Strength of theF18(p,α)O15

Abstract

Production of the radioisotope 18F in novae is severely constrained by the rate of the 18F(p,alpha)15O reaction. A resonance at E(c.m.)=330 keV may strongly enhance the 18F(p,alpha)15O reaction rate, but its strength has been very uncertain. We have determined the strength of this important resonance by measuring the 18F(p,alpha)15O cross section on and off resonance using a radioactive 18F beam at the ORNL Holifield Radioactive Ion Beam Facility. We find that its resonance strength is 1.48+/-0.46 eV, and that it dominates the 18F(p,alpha)15O reaction rate over a significant range of temperatures characteristic of ONeMg novae.

19Ne levels studied with the18F(d,n)Adekola1, Brune2, Bardayan3 et al. 2012Phys. Rev. CSelf Cite

“…This energy corresponds to the well known state at E x = 7076 keV. In addition to the relatively good agreement in excitation energy, the extracted branching ratio, Γ p /Γ α = 0.64 ± 0.04 is in excellent agreement with the value of 0.639 ± 0.066 determined from previous widths of Γ p = 15.2 ± 1.0 keV and Γ α = 23.8 ± 0.12 keV [12].…”

“…19 Ne levels at E x = 7076 and 6741 keV, respectively [11,12]. Dufour and Descouvemont [13] predict an s-wave state around 1.5 MeV above the proton threshold with decay widths of Γ p = 157 keV and Γ α = 139 keV that such a state has yet to be confirmed supports the need for additional studies of the level structure of 15 O particles.…”

Fusion reactions induced by radioactive beams: the18F(p,α)15O case

“…Several data sets are up-to-now available [5][6][7][8][9][10][11][12][13]. Nevertheless many uncertainties are still present on the lowenergy resonance and its width, thus affecting the determination of the reaction rate at the temperatures relevant for astrophysics and, consequently, the novae nucleosynthesis.…”

First results of Trojan horse method using radioactive ion beams: 18F(p,α) at astrophysical energies

“…In spite of smany attempts to measure this cross section (see e.g. [2,3,4,5,6,7,8,9,10,11,12,14,15,13,16]) the situation is not clear. In order to improve this situation, we performed two experiments aiming at the measurement of the 18 F(p,α) 15 O using two different techniques, the thick target method and the Trojan Horse Method.…”