• M. Bousonville
  GSI, Darmstadt
• J. Rausch
  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.

• O.B. Malyshev
  ASTeC, Daresbury
• M.C. Bellachioma, H. Kollmus, A. Krämer, H. Reich-Sprenger
  GSI, Darmstadt
• M. Bender
  LMU, München
• M. Leandersson
  KTH Physics, Stockholm
• E. Hedlund, L. Westerberg
  Uppsala University/Dept. Phys. and Astr., Uppsala
• A. Krasnov
  BINP, Novosibirsk
• B. Zajec
  JSI, Ljubljana

Funding: This work was performed with support from the EUFP6 Program DIRAC-PHASE-1.

Intensity of heavy ion accelerators can be limited by beam induced pressure instability; if pumping is insufficient, pressure will steadily grow reducing the beam lifetime. There is a need of input parameters for vacuum modelling and design of safe UHV systems for updated and new heavy ion accelerators, such as the FAIR facility at GSI, as well as an intention to gain a deeper understanding of the desorption process required an experimental investigation of the ion induced desorption yields (number of released molecules per incident ion) from different materials commonly used in particle accelerators. The experimental data have been obtained with perpendicular incidence beams with an experimental setup based on the throughput method located at the Svedberg laboratory in Uppsala (Sweden). The investigated materials were ¹¹⁶In, Cu, etched Cu, gold coated Cu and Ta and the chosen beams were 5 MeV/u Ar⁸⁺, 9.6 MeV/u Ar⁹⁺ and 17.7 MeV/u Ar¹²⁺. The samples can be biased, which means that the amount of secondary outgoing positive and negative particles during ion bombardment could be investigated. A few samples were also bombarded with grazing incident angle. A summary of the results will be reported.

• A. Plotnikov, E. Floch, E. Mustafin, E. Schubert, T. Seidl, I. Strašík
  GSI, Darmstadt
• A. Smolyakov
  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.

• E. Mustafin, E. Floch, A. Plotnikov, E. Schubert, T. Seidl, I. Strašík
  GSI, Darmstadt
• L.N. Latysheva
  RAS/INR, Moscow
• A. Smolyakov
  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.

• I. Strašík, E. Floch, E. Mustafin, A. Plotnikov, E. Schubert, T. Seidl, A. Smolyakov
  GSI, Darmstadt

Funding: Work is partially supported by project VEGA 1/0129/09.

In the frame of the FAIR project irradiation test of superconducting magnet components was performed at GSI Darmstadt in May 2008. As a part of the experiment stainless steel samples were irradiated by 1 GeV/u ²³⁸U ions. In contrast to the previous experimental studies performed with thick cylindrical samples, the target was a thin plate irradiated at small angle. The target was constituted as a set of individual foils. This stacked-foil target configuration was foreseen for depth-profiling of residual activity. Gamma-ray spectroscopy was used as the main analytical technique. The isotopes with dominating contribution to the residual activity induced in the samples were identified and their contributions were quantified. Depth-profiling of the residual activity of all identified isotopes was performed by measurements of the individual target foils. The characteristic shape of the depth-profiles for the products of target activation and projectile fragments was found and described. Monte Carlo code FLUKA was used for simulations of the residual activity and for estimation of the number of ions delivered to the target and their distribution. The measured data are relevant for assessment of radiation situation at high-energy accelerators during the “hands-on” maintenance as well for assessment of the tolerable beam-losses.

• G.N. Kropachev, A. Aleev, A.D. Fertman, R.P. Kuibeda, T.V. Kulevoy, A.A. Nikitin, S.V. Rogozhkin, A.I. Semennikov
  ITEP, Moscow
• M. Cavenago
  INFN/LNL, Legnaro

Development of new materials for future energy facilities with higher operating efficiency is a challenging and crucial task. However, full-scale testing of radiation hardness of reactor materials is quite sophisticated and difficult as it requires long session of reactor irradiation; moreover, induced radioactivity considerably complicates further investigation. Ion beam irradiation does not have such a drawback, on the contrary, it has certain advantages. One of them is high speed of defect formation. Therefore, it provides a useful tool for modeling of different radiation damages. Improved understanding of material behavior under high dose irradiation will probably allow to simulate reactor irradiation close to real conditions and to make an adequate estimation of material radiation hardness. Since 2008 in ITEP the ion beam irradiation experiments are under development at the ITEP heavy ion RFQ HIP-1. The main objectives of this work are to study primary damage, cascade formation phenomena, phase stability and self-organization under irradiation. This research is carried out by means of tomographic atom probe and transmission electron microscopy. This linac provides accelerated beams of Cu²⁺, Fe²⁺, Cr²⁺ ions with current up to 10 mA and energy 101 keV/n. The first experiments with ion beam at the linac injector demonstrated promising results. The linac output beam line is now under upgrade. The results of beam extraction line adjustment for experiments with reactor materials are presented. The construction of controllable heated target is presented as well.