Examination and experimental constraints of the stellar reaction rate factorNA〈σv〉of the18Ne(

A. Matić

¹

,

P. Mohr

²

Abstract

The18 Ne(α,p) 21 Na reaction is one key for the break-out from the hot CNO-cycles to the rpprocess. Recent papers have provided reaction rate factors NA < σv > which are discrepant by at least one order of magnitude. The compatibility of the latest experimental results is tested, and a partial explanation for the discrepant NA < σv > is given. A new rate factor is derived from the combined analysis of all available data. The new rate factor is located slightly below the higher rate factor by Matic et al. at low temperatures and significantly below at higher temperatures whereas it is about a factor of five higher than the lower rate factor recently published by Salter et al.

Thermonuclear reaction rate ofNe18(α,p)Na21Mohr1, Longland2, Iliadis3 2014Phys. Rev. CSelf Cite2618932View full textAdd to dashboardCite

“…Furthermore, the reverse 21 Na (p,α) 18 Ne reaction has been used in two independent experiments [7,8] to determine a lower limit of the forward 18 Ne(α,p) 21 Na reaction cross section. Mohr and Matic [4] found a dramatic disagreement between the earlier forward 18 Ne(α,p) 21 Na reaction data obtained by Groombridge et al [9] and the reverse reaction data [7,8]. Consequently, the data of Ref.…”

“…These energies define the resonance energies, E, in the 18 Ne(α,p) 21 Na reaction, which enter exponentially into the expression for the reaction rate and are thus the most important ingredient. From the same experiment, total widths Γ of these states were derived [4]. In addition, spins and parities, J π , of several states in 22 Mg have been measured recently by resonant proton scattering using the 21 Na(p,p) 21 Na reaction in inverse kinematics [5,6].…”

“…system unless noted otherwise. The deviations between the simple narrow-resonance formalism and a numerical integration of the cross section σ(E) in N A σv remain below 5 % for T 9 = 1−2 and below 10 % for a wider temperature range of T 9 = 0.25 − 3 [4].Resonance energies are derived from the measured excitation energies [3] by using E = E * − S α , with the α-particle binding energy in the 22 Mg compound nucleus given by S α = 8142.5 ± 0.5 keV [15]. The uncertainty of S α does not significantly affect the uncertainty of the reaction rate.…”

High precision113In(α,α)113In elastic scattering at energies near the Coulomb barrie

“…The predicted σ reac from the global potentials do not deviate by more than 10%-15% from the experimental result at the lowest energy of 15.59 MeV, and the agreement becomes even better with 5%-10% deviation at 18.82 and 40.76 MeV for all potentials under study. An explanation for this relatively good agreement of σ reac from the various potentials is given in [58,63]. As expected, the ATOMKI-V1 potential [9] which is designed for low energies (with a surface imaginary part only; higher energies would require an additional volume term), shows a very poor χ 2 /F at the highest energy.…”

“…The resulting σ reac has typical uncertainties of about 3% at energies around and above the Coulomb barrier if the underlying angular distributions have been measured in a wide angular range with small uncertainties [41]. Larger uncertainties appear at energies significantly below the Coulomb barrier, and the lower limit for the extraction of σ reac is studied in [58]. It should be noted that a straightforward determination of σ reac , using η L from fitting elastic scattering data, is only possible when compound-elastic scattering is negligible [56,57].…”