<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>γ</mml:mi></mml:math>-to-neutron branching ratio for deuterium-tritium fusion determined using high-energy-density plasmas and a fused silica Cherenkov detector
Z. L. Mohamed, Y. Kim, J. P. Knauer, M. S. Rubery
Abstract
A fused silica Cherenkov detector was used to measure deuterium-tritium (DT) gammas during a set of 52 direct-drive cryogenic experiments performed at OMEGA. The detector was calibrated using the 4.4 MeV $\ensuremath{\gamma}$ from the first-excited state of carbon, which is produced when 14-MeV DT neutrons impinge upon a carbon puck. An approximate DT $\ensuremath{\gamma}$ spectrum as well as neutron yields from a standard neutron time-of-flight detector at OMEGA were used to calculate a DT $\ensuremath{\gamma}$-to-neutron branching ratio of $(8.42\ifmmode\pm\else\textpm\fi{}2.84)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$. Assuming an excited-state to ground-state ratio of $2.1:1$, the measurement detailed in this work results in an approximate ground state only $\ensuremath{\gamma}$-to-neutron branching ratio of $2.72\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$. This value is somewhat lower than accelerator-based measurements of the ground-state DT $\ensuremath{\gamma}$ only.