Beusch, A.

Hartmann, Willi

Hübner, A.

Kindler, B.

Lommel, B.

Steiner, J.

Yakusheva, V.

GSI Repository

GSITemplate2007 50Ti for a High-Intensity Heavy-Ion Beam  Bettina Lommell, Andreas Beusch1, Willi Hartmann1, Annett Hübner1, Birgit Kindler1,Jutta Steiner1, Vera Yakusheva2,11GSI, Darmstadt, Germany; 2 Helmholtz-Institut Mainz, 55099 Mainz, Germany The semi-magic 50Ti has a closed neutron shell with N = 28 and is the most neutron rich of the stable Ti-isotopes. This makes the isotope especially interesting as a beam projectile for heavy-element synthesis. For the production of a high intensity ion beam over long time periods, the metallic form of the enriched isotope is preferable for both, ECR and PIG ion sources. Highly enriched 50Ti is delivered either as the dioxide or as the tetrachloride. The task was to establish a process to reduce the compound to the metal with a high efficien-cy and a high chemical purity. Process For the reduction process we preferred the solid TiO2 to the liquid TiCl4 since handling gaseous TiCl4 at higher temperatures needed for the reduction process involves a higher risk of losing material. For the TiO2 there are in principle two common routes for reducing it to the metal either with metallic Ca or with CaH2 as reducing agent [1]. Since for the affectivity of the reduction the purity of the Ca is crucial we decided to use the CaH2 in the pro-cess. The Ca vapours are generated within the mixture via thermal decomposition of the hydride and can react im-mediately with the adjacent TiO2. The process chosen [2] is described by the following chemical equation:  TiO2 + 2 CaH2  Ti + 2 CaO + 2 H2                 (1) For the reduction we prepared a mixture of the two components in an agate mortar with a 40% access of CaH2 to the stoichiometric composition described by the reaction equation (1) and pressed to tablets with a hydrau-lic press. The tablets are heated in a molybdenum boat inside a stainless steel tube at 950°C for an hour in a con-stant flow of dry argon. After the reduction the tablets now containing Ti-metal, CaO and rest of Ca are cooled down to room temperature, dissolved in diluted acetic acid; then the precipitate is washed and dried, obtaining a fine powder of metallic Ti. Analysis At first the setup and the process were tested with dif-ferent batches of natural TiO2 where a yield of 95 % was achieved. For the application in the ion sources ten differ-ent batches of 50TiO2 from three different producers were reduced. The starting material obviously differed in col-our, in grain size and in softness leading to quite different behaviour by pressing tablets for the reduction and by melting metallic Ti, as well as a significantly variation in yield during reduction.  To get an understanding of the impurities in the starting material and their behaviour during the reduction process, energy-dispersive x-ray analysis (EDX) of all batches before and after the reduction was applied. In the natural material no impurities were detectable before the reduc-tion, after the reduction a Ca-content of ~ 0.3 – 0.6 % was observed. Several batches of the enriched 50TiO2 showed no impurities before and only the expected amount of calcium after the reduction. But a number of batches had impurities of Cl, Si or Sn or a combination of those. All impurities were in in the range of 1.5 % up to 5 %. The Cl vanished completely after the reduction, whereas the Si and the Sn stayed in the same amount. The different impurities caused different behaviour in the further processing especially by melting tablet of Ti powder to beads.  Results With the new setup we are able convert between 0.5 g up to several grams of highly enriched 50Ti in one run with yields between 90 % and 98 %. Different impurities in the starting material influence the melting behaviour and therefore the final yield significantly. We obtain en-riched metallic titanium for application in the ion source or as a starting material for target production. The reduced material was used at UNILAC for production of 50Ti-beam with intensities of about 1 particleμA at a target for experiments which lasted several month in 2011 and 2012 [3,4,5]. References [1] Handbuch der präparativen anorganischen Chemie (ed. G. Brauer) Ferdinand Enke Verlag, Stuttgart 1978, vol. 2 [2] W. Freundlich, M. Bichara,  Comptes rendus hebdo-madaires des séances de l'Académie des sciences / publiés par MM. les secrétaires perpétuels T238 (1954) p. 1324.  [3] K. Tinschert et al., this report. [4] R. Hollinger, this report. [5] B. Lommel, A. Beusch, W. Hartmann, A. Hübner, B. Kindler, J. Steiner, V. Yakusheva, J. Radioanal. Nucl. Chem. to be published.PHN-ENNA-EXP-14 GSI SCIENTIFIC REPORT 2012144 FAIR@GSI

$^{50}$Ti for a High-Intensity Heavy-Ion Beam

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$^{50}$ Ti for a High-Intensity Heavy-Ion Beam

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50^{50}50Ti for a High-Intensity Heavy-Ion Beam

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$^{50}$ Ti for a High-Intensity Heavy-Ion Beam