Determination of the Ce 142 (,n) cross section using quasi-monoenergetic Compton backscattered rays
Background: Knowing the energy dependence of the (,n) cross section is mandatory to predict the abundances of heavy elements using astrophysical models. The data can be applied directly or used to constrain the cross section of the inverse (n,) reaction. Purpose: The measurement of the reaction Ce142(,n)141Ce just above the reaction threshold amends the existing experimental database in that mass region for p-process nucleosynthesis and helps to understand the s-process branching at the isotope Ce141. Method: The quasi-monoenergetic photon beam of the High Intensity -ray Source (HIS), TUNL, USA, is used to irradiate naturally composed Ce targets. The reaction yield is determined afterwards with high-resolution -ray spectroscopy. Results: The experimental data are in agreement with previous measurements at higher energies. Since the cross-section prediction of the Ce142(,n) reaction is exclusively sensitive to the -ray strength function, the resulting cross-section values were compared to Hauser-Feshbach calculations using different -ray strength functions. A microscopic description within the framework of the Hartree-Fock-BCS model describes the experimental values well within the measured energy range. Conclusions: The measured data show that the predicted (,n) reaction rate is correct within a factor of 2 even though the closed neutron shell N=82 is approached. This agreement allows us to constrain the (n,) cross section and to improve the understanding of the s-process branching at Ce141. © 2014 American Physical Society.
Sauerwein, A; Sonnabend, K; Fritzsche, M; Glorius, J; Kwan, E; Pietralla, N; Romig, C; Rusev, G; Savran, D; Schnorrenberger, L; Tonchev, AP; Tornow, W; Weller, HR
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