Speaker
Emma Haettner
(II. Physikalisches Institut, Justus-Liebig-Universität, 35392 Gießen, Germany and GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany)
Description
The masses of proton-rich nuclides in the element range from Sr to Tc were measured with the Penning trap mass spectrometer SHIPTRAP [1] at GSI. These nuclei were produced in the fusion-evaporation reaction 36Ar + 54Fe at energies of 5.0 and 5.9 MeV/u and separated by the velocity filter SHIP [2]. Their masses were measured with relative accuracies ranging from 5·10-8 to 2·10-7.
The masses of 85,86,87Mo and 87Tc were measured for the first time in a direct measurement; 85Mo and 87Tc are the heaviest N=Z+1 nuclides measured in a Penning trap. Results from this experiment show a shift of the mass surface towards less-bound nuclei. Shifts in the mass excess values of up to 1.6 MeV is observed compared to the values of the 2003 Atomic Mass Evaluation (AME 2003) [3]. Previous experiments at SHIPTRAP and JYFLTRAP show a similar trend for neighboring nuclides, but less strong [4,5]. Even though the masses generally are shifted in the same direction, the changes also influence the proton and neutron separation energies. For example, the proton separation energy of 87Tc has now been determined to be only half that of the extrapolated value given in the AME 2003.
The newly measured and extrapolated mass data serve as important input for improved calculations on the rp-process path. Preliminary data on mass excess, separation energies, and their impact on rp-process network calculations will be discussed. Perspectives and developments for future mass measurements at SHIPTRAP targeting N=Z nuclei will be outlined.
[1] M. Block et al., Eur. Phys. J. D 45 (2007) 39.
[2] S. Hofmann and G. Münzenberg, Rev. Mod. Phys. 72 (2000) 733.
[3] G. Audi et al., Nucl. Phys. A 729 (2003) 337.
[4] A. Kankainen et al., Eur. Phys. J. A 29 (2006) 271.
[5] C. Weber et al., Phys. Rev. C 78 (2008) 054310.
Author
Emma Haettner
(II. Physikalisches Institut, Justus-Liebig-Universität, 35392 Gießen, Germany and GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany)
Co-authors
C. Scheidenberger
(II. Physikalisches Institut, Justus-Liebig-Universität, 35392 Gießen, Germany and GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany)
C. Weber
(Department of Physics, University of Jyväskylä, 40014 Jyväskylä, Finland; now at Fakultät für Physik, Ludwig-Maximillians-Universität, 85748 Garching, Germany)
D. Ackermann
(GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany)
D. Rodriguez
(Universidad de Huelva, Avda. de las Fuerzas Armadas s/n, 21071 Huelva, Spain; now at Departamento de FAMN, Universidad de Granada, 18071 Granada, Spain.)
F. Herfurth
(GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany)
F.P. Hessberger
(GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany)
G. Vorobjev
(GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany)
H.-J. Kluge
(GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany)
J. Ketelaer
(Institut für Physik, Johannes-Gutenberg-Universität, 55099 Mainz, Germany)
J. Ketter
(Institut für Physik, Johannes-Gutenberg-Universität, 55099 Mainz, Germany)
K. Blaum
(GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany and Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany)
L. Schweikhard
(Institut für Physik, Ernst-Moritz-Arndt-Universität, 17487 Greifswald, Germany)
M. Block
(GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany)
P.G. Thirolf
(Fakultät für Physik, Ludwig-Maximillians-Universität, 85748 Garching, Germany)
S. Eliseev
(Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany)
S. Hofmann
(GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany)
S. Rahaman
(Department of Physics, University of Jyväskylä, 40014 Jyväskylä, Finland)
T. Fleckenstein
(II. Physikalisches Institut, Justus-Liebig-Universität, 35392 Gießen, Germany)
W.R. Plass
(II. Physikalisches Institut, Justus-Liebig-Universität, 35392 Gießen, Germany and GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany)
Yu.N. Novikov
(GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany and Petersburg Nuclear Physics Institute, RU-188300 Gatchina, St. Petersburg, Russia)