Tables of thermonuclear-reaction-rate data for neutron-induced reactions on heavy nuclei

Abstract

The results of statistical model calculations of ( n, γ), ( n, p), and ( n, α) cross sections and reaction-rate factors are presented in tabular form for over 500 target nuclei in the range 36 ≤ Z ≤ 83 (krypton to bismuth). Included in these tables is information on (i) the reaction cross section as a function of energy for the exoergic channel in the range 0.01 ≤ E(MeV) ≤ 3.0; (ii) the thermally averaged reaction-rate factor, N A 〈 σv〉 and the nuclear partition function G( T) for temperatures in the range 10 8 ≤ T( oK) ≤ 3 × 10 9; (iii) analytic fits to the reaction-rate factors and partition functions as functions of temperature; and (iv) nuclear level-density parameters and formulas for their extrapolation. Two types of reaction-rate factors have been computed. One, which may be called the “laboratory rate factor,” is based on the assumption that the target nuclei occupy only their ground states. The other, which shall be termed the “stellar rate factor,” is based on the more realistic assumption that the target nuclei occupy a thermal distribution of excited states at temperature T. A brief discussion of theory and instructions for usage of the tables are included. New fitting forms for statistical-model thermonuclear reaction rates are presented and justified.