Heather Olliver, SUNY Geneseo

Title: Carbon Activation using High Energy Neutrons

Authors: H. Olliver, J. Nyquist, S. Padalino (SUNY Geneseo); S. Lassell, (Ward Reactor Laboratory, Cornell University); R. Bahukutumbi (Laboratory for Laser Energetics, University of Rochester)

Abstract: The Laboratory for Laser Energetics at the University of Rochester has been conducting experiments using laser induced nuclear fusion as a possible alternative energy source. The Ariel density of an inertial confinement fusion (ICF) reaction can be determined by calculating the ratio of the tertiary neutron yield to the primary neutron yield. During an ICF reaction, 14.1 MeV neutrons emitted from the T(d,n) fusion reaction strike fuel deuterons causing them to accelerate. These deuterons then collide with tritium fuel to produce tertiary T(d,n) reactions that produce high energy neutrons in the range of 18 to 30 MeV. A pure carbon sample is placed near the reaction where it becomes activated through the 12C(n,2n)11C reaction which has a high neutron threshold and can not be activated by the primary neutrons. The 11C consequently beta decays by emitting positrons. Once activated, the sample is removed from the reaction area.  High Purity Germanium Detectors or NaI detectors can then count, in coincidence, the back to back 511 keV gamma rays emitted from the positron annihilation.  The number of gamma rays counted is directly related to the tertiary neutron yield of the fusion reaction. The chief concern of using this method arises from contamination of the graphite with materials that will be activated by the primary neutrons, such as copper. These contaminants have been investigated through the use of trace elemental analysis methods at the Cornell Research reactor.

*Funded in part by the Department of Energy