First experimental results of a cryogenic stopping cell with short-lived, heavy uranium fragments produced at 1000 MeV/u

Purushothaman, S.; Reiter, M. P.; Haettner, E.; Dendooven, P.; Dickel, T.; Geißel, H.; Ebert, Jens; Jesch, C.; Plaß, W. R.; Ranjan, M.; Weick, H.; Amjad, F.; Ayet, S.; Diwisch, M.; Estradé, A.; Farinon, F.; Greiner, Florian; Kalantar‐Nayestanaki, N.; Knöbel, R.; Kurcewicz, J.; Lang, Johannes; Moore, I. D.; Mukha, I.; Nociforo, C.; Petrick, Martin; Pfützner, M.; Piétri, S.; Procházka, A.; Rink, Ann-Kathrin; Rinta‐Antila, S.; Scheidenberger, C.; Takechi, M.; Tanaka, Y. K.; Winfield, J. S.; Yavor, M.I.

doi:10.1209/0295-5075/104/42001

Cited by 45 publications

(30 citation statements)

References 29 publications

(35 reference statements)

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“…During off-line commissioning, electric fields of up to 12.6 V/ cm were applied for helium pressures around 100 mbar at 83 K. The updated DC cage was operated during the on-line experiments with a DC field of up to 27.5 V/cm. For a helium pressure of 49 mbar and a temperature of 74 K (representing an areal density of 3.1 mg/cm 2 ), and a DC field of 22.2 V/cm, the mean extraction time of 221 Ac fragmentation products was measured to be 23.9 ms [18]. This value agrees well with the value of 27.5 ms expected from mobility theory calculated as in Section 3.2.…”

Section: Fieldsupporting

confidence: 82%

“…The first results of the on-line performance of the stopping cell at the FRS Ion Catcher Facility (which is discussed by Plaß et al [17]) are reported by Purushothaman et al [18]. First mass measurements of very short-lived isotopes extracted from the stopping cell and injected into a multiple-reflection time-offlight mass spectrometer [19][20][21] will be reported elsewhere.…”

Section: Nuclear Instruments and Methods Inmentioning

confidence: 99%

“…Results of off-line and on-line commissioning of the cryogenic stopping cell have been published earlier [16][17][18]. Here we focus on the cooling system performance in realistic on-line conditions.…”

Section: Performance Of the Cooling Systemmentioning

confidence: 99%

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

Ranjan

Dendooven

Purushothaman

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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a b s t r a c tA cryogenic stopping cell for stopping energetic radioactive ions and extracting them as a low energy beam was developed. This first ever cryogenically operated stopping cell serves as prototype device for the Low-Energy Branch of the Super-FRS at FAIR. The cell has a stopping volume that is 1 m long and 25 cm in diameter. Ions are guided by a DC field along the length of the stopping cell and by a combined RF and DC fields provided by an RF carpet at the exit-hole side. The ultra-high purity of the stopping gas required for optimum ion survival is reached by cryogenic operation. The design considerations and construction of the cryogenic stopping cell, as well as some performance characteristics, are described in detail. Special attention is given to the cryogenic aspects in the design and construction of the stopping cell and the cryocooler-based cooling system. The cooling system allows the operation of the stopping cell at any desired temperature between about 70 K and room temperature. The cooling system performance in realistic on-line conditions at the FRS Ion Catcher Facility at GSI is discussed. A temperature of 110 K at which efficient ion survival was observed is obtained after 10 h of cooling. A minimum temperature of the stopping gas of 72 K was reached. The expertise gained from the design, construction and performance of the prototype cryogenic stopping cell has allowed the development of a final version for the Low-Energy Branch of the Super-FRS to proceed.

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Section: Fieldsupporting

confidence: 82%

Section: Nuclear Instruments and Methods Inmentioning

confidence: 99%

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

Ranjan

Dendooven

Purushothaman

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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“…This operating mode has the best performance for spatial isotopic separation in-flight and is also preferable for experiments with the combination with the ESR. However, there are experiment classes where an efficient energy compression has priority because the separated exotic nuclides must be completely stopped (thermalized) in a helium-filled (5 mg/cm 2 ) cryogenic (70-100 K) stopping cell (CSC) [24], i.e., the normally large range straggling of the fragments due to their velocity spread must be strongly reduced with a so-called mono-energetic degrader [25]. A mono-energetic degrader has a special shape which matches the optical dispersion of the FRS in such a way that the energy loss is larger for the faster ions so that the energy of all ions after penetration is the same all over the dispersive plane.…”

Section: Experiments With Energy Compression a Lateral-dispersive Spmentioning

confidence: 99%

“…The complete particle identification with the FRS has been provided by time-of-flight (SCI), position (TPC) and energy-deposition (IC) measurements at the focal planes F2 and F4. The selected fragment beam is completely stopped and thermalized in the cryogenic gas cell (CSC) [24]. The energy compression is performed with a mono-energetic degrader system (MD) placed at the central dispersive focal plane of the FRS.…”

Section: Experiments With Energy Compression a Lateral-dispersive Spmentioning

confidence: 99%

The Challenge of High-Resolution Spectrometer Experiments with Exotic Nuclei

et al. 2015

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Exotic atomic nuclei are short-lived species and are characterized by extreme proton-to-neutron ratios. These nuclei are created in stellar reactions and are keys to understand the abundance of the elements in the universe [1]. Exotic nuclei have quite different properties compared to the well-known species close to the valley of beta stability. This observation makes them essential for the basic understanding of nuclear matter. Nowadays, these rare isotopes can also be produced with modern powerful accelerator facilities at several laboratories worldwide [2] which solve the problems of the inherent small production cross section sections via high primary beam intensities and high energies [3,4]. However, the successful production of exotic nuclei is only the first necessary step, the separation from the primary beam and from the abundant contaminants and the measurements of their properties are of equal importance [5]. Spectrometer BasicsHigh resolution experiments with energetic heavy ions can in principle be performed in-flight with lateral-dispersive and longitudinal-dispersive electromagnetic spectrometers. Lateral-dispersive systems analyze with magnetic and electric dipole fields and apply multipole fields for focusing and correction of image aberrations [6,7]. A typical lateral-dispersive spectrometer stage, such as it is used in many accelerator based heavy ion laboratories, is shown schematically in Figure 1. A lens system is used at the entrance of a dipole magnet and a second one is placed behind to determine the focal plane conditions. The physical quantity of interest is the momentum resolving power which is mainly determined by the entrance emittance of the ion beam to be analyzed and the illuminated area in the dispersive plane of the dipole magnet. Electric fields can also be applied at low energies (at and below the Coulomb barrier) instead of magnets, but the same statements on the resolving power hold in this case as well. In longitudinal dispersive devices such as ion storage rings [8] and multiplereflection time-of-flight mass spectrometers (MR-TOF-MS) [9,10] the challenge is to achieve isochronous conditions with negligible aberrations of the higher-order optics. In general, one can achieve a higher resolving power with the longitudinal-dispersive, multi-path devices compared to the lateraldispersive spectrometers. The latter spectrometers may be applied as in-flight separators for nuclear reaction products and usually consist of a combination of several dispersive stages. The advantage of these spectrometers is the superior spatial isotopic separation of rare isotopes from the intense primary beam and the abundant contaminants. Space-charge problems are of minor importance for such lateral-dispersive spectrometers. They can have an overall maximum momentum resolving power (p/p) of several 10 4 [11,12], whereas storage rings and MR-TOF-MS systems can achieve more than 50 times higher resolving powers. In lateral spectrometers, the spatial deflections and resolving power are measured by po...

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Development of a low-energy radioactive ion beam facility for the MARA separator

et al. 2016

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A low-energy radioactive ion beam facility for the production and study of nuclei produced close to the proton drip line is under development at the Accelerator Laboratory of the University of Jyväskylä, Finland. The facility will take advantage of the mass selectivity of the recently commissioned MARA vacuum-mode mass separator. The ions selected by MARA will be stopped and thermalised in a smallvolume gas cell prior to extraction and further mass separation. The gas cell design allows for resonance laser ionisation/spectroscopy both in-gas-cell and in-gas-jet. The facility will include experimental setups allowing ion counting, mass measurement and decay spectroscopy.

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First experimental results of a cryogenic stopping cell with short-lived, heavy uranium fragments produced at 1000 MeV/u

Cited by 45 publications

References 29 publications

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

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

The Challenge of High-Resolution Spectrometer Experiments with Exotic Nuclei

Development of a low-energy radioactive ion beam facility for the MARA separator

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