Speaker
Jens Ketelaer
(Universität Mainz, Institut für Physik, Staudinger Weg 7, D-55128 Mainz, Germany)
Description
Nuclear masses are fundamental quantities in nature, reflecting the binding energy of the nucleons. In particular, experimentally determined masses of heavy nuclides provide new information on nuclear structure and test theoretical mass models in this region of the nuclear chart [1,2]. Masses of a few nobelium isotopes have been recently determined by SHIPTRAP (GSI, Darmstadt, Germany). However, none of the masses between uranium and californium has been directly measured yet, but most of them are linked to known species by alpha-decays [3].
We recently installed the double-Penning trap mass spectrometer TRIGA-TRAP at the nuclear research reactor TRIGA Mainz [4], which is dedicated in a first measurement period to off-line mass determinations of heavy nuclides between uranium and californium. For this purpose, a non-resonant laser ablation ion source has been developed, also providing carbon cluster ions for the calibration. The actual mass measurement can be carried out via the common Time-of-Flight-Ion-Cyclotron-Resonance (TOF-ICR) technique, where the mass value is determined by exciting and ejecting the ions from the trap and observing the minimum time of flight as a function of the excitation frequency. In a later stage, especially for nuclides with very low production rates of a few ions per minute but rather long half-lives above several tens of seconds, the non-destructive Fourier Transform-Ion Cyclotron Resonance (FT-ICR) technique will be employed for the first time for mass measurements on radionuclides. This method is based on the detection of image currents induced by the ions in the trap electrodes without the need for ion ejection, enabling repeated measurement cycles on the same stored charged particle. In future, this technique will be applied at the on-line facility SHIPTRAP for mass measurements on superheavy elements [5].
Besides mass measurements on heavy nuclides, TRIGA-TRAP will be connected to the research reactor TRIGA Mainz to exploit the field of neutron-rich nuclides produced by fission of 249Cf using the reactor. The status of the experiment as well as first mass measurements will be presented.
[1] Y. Oganessian, J. Phys. G 34 (2007) R165–R242.
[2] D. Lunney et al., Rev. Mod. Phys. 75 (2003) 1021.
[3] A. Wapstra et al., Nucl. Phys. A 729 (2003) 129.
[4] J. Ketelaer et al., Nucl. Instr. Meth. A 594 (2008) 162.
[5] M. Block et al., Eur. Phys. J. D 45 (2007) 39.
Author
Jens Ketelaer
(Universität Mainz, Institut für Physik, Staudinger Weg 7, D-55128 Mainz, Germany)
Co-authors
Christian Smorra
(Universität Mainz, Institut für Kernchemie, Fritz-Straßmann-Weg 2, D-55128 Mainz, Germany)
Christine Weber
(University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 Jyväskylä, Finland)
Dennis Neidherr
(Universität Mainz, Institut für Physik, Staudinger Weg 7, D-55128 Mainz, Germany)
Frank Herfurth
(Gesellschaft für Schwerionenforschung mbH, Planckstraße 1, D-64291 Darmstadt, Germany)
Jochen Ketter
(Universität Mainz, Institut für Physik, Staudinger Weg 7, D-55128 Mainz, Germany)
Julia Repp
(Universität Mainz, Institut für Physik, Staudinger Weg 7, D-55128 Mainz, Germany)
Klaus Blaum
(Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany)
Klaus Eberhardt
(Universität Mainz, Institut für Kernchemie, Fritz-Straßmann-Weg 2, D-55128 Mainz, Germany)
Martin Eibach
(Universität Mainz, Institut für Physik, Staudinger Weg 7, D-55128 Mainz, Germany)
Michael Block
(Gesellschaft für Schwerionenforschung mbH, Planckstraße 1, D-64291 Darmstadt, Germany)
Rafael Ferrer
(Universität Mainz, Institut für Physik, Staudinger Weg 7, D-55128 Mainz, Germany)
Sebastian George
(Universität Mainz, Institut für Physik, Staudinger Weg 7, D-55128 Mainz, Germany)
Szilard Nagy
(Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg, Germany)
Wilfried Nörtershäuser
(Universität Mainz, Institut für Kernchemie, Fritz-Straßmann-Weg 2, D-55128 Mainz, Germany)
