Indirect determination of neutron capture cross sections on spherical and near-spherical nuclei using the surrogate method

Abstract

The 92 Mo(n,γ) cross section was obtained using both the absolute surrogate approach and surrogate ratio method (SRM), relative to the 94 Mo(n,γ) cross section, in an equivalent neutron energy range of 80 to 890 keV. Excited 93 Mo and 95 Mo nuclei were populated using the 92 Mo(d, p) and 94 Mo(d, p) reactions, respectively. Both discrete and statistical tagging approaches were employed to identify the γ-decay channel and were examined in terms of their sensitivity to the initial angular momentum population distribution. The absolute surrogate 92 Mo(n,γ) cross sections disagree with evaluated neutron capture cross section data by as much as a factor of four, whereas the results obtained using the SRM trend more favorably with the evaluated result. Experimental results suggest that discrete and statistical tagging approaches may sample different contributions of the γ-cascade for near-spherical nuclei. This work represents the first use of the surrogate method in the determination of neutron capture cross sections on spherical and quasi-spherical nuclei in the mass-90 region and provides a possible pathway to extend the SRM to a broader mass range.

Completing the nuclear reaction puzzle of the nucleosynthesis ofMo92

“…[14]). Data constrain the reaction rates of 92 Mo(α, γ) [15], 92 Mo(p, γ) [16][17][18] and 92 Mo(n, γ) 93 Mo [19,20]. The only reaction remaining as a possible source for the 92 Mo puzzle is the dominant destruction reaction 92 Mo(γ, p) 91 Nb.…”