The production rates of neutron-rich fission products for the next-generation radioactive beam facility EURISOL are mainly limited by the maximum amount of power deposited by protons in the target. An alternative approach is to use neutron beams to induce fission in actinide targets. This has the advantage of reducing: the energy deposited by the proton beam in the target; contamination from neutron-deficient isobars that would be produced by spallation; and mechanical stress on the target. At ISOLDE CERN, tests have been made on standard ISOLDE actinide targets using fast neutron bunches produced by bombarding thick, high-Z metal converters with 1 and 1.4 GeV proton pulses. This paper reviews the first applications of converters used at ISOLDE. It highlights the different geometries and the techniques used to compare fission yields produced by the proton beam directly on the target with neutron-induced fission. Results from the six targets already tested, namely UC 2 /graphite and ThO 2 targets with tungsten and tantalum converters, are presented.To gain further knowledge for the design of a dedicated target as required by the TARGISOL project, the results are compared to simulations, using the MARS code interfaced with MCNP libraries, of the neutron flux from the converters interacting with the actinide targets. Victoria, B.C. Canada, 6-10 May, 2002 Geneva R. Catherall ** , J. Lettry, S. Gilardoni, U. Köster and the ISOLDE collaboration
Paper presented at the 14th International Conference on Electromagnetic Isotope Separators and Techniques Related to their Application
CERN, CH-1211 Genève 23, Switzerland
AbstractThe production rates of neutron-rich fission products for the next-generation radioactive beam facility EURISOL [1] are mainly limited by the maximum amount of power deposited by protons in the target. An alternative approach is to use neutron beams to induce fission in actinide targets. This has the advantage of reducing: the energy deposited by the proton beam in the target; contamination from neutron-deficient isobars that would be produced by spallation; and mechanical stress on the target. At ISOLDE CERN [2], tests have been made on standard ISOLDE actinide targets using fast neutron bunches produced by bombarding thick, high-Z metal converters with 1 and 1.4 GeV proton pulses.This paper reviews the first applications of converters used at ISOLDE. It highlights the different geometries and the techniques used to compare fission yields produced by the proton beam directly on the target with neutron-induced fission. Results from the six targets already tested, namely UC 2 /graphite and ThO 2 targets with tungsten and tantalum converters, are presented.To gain further knowledge for the design of a dedicated target as required by the TARGISOL project [3], the results are compared to simulations, using the MARS [4][5][6][7] code interfaced with MCNP [8,9] libraries, of the neutron flux from the converters interacting with the actinide targets.