Nov 25 – 27, 2013
Europe/Zurich timezone

Testing the magic number N = 32 with multi-reflection time-of-flight mass measurements of the exotic potassium isotopes A = 52 and A = 53

Nov 25, 2013, 6:10 PM
1h 20m
The Globe (CERN)

The Globe



Marco Rosenbusch (Ernst-Moritz-Arndt-Universitaet (DE))


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. [2] R. N. Wolf et al. Phys. Rev. Lett., 110, 041101, 2013. [3] F. Wienholtz et al. Nature, 498, 346-349, 2013.

Primary author

Marco Rosenbusch (Ernst-Moritz-Arndt-Universitaet (DE))

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