Non-Resonant Alpha-Induced Neutron-Emission: A Multi- Method Comparison Of Nuclear Reaction Rates

TL;DR

This work tackles the need for accurate non-resonant alpha-induced neutron-emission rates in astrophysical environments, notably during the alpha-rich freeze-out in core-collapse supernovae and AGB stars. It combines analytical, Monte Carlo, and a custom Python Monte Carlo approach to compute thermonuclear rates for five $(\alpha,n)$ reactions and validates the results against an open-source rates-mc framework by disabling resonant contributions. The study demonstrates a consistent, rapid rise in $\langle \sigma v \rangle$ with temperature, with strong agreement between numerical methods (Monte Carlo and SciPy quad) and only minor differences at low temperatures due to sampling and integration sensitivity. Overall, the work provides a transparent, Python-based toolkit for calculating non-resonant alpha-induced neutron-emission rates and confirms the reliability of MC-based rate computations for nucleosynthesis modeling.

Abstract

The precise calculation of alpha-induced neutron-emission ($α$,n) reaction rates is fundamental to understanding nucleosynthesis in diverse stellar environments. This study investigates the nuclear reaction rates for various non-resonant alpha-induced neutron-emission reactions by employing analytical, theoretical, and computational methods. We have adopted analytical expressions from existing literature, and for the computational approach, we have implemented the Monte Carlo method. To better understand the functionality and validate the established open-source Monte Carlo scripts, we also developed our own computational code and used it to test various aspects of the method. A comprehensive comparison of the reaction rates from each method is presented by plotting their dependency on temperature.

Figures (5)

• Figure 1: Comparison of experimental and calculated cross sections for the $^{45}$Sc($\alpha,n$)$^{48}$V reaction.
• Figure 2: Comparison of experimental and calculated cross sections for the $^{48}$Ti($\alpha,n$)$^{51}$Cr reaction.
• Figure 3: Comparison of experimental and calculated cross sections for the $^{50}$Cr($\alpha,n$)$^{53}$Fe reaction.
• Figure 4: Comparison of experimental and calculated cross sections for the $^{55}$Mn($\alpha,n$)$^{58}$Co reaction.
• Figure 5: Comparison of experimental and calculated cross sections for the $^{51}$V($\alpha,n$)$^{54}$Mn reaction.