Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Astrophysical Reaction Rates for Charged-Particle Induced Reactions on Proton-Rich Nuclides

Thomas Rauscher

TL;DR

This work delivers updated SMARAGD Hauser-Feshbach reaction-rate calculations for proton-rich nuclides, including both charged-particle and neutron-induced channels, with modern nuclear inputs and detailed sensitivity analyses. It provides online datasets and REACLIB fits for temperatures between $0.1$ and $10$ GK, highlighting improvements over older rate libraries, especially for alpha-induced processes. The authors emphasize careful comparison between theory and data, accounting for excited-state contributions and the distinction between ground-state cross sections and astrophysical rates, and they demonstrate substantial agreement with selected experimental data using state-of-the-art optical potentials such as ATOMKI-V2. These results enhance the reliability of nucleosynthesis modelling in proton-rich environments (e.g., rp-process and related scenarios) and guide future experimental efforts near the driplines.

Abstract

Astrophysical reaction rates for reactions with proton-rich nuclides from stability to the proton dripline were calculated with an updated version of the SMARAGD statistical model (Hauser-Feshbach) code. Here, the focus was on reactions with protons or $α$ particles as required for nucleosynthesis in proton-rich matter. For completeness, also neutron-induced reactions are provided for the same set of targets. Some comments on dependencies of rates on various nuclear properties and on the appropriate way to compare to experiments are given. The new rate set for charged-particle induced reactions provides a better description of experimental data than previously widely used rates, especially for reactions involving $α$ particles.

Astrophysical Reaction Rates for Charged-Particle Induced Reactions on Proton-Rich Nuclides

TL;DR

This work delivers updated SMARAGD Hauser-Feshbach reaction-rate calculations for proton-rich nuclides, including both charged-particle and neutron-induced channels, with modern nuclear inputs and detailed sensitivity analyses. It provides online datasets and REACLIB fits for temperatures between and GK, highlighting improvements over older rate libraries, especially for alpha-induced processes. The authors emphasize careful comparison between theory and data, accounting for excited-state contributions and the distinction between ground-state cross sections and astrophysical rates, and they demonstrate substantial agreement with selected experimental data using state-of-the-art optical potentials such as ATOMKI-V2. These results enhance the reliability of nucleosynthesis modelling in proton-rich environments (e.g., rp-process and related scenarios) and guide future experimental efforts near the driplines.

Abstract

Astrophysical reaction rates for reactions with proton-rich nuclides from stability to the proton dripline were calculated with an updated version of the SMARAGD statistical model (Hauser-Feshbach) code. Here, the focus was on reactions with protons or particles as required for nucleosynthesis in proton-rich matter. For completeness, also neutron-induced reactions are provided for the same set of targets. Some comments on dependencies of rates on various nuclear properties and on the appropriate way to compare to experiments are given. The new rate set for charged-particle induced reactions provides a better description of experimental data than previously widely used rates, especially for reactions involving particles.

Paper Structure

This paper contains 10 sections, 8 equations, 15 figures.

Table of Contents

  1. Introduction
  2. Definition of Astrophysical Reaction Rates
  3. The Statistical Model (Hauser-Feshbach)
  4. Implementation in SMARAGD
  5. Results for charged-particle induced reactions
  6. Comparison to data
  7. Some comments on comparing data to predictions
  8. Comparison to selected experimental data
  9. Comparison to calculations with different treatment of nuclear properties
  10. Summary

Figures (15)

  • Figure 1: Type of reaction width dominating the size of proton-induced astrophysical reaction rates at 3 GK; the dominating width is identified by the colour of the square for the target nuclide. The assignment "unknown" means that the rate is sensitive to more than one width of comparable size. Except for capture reactions, only reactions with positive $Q$ value are shown. This figure was created using the rate sensitivities given in 2012ApJS..201...26R.
  • Figure 2: Same as Figure \ref{['fig:domi_proton']} but for $\alpha$-induced astrophysical reaction rates at 2.5 GK.
  • Figure 3: Same as Figure \ref{['fig:domi_proton']} but for neutron-induced astrophysical reaction rates at 2.5 GK.
  • Figure 4: Same as Figure \ref{['fig:domi_proton']} but for neutron-induced astrophysical reaction rates at 1 GK.
  • Figure 5: Fit quality for proton-induced reactions; shown is the overall deviation of the fit from the actual values within the relevant temperature region (see text for details) by the fill colour of the square identifying the target nuclide. For the (p,$\alpha$) reactions only reactions with positive $Q$ value are shown. Reactions off the neutron-rich side of stability are not included in the rate set presented here.
  • ...and 10 more figures