Speaker
Marco Rosenbusch
(Ernst-Moritz-Arndt-Universitaet (DE))
Description
The mass is a unique property of an atomic nucleus, reflecting its binding energy and thus the sum of all interactions at work in the atom. Precise measurements of nuclear masses, especially of short-lived exotic nuclides with extreme proton-to-neutron imbalance, provide important input for nuclear structure and nuclear astrophysics investigations, for tests of the Standard Model, and for weak interaction studies. The Penning-trap mass spectrometer ISOLTRAP at the on-line isotope separator ISOLDE/CERN was set up and continuously improved for precision mass measurements of more and more exotic nuclides. Currently ISOLTRAP consists of four traps [1]: a linear radio-frequency quadrupole cooler and buncher, a multi-reflection time-of-flight mass separator (MR-ToF MS), and two Penning traps. In the MR-ToF MS, ions of interest are separated from isobaric contaminants within a few ten milliseconds by multiple reflections between two electrostatic mirrors, which allowed the fast selection of, e.g., 82Zn+ [2].
Until recently, ISOLTRAP’s precision mass measurements were performed only with the well-established Penning Trap technique. However, the use of the MR-ToF device itself as a precision mass spectrometer has opened the door to nuclides with even shorter half-lives and lower production yields as demonstrated by mass measurements of the calcium isotopes 53,54Ca with sub-ppm uncertainty. These measurements revealed the magic neutron number N = 32 in the calcium isotopes by analysis of mass differences [3].
The investigation of the new magic number has now been continued by the mass determination of the potassium isotopes 52,53K+, neighboring isotones of 53,54Ca+. The N = 32 shell closure is observed again for the potassium chain, i.e. for the element that has one proton less than the closed Z = 20 proton shell of the calcium isotopes. In this contribution, the experimental S2N values for potassium will be presented and compared to HFB calculations.
[1] S. Kreim et al. NIM B, in press, 2013. http://dx.doi.org/10.1016/j.nimb.2013.07.072
[2] R. N. Wolf et al. Phys. Rev. Lett., 110, 041101, 2013. http://dx.doi.org/10.1016/j.ijms.2013.03.020
[3] F. Wienholtz et al. Nature, 498, 346-349, 2013. http://dx.doi.org/10.1038/nature12226
Primary author
Marco Rosenbusch
(Ernst-Moritz-Arndt-Universitaet (DE))
