Measurements of 160Dy (p, γ) at Energies Relevant for the Astrophysical γ Process.

Rare information on photodisintegration reactions of nuclei with mass numbers A ≈ 160 at astrophysical conditions impedes our understanding of the origin of p-nuclei. Experimental determination of the key (p, γ) cross sections has been playing an important role in verifying nuclear reaction models and providing rates of relevant (γ, p) reactions in the γ process. In this paper we report the first cross-section measurements of ¹⁶⁰Dy(p, γ)¹⁶¹Ho and ¹⁶¹Dy(p, n)¹⁶¹Ho in the beam energy range of 3.4–7.0 MeV, partially covering the Gamow window. Such determinations are possible by using two targets with various isotopic fractions. The cross-section data can put a strong constraint on the nuclear level densities and gamma strength functions for A ≈ 160 in the Hauser–Feshbach statistical model. Furthermore, we find the best parameters for TALYS that reproduce the available A ∼ 160 data, ¹⁶⁰Dy(p, γ)¹⁶¹Ho and ¹⁶²Er(p, γ)¹⁶³Tm, and recommend the constrained ¹⁶¹Ho(γ, p)¹⁶⁰Dy reaction rates over a wide temperature range for γ process network calculations. Although the determined ¹⁶¹Ho(γ, p) stellar reaction rates at the temperature of 1 to 2 GK can differ by up to one order of magnitude from the NON-SMOKER predictions, it has a minor effect on the yields of ¹⁶⁰Dy and accordingly the p-nuclei, ^156,158Dy. A sensitivity study confirms that the cross section of ¹⁶⁰Dy(p, γ)¹⁶¹Ho is measured precisely enough to predict yields of p nuclei in the γ process. [ABSTRACT FROM AUTHOR]