Adonin, A.

Berezov, R.

Brühl, M.

Gutermuth, B.

Heymach, F.

Hollinger, R.

Lang, R.

Maimone, J.

Mäder, J.

Ochs, K.

Pfister, J.

Roßbach, J.

Schäffer, P.

Schäffer, S.

Stork, S.

Tinschert, K.

Vierheller, C.

Wesp, A.

Zulauf, S.

GSI Repository

GSITemplate2007 Ion Source Operation at the  GSI Accelerator Facility R. Hollinger*, K. Tinschert*, J. Pfister*, A. Adonin, R. Berezov, M. Brühl, B. Gutermuth,                F. Heymach, R. Lang, J. Mäder, F. Maimone, K. Ochs, J. Roßbach, P. Schäffer, S. Schäffer,             M. Stork, C. Vierheller, A. Wesp, S. Zulauf GSI, Darmstadt, GermanyHigh Current Ion Sources In 2012 ion sources from Terminal North (MUCIS, CHORDIS, VARIS, MEVVA) and Terminal South (PIG ion sources) were supplying the GSI accelerator with various types of ions. The following Table 1 gives an overview of the ion species, which were delivered for physics and accelerator development experiments. A good representative value for delivered intensity to the linear accelerator UNILAC is the analysed current in the accelerator section UH1 in front of the RFQ.  Table 1: Ion beams generated with high current ion sources in 2012. Filament driven volume type ion sources: MUCIS and CHORDIS; Vacuum arc ion sources: VARIS and MEVVA; Penning type ion sources PIG Ion species Dura-tion (days) Ion source  Beam for experiment Analyzed intensity (emA) 6D3+ 6 MUCIS UNI 2-3 14N2+ 7 MUCIS SIS 4 12C2+ 7 PIG UNI 0.06…0.08 20Ne+ 7 PIG ESR 0.1 36Ar+ 6 CHORDIS SIS 8 40Ar2+ 14 PIG UNI 0.2…0.4 50Ti2+ 137 PIG UNI/ESR 0.04…0.07 58Ni2+ 20 VARIS SIS/ESR 5 84Kr2+ 9 MUCIS SIS 3-4 86Kr2+ 9 MUCIS SIS 4 136Xe3+ 15 MUCIS UNI/SIS 2 197Au4+ 39 VARIS UNI/SIS/ESR 3-6 197Au8+ 28 PIG UNI 0.06…0.1 208Pb4+ 11 VARIS UNI/SIS 6-8 208Pb8+ 10 PIG UNI/SIS 0.1 238U4+ 58 VARIS UNI/SIS/ESR 8-12  Ion beams generated in the high current sources can be distinguished into standard elements and non-standard, which are much more challenging to produce and the ion source being operated. In 2011 and especially in 2012 standard titanium-50 operation from the PIG source was established completely with more than one ion source exchange per day.  Another element, which was established in 2012 from the VARIS high current ion source, is the four-fold gold beam, which was not available from this kind of ion source before. The same approach as for 209Bi4+-ions [1] was taken and a proper mixture of elements was found. Same as for the gold beam production the creation of high current four-fold led beam from the VARIS was established upon experimentalists request. From Table 1 it can be deducted that the most re-quested ion beams in 2012 were titanium, gold and ura-nium. It is also shown that most time of the year both terminals were operated at the same time with mostly different ion species.   With a view to the super heavy element experiment TASCA with the need of high amounts of particles the possibility of production of the titanium-50 sputtering electrodes inside GSI was developed. Melting and ma-chining was done in the melting oven of the ion source department as well as the ion source mechanical work-shop. An average particle current of 0.75pµΑ at the experi-ment was reached with an uptime of the ion source of 95%. In front of the accelerator an ion beam of 50Ti2+ with an intensity of 40-70eµΑ was reached.  Refurbishment of the PIG sources started in spring of 2012. These sources have been in operation at GSI since the first days of the UNILAC. The goal of this action is a better performance of these high-duty-cycle ion sources. Furthermore it was finally possible to built up the new PIG service area, where the service of the source can be done under “cleanroom conditions”    For the establishment of the high current gold beam different mixtures of gold and other elements were checked in order to change the physical properties of the element and having the maximum of the charge state distribution in the four-fold peak. Admixtures of ele-ments like Pd, Cr, Zr, Ti and Ta were tested. Best results were reached with mixtures of 50% gold with 50% of chromium. The ion beam current of 197Au4+ in front of the RFQ was 6mA. On led beam the same procedure was undertaken as for gold and bismuth before and it was possible to provide for the first time ever an intensity of up to 8mA of 208Pb4+ was measured in front of the high current injector RFQ. High Charge State Injector HLI For the operation of the GSI accelerator the CAPRICE ECR ion source (ECRIS) at the High Charge State Injec-tor (HLI) delivered the ion species listed in table 2 for various physics experiments in the regular beam time schedule as well as for accelerator development. * Corresponding authors GSI SCIENTIFIC REPORT 2012 PHN-SIS18-ACC-02FAIR@GSI 257Two beam time periods in 2012 dedicated to biophys-ics experiments at the SIS under therapy conditions and to biophysics experiments at the UNILAC were provided with 12C2+ ion beams. Table 2: Ion beams delivered from the HLI in 2012. Ion species Auxiliary gas Duration (days) Analyzed intensity(eµA) D21+ - 3 270 12C2+ O2 12 100 12C3+ - 9 150 20Ne4+ He 4 270 40Ar7+ He 2 90 48Ca10+ He 55 120 80Kr13+ He 10 60 136Xe19+ O2 11 30  Ion beams of 20Ne4+ and of 40Ar7+ were exclusively used for machine investigations at the HLI in different periods. This was dedicated to the preparation of forth-coming experiments with a module of a new type of su-perconducting linear accelerator, the sc cw-LINAC-Demonstrator [3]. After investigations on the feasibility of producing a 12C3+-beam from pure CH4 in 2011 the corresponding dedicated physics experiment was performed at the ESR in the present reporting period. Due to the experiment conditions the 12C3+-beam had to be extracted from the ECRIS and had to be accelerated and transported to the injection of the synchrotron (SIS) without passing through a further stripping target. As the only mass-to-charge separation of the ion beam is performed in the analyzing dipole directly behind the ion source, different ion species of the same mass-to-charge ratio - like 12C3+ and 16O4+ in this case - cannot be separated. The amount of beam contamination with O4+ from the residual gas can only be derived indirectly from the mass-to-charge spectrum. It was estimated in the test run to be in the or-der of 8% oxygen as background contamination. The oxygen contamination is expected to be mostly related to residual gas and surface layers. Therefore an operating period of 3 days for precleaning the plasma chamber of the ECRIS was performed before the dedicated beam time. In fact the amount of oxygen contamination at the mass/charge ratio of 4 (12C3+, 16O4+) could be decreased from 11% to 4%. All other ion beams delivered from the ECRIS were produced from highly enriched isotopic materials upon experimental request for rare isotope ion beams. Ion beams of 136Xe19+ were routinely delivered to experi-ments behind the SIS. A gamma spectroscopy experiment requested for the first time an ion beam from the rare isotope 80Kr. 80Kr13+ from the ECRIS had to be selected. As the isotopic enrichment of the sample material was limited to 51.4% it had to be confirmed that a proper separation of the desired isotope peak in the mass-to-charge spectrum can be achieved. As Figure 1 demon-strates a correct setting of the ion beam optics of the low energy beam transport line fulfils this demand. A minor contamination of this peak with 86Kr14+ cannot be avoided, but only amounts to less than 0.7%.    Figure 1: Separation of  80Kr13+ in the mass/charge spec-trum; Kr13+-isotopes in red (mass 80, 82, 83, 84). As last beam time in 2012 a long run with 48Ca10+ was dedicated to experiments of the Super Heavy Element (SHE) programme at TASCA. This run was characterized by a very stable long time behaviour of the ion beam at high intensity. The mass/charge spectrum in figure 2 ex-hibits the very effective optimization on the desired charge state which also leads to a very high efficiency of material processing with an average material consump-tion of less than 200 µg/h.   Figure 2: Mass/charge spectrum of 48Ca. References [1] K. Tinschert, R. Hollinger et al., GSI Scientific Re-port 2011, GSI Report 2012-1, p.283 [2] A. Adonin, R. Hollinger, Challenges of Production of High Current four-fold Bi and Au Beams from Vacuum Arc Ion Sources at GSI Accelerator Facil-ity, Proceedings of ISDEIV12 [3] S. Mickat et al., GSI Scientific Report 2011, GSI Report 2012-1, p. 292. PHN-SIS18-ACC-02 GSI SCIENTIFIC REPORT 2012258 FAIR@GSI

Ion Source Operation at the GSI Accelerator Facility

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Ion Source Operation at the GSI Accelerator Facility

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