Resonance parameter and covariance evaluation for¹⁶O up to 6 MeV

Abstract

Abstract. A resolved resonance evaluation was performed for 16 O in the energy range 0 eV to 6 MeV using the computer code SAMMY resulting in a set of resonance parameters (RPs) that describes well the experimental data used in the evaluation. A RP covariance matrix (RPC) was also generated. The RP were converted to the evaluated nuclear data file format using the R-Matrix Limited format and the compact format was used to represent the RPC. In contrast to the customary use of RP, which are frequently intended for the generation of total, capture, and scattering cross sections only, the present RP evaluation permits the computation of angle dependent cross sections. Furthermore, the RPs are capable of representing the (n, a) cross section from the energy threshold (2.354 MeV) of the (n, a) reaction to 6 MeV. The intent of this paper is to describe the procedures used in the evaluation of the RP and RPC, the use of the RPC in benchmark calculations and to assess the impact of the 16 O nuclear data uncertainties in the calculate dk eff for critical benchmark experiments.

The C12(α,γ)O16deBoer1, Görres2, Wiescher3 et al. 2017Rev. Mod. Phys.19881431View full textAdd to dashboardCite

“…These backgrounds are chiefly the result of (n, n γ) and (n, γ) reactions on the detector materials themselves and nearby beam line components. Level parameters used to calculate the 13 C(α, n) 16 O cross section have been taken from Sayer et al (2002) and Leal et al (2016). time to test theoretical predictions of isospin mixing of T = 1 contributions into the predominately T = 0 state. The main result was the measurement of the ground state γ width of the state as Γ γ0 ≈ 6 meV, about a factor of 2-3 smaller than the accepted value today.…”

Sensitivity of the C13(α,n)O16S factor to

“…No R-matrix fits are performed, as a proper refitting of the data would entail a new global analysis of many different data sets, including those from the 13 C(α, n) 16 O reaction as well as data from the 13 C(α, α) 13 C reaction and 16 O+n reactions. Instead, the best fit parameters of a recent global fit of Leal et al [5] are used. Only the energy, Γ n and C 2 (or Γ α ) of the near threshold state are varied.…”

New perspectives in neutron reaction cross-section evaluation using consistent multichannel modeling methodology: Application to 17O*

“…[13,14]) and Reactors Physics databases (eg. [15]) within the excited compound-system CoM framework reveals conceptual differencies for the three known bound states (see Table 1). On one hand, the neutron channel width does not show up in the Astrophysics database resulting logically in a total width assigned to the total gamma width (proportional to the half-life of the excited state).…”