Bρ -defined isochronous mass spectrometry: An approach for high-precision mass measurements of short-lived nuclei

Abstract

A novel technique for broadband high-precision mass measurements of short-lived exotic nuclides is reported. It is based on the isochronous mass spectrometry (IMS) and realizes simultaneous determinations of revolution time and velocity of short-lived stored ions at the cooler storage ring CSRe in Lanzhou. The new technique, named as the Bρ-defined IMS or Bρ-IMS, boosts the efficiency, sensitivity, and accuracy of mass measurements, and is applied here to measure masses of neutron-deficient f p-shell nuclides. In a single accelerator setting, masses of 46 Cr, 50 Fe and 54 Ni are determined with relative uncertainties of (5 -6)×10 −8 , thereby improving the input data for testing the unitarity of the Cabibbo-Kobayashi-Maskawa quark mixing matrix. This is the technique of choice for future high-precision measurements of the most rarely produced shortest-lived nuclides.

Ground-state mass of 22Al and test of state-of-the-art ab initio calculations*

“…Therefore, the MED of mirror nuclei serves as a more sensitive observable for testing theoretical calculations when comparing the excitation spectra. Moreover, the mirror systems Al-F have been investigated using the ab initio Gamow shell model based on the same EM1.8/2.0 interaction [29]. Within the Gamow shell model calculations, the effective Hamiltonian is derived through the many-body perturbation theory, and continuum coupling is well accounted for using the Berggren basis.…”

“…This was due to the loosely bound proton in Al, which could be the origin of possible halo structure for the state [22]. Ab initio calculations have also been applied to investigate the large MEDs of the sd-shell nuclei [11,23,29]. The significant uncertainties in MEDs of Al-F mirror nuclei hinder direct comparison with theoretical predictions, thereby challenging our understanding of the isospin symmetry breaking in the dripline nucleus Al.…”