: English
• Subjects: Fundamental constants; Highly charged ions; Mass measurements; Penning trap
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/S0168-9002(01)02178-7

The precision of mass measurements in a Penning trap increases linearly with the charge of the ion. Therefore we have attached a Penning trap, named SMILETRAP, to the electron beam ion source CRYSIS at MSL. CRYSIS is via an isotope separator connected to an ion source that can deliver singly charged ions of practically any element. In CRYSIS charge state breeding occurs by intense electron bombardment. We have shown that it is possible to produce, catch and measure the cyclotron frequencies of ions in the charge region 1+ to 52+. The relevant observable in mass measurements using a Penning trap is the ratio of the cyclotron frequencies of the ion of interest and ion used as a mass reference. High precision requires that the two frequencies are measured after one another in the shortest possible time. For reasons of convenience the precision trap operates at room temperature. So far it has been believed that warm traps working at 4 K are required for high mass precision with exactly one ion in the trap at a time. In this paper we demonstrate that mass precision of a few parts in 10 10 also can be obtained in a warm trap at a pressure of about 5×10 −12 mbar by stabilizing the pressure in the He-dewar, the trap temperature and the frequency synthesizer. In order to reduce the influence of changes of the magnetic field to a level below 10 −10, the scanning of the frequencies close to the resonances of both the ion of interest and the reference ion is done in a total time