Thermal neutron capture cross-section to ¹¹³Cd isomer for the study of s-process origin of ¹¹⁵Sn

The astrophysical origin of a p-nucleus ¹¹⁵Sn has remained still an open question. The nucleus ¹¹⁵Sn may be produced by a weak branch of the s-process through a β -unstable isomer in ¹¹³Cd. However, a neutron capture cross-section to this isomer has not been measured with high accuracy at any energy. A neutron capture cross-section for the ¹¹²Cd(n,γ )¹¹³Cd^m reaction has been measured with neutrons provided from a nuclear reactor. The nucleus ¹¹⁵Sn may be produced by a nucleosynthesis flow through ¹¹³Cd^m in the s-process. We have obtained the thermal neutron capture cross-section of 0.028±0.009 [b] and the resonance integral of 1.1±0.3 [b] using a cadmium difference method. The cross-section ratio of the isomer to the ground state has been calculated as a function of the incident neutron energy, E, by using a statistical model. The calculated ratios are almost constant over a wide range of E < 100 keV. We have evaluated the s-process contribution to the solar abundance of ¹¹⁵Sn using the classical steady-flow model. This calculated result has shown that the production through ¹¹³Cdm may be minor contribution to ¹¹⁵Sn.