Masses of uranium fission fragments have been measured with the FRagment Separator (FRS) combined with the Experimental Storage Ring (ESR) at GSI. A 410-415 MeV/u 238U projectile beam was fast extracted from the synchrotron SIS-18 with an average intensity of 109/spill. The projectiles were focused on a 1g/cm2 beryllium target at the entrance of the FRS to create neutron-rich isotopes via abrasion-fission. The fission fragments were spatially separated with the FRS and injected into the isochronous storage ring ESR for fast mass measurements without applying cooling. The Isochronous Mass Spectrometry (IMS) was performed under two different experimental conditions, with and without B \(\rho\)-tagging at the high-resolution dispersive central focal plane of the FRS. The evaluation has been done for the combined data sets from both experiments with a new method of data analysis. The use of a correlation matrix has provided experimental mass values for 23 different neutron-rich isotopes for the first time and 6 masses with improved values. The new masses were obtained for nuclides in the element range from Se to Ce. The applied analysis has given access even to rare isotopes detected with an intensity of a few atoms per week. The novel data analysis and systematic error determination are described and the results are compared with extrapolations of experimental values and theoretical models.

The magnetic field stability of the collector ring dipole magnets has been studied with driving current ripple phenomena. The current ripple and corresponding magnetic field variation can be a cause of the beam orbit instability. We investigate the magnetic field variation due to the current ripple in the frequency range of 10 Hz to 10 kHz. The amplitude of magnetic field variation has the exponential decay with respect to the increasing current ripple frequency. This result explains the effect of the secondary magnetic field in the beam chamber. Although the dipole field variation is reduced, the higher odd-number multipoles by eddy current are not compensated. The multipole profiles depend on the beam chamber shape. We present the field stability simulation results including the secondary field harmonics with the vacuum beam chamber geometry.

M. Diwisch1, R. Kn̈obel1,2, H. Geissel 1,2, Yu. A. Litvinov2, Z. Patyk3, W. R. Pla߆1,2, C. Scheidenberger 1,2, B. Sun2,4, H. Weick2, F. Bosch2, D. Boutin2, L. Chen1,2, C. Dimopoulou2, A. Dolinskii2, B. Franczak2, B. Franzke2, M. Hausmann 5, C. Kozhuharov 2, J. Kurcewicz2, S. A. Litvinov2, G. Martinez-Pinedo 2,6, M. Matoš2, M. Mazzocco 2, G. Münzenberg 2, S. Nakajima7, C. Nociforo2, F. Nolden2, T. Ohtsubo8, A. Ozawa9, J. Stadlmann 2, M. Steck2, T. Suzuki 7, P. M. Walker10, M.-R. Wu6, M. Winkler2, and T. Yamaguchi 7

A 410 MeV/u 238U projectile beam was used to create cadmium isotopes via abrasion-fission in a beryllium target placed at the entrance of the in-flight separator FRS at GSI. The fission fragments were separated by the FRS and injected into the isochronous storage ring ESR for mass measurements. Isochronous Mass Spectrometry (IMS) was performed under two different experimental conditions, with and without Bρ-tagging at the high-resolution central focal plane of the FRS. In the experiment with Bρ-tagging the magnetic rigidity of the injected fragments was determined with an accuracy of 2⋅10−4. A new method of data analysis, which uses a correlation matrix for the combined data set from both experiments, has provided experimental mass values of 25 rare isotopes for the first time. The high sensitivity and selectivity of the method have given access to nuclides detected with a rate of a few atoms per week. In this letter we present for the 129,130,131Cd isotopes mass values directly measured for the first time. The experimental mass values of cadmium as well as for tellurium and tin isotopes show a pronounced shell effect towards and at N=82. Shell quenching cannot be deduced from a single new mass value, nor by a better agreement with a theoretical model which explicitly takes into account a quenching feature. This is in agreement with the conclusion from γ-ray spectroscopy and confirms modern shell-model calculations.

In 2012 the CRYRING storage ring was delivered from Stockholm to Darmstadt as a part of the Swedish in-kind contribution to the FAIR project. The ring lattice has been slightly changed for optimal injection and to provide additional space for experiment equipment. For the injection from the experimental storage ring (ESR), a new transfer line has been designed. The local injector line has been significantly modified compared to the previous one in Stockholm taking into account the geometry of the existing GSI building. In this paper we present the ion-optical properties of CRYRING@ESR after the described modifications. Single-turn injection from the ESR and multi-turn injection from the local injector are discussed. Ion-optical calculations of fast and slow extraction from CRYRING are also presented. The closed orbit correction scheme is considered taking into account the future arrangement of the beam position monitors and correction magnets. Based on the results of the calculations the requirements for the magnet alignment are finally discussed.

In this paper the time domain algorithm is described. The beam dynamics under influence of stochastic cooling forces is studied by a particle-by-particle and turn-by-turn treatment in the time-domain. This treatment escapes the involvement of complicated, changing frequency spectra, which anyhow are likely to be incomplete by considering the Fokker-Planck equation and its solution. Using the proposed method, a special computer code has been developed to calculate beam cooling in the time domain within reasonable computing time.

A ^238U projectile beam was used to create cadmium isotopes via abrasion-fission at 410 MeV/u in a beryllium target at the entrance of the in-flight separator FRS at GSI. The fission fragments were separated with the FRS and injected into the isochronous storage ring ESR for mass measurements. The Isochronous Mass Spectrometry (IMS) was performed under two different experimental conditions, with and without Bρ-tagging at the dispersive central focal plane of the FRS. In the experiment with Bρ-tagging the magnetic rigidity of the injected fragments was determined by an accuracy of 2× 10^-4. A new method of data analysis, using a correlation matrix for the combined data set from both experiments, has provided mass values for 25 different isotopes for the first time. The high selectivity and sensitivity of the experiment and analysis has given access even to rare isotopes detected with a few atoms per week. In this letter we present for the ^129,130,131Cd isotopes mass values directly measured for the first time. The Cd results clearly show a very pronounced shell effect at N=82 which is in agreement with the conclusion from γ-ray spectroscopy of ^130Cd and confirms the assumptions of modern shell-model calculations.

In order to understand how the heavy elements from iron to uranium were produced in nature, masses and lifetimes of extremely exotic nuclei up to the limits of nuclear existence have to be measured. In particular, for modeling the r-process nucleosynthesis the nuclei close to the neutron drip line are relevant. However, such nuclei typically have very short half-lives and furthermore have tiny production cross-sections. The Super-FRS-CR facility at FAIR [1] offers unique possibilities for such measurements. Exotic nuclei with half-lives of T-1/2 > 20 mu s will be produced and selected in flight with the Super-FRS fragment separator [2], injected and stored in the large acceptance collector ring (CR) [3] which will be tuned into the isochronous ion-optical mode and operated as a time-of-flight (TOF) spectrometer. We demonstrate here, a comparison between the achromatic and non-achromatic isochronous optics. The importance of the TOF detectors installation in the dispersion free region will be shown.

The collector ring is a dedicated ring for fast cooling of ions coming from separators at the FAIR project. To accommodate optimal technical solutions, a structure of a magnet lattice was recently reviewed and modified. Consequently, more appropriate technical solutions for the main magnets could be adopted. A general layout and design of the present machine is shown. The demanding extraction schemes have been detailed and open design issues were completed.

Facility for Antiproton and Ion Research (FAIR), will offer unprecedented experimental opportunities. The Stored Particles Atomic Research Collaboration (SPARC) at FAIR aims at creating a worldwide unique research program with highly charged ions by utilizing storage ring and trapping facilities. The foreseen experiments will address physics at strong, ultra-short electromagnetic fields including the fundamental interactions between electrons and heavy nuclei as well as the experiments at the border between nuclear and atomic physics. In view of the staged construction of the FAIR facility, SPARC worked out an early realization scheme for experiments with highly-charged heavy-ions at relativistic energies to be conducted in the High-Energy Storage Ring.

The large acceptance Collector Ring at FAIR is designed to provide a stochastic pre-cooling of either antiprotons (Pbar) or Rare Isotopic Beams (RIB) injected in the ring. In addition, for mass measurement of exotic short-lived nuclides, the CR will be tuned in the special isochronous ion-optical setting, in which it will be used as a Time-Of-Flight (TOF) spectrometer. In order to reach necessary time resolution, the octupole corrector magnets will be installed in the CR. The nonlinear field imperfections of the magnets and fringing fields of the wide aperture quadrupole magnets excite high-order chromatic aberrations, which lead to the beam losses. This is especially important for the large momentum acceptance antiproton and RIB ion-optical modes. To improve the dynamic aperture and to reach necessary time resolution for TOF sextupole and octupole corrections are planned to be applied in the ring.

The CR is a dedicated ring for cooling of hot beams coming either from the antiproton separator or Super-FRS [1]. It is anticipated that the understanding and control of the beam orbits will be important for achieving low beam losses. We describe our plans for measuring and correcting the Closed Orbit Distortion (COD) of the CR. The COD of the CR, which is distorted due to magnet misalignments, can reduce the ring acceptance by factor of 2, if a special correction system is not applied. The system, which is developed for the CR should be periodically or manually invoked to correct the global closed orbit and used to adjust the orbit position at some point using local bump. The Beam Position Monitor (BPM) and corrector magnet, which are planned to be used at the CR, are described in this paper. The numerical calculations based on the Singular Value Decomposition (SVD) algorithm have been performed in order to define possible COD without and with applying of a planned correction system. The SVD method is used to obtain the corrector strength.

A challenge for nuclear physics is to measure masses of exotic nuclei up to the limits of nuclear existence which are characterized by low production cross-sections and short half-lives. The large acceptance Collector Ring (CR) [1] at FAIR [2] tuned in the isochronous ion-optical mode offers unique possibilities for measuring short-lived and very exotic nuclides. However, in a ring designed for maximal acceptance, many factors limit the resolution. One point is a limit in time resolution inversely proportional to the transverse emittance. But most of the time aberrations can be corrected and others become small for large number of turns. We show the relations of the time correction to the corresponding transverse focusing and that the main correction for large emittance corresponds directly to the chromaticity correction for transverse focusing of the beam. With the help of Monte-Carlo simulations for the full acceptance we demonstrate how to correct the revolution times so that in principle resolutions of Δm/m=10−6 can be achieved. In these calculations the influence of magnet inhomogeneities and extended fringe fields are considered and a calibration scheme also for ions with different mass-to-charge ratio is presented.

A new method is proposed to determine half-lives and branching ratios of β -delayed neutron emitters, especially those beyond N=126 that are relevant for the r-process.The existing storage ring ESR or the future ring CR at GSI would be employed to store and cool the mother nuclei.The decay half-life and the neutron emission probability could be deduced from the detection of the mother and decay daughter ions with Schottky pick-ups and a particle detector in contrast to the standard method via detection of β -delayed neutrons.This method could be complementary and has the advantage to be independent of the neutron detection efficiency.As candidates for a proof-of-principle tests we suggest the nuclei 211 Hg, 212 Hg, 210 Tl, and 213 Tl which have been investigated in a recent experiment by traditional detection methods.

Today the challenge is to measure masses of exotic nuclei up to the limits of nuclear existence which are characterized by low production cross-sections and short halflives. The large acceptance Collector Ring (CR) [1] at FAIR [2] tuned in the isochronous ion-optical mode offers unique possibilities for such measurements. Nonlinear field errors as well as fringe fields of the wide aperture quadrupolesand dipoles strongly excite the high-order aberrations which negatively affect the time resolution of the isochronous ring. Their influence is investigated here and a possible correction scheme is shown.

In the modularized start version of the FAIR project, the New Experimental Storage Ring is not included and therefore the task of the stochastic cooling system at the Collector Ring (CR) is now focused on the 3 GeV antiproton beam. On the other hand, recently the SPARC collaboration has proposed to perform the high energy atomic physics experiments in the HESR ring with stable ions, typically a U beam, employing an internal target. Furthermore the future possibility of the nuclear physics experiments with rare isotope beams (RIBs), typically a Sn beam, in the HESR is envisaged. In the present report, the beam dynamics, mainly the longitudinal motion from the fragment separator SuperFRS to the end of beam cooling in the CR are described emphasizing the process of stochastic cooling of the rare isotope beam.