GSI, Darmstadt
HIT, Heidelberg
The Therapy Linac in Heidelberg (HIT) was successfully commissioned in 2006. Required beam parameters were reached except of the beam intensity. The achieved particle transmission for C4+ (design ion) is significantly lower than design. Particle losses are mainly observed in the RFQ. One critical point is the matching section of the RFQ electrodes - Input Radial Matcher (IRM). The original design requires too rigid and narrow beam Twiss-parameters at the RFQ entrance. Also the measured emittance is about twice higher compared to the design. Numerically and experimentally it was proven that the solenoid, used for the beam matching to the RFQ, is not able to provide for the necessary beam size and convergence. As it was shown by beam dynamics simulations using the code DYNAMION, a minor modification of the IRM allows for an improvement of the beam transmission (up to 50%). The proposed measure was realized for an advanced HIT-RFQ-layout, which is recently under test stage. The same modification is already proposed for the linac frontend at Italian Hadrontherapy Center (CNAO, Pavia).
GSI, Darmstadt
TU Darmstadt, Darmstadt
Funding: Work supported by EURATOM (IFE KiT Program).
The recent development in laser acceleration of protons and ions has stimulated ideas for using this concept as innovative and compact therapy accelerator. While currently achieved parameters do not allow a realistic conceptual study yet we find that our simulation studies on ion collimation and transport, based on output data from the PHELIX experiment, already give a useful guidance. Of particular importance are the chromatic and geometric aberrations of the first collimator as interface between the production target and a conventional accelerator structure. We show that the resulting 6D phase space matches well with the requirements for synchrotron injection.