The Proton Drip Line Near 100Sn

by Dr Roman Gernhaeuser (TUM)

Monday 19 Oct 2015, 14:15 → 15:45 Europe/Berlin

3344 (TUM - Physics Department - Garching)

The investigation of the shell structure far from the valley of stability is a major task in modern nuclear structure physics. Especially the region around the doubly magic nucleus 100Sn close to the drip line is of particular interest [1] due to the large gap between the g9/2 and g7/2 shells for protons and neutrons. This region was studied since many years and recently the decay of 100Sn was established to show the smallest log(ft) = 2.62+0.13 -0.11 value in the nuclear chart [2]. At the RIBF facility of the RIKEN Nishina Center a 124Xe beam of 345 MeV/u energy at intensities up to 40 pnA became available in 2013. Using projectile fragmentation on a 4 mm Be target a recent experiment was able to produce and identify 2525 100Sn ions which increases the world statistics in this nucleus by about one order of magnitude. Furthermore, a number of nuclides towards the proton drip line like 94Cd, 92Ag, 90Pd have been newly identified and first evidence for the existence of 96In and 98Sn has been found. In order to observe - and -decays, 100Sn and most of the neighboring nuclei were implanted into the WAS3ABi detector, which is a compact stack consisting of 3 highly segmented silicon detectors of 1 mm thickness each, surrounded by 84 Ge- and 18 LaBr3 detectors of the 4-spectrometer EURICA. This WAS3ABi detector array was extended by a stack of 10 silicon detectors of the same thickness in order to measure the total energy of the decay positrons accurately. We will report on a series of selected topics covered by this large data sample on exotic nuclei in the N=Z and N=Z-1 region. New beta-decay half-lives, spectroscopy on isomers, and a survey of beta delayed gamma rays and protons provide valuable spectroscopic information. References [1] T. Faestermann, M. Gorska, H. Grawe, Prog. Part. Nuc. Phys. 69, 85-130 (2013). [2] C. Hinke et al., Nature 486, 341 (2012).