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Havener, C.C.

Paper Title Page
TPPE019 Laser Ion Source Development for ISOL Systems at RIA 1640
 
  • Y. Liu, C. Baktash, J.R. Beene, H. Z. Bilheux, C.C. Havener, H.F. Krause, D.R. Schultz, D.W. Stracener, C.R. Vane
    ORNL, Oak Ridge, Tennessee
  • K. Brueck, Ch. Geppert, T. Kessler, K. Wendt
    Johannes Gutenberg University Mainz, Mainz
 
  Funding: Managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC05-00OR22725.

The isobaric purity of radioactive ion beams (RIBs) is of crucial importance to many experiments. Laser ion sources based on resonant photoionization have already proved to be of great value at existing ISOL RIB facilities. In these ion sources, ions of a selected isotope are produced by laser radiation via stepwise atomic resonant excitations followed by ionization in the last transition. Because each element has its own unique atomic energy levels, the resonant photoionization process can provide elemental selectivity of nearly 100%. We have initiated a research effort to develop a prototype laser ion source with the potential to achieve the high selectivity and high efficiency required for research with ISOL-generated RIBs at the Rare Isotope Accelerator (RIA). A pilot experiment has been conducted to demonstrate resonant photoionization of three atomic species using all-solid-state tunable Ti:Sapphire lasers. Three Ti:Sapphire lasers were provided by the University of Mainz and used in the experiment for three-photon resonant ionization of the elements. Laser generated Sn, Ni, and Ge ions have been successfully obtained in a hot-cavity laser ion source with overall efficiencies of 22%, 2.7%, and 3.3%, respectively.

 
FPAE053 Isobar Suppression by Photodetachment in a Gas-Filled RF Quadrupole Ion Guide 3250
 
  • Y. Liu, J.R. Beene, C.C. Havener, J. F. Liang
    ORNL, Oak Ridge, Tennessee
  • A.C. Havener
    University of Tennessee, Knoxville, Tennessee
 
  Funding: Managed by UT-Battelle, LLC, for the U.S. DOE under contract DE-AC05-00OR22725. Co-author Aaron Havener was under a U.S. DOE Science Undergraduate Laboratory Internship.

A novel method is described for selective suppression of isobar contaminants in negative radioactive ion beams. Negative ion beams extracted from an ion source were decelerated to low energies and injected into a gas-filled radio-frequency quadrupole (RFQ) ion guide where the ions were cooled and unwanted ions were selectively removed by non-resonant photodetachment with photons of sufficient energy. Simulation studies show that the laser-ion interaction time in a 40 cm long RFQ ion guide can be on the order of milliseconds, thus, high efficiency photodetachment is possible with commercially available CW lasers. There are a number of adjacent-Z species whose negative ions are such that photodetachment can be used to suppress the unwanted negative ion species while leaving the species of interest intact. Examples of particular interest include suppressing the 56Co- component in a mixed 56Ni- + 56Co- beam and the 17O- component in a mixed 17O- + 17F- beam. In a proof–of-principle experiment a CW Nd:YAG laser at 1064 nm wavelength was used to selectively remove Co- ions in the (Ni, Co) pair. With laser power on the order of 3 W, 95% of Co- beams were suppressed while only 10% of Ni- beams were neutralized in a He-filled RFQ guide.