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.

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.

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.

The former storage ring CRYRING has been shipped from the Manne Siegbahn Laboratory in Stockholm to Darmstadt as a Swedish in-kind contribution to FAIR. At its new location downstream of ESR all ion species presently accessible in ESR can be transferred to CRYRING, in which ions with rigidities between 1.44 and 0.054 Tm can be stored. The original Swedish layout has been modified by reconfiguring the sequence of straight sections and by slightly increasing the circumference to ESR/2. Ions can be injected from ESR or from an independent 300 keV/u RFQ test injector. The instrumentation of the ring includes an RF drift tube system for acceleration and deceleration (1 T s(-1), with a possibility for an upgrade to 7 T s(-1)), electron cooling, a free experimental section, and both fast and slow extraction of ions. We report on the present progress of this project, give a prospective timeline, and summarize the new research which will be enabled by this project. First beam for commissioning of the storage ring is expected for 2015, final bakeout to restore ultrahigh vacuum conditions in 2016 and ion beams injected through ESR in similar to 2017.

At the FAIR facility for antiprotons and ion research, the high-energy storage ring will provide highly charged heavy ions with Z all the way to Z = 92 for beam energies ranging from 200 A MeV up to energies of approximately 5 A GeV. This opens up a wealth of opportunities for in-ring atomic physics experiments on few-body quantum dynamics ranging from, for example, the correlated dynamics of various e(+)-e(-) pair creation processes to quasi-photoionization of inner shells of the highest-Z ions.

Long-lived isomers in (212)Bi have been studied following (238)U projectile fragmentation at 670 MeV per nucleon. The fragmentation products were injected as highly charged ions into a storage ring, giving access to masses and half-lives. While the excitation energy of the first isomer of (212)Bi was confirmed, the second isomer was observed at 1478(30) keV, in contrast to the previously accepted value of >1910 keV. It was also found to have an extended Lorentz-corrected in-ring half-life >30 min, compared to 7.0(3) min for the neutral atom. Both the energy and half-life differences can be understood as being due a substantial, though previously unrecognized, internal decay branch for neutral atoms. Earlier shell-model calculations are now found to give good agreement with the isomer excitation energy. Furthermore, these and new calculations predict the existence of states at slightly higher energy that could facilitate isomer deexcitation studies.

The Swedish in-kind contribution to the FAIR facility in Darmstadt, the heavy-ion storage ring CRYRING, has been transported to Darmstadt recently. Instead of warehousing until installation at the Facility for Antiproton and Ion Research, FAIR, the immediate installation behind the existing Experimental Storage Ring, ESR, has been proposed. CRYRING can decelerate, cool and store heavy, highly charged ions that come from the ESR down to a few 100 keV/nucleon. It provides a high performance electron cooler in combination with a gas jet target and thus opens up a very attractive physics program as a natural extension of the ESR, which can only operate down to about 4 MeV/nucleon. CRYRING@ESR also provides beams of low charged ions independently on the GSI accelerator. All this makes CRYRING@ESR the perfect machine for FAIR related tests of diagnostics, software and concepts, and atomic physics experiments with heavy, highly charged ions stored at low energy. Perspectives are also opened up for low-energy nuclear physics investigations. CRYRING@ESR is a first step towards atomic physics with low-energy, highly charged ions at FAIR as planned within the SPARC and APPA collaborations.

At the FAIR facility for antiproton and ion research, the new ESR + CRYRING combination of storage rings CRYRING@ESR opens up a wealth of opportunities for in-ring atomic physics experiments on few-body quantum dynamics. The low-energy storage ring CRYRING will serve in its new location at FAIR/ESR for experiments with decelerated antiprotons and highly charged ions. We will discuss selected new experiments in the field of quantum dynamics of high-Z ions, for example for adiabatic superheavy quasi-molecules transiently formed with bare and H-like projectiles. Such experiments will be for the first time possible at the future CRYRING at ESR.

Masses of 238U projectile fragments have been measured with time-resolved Schottky Mass Spectrometry (SMS) at the FRS-ESR facility at GSI. The exotic nuclei were created in the production target at the entrance of the fragment separator FRS, spatially separated in flight and injected into the storage-cooler ring ESR at about 70% light velocity. This means the ions were mainly bare or carried only a few electrons, e.g., the population of Li-like ions was below 1% for Pt fragments. Accurate new mass values of 33 neutron-rich, stored exotic nuclei in the element range from platinum to uranium have been obtained for the first time. In total more than 150 nuclides including references with well-known masses have been covered in this large-area SMS measurement. A novel data analysis has been applied which reduces the systematic errors by taking into account the velocity profile of the cooler electrons and the residual ion-optical dispersion in this part of the storage ring. The experiment, the data analysis, and the mass values are presented. The experimental data are compared with theoretical predictions demonstrating systematic deviations of up to 1500 keV from modern mass models.

Absolute rate coefficients for dielectronic recombination (DR) of hydrogenlike U91+ have been measured at GSI's heavy-ion storage ring ESR in the center-of-mass energy range 63–90 keV. We find an excellent agreement between the measured DR rate coefficients and theoretical results from multi-configuration Dirac-Fock theory which includes the Breit interaction. The latter contributes nearly one half to the total resonance strengths of the KL1/2L1/2 and KL1/2M1/2 resonance groups.

Fast longitudinal beam accumulation has been demonstrated in the ESR at GSI with an Ar beam coming from the synchrotron SIS18 at 400 MeV/u. Continuous application of stochastic cooling in all three phase space directions merged the stack with the newly injected bunch. Longitudinal beam compression was achieved either by using short barrier bucket rf pulses or by successive injections onto the unstable fixed point of the rf bucket at h=1. This recent experiment in the ESR provides the proof of principle for the longitudinal stacking of antiprotons in the FAIR project. It is planned to accumulate pre-cooled antiprotons in the HESR, injected from the CR.

M. Jung, F. Bosch, K. Beckert, H. Eickhoff, H. Folger, B. Franzke, A. Gruber, P. Kienle, O. Klepper, W. Koenig, C. Kozhuharov, R. Mann, R. Moshamnler, F. Nolden, U. Schaaf, G. Soff, P. Spadtke, M. Steck, Th. Stohlker, and K. Summerer Gesellschaft fur Schwerionenforschung (GSl), D 6100 -Darmstadt, Germany (Received 20 July 1992) Bound-state P decay was observed for the first time by storing bare 'QDy + ions in a heavy-ion storage ring. From the number of 'QHo66+ daughter ions, measured as a function of the storage time, a half-life of 47-+4 d was derived. By comparing this result with reported half-lives for electron capture (EC) from the Ml and M2 shells of neutral '[jHo, bounds for both the QEc value of neutral ')/Ho and for the electron-neutrino mass were set.

The electron–ion scattering experiment ELISe is part of the installations envisaged at the new experimental storage ring at the International Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. It offers an unique opportunity to use electrons as probe in investigations of the structure of exotic nuclei. The conceptual design and the scientific challenges of ELISe are presented.