Book of Abstracts Book of Abstracts - Universität Konstanz

B - 48
96
Carbon clusters for the calibration in mass spectrometry
Alexander Herlert 1,2 , Sudarshan Baruah 1 , Klaus Blaum 3,4 , Michael Block 4 ,
Ankur Chaudhuri 1 , Frank Herfurth 4 , Alban Kellerbauer 2 , H.-Jürgen Kluge 4 ,
Gerrit Marx 1 , Mannas Mukherjee 4 , Lutz Schweikhard 1 , and Chabouh Yazidjian 2,4
for the ISOLTRAP and SHIPTRAP collaboration
1 Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17487 Greifswald, Germany
2 CERN, Department of Physics, 1211 Geneva 23, Switzerland
3 Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany
4 GSI, Planckstr. 1, 64291 Darmstadt, Germany
The masses of radionuclides are of importance in a wide range of physics branches [1]:
From nuclear structure studies to tests of the Standard model. Penning traps have proven to
allow the mass determination of short-lived nuclides with a relative mass uncertainty of less
than δm/m=1·10 -8 [2,3] and in case of stable nuclides even below 2·10 -11 [4,5].
The principle of accurate mass measurements is based on the precise determination of the
cyclotron frequency νc=qB/(2πm) of the stored ions in the trap. The experimental scheme
monitors the gain in kinetic energy of the radial ion motion after excitation with a quadrupolar
radiofrequency field [6]. For the determination of the ion mass, the magnetic field needs to be
calibrated. This is achieved with the measurement of the cyclotron frequency of an ion with
well-known mass. Here, carbon clusters are the reference particles of choice. First, the mass of a
12 C atom defines the atomic mass unit. Second, with respect to their mass, carbon clusters Cn are
distributed like a grid on the chart of nuclides, where the maximum distance of any nuclide to a
carbon cluster is six atomic masses.
In addition, cross-reference measurements allow consistency checks. Thus, carbon clusters
have been used to determine the systematic uncertainties in the mass determination of very
short-lived nuclides [7] at the triple trap mass spectrometer ISOLTRAP [8] at ISOLDE/CERN.
For these studies the clusters were produced by laser ablation from a Fullerene target [9]. A new
carbon cluster ion source has recently been installed and will be tested for the upcoming beamtime
period at ISOLDE/CERN. A similar cluster ion source is presently being installed at the
mass spectrometer SHIPTRAP [10] at GSI, which is devoted to mass spectrometry of superheavy
nuclides that are delivered from the mass separator SHIP. First results are presented.
References
[1] D. Lunney et al., Rev. Mod. Phys. 75, 1021 (2003).
[2] G. Bollen, Eur. Phys. J. A 15, 237 (2002).
[3] M. Mukherjee et al., Phys. Rev. Lett. 93, 150801 (2004).
[4] R.S. van Dyck et al., Phys. Rev. Lett. 92, 220802 (2004).
[5] S. Rainville et al., Science 303, 334 (2004).
[6] M. König et al., Int. J. Mass Spectrom.Ion Proc. 142, 95 (1995).
[7] A. Kellerbauer et al., Eur. Phys. J. D 22, 53 (2003).
[8] F. Herfurth et al., J. Phys. B: At. Mol. Opt. Phys. 36, 391 (2002).
[9] K. Blaum et al., Anal. Bioanal. Chem. 377, 1133 (2003).
[10] G. Marx et al., Hyperfine Interact. 146/147, 245 (2003).