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Preliminary results of the data analysis of the beta decay of 94Rb using a novel - segmented- total absorption spectrometer are shown in this contribution. This result is part of a systematic study of important contributors to the decay heat problem in nuclear reactors. In this particular case the goal is to determine the beta intensity distribution below the neutron separation energy and the gamma/beta competition above.

Shell gap at the magic number N = 82 is important to reproduce the 2nd peak of r-process abundance. If a spin-orbit force is reduced in a very neutron-rich region, a shell quenching at N = 82 and a new shell closure at N = 70 are predicted. A shell evolution by the spin-orbit-force reduction can be searched for through the shape evolution of Zr isotopes around an expected double magic nuclei, 110Zr(Z=40,N=70). We performed β-γ and isomer spectroscopy at RIBF to observe low-lying states in 106,108Zr. The present results indicate a well deformed shape for 106,108Zr. The drastic reduction of the spin-orbit force most likely does not occur around 110Zr on an r-process path. © 2012 American Institute of Physics.

7Li induced-reactions have been used with a 186W target to populate nuclei around A∼180-190 at the National Institute of Physics and Nuclear Engineering in Bucharest, Romania. An array of high-purity germanium (HPGe) and cerium-doped lanthanum bromide (LaBr3:Ce) detectors have been used to measure sub-nanosecond half-lives with fast-timing techniques. The yrast 2+ state in 190Os was measured to be t1/2 = 375(20)ps, in excellent agreement with the literature value. The previously unreported half-life of the 564-keV state in 189Ir has also been measured and a value of t1/2 = 540(100)ps ps obtained.

A RISING experiment with an aim to study exotic Cd nuclei was carried out at GSI‐FRS facility. Some preliminary results from this experiment are presented here. In particular, the β decay of 96Cd to 96Ag revealed the existence of a high spin isomer predicted a few decades ago. In this context, the structures of both these nuclei are discussed. Shell model calculations using the Gross‐Frenkel interaction are used to interpret the results.

This conference paper outlines the operation and some of the preliminary physics results using the GSI RISING active stopper. Data are presented from an experiment using combined isomer and beta‐delayed gamma‐ray spectroscopy to study low‐lying spectral and decay properties of heavy‐neutron‐rich nuclei around A∼190 produced following the relativistic projectile fragmentation of 208Pb primary beam. The response of the RISING active stopper detector is demonstrated for both the implantation of heavy secondary fragments and in‐situ decay of beta‐particles. Beta‐delayed gamma‐ray spectroscopy following decays of the neutron‐rich nucleus 194Re is presented to demonstrate the experimental performance of the set‐up. The resulting information inferred from excited states in the W and Os daughter nuclei is compared with results from Skyrme Hartree‐Fock predictions of the evolution of nuclear shape.

An open problem in Nuclear Astrophysics concerns the understanding of electron‐screening effects on nuclear reaction rates at stellar energies. In this framework, we have proposed to investigate the influence of the electron cloud on α‐decay by measuring Q‐values and α‐decay half‐lives of fully stripped, H‐like and He‐like ions. These kinds of measurements have been feasible just recently for highly‐charged radioactive nuclides by fragmentation of 238U at relativistic energies at the FRS‐ESR facility at GSI. In this way it is possible to produce, efficiently separate and store highly‐charged α‐emitters. Candidates for the proposed investigation were carefully selected and will be studied by using the Schottky Mass Spectroscopy technique. In order to establish a solid reference data set, lifetimes and Qα‐value measurements of the corresponding neutrals have been performed directly at the FRS, by implanting the separated ions into an active Silicon stopper.

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, projectile‐fragmentation reactions to study nuclei with exotic proton‐to‐neutron ratios. This paper introduces the physics aims of the Stopped RISING collaboration and presents some technical details and initial results from experiments using the RISING array to study decays from metastable nuclear states in both proton and neutron‐rich nuclei.

Fusion‐fission reactions were induced by bombarding a thick 27Al target with 178Hf projectiles at a laboratory energy of 1150 MeV using the ATLAS accelerator at Argonne National Laboratory. The subsequent γ‐ray decays were measured using the GAMMASPHERE germanium detector array. The beam was pulsed at two different ON/OFF cycles of 82.5/825 ns and 25/75 μs in order to observe the γ rays from the decay of isomeric states. In 121Sb 2721+Δ keV, Iπ=(25/2+) and 2434 keV, Iπ=19/2− states have measured half‐lives of T1/2=200(30) μs and 8.2(2) ns respectively. The 2614+Δ keV, Iπ=(27/2+) and 2486 keV, Iπ=19/2+ states in 123Sb have measured half‐lives of T1/2=52(3) μs and 7.9(4) ns respectively. The positive parity isomers in these nuclei correspond to a πd5/2 or πg7/2 configuration, in 121Sb and 123Sb respectively, coupled to aligned (h11/2)2 neutrons. The Iπ=19/2− isomeric state in 121Sb is proposed to have a νh11/2 ⊗ νd3/2 ⊗ πd5/2 configuration. A previously unobserved isomer has been identified in 99Mo at an en...

The population of metastable states produced in relativistic‐energy fragmentation of a 238U beam has been measured. For states with high angular momentum, I=17ℏ and I=21.5ℏ, a higher population than expected has been observed, with the discrepancy increasing with angular momentum. By considering two sources for the angular momentum, related to single‐particle and collective motions, a much improved description of the experimental results can be obtained. In addition, new results on the structure of 208Fr, 211Ra and 216Ac are reported.

This contribution reports on the results of an experiment to study the near‐yrast states in selenium‐ and osmium‐like nuclei, following their population in thick‐target, multinucleon transfer reactions between an 82Se beam and a 192Os target. The experimental results for the level scheme for 84Se are presented together with investigations into the use of multi‐dimensional gamma‐ray energy gating to investigate angular momentum population in such heavy‐ion binary reactions.

Isomeric states in neutron‐deficient nuclei around A ≈190 have been identified following the projectile fragmentation of a relativistic energy 238U beam. The deduced isomeric ratios are compared with a model based on the abrasion‐ablation description. The experimental isomeric ratios are lower by a factor of ≈2 than the calculated ones assuming the ‘sharp cutoff’ approximation. The observation of the previously reported isomeric Iπ=43/2− state in 215Ra represents the current record for the highest discrete spin state observed following a projectile fragmentation reaction.

The present work reports on the 76195Os isotope, which is the most neutron‐rich osmium isotope for which transitions have been measured. It has been populated following a multi‐nucleon transfer reaction between a thin 78198Pt target and an 850‐MeV 54136Xe beam. Evidence from γ‐ray coincidences has been found for an Iπ = (272−) isomeric state with a measured half‐life of 26 ± 9ns.

The structure of stable and neutron‐rich nuclei with Z∼42 and N∼58 have been studied following binary heavy‐ion reactions between a 136Xe beam and a thin, self‐supporting 100Mo target. Discrete states at spins of 20ℏ and above have been identified and these data allow both gamma‐ray fold and binary‐fragment particle angular distribiution analyses to be made. On the basis of these results, suggestions are made for future directions of this research extending to higher spin states in this region where more exotic nuclear shapes are predicted.

Multinucleon transfer reactions between a thin 100Mo target and a 136Xe beam at an energy of 700 MeV have been used to investigate the evolution of structure with increasing angular momentum in a range of nuclei with A∼100. The use of kinematically complete experiments coupled with isomer tagging allow the selection of specific exit channels. The evolution from quasi‐vibrational states at low spins to quasi‐rotational structures following the population of a low‐Ω, ‘rotationally aligned’ h11/2 neutron configuration is demonstrated to be a standard feature of the region using the so‐called E‐Gamma Over Spin (E‐GOS) empirical prescription. This treatment is extended to odd‐A nuclei.

This paper reports on a test experiment to investigate the viability of using in‐beam gamma‐ray spectroscopy with projectile fragmentation reactions to explore the structure of heavy, neutron‐rich nuclei. The experiment used a ‘thin target’ fragmentation reaction with a 30 MeV per nucleon 12C beam on a 30 mg/cm2 self‐supporting gold target. The initial analysis has identified a number of previously known discrete cascades in a variety of in‐beam reaction products. The decay of products has also been investigated and an initial comparison of their relative yields with predictions from the EPAX parameterisation begun. The relevance and future viability of this method as a complimentary technique to fragmentation‐isomer studies to investigate the near‐yrast properties of heavy, neutron‐rich nuclei is discussed.

Fragmentation of 208Pb has been used to populate very neutron-rich nuclei in the transitional region with A∼190–200. The isomeric states of these nuclei have been studied using γ-ray spectroscopy. After fragmentation, the nuclei of interest were separated, identified and finally implanted in an aluminum plate surrounded by a γ-spectroscopy set-up. This experiment has proven the ability of such a technique to populate medium to high spin states and γ-ray transitions have been observed for the first time in a number of neutron-rich nuclei in this region, including 190W, 195Os, 197Ir, 202Pt.

A complete study of the nuclear structure by means of gamma spectroscopy requires, in addition to the high resolution gamma measurement and accurate DCO's or angular distributions, the information concerning the Electric or Magnetic character of the transition. This information for transitions in nuclei far from stability valley is now reachable in the new generation of Ge-arrays based in composite detectors. EUROBALL III is a good example with the high polarization sensitivity of the 90 degrees ring of Clovers. The Polarization correlations PCO's measured in coincidence with the Cluster detectors permits to investigate transitions in weakly populated nuclei. In this contribution we present results on medium mass N=Z nuclei measured with EUROBALL III coupled with light particle ancillary detectors. (Less)

The high-spin states of the N=Z nucleus 64Ge have been investigated using the EUROBALL array coupled to the ISIS Si-ball and to a highly efficient n-Wall. Spins and parities were assigned on the basis of a DCO and of a polarization analysis.

The results of recent experiments performed at L.N.L. on multiple octupole excitations in the N=84 isotones are reviewed. In particular, the results on B(E3) strengths in 146Sm are discussed and expectations for higher-order octupole excitations are compared with the present experimental situation.

The high-spin structure of the N≃Z nuclei 62,64,65Ga have been investigated using the EUROBALL array coupled to the ISIS Si-ball. The collective bands of such nuclei are then compared showing an unexpected behavior.

Gamma spectroscopy methods have been used to search for microsecond isomers among fragmentation products of 1 GeV/nucleon 208Pb beam. Decays of several known K-isomers in the rare earth region of A∼180 were observed, including the K=35/2 isomer in 179W. Several new isomeric decays in the very neutron rich systems, such as 190W, have been identified. In addition, in the course of this work, a number of neutron rich rare earth isotopes have also been synthesised and identified for the first time.