NIRS, Chiba-shi
Heavy-ion beams have attractive growing interest for cancer treatment owing to their high dose localization at the Bragg peak as well as high biological effect there. Recently, therefore, heavy-ion cancer treatments have been successfully carried out at various facilities and several construction projects for the facility of the heavy-ion therapy have also been progressing in the world, based on the development of accelerator technologies.
GSI, Darmstadt
TU Darmstadt, Darmstadt
In this paper, a method for the generation of RF reference signals for synchrotrons and storage rings will be presented. With these reference signals, the RF cavities in the Facility for Antiproton and Ion Research (FAIR) shall be synchronised. Digital frequency generators that work according to the DDS (direct digital synthesis) principle will be used as reference generators. Via an optical network with star topology, these reference generators will be fed with two clock signals that show a certain correlation of frequency and phase. Due to delay measurements, their phases at different end points of the optical network are known. From these clock signals, reference signals with specific frequencies can be derived. The phases of these reference signals can be fine-tuned against the phases of the clock signals, allowing the phases of different reference signals to be synchronised. With the commercially available DDS generators used in the prototype, phase steps of 0.022° are possible. At a reference signal frequency of 50 MHz, this corresponds to 1.22 ps. The presentation describes the functionality of this method for reference signal generation and shows under which conditions the step size of the phase adjustment can be improved further.
GSI, Darmstadt
ITEP, Moscow
In the frame of the FAIR project in spring 2008 an irradiation test of superconducting magnet components was done at GSI Darmstadt. Cave HHD with the beam dump of SIS18 synchrotron was taken as the test area. The beam dump was reequipped to meet the irradiation test requirements. Thereby the first stage of preparation for the irradiation test was to investigate the radiation field around the reconstructed beam dump from the point of view of radiation safety. FLUKA simulations were performed to estimate the dose rate inside and immediate outside of the cave during the irradiation. The simulations showed safe level of the radiation field, and it was later confirmed by the measurements provided by the radiation safety group of GSI.
GSI, Darmstadt
RAS/INR, Moscow
ITEP, Moscow
In spring 2008 an irradiation test of superconducting magnet components was done at GSI Darmstadt in the frame of the FAIR project. Cave HHD with the beam dump of SIS synchrotron was used for irradiation. The irradiation set-up modeled a scenario of beam loss in a FAIR accelerator: U beam with energy of 1 GeV/u was used to irradiate a thin stainless steel bar at very small angle, so that the test samples situated behind the stainless steel bar were exposed to the beam of secondary particles created in the bar. The total number of U ions dumped on the target assembly was about 2·1014. Presently, in spring 2009 some samples are still radioactive. In the paper we present the estimates of the energy deposition and secondary particle fluences in the test samples and also discuss some results of the irradiation campaign.
Kyoto University/ICR, Kyoto
JINR, Dubna
NIRS, Chiba-shi
Kyoto University/IAE, Kyoto
MPI-K, Heidelberg
Funding: The present work was supported by Advanced Compact Accelerator Development program by MEXT of Japanese Government. Support from Global COE, The Next Generation of Physics, is also greatly appreciated.
Laser cooling for bunched Mg ion beam with the kinetic energy of 40 keV has been applied with S-LSR at ICR, Kyoto University. Up to now, clear peaking of equilibrium momentum spread after laser cooling has been observed at such a synchrotron tune as resonates with the horizontal betatron tune, which is considered to be due to heat transfer from the horizontal degree of freedom to the longitudinal one. In order to demonstrate transverse cooling by observation of reduction of the horizontal beam size, spontaneous emission from laser induced excited state of the Mg ion, has been observed with the use of CCD camera. Some reduction of horizontal beam size has been observed with a certain synchrotron tune, a little bit smaller compared with the fractional part of the horizontal tune.
KIRAMS, Seoul
A magnet lattice of the carbon-ion synchrotron was studied for cancer therapy, which requires maximum 400 MeV/u carbon beam, at KIRAMS. In the study, we optimized the magnet lattice configuration to fit into the therapy purpose. Major requirements for the purpose are (1) long extraction time (about 1 second), (2) compact size, and (3) low cost. For the requirement (1), a slow extraction scheme was adopted by the use of third integer resonance. For (2) and (3), we minimized the circumference as 69.6m and a number of the magnet elements as 16 and 20 for bending magnet and quadrupole magnet, respectively. The study was carried out by the use of a simulation codes for beam particle dynamics and optics. A detail of the conceptual lattice design of the carbon-ion synchrotron is described in the paper.
JINR, Dubna
The stability of an ion beam in synchrotrons with digital filters in the feedback loop of a transverse damper is treated. Solving the characteristic equation allows to calculate the achievable damping rates as a function of instability growth rate, feedback gain and parameters of the signal processing. A transverse feedback system (TFS) is required in synchrotrons to stabilize the high intensity ion beams against transverse instabilities and to damp the beam injection errors. The TFS damper kicker (DK) corrects the transverse momentum of a bunch in proportion to its displacement from the closed orbit at the location of the beam position monitor (BPM). The digital signal processing unit in the feedback loop between BPM and DK ensures a condition to achieve optimal damping. Transverse Feedback Systems commonly use digital FIR (finite impulse response) and IIR (infinite impulse response) filters for the signal processing. A notch filter is required to remove the closed orbit content of the signal and correct for the imperfect electric centre of the BPM. Further processing is required to adjust for the betatron phase advance between the beam pick-up (BPM) and the damper kicker (DK). Damping rates of the feedback systems with digital notch, Hilbert and all-pass filters are analysed in comparison with those in an ideal feedback system.
TU Dresden, Dresden
DREEBIT, Dresden
Siemens AG, Erlangen
Funding: Work supported by the EFRE fund of the EU and by the Freistaat Sachsen (Project Nos. 12321/2000 and 12184/2000) and Siemens AG.
The technical performance of ion sources of the Electron Beam Ion Source (EBIS) type has substantially improved during the last years. This is demonstrated by proof-of-principle experiments which have been done using a room temperature EBIS, a so-called Dresden EBIS-A, which has been in use for several years. A new superconducting EBIS, a so-called Dresden EBIS-SC, has been taken into operation. With the expected higher beam intensities the Dresden EBIS-SC will offer a compact and low-cost solution for applications in particle therapy and will be applicable for synchrotron based solutions (single- or multi-turn injection) as well as other accelerator schemes. It is shown that the introduction of the Dresden EBIS-SC will simplify the injection beam line of medical accelerator facilities.