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We have investigated nuclear fragmentation reactions of a relativistic 208Pb beam.Ten isomeric states for nuclei with A = 142-152 and Z = 62-67 were observed. Measured isomeric ratios were compared, together with values from other experiments, with prediction of theoretical models. The discrepancies between the experimental and theoretical values were discussed in terms of transitions by-passing the isomer that are not included in the models. [ABSTRACT FROM AUTHOR]

Heavy neutron-rich nuclei were populated via relativistic energy fragmentation of a E/A = 1 GeV208Pb beam. The nuclei of interest were selected and identified by a fragment separator and then implanted in a passive plastic stopper. Delayed γ rays following internal isomeric decays were detected by the RISING array. Experimental information was obtained on a number of nuclei with Z = 73-80 (Ta-Hg), providing new information both on the prolate-oblate transitional region as well as on the N = 126 closed shell nuclei. [ABSTRACT FROM AUTHOR]

Neutron-deficient nuclei with N = 126 have been populated following projectile fragmentation of a 238U beam with energy 1 GeV/A. The decay of several previously reported isomers has been measured. This will allow us to calculate high-spin isomeric ratios and compare them with model calculations to allow a better understanding of the reaction mechanism. [ABSTRACT FROM AUTHOR]

Gamma rays from the decay of an isomer in 190W116 have been observed following projectile fragmentation of a 1 GeV per nucleon 208Pb beam. An earlier experiment indicated decay from a (10-) isomer to the ground state rotational band. Improved statistics have enabled gamma coincidence and time-difference measurements to be made which alter the previous interpretation. Blocked BCS calculations have also been used together with reduced hindrance factors to indicate possible values of spin-parity for the isomer. [ABSTRACT FROM AUTHOR]

Decays of neutron-rich A ~ 190 nuclei have been studied following projectile fragmentation of a 208Pb beam on a 9Be target at the GSI Fragment Separator. Gamma-ray decays from previously reported isomeric states in 188Ta, 190W and 192,193Re were used as internal calibrations for the particle identification analysis, together with the identification of previously unreported isomeric decays in 189Ta and 191W. The current work also identifies β-delayed γ rays following the decay of 188Ta to 188W for the first time. [ABSTRACT FROM AUTHOR]

The nuclear structure of neutron-rich N > 126 nuclei has been investigated following their production via relativistic projectile fragmentation of a E/A = 1 GeV 238U beam on a Be target. The preliminary analysis indicates the presence of previously unreported isomeric states in the N = 128 isotones 208Hg and 209Tl. [ABSTRACT FROM AUTHOR]

The fragmentation of a 550MeV/u primary beam of 58Ni on a 9Be target has been used to measure time- and energy-correlated γ decays following the implantation of event-by-event discriminated secondary fragments into a 9Be stopper plate. A new isomeric γ decay with T 1/2 = 14( $ \begin{smallmatrix}6 4\end{smallmatrix}$ ) ns and E γ = 646.2(2) keV is observed and attributed to the decay of the yrast 3/2- state in 53 27Co26 . This short-lived isomeric state has been populated by means of nuclear reactions during the stopping process of the secondary fragments. The experimental findings are discussed in the framework of large-scale spherical shell model calculations in conjunction with isospin symmetry-breaking residual interactions for the A = 53 , T z = ±1/2 mirror nuclei 53Co and 53Fe . [ABSTRACT FROM AUTHOR]

Relativistic fragmentation of 208Pb has been used to produce excited states in neutron-rich nuclei with N ≈ 126. Spectroscopic information for a range of nuclei has been obtained through observing delayed γ-ray emissions from isomeric states. Preliminary results for 203,204Pt nuclei are presented. For the first time, excited states have been observed in 203Pt and 204Pt. The yrast structure of 204Pt up to spin-parity, Iπ = (10+) has been tentatively inferred from the internal decay of two isomeric states. [ABSTRACT FROM AUTHOR]

The first results from a series of experiments focused on the study of the internal structure of nuclei at the extremes of N:Z ratio using isomer spectroscopy are reported. These experiments represent the first of the Stopped Beam section of the Rare Isotopes Investigations at GSI (RIS-ING) project. Exotic nuclei were synthesized using relativistic projectile fragmentation of ∼ 500 → 1000 MeV/u beams of 107Ag, 208Pb, 136Xe and 58Ni, or fission of 750 MeV/u 238U provided by the SIS synchrotron at GSI. A detailed description of the RISING stopped beam set up is given, together with a report of the performance of the associated gamma-ray spectrometer array. Selected results of the first experimental campaign are presented together with a discussion on the use of isomeric spectroscopy to study GeV range nuclear fragmentation. Details on future research plans of this collaboration are also outlined. [ABSTRACT FROM AUTHOR]

Preliminary results from the first experiment of the Stopped Beam RISING campaign are presented. The relativistic projectile fragmentation of a 750 MeV/u beam of 107Ag populated isomeric states in very neutron deficient nuclei at the proton dripline around mass 80-90. Nuclei were unambiguously identified using the FRagment Separator (FRS) and its ancillary detectors located at GSI. The ions produced were slowed down from relativistic energies by means of an Al degrader and implanted in the centre of the high-efficiency Stopped RISING array. This allowed the identification of new excited states in the N = Z = 43 nucleus, 86Tc, populated following the de-excitation of a microsecond isomer. Preliminary results of this analysis, as well as previously unobserved isomeric states in 87,88Tc, are reported. [ABSTRACT FROM AUTHOR]

The single-particle structure and shell gap of 100Sn is inferred from prompt in-beam and delayed γ-ray spectroscopy of seniority and spin-gap isomers. Recent results in 94, 95Ag and 98Cd stress the importance of large-scale shell model calculations employing realistic interactions for the isomerism, np- nh excitations and E2 polarisation of the 100Sn core. The strong monopole interaction of the Δ l = 0 spin-flip partners π g9/2- ν g7/2 in N = 51 isotones below 100Sn is echoed in the Δ l = 1 π f5/2- ν g9/2 pair of nucleons, which is decisive for the persistence of the N = 50 shell gap in 78Ni. This is corroborated by recent experimental data on 70, 76Ni, 78Zn. The importance of monopole driven shell evolution for the appearance of new shell closures in neutron-rich nuclei and implications for r-process abundances near the N = 82 shell is discussed. [ABSTRACT FROM AUTHOR]

We report results from a pioneering experiment to measure the g factors of isomeric states of neutron-rich nuclei around [sup 68]Ni, far from the valley of β stability. For the first time, the timedependent perturbed angular distribution method was applied in combination with the heavy-ion-γ correlation technique to study g factors of spin-aligned isomers produced in a projectile fragmentation reaction and mass-separated. Some technical aspects are discussed and illustrated with preliminary results. [ABSTRACT FROM AUTHOR]

Isomeric states in the semimagic 128-130Sn isotopes were populated in the fragmentation of a 136Xe beam on a 9Be target at an energy of 750 A·MeV. The decay of an isomeric state in 128Sn at an excitation energy of 4098 keV has been observed. Its half live has been determined to be T½ = 220(30) ns from the time distributions of the delayed γ rays emitted in its decay. γ γ coincidence relations were analyzed in order to establish the decay pattern of the newly established state toward the known (7-) and (10+) isomers at excitation energies of 2092 and 2492 keV, respectively. Based on a comparison with results of state-of-the-art shell-model calculations the new isomeric state is proposed to have the υh11/2-3d3/2-1 configuration with the four neutron holes in 132Sn maximally aligned to a total spin of Iπ = 15-. [ABSTRACT FROM AUTHOR]

Abstract: Neutron-rich nuclei in the lead region, beyond , have been studied at the FRS-RISING setup at GSI, exploiting the fragmentation of a primary uranium beam. Two isomeric states have been identified in 210Hg: the isomer expected from the seniority scheme in the shell and a second one at low spin and low excitation energy. The decay strength of the isomer confirms the need of effective three-body forces in the case of neutron-rich lead isotopes. The other unexpected low-lying isomer has been tentatively assigned as a state, although this is in contrast with theoretical expectations. [Copyright &y& Elsevier]

Gamma rays from the decay of an isomer in 190W116 have been observed following projectile fragmentation of a 1 GeV per nucleon 208Pb beam. An earlier experiment indicated decay from a (10-) isomer to the ground state rotational band. Improved statistics have enabled gamma coincidence and time-difference measurements to be made which alter the previous interpretation. Blocked BCS calculations have also been used together with reduced hindrance factors to indicate possible values of spin-parity for the isomer. [ABSTRACT FROM AUTHOR]

Abstract: The first results from the stopped beam RISING experimental campaign performed at the GSI laboratory in Darmstadt, Germany, are presented. RISING (Rare ISotope Investigations at GSI) constitutes a major new experimental program in European nuclear structure physics research aimed at using relativistic energy (typically around 1GeV per nucleon) projectile fragmentation reactions to populate nuclei with highly exotic proton-to-neutron ratios compared to the line of beta stability. In its high-efficiency ‘stopped beam’ configuration, the RISING γ-ray spectrometer consists of 105 individual, large volume germanium crystals which view a focal plane in which the exotic nuclei are brought to rest (i.e. ‘stopped’). Here, decays from metastable or ‘isomeric’ states with half-lives in the nano to milliseconds range can be observed, often providing the first spectroscopic information on these exotic nuclear species. This paper introduces the physics aims of the stopped RISING collaboration and presents some technical details on the RISING detector array. Results of initial commissioning experiments are also shown and details of the planned future experimental program are given. [Copyright &y& Elsevier]