Measurement of theH2(n,γ)H3reaction cross section between 10 and 550 keV

Abstract

We have measured for the first time the cross section of the $^{2}\mathrm{H}$$(n,\ensuremath{\gamma})$$^{3}\mathrm{H}$ reaction at an energy relevant to big-bang nucleosynthesis by employing a prompt discrete \ensuremath{\gamma}-ray detection method. The outgoing photons have been detected by means of anti-Compton NaI(Tl) spectrometers with a large signal-to-noise ratio. The resulting cross sections are $2.23\ifmmode\pm\else\textpm\fi{}0.34,1.99\ifmmode\pm\else\textpm\fi{}0.25$, and $3.76\ifmmode\pm\else\textpm\fi{}0.41\ensuremath{\mu}$b at ${E}_{n}=30.5,54.2$, and 531 keV, respectively. At ${E}_{n}=30.5$ keV the cross section differs from the value reported previously by a factor of 2. Based on the present data the reaction rate has been obtained for temperatures in the range ${10}^{7}\ensuremath{-}{10}^{10}$ K. The astrophysical impact of the present result is discussed. The obtained cross sections are compared with a theoretical calculation based on the Faddeev approach, which includes meson exchange currents as well as a three-nucleon force.