First spectral measurement of deuterium-tritium fusion <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>γ</mml:mi></mml:math> rays in inertial fusion experiments
C. J. Horsfield, M. S. Rubery, J. M. Mack, H. W. Herrmann, Y. Kim, C. S. Young, S. E. Caldwell, Scott Evans, T. Sedillo, A. M. McEvoy, N. M. Hoffman, Michael Huff, J. R. Langenbrunner, G. M. Hale, D. C. Wilson, W. Stoeffl, J. A. Church, Elliot Grafil, E. K. Miller, V. Yu. Glebov
Abstract
The $R$-matrix analysis of $A=5$ nuclear systems has been partially validated by applying the technique to the $^{5}\mathrm{Li}$ system and comparing the predicted $\ensuremath{\gamma}$-ray spectrum with historical data. $R$-matrix analysis of the similar $^{5}\mathrm{He}$ system was then used to predict the $\ensuremath{\gamma}$-ray spectral shape for the deuterium-tritium (DT) reaction. The resulting spectra have been used in the analysis of DT implosions on the Omega laser where the $\ensuremath{\gamma}$-ray interaction rate was measured by a gas Cherenkov detector. Comparison of predictions to experiment confirmed the presence of both 16.75 and $\ensuremath{\approx}13$ MeV $\ensuremath{\gamma}$-ray contributions; analysis, using $R$-matrix spectra, yielded a ratio of $\ensuremath{\gamma}$-ray emission from a transition to the intermediate excited state to that from a transition to the ground state of $(2.1\ifmmode\pm\else\textpm\fi{}0.4):1$, substantiating the first spectral measurement of the DT fusion $\ensuremath{\gamma}$ ray in an inertial fusion environment.