Isobar Suppression by Photodetachment in a RF Quadrupole Ion Guide
- Physics Division, Oak Ridge National Laboaratory, Oak Ridge, TN 37831 (United States)
- Physikalisches Institut, Universitaet Giessen, 35392 Giessen (Germany)
Ion beam purity is of crucial importance to experimental research in nuclear structure and nuclear astrophysics at the Holifield Radioactive Ion Beam Facility (HRIBF). Mass selected beams are often mixtures of the radioactive isotope of interest and isobaric contaminants that complicate and sometimes compromise experiment. In order to maximize the use of the large radius magnetic mass separator at HRIBF for isobaric purification, the inherent energy spread of injected beams in the 25-MV tandem electrostatic accelerator must be minimized. The development of a negative ion beam cooler based on collisional cooling in a gas-filled RF ion guide has been reported to reduce negative ion beam spreads to a few eV. However, for some systems where magnetic separation is not sufficient, a novel technique based on selective non-resonant laser photodetachment inside the cooler has been developed. The interaction time of the laser radiation with the negative ions dramatically increases in the cooler, substantially increasing the efficiency of the selective photodetachment process. For example, due to a difference in the electron affinities of Co (0.661 eV) and Ni (1.156 eV), 2.5 W Nd:YAG laser radiation at 1.165 eV directed through the cooler achieved 95% suppression of 59Co- ions, while under identical conditions only 10% of 58Ni- ions were neutralized. Improvements in this proof-of-principle experiment and new results for O, F and S, Cl using laser radiation at 2.35 eV, are presented.
- OSTI ID:
- 21032667
- Journal Information:
- AIP Conference Proceedings, Vol. 925, Issue 1; Conference: 11. international symposium on the production and neutralization of negative ions and beams, Santa Fe, NM (United States), 13-15 Sep 2006; Other Information: DOI: 10.1063/1.2773673; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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