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A complex, long-range experimental program for the production of neutron-rich nuclei via multi-nucleon transfer (MNT) reactions and spontaneous fission (SF) inside the Cryogenic Stopping Cell (CSC) of the FRS Ion Catcher facility at GSI has been suggested and is under development. A key component is a new experimental set-up, consisting of a modified DC cage, a target-wheel, a beam-dump and a space charge suppression system. This setup replaces the standard electrode structure of the CSC, enabling generation of radioactive isotope beams by in-cell MNT reactions inside the CSC and the efficient and fast extraction of ions produced by MNT reactions or spontaneous fission. Furthermore, the system allows to do experiments with beams from the FRS with much higher rates and shorter half-lives. We present the specifications, design and production of this device. We also present the technical solution adopted against the space charge effect and the simulations that validate it. [ABSTRACT FROM AUTHOR]

The novel technique of mean range bunching has been developed and applied at the projectile fragment separator FRS at GSI in four experiments of the FAIR phase-0 experimental program. Using a variable degrader system at the final focal plane of the FRS, the ranges of the different nuclides can be aligned, allowing to efficiently implant a large number of different nuclides simultaneously in a gas-filled stopping cell or an implantation detector. Stopping and studying a cocktail beam overcomes the present limitations of stopped-beam experiments. The conceptual idea of mean range bunching is described and illustrated using simulations. In a single setting of the FRS, 37 different nuclides were stopped in the cryogenic stopping cell and were measured in a single setting broadband mass measurement with the multiple-reflection time-of-flight mass spectrometer of the FRS Ion Catcher. [ABSTRACT FROM AUTHOR]

The access to exotic nuclei at radioactive ion beam facilities is crucial for the state of the art research across several fields of physics such as in nuclear structure, the understanding of fundamental interactions and nuclear astrophysics. The particle identification is of high importance, besides the challenging production of these rare and short-lived nuclei. At in-flight facilities, the particle identification is based on measuring the time-of-flight, energy-deposition and magnetic rigidity. These quantities are calibrated to convert them into A/Q and Z of the ions. To ensure a correct calibration, the unambiguous identification, also called tagging, of one species is necessary. Here, we present a novel tagging method by high-resolution mass measurements using an MR-TOF-MS after thermalization of the ions in a cryogenic stopping cell. The method was successfully established and tested at the fragment separator FRS at GSI with the FRS Ion Catcher in experiments using different FRS operation modes. [ABSTRACT FROM AUTHOR]

Long-lived isomeric states in 97Ag and 101−109In were investigated with the FRS Ion Catcher at GSI. In the isotope 97Ag, a long-lived (1 / 2 −) isomeric state was discovered, and its excitation energy was determined to be 618(38) keV. This is simultaneously the first discovery of a nuclear isomeric state by multiple-reflection time-of-flight mass spectrometry. The measured excitation energies were compared to large-scale shell-model calculations, which indicated the importance of core excitation around 100Sn. Furthermore, advanced mean-field calculations for the 97Ag nucleus and relevant neighboring nuclei were performed, which have contributed to a better understanding of the repetitive appearance of certain isomeric structures in neighboring nuclei, and which have supported the discovery of the isomeric state in 97Ag in a global shell-evolution scheme. [ABSTRACT FROM AUTHOR]

A Laser Ablation Carbon Cluster Ion source (LACCI) has been developed and commissioned at the FRS Ion Catcher at GSI. It is the first laser ablation ion source for long-term measurements with a multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS). This is enabled by two key developments: (i) a two-dimensional movable target platform that ensures the long-term stable production of ions and (ii) a mass filter for the isolation of the ions of interest. LACCI is capable of providing closely-spaced reference ions in the mass range up to ∼ 300 u for accurate mass measurements of exotic nuclei (relative mass uncertainty ∼ 1 0 − 8 ) and systematic studies of the mass uncertainties with the multiple-reflection time-of-flight mass spectrometer. Investigations of the laser energy and repetition rate and long-term measurements have been carried out with carbon targets (Sigradur®, Fullerene) and metallic targets (silver, gold, copper, tungsten, and erbium). In a test experiment, LACCI has delivered a stable ion current for more than 20 h at a laser repetition rate of 100 Hz, corresponding to an operation for one week at 10 Hz. It thus fully satisfies the requirements for long-term accurate mass measurements of exotic nuclei with an MR-TOF-MS. This enables the access of exotic ions, detected with rates as low as 0.1 per hour at the FRS Ion Catcher. [ABSTRACT FROM AUTHOR]

Direct mass measurements of neutron-deficient nuclides around the N = 50 shell closure below 100Sn were performed at the FRS Ion Catcher (FRS-IC) at GSI, Germany. The nuclei were produced by projectile fragmentation of 124Xe, 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 98Cd and 97Rh. A new Q EC = 5437 ± 67 keV was obtained for 98Cd, resulting in a summed Gamow-Teller (GT) strength for the five observed transitions (0 + ⟶ 1 +) as B (GT) = 2.94 − 0.28 + 0.32. Investigation of this result in state-of-the-art shell model approaches accounting for the first time experimentally observed spectrum of GT transitions points to a perfect agreement for N = 50 isotones. The excitation energy of the long-lived isomeric state in 94Rh was determined for the first time to be 293 ± 21 keV. This, together with the shell model calculations, allows the level ordering in 94Rh to be understood. [ABSTRACT FROM AUTHOR]

Due to technical constraints this article was published in volume 240:1 with erroneous article citation ID number 3 whereas this should have been 73 which is corrected as such. Springer Nature sincerely apologizes towards the author(s) for the inconvenience caused. [ABSTRACT FROM AUTHOR]

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 storage of mother and daughter nuclides 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). We utilized our method to record the decay and growth of the 216Po and 212Pb isotopes (alpha decay) and of the 119m2Sb isomer ( t 1 / 2 = 850 ± 90 ms) and 119gSb isotope (isomer transition), obtaining half-lives consistent with literature values. The amount of non-nuclear-decay losses in the CSC up to ∼ 10 s is negligible, which exhibits its extraordinary cleanliness. For 119Sb isotopes, we present the first direct measurements of the mass of its ground state, and the excitation energy and decay branching ratios of its second isomeric state (119m2Sb). This resolves discrepancies in previous excitation energy data, and is the first direct evidence that the 119m2Sb isomer decays dominantly via γ emission. These results pave the way for the measurement of branching ratios of exotic nuclei. [ABSTRACT FROM AUTHOR]

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 time-of-flight mass spectrometer (MR-TOF-MS) at mass resolving powers of up to 410,000, with production cross sections down to the microbarn-level, and at rates down to a few ions per hour. The versatility of the MR-TOF-MS for isomer research has been demonstrated by the measurement of various isomers, determination of excitation energies and the production of a pure isomeric beam. Recently, several instrumental upgrades have been implemented at the FRS Ion Catcher. New experiments will be carried out during FAIR Phase-0 at GSI, including direct mass measurements of neutron-deficient nuclides below 100Sn and neutron-rich nuclides below 208Pb, measurement of β-delayed neutron emission probabilities and reaction studies with multi-nucleon transfer. [ABSTRACT FROM AUTHOR]