Design, construction and cooling system performance of a prototype cryogenic stopping cell for the Super-FRS at FAIR

Ranjan, M.; Dendooven, P.; Purushothaman, S.; Dickel, T.; Reiter, M. P.; Ayet, S.; Haettner, E.; Moore, I. D.; Kalantar‐Nayestanaki, N.; Geißel, H.; Plaß, W. R.; Schaefer, D. L.; Scheidenberger, C.; Schreuder, F.; Timersma, H. J.; Walle, J. Van de; Weick, H.

doi:10.1016/j.nima.2014.09.075

Cited by 39 publications

(26 citation statements)

References 42 publications

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“…In Fig. 2, a schematic view of the FRS-IC with its three main parts is shown: (i) the gas-filled cryogenic stopping cell (CSC) [29][30][31][32] for thermalization of the exotic nuclei produced at relativistic energies, (ii) a beamline, based on radio frequency quadrupoles (RFQ) [32][33][34][35] for mass-selective transport and differential pumping, equipped with detectors (channeltrons and silicon detectors) for ion counting and α-decay spectroscopy and with ion sources for diagnostic purposes, and (iii) the MR-TOF-MS [14,36,37] for several purposes, such as diagnostics of the upstream beamline, ion identification and counting, and direct mass measurements.…”

Section: Methodsmentioning

confidence: 99%

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

Andrés¹,

Hornung²,

Ebert³

et al. 2019

Phys. Rev. C

121

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Mass measurements of fission and projectile fragments, produced via 238 U and 124 Xe primary beams, have been performed with the multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) of the Fragment Separator (FRS) Ion Catcher with a mass resolving power (FWHM) of up to 410 000 and an uncertainty of down to 6 × 10 −8. The nuclides were produced and separated in flight with the fragment separator FRS at 300 to 1000 MeV/u and thermalized in a cryogenic stopping cell. The data-analysis procedure was developed to determine with highest accuracy the mass values and the corresponding uncertainties for the most challenging conditions: down to a few events in a spectrum and overlapping distributions, which can be distinguished from a single peak only by a broader peak shape. With this procedure, the resolution of low-lying isomers is increased by a factor of up to 3 compared to standard data analysis. The ground-state masses of 31 short-lived nuclides of 15 different elements with half-lives of down to 17.9 ms and count rates as low as 11 events per nuclide were determined. This is the first direct mass measurement for seven nuclides. The excitation energies and the isomer-to-groundstate ratios of six isomeric states with excitation energies of as little as 280 keV were measured. For nuclides with known mass values, the average relative deviation from the literature values is (4.5 ± 5.3) × 10 −8. The measured two-neutron separation energies and their slopes near and at the N = 126 and Z = 82 shell closures indicate a strong element-dependent binding energy of the first neutron above the closed proton shell Z = 82. The experimental results deviate strongly from the theoretical predictions, especially for N = 126 and N = 127.

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Section: Methodsmentioning

confidence: 99%

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

Andrés¹,

Hornung²,

Ebert³

et al. 2019

Phys. Rev. C

121

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“…With the FRS-IC ( Fig. 1) these fragments are then slowed down and thermalized in a cryogenic stopping cell (CSC) [3]. A multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) is used to perform direct mass measurements and to provide an isobarically and isomerically clean beam for further experiments, such as mass-selected decay spectroscopy [4,5].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2019

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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 238 U and 124 Xe 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-offlight 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 100 Sn and neutronrich nuclides below 208 Pb, measurement of β-delayed neutron emission probabilities and reaction studies with multi-nucleon transfer.

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“…It usually utilizes rare isotopes from the FRS following in-flight fragmentation or fission of relativistic heavy ions. Thermalization is performed in a cryogenic stopping cell (CSC) [17][18][19]. The isotopes are then extracted, diagnosed and transported by a versatile RFQ beam-line [20].…”

Section: Description Of the Methodsmentioning

confidence: 99%

Determining spontaneous fission properties by direct mass measurements with the FRS Ion Catcher

et al. 2020

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We present a direct method to measure fission product yield distributions (FPY) and isomeric yield ratios (IYR) for spontaneous fission (SF) fragments. These physical properties are of utmost importance to the understanding of basic nuclear physics, the astrophysical rapid neutron capture process ('r process') of nucleosynthesis, neutron star composition, and nuclear reactor safety. With this method, fission fragments are produced by spontaneous fission from a source that is mounted in a cryogenic stopping cell (CSC), thermalized and stopped within it, and then extracted and transported to a multiple-reflection time-of-flight mass-spectrometer (MR-TOF-MS). We will implement the method at the FRS Ion Catcher (FRS-IC) at GSI (Germany), whose MR-TOF-MS relative mass accuracy (~ 10-7) and resolving power (~ 600,000 FWHM) are sufficient to separate all isobars and numerous isomers in the fission fragment realm. The system's essential element independence and its fast simultaneous mass measurement provide a new direct way to measure isotopic FPY distributions, which is complementary to existing methods. It will enable nuclide FPY measurements in the high fission peak, which is hardly accessible by current techniques. The extraction time of the CSC, tens of milliseconds, enables a direct measurement of independent fission yields, and a first study of the temporal dependence of FPY distributions in this duration range. The ability to resolve isomers will further enable direct extraction of numerous IYRs while performing the FPY measurements. The method has been recently demonstrated at the FRS-ICr for SF with a 37 kBq 252Cf fission source, where about 70 different fission fragments have been identified and counted. In the near future, it will be used for systematic studies of SF with a higher-activity 252Cf source and a 248Cm source. The method can be implemented also for neutron induced fission at appropriate facilities.

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Design, construction and cooling system performance of a prototype cryogenic stopping cell for the Super-FRS at FAIR

Cited by 39 publications

References 42 publications

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

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

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

Determining spontaneous fission properties by direct mass measurements with the FRS Ion Catcher

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