High-precision mass measurement of neutron-rich 96Kr

While the nuclear deformation in the region around Z = 40 and N = 60 has been studied in great detail, the possible onset of nuclear deformation in the isotopic chain of krypton (Z = 36) is still a subject of controversy. Here, we present a high-precision mass measurement of the neutron-rich nuclide 96Kr, as measured by the Multiple-Reflection Time-of-Flight Mass Spectrometer (MR-TOF-MS) at TRIUMF’s Ion Trap for Atomic and Nuclear Science (TITAN). A statistical method, based on a hyper-exponentially modified Gaussian, has been employed to model the data. As such, the uncertainty introduced by overlapping peaks from beam contaminants was reduced and the mass excess of 96Kr determined to be -53097(57)keV. The capability of the method has been confirmed with measurements of the stable isotopic pair 40Ar/40Ca, in which a relative accuracy Δm/m of 3.5 ⋅ 10− 8 and a mass resolving power of more than 400000 were achieved.