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The future Super-FRS separator-spectrometer at FAIR will provide rare-isotope beams for key experiments in nuclear structure, astrophysics and nuclear reactions. The Super-FRS will use large-aperture magnets, which is important for the acceptance of nuclear reaction products with a large transverse and longitudinal emittance. In the standard ion-optical separator mode, magnetic rigidity analysis in combination with atomic energy-loss will be performed for clean isotopic spatial separation, once in the Pre-Separator and second in the Main-Separator. New ion-optical developments, prepared for different categories of experiments, are presented in this article. The operating modes described in the early publications of the project are updated in the first part of the paper. In the second part, special ion-optical modes mainly for the experiments of the Super-FRS Experiment Collaboration are discussed. This collaboration is the succession of the FRS Collaboration which has concentrated on separator-spectrometer experiments with the present facility at GSI since 1990. [ABSTRACT FROM AUTHOR]

The possible existence of η′-nucleus bound states has been put forward through theoretical and experimental studies. It is strongly related to the η′ mass at finite density, which is expected to be reduced because of the interplay between the U(1) anomaly and partial restoration of chiral symmetry. The investigation of the C( p, d) reaction at GSI and FAIR, as well as an overview of the experimental program at GSI and future plans at FAIR are discussed. [ABSTRACT FROM AUTHOR]

Abstract: The Super-FRS in-flight fragment separator at FAIR will be used to produce exotic nuclei at relativistic energies. High resolution experiments in ion traps with the separated fragments will be performed after they are slowed-down in matter and quickly extracted from a gas-filled stopping cell. Such experiments require an effective range bunching with a high-resolution magnetic spectrometer in combination with a wedge-shaped degrader at the dispersive focal plane. The ion-optical system of the spectrometer proposed here is rather versatile because it consists of several dipole and quadrupole magnets arranged such to serve as an energy-buncher and also as a large-acceptance spectrometer for the analysis of secondary reaction products. The performance and the experimental potential of such a multi-purpose spectrometer are described. [Copyright &y& Elsevier]

One-neutron knockout reactions have been studied in a systematic way for a set of neutron-rich projectiles. The goal of the experiment, performed at GSI, was to explore the evolution of the nuclear structure close to the neutron drip line, in the region between C and Al. The momentum distributions of the surviving fragments and the cross-sections of the knockout process have been measured and used as physical observables. This report focuses on oxygen and nitrogen isotopes around N = 14. In particular, we discuss the case of 22N, for which the mentioned observables have been determined for the first time. We will consider 23O, already studied in earlier experiments, as a reference. [ABSTRACT FROM AUTHOR]

The projectile fragmentation of a 92 Mo beam onto a beryllium target at an incident energy of 500 A MeV has been studied at the high-resolution spectrometer FRS at GSI. The isotopic production cross-sections of the projectile fragments produced in the reaction have been determined. The data have been compared to the empirical parameterisation, EPAX, and to a microscopic nuclear reaction model, ABRABLA. [ABSTRACT FROM AUTHOR]

The very neutron-deficient isotope 50Ni was produced in fragmentation reactions between a 650 A MeV 58Ni beam and a 9Be target. For the first time the decay of this nucleus was investigated, leading to the determination of the half-life as 12+3 -2 ms and the branching ratio for β-delayed proton emission of (70 ± 20)%. [ABSTRACT FROM AUTHOR]

The conceptual design of a next-generation cryogenic stopping cell (CSC) for the Low-Energy Branch (LEB) of the Super-FRS has been developed. It builds on advanced techniques implemented in the prototype version of the CSC, which has recently been commissioned as part of the FRS Ion Catcher with 238 U projectile and fission fragments produced at 1000 MeV/u. These techniques include cryogenic operation to ensure a high purity of the stopping gas and high-density operation enabled using an RF carpet with a small electrode structure size. The next generation CSC implements several novel concepts (e.g. perpendicular extraction) which lead to enhanced performance compared to the prototype CSC: (i) extremely short extraction times, (ii) higher rate capability, (iii) increased areal density without deteriorating extraction times, efficiencies or rate capability, (iv) minimized RF power, (v) precise range measurement of the ions and (vii) improved cleanliness of the CSC. [ABSTRACT FROM AUTHOR]

Abstract: Using the high-resolution performance of the fragment separator FRS at GSI we have discovered 60 new neutron-rich isotopes in the atomic number range of . The new isotopes were unambiguously identified in reactions with a beam impinging on a Be target at 1 GeV/nucleon. The production cross-section for the new isotopes have been measured down to the pico-barn level and compared with predictions of different model calculations. For elements above hafnium fragmentation is the dominant reaction mechanism which creates the new isotopes, whereas fission plays a dominant role for the production of the new isotopes up to thulium. [Copyright &y& Elsevier]

Abstract: MOCADI, the Monte-Carlo code for tracking of ions in ion-optical systems with non-Liouvillian elements, has been extended. Accurate atomic and nuclear interactions are taken into account when ions penetrate gaseous and solid matter placed within the ion-optical system. The new features of MOCADI are described in this article with practical examples which demonstrate the new possibilities, such as new event-generators for targets and spontaneous nuclear decay, the option of atomic-charge state fluctuation in matter, loops for multi-turn ion-optical systems and a graphical user interface for easier operating and control of the program. Experiments for investigation of nuclear structure and reactions with ions circulating in a storage ring can now be ideally studied with MOCADI. [Copyright &y& Elsevier]

Abstract A thick neutron skin emerges from the first determination of root mean square radii of the proton distributions for 17−22N from charge changing cross section measurements around 900 A MeV at GSI. Neutron halo effects are signalled for 22N from an increase in the proton and matter radii. The radii suggest an unconventional shell gap at N = 14 arising from the attractive proton–neutron tensor interaction, in good agreement with shell model calculations. Ab initio , in-medium similarity re-normalization group, calculations with a state-of-the-art chiral nucleon–nucleon and three-nucleon interaction reproduce well the data approaching the neutron drip-line isotopes but are challenged in explaining the complete isotopic trend of the radii. [ABSTRACT FROM AUTHOR]

A new technique developed for measuring nuclear reactions at low momentum transfer with stored beams in inverse kinematics was successfully used to study isoscalar giant resonances. The experiment was carried out at the experimental heavy-ion storage ring (ESR) at the GSI facility using a stored 58 Ni beam at 100 MeV/u and an internal helium gas-jet target. In these measurements, inelastically scattered α -recoils at very forward center-of-mass angles ( θ cm ≤ 1.5 ° ) were detected with a dedicated setup, including ultra-high vacuum compatible detectors. Experimental results indicate a dominant contribution of the isoscalar giant monopole resonance at this very forward angular range. It was found that the monopole contribution exhausts 79 − 11 + 12 % of the energy-weighted sum rule (EWSR), which agrees with measurements performed in normal kinematics. This opens up the opportunity to investigate the giant resonances in a large domain of unstable and exotic nuclei in the near future. It is a fundamental milestone towards new nuclear reaction studies with stored ion beams. [ABSTRACT FROM AUTHOR]

Abstract: We report on a new experimental setup for the investigation of proton induced reactions on exotic nuclei in inverse kinematics. It was installed and successfully used in the scattering study of intermediate-energy protons () on neutron-rich nuclei 6,8He produced with the FRagment Separator (FRS) at the GSI facility, Darmstadt. A new pure liquid-hydrogen target was successfully adapted allowing to obtain low-background data as compared to commonly used (CH2) n targets. Absolute differential cross-sections for elastic (p,6,8He) scattering were obtained at angles corresponding to (GeV/c)2 of the four-momentum transfer squared (−t) leading to the first diffraction minimum and spanning more than two orders of magnitude. They complement an earlier measurement at smaller angles (GeV/c)2 performed at the same energy with an active target. Both data sets agree well in the overlap region (GeV/c)2 and enable a refined and comparative study of the radial distribution of the nuclear matter density. [Copyright &y& Elsevier]

One-neutron knockout data for 18-22N are analyzed in the eikonal approximation of the Glauber model. The role of the s-d shell and the crossing of the N = 14 neutron subshell are discussed. Of particular interest is the nucleus 22N, where the knockout data provide a sensitive experimental test for a possible halo structure of its ground state. The observation of a narrow momentum distribution of the 21N fragments, together with an essential 1s1/2 contribution needed to describe the observed longitudinal-momentum distribution, allow the firm conclusion that the ground state of 22N is a well-developed nuclear halo. The results also show that the N = 14 subshell in 22N is somewhat reduced as compared to that of 23O. [ABSTRACT FROM AUTHOR]

Abstract: The unbound nuclei 9He and 10He have been produced in proton-knockout reactions from a 280 MeV/u 11Li beam impinging on a liquid hydrogen target at the ALADIN-LAND setup at GSI. Information on their nuclear structure has been obtained from the relative-energy spectra, and , employing reaction models incorporating the structure of 11Li. The relative-energy spectrum is dominated by a strong peak-like structure at low energy, which may be interpreted within the effective-range approximation as the result of an s-wave interaction with a neutron scattering length of . This spectrum also shows evidence for resonance states at and at 2.4 MeV above the threshold. It is argued that the s-state might not be the 9He ground state. For , the analysis of the relative-energy spectrum gives two alternative possibilities for an interpretation: either a narrow resonance at () superimposed on a correlated background, or two overlapping resonances, a ground state at 1.54(11) MeV () together with an excited state at 3.99(26) MeV (). The two possible interpretations are discussed. [Copyright &y& Elsevier]

Abstract: One-neutron knockout reactions of 24–28Ne in a beryllium target have been studied in the Fragment Separator (FRS), at GSI. The results include inclusive one-neutron knockout cross-sections as well as longitudinal-momentum distributions of the knockout fragments. The ground-state structure of the neutron-rich neon isotopes was obtained from an analysis of the measured momentum distributions. The results indicate that the two heaviest isotopes, 27Ne and 28Ne, are dominated by a configuration in which a neutron is coupled to an excited state of the 26Ne and 27Ne core, respectively. [Copyright &y& Elsevier]

Abstract: The first reaction spectroscopy on the ground state structure of 33Mg through the measurement of the longitudinal momentum distribution from the one-neutron removal reaction using a C target at is reported. The experiment was performed at the FRS, GSI. The distribution has a relatively narrow width ( (FWHM)) and the one-neutron removal cross-section is . An increased contribution from the orbital is required to explain the observation showing its lowering compared to existing model predictions. This provides new information regarding the configuration of 33Mg and the island of inversion. [Copyright &y& Elsevier]

Abstract: The unbound nucleus 7He, produced in neutron-knockout reactions with a 240 MeV/u 8He beam in a liquid-hydrogen target, has been studied in an experiment at the ALADIN-LAND setup at GSI. From an R-matrix analysis the resonance parameters for 7He as well as the spectroscopic factor for the 6He(0+)+n configuration in its ground-state have been obtained. The spectroscopic factor is 0.61 confirming that 7He is not a pure single-particle state. An analysis of 5He data from neutron-knockout reactions of 6He in a carbon target reveals the presence of an s-wave component at low energies in the relative energy spectrum. A possible low-lying exited state in 7He observed in neutron knockout data from 8He in a carbon target and tentatively interpreted as a state, could not be observed in the present experiment. Possible explanations of the shape difference between the 7He resonance obtained in the two knockout reactions are discussed in terms of target-dependence or different reaction mechanisms at relativistic energies. [Copyright &y& Elsevier]

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]

Abstract: The production cross-sections of proton-rich protactinium and thorium isotopes have been investigated for the fragmentation of 1 A GeV 238U in a beryllium target at the SIS/FRS facility at GSI Darmstadt. The experimental results are compared with the predictions of an abrasion–ablation model of nuclear fragmentation yielding good overall agreement. Weak evidence for first observation of the new isotopes 208Th and 211Pa is presented. [Copyright &y& Elsevier]

A new approach to the production of low energy radioactive beams involves the stopping of fast beams produced by fragmentation, in-flight fission or fusion–evaporation reaction into a large gas catcher where the reaction products are thermalized in high-purity helium and extracted as singly charged ions for post-acceleration. This removes the limitation present in standard ISOL technique for species that are difficult to extract from the target/ion source assembly. This approach has been implemented at Argonne since 1998 to inject fusion–evaporation products in an ion trap system. Via a series of improvements since then, we now reach efficiencies for these devices of close to 50% with delay times below 10 ms. In preparation for the RIA project, a larger device for stopping fragmentation products is in preparation. The basic principles behind these devices together with results obtained and experience gained operating these devices will be presented. Preparation for a test of the large gas cell at the full RIA energy at GSI will also be presented. [Copyright &y& Elsevier]

Dissociation of a 227 MeV/u 8He beam in a lead target has been studied in a kinematically complete experiment. The results are compared with similar data from the well-known halo nucleus 6He. Coulomb–nuclear interference in the inelastic channel gives evidence for a Iπ=1− resonance in 8He at Ex=4.15 MeV. The deduced B(E1) value of 0.38±0.07 e2fm2 indicates a uniform distribution of the four neutrons around the α-particle core. [Copyright &y& Elsevier]

The proton-removal mechanism of the 12C → 11 B reaction induced on a carbon target via elementary nucleon-nucleon scattering is investigated in exclusive triple-coincidence measurements. The observed two-nucleon angular correlations are found to be consistent with quasi-free scattering of a projectile-like proton off a target-like nucleon. Exclusive cross sections for one-step pp and pn interactions are determined as σ p p = 17.2 (12) mb and σ p n = 18.2 (18) , respectively. The extracted quasi-free component amounts up to 58(4)% of the total proton-removal cross section. The results are compared to total proton-removal cross sections obtained from the experiment and eikonal reaction theory. [ABSTRACT FROM AUTHOR]