Studies of release properties of ISOLDE targets

Perajärvi, K.; Bergmann, U. C.; Fedoseyev, V. N.; Joinet, A.; Köster, U.; Lau, C.; Lettry, J.; Ravn, H. L.; Santana-Leitner, M.

doi:10.1016/s0168-583x(02)01924-9

Cited by 8 publications

(3 citation statements)

References 17 publications

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“…This provides desorption times in the 0.5-4.0 ms range. When folding this with an estimated number of interactions with a foil target (100 000) or with the structural material (500), this provides an overall effusion delay time of the order of 0.25-400 s for TIS temperatures up to 1300°C, well in the range to account for the slow release properties and reduced efficiencies for exotic isotopes as shown in figure 9 and table 4 [73].…”

Section: Isotopementioning

confidence: 99%

Production of negatively charged radioactive ion beams

2017

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Beams of short-lived radioactive nuclei are needed for frontier experimental research in nuclear structure, reactions, and astrophysics. Negatively charged radioactive ion beams have unique advantages and allow for the use of a tandem accelerator for post-acceleration, which can provide the highest beam quality and continuously variable energies. Negative ion beams can be obtained with high intensity and some unique beam purification techniques based on differences in electronegativity and chemical reactivity can be used to provide beams with high purity. This article describes the production of negative radioactive ion beams at the former holifield radioactive ion beam facility at Oak Ridge National Laboratory and at the CERN ISOLDE facility with emphasis on the development of the negative ion sources employed at these two facilities.

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Section: Isotopementioning

confidence: 99%

Production of negatively charged radioactive ion beams

2017

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“…A "MK7" ISOLDE type FEBIAD ion source [18] connected via a water-cooled transfer line gave pure beams of Kr, reported in [19]. Also He, Ne and Ar beams were observed (see Fig.…”

Section: Release and Yields At Isoldementioning

confidence: 99%

“…Release and yields of Mn isotopes from a ZrO 2 felt target, ionized with the resonance ionization laser ion source (RILIS) [21] are discussed in [19].…”

Section: Release and Yields At Isoldementioning

confidence: 99%

Oxide fiber targets at ISOLDE

Köster

Bergmann

Carminati

et al. 2003

Nuclear Instruments and Methods in Physics Research Section B:

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Many elements are rapidly released from oxide matrices. Some oxide powder targets show a fast sintering, thus losing their favorable release characteristics. Loosely packed oxide fiber targets are less critical since they may maintain their open structure even when starting to fuse together at some contact points. The experience with various oxide fiber targets (titania, zirconia, ceria and thoria) used in the last years at ISOLDE is reviewed. For short-lived isotopes of Cu, Ga and Xe the zirconia and ceria targets respectively provided significantly higher yields than any other target (metal foils, oxide powders, etc.) tested before. Titania fibers, which were not commercially available, were produced in a relic process by impregnation of a rayon felt in a titanium chloride solution and subsequent calcination by heating the dried felt in air. Thoria fibers were obtained either by the same process or by burning commercial gas lantern mantle cloth. In the future a beryllia fiber target could be used to produce very intense 6 He beams (order of 10 13 ions per s) via the 9 Be(n,α) reaction using spallation neutrons.(Submitted to Nuclear Instruments and Methods in Physics Research B) Introduction A great variety of materials is used as ISOL (isotope separation on-line) targets (see e.g. [1]): molten metals, solid metals (as foils or powder), carbides, oxides and other compounds. Here we will discuss recent on-line results (release parameters and yields) of ISOLDE oxide targets and, in particular, of oxide fiber targets.Oxide targets have a long history at ISOL facilities. Already in the very first ISOL experiment [2] a 10 kg UO 2 target was used. Then, in the first experiments at ISOLDE several oxide targets served to produce radioactive noble gas isotopes [3,4]. These oxides (TiO 2 , ZrO 2 , CeO 2 and ThO 2 ) were precipitated out of solutions, vacuum-dried at room temperature and ground to powder. The targets were only partly dehydrated when operated at room temperature and had average delay times (for Kr and Xe) of 17 − 110 s [5].Later, other oxides were used at higher temperatures, after having been dehydrated by slowly heating them off-line under vacuum. All these oxides were used in form of powder or as pills of pressed powder: BeO, MgO, Al 2 O 3 , CaO, SrO, BaO, La 2 O 3 , ThO 2 and UO 2 . However, a powder target has a large number of mutual contact points between the individual grains. When heated for longer time to high temperature, the grains can "bake together" at these contact points and the formerly fine-grained powder will sinter to a bigger block with consequently longer diffusion paths and slower release. This was observed in particular for thoria and urania powder targets. Here it would be preferable to use instead thin fibers, which are arranged as a loose "pile of spaghetti". They have less mutual contact points and provide a better mechanical stability even when sintering starts locally at the contact points.Felts and cloths made from fibers of ZrO 2 and other oxides are commercially av...

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