The matter radius of the doubly magic ^56 Ni was extracted from a measurement of the differential cross section by employing, for the first time, elastic proton scattering in inverse kinematics with a radioactive beam at E_kin=390.2 MeV/nucleon circulating in a storage ring and passing an internal hydrogen gas-jet target with a revolution frequency of around 2 MHz. The novel experimental scheme is based on UHV-compatible Si detectors operated as active vacuum windows, which were implemented in the ESR storage ring at GSI. A matter radius ^1/2=3.74^+0.03_-0.06 fm was extracted for the doubly-magic self-conjugate nucleus ^56 Ni.

In the present study, B(E2; 2+1 → 0+1 ) values have been measured in the Rn and Po nuclei through Coulomb excitation of re-accelerated radioactive beams in inverse kinematics at CERNISOLDE. These nuclei have been proposed to lie in, or at the boundary of the region where the seniority scheme should persist. However, contributions from collective excitations are likely to be present when moving away from the N = 126 closed shell. Such an effect is confirmed by the observed increased collectivity of the 2+1 → 0+1 transitions. Experimental results have been interpreted with the aid of theoretical studies carried out within the BCS-based QRPA framework.

The \(\beta\) decay of the N = 83 nucleus 131Cd has been studied at the RIBF facility at the RIKEN Nishina Center. The main purpose of the study was to identify the position of the \(1p_{3/2}\) and \(0f_{5/2}\) proton-hole states and the energies of core-excited configurations in the semi-magic nucleus 131In. From the radiation emitted following the \(\beta\) decay, a level scheme of 131In was established and the \(\beta\) feeding to each excited state determined. Similarities between the single-particle transitions observed in the \(\beta\) decays of the N = 83 isotones 132In and 131Cd are discussed. Finally the excitation energies of several core-excited configurations in 131In are compared to QRPA and shell-model calculations.

In the present study, \(B(E2; 2^{+}_{1}\rightarrow 0^{+}_{1})\) values have been measured in the 208,210Rn and 206Po nuclei through Coulomb excitation of re-accelerated radioactive beams in inverse kinematics at CERN-ISOLDE. These nuclei have been proposed to lie in, or at the boundary of the region where the seniority scheme should persist. However, contributions from collective excitations are likely to be present when moving away from the N=126 closed shell. Such an effect is confirmed by the observed increased collectivity of the \(2^{+}_{1}\rightarrow 0^{+}_{1}\) transitions. Experimental results have been interpreted with the aid of theoretical studies carried out within the BCS-based QRPA framework.

The electromagnetic structure of 140 Sm was studied in a low-energy Coulomb excitation experiment with a radioactive ion beam from the REX-ISOLDE facility at CERN. The 2 + and 4 + states of the ground-state band and a second 2 + state were populated by multistep excitation. The analysis of the differential Coulomb excitation cross sections yielded reduced transition probabilities between all observed states and the spectroscopic quadrupole moment for the 2 + 1 state. The experimental results are compared to large-scale shell model calculations and beyond-mean-field calculations based on the Gogny D1S interaction with a five-dimensional collective Hamiltonian formalism. Simpler geometric and algebraic models are also employed to interpret the experimental data. The results indicate that 140 Sm shows considerable γ softness, but in contrast to earlier speculation no signs of shape coexistence at low excitation energy. This work sheds more light on the onset of deformation and collectivity in this mass region.

For the first time, the γ decay of excited states has been observed in a nucleus situated in the quadrant south-east of doubly magic Sn132, a region in which experimental information so far is limited to ground-state properties. Six γ rays with energies of 50, 86, 103, 227, 357, and 602 keV were observed following the β-delayed neutron emission from Cd85133, populated in the projectile fission of a U238 beam at the Radioactive Isotope Beam Factory at RIKEN within the EURICA project. The new experimental information is compared to the results of a modern realistic shell-model calculation, the first one in this region very far from stability, focusing in particular on the π0g9/2-1 - ν1f7/2 particle-hole multiplet in In83132. In addition, theoretical estimates based on a scaling of the two-body matrix elements for the πh11/2-1 - νg9/2 analog multiplet in Tl127208, one major proton and one major neutron shell above, are presented. © 2016 American Physical Society.

We have measured the nuclear-matter distribution of the doubly-magic N = Z nucleus Ni-56 by investigating elastic proton scattering in inverse kinematics. The radioactive beam of Ni-56 was injected and stored in the experimental storage ring (ESR, GSI) and interacted with an internal hydrogen gas-jet target. The high revolution frequency of the ions in the ring enabled a high luminosity, despite the low density of the target being used. This way, measurements at very low momentum transfers became possible. By measuring the energy and the scattering angle of the recoiling protons, we were able to separate the elastic reaction channel from inelastic scattering to the first excited 2(+) state of Ni-56 and deduced the differential cross section of Ni-56 (p, p)(56) Ni. The data were analyzed within the framework of the Glauber multiple-scattering theory in order to extract the nuclear-matter radius and radial matter distribution of Ni-56. Parameterizing the matter distribution with the phenomenological Symmetrized Fermi distribution, a preliminary value of 3.5 fm for the rms matter radius was deduced. This experiment was part of an EXL (EXotic nuclei studied in Light-ion induced reactions at storage rings) campaign at GSI in 2012 and was the first successful investigation of nuclear reactions with a stored radioactive beam ever.

All material supplied via JYX is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form. You must obtain permission for any other use. Electronic or print copies may not be offered, whether for sale or otherwise to anyone who is not an authorised user. Recoil-decay tagging spectroscopy of 162 74 W 88 Li, H. J.; Cederwall, B.; Bäck, T.; Qi, C.; Doncel, M.; Jakobsson, Ulrika; Auranen, Kalle; Bönig, S.; Drummond, M. C.; Grahn, Tuomas; Greenlees, Paul; Herzan, Andrej; Julin, Rauno; Juutinen, Sakari; Konki, Joonas; Kröll, T.; Leino, Matti; McPeake, C.; O'Donnell, D.; Page, R. D.; Pakarinen, Janne; Partanen, Jari; Peura, Pauli; Rahkila, Panu; Ruotsalainen, Panu; Sandzelius, Mikael; Sarén, Jan; Saygı, B.; Scholey, Catherine; Sorri, Juha; Stolze, Sanna; Taylor, M. J.; Thornthwaite, A.; Uusitalo, Juha; Xiao, Z. G.

The investigation of light-ion induced direct reactions using stored and cooled radioactive beams, interacting with internal targets of storage rings, can lead to substantial advantages over external target experiments, in particular for direct reaction experiments in inverse kinematics at very low momentum transfer, q. This new and challenging experimental technique enables high-resolution measurements down to very low q and provides a gain in luminosity from accumulation and recirculation of the stored beams. For performing first experiments of this kind a dedicated experimental setup housing several DSSD (Double-sided Silicon Strip Detector) and Si(Li) detectors for recoil particles, well suited for meeting the demanding UHV (Ultra High Vacuum) conditions of a storage ring, was recently designed, constructed and installed at the internal target of the ESR storage ring at GSI. From the interaction of a stored 56Ni beam with an internal H2 target, good quality differential cross section data for elastic proton scattering, measured with the aim to determine the radial shape of the nuclear matter distribution of 56Ni, were obtained. Preliminary results are presented. Being the first reaction experiment ever performed with a stored radioactive beam on a world-wide scale, this experiment can be considered as a breakthrough for nuclear structure and astrophysics studies, and, in addition, as a successful proof-of-principle of the new experimental concept. In addition, preliminary results from a feasibility study on inelastic α-scattering from 58Ni in inverse kinematics, where it was demonstrated that the Isoscalar Giant Monopole Resonance in 58Ni can be investigated by the present technique down to CM angles below 1 degree, are discussed. Such an experiment, performed in the future with the doubly magic 56Ni, would provide important information on the EOS of nuclear matter.

All material supplied via JYX is protected by copyright and other intellectual property rights, and duplication or sale of all or part of any of the repository collections is not permitted, except that material may be duplicated by you for your research use or educational purposes in electronic or print form. You must obtain permission for any other use. Electronic or print copies may not be offered, whether for sale or otherwise to anyone who is not an authorised user. First identification of rotational band structures in Re-166(75)91 Li, H. J.; Doncel, M.; Patial, M.; Cederwall, B.; Bäck, T.; Jakobsson, Ulrika; Auranen, Kalle; Bönig, S.; Drummond, M.; Grahn, Tuomas; Greenlees, Paul; Herzan, Andrej; Joss, D. T.; Julin, Rauno; Juutinen, Sakari; Konki, Joonas; Kröll, T.; Leino, Matti; McPeake, C.; O'Donnell, D.; Page, R. D.; Pakarinen, Janne; Partanen, Jari; Peura, Pauli; Rahkila, Panu; Ruotsalainen, Panu; Sandzelius, Mikael; Sarén, Jan; Saygı, B.; Scholey, Catherine; Sorri, Juha; Stolze, Sanna; Taylor, M. J.; Thornthwaite, A.; Uusitalo, Juha; Xiao, Z. G.

Picosecond lifetimes of excited states in neutron-rich Xe isotopes were measured at the Institut Laue- Langevin via $\gamma$-ray spectroscopy of fission fragments from neutron-induced fission of 235U and 241Pu targets. The data collected with the recently installed fast timing array FATIMA in combination with the EXOGAM Ge array were analysed using the new generalized centroid difference method. Our aim is to study the quadrupole and octupole collectivity, arising in the mass region beyond the doubly magic 132Sn, by means of transition probabilities. These can be calculated from the directly measured lifetimes.

Electromagnetic transition strengths and spectroscopic quadrupole moments for Sm-140 were measured by means of multi-step Coulomb excitation with radioactive beam at the ISOLDE facility at CERN. A complementary experiment was performed at the Heavy Ion Laboratory in Warsaw to assign spins for non-yrast states using the angular correlation technique. Based on the new experimental data previous spin assignments need to be revised.

In the first campaign of the exotic nuclei studied with light-ion induced reaction in storage rings (EXL) collaboration at the existing storage ring experimental heavy-ion storage ring (ESR) at Helmholtz Center for Heavy Ion Research (GSI), we performed the first experiments using a stored beam of Ni-58 and an internal helium gas-jet target aiming for the investigation of isoscalar giant resonances in inverse kinematics. In this experiment, inelastically scattered recoil particles (at very forward angles, theta(cm) <= 1 degrees) were detected with a dedicated setup, including ultra-high vacuum (UHV)-compatible double-sided silicon strip detector (DSSDs). Preliminary results show evidence for the excitation of the isoscalar giant monopole resonance (ISGMR) in the Ni-58 nucleus. This opens the opportunity to study in the near future giant resonances also with stored radioactive beams, like Ni-56, and extract important information about the nuclear matter incompressibility. In the present work the current status of the data analysis and results are shown and discussed.

A low-lying state in 131In82, the one-proton hole nucleus with respect to double magic 132Sn, was observed by its γ decay to the Iπ=1/2- β-emitting isomer. We identify the new state at an excitation energy of Ex=1353  keV, which was populated both in the β decay of 131Cd83 and after β-delayed neutron emission from 132Cd84, as the previously unknown πp3/2 single-hole state with respect to the 132Sn core. Exploiting this crucial new experimental information, shell-model calculations were performed to study the structure of experimentally inaccessible N=82 isotones below 132Sn. The results evidence a surprising absence of proton subshell closures along the chain of N=82 isotones. The consequences of this finding for the evolution of the N=82 shell gap along the r-process path are discussed.

The ISOLTRAP mass spectrometer is dedicated to determining nuclear binding energies and Q values by the Penning-trap technique. The experiments concerned by the present report have been directed at a wide range of physics subjects, of which the study of nuclear shell effects far from stability, the onset of nuclear collectivity and the modeling of astrophysical environments/processes stand out. A decisive strength of the setup is its flexibility under online conditions, allowing for efficient use of on-line beam time in the case of difficulties with allocated beams. To overcome the increasingly difficult task of coping with short-lived, highlycontaminated ion beams, a series of on-line and off-line technical developments have taken place at ISOLTRAP, which, in their turn, open the path to new experimental opportunities. Experiments and remaining shifts: The ISOLTRAP experiment has at present 12 active experiments or approved proposals, as summarized in the table below: