Separation of atomic and molecular ions by ion mobility with an RF carpet

Gas-filled stopping cells are used at accelerator laboratories for the thermalization of high-energy radioactive ion beams. Common challenges of many stopping cells are a high molecular background of extracted ions and limitations of extraction efficiency due to space-charge effects. At the FRS Ion Catcher at GSI, a new technique for removal of ionized molecules prior to their extraction out of the stopping cell has been developed. This technique utilizes the RF carpet for the separation of atomic ions from molecular contaminant ions through their difference in ion mobility. Results from the successful implementation and test during an experiment with a 600~MeV/u $^{124}$Xe primary beam are…

Rate capability of a cryogenic stopping cell for uranium projectile fragments produced at 1000 MeV/u

At the Low-Energy Branch (LEB) of the Super-FRS at FAIR, projectile and fission fragments will be produced at relativistic energies, separated in-flight, energy-bunched, slowed down and thermalized in a cryogenic stopping cell (CSC) filled with ultra-pure He gas. The fragments are extracted from the stopping cell using a combination of DC and RF electric fields and gas flow. A prototype CSC for the LEB has been developed and successfully commissioned at the FRS Ion Catcher at GSI. Ionization of He buffer gas atoms during the stopping of energetic ions creates a region of high space charge in the stopping cell. The space charge decreases the extraction efficiency of stopping cells since the …

From Neo-Functional Peace to a Logic of Spillover in EU External Policy: A Response to Visoka and Doyle

In their recently published JCMS article, Gezim Visoka and John Doyle have proposed the concept of ‘neofunctional peace’ as a means to conceptualize the EU's peacemaking practices in the case of the EU-facilitated Belgrade-Pristina dialogue. This article challenges the ‘neo-functional peace’ on conceptual and empirical grounds. We critically discuss Visoka and Doyle's (2016) reading of neofunctionalism and question parts of their empirical evidence given for the existence of a ‘neo-functional peace’. Going beyond a mere critique of the article by Visoka and Doyle and arguing that the authors may not have fully exploited neofunctionalism's potential for theorizing EU external policy, we stip…

Motives, Roles, Effectiveness and the Future of the EU as an International Mediator

AbstractThis article concludes this special issue on the European Union as international mediator that set out to advance our theoretical and empirical knowledge aboutEUmediation. Providing a comprehensive reflection ofEUmediation activities and the diverse settings where they take place, this concluding article identifies some connection points between the articles and discusses their findings on the motives/drivers, roles/strategies, effectiveness and institutional capacities ofEUmediation. It discusses the implications of these findings for policymaking, focusing on the conditions forEUmediation effectiveness, the advantages of the multi-layered nature ofEUmediation and the need for flex…

Mediating International Conflicts: The European Union as an Effective Peacemaker?

This article examines how the EU's effectiveness as a mediator in peace negotiations can be appropriately conceptualized and analysed. Mediator effectiveness is analysed along two dimensions: goal-attainment and conflict settlement. Investigation of the conditions of mediator effectiveness is structured around four key sets of variables: mediator leverage, mediation strategy, coherence and the conflict's context. In our empirical analysis of EU mediation between Serbia and Kosovo (Belgrade–Pristina dialogue) we find that the medium degree of EU effectiveness (both in terms of goal-attainment and conflict settlement) can be explained by its great leverage vis-a-vis the conflict parties due t…

Dawning of the N=32 shell closure seen through precision mass measurements of neutron-rich titanium isotopes

A precision mass investigation of the neutron-rich titanium isotopes 51 − 55 Ti was performed at TRIUMF’s Ion Trap for Atomic and Nuclear science (TITAN). The range of the measurements covers the N = 32 shell closure, and the overall uncertainties of the 52 − 55 Ti mass values were significantly reduced. Our results conclusively establish the existence of the weak shell effect at N = 32 , narrowing down the abrupt onset of this shell closure. Our data were compared with state-of-the-art ab initio shell model calculations which, despite very successfully describing where the N = 32 shell gap is strong, overpredict its strength and extent in titanium and heavier isotones. These measurements a…

A Novel Method for the Measurement of Half-Lives and Decay Branching Ratios of Exotic Nuclei

A novel method for simultaneous measurement of masses, Q-values, isomer excitation energies, half-lives and decay branching ratios of exotic nuclei has been demonstrated. The method includes first use of a stopping cell as an ion trap, combining containment of precursors and decay-recoils for variable durations in a cryogenic stopping cell (CSC), and afterwards the identification and counting of them by a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). Feasibility has been established by recording the decay and growth of $^{216}$Po and $^{212}$Pb (alpha decay) and of $^{119m2}$Sb (t$_{1/2}$ = 850$\pm$90 ms) and $^{119g}$Sb (isomer transition), obtaining half-lives and bran…

Introduction: The EU as International Mediator – Theoretical and Empirical Perspectives

AbstractIn this introductory article of the special issue, we examine European Union (EU) mediation practice and identify different conceptual and empirical perspectives from which it can be analyzed. We present different understandings of mediation in research and practice a definition and conceptual clarification ofEUmediation practice, and offer a definition that covers mediation efforts and mediation support activities. Then, the institutional architecture forEUmediation activities is presented. Next, the focus of this special issue is examined and research questions that have not yet been sufficiently addressed in existing research ofEUforeign policy and mediation are discussed. Based …

Mass and half-life measurements of neutron-deficient iodine isotopes

The European physical journal / A 56(5), 143 (2020). doi:10.1140/epja/s10050-020-00153-5

Removal of molecular contamination in low-energy RIBs by the isolation-dissociation-isolation method

Nuclear instruments & methods in physics research / B 463, 324 - 326 (2020). doi:10.1016/j.nimb.2019.04.072

The science case of the FRS Ion Catcher for FAIR Phase-0

The FRS Ion Catcher at GSI enables precision experiments with thermalized projectile and fission fragments. At the same time it serves as a test facility for the Low-Energy Branch of the Super-FRS at FAIR. The FRS Ion Catcher has been commissioned and its performance has been characterized in five experiments with 238U and 124Xe projectile and fission fragments produced at energies in the range from 300 to 1000 MeV/u. High and almost element-independent efficiencies for the thermalization of short-lived nuclides produced at relativistic energies have been obtained. High-accuracy mass measurements of more than 30 projectile and fission fragments have been performed with a multiple-reflection…

The Middle East Peace Process and the EU: Foreign Policy and Security Strategy in International Politics, by T.Ö. Kaya (London: I.B. Tauris, 2013, ISBN 9781848859821); 304pp., £59.50 hb.

Mass measurements of As, Se, and Br nuclei, and their implication on the proton-neutron interaction strength toward the N=Z line

Mass measurements of the $^{69}$As, $^{70,71}$Se and $^{71}$Br isotopes, produced via fragmentation of a $^{124}$Xe primary beam at the FRS at GSI, have been performed with the multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) of the FRS Ion Catcher with an unprecedented mass resolving power of almost 1,000,000. For the $^{69}$As isotope, this is the first direct mass measurement. A mass uncertainty of 22 keV was achieved with only 10 events. For the $^{70}$Se isotope, a mass uncertainty of 2.6 keV was obtained, corresponding to a relative accuracy of $\delta$m/m = 4.0$\times 10^{-8}$, with less than 500 events. The masses of the $^{71}$Se and $^{71}$Br isotopes were measured…

High-resolution, accurate multiple-reflection time-of-flight mass spectrometry for short-lived, exotic nuclei of a few events in their ground and low-lying isomeric states

Physical review / C covering nuclear physics 99(6), 064313 (2019). doi:10.1103/PhysRevC.99.064313

Studying Gamow-Teller transitions and the assignment of isomeric and ground states at $N=50$

Direct mass measurements of neutron-deficient nuclides around the N=50 shell closure below $^{100}$Sn were performed at the FRS Ion Catcher (FRS-IC) at GSI, Germany. The nuclei were produced by projectile fragmentation of $^{124}$Xe, separated in the fragment separator FRS and delivered to the FRS-IC. The masses of 14 ground states and two isomers were measured with relative mass uncertainties down to 1×10−7 using the multiple-reflection time-of-flight mass spectrometer of the FRS-IC, including the first direct mass measurements of $^{98}$Cd and $^{97}$Rh. A new QEC=5437±67 keV was obtained for $^{98}$Cd, resulting in a summed Gamow-Teller (GT) strength for the five observed transitions (0+…