First Measurement of the ¹⁹F(α, p)²²Ne Reaction at Energies of Astrophysical Relevance

Abstract

The observational 19 F abundance in stellar environments systematically exceeds the predicted one, thus representing one of the unsolved challenges for stellar modeling. It is therefore clear that further investigation is needed in this field. In this work, we focus our attention on the measurement of the a p F , Ne 19 22

Nuclear reactions in AGB nucleosynthesis: the19F(α, p)22Ne at energies of astrophysical relevance

“…Dividing the measured three-body triple differential cross-section for KF and |Φ(p s )| 2 it is therefore possible to obtain the twobody one of interest in arbitrary units. Those data were then fitted by means of the Modified R-Matrix procedure [2] and a first evaluation of the widths of the involved resonances has been performed [6,7]. The measured cross-section was then normalized to direct data [9] in the overlap region (0.6÷0.9 MeV in the center-of-mass reference frame), obtaining in the end the absolute units cross-section for the 19 F(α,p) 22 Ne reaction.…”

“…To study the 19 F(α,p) 22 Ne reaction, the THM was applied by using a 6 Li beam (6 MeV energy, 5 enA intensity) and that can be considered as a cluster α ⊕ d, impinging on a 7 LiF target (150 µm thick), with the aim to induce the 6 Li( 19 F,p 22 Ne)d three-body reaction to study the 19 F(α,p) 22 Ne two-body one: in this reaction, the α particle is considered as the participant to the two-body reaction, while the deuteron continues its course undisturbed, and is therefore considered the spectator for the process of interest. Following the THM prescriptions, the beam energy was chosen to measure the 19 F(α,p) 22 Ne cross-section in the energy region of interest for astrophysics.…”

“…1). The necessity to have detectors sensible to the position is given by the fact that one of the three particles in the exit channel of the 6 Li( 19 F,p 22 Ne)d, in this case 22 Ne, is not experimentally detected, but its characteristics are reconstructed form the energies and positions of the two measured ones. About the THM application in this case, in this case the Trojan Horse (TH) nucleus is in the beam and we chose to reveal the spectator (deuterons) along with the light outgoin particle (protons).…”

“…About the THM application in this case, in this case the Trojan Horse (TH) nucleus is in the beam and we chose to reveal the spectator (deuterons) along with the light outgoin particle (protons). This last fact is due to the characteristics of the 22 • ) -where the elastic scattering 6 Li + 19 F (circa 4kHz) would eventually break down the detectors -and at energies (3.5 MeV) that are not high enough to emerge from the target. In order to maximize the statistics on PSD1 and PSD2, it was also decided to tilt the target at 45…”

Neutron-captures in Low Mass Stars and the Early Solar System Record of Short-lived Radioactivities

“…This last was suggested to occur during the recurrent inward extensions of the envelope, known collectively under the name of Third Dredge-up or TDU. Even in absence of a model, it was assumed that at TDU deep mixing phenomena could inject protons into the He-rich layer in concentrations suitable to interact with the abundant 12 C, producing the required 13 C.…”