[en] The β +/EC-decay of "1"0"0In, the one proton-hole and one neutron-particle neighbour nucleus to the doubly-magic "1"0"0Sn, was investigated at the GSI ISOL facility by using a Germanium detector array for high-resolution spectroscopy and a highly-efficient NaI total-absorption spectrometer (TAS) to measure the Gamow-Teller (GT) strength and distribution. The beta-decay scheme was studied for the first time. Large-scale shell-model calculations using a realistic interaction are used to assign configurations to low-lying states in "1"0"0In and "1"0"0Cd. The experimental GT beta-decay strength distributions as measured in TAS are compared to shell-model predictions. The hindrance factor for the total GT strength amounts to h=4.1(9). This value agrees well with a value extrapolated for the GT resonance in "1"0"0Sn from previously measured values in neighbouring nuclei.

[en] Two main mechanisms are predicted to drive the possible shell evolution phenomena: the first is the so called monopole migration [1], which acts for both proton and neutron-rich nuclei, and the second, shell quenching, which is due to a softening of the potential shape that results from the presence of an excessive number of neutrons in very neutron-rich nuclei [2]. These mechanisms modify the known magic numbers as a consequence of shifting effective single-particle levels when going towards either the proton or the neutron drip lines. In medium-heavy nuclei the effort to establish shell evolution concentrates around the 1^00Sn [3] and 1^32Sn [4,5] doubly magic nuclei. The Sn isotopes form the longest isotopic chain in the nuclear chart accessible to current experimental study and thus provide a stringent testing ground for nuclear structure models. A remarkable similarity was found between the decay of 8⁺ isomers in 9^8Cd₅₀ [6] and 1^30Cd₈₂ [5], both of which have a pure g_9/2^-2 proton-hole configuration. However, the analogue of the known core excited isomer in 9^8Cd [7] was not observed in 1^30Cd, within experimental sensitivity, thus underlining the differences in the underlying neutron single-particle structure. The understanding of analogies in the structure of both regions of nuclei and the evolution of the N=82 shell gap below 1^32Sn is of importance in predicting the path of the rapid-neutron capture process which partially drives the production of elements heavier than Fe in nature. A handful of additional information on these two regions of nuclei was obtained recently in spectroscopy studies within the Rare ISotopes INvestigation at GSI (RISING) project [8,9] including the rp-process waiting point nuclei. Selected results will be discussed and compared with large scale shell model calculations using various sets of the realistic residual two-body interaction.(author)

[en] The research programme pursued at the ISOL facility of GSI Darmstadt focuses on the study of decay properties of nuclei along the N congruent with Z line between the double shell closures at ⁵⁶Ni and ¹⁰⁰Sn. In this report, the major scientific achievements obtained in the past two years are reviewed, with particular emphasis being put on the detection techniques

[en] In recent years collectivity in the mass region around A = 100 has become the focus of increased interest. The N = 52 isotones were investigated in detail and phonon excitations -especially one- and two-phonon mixed-symmetry states--were identified. In order to investigate how vibrator-like behavior and states with mixed-symmetry character evolve with increasing neutron number it is interesting to study the N = 54 isotones. Therefore an experiment to measure the low-spin excitations of ¹⁰⁰Pd was performed at the FN-Tandem accelerator with the HORUS cube spectrometer. Besides the determination of excitation and transition energies and branching ratios, spins and multipole mixing ratios resulted from the γγ angular correlation analysis. The newly gained data were compared with predictions from theory both from collective models and from shell model.

[en] The N = 52 nucleus ⁹⁸Pd was investigated at the Cologne TANDEM accelerator both with the Cologne plunger using the recoil distance Doppler-shift method (RDDS) and with the Cologne HORUS spectrometer for a γγ angular correlation experiment. For the first time lifetimes of yrast states and highly excited low-spin states were measured in ⁹⁸Pd and the low-spin level scheme was extended. From our data we were able to interpret ⁹⁸Pd as a nucleus that exhibits some collective features, but is obviously much less collective than the neighboring N = 52 isotones ⁹⁴Mo and ⁹⁶Ru due to its closeness to doubly-magic ¹⁰⁰Sn.

[en] We have observed the high-spin states in ⁹³Rh populated by delayed-proton emission following the β decay of ⁹⁴Ag. The existence of a second isomer in ⁹⁴Ag with I≥17, T1/2=0.42(5) s, whose β-decay energy is at least 15.5 MeV, has been established. This state features most likely the highest spin ever observed for β-decaying nuclei. (orig.)

[en] Recently, lifetimes of low-lying excited states in ¹²⁸Xe were measured using the plunger technique after projectile Coulomb excitation. This experiment was performed at the JYFL, Jyvaeskylae using the JUROGAM Ge-detector array and the Cologne coincidence plunger device equipped with an array of 32 small Si-detectors. The Si-detectors were used to measure the reaction kinematics by registering target-like nuclei scattered in forward direction. In order to cross-check the results obtained from the recoil distance Doppler shift analysis an evaluation of the measured excitation cross-sections was performed with the computer code GOSIA. In addition deorientation effects were investigated and effort was made to extract absolute quadrupole moments. Details of the experiment and the calculations are presented.

[en] A systematic study was performed of microsecond gamma-decaying isomers around ¹⁰⁰Sn produced in a fragmentation reaction of a ¹²⁴Xe beam at 345 MeV/u at the Radioactive Ion Beam Factory of the RIKEN Nishina Center in Saitama, Japan. Half-lives of isomeric states in that region were remeasured allowing us to improve the currently available experimental information. Reduced transition probabilities were deduced and compared to shell-model calculations in various model spaces. The recently reported low-energy transitions in ⁹²Rh and ⁹⁶Ag were remeasured with improved precision. Additionally, experimental information on isomeric ratios, including five new ones, were extracted and compared to a previous experimental study and the sharp cutoff model of fragmentation reaction. (authors)

No abstract available

[en] The study of nuclei in the region around the N = Z doubly-magic nucleus ¹⁰⁰Sn has been of long standing interest for the nuclear structure and nuclear astrophysics. Recently, Park et al. have reported on properties of gamma-decaying isomers and isomeric ratios in the vicinity of ¹⁰⁰Sn. That experiment was performed at the Radioactive Ion Beam Factory (RIBF) of the RIKEN Nishina Center in Japan as a part of the EURICA campaign. Neutron-deficient nuclei were produced in a fragmentation reaction of a ¹²⁴Xe primary beam on a 9 Be target at an energy of 345 MeV/A. Secondary ions were separated and identified in the BigRIPS fragment separator and implanted in the silicon detector array WAS3ABi. The data presented here were obtained in another experiment performed at the RIBF using the same reaction but slightly different separator settings. New results of ratios of isomeric population and half-lives of gamma-decaying isomers populated in the experiment are presented. (authors)