• A. Kolomiets, S. Minaev
  ITEP, Moscow
• W. Barth, L.A. Dahl, H. Vormann, S. Yaramyshev
  GSI, Darmstadt

Funding: Work supported by the European Community INTAS Project Ref. no. 06-1000012-8782.
For the operation of the GSI-accelerator chain as an injector for the future FAIR facility a considerable increase of the heavy ion beam intensity by a factor 3-5 at the end of the UNILAC is required. The bottleneck of the whole UNILAC, is the front-end system of the High Current Injector. It is shown that the transverse RFQ-acceptance can be significantly increased while the emittance growth can be reduced. Both goals are achieved with only a moderate change of the RFQ electrode geometry; the intervane voltage raised from 125 kV to 155 kV keeping the design limit of the maximum field at the electrode surface. The changed resonant frequency can be compensated with a relatively small correction of the carrying rings. The beam parameters in the final focusing elements of the LEBT were improved together with the input radial matcher design; the length of the gentle buncher section was considerably increased to provide slow and smooth bunching resulting in a reduce influence of space charge forces. DYNAMION-simulation with the modified electrode design resulted in an increase of U⁴⁺-beam current of up to 20 emA. It is planned to start the upgrade measure in spring 2009.

• M.T. Maier, W. Barth, A. Orzhekhovskaya, B. Schlitt, H. Vormann, S. Yaramyshev
  GSI, Darmstadt
• R. Cee
  HIT, Heidelberg

A clinical facility for cancer therapy using energetic proton and ion beams (C, He and O) has been installed at the Radiologische Universitätsklinik in Heidelberg, Germany. It consists of two ECR ion sources, a 7 MeV/u linac injector, and a 6.5 Tm synchrotron to accelerate the ions to energies of 430 MeV/u. The linac comprises a 400 keV/u RFQ and a 7 MeV/u IH-DTL operating at 216.8 MHz and has been commissioned successfully in 2006. Yet the overall achieved transmission through the injector linac did not exceed 30% due to a mismatch of the beam at the RFQ entrance. Thus a detailed upgrade programme has been started to exchange the RFQ with a new radial matcher design, to correct the alignment and to optimize beam transport to the IH-DTL. The aim is to achieve a sufficient linac transmission above 60%. The new design of the RFQ has been finished in 2007 and the RFQ is currently in production. A test bench comprising a full ion source and LEBT setup to commission the RFQ in 2008 is under construction at Danfysik in Danemark. The current status of this upgrade programme will be reported in this contribution.