Population inversion of nuclear states by a Penning trap mass spectrometerK. Blaum1, 2, D. Beck2, G. Bollen3, P. Delahaye1, C. Guénaut4, F. Herfurth2, A. Kellerbauer1, H.-J. Kluge2, D. Lunney4, S. Schwarz3, L. Schweikhard5 and C. Yazidjian2
1 CERN, Physics Department - 1211 Genève 23, Switzerland
2 GSI - Planckstraße 1, 64291 Darmstadt, Germany
3 NSCL, Michigan State University - East Lansing, MI 48824-1321, USA
4 CSNSM-IN2P3-CNRS - 91405 Orsay-Campus, France
5 Institute of Physics, Ernst-Moritz-Arndt-University - 17487 Greifswald, Germany
(Received 7 April 2004; accepted 2 June 2004)
According to the energy-mass equivalence, E=mc2, excited long-lived nuclear states, so-called isomers, are distinguished from the ground state by their additional mass. The ultra-high accuracy provided by Penning traps now allows to weigh nuclear excitation energies. With the on-line Penning trap mass spectrometer ISOLTRAP, we have developed a mass-separation procedure of sufficient resolving power to isolate particles of a selected isomeric state from an ensemble delivered from the radioactive beam facility ISOLDE at CERN, first demonstrated for . The resulting unique form of ion ensembles opens up a large variety of new nuclear-physics experiments. Mass excesses of -65567.0(1.6) for the 1+ ground state and -64850.3(1.5) for the 6- isomeric state have been determined.
21.10.Dr - Binding energies and masses.
07.75.+h - Mass spectrometers.
21.10.-k - Properties of nuclei; nuclear energy levels.
© EDP Sciences 2004