112 research outputs found
Isochronous Mode of the Future Collector Ring At the Centre for Heavy Ion Research, Darmstadt, Germany
Short-lived exotic nuclei can be produced and separated with the high-energy nuclear beam facility called fragment separator at the Centre for Heavy Ion Research. These nuclides can be injected and stored in the storage ring called experimental storage ring. The lower lifetime limit of the presently existing methods for mass measurements on these nuclides at the experimental storage ring is about a few seconds. We have developed and investigated an isochronous operational mode of the future collector ring, that makes mass measurements feasible for nuclides with lifetimes down to a few microseconds. A mass resolving power of about 150 000 is expected
Spectroscopy of eta'-nucleus bound states at GSI-SIS
The eta' meson mass may be reduced due to partial restoration of chiral
symmetry. If this is the case, an eta'-nucleus system may form a nuclear bound
state. We plan to carry out a missing-mass spectroscopy with the 12C(p,d)
reaction at GSI-SIS. Peak structures corresponding to such a bound state may be
observed even in an inclusive measurement, if the decay width is narrow enough.Comment: 4 pages, 2 figures, to appear in the proceedings of MESON2012 (12th
International Workshop on Meson Production, Properties and Interaction),
Krakow, Polan
Feasibility Study of Observing eta' Mesic Nuclei with (p,d) Reaction
A novel method is proposed to measure eta'(958) meson bound states in 11C
nuclei by missing mass spectroscopy of the 12C(p,d) reaction near the eta'
production threshold. It is shown that peak structures will be observed
experimentally in an inclusive measurement in case that the in-medium eta' mass
reduction is sufficiently large and that the decay width of eta' mesic states
is narrow enough. Such a measurement will be feasible with the intense proton
beam supplied by the SIS synchrotron at GSI combined with the good energy
resolution of the fragment separator FRS.Comment: 12 pages, 6 figures, accepted for publication in Progress of
Theoretical Physic
First Measurement of the Ru(p,)Rh Cross Section for the p-Process with a Storage Ring
This work presents a direct measurement of the Ru()Rh cross section via a novel technique using a storage ring,
which opens opportunities for reaction measurements on unstable nuclei. A
proof-of-principle experiment was performed at the storage ring ESR at GSI in
Darmstadt, where circulating Ru ions interacted repeatedly with a
hydrogen target. The Ru()Rh cross section between 9
and 11 MeV has been determined using two independent normalization methods. As
key ingredients in Hauser-Feshbach calculations, the -ray strength
function as well as the level density model can be pinned down with the
measured () cross section. Furthermore, the proton optical potential
can be optimized after the uncertainties from the -ray strength
function and the level density have been removed. As a result, a constrained
Ru()Rh reaction rate over a wide temperature range is
recommended for -process network calculations.Comment: 10 pages, 7 figs, Accepted for publication at PR
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
Xe primary beam are presented. Suppression of molecular contaminants by
three orders of magnitude has been demonstrated. Essentially background-free
measurement conditions with less than of background events within a
mass-to-charge range of 25 u/e have been achieved. The technique can also be
used to reduce the space-charge effects at the extraction nozzle and in the
downstream beamline, thus ensuring high efficiency of ion transport and
highly-accurate measurements under space-charge-free conditions.Comment: 8 pages, 4 figure
Measurements of proton-induced reactions on ruthenium-96 in the ESR at GSI
8th International Conference on Nuclear Physics at Storage Rings Stori11, October 9-14, 2011 Laboratori Nazionale di Frascati, Italy.
Storage rings offer the possibility of measuring proton- and alpha-induced reactions in inverse kinematics. The combination of this approachwith a radioactive beamfacility allows, in principle, the determination of the respective cross sections for radioactive isotopes. Such data are highly desired for a better understanding of astrophysical nucleosynthesis processes like the p-process. A pioneering experiment has been performed at the Experimental Storage Ring (ESR) at GSI using a stable 96Ru beam at 9-11 AMeV and a hydrogen target. Monte-Carlo simulations of the experiment were made using the Geant4 code. In these simulations, the experimental setup is described in detail and all reaction channels can be investigated. Based on the Geant4 simulations, a prediction of the shape of different spectral components can be performed. A comparison of simulated predictions with the experimental results shows a good agreement and allows the extraction of the cross section
Coulomb dissociation of N 20,21
Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N20,21 are reported. Relativistic N20,21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the N19(n,γ)N20 and N20(n,γ)N21 excitation functions and thermonuclear reaction rates have been determined. The N19(n,γ)N20 rate is up to a factor of 5 higher at
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 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.Peer reviewe
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