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5. The HRIBF Cyclotron Replacement Project
[ C. J. Gross & B. A. Tatum]

The HRIBF is proposing to replace the nearly 50-year-old ORIC with a commercial 70-MeV cyclotron that can replace most of the abilities of ORIC as well as bring new features beneficial to RIB production. The new cyclotron provides higher and easily adjustable proton energy. Coupled with higher beam intensity, the new cyclotron would increase the yield of neutron-rich fission fragment beams by at least a factor of 8 and potentially much more through the use of a two-step target. The variable energy deuteron beam allows us to maintain our current (d,n) reactions at low-energy for proton-rich beam production, e.g., 17F. The 70-MeV alpha beam also adequately covers ORIC's beam energy and intensity capabilities while, at the same time, eliminating problems associated with running alphas on ORIC:

  • Mechanical reconfiguration and stresses (rf, ion source, extraction system)
  • Ion source cathode replacement every 24-48 hours of operation
  • Power consumption

Figure 5-1 - A schematic layout of the HRIBF with the proposed location of the new cyclotron.

In addition, a possible dual port extraction capability will allow us to simultaneously extract two beams of deuterons or protons at different energies. One beam can be used for normal RIB production while the other can be used for isotope production such as 7Be which we could use in our batch-mode ion source.

Very large beam intensities are possible with a commercial cyclotron. This ability will allow us to develop two-step targets where neutrons generated on a Be or Ta target could be used to induce fission on a surrounding uranium target. This "cold fission" process will produce more neutron-rich radioactive species than our current proton-induced fission process resulting in orders of magnitude improvement of many of our beams.

A more in-depth discussion of the commercial cyclotron possibilities may be found in two white papers:

The next step will be to develop a proposal based on the above white papers which we hope to submit to DOE this summer.

To summarize:

  • Scientific Benefits
    • Immediate >8x gain in neutron-rich beams from (p,f)
    • Employ (n,f) with n from (p,n) or (d,n) for bigger gains
    • Sample n-rich yields relative to present HRIBF
      • 132Sn x 50, 134Sn x 1100; class="style2" 136Sn x 1900; 133Sn x 8000
      • 82Ge x 460; 84Ge x 1790; 86Ge x 4300; 88Ge x 7300
    • Above yields attainable with only minor upgrades to existing infrastructure
    • Up to 3x more with infrastructure upgrades
    • Maintains and extends existing proton-rich capability
    • Produce long lived isotopes for batch mode operations very economically using dual port proton or deuteron beams
  • Facility/Operational Benefits
    • Fully replaces ORIC and expands on capabilities
    • Commercial accelerator sold for isotope production
    • Batch mode sample or isotope production while producing RIB
    • Much improved reliability (effect on both n-rich and p-rich)
    • Much reduced power cost (~15% of ORIC)
    • Use existing target rooms - no major civil construction
  • Machine specifications
    • Multiple beam capability, variable energy
    • 750 μA proton, variable energy up to 70 MeV
    • >50 μA deuterons, variable energy up to 35 MeV
    • ~50 μA alpha, fixed energy at 70 MeV

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