Publications [#329813] of Anton P. Tonchev

Papers Published
  1. Grim, GP; Rundberg, R; Hayes, AC; Jungman, G; Boswell, M; Klein, A; Wilhelmy, J; Tonchev, A; Yeamans, CB, Measurement of reaction-in-ight neutrons using thulium activation at the National Ignition Facility, Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics, vol. 9211 (January, 2014) [doi] .

    © 2014 SPIE. We report on the first observation of tertiary reaction-in-ight (RIF) neutrons produced in compressed deuterium and tritium filled capsules using the National Ignition Facility at Lawrence Livermore National Laboratory, Livermore, CA. RIF neutrons are produced by third-order, out of equilibrium ("in-ight") fusion reactions, initiated by primary fusion products. The rate of RIF reactions is dependent upon the range of the elastically scattered fuel ions and therefore a diagnostic of Coulomb physics within the plasma. At plasma temperatures of∼5 keV, the presence of neutrons with kinetic energies greater than 15 MeV is a unique signature for RIF neutron production. The reaction 169 Tm(n,3n) 167 Tm has a threshold of 15.0 MeV, and a unique decay scheme making it a suitable diagnostic for observing RIF neutrons. RIF neutron production is quantified by the ratio of 167Tm/168Tm observed in a 169 Tm foil, where the reaction 169 Tm(n,2n) 168 Tm samples the primary neutron uence. Averaged over 4 implosions 1-4 at the NIF, the 167 Tm/ 168 Tm ratio is measured to be 1.5± 0.3× 10 -5 , leading to an average ratio of RIF to primary neutron ratio of 1.0± 0.2× 10 -4 . These ratios are consistent with the predictions for charged particle stopping in a quantum degenerate plasma.