Isomer and decay studies for the rp process at IGISOL

This article reviews the decay studies of neutron-deficient nuclei within the mass region \ensuremathA=56--100 performed at the Ion-Guide Isotope Separator On-Line (IGISOL) facility in the University of Jyväskylä over last 25 years. Development from He-jet measurements to on-line mass spectrometry, and eventually to atomic mass measurements and post-trap spectroscopy at IGISOL, has yielded studies of around 100 neutron-deficient nuclei over the years. The studies form a solid foundation to astrophysical rp -process path modelling. The focus is on isomers studied either via spectroscopy or via Penning-trap mass measurements. The review is complemented with recent results on the ground and is…

Isomers of astrophysical interest in neutron-deficient nuclei at masses A = 81, 85 and 86

Decay properties of neutron-deficient exotic nuclei close to A=80 have been investigated at the IGISOL facility. The studied nuclei, 81Y, 81Sr, 81mKr, 85Nb, 85Zr, 86Mo and 86Nb, were produced by a 32S beam from the Jyväskylä isochronous cyclotron on 54Fe and natNi targets. The internal conversion coefficient for a 190.5 keV isomeric transition in 81mKr has been measured and the internal transition rate has been determined. The internal transition rate has been used to estimate a neutrino capture rate on 81Br, which yields a log ft of 5.13±0.09 for the reaction 81Br( ν, e-)81mKr. A new isomer with a half-life of 3.3±0.9 s has been observed in 85Nb. The existence of an earlier reported isomer…

Quenching of the SnSbTe Cycle in the rp-Process

Mass measurements of neutron-deficient nuclides close to A=80 with a Penning trap

The masses of 80,81,82,83Y, 83,84,85,86,88Zr and 85,86,87,88Nb have been measured with a typical precision of 7 keV by using the Penning trap setup at IGISOL. The mass of 84Zr has been measured for the first time. These precise mass measurements have improved Sp and QEC values for astrophysically important nuclides. peerReviewed

Quenching of the SnSbTe Cycle in therpProcess

The nuclides 104-108Sn, 106-110Sb, 108,109Te, and 111I at the expected endpoint of the astrophysical rp process have been produced in 58Ni+natNi fusion-evaporation reactions at IGISOL and their mass values were precisely measured with the JYFLTRAP Penning trap mass spectrometer. For 106Sb, 108Sb, and 110Sb these are the first direct experimental mass results obtained. The related one-proton separation energies have been derived and the value for 106Sb, Sp=424(8) keV, shows that the branching into the closed SnSbTe cycle in the astrophysical rp process is weaker than expected.