THO2B  —  Beam Interaction Material & Beam Dynamics in High-Intensity Circular Machines   (30-Sep-10   10:50—12:30)

Chair: E. Métral, CERN, Geneva

Paper Title Page
THO2B01 A New Possibility of Low-Z Gas Stripper for High-Power Uranium Beam Acceleration Alternative to C Foil 600
 
  • H. Okuno, N. Fukunishi, A. Goto, H. Hasebe, O. Kamigaito, M. Kase, H. Kuboki, Y. Yano
    RIKEN Nishina Center, Wako
  • A. Hershcovitch
    BNL, Upton, Long Island, New York
  • H. Imao
    RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama
 
 

Electron stripping process from heavy ion in material is a useful tool in accelerator complex to give higher charge state of the ion, allowing its effective acceleration. This process is competed with electron capture process and reach to the equilibrium charge state. Carbon foils is convenient for charge stripper but have short lifetime due to thermal stress and sputtering. Gas is basically free from lifetime but gives lower charge state due to density effect. Therefore, charge stripper especially for uranium beams at 10-20 MeV/u will be a bottle-neck problem in high power heavy ion facility such as RIBF, FRIB and FAIR. Electron stripping and capture cross section of uranium ion beams in helium gas were measured as a function of their charge state at 11, 14 and 15 MeV/u with expectation that low-Z gas (H2 and He) would provide a better stripping media than nitrogen with a higher charge state. We will show the promising results with discussion about plasma confinement of low-Z gas.

 

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THO2B02 Parametric Study of a Two-Stage Betatron Collimation System for the PS2 605
 
  • J. Barranco, Y. Papaphilippou
    CERN, Geneva
 
 

Beam losses are a potential limiting factor in the performance in any high intensity synchrotron. For the new CERN PS2, an overall low loss design has been adopted. However, it is unavoidable that due to different processes a certain fraction of particles leave the beam core populating the so-called beam halo. A collimation system removes in a controlled way all particles outside the prescribed betatron and collimator acceptances. This article presents a two-stage betatron collimation design as an optical device for different long straight sections layouts. Parametric studies for the different main design parameters are presented and their influence in the expected cleaning efficiency of the system is analyzed and compared to the accepted thresholds of admissible losses. Finally, different errors were introduced in the lattice to test the robustness of the design against realistic operation scenarios.

 

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THO2B03 Operation of the J-PARC Main Ring with the Moderate Beam Power: Predictions and Observations. 610
 
  • A.Y. Molodozhentsev
    KEK, Ibaraki
 
 

From April 2010 the routine operation of the J-PARC Main Ring for the Neutrino experiments has begun, providing the moderate beam power at the maximum energy of 30GeV. The beam intensity delivered to Main Ring from the booster (rapid cycling synchrotron, J-PARC RCS) is about 1.25·1013 protons per bunch, which corresponds to the beam power of 300kW at the energy of 3GeV. The maximum expected beam power from Main Ring for the ‘phass-1’ stage is about 145kW (8 bunches operation, the repetition time is 3.3 sec). To optimize the machine performance, providing minimum particle losses during the injection and acceleration processes, the computational model of the J-PARC Main Ring has been established. In frame of this report the comparison between predictions, based on the corresponding simulations, and measured beam losses for different ‘bare’ tunes is performed. The effects of the linear coupling correction at the moderate beam power are analyzed for the J-PARC Main Ring operation. The predicted and obtained budget of the lost beam for the machine operation with the moderate beam power is presented. The basic scenario for the high beam power operation will be discussed shortly.

 

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THO2B04 Long Term Simulations of the Space Charge and Beam Loss in the SIS18 615
 
  • G. Franchetti, W.B. Bayer, F. Becker, O. Chorniy, P. Forck, T. Giacomini, I. Hofmann, M.M. Kirk, T.S. Mohite, C. Omet, A.S. Parfenova, P. Schütt
    GSI, Darmstadt
 
 

In this contribution we present the simulations of the experiment made in the SIS18 synchrotron on the effect of the space charge in a bunched beam stored for one second. To the simulations a discussion of the underlying dominant effect (trapping or scattering?) is included. A discussion on the consequences of this beam dynamic regime on the SIS100 is presented, open issues and future (experimental and numerical) studies are outlined.

 

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THO2B05 High Intensity Studies on the ISIS Synchrotron, Including Key Factors for Upgrades and the Effects of Half Integer Resonance. 619
 
  • C.M. Warsop, D.J. Adams, I.S.K. Gardner, B. Jones, R.J. Mathieson, S.J. Payne, B.G. Pine, A. Seville, H. V. Smith, J.W.G. Thomason, R.E. Williamson
    STFC/RAL/ISIS, Chilton, Didcot, Oxon
  • C.R. Prior, G.H. Rees
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
 
 

ISIS is the spallation neutron source at Rutherford Appleton Laboratory in the UK. Operation centres on a high intensity proton synchrotron, accelerating 3·1013 ppp from 70-800 MeV, at a rep rate of 50 Hz. Studies are under way looking at many aspects of high intensity behaviour, with a view to increasing operational intensity, identifying optimal upgrade routes and understanding more about fundamental intensity limitations. Present work is assessing the possibility of increasing beam power by raising injection energy into the present ring (~180 MeV), with a new optimised injector. Progress on calculations and simulations for the main high intensity topics is presented, including: space charge and emittance evolution in the transverse and longitudinal planes, beam stability and injection optimisation. Of particular interest is the space charge limit imposed by half integer resonance, for which latest experimental and simulation results are reviewed. Results from measurement and 3D simulation of the present operational machine are also summarised, along with investigations of the observed loss mechanisms. Finally, future plans are outlined.

 

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