Effects of energy levels on the double-differential cross sections of outgoing charged particles for the n+19F reaction below 20 MeV

Abstract

The double-differential cross sections (DDCS) for $n + ^{19}$F reaction is of critical importance for elucidating the mechanisms of nuclear reaction processes, advancing applications in nuclear engineering and technology, and supporting fundamental research in nuclear astrophysics. The quantitative description of DDCS for emission products presents a persistent theoretical challenge, primarily due to the more intricate effects of energy levels than those of 1p-shell nuclei. The pick-up mechanism of complex particles, as one of the important components of statistical theory for light nuclear reactions (STLN), is improved to describe the DDCS of outgoing charged particles, considering the effect of energy levels with energy, angular momentum and parity conservations. A comprehensive analysis of all open reaction channels is performed for $n + ^{19}$F reaction below 20 MeV. After ensuring the acquisition of high-quality DDCS of the emitted neutrons, the DDCS of outgoing charged particles (including $p, d, t, α$) are self-consistently obtained. The results of this work are not only in good agreement with the recently measured experimental data at $E_n$=14.2 MeV, but also superior to the data recommended by the current major nuclear databases. Thus, LUNF code for $n + ^{19}$F reaction is developed to obtain the ENDF-6 formatted DDCS file of the nucleon and light composite charged particles.