Author: Rao, Y.-N.
Paper Title Page
TUPPT011 Measurement of Turn Structure in the Central Region of TRIUMF Cyclotron 177
  • T. Planche, R.A. Baartman, Y.-N. Rao
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  To get the most out of the existing beam diagnostics in the TRIUMF cyclotron, we started in 2011 to developed new data processing and visualization tools. The main advantage of these Matlab-based tools, compared to old VMS-based tools, is that they can benefit from a much larger library of modern data processing and visualization algorithms. This effort has already shown itself very useful to highlight essential features of the beam dynamics which remained unnoticed before. In this paper we present measurements results displaying beam dynamics process, and in particular space charge related process, happening in the central region of the TRIUMF cyclotron.  
poster icon Poster TUPPT011 [32.212 MB]  
TU3PB04 TRIUMF Extraction Foil Developments and Contamination Reduction 269
  • Y.-N. Rao, R.A. Baartman, I.V. Bylinskii, V.A. Verzilov
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  • J.M. Schippers
    PSI, Villigen PSI, Switzerland
  Funding: TRIUMF receives funding via a contribution agreement through the National Research Council of Canada.
We made important developments on the extraction probes and stripping foils at TRIUMF. One of the issues we had was the 7Be contamination being observed near the 1A stripper, and relatedly, stripping foils warped or even broke during use. This was deemed due to over-heating in the foil and the frame. Another issue was related to the beam spills. Beam spills are primarily caused by the large angle scattering from the stripping foil. It was thus suggested that thinner foils be used to minimize the scattering. In view of these 2 issues, improvements were made such that (1) highly-orientated pyrolytic graphite foils, of thickness around 2 mg/cm2, are now used; (2) Tantalum frame is now used in place of the previous stainless steel. These changes, plus additional heat relief features introduced, have resulted in 4 times longer lifetime with the foil, and 5 to 10 times reduction to the tank contamination level around the extraction probe. Also, these improvements have led to significantly reduced amount of beam spill monitor trips. This paper presents these developments and outcomes, including the simulations and calculations performed.
slides icon Slides TU3PB04 [4.798 MB]  
WE3PB02 Improvement of the Current Stability from the TRIUMF Cyclotron 414
  • T. Planche, R.A. Baartman, Y.-N. Rao
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  The νr=3/2 resonance, driven by the third harmonic of the magnetic gradient errors, causes modulation of the radial beam density in the TRIUMF cyclotron. Since extraction is by H- stripping, this modulation induces unwanted fluctuations of the current split between the two high-energy beam lines. To compensate field imperfections, the cyclotron has sets of harmonic correction coils at different radii, each set constituted of 6 pairs of coils placed in a 6-fold symmetrical manner. The 6-fold symmetry of this layout cannot create a third harmonic of arbitrary phase, and so a single set of harmonic coils cannot provide a full correction of third harmonic errors driving the νr=3/2 resonance. However, the outermost two sets of harmonic correction coils are azimuthally displaced. We took advantage of it to achieve a full correction of the resonance. This greatly improved the beam current stability in the high-energy beam lines. To further improve the current stability in the high-energy beam lines, we implemented an active feedback system. This feedback system acts on the amplitude of the first harmonic Bz correction produced by outermost set of harmonic coils.  
slides icon Slides WE3PB02 [1.007 MB]  
WE4PB01 Tracking in a Cyclotron with Geant4 423
  • F.W. Jones, T. Planche, Y.-N. Rao
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
  Building on its precursor GEANT, the tracking and simulation toolkit Geant4 has been conceived and realised in a very general fashion, with much attention given to the modeling of electric and magnetic fields and the accuracy of tracking charged particles through them. As evidenced by the G4Beamline application, Geant4 offers a unique simulation approach to beam lines and accelerators, in a 3D geometry and without some of the limitations posed by conventional optics and tracking codes. Here we apply G4Beamline to the TRIUMF cyclotron, describing the generation and input of the field data, accuracy of closed orbits, stability of multi-turn tracking, tracking accelerated orbits, and phase acceptance. Geant4's 3D visualization tools allow detailed examination of trajectories as well as a particle's-eye view of the acceleration process.  
slides icon Slides WE4PB01 [4.146 MB]